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+
+Project Gutenberg's A Manual of Elementary Geology, by Charles Lyell
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: A Manual of Elementary Geology
+       or, The Ancient Changes of the Earth and its Inhabitants
+              as Illustrated by Geological Monuments
+
+Author: Charles Lyell
+
+Release Date: November 17, 2010 [EBook #34350]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK A MANUAL OF ELEMENTARY GEOLOGY ***
+
+
+
+
+Produced by Julia Miller, Iris Schr�der-Gehring and the
+Online Distributed Proofreading Team at http://www.pgdp.net
+(This file was produced from images generously made
+available by The Internet Archive/American Libraries.)
+
+
+
+
+
+
+</pre>
+
+
+<span class="pagenum"><a id="pageii"></a>[p.ii]</span>
+<a id="img001" name="img001"></a>
+<div class="figcenter1 width600">
+<img src="images/img001.jpg" width="600" height="242" alt="" title="">
+<p class="smaller">From a Painting by James Hall, <span class="add6em">Esq. Engraved</span> by S. Williams.</p>
+<p class="martop1">STRATA OF RED SANDSTONE, SLIGHTLY INCLINED, RESTING ON VERTICAL SCHIST, AT
+THE SICCAR POINT, BERWICKSHIRE.</p>
+
+<p class="smaller"><span class="smcap">To illustrate unconformable Stratification.</span> See <a href="#page60">page 60.</a></p>
+
+<p class="blq5"><i>"The mind seemed to grow giddy by looking so far into the abyss of time;
+and while we listened with earnestness and admiration to the philosopher
+who was now unfolding to us the order and series of these wonderful events,
+we became sensible how much farther reason may sometimes go than
+imagination can venture to follow."</i>&mdash;<span class="smcap smaller">Playfair</span><span class="smaller">, Biography of Hutton.</span></p></div>
+
+<span class="pagenum"><a id="pageiii"></a>[p.iii]</span><h1 class="lihei2 wosp05">A MANUAL<br>
+<span class="smaller">OF</span><br>
+ELEMENTARY GEOLOGY:</h1>
+<div class="center1">
+<p class="smaller">OR,</p>
+<p class="ftsize115 martop2 lihei2">THE ANCIENT CHANGES OF THE EARTH AND<br>
+ITS INHABITANTS</p>
+<p class="ftsize95">AS ILLUSTRATED BY GEOLOGICAL MONUMENTS.</p>
+<p class="martop3"><span class="smcap ftsize115">by Sir</span> <span class="smcap ftsize115 hweight">CHARLES LYELL</span>, <span class="smcap">M.A. F.R.S.</span></p>
+<p class="ftsize95">AUTHOR OF "PRINCIPLES OF GEOLOGY," "TRAVELS IN NORTH AMERICA,"<br>
+"A SECOND VISIT TO THE UNITED STATES,"<br>
+ETC. ETC.</p>
+</div>
+
+<hr class="martop2">
+
+<p class="smaller">"It is a philosophy which never rests&mdash;its law is progress: a point which
+yesterday was invisible is its goal to-day, and will be its starting post
+to-morrow."</p>
+
+<p class="smaller ralign2"><span class="smcap">Edinburgh Review</span>, No. 132. p. 83. July, 1837.</p>
+<p>&nbsp;</p>
+
+<hr class="martop2">
+
+<div class="center1">
+<p class="ftsize110 martop3"><i>FOURTH AND ENTIRELY REVISED EDITION.</i></p>
+<p class="ftsize95 martop2 hweight">ILLUSTRATED WITH 500 WOODCUTS.</p>
+<p class="ftsize110 lihei1 martop4"><span class="wosp01 lesp01">LONDON:<br>
+JOHN MURRAY, ALBEMARLE STREET.</span><br>
+<span class="smaller">1852.</span></p>
+</div>
+
+<div class="center1 martop4">
+<p><span class="pagenum"><a id="pageiv"></a>[p.iv]</span> <span class="smcap">London</span>:</p>
+<p class="martopm1"><span class="smcap">Spottiswoodes</span> and <span class="smcap">Shaw</span>,<br>
+New-street-Square.</p>
+</div>
+
+
+
+
+<h2><span class="pagenum"><a id="pagev"></a>[p.v]</span>PREFACE TO THE FOURTH EDITION.</h2>
+
+
+<p>In consequence of the rapid sale of the third edition of the "Manual," of
+which 2000 copies were printed in January last, a new edition has been
+called for in less than a twelvemonth. Even in this short interval some new
+facts of unusual importance in pal�ontology have come to light, or have
+been verified for the first time. Instead of introducing these new
+discoveries into the body of the work, which would render them inaccessible
+to the purchasers of the former edition, I have given them in a postscript
+to this Preface (printed and sold separately), and have pointed out at the
+same time their bearing on certain questions of the highest theoretical
+interest.<a name="FNanchor_A_1" id="FNanchor_A_1"></a><a href="#Footnote_A_1" class="fnanchor">[v-A]</a></p>
+
+<p>As on former occasions, I shall take this opportunity of stating that the
+"Manual" is not an epitome of the "Principles of Geology," nor intended as
+introductory to that work. So much confusion has arisen on this subject,
+that it is desirable to explain fully the different ground occupied by the
+two publications. The first five editions of the "Principles" comprised a
+4th book, in which some account was given of systematic geology, and in
+which the principal rocks composing the earth's crust and their organic
+remains were described. In subsequent editions this book was omitted, it
+having been expanded, in 1838, into a separate treatise called the
+"Elements of Geology," first re-edited in 1842, and again recast and
+enlarged in 1851, and entitled "A Manual of Elementary Geology."</p>
+
+<p>Although the subjects of both treatises relate to geology, as their titles
+imply, their scope is very different; the "Principles" containing a view of
+the <i>modern</i> changes of the earth and its inhabitants, while the "Manual"
+relates to the monuments of <i>ancient</i> changes. In separating the one from
+the other, I have endeavoured to render each complete in itself, and
+independent; but if asked by a student which he should read first, I would
+recommend him to begin with the "Principles," as he may then proceed from
+the known to the unknown, and be provided beforehand with a key for
+interpreting the ancient phenomena, whether of the organic or inorganic
+world, by reference to changes now in progress.</p>
+
+<p><span class="pagenum"><a id="pagevi"></a>[p.vi]</span> Owing to the former incorporation of the two subjects in one work,
+and the supposed identity of their subject matter, it may be useful to give
+here a brief abstract of the contents of the "Principles," for the sake of
+comparison.</p>
+
+
+<h3><i>Abstract of the "Principles of Geology," Eighth Edition.</i></h3>
+
+<h4><span class="smcap">Book I.</span></h4>
+
+<ul class="indentm2">
+<li class="martop04">1. Historical sketch of the early progress of geology, chaps. i. to
+iv.</li>
+
+<li class="martop04">2. Circumstances which combined to make the first cultivators of the
+science regard the former course of nature as different from the
+present, and the former changes of the earth's surface as the effects
+of agents different in kind and degree from those now acting, chap. v.</li>
+
+<li class="martop04">3. Whether the former variations in climate established by geology are
+explicable by reference to existing causes, chaps. vi. to viii.</li>
+
+<li class="martop04">4. Theory of the progressive development of organic life in former
+ages, and the introduction of man into the earth, chap. ix.</li>
+
+<li class="martop04">5. Supposed former intensity of aqueous and igneous causes considered,
+chaps. x. and xi.</li>
+
+<li class="martop04">6. How far the older rocks differ in texture from those now forming,
+chap. xii.</li>
+
+<li class="martop04">7. Supposed alternate periods of repose and disorder, chap. xiii.</li>
+</ul>
+
+
+<h4><span class="smcap">Book II.</span></h4>
+
+<h5>CHANGES NOW IN PROGRESS IN THE INORGANIC WORLD.</h5>
+<ul class="indentm2">
+<li class="martop04">8. Aqueous causes now in action: Floods&mdash;Rivers&mdash;Carrying power of
+ice&mdash;Springs and their deposits&mdash;Deltas&mdash;Waste of cliffs and strata
+produced by marine currents: chaps. xiv. to xxii.</li>
+
+<li class="martop04">9. Permanent effects of igneous causes now in operation: Active
+volcanos and earthquakes&mdash;their effects and causes: chaps. xxiii. to
+xxxiii.</li>
+</ul>
+
+
+<h4><span class="smcap">Book III.</span></h4>
+
+<h5>CHANGES OF THE ORGANIC WORLD NOW IN PROGRESS.</h5>
+<ul class="indentm2">
+<li class="martop04">10. Doctrine of the transmutation of species controverted, chaps.
+xxxiv. and xxxv.</li>
+
+<li class="martop04">11. Whether species have a real existence in nature, chaps. xxxvi. and
+xxxvii.</li>
+
+<li class="martop04">12. Laws which regulate the geographical distribution of species,
+chaps. xxxviii. to xl.</li>
+
+<li class="martop04">13. Creation and extinction of species, chaps. xli. to xliv.</li>
+
+<li class="martop04">14. Imbedding of organic bodies, including the remains of man and his
+works, in strata now forming, chaps. xlv. to l.</li>
+
+<li class="martop04">15. Formation of coral reefs, chap. li.</li>
+</ul>
+
+<p>It will be seen on comparing this analysis of the contents of the
+"Principles" with the headings of the chapters of the present work (see <a href="#pagexxiii">p.
+xxiii.</a>), that the two treatises have but little in common; or, to repeat
+what I have said in the Preface to the 8th edition of the "Principles,"
+they have the same kind of connection which Chemistry bears to Natural
+Philosophy, each being subsidiary to the other, and yet admitting of being
+considered as different departments of science.<a name="FNanchor_A_2" id="FNanchor_A_2"></a><a href="#Footnote_A_2" class="fnanchor">[vi-A]</a></p>
+
+<p class="teri martopm1"><span class="smcap">Charles Lyell.</span></p>
+
+<p class="smaller martopm1"><i>11 Harley Street, London, December 10. 1851.</i></p>
+
+
+
+
+<h2><span class="pagenum"><a id="pagevii"></a>[p.vii]</span> POSTSCRIPT.</h2>
+
+<div class="blq1">
+<p class="indentm2">Tracks of a Lower Silurian reptile in Canada &mdash; Chelonian footprints in
+Old Red Sandstone, Morayshire &mdash; Skeleton of a reptile in the same
+formation in Scotland &mdash; Eggs of Batrachians (?) in a lower division of
+the "Old Red," or Devonian &mdash; Footprints of Lower Carboniferous reptiles
+in the United States &mdash; Fossil rain-marks of the Carboniferous period in
+Nova Scotia &mdash; Triassic Mammifer from the Keuper of
+Stuttgart &mdash; Cretaceous Gasteropoda &mdash; Dicotyledonous leaves in Lower
+Cretaceous strata &mdash; Bearing of the recent discoveries above-mentioned
+on the theory of the progressive development of animal life.</p></div>
+
+
+<p><i><span class="smcap">Tracks</span> of a Lower Silurian reptile in Canada.</i>&mdash;In the year 1847, Mr.
+Robert Abraham announced in the Montreal Gazette, of which he was editor,
+that the track of a freshwater tortoise had been observed on the surface of
+a stratum of sandstone in a quarry opened on the banks of the St. Lawrence
+at Beauharnais in Upper Canada. The inhabitants of the parish being
+perfectly familiar with the track of the amphibious mud-turtles or
+terrapins of their country, assured Mr. Abraham that the fossil impressions
+closely resembled those left by the recent species on sand or mud. Having
+satisfied himself of the truth of their report, he was struck with the
+novelty and geological interest of the phenomenon. Imagining the rock to be
+the lowest member of the old red sandstone, he was aware that no traces had
+as yet been found of a reptile in strata of such high antiquity.</p>
+
+<p>He was soon informed by Mr. Logan, at that time engaged in the geological
+survey of Canada, that the white sandstone above Montreal was really much
+older than the "Old Red," or Devonian. It had in fact been ascertained many
+years before, by the State surveyors of New York (who called it the
+"Potsdam Sandstone"), to lie at the base of the whole Silurian series. As
+such it had been pointed out to me in 1841, in the valley of the Mohawk, by
+Mr. James Hall<a name="FNanchor_B_1" id="FNanchor_B_1"></a><a href="#Footnote_B_1" class="fnanchor">[vii-A]</a>, and its position was correctly described by Mr.
+Emmons, on the borders of Lake Champlain, where I examined it in 1842. It
+has there the character of a shallow-water deposit, ripple-marked
+throughout a considerable thickness, and full of a species of Lingula. The
+flat valves of this shell, of a dark colour, are so numerous, and so
+arranged in horizontal layers, as to play the part of mica, causing the
+rock to divide into lamin�, as in some micaceous sandstones.</p>
+
+<p>When I mentioned this rock in my Travels<a name="FNanchor_B_2" id="FNanchor_B_2"></a><a href="#Footnote_B_2" class="fnanchor">[vii-B]</a> as occurring between
+Kingston and Montreal, (the same in which the Chelonian foot-prints have
+since been found,) I spoke of it as the lowest member of the Lower Silurian
+series; but no traces of any organic being of a higher grade than the
+Lingula had then been seen in it, <span class="pagenum"><a id="pageviii"></a>[p.viii]</span>and I called attention to the
+singular fact, that the oldest fossil form then known in the world, was a
+marine shell strictly referable to a genus now existing.</p>
+
+<p>Early in the year 1851, Mr. Logan laid before the Geological Society of
+London a slab of this sandstone from Beauharnais, containing no less than
+twenty-eight foot-prints of the fore and hind feet of a quadruped, and six
+casts in plaster of Paris, exhibiting a continuation of the same trail.
+Each cast contained from twenty-six to twenty-eight impressions with a
+median channel equidistant from the two parallel rows of foot-prints, the
+one made by the feet of the right side, the other by those of the left. In
+these specimens a greater number of successive foot-marks belonging to one
+and the same series were displayed than had ever before been observed in
+any rock ancient or modern. Mr. Abraham has inferred that the breadth of
+the quadruped was from five to seven inches. A detailed account of the
+trail was published by Professor Owen, in April 1851, from which the
+following extracts are made.</p>
+
+<p>"The foot-prints are in pairs, and the pairs extend in two parallel series,
+with a channel exactly midway between the right and left series. The pairs
+of the same side succeed each other at intervals, varying from one inch and
+a half to two inches and a half, the common distance being about two
+inches. The interval between the right and left pairs, measured from the
+inner border of the small prints, is three inches and a half, and from the
+outer border of the exterior or large prints, is seven inches. The shallow
+median track is one inch and a quarter in breadth, varying in depth, but
+not in its relative position to the right and left foot prints."</p>
+
+<p>"The inference to be deduced from these characters is, that the impressions
+were made by a quadruped with the hind feet larger and somewhat wider apart
+than the fore feet, with both hind and fore feet either very short, or
+prevented by some other part of the animal's structure from making long
+steps; and with the limbs of the right side wide apart from those of the
+left; consequently, that the quadruped had a broad trunk in proportion to
+its length, supported on limbs either short, or capable only of short
+steps, and with rounded and stumpy feet, not provided with long claws.
+There are faint traces of a fine reticulate pattern of the cuticle of the
+sole at the bottom of some of the foot-prints on one portion of the
+sandstone; and the surface of the sand is generally smoother there than
+where not impressed, which, with the rising of the sand at the border of
+the prints, indicates the weight of the impressing body. The median groove
+may be interpreted as due either to the abdomen or the tail of the animal;
+but as there is no indication of any bending or movement of a tail from
+side to side, it was probably scooped out of the soft sand by a hard
+breast-plate or plastron. If this were so, it may be inferred that the
+species was a freshwater or estuary tortoise rather than a land
+tortoise."<a name="FNanchor_B_3" id="FNanchor_B_3"></a><a href="#Footnote_B_3" class="fnanchor">[viii-A]</a></p>
+
+<p>Previously to this discovery, the trias was the oldest stratum in <span class="pagenum"><a id="pageix"></a>[p.ix]</span>
+which any remains or signs of a Chelonian had been detected. Numerous other
+trails have since been observed (1850-51) in various localities in Canada,
+all in the same very ancient fossiliferous rock; and Mr. Logan, who has
+visited the spots, will shortly publish a description of the phenomena.</p>
+
+<p><i>Chelonian foot-prints in Old Red Sandstone, Morayshire.</i>&mdash;Captain Lambart
+Brickenden has just communicated to the Geological Society of London a
+drawing and description of a continuous series of no less than thirty-four
+foot-prints of a quadruped observed in the course of last year (1850), on a
+slab of sandstone quarried at Cummingstone, near Elgin, in Morayshire, a
+rock which has always been considered as an upper member of the Devonian or
+"Old Red."<a name="FNanchor_B_4" id="FNanchor_B_4"></a><a href="#Footnote_B_4" class="fnanchor">[ix-A]</a> A part of the track, the course of which was from <span class="smcap">A</span> to <span class="smcap">B</span>,
+is represented in the annexed woodcut, <a href="#img002">fig. 521.</a> The foot-prints are in
+pairs, forming two parallel rows, which are somewhat less distant from each
+other than those of the Lower Silurian tortoise of Canada above mentioned.
+The stride, on the other hand, is four inches, or twice that of the
+Beauharnais Chelonian. The hind foot is exactly of the same size, being one
+inch in diameter, and larger than the fore foot in the proportion of four
+to three.</p>
+
+<a id="img002" name="img002"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 521.</p>
+<img src="images/img002.jpg" width="500" height="196" alt="" title="">
+<p>Scale one-sixth the original size.</p>
+<p class="martopm1">Part of the trail of a (Chelonian?) quadruped from the Old Red Sandstone of
+Cummingstone, near Elgin, Morayshire.&mdash;Captain Brickenden.</p></div>
+
+<p><i>Skeleton of a reptile, allied to the Batrachians, in the Old Red Sandstone
+of Morayshire.</i>&mdash;Mr. Patrick Duff, author of a "Sketch of the Geology of
+Morayshire" (Elgin, 1842), obtained recently (October, 1851), from the rock
+above alluded to, the first example ever seen of the skeleton of a reptile
+in the Old Red Sandstone. He has kindly allowed me to give a figure of this
+fossil, of which Dr. Mantell has drawn up a detailed osteological account
+for publication in the "Journal of the Geological Society of London." The
+bones in this specimen have decomposed, but the natural position of almost
+all of them can be seen, and nearly perfect casts of their form taken from
+the hollow moulds which they have left. <span class="pagenum"><a id="pagex"></a>[p.x]</span>The matrix is a
+fine-grained, whitish sandstone, with a cement of carbonate of lime. The
+skeleton exhibits the general characters of the Lacertians, blended with
+peculiarities that are Batrachian. Hence Dr. Mantell infers that this
+reptile was either a freshwater Batrachian, resembling the Triton, or a
+small terrestrial Lizard. Slight indications are visible of very minute
+conical teeth. Captain Brickenden, who is well acquainted with the geology
+of that part of Scotland, informs me that this fossil was found in the Hill
+of Spynie, north of the town of Elgin, in a rock quarried for building, and
+the same in which the Chelonian foot-prints, alluded to in the last page,
+occur. The skeleton is about four and a half inches in length, but part of
+the tail is concealed in the rock. Dr. Mantell has proposed for it the
+generic name of Telerpeton, from &#964;&#951;&#955;&#949;, afar off, and
+&#7953;&#961;&#960;&#949;&#964;&#959;&#957;, a reptile; while the specific name Elginense commemorates the
+principal place near which it was obtained.</p>
+
+<a id="img003" name="img003"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 522.</p>
+<img src="images/img003.jpg" width="251" height="600" alt="" title="">
+<p>Natural size. <i>Telerpeton Elginense</i><span class="wosp05">. (Mantell.)</span></p>
+<p class="martopm1">Reptile of Old Red Sandstone, from near Elgin, Morayshire.</p></div>
+
+<p><i>Eggs of Batrachians (?) in the Old Red Sandstone of Scotland.</i>&mdash;At <a href="#page344">page
+344.</a> of this work I have given two figures (<a href="#img376">figs. 397</a> and <a href="#img377">398</a>.) of small
+groups of eggs, very common in the shales and sandstones of the "Old Red"
+of Kincardineshire, Forfarshire, and Fife. I threw out as a conjecture,
+that they might belong to gasteropodous mollusca, like those represented in
+<a href="#img378">fig. 399.</a> <a href="#page345">p. 345.</a>; but Dr. Mantell, some years ago, showed me a small
+bundle of the dried-up eggs of the common English frog (see <a href="#img005">fig. 524 <i>a</i>.</a>),
+black and carbonaceous, and so identical in appearance with the fossils in
+question, that he suggested the probability of these last being of
+Batrachian origin. The plants by which they are often accompanied (<a href="#img377">fig.
+398.</a> <a href="#page344">p. 344.</a>), I formerly supposed to be Fuci, but Mr. Bunbury tells me
+that their grass-like form agrees well with the idea of their being
+freshwater, and of the family Fluviales.</p>
+
+<p>The absence of all shells, so far as our researches have yet gone, in the
+slates and sandstones of Scotland above alluded to, raises a presumption
+against their marine origin, and a still stronger one against the fossil
+eggs being those of Gasteropoda. It is well known <span class="pagenum"><a id="pagexi"></a>[p.xi]</span>that a single
+female of the Batrachian tribe ejects annually an astonishing quantity of
+spawn. Mr. Newport, author of many accurate researches into the
+metamorphoses of the Amphibia, having examined my fossils from Forfarshire,
+concurs in Dr. Mantell's opinion that the clusters of eggs (<a href="#img376">figs. 397.</a> <a href="#img377">398.</a>
+<a href="#page344">p. 344.</a>) may be those of frogs; while other larger ones, occurring singly
+or in pairs in the same slates, and often attached to a leaf, may be the
+ova of a gigantic Triton or Salamander. (See <a href="#img004">figs. 523</a>, <a href="#img005">524</a>, <a href="#img006">525.</a>) I may
+observe that the subdivision of the Old Red Sandstone, in which these
+plants and ova occur (No. 4. of the section, <a href="#img067">fig. 62.</a> <a href="#page48">p. 48.</a>), is
+considerably lower in position than the rock in which the Telerpeton of
+Elgin is imbedded.</p>
+
+<a id="img004" name="img004"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 523. Fossil.&mdash;Old Red.</p>
+<img src="images/img004.jpg" width="300" height="256" alt="" title="">
+<p>Fig. 523. Slab of Old Red Sandstone, Forfarshire, with eggs of Batrachians.</p>
+<ul class="smaller martopm05 leftal">
+<li><i>a.</i> Ova in a carbonized state.</li>
+<li><i>b.</i> Egg cells; the ova shed.</li>
+</ul></div>
+
+<a id="img005" name="img005"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 524. Recent.</p>
+<img src="images/img005.jpg" width="251" height="300" alt="" title="">
+<p>Fig. 524. Eggs of the common frog, <i>Rana temporaria</i>, in a carbonized
+state, from a dried-up pond in Clapham Common.</p>
+<ul class="smaller martopm05 leftal">
+<li><i>a.</i> The ova.</li>
+<li><i>b.</i> A transverse section of the mass exhibiting the form of the egg-cells.</li>
+</ul></div>
+
+<a id="img006" name="img006"></a>
+<div class="floatright smaller width400">
+<p>Fig. 525. Eggs of Batrachians.&mdash;Old Red Sandstone.</p>
+<img src="images/img006.jpg" width="400" height="245" alt="" title="">
+<p>Fig. 525. Shale of Old Red Sandstone, or Devonian, Forfarshire, with
+impression of plants and eggs of Batrachians.</p>
+<ul class="smaller martopm05 leftal">
+<li><i>a.</i> Two pair of ova resembling those
+large Salamanders or Tritons on the same leaf.</li>
+<li><i>b b.</i> Detached ova.</li>
+<li><i>c.</i> Egg-cells of frogs or <i>Ranina</i>.</li>
+</ul></div>
+
+<p class="nofloat"><i>Foot-prints of Lower Carboniferous reptiles in the United States.</i>&mdash;I have
+stated, at <a href="#page340">p. 340.</a>, that in 1849, Mr. Isaac Lea observed the foot-marks of
+a large reptile in the lowest beds of the coal formation at Pottsville,
+about seventy miles N.E. of Philadelphia. These researches have since been
+carried farther by Professor H. D. Rogers, in the same region of
+anthracitic coal, lying on the eastern flank of the Alleghany Mountains.
+Beneath the productive coal-measures of that country occurs a dense mass of
+red shales and sandstones, which correspond nearly in position to the
+millstone grit and Mountain Limestone of the south-east of England. In
+these beds foot-prints, referred to three species of quadrupeds, have
+lately been detected, all of them five-toed and in double rows, with an
+opposite symmetry, as if made by right and left feet, while they likewise
+display the alternation of fore foot and hind foot. One species, the
+largest of the three, presents a diameter for each foot-print of about two
+inches, and shows the fore and hind feet to be nearly equal in dimensions.
+It exhibits a length of stride of about nine inches, and a breadth between
+the right and left treads of nearly four inches. The impressions of the
+hind feet are but little in the rear of <span class="pagenum"><a id="pagexii"></a>[p.xii]</span>the fore feet. The animal
+which made them is supposed to have been allied to a Saurian, rather than
+to a Batrachian or Chelonian; but more information is required before so
+difficult a point can be decided. With these foot-marks were seen shrinkage
+cracks, such as are caused by the sun's heat in mud, and rain-spots, with
+the signs of the trickling of water on a wet, sandy beach; all confirming
+the conclusion derived from the foot-prints, that the quadrupeds belonged
+to air-breathers, and not to aquatic races.<a name="FNanchor_B_5" id="FNanchor_B_5"></a><a href="#Footnote_B_5" class="fnanchor">[xii-A]</a> The Cheirotherian
+foot-prints, figured by me at <a href="#page338">p. 338.</a>, in which the fore and hind feet are
+very unequal in size, betoken a distinct genus, and occur in the midst of
+the productive coal measures, being consequently less ancient.</p>
+
+<p><i>On Fossil Rain-marks of the Carboniferous Period in North
+America.</i>&mdash;Having alluded to the spots left by rain on the surface of
+carboniferous strata in the Alleghanies, on which quadrupedal foot-prints
+are seen, I may mention that similar rain-prints are conspicuous in the
+coal measures of Cape Breton, in Nova Scotia, in which Mr. Richard Brown
+has described Stigmari� and erect trunks of trees, and where there are
+proofs, as stated at <a href="#page324">p. 324.</a>, of many fossil forests ranged one above the
+other. In such a region, if anywhere, might we expect to detect evidence of
+the fall of rain on a sea-beach, so repeatedly must the conditions of the
+same area have oscillated between land and sea. The intercalation of
+deposits, containing shells of marine or brackish water, indicate the
+constant proximity of a body of salt water when the clays which supported
+the upright trees were formed. In the course of 1851, Mr. Brown had the
+kindness to send me some greenish slates from Sydney, Cape Breton, on which
+are imprinted very delicate impressions of rain-drops, with several
+worm-tracks (<i>a</i>, <i>b</i>, <a href="#img007">fig. 526.</a>), such as usually accompany rain-marks on
+the recent mud of the Bay of Fundy, and other modern beaches.<a name="FNanchor_B_6" id="FNanchor_B_6"></a><a href="#Footnote_B_6" class="fnanchor">[xii-B]</a></p>
+
+<a id="img007" name="img007"></a>
+<div class="figcenter smaller width500">
+<img src="images/img007.jpg" width="500" height="291" alt="" title="">
+<p>Fig. 526. Carboniferous rain-prints with worm-tracks (<i>a</i>,
+<i>b</i>) on green shale, from Cape Breton, Nova Scotia.</p>
+<p>Fig. 527. Casts of rain-prints on a portion of the same
+slab, No. 526. seen on the under side of an incumbent layer of arenaceous
+shale.</p>
+<p class="martopm1">The arrow represents the direction of the shower.</p></div>
+
+<span class="pagenum"><a id="pagexiii"></a>[p.xiii]</span><a id="img009" name="img009"></a>
+<div class="figcenter1 smaller width500">
+<p class="martop2">Fig. 528.</p>
+<img src="images/img009.jpg" width="500" height="243" alt="" title="">
+<p>Fig. 528. Casts of carboniferous rain-prints and
+shrinkage-cracks, (<i>a</i>) on the under side of a layer of sandstone, Cape
+Breton, Nova Scotia.</p></div>
+
+<p>The casts of rain-prints, in <a href="#img007">figs. 527.</a> and <a href="#img009">528.</a>, project from the under
+side of two layers, occurring at different levels, the one a sandy shale,
+resting on the green shale (<a href="#img007">fig. 526.</a>), the other a sandstone presenting a
+similar warty or blistered surface, on which are also observable some small
+ridges as at <i>a</i>, which stand out in relief, and afford evidence of cracks
+formed by the shrinkage of subjacent clay, on which rain had fallen. Many
+of the associated sandstones are described by Mr. Brown as ripple-marked.</p>
+
+<p>The great humidity of the climate of the coal period had been previously
+inferred from the nature of its vegetation and the continuity of its
+forests for hundreds of miles; but it is satisfactory to have at length
+obtained such positive proofs of showers of rain, the drops of which
+resembled in their average size those which now fall from the clouds. From
+such data we may presume that the atmosphere of the carboniferous period
+corresponded in density with that now investing the globe, and that
+different currents of air varied then as now, in temperature, so as to give
+rise, by their mixture, to the condensation of aqueous vapour.</p>
+
+<p><i>Triassic Mammifer (Microlestes antiquus Plieninger.)</i>&mdash;In the year 1847,
+Professor Plieninger, of Stuttgart, published a description of two fossil
+molar teeth, referred by him to a warm-blooded quadruped<a name="FNanchor_B_7" id="FNanchor_B_7"></a><a href="#Footnote_B_7" class="fnanchor">[xiii-A]</a>, which he
+obtained from a bone-breccia in W�rtemberg occurring between the lias and
+the keuper. As the announcement of so novel a fact has never met with the
+attention it deserved, we are indebted to Dr. J�ger, of Stuttgart, for
+having recently reminded us of it in his Memoir on the Fossil Mammalia of
+W�rtemberg.<a name="FNanchor_B_8" id="FNanchor_B_8"></a><a href="#Footnote_B_8" class="fnanchor">[xiii-B]</a></p>
+
+<p><a href="#img010">Fig. 529.</a> represents the tooth first found, taken from the plate published
+in 1847, by Professor Plieninger; and <a href="#img011">fig. 530.</a> is a drawing of the same
+executed from the original by Mr. Hermann von Meyer, <span class="pagenum"><a id="pagexiv"></a>[p.xiv]</span>which he has
+been kind enough to send me. <a href="#img010">Fig. 529.</a> is a second and larger molar, copied
+from Dr. J�ger's plate lxxi., fig. 15.</p>
+
+<a id="img010" name="img010"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 529.</p>
+<img src="images/img010.jpg" width="450" height="129" alt="" title="">
+<p><i>Microlestes antiquus</i>, Plieninger. Molar tooth
+magnified. Upper Trias, Diegerloch, near Stuttgart, W�rtemberg.</p>
+<ul class="smaller martopm05 leftal">
+<li><i>a.</i> View of inner side?</li>
+<li><i>b.</i> same, outer side?</li>
+<li><i>c.</i> Same in profile.</li>
+<li><i>d.</i> Crown of same.</li>
+</ul></div>
+
+<a id="img011" name="img011"></a>
+<div class="figcenter smaller width200">
+<p class="martop2">Fig. 530.</p>
+<img src="images/img011.jpg" width="129" height="150" alt="" title="">
+<p><i>Microlestes antiquus</i>, Plien.</p>
+<p class="martopm1">View of same molar as <a href="#img010">No. 529.</a> From a drawing by Herman von Meyer.</p>
+<ul class="smaller martopm05 leftal">
+<li><i>a.</i> View of inner side?</li>
+<li><i>b.</i> Crown of same.</li>
+</ul></div>
+
+<a id="img012" name="img012"></a>
+<div class="floatleft smaller width112">
+<p> Fig. 531.</p>
+<img src="images/img012.jpg" width="114" height="150" alt="" title="">
+<p>Molar of <i>Microlestes</i>? Plien. 4 times as large as
+<a href="#img010">fig. 529.</a> From the trias of Diegerloch, Stuttgart.</p></div>
+
+<p>Professor Plieninger inferred in 1847, from the double fangs of this tooth
+and their unequal size, and from the form and number of the protuberances
+or cusps on the flat crowns, that it was the molar of a Mammifer; and
+considering it as predaceous, probably insectivorous, he called it
+Microlestes, from &#956;&#953;&#954;&#961;&#959;&#962;, little, and &#955;&#951;&#963;&#964;&#951;&#962;, a beast of
+prey. Soon afterwards, he found the second tooth also, at the same
+locality, Diegerloch, about two miles to the south-east of Stuttgart. Some
+of its cusps are broken, but there seem to have been six of them
+originally. From its agreement in general characters, it is supposed by
+Professor Plieninger to be referable to the same animal, but as it is four
+times as big, it may perhaps have belonged to another allied species. This
+molar is attached to the matrix consisting of sandstone, whereas the tooth,
+No. 529., is isolated. Several fragments of bone, differing in structure
+from that of the associated saurians and fish, and believed to be
+mammiferous, were imbedded near them in the same rock.</p>
+
+<p>Mr. Waterhouse, of the British Museum, after studying the annexed <a href="#img010">figs.
+529.</a> <a href="#img012">531.</a> and the descriptions of Prof. Plieninger, observes, that not only
+the double roots of the teeth and their crowns presenting several cusps,
+resemble those of Mammalia, but the cingulum also, or ridge surrounding the
+base of that part of the body of the tooth which was exposed or above the
+gum, is a character distinguishing them from fish and reptiles. "The
+arrangement of the six cusps or tubercles in two rows, in <a href="#img010">fig. 529.</a>, with a
+groove or depression between them and the oblong form of the tooth, lead
+him, he says, to regard it as a molar of the lower jaw. Both the teeth
+differ from those of the Stonesfield Mammalia<a name="FNanchor_B_9" id="FNanchor_B_9"></a><a href="#Footnote_B_9" class="fnanchor">[xiv-A]</a>, but do not supply
+sufficient data for determining to what order they belonged. Even in regard
+to the Stonesfield jaws, where we possess so much ampler materials, we
+cannot safely pronounce on the order."</p>
+
+<p><span class="pagenum"><a id="pagexv"></a>[p.xv]</span>Professor Plieninger has sent me a cast of the smaller tooth, which
+exhibits well the characteristic mammalian test, the double fang; but Mr.
+Owen, to whom I have shown it, is not able to recognize its affinity with
+any mammalian type, recent or extinct, known to him.</p>
+
+<p>It has already been stated that the stratum in which the above-mentioned
+fossils occur is intermediate between the lias and the uppermost member of
+the trias. That it is really triassic may be deduced from the following
+considerations. In W�rtemberg there are two "bone-beds," one of great
+extent, and very rich in the remains of fish and reptiles, which intervenes
+between the muschelkalk and keuper, the other, containing the Microlestes,
+less extensive and fossiliferous, which rests on the keuper, or superior
+member of the trias, and is covered by the sandstone of the lias. The
+last-mentioned breccia therefore occupies the same place as the well-known
+English "bone-bed" of Axmouth and Aust-cliff near Bristol, which is
+shown<a name="FNanchor_B_10" id="FNanchor_B_10"></a><a href="#Footnote_B_10" class="fnanchor">[xv-A]</a> to include characteristic species of muschelkalk fish, of the
+genus Saurichthys, Hybodus, and Gyrolepis. In both the W�rtemberg bone-beds
+these three genera are also found, and one of the <i>species</i>, Saurichthys
+Mougeotii, is common to both the lower and upper breccias, as is also a
+remarkable reptile called Nothosaurus mirabilis. The Saurian called Belodon
+by H. Von Meyer of the Thecodont family, is another Triassic form,
+associated at Diegerloch with Microlestes.</p>
+
+<p>Previous to this discovery of Professor Plieninger, the most ancient of
+known fossil Mammalia were those of the Stonesfield slate, a subdivision of
+the Lower Oolite<a name="FNanchor_B_11" id="FNanchor_B_11"></a><a href="#Footnote_B_11" class="fnanchor">[xv-B]</a> no representative of this class having as yet been
+met with in the Fuller's earth, or inferior Oolite (see Table, <a href="#page258">p. 258.</a>),
+nor in any member of the lias.</p>
+
+<p><i>Thecodont Saurians.</i>&mdash;This family of reptiles is common to the Trias and
+Permian groups in Germany, and the geologists employed in the government
+survey of Great Britain have come to the conclusion, that the rock
+containing the two species alluded to at <a href="#page306">p. 306.</a>, and of which the teeth
+are represented in <a href="#img332">figs. 348</a>, <a href="#img333">349.</a>, ought rather to be referred to the
+Trias than to the Permian group.</p>
+
+
+<h3>CRETACEOUS GASTEROPODA.</h3>
+
+<p>In speaking of the chalk of Faxoe in Denmark (<a href="#page210">p. 210.</a>) or the highest
+member of the Cretaceous series, I have remarked that it is characterized
+by univalve Mollusca, both spiral and patelliform, which are wanting or
+rare in the white chalk of Europe. This last statement requires, I find,
+some modification. It holds true in regard to certain forms, such as Cypr�a
+and Oliva, found at Faxoe; but M. A. d'Orbigny enumerates 24 species of
+Gasteropoda from the white chalk (Terrain S�nonien) of France alone. The
+same author describes 134 French species of Gasteropoda from the chloritic
+chalk marl and upper greensand (Turonien), 77 from the gault, and 90 from
+the lower greensand (Neocomien), in all 325 species of Gasteropoda,
+<span class="pagenum"><a id="pagexvi"></a>[p.xvi]</span>from the cretaceous group below the Maestricht beds. Among these
+he refers 1 to the genus Mitra, 17 to Fusus, 17 to Trochus, 4 to
+Emarginula, and 36 to Cerithium. Notwithstanding, therefore, the
+peculiarity of the chambered univalves of various genera, so abundant in
+the chalk, the Mollusca of the period approximate in character to the
+tertiary and recent Fauna far more than was formerly supposed.</p>
+
+
+<h3>DICOTYLEDONOUS LEAVES IN LOWER CRETACEOUS STRATA.</h3>
+
+<p>M. Adolphe Brongniart when founding his classification of the fossiliferous
+strata in reference to their imbedded fossil plants, has placed the
+cretaceous group in the same division with the tertiary, that is to say, in
+his "Age of Angiosperms."<a name="FNanchor_B_12" id="FNanchor_B_12"></a><a href="#Footnote_B_12" class="fnanchor">[xvi-A]</a> This arrangement is based on the fact,
+that the cretaceous plants display a transition character from the
+vegetation of the secondary to that of the tertiary periods. Conifer� and
+Cycade� still flourished as in the preceding oolitic and triassic epochs;
+but with these fossils, some well-marked leaves of dicotyledonous trees
+referred to several species of the genus Credneria, had been found in
+Germany in the Quadersandstein and Pl�ner-kalk. Still more recently, Dr.
+Debey of Aix-la-Chapelle has met with a great variety of other leaves of
+dicotyledonous plants in the cretaceous flora<a name="FNanchor_B_13" id="FNanchor_B_13"></a><a href="#Footnote_B_13" class="fnanchor">[xvi-B],</a> of which he
+enumerates no less than 26 species, some of the leaves being from four to
+six inches in length, and in a beautiful state of preservation. In the
+absence of the organs of fructification and of fossil fruits, the number of
+species may be exaggerated; but we may nevertheless affirm, reasoning from
+our present data, that in the lower chalk of Aix-la-Chapelle,
+Dicotyledonous Angiosperms flourished nearly in equal proportions with
+Gymnosperms; a fact of great significance, as some geologists had wished to
+connect the rarity of dicotyledonous trees with a peculiarity in the state
+of the atmosphere in the earlier ages of the planet, imagining that a
+denser air and noxious gases, especially carbonic acid in excess, were
+adverse to the prevalence, not only of the quick-breathing classes of
+animals, (mammalia and birds,) but to a flora like that now existing, while
+it favoured the predominance of reptile life, and a cryptogamic and
+gymnospermous flora. The co-existence, therefore, of dicotyledonous
+angiosperms in abundance with Cycads and Conifer�, and with a rich
+reptilian fauna comprising the Iguanodon, Ichthyosaurus, Pliosaurus, and
+Pterodactyl, in the lower cretaceous series tends, like the oolitic
+mammalia of Stonesfield and Stuttgart, and the triassic birds of
+Connecticut, to dispel the idea of a meteorological state of things in the
+secondary periods widely distinct from that now prevailing.</p>
+
+<p><i>General remarks.</i>&mdash;In the preliminary chapters of "The Principles of
+Geology," in the first and subsequent editions, I have considered the
+question, how far the changes of the earth's crust in past times confirm or
+invalidate the popular hypothesis of a gradual improvement <span class="pagenum"><a id="pagexvii"></a>[p.xvii]</span>in
+the habitable condition of the planet, accompanied by a contemporaneous
+development and progression in organic life. It had long been a favourite
+theory, that in the earlier ages to which we can carry back our geological
+researches, the earth was shaken by more frequent and terrible earthquakes
+than now, and that there was no certainty nor stability in the order of the
+natural world. A few sea-weeds and zoophytes, or plants and animals of the
+simplest organization, were alone capable of existing in a state of things
+so unfixed and unstable. But in proportion as the conditions of existence
+improved, and great convulsions and catastrophes became rarer and more
+partial, flowering plants were added to the cryptogamic class, and by the
+introduction of more and more perfect species, a varied and complex flora
+was at last established. In like manner, in the animal kingdom, the
+zoophyte, the brachiopod, the cephalopod, the fish, the reptile, the bird,
+and the warm-blooded quadruped made their entrance into the earth, one
+after the other, until finally, after the close of the tertiary period,
+came the quadrumanous mammalia, most nearly resembling man in outward form
+and internal structure, and followed soon afterwards, if not accompanied at
+first, by the human race itself.</p>
+
+<p>The objections which, in 1830, I urged against this doctrine<a name="FNanchor_B_14" id="FNanchor_B_14"></a><a href="#Footnote_B_14" class="fnanchor">[xvii-A]</a>, in so
+far as relates to the passage of the earth from a chaotic to a more settled
+condition, have since been embraced by a large and steadily increasing
+school of geologists; and in reference to the animate world, it will be
+seen, on comparing the present state of our knowledge with that which we
+possessed twenty years ago, how fully I was justified in declaring the
+insufficiency of the data on which such bold generalizations, respecting
+progressive development, were based. Speaking of the absence, from the
+tertiary formations, of fossil Quadrumana, I observed, in 1830, that "we
+had no right to expect to have detected any remains of tribes which live in
+trees, until we knew more of those quadrupeds which frequent marshes,
+rivers, and the borders of lakes, such being usually first met with in a
+fossil state."<a name="FNanchor_B_15" id="FNanchor_B_15"></a><a href="#Footnote_B_15" class="fnanchor">[xvii-B]</a> I also added, "if we are led to infer, from the
+presence of crocodiles and turtles in the London clay, and from the
+cocoa-nuts and spices found in the isle of Sheppey, that at the period when
+our older tertiary strata were formed, the climate was hot enough for the
+Quadrumana, we nevertheless could not hope to discover any of their
+skeletons, until we had made considerable progress in ascertaining what
+were the contemporary Pachydermata; and not one of these has been
+discovered as yet in any strata of this epoch in England."</p>
+
+<p>Nine years afterwards, when these fossil Pachyderms had been found in the
+London clay, and in the sandy strata at its base, the remains of a monkey,
+of the genus Macacus, were detected near Woodbridge, in Suffolk; and other
+Quadrumana had been met with, a short time previously, in different stages
+of the tertiary series, in India, France, and Brazil.</p>
+
+<p><span class="pagenum"><a id="pagexviii"></a>[p.xviii]</span>When we consider the small area of the earth's surface hitherto
+examined geologically, and our scanty acquaintance with the fossil
+Vertebrata, even of the environs of great European capitals, it is truly
+surprising that any naturalist should be rash enough to assume that the
+Lower Eocene deposits mark the era of the first creation of Quadrumana. It
+is, however, still more unphilosophical to infer from a single extinct
+species of this order, obtained in a latitude far from the tropics, that
+the Eocene Quadrumana had not attained as high a grade of organization as
+those of our own times, when the naturalist is acquainted with all, or
+nearly all, the species of monkeys, apes and orangs which are contemporary
+with man.</p>
+
+<p>To return to the year 1830, Mammalia had not then been traced to rocks of
+higher antiquity than the Stonesfield Oolite, whereas we have just seen
+that memorials of this class have at length made their appearance in the
+Trias of Germany. In 1830 birds had been discovered no lower in the series
+than the Paris gypsum, or Middle Eocene. Their bones have now been found
+both in England and the Swiss Alps in the Lower Eocene, and their existence
+has been established by foot-prints in the triassic epoch in North America
+(<a href="#page297">p. 297.</a>). Reptiles in 1830 had not been detected in rocks older than the
+Magnesian limestone, or Permian formation; whereas the skeletons of four
+species have since been brought to light (see <a href="#page336">p. 336.</a>) in the
+coal-measures, and one in the Old Red sandstone, of Europe, while the
+footprints of three or four more have been observed in carboniferous rocks
+of North America, not to mention the chelonian trail above described, from
+the most ancient of the fossiliferous rocks of Canada, the "Potsdam
+Sandstone," which lies at the base of the Lower Silurian system. (See
+above, <a href="#pagevii">p. vii.</a>)</p>
+
+<p>Lastly, the remains of fish, which in 1830 were scarcely recognized in
+deposits older than the coal, have now been found plentifully in the
+Devonian, and sparingly in the Silurian, strata; though not in any
+formation of such high antiquity as the Chelonian of Montreal.</p>
+
+<p>Previously to the discovery last mentioned, it was by no means uncommon for
+paleontologists to speak with confidence of fish as having been created
+before reptiles. It was deemed reasonable to suppose that the introduction
+of a particular class or order of beings into the planet coincided, in
+date, with the age of the oldest rock to which the remains of that class or
+order happened then to have been traced back. To be consistent with
+themselves, the same naturalists ought now to take for granted that
+reptiles were called into existence before fish. This they will not do,
+because such a conclusion would militate against their favourite hypothesis
+of an ascending scale, according to which Nature "evolved the organic
+world," rendering it more and more perfect in the lapse of ages.</p>
+
+<p>In our efforts to arrive at sound theoretical views on such a question, it
+would seem most natural to turn to the marine invertebrate animals as to a
+class affording the most complete series of monuments that have come down
+to us, and where we can find corresponding <span class="pagenum"><a id="pagexix"></a>[p.xix]</span>terms of comparison,
+in strata of every age. If, in this more complete series of her archives,
+Nature had really exhibited a more simple grade of organization in fossils
+of the remotest antiquity, we might have suspected that there was some
+foundation of facts in the theory of successive development. But what do we
+find? In the Lower Silurian there is a full representation of the Radiata,
+Mollusca, and Articulata proper to the sea. The marine Fauna, indeed, in
+those three classes, is so rich as almost to imply a more perfect
+development than that which now peoples the ocean. Thus, in the great
+division of the Radiata, we find asteroid and helianthoid zoophytes,
+besides crinoid and cystidean echinoderms. In the Mollusca of the same most
+ancient epoch M. Barrande enumerates, in Bohemia alone, the astonishing
+number of 253 species of Cephalopoda. In the Articulata we have the
+crustaceans, represented by more than 200 species of Trilobites, not to
+mention other genera.</p>
+
+<p>It is only then, in reference to the Vertebrata, that the argument of
+degeneracy in proportion as we trace fossils back to older formations can
+be maintained; and the dogma rests mainly for its support on negative
+evidence, whether deduced from the entire absence of the fossil
+representatives of certain classes in particular rocks, or the low grade of
+the first few species of a class which chance has thrown in our way.</p>
+
+<p>The scarcity of all memorials of birds in strata below the Eocene, has been
+a subject of surprise to some geologists. The bones formerly referred to
+birds in the Wealden and Chalk, are now admitted to have belonged to flying
+reptiles, of various sizes, one of them from the Kentish chalk so large as
+to have measured 16 feet 6 inches from tip to tip of its outstretched
+wings. Whether some elongated bones of the Stonesfield Oolite should be
+referred to birds, which they seem greatly to resemble in microscopic
+structure or to Pterodactyles, is a point now under investigation. If it
+should be proved that no osseous remains of the class Aves have hitherto
+been derived from any secondary or primary formation, we must not too
+hastily conclude that birds were even scarce in these periods. The rarity
+of such fossils in the Eocene marine strata is very striking. In 1846,
+Professor Owen, in his "History of the Fossil Mammalia and Birds of Great
+Britain," was unable to obtain more than four or five fragments of bones
+and skulls of birds from the London Clay, by the aid of which four species
+were recognized. Even so recently, therefore, as 1846, as much was known of
+the Mammalia of the Stonesfield Oolite, as of the ornithic Fauna of our
+English Eocene deposits.</p>
+
+<p>To reason correctly on the value of negative facts in this branch of
+Paleontology, we must first have ascertained how far the relics of birds
+are now becoming preserved in new strata, whether marine, fluviatile, or
+lacustrine. I have explained, in the "Principles of Geology," that the
+imbedding of the bones of living birds in deposits now in progress in
+inland lakes appears to be extremely rare. In the shell-marl of Scotland,
+which is made up bodily of the shells of the genera Limneus, Planorbis,
+Succinea, and Valvata, and in which the <span class="pagenum"><a id="pagexx"></a>[p.xx]</span>skeletons of deer and oxen
+abound, we find no bones of birds. Yet we know that, before the lakes were
+drained which yield this marl used in agriculture, the surface of the water
+and the bordering swamps were covered with wild ducks, herons, and other
+fowl. They left no memorials behind them, because, if they perished on the
+land, their bodies decomposed or became the prey of carnivorous animals; if
+on the water, they were buoyant and floated till they were devoured by
+predaceous fish or birds. The same causes of obliteration have no power to
+efface the foot-prints which the same creatures may leave, under favourable
+circumstances, imprinted on an ancient mud-bank or shore, on which new
+strata may be from time to time thrown down. In the red mud of recent
+origin spread over wide areas by the high tides of the bay of Fundy,
+innumerable foot-tracks of recent birds (Tringa minuta) are preserved in
+successive layers, and hardened by the sun. Yet none of the bones of these
+birds, though diligently searched for, have yet been discovered in digging
+trenches through the red mud. It is true that, in a few spots, the bones of
+birds have been met with plentifully in the older tertiary strata, but
+always in rocks of freshwater origin, such as the Paris gypsum or the
+lacustrine limestone of the Limagne d'Auvergne. In strata of the same age,
+in Belgium and other European countries, or in the United States, where no
+less careful search has been made, few, if any, fossil birds have come to
+light.</p>
+
+<p>We ought, therefore, most clearly to perceive that it is no part of the
+plan of Nature to hand down to after times a complete or systematic record
+of the former history of the animate world. The preservation of the relics,
+even of aquatic tribes of animals, is an exception to the general rule,
+although time may so multiply exceptional cases that they may seem to
+constitute the rule; and may thus impose upon the imagination, leading us
+to infer the non-existence of creatures of which no monuments are extant.
+Hitherto our acquaintance with the birds, and even the Mammalia, of the
+Eocene period has depended, almost everywhere, on single specimens, or on a
+few individuals found in one spot. It has therefore depended on what we
+commonly call chance; and we must not wonder if the casual discovery of a
+tertiary, secondary, or primary rock, rich in fossil impressions of the
+foot-prints of birds or quadrupeds, should modify or suddenly overthrow all
+theories based on negative facts.</p>
+
+<p>The chief reason why we meet more readily with the remains of every class
+in tertiary than in secondary strata, is simply that the older rocks are
+more and more exclusively marine in proportion as we depart farther and
+farther from periods during which the existing continents were built up.
+The secondary and primary formations are, for the most part, marine,&mdash;not
+because the ocean was more universal in past times, but because the epochs
+which preceded the Eocene were so distant from our own, that entire
+continents have been since submerged.</p>
+
+<p>I have alluded at <a href="#page299">p. 299.</a> to Mr. Darwin's account of the South American
+Ostriches, seen on the coast of Buenos Ayres, walking at <span class="pagenum"><a id="pagexxi"></a>[p.xxi]</span>low
+water over extensive mud-banks, which are then dry, for the sake of feeding
+on small fish. Perhaps no bird of such perfect organization as the eagle or
+vulture may ever accompany these ostriches. Certainly, we cannot expect the
+condor of the Andes to leave its trail on such a shore; and no traveller,
+after searching for footprints along the whole eastern coast of South
+America, would venture to speculate, from the results of such an inquiry,
+on the extent, variety, or development of the feathered Fauna of the
+interior of that continent.</p>
+
+<p>The absence of Cetacea from rocks older than the Eocene has been frequently
+adduced as lending countenance to the theory of the late appearance of the
+highest class of Vertebrata on the earth. That we have hitherto failed to
+detect them in the Oolite or Trias, does not imply, as we have now seen,
+that Mammalia were not then created. Even in the Eocene strata of Europe,
+the discovery of Cetaceans has never kept pace with that of land
+quadrupeds. The only instance cited in Great Britain is a species of
+Monodon, from the London clay, of doubtful authenticity as to its
+geological position. On the other hand, the gigantic Zeuglodon of North
+America (see <a href="#page207">p. 207.</a>), occurs abundantly in the Middle Eocene strata of
+Georgia and Alabama, from which as yet no bones of land-quadrupeds have
+been obtained.</p>
+
+<p>Professor Sedgwick states in a recent work<a name="FNanchor_B_16" id="FNanchor_B_16"></a><a href="#Footnote_B_16" class="fnanchor">[xxi-A]</a>, that he possesses in the
+Woodwardian Museum, a mass of anchylosed cervical vertebr� of a whale which
+he found near Ely, and which he believes to have been washed out of the
+Kimmeridge clay, a member of the Upper Oolite; but its true geological site
+is not well determined. It differs, says Professor Owen, from any other
+known fossil or recent whale.</p>
+
+<p>In the present imperfect state then of our information, we can scarcely say
+more than that the Cetacea may have been scarce, in the secondary and
+primary periods. It is quite conceivable that when aquatic saurians, some
+of them carnivorous, like the Ichthyosaurus, were swarming in the sea, and
+when there were large herbivorous reptiles, like the Iguanodon, on the
+land, such reptiles may, to a certain extent, have superseded the Cetacea,
+and discharged their functions in the animal economy.</p>
+
+<p>The views which I proposed originally in the Principles of Geology in
+opposition to the theory of progressive development may be thus briefly
+explained. From the earliest period at which plants and animals can be
+proved to have existed, there has been a continual change going on in the
+position of land and sea, accompanied by great fluctuations of climate. To
+these ever-varying geographical and climatal conditions the state of the
+animate world has been unceasingly adapted. No satisfactory proof has yet
+been discovered of the gradual passage of the earth from a chaotic to a
+more habitable state, nor of a law of progressive development governing the
+extinction and renovation of species, and causing the Fauna and Flora to
+pass from an embryonic to a more perfect condition, from a simple to a more
+complex organization.</p>
+
+<p><span class="pagenum"><a id="pagexxii"></a>[p.xxii]</span>The principle of adaptation above alluded to, appears to have
+been analogous to that which now peoples the arctic, temperate, and
+tropical regions contemporaneously with distinct assemblages of species and
+genera, or which independently of mere temperature gives rise to a
+predominance of the marsupial tribe of quadrupeds in Australia, and of the
+placental tribe in Asia and Europe, or to a profusion of reptiles without
+mammalia in the Galapagos Archipelago, and of mammalia without reptiles in
+Greenland.<a name="FNanchor_B_17" id="FNanchor_B_17"></a><a href="#Footnote_B_17" class="fnanchor">[xxii-A]</a></p>
+
+<p>This theory implies, almost necessarily, a very unequal representation at
+successive periods of the principal classes and orders of plants and
+animals, if not in the whole globe, at least throughout very wide areas.
+Thus, for example, the proportional number of genera, species, and
+individuals in the vertebrate class may differ, in two different and
+distinct epochs, to an extent unparalleled by any two contemporaneous
+Faunas, because in the course of millions of ages, the contrast of climate
+and geographical conditions may exceed the difference now observable in
+polar and equatorial latitudes.</p>
+
+<p>I shall conclude by observing, that if the doctrine of successive
+development had been paleontologically true, as the new discoveries above
+enumerated show that it is not; if the sponge, the cephalopod, the fish,
+the reptile, the bird, and the mammifer had followed each other in regular
+chronological order&mdash;the creation of each class being separated from the
+other by vast intervals of time; and if it were admitted that Man was
+created last of all, still we should by no means be able to recognize, in
+his entrance upon the earth, the last term of one and the same series of
+progressive developments. For the superiority of Man, as compared to the
+irrational mammalia, is one of kind, rather than of degree, consisting in a
+rational and moral nature, with an intellect capable of indefinite
+progression, and not in the perfection of his physical organization, or
+those instincts in which he resembles the brutes. He may be considered as a
+link in the same unbroken chain of being, if we regard him simply as a new
+species&mdash;a member of the animal kingdom&mdash;subject, like other species, to
+certain fixed and invariable laws, and adapted like them to the state of
+the animate and inanimate world prevailing at the time of his creation.
+Physically considered, he may form part of an indefinite series of
+terrestrial changes past, present, and to come; but morally and
+intellectually he may belong to another system of things&mdash;of things
+immaterial&mdash;a system which is not permitted to interrupt or disturb the
+course of the material world, or the laws which govern its changes.<a name="FNanchor_B_18" id="FNanchor_B_18"></a><a href="#Footnote_B_18" class="fnanchor">[xxii-B</a>]</p>
+
+
+
+
+<h2><span class="pagenum"><a id="pagexxiii"></a>[p.xxiii]</span>CONTENTS.</h2>
+
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER I.</li>
+<li class="center hweight p1mi">ON THE DIFFERENT CLASSES OF ROCKS.</li>
+</ul>
+
+<blockquote>Geology defined &mdash; Successive formation of the earth's
+crust &mdash; Classification of rocks according to their origin and
+age &mdash; Aqueous rocks &mdash; Their stratification and imbedded
+fossils &mdash; Volcanic rocks, with and without cones and craters &mdash; Plutonic
+rocks, and their relation to the volcanic &mdash; Metamorphic rocks and their
+probable origin &mdash; The term primitive, why erroneously applied to the
+crystalline formations &mdash; Leading division of the work <span class="ralign1"> <a href="#page1">Page 1</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER II.</li>
+<li class="center hweight p1mi">AQUEOUS ROCKS&mdash;THEIR COMPOSITION AND FORMS OF STRATIFICATION.</li>
+</ul>
+
+<blockquote>Mineral composition of strata &mdash; Arenaceous
+rocks &mdash; Argillaceous &mdash; Calcareous &mdash; Gypsum &mdash; Forms of
+stratification &mdash; Original horizontality &mdash; Thinning out &mdash; Diagonal
+arrangement &mdash; Ripple mark <span class="ralign1"><a href="#page10">10</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER III.</li>
+<li class="center hweight p1mi">ARRANGEMENT OF FOSSILS IN STRATA&mdash;FRESHWATER AND MARINE.</li>
+</ul>
+
+<blockquote>Successive deposition indicated by fossils &mdash; Limestones formed of
+corals and shells &mdash; Proofs of gradual increase of strata derived from
+fossils &mdash; Serpula attached to spatangus &mdash; Wood bored by
+Teredina &mdash; Tripoli and semi-opal formed of infusoria &mdash; Chalk derived
+principally from organic bodies &mdash; Distinction of freshwater from marine
+formations &mdash; Genera of freshwater and land shells &mdash; Rules for
+recognizing marine testacea &mdash; Gyrogonite and chara &mdash; Freshwater
+fishes &mdash; Alternation of marine and freshwater deposits &mdash; Lym-Fiord <span class="ralign1"><a href="#page21">21</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER IV.</li>
+<li class="center hweight p1mi">CONSOLIDATION OF STRATA AND PETRIFACTION OF FOSSILS.</li>
+</ul>
+
+<blockquote>Chemical and mechanical deposits &mdash; Cementing together of
+particles &mdash; Hardening by exposure to air &mdash; Concretionary
+nodules &mdash; Consolidating effects of pressure &mdash; Mineralization of organic
+remains &mdash; Impressions and casts how formed &mdash; Fossil wood &mdash; G�ppert's
+experiments &mdash; Precipitation of stony matter most rapid where
+putrefaction is going on &mdash; Source of lime in solution &mdash; Silex derived
+from decomposition of felspar &mdash; Proofs of the lapidification of some
+fossils soon after burial, of others when much decayed <span class="ralign1"><a href="#page33">33</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2"><span class="pagenum"><a id="pagexxiv"></a>[p.xxiv]</span>CHAPTER V.</li>
+<li class="center hweight p1mi">ELEVATION OF STRATA ABOVE THE SEA&mdash;HORIZONTAL AND INCLINED
+STRATIFICATION.</li>
+</ul>
+
+<blockquote>Why the position of marine strata, above the level of the sea, should
+be referred to the rising up of the land, not to the going down of the
+sea &mdash; Upheaval of extensive masses of horizontal strata &mdash; Inclined and
+vertical stratification &mdash; Anticlinal and synclinal lines &mdash; Bent strata
+in east of Scotland &mdash; Theory of folding by lateral
+movement &mdash; Creeps &mdash; Dip and strike &mdash; Structure of the Jura &mdash; Various forms
+of outcrop &mdash; Rocks broken by flexure &mdash; Inverted position of disturbed
+strata &mdash; Unconformable stratification &mdash; Hutton and Playfair on the
+same &mdash; Fractures of strata &mdash; Polished surfaces &mdash; Faults &mdash; Appearance of
+repeated alternations produced by them &mdash; Origin of great faults <span class="ralign1"><a href="#page44">44</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER VI.</li>
+<li class="center hweight p1mi">DENUDATION.</li>
+</ul>
+
+<blockquote>Denudation defined &mdash; Its amount equal to the entire mass of stratified
+deposits in the earth's crust &mdash; Horizontal sandstone denuded in
+Ross-shire &mdash; Levelled surface of countries in which great faults
+occur &mdash; Coalbrook Dale &mdash; Denuding power of the ocean during the
+emergence of land &mdash; Origin of Valleys &mdash; Obliteration of
+sea-cliffs &mdash; Inland sea-cliffs and terraces in the Morea and
+Sicily &mdash; Limestone pillars at St. Mihiel, in France &mdash; in Canada &mdash; in the
+Bermudas <span class="ralign1"><a href="#page66">66</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER VII.</li>
+<li class="center hweight p1mi">ALLUVIUM.</li>
+</ul>
+
+<blockquote>Alluvium described &mdash; Due to complicated causes &mdash; Of various ages, as
+shown in Auvergne &mdash; How distinguished from rocks <i>in
+situ</i> &mdash; River-terraces &mdash; Parallel roads of Glen Roy &mdash; Various theories
+respecting their origin <span class="ralign1"><a href="#page79">79</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER VIII.</li>
+<li class="center hweight p1mi">CHRONOLOGICAL CLASSIFICATION OF ROCKS.</li>
+</ul>
+
+<blockquote>Aqueous, plutonic, volcanic, and metamorphic rocks, considered
+chronologically &mdash; Lehman's division into primitive and
+secondary &mdash; Werner's addition of a transition class &mdash; Neptunian
+theory &mdash; Hutton on igneous origin of granite &mdash; How the name of primary
+was still retained for granite &mdash; The term "transition," why faulty &mdash; The
+adherence to the old chronological nomenclature retarded the progress
+of geology &mdash; New hypothesis invented to reconcile the igneous origin of
+granite to the notion of its high antiquity &mdash; Explanation of the
+chronological nomenclature adopted in this work, so far as regards
+primary, secondary, and tertiary periods <span class="ralign1"><a href="#page89">89</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER IX.</li>
+<li class="center hweight p1mi">ON THE DIFFERENT AGES OF THE AQUEOUS ROCKS.</li>
+</ul>
+
+<blockquote>On the three principal tests of relative age &mdash; superposition, mineral
+character, and fossils &mdash; Change of mineral character and fossils in the
+same continuous formation &mdash; Proofs that distinct species of animals and
+plants have lived at successive periods &mdash; Distinct provinces of
+indigenous species &mdash; Great extent of single provinces &mdash; Similar laws
+prevailed at successive geological periods &mdash; Relative importance of
+mineral and pal�ontological characters &mdash; Test of age by included
+fragments &mdash; Frequent absence of strata of intervening
+periods &mdash; Principal groups of strata in western Europe <span class="ralign1"><a href="#page96">96</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2"><span class="pagenum"><a id="pagexxv"></a>[p.xxv]</span>CHAPTER X.</li>
+<li class="center hweight p1mi">CLASSIFICATION OF TERTIARY FORMATIONS.&mdash;POST-PLIOCENE GROUP.</li>
+</ul>
+
+<blockquote>General principles of classification of tertiary strata &mdash; Detached
+formations scattered over Europe &mdash; Strata of Paris and London &mdash; More
+modern groups &mdash; Peculiar difficulties in determining the chronology of
+tertiary formations &mdash; Increasing proportion of living species of shells
+in strata of newer origin &mdash; Terms Eocene, Miocene, and
+Pliocene &mdash; Post-Pliocene strata &mdash; Recent or human period &mdash; Older
+Post-Pliocene formations of Naples, Uddevalla, and Norway &mdash; Ancient
+upraised delta of the Mississippi &mdash; Loess of the Rhine <span class="ralign1"><a href="#page104">104</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XI.</li>
+<li class="center hweight p1mi">NEWER PLIOCENE PERIOD. &mdash; BOULDER FORMATION.</li>
+</ul>
+
+<blockquote>Drift of Scandinavia, northern Germany, and Russia &mdash; Its northern
+origin &mdash; Not all of the same age &mdash; Fundamental rocks polished, grooved,
+and scratched &mdash; Action of glaciers and icebergs &mdash; Fossil shells of
+glacial period &mdash; Drift of eastern Norfolk &mdash; Associated freshwater
+deposit &mdash; Bent and folded strata lying on undisturbed beds &mdash; Shells on
+Moel Tryfane &mdash; Ancient glaciers of North Wales &mdash; Irish drift <span class="ralign1"><a href="#page121">121</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XII.</li>
+<li class="center hweight p1mi">BOULDER FORMATION&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Difficulty of interpreting the phenomena of drift before the glacial
+hypothesis was adopted &mdash; Effects of intense cold in augmenting the
+quantity of alluvium &mdash; Analogy of erratics and scored rocks in North
+America and Europe &mdash; Bayfield on shells in drift of Canada &mdash; Great
+subsidence and re-elevation of land from the sea, required to account
+for glacial appearances &mdash; Why organic remains so rare in northern
+drift &mdash; Mastodon giganteus in United States &mdash; Many shells and some
+quadrupeds survived the glacial cold &mdash; Alps an independent centre of
+dispersion of erratics &mdash; Alpine blocks on the Jura &mdash; Recent
+transportation of erratics from the Andes to Chiloe &mdash; Meteorite in
+Asiatic drift <span class="ralign1"><a href="#page131">131</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XIII.</li>
+<li class="center hweight p1mi">NEWER PLIOCENE STRATA AND CAVERN DEPOSITS.</li>
+</ul>
+
+<blockquote>Chronological classification of Pleistocene formations, why
+difficult &mdash; Freshwater deposits in valley of Thames &mdash; In Norfolk
+cliffs &mdash; In Patagonia &mdash; Comparative longevity of species in the mammalia
+and testacea &mdash; Fluvio-marine crag of Norwich &mdash; Newer Pliocene strata of
+Sicily &mdash; Limestone of great thickness and elevation &mdash; Alternation of
+marine and volcanic formations &mdash; Proofs of slow accumulation &mdash; Great
+geographical changes in Sicily since the living fauna and flora began
+to exist &mdash; Osseous breccias and cavern
+deposits &mdash; Sicily &mdash; Kirkdale &mdash; Origin of stalactite &mdash; Australian
+cave-breccias &mdash; Geographical relationship of the provinces of living
+vertebrata and those of the fossil species of the Pliocene
+periods &mdash; Extinct struthious birds of New Zealand &mdash; Teeth of fossil
+quadrupeds <span class="ralign1"><a href="#page146">146</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XIV.</li>
+<li class="center hweight p1mi">OLDER PLIOCENE AND MIOCENE FORMATIONS.</li>
+</ul>
+
+<blockquote>Strata of Suffolk termed Red and Coralline crag &mdash; Fossils, and
+proportion of recent species &mdash; Depth of sea and climate &mdash; Reference of
+Suffolk crag to the older Pliocene period &mdash; Migration of many species
+of shells southwards during the glacial period &mdash; Fossil
+whales &mdash; Subapennine beds &mdash; Asti, Sienna, Rome &mdash; Miocene
+formations &mdash; Faluns of Touraine &mdash; Depth of sea and littoral character of
+fauna &mdash; Tropical climate implied by the testacea &mdash; Proportion of recent
+species of <span class="pagenum"><a id="pagexxvi"></a>[p.xxvi]</span>shells &mdash; Faluns more ancient than the Suffolk
+crag &mdash; Miocene strata of Bordeaux and Piedmont &mdash; Molasse of
+Switzerland &mdash; Tertiary strata of Lisbon &mdash; Older Pliocene and Miocene
+formations in the United States &mdash; Sew�lik Hills in India <span class="ralign1"><a href="#page161">161</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XV.</li>
+<li class="center hweight p1mi">UPPER EOCENE FORMATIONS.</li>
+</ul>
+
+<blockquote>Eocene areas in England and France &mdash; Tabular view of French Eocene
+strata &mdash; Upper Eocene group of the Paris basin &mdash; Same beds in Belgium
+and at Berlin &mdash; Mayence tertiary strata &mdash; Freshwater upper Eocene of
+Central France &mdash; Series of geographical changes since the land emerged
+in Auvergne &mdash; Mineral character an uncertain test of age &mdash; Marls
+containing Cypris &mdash; Oolite of Eocene period &mdash; Indusial limestone and its
+origin &mdash; Fossil mammalia of the upper Eocene strata in
+Auvergne &mdash; Freshwater strata of the Cantal, calcareous and
+siliceous &mdash; Its resemblance to chalk &mdash; Proofs of gradual deposition of
+strata <span class="ralign1"><a href="#page174">174</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XVI.</li>
+<li class="center hweight p1mi">EOCENE FORMATIONS&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Subdivisions of the Eocene group in the Paris basin &mdash; Gypseous
+series &mdash; Extinct quadrupeds &mdash; Impulse given to geology by Cuvier's
+osteological discoveries &mdash; Shelly sands called sables moyens &mdash; Calcaire
+grossier &mdash; Miliolites &mdash; Calcaire siliceux &mdash; Lower Eocene in France &mdash; Lits
+coquilliers &mdash; Sands and plastic clay &mdash; English Eocene strata &mdash; Freshwater
+and fluvio-marine beds &mdash; Barton beds &mdash; Bagshot and Bracklesham
+division &mdash; Large ophidians and saurians &mdash; Lower Eocene and London Clay
+proper &mdash; Fossil plants and shells &mdash; Strata of Kyson in Suffolk &mdash; Fossil
+monkey and opossum &mdash; Mottled clays and sand below London
+Clay &mdash; Nummulitic formation of Alps and Pyrenees &mdash; Its wide geographical
+extent &mdash; Eocene strata in the United States &mdash; Section at Claiborne,
+Alabama &mdash; Colossal cetacean &mdash; Orbitoid limestone &mdash; Burr stone <span class="ralign1"><a href="#page190">190</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XVII.</li>
+<li class="center hweight p1mi">CRETACEOUS GROUP.</li>
+</ul>
+
+<blockquote>Divisions of the cretaceous series in North-Western Europe &mdash; Upper
+cretaceous strata &mdash; Maestricht beds &mdash; Chalk of Faxoe &mdash; White
+chalk &mdash; Characteristic fossils &mdash; Extinct cephalopoda &mdash; Sponges and corals
+of the chalk &mdash; Signs of open and deep sea &mdash; White area of white
+chalk &mdash; Its origin from corals and shells &mdash; Single pebbles in
+chalk &mdash; Siliceous sandstone in Germany contemporaneous with white
+chalk &mdash; Upper greensand and gault &mdash; Lower cretaceous strata &mdash; Atherfield
+section, Isle of Wight &mdash; Chalk of South of Europe &mdash; Hippurite
+limestone &mdash; Cretaceous Flora &mdash; Chalk of United States <span class="ralign1"><a href="#page209">209</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XVIII.</li>
+<li class="center hweight p1mi">WEALDEN GROUP.</li>
+</ul>
+
+<blockquote>The Wealden divisible into Weald Clay, Hastings Sand, and Purbeck
+Beds &mdash; Intercalated between two marine formations &mdash; Weald clay and
+Cypris-bearing strata &mdash; Iguanodon &mdash; Hastings sands &mdash; Fossil fish &mdash; Strata
+formed in shallow water &mdash; Brackish water-beds &mdash; Upper, middle, and lower
+Purbeck &mdash; Alternations of brackish water, freshwater, and
+land &mdash; Dirt-bed, or ancient soil &mdash; Distinct species of fossils in each
+subdivision of the Wealden &mdash; Lapse of time implied &mdash; Plants and insects
+of Wealden &mdash; Geographical extent of Wealden &mdash; Its relation to the
+cretaceous and oolitic periods &mdash; Movements in the earth's crust to
+which it owed its origin and submergence <span class="ralign1"><a href="#page225">225</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2"><span class="pagenum"><a id="pagexxvii"></a>[p.xxvii]</span>CHAPTER XIX.</li>
+<li class="center hweight p1mi">DENUDATION OF THE CHALK AND WEALDEN.</li>
+</ul>
+
+<blockquote>Physical geography of certain districts composed of Cretaceous and
+Wealden strata &mdash; Lines of inland chalk-cliffs on the Seine in
+Normandy &mdash; Outstanding pillars and needles of chalk &mdash; Denudation of the
+chalk and Wealden in Surrey, Kent, and Sussex &mdash; Chalk once continuous
+from the North to the South Downs &mdash; Anticlinal axis and parallel
+ridges &mdash; Longitudinal and transverse valleys &mdash; Chalk escarpments &mdash; Rise
+and denudation of the strata gradual &mdash; Ridges formed by harder, valleys
+by softer beds &mdash; Why no alluvium, or wreck of the chalk, in the central
+district of the Weald &mdash; At what periods the Weald valley was
+denuded &mdash; Land has most prevailed where denudation has been
+greatest &mdash; Elephant bed, Brighton <span class="ralign1"><a href="#page238">238</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XX.</li>
+<li class="center hweight p1mi">OOLITE AND LIAS.</li>
+</ul>
+
+<blockquote>Subdivisions of the Oolitic or Jurassic group &mdash; Physical geography of
+the Oolite in England and France &mdash; Upper Oolite &mdash; Portland stone and
+fossils &mdash; Lithographic stone of Solenhofen &mdash; Middle Oolite, coral
+rag &mdash; Zoophytes &mdash; Nerin�an limestone &mdash; Diceras limestone &mdash; Oxford clay,
+Ammonites and Belemnites &mdash; Lower Oolite, Crinoideans &mdash; Great Oolite and
+Bradford clay &mdash; Stonesfield slate &mdash; Fossil mammalia, placental and
+marsupial &mdash; Resemblance to an Australian fauna &mdash; Doctrine of progressive
+development &mdash; Collyweston slates &mdash; Yorkshire Oolitic coal-field &mdash; Brora
+coal &mdash; Inferior Oolite and fossils <span class="ralign1"><a href="#page257">257</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXI.</li>
+<li class="center hweight p1mi">OOLITE AND LIAS&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Mineral character of Lias &mdash; Name of Gryphite limestone &mdash; Fossil shells
+and fish &mdash; Ichthyodorulites &mdash; Reptiles of the Lias &mdash; Ichthyosaur and
+Plesiosaur &mdash; Marine Reptile of the Galapagos Islands &mdash; Sudden
+destruction and burial of fossil animals in Lias &mdash; Fluvio-marine beds
+in Gloucestershire and insect limestone &mdash; Origin of the Oolite and
+Lias, and of alternating calcareous and argillaceous
+formations &mdash; Oolitic coal-field of Virginia, in the United States <span class="ralign1"><a href="#page273">273</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXII.</li>
+<li class="center hweight p1mi">TRIAS OR NEW RED SANDSTONE GROUP.</li>
+</ul>
+
+<blockquote>Distinction between New and Old Red Sandstone &mdash; Between Upper and Lower
+New Red &mdash; The Trias and its three divisions &mdash; Most largely developed in
+Germany &mdash; Keuper and its fossils &mdash; Muschelkalk &mdash; Fossil plants of
+Bunter &mdash; Triassic group in England &mdash; Bone-bed of Axmouth and Aust &mdash; Red
+Sandstone of Warwickshire and Cheshire &mdash; Footsteps of <i>Chirotherium</i> in
+England and Germany &mdash; Osteology of the <i>Labyrinthodon</i> &mdash; Identification
+of this Batrachian with the Chirotherium &mdash; Origin of Red Sandstone and
+rock-salt &mdash; Hypothesis of saline volcanic exhalations &mdash; Theory of the
+precipitation of salt from inland lakes or lagoons &mdash; Saltness of the
+Red Sea &mdash; New Red Sandstone in the United States &mdash; Fossil footprints of
+birds and reptiles in the Valley of the Connecticut &mdash; Antiquity of the
+Red Sandstone containing them <span class="ralign1"><a href="#page286">286</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXIII.</li>
+<li class="center hweight p1mi">PERMIAN OR MAGNESIAN LIMESTONE GROUP.</li>
+</ul>
+
+<blockquote>Fossils of Magnesian Limestone and Lower New Red distinct from the
+Triassic &mdash; Term Permian &mdash; English and German equivalents &mdash; Marine shells
+and corals of <span class="pagenum"><a id="pagexxviii"></a>[p.xxviii]</span>English Magnesian limestone &mdash; Pal�oniscus
+and other fish of the marl slate &mdash; Thecodont Saurians of dolomitic
+conglomerate of Bristol &mdash; Zechstein and Rothliegendes of
+Thuringia &mdash; Permian Flora &mdash; Its generic affinity to the
+carboniferous &mdash; Psaronites or tree-ferns <span class="ralign1"><a href="#page301">301</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXIV.</li>
+<li class="center hweight p1mi">THE COAL OR CARBONIFEROUS GROUP.</li>
+</ul>
+
+<blockquote>Carboniferous strata in the south-west of England &mdash; Superposition of
+Coal-measures to Mountain limestone &mdash; Departure from this type in north
+of England and Scotland &mdash; Section in South Wales &mdash; Underclays with
+Stigmaria &mdash; Carboniferous Flora &mdash; Ferns, Lepidodendra, Calamites,
+Asterophyllites, Sigillari�, Stigmari�, &mdash; Conifer� &mdash; Endogens &mdash; Absence
+of Exogens &mdash; Coal, how formed &mdash; Erect fossil trees &mdash; Parkfield
+Colliery &mdash; St. Etienne, Coal-field &mdash; Oblique trees or snags &mdash; Fossil
+forests in Nova Scotia &mdash; Brackish water and marine strata &mdash; Origin of
+Clay-iron-stone <span class="ralign1"><a href="#page308">308</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXV.</li>
+<li class="center hweight p1mi">CARBONIFEROUS GROUP&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Coal-fields of the United States &mdash; Section of the country between the
+Atlantic and Mississippi &mdash; Position of land in the carboniferous period
+eastward of the Alleghanies &mdash; Mechanically formed rocks thinning out
+westward, and limestones thickening &mdash; Uniting of many coal-seams into
+one thick one &mdash; Horizontal coal at Brownsville, Pennsylvania &mdash; Vast
+extent and continuity of single seams of coal &mdash; Ancient river-channel
+in Forest of Dean coal-field &mdash; Absence of earthy matter in
+coal &mdash; Climate of carboniferous period &mdash; Insects in coal &mdash; Rarity of
+air-breathing animals &mdash; Great number of fossil fish &mdash; First discovery of
+the skeletons of fossil reptiles &mdash; Footprints of reptilians &mdash; Mountain
+limestone &mdash; Its corals and marine shells <span class="ralign1"><a href="#page326">326</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXVI.</li>
+<li class="center hweight p1mi">OLD RED SANDSTONE, OR DEVONIAN GROUP.</li>
+</ul>
+
+<blockquote>Old Red Sandstone of Scotland, and borders of Wales &mdash; Fossils usually
+rare &mdash; "Old Red" in Forfarshire &mdash; Ichthyolites of Caithness &mdash; Distinct
+lithological type of Old Red in Devon and Cornwall &mdash; Term
+"Devonian" &mdash; Organic remains of intermediate character between those of
+the Carboniferous and Silurian systems &mdash; Corals and shells &mdash; Devonian
+strata of Westphalia, the Eifel, Russia, and the United States &mdash; Coral
+reef at Falls of the Ohio &mdash; Devonian Flora <span class="ralign1"><a href="#page342">342</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXVII.</li>
+<li class="center hweight p1mi">SILURIAN GROUP.</li>
+</ul>
+
+<blockquote>Silurian strata formerly called transition &mdash; Term
+grauwack� &mdash; Subdivisions of Upper and Lower Silurian &mdash; Ludlow formation
+and fossils &mdash; Wenlock formation, corals and shells &mdash; Caradoc and
+Llandeilo beds &mdash; Graptolites &mdash; Lingula &mdash; Trilobites &mdash; Cystide� &mdash; Vast
+thickness of Silurian strata in North Wales &mdash; Unconformability of
+Caradoc sandstone &mdash; Silurian strata of the United States &mdash; Amount of
+specific agreement of fossils with those of Europe &mdash; Great number of
+brachiopods &mdash; Deep-sea origin of Silurian strata &mdash; Absence of fluviatile
+formations &mdash; Mineral character of the most ancient fossiliferous rocks <span class="ralign1"><a href="#page350">350</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2"><span class="pagenum"><a id="pagexxix"></a>[p.xxix]</span>CHAPTER XXVIII.</li>
+<li class="center hweight p1mi">VOLCANIC ROCKS.</li>
+</ul>
+
+<blockquote>Trap rocks &mdash; Name, whence derived &mdash; Their igneous origin at first
+doubted &mdash; Their general appearance and character &mdash; Volcanic cones and
+craters, how formed &mdash; Mineral composition and texture of volcanic
+rocks &mdash; Varieties of felspar &mdash; Hornblende and
+augite &mdash; Isomorphism &mdash; Rocks, how to be studied &mdash; Basalt, greenstone,
+trachyte, porphyry, scoria, amygdaloid, lava, tuff &mdash; Alphabetical list,
+and explanation of names and synonyms, of volcanic rocks &mdash; Table of the
+analyses of minerals most abundant in the volcanic and hypogene rocks <span class="ralign1"><a href="#page366">366</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXIX.</li>
+<li class="center hweight p1mi">VOLCANIC ROCKS&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Trap dike &mdash; sometimes project &mdash; sometimes leave fissures vacant by
+decomposition &mdash; Branches and veins of trap &mdash; Dikes more crystalline in
+the centre &mdash; Foreign fragments of rock imbedded &mdash; Strata altered at or
+near the contact &mdash; Obliteration of organic remains &mdash; Conversion of chalk
+into marble &mdash; and of coal into coke &mdash; Inequality in the modifying
+influence of dikes &mdash; Trap interposed between strata &mdash; Columnar and
+globular structure &mdash; Relation of trappean rocks to the products of
+active volcanos &mdash; Submarine lava and ejected matter correspond
+generally to ancient trap &mdash; Structure and physical features of Palma
+and some other extinct volcanos <span class="ralign1"><a href="#page378">378</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXX.</li>
+<li class="center hweight p1mi">ON THE DIFFERENT AGES OF THE VOLCANIC ROCKS.</li>
+</ul>
+
+<blockquote>Tests of relative age of volcanic rocks &mdash; Test by superposition and
+intrusion &mdash; Dike of Quarrington Hill, Durham &mdash; Test by alteration of
+rocks in contact &mdash; Test by organic remains &mdash; Test of age by mineral
+character &mdash; Test by included fragments &mdash; Volcanic rocks of the
+Post-Pliocene period &mdash; Basalt of Bay of Trezza in Sicily &mdash; Post-Pliocene
+volcanic rocks near Naples &mdash; Dikes of Somma &mdash; Igneous formations of the
+Newer Pliocene period &mdash; Val di Noto in Sicily <span class="ralign1"><a href="#page397">397</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXXI.</li>
+<li class="center hweight p1mi">ON THE DIFFERENT AGES OF THE VOLCANIC ROCKS&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Volcanic rocks of the Older Pliocene period &mdash; Tuscany &mdash; Rome &mdash; Volcanic
+region of Olot in Catalonia &mdash; Cones and lava-currents &mdash; Ravines and
+ancient gravel-beds &mdash; Jets of air called Bufadors &mdash; Age of the
+Catalonian volcanos &mdash; Miocene period &mdash; Brown-coal of the Eifel and
+contemporaneous trachytic breccias &mdash; Age of the brown-coal &mdash; Peculiar
+characters of the volcanos of the upper and lower Eifel &mdash; Lake
+craters &mdash; Trass &mdash; Hungarian volcanos <span class="ralign1"><a href="#page408">408</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXXII.</li>
+<li class="center hweight p1mi">ON THE DIFFERENT AGES OF THE VOLCANIC ROCKS&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Volcanic rocks of the Pliocene and Miocene periods
+continued &mdash; Auvergne &mdash; Mont Dor &mdash; Breccias and alluviums of Mont Perrier,
+with bones of quadrupeds &mdash; River dammed up by lava-current &mdash; Range of
+minor cones from Auvergne to the Vivarais &mdash; Monts Dome &mdash; Puy de
+C�me &mdash; Puy de Pariou &mdash; Cones not denuded by general flood &mdash; Velay &mdash; Bones
+of quadrupeds buried in scori� &mdash; Cantal &mdash; Eocene volcanic rocks &mdash; Tuffs
+near Clermont &mdash; Hill of Gergovia &mdash; Trap of Cretaceous period &mdash; Oolitic
+period &mdash; New Red Sandstone period &mdash; Carboniferous period &mdash; Old Red
+Sandstone period &mdash; "Rock and Spindle" near St. Andrews &mdash; Silurian
+period &mdash; Cambrian volcanic rocks <span class="ralign1"><a href="#page422">422</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2"><span class="pagenum"><a id="pagexxx"></a>[p.xxx]</span>CHAPTER XXXIII.</li>
+<li class="center hweight p1mi">PLUTONIC ROCKS&mdash;GRANITE.</li>
+</ul>
+
+<blockquote>General aspect of granite &mdash; Decomposing into spherical masses &mdash; Rude
+columnar structure &mdash; Analogy and difference of volcanic and plutonic
+formations &mdash; Minerals in granite, and their arrangement &mdash; Graphic and
+porphyritic granite &mdash; Mutual penetration of crystals of quartz and
+felspar &mdash; Occasional minerals &mdash; Syenite &mdash; Syenitic, talcose, and schorly
+granites &mdash; Eurite &mdash; Passage of granite into trap &mdash; Examples near
+Christiania and in Aberdeenshire &mdash; Analogy in composition of trachyte
+and granite &mdash; Granite veins in Glen Tilt, Cornwall, the Valorsine, and
+other countries &mdash; Different composition of veins from main body of
+granite &mdash; Metalliferous veins in strata near their junction with
+granite &mdash; Apparent isolation of nodules of granite &mdash; Quartz
+veins &mdash; Whether plutonic rocks are ever overlying &mdash; Their exposure at
+the surface due to denudation <span class="ralign1"><a href="#page436">436</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXXIV.</li>
+<li class="center hweight p1mi">ON THE DIFFERENT AGES OF THE PLUTONIC ROCKS.</li>
+</ul>
+
+<blockquote>Difficulty in ascertaining the precise age of a plutonic rock &mdash; Test of
+age by relative position &mdash; Test by intrusion and alteration &mdash; Test by
+mineral composition &mdash; Test by included fragments &mdash; Recent and Pliocene
+plutonic rocks, why invisible &mdash; Tertiary plutonic rocks in the
+Andes &mdash; Granite altering Cretaceous rocks &mdash; Granite altering Lias in the
+Alps and in Skye &mdash; Granite of Dartmoor altering Carboniferous
+strata &mdash; Granite of the Old Red Sandstone period &mdash; Syenite altering
+Silurian strata in Norway &mdash; Blending of the same with gneiss &mdash; Most
+ancient plutonic rocks &mdash; Granite protruded in a solid form &mdash; On the
+probable age of the granites of Arran, in Scotland <span class="ralign1"><a href="#page449">449</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXXV.</li>
+<li class="center hweight p1mi">METAMORPHIC ROCKS.</li>
+</ul>
+
+<blockquote>General character of metamorphic rocks &mdash; Gneiss &mdash; Hornblende-schist
+ &mdash; Mica-schist &mdash; Clay-slate &mdash; Quartzite &mdash; Chlorite-schist &mdash; Metamorphic
+limestone &mdash; Alphabetical list and explanation of other rocks of this
+family &mdash; Origin of the metamorphic strata &mdash; Their stratification is real
+and distinct from cleavage &mdash; Joints and slaty cleavage &mdash; Supposed causes
+of these structures &mdash; how far connected with crystalline action <span class="ralign1"><a href="#page463">463</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXXVI.</li>
+<li class="center hweight p1mi">METAMORPHIC ROCKS&mdash;<i>continued</i>.</li>
+</ul>
+
+<blockquote>Strata near some intrusive masses of granite converted into rocks
+identical with different members of the metamorphic series &mdash; Arguments
+hence derived as to the nature of plutonic action &mdash; Time may enable
+this action to pervade denser masses &mdash; From what kinds of sedimentary
+rock each variety of the metamorphic class may be derived &mdash; Certain
+objections to the metamorphic theory considered &mdash; Lamination of
+trachyte and obsidian due to motion &mdash; Whether some kinds of gneiss have
+become schistose by a similar action <span class="ralign1"><a href="#page473">473</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXXVII.</li>
+<li class="center hweight p1mi">ON THE DIFFERENT AGES OF THE METAMORPHIC ROCKS.</li>
+</ul>
+
+<blockquote>Age of each set of metamorphic strata twofold &mdash; Test of age by fossils
+and mineral character not available &mdash; Test by superposition
+ambiguous &mdash; Conversion of dense masses of fossiliferous strata into
+metamorphic rocks &mdash; Limestone and shale of Carrara &mdash; Metamorphic strata
+of modern periods in the Alps of Switzerland and <span class="pagenum"><a id="pagexxxi"></a>[p.xxxi]</span>Savoy &mdash; Why
+the visible crystalline strata are none of them very modern &mdash; Order of
+succession in metamorphic rocks &mdash; Uniformity of mineral character &mdash; Why
+the metamorphic strata are less calcareous than the fossiliferous <span class="ralign1"><a href="#page481">481</a></span></blockquote>
+
+<ul>
+<li class="ftsize115 center hweight p2">CHAPTER XXXVIII.</li>
+<li class="center hweight p1mi">MINERAL VEINS.</li>
+</ul>
+
+<blockquote>Werner's doctrine that mineral veins were fissures filled from
+above &mdash; Veins of segregation &mdash; Ordinary metalliferous veins or
+lodes &mdash; Their frequent coincidence with faults &mdash; Proofs that they
+originated in fissures in solid rock &mdash; Veins shifting other
+veins &mdash; Polishing of their walls &mdash; Shells and pebbles in lodes &mdash; Evidence
+of the successive enlargement and re-opening of veins &mdash; Fournet's
+observations in Auvergne &mdash; Dimensions of veins &mdash; Why some alternately
+swell out and contract &mdash; Filling of lodes by sublimation from
+below &mdash; Chemical and electrical action &mdash; Relative age of the precious
+metals &mdash; Copper and lead veins in Ireland older than Cornish tin &mdash; Lead
+vein in lias, Glamorganshire &mdash; Gold in Russia &mdash; Connection of hot
+springs and mineral veins &mdash; Concluding remarks <span class="ralign1"><a href="#page488">488</a></span></blockquote>
+
+<hr>
+
+
+<h3><i>Dates of the successive Editions of the "Principles" and "Elements" (or
+Manual) of Geology, by the Author.</i></h3>
+
+
+<table border="0" cellpadding="5" summary="DATES OF THE SUCCESSIVE EDITIONS OF THE
+PRINCIPLES AND ELEMENTS OF GEOLOGY">
+<colgroup>
+    <col width="60%">
+    <col width="20%">
+    <col width="20%">
+</colgroup>
+
+<tr>
+  <td>Principles, 1st vol. in octavo, published in</td>
+  <td>&nbsp;</td>
+  <td>Jan. 1830.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, 2d vol. &nbsp; do.</td>
+  <td>&nbsp;</td>
+  <td>Jan. 1832.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, 1st vol. 2d edition in octavo</td>
+  <td>&nbsp;</td>
+  <td>1832.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, 2d vol. 2d edition &nbsp; do.</td>
+  <td>&nbsp;</td>
+  <td>Jan. 1833.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, 3d vol. 1st edition &nbsp; do.</td>
+  <td>&nbsp;</td>
+  <td>May  1833.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, New edition (called the 3d) of the whole work in 4 vols. 12mo.</td>
+  <td>&nbsp;</td>
+  <td>May  1834.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, 4th edition, 4 vols. 12mo.</td>
+  <td>&nbsp;</td>
+  <td>June 1835.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, 5th edition, &nbsp; do. &nbsp; do.</td>
+  <td>&nbsp;</td>
+  <td>Mar. 1837.</td>
+</tr>
+
+<tr>
+  <td>Elements, 1st edition in one vol.</td>
+  <td>&nbsp;</td>
+  <td>July 1838.</td>
+</tr>
+
+<tr>
+  <td>Principles, 6th edition, 3 vols. 12mo.</td>
+  <td>&nbsp;</td>
+  <td>June 1840.</td>
+</tr>
+
+<tr>
+  <td>Elements, 2d edition in 2 vols. 12mo.</td>
+  <td>&nbsp;</td>
+  <td>July 1841.</td>
+</tr>
+
+<tr>
+  <td>Principles, 7th edition in one vol. 8vo.</td>
+  <td>&nbsp;</td>
+  <td>Feb. 1847.</td>
+</tr>
+
+<tr>
+  <td>&mdash;&mdash;, 8th edition, now published in one vol. 8vo.</td>
+  <td>&nbsp;</td>
+  <td>May 1850.</td>
+</tr>
+
+<tr>
+  <td>Manual of Elementary Geology (or "Elements," 3d edition), now
+published in one vol. 8vo.</td>
+  <td>&nbsp;</td>
+  <td>Jan. 1851.</td>
+</tr>
+</table>
+
+
+<h3><span class="pagenum"><a id="pagexxxii"></a>[p.xxxii]</span><i>Works by Sir Charles Lyell.</i></h3>
+<hr>
+<h4>I.</h4>
+
+<div class="blq2">
+<p class="indentm2"><span class="ftsize105">TRAVELS IN NORTH AMERICA</span>,&mdash;1841-2. With Geological Observations on the
+United States, Canada, and Nova Scotia. With large coloured geological Map
+and <span class="wosp1">Plates. 2</span> vols. post 8vo. 21<i>s.</i></p></div>
+
+
+<h4>II.</h4>
+
+<div class="blq2">
+<p class="indentm2"><span class="ftsize105">A SECOND VISIT TO THE UNITED STATES</span>,&mdash;1845-6. <i>Second Edition.</i><span class="wosp1"> 2</span>
+vols. post 8vo. 18<i>s.</i></p></div>
+
+
+<h4>III.</h4>
+
+<div class="blq2">
+<p class="indentm2"><span class="ftsize105">PRINCIPLES OF GEOLOGY</span>; or the Modern Changes of the Earth and its
+Inhabitants considered, as illustrative of Geology. <i>Eighth Edition,
+thoroughly revised.</i> With Maps, Plates, and <span class="wosp1">Woodcuts. 8vo.</span> 18<i>s.</i></p></div>
+
+
+<h4>IV.</h4>
+
+<div class="blq2">
+<p class="indentm2"><span class="ftsize105">A MANUAL OF ELEMENTARY GEOLOGY</span>; or the ANCIENT CHANGES of the Earth and its
+Inhabitants, as illustrated by Geological Monuments. Fourth Edition.
+<i>Thoroughly revised.</i> With 531 Woodcuts and <span class="wosp1">Plates. 8vo.</span> 12<i>s.</i></p></div>
+
+
+
+
+<h1><span class="pagenum"><a id="page1"></a>[p.1]</span>MANUAL OF ELEMENTARY GEOLOGY.</h1>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER I.</h2>
+
+<h4>ON THE DIFFERENT CLASSES OF ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Geology defined &mdash; Successive formation of the earth's
+crust &mdash; Classification of rocks according to their origin and
+age &mdash; Aqueous rocks &mdash; Their stratification and imbedded
+fossils &mdash; Volcanic rocks, with and without cones and craters &mdash; Plutonic
+rocks, and their relation to the volcanic &mdash; Metamorphic rocks and their
+probable origin &mdash; The term primitive, why erroneously applied to the
+crystalline formations &mdash; Leading division of the work.</p></div>
+
+
+<p><span class="smcap">Of</span> what materials is the earth composed, and in what manner are these
+materials arranged? These are the first inquiries with which Geology is
+occupied, a science which derives its name from the Greek &#947;&#8134;,
+<i>ge</i>, the earth, and &#955;&#959;&#947;&#959;&#962;, <i>logos</i>, a discourse. Previously to
+experience we might have imagined that investigations of this kind would
+relate exclusively to the mineral kingdom, and to the various rocks, soils,
+and metals, which occur upon the surface of the earth, or at various depths
+beneath it. But, in pursuing such researches, we soon find ourselves led on
+to consider the successive changes which have taken place in the former
+state of the earth's surface and interior, and the causes which have given
+rise to these changes; and, what is still more singular and unexpected, we
+soon become engaged in researches into the history of the animate creation,
+or of the various tribes of animals and plants which have, at different
+periods of the past, inhabited the globe.</p>
+
+<p>All are aware that the solid parts of the earth consist of distinct
+substances, such as clay, chalk, sand, limestone, coal, slate, granite, and
+the like; but previously to observation it is commonly imagined that all
+these had remained from the first in the state in which we now see
+them,&mdash;that they were created in their present form, and in their present
+position. The geologist soon comes to a different conclusion, discovering
+proofs that the external parts of the earth were not all produced in the
+beginning of things, in the state in which we now behold them, nor in an
+instant of time. On the contrary, he can show that they have acquired their
+actual configuration and condition gradually, under a great variety of
+circumstances, and at successive periods, during each of which distinct
+races of living beings <span class="pagenum"><a id="page2"></a>[p.2]</span>have flourished on the land and in the
+waters, the remains of these creatures still lying buried in the crust of
+the earth.</p>
+
+<p>By the "earth's crust," is meant that small portion of the exterior of our
+planet which is accessible to human observation, or on which we are enabled
+to reason by observations made at or near the surface. These reasonings may
+extend to a depth of several miles, perhaps ten miles; and even then it may
+be said, that such a thickness is no more than 1/400 part of the distance
+from the surface to the centre. The remark is just; but although the
+dimensions of such a crust are, in truth, insignificant when compared to
+the entire globe, yet they are vast, and of magnificent extent in relation
+to man, and to the organic beings which people our globe. Referring to this
+standard of magnitude, the geologist may admire the ample limits of his
+domain, and admit, at the same time, that not only the exterior of the
+planet, but the entire earth, is but an atom in the midst of the countless
+worlds surveyed by the astronomer.</p>
+
+<p>The materials of this crust are not thrown together confusedly; but
+distinct mineral masses, called rocks, are found to occupy definite spaces,
+and to exhibit a certain order of arrangement. The term <i>rock</i> is applied
+indifferently by geologists to all these substances, whether they be soft
+or stony, for clay and sand are included in the term, and some have even
+brought peat under this denomination. Our older writers endeavoured to
+avoid offering such violence to our language, by speaking of the component
+materials of the earth as consisting of rocks and <i>soils</i>. But there is
+often so insensible a passage from a soft and incoherent state to that of
+stone, that geologists of all countries have found it indispensable to have
+one technical term to include both, and in this sense we find <i>roche</i>
+applied in French, <i>rocca</i> in Italian, and <i>felsart</i> in German. The
+beginner, however, must constantly bear in mind, that the term rock by no
+means implies that a mineral mass is in an indurated or stony condition.</p>
+
+<p>The most natural and convenient mode of classifying the various rocks which
+compose the earth's crust, is to refer, in the first place, to their
+origin, and in the second to their relative age. I shall therefore begin by
+endeavouring briefly to explain to the student how all rocks may be divided
+into four great classes by reference to their different origin, or, in
+other words, by reference to the different circumstances and causes by
+which they have been produced.</p>
+
+<p>The first two divisions, which will at once be understood as natural, are
+the aqueous and volcanic, or the products of watery and those of igneous
+action at or near the surface.</p>
+
+<p><i>Aqueous rocks.</i>&mdash;The aqueous rocks, sometimes called the sedimentary, or
+fossiliferous, cover a larger part of the earth's surface than any others.
+These rocks are <i>stratified</i>, or divided into distinct layers, or strata.
+The term <i>stratum</i> means simply a bed, or any thing spread out or <i>strewed</i>
+over a given surface; and we infer that these strata have been generally
+spread out by the action of water, from what we daily see taking place near
+the mouths of rivers, or on <span class="pagenum"><a id="page3"></a>[p.3]</span>the land during temporary inundations.
+For, whenever a running stream charged with mud or sand, has its velocity
+checked, as when it enters a lake or sea, or overflows a plain, the
+sediment, previously held in suspension by the motion of the water, sinks,
+by its own gravity, to the bottom. In this manner layers of mud and sand
+are thrown down one upon another.</p>
+
+<p>If we drain a lake which has been fed by a small stream, we frequently find
+at the bottom a series of deposits, disposed with considerable regularity,
+one above the other; the uppermost, perhaps, may be a stratum of peat, next
+below a more dense and solid variety of the same material; still lower a
+bed of shell-marl, alternating with peat or sand, and then other beds of
+marl, divided by layers of clay. Now, if a second pit be sunk through the
+same continuous lacustrine <i>formation</i>, at some distance from the first,
+nearly the same series of beds is commonly met with, yet with slight
+variations; some, for example, of the layers of sand, clay, or marl, may be
+wanting, one or more of them having thinned out and given place to others,
+or sometimes one of the masses first examined is observed to increase in
+thickness to the exclusion of other beds.</p>
+
+<p>The term "<i>formation</i>," which I have used in the above explanation,
+expresses in geology any assemblage of rocks which have some character in
+common, whether of origin, age, or composition. Thus we speak of stratified
+and unstratified, freshwater and marine, aqueous and volcanic, ancient and
+modern, metalliferous and non-metalliferous formations.</p>
+
+<p>In the estuaries of large rivers, such as the Ganges and the Mississippi,
+we may observe, at low water, phenomena analogous to those of the drained
+lakes above mentioned, but on a grander scale, and extending over areas
+several hundred miles in length and breadth. When the periodical
+inundations subside, the river hollows out a channel to the depth of many
+yards through horizontal beds of clay and sand, the ends of which are seen
+exposed in perpendicular cliffs. These beds vary in colour, and are
+occasionally characterized by containing drift-wood or shells. The shells
+may belong to species peculiar to the river, but are sometimes those of
+marine testacea, washed into the mouth of the estuary during storms.</p>
+
+<p>The annual floods of the Nile in Egypt are well known, and the fertile
+deposits of mud which they leave on the plains. This mud is <i>stratified</i>,
+the thin layer thrown down in one season differing slightly in colour from
+that of a previous year, and being separable from it, as has been observed
+in excavations at Cairo, and other places.<a name="FNanchor_C_1" id="FNanchor_C_1"></a><a href="#Footnote_C_1" class="fnanchor">[3-A]</a></p>
+
+<p>When beds of sand, clay, and marl, containing shells and vegetable matter,
+are found arranged in a similar manner in the interior of the earth, we
+ascribe to them a similar origin; and the more we examine their characters
+in minute detail, the more exact do we find the resemblance. Thus, for
+example, at various heights and depths in the earth, and often far from
+seas, lakes, and rivers, we meet with layers <span class="pagenum"><a id="page4"></a>[p.4]</span>of rounded pebbles
+composed of different rocks mingled together. They are like the shingle of
+a sea-beach, or pebbles formed in the beds of torrents and rivers, which
+are carried down into the ocean wherever these descend from high grounds
+bordering a coast. There the gravel is spread out by the waves and currents
+over a considerable space; but during seasons of drought the torrents and
+rivers are nearly dry, and have only power to convey fine sand or mud into
+the sea. Hence, alternate layers of gravel and fine sediment accumulate
+under water, and such alternations are found by geologists in the interior
+of every continent.<a name="FNanchor_C_2" id="FNanchor_C_2"></a><a href="#Footnote_C_2" class="fnanchor">[4-A]</a></p>
+
+<p>If a stratified arrangement, and the rounded forms of pebbles, are alone
+sufficient to lead us to the conclusion that certain rocks originated under
+water, this opinion is farther confirmed by the distinct and independent
+evidence of <i>fossils</i>, so abundantly included in the earth's crust. By a
+<i>fossil</i> is meant any body, or the traces of the existence of any body,
+whether animal or vegetable, which has been buried in the earth by natural
+causes. Now the remains of animals, especially of aquatic species, are
+found almost everywhere imbedded in stratified rocks, and sometimes, in the
+case of limestone, they are in such abundance as to constitute the entire
+mass of the rock itself. Shells and corals are the most frequent, and with
+them are often associated the bones and teeth of fishes, fragments of wood,
+impressions of leaves, and other organic substances. Fossil shells, of
+forms such as now abound in the sea, are met with far inland, both near the
+surface, and at great depths below it. They occur at all heights above the
+level of the ocean, having been observed at elevations of 8000 feet in the
+Pyrenees, 10,000 in the Alps, 13,000 in the Andes, and above 16,000 feet in
+the Himalayas.<a name="FNanchor_C_3" id="FNanchor_C_3"></a><a href="#Footnote_C_3" class="fnanchor">[4-B]</a></p>
+
+<p>These shells belong mostly to marine testacea, but in some places
+exclusively to forms characteristic of lakes and rivers. Hence it is
+concluded that some ancient strata were deposited at the bottom of the sea,
+and others in lakes and estuaries.</p>
+
+<p>When geology was first cultivated, it was a general belief, that these
+marine shells and other fossils were the effects and proofs of the deluge
+of Noah; but all who have carefully investigated the phenomena have long
+rejected this doctrine. A transient flood might be supposed to leave behind
+it, here and there upon the surface, scattered heaps of mud, sand, and
+shingle, with shells confusedly intermixed; but the strata containing
+fossils are not superficial deposits, and do not simply cover the earth,
+but constitute the entire mass of mountains. Nor are the fossils mingled
+without reference to the original habits and natures of the creatures of
+which they are the memorials; those, for example, being found associated
+together which lived in deep or in shallow water, near the shore or far
+from it, in brackish or in salt water.</p>
+
+<p>It has, moreover, been a favourite notion of some modern writers, who were
+aware that fossil bodies could not all be referred to the <span class="pagenum"><a id="page5"></a>[p.5]</span>deluge,
+that they, and the strata in which they are entombed, might have been
+deposited in the bed of the ocean during the period which intervened
+between the creation of man and the deluge. They have imagined that the
+antediluvian bed of the ocean, after having been the receptacle of many
+stratified deposits, became converted, at the time of the flood, into the
+lands which we inhabit, and that the ancient continents were at the same
+time submerged, and became the bed of the present sea. This hypothesis,
+although preferable to the diluvial theory before alluded to, since it
+admits that all fossiliferous strata were successively thrown down from
+water, is yet wholly inadequate to explain the repeated revolutions which
+the earth has undergone, and the signs which the existing continents
+exhibit, in most regions, of having emerged from the ocean at an era far
+more remote than four thousand years from the present time. Ample proofs of
+these reiterated revolutions will be given in the sequel, and it will be
+seen that many distinct sets of sedimentary strata, each several hundreds
+or thousands of feet thick, are piled one upon the other in the earth's
+crust, each containing peculiar fossil animals and plants which are
+distinguishable with few exceptions from species now living. The mass of
+some of these strata consists almost entirely of corals, others are made up
+of shells, others of plants turned into coal, while some are without
+fossils. In one set of strata the species of fossils are marine; in
+another, lying immediately above or below, they as clearly prove that the
+deposit was formed in a brackish estuary or lake. When the student has more
+fully examined into these appearances, he will become convinced that the
+time required for the origin of the rocks composing the actual continents
+must have been far greater than that which is conceded by the theory above
+alluded to; and likewise that no one universal and sudden conversion of sea
+into land will account for geological appearances.</p>
+
+<p>We have now pointed out one great class of rocks, which, however they may
+vary in mineral composition, colour, grain, or other characters, external
+and internal, may nevertheless be grouped together as having a common
+origin. They have all been formed under water, in the same manner as modern
+accumulations of sand, mud, shingle, banks of shells, reefs of coral, and
+the like, and are all characterized by stratification or fossils, or by
+both.</p>
+
+<p><i>Volcanic rocks.</i>&mdash;The division of rocks which we may next consider are the
+volcanic, or those which have been produced at or near the surface whether
+in ancient or modern times, not by water, but by the action of fire or
+subterranean heat. These rocks are for the most part unstratified, and are
+devoid of fossils. They are more partially distributed than aqueous
+formations, at least in respect to horizontal extension. Among those parts
+of Europe where they exhibit characters not to be mistaken, I may mention
+not only Sicily and the country round Naples, but Auvergne, Velay, and
+Vivarais, now the departments of Puy de Dome, Haute Loire, and Ard�che,
+towards the centre and south of France, in which are several hundred
+conical hills having the forms of modern volcanos, with craters more or
+less <span class="pagenum"><a id="page6"></a>[p.6]</span>perfect on many of their summits. These cones are composed
+moreover of lava, sand, and ashes, similar to those of active volcanos.
+Streams of lava may sometimes be traced from the cones into the adjoining
+valleys, where they have choked up the ancient channels of rivers with
+solid rock, in the same manner as some modern flows of lava in Iceland have
+been known to do, the rivers either flowing beneath or cutting out a narrow
+passage on one side of the lava. Although none of these French volcanos
+have been in activity within the period of history or tradition, their
+forms are often very perfect. Some, however, have been compared to the mere
+skeletons of volcanos, the rains and torrents having washed their sides,
+and removed all the loose sand and scori�, leaving only the harder and more
+solid materials. By this erosion, and by earthquakes, their internal
+structure has occasionally been laid open to view, in fissures and ravines;
+and we then behold not only many successive beds and masses of porous lava,
+sand, and scori�, but also perpendicular walls, or <i>dikes</i>, as they are
+called, of volcanic rock, which have burst through the other materials.
+Such dikes are also observed in the structure of Vesuvius, Etna, and other
+active volcanos. They have been formed by the pouring of melted matter,
+whether from above or below, into open fissures, and they commonly traverse
+deposits of <i>volcanic tuff</i>, a substance produced by the showering down
+from the air, or incumbent waters, of sand and cinders, first shot up from
+the interior of the earth by the explosions of volcanic gases.</p>
+
+<p>Besides the parts of France above alluded to, there are other countries, as
+the north of Spain, the south of Sicily, the Tuscan territory of Italy, the
+lower Rhenish provinces, and Hungary, where spent volcanos may be seen,
+still preserving in many cases a conical form, and having craters and often
+lava-streams connected with them.</p>
+
+<p>There are also other rocks in England, Scotland, Ireland, and almost every
+country in Europe, which we infer to be of igneous origin, although they do
+not form hills with cones and craters. Thus, for example, we feel assured
+that the rock of Staffa, and that of the Giant's Causeway, called basalt,
+is volcanic, because it agrees in its columnar structure and mineral
+composition with streams of lava which we know to have flowed from the
+craters of volcanos. We find also similar basaltic and other igneous rocks
+associated with beds of <i>tuff</i> in various parts of the British Isles, and
+forming <i>dikes</i>, such as have been spoken of; and some of the strata
+through which these dikes cut are occasionally altered at the point of
+contact, as if they had been exposed to the intense heat of melted matter.</p>
+
+<p>The absence of cones and craters, and long narrow streams of superficial
+lava, in England and many other countries, is principally to be attributed
+to the eruptions having been submarine, just as a considerable proportion
+of volcanos in our own times burst out beneath the sea. But this question
+must be enlarged upon more fully in the chapters on Igneous Rocks, in which
+it will also be shown, that as different sedimentary formations, containing
+each <span class="pagenum"><a id="page7"></a>[p.7]</span>their characteristic fossils, have been deposited at
+successive periods, so also volcanic sand and scori� have been thrown out,
+and lavas have flowed over the land or bed of the sea, at many different
+epochs, or have been injected into fissures; so that the igneous as well as
+the aqueous rocks may be classed as a chronological series of monuments,
+throwing light on a succession of events in the history of the earth.</p>
+
+<p><i>Plutonic rocks</i> (Granite, &amp;c.).&mdash;We have now pointed out the existence of
+two distinct orders of mineral masses, the aqueous and the volcanic: but if
+we examine a large portion of a continent, especially if it contain within
+it a lofty mountain range, we rarely fail to discover two other classes of
+rocks, very distinct from either of those above alluded to, and which we
+can neither assimilate to deposits such as are now accumulated in lakes or
+seas, nor to those generated by ordinary volcanic action. The members of
+both these divisions of rocks agree in being highly crystalline and
+destitute of organic remains. The rocks of one division have been called
+plutonic, comprehending all the granites and certain porphyries, which are
+nearly allied in some of their characters to volcanic formations. The
+members of the other class are stratified and often slaty, and have been
+called by some the <i>crystalline schists</i>, in which group are included
+gneiss, micaceous-schist (or mica-slate), hornblende-schist, statuary
+marble, the finer kinds of roofing slate, and other rocks afterwards to be
+described.</p>
+
+<p>As it is admitted that nothing strictly analogous to these crystalline
+productions can now be seen in the progress of formation on the earth's
+surface, it will naturally be asked, on what data we can find a place for
+them in a system of classification founded on the origin of rocks. I
+cannot, in reply to this question, pretend to give the student, in a few
+words, an intelligible account of the long chain of facts and reasonings by
+which geologists have been led to infer the analogy of the rocks in
+question to others now in progress at the surface. The result, however, may
+be briefly stated. All the various kinds of granite, which constitute the
+plutonic family, are supposed to be of igneous origin, but to have been
+formed under great pressure, at considerable depths in the earth, or
+sometimes, perhaps, under a certain weight of incumbent water. Like the
+lava of volcanos, they have been melted, and have afterwards cooled and
+crystallized, but with extreme slowness, and under conditions very
+different from those of bodies cooling in the open air. Hence they differ
+from the volcanic rocks, not only by their more crystalline texture, but
+also by the absence of tuffs and breccias, which are the products of
+eruptions at the earth's surface, or beneath seas of inconsiderable depth.
+They differ also by the absence of pores or cellular cavities, to which the
+expansion of the entangled gases gives rise in ordinary lava.</p>
+
+<p>Although granite has often pierced through other strata, it has rarely, if
+ever, been observed to rest upon them, as if it had overflowed. But as this
+is continually the case with the volcanic rocks, <span class="pagenum"><a id="page8"></a>[p.8]</span>they have been
+styled, from this peculiarity, "overlying" by Dr. MacCulloch; and Mr.
+Necker has proposed the term "underlying" for the granites, to designate
+the opposite mode in which they almost invariably present themselves.</p>
+
+<p><i>Metamorphic, or stratified crystalline rocks.</i>&mdash;The fourth and last great
+division of rocks are the crystalline strata and slates, or schists, called
+gneiss, mica-schist, clay-slate, chlorite-schist, marble, and the like, the
+origin of which is more doubtful than that of the other three classes. They
+contain no pebbles, or sand, or scori�, or angular pieces of imbedded
+stone, and no traces of organic bodies, and they are often as crystalline
+as granite, yet are divided into beds, corresponding in form and
+arrangement to those of sedimentary formations, and are therefore said to
+be stratified. The beds sometimes consist of an alternation of substances
+varying in colour, composition, and thickness, precisely as we see in
+stratified fossiliferous deposits. According to the Huttonian theory, which
+I adopt as most probable, and which will be afterwards more fully
+explained, the materials of these strata were originally deposited from
+water in the usual form of sediment, but they were subsequently so altered
+by subterranean heat, as to assume a new texture. It is demonstrable, in
+some cases at least, that such a complete conversion has actually taken
+place, fossiliferous strata having exchanged an earthy for a highly
+crystalline texture for a distance of a quarter of a mile from their
+contact with granite. In some cases, dark limestones, replete with shells
+and corals, have been turned into white statuary marble, and hard clays
+into slates called mica-schist and hornblende-schist, all signs of organic
+bodies having been obliterated.</p>
+
+<p>Although we are in a great degree ignorant of the precise nature of the
+influence exerted in these cases, yet it evidently bears some analogy to
+that which volcanic heat and gases are known to produce; and the action may
+be conveniently called plutonic, because it appears to have been developed
+in those regions where plutonic rocks are generated, and under similar
+circumstances of pressure and depth in the earth. Whether hot water or
+steam permeating stratified masses, or electricity, or any other causes
+have co-operated to produce the crystalline texture, may be matter of
+speculation, but it is clear that the plutonic influence has sometimes
+pervaded entire mountain masses of strata.</p>
+
+<p>In accordance with the hypothesis above alluded to, I proposed in the first
+edition of the Principles of Geology (1833), the term "Metamorphic" for the
+altered strata, a term derived from &#956;&#949;&#964;&#945;, meta, <i>trans</i>, and
+&#956;&#959;&#961;&#966;&#951;, morphe, <i>forma</i>.</p>
+
+<p>Hence there are four great classes of rocks considered in reference to
+their origin,&mdash;the aqueous, the volcanic, the plutonic, and the
+metamorphic. In the course of this work it will be shown, that portions of
+each of these four distinct classes have originated at many successive
+periods. They have all been produced contemporaneously, and may even now be
+in the progress of formation. It is not true, as was formerly supposed,
+that all granites, together with <span class="pagenum"><a id="page9"></a>[p.9]</span>the crystalline or metamorphic
+strata, were first formed, and therefore entitled to be called "primitive,"
+and that the aqueous and volcanic rocks were afterwards superimposed, and
+should, therefore, rank as secondary in the order of time. This idea was
+adopted in the infancy of the science, when all formations, whether
+stratified or unstratified, earthy or crystalline, with or without fossils,
+were alike regarded as of aqueous origin. At that period it was naturally
+argued, that the foundation must be older than the superstructure; but it
+was afterwards discovered, that this opinion was by no means in every
+instance a legitimate deduction from facts; for the inferior parts of the
+earth's crust have often been modified, and even entirely changed, by the
+influence of volcanic and other subterranean causes, while superimposed
+formations have not been in the slightest degree altered. In other words,
+the destroying and renovating processes have given birth to new rocks
+below, while those above, whether crystalline or fossiliferous, have
+remained in their ancient condition. Even in cities, such as Venice and
+Amsterdam, it cannot be laid down as universally true, that the upper parts
+of each edifice, whether of brick or marble, are more modern than the
+foundations on which they rest, for these often consist of wooden piles,
+which may have rotted and been replaced one after the other, without the
+least injury to the buildings above; meanwhile, these may have required
+scarcely any repair, and may have been constantly inhabited. So it is with
+the habitable surface of our globe, in its relation to large masses of rock
+immediately below: it may continue the same for ages, while subjacent
+materials, at a great depth, are passing from a solid to a fluid state, and
+then reconsolidating, so as to acquire a new texture.</p>
+
+<p>As all the crystalline rocks may, in some respects, be viewed as belonging
+to one great family, whether they be stratified or unstratified, plutonic
+or metamorphic, it will often be convenient to speak of them by one common
+name. It being now ascertained, as above stated, that they are of very
+different ages, sometimes newer than the strata called secondary, the term
+primary, which was formerly used for the whole, must be abandoned, as it
+would imply a manifest contradiction. It is indispensable, therefore, to
+find a new name, one which must not be of chronological import, and must
+express, on the one hand, some peculiarity equally attributable to granite
+and gneiss (to the plutonic as well as the <i>altered</i> rocks), and, on the
+other, must have reference to characters in which those rocks differ, both
+from the volcanic and from the <i>unaltered</i> sedimentary strata. I proposed
+in the Principles of Geology (first edition, vol. iii.), the term
+"hypogene" for this purpose, derived from &#8017;&#960;&#959;, <i>under</i>, and
+&#947;&#953;&#957;&#959;&#956;&#945;&#953;, <i>to be</i>, or <i>to be born</i>; a word implying the theory that
+granite, gneiss, and the other crystalline formations are alike
+<i>nether-formed</i> rocks, or rocks which have not assumed their present form
+and structure at the surface. This occurs in the lowest place in the order
+of superposition. Even in regions such as the Alps, where some masses of
+granite and gneiss can be shown to be of comparatively modern date,
+belonging, for example, to the period hereafter <span class="pagenum"><a id="page10"></a>[p.10]</span>to be described as
+tertiary, they are still <i>underlying</i> rocks. They never repose on the
+volcanic or trappean formations, nor on strata containing organic remains.
+They are <i>hypogene</i>, as "being under" all the rest.</p>
+
+<p>From what has now been said, the reader will understand that each of the
+four great classes of rocks may be studied under two distinct points of
+view; first, they may be studied simply as mineral masses deriving their
+origin from particular causes, and having a certain composition, form, and
+position in the earth's crust, or other characters both positive and
+negative, such as the presence or absence of organic remains. In the second
+place, the rocks of each class may be viewed as a grand chronological
+series of monuments, attesting a succession of events in the former history
+of the globe and its living inhabitants.</p>
+
+<p>I shall accordingly proceed to treat of each family of rocks; first, in
+reference to those characters which are not chronological, and then in
+particular relation to the several periods when they were formed.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER II.</h2>
+
+<h4>AQUEOUS ROCKS&mdash;THEIR COMPOSITION AND FORMS OF STRATIFICATION.</h4>
+
+<div class="blq1">
+<p class="indentm2">Mineral composition of strata &mdash; Arenaceous
+rocks &mdash; Argillaceous &mdash; Calcareous &mdash; Gypsum &mdash; Forms of
+stratification &mdash; Original horizontality &mdash; Thinning out &mdash; Diagonal
+arrangement &mdash; Ripple mark.</p></div>
+
+
+<p><span class="smcap">In</span> pursuance of the arrangement explained in the last chapter, we shall
+begin by examining the aqueous or sedimentary rocks, which are for the most
+part distinctly stratified, and contain fossils. We may first study them
+with reference to their mineral composition, external appearance, position,
+mode of origin, organic contents, and other characters which belong to them
+as aqueous formations, independently of their age, and we may afterwards
+consider them chronologically or with reference to the successive
+geological periods when they originated.</p>
+
+<p>I have already given an outline of the data which led to the belief that
+the stratified and fossiliferous rocks were originally deposited under
+water; but, before entering into a more detailed investigation, it will be
+desirable to say something of the ordinary materials of which such strata
+are composed. These may be said to belong principally to three divisions,
+the arenaceous, the argillaceous, and the calcareous, which are formed
+respectively of sand, clay, and carbonate of lime. Of these, the
+arenaceous, or sandy masses, are chiefly made up of siliceous or flinty
+grains; the argillaceous, or clayey, of a <span class="pagenum"><a id="page11"></a>[p.11]</span>mixture of siliceous
+matter, with a certain proportion, about a fourth in weight, of aluminous
+earth; and, lastly, the calcareous rocks or limestones consist of carbonic
+acid and lime.</p>
+
+<p><i>Arenaceous or siliceous rocks.</i>&mdash;To speak first of the sandy division:
+beds of loose sand are frequently met with, of which the grains consist
+entirely of silex, which term comprehends all purely siliceous minerals, as
+quartz and common flint. Quartz is silex in its purest form; flint usually
+contains some admixture of alumine and oxide of iron. The siliceous grains
+in sand are usually rounded, as if by the action of running water.
+Sandstone is an aggregate of such grains, which often cohere together
+without any visible cement, but more commonly are bound together by a
+slight quantity of siliceous or calcareous matter, or by iron or clay.</p>
+
+<p>Pure siliceous rocks may be known by not effervescing when a drop of
+nitric, sulphuric, or other acid is applied to them, or by the grains not
+being readily scratched or broken by ordinary pressure. In nature there is
+every intermediate gradation, from perfectly loose sand, to the hardest
+sandstone. In <i>micaceous sandstones</i> mica is very abundant; and the thin
+silvery plates into which that mineral divides, are often arranged in
+layers parallel to the planes of stratification, giving a slaty or
+laminated texture to the rock.</p>
+
+<p>When sandstone is coarse-grained, it is usually called <i>grit</i>. If the
+grains are rounded, and large enough to be called pebbles, it becomes a
+<i>conglomerate</i>, or <i>pudding-stone</i>, which may consist of pieces of one or
+of many different kinds of rock. A conglomerate, therefore, is simply
+gravel bound together by a cement.</p>
+
+<p><i>Argillaceous rocks.</i>&mdash;Clay, strictly speaking, is a mixture of silex or
+flint with a large proportion, usually about one fourth, of alumine, or
+argil; but, in common language, any earth which possesses sufficient
+ductility, when kneaded up with water, to be fashioned like paste by the
+hand, or by the potter's lathe, is called a <i>clay</i>; and such clays vary
+greatly in their composition, and are, in general, nothing more than mud
+derived from the decomposition or wearing down of various rocks. The purest
+clay found in nature is porcelain clay, or kaolin, which results from the
+decomposition of a rock composed of felspar and quartz, and it is almost
+always mixed with quartz.<a name="FNanchor_D_1" id="FNanchor_D_1"></a><a href="#Footnote_D_1" class="fnanchor">[11-A]</a> <i>Shale</i> has also the property, like clay,
+of becoming plastic in water: it is a more solid form of clay, or
+argillaceous matter, condensed by pressure. It usually divides into
+irregular lamin�.</p>
+
+<p>One general character of all argillaceous rocks is to give out a peculiar,
+earthy odour when breathed upon, which is a test of the presence of
+alumine, although it does not belong to pure alumine, but, apparently, to
+the combination of that substance with oxide of iron.<a name="FNanchor_D_2" id="FNanchor_D_2"></a><a href="#Footnote_D_2" class="fnanchor">[11-B]</a></p>
+
+<p><span class="pagenum"><a id="page12"></a>[p.12]</span><i>Calcareous rocks.</i>&mdash;This division comprehends those rocks which,
+like chalk, are composed chiefly of lime and carbonic acid. Shells and
+corals are also formed of the same elements, with the addition of animal
+matter. To obtain pure lime it is necessary to calcine these calcareous
+substances, that is to say, to expose them to heat of sufficient intensity
+to drive off the carbonic acid, and other volatile matter, without
+vitrifying or melting the lime itself. White chalk is often pure carbonate
+of lime; and this rock, although usually in a soft and earthy state, is
+sometimes sufficiently solid to be used for building, and even passes into
+a <i>compact</i> stone, or a stone of which the separate parts are so minute as
+not to be distinguishable from each other by the naked eye.</p>
+
+<p>Many limestones are made up entirely of minute fragments of shells and
+coral, or of calcareous sand cemented together. These last might be called
+"calcareous sandstones;" but that term is more properly applied to a rock
+in which the grains are partly calcareous and partly siliceous, or to
+quartzose sandstones, having a cement of carbonate of lime.</p>
+
+<p>The variety of limestone called "oolite" is composed of numerous small
+egg-like grains, resembling the roe of a fish, each of which has usually a
+small fragment of sand as a nucleus, around which concentric layers of
+calcareous matter have accumulated.</p>
+
+<p>Any limestone which is sufficiently hard to take a fine polish is called
+<i>marble</i>. Many of these are fossiliferous; but statuary marble, which is
+also called saccharine limestone, as having a texture resembling that of
+loaf-sugar, is devoid of fossils, and is in many cases a member of the
+metamorphic series.</p>
+
+<p><i>Siliceous limestone</i> is an intimate mixture of carbonate of lime and
+flint, and is harder in proportion as the flinty matter predominates.</p>
+
+<p>The presence of carbonate of lime in a rock may be ascertained by applying
+to the surface a small drop of diluted sulphuric, nitric, or muriatic
+acids, or strong vinegar; for the lime, having a greater chemical affinity
+for any one of these acids than for the carbonic, unites immediately with
+them to form new compounds, thereby becoming a sulphate, nitrate, or
+muriate of lime. The carbonic acid, when thus liberated from its union with
+the lime, escapes in a gaseous form, and froths up or effervesces as it
+makes its way in small bubbles through the drop of liquid. This
+effervescence is brisk or feeble in proportion as the limestone is pure or
+impure, or, in other words, according to the quantity of foreign matter
+mixed with the carbonate of lime. Without the aid of this test, the most
+experienced eye cannot always detect the presence of carbonate of lime in
+rocks.</p>
+
+<p>The above-mentioned three classes of rocks, the siliceous, argillaceous,
+and calcareous, pass continually into each other, and rarely occur in a
+perfectly separate and pure form. Thus it is an exception to the general
+rule to meet with a limestone as pure as ordinary white chalk, or with clay
+as aluminous as that used in Cornwall for porcelain, or with sand so
+entirely composed of siliceous grains as the white sand of Alum Bay in the
+Isle of Wight, or sandstone so pure <span class="pagenum"><a id="page13"></a>[p.13]</span>as the grit of Fontainebleau,
+used for pavement in France. More commonly we find sand and clay, or clay
+and marl, intermixed in the same mass. When the sand and clay are each in
+considerable quantity, the mixture is called <i>loam</i>. If there is much
+calcareous matter in clay it is called <i>marl</i>; but this term has
+unfortunately been used so vaguely, as often to be very ambiguous. It has
+been applied to substances in which there is no lime; as, to that red loam
+usually called red marl in certain parts of England. Agriculturists were in
+the habit of calling any soil a marl, which, like true marl, fell to pieces
+readily on exposure to the air. Hence arose the confusion of using this
+name for soils which, consisting of loam, were easily worked by the plough,
+though devoid of lime.</p>
+
+<p><i>Marl slate</i> bears the same relation to marl which shale bears to clay,
+being a calcareous shale. It is very abundant in some countries, as in the
+Swiss Alps. Argillaceous or marly limestone is also of common occurrence.</p>
+
+<p>There are few other kinds of rock which enter so largely into the
+composition of sedimentary strata as to make it necessary to dwell here on
+their characters. I may, however, mention two others,&mdash;magnesian limestone
+or dolomite, and gypsum. <i>Magnesian limestone</i> is composed of carbonate of
+lime and carbonate of magnesia; the proportion of the latter amounting in
+some cases to nearly one half. It effervesces much more slowly and feebly
+with acids than common limestone. In England this rock is generally of a
+yellowish colour; but it varies greatly in mineralogical character, passing
+from an earthy state to a white compact stone of great hardness.
+<i>Dolomite</i>, so common in many parts of Germany and France, is also a
+variety of magnesian limestone, usually of a granular texture.</p>
+
+<p><i>Gypsum.</i>&mdash;Gypsum is a rock composed of sulphuric acid, lime, and water. It
+is usually a soft whitish-yellow rock, with a texture resembling that of
+loaf-sugar, but sometimes it is entirely composed of lenticular crystals.
+It is insoluble in acids, and does not effervesce like chalk and dolomite,
+because it does not contain carbonic acid gas, or fixed air, the lime being
+already combined with sulphuric acid, for which it has a stronger affinity
+than for any other. Anhydrous gypsum is a rare variety, into which water
+does not enter as a component part. Gypseous marl is a mixture of gypsum
+and marl. Alabaster is a granular and compact variety of gypsum found in
+masses large enough to be used in sculpture and architecture. It is
+sometimes a pure snow-white substance, as that of Volterra in Tuscany, well
+known as being carved for works of art in Florence and Leghorn. It is a
+softer stone than marble, and more easily wrought.</p>
+
+<p><i>Forms of stratification.</i>&mdash;A series of strata sometimes consists of one of
+the above rocks, sometimes of two or more in alternating beds. Thus, in the
+coal districts of England, for example, we often pass through several beds
+of sandstone, some of finer, others of coarser grain, some white, others of
+a dark colour, and below these, layers of shale and sandstone or beds of
+shale, divisible into leaf-like lamin�, <span class="pagenum"><a id="page14"></a>[p.14]</span>and containing beautiful
+impressions of plants. Then again we meet with beds of pure and impure
+coal, alternating with shales and sandstones, and underneath the whole,
+perhaps, are calcareous strata, or beds of limestone, filled with corals
+and marine shells, each bed distinguishable from another by certain
+fossils, or by the abundance of particular species of shells or zoophytes.</p>
+
+<p>This alternation of different kinds of rock produces the most distinct
+stratification; and we often find beds of limestone and marl, conglomerate
+and sandstone, sand and clay, recurring again and again, in nearly regular
+order, throughout a series of many hundred strata. The causes which may
+produce these phenomena are various, and have been fully discussed in my
+treatise on the modern changes of the earth's surface.<a name="FNanchor_D_3" id="FNanchor_D_3"></a><a href="#Footnote_D_3" class="fnanchor">[14-A]</a> It is there
+seen that rivers flowing into lakes and seas are charged with sediment,
+varying in quantity, composition, colour, and grain according to the
+seasons; the waters are sometimes flooded and rapid, at other periods low
+and feeble; different tributaries, also, draining peculiar countries and
+soils, and therefore charged with peculiar sediment, are swollen at
+distinct periods. It was also shown that the waves of the sea and currents
+undermine the cliffs during wintry storms, and sweep away the materials
+into the deep, after which a season of tranquillity succeeds, when nothing
+but the finest mud is spread by the movements of the ocean over the same
+submarine area.</p>
+
+<p>It is not the object of the present work to give a description of these
+operations, repeated as they are, year after year, and century after
+century; but I may suggest an explanation of the manner in which some
+micaceous sandstones have originated, those in which we see innumerable
+thin layers of mica dividing layers of fine quartzose sand. I observed the
+same arrangement of materials in recent mud deposited in the estuary of La
+Roche St. Bernard in Brittany, at the mouth of the Loire. The surrounding
+rocks are of gneiss, which, by its waste, supplies the mud: when this dries
+at low water, it is found to consist of brown laminated clay, divided by
+thin seams of mica. The separation of the mica in this case, or in that of
+micaceous sandstones, may be thus understood. If we take a handful of
+quartzose sand, mixed with mica, and throw it into a clear running stream,
+we see the materials immediately sorted by the water, the grains of quartz
+falling almost directly to the bottom, while the plates of mica take a much
+longer time to reach the bottom, and are carried farther down the stream.
+At the first instant the water is turbid, but immediately after the flat
+surfaces of the plates of mica are seen alone reflecting a silvery light,
+as they descend slowly, to form a distinct micaceous lamina. The mica is
+the heavier mineral of the two; but it remains longer suspended, owing to
+its great extent of surface. It is easy, therefore, to perceive that where
+such mud is acted upon by a river or tidal current, the thin plates of mica
+will be carried <span class="pagenum"><a id="page15"></a>[p.15]</span>farther, and not deposited in the same places as
+the grains of quartz; and since the force and velocity of the stream varies
+from time to time, layers of mica or of sand will be thrown down
+successively on the same area.</p>
+
+<p><i>Original horizontality.</i>&mdash;It has generally been said that the upper and
+under surfaces of strata, or the planes of stratification, as they are
+termed, are parallel. Although this is not strictly true, they make an
+approach to parallelism, for the same reason that sediment is usually
+deposited at first in nearly horizontal layers. The reason of this
+arrangement can by no means be attributed to an original evenness or
+horizontality in the bed of the sea; for it is ascertained that in those
+places where no matter has been recently deposited, the bottom of the ocean
+is often as uneven as that of the dry land, having in like manner its
+hills, valleys, and ravines. Yet if the sea should sink, or the water be
+removed near the mouth of a large river where a delta has been forming, we
+should see extensive plains of mud and sand laid dry, which, to the eye,
+would appear perfectly level, although, in reality, they would slope gently
+from the land towards the sea.</p>
+
+<p>This tendency in newly-formed strata to assume a horizontal position arises
+principally from the motion of the water, which forces along particles of
+sand or mud at the bottom, and causes them to settle in hollows or
+depressions, where they are less exposed to the force of a current than
+when they are resting on elevated points. The velocity of the current and
+the motion of the superficial waves diminish from the surface downwards,
+and are least in those depressions where the water is deepest.</p>
+
+<a id="img013" name="img013"></a>
+<div class="floatleft smaller">
+<p>Fig. 1.</p>
+<img src="images/img013.jpg" width="200" height="062" alt="" title=""></div>
+
+<p>A good illustration of the principle here alluded to may be sometimes seen
+in the neighbourhood of a volcano, when a section, whether natural or
+artificial, has laid open to view a succession of various-coloured layers
+of sand and ashes, which have fallen in showers upon uneven ground. Thus
+let A B (<a href="#img013">fig. 1.</a>) be two ridges, with an intervening valley. These original
+inequalities of the surface have been gradually effaced by beds of sand and
+ashes <i>c</i>, <i>d</i>, <i>e</i>, the surface at e being quite level. It will be seen
+that although the materials of the first layers have accommodated
+themselves in a great degree to the shape of the ground A B, yet each bed
+is thickest at the bottom. At first a great many particles would be carried
+by their own gravity down the steep sides of A and B, and others would
+afterwards be blown by the wind as they fell off the ridges, and would
+settle in the hollow, which would thus become more and more effaced as the
+strata accumulated from <i>c</i> to <i>e</i>. This levelling operation may perhaps be
+rendered more clear to the student by supposing a number of parallel
+trenches to be dug in a plain of moving sand, like the African desert, in
+which case the wind would soon cause all signs of these trenches to
+disappear, and the surface would be as uniform as before. Now, water in
+<span class="pagenum"><a id="page16"></a>[p.16]</span>motion can exert this levelling power on similar materials more
+easily than air, for almost all stones lose in water more than a third of
+the weight which they have in air, the specific gravity of rocks being in
+general as 2<span class="smaller"><sup>1</sup>/<sub>2</sub></span> when compared to that of water, which is estimated at 1.
+But the buoyancy of sand or mud would be still greater in the sea, as the
+density of salt water exceeds that of fresh.</p>
+
+<p>Yet, however uniform and horizontal may be the surface of new deposits in
+general, there are still many disturbing causes, such as eddies in the
+water, and currents moving first in one and then in another direction,
+which frequently cause irregularities. We may sometimes follow a bed of
+limestone, shale, or sandstone, for a distance of many hundred yards
+continuously; but we generally find at length that each individual stratum
+thins out, and allows the beds which were previously above and below it to
+meet. If the materials are coarse, as in grits and conglomerates, the same
+beds can rarely be traced many yards without varying in size, and often
+coming to an end abruptly. (See <a href="#img014">fig. 2.</a>)</p>
+
+<a id="img014" name="img014"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 2.</p>
+<img src="images/img014.jpg" width="400" height="076" alt="" title="">
+<p>Section of strata of sandstone, grit, and
+conglomerate.</p></div>
+
+<a id="img015" name="img015"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 3.</p>
+<img src="images/img015.jpg" width="500" height="473" alt="" title="">
+<p>Section of sand at Sandy Hill, near Biggleswade,
+Bedfordshire. Height 20 <span class="wosp05">feet. (Greensand</span> formation.)</p></div>
+
+<p><i>Diagonal or Cross Stratification.</i>&mdash;There is also another phenomenon of
+frequent occurrence. We find a series of larger strata, each of which is
+composed of a number of minor layers placed obliquely to the general planes
+of stratification. To this diagonal arrangement the name of "false or cross
+stratification" has been given. Thus in the annexed section (<a href="#img015">fig. 3.</a>) we
+see seven or eight <span class="pagenum"><a id="page17"></a>[p.17]</span>large beds of loose sand, yellow and brown, and
+the lines <i>a</i>, <i>b</i>, <i>c</i>, mark some of the principal planes of
+stratification, which are nearly horizontal. But the greater part of the
+subordinate lamin� do not conform to these planes, but have often a steep
+slope, the inclination being sometimes towards opposite points of the
+compass. When the sand is loose and incoherent, as in the case here
+represented, the deviation from parallelism of the slanting lamin� cannot
+possibly be accounted for by any re-arrangement of the particles acquired
+during the consolidation of the rock. In what manner then can such
+irregularities be due to original deposition? We must suppose that at the
+bottom of the sea, as well as in the beds of rivers, the motions of waves,
+currents, and eddies often cause mud, sand, and gravel to be thrown down in
+heaps on particular spots, instead of being spread out uniformly over a
+wide area. Sometimes, when banks are thus formed, currents may cut passages
+through them, just as a river forms its bed. Suppose the bank A (<a href="#img016">fig. 4.</a>)
+to be thus formed with a steep sloping side, and the water being in a
+tranquil state, the layer of sediment No. 1. is thrown down upon it,
+conforming nearly to its surface. Afterwards the other layers, 2, 3, 4, may
+be deposited in succession, so that the bank B C D is formed. If the
+current then increases in velocity, it may cut away the upper portion of
+this mass down to the dotted line <i>e</i> (<a href="#img016">fig. 4.</a>), and deposit the materials
+thus removed farther on, so as to form the layers 5, 6, 7, 8. We have now
+the bank B C D E (<a href="#img017">fig. 5.</a>), of which the surface is almost level, and on
+which the nearly horizontal layers, 9, 10, 11, may then accumulate. It was
+shown in <a href="#img015">fig. 3.</a> that the diagonal layers of successive strata may
+sometimes have an opposite slope. This is well seen in some cliffs of loose
+sand on the Suffolk coast. A portion of one of these is represented in <a href="#img018">fig.
+6.</a>, where the layers, of which there are about six in the thickness of an
+inch, are composed of quartzose grains. This arrangement may have been due
+to the altered direction of the tides and currents in the same place.</p>
+
+<a id="img016" name="img016"></a>
+<div class="figcenter smaller">
+<p>Fig. 4.</p>
+<img src="images/img016.jpg" width="500" height="140" alt="" title=""></div>
+
+<a id="img017" name="img017"></a>
+<div class="figcenter smaller">
+<p class="martop2">Fig. 5.</p>
+<img src="images/img017.jpg" width="500" height="113" alt="" title=""></div>
+
+<a id="img018" name="img018"></a>
+<div class="figcenter smaller">
+<p class="martop2">Fig. 6.</p>
+<img src="images/img018.jpg" width="400" height="192" alt="" title="">
+<p>Cliff between Mismer and Dunwich.</p></div>
+
+<span class="pagenum"><a id="page18"></a>[p.18]</span>
+<a id="img019" name="img019"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 7.</p>
+<img src="images/img019.jpg" width="500" height="207" alt="" title="">
+<p>Section from Monte Calvo to the sea by the
+valley of Magnan, near Nice.</p>
+<ul class="smaller martopm05 leftal">
+<li>A. Dolomite and sandstone. (Greensand formation?)</li>
+<li><i>a</i>, <i>b</i>, <i>d</i>. Beds of gravel and sand.</li>
+<li><i>c.</i> Fine marl and sand of St. Madeleine, with marine shells.</li>
+</ul></div>
+
+<p>The description above given of the slanting position of the minor layers
+constituting a single stratum is in certain cases applicable on a much
+grander scale to masses several hundred feet thick, and many miles in
+extent. A fine example may be seen at the base of the Maritime Alps near
+Nice. The mountains here terminate abruptly in the sea, so that a depth of
+many hundred fathoms is often found within a stone's throw of the beach,
+and sometimes a depth of 3000 feet within half a mile. But at certain
+points, strata of sand, marl, or conglomerate, intervene between the shore
+and the mountains, as in the annexed <a href="#img019">fig. 7.</a>, where a vast succession of
+slanting beds of gravel and sand may be traced from the sea to Monte Calvo,
+a distance of no less than 9 miles in a straight line. The dip of these
+beds is remarkably uniform, being always southward or towards the
+Mediterranean, at an angle of about 25�. They are exposed to view in nearly
+vertical precipices, varying from 200 to 600 feet in height, which bound
+the valley through which the river Magnan flows. Although in a general
+view, the strata appear to be parallel and uniform, they are nevertheless
+found, when examined closely, to be wedge-shaped, and to thin out when
+followed for a few hundred feet or yards, so that we may suppose them to
+have been thrown down originally upon the side of a steep bank, where a
+river or alpine torrent discharged itself into a deep and tranquil sea, and
+formed a delta, which advanced gradually from the base of Monte Calvo to a
+distance of 9 miles from the original shore. If subsequently this part of
+the Alps and bed of the sea were raised 700 feet, the coast would acquire
+its present configuration, the delta would emerge, and a deep channel might
+then be cut through it by a river.</p>
+
+<p>It is well known that the torrents and streams, which now descend from the
+alpine declivities to the shore, bring down annually, when the snow melts,
+vast quantities of shingle and sand, and then, as they subside, fine mud,
+while in summer they are nearly or entirely dry; so that it may be safely
+assumed, that deposits like those of the valley of the Magnan, consisting
+of coarse gravel alternating with fine sediment, are still in progress at
+many points, as, for instance, at the mouth of the Var. They must advance
+upon the Mediterranean in the form of great shoals terminating in a steep
+talus; such being the <span class="pagenum"><a id="page19"></a>[p.19]</span>original mode of accumulation of all coarse
+materials conveyed into deep water, especially where they are composed in
+great part of pebbles, which cannot be transported to indefinite distances
+by currents of moderate velocity. By inattention to facts and inferences of
+this kind, a very exaggerated estimate has sometimes been made of the
+supposed depth of the ancient ocean. There can be no doubt, for example,
+that the strata <i>a</i>, <a href="#img019">fig. 7.</a>, or those nearest to Monte Calvo, are older
+than those indicated by <i>b</i>, and these again were formed before <i>c</i>; but
+the vertical depth of gravel and sand in any one place cannot be proved to
+amount even to 1000 feet, although it may perhaps be much greater, yet
+probably never exceeding at any point 3000 or 4000 feet. But were we to
+assume that all the strata were once horizontal, and that their present dip
+or inclination was due to subsequent movements, we should then be forced to
+conclude, that a sea 9 miles deep had been filled up with alternate layers
+of mud and pebbles thrown down one upon another.</p>
+
+<p>In the locality now under consideration, situated a few miles to the west
+of Nice, there are many geological data, the details of which cannot be
+given in this place, all leading to the opinion, that when the deposit of
+the Magnan was formed, the shape and outline of the alpine declivities and
+the shore greatly resembled what we now behold at many points in the
+neighbourhood. That the beds, a, b, c, d, are of comparatively modern date
+is proved by this fact, that in seams of loamy marl intervening between the
+pebbly beds are fossil shells, half of which belong to species now living
+in the Mediterranean.</p>
+
+<a id="img020" name="img020"></a>
+<div class="figcenter smaller">
+<p>Fig. 8.</p>
+<img src="images/img020.jpg" width="483" height="500" alt="" title="">
+<p>Slab of ripple-marked (new red) sandstone from
+Cheshire.</p></div>
+
+<p><i>Ripple mark.</i>&mdash;The ripple mark, so common on the surface of sandstones of
+all ages (see <a href="#img020">fig. 8.</a>), and which is so often seen on the <span class="pagenum"><a id="page20"></a>[p.20]</span>
+sea-shore at low tide, seems to originate in the drifting of materials
+along the bottom of the water, in a manner very similar to that which may
+explain the inclined layers above described. This ripple is not entirely
+confined to the beach between high and low water mark, but is also produced
+on sands which are constantly covered by water. Similar undulating ridges
+and furrows may also be sometimes seen on the surface of drift snow and
+blown sand. The following is the manner in which I once observed the motion
+of the air to produce this effect on a large extent of level beach, exposed
+at low tide near Calais. Clouds of fine white sand were blown from the
+neighbouring dunes, so as to cover the shore, and whiten a dark level
+surface of sandy mud, and this fresh covering of sand was beautifully
+rippled. On levelling all the small ridges and furrows of this ripple over
+an area of several yards square, I saw them perfectly restored in about ten
+minutes, the general direction of the ridges being always at right angles
+to that of the wind. The restoration began by the appearance here and there
+of small detached heaps of sand, which soon lengthened and joined together,
+so as to form long sinuous ridges with intervening furrows. Each ridge had
+one side slightly inclined, and the other steep; the lee-side being always
+steep, as <i>b, c,&mdash;d, e</i>; the windward-side a gentle slope, as <i>a, b,&mdash;c,
+d</i>, <a href="#img021">fig. 9.</a> When a gust of wind blew with sufficient force to drive along a
+cloud of sand, all the ridges were seen to be in motion at once, each
+encroaching on the furrow before it, and, in the course of a few minutes,
+filling the place which the furrows had occupied. The mode of advance was
+by the continual drifting of grains of sand up the slopes <i>a b</i> and <i>c d</i>,
+many of which grains, when they arrived at <i>b</i> and <i>d</i>, fell over the
+scarps <i>b c</i> and <i>d e</i>, and were under shelter from the wind; so that they
+remained stationary, resting, according to their shape and momentum, on
+different parts of the descent, and a few only rolling to the bottom. In
+this manner each ridge was distinctly seen to move slowly on as often as
+the force of the wind augmented. Occasionally part of a ridge, advancing
+more rapidly than the rest, overtook the ridge immediately before it, and
+became confounded with it, thus causing those bifurcations and branches
+which are so common, and two of which are seen in the slab, <a href="#img020">fig. 8.</a> We may
+observe this configuration in sandstones of all ages, and in them also, as
+now on the sea-coast, we may often detect two systems of ripples
+interfering with each other; one more ancient and half effaced, and a newer
+one, in which the grooves and ridges are more distinct, and in a different
+direction. This crossing of two sets of ripples arises from a change of
+wind, and the new direction in which the waves are thrown on the shore.</p>
+
+<a id="img021" name="img021"></a>
+<div class="figcenter smaller">
+<p>Fig. 9.</p>
+<img src="images/img021.jpg" width="500" height="058" alt="" title=""></div>
+
+<p>The ripple mark is usually an indication of a sea-beach, or of water from 6
+to 10 feet deep, for the agitation caused by waves even <span class="pagenum"><a id="page21"></a>[p.21]</span>during
+storms extends to a very slight depth. To this rule, however, there are
+some exceptions, and recent ripple marks have been observed at the depth of
+60 or 70 feet. It has also been ascertained that currents or large bodies
+of water in motion may disturb mud and sand at the depth of 300 or even 450
+feet.<a name="FNanchor_D_4" id="FNanchor_D_4"></a><a href="#Footnote_D_4" class="fnanchor">[21-A]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER III.</h2>
+
+<h4>ARRANGEMENT OF FOSSILS IN STRATA&mdash;FRESHWATER AND MARINE.</h4>
+
+<div class="blq1">
+<p class="indentm2">Successive deposition indicated by fossils &mdash; Limestones formed of
+corals and shells Proofs of gradual increase of strata derived from
+fossils &mdash; Serpula attached to spatangus &mdash; Wood bored by
+Teredina &mdash; Tripoli and semi-opal formed of infusoria &mdash; Chalk derived
+principally from organic bodies &mdash; Distinction of freshwater from marine
+formations &mdash; Genera of freshwater and land shells &mdash; Rules for
+recognizing marine testacea &mdash; Gyrogonite and chara &mdash; Freshwater
+fishes &mdash; Alternation of marine and freshwater deposits &mdash; Lym-Fiord.</p></div>
+
+
+<p><span class="smcap">Having</span> in the last chapter considered the forms of stratification so far as
+they are determined by the arrangement of inorganic matter, we may now turn
+our attention to the manner in which organic remains are distributed
+through stratified deposits. We should often be unable to detect any signs
+of stratification or of successive deposition, if particular kinds of
+fossils did not occur here and there at certain depths in the mass. At one
+level, for example, univalve shells of some one or more species
+predominate; at another, bivalve shells; and at a third, corals; while in
+some formations we find layers of vegetable matter, commonly derived from
+land plants, separating strata.</p>
+
+<p>It may appear inconceivable to a beginner how mountains, several thousand
+feet thick, can have become filled with fossils from top to bottom; but the
+difficulty is removed, when he reflects on the origin of stratification, as
+explained in the last chapter, and allows sufficient time for the
+accumulation of sediment. He must never lose sight of the fact that, during
+the process of deposition, each separate layer was once the uppermost, and
+covered immediately by the water in which aquatic animals lived. Each
+stratum in fact, however far it may now lie beneath the surface, was once
+in the state of shingle, or loose sand or soft mud at the bottom of the
+sea, in which shells and other bodies easily became enveloped.</p>
+
+<p>By attending to the nature of these remains, we are often enabled to
+determine whether the deposition was slow or rapid, whether it took place
+in a deep or shallow sea, near the shore or far from land, and whether the
+water was salt, brackish, or fresh. Some limestones <span class="pagenum"><a id="page22"></a>[p.22]</span>consist almost
+exclusively of corals, and in many cases it is evident that the present
+position of each fossil zoophyte has been determined by the manner in which
+it grew originally. The axis of the coral, for example, if its natural
+growth is erect, still remains at right angles to the plane of
+stratification. If the stratum be now horizontal, the round spherical heads
+of certain species continue uppermost, and their points of attachment are
+directed downwards. This arrangement is sometimes repeated throughout a
+great succession of strata. From what we know of the growth of similar
+zoophytes in modern reefs, we infer that the rate of increase was extremely
+slow, and some of the fossils must have flourished for ages like forest
+trees, before they attained so large a size. During these ages, the water
+remained clear and transparent, for such corals cannot live in turbid
+water.</p>
+
+<a id="img022" name="img022"></a>
+<div class="floatleft smaller width275">
+<p>Fig. 10.</p>
+<img src="images/img022.jpg" width="260" height="400" alt="" title="">
+<p>Fossil <i>Gryph�a</i>, covered both on the outside and
+inside with fossil serpul�.</p></div>
+
+<p>In like manner, when we see thousands of full-grown shells dispersed every
+where throughout a long series of strata, we cannot doubt that time was
+required for the multiplication of successive generations; and the evidence
+of slow accumulation is rendered more striking from the proofs, so often
+discovered, of fossil bodies having lain for a time on the floor of the
+ocean after death before they were imbedded in sediment. Nothing, for
+example, is more common than to see fossil oysters in clay, with serpul�,
+or barnacles (acorn-shells), or corals, and other creatures, attached to
+the inside of the valves, so that the mollusk was certainly not buried in
+argillaceous mud the moment it died. There must have been an interval
+during which it was still surrounded with clear water, when the testacea,
+now adhering to it, grew from an embryo state to full maturity. Attached
+shells which are merely external, like some of the serpul� (<i>a</i>) in the
+annexed figure (<a href="#img022">fig. 10.</a>), may often have grown upon an oyster or other
+shell while the animal within was still living; but if they are found on
+the inside, it could only happen after the death of the inhabitant of the
+shell which affords the support. Thus, in <a href="#img022">fig. 10.</a>, it will be seen that
+two serpul� have grown on the interior, one of them exactly on the place
+where the adductor muscle of the <i>Gryph�a</i> (a kind of oyster) was fixed.</p>
+
+<p>Some fossil shells, even if simply attached to the <i>outside</i> of others,
+bear full testimony to the conclusion above alluded to, namely, that an
+interval elapsed between the death of the creature to whose shell they
+adhere, and the burial of the same in mud or sand. The sea-urchins or
+<i>Echini</i>, so abundant in white chalk, afford a good illustration. <span class="pagenum"><a id="page23"></a>[p.23]</span>
+It is well known that these animals, when living, are invariably covered
+with numerous spines, which serve as organs of motion, and are supported by
+rows of tubercles, which last are only seen after the death of the
+sea-urchin, when the spines have dropped off. In <a href="#img024">fig. 12.</a> a living species
+of <i>Spatangus</i>, common on our coast, is represented with one half of its
+shell stripped of the spines. In <a href="#img023">fig. 11.</a> a fossil of the same genus from
+the white chalk of England shows the naked surface which the individuals of
+this family exhibit when denuded of their bristles. The full-grown
+<i>Serpula</i>, therefore, which now adheres externally, could not have begun to
+grow till the <i>Spatangus</i> had died, and the spines were detached.</p>
+
+<a id="img023" name="img023"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 11.</p>
+<img src="images/img023.jpg" width="181" height="200" alt="" title="">
+<p><i>Serpula</i> attached to a fossil <i>Spatangus</i> from the
+chalk.</p></div>
+
+<a id="img024" name="img024"></a>
+<div class="floatright smaller width275">
+<p>Fig. 12.</p>
+<img src="images/img024.jpg" width="254" height="200" alt="" title="">
+<p>Recent <i>Spatangus</i> with the spines removed from one
+side.</p>
+<ul class="smaller martopm05 leftal">
+<li><i>b.</i> Spine and tubercles, nat. size.</li>
+<li><i>a.</i> The same magnified.</li>
+</ul></div>
+
+<p class="nofloat">Now the series of events here attested by a single fossil may be carried a
+step farther. Thus, for example, we often meet with a sea-urchin in the
+chalk (see <a href="#img025">fig. 13.</a>), which has fixed to it the lower valve of a <i>Crania</i>,
+a genus of bivalve mollusca. The upper valve (<i>b</i>, <a href="#img025">fig. 13.</a>) is almost
+invariably wanting, though occasionally found in a perfect state of
+preservation in white chalk at some distance. In this case, we see clearly
+that the sea-urchin first lived from youth to age, then died and lost its
+spines, which were carried away. Then the young <i>Crania</i> adhered to the
+bared shell, grew and perished in its turn; after which the upper valve was
+separated from the lower before the <i>Echinus</i> became enveloped in chalky
+mud.</p>
+
+<a id="img025" name="img025"></a>
+<div class="figcenter width200">
+<p class="smaller">Fig. 13.</p>
+<img src="images/img025.jpg" width="200" height="196" alt="" title="">
+<ul class="smaller leftal min1em">
+<li><i>a.</i> <i>Echinus</i> from the chalk, with lower valve of the <i>Crania</i> attached.</li>
+<li><i>b.</i> Upper valve of the <i>Crania</i> detached.</li>
+</ul></div>
+
+<p>It may be well to mention one more illustration of the manner in which
+single fossils may sometimes throw light on a former state of things, both
+in the bed of the ocean and on some adjoining land. We meet with many
+fragments of wood bored by ship-worms at various depths in the clay on
+which London is built. Entire branches and stems of trees, several feet in
+length, are sometimes dug out, drilled all over by the holes of these
+borers, the tubes and shells of the mollusk still remaining in the
+cylindrical hollows. In <a href="#img026">fig. 15.</a> <i>e</i>, a representation is given of a piece
+of recent wood pierced by the <i>Teredo navalis</i>, or common ship-worm, which
+destroys wooden piles and ships. When the cylindrical tube <i>d</i> has been
+extracted from the wood, a shell is seen at the larger extremity, composed
+of two pieces, as shown at <i>c</i>. In like manner, a piece of fossil wood
+(<i>a</i>, <a href="#img026">fig. 14.</a>) <span class="pagenum"><a id="page24"></a>[p.24]</span>has been perforated by an animal of a kindred but
+extinct genus, called <i>Teredina</i> by Lamarck. The calcareous tube of this
+mollusk was united and as it were soldered on to the valves of the shell
+(<i>b</i>), which therefore cannot be detached from the tube, like the valves of
+the recent <i>Teredo</i>. The wood in this fossil specimen is now converted into
+a stony mass, a mixture of clay and lime; but it must once have been
+buoyant and floating in the sea, when the <i>Teredin�</i> lived upon it,
+perforating it in all directions. Again, before the infant colony settled
+upon the drift wood, the branch of a tree must have been floated down to
+the sea by a river, uprooted, perhaps, by a flood, or torn off and cast
+into the waves by the wind: and thus our thoughts are carried back to a
+prior period, when the tree grew for years on dry land, enjoying a fit soil
+and climate.</p>
+
+<a id="img026" name="img026"></a>
+<div class="figcenter smaller width500">
+<img src="images/img026.jpg" width="500" height="361" alt="" title="">
+<p>Fossil and recent wood drilled by perforating Mollusca.</p>
+<ul class="smaller martopm05 leftal">
+<li class="min3em"><span class="ftsize105">Fig. 14.</span> <i>a</i>. Fossil wood from London clay, bored by <i>Teredina</i>.</li>
+<li><i>b</i>. Shell and tube of <i>Teredina personata</i>, the right-hand figure the ventral,
+the left the dorsal view.</li>
+</ul>
+<ul class="smaller martopm05 leftal">
+<li class="min3em"><span class="ftsize105">Fig. 15.</span> <i>e</i>. Recent wood bored by <i>Teredo</i>.</li>
+<li><i>d</i>. Shell and tube of <i>Teredo navalis</i>, from the same.</li>
+<li><i>c</i>. Anterior and posterior view of the valves of same detached from the tube.</li>
+</ul></div>
+
+<p>It has been already remarked that there are rocks in the interior of
+continents, at various depths in the earth, and at great heights above the
+sea, almost entirely made up of the remains of zoophytes and testacea. Such
+masses may be compared to modern oyster-beds and coral reefs; and, like
+them, the rate of increase must have been extremely gradual. But there are
+a variety of stony deposits in the earth's crust, now proved to have been
+derived from plants and animals, of which the organic origin was not
+suspected until of late years, even by naturalists. Great surprise was
+therefore created by the recent discovery of Professor Ehrenberg of Berlin,
+that a certain kind of siliceous stone, called tripoli, was entirely
+composed of millions of the remains of organic beings, which the Prussian
+naturalist refers to microscopic Infusoria, but which most others now
+believe to be plants. They abound in freshwater lakes and ponds in England
+and other countries, and are termed Diatomace� by those naturalists who
+believe in their vegetable origin. The substance alluded to has <span class="pagenum"><a id="page25"></a>[p.25]</span>
+long been well known in the arts, being used in the form of powder for
+polishing stones and metals. It has been procured, among other places, from
+Bilin, in Bohemia, where a single stratum, extending over a wide area, is
+no less than 14 feet thick. This stone, when examined with a powerful
+microscope, is found to consist of the siliceous plates or frustules of the
+above-mentioned Diatomace�, united together without any visible cement. It
+is difficult to convey an idea of their extreme minuteness; but Ehrenberg
+estimates that in the Bilin tripoli there are 41,000 millions of
+individuals of the <i>Gaillonella distans</i> (see <a href="#img027">fig. 17.</a>) in every cubic
+inch, which weighs about 220 grains, or about 187 millions in a single
+grain. At every stroke, therefore, that we make with this polishing powder,
+several millions, perhaps tens of millions, of perfect fossils are crushed
+to atoms.</p>
+
+<a id="img027" name="img027"></a>
+<div class="figcenter smaller width500">
+<img src="images/img027.jpg" width="500" height="095" alt="" title="">
+<p>Fig. 16. <i>Bacillaria vulgaris?</i></p>
+<p class="martopm05">Fig. 17. <i>Gaillonella distans.</i></p>
+<p class="martopm05">Fig. 18. <i>Gaillonella ferruginea.</i></p>
+<p>These figures are magnified nearly 300 times, except the
+lower figure of <i>G. ferruginea</i> (fig. 18. <i>a</i>), which is magnified 2000
+times.</p></div>
+
+<a id="img028" name="img028"></a>
+<div class="figcenter smaller width400">
+<img src="images/img028.jpg" width="391" height="400" alt="" title="">
+<p>Fragment of semi-opal from the great bed of Tripoli,
+Bilin.</p>
+<p class="martopm05 leftal min3em left05">Fig. 19. Natural size.</p>
+<p class="martopm05 leftal min3em left05">Fig. 20. The same magnified, showing circular articulations of a species of
+<i>Gaillonella</i>, and spicul� of <i>Spongilla</i>.</p></div>
+
+<p>The remains of these Diatomace� are of pure silex, and their forms are
+various, but very marked and constant in particular genera and species.
+Thus, in the family <i>Bacillaria</i> (see <a href="#img027">fig. 16.</a>), the fossils preserved in
+tripoli are seen to exhibit the same divisions and transverse lines which
+characterize the living species of kindred form. With these, also, the
+siliceous spicul� or internal supports of the freshwater sponge, or
+<i>Spongilla</i> of Lamarck, are sometimes intermingled (see the needle-shaped
+bodies in <a href="#img028">fig. 20.</a>). These flinty cases and spicul�, although hard, are
+very fragile, breaking like glass, and are therefore admirably adapted,
+when rubbed, for wearing down into a fine powder fit for polishing the
+surface of metals.</p>
+
+<p>Besides the tripoli, formed exclusively of the fossils <span class="pagenum"><a id="page26"></a>[p.26]</span>above
+described, there occurs in the upper part of the great stratum at Bilin
+another heavier and more compact stone, a kind of semi-opal, in which
+innumerable parts of Diatomace� and spicul� of the <i>Spongilla</i> are filled
+with, and cemented together by, siliceous matter. It is supposed that the
+siliceous remains of the most delicate Diatomace� have been dissolved by
+water, and have thus given rise to this opal in which the more durable
+fossils are preserved like insects in amber. This opinion is confirmed by
+the fact that the organic bodies decrease in number and sharpness of
+outline in proportion as the opaline cement increases in quantity.</p>
+
+<p>In the Bohemian tripoli above described, as in that of Planitz in Saxony,
+the species of Diatomace� (or Infusoria, as termed by Ehrenberg) are
+freshwater; but in other countries, as in the tripoli of the Isle of
+France, they are of marine species, and they all belong to formations of
+the <i>tertiary</i> period, which will be spoken of hereafter.</p>
+
+<p>A well-known substance, called bog-iron ore, often met with in peat-mosses,
+has also been shown by Ehrenberg to consist of innumerable articulated
+threads, of a yellow ochre colour, composed partly of flint and partly of
+oxide of iron. These threads are the cases of a minute microscopic body,
+called <i>Gaillonella ferruginea</i> (<a href="#img027">fig. 18.</a>).</p>
+
+<a id="img029" name="img029"></a>
+<div class="figcenter smaller">
+<p><i>Cytherid�</i> and <i>Foraminifera</i> from the chalk.</p>
+<img src="images/img029.jpg" width="500" height="106" alt="" title="">
+<p>Fig. 21. <i>Cythere</i>, M�ll. <i>Cytherina</i>, Lam.</p>
+<p class="martopm05">Fig. 22. Portion of <i>Nodosaria</i>.</p>
+<p class="martopm05">Fig. 23. <i>Cristellaria rotulata.</i></p>
+<p class="martopm05">Fig. 24. <i>Rosalina.</i></p></div>
+
+<p>It is clear that much time must have been required for the accumulation of
+strata to which countless generations of Diatomace� have contributed their
+remains; and these discoveries lead us naturally to suspect that other
+deposits, of which the materials have usually been supposed to be
+inorganic, may in reality have been derived from microscopic organic
+bodies. That this is the case with the white chalk, has often been
+imagined, this rock having been observed to abound in a variety of marine
+fossils, such as shells, echini, corals, sponges, crustacea, and fishes.
+Mr. Lonsdale, on examining, in Oct. 1835, in the museum of the Geological
+Society of London, portions of white chalk from different parts of England,
+found, on carefully pulverizing them in water, that what appear to the eye
+simply as white grains were, in fact, well preserved fossils. He obtained
+above a thousand of these from each pound weight of chalk, some being
+fragments of minute corallines, others entire Foraminifera and Cytherid�.
+The annexed drawings will give an idea of the beautiful forms of many of
+these bodies. The figures <i>a</i> <i>a</i> represent their natural size, but, minute
+as they seem, the smallest of them, such as <i>a</i>, <a href="#img029">fig. 24.</a>, are gigantic in
+comparison with the cases of Diatomace� before mentioned. It has, moreover,
+been lately discovered that the <span class="pagenum"><a id="page27"></a>[p.27]</span>chambers into which these
+Foraminifera are divided are actually often filled with thousands of
+well-preserved organic bodies, which abound in every minute grain of chalk,
+and are especially apparent in the white coating of flints, often
+accompanied by innumerable needle-shaped spicul� of sponges. After
+reflecting on these discoveries, we are naturally led on to conjecture
+that, as the formless cement in the semi-opal of Bilin has been derived
+from the decomposition of animal and vegetable remains, so also even those
+parts of chalk flints in which no organic structure can be recognized may
+nevertheless have constituted a part of microscopic animalcules.</p>
+
+<div class="left20">
+<p class="poem">"The dust we tread upon was once alive!"&mdash;<span class="smcap">Byron</span>.</p>
+</div>
+
+<p>How faint an idea does this exclamation of the poet convey of the real
+wonders of nature! for here we discover proofs that the calcareous and
+siliceous dust of which hills are composed has not only been once alive,
+but almost every particle, albeit invisible to the naked eye, still retains
+the organic structure which, at periods of time incalculably remote, was
+impressed upon it by the powers of life.</p>
+
+<p><i>Freshwater and marine fossils.</i>&mdash;Strata, whether deposited in salt or
+fresh water, have the same forms; but the imbedded fossils are very
+different in the two cases, because the aquatic animals which frequent
+lakes and rivers are distinct from those inhabiting the sea. In the
+northern part of the Isle of Wight a formation of marl and limestone, more
+than 50 feet thick, occurs, in which the shells are principally, if not
+all, of extinct species. Yet we recognize their freshwater origin, because
+they are of the same genera as those now abounding in ponds and lakes,
+either in our own country or in warmer latitudes.</p>
+
+<p>In many parts of France, as in Auvergne, for example, strata of limestone,
+marl, and sandstone are found, hundreds of feet thick, which contain
+exclusively freshwater and land shells, together with the remains of
+terrestrial quadrupeds. The number of land shells scattered through some of
+these freshwater deposits is exceedingly great; and there are districts in
+Germany where the rocks scarcely contain any other fossils except
+snail-shells (<i>helices</i>); as, for instance, the limestone on the left bank
+of the Rhine, between Mayence and Worms, at Oppenheim, Findheim, Budenheim,
+and other places. In order to account for this phenomenon, the geologist
+has only to examine the small deltas of torrents which enter the Swiss
+lakes when the waters are low, such as the newly-formed plain where the
+Kander enters the Lake of Thun. He there sees sand and mud strewed over
+with innumerable dead land shells, which have been brought down from
+valleys in the Alps in the preceding spring, during the melting of the
+snows. Again, if we search the sands on the borders of the Rhine, in the
+lower part of its course, we find countless land shells mixed with others
+of species belonging to lakes, stagnant pools, and marshes. These
+individuals have been washed <span class="pagenum"><a id="page28"></a>[p.28]</span>away from the alluvial plains of the
+great river and its tributaries, some from mountainous regions, others from
+the low country.</p>
+
+<p>Although freshwater formations are often of great thickness, yet they are
+usually very limited in area when compared to marine deposits, just as
+lakes and estuaries are of small dimensions in comparison with seas.</p>
+
+<p>We may distinguish a freshwater formation, first, by the absence of many
+fossils almost invariably met with in marine strata. For example, there are
+no sea-urchins, no corals, and scarcely any zoophytes; no chambered shells,
+such as the nautilus, nor microscopic Foraminifera. But it is chiefly by
+attending to the forms of the mollusca that we are guided in determining
+the point in question. In a freshwater deposit, the number of individual
+shells is often as great, if not greater, than in a marine stratum; but
+there is a smaller variety of species and genera. This might be anticipated
+from the fact that the genera and species of recent freshwater and land
+shells are few when contrasted with the marine. Thus, the genera of true
+mollusca according to Blainville's system, excluding those of extinct
+species and those without shells, amount to about 200 in number, of which
+the terrestrial and freshwater genera scarcely form more than a
+sixth.<a name="FNanchor_E_1" id="FNanchor_E_1"></a><a href="#Footnote_E_1" class="fnanchor">[28-A]</a></p>
+
+<a id="img030" name="img030"></a>
+<div class="floatleft smaller">
+<p>Fig. 25.</p>
+<img src="images/img030.jpg" width="200" height="085" alt="" title="">
+<p><i>Cyclas obovata</i>; <span class="wosp05">fossil. Hants.</span></p></div>
+
+<a id="img031" name="img031"></a>
+<div class="floatright smaller">
+<p class="martop2">Fig. 26.</p>
+<img src="images/img031.jpg" width="200" height="146" alt="" title="">
+<p><i>Cyrena consobrina</i>; <span class="wosp05">fossil. Grays,</span> Essex.</p></div>
+
+<a id="img032" name="img032"></a>
+<div class="floatleft smaller">
+<p class="martop2">Fig. 27.</p>
+<img src="images/img032.jpg" width="111" height="250" alt="" title="">
+<p><i>Anodonta Cordierii</i>; <span class="wosp05">fossil. Paris.</span></p></div>
+
+<a id="img033" name="img033"></a>
+<div class="floatright smaller">
+<p class="martop2">Fig. 28.</p>
+<img src="images/img033.jpg" width="164" height="250" alt="" title="">
+<p><i>Anodonta latimarginatus</i>; <span class="wosp05">recent. Bahia.</span></p></div>
+
+<a id="img034" name="img034"></a>
+<div class="figcenter nofloat smaller">
+<p class="martop2">Fig. 29.</p>
+<img src="images/img034.jpg" width="151" height="250" alt="" title="">
+<p><i>Unio littoralis</i>; <span class="wosp05">recent. Auvergne.</span></p></div>
+
+<p>Almost all bivalve shells, or those of acephalous mollusca, are marine,
+about ten only out of ninety genera being freshwater. Among these last, the
+four most common forms, both recent and fossil, are <i>Cyclas</i>, <i>Cyrena</i>,
+<i>Unio</i>, and <i>Anodonta</i> (see figures); the two first and two last of which
+are so nearly allied as to pass into each other.</p>
+
+<span class="pagenum"><a id="page29"></a>[p.29]</span>
+<a id="img035" name="img035"></a>
+<div class="figcenter smaller width225">
+<p>Fig. 30.</p>
+<img src="images/img035.jpg" width="223" height="250" alt="" title="">
+<p><i>Gryph�a incurva</i>, Sow. (<i>G. arcuata</i>,
+Lam.) upper valve. Lias.</p></div>
+
+<p>Lamarck divided the bivalve mollusca into the <i>Dimyary</i>, or those having
+two large muscular impressions in each valve, as <i>a b</i> in the Cyclas, <a href="#img030">fig.
+25.</a>, and the <i>Monomyary</i>, such as the oyster and scallop, in which there is
+only one of these impressions, as is seen in <a href="#img035">fig. 30.</a> Now, as none of these
+last, or the unimuscular bivalves, are freshwater, we may at once presume a
+deposit in which we find any of them to be marine.</p>
+
+<a id="img036" name="img036"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 31.</p>
+<img src="images/img036.jpg" width="250" height="228" alt="" title="">
+<p><i>Planorbis euomphalus</i>; <span class="wosp05">fossil. Isle</span> of Wight.</p></div>
+
+<a id="img037" name="img037"></a>
+<div class="floatright smaller width225">
+<p>Fig. 32.</p>
+<img src="images/img037.jpg" width="207" height="250" alt="" title="">
+<p><i>Lymnea longiscata</i>; <span class="wosp05">fossil. Hants.</span></p></div>
+
+<a id="img038" name="img038"></a>
+<div class="figcenter nofloat smaller width175">
+<p>Fig. 33.</p>
+<img src="images/img038.jpg" width="164" height="250" alt="" title="">
+<p><i>Paludina lenta</i>; <span class="wosp05">fossil. Hants.</span></p></div>
+
+<p>The univalve shells most characteristic of freshwater deposits are,
+<i>Planorbis</i>, <i>Lymnea</i>, and <i>Paludina</i>. (See figures.) But to these are
+occasionally added <i>Physa</i>, <i>Succinea</i>, <i>Ancylus</i>, <i>Valvata</i>, <i>Melanopsis</i>,
+<i>Melania</i>, and <i>Neritina</i>. (See figures.)</p>
+
+<a id="img039" name="img039"></a>
+<div class="floatleft smaller width125">
+<p>Fig. 34.</p>
+<img src="images/img039.jpg" width="124" height="200" alt="" title="">
+<p><i>Succinea amphibia</i>; <span class="wosp05">fossil. Loess,</span> Rhine.</p></div>
+
+<a id="img040" name="img040"></a>
+<div class="floatright smaller">
+<p>Fig. 35.</p>
+<img src="images/img040.jpg" width="450" height="165" alt="" title="">
+<p><i>Ancylus elegans</i>; <span class="wosp05">fossil. Hants.</span></p></div>
+
+<a id="img041" name="img041"></a>
+<div class="floatleft smaller width175">
+<p>Fig. 36.</p>
+<img src="images/img041.jpg" width="158" height="200" alt="" title="">
+<p><i>Valvata</i>; fossil. Grays, Essex.</p></div>
+
+<a id="img042" name="img042"></a>
+<div class="floatright smaller width100">
+<p>Fig. 37.</p>
+<img src="images/img042.jpg" width="100" height="200" alt="" title="">
+<p><i>Physa hypnorum</i>; recent.</p></div>
+
+<a id="img043" name="img043"></a>
+<div class="floatleft smaller width125">
+<p>Fig. 38.</p>
+<img src="images/img043.jpg" width="119" height="250" alt="" title="">
+<p><i>Auricula</i>; <span class="wosp05">recent. Ava.</span></p></div>
+
+<a id="img044" name="img044"></a>
+<div class="floatright smaller width100">
+<p>Fig. 39.</p>
+<img src="images/img044.jpg" width="089" height="250" alt="" title="">
+<p><i>Melania inquinata</i><span class="wosp05">. Paris</span> Basin.</p></div>
+
+<a id="img045" name="img045"></a>
+<div class="floatleft smaller width100">
+<p>Fig. 40.</p>
+<img src="images/img045.jpg" width="078" height="250" alt="" title="">
+<p><i>Physa columnaris</i><span class="wosp05">. Paris</span> Basin.</p></div>
+
+<a id="img046" name="img046"></a>
+<div class="floatright smaller width175">
+<p>Fig. 41.</p>
+<img src="images/img046.jpg" width="161" height="250" alt="" title="">
+<p><i>Melanopsis buccinoidea</i>; <span class="wosp05">recent. Asia.</span></p></div>
+
+<p class="nofloat">In regard to one of these, the <i>Ancylus</i> (<a href="#img040">fig. 35.</a>), Mr. Gray observes that
+it sometimes differs in no respect from the marine <i>Siphonaria</i>, except in
+the animal. The shell, however, of the <i>Ancylus</i> is usually thinner.<a name="FNanchor_E_2" id="FNanchor_E_2"></a><a href="#Footnote_E_2" class="fnanchor">[29-A]</a></p>
+
+<span class="pagenum"><a id="page30"></a>[p.30]</span>
+<a id="img047" name="img047"></a>
+<div class="floatleft smaller">
+<p>Fig. 42.</p>
+<img src="images/img047.jpg" width="450" height="158" alt="" title="">
+<p><i>Neritina globulus</i><span class="wosp05">. Paris</span> basin.</p></div>
+
+<a id="img048" name="img048"></a>
+<div class="floatright smaller width200">
+<p>Fig. 43.</p>
+<img src="images/img048.jpg" width="190" height="150" alt="" title="">
+<p><i>Nerita granulosa</i><span class="wosp05">. Paris</span> basin.</p></div>
+
+<p class="nofloat">Some naturalists include <i>Neritina</i> (<a href="#img047">fig. 42.</a>) and the marine <i>Nerita</i>
+(<a href="#img048">fig. 43.</a>) in the same genus, it being scarcely possible to distinguish the
+two by good generic characters. But, as a general rule, the fluviatile
+species are smaller, smoother, and more globular than the marine; and they
+have never, like the <i>Nerit�</i>, the inner margin of the outer lip toothed or
+crenulated. (See <a href="#img048">fig. 43.</a>)</p>
+
+<a id="img049" name="img049"></a>
+<div class="figcenter smaller width100">
+<p>Fig. 44.</p>
+<img src="images/img049.jpg" width="077" height="300" alt="" title="">
+<p><i>Cerithium cinctum</i><span class="wosp05">. Paris</span> basin.</p></div>
+
+<p>A few genera, among which <i>Cerithium</i> (<a href="#img049">fig. 44.</a>) is the most abundant, are
+common both to rivers and the sea, having species peculiar to each. Other
+genera, like <i>Auricula</i> (<a href="#img043">fig. 38.</a>), are amphibious, frequenting marshes,
+especially near the sea.</p>
+
+<a id="img050" name="img050"></a>
+<div class="figcenter smaller">
+<p>Fig. 45.</p>
+<img src="images/img050.jpg" width="337" height="250" alt="" title="">
+<p><i>Helix Turonensis.</i> Faluns, Touraine.</p></div>
+
+<a id="img051" name="img051"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 46.</p>
+<img src="images/img051.jpg" width="129" height="200" alt="" title="">
+<p><i>Cyclostoma elegans.</i> Loess.</p></div>
+
+<a id="img052" name="img052"></a>
+<div class="floatright smaller width100">
+<p>Fig. 47.</p>
+<img src="images/img052.jpg" width="097" height="200" alt="" title="">
+<p><i>Pupa tridens.</i> Loess.</p></div>
+
+<a id="img053" name="img053"></a>
+<div class="floatleft smaller width75">
+<p>Fig. 48.</p>
+<img src="images/img053.jpg" width="064" height="200" alt="" title="">
+<p><i>Clausilia bidens.</i> Loess.</p></div>
+
+<a id="img054" name="img054"></a>
+<div class="floatright smaller width200">
+<p>Fig. 49.</p>
+<img src="images/img054.jpg" width="196" height="200" alt="" title="">
+<p><i>Bulimus lubricus.</i> Loess, Rhine.</p></div>
+
+<p class="nofloat">The terrestrial shells are all univalves. The most abundant genera among
+these, both in a recent and fossil state, are <i>Helix</i> (<a href="#img050">fig. 45.</a>),
+<i>Cyclostoma</i> (<a href="#img051">fig. 46.</a>), <i>Pupa</i> (<a href="#img052">fig. 47.</a>), <i>Clausilia</i> (<a href="#img053">fig. 48.</a>),
+<i>Bulimus</i> (<a href="#img054">fig. 49.</a>), and <i>Achatina</i>; which two last are nearly allied and
+pass into each other.</p>
+
+<a id="img055" name="img055"></a>
+<div class="figcenter smaller width225">
+<p>Fig. 50.</p>
+<img src="images/img055.jpg" width="225" height="250" alt="" title="">
+<p><i>Ampullaria glauca</i>, from the Jumna.</p></div>
+
+<p>The <i>Ampullaria</i> (<a href="#img055">fig. 50.</a>) is another genus of shells, inhabiting rivers
+and ponds in hot countries. Many fossil species have been referred to this
+genus, but they have been found chiefly in marine formations, and are
+suspected by some conchologists to belong to <i>Natica</i> and other marine
+genera.</p>
+
+<p>All univalve shells of land and freshwater species, with the exception of
+<i>Melanopsis</i> (<a href="#img046">fig. 41.</a>), and <i>Achatina</i>, which has a slight indentation,
+have entire mouths; and this circumstance may often serve as a convenient
+rule for distinguishing freshwater from marine strata; since, if any
+univalves occur of which the mouths are not entire, we may presume that the
+formation is marine. The aperture is said to be entire in such shells as
+the <i>Ampullaria</i> and the land shells (<a href="#img050">figs. 45</a>-<a href="#img054">49.</a>), when its outline is
+not interrupted by an indentation or notch, such as that seen at <i>b</i> in
+<i>Ancillaria</i> <span class="pagenum"><a id="page31"></a>[p.31]</span>(<a href="#img057">fig. 52.</a>); or is not prolonged into a canal, as that
+seen at <i>a</i> in <i>Pleurotoma</i> (<a href="#img056">fig. 51.</a>).</p>
+
+<a id="img056" name="img056"></a>
+<div class="figcenter smaller width125">
+<p>Fig. 51.</p>
+<img src="images/img056.jpg" width="121" height="300" alt="" title="">
+<p><i>Pleurotoma rotata.</i> Subap. hills, Italy.</p></div>
+
+<a id="img057" name="img057"></a>
+<div class="figcenter smaller">
+<p class="martop2">Fig. 52.</p>
+<img src="images/img057.jpg" width="294" height="300" alt="" title="">
+<p><i>Ancillaria subulata</i><span class="wosp05">. London</span> clay.</p></div>
+
+<p>The mouths of a large proportion of the marine univalves have these notches
+or canals, and almost all such species are carnivorous; whereas nearly all
+testacea having entire mouths, are plant-eaters; whether the species be
+marine, freshwater, or terrestrial.</p>
+
+<p>There is, however, one genus which affords an occasional exception to one
+of the above rules. The <i>Cerithium</i> (<a href="#img049">fig. 44.</a>), although provided with a
+short canal, comprises some species which inhabit salt, others brackish,
+and others fresh water, and they are said to be all plant-eaters.</p>
+
+<p>Among the fossils very common in freshwater deposits are the shells of
+<i>Cypris</i>, a minute crustaceous animal, having a shell much resembling that
+of the bivalve mollusca.<a name="FNanchor_E_3" id="FNanchor_E_3"></a><a href="#Footnote_E_3" class="fnanchor">[31-A]</a> Many minute living species of this genus
+swarm in lakes and stagnant pools in Great Britain; but their shells are
+not, if considered separately, conclusive as to the freshwater origin of a
+deposit, because the majority of species in another kindred genus of the
+same order, the <i>Cytherina</i> of Lamarck (see above, <a href="#img029">fig. 21.</a> <a href="#page26">p. 26.</a>),
+inhabit salt water; and, although the animal differs slightly, the shell is
+scarcely distinguishable from that of the <i>Cypris</i>.</p>
+
+<p>The seed-vessels and stems of <i>Chara</i>, a genus of aquatic plants, are very
+frequent in freshwater strata. These seed-vessels were called, before their
+true nature was known, gyrogonites, and were supposed to be foraminiferous
+shells. (See <a href="#img058">fig. 53. <i>a.</i></a>)</p>
+
+<p>The <i>Char�</i> inhabit the bottom of lakes and ponds, and flourish mostly
+where the water is charged with carbonate of lime. Their seed-vessels are
+covered with a very tough integument, capable of resisting decomposition;
+to which circumstance we may attribute their abundance in a fossil state.
+The annexed figure (<a href="#img059">fig. 54.</a>) represents a branch of one of many new
+species found by Professor Amici in the lakes of northern Italy. The
+seed-vessel in this plant is more globular than in the British <i>Char�</i>, and
+therefore more nearly resembles in form the extinct fossil species found in
+England, <span class="pagenum"><a id="page32"></a>[p.32]</span>France, and other countries. The stems, as well as the
+seed-vessels, of these plants occur both in modern shell marl and in
+ancient freshwater formations. They are generally composed of a large tube
+surrounded by smaller tubes; the whole stem being divided at certain
+intervals by transverse partitions or joints. (See <i>b</i>, <a href="#img058">fig. 53.</a>)</p>
+
+<a id="img058" name="img058"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 53.</p>
+<img src="images/img058.jpg" width="199" height="300" alt="" title="">
+<p><i>Chara medicaginula</i>; <span class="wosp05">fossil. Isle</span> of Wight.</p>
+<ul class="smaller martopm05 leftal min1em">
+<li><i>a.</i> Seed-vessel. magnified 20 diameters.</li>
+<li><i>b.</i> Stem, magnified.</li>
+</ul></div>
+
+<a id="img059" name="img059"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 54.</p>
+<img src="images/img059.jpg" width="400" height="262" alt="" title="">
+<p><i>Chara elastica</i>; <span class="wosp05">recent. Italy.</span></p>
+<ul class="smaller martopm05 leftal min1em">
+<li><i>a.</i> Sessile seed vessel between the division of
+the leaves of the female plant.</li>
+<li><i>b.</i> Transverse section of a branch, with five
+seed-vessels magnified, seen from below
+upwards.</li>
+</ul></div>
+
+<p>It is not uncommon to meet with layers of vegetable matter, impressions of
+leaves, and branches of trees, in strata containing freshwater shells; and
+we also find occasionally the teeth and bones of land quadrupeds, of
+species now unknown. The manner in which such remains are occasionally
+carried by rivers into lakes, especially during floods, has been fully
+treated of in the "Principles of Geology."<a name="FNanchor_E_4" id="FNanchor_E_4"></a><a href="#Footnote_E_4" class="fnanchor">[32-A]</a></p>
+
+<p>The remains of fish are occasionally useful in determining the freshwater
+origin of strata. Certain genera, such as carp, perch, pike, and loach
+(<i>Cyprinus</i>, <i>Perca</i>, <i>Esox</i>, and <i>Cobitis</i>), as also <i>Lebias</i>, being
+peculiar to freshwater. Other genera contain some freshwater and some
+marine species, as <i>Cottus</i>, <i>Mugil</i>, and <i>Anguilla</i>, or eel. The rest are
+either common to rivers and the sea, as the salmon; or are exclusively
+characteristic of salt water. The above observations respecting fossil
+fishes are applicable only to the more modern or tertiary deposits; for in
+the more ancient rocks the forms depart so widely from those of existing
+fishes, that it is very difficult, at least in the present state of
+science, to derive any positive information from ichthyolites respecting
+the element in which strata were deposited.</p>
+
+<p>The alternation of marine and freshwater formations, both on a small and
+large scale, are facts well ascertained in geology. When it occurs on a
+small scale, it may have arisen from the alternate occupation of certain
+spaces by river water and the sea; for in the flood season the river forces
+back the ocean and freshens it over a large area, depositing at the same
+time its sediment; after which the salt water again returns, and, on
+resuming its former place, brings with it sand, mud, and marine shells.</p>
+
+<p><span class="pagenum"><a id="page33"></a>[p.33]</span>There are also lagoons at the mouths of many rivers, as the Nile
+and Mississippi, which are divided off by bars of sand from the sea, and
+which are filled with salt and fresh water by turns. They often communicate
+exclusively with the river for months, years, or even centuries; and then a
+breach being made in the bar of sand, they are for long periods filled with
+salt water.</p>
+
+<p>The Lym-Fiord in Jutland offers an excellent illustration of analogous
+changes; for, in the course of the last thousand years, the western
+extremity of this long frith, which is 120 miles in length, including its
+windings, has been four times fresh and four times salt, a bar of sand
+between it and the ocean having been as often formed and removed. The last
+irruption of salt water happened in 1824, when the North Sea entered,
+killing all the freshwater shells, fish, and plants; and from that time to
+the present, the sea-weed <i>Fucus vesiculosus</i>, together with oysters and
+other marine mollusca, have succeeded the <i>Cyclas</i>, <i>Lymnea</i>, <i>Paludina</i>,
+and <i>Char�</i>.<a name="FNanchor_E_5" id="FNanchor_E_5"></a><a href="#Footnote_E_5" class="fnanchor">[33-A]</a></p>
+
+<p>But changes like these in the Lym-Fiord, and those before mentioned as
+occurring at the mouths of great rivers, will only account for some cases
+of marine deposits of partial extent resting on freshwater strata. When we
+find, as in the south-east of England, a great series of freshwater beds,
+1000 feet in thickness, resting upon marine formations and again covered by
+other rocks, such as the cretaceous, more than 1000 feet thick, and of
+deep-sea origin, we shall find it necessary to seek for a different
+explanation of the phenomena.<a name="FNanchor_E_6" id="FNanchor_E_6"></a><a href="#Footnote_E_6" class="fnanchor">[33-B]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER IV.</h2>
+
+<h4>CONSOLIDATION OF STRATA AND PETRIFACTION OF FOSSILS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Chemical and mechanical deposits &mdash; Cementing together of
+particles &mdash; Hardening by exposure to air &mdash; Concretionary
+nodules &mdash; Consolidating effects of pressure &mdash; Mineralization of organic
+remains &mdash; Impressions and casts how formed &mdash; Fossil wood &mdash; G�ppert's
+experiments &mdash; Precipitation of stony matter most rapid where
+putrefaction is going on &mdash; Source of lime in solution &mdash; Silex derived
+from decomposition of felspar &mdash; Proofs of the lapidification of some
+fossils soon after burial, of others when much decayed.</p></div>
+
+
+<p><span class="smcap">Having</span> spoken in the preceding chapters of the characters of sedimentary
+formations, both as dependent on the deposition of inorganic matter and the
+distribution of fossils, I may next treat of the consolidation of
+stratified rocks, and the petrifaction of imbedded organic remains.</p>
+
+<p><i>Chemical and mechanical deposits.</i>&mdash;A distinction has been made <span class="pagenum"><a id="page34"></a>[p.34]</span>
+by geologists between deposits of a chemical, and those of a mechanical,
+origin. By the latter name are designated beds of mud, sand, or pebbles
+produced by the action of running water, also accumulations of stones and
+scori� thrown out by a volcano, which have fallen into their present place
+by the force of gravitation. But the matter which forms a chemical deposit
+has not been mechanically suspended in water, but in a state of solution
+until separated by chemical action. In this manner carbonate of lime is
+often precipitated upon the bottom of lakes and seas in a solid form, as
+may be well seen in many parts of Italy, where mineral springs abound, and
+where the calcareous stone, called travertin, is deposited. In these
+springs the lime is usually held in solution by an excess of carbonic acid,
+or by heat if it be a hot spring, until the water, on issuing from the
+earth, cools or loses part of its acid. The calcareous matter then falls
+down in a solid state, encrusting shells, fragments of wood and leaves, and
+binding them together.<a name="FNanchor_F_1" id="FNanchor_F_1"></a><a href="#Footnote_F_1" class="fnanchor">[34-A]</a></p>
+
+<p>In coral reefs, large masses of limestone are formed by the stony skeletons
+of zoophytes; and these, together with shells, become cemented together by
+carbonate of lime, part of which is probably furnished to the sea-water by
+the decomposition of dead corals. Even shells of which the animals are
+still living, on these reefs, are very commonly found to be encrusted over
+with a hard coating of limestone.<a name="FNanchor_F_2" id="FNanchor_F_2"></a><a href="#Footnote_F_2" class="fnanchor">[34-B]</a></p>
+
+<p>If sand and pebbles are carried by a river into the sea, and these are
+bound together immediately by carbonate of lime, the deposit may be
+described as of a mixed origin, partly chemical, and partly mechanical.</p>
+
+<p>Now, the remarks already made in Chapter II. on the original horizontality
+of strata are strictly applicable to mechanical deposits, and only
+partially to those of a mixed nature. Such as are purely chemical may be
+formed on a very steep slope, or may even encrust the vertical walls of a
+fissure, and be of equal thickness throughout; but such deposits are of
+small extent, and for the most part confined to veinstones.</p>
+
+<p><i>Cementing of particles.</i>&mdash;It is chiefly in the case of calcareous rocks
+that solidification takes place at the time of deposition. But there are
+many deposits in which a cementing process comes into operation long
+afterwards. We may sometimes observe, where the water of ferruginous or
+calcareous springs has flowed through a bed of sand or gravel, that iron or
+carbonate of lime has been deposited in the interstices between the grains
+or pebbles, so that in certain places the whole has been bound together
+into a stone, the same set of strata remaining in other parts loose and
+incoherent.</p>
+
+<p>Proofs of a similar cementing action are seen in a rock at Kelloway in
+Wiltshire. A peculiar band of sandy strata, belonging to the group called
+Oolite by geologists, may be traced through several <span class="pagenum"><a id="page35"></a>[p.35]</span>counties, the
+sand being for the most part loose and unconsolidated, but becoming stony
+near Kelloway. In this district there are numerous fossil shells which have
+decomposed, having for the most part left only their casts. The calcareous
+matter hence derived has evidently served, at some former period, as a
+cement to the siliceous grains of sand, and thus a solid sandstone has been
+produced. If we take fragments of many other argillaceous grits, retaining
+the casts of shells, and plunge them into dilute muriatic or other acid, we
+see them immediately changed into common sand and mud; the cement of lime,
+derived from the shells, having been dissolved by the acid.</p>
+
+<p>Traces of impressions and casts are often extremely faint. In some loose
+sands of recent date we meet with shells in so advanced a stage of
+decomposition as to crumble into powder when touched. It is clear that
+water percolating such strata may soon remove the calcareous matter of the
+shell; and, unless circumstances cause the carbonate of lime to be again
+deposited, the grains of sand will not be cemented together; in which case
+no memorial of the fossil will remain. The absence of organic remains from
+many aqueous rocks may be thus explained; but we may presume that in many
+of them no fossils were ever imbedded, as there are extensive tracts on the
+bottoms of existing seas even of moderate depth on which no fragment of
+shell, coral, or other living creature can be detected by dredging. On the
+other hand, there are depths where the zero of animal life has been
+approached; as, for example, in the Mediterranean, at the depth of about
+230 fathoms, according to the researches of Prof. E. Forbes. In the �gean
+Sea a deposit of yellowish mud of a very uniform character, and closely
+resembling chalk, is going on in regions below 230 fathoms, and this
+formation must be wholly devoid of organic remains.<a name="FNanchor_F_3" id="FNanchor_F_3"></a><a href="#Footnote_F_3" class="fnanchor">[35-A]</a></p>
+
+<p>In what manner silex and carbonate of lime may become widely diffused in
+small quantities through the waters which permeate the earth's crust will
+be spoken of presently, when the petrifaction of fossil bodies is
+considered; but I may remark here that such waters are always passing in
+the case of thermal springs from hotter to colder parts of the interior of
+the earth; and as often as the temperature of the solvent is lowered,
+mineral matter has a tendency to separate from it and solidify. Thus a
+stony cement is often supplied to any sand, pebbles, or fragmentary
+mixture. In some conglomerates, like the pudding-stone of Hertfordshire,
+pebbles of flint and grains of sand are united by a siliceous cement so
+firmly, that if a block be fractured the rent passes as readily through the
+pebbles as through the cement.</p>
+
+<p>It is probable that many strata became solid at the time when they emerged
+from the waters in which they were deposited, and when they first formed a
+part of the dry land. A well-known fact seems to confirm this idea: by far
+the greater number of the stones used for building and road-making are much
+softer when first taken from <span class="pagenum"><a id="page36"></a>[p.36]</span>the quarry than after they have been
+long exposed to the air; and these, when once dried, may afterwards be
+immersed for any length of time in water without becoming soft again. Hence
+it is found desirable to shape the stones which are to be used in
+architecture while they are yet soft and wet, and while they contain their
+"quarry-water," as it is called; also to break up stone intended for roads
+when soft, and then leave it to dry in the air for months that it may
+harden. Such induration may perhaps be accounted for by supposing the
+water, which penetrates the minutest pores of rocks, to deposit, on
+evaporation, carbonate of lime, iron, silex, and other minerals previously
+held in solution, and thereby to fill up the pores partially. These
+particles, on crystallizing, would not only be themselves deprived of
+freedom of motion, but would also bind together other portions of the rock
+which before were loosely aggregated. On the same principle wet sand and
+mud become as hard as stone when frozen; because one ingredient of the
+mass, namely, the water, has crystallized, so as to hold firmly together
+all the separate particles of which the loose mud and sand were composed.</p>
+
+<p>Dr. MacCulloch mentions a sandstone in Skye, which may be moulded like
+dough when first found; and some simple minerals, which are rigid and as
+hard as glass in our cabinets, are often flexible and soft in their native
+beds; this is the case with asbestos, sahlite, tremolite, and chalcedony,
+and it is reported also to happen in the case of the beryl.<a name="FNanchor_F_4" id="FNanchor_F_4"></a><a href="#Footnote_F_4" class="fnanchor">[36-A]</a></p>
+
+<p>The marl recently deposited at the bottom of Lake Superior, in North
+America, is soft, and often filled with freshwater shells; but if a piece
+be taken up and dried, it becomes so hard that it can only be broken by a
+smart blow of the hammer. If the lake therefore was drained, such a deposit
+would be found to consist of strata of marlstone, like that observed in
+many ancient European formations, and like them containing freshwater
+shells.<a name="FNanchor_F_5" id="FNanchor_F_5"></a><a href="#Footnote_F_5" class="fnanchor">[36-B]</a></p>
+
+<p>It is probable that some of the heterogeneous materials which rivers
+transport to the sea may at once set under water, like the artificial
+mixture called pozzolana, which consists of fine volcanic sand charged with
+about 20 per cent. of oxide of iron, and the addition of a small quantity
+of lime. This substance hardens, and becomes a solid stone in water, and
+was used by the Romans in constructing the foundations of buildings in the
+sea.</p>
+
+<p>Consolidation in these cases is brought about by the action of chemical
+affinity on finely comminuted matter previously suspended in water. After
+deposition similar particles seem to exert a mutual attraction on each
+other, and congregate together in particular spots, forming lumps, nodules,
+and concretions. Thus in many argillaceous deposits there are calcareous
+balls, or spherical concretions, ranged in layers parallel to the general
+stratification; an arrangement which took place after the shale or marl had
+been thrown down in successive <span class="pagenum"><a id="page37"></a>[p.37]</span>lamin�; for these lamin� are often
+traced in the concretions, remaining parallel to those of the surrounding
+unconsolidated rock. (See <a href="#img060">fig. 55.</a>) Such nodules of limestone have often a
+shell or other foreign body in the centre.<a name="FNanchor_F_6" id="FNanchor_F_6"></a><a href="#Footnote_F_6" class="fnanchor">[37-A]</a></p>
+
+<a id="img060" name="img060"></a>
+<div class="figcenter smaller">
+<p>Fig. 55.</p>
+<img src="images/img060.jpg" width="300" height="096" alt="" title="">
+<p>Calcareous nodules in Lias.</p></div>
+
+<p>Among the most remarkable examples of concretionary structure are those
+described by Professor Sedgwick as abounding in the magnesian limestone of
+the north of England. The spherical balls are of various sizes, from that
+of a pea to a diameter of several feet, and they have both a concentric and
+radiated structure, while at the same time the lamin� of original
+deposition pass uninterruptedly through them. In some cliffs this limestone
+resembles a great irregular pile of cannon balls. Some of the globular
+masses have their centre in one stratum, while a portion of their exterior
+passes through to the stratum above or below. Thus the larger spheroid in
+the annexed section (<a href="#img061">fig. 56.</a>) passes from the stratum <i>b</i> upwards into
+<i>a</i>. In this instance we must suppose the deposition of a series of minor
+layers, first forming the stratum <i>b</i>, and afterwards the incumbent stratum
+<i>a</i>; then a movement of the particles took place, and the carbonates of
+lime and magnesia separated from the more impure and mixed matter forming
+the still unconsolidated parts of the stratum. Crystallization, beginning
+at the centre, must have gone on forming concentric coats, around the
+original nucleus without interfering with the laminated structure of the
+rock.</p>
+
+<a id="img061" name="img061"></a>
+<div class="figcenter smaller">
+<p>Fig. 56.</p>
+<img src="images/img061.jpg" width="300" height="122" alt="" title="">
+<p>Spheroidal concretions in magnesian limestone.</p></div>
+
+<p>When the particles of rocks have been thus re-arranged by chemical forces,
+it is sometimes difficult or impossible to ascertain whether certain lines
+of division are due to original deposition or to the subsequent aggregation
+of similar particles. Thus suppose three strata of grit, A, B, C, are
+charged unequally with calcareous matter, and that B is the most
+calcareous. If consolidation takes place in B, the concretionary action may
+spread upwards into a part of A, where the carbonate of lime is more
+abundant than in the rest; so that a mass, <i>d</i>, <i>e</i>, <i>f</i>, forming a portion
+of the superior stratum, becomes united with B into one solid mass of
+stone. The original line of division <i>d</i>, <i>e</i>, being thus effaced, the line
+<i>d</i>, <i>f</i>, would generally be considered as the surface of the bed B, though
+not strictly a true plane of stratification.</p>
+
+<a id="img062" name="img062"></a>
+<div class="figcenter smaller">
+<p>Fig. 57.</p>
+<img src="images/img062.jpg" width="300" height="110" alt="" title=""></div>
+
+<p><i>Pressure and heat.</i>&mdash;When sand and mud sink to the bottom of a deep sea,
+the particles are not pressed down by the enormous weight of the incumbent
+ocean; for the water, which becomes mingled with the sand and mud, resists
+pressure with a force equal to that of the <span class="pagenum"><a id="page38"></a>[p.38]</span>column of fluid above.
+The same happens in regard to organic remains which are filled with water
+under great pressure as they sink, otherwise they would be immediately
+crushed to pieces and flattened. Nevertheless, if the materials of a
+stratum remain in a yielding state, and do not set or solidify, they will
+be gradually squeezed down by the weight of other materials successively
+heaped upon them, just as soft clay or loose sand on which a house is built
+may give way. By such downward pressure particles of clay, sand, and marl,
+may become packed into a smaller space, and be made to cohere together
+permanently.</p>
+
+<p>Analogous effects of condensation may arise when the solid parts of the
+earth's crust are forced in various directions by those mechanical
+movements afterwards to be described, by which strata have been bent,
+broken, and raised above the level of the sea. Rocks of more yielding
+materials must often have been forced against others previously
+consolidated, and, thus compressed, may have acquired a new structure. A
+recent discovery may help us to comprehend how fine sediment derived from
+the detritus of rocks may be solidified by mere pressure. The graphite or
+"black lead" of commerce having become very scarce, Mr. Brockedon contrived
+a method by which the dust of the purer portions of the mineral found in
+Borrowdale might be recomposed into a mass as dense and compact as native
+graphite. The powder of graphite is first carefully prepared and freed from
+air, and placed under a powerful press on a strong steel die, with
+air-tight fittings. It is then struck several blows, each of a power of
+1000 tons; after which operation the powder is so perfectly solidified that
+it can be cut for pencils, and exhibits when broken the same texture as
+native graphite.</p>
+
+<p>But the action of heat at various depths in the earth is probably the most
+powerful of all causes in hardening sedimentary strata. To this subject I
+shall refer again when treating of the metamorphic rocks, and of the slaty
+and jointed structure.</p>
+
+<p><i>Mineralization of organic remains.</i>&mdash;The changes which fossil organic
+bodies have undergone since they were first imbedded in rocks, throw much
+light on the consolidation of strata. Fossil shells in some modern deposits
+have been scarcely altered in the course of centuries, having simply lost a
+part of their animal matter. But in other cases the shell has disappeared,
+and left an impression only of its exterior, or a cast of its interior
+form, or thirdly, a cast of the shell itself, the original matter of which
+has been removed. These different forms of fossilization may easily be
+understood if we examine the mud recently thrown out from a pond or canal
+in which there are shells. If the mud be argillaceous, it acquires
+consistency on drying, and on breaking open a portion of it we find that
+each shell has left impressions of its external form. If we then remove the
+shell itself, we find within a solid nucleus of clay, having the form of
+the interior of the shell. This form is often very different from that of
+the outer shell. Thus a cast such as <i>a</i>, <a href="#img063">fig. 58.</a>, commonly called a
+fossil screw, would never be suspected by an inexperienced conchologist to
+be <span class="pagenum"><a id="page39"></a>[p.39]</span>the internal shape of the fossil univalve, <i>b</i>, <a href="#img063">fig. 58.</a> Nor
+should we have imagined at first sight that the shell <i>a</i> and the cast <i>b</i>,
+<a href="#img064">fig. 59.</a>, were different parts of the same fossil. The reader will observe,
+in the last-mentioned figure (<i>b</i>, <a href="#img064">fig. 59.</a>), that an empty space shaded
+dark, which the <i>shell itself</i> once occupied, now intervenes between the
+enveloping stone and the cast of the smooth interior of the whorls. In such
+cases the shell has been dissolved and the component particles removed by
+water percolating the rock. If the nucleus were taken out a hollow mould
+would remain, on which the external form of the shell with its tubercles
+and stri�, as seen in <i>a</i>, <a href="#img064">fig. 59</a>., would be seen embossed. Now if the
+space alluded to between the nucleus and the impression, instead of being
+left empty, has been filled up with calcareous spar, flint, pyrites, or
+other mineral, we then obtain from the mould an exact cast both of the
+external and internal form of the original shell. In this manner silicified
+casts of shells have been formed; and if the mud or sand of the nucleus
+happen to be incoherent, or soluble in acid, we can then procure in flint
+an empty shell, which in shape is the exact counterpart of the original.
+This cast may be compared to a bronze statue, representing merely the
+superficial form, and not the internal organization; but there is another
+description of petrifaction by no means uncommon, and of a much more
+wonderful kind, which may be compared to certain anatomical models in wax,
+where not only the outward forms and features, but the nerves,
+blood-vessels, and other internal organs are also shown. Thus we find
+corals, originally calcareous, in which not only the general shape, but
+also the minute and complicated internal organization are retained in
+flint.</p>
+
+<a id="img063" name="img063"></a>
+<div class="figcenter smaller width325">
+<p>Fig. 58.</p>
+<img src="images/img063.jpg" width="317" height="350" alt="" title="">
+<p><i>Phasianella Heddingtonensis</i>, and cast of the
+<span class="wosp05">same. Coral</span> Rag.</p></div>
+
+<a id="img064" name="img064"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 59.</p>
+<img src="images/img064.jpg" width="242" height="350" alt="" title="">
+<p><i>Trochus Anglicus</i> and <span class="wosp05">cast. Lias.</span></p></div>
+
+<p>Such a process of petrifaction is still more remarkably exhibited in fossil
+wood, in which we often perceive not only the rings of annual growth, but
+all the minute vessels and medullary rays. Many of the minute pores and
+fibres of plants, and even those spiral vessels which in the living
+vegetable can only be discovered by the microscope, are preserved. Among
+many instances, I may mention a fossil tree, 72 feet in length, found at
+Gosforth near Newcastle, in sandstone strata associated with coal. By
+cutting a transverse slice <span class="pagenum"><a id="page40"></a>[p.40]</span>so thin as to transmit light, and
+magnifying it about fifty-five times, the texture seen in <a href="#img065">fig. 60.</a> is
+exhibited. A texture equally minute and complicated has been observed in
+the wood of large trunks of fossil trees found in the Craigleith quarry
+near Edinburgh, where the stone was not in the slightest degree siliceous,
+but consisted chiefly of carbonate of lime, with oxide of iron, alumina,
+and carbon. The parallel rows of vessels here seen are the rings of annual
+growth, but in one part they are imperfectly preserved, the wood having
+probably decayed before the mineralizing matter had penetrated to that
+portion of the tree.</p>
+
+<a id="img065" name="img065"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 60.</p>
+<img src="images/img065.jpg" width="250" height="197" alt="" title="">
+<p>Texture of a tree from the coal strata, <span class="wosp05">magnified.
+(Witham.)</span> Transverse section.</p></div>
+
+<p>In attempting to explain the process of petrifaction in such cases, we may
+first assume that strata are very generally permeated by water charged with
+minute portions of calcareous, siliceous, and other earths in solution. In
+what manner they become so impregnated will be afterwards considered. If an
+organic substance is exposed in the open air to the action of the sun and
+rain, it will in time putrefy, or be dissolved into its component elements,
+which consist chiefly of oxygen, hydrogen, and carbon. These will readily
+be absorbed by the atmosphere or be washed away by rain, so that all
+vestiges of the dead animal or plant disappear. But if the same substances
+be submerged in water, they decompose more gradually; and if buried in
+earth, still more slowly, as in the familiar example of wooden piles or
+other buried timber. Now, if as fast as each particle is set free by
+putrefaction in a fluid or gaseous state, a particle equally minute of
+carbonate of lime, flint, or other mineral, is at hand and ready to be
+precipitated, we may imagine this inorganic matter to take the place just
+before left unoccupied by the organic molecule. In this manner a cast of
+the interior of certain vessels may first be taken, and afterwards the more
+solid walls of the same may decay and suffer a like transmutation. Yet when
+the whole is lapidified, it may not form one homogeneous mass of stone or
+metal. Some of the original ligneous, osseous, or other organic elements
+may remain mingled in certain parts, or the lapidifying substance itself
+may be differently coloured at different times, or so crystallized as to
+reflect light differently, and thus the texture of the original body may be
+faithfully exhibited.</p>
+
+<p>The student may perhaps ask whether, on chemical principles, we have any
+ground to expect that mineral matter will be thrown down precisely in those
+spots where organic decomposition is in progress? The following curious
+experiments may serve to illustrate this point. Professor G�ppert of
+Breslau attempted recently to imitate the natural process of petrifaction.
+For this purpose he steeped a variety of animal and vegetable substances in
+waters, some holding siliceous, others calcareous, others metallic matter
+in solution. He found that in the period of a few weeks, or even days, the
+organic bodies thus immersed were mineralized to a certain extent. Thus,
+for example, <span class="pagenum"><a id="page41"></a>[p.41]</span>thin vertical slices of deal, taken from the Scotch
+fir (<i>Pinus sylvestris</i>), were immersed in a moderately strong solution of
+sulphate of iron. When they had been thoroughly soaked in the liquid for
+several days they were dried and exposed to a red-heat until the vegetable
+matter was burnt up and nothing remained but an oxide of iron, which was
+found to have taken the form of the deal so exactly that casts even of the
+dotted vessels peculiar to this family of plants were distinctly visible
+under the microscope.</p>
+
+<p>Another accidental experiment has been recorded by Mr. Pepys in the
+Geological Transactions.<a name="FNanchor_F_7" id="FNanchor_F_7"></a><a href="#Footnote_F_7" class="fnanchor">[41-A]</a> An earthen pitcher containing several quarts
+of sulphate of iron had remained undisturbed and unnoticed for about a
+twelvemonth in the laboratory. At the end of this time when the liquor was
+examined an oily appearance was observed on the surface, and a yellowish
+powder, which proved to be sulphur, together with a quantity of small
+hairs. At the bottom were discovered the bones of several mice in a
+sediment consisting of small grains of pyrites, others of sulphur, others
+of crystallized green sulphate of iron, and a black muddy oxide of iron. It
+was evident that some mice had accidentally been drowned in the fluid, and
+by the mutual action of the animal matter and the sulphate of iron on each
+other, the metallic sulphate had been deprived of its oxygen; hence the
+pyrites and the other compounds were thrown down. Although the mice were
+not mineralized, or turned into pyrites, the phenomenon shows how mineral
+waters, charged with sulphate of iron, may be deoxydated on coming in
+contact with animal matter undergoing putrefaction, so that atom after atom
+of pyrites may be precipitated, and ready, under favourable circumstances,
+to replace the oxygen, hydrogen, and carbon into which the original body
+would be resolved.</p>
+
+<p>The late Dr. Turner observes, that when mineral matter is in a "nascent
+state," that is to say, just liberated from a previous state of chemical
+combination, it is most ready to unite with other matter, and form a new
+chemical compound. Probably the particles or atoms just set free are of
+extreme minuteness, and therefore move more freely, and are more ready to
+obey any impulse of chemical affinity. Whatever be the cause, it clearly
+follows, as before stated, that where organic matter newly imbedded in
+sediment is decomposing, there will chemical changes take place most
+actively.</p>
+
+<p>An analysis was lately made of the water which was flowing off from the
+rich mud deposited by the Hooghly river in the Delta of the Ganges after
+the annual inundation. This water was found to be highly charged with
+carbonic acid gas holding lime in solution.<a name="FNanchor_F_8" id="FNanchor_F_8"></a><a href="#Footnote_F_8" class="fnanchor">[41-B]</a> Now if newly-deposited
+mud is thus proved to be permeated by mineral matter in a state of
+solution, it is not difficult to perceive that decomposing organic bodies,
+naturally imbedded in sediment, may as readily become petrified as the
+substances artificially immersed by Professor G�ppert in various fluid
+mixtures.</p>
+
+<p><span class="pagenum"><a id="page42"></a>[p.42]</span>It is well known that the water of springs, or that which is
+continually percolating the earth's crust, is rarely free from a slight
+admixture either of iron, carbonate of lime, sulphur, silica, potash, or
+some other earthy, alkaline, or metallic ingredient. Hot springs in
+particular are copiously charged with one or more of these elements; and it
+is only in their waters that silex is found in abundance. In certain cases,
+therefore, especially in volcanic regions, we may imagine the flint of
+silicified wood and corals to have been supplied by the waters of thermal
+springs. In other instances, as in tripoli and chalk-flint, it may have
+been derived in great part, if not wholly, from the decomposition of
+infusoria or diatomace�, sponges, and other bodies. But even if this be
+granted, we have still to inquire whence a lake or the ocean can be
+constantly replenished with the calcareous and siliceous matter so
+abundantly withdrawn from it by the secretions of these zoophytes.</p>
+
+<p>In regard to carbonate of lime there is no difficulty, because not only are
+calcareous springs very numerous, but even rain-water has the power of
+dissolving a minute portion of the calcareous rocks over which it flows.
+Hence marine corals and mollusca may be provided by rivers with the
+materials of their shells and solid supports. But pure silex, even when
+reduced to the finest powder and boiled, is insoluble in water, except at
+very high temperatures. Nevertheless Dr. Turner has well explained, in an
+essay on the chemistry of geology<a name="FNanchor_F_9" id="FNanchor_F_9"></a><a href="#Footnote_F_9" class="fnanchor">[42-A]</a>, how the decomposition of felspar
+may be a source of silex in solution. He has remarked that the siliceous
+earth, which constitutes more than half the bulk of felspar, is intimately
+combined with alumine, potash, and some other elements. The alkaline matter
+of the felspar has a chemical affinity for water, as also for the carbonic
+acid which is more or less contained in the waters of most springs. The
+water therefore carries away alkaline matter, and leaves behind a clay
+consisting of alumine and silica. But this residue of the decomposed
+mineral, which in its purest state is called porcelain clay, is found to
+contain a part only of the silica which existed in the original felspar.
+The other part, therefore, must have been dissolved and removed; and this
+can be accounted for in two ways; first, because silica when combined with
+an alkali is soluble in water; secondly, because silica in what is
+technically called its nascent state is also soluble in water. Hence an
+endless supply of silica is afforded to rivers and the waters of the sea.
+For the felspathic rocks are universally distributed, constituting, as they
+do, so large a proportion of the volcanic, plutonic, and metamorphic
+formations. Even where they chance to be absent in mass, they rarely fail
+to occur in the superficial gravel or alluvial deposits of the basin of
+every large river.</p>
+
+<p>The disintegration of mica also, another mineral which enters largely into
+the composition of granite and various sandstones, may <span class="pagenum"><a id="page43"></a>[p.43]</span>yield
+silica which may be dissolved in water, for nearly half of this mineral
+consists of silica, combined with alumine, potash, and about a tenth part
+of iron. The oxidation of this iron in the air is the principal cause of
+the waste of mica.</p>
+
+<p>We have still, however, much to learn before the conversion of fossil
+bodies into stone is fully understood. Some phenomena seem to imply that
+the mineralization must proceed with considerable rapidity, for stems of a
+soft and succulent character, and of a most perishable nature, are
+preserved in flint; and there are instances of the complete silicification
+of the young leaves of a palm-tree when just about to shoot forth, and in
+that state which in the West Indies is called the cabbage of the
+palm.<a name="FNanchor_F_10" id="FNanchor_F_10"></a><a href="#Footnote_F_10" class="fnanchor">[43-A]</a> It may, however, be questioned whether in such cases there may
+not have been some antiseptic quality in the water which retarded
+putrefaction, so that the soft parts of the buried substance may have
+remained for a long time without disintegration, like the flesh of bodies
+imbedded in peat.</p>
+
+<p>Mr. Stokes has pointed out examples of petrifactions in which the more
+perishable, and others where the more durable portions of wood are
+preserved. These variations, he suggests, must doubtless have depended on
+the time when the lapidifying mineral was introduced. Thus, in certain
+silicified stems of palm-trees, the cellular tissue, that most destructible
+part, is in good condition, while all signs of the hard woody fibre have
+disappeared, the spaces once occupied by it being hollow or filled with
+agate. Here, petrifaction must have commenced soon after the wood was
+exposed to the action of moisture, and the supply of mineral matter must
+then have failed, or the water must have become too much diluted before the
+woody fibre decayed. But when this fibre is alone discoverable, we must
+suppose that an interval of time elapsed before the commencement of
+lapidification, during which the cellular tissue was obliterated. When both
+structures, namely, the cellular and the woody fibre, are preserved, the
+process must have commenced at an early period, and continued without
+interruption till it was completed throughout.<a name="FNanchor_F_11" id="FNanchor_F_11"></a><a href="#Footnote_F_11" class="fnanchor">[43-B]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page44"></a>[p.44]</span>CHAPTER V.</h2>
+
+<h4>ELEVATION OF STRATA ABOVE THE SEA&mdash;HORIZONTAL AND INCLINED STRATIFICATION.</h4>
+
+<div class="blq1">
+<p class="indentm2">Why the position of marine strata, above the level of the sea, should
+be referred to the rising up of the land, not to the going down of the
+sea &mdash; Upheaval of extensive masses of horizontal strata &mdash; Inclined and
+vertical stratification &mdash; Anticlinal and synclinal lines &mdash; Bent strata
+in east of Scotland &mdash; Theory of folding by lateral
+movement &mdash; Creeps &mdash; Dip and strike &mdash; Structure of the Jura &mdash; Various forms
+of outcrop &mdash; Rocks broken by flexure &mdash; Inverted position of disturbed
+strata &mdash; Unconformable stratification &mdash; Hutton and Playfair on the
+same &mdash; Fractures of strata &mdash; Polished surfaces &mdash; Faults &mdash; Appearance of
+repeated alternations produced by them &mdash; Origin of great faults.</p></div>
+
+
+<p><i><span class="smcap">Land</span> has been raised, not the sea lowered.</i>&mdash;It has been already stated
+that the aqueous rocks containing marine fossils extend over wide
+continental tracts, and are seen in mountain chains rising to great heights
+above the level of the sea. Hence it follows, that what is now dry land was
+once under water. But if we admit this conclusion, we must imagine, either
+that there has been a general lowering of the waters of the ocean, or that
+the solid rocks, once covered by water, have been raised up bodily out of
+the sea, and have thus become dry land. The earlier geologists, finding
+themselves reduced to this alternative, embraced the former opinion,
+assuming that the ocean was originally universal, and had gradually sunk
+down to its actual level, so that the present islands and continents were
+left dry. It seemed to them far easier to conceive that the water had gone
+down, than that solid land had risen upwards into its present position. It
+was, however, impossible to invent any satisfactory hypothesis to explain
+the disappearance of so enormous a body of water throughout the globe, it
+being necessary to infer that the ocean had once stood at whatever height
+marine shells might be detected. It moreover appeared clear, as the science
+of Geology advanced, that certain spaces on the globe had been alternately
+sea, then land, then estuary, then sea again, and, lastly, once more
+habitable land, having remained in each of these states for considerable
+periods. In order to account for such phenomena, without admitting any
+movement of the land itself, we are required to imagine several retreats
+and returns of the ocean; and even then our theory applies merely to cases
+where the marine strata composing the dry land are horizontal, leaving
+unexplained those more common instances where strata are inclined, curved,
+or placed on their edges, and evidently not in the position in which they
+were first deposited.</p>
+
+<p>Geologists, therefore, were at last compelled to have recourse to the other
+alternative, namely, the doctrine that the solid land has been repeatedly
+moved upwards or downwards, so as permanently to change its position
+relatively to the sea. There are several distinct <span class="pagenum"><a id="page45"></a>[p.45]</span>grounds for
+preferring this conclusion. First, it will account equally for the position
+of those elevated masses of marine origin in which the stratification
+remains horizontal, and for those in which the strata are disturbed,
+broken, inclined, or vertical. Secondly, it is consistent with human
+experience that land should rise gradually in some places and be depressed
+in others. Such changes have actually occurred in our own days, and are now
+in progress, having been accompanied in some cases by violent convulsions,
+while in others they have proceeded so insensibly, as to have been
+ascertainable only by the most careful scientific observations, made at
+considerable intervals of time. On the other hand, there is no evidence
+from human experience of a lowering of the sea's level in any region, and
+the ocean cannot sink in one place without its level being depressed all
+over the globe.</p>
+
+<p>These preliminary remarks will prepare the reader to understand the great
+theoretical interest attached to all facts connected with the position of
+strata, whether horizontal or inclined, curved or vertical.</p>
+
+<p>Now the first and most simple appearance is where strata of marine origin
+occur above the level of the sea in horizontal position. Such are the
+strata which we meet with in the south of Sicily, filled with shells for
+the most part of the same species as those now living in the Mediterranean.
+Some of these rocks rise to the height of more than 2000 feet above the
+sea. Other mountain masses might be mentioned, composed of horizontal
+strata of high antiquity, which contain fossil remains of animals wholly
+dissimilar from any now known to exist. In the south of Sweden, for
+example, near Lake Wener, the beds of one of the oldest of the
+fossiliferous deposits, namely that formerly called Transition, and now
+Silurian, by geologists, occur in as level a position as if they had
+recently formed part of the delta of a great river, and been left dry on
+the retiring of the annual floods. Aqueous rocks of about the same age
+extend for hundreds of miles over the lake-district of North America, and
+exhibit in like manner a stratification nearly undisturbed. The Table
+Mountain at the Cape of Good Hope is another example of highly elevated yet
+perfectly horizontal strata, no less than 3500 feet in thickness, and
+consisting of sandstone of very ancient date.</p>
+
+<p>Instead of imagining that such fossiliferous rocks were always at their
+present level, and that the sea was once high enough to cover them, we
+suppose them to have constituted the ancient bed of the ocean, and that
+they were gradually uplifted to their present height. This idea, however
+startling it may at first appear, is quite in accordance, as before stated,
+with the analogy of changes now going on in certain regions of the globe.
+Thus, in parts of Sweden, and the shores and islands of the Gulf of
+Bothnia, proofs have been obtained that the land is experiencing, and has
+experienced for centuries, a slow upheaving movement. Playfair argued in
+favour of this opinion in 1802; and in 1807, Von Buch, after his travels in
+Scandinavia, announced his conviction that a rising of the land was in
+progress. Celsius and other Swedish writers had, a century before, declared
+their belief that a gradual change had, for ages, <span class="pagenum"><a id="page46"></a>[p.46]</span>been taking
+place in the relative level of land and sea. They attributed the change to
+a fall of the waters both of the ocean and the Baltic. This theory,
+however, has now been refuted by abundant evidence; for the alteration of
+relative level has neither been universal nor every where uniform in
+quantity, but has amounted, in some regions, to several feet in a century,
+in others to a few inches; while in the southernmost part of Sweden, or the
+province of Scania, there has been actually a loss instead of a gain of
+land, buildings having gradually sunk below the level of the sea.<a name="FNanchor_G_1" id="FNanchor_G_1"></a><a href="#Footnote_G_1" class="fnanchor">[46-A]</a></p>
+
+<p>It appears, from the observations of Mr. Darwin and others, that very
+extensive regions of the continent of South America have been undergoing
+slow and gradual upheaval, by which the level plains of Patagonia, covered
+with recent marine shells, and the Pampas of Buenos Ayres, have been raised
+above the level of the sea.<a name="FNanchor_G_2" id="FNanchor_G_2"></a><a href="#Footnote_G_2" class="fnanchor">[46-B]</a> On the other hand, the gradual sinking of
+the west coast of Greenland, for the space of more than 600 miles from
+north to south, during the last four centuries, has been established by the
+observations of a Danish naturalist, Dr. Pingel. And while these proofs of
+continental elevation and subsidence, by slow and insensible movements,
+have been recently brought to light, the evidence has been daily
+strengthened of continued changes of level effected by violent convulsions
+in countries where earthquakes are frequent. There the rocks are rent from
+time to time, and heaved up or thrown down several feet at once, and
+disturbed in such a manner, that the original position of strata may, in
+the course of centuries, be modified to any amount.</p>
+
+<p>It has also been shown by Mr. Darwin, that, in those seas where circular
+coral islands and barrier reefs abound, there is a slow and continued
+sinking of the submarine mountains on which the masses of coral are based;
+while there are other areas of the South Sea, where the land is on the
+rise, and where coral has been upheaved far above the sea-level.</p>
+
+<p>It would require a volume to explain to the reader the various facts which
+establish the reality of these movements of land, whether of elevation or
+depression, whether accompanied by earthquakes or accomplished slowly and
+without local disturbance. Having treated fully of these subjects in the
+Principles of Geology<a name="FNanchor_G_3" id="FNanchor_G_3"></a><a href="#Footnote_G_3" class="fnanchor">[46-C]</a>, I shall assume, in the present work, that such
+changes are part of the actual course of nature; and when admitted, they
+will be found to afford a key to the interpretation of a variety of
+geological appearances, such as the elevation of horizontal, inclined, or
+disturbed marine strata, and the superposition of freshwater to marine
+deposits, afterwards to be described. It will also appear, in the sequel,
+how much light the <span class="pagenum"><a id="page47"></a>[p.47]</span>doctrine of a continued subsidence of land may
+throw on the manner in which a series of strata, formed in shallow water,
+may have accumulated to a great thickness. The excavation of valleys also,
+and other effects of <i>denudation</i>, of which I shall presently treat, can
+alone be understood when we duly appreciate the proofs, now on record, of
+the prolonged rising and sinking of land, throughout wide areas.</p>
+
+<p>To conclude this subject, I may remind the reader, that were we to embrace
+the doctrine which ascribes the elevated position of marine formations, and
+the depression of certain freshwater strata, to oscillations in the level
+of the waters instead of the land, we should be compelled to admit that the
+ocean has been sometimes every where much shallower than at present, and at
+others more than three miles deeper.</p>
+
+<a id="img066" name="img066"></a>
+<div class="floatright smaller width250">
+<p>Fig. 61.</p>
+<img src="images/img066.jpg" width="250" height="164" alt="" title="">
+<p>Vertical conglomerate and sandstone.</p></div>
+
+<p><i>Inclined stratification.</i>&mdash;The most unequivocal evidence of a change in
+the original position of strata is afforded by their standing up
+perpendicularly on their edges, which is by no means a rare phenomenon,
+especially in mountainous countries. Thus we find in Scotland, on the
+southern skirts of the Grampians, beds of pudding-stone alternating with
+thin layers of fine sand, all placed vertically to the horizon. When
+Saussure first observed certain conglomerates in a similar position in the
+Swiss Alps, he remarked that the pebbles, being for the most part of an
+oval shape, had their longer axes parallel to the planes of stratification
+(See <a href="#img066">fig. 61.</a>). From this he inferred, that such strata must, at first,
+have been horizontal, each oval pebble having originally settled at the
+bottom of the water, with its flatter side parallel to the horizon, for the
+same reason that an egg will not stand on either end if unsupported. Some
+few, indeed, of the rounded stones in a conglomerate occasionally afford an
+exception to the above rule, for the same reason that we see on a shingle
+beach some oval or flat-sided pebbles resting on their ends or edges; these
+having been forced along the bottom and against each other by a wave or
+current so as to settle in this position.</p>
+
+<p>Vertical strata, when they can be traced continuously upwards or downwards
+for some depth, are almost invariably seen to be parts of great curves,
+which may have a diameter of a few yards, or of several miles. I shall
+first describe two curves of considerable regularity, which occur in
+Forfarshire, extending over a country twenty miles in breadth, from the
+foot of the Grampians to the sea near Arbroath.</p>
+
+<p>The mass of strata here shown may be nearly 2000 feet in thickness,
+consisting of red and white sandstone, and various coloured shales, the
+beds being distinguishable into four principal groups, namely, No. 1. red
+marl or shale; No. 2. red sandstone, used for building; No. 3.
+conglomerate; and No. 4. grey paving-stone, and tile-stone, with green and
+reddish shale, containing peculiar organic remains. A glance at the section
+will show that each of the formations <span class="pagenum"><a id="page48"></a>[p.48]</span>2, 3, 4, are repeated thrice
+at the surface, twice with a southerly, and once with a northerly
+inclination or <i>dip</i>, and the beds in No. 1., which are nearly horizontal,
+are still brought up twice by a slight curvature to the surface, once on
+each side of A. Beginning at the north-west extremity, the tile-stones and
+conglomerates No. 4. and No. 3. are vertical, and they generally form a
+ridge parallel to the southern skirts of the Grampians. The superior strata
+Nos. 2. and 1. become less and less inclined on descending to the valley of
+Strathmore, where the strata, having a concave bend, are said by geologists
+to lie in a "trough" or "basin." Through the centre of this valley runs an
+imaginary line A, called technically a "synclinal line," where the beds,
+which are tilted in opposite directions, may be supposed to meet. It is
+most important for the observer to mark such lines, for he will perceive by
+the diagram, that in travelling from the north to the centre of the basin,
+he is always passing from older to newer beds; whereas, after crossing the
+line A, and pursuing his course in the same southerly direction, he is
+continually leaving the newer, and advancing upon older strata. All the
+deposits which he had before examined begin then to recur in reversed
+order, until he arrives at the central axis of the Sidlaw hills, where the
+strata are seen to form an arch or <i>saddle</i>, having an <i>anticlinal</i> line B,
+in the centre. On passing this line, and continuing towards the S.E., the
+formations 4, 3, and 2, are again repeated, in the same relative order of
+superposition, but with a northerly dip. At Whiteness (see diagram) it will
+be seen that the inclined strata are covered by a newer deposit, <i>a</i>, in
+horizontal beds. These are composed of red conglomerate and sand, and are
+newer than any of the groups, 1, 2, 3, 4, before described, and rest
+<i>unconformably</i> upon strata of the sandstone group, No. 2.</p>
+
+<a id="img067" name="img067"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 62.</p>
+<img src="images/img067.jpg" width="500" height="113" alt="" title="">
+<p>Section of Forfarshire, from N.W. to S.E., from
+foot of the Grampians to the sea at Arbroath (volcanic or trap rocks
+omitted). Length of section twenty miles.</p></div>
+
+<p>An example of curved strata, in which the bends or convolutions of the rock
+are sharper and far more numerous within an equal space, has been well
+described by Sir James Hall.<a name="FNanchor_G_4" id="FNanchor_G_4"></a><a href="#Footnote_G_4" class="fnanchor">[48-A]</a> It occurs near St. <span class="pagenum"><a id="page49"></a>[p.49]</span>Abb's Head,
+on the east coast of Scotland, where the rocks consist principally of a
+bluish slate, having frequently a ripple-marked surface. The undulations of
+the beds reach from the top to the bottom of cliffs from 200 to 300 feet in
+height, and there are sixteen distinct bendings in the course of about six
+miles, the curvatures being alternately concave and convex upwards.</p>
+
+<a id="img068" name="img068"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 63.</p>
+<img src="images/img068.jpg" width="400" height="220" alt="" title="">
+<p>Curved strata of slate near St. Abb's Head,
+<span class="wosp05">Berwickshire. (Sir</span> J. Hall.)</p></div>
+
+<a id="img069" name="img069"></a>
+<div class="figcenter smaller">
+<p class="martop2">Fig. 64.</p>
+<img src="images/img069.jpg" width="400" height="212" alt="" title=""></div>
+
+<p>An experiment was made by Sir James Hall, with a view of illustrating the
+manner in which such strata, assuming them to have been originally
+horizontal, may have been forced into their present position. A set of
+layers of clay were placed under a weight, and their opposite ends pressed
+towards each other with such force as to cause them to approach more nearly
+together. On the removal of the weight, the layers of clay were found to be
+curved and folded, so as to bear a miniature resemblance to the strata in
+the cliffs. We must, however, bear in mind, that in the natural section or
+sea-cliff we only see the foldings imperfectly, one part being invisible
+beneath the sea, and the other, or upper portion, being supposed to have
+been carried away by <i>denudation</i>, or that action of water which will be
+explained in the next chapter. The dark lines in the accompanying plan
+(<a href="#img069">fig. 64.</a>) represent what is actually seen of the strata in part of the
+line of cliff alluded to; the fainter lines, that portion which is <span class="pagenum"><a id="page50"></a>[p.50]</span>
+concealed beneath the sea level, as also that which is supposed to have
+once existed above the present surface.</p>
+
+<a id="img070" name="img070"></a>
+<div class="figcenter smaller">
+<p>Fig. 65.</p>
+<img src="images/img070.jpg" width="350" height="181" alt="" title=""></div>
+
+<p>We may still more easily illustrate the effects which a lateral thrust
+might produce on flexible strata, by placing several pieces of differently
+coloured cloths upon a table, and when they are spread out horizontally,
+cover them with a book. Then apply other books to each end, and force them
+towards each other. The folding of the cloths will exactly imitate those of
+the bent strata. (See <a href="#img070">fig. 65.</a>)</p>
+
+<p>Whether the analogous flexures in stratified rocks have really been due to
+similar sideway movements is a question of considerable difficulty. It will
+appear when the volcanic and granitic rocks are described, that some of
+them have, when melted, been injected forcibly into fissures, while others,
+already in a solid state, have been protruded upwards through the incumbent
+crust of the earth, by which a great displacement of flexible strata must
+have been caused.</p>
+
+<p>But we also know by the study of regions liable to earthquakes, that there
+are causes at work in the interior of the earth capable of producing a
+sinking in of the ground, sometimes very local, but sometimes extending
+over a wide area. The frequent repetition, or continuance throughout long
+periods, of such downward movements seems to imply the formation and
+renewal of cavities at a certain depth below the surface, whether by the
+removal of matter by volcanos and hot springs, or by the contraction of
+argillaceous rocks by heat and pressure, or any other combination of
+circumstances. Whatever conjectures we may indulge respecting the causes,
+it is certain that pliable beds may, in consequence of unequal degrees of
+subsidence, become folded to any amount, and have all the appearance of
+having been compressed suddenly by a lateral thrust.</p>
+
+<p>The "Creeps," as they are called in coal-mines, afford an excellent
+illustration of this fact.&mdash;First, it may be stated generally, that the
+excavation of coal at a considerable depth causes the mass of overlying
+strata to sink down bodily, even when props are left to support the roof of
+the mine. "In Yorkshire," says Mr. Buddle, "three distinct subsidences were
+perceptible at the surface, after the clearing out of three seams of coal
+below, and innumerable vertical cracks were caused in the incumbent mass of
+sandstone and shale, which thus settled down."<a name="FNanchor_G_5" id="FNanchor_G_5"></a><a href="#Footnote_G_5" class="fnanchor">[50-A]</a> The exact amount of
+depression in these cases <span class="pagenum"><a id="page51"></a>[p.51]</span>can only be accurately measured where
+water accumulates on the surface, or a railway traverses a coal-field.</p>
+
+<a id="img071" name="img071"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 66.</p>
+<img src="images/img071.jpg" width="500" height="226" alt="" title="">
+<p>Section of carboniferous strata, at Wallsend,
+Newcastle, showing "Creeps." (J. Buddle, Esq.) Horizontal length of section
+174 feet. The upper seam, or main coal, here worked out, was 630 feet below
+the surface.</p></div>
+
+<p>When a bed of coal is worked out, pillars or rectangular masses of coal are
+left at intervals as props to support the roof, and protect the colliers.
+Thus in <a href="#img071">fig. 66.</a>, representing a section at Wallsend, Newcastle, the
+galleries which have been excavated are represented by the white spaces <i>a
+b</i>, while the adjoining dark portions are parts of the original coal-seam
+left as props, beds of sandy clay or shale constituting the floor of the
+mine. When the props have been reduced <span class="pagenum"><a id="page52"></a>[p.52]</span>in size, they are pressed
+down by the weight of overlying rocks (no less than 630 feet thick) upon
+the shale below, which is thereby squeezed and forced up into the open
+spaces.</p>
+
+<p>Now it might have been expected, that instead of the floor rising up, the
+ceiling would sink down, and this effect, called a "Thrust," does, in fact,
+take place where the pavement is more solid than the roof. But it usually
+happens, in coal-mines, that the roof is composed of hard shale, or
+occasionally of sandstone, more unyielding than the foundation, which often
+consists of clay. Even where the argillaceous substrata are hard at first,
+they soon become softened and reduced to a plastic state when exposed to
+the contact of air and water in the floor of a mine.</p>
+
+<p>The first symptom of a "creep," says Mr. Buddle, is a slight curvature at
+the bottom of each gallery, as at <i>a</i>, <a href="#img071">fig. 66.</a>: then the pavement
+continuing to rise, begins to open with a longitudinal crack, as at <i>b</i>:
+then the points of the fractured ridge reach the roof, as at <i>c</i>; and,
+lastly, the upraised beds close up the whole gallery, and the broken
+portions of the ridge are re-united and flattened at the top, exhibiting
+the flexure seen at <i>d</i>. Meanwhile the coal in the props has become crushed
+and cracked by pressure. It is also found, that below the creeps <i>a</i>, <i>b</i>,
+<i>c</i>, <i>d</i>, an inferior stratum, called the "metal coal," which is 3 feet
+thick, has been fractured at the points <i>e</i>, <i>f</i>, <i>g</i>, <i>h</i>, and has risen,
+so as to prove that the upward movement, caused by the working out of the
+"main coal," has been propagated through a thickness of 54 feet of
+argillaceous beds, which intervene between the two coal seams. This same
+displacement has also been traced downwards more than 150 feet below the
+metal coal, but it grows continually less and less until it becomes
+imperceptible.</p>
+
+<p>No part of the process above described is more deserving of our notice than
+the slowness with which the change in the arrangement of the beds is
+brought about. Days, months, or even years, will sometimes elapse between
+the first bending of the pavement and the time of its reaching the roof.
+Where the movement has been most rapid, the curvature of the beds is most
+regular, and the reunion of the fractured ends most complete; whereas the
+signs of displacement or violence are greatest in those creeps which have
+required months or years for their entire accomplishment. Hence we may
+conclude that similar changes may have been wrought on a larger scale in
+the earth's crust by partial and gradual subsidences, especially where the
+ground has been undermined throughout long periods of time; and we must be
+on our guard against inferring sudden violence, simply because the
+distortion of the beds is excessive.</p>
+
+<p>Between the layers of shale, accompanying coal, we sometimes see the leaves
+of fossil ferns spread out as regularly as dried plants between sheets of
+paper in the herbarium of a botanist. These fern-leaves, or fronds, must
+have rested horizontally on soft mud, when first deposited. If, therefore,
+they and the layers of shale are now inclined, or standing on end, it is
+obviously the effect of subsequent derangement. The proof becomes, if
+possible, still more striking <span class="pagenum"><a id="page53"></a>[p.53]</span>when these strata, including
+vegetable remains, are curved again and again, and even folded into the
+form of the letter Z, so that the same continuous layer of coal is cut
+through several times in the same perpendicular shaft. Thus, in the
+coal-field near Mons, in Belgium, these zigzag bendings are repeated four
+or five times, in the manner represented in <a href="#img072">fig. 67.</a>, the black lines
+representing seams of coal.<a name="FNanchor_G_6" id="FNanchor_G_6"></a><a href="#Footnote_G_6" class="fnanchor">[53-A]</a></p>
+
+<a id="img072" name="img072"></a>
+<div class="figcenter center">
+<p>Fig. 67.</p>
+<img src="images/img072.jpg" width="400" height="214" alt="" title="">
+<p>Zigzag flexures of coal near Mons.</p></div>
+
+<p><i>Dip and Strike.</i>&mdash;In the above remarks, several technical terms have been
+used, such as <i>dip</i>, the <i>unconformable position</i> of strata, and the
+<i>anticlinal</i> and <i>synclinal</i> lines, which, as well as the <i>strike</i> of the
+beds, I shall now explain. If a stratum or bed of rock, instead of being
+quite level, be inclined to one side, it is said to <i>dip</i>; the point of the
+compass to which it is inclined is called the <i>point of dip</i>, and the
+degree of deviation from a level or horizontal line is called <i>the amount
+of dip</i>, or <i>the angle of dip</i>. Thus, in the annexed diagram (<a href="#img073">fig. 68.</a>), a
+series of strata are inclined, and they dip to the north at an angle of
+forty-five degrees. The <i>strike</i>, or <i>line of bearing</i>, is the prolongation
+or extension of the strata in a direction <i>at right angles</i> to the dip; and
+hence it is sometimes called the <i>direction</i> of the strata. Thus, in the
+above instance of strata dipping to the north, their strike must
+necessarily be east and west. We have borrowed the word from the German
+geologists, <i>streichen</i> signifying to extend, to have a certain direction.
+Dip and strike may be aptly illustrated by a row of houses running east and
+west, the long ridge of the roof representing the strike of the stratum of
+slates, which dip on one side to the north, and on the other to the south.</p>
+
+<a id="img073" name="img073"></a>
+<div class="figcenter smaller">
+<p>Fig. 68.</p>
+<img src="images/img073.jpg" width="300" height="114" alt="" title=""></div>
+
+<p>A stratum which is horizontal, or quite level in
+all directions, has neither dip nor strike.</p>
+
+<p>It is always important for the geologist, who is endeavouring to comprehend
+the structure of a country, to learn how the beds dip in every part of the
+district; but it requires some practice to avoid being occasionally
+deceived, both as to the point of dip and the amount of it.</p>
+
+<span class="pagenum"><a id="page54"></a>[p.54]</span>
+<a id="img074" name="img074"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 69.</p>
+<img src="images/img074.jpg" width="450" height="268" alt="" title="">
+<p>Apparent horizontality of inclined strata.</p></div>
+
+<p>If the upper surface of a hard stony stratum be uncovered, whether
+artificially in a quarry, or by the waves at the foot of a cliff, it is
+easy to determine towards what point of the compass the slope is steepest,
+or in what direction water would flow, if poured upon it. This is the true
+dip. But the edges of highly inclined strata may give rise to perfectly
+horizontal lines in the face of a vertical cliff, if the observer see the
+strata in the line of their strike, the dip being inwards from the face of
+the cliff. If, however, we come to a break in the cliff, which exhibits a
+section exactly at right angles to the line of the strike, we are then able
+to ascertain the true dip. In the annexed drawing (<a href="#img074">fig. 69.</a>), we may
+suppose a headland, one side of which faces to the north, where the beds
+would appear perfectly horizontal to a person in the boat; while in the
+other side facing the west, the true dip would be seen by the person on
+shore to be at an angle of 40�. If, therefore, our observations are
+confined to a vertical precipice facing in one direction, we must endeavour
+to find a ledge or portion of the plane of one of the beds projecting
+beyond the others, in order to ascertain the true dip.</p>
+
+<a id="img075" name="img075"></a>
+<div class="figcenter smaller">
+<p>Fig. 70.</p>
+<img src="images/img075.jpg" width="347" height="350" alt="" title=""></div>
+
+<p>It is rarely important to determine the angle of inclination with such
+minuteness as to require the aid of the instrument called a clinometer. We
+may measure the angle within a few degrees by standing exactly opposite to
+a cliff where the true dip is exhibited, holding the hands immediately
+before the eyes, and placing the fingers of one in a perpendicular, and of
+the other in a horizontal position, as in <a href="#img075">fig. 70.</a> It is thus easy to
+discover whether the lines of the inclined beds bisect the angle of 90�,
+formed by the meeting of the hands, so as to give an angle of 45�, or
+whether it would divide the space into two equal or unequal portions. The
+upper dotted line may express a stratum dipping to the north; but should
+the beds dip precisely to the opposite point of <span class="pagenum"><a id="page55"></a>[p.55]</span>the compass as in
+the lower dotted line, it will be seen that the amount of inclination may
+still be measured by the hands with equal facility.</p>
+
+<a id="img076" name="img076"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 71.</p>
+<img src="images/img076.jpg" width="450" height="295" alt="" title="">
+<p>Section illustrating the structure of the Swiss
+Jura.</p></div>
+
+<a id="img077" name="img077"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 72.</p>
+<img src="images/img077.jpg" width="350" height="225" alt="" title="">
+<p>Ground plan of the denuded ridge, <a href="#img076">fig. 71.</a></p></div>
+
+<a id="img078" name="img078"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 73.</p>
+<img src="images/img078.jpg" width="200" height="062" alt="" title="">
+<p>Transverse section.</p></div>
+
+<p>It has been already seen, in describing the curved strata on the east coast
+of Scotland, in Forfarshire and Berwickshire, that a series of concave and
+convex bendings are occasionally repeated several times. These usually form
+part of a series of parallel waves of strata, which are prolonged in the
+same direction throughout a considerable extent of country. Thus, for
+example, in the Swiss Jura, that lofty chain of mountains has been proved
+to consist of many parallel ridges, with intervening longitudinal valleys,
+as in <a href="#img076">fig. 71.</a>, the ridges being formed by curved fossiliferous strata, of
+which the nature and dip are occasionally displayed in deep transverse
+gorges, called "cluses," caused by fractures at right angles to the
+direction of the chain.<a name="FNanchor_G_7" id="FNanchor_G_7"></a><a href="#Footnote_G_7" class="fnanchor">[55-A]</a> Now let us suppose these ridges and parallel
+valleys to run north and south, we should then say that the <i>strike</i> of the
+beds is north and south, and the <i>dip</i> east and west. Lines drawn along the
+summits of the ridges, A, B, would be anticlinal lines, and one following
+the bottom of the adjoining valleys a synclinal line. It will be observed
+that some of these ridges, A, B, are unbroken on the summit, whereas one of
+them, C, has been fractured along the line of strike, and a portion of it
+carried away by denudation, so that the ridges of the beds in the
+formations <i>a</i>, <i>b</i>, <i>c</i>, come out to the day, or, as the miners say, <i>crop
+out</i>, on the sides of a valley. The ground plan of such a denuded ridge as
+C, as given in a geological map, may be expressed by the diagram <a href="#img077">fig. 72.</a>,
+and the cross section of the same by <a href="#img078">fig. 73.</a> The line D E, <a href="#img077">fig. 72.</a>, is
+the anticlinal line, on each side <span class="pagenum"><a id="page56"></a>[p.56]</span>of which the dip is in opposite
+directions, as expressed by the arrows. The emergence of strata at the
+surface is called by miners their <i>outcrop</i> or <i>basset</i>.</p>
+
+<p>If, instead of being folded into parallel ridges, the beds form a boss or
+dome-shaped protuberance, and if we suppose the summit of the dome carried
+off, the ground plan would exhibit the edges of the strata forming a
+succession of circles, or ellipses, round a common centre. These circles
+are the lines of strike, and the dip being always at right angles is
+inclined in the course of the circuit to every point of the compass,
+constituting what is termed a qua-quaversal dip&mdash;that is, turning each way.</p>
+
+<p>There are endless variations in the figures described by the basset-edges
+of the strata, according to the different inclination of the beds, and the
+mode in which they happen to have been denuded. One of the simplest rules
+with which every geologist should be acquainted, relates to the V-like form
+of the beds as they crop out in an ordinary valley. First, if the strata be
+horizontal, the V-like form will be also on a level, and the newest strata
+will appear at the greatest heights.</p>
+
+<p>Secondly, if the beds be inclined and intersected by a valley sloping in
+the same direction, and the dip of the beds be less steep than the slope of
+the valley, then the V's, as they are often termed by miners, will point
+upwards (see <a href="#img079">fig. 74.</a>), those formed by the newer beds appearing in a
+superior position, and extending highest up the valley, as A is seen
+above B.</p>
+
+<a id="img079" name="img079"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 74.</p>
+<img src="images/img079.jpg" width="400" height="392" alt="" title="">
+<p>Slope of valley 40�, dip of strata 20�.</p></div>
+
+<p>Thirdly, if the dip of the beds be steeper than the slope of the valley,
+then the V's will point downwards (see <a href="#img080">fig. 75.</a>), and those formed of the
+older beds will now appear uppermost, as B appears above A.</p>
+
+<a id="img080" name="img080"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 75.</p>
+<img src="images/img080.jpg" width="400" height="282" alt="" title="">
+<p>Slope of valley 20�, dip of strata 50�.</p></div>
+
+<p>Fourthly, in every case where the strata dip in a contrary direction to the
+slope of the valley, whatever be the angle of inclination, the newer beds
+will appear the highest, as in the first and second cases. This is shown by
+the drawing (<a href="#img081">fig. 76.</a>), which exhibits strata rising at an angle of 20�,
+<span class="pagenum"><a id="page57"></a>[p.57]</span>and crossed by a valley, which declines in an opposite direction
+at 20�.<a name="FNanchor_G_8" id="FNanchor_G_8"></a><a href="#Footnote_G_8" class="fnanchor">[57-A]</a></p>
+
+<a id="img081" name="img081"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 76.</p>
+<img src="images/img081.jpg" width="400" height="271" alt="" title="">
+<p>Slope of valley 20�, dip of strata 20�, in opposite
+directions.</p></div>
+
+<p>These rules may often be of great practical utility; for the different
+degrees of dip occurring in the two cases represented in <a href="#img079">figures 74</a> and <a href="#img080">75.</a>
+may occasionally be encountered in following the same line of flexure at
+points a few miles distant from each other. A miner unacquainted with the
+rule, who had first explored the valley (<a href="#img079">fig. 74.</a>), may have sunk a
+vertical shaft below the coal seam A, until he reached the inferior bed B.
+He might then pass to the valley <a href="#img080">fig. 75.</a>, and discovering there also the
+outcrop of two coal seams, might begin his workings in the uppermost in the
+expectation of coming down to the other bed A, which would be observed
+cropping out lower down the valley. But a glance at the section will
+demonstrate the futility of such hopes.</p>
+
+<p>In the majority of cases, an anticlinal axis forms a ridge, and a synclinal
+axis a valley, as in A, B, <a href="#img067">fig. 62.</a> <a href="#page48">p. 48.</a>; but there are exceptions to
+this rule, the beds sometimes sloping inwards from either side of a
+mountain, as in <a href="#img082">fig. 77.</a></p>
+
+<a id="img082" name="img082"></a>
+<div class="figcenter smaller">
+<p>Fig. 77.</p>
+<img src="images/img082.jpg" width="300" height="175" alt="" title=""></div>
+
+<p>On following one of the anticlinal ridges of the Jura, before mentioned, A,
+B, C, <a href="#img076">fig. 71.</a>, we often discover longitudinal cracks and sometimes large
+fissures along the line where the flexure was greatest. Some of these, as
+above stated, have been enlarged by denudation into valleys of considerable
+width, as at C, <a href="#img076">fig. 71.</a>, which follow the line of strike, and which we may
+suppose to have been hollowed out at the time when these rocks were still
+beneath the level of the sea, or perhaps at the period of their gradual
+emergence from beneath the waters. The existence of such cracks at the
+point of the sharpest bending of solid strata of limestone is precisely
+what we should have expected; but the occasional want of all similar signs
+of fracture, even where the strain has been greatest, as at <i>a</i>, <a href="#img076">fig. 71.</a>,
+is not always easy to explain. We must imagine that many strata of
+limestone, chert, and other rocks which are now brittle, were pliant when
+bent into their present position. <span class="pagenum"><a id="page58"></a>[p.58]</span>They may have owed their
+flexibility in part to the fluid matter which they contained in their
+minute pores, as before described (<a href="#page35">p. 35.</a>), and in part to the permeation
+of sea-water while they were yet submerged.</p>
+
+<a id="img083" name="img083"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 78.</p>
+<img src="images/img083.jpg" width="400" height="090" alt="" title="">
+<p>Strata of chert, grit, and marl, near St. Jean de
+Luz.</p></div>
+
+<p>At the western extremity of the Pyrenees, great curvatures of the strata
+are seen in the sea cliffs, where the rocks consist of marl, grit, and
+chert. At certain points, as at <i>a</i>, <a href="#img083">fig. 78.</a>, some of the bendings of the
+flinty chert are so sharp, that specimens might be broken off, well fitted
+to serve as ridge-tiles on the roof of a house. Although this chert could
+not have been brittle as now, when first folded into this shape, it
+presents, nevertheless, here and there at the points of greatest flexure
+small cracks, which show that it was solid, and not wholly incapable of
+breaking at the period of its displacement. The numerous rents alluded to
+are not empty, but filled with calcedony and quartz.</p>
+
+<a id="img084" name="img084"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 79.</p>
+<img src="images/img084.jpg" width="300" height="201" alt="" title="">
+<ul class="smaller leftal add3em">
+<li><i>g.</i> gypsum.</li>
+<li><i>m.</i> marl.</li>
+</ul></div>
+
+<p>Between San Caterina and Castrogiovanni, in Sicily, bent and undulating
+gypseous marls occur, with here and there thin beds of solid gypsum
+interstratified. Sometimes these solid layers have been broken into
+detached fragments, still preserving their sharp edges (<i>g g</i>, <a href="#img084">fig. 79.</a>),
+while the continuity of the more pliable and ductile marls, <i>m m</i>, has not
+been interrupted.</p>
+
+<a id="img085" name="img085"></a>
+<div class="figcenter smaller">
+<p>Fig. 80.</p>
+<img src="images/img085.jpg" width="300" height="073" alt="" title=""></div>
+
+<p>I shall conclude my remarks on bent strata by stating, that, in mountainous
+regions like the Alps, it is often difficult for an experienced geologist
+to determine correctly the relative age of beds by superposition, so often
+have the strata been folded back upon themselves, the upper parts of the
+curve having been removed by denudation. Thus, if we met with the strata
+seen in the section <a href="#img085">fig. 80.</a>, we should naturally suppose that there were
+twelve distinct beds, or sets of beds, No. 1. being the newest, and No. 12.
+the oldest of the series. But this section may, perhaps, exhibit merely six
+beds, which have been folded in the manner seen in <a href="#img086">fig. 81.</a>, so that each
+of them is twice repeated, the position of one half being reversed, and
+part of No. 1., originally the uppermost, having now become the lowest of
+the series. These phenomena are often observable on a magnificent scale in
+certain regions in Switzerland in precipices from 2000 to 3000 feet in
+perpendicular height. <span class="pagenum"><a id="page59"></a>[p.59]</span>In the Iselten Alp, in the valley of the
+Lutschine, between Unterseen and Grindelwald, curves of calcareous shale
+are seen from 1000 to 1500 feet in height, in which the beds sometimes
+plunge down vertically for a depth of 1000 feet and more, before they bend
+round again. There are many flexures not inferior in dimensions in the
+Pyrenees, as those near Gavarnie, at the base of Mont Perdu.</p>
+
+<a id="img086" name="img086"></a>
+<div class="figcenter smaller">
+<p>Fig. 81.</p>
+<img src="images/img086.jpg" width="400" height="249" alt="" title=""></div>
+
+<a id="img087" name="img087"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 82.</p>
+<img src="images/img087.jpg" width="450" height="346" alt="" title="">
+<p>Curved strata of the Iselten Alp.</p></div>
+
+<a id="img088" name="img088"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 83.</p>
+<img src="images/img088.jpg" width="400" height="127" alt="" title="">
+<p>Unconformable junction of old red sandstone and
+Silurian schist at the Siccar Point, near St. Abb's Head, <span class="wosp05">Berwickshire. See</span>
+also <a href="#img001">Frontispiece.</a></p></div>
+
+<p><i>Unconformable stratification.</i>&mdash;Strata are said to be unconformable, when
+one series is so placed over another, that the planes of the superior
+repose on the edges of the inferior (see <a href="#img088">fig. 83.</a>). In this case it is
+evident that a period had elapsed between the production of the two sets of
+strata, and that, during this interval, the older <span class="pagenum"><a id="page60"></a>[p.60]</span>series had been
+tilted and disturbed. Afterwards the upper series was thrown down in
+horizontal strata upon it. If these superior beds, as <i>d</i>, <i>d</i>, <a href="#img088">fig. 83.</a>,
+are also inclined, it is plain that the lower strata, <i>a</i>, <i>a</i>, have been
+twice displaced; first, before the deposition of the newer beds, <i>d</i>, <i>d</i>,
+and a second time when these same strata were thrown out of the horizontal
+position.</p>
+
+<p>Playfair has remarked<a name="FNanchor_G_9" id="FNanchor_G_9"></a><a href="#Footnote_G_9" class="fnanchor">[60-A]</a> that this kind of junction which we now call
+unconformable had been described before the time of Hutton, but that he was
+the first geologist who appreciated its importance, as illustrating the
+high antiquity and great revolutions of the globe. He had observed that
+where such contacts occur, the lowest beds of the newer series very
+generally consist of a breccia or conglomerate consisting of angular and
+rounded fragments, derived from the breaking up of the more ancient rocks.
+On one occasion the Scotch geologist took his two distinguished pupils,
+Playfair and Sir James Hall, to the cliffs on the east coast of Scotland,
+near the village of Eyemouth, not far from St. Abb's Head, where the
+schists of the Lammermuir range are undermined and dissected by the sea.
+Here the curved and vertical strata, now known to be of Silurian age, and
+which often exhibit a ripple-marked surface<a name="FNanchor_G_10" id="FNanchor_G_10"></a><a href="#Footnote_G_10" class="fnanchor">[60-B]</a>, are well exposed at the
+headland called the Siccar Point, penetrating with their edges into the
+incumbent beds of slightly inclined sandstone, in which large pieces of the
+schist, some round and others angular, are united by an arenaceous cement.
+"What clearer evidence," exclaims Playfair, "could we have had of the
+different formation of these rocks, and of the long interval which
+separated their formation, had we actually seen them emerging from the
+bosom of the deep? We felt ourselves necessarily carried back to the time
+when the schistus on which we stood was yet at the bottom of the sea, and
+when the sandstone before us was only beginning to be deposited in the
+shape of sand or mud, from the waters of a superincumbent ocean. An epoch
+still more remote presented itself, when even the most ancient of these
+rocks, instead of standing upright in vertical beds, lay in horizontal
+planes at the bottom of the sea, and was not yet disturbed by that
+immeasurable force which has burst asunder the solid pavement of the globe.
+Revolutions still more remote appeared in the distance of this
+extraordinary perspective. The mind seemed to grow giddy by looking so far
+into the abyss of time; and while we listened with earnestness and
+admiration to the philosopher who was now unfolding to us the order and
+series of these wonderful events, we became sensible how much farther
+reason may sometimes go than imagination can venture to follow."<a name="FNanchor_G_11" id="FNanchor_G_11"></a><a href="#Footnote_G_11" class="fnanchor">[60-C]</a></p>
+
+<p>In the frontispiece of this volume the reader will see a view of this
+classical spot, reduced from a large picture, faithfully sketched and
+coloured from nature by the youngest son of the late Sir James Hall. It was
+impossible, however, to do justice to the original sketch, in an <span class="pagenum"><a id="page61"></a>[p.61]</span>
+engraving, as the contrast of the red sandstone and the light fawn-coloured
+vertical schists could not be expressed. From the point of view here
+selected, the underlying beds of the perpendicular schist, <i>a</i>, are visible
+at <i>b</i> through a small opening in the fractured beds of the covering of red
+sandstone, <i>d d</i>, while on the vertical face of the old schist at <i>a' a"</i> a
+conspicuous ripple-mark is displayed.</p>
+
+<a id="img089" name="img089"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 84.</p>
+<img src="images/img089.jpg" width="400" height="105" alt="" title="">
+<p>Junction of unconformable strata near Mons, in
+Belgium.</p></div>
+
+<p>It often happens that in the interval between the deposition of two sets of
+unconformable strata, the inferior rock has not only been denuded, but
+drilled by perforating shells. Thus, for example, at Autreppe and Gusigny,
+near Mons, beds of an ancient (paleozoic) limestone, highly inclined, and
+often bent, are covered with horizontal strata of greenish and whitish
+marls of the Cretaceous formation. The lowest and therefore the oldest bed
+of the horizontal series is usually the sand and conglomerate, <i>a</i>, in
+which are rounded fragments of stone, from an inch to two feet in diameter.
+These fragments have often adhering shells attached to them, and have been
+bored by perforating mollusca. The solid surface of the inferior limestone
+has also been bored, so as to exhibit cylindrical and pear-shaped cavities,
+as at <i>c</i>, the work of saxicavous mollusca; and many rents, as at <i>b</i>,
+which descend several feet or yards into the limestone, have been filled
+with sand and shells, similar to those in the stratum <i>a</i>.</p>
+
+<p><i>Fractures of the strata and faults.</i>&mdash;Numerous rents may often be seen in
+rocks which appear to have been simply broken, the separated parts
+remaining in the same places; but we often find a fissure, several inches
+or yards wide, intervening between the disunited portions. These fissures
+are usually filled with fine earth and sand, or with angular fragments of
+stone, evidently derived from the fracture of the contiguous rocks.</p>
+
+<p>The face of each wall of the fissure is often beautifully polished, as if
+glazed, and not unfrequently striated or scored with parallel furrows and
+ridges, such as would be produced by the continued rubbing together of
+surfaces of unequal hardness. These polished surfaces are called by miners
+"slickensides." It is supposed that the lines of the stri� indicate the
+direction in which the rocks were moved. During one of the minor
+earthquakes in Chili, which happened about the year 1840, and was described
+to me by an eye-witness, the brick walls of a building were rent vertically
+in several places, and made to vibrate for several minutes during each
+shock, after which they remained uninjured, and without any opening,
+although the line of each crack was still visible. When all movement had
+ceased, there <span class="pagenum"><a id="page62"></a>[p.62]</span>were seen on the floor of the house, at the bottom
+of each rent, small heaps of fine brickdust, evidently produced by
+trituration.</p>
+
+<a id="img090" name="img090"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 85.</p>
+<img src="images/img090.jpg" width="450" height="169" alt="" title="">
+<p><span class="wosp05">Faults. A</span> B perpendicular, C D oblique to the
+horizon.</p></div>
+
+<p>It is not uncommon to find the mass of rock, on one side of a fissure,
+thrown up above or down below the mass with which it was once in contact on
+the other side. This mode of displacement is called a shift, slip, or
+fault. "The miner," says Playfair, describing a fault, "is often perplexed,
+in his subterraneous journey, by a derangement in the strata, which changes
+at once all those lines and bearings which had hitherto directed his
+course. When his mine reaches a certain plane, which is sometimes
+perpendicular, as in A B, <a href="#img090">fig. 85.</a>, sometimes oblique to the horizon (as in
+C D, ibid.), he finds the beds of rock broken asunder, those on the one
+side of the plane having changed their place, by sliding in a particular
+direction along the face of the others. In this motion they have sometimes
+preserved their parallelism, as in <a href="#img090">fig. 85.</a>, so that the strata on each
+side of the faults A B, C D, continue parallel to one another; in other
+cases, the strata on each side are inclined, as in <i>a</i>, <i>b</i>, <i>c</i>, <i>d</i> (<a href="#img091">fig.
+86.</a>), though their identity is still to be recognized by their possessing
+the same thickness, and the same internal characters."<a name="FNanchor_G_12" id="FNanchor_G_12"></a><a href="#Footnote_G_12" class="fnanchor">[62-A]</a></p>
+
+<a id="img091" name="img091"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 86.</p>
+<img src="images/img091.jpg" width="450" height="135" alt="" title="">
+<p>E F, fault or fissure filled with rubbish, on each
+side of which the shifted strata are not parallel.</p></div>
+
+<p>In Coalbrook Dale, says Mr. Prestwich<a name="FNanchor_G_13" id="FNanchor_G_13"></a><a href="#Footnote_G_13" class="fnanchor">[62-B]</a>, deposits of sandstone, shale,
+and coal, several thousand feet thick, and occupying an area of many miles,
+have been shivered into fragments, and the broken remnants have been placed
+in very discordant positions, often at levels differing several hundred
+feet from each other. The sides of the faults, when perpendicular, are
+commonly separated several yards, but are sometimes as much as 50 yards
+asunder, the interval being filled with broken <i>d�bris</i> of the strata. In
+following the course of <span class="pagenum"><a id="page63"></a>[p.63]</span>the same fault it is sometimes found to
+produce in different places very unequal changes of level, the amount of
+shift being in one place 300, and in another 700 feet, which arises, in
+some cases, from the union of two or more faults. In other words, the
+disjointed strata have in certain districts been subjected to renewed
+movements, which they have not suffered elsewhere.</p>
+
+<p>We may occasionally see exact counterparts of these slips, on a small
+scale, in pits of fine loose sand and gravel, many of which have doubtless
+been caused by the drying and shrinking of argillaceous and other beds,
+slight subsidences having taken place from failure of support. Sometimes,
+however, even these small slips may have been produced during earthquakes;
+for land has been moved, and its level, relatively to the sea, considerably
+altered, within the period when much of the alluvial sand and gravel now
+covering the surface of continents was deposited.</p>
+
+<p>I have already stated that a geologist must be on his guard, in a region of
+disturbed strata, against inferring repeated alternations of rocks, when,
+in fact, the same strata, once continuous, have been bent round so as to
+recur in the same section, and with the same dip. A similar mistake has
+often been occasioned by a series of faults.</p>
+
+<a id="img092" name="img092"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 87.</p>
+<img src="images/img092.jpg" width="500" height="265" alt="" title="">
+<p>Apparent alternations of strata caused by vertical
+faults.</p></div>
+
+<p>If, for example, the dark line A H (<a href="#img092">fig. 87.</a>) represent the surface of a
+country on which the strata <i>a b c</i> frequently crop out, an observer, who
+is proceeding from H to A, might at first imagine that at every step he was
+approaching new strata, whereas the repetition of the same beds has been
+caused by vertical faults, or downthrows. Thus, suppose the original mass,
+A, B, C, D, to have been a set of uniformly inclined strata, and that the
+different masses under E F, F G, and G D, sank down successively, so as to
+leave vacant the spaces marked in the diagram by dotted lines, and to
+occupy those marked by the continuous lines, then let denudation take place
+along the line A H, so that the protruding masses indicated by the fainter
+lines are swept away,&mdash;a miner, who has not discovered the faults, finding
+the mass <i>a</i>, which we will suppose to be a bed of coal four times
+repeated, might hope to find four beds, workable to an indefinite depth,
+but first on arriving at the fault G he is stopped suddenly in his
+workings, <span class="pagenum"><a id="page64"></a>[p.64]</span>upon reaching the strata of sandstone <i>c</i>, or on
+arriving at the line of fault F he comes partly upon the shale <i>b</i>, and
+partly on the sandstone <i>c</i>, and on reaching E he is again stopped by a
+wall composed of the rock <i>d</i>.</p>
+
+<a id="img093" name="img093"></a>
+<div class="figcenter smaller">
+<p>Fig. 88.</p>
+<img src="images/img093.jpg" width="350" height="098" alt="" title=""></div>
+
+<p>The very different levels at which the separated parts of the same strata
+are found on the different sides of the fissure, in some faults, is truly
+astonishing. One of the most celebrated in England is that called the
+"ninety-fathom dike," in the coal-field of Newcastle. This name has been
+given to it, because the same beds are ninety fathoms lower on the northern
+than they are on the southern side. The fissure has been filled by a body
+of sand, which is now in the state of sandstone, and is called the dike,
+which is sometimes very narrow, but in other places more than twenty yards
+wide.<a name="FNanchor_G_14" id="FNanchor_G_14"></a><a href="#Footnote_G_14" class="fnanchor">[64-A]</a> The walls of the fissure are scored by grooves, such as would
+have been produced if the broken ends of the rock had been rubbed along the
+plane of the fault.<a name="FNanchor_G_15" id="FNanchor_G_15"></a><a href="#Footnote_G_15" class="fnanchor">[64-B]</a> In the Tynedale and Craven faults, in the north
+of England, the vertical displacement is still greater, and has extended in
+a horizontal direction for a distance of thirty miles or more. Some
+geologists consider it necessary to imagine that the upward or downward
+movement in these cases was accomplished at a single stroke, and not by a
+series of sudden but interrupted movements. This idea appears to have been
+derived from a notion that the grooved walls have merely been rubbed in one
+direction. But this is so far from being a constant phenomenon in faults,
+that it has often been objected to the received theory respecting those
+polished surfaces called "slickensides" (see above, <a href="#page61">p. 61.</a>), that the stri�
+are not always parallel, but often curved and irregular. It has, moreover,
+been remarked, that not only the walls of the fissure or fault, but its
+earthy contents, sometimes present the same polished and striated faces.
+Now these facts seem to indicate partial changes in the direction of the
+movement, and some slidings subsequent to the first filling up of the
+fissure. Suppose the mass of rock A, B, C, to overlie an extensive chasm <i>d
+e</i>, formed at the depth of several miles, whether by the gradual
+contraction in bulk of a melted mass passing into a solid or crystalline
+state, or the shrinking of argillaceous strata, baked by a moderate heat,
+or by the subtraction of matter by volcanic action, or any other cause.
+Now, if this region be convulsed by earthquakes, the fissures <i>f g</i>, and
+others at right angles to them, may sever the mass B from A and from C, so
+that it may move freely, and begin to sink into the chasm. A fracture may
+be conceived so clean and <span class="pagenum"><a id="page65"></a>[p.65]</span>perfect as to allow it to subside at
+once to the bottom of the subterranean cavity; but it is far more probable
+that the sinking will be effected at successive periods during different
+earthquakes, the mass always continuing to slide in the same direction
+along the planes of the fissures <i>f g</i>, and the edges of the falling mass
+being continually more broken and triturated at each convulsion. If, as is
+not improbable, the circumstances which have caused the failure of support
+continue in operation, it may happen that when the mass B has filled the
+cavity first formed, its foundations will again give way under it, so that
+it will fall again in the same direction. But, if the direction should
+change, the fact could not be discovered by observing the slickensides,
+because the last scoring would efface the lines of previous friction. In
+the present state of our ignorance of the causes of subsidence, an
+hypothesis which can explain the great amount of displacement in some
+faults, on sound mechanical principles, by a succession of movements, is
+far preferable to any theory which assumes each fault to have been
+accomplished by a single upcast or downthrow of several thousand feet. For
+we know that there are operations now in progress, at great depths in the
+interior of the earth, by which both large and small tracts of ground are
+made to rise above and sink below their former level, some slowly and
+insensibly, others suddenly and by starts, a few feet or yards at a time;
+whereas there are no grounds for believing that, during the last 3000 years
+at least, any regions have been either upheaved or depressed, at a single
+stroke, to the amount of several hundred, much less several thousand feet.
+When some of the ancient marine formations are described in the sequel, it
+will appear that their structure and organic contents point to the
+conclusion, that the floor of the ocean was slowly sinking at the time of
+their origin. The downward movement was very gradual, and in Wales and the
+contiguous parts of England a maximum thickness of 32,000 feet (more than
+six miles) of Carboniferous, Devonian, and Silurian rock was formed, whilst
+the bed of the sea was all the time continuously and tranquilly
+subsiding.<a name="FNanchor_G_16" id="FNanchor_G_16"></a><a href="#Footnote_G_16" class="fnanchor">[65-A]</a> Whatever may have been the changes which the solid
+foundation underwent, whether accompanied by the melting, consolidation,
+crystallization, or desiccation of subjacent mineral matter, it is clear
+from the fact of the sea having remained shallow all the while that the
+bottom never sank down suddenly to the depth of many hundred feet at once.</p>
+
+<p>It is by assuming such reiterated variations of level, each separately of
+small vertical amount, but multiplied by time till they acquire importance
+in the aggregate, that we are able to explain the phenomena of denudation,
+which will be treated of in the next chapter. By such movements every
+portion of the surface of the land becomes in its turn a line of coast, and
+is exposed to the action of the waves and tides. A country which is
+undergoing such movement is never <span class="pagenum"><a id="page66"></a>[p.66]</span>allowed to settle into a state
+of equilibrium, therefore the force of rivers and torrents to remove or
+excavate soil and rocky masses is sustained in undiminished energy.</p>
+
+
+
+
+<hr class="sep2">
+<h2><a id="chavi" name="chavi">CHAPTER VI</a>.</h2>
+
+<h4>DENUDATION.</h4>
+
+<div class="blq1">
+<p class="indentm2">Denudation defined &mdash; Its amount equal to the entire mass of stratified
+deposits in the earth's crust &mdash; Horizontal sandstone denuded in
+Ross-shire &mdash; Levelled surface of countries in which great faults
+occur &mdash; Coalbrook Dale &mdash; Denuding power of the ocean during the
+emergence of land &mdash; Origin of Valleys &mdash; Obliteration of
+sea-cliffs &mdash; Inland sea-cliffs and terraces in the Morea and
+Sicily &mdash; Limestone pillars at St. Mihiel, in France &mdash; in Canada &mdash; in the
+Bermudas.</p></div>
+
+
+<p><span class="smcap">Denudation</span>, which has been occasionally spoken of in the preceding
+chapters, is the removal of solid matter by water in motion, whether of
+rivers or of the waves and currents of the sea, and the consequent laying
+bare of some inferior rock. Geologists have perhaps been seldom in the
+habit of reflecting that this operation has exerted an influence on the
+structure of the earth's crust as universal and important as sedimentary
+deposition itself; for denudation is the inseparable accompaniment of the
+production of all new strata of mechanical origin. The formation of every
+new deposit by the transport of sediment and pebbles necessarily implies
+that there has been, somewhere else, a grinding down of rock into rounded
+fragments, sand, or mud, equal in quantity to the new strata. All
+deposition, therefore, except in the case of a shower of volcanic ashes, is
+the sign of superficial waste going on contemporaneously, and to an equal
+amount elsewhere. The gain at one point is no more than sufficient to
+balance the loss at some other. Here a lake has grown shallower, there a
+ravine has been deepened. The bed of the sea has in one region been raised
+by the accumulation of new matter, in another its depth has been augmented
+by the abstraction of an equal quantity.</p>
+
+<p>When we see a stone building, we know that somewhere, far or near, a quarry
+has been opened. The courses of stone in the building may be compared to
+successive strata, the quarry to a ravine or valley which has suffered
+denudation. As the strata, like the courses of hewn stone, have been laid
+one upon another gradually, so the excavation both of the valley and quarry
+have been gradual. To pursue the comparison still farther, the superficial
+heaps of mud, sand, and gravel, usually called alluvium, may be likened to
+the rubbish of a quarry which has been rejected as useless by the workmen,
+or has fallen upon the road between the quarry and the building, so as to
+lie scattered at random over the ground.</p>
+
+<p>If, then, the entire mass of stratified deposits in the earth's crust is at
+once the monument and measure of the denudation which has <span class="pagenum"><a id="page67"></a>[p.67]</span>taken
+place, on how stupendous a scale ought we to find the signs of this removal
+of transported materials in past ages! Accordingly, there are different
+classes of phenomena, which attest in a most striking manner the vast
+spaces left vacant by the erosive power of water. I may allude, first, to
+those valleys on both sides of which the same strata are seen following
+each other in the same order, and having the same mineral composition and
+fossil contents. We may observe, for example, several formations, as Nos.
+1, 2, 3, 4, in the accompanying diagram (<a href="#img094">fig. 89.</a>); No. 1. conglomerate,
+No. 2. clay, No. 3. grit, and No. 4. limestone, each repeated in a series
+of hills separated by valleys varying in depth. When we examine the
+subordinate parts of these four formations, we find, in like manner,
+distinct beds in each, corresponding, on the opposite sides of the valleys,
+both in composition and order of position. No one can doubt that the strata
+were originally continuous, and that some cause has swept away the portions
+which once connected the whole series. A torrent on the side of a mountain
+produces similar interruptions; and when we make artificial cuts in
+lowering roads, we expose, in like manner, corresponding beds on either
+side. But in nature, these appearances occur in mountains several thousand
+feet high, and separated by intervals of many miles or leagues in extent,
+of which a grand exemplification is described by Dr. MacCulloch, on the
+north-western coast of Ross-shire, in Scotland.<a name="FNanchor_H_1" id="FNanchor_H_1"></a><a href="#Footnote_H_1" class="fnanchor">[67-A]</a> The fundamental rock
+of that country is gneiss, in disturbed strata, on which beds of nearly
+horizontal red sandstone rest unconformably. The latter are often very
+thin, forming mere flags, with their surfaces, distinctly ripple-marked.
+They end abruptly on the declivities of many insulated mountains, which
+rise up at once to the height of about 2000 feet above the gneiss of the
+surrounding plain or table land, and to an average elevation of about 3000
+feet above the sea, which all their summits generally attain. The base of
+gneiss varies in height, so that the lower portions of the sandstone occupy
+different levels, and the thickness of the mass is various, sometimes
+exceeding 3000 feet. It is impossible to compare these scattered and
+detached portions without imagining that the whole country has once been
+covered with a great body of sandstone, and that masses from 1000 to more
+than 3000 feet in thickness have been removed.</p>
+
+<a id="img094" name="img094"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 89.</p>
+<img src="images/img094.jpg" width="250" height="133" alt="" title="">
+<p>Valleys of denudation. <i>a.</i> alluvium.</p></div>
+
+<a id="img095" name="img095"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 90.</p>
+<img src="images/img095.jpg" width="450" height="082" alt="" title="">
+<p>Denudation of red sandstone on north-west coast of
+<span class="wosp05">Ross-shire. (MacCulloch.)</span></p></div>
+
+<p>In the "Survey of Great Britain" (vol. i.), Professor Ramsay <span class="pagenum"><a id="page68"></a>[p.68]</span>has
+shown that the missing beds, removed from the summit of the Mendips, must
+have been nearly a mile in thickness; and he has pointed out considerable
+areas in South Wales and some of the adjacent counties of England, where a
+series of pal�ozoic strata, not less than 11,000 feet in thickness, have
+been stripped off. All these materials have of course been transported to
+new regions, and have entered into the composition of more modern
+formations. On the other hand, it is shown by observations in the same
+"Survey," that the pal�ozoic strata are from 20,000 to 30,000 feet thick.
+It is clear that such rocks, formed of mud and sand, now for the most part
+consolidated, are the monuments of denuding operations, which took place on
+a grand scale at a very remote period in the earth's history. For, whatever
+has been given to one area must always have been borrowed from another; a
+truth which, obvious as it may seem when thus stated, must be repeatedly
+impressed on the student's mind, because in many geological speculations it
+is taken for granted that the external crust of the earth has been always
+growing thicker, in consequence of the accumulation, period after period,
+of sedimentary matter, as if the new strata were not always produced at the
+expense of pre-existing rocks, stratified or unstratified. By duly
+reflecting on the fact, that all deposits of mechanical origin imply the
+transportation from some other region, whether contiguous or remote, of an
+equal amount of solid matter, we perceive that the stony exterior of the
+planet must always have grown thinner in one place whenever, by accessions
+of new strata, it was acquiring density in another. No doubt the vacant
+space left by the missing rocks, after extensive denudation, is less
+imposing to the imagination than a vast thickness of conglomerate or
+sandstone, or the bodily presence as it were of a mountain-chain, with all
+its inclined and curved strata. But the denuded tracts speak a clear and
+emphatic language to our reason, and, like repeated layers of fossil
+nummulites, corals or shells, or like numerous seams of coal, each based on
+its under clay full of the roots of trees, still remaining in their natural
+position, demand an indefinite lapse of time for their elaboration.</p>
+
+<p>No one will maintain that the fossils entombed in these rocks did not
+belong to many successive generations of plants and animals. In like
+manner, each sedimentary deposit attests a slow and gradual action, and the
+strata not only serve as a measure of the amount of denudation
+simultaneously effected elsewhere, but are also a correct indication of the
+rate at which the denuding operation was carried on.</p>
+
+<p>Perhaps the most convincing evidence of denudation on a magnificent scale
+is derived from the levelled surfaces of districts where large faults
+occur. I have shown, in <a href="#img092">fig. 87.</a> <a href="#page63">p. 63.</a>, and in <a href="#img096">fig. 91.</a>, how angular and
+protruding masses of rock might naturally have been looked for on the
+surface immediately above great faults, although in fact they rarely exist.
+This phenomenon may be well studied in those districts where coal has been
+extensively worked, for there the former relation of the beds which have
+shifted their position <span class="pagenum"><a id="page69"></a>[p.69]</span>may be determined with great accuracy. Thus
+in the coal field of Ashby de la Zouch, in Leicestershire (see <a href="#img096">fig. 91.</a>), a
+fault occurs, on one side of which the coal beds <i>a b c d</i> rise to the
+height of 500 feet above the corresponding beds on the other side. But the
+uplifted strata do not stand up 500 feet above the general surface; on the
+contrary, the outline of the country, as expressed by the line <i>z z</i>, is
+uniform and unbroken, and the mass indicated by the dotted outline must
+have been washed away.<a name="FNanchor_H_2" id="FNanchor_H_2"></a><a href="#Footnote_H_2" class="fnanchor">[69-A]</a> There are proofs of this kind in some level
+countries, where dense masses of strata have been cleared away from areas
+several hundred square miles in extent.</p>
+
+<a id="img096" name="img096"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 91.</p>
+<img src="images/img096.jpg" width="400" height="172" alt="" title="">
+<p>Faults and denuded coal strata, Ashby de la <span class="wosp05">Zouch.
+(Mammat.)</span></p></div>
+
+<p>In the Newcastle coal district it is ascertained that faults occur in which
+the upward or downward movement could not have been less than 140 fathoms,
+which, had they affected equally the configuration of the surface to that
+amount, would produce mountains with precipitous escarpments nearly 1000
+feet high, or chasms of the like depth; yet is the actual level of the
+country absolutely uniform&mdash;affording no trace whatever of subterranean
+movements.<a name="FNanchor_H_3" id="FNanchor_H_3"></a><a href="#Footnote_H_3" class="fnanchor">[69-B]</a></p>
+
+<p>The ground from which these materials have been removed is usually
+overspread with heaps of sand and gravel, formed out of the ruins of the
+very rocks which have disappeared. Thus, in the districts above referred
+to, they consist of rounded and angular fragments of hard sandstone,
+limestone, and ironstone, with a small quantity of the more destructible
+shale, and even rounded pieces of coal.</p>
+
+<p>Allusion has been already made to the shattered state and discordant
+position of the carboniferous strata in Coalbrook Dale (<a href="#page62">p. 62.</a>). The
+collier cannot proceed three or four yards without meeting with small
+slips, and from time to time he encounters faults of considerable
+magnitude, which have thrown the rocks up or down several hundred feet. Yet
+the superficial inequalities to which these dislocated masses originally
+gave rise are no longer discernible, and the comparative flatness of the
+existing surface can only be explained, as Mr. Prestwich has observed, by
+supposing the fractured portions to have been removed by water. It is also
+clear that strata of red sandstone, more than 1000 feet thick, which once
+covered the coal, in the same region, have been carried away from <span class="pagenum"><a id="page70"></a>[p.70]</span>
+large areas. That water has, in this case, been the denuding agent, we may
+infer from the fact that the rocks have yielded according to their
+different degrees of hardness; the hard trap of the Wrekin, for example,
+and other hills, having resisted more than the softer shale and sandstone,
+so as now to stand out in bold relief.<a name="FNanchor_H_4" id="FNanchor_H_4"></a><a href="#Footnote_H_4" class="fnanchor">[70-A]</a></p>
+
+<p><i>Origin of valleys.</i>&mdash;Many of the earlier geologists, and Dr. Hutton among
+them, taught that "rivers have in general hollowed out their valleys." This
+is true only of rivulets and torrents which are the feeders of the larger
+streams, and which, descending over rapid slopes, are most subject to
+temporary increase and diminution in the volume of their waters. The
+quantity of mud, sand, and pebbles constituting many a modern delta proves
+indisputably that no small part of the inequalities now existing on the
+earth's surface are due to fluviatile action; but the principal valleys in
+almost every great hydrographical basin in the world, are of a shape and
+magnitude which imply that they have been due to other causes besides the
+mere excavating power of rivers.</p>
+
+<p>Some geologists have imagined that a deluge, or succession of deluges, may
+have been the chief denuding agency, and they have speculated on a series
+of enormous waves raised by the instantaneous upthrow of continents or
+mountain chains out of the sea. But even were we disposed to grant such
+sudden upheavals of the floor of the ocean, and to assume that great waves
+would be the consequence of each convulsion, it is not easy to explain the
+observed phenomena by the aid of so gratuitous an hypothesis.</p>
+
+<p>On the other hand, a machinery of a totally different kind seems capable of
+giving rise to effects of the required magnitude. It has now been
+ascertained that the rising and sinking of extensive portions of the
+earth's crust, whether insensibly or by a repetition of sudden shocks, is
+part of the actual course of nature, and we may easily comprehend how the
+land may have been exposed during these movements to abrasion by the waves
+of the sea. In the same manner as a mountain mass may, in the course of
+ages, be formed by sedimentary deposition, layer after layer, so masses
+equally voluminous may in time waste away by inches; as, for example, if
+beds of incoherent materials are raised slowly in an open sea where a
+strong current prevails. It is well known that some of these oceanic
+currents have a breadth of 200 miles, and that they sometimes run for a
+thousand miles or more in one direction, retaining a considerable velocity
+even at the depth of several hundred feet. Under these circumstances, the
+flowing waters may have power to clear away each stratum of incoherent
+materials as it rises and approaches the surface, where the waves exert the
+greatest force; and in this manner a voluminous deposit may be entirely
+swept away, so that, in the absence of faults, no evidence may remain of
+the denuding operation. It may indeed be affirmed that the signs of waste
+will usually be least obvious where the destruction has been <span class="pagenum"><a id="page71"></a>[p.71]</span>most
+complete; for the annihilation may have proceeded so far, that no ruins are
+left of the dilapidated rocks.</p>
+
+<p>Although denudation has had a levelling influence on some countries of
+shattered and disturbed strata (see <a href="#img092">fig. 87.</a> <a href="#page63">p. 63.</a> and <a href="#img096">fig. 91.</a> <a href="#page69">p. 69.</a>),
+it has more commonly been the cause of superficial inequalities, especially
+in regions of horizontal stratification. The general outline of these
+regions is that of flat and level platforms, interrupted by valleys often
+of considerable depth, and ramifying in various directions. These hollows
+may once have formed bays and channels between islands, and the steepest
+slope on the sides of each valley may have been a sea-cliff, which was
+undermined for ages, as the land emerged gradually from the deep. We may
+suppose the position and course of each valley to have been originally
+determined by differences in the hardness of the rocks, and by rents and
+joints which usually occur even in horizontal strata. In mountain chains,
+such as the Jura before described (see <a href="#img076">fig. 71.</a> <a href="#page55">p. 55.</a>), we perceive at
+once that the principal valleys have not been due to aqueous excavation,
+but to those mechanical movements which have bent the rocks into their
+present form. Yet even in the Jura there are many valleys, such as C (<a href="#img076">fig.
+71.</a>), which have been hollowed out by water; and it may be stated that in
+every part of the globe the unevenness of the surface of the land has been
+due to the combined influence of subterranean movements and denudation.</p>
+
+<p>I may now recapitulate a few of the conclusions to which we have arrived:
+first, all the mechanical strata have been accumulated gradually, and the
+concomitant denudation has been no less gradual: secondly, the dry land
+consists in great part of strata formed originally at the bottom of the
+sea, and has been made to emerge and attain its present height by a force
+acting from beneath: thirdly, no combination of causes has yet been
+conceived so capable of producing extensive and gradual denudation, as the
+action of the waves and currents of the ocean upon land slowly rising out
+of the deep.</p>
+
+<p>Now, if we adopt these conclusions, we shall naturally be led to look
+everywhere for marks of the former residence of the sea upon the land,
+especially near the coasts from which the last retreat of the waters took
+place, and it will be found that such signs are not wanting.</p>
+
+<p>I shall have occasion to speak of ancient sea-cliffs, now far inland, in
+the south-east of England, when treating in Chapter XIX. of the denudation
+of the chalk in Surrey, Kent, and Sussex. Lines of upraised sea-beaches of
+more modern date are traced, at various levels from 20 to 100 feet and
+upwards above the present sea-level, for great distances on the east and
+west coasts of Scotland, as well as in Devonshire, and other counties in
+England. These ancient beach-lines often form terraces of sand and gravel,
+including littoral shells, some broken, others entire, and corresponding
+with species now living on the adjoining coast. But it would be
+unreasonable to expect to meet everywhere with the signs of ancient shores,
+since no geologist can have failed to observe how soon all recent marks of
+the <span class="pagenum"><a id="page72"></a>[p.72]</span>kind above alluded to are obscured or entirely effaced,
+wherever, in consequence of the altered state of the tides and currents,
+the sea has receded for a few centuries. We see the cliffs crumble down in
+a few years if composed of sand or clay, and soon reduced to a gentle
+slope. If there were shells on the beach they decompose, and their
+materials are washed away, after which the sand and shingle may resemble
+any other alluviums scattered over the interior.</p>
+
+<a id="img097" name="img097"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 92.</p>
+<img src="images/img097.jpg" width="450" height="097" alt="" title="">
+<p>Section of inland cliff at Abesse, near Dax.</p>
+<ul class="smaller martopm05 leftal">
+<li><i>a.</i> Sand of the Landes.</li>
+<li><i>b.</i> Limestone.</li>
+<li><i>c.</i> Clay.</li>
+</ul></div>
+
+<p>The features of an ancient shore may sometimes be concealed by the growth
+of trees and shrubs, or by a covering of blown sand, a good example of
+which occurs a few miles west from Dax, near Bordeaux, in the south of
+France. About twelve miles inland, a steep bank may be traced running in a
+direction nearly north-east and south-west, or parallel to the contiguous
+coast. This sudden fall of about 50 feet conducts us from the higher
+platform of the Landes to a lower plain which extends to the sea. The
+outline of the ground suggested to me, as it would do to every geologist,
+the opinion that the bank in question was once a sea-cliff, when the whole
+country stood at a lower level. But this is no longer matter of conjecture,
+for, in making excavations in 1830 for the foundation of a building at
+Abesse, a quantity of loose sand, which formed the slope <i>d e</i>, was
+removed; and a perpendicular cliff, about 50 feet in height, which had
+hitherto been protected from the agency of the elements, was exposed. At
+the bottom appeared the limestone <i>b</i>, containing tertiary shells and
+corals, immediately below it the clay <i>c</i>, and above it the usual tertiary
+sand <i>a</i>, of the department of the Landes. At the base of the precipice
+were seen large partially rounded masses of rock, evidently detached from
+the stratum <i>b</i>. The face of the limestone was hollowed out and weathered
+into such forms as are seen in the calcareous cliffs of the adjoining
+coast, especially at Biaritz, near Bayonne. It is evident that, when the
+country was at a somewhat lower level, the sea advanced along the surface
+of the argillaceous stratum <i>c</i>, which, from its yielding nature, favoured
+the waste by allowing the more solid superincumbent stone <i>b</i> to be readily
+undermined. Afterwards, when the country had been elevated, part of the
+sand, <i>a</i>, fell down, or was drifted by the winds, so as to form the talus,
+<i>d e</i>, which masked the inland cliff until it was artificially laid open to
+view.</p>
+
+<p>When we are considering the various causes which, in the course of ages,
+may efface the characters of an ancient sea-coast, earthquakes must not be
+forgotten. During violent shocks, steep and overhanging cliffs are often
+thrown down and become a heap of <span class="pagenum"><a id="page73"></a>[p.73]</span>ruins. Sometimes unequal
+movements of upheaval or depression entirely destroy that horizontality of
+the base-line which constitutes the chief peculiarity of an ancient
+sea-cliff.</p>
+
+<p>It is, however, in countries where hard limestone rocks abound, that inland
+cliffs retain faithfully the characters which they acquired when they
+constituted the boundary of land and sea. Thus, in the Morea, no less than
+three, or even four, ranges of what were once sea-cliffs are well
+preserved. These have been described, by MM. Boblaye and Virlet, as rising
+one above the other at different distances from the actual shore, the
+summit of the highest and oldest occasionally exceeding 1000 feet in
+elevation. At the base of each there is usually a terrace, which is in some
+places a few yards, in others above 300 yards wide, so that we are
+conducted from the high land of the interior to the sea by a succession of
+great steps. These inland cliffs are most perfect, and most exactly
+resemble those now washed by the waves of the Mediterranean, where they are
+formed of calcareous rock, especially if the rock be a hard crystalline
+marble. The following are the points of correspondence observed between the
+ancient coast lines and the borders of the present sea:&mdash;1. A range of
+vertical precipices, with a terrace at their base. 2. A weathered state of
+the surface of the naked rock, such as the spray of the sea produces. 3. A
+line of littoral caverns at the foot of the cliffs. 4. A consolidated beach
+or breccia with occasional marine shells, found at the base of the cliffs,
+or in the caves. 5. Lithodomous perforations.</p>
+
+<p>In regard to the first of these, it would be superfluous to dwell on the
+evidence afforded of the undermining power of waves and currents by
+perpendicular precipices. The littoral caves, also, will be familiar to
+those who have had opportunities of observing the manner in which the waves
+of the sea, when they beat against rocks, have power to scoop out caverns.
+As to the breccia, it is composed of pieces of limestone and rolled
+fragments of thick solid shell, such as <i>Strombus</i> and <i>Spondylus</i>, all
+bound together by a crystalline calcareous cement. Similar aggregations are
+now forming on the modern beaches of Greece, and in caverns on the
+sea-side; and they are only distinguishable in character from those of more
+ancient date, by including many pieces of pottery. In regard to the
+<i>lithodomi</i> above alluded to, these bivalve mollusks are well known to have
+the power of excavating holes in the hardest limestones, the size of the
+cavity keeping pace with the growth of the shell. When living they require
+to be always covered by salt water, but similar pear-shaped hollows,
+containing the dead shells of these creatures, are found at different
+heights on the face of the inland cliffs above mentioned. Thus, for
+example, they have been observed near Modon and Navarino on cliffs in the
+interior 125 feet high above the Mediterranean. As to the weathered surface
+of the calcareous rocks, all limestones are known to suffer chemical
+decomposition when moistened by the spray of the salt water, and are
+corroded still more deeply at points lower down where they are just reached
+by the breakers. By this action the stone acquires a wrinkled and furrowed
+outline, and <span class="pagenum"><a id="page74"></a>[p.74]</span>very near the sea it becomes rough and branching, as
+if covered with corals. Such effects are traced not only on the present
+shore, but at the base of the ancient cliffs far in the interior. Lastly,
+it remains only to speak of the terraces, which extend with a gentle slope
+from the base of almost all the inland cliffs, and are for the most part
+narrow where the rock is hard, but sometimes half a mile or more in breadth
+where it is soft. They are the effects of the encroachment of the ancient
+sea upon the shore at those levels at which the land remained for a long
+time stationary. The justness of this view is apparent on examining the
+shape of the modern shore wherever the sea is advancing upon the land, and
+removing annually small portions of undermined rock. By this agency a
+submarine platform is produced on which we may walk for some distance from
+the beach in shallow water, the increase of depth being very gradual, until
+we reach a point where the bottom plunges down suddenly. This platform is
+widened with more or less rapidity according to the hardness of the rocks,
+and when upraised it constitutes an inland terrace.</p>
+
+<p>But the four principal lines of cliff observed in the Morea do not imply,
+as some have imagined, four great eras of sudden upheaval; they simply
+indicate the intermittence of the upheaving force. Had the rise of the land
+been continuous and uninterrupted, there would have been no one prominent
+line of cliff; for every portion of the surface having been, in its turn,
+and for an equal period of time, a sea-shore, would have presented a nearly
+similar aspect. But if pauses occur in the process of upheaval, the waves
+and currents have time to sap, throw down, and clear away considerable
+masses of rock, and to shape out at certain levels lofty ranges of cliffs
+with broad terraces at their base.</p>
+
+<p>There are some levelled spaces, however, both ancient and modern, in the
+Morea, which are not due to denudation, although resembling in outline the
+terraces above described. They may be called Terraces of Deposition, since
+they have resulted from the gain of land upon the sea where rivers and
+torrents have produced deltas. If the sedimentary matter has filled up a
+bay or gulf surrounded by steep mountains, a flat plain is formed skirting
+the inland precipices; and if these deposits are upraised, they form a
+feature in the landscape very similar to the areas of denudation before
+described.</p>
+
+<p>In the island of Sicily I have examined many inland cliffs like those of
+the Morea; as, for example, near Palermo, where a precipice is seen
+consisting of limestone at the base of which are numerous caves. One of
+these called San Ciro, about 2 miles distant from Palermo, is about 20 feet
+high, 10 wide, and 180 above the sea. Within it is found an ancient beach
+(<i>b</i>, <a href="#img098">fig. 93.</a>), formed of pebbles of various rocks, many of which must
+have come from places far remote. Broken pieces of coral and shell,
+especially of oysters and pectens, are seen intermingled with the pebbles.
+Immediately above the level of this beach, <i>serpul�</i> are still found
+adhering to the face of the rock, and the limestone is perforated by
+<i>lithodomi</i>. Within the grotto, also, at the same level, similar
+perforations occur; and so <span class="pagenum"><a id="page75"></a>[p.75]</span>numerous are the holes, that the rock
+is compared by Hoffmann to a target pierced by musket balls. But in order
+to expose to view these marks of boring-shells in the interior of the cave,
+it was necessary first to remove a mass of breccia, which consisted of
+numerous fragments of rock and an immense quantity of bones of the mammoth,
+hippopotamus, and other quadrupeds, imbedded in a dark brown calcareous
+marl. Many of the bones were rolled as if partially subjected to the action
+of the waves. Below this breccia, which is about 20 feet thick, was found a
+bed of sand filled with sea-shells of recent species; and underneath the
+sand, again, is the secondary limestone of Monte Grifone. The state of the
+surface of the limestone in the cave above the level of the marine sand is
+very different from that below it. <i>Above</i>, the rock is jagged and uneven,
+as is usual in the roofs and sides of limestone caverns; <i>below</i>, the
+surface is smooth and polished, as if by the attrition of the waves.</p>
+
+<a id="img098" name="img098"></a>
+<div class="figcenter width450">
+<p>Fig. 93.</p>
+<img src="images/img098.jpg" width="450" height="164" alt="" title="">
+<ul class="smaller leftal min1em">
+<li><i>a.</i> Monte Grifone.</li>
+<li><i>b.</i> Cave of San Ciro.<a name="FNanchor_H_5" id="FNanchor_H_5"></a><a href="#Footnote_H_5" class="fnanchor">[75-A]</a></li>
+<li><i>c.</i> Plain of Palermo, in which are Newer Pliocene strata of
+limestone and sand.</li>
+<li><i>d.</i> Bay of Palermo.</li>
+</ul></div>
+
+<p>The platform indicated at <i>c</i>, <a href="#img098">fig. 93.</a>, is formed by a tertiary deposit
+containing marine shells almost all of living species, and it affords an
+illustration of the terrace of deposition, or the last of the two kinds
+before mentioned (<a href="#page74">p. 74.</a>).</p>
+
+<p>There are also numerous instances in Sicily of terraces of denudation. One
+of these occurs on the east coast to the north of Syracuse, and the same is
+resumed to the south beyond the town of Noto, where it may be traced
+forming a continuous and lofty precipice, <i>a b</i>, <a href="#img099">fig. 94.</a>, facing towards
+the sea, and constituting the abrupt termination of a calcareous formation,
+which extends in horizontal strata far inland. This precipice varies in
+height from 500 to 700 feet, and between its base and the sea is an
+inferior platform, <i>c b</i>, consisting of similar white limestone. All the
+beds dip towards the sea, but are usually inclined at a very slight angle:
+they are seen to extend uninterruptedly from the base of the escarpment
+into the platform, showing distinctly that the lofty cliff was not produced
+by a fault or vertical shift of the beds, but by the removal of a
+considerable mass of rock. Hence we may conclude that the sea, which is now
+undermining the cliffs of <span class="pagenum"><a id="page76"></a>[p.76]</span>the Sicilian coast, reached at some
+former period the base of the precipice <i>a b</i>, at which time the surface of
+the terrace <i>c b</i> must have been covered by the Mediterranean. There was a
+pause, therefore, in the upward movement, when the waves of the sea had
+time to carve out the platform <i>c b</i>; but there may have been many other
+stationary periods of minor duration. Suppose, for example, that a series
+of escarpments <i>e</i>, <i>f</i>, <i>g</i>, <i>h</i>, once existed, and that the sea, during a
+long interval free from subterranean movements, advances along the line <i>c
+b</i>, all preceding cliffs must have been swept away one after the other, and
+reduced to the single precipice <i>a b</i>.</p>
+
+<a id="img099" name="img099"></a>
+<div class="figcenter smaller">
+<p>Fig. 94.</p>
+<img src="images/img099.jpg" width="450" height="184" alt="" title=""></div>
+
+<a id="img100" name="img100"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 95.</p>
+<img src="images/img100.jpg" width="450" height="283" alt="" title="">
+<p>Valley called Gozzo degli Martiri, below Melilli,
+Val di Noto.</p></div>
+
+<p>That such a series of smaller cliffs, as those represented at <i>e</i>, <i>f</i>,
+<i>g</i>, <i>h</i>, <a href="#img099">fig. 94.</a>, did really once exist at intermediate heights in place
+of the single precipice <i>a b</i>, is rendered highly probable by the fact,
+that in certain bays and inland valleys opening towards the east coast of
+Sicily, and not far from the section given in <a href="#img099">fig. 94.</a>, the solid limestone
+is shaped out into a great succession of ledges, separated from each other
+by small vertical cliffs. These are sometimes so numerous, one above the
+other, that where there is a bend at the head of a valley, they produce an
+effect singularly resembling the seats of a <span class="pagenum"><a id="page77"></a>[p.77]</span>Roman amphitheatre. A
+good example of this configuration occurs near the town of Melilli, as seen
+in the annexed view (<a href="#img100">fig. 95.</a>). In the south of the island, near
+Spaccaforno, Scicli, and Modica, precipitous rocks of white limestone,
+ascending to the height of 500 feet, have been carved out into similar
+forms.</p>
+
+<a id="img101" name="img101"></a>
+<div class="figcenter smaller">
+<p>Fig. 96.</p>
+<img src="images/img101.jpg" width="400" height="130" alt="" title=""></div>
+
+<p>This appearance of a range of marble seats circling round the head of a
+valley, or of great flights of steps descending from the top to the bottom,
+on the opposite sides of a gorge, may be accounted for, as already hinted,
+by supposing the sea to have stood successively at many different levels,
+as at <i>a a</i>, <i>b b</i>, <i>c c</i>, in the accompanying <a href="#img101">fig. 96.</a> But the causes of
+the gradual contraction of the valley from above downwards may still be
+matter of speculation. Such contraction may be due to the greater force
+exerted by the waves when the land at its first emergence was smaller in
+quantity, and more exposed to denudation in an open sea; whereas the wear
+and tear of the rocks might diminish in proportion as this action became
+confined within bays or channels closed in on two or three sides. Or,
+secondly, the separate movements of elevation may have followed each other
+more rapidly as the land continued to rise, so that the times of those
+pauses, during which the greatest denudation was accomplished at certain
+levels, were always growing shorter. It should be remarked, that the cliffs
+and small terraces are rarely found on the opposite sides of the Sicilian
+valleys at heights so precisely answering to each other as those given in
+<a href="#img101">fig. 96.</a>, and this might have been expected, to whichever of the two
+hypotheses above explained we incline; for, according to the direction of
+the prevailing winds and currents, the waves may beat with unequal force on
+different parts of the shore, so that while no impression is made on one
+side of a bay, the sea may encroach so far on the other as to unite several
+smaller cliffs into one.</p>
+
+<p>Before quitting the subject of ancient sea-cliffs, carved out of limestone,
+I shall mention the range of precipitous rocks, composed of a white marble
+of the Oolitic period, which I have seen near the northern gate of St.
+Mihiel in France. They are situated on the right bank of the Meuse, at a
+distance of 200 miles from the nearest sea, and they present on the
+precipice facing the river three or four horizontal grooves, one above the
+other, precisely resembling those which are scooped out by the undermining
+waves. The summits of several of these masses are detached from the
+adjoining hill, in which case the grooves pass all round them, facing
+towards all points <span class="pagenum"><a id="page78"></a>[p.78]</span>of the compass, as if they had once formed
+rocky islets near the shore.<a name="FNanchor_H_6" id="FNanchor_H_6"></a><a href="#Footnote_H_6" class="fnanchor">[78-A]</a></p>
+
+<p>Captain Bayfield, in his survey of the Gulf of St. Lawrence, discovered in
+several places, especially in the Mingan islands, a counterpart of the
+inland cliffs of St. Mihiel, and traced a succession of shingle beaches,
+one above the other, which agreed in their level with some of the principal
+grooves scooped out of the limestone pillars. These beaches consisted of
+calcareous shingle, with shells of recent species, the farthest from the
+shore being 60 feet above the level of the highest tides. In addition to
+the drawings of the pillars called the flower-pots, which he has
+published<a name="FNanchor_H_7" id="FNanchor_H_7"></a><a href="#Footnote_H_7" class="fnanchor">[78-B]</a>, I have been favoured with other views of rocks on the same
+coast, drawn by Lieut. A. Bowen, R. N. (See <a href="#img102">fig. 97.</a>)</p>
+
+<a id="img102" name="img102"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 97.</p>
+<img src="images/img102.jpg" width="400" height="291" alt="" title="">
+<p>Limestone columns in Niapisca Island, in the Gulf
+of St. <span class="wosp05">Lawrence. Height</span> of the second column on the left, 60 feet.</p></div>
+
+<p>In the North-American beaches above mentioned rounded fragments of
+limestone have been found perforated by <i>lithodomi</i>; and holes drilled by
+the same mollusks have been detected in the columnar rocks or
+"flower-pots," showing that there has been no great amount of atmospheric
+decomposition on the surface, or the cavities alluded to would have
+disappeared.</p>
+
+<a id="img103" name="img103"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 98</p>
+<img src="images/img103.jpg" width="400" height="154" alt="" title="">
+<p> The North Rocks, Bermuda, lying outside the great
+coral reef. A. 16 feet high, and B. 12 feet. <i>c.</i> <i>c.</i> Hollows worn by the
+sea.</p></div>
+
+<p>We have an opportunity of seeing in the Bermuda islands the <span class="pagenum"><a id="page79"></a>[p.79]</span>manner
+in which the waves of the Atlantic have worn, and are now wearing out, deep
+smooth hollows on every side of projecting masses of hard limestone. In the
+annexed drawing, communicated to me by Lieut. Nelson, the excavations <i>c</i>,
+<i>c</i>, <i>c</i>, have been scooped out by the waves in a stone of very modern
+date, which, although extremely hard, is full of recent corals and shells,
+some of which retain their colour.</p>
+
+<p>When the forms of these horizontal grooves, of which the surface is
+sometimes smooth and almost polished, and the roofs of which often overhang
+to the extent of 5 feet or more, have been carefully studied by geologists,
+they will serve to testify the former action of the waves at innumerable
+points far in the interior of the continents. But we must learn to
+distinguish the indentations due to the original action of the sea, and
+those caused by subsequent chemical decomposition of calcareous rocks, to
+which they are liable in the atmosphere.</p>
+
+<p>Notwithstanding the enduring nature of the marks left by littoral action on
+calcareous rocks, we can by no means detect sea-beaches and inland cliffs
+everywhere, even in Sicily and the Morea. On the contrary, they are, upon
+the whole, extremely partial, and are often entirely wanting in districts
+composed of argillaceous and sandy formations, which must, nevertheless,
+have been upheaved at the same time, and by the same intermittent
+movements, as the adjoining calcareous rocks.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER VII.</h2>
+
+<h4>ALLUVIUM.</h4>
+
+<div class="blq1">
+<p class="indentm2">Alluvium described &mdash; Due to complicated causes &mdash; Of various ages, as
+shown in Auvergne &mdash; How distinguished from rocks in
+situ &mdash; River-terraces &mdash; Parallel roads of Glen Roy &mdash; Various theories
+respecting their origin.</p></div>
+
+
+<p><span class="smcap">Between</span> the superficial covering of vegetable mould and the subjacent rock
+there usually intervenes in every district a deposit of loose gravel, sand,
+and mud, to which the name of alluvium has been applied. The term is
+derived from <i>alluvio</i>, an inundation, or <i>alluo</i>, to wash, because the
+pebbles and sand commonly resemble those of a river's bed or the mud and
+gravel spread over low lands by a flood.</p>
+
+<p>A partial covering of such alluvium is found alike in all climates, from
+the equatorial to the polar regions; but in the higher latitudes of Europe
+and North America it assumes a distinct character, being very frequently
+devoid of stratification, and containing huge fragments of rock, some
+angular and others rounded, which have been transported to great distances
+from their parent mountains. When <span class="pagenum"><a id="page80"></a>[p.80]</span>it presents itself in this form,
+it has been called "diluvium," "drift," or the "boulder formation;" and its
+probable connexion with the agency of floating ice and glaciers will be
+treated of more particularly in the eleventh and twelfth chapters.</p>
+
+<a id="img104" name="img104"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 99.</p>
+<img src="images/img104.jpg" width="400" height="181" alt="" title="">
+<p>Lavas of Auvergne resting on alluviums of different
+ages.</p></div>
+
+<p>The student will be prepared, by what I have said in the last chapter on
+denudation, to hear that loose gravel and sand are often met with, not only
+on the low grounds bordering rivers, but also at various points on the
+sides or even summits of mountains. For, in the course of those changes in
+physical geography which may take place during the gradual emergence of the
+bottom of the sea and its conversion into dry land, any spot may either
+have been a sunken reef, or a bay, or estuary, or sea-shore, or the bed of
+a river. For this reason it would be unreasonable to hope that we should
+ever be able to account for all the alluvial phenomena of each particular
+country, seeing that the causes of their origin are so complicated.
+Moreover, the last operations of water have a tendency to disturb and
+confound together all pre-existing alluviums. Hence we are always in danger
+of regarding as the work of a single era, and the effect of one cause, what
+has in reality been the result of a variety of distinct agents, during a
+long succession of geological epochs. Much useful instruction may therefore
+be gained from the exploration of a country like Auvergne, where the
+superficial gravel of very different eras happens to have been preserved by
+sheets of lava, which were poured out one after the other at periods when
+the denudation, and probably the upheaval, of rocks were in progress. That
+region had already acquired in some degree its present configuration before
+any volcanos were in activity, and before any igneous matter was
+superimposed upon the granitic and fossiliferous formations. The pebbles
+therefore in the older gravels are exclusively constituted of granite and
+other aboriginal rocks; and afterwards, when volcanic vents burst forth
+into eruption, those earlier alluviums were covered by streams of lava,
+which protected them from intermixture with gravel of subsequent date. In
+the course of ages, a new system of valleys was excavated, so that the
+rivers ran at lower levels than those at which the first alluviums and
+sheets of lava were formed. When, therefore, fresh eruptions gave rise to
+new lava, the melted matter was poured out over lower grounds; and the
+gravel of these plains <span class="pagenum"><a id="page81"></a>[p.81]</span>differed from the first or upland alluvium,
+by containing in it rounded fragments of various volcanic rocks, and often
+bones belonging to distinct groups of land animals which flourished in the
+country in succession.</p>
+
+<p>The annexed drawing will explain the different heights at which beds of
+lava and gravel, each distinct from the other in composition and age, are
+observed, some on the flat tops of hills, 700 or 800 feet high, others on
+the slope of the same hills, and the newest of all in the channel of the
+existing river where there is usually gravel alone, but in some cases a
+narrow stripe of solid lava sharing the bottom of the valley with the
+river. In all these accumulations of transported matter of different ages
+the bones of extinct quadrupeds have been found belonging to assemblages of
+land mammalia which flourished in the country in succession, and which vary
+specifically, the one from the other, in a greater or less degree, in
+proportion as the time which separated their entombment has been more or
+less protracted. The streams in the same district are still undermining
+their banks and grinding down into pebbles or sand, columns of basalt and
+fragments of granite and gneiss; but the older alluviums, with the fossil
+remains belonging to them, are prevented from being mingled with the gravel
+of recent date by the cappings of lava before mentioned. But for the
+accidental interference, therefore, of this peculiar cause, all the
+alluviums might have passed so insensibly the one into the other, that
+those formed at the remotest era might have appeared of the same date as
+the newest, and the whole formation might have been regarded by some
+geologists as the result of one sudden and violent catastrophe.</p>
+
+<p>In almost every country, the alluvium consists in its upper part of
+transported materials, but it often passes downwards into a mass of broken
+and angular fragments derived from the subjacent rock. To this mass the
+provincial name of "rubble," or "brash," is given in many parts of England.
+It may be referred to the weathering or disintegration of stone on the
+spot, the effects of air and water, sun and frost, and chemical
+decomposition.</p>
+
+<a id="img105" name="img105"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 100.</p>
+<img src="images/img105.jpg" width="250" height="211" alt="" title="">
+<ul class="smaller leftal">
+<li><i>a.</i> Vegetable soil.</li>
+<li><i>b.</i> Alluvium.</li>
+<li><i>c.</i> Mass of same, apparently detached.</li>
+</ul></div>
+
+<p>The inferior surface of alluvial deposits is often very irregular,
+conforming to all the inequalities of the fundamental rocks (<a href="#img105">fig. 100.</a>).
+Occasionally, a small mass, as at <i>c</i>, appears detached, and as if included
+in the subjacent formation. Such isolated portions are usually sections of
+winding subterranean hollows filled up with alluvium. They may have been
+the courses of springs or subterranean streamlets, which have flowed
+through and enlarged natural rents; or, when on a small scale and in soft
+strata, they may be spaces which the roots of large trees have once
+occupied, gravel and sand having been introduced after their decay.</p>
+
+<span class="pagenum"><a id="page82"></a>[p.82]</span>
+<a id="img106" name="img106"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 101.</p>
+<img src="images/img106.jpg" width="500" height="252" alt="" title="">
+<p>Sand-pipes in the chalk at Eaton, near
+Norwich.</p></div>
+
+<p>But there are other deep hollows of a cylindrical form found in England,
+France, and elsewhere, penetrating the white chalk, and filled with sand
+and gravel, which are not so readily explained. They are sometimes called
+"sand-pipes," or "sand-galls," and "puits naturels," in France. Those
+represented in the annexed cut were observed by me in 1839, laid open in a
+large chalk-pit near Norwich. They were of very symmetrical form, the
+largest more than 12 feet in diameter, and some of them had been traced, by
+boring, to the depth of more than 60 feet. The smaller ones varied from a
+few inches to a foot in diameter, and seldom descended more than 12 feet
+below the surface. Even where three of them occurred, as at <i>a</i>, <a href="#img106">fig. 101.</a>,
+very close together, the parting walls of soft white chalk were not broken
+through. They all taper downwards and end in a point. As a general rule,
+sand and pebbles occupy the central parts of each pipe, while the sides and
+bottom are lined with clay.</p>
+
+<p>Mr. Trimmer, in speaking of appearances of the same kind in the Kentish
+chalk, attributes the origin of such "sand-galls" to the action of the sea
+on a beach or shoal, where the waves, charged with shingle and sand, not
+only wear out longitudinal furrows, such as may be observed on the surface
+of the chalk near Norwich when the incumbent gravel is removed, but also
+drill deep circular hollows by the rotatory motion imparted to sand and
+pebbles. Such furrows, as well as vertical cavities, are now formed, he
+observes, on the coast where the shores are composed of chalk.<a name="FNanchor_I_1" id="FNanchor_I_1"></a><a href="#Footnote_I_1" class="fnanchor">[82-A]</a></p>
+
+<p>That the commencement of many of the tubular cavities now under
+consideration has been due to the cause here assigned, I have little doubt.
+But such mechanical action could not have hollowed out the whole of the
+sand-pipes <i>c</i> and <i>d</i>, <a href="#img106">fig. 101.</a>, because several large chalk-flints seen
+protruding from the walls of the pipes have not been eroded, while sand and
+gravel have penetrated many feet below them. In other cases, as at <i>b b</i>,
+similar unrounded nodules of flint, still preserving their irregular form
+and white coating, are found at <span class="pagenum"><a id="page83"></a>[p.83]</span>various depths in the midst of the
+loose materials filling the pipe. These have evidently been detached from
+regular layers of flints occurring above. It is also to be remarked that
+the course of the same sand-pipe, <i>b b</i>, is traceable above the level of
+the chalk for some distance upwards, through the incumbent gravel and sand,
+by the obliteration of all signs of stratification. Occasionally, also, as
+in the pipe <i>d</i>, the overlying beds of gravel bend downwards into the mouth
+of the pipe, so as to become in part vertical, as would happen if
+horizontal layers had sunk gradually in consequence of a failure of
+support. All these phenomena may be accounted for by attributing the
+enlargement and deepening of the sand-pipes to the chemical action of water
+charged with carbonic acid, derived from the vegetable soil and the
+decaying roots of trees. Such acid might corrode the chalk, and deepen
+indefinitely any previously existing hollow, but could not dissolve the
+flints. The water, after it had become saturated with carbonate of lime,
+might freely percolate the surrounding porous walls of chalk, and escape
+through them and from the bottom of the tube, so as to carry away in the
+course of time large masses of dissolved calcareous rock<a name="FNanchor_I_2" id="FNanchor_I_2"></a><a href="#Footnote_I_2" class="fnanchor">[83-A]</a>, and leave
+behind it on the edges of each tubular hollow a coating of fine clay, which
+the white chalk contains.</p>
+
+<p>I have seen tubes precisely similar and from 1 to 5 feet in diameter
+traversing vertically the upper half of the soft calcareous building stone,
+or chalk without flints, constituting St. Peter's Mount, Maestricht. These
+hollows are filled with pebbles and clay, derived from overlying beds of
+gravel, and all terminate downwards like those of Norfolk. I was informed
+that, 6 miles from Maestricht, one of these pipes, 2 feet in diameter, was
+traced downwards to a bed of flattened flints, forming an almost continuous
+layer in the chalk. Here it terminated abruptly, but a few small root-like
+prolongations of it were detected immediately below, probably where the
+dissolving substance had penetrated at some points through openings in the
+siliceous mass.</p>
+
+<p>It is not so easy as may at first appear to draw a clear line of
+distinction between the <i>fixed</i> rocks, or regular strata (rocks <i>in situ</i>
+or <i>in place</i>), and <i>alluvium</i>. If the bed of a torrent or river be dried
+up, we call the gravel, sand, and mud left in their channels, or whatever,
+during floods, they may have scattered over the neighbouring plains,
+alluvium. The very same materials carried into a lake, where they become
+sorted by water and arranged in more distinct layers, especially if they
+inclose the remains of plants, shells, or other fossils, are termed regular
+strata.</p>
+
+<p>In like manner we may sometimes compare the gravel, sand, and broken
+shells, strewed along the path of a rapid marine current, with a deposit
+formed contemporaneously by the discharge of similar materials, year after
+year, into a deeper and more tranquil part of the sea. In such cases, when
+we detect marine shells or other organic remains entombed in the strata,
+which enable us to determine their <span class="pagenum"><a id="page84"></a>[p.84]</span>age and mode of origin, we
+regard them as part of the regular series of fossiliferous formations,
+whereas, if there are no fossils, we have frequently no power of separating
+them from the general mass of superficial alluvium.</p>
+
+<p>The usual rarity of organic remains in beds of loose gravel and sand is
+partly owing to the rapid and turbid water in which they were formed having
+been in a condition unfavourable to the habitation of aquatic beings, and
+partly to their porous nature, which, by allowing the free percolation of
+rain-water, has promoted the decomposition and removal of organic matter.</p>
+
+<p>It has long been a matter of common observation that most rivers are now
+cutting their channels through alluvial deposits of greater depth and
+extent than could ever have been formed by the present streams. From this
+fact a rash inference has sometimes been drawn, that rivers in general have
+grown smaller, or become less liable to be flooded than formerly. But such
+phenomena would be a natural result of any considerable oscillations in the
+level of the land experienced since the existing valleys originated.</p>
+
+<p>Suppose part of a continent, comprising within it a large hydrographical
+basin like that of the Mississippi, to subside several inches or feet in a
+century, as the west coast of Greenland, extending 600 miles north and
+south, has been sinking for three or four centuries, between the latitudes
+60� and 69� N.<a name="FNanchor_I_3" id="FNanchor_I_3"></a><a href="#Footnote_I_3" class="fnanchor">[84-A]</a> There might be no encroachment of the sea at the
+river's mouth in consequence of this change of level, but the fall of the
+waters flowing from the interior being lessened, the main river and its
+tributaries would have less power to carry down to its delta, and to
+discharge into the ocean, the sedimentary matter with which they are
+annually loaded. They would all begin to raise their channels and alluvial
+plains by depositing in them the heavier sand and pebbles washed down from
+the upland country, and this operation would take place most effectively if
+the amount of subsidence in the interior was unequal, and especially if, on
+the whole, it exceeded that of the region near the sea. If then the same
+area of land be again upheaved to its former height, the fall, and
+consequently the velocity, of every river would begin to augment. Each of
+them would be less given to overflow its alluvial plain; and their power of
+carrying earthy matter seaward, and of scouring out and deepening their
+channels, would continue till, after a lapse of many thousand years, each
+of them would have eroded a new channel or valley through a fluviatile
+formation of modern date. The surface of what was once the river-plain at
+the period of greatest depression, would remain fringing the valley sides
+in the form of a terrace apparently flat, but in reality sloping down with
+the general inclination of the river. Everywhere this terrace would present
+cliffs of gravel and sand, facing the river. That such a series of
+movements has actually taken place in the main valley of the Mississippi
+and in its tributary valleys during oscillations of level, <span class="pagenum"><a id="page85"></a>[p.85]</span>I have
+endeavoured to show in my description of that country<a name="FNanchor_I_4" id="FNanchor_I_4"></a><a href="#Footnote_I_4" class="fnanchor">[85-A]</a>; and the
+freshwater shells of existing species and bones of land quadrupeds, partly
+of extinct races preserved in the terraces of fluviatile origin, attest the
+exclusion of the sea during the whole process of filling up and partial
+re-excavation.</p>
+
+<p>In many cases, the alluvium in which rivers are now cutting their channels,
+originated when the land first rose out of the sea. If, for example, the
+emergence was caused by a gradual and uniform motion, every bay and
+estuary, or the straits between islands, would dry up slowly, and during
+their conversion into valleys, every part of the upheaved area would in its
+turn be a sea-shore, and might be strewed over with littoral sand and
+pebbles, or each spot might be the point where a delta accumulated during
+the retreat and exclusion of the sea. Materials so accumulated would
+conform to the general slope of a valley from its head to the sea-coast.</p>
+
+<p><i>River terraces.</i>&mdash;We often observe at a short distance from the present
+bed of a river a steep cliff a few feet or yards high, and on a level with
+the top of it a flat terrace corresponding in appearance to the alluvial
+plain which immediately borders the river. This terrace is again bounded by
+another cliff, above which a second terrace sometimes occurs: and in this
+manner two or three ranges of cliffs and terraces are occasionally seen on
+one or both sides of the stream, the number varying, but those on the
+opposite sides often corresponding in height.</p>
+
+<a id="img107" name="img107"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 102.</p>
+<img src="images/img107.jpg" width="450" height="268" alt="" title="">
+<p>River Terraces and Parallel Roads.</p></div>
+
+<p>These terraces are seldom continuous for great distances, and their surface
+slopes downwards, with an inclination similar to that of the river. They
+are readily explained if we adopt the hypothesis before suggested, of a
+gradual rise of the land; especially if, while rivers are shaping out their
+beds, the upheaving movement be intermittent, so that long pauses shall
+occur, during which the stream will have time to encroach upon one of its
+banks, so as to clear away and flatten a large space. This operation being
+afterwards repeated at lower levels, there will be several successive
+cliffs and terraces.</p>
+
+<p><span class="pagenum"><a id="page86"></a>[p.86]</span><i>Parallel roads.</i>&mdash;The parallel shelves, or roads, as they have
+been called, of Lochaber or Glen Roy and other contiguous valleys in
+Scotland, are distinct both in character and origin from the terraces above
+described; for they have no slope towards the sea like the channel of a
+river, nor are they the effect of denudation. Glen Roy is situated in the
+western Highlands, about ten miles north of Fort William, near the western
+end of the great glen of Scotland, or Caledonian Canal, and near the foot
+of the highest of the Grampians, Ben Nevis. Throughout its whole length, a
+distance of more than ten miles, two, and in its lower part three, parallel
+roads or shelves are traced along the steep sides of the mountains, as
+represented in the annexed figure, <a href="#img107">fig. 102.</a>, each maintaining a perfect
+horizontality, and continuing at exactly the same level on the opposite
+sides of the glen. Seen at a distance, they appear like ledges or roads,
+cut artificially out of the sides of the hills; but when we are upon them
+we can scarcely recognize their existence, so uneven is their surface, and
+so covered with boulders. They are from 10 to 60 feet broad, and merely
+differ from the side of the mountain by being somewhat less steep.</p>
+
+<p>On closer inspection, we find that these terraces are stratified in the
+ordinary manner of alluvial or littoral deposits, as may be seen at those
+points where ravines have been excavated by torrents. The parallel shelves,
+therefore, have not been caused by denudation, but by the deposition of
+detritus, precisely similar to that which is dispersed in smaller
+quantities over the declivities of the hills above. These hills consist of
+clay-slate, mica-schist, and granite, which rocks have been worn away and
+laid bare at a few points only, in a line just above the parallel roads.
+The highest of these roads is about 1250 feet above the level of the sea,
+the next about 200 feet lower than the uppermost, and the third still lower
+by about 50 feet. It is only this last, or the lowest of the three, which
+is continued throughout Glen Spean, a large valley with which Glen Roy
+unites. As the shelves are always at the same height above the sea, they
+become continually more elevated above the river in proportion as we
+descend each valley; and they at length terminate very abruptly, without
+any obvious cause, either in the shape of the ground, or any change in the
+composition or hardness of the rocks. I should exceed the limits of this
+work, were I to attempt to give a full description of all the geographical
+circumstances attending these singular terraces, or to discuss the
+ingenious theories which have been severally proposed to account for them
+by Dr. MacCulloch, Sir T. D. Lauder, and Messrs. Darwin, Agassiz, Milne,
+and Chambers. There is one point, however, on which all are agreed, namely,
+that these shelves are ancient beaches, or littoral formations accumulated
+round the edges of one or more sheets of water which once stood at the
+level, first of the highest shelf, and successively at the height of the
+two others. It is well known, that wherever a lake or marine fiord exists
+surrounded by steep mountains subject to disintegration by frost or the
+action of torrents, some loose matter is washed down annually, especially
+<span class="pagenum"><a id="page87"></a>[p.87]</span>during the melting of snow, and a check is given to the descent of
+this detritus at the point where it reaches the waters of the lake. The
+waves then spread out the materials along the shore, and throw some of them
+upon the beach; their dispersing power being aided by the ice, which often
+adheres to pebbles during the winter months, and gives buoyancy to them.
+The annexed diagram illustrates the manner in which Dr. MacCulloch and Mr.
+Darwin suppose "the roads" to constitute mere indentations in a superficial
+alluvial coating which rests upon the hillside, and consists chiefly of
+clay and sharp unrounded stones.</p>
+
+<a id="img108" name="img108"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 103.</p>
+<img src="images/img108.jpg" width="200" height="182" alt="" title="">
+<p>A B. Supposed original surface of rock.
+C D. Roads or shelves in the outer alluvial covering of the hill.</p></div>
+
+<p>Among other proofs that the parallel roads have really been formed along
+the margin of a sheet of water, it may be mentioned, that wherever an
+isolated hill rises in the middle of the glen above the level of any
+particular shelf, a corresponding shelf is seen at the same level passing
+round the hill, as would have happened if it had once formed an island in a
+lake or fiord. Another very remarkable peculiarity in these terraces is
+this; each of them comes in some portion of its course to a <i>col</i>, or
+passage between the heads of glens, the explanation of which will be
+considered in the sequel.</p>
+
+<p>Those writers who first advocated the doctrine that the roads were the
+ancient beaches of freshwater lakes, were unable to offer any probable
+hypothesis respecting the formation and subsequent removal of barriers of
+sufficient height and solidity to dam up the water. To introduce any
+violent convulsion for their removal was inconsistent with the
+uninterrupted horizontality of the roads, and with the undisturbed aspect
+of those parts of the glens where the shelves come suddenly to an end. Mr.
+Agassiz and Dr. Buckland, desirous, like the defenders of the lake theory,
+to account for the limitation of the shelves to certain glens, and their
+absence in contiguous glens, where the rocks are of the same composition,
+and the slope and inclination of the ground very similar, started the
+conjecture that these valleys were once blocked up by enormous glaciers
+descending from Ben Nevis, giving rise to what are called in Switzerland
+and in the Tyrol, glacier-lakes. After a time the icy barrier was broken
+down, or melted, first, to the level of the second, and afterwards to that
+of the third road or shelf.</p>
+
+<p>In corroboration of this view, they contended that the alluvium of Glen
+Roy, as well as of other parts of Scotland, agrees in character with the
+moraines of glaciers seen in the Alpine valleys of Switzerland. Allusion
+will be made in the eleventh chapter to the former existence of glaciers in
+the Grampians: in the mean time it will readily be conceded that this
+hypothesis is preferable to any previous lacustrine theory, by accounting
+more easily for the temporary existence and entire disappearance of lofty
+transverse barriers, although <span class="pagenum"><a id="page88"></a>[p.88]</span>the height required for the
+imaginary dams of ice may be startling.</p>
+
+<p>Before the idea last alluded to had been entertained, Mr. Darwin examined
+Glen Roy, and came to the opinion that the shelves were formed when the
+glens were still arms of the sea, and, consequently, that there never were
+any barriers. According to him, the land emerged during a slow and uniform
+upward movement, like that now experienced throughout a large part of
+Sweden and Finland; but there were certain pauses in the upheaving process,
+at which times the waters of the sea remained stationary for so many
+centuries as to allow of the accumulation of an extraordinary quantity of
+detrital matter, and the excavation, at points immediately above, of many
+deep notches and bare cliffs in the hard and solid rock.</p>
+
+<p>The phenomena which are most difficult to reconcile with this theory are,
+first, the abrupt cessation of the roads at certain points in the different
+glens; secondly, their unequal number in different valleys connecting with
+each other, there being three, for example, in Glen Roy and only one in
+Glen Spean; thirdly, the precise horizontality of level maintained by the
+same shelf over a space many leagues in length requiring us to assume, that
+during a rise of 1250 feet no one portion of the land was raised even a few
+yards above another; fourthly, the coincidence of level already alluded to
+of each shelf with a <i>col</i>, or the point forming the head of two glens,
+from which the rain-waters flow in opposite directions. This last-mentioned
+feature in the physical geography of Lochaber seems to have been explained
+in a satisfactory manner by Mr. Darwin. He calls these <i>cols</i>
+"landstraits," and regards them as having been anciently sounds or channels
+between islands. He points out that there is a tendency in such sounds to
+be silted up, and always the more so in proportion to their narrowness. In
+a chart of the Falkland Islands by Capt. Sullivan, R. N., it appears that
+there are several examples there of straits where the soundings diminish
+regularly towards the narrowest part. One is so nearly dry that it can be
+walked over at low water, and another, no longer covered by the sea, is
+supposed to have recently dried up in consequence of a small shift in the
+relative level of sea and land. "Similar straits," observes Mr. Chambers,
+"hovering, in character, between sea and land, and which may be called
+fords, are met with in the Hebrides. Such, for example, is the passage
+dividing the islands of Lewis and Harris, and that between North Uist and
+Benbecula, both of which would undoubtedly appear as <i>cols</i>, coinciding
+with a terrace or raised beach, all round the islands, if the sea were to
+subside."<a name="FNanchor_I_5" id="FNanchor_I_5"></a><a href="#Footnote_I_5" class="fnanchor">[88-A]</a></p>
+
+<p>The precise horizontality of level maintained by the roads or shelves of
+Lochaber over an area many leagues in length and breadth, is a difficulty
+common in some degree to all the rival hypotheses, whether of lakes, or
+glaciers, or of the simple upheaval of the land above the sea. For we
+cannot suppose the roads to be more ancient than the glacial period, or the
+era of the boulder formation of <span class="pagenum"><a id="page89"></a>[p.89]</span>Scotland, of which I shall speak
+in the eleventh and twelfth chapters. Strata of that era of marine origin
+containing northern shells of existing species have been found at various
+heights in Scotland, some on the east, and others on the west coast, from
+20 to 400 feet high; and in one region in Lanarkshire not less than 524
+feet above high-water mark. It seems, therefore, in the highest degree
+improbable that Glen Roy should have escaped entirely the upward movement
+experienced in so many surrounding regions,&mdash;a movement implied by the
+position of these marine deposits, in which the shells are almost all of
+known recent species. But if the motion has really extended to Glen Roy and
+the contiguous glens, it must have uplifted them bodily, without in the
+slightest degree affecting their horizontality; and this being admitted,
+the principal objection to the theory of marine beaches, founded on the
+uniformity of upheaval, is removed, or is at least common to every theory
+hitherto proposed.</p>
+
+<p>To assume that the ocean has gone down from the level of the uppermost
+shelf, or 1250 feet, simultaneously all over the globe, while the land
+remained unmoved, is a view which will find favour with very few
+geologists, for the reasons explained in the fifth chapter.</p>
+
+<p>The student will perceive, from the above sketch of the controversy
+respecting the formation of these curious shelves, that this problem, like
+many others in geology, is as yet only solved in part; and that a larger
+number of facts must be collected and reasoned upon before the question can
+be finally settled.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER VIII.</h2>
+
+<h4>CHRONOLOGICAL CLASSIFICATION OF ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Aqueous, plutonic, volcanic, and metamorphic rocks, considered
+chronologically &mdash; Lehman's division into primitive and
+secondary &mdash; Werner's addition of a transition class &mdash; Neptunian
+theory &mdash; Hutton on igneous origin of granite &mdash; How the name of primary
+was still retained for granite &mdash; The term "transition," why faulty &mdash; The
+adherence to the old chronological nomenclature retarded the progress
+of geology &mdash; New hypothesis invented to reconcile the igneous origin of
+granite to the notion of its high antiquity &mdash; Explanation of the
+chronological nomenclature adopted in this work, so far as regards
+primary, secondary, and tertiary periods.</p></div>
+
+
+<p><span class="smcap">In</span> the first chapter it was stated that the four great classes of rocks,
+the aqueous, the volcanic, the plutonic, and the metamorphic, would each be
+considered not only in reference to their mineral characters, and mode of
+origin, but also to their relative age. The preservation of the shelves may
+have required, says Darwin, the quick growth of green turf on a good soil;
+their abrupt cessation may mark the place where the soil was barren, and
+when a green sward formed slowly. In regard to the aqueous rocks, we have
+already seen that they are stratified, that some are calcareous, others
+argillaceous or siliceous, some made up of sand, others of pebbles; that
+some contain freshwater, <span class="pagenum"><a id="page90"></a>[p.90]</span>others marine fossils, and so forth; but
+the student has still to learn which rocks, exhibiting some or all of these
+characters, have originated at one period of the earth's history, and which
+at another.</p>
+
+<p>To determine this point in reference to the fossiliferous formations is
+more easy than in any other class, and it is therefore the most convenient
+and natural method to begin by establishing a chronology for these
+fossiliferous strata, and then to endeavour to refer to the same divisions,
+the several groups of plutonic, volcanic, and metamorphic rocks. This
+system of classification is not only recommended by its greater clearness
+and facility of application, but is also best fitted to strike the
+imagination by bringing into one view the past changes of the inorganic
+world, and the contemporaneous revolutions of the organic creation. For the
+sedimentary formations of successive periods are most readily distinguished
+by the different species of fossil animals and plants which they inclose,
+and of which one race after another has flourished and then disappeared
+from the earth.</p>
+
+<p>But before entering specially on the subdivisions of the aqueous rocks
+arranged according to the order of time, it will be desirable to say a few
+words on the chronology of rocks in general, although in doing so we shall
+be unavoidably led to allude to some classes of phenomena which the
+beginner must not yet expect fully to comprehend.</p>
+
+<p>It was for many years a received opinion, that the formation of entire
+families of rocks, such as the plutonic and those crystalline schists
+spoken of in the first chapter as metamorphic, began and ended before any
+members of the aqueous and volcanic orders were produced; and although this
+idea has long been modified, and is nearly exploded, it will be necessary
+to give some account of the ancient doctrine, in order that beginners may
+understand whence many prevailing opinions, and some part of the
+nomenclature of geology, still partially in use, was derived.</p>
+
+<p>About the middle of the last century, Lehman, a German miner, proposed to
+divide rocks into three classes, the first and oldest to be called
+primitive, comprising the hypogene, or plutonic and metamorphic rocks; the
+next to be termed secondary, comprehending the aqueous or fossiliferous
+strata; and the remainder, or third class, corresponding to our alluvium,
+ancient and modern, which he referred to "local floods, and the deluge of
+Noah." In the primitive class, he said, such as granite and gneiss, there
+are no organic remains, nor any signs of materials derived from the ruins
+of pre-existing rocks. Their origin, therefore, may have been purely
+chemical, antecedent to the creation of living beings, and probably coeval
+with the birth of the world itself. The secondary formations, on the
+contrary, which often contain sand, pebbles, and organic remains, must have
+been mechanical deposits, produced after the planet had become the
+habitation of animals and plants. This bold generalization, although
+anticipated in some measure by Steno, a century before, in Italy, formed at
+the time an important step in the progress of geology, and sketched out
+correctly some of the leading divisions into which rocks may be separated.
+About half a century later, Werner, so justly <span class="pagenum"><a id="page91"></a>[p.91]</span>celebrated for his
+improved methods of discriminating the mineralogical characters of rocks,
+attempted to improve Lehman's classification, and with this view
+intercalated a class, called by him "the transition formations," between
+the primitive and secondary. Between these last he had discovered, in
+northern Germany, a series of strata, which in their mineral peculiarities
+were of an intermediate character, partaking in some degree of the
+crystalline nature of micaceous schist and clay-slate, and yet exhibiting
+here and there signs of a mechanical origin and organic remains. For this
+group, therefore, forming a passage between Lehman's primitive and
+secondary rocks, the name of <i>�bergang</i> or transition was proposed. They
+consisted principally of clay-slate and an argillaceous sandstone, called
+grauwacke, and partly of calcareous beds. It happened in the district which
+Werner first investigated, that both the primitive and transition strata
+were highly inclined, while the beds of the newer fossiliferous rocks, the
+secondary of Lehman, were horizontal. To these latter, therefore, he gave
+the name <i>fl�tz</i>, or "a level floor;" and every deposit more modern than
+the chalk, which was classed as the uppermost of the fl�tz series, was
+designated "the overflowed land," an expression which may be regarded as
+equivalent to alluvium, although under this appellation were confounded all
+the strata afterwards called tertiary, of which Werner had scarcely any
+knowledge. As the followers of Werner soon discovered that the inclined
+position of the "transition beds," and the horizontality of the fl�tz, or
+newer fossiliferous strata, were mere local accidents, they soon abandoned
+the term fl�tz; and the four divisions of the Wernerian school were then
+named primitive, transition, secondary, and alluvial.</p>
+
+<p>As to the trappean rocks, although their igneous origin had been already
+demonstrated by Arduino, Fortis, Faujas, and others, and especially by
+Desmarest, they were all regarded by Werner as aqueous, and as mere
+subordinate members of the secondary series.<a name="FNanchor_J_1" id="FNanchor_J_1"></a><a href="#Footnote_J_1" class="fnanchor">[91-A]</a></p>
+
+<p>This theory of Werner's was called the "Neptunian," and for many years
+enjoyed much popularity. It assumed that the globe had been at first
+invested by an universal chaotic ocean, holding the materials of all rocks
+in solution. From the waters of this ocean, granite, gneiss, and other
+crystalline formations, were first precipitated; and afterwards, when the
+waters were purged of these ingredients, and more nearly resembled those of
+our actual seas, the transition strata were deposited. These were of a
+mixed character, not purely chemical, because the waves and currents had
+already begun to wear down solid land, and to give rise to pebbles, sand,
+and mud; nor entirely without fossils, because a few of the first marine
+animals had begun to exist. After this period, the secondary formations
+were accumulated in waters resembling those of the present ocean, except at
+certain intervals, when, from causes wholly unexplained, a partial
+recurrence of the "chaotic fluid" took place, during which various trap
+rocks, some highly crystalline, were formed. This arbitrary hypothesis
+rejected all intervention of igneous agency, volcanos being <span class="pagenum"><a id="page92"></a>[p.92]</span>
+regarded as modern, partial, and superficial accidents, of trifling account
+among the great causes which have modified the external structure of the
+globe.</p>
+
+<p>Meanwhile Hutton, a contemporary of Werner, began to teach, in Scotland,
+that granite as well as trap was of igneous origin, and had at various
+periods intruded itself in a fluid state into different parts of the
+earth's crust. He recognized and faithfully described many of the phenomena
+of granitic veins, and the alterations produced by them on the invaded
+strata, which will be treated of in the thirty-second chapter. He,
+moreover, advanced the opinion, that the crystalline strata called
+primitive had not been precipitated from a prim�val ocean, but were
+sedimentary strata altered by heat. In his writings, therefore, and in
+those of his illustrator, Playfair, we find the germ of that metamorphic
+theory which has been already hinted at in the first chapter, and which
+will be more fully expounded in the thirty-fourth and thirty-fifth
+chapters.</p>
+
+<p>At length, after much controversy, the doctrine of the igneous origin of
+trap and granite made its way into general favour; but although it was, in
+consequence, admitted that both granite and trap had been produced at many
+successive periods, the term primitive or primary still continued to be
+applied to the crystalline formations in general, whether stratified, like
+gneiss, or unstratified, like granite. The pupil was told that granite was
+a primary rock, but that some granites were newer than certain secondary
+formations; and in conformity with the spirit of the ancient language, to
+which the teacher was still determined to adhere, a desire was naturally
+engendered of extenuating the importance of those more modern granites, the
+true dates of which new observations were continually bringing to light.</p>
+
+<p>A no less decided inclination was shown to persist in the use of the term
+"transition," after it had been proved to be almost as faulty in its
+original application as that of fl�tz. The name of transition, as already
+stated, was first given by Werner, to designate a mineral character,
+intermediate between the highly crystalline or metamorphic state and that
+of an ordinary fossiliferous rock. But the term acquired also from the
+first a chronological import, because it had been appropriated to
+sedimentary formations, which, in the Hartz and other parts of Germany,
+were more ancient than the oldest of the secondary series, and were
+characterized by peculiar fossil zoophytes and shells. When, therefore,
+geologists found in other districts stratified rocks occupying the same
+position, and inclosing similar fossils, they gave to them also the name of
+<i>transition</i>, according to rules which will be explained in the next
+chapter; yet, in many cases, such rocks were found not to exhibit the same
+mineral texture which Werner had called transition. On the contrary, many
+of them were not more crystalline than different members of the secondary
+class; while, on the other hand, these last were sometimes found to assume
+a semi-crystalline and almost metamorphic aspect, and thus, on lithological
+grounds, to deserve equally the name of transition. So remarkably was this
+the case in <span class="pagenum"><a id="page93"></a>[p.93]</span>the Swiss Alps, that certain rocks, which had for
+years been regarded by some of the most skilful disciples of Werner to be
+transition, were at last acknowledged, when their relative position and
+fossils were better understood, to belong to the newest of the secondary
+groups; nay, some of them have actually been discovered to be members of
+the lower tertiary series! If, under such circumstances, the name of
+transition was retained, it is clear that it ought to have been applied
+without reference to the age of strata, and simply as expressive of a
+mineral peculiarity. The continued appropriation of the term to formations
+of a given date, induced geologists to go on believing that the ancient
+strata so designated bore a less resemblance to the secondary than is
+really the case, and to imagine that these last never pass, as they
+frequently do, into metamorphic rocks.</p>
+
+<p>The poet Waller, when lamenting over the antiquated style of Chaucer,
+complains that&mdash;</p>
+
+<div class="left20">
+<p class="poem">
+We write in sand, our language grows,<br>
+And, like the tide, our work o'erflows.</p>
+</div>
+
+<p>But the reverse is true in geology; for here it is our work which
+continually outgrows the language. The tide of observation advances with
+such speed that improvements in theory outrun the changes of nomenclature;
+and the attempt to inculcate new truths by words invented to express a
+different or opposite opinion, tends constantly, by the force of
+association, to perpetuate error; so that dogmas renounced by the reason
+still retain a strong hold upon the imagination.</p>
+
+<p>In order to reconcile the old chronological views with the new doctrine of
+the igneous origin of granite, the following hypothesis was substituted for
+that of the Neptunists. Instead of beginning with an aqueous menstruum or
+chaotic fluid, the materials of the present crust of the earth were
+supposed to have been at first in a state of igneous fusion, until part of
+the heat having been diffused into surrounding space, the surface of the
+fluid consolidated, and formed a crust of granite. This covering of
+crystalline stone, which afterwards grew thicker and thicker as it cooled,
+was so hot, at first, that no water could exist upon it; but as the
+refrigeration proceeded, the aqueous vapour in the atmosphere was
+condensed, and, falling in rain, gave rise to the first <i>thermal ocean</i>. So
+high was the temperature of this boiling sea, that no aquatic beings could
+inhabit its waters, and its deposits were not only devoid of fossils, but,
+like those of some hot springs, were highly crystalline. Hence the origin
+of the primary or crystalline strata,&mdash;gneiss, mica-schist, and the rest.</p>
+
+<p>Afterwards, when the granitic crust had been partially broken up, land and
+mountains began to rise above the waters, and rains and torrents ground
+down rock, so that sediment was spread over the bottom of the seas. Yet the
+heat still remaining in the solid supporting substances was sufficient to
+increase the chemical action <span class="pagenum"><a id="page94"></a>[p.94]</span>exerted by the water, although not so
+intense as to prevent the introduction and increase of some living beings.
+During this state of things some of the residuary mineral ingredients of
+the prim�val ocean were precipitated, and formed deposits (the transition
+strata of Werner), half chemical and half mechanical, and containing a few
+fossils.</p>
+
+<p>By this new theory, which was in part a revival of the doctrine of
+Leibnitz, published in 1680, on the igneous origin of the planet, the old
+ideas respecting the priority of all crystalline rocks to the creation of
+organic beings, were still preserved; and the mistaken notion that all the
+semi-crystalline and partially fossiliferous rocks belonged to one period,
+while all the earthy and uncrystalline formations originated at a
+subsequent epoch, was also perpetuated.</p>
+
+<p>It may or may not be true, as the great Leibnitz imagined, that the whole
+planet was once in a state of liquefaction by heat; but there are certainly
+no geological proofs that the granite which constitutes the foundation of
+so much of the earth's crust was ever at once in a state of universal
+fusion. On the contrary, all our evidence tends to show that the formation
+of granite, like the deposition of the stratified rocks, has been
+successive, and that different portions of granite have been in a melted
+state at distinct and often distant periods. One mass was solid, and had
+been fractured, before another body of granitic matter was injected into
+it, or through it, in the form of veins. Some granites are more ancient
+than any known fossiliferous rocks; others are of secondary; and some, such
+as that of Mont Blanc and part of the central axis of the Alps, of tertiary
+origin. In short, the universal fluidity of the crystalline foundations of
+the earth's crust, can only be understood in the same sense as the
+universality of the ancient ocean. All the land has been under water, but
+not all at one time; so all the subterranean unstratified rocks to which
+man can obtain access have been melted, but not simultaneously.</p>
+
+<p>In the present work the four great classes of rocks, the aqueous, plutonic,
+volcanic, and metamorphic, will form four parallel, or nearly parallel,
+columns in one chronological table. They will be considered as four sets of
+monuments relating to four contemporaneous, or nearly contemporaneous,
+series of events. I shall endeavour, in a subsequent chapter on the
+plutonic rocks, to explain the manner in which certain masses belonging to
+each of the four classes of rocks may have originated simultaneously at
+every geological period, and how the earth's crust may have been
+continually remodelled, above and below, by aqueous and igneous causes,
+from times indefinitely remote. In the same manner as aqueous and
+fossiliferous strata are now formed in certain seas or lakes, while in
+other places volcanic rocks break out at the surface, and are connected
+with reservoirs of melted matter at vast depths in the bowels of the
+earth,&mdash;so, at every era of the past, fossiliferous deposits and
+superficial igneous rocks were in progress contemporaneously with others of
+subterranean and plutonic origin, and some sedimentary <span class="pagenum"><a id="page95"></a>[p.95]</span>strata were
+exposed to heat and made to assume a crystalline or metamorphic structure.</p>
+
+<p>It can by no means be taken for granted, that during all these changes the
+solid crust of the earth has been increasing in thickness. It has been
+shown, that so far as aqueous action is concerned, the gain by fresh
+deposits, and the loss by denudation, must at each period have been equal
+(see above, <a href="#page68">p. 68.</a>); and in like manner, in the inferior portion of the
+earth's crust, the acquisition of new crystalline rocks, at each successive
+era, may merely have counter-balanced the loss sustained by the melting of
+materials previously consolidated. As to the relative antiquity of the
+crystalline foundations of the earth's crust, when compared to the
+fossiliferous and volcanic rocks which they support, I have already stated,
+in the first chapter, that to pronounce an opinion on this matter is as
+difficult as at once to decide which of the two, whether the foundations or
+superstructure of an ancient city built on wooden piles, may be the oldest.
+We have seen that, to answer this question, we must first be prepared to
+say whether the work of decay and restoration had gone on most rapidly
+above or below, whether the average duration of the piles has exceeded that
+of the stone buildings, or the contrary. So also in regard to the relative
+age of the superior and inferior portions of the earth's crust; we cannot
+hazard even a conjecture on this point, until we know whether, upon an
+average, the power of water above, or that of heat below, is most
+efficacious in giving new forms to solid matter.</p>
+
+<p>After the observations which have now been made, the reader will perceive
+that the term primary must either be entirely renounced, or, if retained,
+must be differently defined, and not made to designate a set of crystalline
+rocks, some of which are already ascertained to be newer than all the
+secondary formations. In this work I shall follow most nearly the method
+proposed by Mr. Bou�, who has called all <i>fossiliferous</i> rocks older than
+the secondary by the name of primary. To prevent confusion, however, I
+shall always speak of these, when they are of the aqueous class, as the
+<i>primary fossiliferous</i> formations, because the word primary has hitherto
+been almost inseparably connected with the idea of a non-fossiliferous
+rock.</p>
+
+<p>If we can prove any plutonic, volcanic, or metamorphic rocks to be older
+than the secondary formations, such rocks will also be primary, according
+to this system. Mr. Bou� having with great propriety excluded the
+metamorphic rocks, <i>as a class</i>, from the primary formations, proposed to
+call them all "crystalline schists."</p>
+
+<p>As there are secondary fossiliferous strata, so we shall find that there
+are plutonic, volcanic, and metamorphic rocks of contemporaneous origin,
+which I shall also term secondary.</p>
+
+<p>In the next chapter it will be shown that the strata above the chalk have
+been called tertiary. If, therefore, we discover any volcanic, plutonic, or
+metamorphic rocks, which have originated since the deposition of the chalk,
+these also will rank as tertiary formations.</p>
+
+<p><span class="pagenum"><a id="page96"></a>[p.96]</span>It may perhaps be suggested that some metamorphic strata, and some
+granites, may be anterior in date to the oldest of the primary
+fossiliferous rocks. This opinion is doubtless true, and will be discussed
+in future chapters; but I may here observe, that when we arrange the four
+classes of rocks in four parallel columns in one table of chronology, it is
+by no means assumed that these columns are all of equal length; one may
+begin at an earlier period than the rest, and another may come down to a
+later point of time. In the small part of the globe hitherto examined, it
+is hardly to be expected that we should have discovered either the oldest
+or the newest members of each of the four classes of rocks. Thus, if there
+be primary, secondary, and tertiary rocks of the aqueous or fossiliferous
+class, and in like manner primary, secondary, and tertiary hypogene
+formations, we may not be yet acquainted with the most ancient of the
+primary fossiliferous beds, or with the newest of the hypogene.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER IX.</h2>
+
+<h4>ON THE DIFFERENT AGES OF THE AQUEOUS ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">On the three principal tests of relative age &mdash; superposition, mineral
+character, and fossils &mdash; Change of mineral character and fossils in the
+same continuous formation &mdash; Proofs that distinct species of animals and
+plants have lived at successive periods &mdash; Distinct provinces of
+indigenous species &mdash; Great extent of single provinces &mdash; Similar laws
+prevailed at successive geological periods &mdash; Relative importance of
+mineral and pal�ontological characters &mdash; Test of age by included
+fragments &mdash; Frequent absence of strata of intervening
+periods &mdash; Principal groups of strata in western Europe.</p></div>
+
+
+<p><span class="smcap">In</span> the last chapter I spoke generally of the chronological relations of the
+four great classes of rocks, and I shall now treat of the aqueous rocks in
+particular, or of the successive periods at which the different
+fossiliferous formations have been deposited.</p>
+
+<p>There are three principal tests by which we determine the age of a given
+set of strata; first, superposition; secondly, mineral character; and,
+thirdly, organic remains. Some aid can occasionally be derived from a
+fourth kind of proof, namely, the fact of one deposit including in it
+fragments of a pre-existing rock, by which the relative ages of the two
+may, even in the absence of all other evidence, be determined.</p>
+
+<p><i>Superposition.</i>&mdash;The first and principal test of the age of one aqueous
+deposit, as compared to another, is relative position. It has been already
+stated, that where strata are horizontal, the bed which lies uppermost is
+the newest of the whole, and that which lies at the bottom the most
+ancient. So, of a series of sedimentary formations, they are like volumes
+of history, in which each writer has recorded <span class="pagenum"><a id="page97"></a>[p.97]</span>the annals of his
+own times, and then laid down the book, with the last written page
+uppermost, upon the volume in which the events of the era immediately
+preceding were commemorated. In this manner a lofty pile of chronicles is
+at length accumulated; and they are so arranged as to indicate, by their
+position alone, the order in which the events recorded in them have
+occurred.</p>
+
+<p>In regard to the crust of the earth, however, there are some regions where,
+as the student has already been informed, the beds have been disturbed, and
+sometimes extensively thrown over and turned upside down. (See pp. <a href="#page58">58</a>, <a href="#page59">59.</a>)
+But an experienced geologist can rarely be deceived by these exceptional
+cases. When he finds that the strata are fractured, curved, inclined, or
+vertical, he knows that the original order of superposition must be
+doubtful, and he then endeavours to find sections in some neighbouring
+district where the strata are horizontal, or only slightly inclined. Here
+the true order of sequence of the entire series of deposits being
+ascertained, a key is furnished for settling the chronology of those strata
+where the displacement is extreme.</p>
+
+<p><i>Mineral character.</i>&mdash;The same rocks may often be observed to retain for
+miles, or even hundreds of miles, the same mineral peculiarities, if we
+follow the planes of stratification, or trace the beds, if they be
+undisturbed, in a horizontal direction. But if we pursue them vertically,
+or in any direction transverse to the planes of stratification, this
+uniformity ceases almost immediately. In that case we can scarcely ever
+penetrate a stratified mass for a few hundred yards without beholding a
+succession of extremely dissimilar, calcareous, argillaceous, and siliceous
+rocks. These phenomena lead to the conclusion, that rivers and currents
+have dispersed the same sediment over wide areas at one period, but at
+successive periods have been charged, in the same region, with very
+different kinds of matter. The first observers were so astonished at the
+vast spaces over which they were able to follow the same homogeneous rocks
+in a horizontal direction, that they came hastily to the opinion, that the
+whole globe had been environed by a succession of distinct aqueous
+formations, disposed round the nucleus of the planet, like the concentric
+coats of an onion. But although, in fact, some formations may be continuous
+over districts as large as half of Europe, or even more, yet most of them
+either terminate wholly within narrower limits, or soon change their
+lithological character. Sometimes they thin out gradually, as if the supply
+of sediment had failed in that direction, or they come abruptly to an end,
+as if we had arrived at the borders of the ancient sea or lake which served
+as their receptacle. It no less frequently happens that they vary in
+mineral aspect and composition, as we pursue them horizontally. For
+example, we trace a limestone for a hundred miles, until it becomes more
+arenaceous, and finally passes into sand, or sandstone. We may then follow
+this sandstone, already proved by its continuity to be of the same age,
+throughout another district a hundred miles or more in length.</p>
+
+<p><i>Organic remains.</i>&mdash;This character must be used as a criterion of <span class="pagenum"><a id="page98"></a>[p.98]</span>
+the age of a formation, or of the contemporaneous origin of two deposits in
+distant places, under very much the same restrictions as the test of
+mineral composition.</p>
+
+<p>First, the same fossils may be traced over wide regions, if we examine
+strata in the direction of their planes, although by no means for
+indefinite distances.</p>
+
+<p>Secondly, while the same fossils prevail in a particular set of strata for
+hundreds of miles in a horizontal direction, we seldom meet with the same
+remains for many fathoms, and very rarely for several hundred yards, in a
+vertical line, or a line transverse to the strata. This fact has now been
+verified in almost all parts of the globe, and has led to a conviction,
+that at successive periods of the past, the same area of land and water has
+been inhabited by species of animals and plants even more distinct than
+those which now people the antipodes, or which now co-exist in the arctic,
+temperate, and tropical zones. It appears, that from the remotest periods
+there has been ever a coming in of new organic forms, and an extinction of
+those which pre-existed on the earth; some species having endured for a
+longer, others for a shorter, time; while none have ever reappeared after
+once dying out. The law which has governed the creation and extinction of
+species seems to be expressed in the verse of the poet,&mdash;</p>
+
+<div class="left20">
+<p class="poem lihei1">
+Natura il fece, e poi ruppe la <span class="wosp3">stampa.&nbsp;</span><span class="smcap">Ariosto.</span><br>
+Nature made him, and then broke the die.</p>
+</div>
+
+<p>And this circumstance it is, which confers on fossils their highest value
+as chronological tests, giving to each of them, in the eyes of the
+geologist, that authority which belongs to contemporary medals in history.</p>
+
+<p>The same cannot be said of each peculiar variety of rock; for some of
+these, as red marl and red sandstone, for example, may occur at once at the
+top, bottom, and middle of the entire sedimentary series; exhibiting in
+each position so perfect an identity of mineral aspect as to be
+undistinguishable. Such exact repetitions, however, of the same mixtures of
+sediment have not often been produced, at distant periods, in precisely the
+same parts of the globe; and even where this has happened, we are seldom in
+any danger of confounding together the monuments of remote eras, when we
+have studied their imbedded fossils and relative position.</p>
+
+<p>It was remarked that the same species of organic remains cannot be traced
+horizontally, or in the direction of the planes of stratification for
+indefinite distances. This might have been expected from analogy; for when
+we inquire into the present distribution of living beings, we find that the
+habitable surface of the sea and land may be divided into a considerable
+number of distinct provinces, each peopled by a peculiar assemblage of
+animals and plants. In the Principles of Geology, I have endeavoured to
+point out the extent and probable origin of these separate divisions; and
+it was shown that climate is only one of many causes on which they depend,
+and <span class="pagenum"><a id="page99"></a>[p.99]</span>that difference of longitude as well as latitude is generally
+accompanied by a dissimilarity of indigenous species.</p>
+
+<p>As different seas, therefore, and lakes are inhabited at the same period,
+by different aquatic animals and plants, and as the lands adjoining these
+may be peopled by distinct terrestrial species, it follows that distinct
+fossils will be imbedded in contemporaneous deposits. If it were
+otherwise&mdash;if the same species abounded in every climate, or in every part
+of the globe where, so far as we can discover, a corresponding temperature
+and other conditions favourable to their existence are found&mdash;the
+identification of mineral masses of the same age, by means of their
+included organic contents, would be a matter of still greater certainty.</p>
+
+<p>Nevertheless, the extent of some single zoological provinces, especially
+those of marine animals, is very great; and our geological researches have
+proved that the same laws prevailed at remote periods; for the fossils are
+often identical throughout wide spaces, and in a great number of detached
+deposits, in which the mineral nature of the rocks is variable.</p>
+
+<p>The doctrine here laid down will be more readily understood, if we reflect
+on what is now going on in the Mediterranean. That entire sea may be
+considered as one zoological province; for, although certain species of
+testacea and zoophytes may be very local, and each region has probably some
+species peculiar to it, still a considerable number are common to the whole
+Mediterranean. If, therefore, at some future period, the bed of this inland
+sea should be converted into land, the geologist might be enabled, by
+reference to organic remains, to prove the contemporaneous origin of
+various mineral masses scattered over a space equal in area to the half of
+Europe.</p>
+
+<p>Deposits, for example, are well known to be now in progress in this sea in
+the deltas of the Po, Rhone, Nile, and other rivers, which differ as
+greatly from each other in the nature of their sediment as does the
+composition of the mountains which they drain. There are also other
+quarters of the Mediterranean, as off the coast of Campania, or near the
+base of Etna, in Sicily, or in the Grecian Archipelago, where another class
+of rocks is now forming; where showers of volcanic ashes occasionally fall
+into the sea, and streams of lava overflow its bottom; and where, in the
+intervals between volcanic eruptions, beds of sand and clay are frequently
+derived from the waste of cliffs, or the turbid waters of rivers.
+Limestones, moreover, such as the Italian travertins, are here and there
+precipitated from the waters of mineral springs, some of which rise up from
+the bottom of the sea. In all these detached formations, so diversified in
+their lithological characters, the remains of the same shells, corals,
+crustacea, and fish are becoming inclosed; or, at least, a sufficient
+number must be common to the different localities to enable the zoologist
+to refer them all to one contemporaneous assemblage of species.</p>
+
+<p>There are, however, certain combinations of geographical circumstances
+which cause distinct provinces of animals and plants to be <span class="pagenum"><a id="page100"></a>[p.100]</span>
+separated from each other by very narrow limits; and hence it must happen,
+that strata will be sometimes formed in contiguous regions, differing
+widely both in mineral contents and organic remains. Thus, for example, the
+testacea, zoophytes, and fish of the Red Sea are, as a group, extremely
+distinct from those inhabiting the adjoining parts of the Mediterranean,
+although the two seas are separated only by the narrow isthmus of Suez. Of
+the bivalve shells, according to Philippi, not more than a fifth are common
+to the Red Sea and the sea around Sicily, while the proportion of univalves
+(or Gasteropoda) is still smaller, not exceeding eighteen in a hundred.
+Calcareous formations have accumulated on a great scale in the Red Sea in
+modern times, and fossil shells of existing species are well preserved
+therein; and we know that at the mouth of the Nile large deposits of mud
+are amassed, including the remains of Mediterranean species. It follows,
+therefore, that if at some future period the bed of the Red Sea should be
+laid dry, the geologist might experience great difficulties in endeavouring
+to ascertain the relative age of these formations, which, although
+dissimilar both in organic and mineral characters, were of synchronous
+origin.</p>
+
+<p>But, on the other hand, we must not forget that the north-western shores of
+the Arabian Gulf, the plains of Egypt, and the isthmus of Suez, are all
+parts of one province of <i>terrestrial</i> species. Small streams, therefore,
+occasional land-floods, and those winds which drift clouds of sand along
+the deserts, might carry down into the Red Sea the same shells of
+fluviatile and land testacea which the Nile is sweeping into its delta,
+together with some remains of terrestrial plants and the bones of
+quadrupeds, whereby the groups of strata, before alluded to, might,
+notwithstanding the discrepancy of their mineral composition and <i>marine</i>
+organic fossils, be shown to have belonged to the same epoch.</p>
+
+<p>Yet while rivers may thus carry down the same fluviatile and terrestrial
+spoils into two or more seas inhabited by different marine species, it will
+much more frequently happen, that the co-existence of terrestrial species
+of distinct zoological and botanical provinces will be proved by the
+identity of the marine beings which inhabited the intervening space. Thus,
+for example, the land quadrupeds and shells of the south of Europe, north
+of Africa, and north-west of Asia, are different, yet their remains are all
+washed down by rivers flowing from these three countries into the
+Mediterranean.</p>
+
+<p>In some parts of the globe, at the present period, the line of demarcation
+between distinct provinces of animals and plants is not very strongly
+marked, especially where the change is determined by temperature, as in
+seas extending from the temperate to the tropical zone, or from the
+temperate to the arctic regions. Here a gradual passage takes place from
+one set of species to another. In like manner the geologist, in studying
+particular formations of remote periods, has sometimes been able to trace
+the gradation from one ancient province to another, by observing carefully
+the fossils of all the intermediate places. His success in thus acquiring a
+knowledge <span class="pagenum"><a id="page101"></a>[p.101]</span>of the zoological or botanical geography of very
+distant eras has been mainly owing to this circumstance, that the mineral
+character has no tendency to be affected by climate. A large river may
+convey yellow or red mud into some part of the ocean, where it may be
+dispersed by a current over an area several hundred leagues in length, so
+as to pass from the tropics into the temperate zone. If the bottom of the
+sea be afterwards upraised, the organic remains imbedded in such yellow or
+red strata may indicate the different animals or plants which once
+inhabited at the same time the temperate and equatorial regions.</p>
+
+<p>It may be true, as a general rule, that groups of the same species of
+animals and plants may extend over wider areas than deposits of homogeneous
+composition; and if so, pal�ontological characters will be of more
+importance in geological classification than mineral composition; but it is
+idle to discuss the relative value of these tests, as the aid of both is
+indispensable, and it fortunately happens, that where the one criterion
+fails, we can often avail ourselves of the other.</p>
+
+<p><i>Test by included fragments of older rocks.</i>&mdash;It was stated, that
+independent proof may sometimes be obtained of the relative date of two
+formations, by fragments of an older rock being included in a newer one.
+This evidence may sometimes be of great use, where a geologist is at a loss
+to determine the relative age of two formations from want of clear sections
+exhibiting their true order of position, or because the strata of each
+group are vertical. In such cases we sometimes discover that the more
+modern rock has been in part derived from the degradation of the older.
+Thus, for example, we may find in one part of a country chalk with flints;
+and, in another, a distinct formation, consisting of alternations of clay,
+sand, and pebbles. If some of these pebbles consist of similar flint and
+fossil shells, sponges, and foraminifer�, of the same species as those in
+the chalk, we may confidently infer that the chalk is the oldest of the two
+formations.</p>
+
+<p><i>Chronological groups.</i>&mdash;The number of groups into which the fossiliferous
+strata may be separated are more or less numerous, according to the views
+of classification which different geologists entertain; but when we have
+adopted a certain system of arrangement, we immediately find that a few
+only of the entire series of groups occur one upon the other in any single
+section or district.</p>
+
+<a id="img109" name="img109"></a>
+<div class="figcenter smaller">
+<p>Fig. 104.</p>
+<img src="images/img109.jpg" width="400" height="073" alt="" title=""></div>
+
+<p>The thinning out of individual strata was before described (<a href="#page16">p. 16.</a>). But
+let the annexed diagram represent seven fossiliferous groups, instead of as
+many strata. It will then be seen that in the middle <span class="pagenum"><a id="page102"></a>[p.102]</span>all the
+superimposed formations are present; but in consequence of some of them
+thinning out, No. 2. and No. 5. are absent at one extremity of the section,
+and No. 4. at the other.</p>
+
+<a id="img110" name="img110"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 105.</p>
+<img src="images/img110.jpg" width="500" height="167" alt="" title="">
+<p>Section South of <span class="wosp3">Bristol. A.</span> C. Ramsay.<br>
+Length of section 4 miles. &nbsp; &nbsp; <i>a</i>, <i>b</i>. Level of the sea.</p>
+<ul class="smaller martopm05 leftal add2em">
+<li>1. Inferior oolite.</li>
+<li>2. Lias.</li>
+<li>3. New red sandstone.</li>
+<li>4. Magnesian conglomerate.</li>
+<li>5. Coal measure.</li>
+<li>6. Carboniferous limestone.</li>
+<li>7. Old red sandstone.</li>
+</ul></div>
+
+<p>In the annexed diagram, <a href="#img110">fig. 105.</a>, a real section of the geological
+formations in the neighbourhood of Bristol and the Mendip Hills, is
+presented to the reader as laid down on a true scale by Professor Ramsay,
+where the newer groups 1, 2, 3, 4. rest unconformably on the formations 5
+and 6. Here at the southern end of the line of section we meet with the
+beds No. 3. (the New Red Sandstone) resting immediately on No. 6., while
+farther north, as at Dundry Hill, we behold six groups superimposed one
+upon the other, comprising all the strata from the inferior oolite to the
+coal and carboniferous limestone. The limited extension of the groups 1 and
+2. is owing to denudation, as these formations end abruptly, and have left
+outlying patches to attest the fact of their having originally covered a
+much wider area.</p>
+
+<p>In many instances, however, the entire absence of one or more formations of
+intervening periods between two groups, such as 3. and 5. in the same
+section, arises, not from the destruction of what once existed, but because
+no strata of an intermediate age were ever deposited on the inferior rock.
+They were not formed at that place, either because the region was dry land
+during the interval, or because it was part of a sea or lake to which no
+sediment was carried.</p>
+
+<p>In order, therefore, to establish a chronological succession of
+fossiliferous groups, a geologist must begin with a single section, in
+which several sets of strata lie one upon the other. He must then trace
+these formations, by attention to their mineral character and fossils,
+continuously, as far as possible, from the starting point. As often as he
+meets with new groups, he must ascertain by superposition their age
+relatively to those first examined, and thus learn how to intercalate them
+in a tabular arrangement of the whole.</p>
+
+<p>By this means the German, French, and English geologists have determined
+the succession of strata throughout a great part of <span class="pagenum"><a id="page103"></a>[p.103]</span>Europe, and
+have adopted pretty generally the following groups, almost all of which
+have their representatives in the British Islands.</p>
+
+<p><i>Groups of Fossiliferous Strata observed in Western Europe, arranged in
+what is termed a descending Series, or beginning with the newest.</i> (<i>See a
+more detailed Tabular view</i>, pp. <a href="#page360">360.</a> <a href="#page365">365.</a>)</p>
+
+
+<table  border="0" cellpadding="2" summary="GROUPS OF FOSSILIFEROUS STRATA OBSERVED IN WESTERN EUROPE.">
+<colgroup>
+    <col width="45%">
+    <col width="10%">
+    <col width="10%">
+    <col width="35%">
+</colgroup>
+
+<tr>
+  <td class="td-left tdtx-mid">1. Post-Pliocene, including those of the
+  Recent, or human period.</td>
+  <td>&nbsp;</td>
+  <td rowspan="22">&nbsp;</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="ftsizexs">&nbsp;</td>
+  <td valign="middle" rowspan="5" style="white-space: nowrap; font-size: 60pt; font-weight: 600;" class="td-mous">}</td>
+  <td class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">2. Newer Pliocene, or Pleistocene.</td>
+  <td rowspan="4" class="td-left tdtx-mid">Tertiary, Supracretaceous<a name="FNanchor_K_1" id="FNanchor_K_1"></a><a href="#Footnote_K_1" class="fnanchor">[103-A]</a>,
+  or Cainozoic.<a name="FNanchor_K_2" id="FNanchor_K_2"></a><a href="#Footnote_K_2" class="fnanchor">[103-B]</a></td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">3. Older Pliocene.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">4. Miocene.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">5. Eocene.</td>
+</tr>
+
+<tr>
+  <td class="ftsizexs">&nbsp;</td>
+  <td valign="middle" rowspan="9" style="white-space: nowrap; font-size: 105pt; font-weight: 100;" class="td-mous padtop">}</td>
+  <td class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">6. Chalk.</td>
+  <td rowspan="8" class="td-left tdtx-mid">Secondary, or Mesozoic.<a name="FNanchor_K_3" id="FNanchor_K_3"></a><a href="#Footnote_K_3" class="fnanchor">[103-C]</a></td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">7. Greensand.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">8. Wealden.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">9. Upper Oolite.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">10. Middle Oolite.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">11. Lower Oolite.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">12. Lias.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">13. Trias.</td>
+</tr>
+
+<tr>
+  <td class="ftsizexs">&nbsp;</td>
+  <td valign="middle" rowspan="7" style="white-space: nowrap; font-size: 90pt; font-weight: 100;" class="td-mous">}</td>
+  <td class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">14. Permian.</td>
+  <td rowspan="6" class="td-left tdtx-mid">Primary fossiliferous,
+  or paleozoic.<a name="FNanchor_K_4" id="FNanchor_K_4"></a><a href="#Footnote_K_4" class="fnanchor">[103-D]</a></td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">15. Coal.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">16. Old Red sandstone, or Devonian.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">17. Upper Silurian.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">18. Lower Silurian.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">19. Cambrian and older fossiliferous strata.</td>
+</tr>
+</table>
+
+
+<p>It is not pretended that the three principal sections in the above table,
+called primary, secondary, and tertiary, are of equivalent importance, or
+that the eighteen subordinate groups comprise monuments relating to equal
+portions of past time, or of the earth's history. But we can assert that
+they each relate to successive periods, during which certain animals and
+plants, for the most part peculiar to their respective eras, have
+flourished, and during which different kinds of sediment were deposited in
+the space now occupied by Europe.</p>
+
+<p>If we were disposed, on pal�ontological grounds<a name="FNanchor_K_5" id="FNanchor_K_5"></a><a href="#Footnote_K_5" class="fnanchor">[103-5]</a>, to divide the
+entire fossiliferous series into a few groups less numerous than those in
+the above table, and more nearly co-ordinate in value than the sections
+called primary, secondary, and tertiary, we might, perhaps, adopt the six
+groups or periods given in the next table (<a href="#page104">p. 104.</a>).</p>
+
+<p>At the same time, I may observe, that, in the present state of the science,
+when we have not yet compared the evidence derivable from all classes of
+fossils, not even those most generally distributed, such as shells, corals,
+and fish, such generalizations are premature, and can only be regarded as
+conjectural or provisional schemes for the founding of large natural
+groups.</p>
+
+
+<h3><span class="pagenum"><a id="page104"></a>[p.104]</span><i>Fossiliferous Strata of Western Europe divided into Six Groups.</i></h3>
+
+
+<table  border="0" cellpadding="2" summary="FOSSILIFEROUS STRATA OF WESTERN EUROPE DIVIDED INTO SIX GROUPS.">
+<colgroup>
+    <col width="45%">
+    <col width="10%">
+    <col width="45%">
+</colgroup>
+
+<tr>
+  <td class="td-left tdtx-top">1. Post Pliocene and
+  Tertiary</td>
+  <td class="gmous">}</td>
+  <td class="td-left tdtx-top">from the Post-Pliocene to the Eocene inclusive.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">2. Cretaceous</td>
+  <td class="gmous">{</td>
+  <td class="td-left tdtx-top">from the Maestricht Chalk to the Lower Greensand
+  inclusive.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">3. Oolitic</td>
+  <td class="gmous">}</td>
+  <td class="td-left tdtx-top">from the Wealden to the Lias inclusive.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">4. Triassic</td>
+  <td class="gmous">{</td>
+  <td class="td-left tdtx-top">including the Keuper, Muschelkalk, and Bunter
+  Sandstein of the Germans.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">5. Permian, Carboniferous,
+  and Devonian</td>
+  <td class="gmous">}</td>
+  <td class="td-left tdtx-top">including Magnesian Limestone (Zechstein), Coal,
+  Mountain Limestone, and Old Red sandstone.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">6. Silurian and Cambrian</td>
+  <td class="gmous">{</td>
+  <td class="td-left tdtx-top">from the Upper Silurian to the oldest fossiliferous
+  rocks inclusive.</td>
+</tr>
+</table>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER X.</h2>
+
+<h4>CLASSIFICATION OF TERTIARY FORMATIONS.&mdash;POST-PLIOCENE GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">General principles of classification of tertiary strata &mdash; Detached
+formations scattered over Europe &mdash; Strata of Paris and
+London &mdash; More modern groups &mdash; Peculiar difficulties in determining
+the chronology of tertiary formations &mdash; Increasing proportion of living
+species of shells in strata of newer origin &mdash; Terms Eocene, Miocene,
+and Pliocene &mdash; Post-Pliocene strata &mdash; Recent or human
+period &mdash; Older Post-Pliocene formations of Naples, Uddevalla, and
+Norway &mdash; Ancient upraised delta of the Mississippi &mdash; Loess of the
+Rhine.</p></div>
+
+
+<p><span class="smcap">Before</span> describing the most modern of the sets of strata enumerated in the
+tables given at the end of the last chapter, it will be necessary to say
+something generally of the mode of classifying the formations called
+tertiary.</p>
+
+<p>The name of tertiary has been given to them, because they are all posterior
+in date to the rocks termed "secondary," of which the chalk constitutes the
+newest group. These tertiary strata were at first confounded, as before
+stated, <a href="#page91">p. 91.</a>, with the superficial alluviums of Europe; and it was long
+before their real extent and thickness, and the various ages to which they
+belong, were fully recognized. They were observed to occur in patches, some
+of freshwater, others of marine origin, their geographical area being
+usually small as compared to the secondary formations, and their position
+often suggesting the idea of their having been deposited in different bays,
+lakes, estuaries, or inland seas, after a large portion of the space now
+occupied by Europe had already been converted into dry land.</p>
+
+<p>The first deposits of this class, of which the characters were accurately
+determined, were those occurring in the neighbourhood of Paris, described
+in 1810 by MM. Cuvier and Brongniart. They were ascertained to consist of
+successive sets of strata, some of marine, others of freshwater origin,
+lying one upon the other. The fossil shells and corals were perceived to be
+almost all of unknown <span class="pagenum"><a id="page105"></a>[p.105]</span>species, and to have in general a near
+affinity to those now inhabiting warmer seas. The bones and skeletons of
+land animals, some of them of large size, and belonging to more than forty
+distinct species, were examined by Cuvier, and declared by him not to agree
+specifically and for the most part not even generically, with any hitherto
+observed in the living creation.</p>
+
+<p>Strata were soon afterwards brought to light in the vicinity of London, and
+in Hampshire, which, although dissimilar in mineral composition, were
+justly inferred by Mr. T. Webster to be of the same age as those of Paris,
+because the greater number of the fossil shells were specifically
+identical. For the same reason rocks found on the Gironde, in the South of
+France, and at certain points in the North of Italy, were suspected to be
+of contemporaneous origin.</p>
+
+<p>A variety of deposits were afterwards found in other parts of Europe, all
+reposing immediately on rocks as old or older than the chalk, and which
+exhibited certain general characters of resemblance in their organic
+remains to those previously observed near Paris and London. An attempt was
+therefore made at first to refer the whole to one period; and when at
+length this seemed impracticable, it was contended that as in the Parisian
+series there were many subordinate formations of considerable thickness
+which must have accumulated one after the other, during a great lapse of
+time, so the various patches of tertiary strata scattered over Europe might
+correspond in age, some of them to the older, and others to the newer,
+subdivisions of the Parisian series.</p>
+
+<p>This error, although most unavoidable on the part of those who made the
+first generalizations in this branch of geology, retarded seriously for
+some years the progress of classification. A more scrupulous attention to
+specific distinctions, aided by a careful regard to the relative position
+of the strata containing them, led at length to the conviction that there
+were formations both marine and freshwater of various ages, and all newer
+than the strata of the neighbourhood of Paris and London.</p>
+
+<p>One of the first steps in this chronological reform was made in 1811, by an
+English naturalist, Mr. Parkinson, who pointed out the fact that certain
+shelly strata, provincially termed "Crag" in Suffolk, lay decidedly over a
+deposit which was the continuation of the blue clay of London. At the same
+time he remarked that the fossil testacea in these newer beds were distinct
+from those of the blue clay, and that while some of them were of unknown
+species, others were identical with species now inhabiting the British
+seas.</p>
+
+<p>Another important discovery was soon afterwards made by Brocchi in Italy,
+who investigated the argillaceous and sandy deposits replete with shells
+which form a low range of hills, flanking the Apennines on both sides, from
+the plains of the Po to Calabria. These lower hills were called by him the
+Subapennines, and were formed of strata of different ages, all newer than
+those of Paris and London.</p>
+
+<p>Another tertiary group occurring in the neighbourhood of Bordeaux and Dax,
+in the south of France, was examined by M. de Basterot in <span class="pagenum"><a id="page106"></a>[p.106]</span>1825,
+who described and figured several hundred species of shells, which differed
+for the most part both from the Parisian series and those of the
+Subapennine hills. It was soon, therefore, suspected that this fauna might
+belong to a period intermediate between that of the Parisian and
+Subapennine strata, and it was not long before the evidence of
+superposition was brought to bear in support of this opinion; for other
+strata, contemporaneous with those of Bordeaux, were observed in one
+district (the Valley of the Loire), to overlie the Parisian formation, and
+in another (in Piedmont) to underlie the Subapennine beds. The first
+example of these was pointed out in 1829 by M. Desnoyers, who ascertained
+that the sand and marl of marine origin called Faluns, near Tours, in the
+basin of the Loire, full of sea-shells and corals, rested upon a lacustrine
+formation, which constitutes the uppermost subdivision of the Parisian
+group, extending continuously throughout a great table-land intervening
+between the basin of the Seine and that of the Loire. The other example
+occurs in Italy, where strata, containing many fossils similar to those of
+Bordeaux, were observed by Bonelli and others in the environs of Turin,
+subjacent to strata belonging to the Subapennine group of Brocchi.</p>
+
+<p>Without pretending to give a complete sketch of the progress of discovery,
+I may refer to the facts above enumerated, as illustrating the course
+usually pursued by geologists when they attempt to found new chronological
+divisions. The method bears some analogy to that pursued by the naturalist
+in the construction of genera, when he selects a typical species, and then
+classes as congeners all other species of animals and plants which agree
+with this standard within certain limits. The genera A. and C. having been
+founded on these principles, a new species is afterwards met with,
+departing widely both from A. and C., but in many respects of an
+intermediate character. For this new type it becomes necessary to institute
+the new genus B., in which are included all species afterwards brought to
+light, which agree more nearly with B. than with the types of A. or C. In
+like manner a new formation is met with in geology, and the characters of
+its fossil fauna and flora investigated. From that moment it is considered
+as a record of a certain period of the earth's history, and a standard to
+which other deposits may be compared. If any are found containing the same
+or nearly the same organic remains, and occupying the same relative
+position, they are regarded in the light of contemporary annals. All such
+monuments are said to relate to one period, during which certain events
+occurred, such as the formation of particular rocks by aqueous or volcanic
+agency, or the continued existence and fossilization of certain tribes of
+animals and plants. When several of these periods have had their true
+places assigned to them in a chronological series, others are discovered
+which it becomes necessary to intercalate between those first known; and
+the difficulty of assigning clear lines of separation must unavoidably
+increase in proportion as chasms in the past history of the globe are
+filled up.</p>
+
+<p>Every zoologist and botanist is aware that it is a comparatively easy task
+to establish genera in departments which have been enriched <span class="pagenum"><a id="page107"></a>[p.107]</span>with
+only a small number of species, and where there is as yet no tendency in
+one set of characters to pass almost insensibly, by a multitude of
+connecting links, into another. They also know that the difficulty of
+classification augments, and that the artificial nature of their divisions
+becomes more apparent, in proportion to the increased number of objects
+brought to light. But in separating families and genera, they have no other
+alternative than to avail themselves of such breaks as still remain, or of
+every hiatus in the chain of animated beings which is not yet filled up. So
+in geology, we may be eventually compelled to resort to sections of time as
+arbitrary, and as purely conventional, as those which divide the history of
+human events into centuries. But in the present state of our knowledge, it
+is more convenient to use the interruptions which still occur in the
+regular sequence of geological monuments, as boundary lines between our
+principal groups or periods, even though the groups thus established are of
+very unequal value.</p>
+
+<p>The isolated position of distinct tertiary deposits in different parts of
+Europe has been already alluded to. In addition to the difficulty presented
+by this want of continuity when we endeavour to settle the chronological
+relations of these deposits, another arises from the frequent dissimilarity
+in mineral character of strata of contemporaneous date, such, for example,
+as those of London and Paris before mentioned. The identity or non-identity
+of species is also a criterion which often fails us. For this we might have
+been prepared, for we have already seen, that the Mediterranean and Red
+Sea, although within 70 miles of each other, on each side of the Isthmus of
+Suez, have each their peculiar fauna; and a marked difference is found in
+the four groups of testacea now living in the Baltic, English Channel,
+Black Sea, and Mediterranean, although all these seas have many species in
+common. In like manner a considerable diversity in the fossils of different
+tertiary formations, which have been thrown down in distinct seas,
+estuaries, bays, and lakes, does not always imply a distinctness in the
+times when they were produced, but may have arisen from climate and
+conditions of physical geography wholly independent of time. On the other
+hand, it is now abundantly clear, as the result of geological
+investigation, that different sets of tertiary strata, immediately
+superimposed upon each other, contain distinct imbedded species of fossils,
+in consequence of fluctuations which have been going on in the animate
+creation, and by which in the course of ages one state of things in the
+organic world has been substituted for another wholly dissimilar. It has
+also been shown that in proportion as the age of a tertiary deposit is more
+modern, so is its fauna more analogous to that now in being in the
+neighbouring seas. It is this law of a nearer agreement of the fossil
+testacea with the species now living, which may often furnish us with a
+clue for the chronological arrangement of scattered deposits, where we
+cannot avail ourselves of any one of the three ordinary chronological
+tests; namely, superposition, mineral character, and the specific identity
+of the fossils.</p>
+
+<p><span class="pagenum"><a id="page108"></a>[p.108]</span>Thus, for example, on the African border of the Red Sea, at the
+height of 40 feet, and sometimes more, above its level, a white calcareous
+formation has been observed, containing several hundred species of shells
+differing from those found in the clay and volcanic tuff of the country
+round Naples, and of the contiguous island of Ischia. Another deposit has
+been found at Uddevalla, in Sweden, in which the shells do not agree with
+those found near Naples. But although in these three cases there may be
+scarcely a single shell common to the three different deposits, we do not
+hesitate to refer them all to one period (the Post-Pliocene), because of
+the very close agreement of the fossil species in every instance with those
+now living in the contiguous seas.</p>
+
+<p>To take another example, where the fossil fauna recedes a few steps farther
+back from our own times. We may compare, first, the beds of loam and clay
+bordering the Clyde in Scotland (called glacial by some geologists),
+secondly, others of fluvio-marine origin near Norwich, and, lastly, a third
+set often rising to considerable heights in Sicily, and we discover that in
+every case more than three-fourths of the shells agree with species still
+living, while the remainder are extinct. Hence we may conclude that all
+these, greatly diversified as are their organic remains, belong to one and
+the same era, or to a period immediately antecedent to the Post-Pliocene,
+because there has been time in each of the areas alluded to for an equal or
+nearly equal amount of change in the marine testaceous fauna.
+Contemporaneousness of origin is inferred in these cases, in spite of the
+most marked differences of mineral character or organic contents, from a
+similar degree of divergence in the shells from those now living in the
+adjoining seas. The advantage of such a test consists in supplying us with
+a common point of departure in all countries, however remote.</p>
+
+<p>But the farther we recede from the present times, and the smaller the
+relative number of recent as compared with extinct species in the tertiary
+deposits, the less confidence can we place in the exact value of such a
+test, especially when comparing the strata of very distant regions; for we
+cannot presume that the rate of former alterations in the animate world, or
+the continual going out and coming in of species, has been every where
+exactly equal in equal quantities of time. The form of the land and sea,
+and the climate, may have changed more in one region than in another; and
+consequently there may have been a more rapid destruction and renovation of
+species in one part of the globe than elsewhere. Considerations of this
+kind should undoubtedly put us on our guard against relying too implicitly
+on the accuracy of this test; yet it can never fail to throw great light on
+the chronological relations of tertiary groups with each other, and with
+the Post-Pliocene period.</p>
+
+<p>We may derive a conviction of this truth not only from a study of
+geological monuments of all ages, but also by reflecting on the tendency
+which prevails in the present state of nature to a uniform rate of
+simultaneous fluctuation in the flora and fauna of the whole globe. The
+grounds of such a doctrine cannot be discussed here, and I <span class="pagenum"><a id="page109"></a>[p.109]</span>have
+explained them at some length in the third Book of the Principles of
+Geology, where the causes of the successive extinction of species are
+considered. It will be there seen that each local change in climate and
+physical geography is attended with the immediate increase of certain
+species, and the limitation of the range of others. A revolution thus
+effected is rarely, if ever, confined to a limited space, or to one
+geographical province of animals or plants, but affects several other
+surrounding and contiguous provinces. In each of these, moreover, analogous
+alterations of the stations and habitations of species are simultaneously
+in progress, reacting in the manner already alluded to on the first
+province. Hence, long before the geography of any particular district can
+be essentially altered, the flora and fauna throughout the world will have
+been materially modified by countless disturbances in the mutual relation
+of the various members of the organic creation to each other. To assume
+that in one large area inhabited exclusively by a single assemblage of
+species any important revolution in physical geography can be brought
+about, while other areas remain stationary in regard to the position of
+land and sea, the height of mountains, and so forth, is a most improbable
+hypothesis, wholly opposed to what we know of the laws now governing the
+aqueous and igneous causes. On the other hand, even were this conceivable,
+the communication of heat and cold between different parts of the
+atmosphere and ocean is so free and rapid, that the temperature of certain
+zones cannot be materially raised or lowered without others being
+immediately affected; and the elevation or diminution in height of an
+important chain of mountains or the submergence of a wide tract of land
+would modify the climate even of the antipodes.</p>
+
+<p>It will be observed that in the foregoing allusions to organic remains, the
+testacea or the shell-bearing mollusca are selected as the most useful and
+convenient class for the purposes of general classification. In the first
+place, they are more universally distributed through strata of every age
+than any other organic bodies. Those families of fossils which are of rare
+and casual occurrence are absolutely of no avail in establishing a
+chronological arrangement. If we have plants alone in one group of strata
+and the bones of mammalia in another, we can draw no conclusion respecting
+the affinity or discordance of the organic beings of the two epochs
+compared; and the same may be said if we have plants and vertebrated
+animals in one series and only shells in another. Although corals are more
+abundant, in a fossil state, than plants, reptiles, or fish, they are still
+rare when contrasted with shells, especially in the European tertiary
+formations. The utility of the testacea is, moreover, enhanced by the
+circumstance that some forms are proper to the sea, others to the land, and
+others to freshwater. Rivers scarcely ever fail to carry down into their
+deltas some land shells, together with species which are at once fluviatile
+and lacustrine. By this means we learn what terrestrial, freshwater, and
+marine species co-existed at particular eras of the past; and having thus
+identified strata formed in seas with others which originated
+contemporaneously in inland lakes, we <span class="pagenum"><a id="page110"></a>[p.110]</span>are then enabled to advance
+a step farther, and show that certain quadrupeds or aquatic plants, found
+fossil in lacustrine formations, inhabited the globe at the same period
+when certain fish, reptiles, and zoophytes lived in the ocean.</p>
+
+<p>Among other characters of the molluscous animals, which render them
+extremely valuable in settling chronological questions in geology, may be
+mentioned, first, the wide geographical range of many species; and,
+secondly, what is probably a consequence of the former, the great duration
+of species in this class, for they appear to have surpassed in longevity
+the greater number of the mammalia and fish. Had each species inhabited a
+very limited space, it could never, when imbedded in strata, have enabled
+the geologist to identify deposits at distant points; or had they each
+lasted but for a brief period, they could have thrown no light on the
+connection of rocks placed far from each other in the chronological, or, as
+it is often termed, vertical series.</p>
+
+<p>Many authors have divided the European tertiary strata into three
+groups&mdash;lower, middle, and upper; the lower comprising the oldest
+formations of Paris and London before-mentioned; the middle those of
+Bordeaux and Touraine; and the upper all those newer than the middle group.</p>
+
+<p>When engaged in 1828 in preparing my work on the Principles of Geology, I
+conceived the idea of classing the whole series of tertiary strata in four
+groups, and endeavouring to find characters for each, expressive of their
+different degrees of affinity to the living fauna. With this view, I
+obtained information respecting the specific identity of many tertiary and
+recent shells from several Italian naturalists, and among others from
+Professors Bonelli, Guidotti, and Costa. Having in 1829 become acquainted
+with M. Deshayes, of Paris, already well known by his conchological works,
+I learnt from him that he had arrived, by independent researches, and by
+the study of a large collection of fossil and recent shells, at very
+similar views respecting the arrangement of tertiary formations. At my
+request he drew up, in a tabular form, lists of all the shells known to him
+to occur both in some tertiary formation and in a living state, for the
+express purpose of ascertaining the proportional number of fossil species
+identical with the recent which characterized successive groups; and this
+table, planned by us in common, was published by me in 1833.<a name="FNanchor_L_1" id="FNanchor_L_1"></a><a href="#Footnote_L_1" class="fnanchor">[110-A]</a> The
+number of tertiary fossil shells examined by M. Deshayes was about 3000;
+and the recent species with which they had been compared about 5000. The
+result then arrived at was, that in the lower tertiary strata, or those of
+London and Paris, there were about 3<span class="smaller"><sup>1</sup>/<sub>2</sub></span> per cent. of species identical
+with recent; in the middle tertiary of the Loire and Gironde about 17 per
+cent.; and in the upper tertiary or Subapennine beds, from 35 to 50 per
+cent. In formations still more modern, some of which I had particularly
+studied in Sicily, where they attain a vast thickness and elevation above
+the sea, the number of species identical with those now living was believed
+to be from <span class="pagenum"><a id="page111"></a>[p.111]</span>90 to 95 per cent. For the sake of clearness and
+brevity, I proposed to give short technical names to these four groups, or
+the periods to which they respectively belonged. I called the first or
+oldest of them Eocene, the second Miocene, the third Older Pliocene, and
+the last or fourth Newer Pliocene. The first of the above terms, Eocene, is
+derived from &#951;&#969;&#962;, eos, <i>dawn</i>, and &#954;&#945;&#953;&#957;&#959;&#962;, cainos,
+<i>recent</i>, because the fossil shells of this period contain an extremely
+small proportion of living species, which may be looked upon as indicating
+the dawn of the existing state of the testaceous fauna, no recent species
+having been detected in the older or secondary rocks.</p>
+
+<p>The term Miocene (from &#956;&#949;&#953;&#959;&#957;, meion, <i>less</i>, and &#954;&#945;&#953;&#957;&#959;&#962;,
+cainos, <i>recent</i>) is intended to express a minor proportion of recent
+species (of testacea), the term Pliocene (from &#960;&#955;&#949;&#953;&#959;&#957;, pleion,
+<i>more</i>, and &#954;&#945;&#953;&#957;&#959;&#962;, cainos, <i>recent</i>) a comparative plurality of
+the same. It may assist the memory of students to remind them, that the
+<i>Mi</i>ocene contain a <i>mi</i>nor proportion, and <i>Pl</i>iocene a comparative
+<i>pl</i>urality of recent species; and that the greater number of recent
+species always implies the more modern origin of the strata.</p>
+
+<p>It has sometimes been objected to this nomenclature that certain species of
+infusoria found in the chalk are still existing, and, on the other hand,
+the Miocene and Older Pliocene deposits often contain the remains of
+mammalia, reptiles, and fish, exclusively of extinct species. But the
+reader must bear in mind that the terms Eocene, Miocene, and Pliocene were
+originally invented with reference purely to conchological data, and in
+that sense have always been and are still used by me.</p>
+
+<p>The distribution of the fossil species from which the results before
+mentioned were obtained in 1830 by M. Deshayes was as follows:&mdash;</p>
+
+
+<table  border="0" cellpadding="1" summary="DISTRIBUTION OF THE FOSSIL SPECIES">
+<colgroup>
+    <col width="65%">
+    <col width="5%">
+    <col width="15%">
+    <col width="15%">
+</colgroup>
+
+<tr>
+  <td class="td-left">In the formations of the Pliocene periods, older and newer</td>
+  <td rowspan="6">&nbsp;</td>
+  <td class="td-right">777</td>
+  <td rowspan="6">&nbsp;<td>
+</tr>
+
+<tr>
+  <td class="td-left">In the Miocene</td>
+  <td class="td-right">1021</td>
+</tr>
+
+<tr>
+  <td class="td-left">In the Eocene</td>
+  <td class="td-right">1238</td>
+</tr>
+
+<tr>
+  <td rowspan="3">&nbsp;</td>
+  <td class="td-right">&mdash;&mdash;&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-right">3036</td>
+</tr>
+
+<tr>
+  <td class="td-right">&mdash;&mdash;&mdash;</td>
+</tr>
+</table>
+
+
+<p>Since the year 1830 the progress of conchological science has been most
+rapid, and the number of living species obtained from different parts of
+the globe has been raised from about 5000 to more than 10,000. New fossil
+species have also been added to our collections in great abundance; and at
+the same time a more copious supply of individuals both of fossil and
+recent species, some of which were previously very rare, have been
+procured, affording more ample data for determining the specific character.
+Besides the reforms introduced in consequence of these new zoological
+facilities, other errors of a geological nature have been in many instances
+removed.</p>
+
+
+<h3><span class="smcap">Post-Pliocene Formations.</span></h3>
+
+<p>I have adopted the term Post-Pliocene for those strata which are sometimes
+called post-tertiary or modern, and which are characterized <span class="pagenum"><a id="page112"></a>[p.112]</span>by
+having all the imbedded fossil shells identical with species now living,
+whereas even the Newer Pliocene, or newest of the tertiary deposits above
+alluded to, contain always some small proportion of shells of extinct
+species.</p>
+
+<p>These modern formations, thus defined, comprehend not only those strata
+which can be shown to have originated since the earth was inhabited by man,
+but also deposits of far greater extent and thickness, in which no signs of
+man or his works can be detected. In some of these, of a date long anterior
+to the times of history and tradition, the bones of extinct quadrupeds have
+been met with of species which probably never co-existed with the human
+race, as, for example, the mammoth, mastodon, megatherium, and others, and
+yet the shells are the same as those now living.</p>
+
+<p>That portion of the post-pliocene group which belongs to the human epoch,
+and which is sometimes called <i>Recent</i>, forms a very unimportant feature in
+the geological structure of the earth's crust. I have shown, however, in
+"The Principles," where the recent changes of the earth illustrative of
+geology are described at length, that the deposits accumulated at the
+bottom of lakes and seas within the last 4000 or 5000 years can neither be
+insignificant in volume or extent. They lie hidden, for the most part, from
+our sight; but we have opportunities of examining them at certain points
+where newly-gained land in the deltas of rivers has been cut through during
+floods, or where coral reefs are growing rapidly, or where the bed of a sea
+or lake has been heaved up by subterranean movements and laid dry. Their
+age may be recognized either by our finding in them the bones of man in a
+fossil state, that is to say, imbedded in them by natural causes, or by
+their containing articles fabricated by the hands of man.</p>
+
+<p>Thus at Puzzuoli, near Naples, marine strata are seen containing fragments
+of sculpture, pottery, and the remains of buildings, together with
+innumerable shells retaining in part their colour, and of the same species
+as those now inhabiting the Bay of Bai�. The uppermost of these beds is
+about 20 feet above the level of the sea. Their emergence can be proved to
+have taken place since the beginning of the sixteenth century.<a name="FNanchor_L_2" id="FNanchor_L_2"></a><a href="#Footnote_L_2" class="fnanchor">[112-A]</a> Now
+here, as in almost every instance where any alterations of level have been
+going on in historical periods, it is found that rocks containing shells,
+all, or nearly all, of which still inhabit the neighbouring sea, may be
+traced for some distance into the interior, and often to a considerable
+elevation above the level of the sea. Thus, in the country round Naples,
+the post-pliocene strata, consisting of clay and horizontal beds of
+volcanic tuff, rise at certain points to the height of 1500 feet. Although
+the marine shells are exclusively of living species, they are not
+accompanied like those on the coast at Puzzuoli by any traces of man or his
+works. Had any such been discovered, it would have afforded to the
+antiquary and geologist matter of great surprise, <span class="pagenum"><a id="page113"></a>[p.113]</span>since it would
+have shown that man was an inhabitant of that part of the globe, while the
+materials composing the present hills and plains of Campania were still in
+the progress of deposition at the bottom of the sea; whereas we know that
+for nearly 3000 years, or from the times of the earliest Greek colonists,
+no material revolution in the physical geography of that part of Italy has
+occurred.</p>
+
+<p>In Ischia, a small island near Naples, composed in like manner of marine
+and volcanic formations, Dr. Philippi collected in the stratified tuff and
+clay ninety-two species of shells of existing species. In the centre of
+Ischia, the lofty hill called Epomeo, or San Nicola, is composed of
+greenish indurated tuff, of a prodigious thickness, interstratified in some
+parts with marl, and here and there with great beds of solid lava. Visconti
+ascertained by trigonometrical measurement that this mountain was 2605 feet
+above the level of the sea. Not far from its summit, at the height of about
+2000 feet, as also near Moropano, a village only 100 feet lower, on the
+southern declivity of the mountain, I collected, in 1828, many shells of
+species now inhabiting the neighbouring gulf. It is clear, therefore, that
+the great mass of Epomeo was not only raised to its present height, but was
+also <i>formed</i> beneath the waters, within the post-pliocene period.</p>
+
+<p>It is a fact, however, of no small interest, that the fossil shells from
+these modern tuffs of the volcanic region surrounding the Bay of Bai�,
+although none of them extinct, indicate a slight want of correspondence
+between the ancient fauna and that now inhabiting the Mediterranean.
+Philippi informs us that when he and M. Scacchi had collected ninety-nine
+species of them, he found that only one, <i>Pecten medius</i>, now living in the
+Red Sea, was absent from the Mediterranean. Notwithstanding this, he adds,
+"the condition of the sea when the tufaceous beds were deposited must have
+been considerably different from its present state; for <i>Tellina striata</i>
+was then common, and is now rare; <i>Lucina spinosa</i> was both more abundant
+and grew to a larger size; <i>Lucina fragilis</i>, now rare, and hardly
+measuring 6 lines, then attained the enormous dimensions of 14 lines, and
+was extremely abundant; and <i>Ostrea lamellosa</i>, Broc., no longer met with
+near Naples, existed at that time, and attained a size so large that one
+lower valve has been known to measure 5 inches 9 lines in length, 4 inches
+in breadth, 1<span class="smaller"><sup>1</sup>/<sub>2</sub></span> inch in thickness, and weighed 26<span class="smaller"><sup>1</sup>/<sub>2</sub></span> ounces."<a name="FNanchor_L_3" id="FNanchor_L_3"></a><a href="#Footnote_L_3" class="fnanchor">[113-A]</a></p>
+
+<p>There are other parts of Europe where no volcanic action manifests itself
+at the surface, as at Naples, whether by the eruption of lava or by
+earthquakes, and yet where the land and bed of the adjoining sea are
+undergoing upheaval. The motion is so gradual as to be insensible to the
+inhabitants, being only ascertainable by careful scientific measurements
+compared after long intervals. Such an upward movement has been proved to
+be in progress in Norway and Sweden throughout an area about 1000 miles N.
+and S., and for an unknown distance E. and W., the amount of elevation
+always increasing as we <span class="pagenum"><a id="page114"></a>[p.114]</span>proceed towards the North Cape, where it
+may equal 5 feet in a century. If we could assume that there had been an
+average rise of 2<span class="smaller"><sup>1</sup>/<sub>2</sub></span> feet in each hundred years for the last fifty
+centuries, this would give an elevation of 125 feet in that period. In
+other words, it would follow that the shores, and a considerable area of
+the former bed of the Baltic and North Sea, had been uplifted vertically to
+that amount, and converted into land in the course of the last 5000 years.
+Accordingly, we find near Stockholm, in Sweden, horizontal beds of sand,
+loam, and marl containing the same peculiar assemblage of testacea which
+now live in the brackish waters of the Baltic. Mingled with these, at
+different depths, have been detected various works of art implying a rude
+state of civilization, and some vessels built before the introduction of
+iron, the whole marine formation having been upraised, so that the upper
+beds are now 60 feet higher than the surface of the Baltic. In the
+neighbourhood of these recent strata, both to the north-west and south of
+Stockholm, other deposits similar in mineral composition occur, which
+ascend to greater heights, in which precisely the same assemblage of fossil
+shells is met with, but without any intermixture of human bones or
+fabricated articles.</p>
+
+<p>On the opposite or western coast of Sweden, at Uddevalla, post-pliocene
+strata, containing recent shells, not of that brackish water character
+peculiar to the Baltic, but such as now live in the northern ocean, ascend
+to the height of 200 feet; and beds of clay and sand of the same age attain
+elevations of 300 and even 700 feet in Norway, where they have been usually
+described as "raised beaches." They are, however, thick deposits of
+submarine origin, spreading far and wide, and filling valleys in the
+granite and gneiss, just as the tertiary formations, in different parts of
+Europe, cover or fill depressions in the older rocks.</p>
+
+<p>It is worthy of remark, that although the fossil fauna characterizing these
+upraised sands and clays consists exclusively of existing northern species
+of testacea, yet, according to Lov�n (an able living naturalist of Norway),
+the species do not constitute such an assemblage as now inhabits
+corresponding latitudes in the German Ocean. On the contrary, they
+decidedly represent a more arctic fauna.<a name="FNanchor_L_4" id="FNanchor_L_4"></a><a href="#Footnote_L_4" class="fnanchor">[114-A]</a> In order to find the same
+species flourishing in equal abundance, or in many cases to find them at
+all, we must go northwards to higher latitudes than Uddevalla in Sweden, or
+even nearer the pole than Central Norway.</p>
+
+<p>Judging by the uniformity of climate now prevailing from century to
+century, and the insensible rate of variation in the organic world in our
+own times, we may presume that an extremely lengthened period was required
+even for so slight a modification of the molluscous fauna, as that of which
+the evidence is here brought to light. On the other hand, we have every
+reason for inferring on independent grounds (namely, the rate of upheaval
+of land in modern times) that the antiquity of the deposits in question
+must be very great. For if <span class="pagenum"><a id="page115"></a>[p.115]</span>we assume, as before suggested, that
+the mean rate of continuous vertical elevation has amounted to 2<span class="smaller"><sup>1</sup>/<sub>2</sub></span> feet
+in a century (and this is probably a high average), it would require 27,500
+years for the sea-coast to attain the height of 700 feet, without making
+allowance for any pauses such as are now experienced in a large part of
+Norway, or for any oscillations of level.</p>
+
+<p>In England, buried ships have been found in the ancient and now deserted
+channels of the Rother in Sussex, of the Mersey in Kent, and the Thames
+near London. Canoes and stone hatchets have been dug up, in almost all
+parts of the kingdom, from peat and shell-marl; but there is no evidence,
+as in Sweden, Italy, and many other parts of the world, of the bed of the
+sea, and the adjoining coast, having been uplifted bodily to considerable
+heights within the human period. Recent strata have been traced along the
+coasts of Peru and Chili, inclosing shells in abundance, all agreeing
+specifically with those now swarming in the Pacific. In one bed of this
+kind, in the island of San Lorenzo, near Lima, Mr. Darwin found, at the
+altitude of 85 feet above the sea, pieces of cotton-thread, plaited rush,
+and the head of a stalk of Indian corn, the whole of which had evidently
+been imbedded with the shells. At the same height on the neighbouring
+mainland, he found other signs corroborating the opinion that the ancient
+bed of the sea had there also been uplifted 85 feet, since the region was
+first peopled by the Peruvian race.<a name="FNanchor_L_5" id="FNanchor_L_5"></a><a href="#Footnote_L_5" class="fnanchor">[115-A]</a> But similar shelly masses are
+also met with at much higher elevations, at innumerable points between the
+Chilian and Peruvian Andes and the sea-coast, in which no human remains
+were ever, or in all probability ever will be, discovered.</p>
+
+<p>In the West Indies, also, in the island of Guadaloupe, a solid limestone
+occurs, at the level of the sea-beach, enveloping human skeletons. The
+stone is extremely hard, and chiefly composed of comminuted shell and
+coral, with here and there some entire corals and shells, of species now
+living in the adjacent ocean. With them are included arrow-heads, fragments
+of pottery, and other articles of human workmanship. A limestone with
+similar contents has been formed, and is still forming, in St. Domingo. But
+there are also more ancient rocks in the West Indian Archipelago, as in
+Cuba, near the Havanna, and in other islands, in which are shells identical
+with those now living in corresponding latitudes; some well-preserved,
+others in the state of casts, all referable to the post-pliocene period.</p>
+
+<p>I have already described in the seventh chapter, <a href="#page84">p. 84.</a>, what would be the
+effects of oscillations and changes of level in any region drained by a
+great river and its tributaries, supposing the area to be first depressed
+several hundred feet, and then re-elevated. I believe that such changes in
+the relative level of land and sea have actually occurred in the
+post-pliocene era in the hydrographical basin of the Mississippi and in
+that of the Rhine. The accumulation of fluviatile matter in a delta during
+a slow subsidence may raise the newly <span class="pagenum"><a id="page116"></a>[p.116]</span>gained land superficially
+at the same rate at which its foundations sink, so that these may go down
+hundreds or thousands of feet perpendicularly, and yet the sea bordering
+the delta may always be excluded, the whole deposit continuing to be
+terrestrial or freshwater in character. This appears to have happened in
+the deltas both of the Po and Ganges, for recent artesian borings,
+penetrating to the depth of 400 feet, have there shown that fluviatile
+strata, with shells of recent species, together with ancient surfaces of
+land supporting turf and forests, are depressed hundreds of feet below the
+sea level.<a name="FNanchor_L_6" id="FNanchor_L_6"></a><a href="#Footnote_L_6" class="fnanchor">[116-A]</a> Should these countries be once more slowly upraised, the
+rivers would carve out valleys through the horizontal and unconsolidated
+strata as they rose, sweeping away the greater portion of them, and leaving
+mere fragments in the shape of terraces skirting newly-formed alluvial
+plains, as monuments of the former levels at which the rivers ran. Of this
+nature are "the bluffs," or river cliffs, now bounding the valley of the
+Mississippi throughout a large portion of its course. Thus let <i>a b</i>, <a href="#img111">fig.
+106.</a>, represent the alluvial plain of the Mississippi, a plain which, at
+the point alluded to, is more than 30 miles broad, and is truly a
+prolongation of the modern delta of that river. It is bounded by bluffs,
+the upper portions of which consist, both on the east and west side, of
+shelly loam, No. 2. rising from 100 to 200 feet above the level of the
+plain, and containing land and freshwater shells of the genera <i>Helix</i>,
+<i>Pupa</i>, <i>Succinea</i>, and <i>Lymnea</i>, of the same species as those now
+inhabiting the neighbouring forests and swamps. In the same loam also, No.
+2., are found the bones of the Mastodon, Elephant, Megalonyx, and other
+extinct quadrupeds.</p>
+
+<a id="img111" name="img111"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 106.</p>
+<img src="images/img111.jpg" width="450" height="094" alt="" title="">
+<p>Valley of the Mississippi.</p>
+<ul class="smaller martopm05 leftal add2em">
+<li>1. Alluvium.</li>
+<li>2. Loess.</li>
+<li>3. <i>f</i>. Eocene.</li>
+<li>4. Cretaceous.</li>
+</ul></div>
+
+<p>I have endeavoured to show that the deposits forming the delta and alluvial
+plain of the Mississippi consist of sedimentary matter, extending over an
+area of 30,000 square miles, and known in some parts to be several hundred
+feet deep. Although we cannot estimate correctly how many years it may have
+required for the river to bring down from the upper country so large a
+quantity of earthy matter&mdash;the data for such a computation being as yet
+incomplete&mdash;we may still approximate to a minimum of the time which such an
+operation must have taken, by ascertaining experimentally the annual
+discharge of water by the Mississippi, and the mean annual amount of solid
+matter contained in its waters. The lowest estimate of the time required
+would lead us to assign a high antiquity, amounting to many tens of
+<span class="pagenum"><a id="page117"></a>[p.117]</span>thousands of years to the existing delta, the origin of which is
+nevertheless an event of yesterday when contrasted with those terraces,
+<i>c</i>, and <i>d e</i>, <a href="#img111">fig. 106.</a>, formed of the loam No. 2. above mentioned. These
+materials of the bluffs <i>a</i> and <i>d</i> were produced, the reader will observe,
+during the first part of that great oscillation of level which depressed to
+a depth of 200 feet a larger area than the modern delta and plain of the
+Mississippi, and then restored the region to its former position.<a name="FNanchor_L_7" id="FNanchor_L_7"></a><a href="#Footnote_L_7" class="fnanchor">[117-A]</a></p>
+
+<p><i>Loess of the Valley of the Rhine.</i>&mdash;A similar succession of geographical
+changes, attended by the production of a fluviatile formation, singularly
+resembling that which bounds the great plain of the Mississippi, seems to
+have occurred in the hydrographical basin of the Rhine, since the time when
+that basin had already acquired its present outline of hill and valley. I
+allude to the deposit provincially termed <i>loess</i> in part of Germany, or
+<i>lehm</i> in Alsace, filled with land and freshwater shells of existing
+species. It is a finely comminuted sand or pulverulent loam of a yellowish
+grey colour, consisting chiefly of argillaceous matter combined with a
+sixth part of carbonate of lime, and a sixth of quartzose and micaceous
+sand. It often contains calcareous sandy concretions or nodules, rarely
+exceeding the size of a man's head. Its entire thickness amounts, in some
+places, to between 200 and 300 feet; yet there are often no signs of
+stratification in the mass, except here and there at the bottom, where
+there is occasionally a slight intermixture of drifted materials derived
+from subjacent rocks. Unsolidified as it is, and of so perishable a nature,
+that every streamlet flowing over it cuts out for itself a deep gully, it
+usually terminates in a vertical cliff, from the surface of which land
+shells are seen here and there to project in relief. In all these features
+it presents a precise counterpart to the loess of the Mississippi. It is so
+homogeneous as generally to exhibit no signs of stratification, owing,
+probably, to its materials having been derived from a common source, and
+having been accumulated by a uniform action. Yet it displays in some few
+places decided marks of successive deposition, where coarser and finer
+materials alternate, especially near the bottom. Calcareous concretions,
+also enclosing land-shells, are sometimes arranged in horizontal layers. It
+is a remarkable deposit, from its position, wide extent, and thickness, its
+homogeneous mineral composition, and freshwater origin. Its distribution
+clearly shows that after the great valley of the Rhine, from Schaffhausen
+to Bonn, had acquired its present form, having its bottom strewed over with
+coarse gravel, a period arrived when it became filled up from side to side
+with fine mud, which was also thrown down in the valleys of the principal
+tributaries of the Rhine.</p>
+
+<p>Thus, for example, it may be traced far into W�rtemberg, up the valley of
+the Neckar, and from Frankfort, up the valley of the Main, to above
+Dettelbach. I have also seen it spreading over the country of Mayence,
+Eppelsheim, and Worms, on the left bank of the Rhine, and on the opposite
+side on the table-land above the Bergstrasse, between <span class="pagenum"><a id="page118"></a>[p.118]</span>Wiesloch
+and Bruchsal, where it attains a thickness of 200 feet. Near Strasburg,
+large masses of it appear at the foot of the Vosges on the left bank, and
+at the base of the mountains of the Black Forest on the right bank. The
+Kaiserstuhl, a volcanic mountain which stands in the middle of the plain of
+the Rhine near Freiburg, has been covered almost everywhere with this loam,
+as have the extinct volcanos between Coblentz and Bonn. Near Andernach, in
+the Kirchweg, the loess containing the usual shells alternates with
+volcanic matter; and over the whole are strewed layers of pumice, lapilli,
+and volcanic sand, from 10 to 15 feet thick, very much resembling the
+ejections under which Pompeii lies buried. There is no passage at this
+upper junction from the loess into the pumiceous superstratum; and this
+last follows the slope of the hill, just as it would have done had it
+fallen in showers from the air on a declivity partly formed of loess.</p>
+
+<p>But, in general, the loess overlies all the volcanic products, even those
+between Neuwied and Bonn, which have the most modern aspect; and it has
+filled up in part the crater of the Roderberg, an extinct volcano near
+Bonn. In 1833 a well was sunk at the bottom of this crater, through 70 feet
+of loess, in part of which were the usual calcareous concretions.</p>
+
+<p>The interstratification above alluded to, of loess with layers of pumice
+and volcanic ashes, has led to the opinion that both during and since its
+deposition some of the last volcanic eruptions of the Lower Eifel have
+taken place. Should such a conclusion be adopted, we should be called upon
+to assign a very modern date to these eruptions. This curious point,
+therefore, deserves to be reconsidered; since it may possibly have happened
+that the waters of the Rhine, swollen by the melting of snow and ice, and
+flowing at a great height through a valley choked up with loess, may have
+swept away the loose superficial scori� and pumice of the Eifel volcanos,
+and spread them out occasionally over the yellow loam. Sometimes, also, the
+melting of snow on the slope of small volcanic cones may have given rise to
+local floods, capable of sweeping down light pumice into the adjacent low
+grounds.</p>
+
+<p>The first idea which has occurred to most geologists, after examining the
+loess between Mayence and Basle, is to imagine that a great lake once
+extended throughout the valley of the Rhine between those two places. Such
+a lake may have sent off large branches up the course of the Main, Neckar,
+and other tributary valleys, in all of which large patches of loess are now
+seen. The barrier of the lake might be placed somewhere in the narrow and
+picturesque gorge of the Rhine between Bingen and Bonn. But this theory
+fails altogether to explain the phenomena; when we discover that that gorge
+itself has once been filled with loess, which must have been tranquilly
+deposited in it, as also in the lateral valley of the Lahn, communicating
+with the gorge. The loess has also overspread the high adjoining platform
+near the village of Plaidt above Andernach. Nay, on proceeding farther down
+to the north, we discover that the <span class="pagenum"><a id="page119"></a>[p.119]</span>hills which skirt the great
+valley between Bonn and Cologne have loess on their flanks, which also
+covers here and there the gravel of the plain as far as Cologne, and the
+nearest rising grounds.</p>
+
+<p>Besides these objections to the lake theory, the loess is met with near
+Basle, capping hills more than 1200 feet above the sea; so that a barrier
+of land capable of separating the supposed lake from the ocean would
+require to be, at least, as high as the mountains called the Siebengebirge,
+near Bonn, the loftiest summit of which, the Oehlberg, is 1209 feet above
+the Rhine and 1369 feet above the sea. It would be necessary, moreover, to
+place this lofty barrier somewhere below Cologne, or precisely where the
+level of the land is now lowest.</p>
+
+<p>Instead, therefore, of supposing one continuous lake of sufficient extent
+and depth to allow of the simultaneous accumulation of the loess, at
+various heights, throughout the whole area where it now occurs, I formerly
+suggested that, subsequently to the period when the countries now drained
+by the Rhine and its tributaries had nearly acquired their actual form and
+geographical features, they were again depressed gradually by a movement
+like that now in progress on the west coast of Greenland.<a name="FNanchor_L_8" id="FNanchor_L_8"></a><a href="#Footnote_L_8" class="fnanchor">[119-A]</a> In
+proportion as the whole district was lowered, the general fall of the
+waters between the Alps and the ocean was lessened; and both the main and
+lateral valleys, becoming more subject to river inundations, were partially
+filled up with fluviatile silt, containing land and freshwater shells. When
+a thickness of many hundred feet of loess had been thrown down slowly by
+this operation, the whole region was once more upheaved gradually. During
+this upward movement most of the fine loam would be carried off by the
+denuding power of rains and rivers; and thus the original valleys might
+have been re-excavated, and the country almost restored to its pristine
+state, with the exception of some masses and patches of loess such as still
+remain, and which, by their frequency and remarkable homogeneousness of
+composition and fossils, attest the ancient continuity and common origin of
+the whole. By imagining these oscillations of level, we dispense with the
+necessity of erecting and afterwards removing a mountain barrier
+sufficiently high to exclude the ocean from the valley of the Rhine during
+the period of the accumulation of the loess.</p>
+
+<p>The proportion of land shells of the genera <i>Helix</i>, <i>Pupa</i>, and <i>Bulimus</i>,
+is very large in the loess; but in many places aquatic species of the
+genera <i>Lymnea</i>, <i>Paludina</i>, and <i>Planorbis</i> are also found. These may have
+been carried away during floods from shallow pools and marshes bordering
+the river; and the great extent of marshy ground caused by the wide
+overflowings of rivers above supposed would favour the multiplication of
+amphibious mollusks, such as the <i>Succinea</i> (<a href="#img112">fig. 107.</a>), which is almost
+everywhere characteristic of this formation, and is sometimes accompanied,
+as near Bonn, by another species, <i>S. amphibia</i> (<a href="#img039">fig. 34.</a> <a href="#page29">p. 29.</a>). Among
+other abundant <span class="pagenum"><a id="page120"></a>[p.120]</span>fossils are <i>Helix plebeium</i> and <i>Pupa muscorum</i>.
+(See Figures.) Both the terrestrial and aquatic shells preserved in the
+loess are of most fragile and delicate structure, and yet they are almost
+invariably perfect and uninjured. They must have been broken to pieces had
+they been swept along by a violent inundation. Even the colour of some of
+the land shells, as that of <i>Helix nemoralis</i>, is occasionally preserved.</p>
+
+<a id="img112" name="img112"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 107.</p>
+<img src="images/img112.jpg" width="200" height="117" alt="" title="">
+<p><i>Succinea elongata.</i></p></div>
+
+<a id="img113" name="img113"></a>
+<div class="floatright smaller width200">
+<p>Fig. 108.</p>
+<img src="images/img113.jpg" width="200" height="145" alt="" title="">
+<p><i>Pupa muscorum.</i></p></div>
+
+<a id="img114" name="img114"></a>
+<div class="figcenter nofloat smaller width325">
+<p>Fig. 109.</p>
+<img src="images/img114.jpg" width="305" height="100" alt="" title="">
+<p><i>Helix plebeium.</i></p></div>
+
+<p>Bones of vertebrated animals are rare in the loess, but those of the
+mammoth, horse, and some other quadrupeds have been met with. At the
+village of Binningen, and the hills called Bruderholz, near Basle, I found
+the vertebr� of fish, together with the usual shells. These vertebr�,
+according to M. Agassiz, belong decidedly to the Shark family, perhaps to
+the genus <i>Lamna</i>. In explanation of their occurrence among land and
+freshwater shells, it may be stated that certain fish of this family ascend
+the Senegal, Amazon, and other great rivers, to the distance of several
+hundred miles from the ocean.<a name="FNanchor_L_9" id="FNanchor_L_9"></a><a href="#Footnote_L_9" class="fnanchor">[120-A]</a></p>
+
+<p>At Cannstadt, near Stuttgart, in a valley also belonging to the
+hydrographical basin of the Rhine, I have seen the loess pass downwards
+into beds of calcareous tuff and travertin. Several valleys in northern
+Germany, as that of the Ilm at Weimar, and that of the Tonna, north of
+Gotha, exhibit similar masses of modern limestone filled with recent shells
+of the genera <i>Planorbis</i>, <i>Lymnea</i>, <i>Paludina</i>, &amp;c., from 50 to 80 feet
+thick, with a bed of loess much resembling that of the Rhine, occasionally
+incumbent on them. In these modern limestones used for building, the bones
+of <i>Elephas primigenius</i>, <i>Rhinoceros tichorinus</i>, <i>Ursus spel�us</i>, <i>Hy�na
+spel�a</i>, with the horse, ox, deer, and other quadrupeds, occur; and in 1850
+Mr. H. Credner and I obtained in a quarry at Tonna, at the depth of 15
+feet, inclosed in the calcareous rock and surrounded with dicotyledonous
+leaves and petrified leaves, four eggs of a snake of the size of the
+largest European Coluber, which, with three others, had been found lying in
+a series, or string.</p>
+
+<p>They are, I believe, the first reptilian remains which have been met with
+in strata of this age.</p>
+
+<p>The agreement of the shells in these cases with recent European species
+enables us to refer to a very modern period the filling up and
+re-excavation of the valleys; an operation which doubtless consumed a long
+period of time, since which the mammiferous fauna has undergone a
+considerable change.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page121"></a>[p.121]</span>CHAPTER XI.</h2>
+
+<h4>NEWER PLIOCENE PERIOD.&mdash;BOULDER FORMATION.</h4>
+
+<div class="blq1">
+<p class="indentm2">Drift of Scandinavia, northern Germany, and Russia &mdash; Its northern
+origin &mdash; Not all of the same age &mdash; Fundamental rocks polished,
+grooved, and scratched &mdash; Action of glaciers and icebergs &mdash; Fossil
+shells of glacial period &mdash; Drift of eastern Norfolk &mdash; Associated
+freshwater deposit &mdash; Bent and folded strata lying on undisturbed
+beds &mdash; Shells on Moel Tryfane &mdash; Ancient glaciers of North
+Wales &mdash; Irish drift.</p></div>
+
+
+<p><span class="smcap">Among</span> the different kinds of alluvium described in the seventh chapter,
+mention was made of the boulder formation in the north of Europe, the
+peculiar characters of which may now be considered, as it belongs in part
+to the post-pliocene, and partly to the newer pliocene, period. I shall
+first allude briefly to that portion of it which extends from Finland and
+the Scandinavian mountains to the north of Russia, and the low countries
+bordering the Baltic, and which has been traced southwards as far as the
+eastern coast of England. This formation consists of mud, sand, and clay,
+sometimes stratified, but often wholly devoid of stratification, for a
+depth of more than a hundred feet. To this unstratified form of the
+deposit, the name of <i>till</i> has been applied in Scotland. It generally
+contains numerous fragments of rocks, some angular and others rounded,
+which have been derived from formations of all ages, both fossiliferous,
+volcanic, and hypogene, and which have often been brought from great
+distances. Some of the travelled blocks are of enormous size, several feet
+or yards in diameter; their average dimensions increasing as we advance
+northwards. The till is almost everywhere devoid of organic remains, unless
+where these have been washed into it from older formations; so that it is
+chiefly from relative position that we must hope to derive a knowledge of
+its age.</p>
+
+<p>Although a large proportion of the boulder deposit, or "northern drift," as
+it has sometimes been called, is made up of fragments brought from a
+distance, and which have sometimes travelled many hundred miles, the bulk
+of the mass in each locality consists of the ruins of subjacent or
+neighbouring rocks; so that it is red in a region of red sandstone, white
+in a chalk country, and grey or black in a district of coal and coal-shale.</p>
+
+<p>The fundamental rock on which the boulder formation reposes, if it consist
+of granite, gneiss, marble, or other hard stone capable of permanently
+retaining any superficial markings which may have been imprinted upon it,
+is smoothed or polished, and usually exhibits parallel stri� and furrows
+having a determinate direction. This direction, both in Europe and North
+America, is evidently connected with the course taken by the erratic blocks
+in the same district being north or south, or 20 or 30 degrees to the east
+or west of north, according as the large angular and rounded stones have
+travelled. <span class="pagenum"><a id="page122"></a>[p.122]</span>These stones themselves also are often furrowed and
+scratched on more than one side.</p>
+
+<a id="img115" name="img115"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 110.</p>
+<img src="images/img115.jpg" width="450" height="372" alt="" title="">
+<p>Limestone polished, furrowed, and scratched by the
+glacier of Rosenlaui, in <span class="wosp05">Switzerland. (Agassiz.)</span></p>
+<ul class="smaller martopm05 leftal min2em add2em">
+<li><i>a a.</i> White streaks or scratches, caused by small grains of flint frozen into the ice.</li>
+<li><i>b b.</i> Furrows.</li>
+</ul></div>
+
+<p>In explanation of such phenomena I may refer the student to what was said
+of the action of glaciers and icebergs in the Principles of Geology.<a name="FNanchor_M_1" id="FNanchor_M_1"></a><a href="#Footnote_M_1" class="fnanchor">[122-A]</a>
+It is ascertained that hard stones, frozen into a moving mass of ice, and
+pushed along under the pressure of that mass, scoop out long rectilinear
+furrows or grooves parallel to each other on the subjacent solid rock. (See
+<a href="#img115">fig. 110.</a>) Smaller scratches and stri� are made on the polished surface by
+crystals or projecting edges of the hardest minerals, just as a diamond
+cuts glass. The recent polishing and striation of limestone by coast-ice
+carrying boulders even as far south as the coast of Denmark, has been
+observed by Dr. Forchhammer, and helps us to conceive how large icebergs,
+running aground on the bed of the sea, may produce similar furrows on a
+grander scale. An account was given so long ago as the year 1822, by
+Scoresby, of icebergs seen by him drifting along in latitudes 69� and 70�
+N., which rose above the surface from 100 to 200 feet, and measured from a
+few yards to a mile in circumference. Many of them were loaded with beds of
+earth and rock, of such thickness that the weight was conjectured to be
+from 50,000 to 100,000 tons.<a name="FNanchor_M_2" id="FNanchor_M_2"></a><a href="#Footnote_M_2" class="fnanchor">[122-B]</a> A similar transportation of rocks is
+known to be in progress in the southern hemisphere, where boulders included
+in ice are far more frequent than in the north. One of these icebergs was
+encountered in 1839, in mid-ocean, in the antarctic regions, many hundred
+miles from any known land, sailing northwards, with a large erratic block
+<span class="pagenum"><a id="page123"></a>[p.123]</span>firmly frozen into it. In order to understand in what manner long
+and straight grooves may be cut by such agency, we must remember that these
+floating islands of ice have a singular steadiness of motion, in
+consequence of the larger portion of their bulk being sunk deep under
+water, so that they are not perceptibly moved by the winds and waves even
+in the strongest gales. Many had supposed that the magnitude commonly
+attributed to icebergs by unscientific navigators was exaggerated, but now
+it appears that the popular estimate of their dimensions has rather fallen
+within than beyond the truth. Many of them, carefully measured by the
+officers of the French exploring expedition of the Astrolabe, were between
+100 and 225 feet high above water, and from 2 to 5 miles in length. Captain
+d'Urville ascertained one of them which he saw floating in the Southern
+Ocean to be 13 miles long and 100 feet high, with walls perfectly vertical.
+The submerged portions of such islands must, according to the weight of ice
+relatively to sea-water, be from six to eight times more considerable than
+the part which is visible, so that the mechanical power they might exert
+when fairly set in motion must be prodigious.<a name="FNanchor_M_3" id="FNanchor_M_3"></a><a href="#Footnote_M_3" class="fnanchor">[123-A]</a></p>
+
+<p>Glaciers formed in mountainous regions become laden with mud and stones,
+and if they melt away at their lower extremity before they reach the sea,
+they leave wherever they terminate a confused heap of unstratified rubbish,
+called "a moraine," composed of mud and pieces of all the rocks with which
+they were loaded. We may expect, therefore, to find a formation of the same
+kind, resulting from the liquefaction of icebergs, in tranquil water. But,
+should the action of a current intervene at certain points or at certain
+seasons, then the materials will be sorted as they fall, and arranged in
+layers according to their relative weight and size. Hence there will be
+passages from <i>till</i>, as it is called in Scotland, to stratified clay,
+gravel, and sand, and intercalations of one in the other.</p>
+
+<p>I have yet to mention another appearance connected with the boulder
+formation, which has justly attracted much attention in Norway and other
+parts of Europe. Abrupt pinnacles and outstanding ridges of rock are often
+observed to be polished and furrowed on the north, or "strike" side as it
+is called, or on the side facing the region from which the erratics have
+come; while, on the other side, which is usually steeper and often
+perpendicular, called the "lee-side," such superficial markings are
+wanting. There is usually a collection on this lee-side of boulders and
+gravel, or of large angular fragments. In explanation we may suppose that
+the north side was exposed, when still submerged, to the action of
+icebergs, and afterwards, when the land was upheaved, of coast-ice, which
+ran aground upon shoals, or was <i>packed</i> on the beach; so that there would
+be great wear and tear on the seaward slope, while, on the other, gravel
+and boulders might be heaped up in a sheltered position.</p>
+
+<p><i>Northern origin of erratics.</i>&mdash;That the erratics of northern Europe
+<span class="pagenum"><a id="page124"></a>[p.124]</span>have been carried southward cannot be doubted; those of granite,
+for example, scattered over large districts of Russia and Poland, agree
+precisely in character with rocks of the mountains of Lapland and Finland;
+while the masses of gneiss, syenite, porphyry, and trap, strewed over the
+low sandy countries of Pomerania, Holstein, and Denmark, are identical in
+mineral characters with the mountains of Norway and Sweden.</p>
+
+<p>It is found to be a general rule in Russia, that the smaller blocks are
+carried to greater distances from their point of departure than the larger;
+the distance being sometimes 800 and even 1000 miles from the nearest rocks
+from which they were broken off; the direction having been from N.W. to
+S.E., or from the Scandinavian mountains over the seas and low lands to the
+south-east. That its accumulation throughout this area took place in part
+during the post-pliocene period is proved by its superposition at several
+points to strata containing recent shells. Thus, for example, in European
+Russia, MM. Murchison and De Verneuil found in 1840, that the flat country
+between St. Petersburg and Archangel, for a distance of 600 miles,
+consisted of horizontal strata, full of shells similar to those now
+inhabiting the arctic sea, on which rested the boulder formation,
+containing large erratics.</p>
+
+<p>In Sweden, in the immediate neighbourhood of Upsala, I observed, in 1834, a
+ridge of stratified sand and gravel, in the midst of which is a layer of
+marl, evidently formed originally at the bottom of the Baltic, by the slow
+growth of the mussel, cockle, and other marine shells, intermixed with some
+of freshwater species. The marine shells are all of dwarfish size, like
+those now inhabiting the brackish waters of the Baltic; and the marl, in
+which myriads of them are imbedded, is now raised more than 100 feet above
+the level of the Gulf of Bothnia. Upon the top of this ridge repose several
+huge erratics, consisting of gneiss for the most part unrounded, from 9 to
+16 feet in diameter, and which must have been brought into their present
+position since the time when the neighbouring gulf was already
+characterized by its peculiar fauna.<a name="FNanchor_M_4" id="FNanchor_M_4"></a><a href="#Footnote_M_4" class="fnanchor">[124-A]</a> Here, therefore, we have proof
+that the transport of erratics continued to take place, not merely when the
+sea was inhabited by the existing testacea, but when the north of Europe
+had already assumed that remarkable feature of its physical geography,
+which separates the Baltic from the North Sea, and causes the Gulf of
+Bothnia to have only one fourth of the saltness belonging to the ocean. In
+Denmark, also, recent shells have been found in stratified beds, closely
+associated with the boulder clay.</p>
+
+<p>It was stated that in Russia the erratics diminished generally in size in
+proportion as they are traced farther from their source. The same
+observation holds true in regard to the average bulk of the Scandinavian
+boulders, when we pursue them southwards, from the south of Norway and
+Sweden through Denmark and Westphalia. <span class="pagenum"><a id="page125"></a>[p.125]</span>This phenomenon is in
+perfect harmony with the theory of ice-islands floating in a sea of
+variable depth; for the heavier erratics require icebergs of a larger size
+to buoy them up; and, even when there are no stones frozen in, more than
+seven eighths, and often nine tenths, of a mass of drift ice is under
+water. The greater, therefore, the volume of the iceberg, the sooner would
+it impinge on some shallower part of the sea; while the smaller and lighter
+floes, laden with finer mud and gravel, may pass freely over the same
+banks, and be carried to much greater distances. In those places, also,
+where in the course of centuries blocks have been carried southwards by
+coast-ice, having been often stranded and again set afloat in the direction
+of a prevailing current, the blocks will be worn and diminish in size the
+farther they travel from their point of departure.</p>
+
+<p>The "northern drift" of the most southern latitudes is usually of the
+highest antiquity. In Scotland it rests immediately on the older rocks, and
+is covered by stratified sand and clay, usually devoid of fossils, but in
+which, at certain points near the east and west coast, as, for example, in
+the estuaries of the Tay and Clyde, marine shells have been discovered. The
+same shells have also been met with in the north, at Wick in Caithness, and
+on the shores of the Moray Frith. The principal deposit on the Clyde occurs
+at the height of about 70 feet, but a few shells have been traced in it as
+high as 554 feet above the sea. Although a proportion of between 85 or 90
+in 100 of the imbedded shells are of recent species, the remainder are
+unknown; and even many which are recent now inhabit more northern seas,
+where we may, perhaps, hereafter find living representatives of some of the
+unknown fossils. The distance to which erratic blocks have been carried
+southwards in Scotland, and the course they have taken, which is often
+wholly independent of the present position of hill and valley, favours the
+idea that ice-rafts rather than glaciers were in general the transporting
+agents. The Grampians in Forfarshire and in Perthshire are from 3000 to
+4000 feet high. To the southward lies the broad and deep valley of
+Strathmore, and to the south of this again rise the Sidlaw Hills<a name="FNanchor_M_5" id="FNanchor_M_5"></a><a href="#Footnote_M_5" class="fnanchor">[125-A]</a> to
+the height of 1500 feet and upwards. On the highest summits of this chain,
+formed of sandstone and shale, and at various elevations, are found huge
+angular fragments of mica schist, some 3 and others 15 feet in diameter,
+which have been conveyed for a distance of at least 15 miles from the
+nearest Grampian rocks from which they could have been detached. Others
+have been left strewed over the bottom of the large intervening vale of
+Strathmore.</p>
+
+<p>Still farther south on the Pentland Hills, at the height of 1100 feet above
+the sea, Mr. Maclaren has observed a fragment of mica-schist weighing from
+8 to 10 tons, the nearest mountain composed of this formation being 50
+miles distant.<a name="FNanchor_M_6" id="FNanchor_M_6"></a><a href="#Footnote_M_6" class="fnanchor">[125-B]</a></p>
+
+<p>The testaceous fauna of the boulder period, in Scotland, England, and
+Ireland, has been shown by Prof. E. Forbes to contain a much <span class="pagenum"><a id="page126"></a>[p.126]</span>
+smaller number of species than that now belonging to the British seas, and
+to have been also much less rich in species than the Older Pliocene fauna
+of the crag which preceded it. Yet the species are nearly all of them now
+living either in the British or more northern seas, the shells of more
+arctic latitudes being the most abundant and the most wide spread
+throughout the entire area of the drift from north to south.</p>
+
+<p>This extensive range of the fossils can by no means be explained by
+imagining the mollusca of the drift to have been inhabitants of a deep sea,
+where a more uniform temperature prevailed. On the contrary, many species
+were littoral, and others belonged to a shallow sea, not above 100 feet
+deep, and very few of them lived, according to Prof. E. Forbes, at greater
+depths than 300 feet.</p>
+
+<p>From what was before stated it will appear that the boulder formation
+displays almost everywhere, in its mineral ingredients, a strange
+heterogeneous mixture of the ruins of adjacent lands, with stones both
+angular and rounded, which have come from points often very remote. Thus we
+find it in our eastern counties, as in Norfolk, Suffolk, Cambridge,
+Huntingdon, Bedford, Hertford, Essex, and Middlesex, containing stones from
+the Silurian and Carboniferous strata, and from the lias, oolite, and
+chalk, all with their peculiar fossils, together with trap, syenite,
+mica-schist, granite, and other crystalline rocks. A fine example of this
+singular mixture extends to the very suburbs of London, being seen on the
+summit of Muswell Hill, Highgate. But south of London the northern drift is
+wanting, as, for example, in the Wealds of Surrey, Kent, and Sussex.</p>
+
+<p><i>Norfolk drift.</i>&mdash;The drift can nowhere be studied more advantageously in
+England than in the cliffs of the Norfolk coast between Happisburgh and
+Cromer. Vertical sections, having an ordinary height of from 50 to 70 feet,
+are there exposed to view for a distance of about 20 miles. The name of
+diluvium was formerly given to it by those who supposed it to have been
+produced by the violent action of a sudden and transient deluge, but the
+term drift has been substituted by those who reject this hypothesis. Here,
+as elsewhere, it consists for the most part of clay, loam, and sand, in
+part stratified, in part devoid of stratification. Pebbles, together with
+some large boulders of granite, porphyry, greenstone, lias, chalk, and
+other transported rocks, are interspersed, especially through the till.
+That some of the granitic and other fragments came from Scandinavia I have
+no doubt, after having myself traced the course of the continuous stream of
+blocks from Norway and Sweden to Denmark, and across the Elbe, through
+Westphalia, to the borders of Holland. We need not be surprised to find
+them reappear on our eastern coast, between the Tweed and the Thames,
+regions not half so remote from parts of Norway as are many Russian
+erratics from the sources whence they came.</p>
+
+<p>White chalk rubble, unmixed with foreign matter, and even huge fragments of
+solid chalk, also occur in many localities in these Norfolk cliffs. No
+fossils have been detected in this drift, which can positively <span class="pagenum"><a id="page127"></a>[p.127]</span>be
+referred to the era of its accumulation; but at some points it overlies a
+freshwater formation containing recent shells, and at others it is blended
+with the same in such a manner as to force us to conclude that both were
+contemporaneously deposited.</p>
+
+<a id="img116" name="img116"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 111.</p>
+<img src="images/img116.jpg" width="400" height="071" alt="" title="">
+<p>The shaded portion consists of Freshwater beds.
+Intercalation of freshwater beds and of boulder clay and sand at
+Mundesley.</p></div>
+
+<p>This interstratification is expressed in the annexed figure, the dark mass
+indicating the position of the freshwater beds, which contain much
+vegetable matter, and are divided into thin layers. The imbedded shells
+belong to the genera <i>Planorbis</i>, <i>Lymnea</i>, <i>Paludina</i>, <i>Unio</i>, <i>Cyclas</i>,
+and others, all of British species, except a minute <i>Paludina</i> now
+inhabiting France. (See <a href="#img117">fig. 112.</a>)</p>
+
+<a id="img117" name="img117"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 112.</p>
+<img src="images/img117.jpg" width="350" height="181" alt="" title="">
+<p><i>Paludina marginata</i>, Michaud. (<i>P. minuta</i>,
+Strickland.) The middle figure is of the natural size.</p></div>
+
+<p>The <i>Cyclas</i> (<a href="#img118">fig. 113.</a>) is merely a remarkable variety of the common
+English species. The scales and teeth of fish of the genera Pike, Perch,
+Roach, and others, accompany these shells; but the species are not
+considered by M. Agassiz to be identical with known British or European
+kinds.</p>
+
+<a id="img118" name="img118"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 113.</p>
+<img src="images/img118.jpg" width="350" height="107" alt="" title="">
+<p><i>Cyclas</i> (<i>Pisidium</i>) <i>amnica</i>, var.? The two
+middle figures are of the natural size.</p></div>
+
+<p>The series of formations in the cliffs of eastern Norfolk, now under
+consideration, beginning with the lowest, is as follows:&mdash;First, chalk;
+secondly, patches of a marine tertiary formation, called the Norwich Crag,
+hereafter to be described; thirdly, the freshwater beds already mentioned;
+and lastly, the drift. Immediately above the chalk, or crag, when that is
+present, is found here and there a buried forest, or a stratum in which the
+stools and roots of trees stand <span class="pagenum"><a id="page128"></a>[p.128]</span>in their natural position, the
+trunks having been broken short off and imbedded with their branches and
+leaves. It is very remarkable that the strata of the overlying boulder
+formation have often undergone great derangement at points where the
+subjacent forest bed and chalk remain undisturbed. There are also cases
+where the upper portion of the boulder deposit has been greatly deranged,
+while the lower beds of the same have continued horizontal. Thus the
+annexed section (<a href="#img119">fig. 114.</a>) represents a cliff about 50 feet high, at the
+bottom of which is <i>till</i>, or unstratified clay, containing boulders,
+having an even horizontal surface, on which repose conformably beds of
+laminated clay and sand about 5 feet thick, which, in their turn, are
+succeeded by vertical, bent, and contorted layers of sand and loam 20 feet
+thick, the whole being covered by flint gravel. Now the curves of the
+variously coloured beds of loose sand, loam, and pebbles are so complicated
+that not only may we sometimes find portions of them which maintain their
+verticality to a height of 10 or 15 feet, but they have also been folded
+upon themselves in such a manner that continuous layers might be thrice
+pierced in one perpendicular boring.</p>
+
+<a id="img119" name="img119"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 114.</p>
+<img src="images/img119.jpg" width="500" height="169" alt="" title="">
+<p>Cliff 50 feet high between Bacton Gap and Mundesley.</p></div>
+
+<a id="img120" name="img120"></a>
+<div class="figcenter smaller width200">
+<p class="martop2">Fig. 115.</p>
+<img src="images/img120.jpg" width="200" height="121" alt="" title="">
+<p>Folding of the strata between East and West Runton.</p></div>
+
+<a id="img121" name="img121"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 116.</p>
+<img src="images/img121.jpg" width="400" height="299" alt="" title="">
+<p>Section of concentric beds west of Cromer.</p>
+<ul class="smaller martopm05 leftal add1em">
+<li>1. Blue clay.</li>
+<li>2. White sand.</li>
+<li>3. Yellow Sand.</li>
+<li>4. Striped loam and clay.</li>
+<li>5. Laminated blue clay.</li>
+</ul></div>
+
+<p>At some points there is an apparent folding of the beds round a central
+nucleus, as at <i>a</i>, <a href="#img120">fig. 115.</a>, where the strata seem bent round a small
+mass of chalk; or, as in <a href="#img121">fig. 116.</a>, where the blue clay, No. 1., is in the
+centre; and where the other strata, 2, 3, 4, 5, are coiled <span class="pagenum"><a id="page129"></a>[p.129]</span>round
+it; the entire mass being 20 feet in perpendicular height. This appearance
+of concentric arrangement around a nucleus is, nevertheless, delusive,
+being produced by the intersection of beds bent into a convex shape; and
+that which seems the nucleus being, in fact, the innermost bed of the
+series, which has become partially visible by the removal of the
+protuberant portions of the outer layers.</p>
+
+<p>To the north of Cromer are other fine illustrations of contorted drift
+reposing on a floor of chalk horizontally stratified and having a level
+surface. These phenomena, in themselves sufficiently difficult of
+explanation, are rendered still more anomalous by the occasional inclosure
+in the drift of huge fragments of chalk many yards in diameter. One
+striking instance occurs west of Sherringham, where an enormous pinnacle of
+chalk, between 70 and 80 feet in height, is flanked on both sides by
+vertical layers of loam, clay, and gravel. (<a href="#img122">Fig. 117.</a>)</p>
+
+<a id="img122" name="img122"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 117.</p>
+<img src="images/img122.jpg" width="450" height="291" alt="" title="">
+<p>Included pinnacle of chalk at Old Hythe point,
+west of Sherringham.</p>
+<ul class="smaller martopm05 leftal min1em add2em">
+<li><i>d.</i> Chalk with regular layers of chalk flints.</li>
+<li><i>c.</i> Layer called "the pan," of loose chalk, flints, and marine shells of recent
+species, cemented by oxide of iron.</li>
+</ul></div>
+
+<p>This chalky fragment is only one of many detached masses which have been
+included in the drift, and forced along with it into their present
+position. The level surface of the chalk <i>in situ</i> (<i>d</i>) may be traced for
+miles along the coast, where it has escaped the violent movements to which
+the incumbent drift has been exposed.<a name="FNanchor_M_7" id="FNanchor_M_7"></a><a href="#Footnote_M_7" class="fnanchor">[129-A]</a></p>
+
+<p>We are called upon, then, to explain how any force can have been exerted
+against the upper masses, so as to produce movements in which the subjacent
+strata have not participated. It may be answered that, if we conceive the
+<i>till</i> and its boulders to have been drifted to their present place by ice,
+the lateral pressure may have been supplied by the stranding of
+ice-islands. We learn, from the observations of Messrs. Dease and Simpson
+in the polar regions, that such islands, when they run aground, push before
+them large mounds of shingle and sand. It is therefore probable that they
+often cause great alterations in the arrangement of pliant and incoherent
+strata forming <span class="pagenum"><a id="page130"></a>[p.130]</span>the upper part of shoals or submerged banks, the
+inferior portions of the same remaining unmoved. Or many of the complicated
+curvatures of these layers of loose sand and gravel may have been due to
+another cause, the melting on the spot of icebergs and coast ice in which
+successive deposits of pebbles, sand, ice, snow, and mud, together with
+huge masses of rock fallen from cliffs, may have become interstratified.
+Ice-islands so constituted often capsize when afloat, and gravel once
+horizontal may have assumed, before the associated ice was melted, an
+inclined or vertical position. The packing of ice forced up on a coast may
+lead to similar derangement in a frozen conglomerate of sand or shingle,
+and, as Mr. Trimmer has suggested<a name="FNanchor_M_8" id="FNanchor_M_8"></a><a href="#Footnote_M_8" class="fnanchor">[130-A]</a>, alternate layers of earthy matter
+may have sunk down slowly during the liquefaction of the intercalated ice,
+so as to assume the most fantastic and anomalous positions, while the
+aqueous strata below, and those afterwards thrown down above, may be
+perfectly horizontal.</p>
+
+<p>A buried forest has been adverted to as underlying the drift on the coast
+of Norfolk. At the time when the trees grew there must have been dry land
+over a large area, which was afterwards submerged, so as to allow a mass of
+stratified and unstratified drift, 200 feet and more in thickness, to be
+superimposed. The undermining of the cliffs by the sea in modern times has
+enabled us to demonstrate, beyond all doubt, the fact of this
+superposition, and that the forest was not formed along the present
+coast-line. Its situation implies a subsidence of several hundred feet
+since the commencement of the drift period, after which there must have
+been an upheaval of the same ground; for the forest bed of Norfolk is now
+again so high as to be exposed to view at many points at low water; and
+this same upward movement may explain why the <i>till</i>, which is conceived to
+have been of submarine origin, is now met with far inland, and on the
+summit of hills.</p>
+
+<p>The boulder formation of the west of England, observed in Lancashire,
+Cheshire, Shropshire, Staffordshire, and Worcestershire, contains in some
+places marine shells of recent species, rising to various heights, from 100
+to 350 feet above the sea. The erratics have come partly from the mountains
+of Cumberland, and partly from those of Scotland.</p>
+
+<p>But it is on the mountains of North Wales that the "Northern drift," with
+its characteristic marine fossils, reaches its greatest altitude. On Moel
+Tryfane, near the Menai Straits, Mr. Trimmer met with shells of the species
+commonly found in the drift at the height of 1392 feet above the level of
+the sea.</p>
+
+<p>It is remarkable that in the same neighbourhood where there is evidence of
+so great a submergence of the land during part of the glacial period, we
+have also the most decisive proofs yet discovered in the British Isles of
+subaerial glaciers. Dr. Buckland published in 1842 his reasons for
+believing that the Snowdonian mountains in Caernarvonshire were formerly
+covered with glaciers, which radiated from the central heights through the
+seven principal valleys <span class="pagenum"><a id="page131"></a>[p.131]</span>of that chain, where stri� and flutings
+are seen on the polished rocks directed towards as many different points of
+the compass. He also described the "moraines" of the ancient glaciers, and
+the rounded "bosses" or small flattened domes of polished rock, such as the
+action of moving glaciers is known to produce in Switzerland, when gravel,
+sand, and boulders, underlying the ice, are forced along over a foundation
+of hard stone. Mr. Darwin, and subsequently Prof. Ramsay, have confirmed
+Dr. Buckland's views in regard to these Welsh glaciers. Nor indeed was it
+to be expected that geologists should discover proofs of icebergs having
+abounded in the area now occupied by the British Isles in the Pleistocene
+period without sometimes meeting with the signs of contemporaneous glaciers
+which covered hills even of moderate elevation between the 50th and 60th
+degrees of latitude.</p>
+
+<p>In Ireland the "drift" exhibits the same general characters and fossil
+remains as in Scotland and England; but in the southern part of that
+island, Prof. E. Forbes and Capt. James found in it some shells which show
+that the glacial sea communicated with one inhabited by a more southern
+fauna. Among other species in the south, they mention at Wexford and
+elsewhere the occurrence of <i>Nucula Cobboldi�</i> (see <a href="#img125">fig. 120.</a> <a href="#page149">p. 149.</a>) and
+<i>Turritella incrassata</i> (a crag fossil); also a southern form of <i>Fusus</i>,
+and a <i>Mitra</i> allied to a Spanish species.<a name="FNanchor_M_9" id="FNanchor_M_9"></a><a href="#Footnote_M_9" class="fnanchor">[131-A]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XII.</h2>
+
+<h4>BOULDER FORMATION&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Difficulty of interpreting the phenomena of drift before the glacial
+hypothesis was adopted &mdash; Effects of intense cold in augmenting the
+quantity of alluvium &mdash; Analogy of erratics and scored rocks in North
+America and Europe &mdash; Bayfield on shells in drift of Canada &mdash; Great
+subsidence and re-elevation of land from the sea, required to account for
+glacial appearances &mdash; Why organic remains so rare in northern
+drift &mdash; Mastodon giganteus in United States &mdash; Many shells and some
+quadrupeds survived the glacial cold &mdash; Alps an independent centre of
+dispersion of erratics &mdash; Alpine blocks on the Jura &mdash; Whether
+transported by glaciers or floating ice &mdash; Recent transportation of
+erratics from the Andes to Chiloe &mdash; Meteorite in Asiatic drift.</p></div>
+
+
+<p><span class="smcap">It</span> will appear from what was said in the last chapter of the marine shells
+characterizing the boulder formation, that nine-tenths or more of them
+belong to species still living. The superficial position of "the drift" is
+in perfect accordance with its imbedded organic remains, leading us to
+refer its origin to a modern period. If, then, we encounter so much
+difficulty in the interpretation of monuments relating to times so near our
+own&mdash;if in spite of their recent date they are involved in so much
+obscurity&mdash;the student may ask, not without reasonable alarm, how we can
+hope to decipher the records of remote ages.</p>
+
+<p><span class="pagenum"><a id="page132"></a>[p.132]</span>To remove from the mind as far as possible this natural feeling of
+discouragement, I shall endeavour in this chapter to prove that what seems
+most strikingly anomalous, in the "erratic formation," as some call it, is
+really the result of that glacial action which has already been alluded to.
+If so, it was to be expected that so long as the true origin of so singular
+a deposit remained undiscovered, erroneous theories and terms would be
+invented in the effort to solve the problem. These inventions would
+inevitably retard the reception of more correct views which a wider field
+of observation might afterwards suggest.</p>
+
+<p>The term "diluvium" was for a time the popular name of the boulder
+formation, because it was referred by some geologists to the deluge. Others
+retained the name as expressive of their opinion that a series of diluvial
+waves raised by hurricanes and storms, or by earthquakes, or by the sudden
+upheaval of land from the bed of the sea, had swept over the continents,
+carrying with them vast masses of mud and heavy stones, and forcing these
+stones over rocky surfaces so as to polish and imprint upon them long
+furrows and stri�.</p>
+
+<p>But no explanation was offered why such agency should have been developed
+more energetically in modern times than at former periods of the earth's
+history, or why it should be displayed in its fullest intensity in northern
+latitudes; for it is important to insist on the fact, that the boulder
+formation is a <i>northern</i> phenomenon. Even the southern extension of the
+drift, or the large erratics found in the Alps and the surrounding lands,
+especially their occurrence round the highest parts of the chain, offers
+such an exception to the general rule as confirms the glacial hypothesis;
+for it shows that the transportation of stony fragments to great distances,
+and the striation, polishing, and grooving of solid floors of rock, are
+here again intimately connected with accumulations of perennial snow and
+ice.</p>
+
+<p>That there is some intimate connection between a cold or northern climate
+and the various geological appearances now commonly called glacial, cannot
+be doubted by any one who has compared the countries bordering the Baltic
+with those surrounding the Mediterranean. The smoothing and striation of
+rocks, and the erratics, are traced from the sea-shore to the height of
+3000 feet above the level of the Baltic, whereas such phenomena are wholly
+wanting in countries bordering the Mediterranean; and their absence is
+still more marked in the equatorial parts of Asia, Africa, and America; but
+when we cross the southern tropic, and reach Chili and Patagonia, we again
+encounter the boulder formation, between the latitude 41� S. and Cape Horn,
+with precisely the same characters which it assumes in Europe. The evidence
+as to climate derived from the organic remains of the drift is, as we have
+seen, in perfect harmony with the conclusions above alluded to, the former
+habits of the species of mollusca being accurately ascertainable, inasmuch
+as they belong to species still living, and known to have at present a wide
+range in northern seas.</p>
+
+<p>But if we are correct in assuming that the northern hemisphere was
+considerably colder than now during the period under consideration,
+<span class="pagenum"><a id="page133"></a>[p.133]</span>owing probably to the greater area and height of arctic lands,
+and to the quantity of icebergs which such a geographical state of things
+would generate, it may be well to reflect before we proceed farther on the
+entire modification which extreme cold would produce in the operation of
+those causes spoken of in the sixth chapter as most active in the formation
+of alluvium. A large part of the materials derived from the detritus of
+rocks, which in warm climates would go to form deltas, or would be
+regularly stratified by marine currents, would, under arctic influences,
+assume a superficial and alluvial character. Instead of mud being carried
+farther from a coast than sand, and sand farther out than pebbles,&mdash;instead
+of dense stratified masses being heaped up in limited areas,&mdash;nearly the
+whole materials, whether coarse or fine, would be conveyed by ice to equal
+distances, and huge fragments, which water alone could never move, would be
+borne for hundreds of miles without having their edges worn or fractured;
+and the earthy and stony masses, when melted out of the frozen rafts, would
+be scattered at random over the submarine bottom, whether on mountain tops
+or in low plains, with scarcely any relation to the inequalities of the
+ground, settling on the crests or ridges of hills in tranquil water as
+readily as in valleys and ravines. Occasionally, in those deep and
+uninhabited parts of the ocean, never reached by any but the finest
+sediment in a normal state of things, the bottom would become densely
+overspread by gravel, mud, and boulders.</p>
+
+<p>In the Western Hemisphere, both in Canada and as far south as the 40th and
+even 38th parallel of latitude in the United States, we meet with a
+repetition of all the peculiarities which distinguish the European boulder
+formation. Fragments of rock have travelled for great distances from north
+to south; the surface of the subjacent rock is smoothed, striated, and
+fluted; unstratified mud or <i>till</i> containing boulders is associated with
+strata of loam, sand, and clay, usually devoid of fossils. Where shells are
+present, they are of species still living in northern seas, and half of
+them identical with those already enumerated as belonging to European drift
+10 degrees of latitude farther north. The fauna also of the glacial epoch
+in North America is less rich in species than that now inhabiting the
+adjacent sea, whether in the Gulf of St. Lawrence, or off the shores of
+Maine, or in the Bay of Massachusetts. At the southern extremity of its
+course, moreover, it presents an analogy with the drift of the south of
+Ireland, by blending with a more southern fauna, as for example at Brooklyn
+near New York, in lat. 41� N., where, according to MM. Redfield and Desor,
+<i>Venus mercenaria</i> and other southern species of shells begin to occur as
+fossils in the drift.</p>
+
+<p>The extension on the American continent of the range of erratics during the
+Pleistocene period to lower latitudes than they reached in Europe, agrees
+well with the present southward deflection of the isothermal lines, or
+rather the lines of equal winter temperature. Formerly, as now, a more
+extreme climate and a more abundant supply of floating ice prevailed on the
+western side of the Atlantic.</p>
+
+<p><span class="pagenum"><a id="page134"></a>[p.134]</span>Another resemblance between the distribution of the drift fossils
+in Europe and North America has yet to be pointed out. In Norway, Sweden,
+and Scotland, as in Canada and the United States, the marine shells are
+confined to very moderate elevations above the sea (between 100 and 700
+feet), while the erratic blocks and the grooved and polished surfaces of
+rock extend to elevations of several thousand feet.</p>
+
+<a id="img123" name="img123"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 118.</p>
+<img src="images/img123.jpg" width="450" height="099" alt="" title="">
+<ul class="smaller leftal min1em add2em">
+<li>K. Mr. Ryland's house.</li>
+<li><i>h</i>. Clay and sand of higher grounds, with
+<i>Saxicava</i>, &amp;c.</li>
+<li><i>g</i>. Gravel with boulders.</li>
+<li><i>f</i>. Mass of <i>Saxicava rugosa</i>, 12 feet thick.</li>
+<li><i>e</i>. Sand and loam with <i>Mya truncata</i>, <i>Scalaria
+Gr&oelig;nlandica</i>, &amp;c.</li>
+<li><i>d</i>. Drift, with boulders of syenite, &amp;c.</li>
+<li><i>c</i>. Yellow sand.</li>
+<li><i>b</i>. Laminated clay, 25 feet thick.</li>
+<li>A. Horizontal lower Silurian strata.</li>
+<li>B. Valley re-excavated.</li>
+</ul></div>
+
+<p>I described in 1839 the fossil shells collected by Captain Bayfield from
+strata of drift at Beauport near Quebec, in lat. 47�, and drew from them
+the inference that they indicated a more northern climate, the shells
+agreeing in great part with those of Uddevalla in Sweden.<a name="FNanchor_N_1" id="FNanchor_N_1"></a><a href="#Footnote_N_1" class="fnanchor">[134-A]</a> The shelly
+beds attain at Beauport and the neighbourhood a height of 200, 300, and
+sometimes 400 feet above the sea, and dispersed through some of them are
+large boulders of granite, which could not have been propelled by a violent
+current, because the accompanying fragile shells are almost all entire.
+They seem, therefore, said Captain Bayfield, writing in 1838, to have been
+dropped down from melting ice, like similar stones which are now annually
+deposited in the St. Lawrence.<a name="FNanchor_N_2" id="FNanchor_N_2"></a><a href="#Footnote_N_2" class="fnanchor">[134-B]</a> I visited this locality in 1842, and
+made the annexed section, <a href="#img123">fig. 118.</a>, which will give an idea of the general
+position of the drift in Canada and the United States. I imagine that the
+whole of the valley B was once filled up with the beds <i>b</i>, <i>c</i>, <i>d</i>, <i>e</i>,
+<i>f</i>, which were deposited during a period of subsidence, and that
+subsequently the higher country (<i>h</i>) was submerged and overspread with
+drift. The partial re-excavation of B took place when this region was again
+uplifted above the sea to its present height. Among the twenty-three
+species of fossil shells collected by me from these beds at Beauport, all
+were of recent northern species, except one, which is unknown as living,
+and may be extinct (see <a href="#img124">fig. 119.</a>). I also examined the same formation
+farther up the valley of the St. Lawrence, in the suburbs of Montreal,
+where some of the beds of loam are filled with great numbers of the
+<i>Mytilus edulis</i>, or our common European mussel, retaining both its valves
+and purple colour. This shelly deposit, containing <i>Saxicava rugosa</i> and
+other characteristic marine shells, <span class="pagenum"><a id="page135"></a>[p.135]</span>also occurs at an elevated
+point on the mountain of Montreal, 450 feet above the level of the
+sea.<a name="FNanchor_N_3" id="FNanchor_N_3"></a><a href="#Footnote_N_3" class="fnanchor">[135-A]</a></p>
+
+<a id="img124" name="img124"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 119.</p>
+<img src="images/img124.jpg" width="350" height="099" alt="" title="">
+<p><i>Astarte Laurentiana.</i></p>
+<ul class="smaller martopm05 leftal add1em">
+<li><i>a.</i> Outside.</li>
+<li><i>b.</i> Inside of right valve.</li>
+<li><i>c.</i> Inside of left valve.</li>
+</ul></div>
+
+<p>In my account of Canada and the United States, published in 1845, I
+announced the conclusion to which I had then arrived, that to explain the
+position of the erratics and the polished surfaces of rocks, and their
+stri� and flutings, we must assume first a gradual submergence of the land
+in North America, after it had acquired its present outline of hill and
+valley, cliff and ravine, and then its re-emergence from the ocean. When
+the land was slowly sinking, the sea which bordered it was covered with
+islands of floating ice coming from the north, which, as they grounded on
+the coast and on shoals, pushed along such loose materials of sand and
+pebbles as lay strewed over the bottom. By this force all angular and
+projecting points were broken off, and fragments of hard stone, frozen into
+the lower surface of the ice, had power to scoop out grooves in the
+subjacent solid rock. The sloping beach, as well as the floor of the ocean,
+might be polished and scored by this machinery; but no flood of water,
+however violent, or however great the quantity of detritus or size of the
+rocky fragments swept along by it, could produce such long, perfectly
+straight and parallel furrows, as are everywhere visible in the Niagara
+district, and generally in the region north of the 40th parallel of
+latitude.<a name="FNanchor_N_4" id="FNanchor_N_4"></a><a href="#Footnote_N_4" class="fnanchor">[135-B]</a></p>
+
+<p>By the hypothesis of such a slow and gradual subsidence of the land we may
+account for the fact that almost everywhere in N. America and Northern
+Europe the boulder formation rests on a polished and furrowed surface of
+rock,&mdash;a fact by no means obliging us to imagine, as some think, that the
+polishing and grooving action was, as a whole, anterior in date to the
+transportation of the erratics. During the successive depression of high
+land, varying originally in height from 1000 to 3000 feet above the
+sea-level, every portion of the surface would be brought down by turns to
+the level of the ocean, so as to be converted first into a coast-line, and
+then into a shoal; and at length, after being well scored by the stranding
+upon it of thousands of icebergs, might be sunk to a depth of several
+hundred fathoms. By the constant depression of land, the coast would recede
+farther and farther from the successively formed zones of polished and
+striated rock, each outer zone becoming in its turn so deep under water as
+to be no longer grated upon by the heaviest icebergs. Such sunken areas
+would then simply serve as receptacles of mud, sand, and boulders dropped
+from melting ice, perhaps to a depth scarcely, if at <span class="pagenum"><a id="page136"></a>[p.136]</span>all,
+inhabited by testacea and zoophytes. Meanwhile, during the formation of the
+unstratified and unfossiliferous mass in deeper water, the smoothing and
+furrowing of shoals and beaches is still going on elsewhere upon and near
+the coast in full activity. If at length the subsidence should cease, and
+the direction of the movement of the earth's crust be reversed, the sunken
+area covered with drift would be slowly reconverted into land. The boulder
+deposit, before emerging, would then for a time be brought within the
+action of the waves, tides, and currents, so that its upper portion, being
+partially disturbed, would have its materials re-arranged and stratified.
+Streams also flowing from the land would in some places throw down layers
+of sediment upon the <i>till</i>. In that case, the order of superposition will
+be, first and uppermost, sand, loam, and gravel occasionally fossiliferous;
+secondly, an unstratified and unfossiliferous mass, for the most part of
+much older date than the preceding, with angular erratics, or with boulders
+interspersed; and, thirdly, beneath the whole, a surface of polished and
+furrowed rock. Such a succession of events seems to have prevailed very
+widely on both sides of the Atlantic, the travelled blocks having been
+carried in general from the North Pole southwards, but mountain chains
+having in some cases served as independent centres of dispersion, of which
+the Alps present the most conspicuous example.</p>
+
+<p>It is by no means rare to meet with boulders imbedded in drift which are
+worn flat on one or more of their sides, the surface being at the same time
+polished, furrowed, and striated. They may have been so shaped in a glacier
+before they reached the sea, or when they were fixed in the bottom of an
+iceberg as it ran aground. We learn from Mr. Charles Martins that the
+glaciers of Spitzbergen project from the coast into a sea between 100 and
+400 feet deep; and that numbers of striated pebbles or blocks are there
+seen to disengage themselves from the overhanging masses of ice as they
+melt, so as to fall at once into deep water.<a name="FNanchor_N_5" id="FNanchor_N_5"></a><a href="#Footnote_N_5" class="fnanchor">[136-A]</a></p>
+
+<p>That they should retain such markings when again upraised above the sea
+ought not to surprise us, when we remember that rippled sands, and the
+cracks in clay dried between high and low water, and the foot-tracks of
+animals and rain-drops impressed on mud, and other superficial markings,
+are all found fossil in rocks of various ages.</p>
+
+<p>On the other hand, it is not difficult to account for the absence in many
+districts of striated and scored pebbles and boulders in glacial deposits,
+for they may have been exposed to the action of the waves on a coast while
+it was sinking beneath or rising above the sea. No shingle on an ordinary
+sea-beach exhibits such stri�, and at a very short distance from the
+termination of a glacier every stone in the bed of the torrent which gushes
+out from the melting ice is found to have lost its glacial markings by
+being rolled for a distance even of a few hundred yards.</p>
+
+<p>The usual dearth of fossil shells in glacial clays well fitted to preserve
+<span class="pagenum"><a id="page137"></a>[p.137]</span>organic remains may, perhaps, be owing, as already hinted, to the
+absence of testacea in the deep sea, where the undisturbed accumulation of
+boulders melted out of very large bergs may take place. In the �gean and
+other parts of the Mediterranean, the zero of animal life, according to
+Prof. E. Forbes, is approached at a depth of about 300 fathoms. In tropical
+seas it would descend farther down, just as vegetation ascends higher on
+the mountains of hot countries. Near the pole, on the other hand, the same
+zero would be reached much sooner both on the hills and in the sea. If the
+ocean was filled with floating bergs, and a low temperature prevailed in
+the northern hemisphere during the glacial period, even the shallow part of
+the sea might have been uninhabitable, or very thinly peopled with living
+beings. It may also be remarked that the melting of ice in some fiords in
+Norway freshens the water so as to destroy marine life, and famines have
+been caused in Iceland by the stranding of icebergs drifted from the
+Greenland coast, which have required several years to melt, and have not
+only injured the hay harvest by cooling the atmosphere, but have driven
+away the fish from the shore by chilling and freshening the sea.</p>
+
+<p>If the cold of the glacial epoch came on slowly, if it was long before it
+reached its greatest intensity, and again if it abated gradually, we may
+expect to find the earliest and latest formed drift less barren of organic
+remains than that deposited during the coldest period. We may also expect
+that along the southern limits of the drift during the whole glacial epoch,
+there would be an intimate association of transported matter of northern
+origin with fossil-bearing sediment, whether marine or freshwater,
+belonging to more southern seas, rivers, and continents.</p>
+
+<p>That in the United States, the <i>Mastodon giganteus</i> was very abundant after
+the drift period is evident from the fact that entire skeletons of this
+animal are met with in bogs and lacustrine deposits occupying hollows in
+the drift. They sometimes occur in the bottom even of small ponds recently
+drained by the agriculturist for the sake of the shell marl. I examined one
+of these spots at Geneseo in the state of New York, from which the bones,
+skull, and tusk of a Mastodon had been procured in the marl below a layer
+of black peaty earth, and ascertained that all the associated freshwater
+and land shells were of a species now common in the same district. They
+consisted of several species of <i>Lymnea</i>, of <i>Planorbis bicarinatus</i>,
+<i>Physa heterostropha</i>, &amp;c.</p>
+
+<p>In 1845 no less than six skeletons of the same species of Mastodon were
+found in Warren County, New Jersey, 6 feet below the surface, by a farmer
+who was digging out the rich mud from a small pond which he had drained.
+Five of these skeletons were lying together, and a large part of the bones
+crumbled to pieces as soon as they were exposed to the air. But nearly the
+whole of the other skeleton, which lay about 10 feet apart from the rest,
+was preserved entire, and proved the correctness of Cuvier's conjecture
+respecting this extinct animal, namely, that it had twenty ribs like the
+living elephant. <span class="pagenum"><a id="page138"></a>[p.138]</span>From the clay in the interior within the ribs,
+just where the contents of the stomach might naturally have been looked
+for, seven bushels of vegetable matter were extracted. I submitted some of
+this matter to Mr. A. Henfrey of London for microscopic examination, and he
+informs me that it consists of pieces of small twigs of a coniferous tree
+of the Cypress family, probably the young shoots of the white cedar, <i>Thuja
+occidentalis</i>, still a native of North America, on which therefore we may
+conclude that this extinct Mastodon once fed.</p>
+
+<p>Another specimen of the same quadruped, the most complete and probably the
+largest ever found, was exhumed in 1845 in the town of Newburg, New York,
+the length of the skeleton being 25 feet, and its height 12 feet. The
+anchylosing of the last two ribs on the right side afforded Dr. John C.
+Warren a true gauge for the space occupied by the intervertebrate
+substance, so as to enable him to form a correct estimate of the entire
+length. The tusks when discovered were 10 feet long, but a part only could
+be preserved. The large proportion of animal matter in the tusk, teeth, and
+bones of some of these fossil mammalia is truly astonishing. It amounts in
+some cases, as Dr. C. T. Jackson has ascertained by analysis, to 27 per
+cent., so that when all the earthy ingredients are removed by acids, the
+form of the bone remains as perfect, and the mass of animal matter is
+almost as firm, as in a recent bone subjected to similar treatment.</p>
+
+<p>It would be rash, however, to infer from such data that these quadrupeds
+were mired in <i>modern</i> times, unless we use that term strictly in a
+geological sense. I have shown that there is a fluviatile deposit in the
+valley of the Niagara, containing shells of the genera <i>Melania</i>, <i>Lymnea</i>,
+<i>Planorbis</i>, <i>Valvata</i>, <i>Cyclas</i>, <i>Unio</i>, and <i>Helix</i>, &amp;c., all of recent
+species, from which the bones of the great Mastodon have been taken in a
+very perfect state. Yet the whole excavation of the ravine, for many miles
+below the Falls, has been slowly effected since that fluviatile deposit was
+thrown down.</p>
+
+<p>Whether or not, in assigning a period of more than 30,000 years for the
+recession of the Falls from Queenstown to their present site, I have over
+or under estimated the time required for that operation, no one can doubt
+that a vast number of centuries must have elapsed before so great a series
+of geographical changes were brought about as have occurred since the
+entombment of this elephantine quadruped. The freshwater gravel which
+incloses it is decidedly of much more modern origin than the drift or
+boulder clay of the same region.<a name="FNanchor_N_6" id="FNanchor_N_6"></a><a href="#Footnote_N_6" class="fnanchor">[138-A]</a></p>
+
+<p>Other extinct animals accompany the <i>Mastodon giganteus</i> in the
+post-glacial deposits of the United States, among which the <i>Castoroides
+ohioensis</i>, Foster and Wyman, a huge rodent allied to the beaver, and the
+<i>Capybara</i> may be mentioned. But whether the "loess," and other freshwater
+and marine strata of the Southern States, in which skeletons of the same
+Mastodon are mingled with the bones of the Megatherium, Mylodon, and
+Megalonyx, were contemporaneous with the drift, or were of subsequent date,
+is a chronological question still <span class="pagenum"><a id="page139"></a>[p.139]</span>open to discussion. It appears
+clear, however, from what we know of the tertiary fossils of Europe&mdash;and I
+believe the same will hold true in North America&mdash;that many species of
+testacea and some mammalia, which existed prior to the glacial epoch,
+survived that era. As European examples among the warm-blooded quadrupeds,
+the <i>Elephas primigenius</i> and <i>Rhinoceros tichorinus</i> may be mentioned. As
+to the shells, whether fresh water, terrestrial, or marine, they need not
+be enumerated here, as allusion will be made to them in the sequel, when
+the pliocene tertiary fossils of Suffolk are described. The fact is
+important, as refuting the hypothesis that the cold of the glacial period
+was so intense and universal as to annihilate all living creatures
+throughout the globe.</p>
+
+<p>That the cold was greater for a time than it is now in certain parts of
+Siberia, Europe, and North America, will not be disputed; but, before we
+can infer the universality of a colder climate, we must ascertain what was
+the condition of other parts of the northern, and of the whole southern,
+hemisphere at the time when the Scandinavian, British, and Alpine erratics
+were transported into their present position. It must not be forgotten that
+a great deposit of drift and erratic blocks is now in full progress of
+formation in the southern hemisphere, in a zone corresponding in latitude
+to the Baltic, and to Northern Italy, Switzerland, France, and England.
+Should the uneven bed of the southern ocean be hereafter converted by
+upheaval into land, the hills and valleys will be strewed over with
+transported fragments, some derived from the antarctic continent, others
+from islands covered with glaciers, like South Georgia, which must now be
+centres of the dispersion of drift, although situated in a latitude,
+agreeing with that of the Cumberland mountains in England.</p>
+
+<p>Not only are these operations going on between the 45th and 60th parallels
+of latitude south of the line, while the corresponding zone of Europe is
+free from ice; but, what is still more worthy of remark, we find in the
+southern hemisphere itself, only 900 miles distant from South Georgia,
+where the perpetual snow reaches to the sea-beach, lands covered with
+forests, as in Terra del Fuego. There is here no difference of latitude to
+account for the luxuriance of vegetation in one spot, and the absolute want
+of it in the other; but among other refrigerating causes in South Georgia
+may be enumerated the countless icebergs which float from the antarctic
+zone, and which chill, as they melt, the waters of the ocean, and the
+surrounding air, which they fill with dense fogs.</p>
+
+<p>I have endeavoured in the "Principles of Geology," chapters 7. and 8., to
+point out the intimate connexion of climate and the physical geography of
+the globe, and the dependence of the mean annual temperature, not only on
+the height of the dry land, but on its distribution in high or low
+latitudes at particular epochs. If, for example, at certain periods of the
+past, the antarctic land was less elevated and less extensive than now,
+while that at the north pole was higher and more continuous, the conditions
+of the northern and southern hemispheres might have been the reverse of
+what we <span class="pagenum"><a id="page140"></a>[p.140]</span>now witness in regard to climate, although the mountains
+of Scandinavia, Scotland, and Switzerland, may have been less elevated than
+at present. But if in both of the polar regions a considerable area of
+elevated dry land existed, such a concurrence of refrigerating conditions
+in both hemispheres might have created for a time an intensity of cold
+never experienced since; and such probably was the state of things during
+that period of submergence to which I have alluded in this chapter.</p>
+
+<p><i>Alpine erratics.</i>&mdash;Although the arctic regions constitute the great centre
+from which erratics have travelled southwards in all directions in Europe
+and North America, yet there are some mountains, as I have already stated,
+like those of North Wales and the Alps, which have served as separate and
+independent centres for the dispersion of blocks. In illustration of this
+fact, the Alps deserve particular attention, not only from their magnitude,
+but because they lie beyond the ordinary limits of the "northern drift" of
+Europe, being situated between the 44th and 47th degrees of north latitude.
+On the flanks of these mountains, and on the Subalpine ranges of hills or
+plains adjoining them, those appearances which have been so often alluded
+to, as distinguishing or accompanying the drift, between the 50th and 70th
+parallels of north latitude, suddenly reappear, to assume in a more
+southern country their most exaggerated form. Where the Alps are highest,
+the largest erratic blocks have been sent forth, as, for example, from the
+regions of Mont Blanc and Monte Rosa, into the adjoining parts of France,
+Switzerland, Austria, and Italy, while in districts where the great chain
+sinks in altitude, as in Carinthia, Carniola, and elsewhere, no such rocky
+fragments, or a few only and of smaller bulk, have been detached and
+transported to a distance.</p>
+
+<p>In the year 1821, M. Venetz first announced his opinion that the Alpine
+glaciers must formerly have extended far beyond their present limits, and
+the proofs appealed to by him in confirmation of this doctrine were
+afterwards acknowledged by M. Charpentier, who strengthened them by new
+observations and arguments, and declared, in 1836, his conviction that the
+glaciers of the Alps must once have reached as far as the Jura, and have
+carried thither their moraines across the great valley of Switzerland. M.
+Agassiz, after several excursions in the Alps with M. Charpentier, and
+after devoting himself some years to the study of glaciers, published, in
+1840, an admirable description of them, and of the marks which attest the
+former action of great masses of ice over the entire surface of the Alps
+and the surrounding country.<a name="FNanchor_N_7" id="FNanchor_N_7"></a><a href="#Footnote_N_7" class="fnanchor">[140-A]</a> He pointed out that the surface of
+every large glacier is strewed over with gravel and stones detached from
+the surrounding precipices by frost, rain, lightning, or avalanches. And he
+described more carefully than preceding writers the long lines of these
+stones, which settle on the sides of the glacier, and are called the
+lateral moraines; those found at the lower end of the ice being called
+terminal moraines. Such heaps of earth and boulders every <span class="pagenum"><a id="page141"></a>[p.141]</span>glacier
+pushes before it when advancing, and leaves behind it when retreating. When
+the Alpine glacier reaches a lower and warmer situation, about 3000 or 4000
+feet above the sea, it melts so rapidly that, in spite of the downward
+movement of the mass, it can advance no farther. Its precise limits are
+variable from year to year, and still more so from century to century; one
+example being on record of a recession of half a mile in a single year. We
+also learn from M. Venetz, that whereas, between the eleventh and fifteenth
+centuries, all the Alpine glaciers were less advanced than now, they began
+in the seventeenth and eighteenth centuries to push forward so as to cover
+roads formerly open, and to overwhelm forests of ancient growth.</p>
+
+<p>These oscillations enable the geologist to note the marks which they leave
+behind them as they retrograde, and among these the most prominent, as
+before stated, are the terminal moraines, or mounds of unstratified earth
+and stones, often divided by subsequent floods into hillocks, which cross
+the valley like ancient earth-works, or embankments made to dam up the
+river. Some of these transverse barriers were formerly pointed out by
+Saussure below the glacier of the Rhone, as proving how far it had once
+transgressed its present boundaries. On these moraines we see many large
+angular fragments, which, having been carried along on the surface of the
+ice, have not had their edges worn off by friction; but the greater number
+of the boulders, even those of large size, have been well rounded, not by
+the power of water, but by the mechanical force of the ice, which has
+pushed them against each other, or against the rocks flanking the valley.
+Others have fallen down the numerous fissures which intersect the glacier,
+where, being subject to the pressure of the whole mass of ice, they have
+been forced along, and either well rounded or ground down into sand, or
+even the finest mud, of which the moraine is largely constituted.</p>
+
+<p>As the terminal moraines are the most prominent of all the monuments left
+by a receding glacier, so are they the most liable to obliteration; for
+violent floods or debacles are often occasioned in the Alps by the sudden
+bursting of what are called glacier-lakes. These temporary sheets of water
+are caused by the damming up of a river by a glacier which has increased
+during a succession of cold seasons, and, descending from a tributary into
+the main valley, has crossed it from side to side. On the failure of this
+icy barrier, the accumulated waters are let loose, which sweep away and
+level all transverse mounds of gravel and loose boulder below, and spread
+their materials in confused and irregular beds over the river-plain.</p>
+
+<p>Another mark of the former action of glaciers, in situations where they
+exist no longer, is the polished, striated, and grooved surfaces of rocks
+already alluded to. Stones which lie underneath the glacier and are pushed
+along by it, sometimes adhere to the ice, and as the mass glides slowly
+along at the rate of a few inches, or at the utmost two or three feet, per
+day, abrade, groove, and polish the rock, and the larger blocks are
+reciprocally grooved and polished by the rock on their lower sides. As the
+forces both of pressure and propulsion <span class="pagenum"><a id="page142"></a>[p.142]</span>are enormous, the sand,
+acting like emery, polishes the surface; the pebbles, like coarse gravers,
+scratch and furrow it; and the large stones scoop out grooves in it.
+Another effect also of this action, not yet adverted to, is called "roches
+moutonn�es." Projecting eminences of rock are smoothed and worn into the
+shape of flattened domes, where the glaciers have passed over them.</p>
+
+<p>Although the surface of almost every kind of rock, when exposed in the open
+air, wastes away by decomposition, yet some retain for ages their polished
+and furrowed exterior; and, if they are well protected by a covering of
+clay or turf, these marks of abrasion seem capable of enduring for ever.
+They have been traced in the Alps to great heights above the present
+glaciers, and to great horizontal distances beyond them.</p>
+
+<p>There are also found, on the sides of the Swiss valleys, round and deep
+holes, with polished sides, such holes as waterfalls make in the solid
+rock, but in places remote from running waters, and where the form of the
+surface will not permit us to suppose that any cascade could ever have
+existed. Similar cavities are common in hard rocks, such as gneiss, in
+Sweden, where they are called <i>giant caldrons</i>, and are sometimes 10 feet
+and more in depth; but in the Alps and Jura they often pass into
+spoon-shaped excavations and prolonged gutters. We learn from M. Agassiz
+that hollows of this form are now cut out by streams of water, which flow
+along the surface of glaciers, and then fall into fissures which are open
+to the bottom. Here, forming a cascade, the stream cuts a round cavity in
+the rock with the gravel and sand, which it either finds there or carries
+down with it, and causes to rotate; and, as it usually happens that the
+glacier is advancing, a locomotive cascade is produced, which converts the
+first circular hole into a deep groove.</p>
+
+<p>Another effect of a glacier is to lodge a ring of stones round the summit
+of a conical peak which may happen to project through the ice. If the
+glacier is lowered greatly by melting, these circles of large angular
+fragments, which are called "perched blocks," are left in a singular
+situation near the top of a steep hill or pinnacle, the lower parts of
+which may be destitute of boulders.</p>
+
+<p><i>Alpine blocks on the Jura.</i>&mdash;Now some or all the marks above
+enumerated,&mdash;the moraines, erratics, polished surfaces, domes, stri�,
+caldrons, and perched rocks, are observed in the Alps at great heights
+above the present glaciers, and far below their actual extremities; also in
+the great valley of Switzerland, 50 miles broad; and almost everywhere on
+the Jura, a chain which lies to the north of this valley. The average
+height of the Jura is about one third that of the Alps, and is now entirely
+destitute of glaciers, yet it presents almost everywhere similar moraines,
+and the same polished and grooved surfaces, and water-worn cavities. The
+erratics, moreover, which cover it, present a phenomenon which has
+astonished and perplexed the geologist for more than half a century. No
+conclusion can be more incontestible than that these angular blocks of
+granite, gneiss, and other crystalline formations, came from the Alps, and
+that <span class="pagenum"><a id="page143"></a>[p.143]</span>they have been brought for a distance of 50 miles and
+upwards across one of the widest and deepest valleys of the world, so that
+they are now lodged on the hills and valleys of a chain composed of
+limestone and other formations, altogether distinct from those of the Alps.
+Their great size and angularity, after a journey of so many leagues, has
+justly excited wonder; for hundreds of them are as large as cottages; and
+one in particular, celebrated under the name of Pierre � Bot, rests on the
+side of a hill about 900 feet above the lake of Neufchatel, and is no less
+than 40 feet in diameter.</p>
+
+<p>It will be remarked that these blocks on the Jura offer an exception to the
+rule before laid down, as applicable in general to erratics, since they
+have gone from south to north. Some of the largest masses of granite and
+gneiss have been found to contain 50,000 and 60,000 cubic feet of stone,
+and one limestone block near Devens, which has travelled 30 miles, contains
+161,000 cubic feet, its angles being sharp and unworn.<a name="FNanchor_N_8" id="FNanchor_N_8"></a><a href="#Footnote_N_8" class="fnanchor">[143-A]</a></p>
+
+<p>Von Buch, Escher, and Studer have shown, from an examination of the mineral
+composition of the boulders, that those on the western Jura, near
+Neufchatel, have come from the region of Mont Blanc and the Valais; those
+on the middle parts of the Jura from the Bernese Oberland; and those on the
+eastern Jura from the Alps of the small cantons, Glaris, Schwytz, Uri, and
+Zug. The blocks, therefore, of these three great districts have been
+derived from parts of the Alps nearest to the localities in the Jura where
+we now find them, as if they had crossed the great valley in a direction at
+right angles to its length: the most western stream having followed the
+course of the Rhone; the central, that of the Aar; and the eastern, that of
+the two great rivers, Reuss and Limmat. The non-intermixture of these
+groups of travelled fragments, except near their confines, was always
+regarded as most enigmatical by those who adopted the opinion of Saussure,
+that they were all whirled along by a rapid current of muddy water rushing
+from the Alps.</p>
+
+<p>M. Charpentier first suggested, as before mentioned, that the Swiss
+glaciers once reached continuously to the Jura, and conveyed to them these
+erratics; but at the same time he conceived that the Alps were formerly
+higher than now. M. Agassiz, on the other hand, instead of introducing
+distinct and separate glaciers, imagines that the whole valley of
+Switzerland was filled with ice, and that one great sheet of it extended
+from the Alps to the Jura, when the two chains were of the same height as
+now relatively to each other. Such an hypothesis labours under this
+difficulty, that the difference of altitude, when distributed over a space
+of 50 miles, gives an inclination of no more than two degrees, or far less
+than that of any known glaciers. It has, however, since received the able
+support of Professor James Forbes, in his excellent work on the Alps,
+published in 1843.</p>
+
+<p>In the theory which I formerly advanced, jointly with Mr. Darwin<a name="FNanchor_N_9" id="FNanchor_N_9"></a><a href="#Footnote_N_9" class="fnanchor">[143-B]</a>,
+<span class="pagenum"><a id="page144"></a>[p.144]</span>it was suggested that the erratics may have been transferred by
+floating ice to the Jura, at the time when the greater part of that chain,
+and the whole of the Swiss valley to the south, was under the sea. At that
+period the Alps may have attained only half their present altitude, and may
+yet have constituted a chain as lofty as the Chilian Andes, which, in a
+latitude corresponding to Switzerland, now send down glaciers to the head
+of every sound, from which icebergs, covered with blocks of granite, are
+floated seaward.<a name="FNanchor_N_10" id="FNanchor_N_10"></a><a href="#Footnote_N_10" class="fnanchor">[144-A]</a> Opposite that part of Chili where the glaciers
+abound is situated the island of Chiloe, 100 miles in length, with a
+breadth of 30 miles, running parallel to the continent. The channel which
+separates it from the main land is of considerable depth, and 25 miles
+broad. Parts of its surface, like the adjacent coast of Chili, are
+overspread with recent marine shells, showing an upheaval of the land
+during a very modern period; and beneath these shells is a boulder deposit,
+in which Mr. Darwin found large travelled blocks. One group of fragments
+were of granite, which had evidently come from the Andes, while in another
+place angular blocks of syenite were met with. Their arrangement may have
+been due to successive crops of icebergs issuing from different sounds, to
+the heads of which glaciers descend from the Andes. These icebergs, taking
+their departure year after year from distinct points, may have been
+stranded repeatedly, in equally distinct groups, in bays or creeks of
+Chiloe, and on islets off the coast, so as afterwards to appear, some on
+hills and others in valleys, when that country and the bed of the adjacent
+sea had been upheaved. A continuance in future of the elevatory movement,
+in the region of the Andes and of Chiloe, might cause the former chain to
+rival the Alps in altitude, and give to Chiloe a height equal to that of
+the Jura. The same rise might dry up the channel between Chiloe and the
+main land, so that it would then represent the great valley of Switzerland.
+In the course of these changes, all parts of Chiloe and the intervening
+strait, having in their turn been a sea-shore, may have been polished and
+scratched by coast-ice, and by innumerable icebergs running aground and
+grating on the bottom.</p>
+
+<p>If we apply this hypothesis to Switzerland and the Jura, we are by no means
+precluded from the supposition that, in proportion as the land acquired
+additional height, and the bed of the sea emerged, the Jura itself may have
+had its glaciers; and those existing in the Alps, which had at first
+extended to the sea, may, during some part of the period of upheaval, have
+been prolonged much farther into the valleys than now. At a later period,
+when the climate grew milder, these glaciers may have entirely disappeared
+from the Jura, and may have receded in the Alps to their present limits,
+leaving behind them in both districts those moraines which now attest the
+former extension of the ice.<a name="FNanchor_N_11" id="FNanchor_N_11"></a><a href="#Footnote_N_11" class="fnanchor">[144-B]</a></p>
+
+<p><span class="pagenum"><a id="page145"></a>[p.145]</span><i>Meteorites in drift.</i>&mdash;Before concluding my remarks on the
+northern drift of the Old World, I shall refer to a fact recently
+announced, the discovery of a meteoric stone at a great depth in the
+alluvium of Northern Asia.</p>
+
+<p>Erman, in his Archives of Russia for 1841 (p. 314.), cites a very
+circumstantial account drawn up by a Russian miner of the finding of a mass
+of meteoric iron in the auriferous alluvium of the Altai. Some small
+fragments of native iron were first met with in the gold-washings of
+Petropawlowsker in the Mrassker Circle; but though they attracted
+attention, it was supposed that they must have been broken off from the
+tools of the workmen. At length, at the depth of 31 feet 5 inches from the
+surface, they dug out a piece of iron weighing 17<span class="smaller"><sup>1</sup>/<sub>2</sub></span> pounds, of a
+steel-grey colour, somewhat harder than ordinary iron, and, on analysing
+it, found it to consist of native iron, with a small proportion of nickel,
+as usual in meteoric stones. It was buried in the bottom of the deposit
+where the gravel rested on a flaggy limestone. Much brown iron ore, as well
+as gold, occurs in the same gravel, which appears to be part of that
+extensive auriferous formation in which the bones of the mammoth, the
+<i>Rhinoceros tichorhinus</i>, and other extinct quadrupeds abound. No
+sufficient data are supplied to enable us to determine whether it be of
+Post-Pliocene or Newer Pliocene date.</p>
+
+<p>We ought not, I think, to feel surprise that we have not hitherto succeeded
+in detecting the signs of such a�rolites in older rocks, for, besides their
+rarity in our own days, those which fell into the sea (and it is with
+marine strata that geologists have usually to deal), being chiefly composed
+of native iron, would rapidly enter into new chemical combinations, the
+water and mud being charged with chloride of sodium and other salts. We
+find that anchors, cannon, and other cast-iron implements which have been
+buried for a few hundred years off our English coast have decomposed in
+part or entirely, turning the sand and gravel which enclosed them into a
+conglomerate, cemented together by oxide of iron. In like manner meteoric
+iron, although its rusting would be somewhat checked by the alloy of
+nickel, could scarcely ever fail to decompose in the course of thousands of
+years, becoming oxide, sulphuret or carbonate of iron, and its origin being
+then no longer distinguishable. The greater the antiquity of rocks,&mdash;the
+oftener they have been heated and cooled, permeated by gases or by the
+waters of the sea, the atmosphere or mineral springs,&mdash;the smaller must be
+the chance of meeting with a mass of native iron unaltered; but the
+preservation of the ancient meteorite of the Altai, and the presence of
+nickel in these curious bodies, renders the recognition of them in deposits
+of remote periods less hopeless than we might have anticipated.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page146"></a>[p.146]</span>CHAPTER XIII.</h2>
+
+<h4>NEWER PLIOCENE STRATA AND CAVERN DEPOSITS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Chronological classification of Pleistocene formations, why
+difficult &mdash; Freshwater deposits in valley of Thames &mdash; In Norfolk
+cliffs &mdash; In Patagonia &mdash; Comparative longevity of species in the
+mammalia and testacea &mdash; Fluvio-marine crag of Norwich &mdash; Newer
+Pliocene strata of Sicily &mdash; Limestone of great thickness and
+elevation &mdash; Alternation of marine and volcanic formations &mdash; Proofs
+of slow accumulation&mdash;Great geographical changes in Sicily since the
+living fauna and flora began to exist &mdash; Osseous breccias and cavern
+deposits &mdash; Sicily &mdash; Kirkdale &mdash; Origin of
+stalactite &mdash; Australian cave-breccias &mdash; Geographical relationship
+of the provinces of living vertebrata and those of the fossil species of
+the Pliocene periods &mdash; Extinct struthious birds of New
+Zealand &mdash; Teeth of fossil quadrupeds.</p></div>
+
+
+<p><span class="smcap">Having</span> in the last chapter treated of the boulder formation and its
+associated freshwater and marine strata as belonging chiefly to the close
+of the Newer Pliocene period, we may now proceed to other deposits of the
+same or nearly the same age. It should, however, be stated that it is
+difficult to draw the line of separation between these modern formations,
+especially when we are called upon to compare deposits of marine and
+freshwater origin, or these again with the ossiferous contents of caverns.</p>
+
+<p>If as often as the carcasses of quadrupeds were buried in alluvium during
+floods, or mired in swamps, or imbedded in lacustrine strata, a stream of
+lava had descended and preserved the alluvial or freshwater deposits, as
+frequently happened in Auvergne (see above, <a href="#page80">p. 80.</a>), keeping them free from
+intermixture with strata subsequently formed, then indeed the task of
+arranging chronologically the whole series of mammaliferous formations
+might have been easy, even though many species were common to several
+successive groups. But when there have been oscillations in the levels of
+the land, accompanied by the widening and deepening of valleys at more than
+one period,&mdash;when the same surface has sometimes been submerged beneath the
+sea, after supporting forests and land quadrupeds, and then raised again,
+and subject during each change of level to sedimentary deposition and
+partial denudation,&mdash;and when the drifting of ice by marine currents or by
+rivers, during an epoch of intense cold, has for a season interfered with
+the ordinary mode of transport, or with the geographical range of species,
+we cannot hope speedily to extricate ourselves from the confusion in which
+the classification of these Pleistocene formations is involved.</p>
+
+<p>At several points in the valley of the Thames, remnants of ancient
+fluviatile deposits occur, which may differ considerably in age, although
+the imbedded land and freshwater shells in each are of recent species. At
+Brentford, for example, the bones of the Siberian Mammoth, <span class="pagenum"><a id="page147"></a>[p.147]</span>or
+<i>Elephas primigenius</i>, and the <i>Rhinoceros tichorhinus</i>, both of them
+quadrupeds of which the flesh and hair have been found preserved in the
+frozen soil of Siberia, occur abundantly, with the bones of an
+hippopotamus, aurochs, short-horned ox, red deer, rein-deer, and great
+cave-tiger or lion.<a name="FNanchor_O_1" id="FNanchor_O_1"></a><a href="#Footnote_O_1" class="fnanchor">[147-A]</a> A similar group has been found fossil at
+Maidstone, in Kent, and other places, agreeing in general specifically with
+the fossil bones detected in the caverns of England. When we see the
+existing rein-deer and an extinct hippopotamus in the same fluviatile loam,
+we are tempted to indulge our imaginations in speculating on the climatal
+conditions which could have enabled these genera to co-exist in the same
+region. Wherever there is a continuity of land from polar to temperate and
+equatorial regions, there will always be points where the southern limit of
+an arctic species meets the northern range of a southern species; and if
+one or both have migratory habits, like the Bengal tiger, the American
+bison, the musk ox, and others, they may each penetrate mutually far into
+the respective provinces of the other. There may also have been several
+oscillations of temperature during the periods which immediately preceded
+and followed the more intense cold of the glacial epoch.</p>
+
+<p>The strata bordering the left bank of the Thames at Grays Thurrock, in
+Essex, are probably of older date than those of Brentford, although the
+associated land and freshwater shells are nearly all, if not all, identical
+with species now living. Three of the shells, however, are no longer
+inhabitants of Great Britain; namely, <i>Paludina marginata</i> (<a href="#img117">fig. 112.</a> <a href="#page127">p.
+127.</a>), now living in France; <i>Unio littoralis</i> (<a href="#img034">fig. 29.</a> <a href="#page28">p. 28.</a>), now
+inhabiting the Loire; and <i>Cyrena consobrina</i> (<a href="#img031">fig. 26.</a> <a href="#page28">p. 28.</a>). The
+last-mentioned fossil (a recent Egyptian shell of the Nile) is very
+abundant at Grays, and deserves notice, because the genus <i>Cyrena</i> is now
+no longer European.</p>
+
+<p>The rhinoceros occurring in the same beds (<i>R. leptorhinus</i>, see <a href="#img136">fig. 131.</a>
+<a href="#page160">p. 160.</a>) is of a different species from that of Brentford above mentioned,
+and the accompanying elephant belongs to the variety called <i>Elephas
+meridionalis</i>, which, according to MM. Owen and H. von Meyer, two high
+authorities, is the same species as the Siberian mammoth, although some
+naturalists regard it as distinct. With the above mammalia is also found
+the <i>Hippopotamus major</i>, and what is most remarkable in so modern and
+northern a deposit, a monkey, called by Owen, <i>Macacus pliocenus</i>.</p>
+
+<p>The submerged forest already alluded to (<a href="#page130">p. 130.</a>) as underlying the drift
+at the base of the cliffs of Norfolk is associated with a bed of lignite
+and loam, in which a great number of fossil bones occur, apparently of the
+same group as that of Grays, just mentioned. It has sometimes been called
+"the Elephant bed." One portion of it, which stretches out under the sea at
+Happisburgh, was overgrown in 1820 by a bank of recent oysters, and there
+the fishermen dredged up, according to Woodward, in the course of thirteen
+years, together with the oysters, above 2000 mammoths' grinders.<a name="FNanchor_O_2" id="FNanchor_O_2"></a><a href="#Footnote_O_2" class="fnanchor">[147-B]</a>
+Another portion <span class="pagenum"><a id="page148"></a>[p.148]</span>of the same continuous stratum has yielded at
+Bacton, Cromer, and other places on the coast, the bones of a gigantic
+beaver (<i>Trogontherium Cuvierii</i>, Fischer), as well as the ox, horse, and
+deer, and both species of rhinoceros, <i>R. tichorhinus</i> and <i>R.
+leptorhinus</i>.</p>
+
+<p>In studying these and various other similar assemblages of fossils, we have
+a good exemplification of the more rapid rate at which the mammiferous
+fauna, as compared to the testaceous, diverges when traced backwards in
+time from the recent type. I have before hinted, that the longevity of
+species in the class of warm-blooded quadrupeds is less great than in that
+of the mollusca, the latter having probably more capacity for enduring
+those changes of climate and other external circumstances which take place
+in the course of ages on the earth's surface. This phenomenon is by no
+means confined to Europe, for Mr. Darwin found at Bahia Blanca, in South
+America, lat. 39� S., near the northern confines of Patagonia, fossil
+remains of the extinct mammiferous genera Megatherium, Megalonyx, Toxodon,
+and others, associated with shells, almost all of species already
+ascertained to be still living in the contiguous sea<a name="FNanchor_O_3" id="FNanchor_O_3"></a><a href="#Footnote_O_3" class="fnanchor">[148-A]</a>; the marine
+mollusca, as well as those of rivers, lakes, or the land, having died out
+more slowly than the terrestrial mammalia.</p>
+
+<p>I alluded before (<a href="#page125">p. 125.</a>) to certain marine strata overlying till near
+Glasgow, and at other points on the Clyde, in which the shells are for the
+most part British, with an intermixture of some arctic species; while
+others, about a tenth of the whole, are supposed to be extinct. This
+formation may also be called Newer Pliocene.</p>
+
+<p><i>Fluvio-marine crag of Norwich.</i>&mdash;At several places within five miles of
+Norwich, on both banks of the Yare, beds of sand, loam, and gravel,
+provincially termed "crag," occur, in which there is a mixture of marine,
+land, and freshwater shells, with ichthyolites and bones of mammalia. It is
+clear that these beds have been accumulated at the bottom of the sea near
+the mouth of a river. They form patches of variable thickness, resting on
+white chalk, and are covered by a dense mass of stratified flint gravel.
+The surface of the chalk is often perforated to the depth of several inches
+by the <i>Pholas crispata</i>, each fossil shell still remaining at the bottom
+of its cylindrical cavity, now filled up with loose sand which has fallen
+from the incumbent crag. This species of Pholas still exists and drills the
+rocks between high and low water on the British coast. The most common
+shells of these strata, such as <i>Fusus striatus</i>, <i>Turritella terebra</i>,
+<i>Cardium edule</i>, and <i>Cyprina islandica</i>, are now abundant in the British
+seas; but with them are some extinct species, such as <i>Nucula Cobboldi�</i>
+(<a href="#img125">fig. 120.</a>) and <i>Tellina obliqua</i> (<a href="#img126">fig. 121.</a>). <i>Natica helicoides</i> (<a href="#img127">fig.
+122.</a>) is an example of a species formerly known only as fossil, but which
+has now been found living in our seas.</p>
+
+<p>Among the accompanying bones of mammalia is the <i>Mastodon</i> <span class="pagenum"><a id="page149"></a>[p.149]</span>
+<i>angustidens</i><a name="FNanchor_O_4" id="FNanchor_O_4"></a><a href="#Footnote_O_4" class="fnanchor">[149-A]</a> (see <a href="#img135">fig. 130.</a>), a portion of the upper jawbone with a
+tooth having been found by Mr. Wigham at Postwick, near Norwich. As this
+species has also been found in the Red Crag, both at Sutton and at
+Felixstow, and had hitherto been regarded as characteristic of formations
+older than the Pleistocene, it may possibly have been washed out of the Red
+into the Norwich Crag.</p>
+
+<a id="img125" name="img125"></a>
+<div class="figcenter smaller">
+<p>Fig. 120.</p>
+<img src="images/img125.jpg" width="484" height="200" alt="" title="">
+<p><i>Nucula Cobboldi�.</i></p></div>
+
+<a id="img126" name="img126"></a>
+<div class="floatleft smaller">
+<p>Fig. 121.</p>
+<img src="images/img126.jpg" width="250" height="229" alt="" title="">
+<p><i>Tellina obliqua.</i></p></div>
+
+<a id="img127" name="img127"></a>
+<div class="floatright smaller width225">
+<p>Fig. 122.</p>
+<img src="images/img127.jpg" width="210" height="275" alt="" title="">
+<p><i>Natica helicoides</i>, Johnston.</p></div>
+
+<p class="nofloat">Among the bones, however, respecting the authenticity of which there seems
+no doubt, may be mentioned those of the elephant, horse, pig, deer, and the
+jaws and teeth of field mice (<a href="#img146">fig. 141.</a>). I have seen the tusk of an
+elephant from Bramerton near Norwich, to which, many serpul� were attached,
+showing that it had lain for some time at the bottom of the sea of the
+Norwich Crag.</p>
+
+<p>At Thorpe, near Aldborough, and at Southwold, in Suffolk, this
+fluvio-marine formation is well exposed in the sea-cliffs, consisting of
+sand, shingle, loam, and laminated clay. Some of the strata there bear the
+marks of tranquil deposition, and in one section a thickness of 40 feet is
+sometimes exposed to view. Some of the lamellibranchiate shells have both
+valves united, although mixed with land and freshwater testacea, and with
+the bones and teeth of elephant, rhinoceros, horse, and deer. Captain
+Alexander, with whom I examined these strata in 1835, showed me a bed rich
+in marine shells, in which he had found a large specimen of the <i>Fusus
+striatus</i>, filled with sand, and in the interior of which was the tooth of
+a horse.</p>
+
+<p>Among the freshwater shells I obtained the <i>Cyrena consobrina</i> (<a href="#img031">fig. 26.</a> <a href="#page28">p.
+28.</a>), before mentioned, supposed to agree with a species now living in the
+Nile.</p>
+
+<p>I formerly classed the Norwich Crag as older Pliocene, conceiving that more
+than a third of the fossil testacea were extinct; but there now seems good
+reason for believing that several of the rarer shells obtained from these
+strata do not really belong to a contemporary fauna, but have been washed
+out of the older beds of the "Red Crag;" while other species, once supposed
+to have died out, have lately been met with living in the British seas.
+According to Mr. Searles Wood, the total number of marine species does not
+exceed seventy-six, of which one tenth only are extinct. Of the fourteen
+associated freshwater shells, all the species appear to be living. Strata
+containing the same shells as those near Norwich have been found by Mr.
+Bean, at Bridlington, in Yorkshire.</p>
+
+<p><i>Newer Pliocene strata of Sicily.</i>&mdash;In no part of Europe are the <span class="pagenum"><a id="page150"></a>[p.150]</span>
+Newer Pliocene formations seen to enter so largely into the structure of
+the earth's crust, or to rise to such heights above the level of the sea,
+as in Sicily. They cover nearly half the island, and near its centre, at
+Castrogiovanni, they reach an elevation of 3000 feet. They consist
+principally of two divisions, the upper calcareous, the lower argillaceous,
+both of which may be seen at Syracuse, Girgenti, and Castrogiovanni.</p>
+
+<p>According to Philippi, to whom we are indebted for the best account of the
+tertiary shells of this island, thirty-five species out of one hundred and
+twenty-four obtained from the beds in central Sicily are extinct. Of the
+remainder, which still live, five species are no longer inhabitants of the
+Mediterranean. When I visited Sicily in 1828 I estimated the proportion of
+living species as somewhat greater, partly because I confounded with the
+tertiary formation of central Sicily the strata at the base of Etna, and
+some other localities, where the fossils are now proved to agree entirely
+with the present Mediterranean fauna.</p>
+
+<p>Philippi came to the conclusion, that in Sicily there is a gradual passage
+from beds containing 70 per cent. of recent shells, to those in which the
+whole of the fossils are identical with recent species; but his tables
+appear scarcely to bear out so important a generalization, several of the
+places cited by him in confirmation having as yet furnished no more than
+twenty or thirty species of testacea. The Sicilian beds in question
+probably belong to about the same period as the Norwich Crag, although a
+geologist, accustomed to see nearly all the Pleistocene formations in the
+north of Europe occupying low grounds and very incoherent in texture, is
+naturally surprised to behold formations of the same age so solid and
+stony, of such thickness, and attaining so great an elevation above the
+level of the sea.</p>
+
+<p>The upper or calcareous member of this group in Sicily consists in some
+places of a yellowish-white stone, like the calcaire grossier of Paris, in
+others, of a rock nearly as compact as marble. Its aggregate thickness
+amounts sometimes to 700 or 800 feet. It usually occurs in regular
+horizontal beds, and is occasionally intersected by deep valleys, such as
+those of Sortino and Pentalica, in which are numerous caverns. The fossils
+are in every stage of preservation, from shells retaining portions of their
+animal matter and colour, to others which are mere casts.</p>
+
+<p>The limestone passes downwards into a sandstone and conglomerate, below
+which is clay and blue marl, like that of the Subapennine hills, from which
+perfect shells and corals may be disengaged. The clay sometimes alternates
+with yellow sand.</p>
+
+<p>South of the plain of Catania is a region in which the tertiary beds are
+intermixed with volcanic matter, which has been for the most part the
+product of submarine eruptions. It appears that, while the clay, sand, and
+yellow limestone before mentioned were in course of deposition at the
+bottom of the sea, volcanos burst out beneath the waters, like that of
+Graham Island, in 1831, and these explosions recurred again and again at
+distant intervals of time. Volcanic ashes and sand were showered down and
+spread by the waves and currents <span class="pagenum"><a id="page151"></a>[p.151]</span>so as to form strata of tuff,
+which are found intercalated between beds of limestone and clay containing
+marine shells, the thickness of the whole mass exceeding 2000 feet. The
+fissures through which the lava rose may be seen in many places forming
+what are called <i>dikes</i>.</p>
+
+<p>In part of the region above alluded to, as, for example, near Lentini, a
+conglomerate occurs in which I observed many pebbles of volcanic rocks
+covered by full grown <i>serpul�</i>. We may explain the origin of these by
+supposing that there were some small volcanic islands which may have been
+destroyed from time to time by the waves, as Graham Island has been swept
+away since 1831. The rounded blocks and pebbles of solid volcanic matter,
+after being rolled for a time on the beach of such temporary islands, were
+carried at length into some tranquil part of the sea, where they lay for
+years, while the marine <i>serpul�</i> adhered to them, their shells growing and
+covering their surface, as they are seen adhering to the shell figured in
+<a href="#page22">p. 22.</a> Finally, the bed of pebbles was itself covered with strata of shelly
+limestone. At Vizzini, a town not many miles distant to the S.W., I
+remarked another striking proof of the gradual manner in which these modern
+rocks were formed, and the long intervals of time which elapsed between the
+pouring out of distinct sheets of lava. A bed of oysters no less than 20
+feet in thickness rests upon a current of basaltic lava. The oysters are
+perfectly identifiable with our common eatable species. Upon the oyster
+bed, again, is superimposed a second mass of lava, together with tuff or
+peperino. In the midst of the same alternating igneous and aqueous
+formations is seen near Galieri, not far from Vizzini, a horizontal bed,
+about a foot and a half in thickness, composed entirely of a common
+Mediterranean coral (<i>Caryophyllia c�spitosa</i>, Lam.). These corals stand
+erect as they grew; and, after being traced for hundreds of yards, are
+again found at a corresponding height on the opposite side of the valley.</p>
+
+<a id="img128" name="img128"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 123.</p>
+<img src="images/img128.jpg" width="450" height="266" alt="" title="">
+<p><i>Caryophyllia c�spitosa</i>, <span class="wosp05">Lam. (</span><i>Cladocora
+c�spitosa</i>, Ehr.)</p>
+<ul class="smaller martopm05 leftal min1em add1em">
+<li><i>a.</i> Stem with young stem growing from its side.</li>
+<li><i>a*.</i> Young stem of same twice magnified.</li>
+<li><i>b.</i> Portion of branch, twice magnified, with the base of a lateral branch; the exterior
+ridges of the main branch appearing through the lamell� of the lateral one.</li>
+<li><i>c.</i> Transverse section of same, proving, by the integrity of the main branch, that the
+lateral one did not originate in a subdivision of the animal.</li>
+<li><i>d.</i> A branch, having at its base another laterally united to it, and two young corals at
+its upper part.</li>
+<li><i>e.</i> A main branch, with a full grown lateral one.</li>
+<li><i>f.</i> A perfect terminal star.</li>
+</ul></div>
+
+<p><span class="pagenum"><a id="page152"></a>[p.152]</span>The corals are usually branched, but not by the division of the
+animals as some have supposed, but by the attachment of young individuals
+to the sides of the older ones; and we must understand this mode of
+increase, in order to appreciate the time which was required for the
+building up of the whole bed of coral during the growth of many successive
+generations.<a name="FNanchor_O_5" id="FNanchor_O_5"></a><a href="#Footnote_O_5" class="fnanchor">[152-A]</a></p>
+
+<p>Among the other fossil shells met with in these Sicilian strata, which
+still continue to abound in the Mediterranean, no shell is more
+conspicuous, from its size and frequent occurrence, than the great scallop,
+<i>Pecten jacob�us</i> (see <a href="#img129">fig. 124.</a>), now so common in the neighbouring seas.
+We see this shell in the calcareous beds at Palermo in great numbers, in
+the limestone at Girgenti, and in that which alternates with volcanic rocks
+in the country between Syracuse and Vizzini, often at great heights above
+the sea.</p>
+
+<a id="img129" name="img129"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 124.</p>
+<img src="images/img129.jpg" width="400" height="364" alt="" title="">
+<p><i>Pecten jacob�us</i>; half natural size.</p></div>
+
+<p>The more we reflect on the preponderating number of these recent shells,
+the more we are surprised at the great thickness, solidity, and height
+above the sea of the rocky masses in which they are entombed, and the vast
+amount of geographical change which has taken place since their origin. It
+must be remembered that, before they began to emerge, the uppermost strata
+of the whole must have been deposited under water. In order, therefore, to
+form a just conception of their antiquity, we must first examine singly the
+innumerable minute parts of which the whole is made up, the successive beds
+of shells, corals, volcanic ashes, conglomerates, and sheets of lava; and
+we must afterwards contemplate the time required for the gradual upheaval
+of the rocks, and the excavation of the valleys. The historical period
+seems scarcely to form an appreciable unit in this computation, <span class="pagenum"><a id="page153"></a>[p.153]</span>
+for we find ancient Greek temples, like those of Girgenti (Agrigentum),
+built of the modern limestone of which we are speaking, and resting on a
+hill composed of the same; the site having remained to all appearance
+unaltered since the Greeks first colonised the island.</p>
+
+<p>The modern geological date of the rocks in this region leads to another
+singular and unexpected conclusion, namely, that the fauna and flora of a
+large part of Sicily are of higher antiquity than the country itself,
+having not only flourished before the lands were raised from the deep, but
+even before their materials were brought together beneath the waters. The
+chain of reasoning which conducts us to this opinion may be stated in a few
+words. The larger part of the island has been converted from sea into land
+since the Mediterranean was peopled with nearly all the living species of
+testacea and zoophytes. We may therefore presume that, before this region
+emerged, the same land and river shells, and almost all the same animals
+and plants, were in existence which now people Sicily; for the terrestrial
+fauna and flora of this island are precisely the same as that of other
+lands surrounding the Mediterranean. There appear to be no peculiar or
+indigenous species, and those which are now established there must be
+supposed to have migrated from pre-existing lands, just as the plants and
+animals of the Neapolitan territory have colonised Monte Nuovo, since that
+volcanic cone was thrown up in the sixteenth century.</p>
+
+<p>Such conclusions throw a new light on the adaptation of the attributes and
+migratory habits of animals and plants to the changes which are unceasingly
+in progress in the physical geography of the globe. It is clear that the
+duration of species is so great, that they are destined to outlive many
+important revolutions in the configuration of the earth's surface; and
+hence those innumerable contrivances for enabling the subjects of the
+animal and vegetable creation to extend their range; the inhabitants of the
+land being often carried across the ocean, and the aquatic tribes over
+great continental spaces. It is obviously expedient that the terrestrial
+and fluviatile species should not only be fitted for the rivers, valleys,
+plains, and mountains which exist at the era of their creation, but for
+others that are destined to be formed before the species shall become
+extinct; and, in like manner, the marine species are not only made for the
+deep and shallow regions of the ocean existing at the time when they are
+called into being, but for tracts that may be submerged or variously
+altered in depth during the time that is allotted for their continuance on
+the globe.</p>
+
+
+<h3>OSSEOUS BRECCIAS AND DEPOSITS IN CAVES OF THE PLIOCENE PERIOD.</h3>
+
+<p><i>Sicily.</i>&mdash;Caverns filled with marine breccias, at the base of ancient
+sea-cliffs, have been already mentioned in the sixth chapter; and it was
+noticed, respecting the cave of San Ciro, near Palermo (<a href="#page75">p. 75.</a>), that upon
+a bed of sand filled with sea-shells, almost all of recent species,
+<span class="pagenum"><a id="page154"></a>[p.154]</span>rests a breccia (<i>b</i>, <a href="#img098">fig. 93.</a>), composed of fragments of
+calcareous rock, and the bones of animals. In the sand at the bottom of
+that cave, Dr. Philippi found about forty-five marine shells, all clearly
+identical with recent species, except two or three. The bones in the
+incumbent breccia are chiefly those of the mammoth (<i>E. primigenius</i>), with
+some belonging to an hippopotamus, distinct from the recent species, and
+smaller than that usually found fossil. (See <a href="#img137">fig. 132.</a>) Several species of
+deer also, and, according to some accounts, the remains of a bear, were
+discovered. These mammalia are probably referable to the Post-Pliocene
+period.</p>
+
+<p>The Newer Pliocene tertiary limestone of the south of Sicily, already
+described, is sometimes full of caverns; and the student will at once
+perceive that all the quadrupeds of which the remains are found in the
+stalactite of these caverns, being of later origin than the rocks, must be
+referable to the close of the tertiary epoch, if not of still later date.
+The situation of one of these caves, in the valley of Sortino, is
+represented in the annexed section.</p>
+
+<a id="img130" name="img130"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 125.</p>
+<img src="images/img130.jpg" width="450" height="155" alt="" title="">
+
+<table  border="0" cellpadding="2" summary="LEGEND TO FIG. 125.">
+<colgroup>
+    <col width="30%">
+    <col width="10%">
+    <col width="3%">
+    <col width="57%">
+</colgroup>
+
+<tr>
+  <td class="td-left tdtx-top" style="padding-top: 0.7em;"><i>a</i>. Alluvium,</td>
+  <td rowspan="2" valign="middle" style="white-space: nowrap; font-size: 30pt; font-weight: 100;" class="tdtx-top">}</td>
+  <td rowspan="2">&nbsp;</td>
+  <td rowspan="2" class="td-left tdtx-top tdp-left1" style="padding-top: 1.7em;">containing the remains of quadrupeds for the most part extinct.</td>
+</tr>
+
+<tr>
+  <td style="padding-top: 0.5em;" class="td-left tdtx-top"><i>b</i>, <i>b</i>. Deposits in caves,</td>
+</tr>
+
+<tr>
+  <td colspan="4" style="padding-top: 0.3em;" class="td-left tdtx-top">C. Limestone, containing the remains of shells, of which between 70 and 80 per cent. are recent.</td>
+</tr>
+</table></div>
+
+<p><i>England.</i>&mdash;In a cave at Kirkdale, about twenty-five miles N.N.E. of York,
+the remains of about 300 hy�nas, belonging to individuals of every age,
+have been detected. The species (<i>Hy�na spel�a</i>) is extinct, and was larger
+than the fierce <i>Hy�na crocuta</i> of South Africa, which it most resembled.
+Dr. Buckland, after carefully examining the spot, proved that the Hy�nas
+must have lived there; a fact attested by the quantity of their dung,
+which, as in the case of the living hy�na, is of nearly the same
+composition as bone, and almost as durable. In the cave were found the
+remains of the ox, young elephant, hippopotamus, rhinoceros, horse, bear,
+wolf, hare, water-rat, and several birds. All the bones have the appearance
+of having been broken and gnawed by the teeth of the hy�nas; and they occur
+confusedly mixed in loam or mud, or dispersed through a crust of stalagmite
+which covers it. In these and many other cases it is supposed that portions
+of herbivorous quadrupeds have been dragged into caverns by beasts of prey,
+and have served as their food, an opinion quite consistent with the known
+habits of the living hy�na.</p>
+
+<p>No less than thirty-seven species of mammalia are enumerated by Professor
+Owen as having been discovered in the caves of the British islands, of
+which eighteen appear to be extinct, while the others still <span class="pagenum"><a id="page155"></a>[p.155]</span>
+survive in Europe. They were not washed to the spots where the fossils now
+occur by a great flood; but lived and died, one generation after another,
+in the places where they lie buried. Among other arguments in favour of
+this conclusion may be mentioned the great numbers of the shed antlers of
+deer discovered in caves and in freshwater strata throughout
+England.<a name="FNanchor_O_6" id="FNanchor_O_6"></a><a href="#Footnote_O_6" class="fnanchor">[155-A]</a></p>
+
+<p>Examples also occur of fissures into which animals have fallen from time to
+time, or have been washed in from above, together with alluvial matter and
+fragments of rock detached by frost, forming a mass which may be united
+into a bony breccia by stalagmitic infiltrations. Frequently we discover a
+long suite of caverns connected by narrow and irregular galleries, which
+hold a tortuous course through the interior of mountains, and seem to have
+served as the subterranean channels of springs and engulphed rivers. Many
+streams in the Morea are now carrying bones, pebbles, and mud into
+underground passages of this kind.<a name="FNanchor_O_7" id="FNanchor_O_7"></a><a href="#Footnote_O_7" class="fnanchor">[155-B]</a> If, at some future period, the
+form of that country should be wholly altered by subterranean movements and
+new valleys shaped out by denudation, many portions of the former channels
+of these engulphed streams may communicate with the surface, and become the
+dens of wild beasts, or the recesses to which quadrupeds retreat to die.
+Certain caves of France, Germany, and Belgium, may have passed successively
+through these different conditions, and in their last state may have
+remained open to the day for several tertiary periods. It is nevertheless
+remarkable, that on the continent of Europe, as in England, the fossil
+remains of mammalia belong almost exclusively to those of the Newer
+Pliocene and Post-Pliocene periods, and not to the Miocene or Eocene
+epochs, and when they are accompanied by land or river shells, these agree
+in great part, or entirely, with recent species.</p>
+
+<p>As the preservation of the fossil bones is due to a slow and constant
+supply of stalactite, brought into the caverns by water dropping from the
+roof, the source and origin of this deposit has been a subject of curious
+inquiry. The following explanation of the phenomenon has been recently
+suggested by the eminent chemist Liebig. On the surface of Franconia, where
+the limestone abounds in caverns, is a fertile soil, in which vegetable
+matter is continually decaying. This mould or humus, being acted on by
+moisture and air, evolves carbonic acid which is dissolved by rain. The
+rain water, thus impregnated, permeates the porous limestone, dissolves a
+portion of it, and afterwards, when the excess of carbonic acid evaporates
+in the caverns, parts with the calcareous matter, and forms stalactite.</p>
+
+<p><i>Australian cave-breccias.</i>&mdash;Ossiferous breccias are not confined to
+Europe, but occur in all parts of the globe; and those lately discovered in
+fissures and caverns in Australia correspond closely in character with what
+has been called the bony breccia of the Mediterranean, in which the
+fragments of bone and rock are firmly bound together by a red ochreous
+cement.</p>
+
+<p><span class="pagenum"><a id="page156"></a>[p.156]</span>Some of these caves have been examined by Sir T. Mitchell in the
+Wellington Valley, about 210 miles west of Sidney, on the river Bell, one
+of the principal sources of the Macquarie, and on the Macquarie itself. The
+caverns often branch off in different directions through the rock, widening
+and contracting their dimensions, and the roofs and floors are covered with
+stalactite. The bones are often broken, but do not seem to be water-worn.
+In some places they lie imbedded in loose earth, but they are usually
+included in a breccia.</p>
+
+<p>The remains found most abundantly are those of the kangaroo, of which there
+are four species, besides which the genera <i>Hypsiprymnus</i>, <i>Phalangista</i>,
+<i>Phascolomys</i>, and <i>Dasyurus</i>, occur. There are also bones, formerly
+conjectured by some osteologists to belong to the hippopotamus, and by
+others to the dugong, but which are now referred by Mr. Owen to a marsupial
+genus, allied to the <i>Wombat</i>.</p>
+
+<a id="img131" name="img131"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 126.</p>
+<img src="images/img131.jpg" width="400" height="267" alt="" title="">
+<p><i>Macropus atlas</i>, Owen.</p>
+<p class="martopm1"><i>a.</i> permanent false molar, in the alveolus.</p></div>
+
+<a id="img132" name="img132"></a>
+<div class="figcenter smaller width400">
+<p class="martop1">Fig. 127.</p>
+<img src="images/img132.jpg" width="400" height="201" alt="" title="">
+<p>Lowest jaw of largest living species of kangaroo.
+(<i>Macropus major.</i>)</p></div>
+
+<p>In the fossils above enumerated, several species are larger than the
+largest living ones of the same genera now known in Australia. The annexed
+figure of the right side of a lower jaw of a kangaroo (<i>Macropus atlas</i>,
+Owen) will at once be seen to exceed in magnitude the corresponding part of
+the largest living kangaroo, which is represented in <a href="#img132">fig. 127.</a> In both
+these specimens part of the substance of the jaw has been broken open, so
+as to show the <span class="pagenum"><a id="page157"></a>[p.157]</span>permanent false molar (<i>a.</i> <a href="#img131">fig. 126.</a>) concealed
+in the socket. From the fact of this molar not having been cut, we learn
+that the individual was young, and had not shed its first teeth. In <a href="#img133">fig.
+128.</a> a front tooth of the same species of kangaroo is represented.</p>
+
+<a id="img133" name="img133"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 128.</p>
+<img src="images/img133.jpg" width="150" height="406" alt="" title="">
+<p>Incisor of <i>Macropus</i>.</p></div>
+
+<p>Whether the breccias, above alluded to, of the Wellington Valley, appertain
+strictly to the Pliocene period cannot be affirmed with certainty, until we
+are more thoroughly acquainted with the recent quadrupeds of the same
+district, and until we learn what species of fossil land shells, if any,
+are buried in the deposits of the same caves.</p>
+
+<p>The reader will observe that all these extinct quadrupeds of Australia
+belong to the marsupial family, or, in other words, that they are referable
+to the same peculiar type of organization which now distinguishes the
+Australian mammalia from those of other parts of the globe. This fact is
+one of many pointing to a general law deducible from the fossil vertebrate
+and invertebrate animals of the eras immediately antecedent to the human,
+namely, that the present geographical distribution of organic <i>forms</i> dates
+back to a period anterior to the creation of existing <i>species</i>; in other
+words, the limitation of particular genera or families of quadrupeds,
+mollusca, &amp;c., to certain existing provinces of land and sea, began before
+the species now contemporary with man had been introduced into the earth.</p>
+
+<p>Mr. Owen, in his excellent "History of British Fossil Mammals," has called
+attention to this law, remarking that the fossil quadrupeds of Europe and
+Asia differ from those of Australia or South America. We do not find, for
+example, in the Europ�o-Asiatic province fossil kangaroos or armadillos,
+but the elephant, rhinoceros, horse, bear, hy�na, beaver, hare, mole, and
+others, which still characterize the same continent.</p>
+
+<p>In like manner in the Pampas of South America the skeletons of Megatherium,
+Megalonyx, Glyptodon, Mylodon, Toxodon, Macrauchenia, and other extinct
+forms, are analogous to the living sloth, armadillo, cavy, capybara, and
+llama. The fossil quadrumana, also associated with some of these forms in
+the Brazilian caves, belong to the Platyrrhine family of monkeys, now
+peculiar to South America. That the extinct fauna of Buenos Ayres and
+Brazil was very modern has been shown by its relation to deposits of marine
+shells, agreeing with those now inhabiting the Atlantic; and when in
+Georgia in 1845, I ascertained that the Megatherium, Mylodon, <i>Harlanus
+americanus</i> (Owen), <i>Equus curvidens</i>, and other quadrupeds allied to the
+Pampean type were posterior in date to beds containing marine shells
+belonging to forty-five recent species of the neighbouring sea.</p>
+
+<p>There are indeed some cosmopolite genera, such as the Mastodon (a genus of
+the elephant family), and the horse, which were simultaneously represented
+by different fossil species in Europe, North <span class="pagenum"><a id="page158"></a>[p.158]</span>America, and South
+America; but these few exceptions can by no means invalidate the rule which
+has been thus expressed by Professor Owen, "that in the highest organized
+class of animals the same forms were restricted to the same great provinces
+at the Pliocene periods as they are at the present day."</p>
+
+<p>However modern, in a geological point of view, we may consider the
+Pleistocene epoch, it is evident that causes more general and powerful than
+the intervention of man have occasioned the disappearance of the ancient
+fauna from so many extensive regions. Not a few of the species had a wide
+range; the same Megatherium, for instance, extended from Patagonia and the
+river Plata in South America, between latitudes 31� and 39� south, to
+corresponding latitudes in North America, the same animal being also an
+inhabitant of the intermediate country of Brazil, where its fossil remains
+have been met with in caves. The extinct elephant, likewise, of Georgia
+(<i>Elephas primigenius</i>) has been traced in a fossil state northward from
+the river Alatamaha, in lat. 33� 50' N. to the polar regions, and then
+again in the eastern hemisphere from Siberia to the south of Europe. If it
+be objected that, notwithstanding the adaptation of such quadrupeds to a
+variety of climates and geographical conditions, their great size exposed
+them to extermination by the first hunter tribes, we may observe that the
+investigations of Lund and Clausen in the ossiferous limestone caves of
+Brazil have demonstrated that these large mammalia were associated with a
+great many smaller quadrupeds, some of them as diminutive as field mice,
+which have all died out together, while the land shells formerly their
+contemporaries still continue to exist in the same countries. As we may
+feel assured that these minute quadrupeds could never have been extirpated
+by man, so we may conclude that all the species, small and great, have been
+annihilated one after the other, in the course of indefinite ages, by those
+changes of circumstances in the organic and inorganic world which are
+always in progress, and are capable in the course of time of greatly
+modifying the physical geography, climate, and all other conditions on
+which the continuance upon the earth of any living being must
+depend.<a name="FNanchor_O_8" id="FNanchor_O_8"></a><a href="#Footnote_O_8" class="fnanchor">[158-A]</a></p>
+
+<p>The law of geographical relationship above alluded to, between the living
+vertebrata of every great zoological province and the fossils of the period
+immediately antecedent, even where the fossil species are extinct, is by no
+means confined to the mammalia. New Zealand, when first examined by
+Europeans, was found to contain no indigenous land quadrupeds, no
+kangaroos, or opossums, like Australia; but a wingless bird abounded there,
+the smallest living representative of the ostrich family, called the Xivi,
+by the natives (<i>Apteryx</i>). In the fossils of the Post-Pliocene and
+Pleistocene period in this same island, there is the like absence of
+kangaroos, opossums, wombats, and the rest; but in their place a prodigious
+number of well preserved specimens of gigantic birds of the struthious
+order, called by Owen <span class="pagenum"><a id="page159"></a>[p.159]</span>Dinornis and Palapteryx, which are entombed
+in superficial deposits. These genera comprehended many species, some of
+which were 4, some 7, others 9, and others 11 feet in height! It seems
+doubtful whether any contemporary mammalia shared the land with this
+population of gigantic feathered bipeds.</p>
+
+<p>To those who have never studied comparative anatomy it may seem scarcely
+credible, that a single bone taken from any part of the skeleton may enable
+a skilful osteologist to distinguish, in many cases, the genus, and
+sometimes the species, of quadruped to which it belonged. Although few
+geologists can aspire to such knowledge, which must be the result of long
+practice and study, they will nevertheless derive great advantage from
+learning what is comparatively an easy task, to distinguish the principal
+divisions of the mammalia by the forms and characters of their teeth. The
+annexed figures, all taken from original specimens, may be useful in
+assisting the student to recognize the teeth of many genera most frequently
+found fossil in Europe:&mdash;</p>
+
+<a id="img134" name="img134"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 129.</p>
+<img src="images/img134.jpg" width="450" height="348" alt="" title="">
+<p><i>Elephas primigenius</i> (or Mammoth); molar of upper
+jaw, right side; one third of nat. size.</p>
+<ul class="smaller martopm05 leftal add1em">
+<li><i>a.</i> grinding surface.</li>
+<li><i>b.</i> side view.</li>
+</ul></div>
+
+<a id="img135" name="img135"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 130.</p>
+<img src="images/img135.jpg" width="450" height="282" alt="" title="">
+<p><i>Mastodon angustidens</i> (Norwich Crag, Postwick,
+also found in Red Crag, see <a href="#page149">p. 149.</a>); second true molar, left side, upper
+jaw; grinding surface, nat. size. (See <a href="#page149">p. 149.</a>)</p></div>
+
+<span class="pagenum"><a id="page160"></a>[p.160]</span>
+<a id="img136" name="img136"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 131.</p>
+<img src="images/img136.jpg" width="250" height="359" alt="" title="">
+<p>Rhinoceros.</p>
+<p><i>Rhinoceros leptorhinus</i>; fossil from freshwater beds of Grays, Essex (see
+<a href="#page147">p. 147.</a>); penultimate molar, lower jaw, left side; two-thirds of nat.
+size.</p></div>
+
+<a id="img137" name="img137"></a>
+<div class="floatright smaller width250">
+<p>Fig. 132.</p>
+<img src="images/img137.jpg" width="250" height="300" alt="" title="">
+<p>Hippopotamus.</p>
+<p>Hippopotamus; from cave near Palermo (see <a href="#page154">p. 154.</a>); molar tooth; two-thirds
+of nat. size.</p></div>
+
+<a id="img138" name="img138"></a>
+<div class="figcenter nofloat smaller width200">
+<p class="martop2">Fig. 133.</p>
+<img src="images/img138.jpg" width="200" height="426" alt="" title="">
+<p>Pig.</p>
+<p><i>Sus scrofa</i>, Lin. (common pig); from shell-marl, Forfarshire; posterior
+molar, lower jaw, nat. size.</p></div>
+
+<a id="img139" name="img139"></a>
+<div class="figcenter smaller width300">
+<p class="martop2">Fig. 134.</p>
+<img src="images/img139.jpg" width="300" height="345" alt="" title="">
+<p>Horse.</p>
+<p><i>Equus caballus</i>, Lin. (common horse); from the shell marl, Forfarshire;
+second molar, lower jaw.</p>
+<ul class="martopmm05 smaller leftal add1em min1em">
+<li><i>a.</i> grinding surface, two-thirds nat. size.</li>
+<li><i>b.</i> side view of same, half nat. size.</li>
+</ul></div>
+
+<a id="img140" name="img140"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 135.</p>
+<img src="images/img140.jpg" width="250" height="302" alt="" title="">
+<p>Tapir.</p>
+<p><i>Tapirus Americanus</i>; recent; third molar, upper jaw; nat. size</p></div>
+
+<a id="img141" name="img141"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 136.</p>
+<img src="images/img141.jpg" width="350" height="473" alt="" title="">
+<p><i>a.</i> <i>b.</i> Deer.</p>
+<p>Elk (<i>Cervus alces</i>, Lin.); recent; molar of upper jaw.</p>
+<ul class="martopmm05 smaller leftal add2em min1em">
+<li><i>a.</i> grinding surface.</li>
+<li><i>b.</i> side view; two-thirds of nat. size.</li>
+</ul></div>
+
+<a id="img142" name="img142"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 137.</p>
+<img src="images/img142.jpg" width="350" height="400" alt="" title="">
+<p><i>c.</i> <i>d.</i> Ox.</p>
+<p>Ox, common, from shell marl, Forfarshire; true molar upper jaw; two-thirds
+nat. size.</p>
+<ul class="smaller leftal martopm05 add1em">
+<li><i>c.</i> grinding surface.</li>
+<li><i>d.</i> side view.</li>
+</ul></div>
+
+<span class="pagenum"><a id="page161"></a>[p.161]</span>
+<a id="img143" name="img143"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 138.</p>
+<img src="images/img143.jpg" width="350" height="420" alt="" title="">
+<p>Bear.</p>
+<ul class="leftal smaller martopm05 min1em add1em">
+<li><i>a.</i> canine tooth or tusk of bear (<i>Ursus
+spel�us</i>); from cave near Liege.</li>
+<li><i>b.</i> molar of left side, upper jaw; one
+third of nat. size.</li>
+</ul></div>
+
+<a id="img144" name="img144"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 139.</p>
+<img src="images/img144.jpg" width="350" height="375" alt="" title="">
+<p>Tiger.</p>
+<ul class="leftal smaller martopm05 add1em min1em">
+<li><i>c.</i> canine tooth of tiger (<i>Felis tigris</i>); recent.</li>
+<li><i>d.</i> outside view of posterior molar, lower
+jaw; one-third of nat. size.</li>
+</ul></div>
+
+<a id="img145" name="img145"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 140.</p>
+<img src="images/img145.jpg" width="250" height="200" alt="" title="">
+<p><i>Hy�na spel�a</i>; second molar, left side, lower
+jaw; nat. <span class="wosp05">size. Cave</span> of <span class="wosp05">Kirkdale. (See</span> <a href="#page154">p. 154.</a>)</p></div>
+
+<a id="img146" name="img146"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 141.</p>
+<img src="images/img146.jpg" width="400" height="103" alt="" title="">
+<p>Teeth of a new species of <i>Arvicola</i>
+(field-mouse); from the Norwich <span class="wosp05">Crag. (See</span> <a href="#page149">p. 149.</a>)</p>
+<ul class="leftal smaller martopm05 add1em">
+<li><i>a.</i> grinding surface.</li>
+<li><i>b.</i> side view of same.</li>
+<li><i>c.</i> nat. size of a and b.</li>
+</ul></div>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XIV.</h2>
+
+<h4>OLDER PLIOCENE AND MIOCENE FORMATIONS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Strata of Suffolk termed Red and Coralline crag &mdash; Fossils, and
+proportion of recent species &mdash; Depth of sea and climate &mdash; Reference
+of Suffolk crag to the older Pliocene period &mdash; Migration of many
+species of shells southwards during the glacial period &mdash; Fossil
+whales &mdash; Subapennine beds &mdash; Asti, Sienna, Rome &mdash; Miocene
+formations &mdash; Faluns of Touraine &mdash; Depth of sea and littoral
+character of fauna &mdash; Tropical climate implied by the
+testacea &mdash; Proportion of recent species of shells &mdash; Faluns more
+ancient than the Suffolk crag &mdash; Miocene strata of Bordeaux and
+Piedmont &mdash; Molasse of Switzerland &mdash; Tertiary strata of
+Lisbon &mdash; Older Pliocene and Miocene formations in the United
+States &mdash; Sew�lik Hills in India.</p></div>
+
+
+<p><span class="smcap">The</span> older Pliocene strata, which next claim our attention, are chiefly
+confined, in Great Britain, to the eastern part of the county of Suffolk,
+where, like the Norwich beds already described, they are called "Crag," a
+provincial name given particularly to those masses of shelly sand which
+have been used from very ancient times in agriculture, to fertilize soils
+deficient in calcareous matter. The relative position of the "red crag" in
+Essex to the London clay, may be understood by reference to the
+accompanying diagram (<a href="#img147">fig. 142.</a>).</p>
+
+<span class="pagenum"><a id="page162"></a>[p.162]</span>
+<a id="img147" name="img147"></a>
+<div class="figcenter smaller">
+<p>Fig. 142.</p>
+<img src="images/img147.jpg" width="400" height="057" alt="" title=""></div>
+
+<p>These deposits, judging by the shells which they contain, appear, according
+to Professor Edward Forbes, to have been formed in a sea of moderate depth,
+generally from 15 to 25 fathoms deep, although in some few spots perhaps
+deeper. But they may, nevertheless, have been accumulated at the distance
+of 40 or 50 miles from land.</p>
+
+<p>The Suffolk crag is divisible into two masses, the upper of which has been
+termed the Red, and the lower the Coralline Crag.<a name="FNanchor_P_1" id="FNanchor_P_1"></a><a href="#Footnote_P_1" class="fnanchor">[162-A]</a> The upper deposit
+consists chiefly of quartzose sand, with an occasional intermixture of
+shells, for the most part rolled, and sometimes comminuted. The lower or
+Coralline crag is of very limited extent, ranging over an area about 20
+miles in length, and 3 or 4 in breadth, between the rivers Alde and Stour.
+It is generally calcareous and marly&mdash;a mass of shells and small corals,
+passing occasionally into a soft building stone. At Sudbourn, near Orford,
+where it assumes this character, are large quarries, in which the bottom of
+it has not been reached at the depth of 50 feet. At some places in the
+neighbourhood, the softer mass is divided by thin flags of hard limestone,
+and corals placed in the upright position in which they grew.</p>
+
+<p>The Red crag is distinguished by the deep ferruginous or ochreous colour of
+its sands and fossils, the Coralline by its white colour. Both formations
+are of moderate thickness; the red crag rarely exceeding 40, and the
+coralline seldom amounting to 20, feet. But their importance is not to be
+estimated by the density of the mass of strata or its geographical extent,
+but by the extraordinary richness of its organic remains, belonging to a
+very peculiar type, which seems to characterize the state of the living
+creation in the north of Europe during the older Pliocene era.</p>
+
+<p>For a large collection of the fish, echinoderms, shells, and corals of the
+deposits in Suffolk, we are indebted to the labours of Mr. Searles Wood. Of
+testacea alone he has obtained from 230 species from the Red, and 345 from
+the Coralline crag, about 150 being common to each. The proportion of
+recent species in the new group is considered by Mr. Wood to be about
+70<a name="FNanchor_P_2" id="FNanchor_P_2"></a><a href="#Footnote_P_2" class="fnanchor">[162-B]</a> per cent., and that in the older or coralline about 60. When I
+examined these shells of Suffolk in 1835, with the assistance of Dr. Beck,
+Mr. George Sowerby, Mr. Searles Wood, and other eminent conchologists, I
+came to the opinion that the extinct species predominated very decidedly in
+number over the living. Recent investigations, however, have thrown much
+new light on the conchology of the Arctic, Scandinavian, British, and
+Mediterranean Seas. Many of the species formerly known only as fossils of
+the Crag, and supposed to have died out, have been dredged up in a living
+state <span class="pagenum"><a id="page163"></a>[p.163]</span>from depths not previously explored. Other recent species,
+before regarded as distinct from the nearest allied Crag fossils, have been
+observed, when numerous individuals were procured, to be liable to much
+greater variation, both in size and form, than had been suspected, and thus
+have been identified. Consequently, the Crag fauna has been found to
+approach much more nearly to the recent fauna of the Northern, British, and
+Mediterranean Seas than had been imagined. The analogy of the whole group
+of testacea to the European type is very marked, whether we refer to the
+large development of certain genera in number of species or to their size,
+or to the suppression or feeble representation of others. The indication
+also afforded by the entire fauna of a climate not much warmer than that
+now prevailing in corresponding latitudes, prepares us to believe that they
+are not of higher antiquity than the Older Pliocene era.<a name="FNanchor_P_3" id="FNanchor_P_3"></a><a href="#Footnote_P_3" class="fnanchor">[163-A]</a></p>
+
+<a id="img148" name="img148"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 143.</p>
+<img src="images/img148.jpg" width="400" height="067" alt="" title="">
+<p>Section near Ipswich, in Suffolk.</p>
+<ul class="leftal smaller martopm05 add2em">
+<li><i>a.</i> Red crag.</li>
+<li><i>b.</i> Coralline crag.</li>
+<li><i>c.</i> London clay.</li>
+</ul></div>
+
+<p>The position of the red crag in Essex to the subjacent London clay and
+chalk has been already pointed out (<a href="#img147">fig. 142.</a>). Whenever the two divisions
+are met with in the same district, the red crag lies uppermost; and, in
+some cases, as in the section represented in <a href="#img148">fig. 143.</a>, it is observed that
+the older or coralline mass <i>b</i> had suffered denudation before the newer
+formation <i>a</i> was thrown down upon it. At D there is not only a distinct
+cliff, 8 or 10 feet high, of coralline crag, running in a direction N.E.
+and S.W., against which the red crag abuts with its horizontal layers; but
+this cliff occasionally overhangs. The rock composing it is drilled
+everywhere by <i>Pholades</i>, the holes which they perforated having been
+afterwards filled with sand and covered over when the newer beds were
+thrown down. As the older formation is shown by its fossils to have
+accumulated in a deeper sea (15, and sometimes 25, fathoms deep or more),
+there must no doubt have been an upheaval of the sea-bottom before the
+cliff here alluded to was shaped out. We may also conclude that so great an
+amount of denudation could scarcely take place, in such incoherent
+materials, without many of the fossils of the inferior beds becoming mixed
+up with the overlying crag, so that considerable difficulty must be
+occasionally experienced by the pal�ontologist in deciding which species
+belong severally to each group. The red crag being formed in a shallower
+sea, often resembles in structure a shifting sand bank, its layers being
+inclined diagonally, and the planes of stratification being sometimes
+directed in the same quarry to the four <span class="pagenum"><a id="page164"></a>[p.164]</span>cardinal points of the
+compass, as at Butley. That in this and many other localities, such a
+structure is not deceptive or due to any subsequent concretionary
+re-arrangement of particles, or to mere lines of colour, is proved by each
+bed being made up of flat pieces of shell which lie parallel to the planes
+of the smaller strata.</p>
+
+<p>Some fossils, which are very abundant in the red crag, have never been
+found in the white or coralline division; as, for example, the <i>Fusus
+contrarius</i> (<a href="#img149">fig. 144.</a>), and several species of <i>Buccinum</i> (or <i>Nassa</i>) and
+<i>Murex</i> (see <a href="#img149">figs. 145</a>, <a href="#img149">146.</a>), which two genera seem wanting in the lower
+crag.</p>
+
+<a id="img149" name="img149"></a>
+<div class="figcenter smaller martopm05 width500">
+<p>Fossils characteristic of the Red Crag.</p>
+<img src="images/img149.jpg" width="500" height="270" alt="" title="">
+<p>Fig. 144. <i>Fusus contrarius.</i></p>
+<p>Fig. 145. <i>Murex alveolatus.</i></p>
+<p>Fig. 146. <i>Nassa granulata.</i></p>
+<p>Fig. 147. <i>Cypr�a coccinelloides.</i></p>
+<p>Fig. 144. half nat. size; the others nat. size.</p></div>
+
+<p>Among the bones and teeth of fishes are those of large sharks
+(<i>Carcharias</i>), and a gigantic skate of the extinct genus <i>Myliobates</i>, and
+many other forms, some common to our seas, and many foreign to them.</p>
+
+<p>The distinctness of the fossils of the coralline crag arises in part from
+higher antiquity, and, in some degree, from a difference in the
+geographical conditions of the submarine bottom. The prolific growth of
+corals, echini, and a prodigious variety of testacea, implies a region of
+deeper and more tranquil water; whereas, the red crag may have formed
+afterwards on the same spot, when the water was shallower. In the mean time
+the climate may have become somewhat cooler, and some of the zoophytes
+which flourished in the first period may have disappeared, so that the
+fauna of the red crag acquired a character somewhat more nearly resembling
+that of our northern seas, as is implied by the large development of
+certain sections of the genera <i>Fusus</i>, <i>Buccinum</i>, <i>Purpura</i>, and
+<i>Trochus</i>, proper to higher latitudes, and which are wanting or feebly
+represented in the inferior crag.</p>
+
+<p>Some of the corals of the lower crag of Suffolk belong to genera unknown in
+the living creation, and of a very peculiar structure; as, for example,
+that represented in the annexed <a href="#img150">fig. (148.)</a>, which is one of several
+species having a globular form. The great number and variety of these
+zoophytes probably indicate an equable climate, free <span class="pagenum"><a id="page165"></a>[p.165]</span>from intense
+cold in winter. On the other hand, that the heat was never excessive is
+confirmed by the prevalence of northern forms among the testacea, such as
+the <i>Glycimeris</i>, <i>Cyprina</i>, and <i>Astarte</i>. Of the genus last mentioned
+(see <a href="#img151">fig. 149.</a>) there are about fourteen species, many of them being rich
+in individuals; and there is an absence of genera peculiar to hot climates,
+such as <i>Conus</i>, <i>Oliva</i>, <i>Mitra</i>, <i>Fasciolaria</i>, <i>Crassatella</i>, and
+others. The cowries (<i>Cypr�a</i>, <a href="#img149">fig. 147.</a>), also, are small, and belong to a
+section (<i>Trivia</i>) now inhabiting the colder regions. A large volute,
+called <i>Voluta Lamberti</i> (<a href="#img152">fig. 150.</a>), may seem an exception; but it differs
+in form from the volutes of the torrid zone, and may, like the living
+<i>Voluta Magellanica</i>, have been fitted for an extra-tropical climate.</p>
+
+<a id="img150" name="img150"></a>
+<div class="figcenter smalller width500">
+<p>Fig. 148.</p>
+<img src="images/img150.jpg" width="500" height="254" alt="" title="">
+<p><i>Fascicularia aurantium</i>, Milne <span class="wosp05">Edwards. Family,</span>
+<i>Tubuliporid�</i>, of same author.</p>
+<p>Coral of extinct genus, from the inferior or coralline crag, Suffolk.</p>
+<ul class="leftal smaller martopm05 add1em min1em">
+<li><i>a.</i> exterior.</li>
+<li><i>b.</i> vertical section of interior.</li>
+<li><i>c.</i> portion of exterior magnified.</li>
+<li><i>d.</i> portion of interior magnified, showing that it is made up of long, thin, straight tubes, united
+in conical bundles.</li>
+</ul></div>
+
+<a id="img151" name="img151"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 149.</p>
+<img src="images/img151.jpg" width="450" height="173" alt="" title="">
+<p><i>Astarte</i> (<i>Crassina</i>, Lam.); species common to
+upper and lower crag.</p>
+<p class="martopm05"><i>Astarte Omalii</i>, Lajonkaire; Syn. <i>A. bipartita</i>, Sow. Min. Con. T. 521.
+f. 3.; a very variable species most characteristic of the coralline crag,
+Suffolk.</p></div>
+
+<a id="img152" name="img152"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 150.</p>
+<img src="images/img152.jpg" width="200" height="437" alt="" title="">
+<p><i>Voluta Lamberti</i>, young individ.</p></div>
+
+<p>The occurrence of a species of <i>Lingula</i> at Sutton is worthy of remark, as
+these <i>Brachiopoda</i> seem now confined to more equatorial latitudes, and the
+same may be said still more decidedly of a species of <i>Pyrula</i>, allied to
+<i>P. reticulata</i>. Whether, therefore, we may incline to the belief that the
+mean <span class="pagenum"><a id="page166"></a>[p.166]</span>annual temperature was higher or lower than now, we may at
+least infer that the climate and geographical conditions were by no means
+the same at the period of the Suffolk crag as those now prevailing in the
+same region.</p>
+
+<p>Of the echinoderms of the coralline crag about eleven species are known,
+but some of these are in too fragmentary a condition to admit of exact
+comparison. Of six which are the most perfect, Prof. E. Forbes has been
+able to identify three with recent species: one of which, of the genus
+<i>Echinus</i>, is British; a second, <i>Echinocyamus</i>, British and Mediterranean;
+and a third, <i>Echinus monilis</i>, a Mediterranean species, also found fossil
+in the faluns of Touraine.</p>
+
+<p>One of the most interesting conclusions deduced from a careful comparison
+of the shells of these British Older Pliocene strata and those now
+inhabiting our seas, has been pointed out by Prof. E. Forbes. It appears
+that, during the glacial period, a period intermediate, as we have seen,
+between that of the crag and our own times, many shells, previously
+established in the temperate zone, retreated southwards to avoid an
+uncongenial climate. The Professor has given a list of fifty shells which
+inhabited the British seas while the coralline and red crag were forming,
+and which are wanting in the Pleistocene or glacial deposits. They must,
+therefore, after their migration to the south, have made their way
+northwards again. In corroboration of these views, it is stated that all
+these fifty species occur fossil in the Newer Pliocene strata of Sicily,
+Southern Italy, and the Grecian Archipelago, where they may have enjoyed,
+during the era of floating icebergs, a climate resembling that now
+prevailing in higher European latitudes.<a name="FNanchor_P_4" id="FNanchor_P_4"></a><a href="#Footnote_P_4" class="fnanchor">[166-A]</a></p>
+
+<p>In the red crag at Felixstow, in Suffolk, Professor Henslow has found the
+ear-bones of no less than four species of cetacea, which, according to Mr.
+Owen, are the remains of true whales of the family <i>Bal�nid�</i>. Mr. Wood is
+of opinion that these cetacea may be of the age of the red crag, or if not
+that they may be derived from the destruction of beds of coralline crag. I
+agree with him that the supposition of their having been washed out of the
+London clay, in which no <i>Bal�nid�</i> have yet been met with, is improbable.</p>
+
+<p>Strata containing fossil shells, like those of the Suffolk crag, above
+described, have been found at Antwerp, and on the banks of the Scheldt
+below that city. In 1840 I observed a small patch of them near Valognes, in
+Normandy; and there is also a deposit containing similar fossils at St.
+George Bohon, and several places a few leagues to the S. of Carentan, in
+Normandy; but they have never been traced farther southwards.</p>
+
+<p><i>Subapennine strata.</i>&mdash;The Apennines, it is well known, are composed
+chiefly of secondary rocks, forming a chain which branches off from the
+Ligurian Alps and passes down the middle of the Italian peninsula. At the
+foot of these mountains, on the side both of the <span class="pagenum"><a id="page167"></a>[p.167]</span>Adriatic and the
+Mediterranean, are found a series of tertiary strata, which form, for the
+most part, a line of low hills occupying the space between the older chain
+and the sea. Brocchi, as we have seen (<a href="#page105">p. 105.</a>), was the first Italian
+geologist who described this newer group in detail, giving it the name of
+the Subapennines; and he classed all the tertiary strata of Italy, from
+Piedmont to Calabria, as parts of the same system. Certain mineral
+characters, he observed, were common to the whole; for the strata consist
+generally of light brown or blue marl, covered by yellow calcareous sand
+and gravel. There are also, he added, some species of fossil shells which
+are found in these deposits throughout the whole of Italy.</p>
+
+<p>We have now, however, satisfactory evidence that the Subapennine beds of
+Brocchi belong, at least, to three periods. To the Miocene we can refer a
+portion of the strata of Piedmont, those of the hill of the Superga, for
+example; to the Older Pliocene, part of the strata of northern Italy, of
+Tuscany, and of Rome; while the tufaceous formations of Naples, of Ischia,
+and the calcareous strata of Otranto, are referable to the Newer Pliocene,
+and in great part to the Post-Pliocene period.</p>
+
+<p>That there is a considerable correspondence in the mineral composition of
+these different Italian groups is undeniable; but not that exact
+resemblance which should lead us to assume a precise identity of age,
+unless the fossil remains agreed very closely. It is now indispensable that
+a new scrutiny should be made in each particular district, of the fossils
+derived from the upper and lower beds&mdash;especially such localities as Asti
+and Parma, where the formation attains a great thickness; and at Sienna,
+where the shells of the incumbent yellow sand are generally believed to
+approach much more nearly, as a whole, to the recent fauna of the
+Mediterranean than those in the subjacent blue marl.</p>
+
+<p>The greyish brown or blue marl of the Subapennine formation is very
+aluminous, and usually contains much calcareous matter and scales of mica.
+Near Parma it attains a thickness of 2000 feet, and is charged throughout
+with marine shells, some of which lived in deep, others in shallow water,
+while a few belong to freshwater genera, and must have been washed in by
+rivers. Among these last I have seen the common <i>Limnea palustris</i> in the
+blue marl, filled with small marine shells. The wood and leaves, which
+occasionally form beds of lignite in the same deposit, may have been
+carried into the sea by similar causes. The shells, in general, are soft
+when first taken from the marl, but they become hard when dried. The
+superficial enamel is often well preserved, and many shells retain their
+pearly lustre, part of their external colour, and even the ligament which
+unites the valves. No shells are more usually perfect than the microscopic
+foraminifera, which abound near Sienna, where more than a thousand
+full-grown individuals may be sometimes poured out of the interior of a
+single univalve of moderate dimensions.</p>
+
+<p>The other member of the Subapennine group, the yellow sand and <span class="pagenum"><a id="page168"></a>[p.168]</span>
+conglomerate, constitutes, in most places, a border formation near the
+junction of the tertiary and secondary rocks. In some cases, as near the
+town of Sienna, we see sand and calcareous gravel resting immediately on
+the Apennine limestone, without the intervention of any blue marl.
+Alternations are there seen of beds containing fluviatile shells, with
+others filled exclusively with marine species; and I observed oysters
+attached to many limestone pebbles. This appears to have been a point where
+a river, flowing from the Apennines, entered the sea when the tertiary
+strata were formed.</p>
+
+<p>The sand passes in some districts into a calcareous sandstone, as at San
+Vignone. Its general superposition to the marl, even in parts of Italy and
+Sicily where the date of its origin is very distinct, may be explained if
+we consider that it may represent the deltas of rivers and torrents, which
+gained upon the bed of the sea where blue marl had previously been
+deposited. The latter, being composed of the finer and more transportable
+mud, would be conveyed to a distance, and first occupy the bottom, over
+which sand and pebbles would afterwards be spread, in proportion as rivers
+pushed their deltas farther outwards. In some large tracts of yellow sand
+it is impossible to detect a single fossil, while in other places they
+occur in profusion. Occasionally the shells are silicified, as at San
+Vitale, near Parma, from whence I saw two individuals of recent species,
+one freshwater and the other marine (<i>Limnea palustris</i>, and <i>Cytherea
+concentrica</i>, Lam.), both perfectly converted into flint.</p>
+
+<p><i>Rome.</i>&mdash;The seven hills of Rome are composed partly of marine tertiary
+strata, those of Monte Mario, for example, of the Older Pliocene period,
+and partly of superimposed volcanic tuff, on the top of which are usually
+cappings of a fluviatile and lacustrine deposit. Thus, on Mount Aventine,
+the Vatican, and the Capitol, we find beds of calcareous tufa with
+incrusted reeds, and recent terrestrial shells, at the height of about 200
+feet above the alluvial plain of the Tiber. The tusk of the mammoth has
+been procured from this formation, but the shells appear to be all of
+living species, and must have been embedded when the summit of the Capitol
+was a marsh, and constituted one of the lowest hollows of the country as it
+then existed. It is not without interest that we thus discover the
+extremely recent date of a geological event which preceded an historical
+era so remote as the building of Rome.</p>
+
+
+<h3>MIOCENE FORMATIONS.</h3>
+
+<p><i>Faluns of Touraine.</i>&mdash;The Miocene strata, corresponding with those named
+by many geologists "Middle Tertiary," will next claim our attention. Near
+the towns of Dinan and Rennes, in Brittany, and again in the provinces
+bordering the Loire, a tertiary formation, containing another assemblage of
+fossils, is met with, to which the name of <i>Faluns</i> has been long given by
+the French agriculturists, who spread the shelly sand and marl over the
+land, in the same <span class="pagenum"><a id="page169"></a>[p.169]</span>manner as the crag was formerly much used in
+Suffolk. Isolated masses of these faluns occur from near the mouth of the
+Loire, near Nantes, as far as a district south of Tours. They are also
+found at Pontlevoy, on the Cher, about 70 miles above the junction of that
+river with the Loire, and 30 miles S.E. of Tours. I have visited all the
+localities above mentioned, and found the beds to consist principally of
+sand and marl, in which are shells and corals, some entire, some rolled,
+and others in minute fragments. In certain districts, as at Dou�, in the
+department of Maine and Loire, 10 miles S.W. of Saumur, they form a soft
+building-stone, chiefly composed of an aggregate of broken shells, corals,
+and echinoderms, united by a calcareous cement; the whole mass being very
+like the coralline crag near Aldborough and Sudbourn in Suffolk. The
+scattered patches of faluns are of slight thickness, rarely exceeding 50
+feet; and between the district called Sologne and the sea they repose on a
+great variety of older rocks; being seen to rest successively upon gneiss,
+clay-slate, and various secondary formations, including the chalk; and,
+lastly, upon the upper freshwater limestone of the Parisian tertiary
+series, which, as before mentioned (<a href="#page106">p. 106.</a>), stretches continuously from
+the basin of the Seine to that of the Loire.</p>
+
+<p>At some points, as at Louans, south of Tours, the shells are stained of a
+ferruginous colour, not unlike that of the red crag of Suffolk. The species
+are, for the most part, marine, but a few of them belong to land and
+fluviatile genera. Among the former, <i>Helix turonensis</i> (<a href="#img050">fig. 45.</a> <a href="#page30">p. 30.</a>)
+is the most abundant. Remains of terrestrial quadrupeds are here and there
+intermixed, belonging to the genera Deinotherium, Mastodon, Rhinoceros,
+Hippopotamus, Ch�ropotamus, Dichobune, Deer, and others, and these are
+accompanied by cetacea, such as the Lamantine, Morse, Sea-calf, and
+Dolphin, all of extinct species.</p>
+
+<p>Professor E. Forbes, after studying the fossil testacea which I obtained
+from these beds; informs me that he has no doubt they were formed partly on
+the shore itself at the level of low water, and partly at very moderate
+depths, not exceeding 10 fathoms below that level. The molluscous fauna of
+the "faluns" is on the whole much more littoral than that of the red and
+coralline crag of Suffolk, and implies a shallower sea. It is, moreover,
+contrasted with the Suffolk crag by the indications it affords of an
+extra-European climate. Thus it contains seven species of <i>Cypr�a</i>, some
+larger than any existing cowry of the Mediterranean, several species of
+<i>Oliva</i>, <i>Ancillaria</i>, <i>Mitra</i>, <i>Terebra</i>, <i>Pyrula</i>, <i>Fasciolaria</i>, and
+<i>Conus</i>. Of the cones there are no less than eight species, some very
+large, whereas the only European cone is of diminutive size. The genus
+<i>Nerita</i>, and many others, are also represented by individuals of a type
+now characteristic of equatorial seas, and wholly unlike any Mediterranean
+forms. These proofs of a more elevated temperature seem to imply the higher
+antiquity of the faluns as compared with the Suffolk crag, and are in
+perfect accordance with the fact of the smaller proportion of testacea of
+recent species found in the faluns.</p>
+
+<p><span class="pagenum"><a id="page170"></a>[p.170]</span>Out of 290 species of shells, collected by myself, in 1840, at
+Pontlevoy, Louans, Boss�e, and other villages 20 miles south of Tours; and
+at Savign�, about 15 miles north-west of that place; 72 only could be
+identified with recent species, which is in the proportion of 25 per cent.
+A large number of the 290 species are common to all the localities, those
+peculiar to each not being more numerous than we might expect to find in
+different bays of the same sea.</p>
+
+<p>The total number of mollusca from the faluns, in my possession, is 302, of
+which 45 only were found by Mr. Wood to be common to the Suffolk crag. The
+number of corals obtained by me at Dou�, and other localities before
+adverted to, amounts to 43, as determined by Mr. Lonsdale, of which 7 agree
+specifically with those of the Suffolk crag. Only one has, as yet, been
+identified with a living species. But it is difficult, if not impossible,
+to institute at present a satisfactory comparison between fossil and recent
+<i>Polyparia</i>, from the deficiency of our knowledge of the living species.
+Some of the genera occurring fossil in Touraine, as the <i>Astrea</i>,
+<i>Lunulites</i>, and <i>Dendrophyllia</i>, have not been found in European seas
+north of the Mediterranean; nevertheless the <i>Polyparia</i> of the faluns do
+not seem to indicate on the whole so warm a climate as would be inferred
+from the shells.</p>
+
+<p>It was stated that, on comparing about 300 species of Touraine shells with
+about 450 from the Suffolk crag, 45 only were found to be common to both,
+which is in the proportion of only 15 per cent. The same small amount of
+agreement is found in the corals also. I formerly endeavoured to reconcile
+this marked difference in species with the supposed co-existence of the two
+faunas, by imagining them to have severally belonged to distinct zoological
+provinces or two seas, the one opening to the north, and the other to the
+south, with a barrier of land between them, like the Isthmus of Suez,
+separating the Red Sea and the Mediterranean. But I now abandon that idea
+for several reasons; among others, because I succeeded in 1841 in tracing
+the Crag fauna southwards in Normandy to within 70 miles of the Falunian
+type, near Dinan, yet found that both assemblages of fossils retained their
+distinctive characters, showing no signs of any blending of species or
+transition of climate.</p>
+
+<p>On a comparison of 280 Mediterranean shells with 600 British species, made
+for me by an experienced conchologist in 1841, 160 were found to be common
+to both collections, which is in the proportion of 57 per cent., a fourfold
+greater specific resemblance than between the seas of the crag and the
+faluns, notwithstanding the greater geographical distance between England
+and the Mediterranean than between Suffolk and the Loire. The principal
+grounds, however, for referring the English crag to the older Pliocene and
+the French faluns to the Miocene epochs, consist in the predominance of
+fossil shells in the British strata identifiable with species, not only
+still living, but which are now inhabitants of neighbouring seas, while the
+accompanying extinct species are of genera such as characterize Europe. In
+the faluns, on the contrary, the recent species are in a <span class="pagenum"><a id="page171"></a>[p.171]</span>decided
+minority, and many of them, like the associated extinct testacea, are much
+less European in character, and point to the prevalence of a warmer
+climate,&mdash;in other words, to a state of things receding farther from the
+present condition of Europe, geographically and climatologically, and
+doubtless, therefore, receding farther in time.</p>
+
+<p><i>Bordeaux.</i>&mdash;A great extent of country between the Pyrenees and the Gironde
+is overspread by tertiary deposits, which have been more particularly
+studied in the environs of Bordeaux and Dax, from whence about 700 species
+of shells have been obtained. A large proportion of these shells belong to
+the same zoological type as those of Touraine; but many are peculiar, and
+the whole may possibly constitute a somewhat older division of the Miocene
+period than the faluns of the Loire. We must wait, however, for farther
+investigations, in order to decide this question with accuracy.</p>
+
+<p><i>Piedmont.</i>&mdash;Many of the shells peculiar to the hill of the Superga, near
+Turin, agree with those found at Bordeaux and Dax; but the proportion of
+recent species is much less. The strata of the Superga consist of a bright
+green sand and marl, and a conglomerate with pebbles, chiefly of green
+serpentine, and are inclined at an angle of more than 70�. This formation,
+which attains a great thickness in the valley of the Bormida, is probably
+one of the oldest Miocene groups hitherto discovered.</p>
+
+<p><i>Molasse of Switzerland.</i>&mdash;If we cross the Alps, and pass from Piedmont to
+Savoy, we find there, at the northern base of the great chain, and
+throughout the lower country of Switzerland, a soft green sandstone much
+resembling some of the beds of the basin of the Bormida, above described,
+and associated in a similar manner with marls and conglomerate. This
+formation is called in Switzerland "molasse," said to be derived from
+"mol," "<i>soft</i>" because the stone is easily cut in the quarry. It is of
+vast thickness, and probably divisible into several formations. How large a
+portion of these belong to the Miocene period cannot yet be determined, as
+fossil shells are often entirely wanting. In some places a decided
+agreement of the fossil fishes of the molasse and faluns has been observed.
+Among those common to both, M. Agassiz pointed out to me <i>Lamna
+contortidens</i>, <i>Myliobates Studeri</i>, <i>Spherodus cinctus</i>, <i>Notidanus
+primigenius</i>, and others.</p>
+
+<p><i>Lisbon.</i>&mdash;Marine tertiary strata near Lisbon contain shells which agree
+very closely with those of Bordeaux, and are therefore referred to the
+Miocene era. Thus, out of 112 species collected by Mr. Smith of Jordanhill,
+between 60 and 70 were found to be common to the strata of Bordeaux and
+Dax, the recent species being in the proportion of 21 per cent.</p>
+
+<p><i>Older Pliocene and Miocene formations in the United States.</i>&mdash;Between the
+Alleghany mountains, formed of older rocks, and the Atlantic, there
+intervenes, in the United States, a low region occupied principally by beds
+of marl, clay, and sand, consisting of the cretaceous and tertiary
+formations, and chiefly of the latter. The general elevation <span class="pagenum"><a id="page172"></a>[p.172]</span>of
+this plain bordering the Atlantic does not exceed 100 feet, although it is
+sometimes several hundred feet high. Its width in the middle and southern
+states is very commonly from 100 to 150 miles. It consists, in the South,
+as in Georgia, Alabama, and South Carolina, almost exclusively of Eocene
+deposits; but in North Carolina, Maryland, Virginia, and Delaware, more
+modern strata predominate, which I have assimilated in age to the English
+crag and Faluns of Touraine.<a name="FNanchor_P_5" id="FNanchor_P_5"></a><a href="#Footnote_P_5" class="fnanchor">[172-A]</a> If, chronologically speaking, they can
+be truly said to be the representatives of these two European formations,
+they may range in age from the Older Pliocene to the Miocene epoch,
+according to the classification of European strata adopted in this chapter.</p>
+
+<p>The proportion of fossil shells agreeing with recent, out of 147 species
+collected by me, amounted to about 17 per cent., or one-sixth of the whole;
+but as the fossils so assimilated were almost always the same as species
+now living in the neighbouring Atlantic, the number may hereafter be
+augmented, when the recent fauna of that ocean is better known. In
+different localities, also, the proportion of recent species varied
+considerably.</p>
+
+<a id="img153" name="img153"></a>
+<div class="floatleft smaller width300">
+<p>Fig. 151.</p>
+<img src="images/img153.jpg" width="300" height="267" alt="" title="">
+<p><i>Fulgur canaliculatus</i><span class="wosp05">. Maryland.</span></p></div>
+
+<a id="img154" name="img154"></a>
+<div class="floatright smaller width200">
+<p>Fig. 152.</p>
+<img src="images/img154.jpg" width="200" height="231" alt="" title="">
+<p><i>Fusus quadricostatus</i>, <span class="wosp05">Say. Maryland.</span></p></div>
+
+<p class="nofloat">On the banks of the James River, in Virginia, about 20 miles below
+Richmond, in a cliff about 30 feet high, I observed yellow and white sands
+overlying an Eocene marl, just as the yellow sands of the crag lie on the
+blue London clay in Suffolk and Essex in England. In the Virginian sands,
+we find a profusion of an Astarte (<i>A. undulata</i>, Conrad), which resembles
+closely, and may possibly be a variety of, one of the commonest fossils of
+the Suffolk crag (<i>A. bipartita</i>); the other shells also, of the genera
+<i>Natica</i>, <i>Fissurella</i>, <i>Artemis</i>, <i>Lucina</i>, <i>Chama</i>, <i>Pectunculus</i>, and
+<i>Pecten</i>, are analogous to shells both of the English crag and French
+faluns, although the species are almost all distinct. Out of 147 of these
+American fossils I could only find 13 species common to Europe, and these
+occur partly in the Suffolk crag, and partly in the faluns of Touraine; but
+it is an important characteristic of the American group, that it not only
+contains many peculiar extinct forms, such as <i>Fusus quadricostatus</i>, Say
+(see <a href="#img154">fig. 152.</a>), and <i>Venus tridacnoides</i>, <span class="pagenum"><a id="page173"></a>[p.173]</span>abundant in these same
+formations, but also some shells which, like <i>Fulgur carica</i> of Say, and
+<i>F. canaliculatus</i> (see <a href="#img153">fig. 151.</a>), <i>Calyptr�a costata</i>, <i>Venus
+mercenaria</i>, Lam., <i>Modiola glandula</i>, Totten, and <i>Pecten magellanicus</i>,
+Lam., are recent species, yet of forms now confined to the western side of
+the Atlantic, a fact implying that the beginning of the present
+geographical distribution of mollusca dates back to a period as remote as
+that of the Miocene strata.</p>
+
+<p>Of ten species of zoophytes which I procured on the banks of the James
+River, two were identical with species of the Faluns of Touraine. With
+respect to climate, Mr. Lonsdale regards these corals as indicating a
+temperature exceeding that of the Mediterranean, and the shells would lead
+to similar conclusions. Those occurring on the James River are in the 37th
+degree of N. latitude, while the French faluns are in the 47th; yet the
+forms of the American fossils would scarcely imply so warm a climate as
+must have prevailed in France, when the Miocene strata of Touraine
+originated.</p>
+
+<p>Among the remains of fish in these Post-Eocene strata of the United States
+are several large teeth of the shark family, not distinguishable
+specifically from fossils of the faluns of Touraine, and the Maltese
+tertiaries.</p>
+
+<p><i>India.</i>&mdash;The freshwater deposits of the Sub-Himalayan or Sew�lik Hills,
+described by Dr. Falconer and Captain Cautley, may perhaps be regarded as
+Miocene. Like the faluns of Touraine, they contain the Deinotherium and
+Mastodon. Whether any of the associated freshwater and land shells are of
+recent species is not yet determined. The occurrence in them of a fossil
+giraffe and hippopotamus, genera now only living in Africa, as well as of a
+camel, implies a geographical state of things very different from that now
+established in the same parts of India. The huge Sivatherium of the same
+era appears to have been a ruminating quadruped bigger than the rhinoceros,
+and provided with a large upper lip, or probably a short proboscis, and
+having two pair of horns, resembling those of antelopes. Several species of
+monkey belonged to the same fauna; and among the reptiles, several
+crocodiles, larger than any now living, and an enormous tortoise, <i>Testudo
+Atlas</i>, the curved shell of which measured 20 feet across.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page174"></a>[p.174]</span>CHAPTER XV.</h2>
+
+<h4>UPPER EOCENE FORMATIONS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Eocene areas in England and France &mdash; Tabular view of French Eocene
+strata &mdash; Upper Eocene group of the Paris basin &mdash; Same beds in
+Belgium and at Berlin &mdash; Mayence tertiary strata &mdash; Freshwater upper
+Eocene of Central France &mdash; Series of geographical changes since the
+land emerged in Auvergne &mdash; Mineral character an uncertain test of
+age &mdash; Marls containing Cypris &mdash; Oolite of Eocene
+period &mdash; Indusial limestone and its origin &mdash; Fossil mammalia of the
+upper Eocene strata in Auvergne &mdash; Freshwater strata of the Cantal,
+calcareous and siliceous &mdash; Its resemblance to chalk &mdash; Proofs of
+gradual deposition of strata.</p></div>
+
+
+<a id="img155" name="img155"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 153. Map of the principal tertiary basins of the Eocene
+period.</p>
+<img src="images/img155.jpg" width="450" height="342" alt="" title="">
+<p>N. B. The space left blank is occupied by secondary formations from the
+Devonian or old red sandstone to the chalk inclusive.</p></div>
+
+<p><span class="smcap">The</span> tertiary strata described in the preceding chapters are all of them
+characterized by fossil shells, of which a considerable proportion are
+specifically identical with the living mollusca; and the greater the
+number, the more nearly does the entire fauna approach in species and
+genera to that now inhabiting the adjoining seas. But in the Eocene
+formations next to be considered, the proportion of recent species is very
+small, and sometimes scarcely appreciable, and those agreeing with the
+fossil testacea often belong to remote parts of the globe, and to various
+zoological provinces. This difference in conchological character implies a
+considerable interval of time between the Eocene and Miocene periods,
+during which the whole fauna and flora underwent other changes as great,
+and often greater, than those exhibited by the mollusca. In the
+accompanying map, the position of several Eocene areas is pointed out, such
+as the basin of the Thames, <span class="pagenum"><a id="page175"></a>[p.175]</span>part of Hampshire, part of the
+Netherlands, and the country round Paris. The deposits, however, occupying
+these spaces comprise a great succession of marine and freshwater
+formations, which, although they may all be termed Eocene, as being newer
+than the chalk, and older than the faluns, are nevertheless divisible into
+separate groups, of high geological importance.</p>
+
+<p>The newest of these, like the Faluns of the Loire, have no true
+representatives, or exact chronological equivalents, in the British Isles.
+Their place in the series will best be understood by referring to the order
+of superposition of the successive deposits found in the neighbourhood of
+Paris. The area which has been called the Paris basin is about 180 miles in
+its greatest length from north-east to south-west, and about 90 miles from
+east to west. This space may be described as a depression in the chalk,
+which has been filled up by alternating groups of marine and freshwater
+strata. MM. Cuvier and Brongniart attempted, in 1810, to distinguish five
+different formations, comprising three freshwater and two marine, which
+alternated with each other. It was imagined that the waters of the ocean
+had been by turns admitted and excluded from the same region; but the
+subsequent investigations of several geologists, especially of M. Constant
+Prevost,<a name="FNanchor_Q_1" id="FNanchor_Q_1"></a><a href="#Footnote_Q_1" class="fnanchor">[175-A]</a> have led to great modifications in these theoretical views;
+and now that the true order of succession is better understood, it appears
+that several of the deposits, which were supposed to have originated one
+after the other, were, in fact, in progress at the same time by the joint
+action of the sea and rivers.</p>
+
+<p>The whole series of strata may be divided into three groups, as expressed
+in the following table:&mdash;</p>
+
+
+<table  border="0" cellpadding="2" summary="SERIES OF STRATA MAY BE DIVIDED INTO THREE GROUPS.">
+<colgroup>
+    <col width="20%">
+    <col width="10%">
+    <col width="10%">
+    <col width="60%">
+</colgroup>
+
+<tr>
+  <td rowspan="2" class="td-left tdtx-mid" style="padding-top: 1.5em;">1. Upper Eocene</td>
+  <td rowspan="2" valign="middle" style="white-space: nowrap; font-size: 50pt; font-weight: 600;" class="td-mous">{</td>
+  <td rowspan="8">&nbsp;</td>
+  <td class="td-left tdtx-mid"><i>a.</i> Upper freshwater limestone, marls, and siliceous millstone.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>b.</i> Upper marine sands, or Fontainebleau sandstone and sand.</td>
+</tr>
+
+<tr>
+  <td rowspan="4" class="td-left tdtx-mid" style="padding-top: 2.5em;">2. Middle Eocene</td>
+  <td rowspan="4" valign="middle" style="white-space: nowrap; font-size: 100pt; font-weight: 100;" class="td-mous tdtx-top">{</td>
+  <td class="td-left tdtx-mid"><i>a.</i> Lower freshwater limestone and marl, or gypseous series.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>b.</i> Sandstone and sands with marine shells (<i>Sables moyens</i>,
+  or <i>gr�s de Beauchamp</i>).</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>c.</i> Calcaire grossier, limestone with marine shells.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>d.</i> Calcaire siliceux, hard siliceous freshwater limestone,
+  for the most part contemporaneous with <i>c</i>.</td>
+</tr>
+
+<tr>
+  <td rowspan="2" class="td-left tdtx-mid" style="padding-top: 1.5em;">3. Lower Eocene</td>
+  <td rowspan="2" valign="middle" style="white-space: nowrap; font-size: 50pt; font-weight: 600;" class="tdtx-top">{</td>
+  <td class="td-left tdtx-mid"><i>a.</i> Lower sands with marine shelly beds (<i>Sables inf�rieurs
+  et lits coquilliers</i>).</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>b.</i> Lower sands, with lignite and plastic clay (<i>Sables
+  inf�rieurs et argiles plastiques</i>).</td>
+</tr>
+</table>
+
+
+<p>Postponing to the next chapter the consideration of the Middle and Lower
+Eocene groups, I shall now speak of the Upper Eocene of Paris, and its
+foreign equivalents.</p>
+
+<p>The upper freshwater marls and limestone (1. <i>a</i>) seem to have been formed
+in a great number of marshes and shallow lakes, such as frequently
+overspread the newest parts of great deltas. It appears that many layers of
+marl, tufaceous limestone, and travertin, with <span class="pagenum"><a id="page176"></a>[p.176]</span>beds of flint,
+continuous or in nodules, accumulated in these lakes. <i>Char�</i>, aquatic
+plants, already alluded to (see <a href="#page32">p. 32.</a>) left their stems and seed-vessels
+imbedded both in the marl and flint, together with freshwater and land
+shells. Some of the siliceous rocks of this formation are used extensively
+for millstones. The flat summits or platforms of the hills round Paris,
+large areas in the forest of Fontainebleau, and the Plateau de la Beauce,
+between the Seine and the Loire, are chiefly composed of these upper
+freshwater strata.</p>
+
+<p>The upper marine sands (1. <i>b</i>), consist chiefly of micaceous and quartzose
+sands, 80 feet thick. As they succeed throughout an extensive area deposit
+of a purely freshwater origin (2 <i>a</i>.), they appear to mark a subsidence of
+the subjacent soil, whether it had formed the bottom of an estuary or a
+lake. The sea, which afterwards took possession of the same space, was
+inhabited by testacea, almost all of them differing from those found in the
+lower formations (2. <i>b</i> and 2. <i>c</i>) and equally or still more distinct
+from the Miocene Faluns of subsequent date. One of these upper Eocene
+strata in the neighbourhood of Paris has been called the oyster bed,
+"couche � <i>Ostrea cyathula</i>, Lamk.," which is spread over a remarkably wide
+area. From the manner in which the oysters lie, it is inferred that they
+did not grow on the spot, but that some current swept them away from a bed
+of oysters formed in some other part of the bay. The strata of sand which
+immediately repose on the oyster-bed are quite destitute of organic
+remains; and nothing is more common in the Paris basin, and in other
+formations, than alternations of shelly beds with others entirely devoid of
+them. The temporary extinction and renewal of animal life at successive
+periods have been rashly inferred from such phenomena, which may
+nevertheless be explained, as M. Prevost justly remarks, without appealing
+to any such extraordinary revolutions in the state of the animate creation.
+A current one day scoops out a channel in a bed of shelly sand and mud, and
+the next day, by a slight alteration of its course, ceases to prey upon the
+same bank. It may then become charged with sand unmixed with shells,
+derived from some dune, or brought down by a river. In the course of ages
+an indefinite number of transitions from shelly strata to those without
+shells may thus be caused.</p>
+
+<p>Besides these oysters, M. Deshayes has described 29 species of shells, in
+his work (Coquilles fossiles de Paris), as belonging to this formation, all
+save one regarded by him as differing from fossils of the calcaire
+grossier. Since that time the railway cuttings near Etampes have enabled M.
+H�bert to raise the number to 90. I have myself collected fossils in that
+district, where the shells are very entire, and detachable from the yellow
+sandy matrix. M. H�bert first pointed out that most of them agree
+specifically with those of Kleyn Spauwen, Boom, and other localities of
+Limburg in Flanders, where they have been studied by MM. Nyst and De
+Koninck.<a name="FNanchor_Q_2" id="FNanchor_Q_2"></a><a href="#Footnote_Q_2" class="fnanchor">[176-A]</a></p>
+
+<p>The position in Belgium of this formation above the older Eocene <span class="pagenum"><a id="page177"></a>[p.177]</span>
+group is well seen in the small hill of Pellenberg, rising abruptly from
+the great plain, half a mile south-east of the city of Louvain, where I
+examined it in company with M. Nyst in 1850. At the top of the hill, a thin
+bed of dark greyish green tile-clay is seen 1<span class="smaller"><sup>1</sup>/<sub>2</sub></span> foot thick, with casts of
+<i>Nucula Deshaysiana</i>. This clay rests on 12 feet of yellow sand, separated,
+by a band of flint and quartz pebbles, from a mass of subjacent white sand
+15 feet thick, in which casts of the Kleyn Spauwen fossils have been met
+with. Under this is a bed of yellow sand 12 feet thick, and, at a lower
+level, the railway cuttings have passed through calcareous sands like those
+of Brussels, in which the <i>Nautilus Burtini</i>, and various shells common to
+the older Eocene strata of the neighbourhood of London, have been obtained.
+Every new fact which throws light on the true paleontological relations of
+the strata now under consideration, (the Upper Marine or Fontainebleau beds
+of the Paris basin, 1. <i>b</i>, <a href="#page175">p. 175.</a>), deserves more particular attention,
+because geologists of high authority differ in opinion as to whether they
+should be classed as Eocene or Miocene.</p>
+
+<p>Professor Beyrich has lately described a formation of the same age,
+occurring within 7 miles of the gates of Berlin, near the village of
+Hermsdorf, where, in the midst of the sands of which that country chiefly
+consists, a mass of tile-clay, more than 40 feet thick, and of a dark
+blueish grey colour, is found, full of shells, among which the genera
+<i>Fusus</i> and <i>Pleurotoma</i> predominate, and among the bivalves, <i>Nucula
+Deshaysiana</i>, Nyst, an extremely common shell in the Belgian beds
+above-mentioned. M. Beyrich has identified eighteen out of forty-five
+species of the Hermsdorf fossils with the Belgian species; and I believe
+that a much larger proportion agree with the Upper Eocene of Belgium,
+France, and the Rhine. On the other hand, eight of the forty-five species
+are supposed by him to agree with English Eocene shells. Messrs. Morris,
+Edwards, and S. Wood have compared a small collection, which I obtained of
+these Berlin shells, with the Eocene fossils of their museums, and
+confirmed the result of M. Beyrich, the species common to the English
+fossils belonging not simply to the uppermost of our marine beds, or those
+of Barton, but some of them to lower parts of the series, such as
+Bracklesham and Highgate. On the other hand, while these testacea, like
+those of Kleyn Spauwen and Etampes, present many analogies to the Middle
+and Lower Eocene group, they differ widely from the Falun shells,&mdash;a fact
+the more important in reference to Etampes, as that locality approaches
+within 70 miles of Pontlevoy, near Blois, and within 100 miles of Savign�,
+near Tours, where Falun shells are found. It is evident that the
+discordance of species cannot be attributed to distance or geographical
+causes, but must be referred to time, or the different epoch at which the
+upper marine beds of the Paris basin and the Faluns of the Loire
+originated.</p>
+
+<p><i>Mayence.</i>&mdash;The true chronological relation of many tertiary strata on the
+banks of the Rhine has always presented a problem of considerable
+difficulty. They occupy a tract from 5 to 12 miles in breadth, extending
+along the left bank of the Rhine from Mayence <span class="pagenum"><a id="page178"></a>[p.178]</span>to the
+neighbourhood of Manheim, and are again found to the east, north, and
+south-west of Frankfort. In some places they have the appearance of a
+freshwater formation; but in others, as at Alzey, the shells are for the
+most part marine. <i>Cerithia</i> are in great profusion, which indicates that
+the sea where the deposit was formed was fed by rivers; and the great
+quantity of fossil land shells, chiefly of the genus <i>Helix</i>, confirm the
+same opinion. The variety in the species of shells is small, while the
+individuals are exceedingly numerous; a fact which accords perfectly with
+the idea that the formation may have originated in a gulf or sea which,
+like the Baltic, was brackish in some parts, and almost fresh in others. A
+species of <i>Paludina</i> (<a href="#img156">fig. 154.</a>), very nearly resembling the recent
+<i>Littorina ulva</i>, is found throughout this basin. These shells are like
+grains of rice in size, and are often in such quantity as to form entire
+beds of marl and limestone. They are as thick as grains of sand, in
+stratified masses from 15 to 30 feet in thickness.</p>
+
+<a id="img156" name="img156"></a>
+<div class="floatright smaller width150">
+<p>Fig. 154.</p>
+<img src="images/img156.jpg" width="150" height="179" alt="" title="">
+<p><i>Paludina.</i> Mayence.</p></div>
+
+<p>That these Rhenish tertiary formations agree more nearly with the Upper
+Eocene deposits above enumerated, than with any others, I have no doubt,
+since I had the advantage of comparing (August, 1850), with the assistance
+of M. De Koninck of Li�ge, the fossils from Kleyn Spauwen, Boom, and other
+Limburg localities, with those from Mayence, Alzey, Weinheim, and other
+Rhenish strata. Among the common Belgian and Rhenish shells which are
+identical, I may mention <i>Cassidaria depressa</i>, <i>Tritonium flandricum</i> De
+Koninck, <i>Cerithium tricinctum</i> Nyst, <i>Tornatella simulata</i>, <i>Rostellaria
+Sowerbyi</i>, <i>Nucula Deshaysiana</i>, <i>Corbula pisum</i>, and <i>Pectunculus
+terebratularis</i>.</p>
+
+<p>From these Upper Eocene deposits of the Rhine M. H. von Meyer has obtained
+a great number of characteristic fossil mammalia, such as <i>Pal�om�ryx
+medius</i>, <i>Hyotherium Meissneri</i>, <i>Tapirus Helveticus</i>, <i>Anthracotherium
+Alsaticum</i>, and others. The three first of these are species common to some
+of the lignite, or brown coal beds in Switzerland, commonly classed with
+the molasse, but of which the true age has not yet been distinctly made
+out.</p>
+
+<p>The fossils of the sandy beds of Eppelsheim, comprising bones of the
+Deinotherium, Mastodon, and other quadrupeds, are regarded by H. von Meyer
+as belonging to a mammiferous fauna quite distinct from that of the Mayence
+basin, and they are probably referable to the Miocene period.</p>
+
+<p>The upper freshwater strata (1. <i>a</i>, <a href="#page175">p. 175.</a>), of the neighbourhood of
+Paris, stretch southwards from the valley of the Seine to that of the
+Loire, and in the last-mentioned region are seen to be older than the
+marine faluns, so that the perforating shells of the Miocene sea have
+sometimes bored the hard compact freshwater limestones; and fragments of
+the Upper Eocene rocks are found at Pontlevoy and elsewhere, which have
+been rolled in the bed of the Miocene sea.</p>
+
+<a id="img157" name="img157"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 155.</p>
+<img src="images/img157.jpg" width="336" height="600" alt="" title=""></div>
+
+<p><i>Central France.</i>&mdash;Lacustrine strata belonging, for the most part, to the
+same Upper Eocene series, are again met with in Auvergne, Cantal, and
+Velay, the sites of which may be seen in the annexed <span class="pagenum"><a id="page179"></a>[p.179]</span>map. They
+appear to be the monuments of ancient lakes, which, like some of those now
+existing in Switzerland, once occupied the depressions in a mountainous
+region, and have been each fed by one or more rivers and torrents. The
+country where they occur is almost <span class="pagenum"><a id="page180"></a>[p.180]</span>entirely composed of granite
+and different varieties of granitic schist, with here and there a few
+patches of secondary strata, much dislocated, and which have probably
+suffered great denudation. There are also some vast piles of volcanic
+matter (see the map), the greater part of which is newer than the
+freshwater strata, and is sometimes seen to rest upon them, while a small
+part has evidently been of contemporaneous origin. Of these igneous rocks I
+shall treat more particularly in another part of this work.</p>
+
+<p>Before entering upon any details, I may observe, that the study of these
+regions possesses a peculiar interest, very distinct in kind from that
+derivable from the investigation either of the Parisian or English tertiary
+strata. For we are presented in Auvergne with the evidence of a series of
+events of astonishing magnitude and grandeur, by which the original form
+and features of the country have been greatly changed, yet never so far
+obliterated but that they may still, in part at least, be restored in
+imagination. Great lakes have disappeared,&mdash;lofty mountains have been
+formed, by the reiterated emission of lava, preceded and followed by
+showers of sand and scori�,&mdash;deep valleys have been subsequently furrowed
+out through masses of lacustrine and volcanic origin,&mdash;at a still later
+date, new cones have been thrown up in these valleys,&mdash;new lakes have been
+formed by the damming up of rivers,&mdash;and more than one creation of
+quadrupeds, birds, and plants, Eocene, Miocene, and Pliocene, have followed
+in succession; yet the region has preserved from first to last its
+geographical identity; and we can still recall to our thoughts its external
+condition and physical structure before these wonderful vicissitudes began,
+or while a part only of the whole had been completed. There was first a
+period when the spacious lakes, of which we still may trace the boundaries,
+lay at the foot of mountains of moderate elevation, unbroken by the bold
+peaks and precipices of Mont Dor, and unadorned by the picturesque outline
+of the Puy de Dome, or of the volcanic cones and craters now covering the
+granitic platform. During this earlier scene of repose deltas were slowly
+formed; beds of marl and sand, several hundred feet thick, deposited;
+siliceous and calcareous rocks precipitated from the waters of mineral
+springs; shells and insects imbedded, together with the remains of the
+crocodile and tortoise, the eggs and bones of water birds, and the
+skeletons of quadrupeds, some of them belonging to the same genera as those
+entombed in the Eocene gypsum of Paris. To this tranquil condition of the
+surface succeeded the era of volcanic eruptions, when the lakes were
+drained, and when the fertility of the mountainous district was probably
+enhanced by the igneous matter ejected from below, and poured down upon the
+more sterile granite. During these eruptions, which appear to have taken
+place after the disappearance of the Eocene fauna, and in the Miocene
+epoch, the mastodon, rhinoceros, elephant, tapir, hippopotamus, together
+with the ox, various kinds of deer, the bear, hy�na, and many beasts of
+prey, ranged the forest, or pastured on the plain, and were occasionally
+overtaken by a fall of burning cinders, or buried in flows of mud, such as
+accompany <span class="pagenum"><a id="page181"></a>[p.181]</span>volcanic eruptions. Lastly, these quadrupeds became
+extinct, and gave place to Pliocene mammalia, and these, in their turn, to
+species now existing. There are no signs, during the whole time required
+for this series of events, of the sea having intervened, nor of any
+denudation which may not have been accomplished by currents in the
+different lakes, or by rivers and floods accompanying repeated earthquakes,
+during which the levels of the district have in some places been materially
+modified, and perhaps the whole upraised relatively to the surrounding
+parts of France.</p>
+
+<p><i>Auvergne.</i>&mdash;The most northern of the freshwater groups is situated in the
+valley-plain of the Allier, which lies within the department of the Puy de
+Dome, being the tract which went formerly by the name of the Limagne
+d'Auvergne. It is inclosed by two parallel mountain ranges,&mdash;that of the
+For�z, which divides the waters of the Loire and Allier, on the east; and
+that of the Monts Domes, which separates the Allier from the Sioule, on the
+west.<a name="FNanchor_Q_3" id="FNanchor_Q_3"></a><a href="#Footnote_Q_3" class="fnanchor">[181-A]</a> The average breadth of this tract is about 20 miles; and it is
+for the most part composed of nearly horizontal strata of sand, sandstone,
+calcareous marl, clay, and limestone, none of which observe a fixed and
+invariable order of superposition. The ancient borders of the lake, wherein
+the freshwater strata were accumulated, may generally be traced with
+precision, the granite and other ancient rocks rising up boldly from the
+level country. The actual junction, however, of the lacustrine and granitic
+beds is rarely seen, as a small valley usually intervenes between them. The
+freshwater strata may sometimes be seen to retain their horizontality
+within a very slight distance of the border-rocks, while in some places
+they are inclined, and in few instances vertical. The principal divisions
+into which the lacustrine series may be separated are the following:&mdash;1st,
+Sandstone, grit, and conglomerate, including red marl and red sandstone.
+2dly, Green and white foliated marls. 3dly, Limestone or travertin, often
+oolitic. 4thly, Gypseous marls.</p>
+
+<p>1. <i>a</i>. <i>Sandstone and conglomerate.</i>&mdash;Strata of sand and gravel, sometimes
+bound together into a solid rock, are found in great abundance around the
+confines of the lacustrine basin, containing, in different places, pebbles
+of all the ancient rocks of the adjoining elevated country; namely,
+granite, gneiss, mica-schist, clay-slate, porphyry, and others. But these
+strata do not form one continuous band around the margin of the basin,
+being rather disposed like the independent deltas which grow at the mouths
+of torrents along the borders of existing lakes.</p>
+
+<p>At Chamalieres, near Clermont, we have an example of one of these deltas,
+or littoral deposits, of local extent, where the pebbly beds slope away
+from the granite, as if they had formed a talus beneath the waters of the
+lake near the steep shore. A section of about 50 feet in vertical height
+has been laid open by a torrent, and the pebbles are seen to consist
+throughout of rounded and <span class="pagenum"><a id="page182"></a>[p.182]</span>angular fragments of granite, quartz,
+primary slate, and red sandstone; but without any intermixture of those
+volcanic rocks which now abound in the neighbourhood, and which could not
+have been there when the conglomerate was formed. Partial layers of lignite
+and pieces of wood are found in these beds.</p>
+
+<p>At some localities on the margin of the basin quartzose grits are found;
+and, where these rest on granite, they are sometimes formed of separate
+crystals of quartz, mica, and felspar, derived from the disintegrated
+granite, the crystals having been subsequently bound together by a
+siliceous cement. In these cases the granite seems regenerated in a new and
+more solid form; and so gradual a passage takes place between the rock of
+crystalline and that of mechanical origin, that we can scarcely distinguish
+where one ends and the other begins.</p>
+
+<p>In the hills called the Puy de Jussat and La Roche, we have the advantage
+of seeing a section continuously exposed for about 700 feet in thickness.
+At the bottom are foliated marls, white and green, about 400 feet thick;
+and above, resting on the marls, are the quartzose grits, cemented by
+calcareous matter, which is sometimes so abundant as to form imbedded
+nodules. These sometimes constitute spheroidal concretions 6 feet in
+diameter, and pass into beds of solid limestone, resembling the Italian
+travertins, or the deposits of mineral springs. This section is close to
+the confines of the basin; so that the lake must here have been filled up
+near the shore with fine mud, before the coarse superincumbent sand was
+introduced. There are other cases where sand is seen below the marl.</p>
+
+<p>1. <i>b.</i> <i>Red marl and sandstone</i>.&mdash;But the most remarkable of the
+arenaceous groups is one of red sandstone and red marl, which are identical
+in all their mineral characters with the secondary <i>New Red sandstone</i> and
+marl of England. In these secondary rocks the red ground is sometimes
+variegated with light greenish spots, and the same may be seen in the
+tertiary formation of freshwater origin at Coudes, on the Allier. The marls
+are sometimes of a purplish-red colour, as at Champheix, and are
+accompanied by a reddish limestone, like the well-known "cornstone," which
+is associated with the Old Red sandstone of English geologists. The red
+sandstone and marl of Auvergne have evidently been derived from the
+degradation of gneiss and mica-schist, which are seen <i>in situ</i> on the
+adjoining hills, decomposing into a soil very similar to the tertiary red
+sand and marl. We also find pebbles of gneiss, mica-schist, and quartz in
+the coarser sandstones of this group, clearly pointing to the parent rocks
+from which the sand and marl are derived. The red beds, although destitute
+themselves of organic remains, pass upwards into strata containing Eocene
+fossils, and are certainly an integral part of the lacustrine formation.
+From this example the student will learn how small is the value of mineral
+character alone, as a test of the relative age of rocks.</p>
+
+<p>2. <i>Green and white foliated marls.</i>&mdash;The same primary rocks of Auvergne,
+which, by the partial degradation of their harder parts, <span class="pagenum"><a id="page183"></a>[p.183]</span>gave
+rise to the quartzose grits and conglomerates before mentioned, would, by
+the reduction of the same materials into powder, and by the decomposition
+of their felspar, mica, and hornblende, produce aluminous clay, and, if a
+sufficient quantity of carbonate of lime was present, calcareous marl. This
+fine sediment would naturally be carried out to a greater distance from the
+shore, as are the various finer marls now deposited in Lake Superior. And,
+as in the American lake, shingle and sand are annually amassed near the
+northern shores, so in Auvergne the grits and conglomerates before
+mentioned were evidently formed near the borders.</p>
+
+<a id="img158" name="img158"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 156.</p>
+<img src="images/img158.jpg" width="350" height="332" alt="" title="">
+<p><i>Cypris unifasciata</i>, a living species, greatly magnified.</p>
+<ul class="leftal martopm05 add1em">
+<li><i>a.</i> Upper part.</li>
+<li><i>b.</i> Side view of the same.</li>
+</ul></div>
+
+<a id="img159" name="img159"></a>
+<div class="figcenter width300 smaller">
+<p class="martop2">Fig. 157.</p>
+<img src="images/img159.jpg" width="300" height="245" alt="" title="">
+<p><i>Cypris vidua</i>, a living species, greatly
+magnified.<a name="FNanchor_Q_4" id="FNanchor_Q_4"></a><a href="#Footnote_Q_4" class="fnanchor">[183-A]</a></p></div>
+
+<p>The entire thickness of these marls is unknown; but it certainly exceeds,
+in some places, 700 feet. They are, for the most part, either light-green
+or white, and usually calcareous. They are thinly foliated,&mdash;a character
+which frequently arises from the innumerable thin shells, or
+carapace-valves, of that small animal called <i>Cypris</i>; a genus which
+comprises several species, of which some are recent, and may be seen
+swimming swiftly through the waters of our stagnant pools and ditches. The
+antenn�, at the end of which are fine pencils of hair, are the principal
+organs of motion, and are seen to vibrate with great rapidity. This animal
+resides within two small valves, not unlike those of a bivalve shell, and
+moults its integuments periodically, which the conchiferous mollusks do
+not. This circumstance may partly explain the countless myriads of the
+shells of <i>Cypris</i> which were shed in the ancient lakes of Auvergne, so as
+to give rise to divisions in the marl as thin as paper, and that, too, in
+stratified masses several hundred feet thick. A more convincing proof of
+the tranquillity and clearness of the waters, and of the slow and gradual
+process by which the lake was filled up with fine mud, cannot be desired.
+But we may easily suppose that, while this fine sediment was thrown down in
+the deep and central parts of the basin, gravel, sand, and rocky fragments
+were hurried into the lake, and deposited near the shore, forming the group
+described in the preceding section.</p>
+
+<p><span class="pagenum"><a id="page184"></a>[p.184]</span>Not far from Clermont, the green marls, containing the <i>Cypris</i> in
+abundance, approach to within a few yards of the granite which forms the
+borders of the basin. The occurrence of these marls so near the ancient
+margin may be explained by considering that, at the bottom of the ancient
+lake, no coarse ingredients were deposited in spaces intermediate between
+the points where rivers and torrents entered, but finer mud only was
+drifted there by currents. The <i>verticality</i> of some of the beds in the
+above section bears testimony to considerable local disturbance subsequent
+to the deposition of the marls; but such inclined and vertical strata are
+very rare.</p>
+
+<a id="img160" name="img160"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 158.</p>
+<img src="images/img160.jpg" width="450" height="148" alt="" title="">
+<p>Vertical strata of marl, at Champradelle, near Clermont.</p>
+<ul class="martopm05 leftal smaller add1em min1em">
+<li>A. Granite.</li>
+<li>B. Space of 60 feet, in which no section is seen.</li>
+<li>C. Green marl, vertical and inclined.</li>
+<li>D. White marl.</li>
+</ul></div>
+
+<p>3. <i>Limestone, travertin, oolite.</i>&mdash;Both the preceding members of the
+lacustrine deposit, the marls and grits, pass occasionally into limestone.
+Sometimes only concretionary nodules abound in them; but these, where there
+is an increase in the quantity of calcareous matter, unite into regular
+beds.</p>
+
+<p>On each side of the basin of the Limagne, both on the west at Gannat, and
+on the east at Vichy, a white oolitic limestone is quarried. At Vichy, the
+oolite resembles our Bath stone in appearance and beauty; and, like it, is
+soft when first taken from the quarry, but soon hardens on exposure to the
+air. At Gannat, the stone contains land-shells and bones of quadrupeds,
+resembling those of the Paris gypsum. At Chadrat, in the hill of La Serre,
+the limestone is pisolitic, the small spheroids combining both the radiated
+and concentric structure.</p>
+
+<p><i>Indusial limestone.</i>&mdash;There is another remarkable form of freshwater
+limestone in Auvergne, called "indusial," from the cases, or <i>indusi�</i>, of
+caddis-worms (the larv� of <i>Phryganea</i>); great heaps of which have been
+incrusted, as they lay, by carbonate of lime, and formed into a hard
+travertin. The rock is sometimes purely calcareous, but there is
+occasionally an intermixture of siliceous matter. Several beds of it are
+frequently seen, either in continuous masses, or in concretionary nodules,
+one upon another, with layers of marl interposed. The annexed drawing (<a href="#img161">fig.
+159.</a>) will show the manner in which one of these indusial beds (<i>a</i>) is
+laid open at the surface, between the marls (<i>b b</i>), near the base of the
+hill of Gergovia; and affords, at the same time, an example of the extent
+to which the lacustrine strata, which must once have filled a hollow, have
+been denuded, and shaped out into hills and valleys, on the site of the
+ancient lakes.</p>
+
+<span class="pagenum"><a id="page185"></a>[p.185]</span>
+<a id="img161" name="img161"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 159.</p>
+<img src="images/img161.jpg" width="450" height="451" alt="" title="">
+<p>Bed of indusial limestone, interstratified with freshwater marl, near
+Clermont (Kleinschrod.)</p></div>
+
+<a id="img162" name="img162"></a>
+<div class="figcenter smaller width200">
+<p class="martop2">Fig. 160.</p>
+<img src="images/img162.jpg" width="200" height="102" alt="" title="">
+<p>Larva of recent Phryganea.<a name="FNanchor_Q_5" id="FNanchor_Q_5"></a><a href="#Footnote_Q_5" class="fnanchor">[185-A]</a></p></div>
+
+<a id="img163" name="img163"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 161.</p>
+<img src="images/img163.jpg" width="350" height="153" alt="" title="">
+<ul class="smaller add1em min1em leftal">
+<li><i>a</i>. Indusial limestone of Auvergne.</li>
+<li><i>b</i>. Fossil <i>Paludina</i> magnified.</li>
+</ul></div>
+
+<p>We may often observe in our ponds the <i>Phryganea</i> (or Caddis-fly), in its
+caterpillar state, covered with small freshwater shells, which they have
+the power of fixing to the outside of their tubular cases, in order,
+probably, to give them weight and strength. The individual figured in the
+annexed cut, which belongs to a species very abundant in England, has
+covered its case with shells of a small <i>Planorbis</i>. In the same manner a
+large species of caddis-worm, which swarmed in the Eocene lakes of
+Auvergne, was accustomed to attach to its dwelling the shells of a small
+spiral univalve of the genus <i>Paludina</i>. A hundred of these minute shells
+are sometimes seen arranged around one tube, part of the central cavity of
+which is often empty, the rest being filled up with thin concentric layers
+of travertin. The cases have been thrown together confusedly, and often
+lie, as in <a href="#img163">fig. 161.</a>, <span class="pagenum"><a id="page186"></a>[p.186]</span>at right angles one to the other. When we
+consider that ten or twelve tubes are packed within the compass of a cubic
+inch, and that some single strata of this limestone are 6 feet thick, and
+may be traced over a considerable area, we may form some idea of the
+countless number of insects and mollusca which contributed their
+integuments and shells to compose this singularly constructed rock. It is
+unnecessary to suppose that the <i>Phrygane�</i> lived on the spots where their
+cases are now found; they may have multiplied in the shallows near the
+margin of the lake, or in the streams by which it was fed, and their cases
+may have been drifted by a current far into the deep water.</p>
+
+<p>In the summer of 1837, when examining, in company with Dr. Beck, a small
+lake near Copenhagen, I had an opportunity of witnessing a beautiful
+exemplification of the manner in which the tubular cases of Auvergne were
+probably accumulated. This lake, called the Fuure-Soe, occurring in the
+interior of Seeland, is about twenty English miles in circumference, and in
+some parts 200 feet in depth. Round the shallow borders an abundant crop of
+reeds and rushes may be observed, covered with the indusi� of the
+<i>Phryganea grandis</i> and other species, to which shells are attached. The
+plants which support them are the bullrush, <i>Scirpus lacustris</i>, and common
+reed, <i>Arundo phragmitis</i>, but chiefly the former. In summer, especially in
+the month of June, a violent gust of wind sometimes causes a current by
+which these plants are torn up by the roots, washed away, and floated off
+in long bands, more than a mile in length, into deep water. The <i>Cypris</i>
+swarms in the same lake; and calcareous springs alone are wanting to form
+extensive beds of indusial limestone, like those of Auvergne.</p>
+
+<p>4. <i>Gypseous marls.</i>&mdash;More than 50 feet of thinly laminated gypseous marls,
+exactly resembling those in the hill of Montmartre, at Paris, are worked
+for gypsum at St. Romain, on the right bank of the Allier. They rest on a
+series of green cypriferous marls which alternate with grit, the united
+thickness of this inferior group being seen, in a vertical section on the
+banks of the river, to exceed 250 feet.</p>
+
+<p><i>General arrangement, origin, and age of the freshwater formations of
+Auvergne.</i>&mdash;The relations of the different groups above described cannot be
+learnt by the study of any one section; and the geologist who sets out with
+the expectation of finding a fixed order of succession may perhaps complain
+that the different parts of the basin give contradictory results. The
+arenaceous division, the marls, and the limestone, may all be seen in some
+places to alternate with each other; yet it can, by no means, be affirmed
+that there is no order of arrangement. The sands, sandstone, and
+conglomerate, constitute in general a littoral group; the foliated white
+and green marls, a contemporaneous central deposit; and the limestone is
+for the most part subordinate to the newer portions of both. The uppermost
+marls and sands are more calcareous than the lower; and we never meet with
+calcareous rocks covered by a considerable thickness of quartzose sand or
+green marl. From the resemblance of the limestones to the <span class="pagenum"><a id="page187"></a>[p.187]</span>Italian
+travertins, we may conclude that they were derived from the waters of
+mineral springs,&mdash;such springs as even now exist in Auvergne, and which may
+be seen rising up through the granite, and precipitating travertin. They
+are sometimes thermal, but this character is by no means constant.</p>
+
+<p>It seems that, when the ancient lake of the Limagne first began to be
+filled with sediment, no volcanic action had yet produced lava and scori�
+on any part of the surface of Auvergne. No pebbles, therefore, of lava were
+transported into the lake,&mdash;no fragments of volcanic rocks embedded in the
+conglomerate. But at a later period, when a considerable thickness of
+sandstone and marl had accumulated, eruptions broke out, and lava and tuff
+were deposited, at some spots, alternately with the lacustrine strata. It
+is not improbable that cold and thermal springs, holding different mineral
+ingredients in solution, became more numerous during the successive
+convulsions attending this development of volcanic agency, and thus
+deposits of carbonate and sulphate of lime, silex, and other minerals were
+produced. Hence these minerals predominate in the uppermost strata. The
+subterranean movements may then have continued until they altered the
+relative levels of the country, and caused the waters of the lakes to be
+drained off, and the farther accumulation of regular freshwater strata to
+cease.</p>
+
+<p>We may easily conceive a similar series of events to give rise to analogous
+results in any modern basin, such as that of Lake Superior, for example,
+where numerous rivers and torrents are carrying down the detritus of a
+chain of mountains into the lake. The transported materials must be
+arranged according to their size and weight, the coarser near the shore,
+the finer at a greater distance from land; but in the gravelly and sandy
+beds of Lake Superior no pebbles of modern volcanic rocks can be included,
+since there are none of these at present in the district. If igneous action
+should break out in that country, and produce lava, scori�, and thermal
+springs, the deposition of gravel, sand, and marl might still continue as
+before; but, in addition, there would then be an intermixture of volcanic
+gravel and tuff, and of rocks precipitated from the waters of mineral
+springs.</p>
+
+<p>Although the freshwater strata of the Limagne approach generally to a
+horizontal position, the proofs of local disturbance are sufficiently
+numerous and violent to allow us to suppose great changes of level since
+the lacustrine period. We are unable to assign a northern barrier to the
+ancient lake, although we can still trace its limits to the east, west, and
+south, where they were formed of bold granite eminences. Nor need we be
+surprised at our inability to restore entirely the physical geography of
+the country after so great a series of volcanic eruptions; for it is by no
+means improbable that one part of it, the southern, for example, may have
+been moved upwards bodily, while others remained at rest, or even suffered
+a movement of depression.</p>
+
+<p>Whether all the freshwater formations of the Limagne d'Auvergne belong to
+one period, I cannot pretend to decide, as large masses both of the
+arenaceous and marly groups are often devoid of fossils. <span class="pagenum"><a id="page188"></a>[p.188]</span>Much
+light has been thrown on the mammiferous fauna by the labours of MM.
+Bravard and Croizet, and by those of M. Pomel. The last-mentioned
+naturalist has pointed out the specific distinction of all, or nearly all,
+the species of mammalia, from those of the gypseous series near Paris.
+Nevertheless, many of the forms are analogous to those of Eocene
+quadrupeds. The <i>Cainotherium</i>, for example, is not far removed from the
+<i>Anoplotherium</i>, and is, according to Waterhouse, the same as the genus
+<i>Microtherium</i> of the Germans. There are two species of marsupial animals
+allied to <i>Didelphys</i>, a genus also found in the Paris gypsum. The
+<i>Amphitragulus elegans</i> of Pomel, has been identified with a Rhenish
+species from Weissenau near Mayence, called by Kaup <i>Dorcatherium nanum</i>;
+and other Auvergne fossils, e.g., <i>Microtherium Reuggeri</i>, and a small
+rodent, <i>Titanomys</i>, are specifically the same with mammalia of the Mayence
+basin.</p>
+
+<p><i>Cantal.</i>&mdash;A freshwater formation, very analogous to that of Auvergne, is
+situated in the department of Haute Loire, near the town of Le Puy, in
+Velay, and another occurs near Aurillac, in Cantal. The leading feature of
+the formation last mentioned, as distinguished from those of Auvergne and
+Velay, is the immense abundance of silex associated with calcareous marls
+and limestone.</p>
+
+<p>The whole series may be separated into two divisions; the lower, composed
+of gravel, sand, and clay, such as might have been derived from the wearing
+down and decomposition of the granitic schists of the surrounding country;
+the upper system, consisting of siliceous and calcareous marls, contains
+subordinately gypsum, silex, and limestone.</p>
+
+<p>The resemblance of the freshwater limestone of the Cantal, and its
+accompanying flint, to the upper chalk of England, is very instructive, and
+well calculated to put the student upon his guard against relying too
+implicitly on mineral character alone as a safe criterion of relative age.</p>
+
+<p>When we approach Aurillac from the west, we pass over great heathy plains,
+where the sterile mica-schist is barely covered with vegetation. Near
+Ytrac, and between La Capelle and Viscamp, the surface is strewed over with
+loose broken flints, some of them black in the interior, but with a white
+external coating; others stained with tints of yellow and red, and in
+appearance precisely like the flint gravel of our chalk districts. When
+heaps of this gravel have thus announced our approach to a new formation,
+we arrive at length at the escarpment of the lacustrine beds. At the bottom
+of the hill which rises before us, we see strata of clay and sand, resting
+on mica-schist; and above, in the quarries of Belbet, Leybros, and Bruel, a
+white limestone, in horizontal strata, the surface of which has been
+hollowed out into irregular furrows, since filled up with broken flint,
+marl, and dark vegetable mound. In these cavities we recognize an exact
+counterpart to those which are so numerous on the furrowed surface of our
+own white chalk. Advancing from these quarries along a road made of the
+white limestone, which reflects as glaring a light in the sun, as do our
+roads composed of chalk, we reach, at <span class="pagenum"><a id="page189"></a>[p.189]</span>length, in the
+neighbourhood of Aurillac, hills of limestone and calcareous marl, in
+horizontal strata, separated in some places by regular layers of flint in
+nodules, the coating of each nodule being of an opaque white colour, like
+the exterior of the flinty nodules of our chalk.</p>
+
+<p>It will be remembered that the siliceous stone of Bilin, called <i>tripoli</i>,
+is a freshwater deposit, and has been shown, by Ehrenberg, to be of
+infusorial origin (see <a href="#page24">p. 24.</a>). What is true of the Bohemian flint and
+opal, where the beds attain a thickness of 14 feet, may also, perhaps, be
+found to hold good respecting the silex of Aurillac, which may also have
+been immediately derived from the minute cases of microscopic animalcules.
+But even if this conclusion be established, the abundant supply both of
+siliceous, calcareous, and gypseous matter, which the ancient lakes of
+France received, may have been connected with the subterranean volcanic
+agency of which those regions were so long the theatre, and which may have
+impregnated the springs with mineral matter, even before the great outbreak
+of lava. It is well known that the hot springs of Iceland, and many other
+countries, contain silex in solution; and it has been lately affirmed, that
+steam at a high temperature is capable of dissolving quartzose rocks
+without the aid of any alkaline or other flux.<a name="FNanchor_Q_6" id="FNanchor_Q_6"></a><a href="#Footnote_Q_6" class="fnanchor">[189-A]</a></p>
+
+<p>Travellers not unfrequently mention, in their accounts of India, Australia,
+and other distant lands, that they have seen chalk with flints, which they
+have assumed to be of the same age as the Cretaceous system of Europe. A
+hasty observation of the white limestone and flint of Aurillac might convey
+the same idea; but when we turn from the mineral aspect and composition to
+the organic remains, we find in the flints of the Cantal the seed-vessels
+of the freshwater <i>Chara</i>, instead of the marine zoophytes so abundantly
+imbedded in chalk flints; and in the limestone we meet with shells of
+<i>Limnea</i>, <i>Planorbis</i>, and other lacustrine genera, instead of the oyster,
+terebratula, and echinus of the Cretaceous period.</p>
+
+<p><i>Proofs of gradual deposition</i>.&mdash;Some sections of the foliated marls in the
+valley of the Cer, near Aurillac, attest, in the most unequivocal manner,
+the extreme slowness with which the materials of the lacustrine series were
+amassed. In the hill of Barrat, for example, we find an assemblage of
+calcareous and siliceous marls; in which, for a depth of at least 60 feet,
+the layers are so thin, that thirty are sometimes contained in the
+thickness of an inch; and when they are separated, we see preserved in
+every one of them the flattened stems of <i>Char�</i>, or other plants, or
+sometimes myriads of small <i>Paludin�</i> and other freshwater shells. These
+minute foliations of the marl resemble precisely some of the recent
+laminated beds of the Scotch marl lakes, and may be compared to the pages
+of a book, each containing a history of a certain period of the past. The
+different layers may be grouped together in beds from a foot to a foot and
+a half in thickness, which are distinguished by differences of composition
+and colour, the tints being white, green, and brown. Occasionally there
+<span class="pagenum"><a id="page190"></a>[p.190]</span>is a parting layer of pure flint, or of black carbonaceous
+vegetable matter, about an inch thick, or of white pulverulent marl. We
+find several hills in the neighbourhood of Aurillac composed of such
+materials, for the height of more than 200 feet from their base, the whole
+sometimes covered by rocky currents of trachytic or basaltic lava.<a name="FNanchor_Q_7" id="FNanchor_Q_7"></a><a href="#Footnote_Q_7" class="fnanchor">[190-A]</a></p>
+
+<p>Thus wonderfully minute are the separate parts of which some of the most
+massive geological monuments are made up! When we desire to classify, it is
+necessary to contemplate entire groups of strata in the aggregate; but if
+we wish to understand the mode of their formation, and to explain their
+origin, we must think only of the minute subdivisions of which each mass is
+composed. We must bear in mind how many thin leaf-like seams of matter,
+each containing the remains of myriads of testacea and plants, frequently
+enter into the composition of a single stratum, and how vast a succession
+of these strata unite to form a single group! We must remember, also, that
+piles of volcanic matter, like the Plomb du Cantal, which rises in the
+immediate neighbourhood of Aurillac, are themselves equally the result of
+successive accumulation, consisting of reiterated sheets of lava, showers
+of scori�, and ejected fragments of rock.&mdash;Lastly, we must not forget that
+continents and mountain-chains, colossal as are their dimensions, are
+nothing more than an assemblage of many such igneous and aqueous groups,
+formed in succession during an indefinite lapse of ages, and superimposed
+upon each other.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XVI.</h2>
+
+<h4>EOCENE FORMATIONS&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Subdivisions of the Eocene group in the Paris basin &mdash; Gypseous
+series &mdash; Extinct quadrupeds &mdash; Impulse given to geology by Cuvier's
+osteological discoveries &mdash; Shelly sands called sables
+moyens &mdash; Calcaire grossier &mdash; Miliolites &mdash; Calcaire
+siliceux &mdash; Lower Eocene in France &mdash; Lits coquilliers &mdash; Sands
+and plastic clay &mdash; English Eocene strata &mdash; Freshwater and
+fluvio-marine beds &mdash; Barton beds &mdash; Bagshot and Bracklesham
+division &mdash; Large ophidians and saurians &mdash; Lower Eocene and London
+Clay proper &mdash; Fossil plants and shells &mdash; Strata of Kyson in
+Suffolk &mdash; Fossil monkey and opossum &mdash; Mottled clays and sands below
+London Clay &mdash; Nummulitic formation of Alps and Pyrenees &mdash; Its wide
+geographical extent &mdash; Eocene strata in the United States &mdash; Section
+at Claiborne, Alabama &mdash; Colossal cetacean &mdash; Orbitoid
+limestone &mdash; Burr stone.</p></div>
+
+
+<p><span class="smcap">From</span> what was said in the two preceding chapters, it has already appeared
+that we have in England no true chronological representative of the Miocene
+faluns of the Loire, and none of the Upper Eocene group <span class="pagenum"><a id="page191"></a>[p.191]</span>described
+in the last chapter. But, when we descend to the middle and inferior
+divisions of the Eocene system of France, we find that they have their
+equivalents in Great Britain.</p>
+
+
+<h3>MIDDLE EOCENE.&mdash;FRANCE.</h3>
+
+<p><i>Gypseous series</i> (2. <i>a</i>, Table, <a href="#page175">p. 175.</a>).&mdash;Next below the upper marine
+sands of the neighbourhood of Paris, we find a series of white and green
+marls, with subordinate beds of gypsum. These are most largely developed in
+the central parts of the Paris basin, and, among other places, in the Hill
+of Montmartre, where its fossils were first studied by M. Cuvier.</p>
+
+<p>The gypsum quarried there for the manufacture of plaster of Paris occurs as
+a granular crystalline rock, and, together with the associated marls,
+contains land and fluviatile shells, together with the bones and skeletons
+of birds and quadrupeds. Several land plants are also met with, among which
+are fine specimens of the fan palm or palmetto tribe (<i>Flabellaria</i>). The
+remains also of freshwater fish and of crocodiles and other reptiles, occur
+in the gypsum. The skeletons of mammalia are usually isolated, often
+entire, the most delicate extremities being preserved; as if the carcasses,
+clothed with their flesh and skin, had been floated down soon after death,
+and while they were still swoln by the gases generated by their first
+decomposition. The few accompanying shells are of those light kinds which
+frequently float on the surface of rivers, together with wood.</p>
+
+<p>M. Prevost has therefore suggested that a river may have swept away the
+bodies of animals, and the plants which lived on its borders, or in the
+lakes which it traversed, and may have carried them down into the centre of
+the gulf into which flowed the waters impregnated with sulphate of lime. We
+know that the Fiume Salso in Sicily enters the sea so charged with various
+salts that the thirsty cattle refuse to drink of it. A stream of
+sulphureous water, as white as milk, descends into the sea from the
+volcanic mountain of Idienne on the east of Java; and a great body of hot
+water, charged with sulphuric acid, rushed down from the same volcano on
+one occasion, and inundated a large tract of country, destroying, by its
+noxious properties, all the vegetation.<a name="FNanchor_R_1" id="FNanchor_R_1"></a><a href="#Footnote_R_1" class="fnanchor">[191-A]</a> In like manner the
+Pusanibio, or "Vinegar River," of Colombia, which rises at the foot of
+Purac�, an extinct volcano, 7,500 feet above the level of the sea, is
+strongly impregnated with sulphuric and muriatic acids and with oxide of
+iron. We may easily suppose the waters of such streams to have properties
+noxious to marine animals, and in this manner the entire absence of marine
+remains in the ossiferous gypsum may be explained.<a name="FNanchor_R_2" id="FNanchor_R_2"></a><a href="#Footnote_R_2" class="fnanchor">[191-B]</a> There are no
+pebbles or coarse sand in the gypsum; a circumstance which agrees well with
+the hypothesis that these beds were precipitated from water holding
+sulphate of lime in solution, and floating the remains of different
+animals.</p>
+
+<p><span class="pagenum"><a id="page192"></a>[p.192]</span>In this formation the relics of about fifty species of quadrupeds,
+including the genera <i>Paleotherium</i>, <i>Anoplotherium</i>, and others, have been
+found, all extinct, and nearly four-fifths of them belonging to a division
+of the order <i>Pachydermata</i>, which is now represented by only four living
+species; namely three tapirs and the daman of the Cape. With them a few
+carnivorous animals are associated, among which are a species of fox and
+gennet. Of the <i>Rodentia</i>, a dormouse and a squirrel; of the <i>Insectivora</i>,
+a bat; and of the <i>Marsupialia</i> (an order now confined to America,
+Australia, and some contiguous islands), an opossum, have been discovered.</p>
+
+<p>Of birds, about ten species have been ascertained, the skeletons of some of
+which are entire. None of them are referable to existing species.<a name="FNanchor_R_3" id="FNanchor_R_3"></a><a href="#Footnote_R_3" class="fnanchor">[192-A]</a>
+The same remark applies to the fish, according to MM. Cuvier, and Agassiz,
+as also to the reptiles. Among the last are crocodiles and tortoises of the
+genera <i>Emys</i> and <i>Trionyx</i>.</p>
+
+<p>The tribe of land quadrupeds most abundant in this formation is such as now
+inhabits alluvial plains and marshes, and the banks of rivers and lakes, a
+class most exposed to suffer by river inundations. Whether the
+disproportion of carnivorous animals can be ascribed to this cause, or
+whether they were comparatively small in number and dimensions, as in the
+indigenous fauna of Australia, when first known to Europeans, is a point on
+which it would be rash, perhaps, to offer an opinion in the present state
+of our knowledge.</p>
+
+<a id="img164" name="img164"></a>
+<div class="figcenter smaller">
+<p>Fig. 162.</p>
+<img src="images/img164.jpg" width="450" height="252" alt="" title="">
+<p><i>Paleotherium magnum.</i></p></div>
+
+<p>The Paleothere, above alluded to, resembled the living tapir in the form of
+the head, and in having a short proboscis, but its molar teeth were more
+like those of the rhinoceros (see <a href="#img165">fig. 163.</a>). <i>Paleotherium magnum</i> was of
+the size of a horse, 3 or 4 feet high. The annexed woodcut, <a href="#img164">fig. 162.</a>, is
+one of the restorations which Cuvier attempted of the outline of the living
+animal, derived from the study of the entire skeleton. When the French
+osteologist declared in the early part of the present century, that all the
+fossil quadrupeds of the gypsum of Paris were extinct, the announcement of
+so startling a <span class="pagenum"><a id="page193"></a>[p.193]</span>fact, on such high authority, created a powerful
+sensation, and from that time a new impulse was given throughout Europe to
+the progress of geological investigation. Eminent naturalists, it is true,
+had long before maintained that the shells and zoophytes, met with in many
+ancient European rocks, had ceased to be inhabitants of the earth, but the
+majority even of the educated classes continued to believe that the species
+of animals and plants now contemporary with man, were the same as those
+which had been called into being when the planet itself was created. It was
+easy to throw discredit upon the new doctrine by asking whether corals,
+shells, and other creatures previously unknown, were not annually
+discovered? and whether living forms corresponding with the fossils might
+not yet be dredged up from seas hitherto unexamined? But from the era of
+the publication of Cuvier's Ossements Fossiles, and still more his popular
+Treatise called "A Theory of the Earth," sounder views began to prevail. It
+was clearly demonstrated that most of the mammalia found in the gypsum of
+Montmartre differed even generically from any now existing, and the extreme
+improbability that any of them, especially the larger ones, would ever be
+found surviving in continents yet unexplored, was made manifest. Moreover,
+the non-admixture of a single living species in the midst of so rich a
+fossil fauna was a striking proof that there had existed a state of the
+earth's surface zoologically unconnected with the present order of things.</p>
+
+<a id="img165" name="img165"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 163.</p>
+<img src="images/img165.jpg" width="200" height="179" alt="" title="">
+<p>Upper molar tooth of <i>Paleotherium magnum</i> from
+Isle of <span class="wosp05">Wight. (Owen's</span> Brit. Foss. p. 317.)</p>
+<p class="martopm05">Reduced one-third.</p></div>
+
+<p><i>Gr�s de Beauchamp</i> (2. <i>b</i>, Table, <a href="#page175">p. 175.</a>).&mdash;In some parts of the Paris
+basin, sands and marls, called the Gr�s de Beauchamp, or Sables Moyens,
+divide the gypseous beds from the underlying Calcaire grossier. These sands
+contain more than 300 species of marine shells, many of them peculiar, but
+others common to the underlying marine deposit (No. 2. <i>c</i>.).</p>
+
+<p><i>Calcaire grossier</i> (2. <i>c</i>, Table, <a href="#page175">p. 175.</a>).&mdash;The formation called
+Calcaire grossier consists of a coarse limestone, often passing into sand.
+It contains the greater number of the fossil shells which characterize the
+Paris basin. No less than 400 distinct species have been procured from a
+single spot near Grignon, where they are embedded in a calcareous sand,
+chiefly formed of comminuted shells, in which, nevertheless, individuals in
+a perfect state of preservation, both of marine, terrestrial, and
+freshwater species, are mingled together. Some of the marine shells may
+have lived on the spot; but the <i>Cyclostoma</i> and <i>Limnea</i> must have been
+brought thither by rivers and currents, and the quantity of triturated
+shells implies considerable movement in the waters.</p>
+
+<p>Nothing is more striking in this assemblage of fossil testacea than the
+great proportion of species referable to the genus <i>Cerithium</i> (see <a href="#img166">fig.
+164.</a>). There occur no less than 137 species of this genus <span class="pagenum"><a id="page194"></a>[p.194]</span>in the
+Paris basin, and almost all of them in the calcaire grossier. Now the
+living <i>Cerithia</i> inhabit the sea near the mouths of rivers, where the
+waters are brackish; so that their abundance in the marine strata now under
+consideration is in harmony with the hypothesis, that the Paris basin
+formed a gulf into which several rivers flowed, the sediment of some of
+which gave rise to the beds of clay and lignite before mentioned; while a
+distinct freshwater limestone, called calcaire siliceux, which will
+presently be described, was precipitated from the waters of others situated
+farther to the south.</p>
+
+<a id="img166" name="img166"></a>
+<div class="figcenter smaller width100">
+<p>Fig. 164.</p>
+<img src="images/img166.jpg" width="100" height="369" alt="" title="">
+<p>Cerithium cinctum.<a name="FNanchor_R_4" id="FNanchor_R_4"></a><a href="#Footnote_R_4" class="fnanchor">[194-A]</a></p></div>
+
+<a id="img167" name="img167"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">EOCENE FORAMINIFERA.</p>
+<img src="images/img167.jpg" width="500" height="541" alt="" title="">
+<p>Fig. 165. <i>Calcarina rarispina</i>, Desh.</p>
+<ul class="smaller leftal martopm05 add6em">
+<li><i>b</i>. natural size.</li>
+<li><i>a</i>, <i>c</i>. same magnified.</li>
+</ul>
+<p>Fig. 166. <i>Spirolina stenostoma</i>, Desh.</p>
+<ul class="smaller leftal martopm05 add6em">
+<li>B. natural size.</li>
+<li>A, C, D. same magnified.</li>
+</ul>
+<p>Fig. 167. <i>Triloculina inflata</i>, Desh.</p>
+<ul class="smaller leftal martopm05 add6em">
+<li><i>b</i>. natural size.</li>
+<li><i>a</i>, <i>c</i>, <i>d</i>, same magnified.</li>
+</ul>
+<p>Fig. 168. <i>Clavulina corrugata</i>, Desh.</p>
+<ul class="smaller leftal martopm05 add6em">
+<li><i>a</i>. natural size.</li>
+<li><i>b</i>, <i>c</i>. same magnified.</li>
+</ul></div>
+
+<p>In some parts of the calcaire grossier round Paris, certain beds occur of a
+stone used in building, and called by the French geologists "Miliolite
+limestone." It is almost entirely made up of millions of microscopic
+shells, of the size of minute grains of sand, which all belong to the class
+Foraminifera. Figures of some of these are given in the annexed woodcut. As
+this miliolitic stone never occurs in the Faluns, or Miocene strata of
+<span class="pagenum"><a id="page195"></a>[p.195]</span>Brittany and Touraine, it often furnishes the geologist with a
+useful criterion for distinguishing the detached Eocene and Miocene
+formations, scattered over those and other adjoining provinces. The
+discovery of the remains of Paleotherium and other mammalia in some of the
+upper beds of the calcaire grossier shows that these land animals began to
+exist before the deposition of the overlying gypseous series had commenced.</p>
+
+<p><i>Calcaire siliceux</i>.&mdash;This compact siliceous limestone extends over a wide
+area. It resembles a precipitate from the waters of mineral springs, and is
+often traversed by small empty sinuous cavities. It is, for the most part,
+devoid of organic remains, but in some places contains freshwater and land
+species, and never any marine fossils. The siliceous limestone and the
+calcaire grossier occupy distinct parts of the Paris basin, the one
+attaining its fullest development in those places where the other is of
+slight thickness. They also alternate with each other towards the centre of
+the basin, as at Sergy and Osny; and there are even points where the two
+rocks are so blended together that portions of each may be seen in hand
+specimens. Thus, in the same bed, at Triel, we have the compact freshwater
+limestone, characterized by its <i>Limne�</i>, mingled with the coarse marine
+limestone, with its small multilocular shells, or "miliolites," dispersed
+through it in countless numbers. These microscopic testacea are also
+accompanied by <i>Cerithia</i> and other shells of the calcaire grossier. It is
+very extraordinary that in this instance both kinds of sediment must have
+been thrown down together on the same spot, yet each retains its own
+peculiar organic remains.</p>
+
+<p>From these facts we may conclude, that while to the north, where the bay
+was probably open to the sea, a marine limestone was formed, another
+deposit of freshwater origin was introduced to the southward, or at the
+head of the bay; for it appears that during the Eocene period, as now, the
+ocean was to the north, and the continent, where the great lakes existed,
+to the south. From that southern region we may suppose a body of fresh
+water to have descended, charged with carbonate of lime and silica, the
+water being perhaps in sufficient volume to freshen the upper end of the
+bay. The gypseous series (2. <i>a</i>, Table, <a href="#page175">p. 175.</a>), before described, was
+once supposed to be entirely subsequent in origin to the two groups, called
+calcaire grossier and calcaire siliceux. But M. Prevost has pointed out
+that in some localities they alternate repeatedly with both.</p>
+
+<p>The gypsum, with its associated marl and limestone, is in greatest force
+towards the centre of the basin, where the calcaire grossier and calcaire
+siliceux are less fully developed. Hence M. Prevost infers, that while
+those two principal deposits were gradually in progress, the one towards
+the north, and the other towards the south, a river descending from the
+east may have brought down the gypseous and marly sediment.</p>
+
+<p>It must be admitted, as highly probable, that a bay or narrow sea, 180
+miles in length, would receive, at more points than one, the waters of the
+adjoining continent. At the same time, we must be <span class="pagenum"><a id="page196"></a>[p.196]</span>prepared to
+find that the simultaneous deposition of two or more sets of strata in one
+basin, some freshwater and others marine, must have produced very complex
+results. But, in proportion as it is more difficult in these cases to
+discover any fixed order of superposition in the associated mineral masses,
+so also is it more easy to explain the manner of their origin, and to
+reconcile their relations to the agency of known causes. Instead of the
+successive irruptions and retreats of the sea, and changes in the chemical
+nature of the fluid, and other speculations of the earlier geologists, we
+are now simply called upon to imagine a gulf, into one extremity of which
+the sea entered, and at the other a large river, while other streams may
+have flowed in at different points, whereby an indefinite number of
+alternations of marine and freshwater beds would be occasioned.</p>
+
+
+<h3>LOWER EOCENE, FRANCE.</h3>
+
+<p><i>Lits coquilliers</i> (3. <i>a</i>, Table, <a href="#page175">p. 175.</a>).&mdash;Below the calcaire grossier
+are extensive deposits of sand, in the upper parts of which some marine
+beds, called "lits coquilliers," occur, in which M. d'Archiac has
+discovered 200 species of shells. Many of these are peculiar, but the
+larger portion appear to agree with species of the calcaire grossier, so
+that the line of demarcation usually adopted between the French Lower and
+Middle Eocene formations, seems not to be very strongly drawn. <i>Sands and
+plastic clay</i> (3. <i>b</i>, Table, <a href="#page175">p. 175.</a>)&mdash;At the base of the tertiary system
+in France are extensive deposits of sands, with occasional beds of clay
+used for pottery, and called "argile plastique." Fossil oysters (<i>Ostrea
+bellovacina</i>) abound in some places, and in others there is a mixture of
+fluviatile shells, such as <i>Cyrena cuneiformis</i> (<a href="#img184">fig. 187.</a> <a href="#page204">p. 204.</a>),
+<i>Melania inquinata</i> (<a href="#img185">fig. 188.</a>), and others, frequently met with in beds
+occupying the same position in the valley of the Thames. Layers of lignite
+also accompany the inferior clays and sands.</p>
+
+<p>Immediately upon the chalk at the bottom of all the tertiary strata there
+is often a conglomerate or breccia of rolled and angular chalk flints,
+cemented by siliceous sand. These beds appear to be of littoral origin, and
+imply the previous emergence of some portions of the chalk, and its waste
+by denudation.</p>
+
+<a id="img168" name="img168"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 169.</p>
+<img src="images/img168.jpg" width="300" height="139" alt="" title="">
+<p><i>Cardium porulosum</i><span class="wosp05">. Paris</span> and London basins.</p></div>
+
+<p>The lower sandy beds of the Paris basin are often called the sands of the
+Soissonais, from a district so named 50 miles N.E. of Paris. One of the
+shells of the formation is adduced by M. Deshayes as an example of the
+changes which certain species underwent in the successive <span class="pagenum"><a id="page197"></a>[p.197]</span>stages
+of their existence. It seems that different varieties of the <i>Cardium
+porulosum</i> are characteristic of different formations. In the Lower Eocene
+of the Soissonais this shell acquires but a small volume, and has many
+peculiarities, which disappear in the lowest beds of the calcaire grossier.
+In these the shell attains its full size, and many distinctive characters,
+which are again modified in the uppermost beds of the calcaire grossier;
+and these last modifications of form are preserved throughout the whole of
+the "upper marine" (or Upper Eocene) series.<a name="FNanchor_R_5" id="FNanchor_R_5"></a><a href="#Footnote_R_5" class="fnanchor">[197-A]</a></p>
+
+
+<h3>ENGLISH EOCENE FORMATIONS.</h3>
+
+<p>The Eocene areas of Hampshire and London are delineated in the map (<a href="#img155">fig.
+153.</a> <a href="#page174">p. 174.</a>).</p>
+
+<p>The following table will show the succession of the principal deposits
+found in our island. The true place of the Bagshot sands, in this series,
+was never accurately ascertained till Mr. Prestwich published, in 1847, his
+classification of the English Eocene strata, dividing them into three
+principal formations, in which the Bagshot sands occupied the central
+place.<a name="FNanchor_R_6" id="FNanchor_R_6"></a><a href="#Footnote_R_6" class="fnanchor">[197-B]</a></p>
+
+
+<table  border="0" cellpadding="2" summary="SUCCESSION OF PRINCIPAL EOCENE FORMATIONS IN BRITAIN.">
+<colgroup>
+    <col width="20%">
+    <col width="7%">
+    <col width="3%">
+    <col width="35%">
+    <col width="35%">
+</colgroup>
+
+<tr>
+  <td colspan="4">&nbsp;</td>
+  <td class="td-center tdtx-mid smaller">Localities.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">1. Upper Eocene.</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="td-left tdtx-top">Wanting in Great Britain.</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td rowspan="3" class="td-left tdtx-mid" style="padding-top: 1.3em;">2. Middle Eocene</td>
+  <td rowspan="3" valign="middle" style="white-space: nowrap; font-size: 60pt; font-weight: 100;" class="tdtx-mid">{</td>
+  <td rowspan="5">&nbsp;</td>
+  <td class="td-left tdtx-mid"><i>a.</i> Freshwater and fluvio-marine beds.</td>
+  <td class="td-left tdtx-mid tdp-left">Headon Hill, Isle of Wight; and
+  Hordwell Cliff, Hants.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>b.</i> Barton beds.</td>
+  <td class="td-left tdtx-mid tdp-left">Barton Cliff, Hants.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>c.</i> Bagshot and Bracklesham sands and clays.</td>
+  <td class="td-left tdtx-mid tdp-left">Bagshot Heath, Surrey; Bracklesham Bay, Sussex.</td>
+</tr>
+
+<tr>
+  <td rowspan="2" class="td-left tdtx-mid" style="padding-top: 1em;">3. Lower Eocene</td>
+  <td rowspan="2" valign="middle" style="white-space: nowrap; font-size: 45pt; font-weight: 300;" class="tdtx-mid">{</td>
+  <td class="td-left tdtx-mid"><i>a.</i> London Clay Proper, and Bognor beds.</td>
+  <td class="td-left tdtx-mid tdp-left">Highgate Hill, Middlesex; I. of Sheppey; Bognor, Sussex.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid"><i>b.</i> Mottled and Plastic clays and sands.</td>
+  <td class="td-left tdtx-mid tdp-left">Newhaven, Sussex; Reading, Berks; Woolwich, Kent.</td>
+</tr>
+</table>
+
+
+<a id="img169" name="img169"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 170.</p>
+<img src="images/img169.jpg" width="250" height="324" alt="" title="">
+<p><i>Lymnea longiscata.</i></p>
+<p class="martopm05">Freshwater Eocene strata, Isle of Wight.</p></div>
+
+<p><i>Freshwater beds</i> (2. <i>a</i>, Table, <a href="#page175">p. 175.</a>).&mdash;In the northern part of the
+Isle of Wight, beds of marl, clay, and sand, and a friable limestone,
+containing freshwater shells, are seen, containing shells of the genera
+<i>Lymnea</i> (see <a href="#img169">fig. 170.</a>), <i>Planorbis</i>, <i>Melanopsis</i>, <i>Cyrena</i>, &amp;c., several
+of them of the same species as those occurring in the Eocene beds of the
+Paris basin. Gyrogonites, also, or seed-vessels of <i>Chara</i>, exhibiting a
+similar specific identity, occur. At Headon Hill, on the western side of
+the island, where these beds are seen in the sea-cliffs, some of the strata
+contain a few marine and estuary shells, such as <i>Cyther�a</i>, <i>Corbula</i>,
+&amp;c., showing a temporary occupation of the area by brackish or salt water,
+after which the river or a lake seems again to have prevailed. A <span class="pagenum"><a id="page198"></a>[p.198]</span>
+species of fan-palm, <i>Flabellaria Lamanonis</i>, Brong., like one which
+characterizes the Parisian Eocene beds, has been recently detected by Dr.
+Mantell in this formation, in Whitecliff Bay, at the eastern end of the
+island.</p>
+
+<p>Several of the species of extinct quadrupeds already alluded to as
+characterizing the gypsum of Montmartre have been discovered by Messrs.
+Pratt and Fox, in the Isle of Wight, chiefly at Binstead, near Ryde, as
+<i>Pal�otherium magnum</i>, <i>P. medium</i>, <i>P. minus</i>, <i>P. minimum</i>, <i>P. curtum</i>,
+<i>P. crassum</i>, also <i>Anoplotherium commune</i>, <i>A. secundarium</i>, <i>Dichobune
+cervinum</i>, and <i>Ch�ropotamus Cuvieri</i>. In Hordwell cliff, also on the
+Hampshire coast, several of these species, with other quadrupeds of new
+genera, such as <i>Paloplotherium</i>, Owen, have been met with; and remains of
+a remarkable carnivorous genus, <i>Hy�nodon</i>. These fossils are accompanied
+by the bones of <i>Trionyx</i>, and other tortoises, and by two land snakes of
+the genus <i>Paleryx</i>, Owen, from 3 to 4 feet long, also a species of
+crocodile, and an alligator. Among other fossils collected by Lady
+Hastings, Sir Philip Egerton has recognized the well-known gar or bony pike
+of the American rivers, a ganoid fish of the genus <i>Lepidotus</i>, with its
+hard shining scales. The shells of Hordwell are similar to those of the
+freshwater beds of the Isle of Wight, and among them are a few specifically
+undistinguishable from recent testacea, as <i>Paludina lenta</i> and <i>Helix
+labyrinthica</i>, the latter discovered by Mr. S. Wood, and identified with an
+existing N. American helix.</p>
+
+<p>The white and green marls of this freshwater series in Hampshire, and some
+of the accompanying limestones, often resemble those of France in mineral
+character and colour in so striking a manner, as to suggest the idea that
+the sediment was derived from the same region, or produced
+contemporaneously under very similar geographical circumstances.</p>
+
+<p><i>Barton beds.</i>&mdash;Both in the cliffs of Headon Hill and Hordwell, already
+mentioned, the freshwater series rests on a mass of pure white sand without
+fossils, and this is seen in Barton Cliff to overlie a marine deposit, in
+which 209 species of testacea have been found. More than half of these are
+peculiar; and, according to Mr. Prestwich, only 11 of them common to the
+London Clay proper, being in the proportion of only 5 per cent. On the
+other hand, 70 of them agree with the <i>calcaire grossier</i> shells. As this
+is the newest purely marine bed of the Eocene series known in England, we
+might have expected that some of its peculiar fossils would be found to
+agree with the upper Eocene strata described in the last chapter, and
+accordingly some identifications have been cited with testacea, both of the
+Berlin and Belgian strata. It is nearly a century since Brander published,
+in 1766, an account of the organic remains collected from these cliffs, and
+his excellent figures of the shells then deposited in the British Museum
+are justly admired by conchologists for their accuracy.</p>
+
+<p><i>Bagshot Sands</i> (2. <i>c</i>, Table, <a href="#page197">p. 197.</a>).&mdash;These beds, consisting chiefly
+<span class="pagenum"><a id="page199"></a>[p.199]</span>of siliceous sand, occupy extensive tracts round Bagshot, in
+Surrey, and in the New Forest, Hampshire. They succeed next in
+chronological order, and may be separated into three divisions, the upper
+and lower consisting of light yellow sands, and the central of dark green
+sands and brown clays, the whole reposing on the London clay proper.<a name="FNanchor_R_7" id="FNanchor_R_7"></a><a href="#Footnote_R_7" class="fnanchor">[199-A]</a>
+Although the Bagshot beds are usually devoid of fossils, they contain
+marine shells in some places, among which <i>Venericardia planicosta</i> (see
+<a href="#img170">fig. 171.</a>) is abundant, with <i>Turritella sulcifera</i> and <i>Nummulites
+l�vigatus</i>. (See <a href="#img173">fig. 174.</a> <a href="#page200">p. 200.</a>)</p>
+
+<a id="img170" name="img170"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 171.</p>
+<img src="images/img170.jpg" width="450" height="180" alt="" title="">
+<p><i>Venericardia planicosta</i>, Lamck.</p>
+<p class="martopm05"><i>Cardita planicosta</i>, Deshayes.</p></div>
+
+<p>At Bracklesham Bay, near Chichester, in Sussex, the characteristic shells
+of this member of the Eocene series are best seen; among others, the huge
+<i>Cerithium giganteum</i>, so conspicuous in the calcaire grossier of Paris,
+where it is sometimes 2 feet in length. The volutes and cowries of this
+formation, as well as the lunulites and other corals, seem to favour the
+idea of a warm climate having prevailed, which is borne out by the
+discovery of a serpent <i>Pal�ophis typh�us</i>, exceeding, according to Mr.
+Owen, 20 feet in length, and allied to the Boa, Python, Coluber, and
+Hydrus. The compressed form and diminutive size of certain caudal vertebr�
+indicate so much analogy with Hydrus as to induce the Hunterian professor
+to pronounce the extinct ophidian to have been marine.<a name="FNanchor_R_8" id="FNanchor_R_8"></a><a href="#Footnote_R_8" class="fnanchor">[199-B]</a> He had
+previously combated with so much success the evidence advanced, to prove
+the existence in the Northern Ocean of sea-serpents in our own times, that
+he will not be suspected of any undue bias in contending for their former
+existence in the British Eocene seas. The climate, however, of the Middle
+Eocene period was evidently far more genial; and amongst the companions of
+the sea-serpent of Bracklesham was an extinct Gavial (<i>Gavialis Dixoni</i>,
+Owen), and numerous fish, such as now frequent the seas of warm latitudes,
+as the sword-fish (see <a href="#img171">fig. 172.</a> <a href="#page200">p. 200.</a>) and gigantic rays of the genus
+Miliobates. (See <a href="#img172">fig. 173.</a>)</p>
+
+<p><span class="pagenum"><a id="page200"></a>[p.200]</span>Out of 193 species of testacea procured from the Bagshot and
+Bracklesham beds in England, 126 occur in the French calcaire grossier. It
+was clearly, therefore, coeval with that part of the Parisian series more
+nearly than with any other. The <i>Nummulites l�vigatus</i> (see <a href="#img173">fig. 174.</a>), a
+fossil characteristic of the lower beds of the calcaire grossier, is
+abundant at Bracklesham.</p>
+
+<a id="img171" name="img171"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 172.</p>
+<img src="images/img171.jpg" width="500" height="033" alt="" title="">
+<p>Prolonged premaxillary bone or "sword" of a fossil sword-fish
+(<i>C�lorhynchus</i>)<span class="wosp05">. Bracklesham. Dixon's</span>
+Fossils of Sussex, pl. 8.</p></div>
+
+<a id="img172" name="img172"></a>
+<div class="figcenter smaller width300">
+<p class="martop2">Fig. 173.</p>
+<img src="images/img172.jpg" width="300" height="190" alt="" title="">
+<p>Dental plates of <i>Myliobates Edwardsi</i>.
+Bracklesham <span class="wosp05">Bay. Ibid.</span> pl. 8.</p></div>
+
+<a id="img173" name="img173"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 174.</p>
+<img src="images/img173.jpg" width="350" height="168" alt="" title="">
+<p><i>Nummulites</i> (<i>Nummularia</i>) <i>l�vigatus.</i>
+<span class="wosp05">Bracklesham. Ibid.</span> pl. 8.</p>
+<ul class="smaller leftal add1em min1em martopm05">
+<li><i>a.</i> section of the nummulite.</li>
+<li><i>b.</i> group, with an individual showing the exterior of the shell.</li>
+</ul></div>
+
+<p><i>London clay proper</i> (3. <i>a</i>, Table, <a href="#page197">p. 197.</a>).&mdash;This formation underlies
+the preceding, and consists of tenacious brown and blueish grey clay, with
+layers of concretions called septaria, which abound chiefly in the brown
+clay, and are obtained in sufficient numbers from the cliffs near Harwich,
+and from shoals of the Essex coast, to be used for making Roman cement. The
+principal localities of fossils in the London clay are Highgate Hill, near
+London, the island of Sheppey, and Bognor in Hampshire. Out of 133 fossil
+shells, Mr. Prestwich found only 20 to be common to the calcaire grossier
+(from which 600 species have been obtained), while 33 are common to the
+lits coquilliers (<a href="#page196">p. 196.</a>), in which only 200 species are known in France.
+We may presume, therefore, that the London clay proper is older than the
+calcaire grossier. This may perhaps remove a difficulty which M. Adolphe
+Brongniart has experienced when comparing the Eocene Flora of the
+neighbourhoods of London and Paris. The fossil species of the island of
+Sheppey, he observes, indicate a much more tropical climate than the Eocene
+Flora of France, which has been derived principally from the "gypseous
+series." The latter resembles the vegetation of the borders of the
+Mediterranean rather than that of an equatorial region.</p>
+
+<p>Mr. Bowerbank, in a valuable publication on the fossil fruits and seeds of
+the island of Sheppey, near London, has described no less than thirteen
+fruits of palms of the recent type <i>Nipa</i>, now only <span class="pagenum"><a id="page201"></a>[p.201]</span>found in the
+Molucca and Philippine islands. (See <a href="#img174">fig. 175.</a>) These plants are allied to
+the cocoa-nut tribe on the one side, and on the other to the <i>Pandanus</i>, or
+screw-pine. Species of cocoa-nuts are also met with, and other kinds of
+palms; also three species of <i>Anona</i>, or custard-apple; cucurbitaceous
+fruits, also (the gourd and melon family), are in considerable abundance.
+Fruits of various species of <i>Acacia</i> are in profusion; and, although less
+decidedly tropical, imply a warm climate.</p>
+
+<a id="img174" name="img174"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 175.</p>
+<img src="images/img174.jpg" width="200" height="252" alt="" title="">
+<p><i>Nipadites ellipticus.</i> <span class="wosp05">Bow. Fossil</span> palm of
+Sheppey.</p></div>
+
+<p>The contiguity of land may be inferred not only from these vegetable
+productions, but also from the teeth and bones of crocodiles and turtles,
+since these creatures, as Mr. Conybeare has remarked, must have resorted to
+some shore to lay their eggs. Of turtles there were numerous species
+referred to extinct genera, and, for the most part, not equal in size to
+the largest living tropical turtles. A snake, which must have been 13 feet
+long, of the genus <i>Pal�ophis</i> before mentioned, has also been described by
+Mr. Owen from Sheppey, of a different species from that of Bracklesham. A
+true crocodile, also, <i>Crocodilus toliapicus</i>, and another Saurian more
+nearly allied to the gravial, accompany the above fossils. A bird allied to
+the vultures, and a quadruped of the new genus <i>Hyracotherium</i>, allied to
+the Hyrax, Hog, and Ch�ropotamus, are also among the additions made of late
+years to the pal�ontology of this division.</p>
+
+<a id="img175" name="img175"></a>
+<div class="figcenter smaller width450">
+<p>FOSSIL SHELLS OF THE LONDON CLAY.</p>
+<img src="images/img175.jpg" width="450" height="380" alt="" title="">
+<p class="leftal add1em">Fig. 176. <i>Mitra scabra</i>.</p>
+<p class="leftal add1em martopm05">Fig. 177. <i>Rostellaria macroptera</i>, Sow. One-third of nat. size.</p>
+<p class="leftal add1em martopm05">Fig. 178. <i>Crassatella sulcata.</i></p></div>
+
+<p>The marine shells of the London clay confirm the inference derivable from
+the plants and reptiles of a high temperature. Thus, many species of
+<i>Conus</i>, <i>Mitra</i>, and <i>Voluta</i> occur, a large <i>Cypr�a</i>, a <span class="pagenum"><a id="page202"></a>[p.202]</span>very
+large <i>Rostellaria</i>, and shells of the genera <i>Terebellum</i>, <i>Cancellaria</i>,
+<i>Crassatella</i>, and others, with four or more species of <i>Nautilus</i> (see
+<a href="#img179">fig. 182.</a>) and other cephalopoda of extinct genera, one of the most
+remarkable of which is the <i>Belosepia</i>.<a name="FNanchor_R_9" id="FNanchor_R_9"></a><a href="#Footnote_R_9" class="fnanchor">[202-A]</a> (See <a href="#img180">fig. 183.</a>)</p>
+
+<a id="img176" name="img176"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 179.</p>
+<img src="images/img176.jpg" width="250" height="230" alt="" title="">
+<p><i>Nautilus centralis.</i></p></div>
+
+<a id="img177" name="img177"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 180.</p>
+<img src="images/img177.jpg" width="200" height="272" alt="" title="">
+<p><i>Voluta athleta.</i></p></div>
+
+<a id="img178" name="img178"></a>
+<div class="floatright smaller width100">
+<p>Fig. 181.</p>
+<img src="images/img178.jpg" width="100" height="315" alt="" title="">
+<p><i>Terebellum fusiforme.</i></p></div>
+
+<a id="img179" name="img179"></a>
+<div class="figcenter nofloat smaller width300">
+<p>Fig. 182.</p>
+<img src="images/img179.jpg" width="300" height="155" alt="" title="">
+<p><i>Aturia zigzag.</i> Bronn. Syn. <i>Nautilus zigzag.</i>
+Sow. London <span class="wosp05">clay. Sheppey.</span></p></div>
+
+<a id="img180" name="img180"></a>
+<div class="figcenter smaller width300">
+<p class="martop2">Fig. 183.</p>
+<img src="images/img180.jpg" width="300" height="115" alt="" title="">
+<p><i>Belosepia sepiodea</i>, De Blainv. London <span class="wosp05">clay.
+Sheppey.</span></p></div>
+
+<p>The above shells are accompanied by a sword-fish (<i>Tetrapterus priscus</i>,
+Agassiz), about 8 feet long, and a saw-fish (<i>Pristis bisulcatus</i>, Ag.),
+about 10 feet in length; genera now foreign to the British seas. On the
+whole, no less than 50 species of fish have been described by M. Agassiz
+from these beds in Sheppey, and they indicate, in his opinion, a warm
+climate.</p>
+
+<a id="img181" name="img181"></a>
+<div class="figcenter smaller width175">
+<p>Fig. 184.</p>
+<img src="images/img181.jpg" width="175" height="048" alt="" title="">
+<p>Molar of monkey (<i>Macacus</i>).</p></div>
+
+<p><i>Strata of Kyson in Suffolk.</i>&mdash;At Kyson, a few miles east of Woodbridge, a
+bed of Eocene clay, 12 feet thick, underlies the red crag. Beneath it is a
+deposit of yellow and white sand, of considerable interest, in consequence
+of many peculiar fossils contained in it. Its geological position is
+probably the lowest part of the London clay proper. In this sand has been
+found the first example of a fossil quadrumanous animal discovered in Great
+Britain, namely, the teeth and part of a jaw, shown by Mr. Owen to belong
+to a monkey of the genus <i>Macacus</i> (see <a href="#img181">fig. 184.</a>). The mammiferous
+fossils, first met with in the same bed, were those of an opossum
+(<i>Didelphys</i>) (see <a href="#img182">fig. 185.</a>), and an insectivorous bat (<a href="#img183">fig. 186.</a>),
+together with many teeth of fishes of the shark family. <span class="pagenum"><a id="page203"></a>[p.203]</span>Mr.
+Colchester in 1840 obtained other mammalian relics from Kyson, among which
+Mr. Owen has recognized several teeth of the genus <i>Hyracotherium</i>, and the
+vertebr� of a large serpent, probably a <i>Pal�ophis</i>. As the remains both of
+the <i>Hyracotherium</i> and <i>Pal�ophis</i> were afterwards met with in the London
+clay, as before remarked, these fossils confirmed the opinion previously
+entertained, that the Kyson sand belongs to the Eocene period. The
+<i>Macacus</i>, therefore, constitutes the first example of any quadrumanous
+animal found in strata as old as the Eocene, or so far from the equator as
+lat. 52� N. It was not until after the year 1836 that the existence of any
+fossil quadrumana was brought to light. Since that period they have been
+found in France, India, and Brazil.</p>
+
+<a id="img182" name="img182"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 185.</p>
+<img src="images/img182.jpg" width="200" height="114" alt="" title="">
+<p>Molar tooth and part of jaw of opossum. From
+Kyson.<a name="FNanchor_R_10" id="FNanchor_R_10"></a><a href="#Footnote_R_10" class="fnanchor">[203-A]</a></p></div>
+
+<a id="img183" name="img183"></a>
+<div class="figcenter smaller width200">
+<p class="martop2">Fig. 186.</p>
+<img src="images/img183.jpg" width="200" height="097" alt="" title="">
+<p>Molars of insectivorous bats, twice nat. size. From Kyson, Suffolk.</p></div>
+
+<p><i>Mottled or Plastic Clays</i>, <i>&amp;c.</i> (3. <i>b</i>, Table, <a href="#page197">p. 197.</a>).&mdash;No formations
+can be more dissimilar on the whole in mineral character than the Eocene
+deposits of England and Paris; those of our own island being almost
+exclusively of mechanical origin,&mdash;accumulations of mud, sand, and pebbles;
+while in the neighbourhood of Paris we find a great succession of strata
+composed of a coarse white limestone, and compact siliceous limestone with
+beds of crystalline gypsum and siliceous sandstone, and sometimes pure
+flint used for millstones. Hence it is by no means an easy task to
+institute an exact comparison between the various members of the English
+and French series, and to settle their respective ages. It is clear that a
+continual change was going on in the fauna and flora by the coming in of
+new species and the dying out of others; and contemporaneous changes of
+geographical conditions were also in progress in consequence of the rising
+and sinking of the land and bottom of the sea. A particular subdivision,
+therefore, of time was occasionally represented in one area by land, in
+another by an estuary, in a third by the sea, and even where the conditions
+were in both areas of a marine character, there was often shallow water in
+one, and deep sea in another, producing a want of agreement in the state of
+animal life.</p>
+
+<p>At the commencement, however, of the Eocene formations in France and
+England, we find an exception to this rule, for a marked similarity of
+mineral character reigns in the lowest division, whether in the basins of
+Paris, Hampshire, or London. This uniformity of aspect must be seen in
+order to be fully appreciated, since the beds consist simply of sand,
+mottled clays, and well-rolled flint pebbles, derived from the chalk, and
+varying in size from that of a pea to an egg. These strata may be seen at
+Reading, at Blackheath, near <span class="pagenum"><a id="page204"></a>[p.204]</span>London, and at Woolwich. In some of
+the lowest of them, banks of oysters are observed, consisting of <i>Ostrea
+bellovicina</i>, so common in France in the same relative position, and
+<i>Ostrea edulina</i>, scarcely distinguishable from the living eatable species.
+In this formation at Bromley, Dr. Buckland found one large pebble to which
+five full-grown oysters were affixed, in such a manner as to show that they
+had commenced their first growth upon it, and remained attached to it
+through life.</p>
+
+<p>In several places, as at Woolwich on the Thames, at Newhaven in Sussex, and
+elsewhere, a mixture of marine and freshwater testacea distinguishes this
+member of the series. Among the latter, <i>Melania inquinata</i> (see <a href="#img185">fig. 188.</a>)
+and <i>Cyrena cuneiformis</i> are very common. They probably indicate points
+where rivers entered the Eocene sea.</p>
+
+<a id="img184" name="img184"></a>
+<div class="figcenter smaller width225">
+<p>Fig. 187.</p>
+<img src="images/img184.jpg" width="225" height="408" alt="" title="">
+<p><i>Cyrena cuneiformis</i>, Min. Con. Natural size.</p></div>
+
+<a id="img185" name="img185"></a>
+<div class="figcenter smaller width175">
+<p class="martop2">Fig. 188.</p>
+<img src="images/img185.jpg" width="175" height="545" alt="" title="">
+<p><i>Melania inquinata</i>, <span class="wosp05">Des. Nat.</span> size.</p>
+<p class="martopm05">Syn. <i>Cerithium melanoides</i>, Min. Con.</p></div>
+
+<p>With us as in France, clay of this formation is used in some places, as
+near Poole in Dorsetshire, for pottery; and hence the name of plastic clay
+was adopted for the group by Mr. T. Webster. Lignite also is associated
+with it in some spots, as in the Paris basin.</p>
+
+<p>Before the minds of geologists had become familiar with the theory of the
+gradual sinking of the land, and its conversion into sea at different
+periods, and the consequent change from shallow to deep water, the
+freshwater and littoral character of this inferior group appeared strange
+and anomalous. After passing through many hundred feet of London clay,
+proved by its fossils to have been deposited in salt water of considerable
+depth, we arrive at beds of fluviatile origin. Thick masses, also, of
+shingle indicate the proximity of land, where the flints of the chalk were
+rolled into sand and pebbles, and spread continuously over wide spaces, as
+in the Isle of <span class="pagenum"><a id="page205"></a>[p.205]</span>Wight, in the south of Hampshire, and near London,
+always appearing at the bottom of the Eocene series. It may be asked why
+they did not constitute simply a narrow littoral zone, such as we might
+look for in strata formed at a moderate distance from the shore. In answer
+to this inquiry, the student must be reminded, that wherever a
+gently-sloping land is gradually sinking and becoming submerged, shingle
+may be heaped up successively over a wide area, although marine currents
+have no power of dispersing it simultaneously over a large space. In such
+cases it is not the shingle which recedes from the coast, but the coast
+which recedes from the shingle, which is formed one mass after another as
+often as successive portions of the land are converted into sea and others
+into a sea beach.</p>
+
+<p>The London area appears to have been upraised before that of Hampshire, so
+that it never became the receptacle of the Barton clays, nor of the
+overlying fluvio-marine and freshwater beds of Hordwell and the north part
+of the Isle of Wight. On the other hand, the Hampshire Eocene area seems to
+have emerged before that of Paris, so that no marine beds of the Upper
+Eocene era were ever thrown down in Hampshire.</p>
+
+<p><i>Nummulitic formation of the Alps and Pyrenees.</i>&mdash;It has long been matter
+of controversy, whether the nummulitic rocks of the Alps and Pyrenees
+should be regarded as Eocene or Cretaceous; but the number of geologists of
+high authority who regard this important group as belonging to the lowest
+tertiary system of Europe has for many years been steadily increasing. The
+late M. Alex. Brongniart first declared the specific identity of many of
+the shells of this formation with those of the marine strata near Paris,
+although he obtained them from the summit of the Diablerets, one of the
+loftiest of the Swiss Alps, which rises more than 10,000 feet above the
+level of the sea.</p>
+
+<p>Deposits of the same age, found on the flanks of the Pyrenees, contain also
+a great number of shells common to the Paris and London areas, and three or
+four species only which are common to the cretaceous formation.</p>
+
+<p>The calcareous division consists often of a compact crystalline marble,
+full of nummulites (see <a href="#img186">fig. 189.</a>), shells of the class <i>Foraminifera</i>.</p>
+
+<a id="img186" name="img186"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 189.</p>
+<img src="images/img186.jpg" width="400" height="162" alt="" title="">
+<p><i>Nummulites</i><span class="wosp05">. Peyrehorade,</span> Pyrenees.</p>
+<ul class="martopm05 smaller leftal min1em">
+<li><i>a.</i> external surface of one of the nummulites, of which longitudinal sections are seen
+in the limestone.</li>
+<li><i>b.</i> transverse section of same.</li>
+</ul></div>
+
+<p><span class="pagenum"><a id="page206"></a>[p.206]</span>The nummulitic limestone of the Alps is often of great thickness,
+and is immediately covered by another series of strata of dark-coloured
+slates, marls, and fucoidal sandstones, to the whole of which the
+provincial name of "flysch" has been given in parts of Switzerland. The
+researches of Sir Roderick Murchison in the Alps in 1847 enable us to refer
+the whole of these beds to the Eocene period, and it seems probable that
+they most nearly coincide in age with the Lower Eocene. They enter into the
+disturbed and loftiest portions of the Alpine chain, to the elevation of
+which they enable us therefore to assign a comparatively modern date.</p>
+
+<p>The nummulitic formation, with its characteristic fossils, plays a far more
+conspicuous part than any other tertiary group in the solid framework of
+the earth's crust, whether in Europe, Asia, or Africa. It often attains a
+thickness of many thousand feet, and extends from the Alps to the
+Apennines. It is found in the Carpathians, and in full force in the north
+of Africa, as, for example, in Algeria and Morocco. It has also been traced
+from Egypt into Asia Minor, and across Persia by Bagdad to the mouths of
+the Indus. It occurs not only in Cutch, but in the mountain ranges which
+separate Scinde from Persia, and which form the passes leading to Caboul;
+and it has been followed still farther eastward into India.</p>
+
+<p>Some members of this lower tertiary formation in the central Alps,
+including even the superior strata called <i>flysch</i>, have been converted
+into crystalline rocks, and changed into saccharoid marble, quartz, rock,
+and mica-schist.<a name="FNanchor_R_11" id="FNanchor_R_11"></a><a href="#Footnote_R_11" class="fnanchor">[206-A]</a></p>
+
+
+<h3>EOCENE STRATA IN THE UNITED STATES.</h3>
+
+<p>In North America the Eocene formations occupy a large area bordering the
+Atlantic, which increases in breadth and importance as it is traced
+southwards from Delaware and Maryland to Georgia and Alabama. They also
+occur in Louisiana and other states both east and west of the valley of the
+Mississippi. At Claiborne in Alabama no less than four hundred species of
+marine shells, with many echinoderms and teeth of fish, characterize one
+member of this system. Among the shells the <i>Cardita planicosta</i>, before
+mentioned (<a href="#img170">fig. 171.</a> <a href="#page199">p. 199.</a>), is in abundance; and this fossil, and some
+others identical with European species, or very nearly allied to them, make
+it highly probable that the Claiborne beds agree in age with the central or
+Bracklesham group of England, and the calcaire grossier of Paris.<a name="FNanchor_R_12" id="FNanchor_R_12"></a><a href="#Footnote_R_12" class="fnanchor">[206-B]</a></p>
+
+<p>Higher in the series is a remarkable calcareous rock, formerly called "the
+nummulite limestone," from the great number of discoid bodies resembling
+nummulites which it contains, fossils now referred by A. d'Orbigny to the
+genus <i>Orbitoides</i>, which has been demonstrated by Dr. Carpenter to belong
+to the Foraminifera.<a name="FNanchor_R_13" id="FNanchor_R_13"></a><a href="#Footnote_R_13" class="fnanchor">[206-C]</a> The following section will enable the reader to
+understand the position of the three subdivisions <span class="pagenum"><a id="page207"></a>[p.207]</span>of the series,
+Nos. 1, 2, and 3., the relations of which I ascertained in Clarke County,
+between the rivers Alabama and Tombeckbee.</p>
+
+<a id="img187" name="img187"></a>
+<div class="figcenter smaller width500">
+<p class="marbot">Fig. 190.</p>
+<img src="images/img187.jpg" width="500" height="151" alt="" title="">
+
+<table  border="0" cellpadding="2" summary="LEGEND FOR FIG.190.">
+<colgroup>
+    <col width="50%">
+    <col width="3%">
+    <col width="10%">
+    <col width="7%">
+    <col width="30%">
+</colgroup>
+
+<tr>
+  <td style="padding-top: 0.5em;" class="td-left tdtx-mid tdp-left">1. Sand, marl, &amp;c., with numerous fossils.</td>
+  <td rowspan="4">&nbsp;</td>
+  <td rowspan="3" valign="middle" style="white-space: nowrap; font-size: 80pt; font-weight: 100;" class="tdtx-top">}</td>
+  <td rowspan="4">&nbsp;</td>
+  <td rowspan="3" style="padding-top: 1.2em;" class="td-left tdtx-mid tdp-left">Eocene.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left">2. White or rotten limestone, with <i>Zeuglodon</i>.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left">3. Orbitoidal, or so called nummulitic limestone.</td>
+</tr>
+
+<tr style="padding-top: 5em;">
+  <td class="td-left tdtx-bot tdp-left">&nbsp;<br> 4. Overlying formation of sand and clay without fossils.</td>
+  <td>&nbsp;</td>
+  <td class="td-left tdtx-mid tdp-left">Age unknown.</td>
+</tr>
+</table></div>
+
+<p>The lowest set of strata, No. 1., having a thickness of more than 100 feet,
+comprise marly beds, in which the <i>Ostrea sell�formis</i> occurs, a shell
+ranging from Alabama to Virginia, and being a representative form of the
+<i>Ostrea flabellula</i> of the Eocene group of Europe. In others beds of No.
+1., two European shells, <i>Cardita planicosta</i>, before mentioned, and
+<i>Solarium canaliculatum</i> are found, with a great many other species
+peculiar to America. Numerous corals, also, and the remains of placoid fish
+and of rays occur, and the "swords," as they are called, of sword fishes,
+all bearing a great generic likeness to those of the Eocene strata of
+England and France.</p>
+
+<p>No. 2. (<a href="#img187">fig. 190.</a>) is a white limestone, sometimes soft and argillaceous,
+but in parts very compact and calcareous. It contains several peculiar
+corals, and a large Nautilus allied to <i>N. zigzag</i>, also in its upper bed a
+gigantic cetacean, called <i>Zeuglodon</i> by Owen.<a name="FNanchor_R_14" id="FNanchor_R_14"></a><a href="#Footnote_R_14" class="fnanchor">[207-A]</a></p>
+
+<a id="img188" name="img188"></a>
+<div class="figcenter smaller width500">
+<img src="images/img188.jpg" width="500" height="252" alt="" title="">
+<p><i>Zeuglodon cetoides</i>, Owen.<br><i>Basilosaurus</i>, Harlan.</p>
+<p class="martopm05">Fig. 191. Molar tooth, natural size.</p>
+<p class="martopm05">Fig. 192. Vertebra, reduced.</p></div>
+
+<p>The colossal bones of this cetacean are so plentiful in the interior of
+Clarke County as to be characteristic of the formation. The vertebral
+column of one skeleton found by Dr. Buckley at a spot visited <span class="pagenum"><a id="page208"></a>[p.208]</span>by
+me, extended to the length of nearly 70 feet, and not far off part of
+another backbone nearly 50 feet long was dug up. I obtained evidence,
+during a short excursion, of so many localities of this fossil animal
+within a distance of 10 miles, as to lead me to conclude that they must
+have belonged to at least forty distinct individuals.</p>
+
+<p>Mr. Owen first pointed out that the huge animal was not reptilian, since
+each tooth was furnished with double roots (see <a href="#img188">fig. 191.</a>), implanted in
+corresponding double sockets; and his opinion of the cetacean nature of the
+fossil was afterwards confirmed by Dr. Wyman and Professor R. W. Gibbes.
+That it was an extinct species of the whale tribe has since been placed
+beyond all doubt by the discovery of the entire skull of another fossil of
+the same family, found to have the double occipital condyles only met with
+in mammals, and the convoluted tympanic bones which are characteristic of
+cetaceans.</p>
+
+<p>Near the junction of No. 2. and the incumbent limestone, No. 3., next to be
+mentioned, are strata characterized by the following shells: Spondylus
+dumosus (<i>Plagiostoma dumosum</i>, Morton), <i>Pecten Poulsoni</i>, <i>Pecten
+perplanus</i>, and <i>Ostrea cretacea</i>.</p>
+
+<p>No. 3. (<a href="#img187">fig. 190.</a>) is a white limestone, for the most part made up of the
+<i>Orbitoides</i> of d'Orbigny before mentioned (<a href="#page206">p. 206.</a>), formerly supposed to
+be a nummulite, and called <i>N. Mantelli</i>, mixed with a few lunulites and
+small corals and shells.<a name="FNanchor_R_15" id="FNanchor_R_15"></a><a href="#Footnote_R_15" class="fnanchor">[208-A]</a> The origin of this cream-coloured soft
+stone, like that of our white chalk, which it much resembles, is, I
+believe, due to the decomposition of the orbitoides. The surface of the
+country where it prevails is sometimes marked by the absence of wood, like
+our chalk downs, or is covered exclusively by the <i>Juniperus Virginiana</i>,
+as certain chalk districts in England by yew trees and juniper.</p>
+
+<p>Some of the shells of this limestone are common to the Claiborne beds, but
+many of them are peculiar.</p>
+
+<p>It will be seen in the section (<a href="#img187">fig. 190.</a> <a href="#page155">p. 155.</a>) that the strata, Nos. 1,
+2, 3., are, for the most part, overlaid by a dense formation of sand or
+clay without fossils. In some points of the bluff or cliff of the Alabama
+river, at Claiborne, the beds Nos. 1, 2., are exposed nearly from top to
+bottom, whereas at other points the newer formation, No. 4., occupies the
+face of nearly the whole cliff. The age of this overlying mass has not yet
+been determined, as it has hitherto proved destitute of organic remains.</p>
+
+<p>The burr-stone strata of the Southern States contain so many fossils
+agreeing with those of Claiborne, that it doubtless belongs to the same
+part of the Eocene group, though I was not fortunate enough to see the
+relations of the two deposits in a continuous section. Mr. Tuomey considers
+it as the lower portion of the series. It may, perhaps, be a form of the
+Claiborne beds in places where lime was wanting, and where silex, derived
+from the decomposition of felspar, predominated. It consists chiefly of
+slaty clays, quartzose sands, and loam, of a brick red colour, with layers
+of chert or burr-stone, used in some places for millstones.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page209"></a>[p.209]</span>CHAPTER XVII.</h2>
+
+<h4>CRETACEOUS GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">Divisions of the cretaceous series in North-Western Europe &mdash; Upper
+cretaceous strata &mdash; Maestricht beds &mdash; Chalk of Faxoe &mdash; White
+chalk &mdash; Characteristic fossils &mdash; Extinct cephalopoda &mdash; Sponges
+and corals of the chalk &mdash; Signs of open and deep sea &mdash; Wide area of
+white chalk &mdash; Its origin from corals and shells &mdash; Single pebbles in
+chalk &mdash; Siliceous sandstone in Germany contemporaneous with white
+chalk &mdash; Upper greensand and gault &mdash; Lower cretaceous
+strata &mdash; Atherfield section, Isle of Wight &mdash; Chalk of South of
+Europe &mdash; Hippurite limestone &mdash; Cretaceous Flora &mdash; Chalk of
+United States.</p></div>
+
+
+<p><span class="smcap">Having</span> treated in the preceding chapters of the tertiary strata, we have
+next to speak of the uppermost of the secondary groups, called the Chalk or
+Cretaceous (No. 6. Table, <a href="#page103">p. 103.</a>), because in those parts of Europe where
+it was first studied its upper members are formed of that remarkable white
+earthy limestone, termed chalk (<i>creta</i>). The inferior division consists,
+for the most part, of clays and sands, called Greensand, because some of
+the sands derive a bright green colour from intermixed grains of chloritic
+matter. The cretaceous strata in the north-west of Europe may be thus
+divided<a name="FNanchor_S_1" id="FNanchor_S_1"></a><a href="#Footnote_S_1" class="fnanchor">[209-A]</a>:</p>
+
+
+<table  border="0" cellpadding="2" summary="DIVISION OF CRETACEOUS STRAT IN EUROPE.">
+<colgroup>
+    <col width="20%">
+    <col width="60%">
+    <col width="20%">
+</colgroup>
+
+<tr>
+  <td colspan="2" class="td-center tdtx-top ftsize105"><i>Upper Cretaceous.</i></td>
+  <td rowspan="10">&nbsp;</td>
+</tr>
+
+<tr>
+  <td rowspan="6">&nbsp;</td>
+  <td class="td-left min1em">1. Maestricht beds and Faxoe limestone.</td>
+</tr>
+
+<tr>
+  <td class="td-left min1em">2. Upper white chalk, with flints.</td>
+</tr>
+
+<tr>
+  <td class="td-left min1em">3. Lower white chalk, without flints, passing downwards into chalk marl,
+  which is slightly argillaceous.</td>
+</tr>
+
+<tr>
+  <td class="td-left min1em">4. Upper greensand.</td>
+</tr>
+
+<tr>
+  <td class="td-left min1em">5. Gault.</td>
+</tr>
+
+<tr>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td colspan="2" class="td-center tdtx-top ftsize105"><i>Lower Cretaceous.</i></td>
+</tr>
+
+<tr>
+  <td>&nbsp;</td>
+  <td class="td-left min1em">6. Lower greensand&mdash;Ironsand, clay, and occasional beds of limestone
+  (Kentish rag).</td>
+</tr>
+</table>
+
+
+<p><i>Maestricht Beds.</i>&mdash;On the banks of the Meuse, at Maestricht, reposing on
+ordinary white chalk with flints, we find an upper calcareous formation
+about 100 feet thick, the fossils of which are, on the whole, very
+peculiar, and all distinct from tertiary species. Some <span class="pagenum"><a id="page210"></a>[p.210]</span>few are of
+species common to the inferior white chalk, among which may be mentioned
+<i>Belemnites mucronatus</i> (see <a href="#img193">fig. 197.</a>) and <i>Pecten quadricostatus</i>.
+Besides the Belemnite there are other <i>genera</i>, such as Ammonite, Baculite,
+and Hamite, never found in strata newer than the cretaceous, but frequently
+met with in these Maestricht beds. On the other hand, Volutes and other
+genera of univalve shells, usually met with only in tertiary strata, occur.</p>
+
+<p>The upper part of the rock, about 20 feet thick, as seen in St. Peter's
+Mount, in the suburbs of Maestricht, abounds in corals, often detachable
+from the matrix; and these beds are succeeded by a soft yellowish limestone
+50 feet thick, extensively quarried from time immemorial for building. The
+stone below is whiter, and contains occasional nodules of grey chert or
+chalcedony.</p>
+
+<p>M. Bosquet, with whom I lately examined this formation (August, 1850),
+pointed out to me a layer of chalk from 2 to 4 inches thick, containing
+green earth and numerous encrinital stems, which forms the line of
+demarcation between the strata containing the fossils peculiar to
+Maestricht and the white chalk below. The latter is distinguished by
+regular layers of black flint in nodules, and by several shells, such as
+<i>Terebratula carnea</i> (see <a href="#img197">fig. 201.</a>), wholly wanting in beds higher than
+the green band. Some of the organic remains, however, for which St. Peter's
+Mount is celebrated, occur both above and below that parting layer, and,
+among others, the great marine reptile, called <i>Mosasaurus</i>, a saurian
+supposed to have been 24 feet in length, of which the entire skull and a
+great part of the skeleton have been found. Such remains are chiefly met
+with in the soft freestone, the principal member of the Maestricht beds.</p>
+
+<p><i>Chalk of Faxoe.</i>&mdash;In the island of Seeland, in Denmark, the newest member
+of the chalk series, seen in the sea-cliffs at Stevens Klint resting on
+white chalk with flints, is a yellow limestone, a portion of which, at
+Faxoe, where it is used as a building-stone, is composed of corals, even
+more conspicuously than is usually observed in recent coral reefs. It has
+been quarried to the depth of more than 40 feet, but its thickness is
+unknown. The imbedded shells are chiefly casts, many of them of univalve
+mollusca, which, as they strictly belong to the Cretaceous era, are worthy
+of notice, since such forms, whether spiral or patelliform, are wanting in
+the white chalk of Europe generally. Thus, there are two species of
+<i>Cypr�a</i>, one of <i>Oliva</i>, two of <i>Mitra</i>, four of the genus <i>Cerithium</i>,
+six of <i>Fusus</i>, two of <i>Trochus</i>, one <i>Patella</i>, one <i>Emarginula</i>, &amp;c., on
+the whole, more than thirty univalves, spiral or patelliform, not one of
+which is common to the white chalk. At the same time, a large proportion of
+the accompanying bivalve shells, echinoderms, and zoophytes, are
+specifically identical with fossils of older parts of the Cretaceous
+series. Among the cephalopoda of Faxoe, may be mentioned <i>Baculites
+Faujasii</i> and <i>Belemnites mucronatus</i>, shells of the white chalk.</p>
+
+<p>The claws and entire shell of a small crab, <i>Brachyurus rugosus</i>
+(Schlotheim), are scattered through the Faxoe stone, reminding us <span class="pagenum"><a id="page211"></a>[p.211]</span>
+of similar crustaceans enclosed in the rocks of many modern coral
+reefs.<a name="FNanchor_S_2" id="FNanchor_S_2"></a><a href="#Footnote_S_2" class="fnanchor">[211-A]</a> Some small portions of this coralline formation consist of
+white earthy chalk; it is, therefore, clear that this substance must have
+been produced simultaneously, a fact of some importance, as bearing on the
+theory of the origin of white chalk; for the decomposition of such corals
+as we see at Faxoe is capable, we know, of forming white mud,
+undistinguishable from chalk, and which we may suppose to have been
+dispersed far and wide through the ocean, in which such reefs as that of
+Faxoe grew.</p>
+
+<a id="img189" name="img189"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 193.</p>
+<img src="images/img189.jpg" width="500" height="051" alt="" title="">
+<p>Section from Hertfordshire, in England, to Sena, in France.</p></div>
+
+<p><i>White Chalk</i> (2. and 3. Tab. <a href="#page209">p. 209.</a>).&mdash;The highest beds of chalk in
+England and France consist of a pure, white, calcareous mass, usually too
+soft for a building stone, but sometimes passing into a more solid state.
+It consists, almost purely, of carbonate of lime; the stratification is
+often obscure, except where rendered distinct by interstratified layers of
+flint, a few inches thick, occasionally in continuous beds, but oftener in
+nodules, and recurring at intervals from 2 to 4 feet distant from each
+other.</p>
+
+<p>This upper chalk is usually succeeded, in the descending order, by a great
+mass of white chalk without flints, below which comes the chalk marl, in
+which there is a slight admixture of argillaceous matter. The united
+thickness of the three divisions in the south of England equals, in some
+places, 1000 feet.<a name="FNanchor_S_3" id="FNanchor_S_3"></a><a href="#Footnote_S_3" class="fnanchor">[211-B]</a></p>
+
+<p>The annexed section, <a href="#img189">fig. 193.</a>, will show the manner in which the white
+chalk extends from England into France, covered by the tertiary strata
+described in former chapters, and reposing on lower cretaceous beds.</p>
+
+<p>Among the conspicuous forms of mollusca wholly foreign to the tertiary and
+recent periods, and which we meet with in the white chalk, are the
+Belemnite, Ammonite, Baculite, and Turrilite, all genera of <i>Cephalopoda</i>,
+a family to which the living cuttle-fish and nautilus belong.</p>
+
+<a id="img190" name="img190"></a>
+<div class="floatleft smaller width225">
+<p>Fig. 194.</p>
+<img src="images/img190.jpg" width="225" height="131" alt="" title="">
+<p>Portion of <i>Baculites Faujasii</i>. Maestricht and
+Faxoe beds and white chalk.</p></div>
+
+<a id="img191" name="img191"></a>
+<div class="floatright smaller width225">
+<p>Fig. 195.</p>
+<img src="images/img191.jpg" width="225" height="099" alt="" title="">
+<p>Portion of <i>Baculites anceps</i>. Maestricht and
+Faxoe beds and white chalk.</p></div>
+
+<span class="pagenum"><a id="page212"></a>[p.212]</span>
+<a id="img192" name="img192"></a>
+<div class="figcenter nofloat smaller width400">
+<p>Fig. 196.</p>
+<img src="images/img192.jpg" width="400" height="120" alt="" title="">
+<ul class="leftal smaller add1em min1em">
+<li><i>a.</i> <i>Turrilites costatus.</i> Chalk marl.</li>
+<li><i>b.</i> Same, showing the indented border of the partition of the chambers.</li>
+</ul></div>
+
+<a id="img193" name="img193"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 197.</p>
+<img src="images/img193.jpg" width="400" height="057" alt="" title="">
+<ul class="leftal smaller add1em min1em">
+<li><i>a.</i> <i>Belemnites mucronatus.</i></li>
+<li><i>b.</i> Same, showing internal structure.</li>
+</ul>
+<p>Maestricht, Faxoe, and white chalk.</p></div>
+
+<p>Among the brachiopoda in the white chalk, the <i>Terebratul�</i> are very
+abundant. These shells are known to live at the bottom of the sea, where
+the water is tranquil and of some depth (see <a href="#img194">figs. 198</a>, <a href="#img195">199</a>, <a href="#img196">200</a>,<a href="#img197"> 201.</a>).
+With these are associated some forms of oyster (see <a href="#img198">figs. 202.</a> and <a href="#img200">204.</a>),
+and other bivalves (<a href="#img199">figs. 203</a>, <a href="#img201">205</a>, <a href="#img202">206</a>, <a href="#img203">207</a>, <a href="#img204">208.</a>).</p>
+
+<a id="img194" name="img194"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 198.</p>
+<img src="images/img194.jpg" width="200" height="172" alt="" title="">
+<p><i>Terebratula plicatilis</i>, dorsal view. Upper white
+chalk.</p></div>
+
+<a id="img195" name="img195"></a>
+<div class="floatright smaller width150">
+<p>Fig. 199.</p>
+<img src="images/img195.jpg" width="150" height="195" alt="" title="">
+<p><i>Terebratula plicatilis</i>, side view.</p></div>
+
+<a id="img196" name="img196"></a>
+<div class="figcenter nofloat smaller width150">
+<p>Fig. 200.</p>
+<img src="images/img196.jpg" width="150" height="336" alt="" title="">
+<p><i>Terebratula pumilus.</i> (<i>Magas pumilus</i>, Sow.)
+Upper white chalk.</p></div>
+
+<a id="img197" name="img197"></a>
+<div class="figcenter smaller width175">
+<p class="martop2">Fig. 201.</p>
+<img src="images/img197.jpg" width="175" height="195" alt="" title="">
+<p><i>Terebratula carnea.</i> Upper white chalk.</p></div>
+
+<a id="img198" name="img198"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 202.</p>
+<img src="images/img198.jpg" width="350" height="147" alt="" title="">
+<p><i>Ostrea vesicularis.</i> <i>Gryph�a globosa</i>, Min. Con.
+Upper chalk and upper greensand.</p></div>
+
+<a id="img199" name="img199"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 203.</p>
+<img src="images/img199.jpg" width="200" height="222" alt="" title="">
+<p><i>Pecten 5-costatus.</i> White chalk, upper and lower
+greensands.</p></div>
+
+<a id="img200" name="img200"></a>
+<div class="floatright smaller width300">
+<p>Fig. 204.</p>
+<img src="images/img200.jpg" width="300" height="117" alt="" title="">
+<p><i>Ostrea carinata.</i> Chalk marl, upper and lower
+greensands.</p></div>
+
+<span class="pagenum"><a id="page213"></a>[p.213]</span>
+<a id="img201" name="img201"></a>
+<div class="figcenter nofloat smaller width125">
+<p>Fig. 205.</p>
+<img src="images/img201.jpg" width="100" height="086" alt="" title="">
+<p><i>Crania Parisiensis</i>, inferior or
+attached valve. Upper white chalk.</p></div>
+
+<a id="img202" name="img202"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 206.</p>
+<img src="images/img202.jpg" width="200" height="185" alt="" title="">
+<p><i>Plagiostoma Hoperi</i>, Sow. Syn. <i>Lima Hoperi</i>.
+White chalk and upper greensand.</p></div>
+
+<a id="img203" name="img203"></a>
+<div class="floatright smaller width200">
+<p>Fig. 207.</p>
+<img src="images/img203.jpg" width="200" height="215" alt="" title="">
+<p><i>Plagiostoma spinosum</i>, Sow. Syn. <i>Spondylus
+spinosus</i>. Upper white chalk.</p></div>
+
+<p class="nofloat">Among the rest, no form marks the cretaceous era in Europe, America, and
+India, in a more striking manner than the extinct genus <i>Inoceramus</i>
+(<i>Catillus</i> of Lamk.), the shells of which are distinguished by a fibrous
+texture, and are often met with in fragments, having, probably, been
+extremely friable.</p>
+
+<a id="img204" name="img204"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 208.</p>
+<img src="images/img204.jpg" width="300" height="341" alt="" title="">
+<p><i>Inoceramus Lamarckii.</i><br>
+Syn. <i>Catillus Lamarckii</i>.</p>
+<p class="martopm05">White Chalk (Dixon's Geol. Sussex, Tab. 28. fig. 29.)</p></div>
+
+<a id="img205" name="img205"></a>
+<div class="figcenter smaller width350">
+<p class="martopm05">Fig. 209.</p>
+<img src="images/img205.jpg" width="350" height="148" alt="" title="">
+<p><i>Eschara disticha.</i></p>
+<ul class="leftal martopm05 add1em">
+<li><i>a.</i> Natural size.</li>
+<li><i>b.</i> Portion magnified.</li>
+</ul>
+<p>White chalk.</p></div>
+
+<a id="img206" name="img206"></a>
+<div class="figcenter smaller width350">
+<img src="images/img206.jpg" width="350" height="179" alt="" title="">
+<p>A branching sponge in a flint, from the white chalk. From the
+collection of Mr. Bowerbank.</p></div>
+
+<p>With these mollusca are many corals (<a href="#img205">figs. 209</a>, <a href="#img206">210</a>, <a href="#img206">211.</a>) and sea urchins
+(<a href="#img207">fig. 212.</a>), which are alike marine, and, for the most part, indicative of
+a deep sea. They are dispersed indifferently through the soft chalk, and
+hard flint, and some of the flinty nodules owe their irregular forms to
+inclosed <span class="pagenum"><a id="page214"></a>[p.214]</span>zoophytes, as in the specimen represented in <a href="#img206">fig. 211.</a>,
+where the hollows in the exterior are caused by the branches of a sponge
+seen on breaking open the flint, <a href="#img206">fig. 210.</a></p>
+
+<a id="img207" name="img207"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 212.</p>
+<img src="images/img207.jpg" width="400" height="141" alt="" title="">
+<p><i>Ananchytes ovata</i><span class="wosp05">. White</span> chalk, upper and lower.</p>
+<ul class="smaller martopm05 leftal min1em add1em">
+<li><i>a</i>. Side view.</li>
+<li><i>b</i>. Bottom of the shell on which both the oral and anal apertures are placed;
+the anal being more round, and at the smaller end.</li>
+</ul></div>
+
+<p>Of the singular family called <i>Rudistes</i>, by Lamarck, hereafter to be
+mentioned, as extremely characteristic of the chalk of Southern Europe, a
+single representative only (<a href="#img208">fig. 213.</a>) has been discovered in the white
+chalk of England.</p>
+
+<a id="img208" name="img208"></a>
+<div class="figcenter smaller width400">
+<img src="images/img208.jpg" width="400" height="282" alt="" title="">
+<p><i>Hippurites Mortoni</i>, <span class="wosp05">Mantell. Houghton,</span> <span class="wosp05">Sussex. White</span>
+chalk. Diameter one seventh of nat. size.</p>
+<ul class="martopm05 smaller leftal">
+<li>Fig. 213. Two individuals deprived of their opercula, adhering together.</li>
+<li class="min2em add3xem">214. Same seen from above.</li>
+<li class="min2em add3xem">215. Transverse section of part of the wall of the shell, magnified to show the structure.</li>
+<li class="min2em add3xem">216. Vertical section of the same.</li>
+</ul>
+<p style="text-align: justify;" class="martopm05">On the side where the shell is thinnest, there is one external furrow and
+corresponding internal ridge, a, b. <a href="#img208">figs. 213</a>, <a href="#img208">214.</a>; but they are usually
+less prominent than in these figures. This species has been referred to
+<i>Hippurites</i>, but does not, I believe, fully agree in character with that
+genus. I have never seen the opercular piece, or <i>valve</i>, as it is called
+by those conchologists who regard the <i>Rudistes</i> as bivalve mollusca. The
+specimen above figured was discovered by the late Mr. Dixon.</p></div>
+
+<p>The remains of fishes of the Upper Cretaceous formations consist chiefly of
+teeth of the shark family of genera, in part common to the tertiary, and
+partly distinct. But we meet with no bones of land animals, nor any
+terrestrial or fluviatile shells, nor any plants, except sea weeds, and
+here and there a piece of drift wood. All the appearances concur in leading
+us to conclude that the white chalk was the product of an open sea of
+considerable depth.</p>
+
+<p>The existence of turtles and oviparous saurians, and of a Pterodactyl or
+winged-lizard, found in the white chalk of Maidstone, implies, <span class="pagenum"><a id="page215"></a>[p.215]</span>no
+doubt, some neighbouring land; but a few small islets in mid-ocean, like
+Ascension, so much frequented by migratory droves of turtles, might perhaps
+have afforded the required retreat where these creatures might lay their
+eggs in the sand, or from which the flying species may have been blown out
+to sea. Of the vegetation of such islands we have scarcely any indication,
+but it consisted partly of cycadeous plants; for a fragment of one of these
+was found by Capt. Ibbetson in the chalk marl of the Isle of Wight, and is
+referred by A. Brongniart to <i>Clathraria Lyellii</i>, Mantell, a species
+common to the antecedent Wealden period.</p>
+
+<p><i>Geographical extent and origin of the While Chalk.</i>&mdash;The area over which
+the white chalk preserves a nearly homogeneous aspect is so vast, that the
+earlier geologists despaired of discovering any analogous deposits of
+recent date. Pure chalk, of nearly uniform aspect and composition, is met
+with in a north-west and south-east direction, from the north of Ireland to
+the Crimea, a distance of about 1140 geographical miles; and in an opposite
+direction it extends from the south of Sweden to the south of Bordeaux, a
+distance of about 840 geographical miles. In Southern Russia, according to
+Sir R. Murchison, it is sometimes 600 feet thick, and retains the same
+mineral character as in France and England, with the same fossils,
+including <i>Inoceramus Cuvieri</i>, <i>Belemnites mucronatus</i>, and <i>Ostrea
+vesicularis</i>.</p>
+
+<p>But it would be an error to imagine, that the chalk was ever spread out
+continuously over the whole of the space comprised within these limits,
+although it prevailed in greater or less thickness over large portions of
+that area. On turning to those regions of the Pacific where coral reefs
+abound, we find some archipelagoes of lagoon islands, such as that of the
+Dangerous Archipelago, for instance, and that of Radack, with several
+adjoining groups, which are from 1100 to 1200 miles in length, and 300 or
+400 miles broad; and the space to which Flinders proposed to give the name
+of the Corralline Sea is still larger; for it is bounded on the east by the
+Australian barrier&mdash;all formed of coral rock,&mdash;on the west by New
+Caledonia, and on the north by the reefs of Louisiade. Although the islands
+in these areas may be thinly sown, the mud of the decomposing zoophytes may
+be scattered far and wide by oceanic currents. That this mud would resemble
+chalk I have already hinted when speaking of the Faxoe limestone, <a href="#page211">p. 211.</a>;
+and it was also remarked in an early part of this volume, that some even of
+that chalk which appears to an ordinary observer quite destitute of organic
+remains, is nevertheless, when seen under the microscope, full of fragments
+of corals and sponges; together with the valves of entomostraca, the shells
+of foraminifera, and still more minute infusoria.<a name="FNanchor_S_4" id="FNanchor_S_4"></a><a href="#Footnote_S_4" class="fnanchor">[215-A]</a> (See <a href="#page26">p. 26.</a>)</p>
+
+<p>Now it had been often suspected, before these discoveries, that white chalk
+might be of animal origin, even where every trace of organic structure has
+vanished. This bold idea was partly founded <span class="pagenum"><a id="page216"></a>[p.216]</span>on the fact, that the
+chalk consisted of pure carbonate of lime, such as would result from the
+decomposition of testacea, echini, and corals; and partly on the passage
+observable between these fossils when half decomposed and chalk. But this
+conjecture seemed to many naturalists quite vague and visionary, until its
+probability was strengthened by new evidence brought to light by modern
+geologists.</p>
+
+<p>We learn from Lieutenant Nelson, that, in the Bermuda Islands, there are
+several basins or lagoons almost surrounded and enclosed by reefs of coral.
+At the bottom of these lagoons a soft white calcareous mud is formed by the
+decomposition of <i>Eschara</i>, <i>Flustra</i>, <i>Cellepora</i>, and other corallines.
+This mud, when dried, is undistinguishable from common white earthy chalk;
+and some portions of it, presented to the Museum of the Geological Society
+of London, might, after full examination, be mistaken for ancient chalk,
+but for the labels attached to them. About the same time Mr. C. Darwin
+observed similar facts in the coral islands of the Pacific; and came also
+to the opinion, that much of the soft white mud found at the bottom of the
+sea near coral reefs has passed through the bodies of worms, by which the
+stony masses of coral are everywhere bored; and other portions through the
+intestines of fishes; for certain gregarious fishes of the genus <i>Sparus</i>
+are visible through the clear water, browsing quietly, in great numbers, on
+living corals, like grazing herds of graminivorous quadrupeds. On opening
+their bodies, Mr. Darwin found their intestines filled with impure chalk.
+This circumstance is the more in point, when we recollect how the fossilist
+was formerly puzzled by meeting, in chalk, with certain bodies, called
+cones of the larch, which were afterwards recognized by Dr. Buckland to be
+the excrement of fish.<a name="FNanchor_S_5" id="FNanchor_S_5"></a><a href="#Footnote_S_5" class="fnanchor">[216-A]</a> These spiral coprolites (see figures), like
+the scales and bones of fossil fish in the chalk, are composed chiefly of
+phosphate of lime.</p>
+
+<a id="img209" name="img209"></a>
+<div class="smaller floatright width 200">
+<img src="images/img209.jpg" width="200" height="211" alt="" title="">
+<p>Coprolites of fish called <i>Iulo-eido-copri</i>, from the chalk.</p></div>
+
+<p>Mr. Dana, when describing the elevated coral reef of Oahu, in the Sandwich
+Islands, says, that some varieties of the rock consist of aggregated
+shells, imbedded in a compact calcareous base as firm in texture as any
+secondary limestone; while others are like chalk, having its colour, its
+earthy fracture, its soft homogeneous texture, and being an equally good
+writing material. The same author describes, in many growing coral reefs, a
+similar formation of modern chalk, undistinguishable from the
+ancient.<a name="FNanchor_S_6" id="FNanchor_S_6"></a><a href="#Footnote_S_6" class="fnanchor">[216-B]</a> The extension over a wide submarine area of the calcareous
+matrix of the chalk, as well as of the imbedded fossils, would take place
+the more readily, in consequence of the low specific gravity of the shells
+of mollusca and zoophytes, when compared with ordinary sand and mineral
+matter. The mud also derived from their decomposition would be much lighter
+<span class="pagenum"><a id="page217"></a>[p.217]</span>than argillaceous and other inorganic mud, and very easily
+transported by currents, especially in salt water.</p>
+
+<p><i>Single pebbles in chalk.</i>&mdash;The general absence of sand and pebbles in the
+white chalk has been already mentioned; but the occurrence here and there,
+in the south-east of England, of a few isolated pebbles of quartz and green
+schist, some of them 2 or 3 inches in diameter, has justly excited much
+wonder. If these had been carried to the spots where we now find them by
+waves or currents from the lands once bordering the cretaceous sea, how
+happened it that no sand or mud were transported thither at the same time?
+We cannot conceive such rounded stones to have been drifted like erratic
+blocks by ice<a name="FNanchor_S_7" id="FNanchor_S_7"></a><a href="#Footnote_S_7" class="fnanchor">[217-A]</a>, for that would imply a cold climate in the Cretaceous
+period; a supposition inconsistent with the luxuriant growth of large
+chambered univalves, numerous corals, and many fish, and other fossils of
+tropical forms.</p>
+
+<p>Now in Keeling Island, one of those detached masses of coral which rise up
+in the wide Pacific, Captain Ross found a single fragment of greenstone,
+where every other particle of matter was calcareous; and Mr. Darwin
+concludes that it must have come there entangled in the roots of a large
+tree. He reminds us that Chamisso, the distinguished naturalist who
+accompanied Kotzebue, affirms, that the inhabitants of the Radack
+archipelago, a group of lagoon islands, in the midst of the Pacific,
+obtained stones for sharpening their instruments by searching the roots of
+trees which are cast up on the beach.<a name="FNanchor_S_8" id="FNanchor_S_8"></a><a href="#Footnote_S_8" class="fnanchor">[217-B]</a></p>
+
+<p>It may perhaps be objected, that a similar mode of transport cannot have
+happened in the cretaceous sea, because fossil wood is very rare in the
+chalk. Nevertheless wood is sometimes met with, and in the same parts of
+the chalk where the pebbles are found, both in soft stone and in a
+silicified state in flints. In these cases it has often every appearance of
+having been floated from a distance, being usually perforated by
+boring-shells, such as the <i>Teredo</i> and <i>Fistulana</i>.<a name="FNanchor_S_9" id="FNanchor_S_9"></a><a href="#Footnote_S_9" class="fnanchor">[217-C]</a></p>
+
+<p>The only other mode of transport which suggests itself is sea-weed. Dr.
+Beck informs me, that in the Lym-Fiord, in Jutland, the <i>Fucus
+vesiculosus</i>, often called kelp, sometimes grows to the height of 10 feet,
+and the branches rising from a single root form a cluster several feet in
+diameter. When the bladders are distended, the plant becomes so buoyant as
+to float up loose stones several inches in diameter, and these are often
+thrown by the waves high up on the beach. The <i>Fucus giganteus</i> of
+Solander, so common in Terra del Fuego, is said by Captain Cook to attain
+the length of 360 feet, although the stem is not much thicker than a man's
+thumb. It is often met with floating at sea, with shells attached, several
+hundred miles from the spots where it grew. Some of these plants, says Mr.
+Darwin, were found adhering to large loose stones in the inland channels of
+Terra del Fuego, during the voyage of the Beagle in <span class="pagenum"><a id="page218"></a>[p.218]</span>1834; and
+that so firmly, that the stones were drawn up from the bottom into the
+boat, although so heavy that they could scarcely be lifted in by one
+person. Some fossil sea-weeds have been found in the Cretaceous formation,
+but none, as yet, of large size.</p>
+
+<p>But we must not imagine that because pebbles are so rare in the white chalk
+of England and France there are no proofs of sand, shingle, and clay having
+been accumulated contemporaneously even in the European seas. The siliceous
+sandstone, called "upper quader" by the Germans, overlies white
+argillaceous chalk, or "pl�ner-kalk," a deposit resembling in composition
+and organic remains the chalk marl of the English series. This sandstone
+contains as many fossil shells common to our white chalk as could be
+expected in a sea-bottom formed of such different materials. It sometimes
+attains a thickness of 600 feet, and by its jointed structure and vertical
+precipices, plays a conspicuous part in the picturesque scenery of Saxon
+Switzerland, near Dresden.</p>
+
+<p><i>Upper greensand</i> (4. Tab. <a href="#page209">p. 209.</a>).&mdash;The lower chalk without flints passes
+gradually downwards, in the south of England, into an argillaceous
+limestone, "the chalk marl," already alluded to, in which ammonites and
+other cephalopoda, so rare in the higher parts of the series, appear. This
+marly deposit passes in its turn into beds containing green particles of a
+chloritic mineral, called the upper greensand. In parts of Surrey
+calcareous matter is largely intermixed, forming a stone called
+<i>firestone</i>. In the cliffs of the southern coast of the Isle of Wight, this
+upper greensand is 100 feet thick, and contains bands of siliceous
+limestone and calcareous sandstone with nodules of chert.</p>
+
+<a id="img210" name="img210"></a>
+<div class="figcenter width500 smaller">
+<p>Fossils of the Upper Greensand.</p>
+<img src="images/img210.jpg" width="500" height="156" alt="" title="">
+<p class="floatleft">Fig. 219.</p>
+
+<table  style="width: 50%; text-align: left; margin-left: 1%;" border="0" cellpadding="2" summary="LEGEND FOR FIG. 119." class="floatleft">
+<colgroup>
+    <col width="50%">
+    <col width="10%">
+    <col width="40%">
+</colgroup>
+
+<tr>
+  <td class="td-left tdtx-bot"><i>a.</i> <i>Terebratula lyra.</i></td>
+  <td rowspan="2" valign="middle" style="white-space: nowrap; font-size: 30pt; font-weight: 100;" class="tdtx-top">}</td>
+  <td class="td-left tdtx-bot tdp-left">Upper greensand.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top"><i>b.</i> Same, seen in profile.</td>
+  <td class="td-left tdtx-top tdp-left">France.</td>
+</tr>
+</table>
+
+<p style="margin-top: -3em;" class="floatright add4em">Fig. 220. <i>Ammonites Rhotomagensis.</i><br>Upper greensand.</p></div>
+
+<a id="img211" name="img211"></a>
+<div class="figcenter nofloat width350 smaller">
+<p class="martopm05">Fig. 221.</p>
+<img src="images/img211.jpg" width="350" height="210" alt="" title="">
+<p><i>Hamites spiniger</i> (Fitton); near <span class="wosp05">Folkstone. Gault.</span></p></div>
+
+<p><i>Gault.</i>&mdash;The lowest member of the upper Cretaceous group, usually about
+100 feet thick in the S.E. of England, is provincially termed <span class="pagenum"><a id="page219"></a>[p.219]</span>
+Gault. It consists of a dark blue marl, sometimes intermixed with
+greensand. Many peculiar forms of cephalopoda, such as the <i>Hamite</i> (<a href="#img211">fig.
+221.</a>) and <i>Scaphite</i>, with other fossils, characterize this formation,
+which, small as is its thickness, can be traced by its organic remains to
+distant parts of Europe, as, for example, to the Alps.</p>
+
+<p>The phosphate of lime, found lately near Farnham, in Surrey, in such
+abundance as to be used largely by the agriculturist for fertilizing soils,
+occurs exclusively, according to Mr. R. A. C. Austen, in the upper
+greensand and gault. It is doubtless of animal origin, and partly
+coprolitic, probably derived from the excrement of fish.</p>
+
+
+<h3>LOWER CRETACEOUS DIVISION. (No. 6. Tab. <a href="#page209">p. 209.</a>)</h3>
+
+<p>That part of the Cretaceous series which is older than the Gault has been
+commonly called the Lower Greensand. The greater number of its fossils are
+specifically distinct from those of the upper cretaceous system. Dr.
+Fitton, to whom we are indebted for an excellent monograph on this
+formation as developed in England, gives the following as the succession of
+rocks seen in parts of Kent.</p>
+
+
+<table  border="0" cellpadding="2" summary="SUCCESSION OF ROCKS SEEN IN KENT.">
+<colgroup>
+    <col width="10%">
+    <col width="50%">
+    <col width="40%">
+</colgroup>
+
+<tr>
+  <td class="td-right tdtx-top">No.</td>
+  <td class="td-left tdtx-top">1. Sand, white, yellowish, or ferruginous, with concretions
+  of limestone and chert</td>
+  <td class="td-left tdtx-bot tdp-left">70 feet.</td>
+</tr>
+
+<tr>
+  <td rowspan="2">&nbsp;</td>
+  <td class="td-left tdtx-top">2. Sand with green matter</td>
+  <td class="td-left tdtx-bot tdp-left">70 to 100 feet.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">3. Calcareous stone, called Kentish rag</td>
+  <td class="td-left tdtx-bot tdp-left">60 to 80 feet.</td>
+</tr>
+</table>
+
+
+<p>In his detailed description of the fine section displayed at Atherfield, in
+the south of the Isle of Wight, we find the limestone wholly wanting; in
+fact, the variations in the mineral composition of this group, even in
+contiguous districts, is very great; and on comparing the Atherfield beds
+with corresponding strata at Hythe in Kent, distant 95 miles, the whole
+series has lost half its thickness, and presents a very dissimilar
+aspect.<a name="FNanchor_S_10" id="FNanchor_S_10"></a><a href="#Footnote_S_10" class="fnanchor">[219-A]</a></p>
+
+<p>On the other hand, Professor E. Forbes has shown that when the sixty-three
+strata at Atherfield are severally examined, the total thickness of which
+he gives as 843 feet, there are some fossils which range through the whole
+series, others which are peculiar to particular divisions. As a proof that
+all belong chronologically to one system, he states that whenever similar
+conditions are repeated in overlying strata the same species reappear.
+Changes of depth, or of the mineral nature of the bottom, the presence or
+absence of lime or of peroxide of iron, the occurrence of a muddy, or a
+sandy, or a gravelly bottom, are marked by the banishment of certain
+species and the predominance of others. But these differences of conditions
+being mineral, chemical, and local in their nature, have nothing to do with
+the extinction, throughout a large area, of certain animals or plants. The
+rule laid down by this eminent naturalist for enabling us to test the
+arrival of a new state of things in the animate world, is the
+representation by new and different species of corresponding <span class="pagenum"><a id="page220"></a>[p.220]</span>
+genera of mollusca or other beings. When the forms proper to loose sand or
+soft clay, or a stony or calcareous bottom, or a moderate or a great depth
+of water, recur with all the same species, the interval of time has been,
+geologically speaking, small, however dense the mass of matter accumulated.
+But if, the genera remaining the same, the species are changed, we have
+entered upon a new period; and no similarity of climate, or of geographical
+and local conditions, can then recall the old species which a long series
+of destructive causes in the animate and inanimate world has gradually
+annihilated. On passing from the lower greensand to the gault, we suddenly
+reach one of these new epochs, scarcely any of the fossil species being
+common to the lower and upper cretaceous systems, a break in the chain
+implying no doubt many missing links in the series of geological monuments
+which we may some day be able to supply.</p>
+
+<p>One of the largest and most abundant shells in the lowest strata of the
+lower greensand, as displayed in the Atherfield section, is the large
+<i>Perna mulleti</i> of which a reduced figure is here given (<a href="#img212">fig. 222.</a>).</p>
+
+<a id="img212" name="img212"></a>
+<div class="figcenter smaller width500">
+<p class="martopm05">Fig. 222.</p>
+<img src="images/img212.jpg" width="500" height="331" alt="" title="">
+<p><i>Perna mulleti</i><span class="wosp05">. Desh.</span> in Leym.</p>
+<ul class="smaller martopm5 leftal add2em">
+<li><i>a.</i> Exterior.</li>
+<li><i>b.</i> Hinge of upper valve.</li>
+</ul></div>
+
+<p>In the south of England, during the accumulation of the lower greensand
+above described, the bed of the sea appears to have been continually
+sinking, from the commencement of the period, when the freshwater Wealden
+beds were submerged, to the deposition of those strata on which the gault
+immediately reposes.</p>
+
+<p>Pebbles of quartzose sandstone, jasper, and flinty slate, together with
+grains of chlorite and mica, speak plainly of the nature of the
+pre-existing rocks, from the wearing down of which the greensand beds were
+derived. The land, consisting of such rocks, was doubtless submerged before
+the origin of the white chalk, as corals can only <span class="pagenum"><a id="page221"></a>[p.221]</span>multiply in the
+clear waters of the sea in spaces to which no mud or sand are conveyed by
+currents.</p>
+
+
+<h3>HIPPURITE LIMESTONE.</h3>
+
+<p><i>Difference between the chalk of the north and south of Europe.</i>&mdash;By the
+aid of the three tests of relative age, namely, superposition, mineral
+character, and fossils, the geologist has been enabled to refer to the same
+Cretaceous period certain rocks in the north and south of Europe, which
+differ greatly, both in their fossil contents and in their mineral
+composition and structure.</p>
+
+<p>If we attempt to trace the cretaceous deposits from England and France to
+the countries bordering the Mediterranean, we perceive, in the first place,
+that the chalk and Greensand in the neighbourhood of London and Paris form
+one great continuous mass, the Straits of Dover being a trifling
+interruption, a mere valley with chalk cliffs on both sides. We then
+observe that the main body of the chalk which surrounds Paris stretches
+from Tours to near Poitiers (see the annexed map, <a href="#img213">fig. 223.</a>, in which the
+shaded part represents chalk).</p>
+
+<a id="img213" name="img213"></a>
+<div class="figcenter smaller">
+<p>Fig. 223.</p>
+<img src="images/img213.jpg" width="300" height="531" alt="" title=""></div>
+
+<p>Between Poitiers and La Rochelle, the space marked A on the map separates
+two regions of chalk. This space is occupied by the Oolite and certain
+other formations older than the Chalk, and has been supposed by M. E. de
+Beaumont to have formed an island in the cretaceous sea. South of this
+space we again meet with a formation which we at once recognize by its
+mineral character to be chalk, although there are some places where the
+rock becomes oolitic. The fossils are, upon the whole, very similar;
+especially certain species of the genera <i>Spatangus</i>, <i>Ananchytes</i>,
+<i>Cidarites</i>, <i>Nucula</i>, <i>Ostrea</i>, <i>Gryph�a</i> (<i>Exogyra</i>), <i>Pecten</i>,
+<i>Plagiostoma</i> (<i>Lima</i>), <i>Trigonia</i>, <i>Catillus</i>, (<i>Inoceramus</i>), and
+<i>Terebratula</i>.<a name="FNanchor_S_11" id="FNanchor_S_11"></a><a href="#Footnote_S_11" class="fnanchor">[221-A]</a> But <i>Ammonites</i>, as M. d'Archiac observes, of which
+so many species are met with in the chalk of the north of France, are
+scarcely ever found in the southern region; while the genera <i>Hamite</i>,
+<i>Turrilite</i>, and <i>Scaphite</i>, and perhaps <i>Belemnite</i>, are entirely wanting.</p>
+
+<p>On the other hand, certain forms are common in the south which are rare or
+wholly unknown in the north of France. Among these may be mentioned many
+<i>Hippurites</i>, <i>Sph�rulites</i>, and other members <span class="pagenum"><a id="page222"></a>[p.222]</span>of that great
+family of mollusca called <i>Rudistes</i> by Lamarck, to which nothing analogous
+has been discovered in the living creation, but which is quite
+characteristic of rocks of the Cretaceous era in the south of France,
+Spain, Sicily, Greece, and other countries bordering the Mediterranean.</p>
+
+<a id="img214" name="img214"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 224.</p>
+<img src="images/img214.jpg" width="350" height="104" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Radiolites radiosus</i>, <span class="wosp05">D'Orb. (</span><i>Hippurites</i>, Lamk.)</li>
+<li><i>b.</i> Opercular valve of same.</li>
+</ul>
+<p class="martopm05">White chalk of France.</p></div>
+
+<a id="img215" name="img215"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 225.</p>
+<img src="images/img215.jpg" width="250" height="204" alt="" title="">
+<p><i>Radiolites foliaceus</i>, D'Orb. Syn. <i>Sph�rulites
+agariciformis</i>, Blainv. White chalk of France.</p></div>
+
+<a id="img216" name="img216"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 226.</p>
+<img src="images/img216.jpg" width="350" height="372" alt="" title="">
+<p><i>Hippurites organisans</i>, Desmoulins. Upper
+chalk:&mdash;chalk marl of Pyrenees?<a name="FNanchor_S_12" id="FNanchor_S_12"></a><a href="#Footnote_S_12" class="fnanchor">[222-A]</a></p>
+<ul class="martopm05 smaller leftal min1em">
+<li><i>a.</i> Young individual; when full grown they occur in groups adhering
+laterally to each other.</li>
+<li><i>b.</i> Upper side of the opercular valve, showing a reticulated structure in
+those parts, <i>b</i>, where the external coating is worn off.</li>
+<li><i>c.</i> Upper side of the lower and cylindrical valve.</li>
+<li><i>d.</i> Cast of the interior of the lower conical valve.</li>
+</ul></div>
+
+<p>The species called <i>Hippurites organisans</i> (<a href="#img216">fig. 226.</a>) is more abundant
+than any other in the south of Europe; and the geologist should make
+himself well acquainted with the cast <i>d</i>, which is far more common in many
+compact marbles of the upper cretaceous period than the shell itself, which
+has often wholly disappeared. The flutings, or smooth, rounded,
+longitudinal ribs, representing the form <span class="pagenum"><a id="page223"></a>[p.223]</span>of the interior, are
+wholly unlike the hippurite itself, and in some individuals, which attain a
+great size and length, are very conspicuous.</p>
+
+<p>Between the region of chalk last mentioned in which Perigueux is situated,
+and the Pyrenees, the space B intervenes. (See Map, <a href="#page221">p. 221.</a>) Here the
+tertiary strata cover, and for the most part conceal, the cretaceous rocks,
+except in some spots where they have been laid open by the denudation of
+newer formations. In these places they are seen still preserving the form
+of a white chalky rock, which is charged in part with grains of green sand.
+Even as far south as Tercis, on the Adour, near Dax, where I examined them
+in 1828, the cretaceous rocks retain this character. In that region M.
+Grateloup has found in them <i>Ananchytes ovata</i> (<a href="#img207">fig. 212.</a>), and other
+fossils of the English chalk, together with <i>Hippurites</i>.</p>
+
+
+<h3>FLORA OF THE CRETACEOUS PERIOD.</h3>
+
+<p>Although the fossil plants of the Cretaceous era at present known are few
+in number, the rocks being principally marine, they suffice, according to
+M. Ad. Brongniart, to show a transition character between the vegetation of
+the secondary and that of the tertiary formations. The tertiary strata,
+when compared to the older rocks, are marked by the predominance of
+<i>Exogens</i>, which now constitute three-fourths of the living plants of the
+globe.<a name="FNanchor_S_13" id="FNanchor_S_13"></a><a href="#Footnote_S_13" class="fnanchor">[223-A]</a></p>
+
+<p>These exogens are wanting in the secondary strata generally, but in the
+Cretaceous period they equal in number the <i>Gymnogens</i> (<i>Conifer�</i> and
+<i>Cycade�</i>) which abounded so much in the preceding Oolitic period, and
+disappeared before the Eocene rocks were formed.<a name="FNanchor_S_14" id="FNanchor_S_14"></a><a href="#Footnote_S_14" class="fnanchor">[223-B]</a> The discovery of a
+tree-fern in the ferruginous sands of the Lower Cretaceous group of the
+department of Ardennes in France is one of many signs of the contrast of
+the flora, and doubtless of the climate, of this era with that of the
+Pliocene and Modern periods.</p>
+
+
+<h3><span class="pagenum"><a id="page224"></a>[p.224]</span>CRETACEOUS ROCKS IN THE UNITED STATES.</h3>
+
+<p>If we pass to the American continent, we find in the state of New Jersey a
+series of sandy and argillaceous beds wholly unlike our Upper Cretaceous
+system; which we can, nevertheless, recognize as referable,
+paleontologically, to the same division.</p>
+
+<p>That they were about the same age generally as the European chalk and
+greensand, was the conclusion to which Dr. Morton and Mr. Conrad came after
+their investigation of the fossils in 1834. The strata consist chiefly of
+greensand and green marl, with an overlying coralline limestone of a pale
+yellow colour, and the fossils, on the whole, agree most nearly with those
+of the upper European series, from the Maestricht beds to the gault
+inclusive. I collected sixty shells from the New Jersey deposits in 1841;
+five of which were identical with European species&mdash;<i>Ostrea larva</i>, <i>O.
+vesicularis</i>, <i>Gryph�a costata</i>, <i>Pecten quinque-costatus</i>, <i>Belemnites
+mucronatus</i>. As some of these have the greatest vertical range in Europe,
+they might be expected more than any others to recur in distant parts of
+the globe. Even where the species are different, the generic forms, such as
+the Baculite and certain sections of Ammonites, as also the Inoceramus (see
+above, <a href="#img204">fig. 208.</a>) and other bivalves, have a decidedly cretaceous aspect.
+Fifteen out of the sixty shells above alluded to, were regarded by
+Professor Forbes as good geographical representatives of well-known
+cretaceous fossils of Europe. The correspondence, therefore, is not small,
+when we reflect that the part of the United States where these strata occur
+is between 3000 and 4000 miles distant from the chalk of Central and
+Northern Europe, and that there is a difference of ten degrees in the
+latitude of the places compared on opposite sides of the Atlantic.<a name="FNanchor_S_15" id="FNanchor_S_15"></a><a href="#Footnote_S_15" class="fnanchor">[224-A]</a></p>
+
+<p>Fish of the genera <i>Lamna</i>, <i>Galeus</i>, and <i>Carcharias</i> are common to New
+Jersey and the European cretaceous rocks. So also is the genus <i>Mosasaurus</i>
+among reptiles, and <i>Pliosaurus</i> (Owen), another saurian likewise obtained
+from the English chalk. From New Jersey the cretaceous formation extends
+southwards to North Carolina, Georgia, and Alabama, cropping out at
+intervals from beneath the tertiary strata, between the Appalachian
+Mountains and the Atlantic. They then sweep round the southern extremity of
+that chain, and stretch northwards again to Tennessee and Kentucky. They
+have also been traced far up the valley of the Missouri 275 English miles
+above its mouth, to the neighbourhood of Fort Leavenworth; and southwards
+to Texas, according to the observations of Ferdinand R�mer; so that already
+the area which they are ascertained to occupy in North America may perhaps
+equal their extent in Europe. So little do they resemble mineralogically
+the European white chalk, that limestone in North America is, upon the
+whole, an exception to the rule; and, even in Alabama, where I saw a
+calcareous member of this group, the marlstones are much more like the
+<span class="pagenum"><a id="page225"></a>[p.225]</span>English and French Lias than any other secondary deposit of the
+Old World.</p>
+
+<p>At the base of the system in Alabama I found dense masses of shingle,
+perfectly loose and unconsolidated, derived from the waste of paleozoic (or
+carboniferous) rocks, a mass in no way distinguishable, except by its
+position, from ordinary alluvium, but covered with marls abounding in
+Inocerami.</p>
+
+<p>In Texas, according to F. R�mer, the chalk assumes a new lithological type,
+a large portion of it consisting of hard siliceous limestone, but the
+organic remains leaving no doubt in regard to its age.</p>
+
+<p>In South America the cretaceous strata have been discovered in Columbia, as
+at Bogota and elsewhere, containing Ammonites, Hamites, Inocerami, and
+other characteristic shells.<a name="FNanchor_S_16" id="FNanchor_S_16"></a><a href="#Footnote_S_16" class="fnanchor">[225-A]</a></p>
+
+<p>In the South of India, also, at Pondicherry, Verdachellum, and
+Trinconopoly, Messrs. Kaye and Egerton have collected fossils belonging to
+the cretaceous system. Taken in connection with those from the United
+States they prove, says Prof. E. Forbes, that those powerful causes which
+stamped a peculiar character on the forms of marine animal life at this
+period, exerted their full intensity through the Indian, European, and
+American seas.<a name="FNanchor_S_17" id="FNanchor_S_17"></a><a href="#Footnote_S_17" class="fnanchor">[225-B]</a> Here, as in North and South America, the cretaceous
+character can be recognized even where there is no specific identity in the
+fossils; and the same may be said of the organic type of those rocks in
+Europe and India which succeed next in the ascending and descending order,
+the Eocene and the Oolitic.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XVIII.</h2>
+
+<h4>WEALDEN GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">The Wealden divisible into Weald Clay, Hastings Sand, and Purbeck
+Beds &mdash; Intercalated between two marine formations &mdash; Weald clay and
+Cypris-bearing strata &mdash; Iguanodon &mdash; Hastings sands &mdash; Fossil
+fish &mdash; Strata formed in shallow water &mdash; Brackish
+water-beds &mdash; Upper, middle, and lower Purbeck &mdash; Alternations of
+brackish water, freshwater, and land &mdash; Dirt-bed, or ancient
+soil &mdash; Distinct species of fossils in each subdivision of the
+Wealden &mdash; Lapse of time implied &mdash; Plants and insects of
+Wealden &mdash; Geographical extent of Wealden &mdash; Its relation to the
+cretaceous and oolitic periods &mdash; Movements in the earth's crust to
+which it owed its origin and submergence.</p></div>
+
+
+<p><span class="smcap">Beneath</span> the cretaceous rocks in the S.E. of England, a freshwater formation
+is found, called the Wealden (see Nos. 5. and 6. Map, <a href="#page242">p. 242.</a>), which,
+although it occupies a small horizontal area in Europe, as compared to the
+chalk, is nevertheless of great geological interest, not only from its
+position, as being interpolated between <span class="pagenum"><a id="page226"></a>[p.226]</span>two great marine
+formations (Nos. 7. and 9. Table, <a href="#page103">p. 103.</a>), but also because the imbedded
+fossils indicate a grand succession of changes in organic life, effected
+during its accumulation. It is composed of three minor divisions, the Weald
+Clay, the Hastings, and the Purbeck Beds, of which the aggregate thickness
+in some districts may be 700 or 800 feet; but which would be much more
+considerable (perhaps 2000 feet), were we to add together the extreme
+thickness acquired by each of them in their fullest development.</p>
+
+<p>The common name of Wealden was given to the whole, because it was first
+studied in parts of Kent, Surrey, and Sussex, called the Weald, (see Map,
+<a href="#page242">p. 242.</a>), and we are indebted to Dr. Mantell for having shown in 1822, in
+his Geology of Sussex, that the whole group was of fluviatile origin. In
+proof of this he called attention to the entire absence of Ammonites,
+Belemnites, Terebratul�, Echinites, Corals, and other marine fossils, so
+characteristic of the cretaceous rocks above, and of the Oolitic strata
+below, and to the presence of Paludin�, Melani�, and various fluviatile
+shells, as well as the bones of terrestrial reptiles and the trunks and
+leaves of land plants.</p>
+
+<a id="img217" name="img217"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 227.</p>
+<img src="images/img217.jpg" width="350" height="144" alt="" title="">
+<p>Position of the Wealden between two marine formations.</p></div>
+
+<p>The evidence of so unexpected a fact as the infra-position of a dense mass
+of purely freshwater origin to a deep-sea deposit (a phenomenon with which
+we have since become familiar, in other chapters of the earth's
+autobiography), was received, at first, with no small doubt and
+incredulity. But the relative position of the beds is unequivocal; the
+Weald Clay being distinctly seen to pass beneath the Greensand in various
+parts of Surrey, Kent, and Sussex; and if we proceed from Sussex westward
+to the Vale of Wardour, we there again observe the same formation, or, at
+least, the lower division of it, the Purbeck, occupying the same relative
+position, and resting on the Oolite (see <a href="#img218">fig. 228.</a>). Or if we pass from the
+base of the South Downs in Sussex, and cross to the Isle of Wight, we there
+again meet with the Wealden series reappearing beneath the Greensand, and
+cannot doubt that the beds are prolonged subterraneously, as indicated by
+the dotted lines in <a href="#img219">fig. 229.</a></p>
+
+<a id="img218" name="img218"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 228.</p>
+<img src="images/img218.jpg" width="400" height="068" alt="" title="">
+<ul class="leftal smaller add1em min1em">
+<li>O, Oolite.</li>
+<li>G S, Greensand, or Lower Cretaceous.</li>
+</ul></div>
+
+<span class="pagenum"><a id="page227"></a>[p.227]</span>
+<a id="img219" name="img219"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 229.</p>
+<img src="images/img219.jpg" width="450" height="109" alt="" title=""></div>
+
+<p>The minor groups into which the Wealden has been commonly divided in
+England are, as before stated, three, and they succeed each other in the
+following descending order<a name="FNanchor_T_1" id="FNanchor_T_1"></a><a href="#Footnote_T_1" class="fnanchor">[227-A]</a>:&mdash;</p>
+
+
+<table  border="0" cellpadding="2" summary="DEVISION OF WEALDEN IN ENGLAND.">
+<colgroup>
+    <col width="3%">
+    <col width="60%">
+    <col width="37%">
+</colgroup>
+
+<tr>
+  <td colspan="2">&nbsp;</td>
+  <td class="td-left tdtx-top tdp-left smaller">Thickness.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">1st.</td>
+  <td class="td-left tdtx-top tdp-left1">Weald Clay, sometimes including thin beds of sand and
+  shelly limestone</td>
+  <td class="td-left tdtx-bot tdp-left">140 to 280 ft.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">2d.</td>
+  <td class="td-left tdtx-top tdp-left1">Hastings Sand, in which occur some clays and calcareous grits</td>
+  <td class="td-left tdtx-bot tdp-left">400 to 500 ft.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">3d.</td>
+  <td class="td-left tdtx-top tdp-left1">Purbeck Beds, consisting of various kinds of limestones and marls</td>
+  <td class="td-left tdtx-bot tdp-left">150 to 200 ft.</td>
+</tr>
+</table>
+
+
+<h3><i>Weald Clay.</i></h3>
+
+<p>The first division, or Weald Clay, is of purely freshwater origin. The
+uppermost beds are not only conformable, as Dr. Fitton observes, to the
+inferior strata of the Lower Greensand, but of similar mineral composition.
+To explain this, we may suppose, that as the delta of a great river was
+tranquilly subsiding, so as to allow the sea to encroach upon the space
+previously occupied by freshwater, the river still continued to carry down
+the same sediment into the sea. In confirmation of this view it may be
+stated, that the remains of the <i>Iguanodon Mantelli</i>, a gigantic
+terrestrial reptile, very characteristic of the Wealden, has been
+discovered near Maidstone, in the overlying Kentish rag, or marine
+limestone of the Lower Greensand. Hence we may infer that some of the
+saurians which inhabited the country of the great river continued to live
+when part of the country had become submerged beneath the sea. Thus, in our
+own times, we may suppose the bones of large alligators to be frequently
+entombed in recent freshwater strata in the delta of the Ganges. But if
+part of that delta should sink down so as to be covered by the sea, marine
+formations might begin to accumulate in the same space where freshwater
+beds had previously been formed; and yet the Ganges might still pour down
+its turbid waters in the same direction, and carry seaward the carcasses of
+the same species of alligator, in which case their bones might be included
+in marine as well as in subjacent freshwater strata.</p>
+
+<p>The Iguanodon, first discovered by Dr. Mantell, has left more of its
+remains in the Wealden strata of the south-eastern counties, and Isle of
+Wight, than any other genus of associated saurians. It was an herbivorous
+reptile, and regarded by Cuvier as more extraordinary than any with which
+he was acquainted; for the teeth, though bearing a great analogy to the
+modern Iguanas which now frequent the tropical woods of America and the
+West Indies, exhibit many striking and important differences (see <a href="#img220">fig.
+230.</a>). It appears that they have <span class="pagenum"><a id="page228"></a>[p.228]</span>been worn by mastication;
+whereas the existing herbivorous reptiles clip and gnaw off the vegetable
+productions on which they feed, but do not chew them. Their teeth, when
+worn, present an appearance of having been chipped off, and never, like the
+fossil teeth of the Iguanodon, have a flat ground surface (see <a href="#img220">fig. 231.</a>),
+resembling the grinders of herbivorous mammalia. Dr. Mantell computes that
+the teeth and bones of this animal which have passed under his examination
+during the last twenty years, must have belonged to no less than
+seventy-one distinct individuals; varying in age and magnitude from the
+reptile just burst from the egg, to one of which the femur measured 24
+inches in circumference. Yet notwithstanding that the teeth were more
+numerous than any other bones, it is remarkable that it was not till the
+relics of all these individuals had been found, that a solitary example of
+part of a jaw-bone was obtained. More recently remains both of the upper
+and lower jaw have been met with in the Hastings Beds in Tilgate Forest.
+Their size was somewhat greater than had been anticipated, and even
+allowing that the tail was short, which Professor Owen infers from the
+short bodies of the caudal vertebr�, Dr. Mantell estimates the probable
+length of some of these saurians at between 30 and 40 feet. The largest
+femur yet found measures 4 feet 8 inches in length, the circumference of
+the shaft being 25 inches, and round the condyles 42 inches.</p>
+
+<a id="img220" name="img220"></a>
+<div class="figcenter smaller width350">
+<p>Teeth of Iguanodon.</p>
+<img src="images/img220.jpg" width="350" height="265" alt="" title="">
+<p>Fig. 230. Partially worn tooth of a young animal. (Mantell.)</p>
+<p class="martopm05">Fig. 231. Crown of tooth in adult, worn <span class="wosp05">down. (Mantell.)</span></p></div>
+
+<p>Occasionally bands of limestone, called Sussex Marble, occur in the Weald
+Clay, almost entirely composed of a species of <i>Paludina</i>, closely
+resembling the common <i>P. vivipara</i> of English rivers.</p>
+
+<a id="img221" name="img221"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 232.</p>
+<img src="images/img221.jpg" width="150" height="219" alt="" title="">
+<p><i>Cypris spinigera</i>, Fitton.</p></div>
+
+<a id="img222" name="img222"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 233.</p>
+<img src="images/img222.jpg" width="350" height="174" alt="" title="">
+<p><i>Cypris Valdensis</i>, Fitton. (<i>C. faba</i>, Min. Con. 485.)</p></div>
+
+<a id="img223" name="img223"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 234.</p>
+<img src="images/img223.jpg" width="250" height="156" alt="" title="">
+<p><i>Cypris tuberculata</i>, Fitton.</p></div>
+
+<a id="img224" name="img224"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 235.</p>
+<img src="images/img224.jpg" width="200" height="159" alt="" title=""></div>
+
+<p>Shells of the <i>Cypris</i>, an animal belonging to the Crustacea, and before
+mentioned (<a href="#page31">p. 31.</a>) as abounding in lakes and ponds, are also plentifully
+scattered through the clays of the Wealden, sometimes producing, like the
+plates of mica, a thin lamination (see <a href="#img224">fig. 235.</a>). Similar cypriferous
+marls are found in the lacustrine tertiary beds of Auvergne (see above, <a href="#page183">p.
+183.</a>).</p>
+
+
+<h3><span class="pagenum"><a id="page229"></a>[p.229]</span><i>Hastings Sands.</i></h3>
+
+<p>This middle division of the Wealden consists of sand, calciferous grit,
+clay, and shale; the argillaceous strata, notwithstanding the name, being
+nearly in the same proportion as the arenaceous. The calcareous sandstone
+and grit of Tilgate Forest, near Cuckfield, in which the remains of the
+Iguanodon and Hyleosaurus were first found, constitute an upper member of
+this formation. The white "sand-rock" of the Hastings cliffs, about 100
+feet thick, is one of the lower members of the same. The reptiles, which
+are very abundant in it, consist partly of saurians, already referred by
+Owen and Mantell to eight genera, among which, besides those already
+enumerated, we find the Megalosaurus and Plesiosaurus. The Pterodactyl,
+also a flying reptile, is met with in the same strata, and many remains of
+Testudinata of the genera <i>Trionyx</i> and <i>Emys</i>, now confined to tropical
+regions.</p>
+
+<a id="img225" name="img225"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 236.</p>
+<img src="images/img225.jpg" width="400" height="147" alt="" title="">
+<p><i>Lepidotus Mantelli</i>, Agass. Wealden.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> palate and teeth.</li>
+<li><i>b.</i> side view of teeth.</li>
+<li><i>c.</i> scale.</li>
+</ul></div>
+
+<p>The fishes of the Wealden belong partly to the genera <i>Pycnodus</i> and
+<i>Hybodus</i> (see figure of genus in <a href="#chaxxi">Chap. XXI.</a>), forms common to the Wealden
+and Oolite; but the teeth and scales of a species of <i>Lepidotus</i> are most
+widely diffused (see <a href="#img225">fig. 236.</a>). The general form of these fish was that of
+the carp tribe, although perfectly distinct in anatomical character, and
+more allied to the pike. The whole body was covered with large rhomboidal
+scales, very thick, and having the exposed part covered with enamel. Most
+of the species of this genus are supposed to have been either river fish,
+or inhabitants of the coasts, having not sufficient powers of swimming to
+advance into the deep sea.</p>
+
+<a id="img226" name="img226"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 237.</p>
+<img src="images/img226.jpg" width="200" height="080" alt="" title="">
+<p><i>Corbula alata</i>, <span class="wosp05">Fitton. Magnified.</span></p></div>
+
+<p>The shells of the Hastings beds belong to the genera <i>Melanopsis</i>,
+<i>Melania</i>, <i>Paludina</i>, <i>Cyrena</i>, <i>Cyclas</i>, <i>Unio</i>, and others, which
+inhabit rivers or lakes; but one band has been found in Dorsetshire
+indicating a brackish state of the water, and, in some places, even a
+saltness, like that of the sea, where the genera <i>Corbula</i> (see <a href="#img226">fig. 237.</a>),
+<i>Mytilus</i>, and <i>Ostrea</i> occur. At different heights in the Hastings Sand,
+in the middle of the Wealden, we find again and again slabs of sandstone
+with a strong <span class="pagenum"><a id="page230"></a>[p.230]</span>ripple-mark, and between these slabs beds of clay
+many yards thick. In some places, as at Stammerham, near Horsham, there are
+indications of this clay having been exposed so as to dry and crack before
+the next layer was thrown down upon it. The open cracks in the clay have
+served as moulds, of which casts have been taken in relief, and which are,
+therefore, seen on the lower surface of the sandstone (see <a href="#img227">fig. 238.</a>).</p>
+
+<a id="img227" name="img227"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 238.</p>
+<img src="images/img227.jpg" width="400" height="335" alt="" title="">
+<p>Underside of slab of sandstone about one yard in diameter.
+Stammerham, Sussex.</p></div>
+
+<p>Near the same place a reddish sandstone occurs in which are innumerable
+traces of a fossil vegetable, apparently <i>Sphenopteris</i>, the stems and
+branches of which are disposed as if the plants were standing erect on the
+spot where they originally grew, the sand having been gently deposited upon
+and around them; and similar appearances have been remarked in other places
+in this formation.<a name="FNanchor_T_2" id="FNanchor_T_2"></a><a href="#Footnote_T_2" class="fnanchor">[230-A]</a> In the same division also of the Wealden, at
+Cuckfield, is a bed of gravel or conglomerate, consisting of water-worn
+pebbles of quartz and jasper, with rolled bones of reptiles. These must
+have been drifted by a current, probably in water of no great depth.</p>
+
+<a id="img228" name="img228"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 239.</p>
+<img src="images/img228.jpg" width="300" height="220" alt="" title="">
+<p><i>Sphenopteris gracilis</i> (Fitton), from near Tunbridge Wells.</p>
+<p class="martopm05"><i>a.</i> portion of the same magnified.</p></div>
+
+<p>From such facts we may infer that, notwithstanding the great thickness of
+this division of the Wealden (and the same observation applies to the Weald
+Clay and Purbeck Beds), the whole of it was a deposit in water of a
+moderate depth, and often extremely shallow. This idea may seem startling
+at first, yet such would be the natural consequence of a gradual and
+continuous sinking of the ground in an estuary or bay, into which a great
+river discharged its turbid waters. By each foot of subsidence, the
+fundamental rock, such as the Portland Oolite, would be depressed one foot
+farther from the <span class="pagenum"><a id="page231"></a>[p.231]</span>surface; but the bay would not be deepened, if
+newly deposited mud and sand should raise the bottom one foot. On the
+contrary, such new strata of sand and mud might be frequently laid dry at
+low water, or overgrown for a season by a vegetation proper to marshes.</p>
+
+
+<h3><i>Purbeck Beds.</i></h3>
+
+<p>Immediately below the Hastings Sands we find a series of calcareous slates,
+marls, and limestones, called the Purbeck Beds, because well exposed to
+view in the sea-cliffs of the Peninsula of Purbeck, especially in
+Durlestone Bay, near Swanage. They may also be advantageously studied at
+Lulworth Cove and the neighbouring bays between Weymouth and Dorchester. At
+Meup's Bay in particular, Prof. E. Forbes has recently examined minutely
+the organic remains of the three members of the Purbeck group, displayed
+there in a vertical section 155 feet thick. To the information previously
+supplied in the works of Messrs. Webster, Fitton, De la Beche, Buckland,
+and Mantell, he has made most ample and important additions, so that it
+will be desirable to give them at some length, it appearing that the Upper,
+Middle, and Lower Purbecks are each marked by peculiar species of organic
+remains, these again being different, so far as a comparison has yet been
+instituted, from the fossils of the overlying Hastings Sands and Weald
+Clay. This result cannot fail to excite much wonder, and it leads us to
+suspect that the Wealden period, which many geologists have scarcely
+deigned to notice in their classification, may comprehend the history of a
+lapse of time as great as that of the Oolitic or Cretaceous eras
+respectively.<a name="FNanchor_T_3" id="FNanchor_T_3"></a><a href="#Footnote_T_3" class="fnanchor">[231-A]</a></p>
+
+<p><i>Upper Purbeck.</i>&mdash;The highest of the three divisions is purely freshwater,
+the strata, about 50 feet in thickness, containing shells of the genera
+<i>Paludina</i>, <i>Physa</i>, <i>Lymnea</i>, <i>Planorbis</i>, <i>Valvata</i>, <i>Cyclas</i>, and
+<i>Unio</i>, with cyprides, and fish.</p>
+
+<p><i>Middle Purbeck.</i>&mdash;To these succeed the Middle Purbeck, about 30 feet
+thick, the uppermost part of which consists of freshwater limestone, with
+cyprides, turtles, and fish of different species from those in the
+preceding strata. Below the limestone are brackish-water beds full of
+<i>Cyrena</i>, and traversed by bands abounding in <i>Corvul�</i> and <i>Melani�</i>.
+These are based on a purely marine deposit, with <i>Pecten</i>, <i>Modiola</i>,
+<i>Avicula</i>, and <i>Thracia</i>, all undescribed shells. Below this, again, come
+limestones and shales, partly of brackish and partly of freshwater origin,
+in which many fish, especially species of <i>Lepidotus</i> and <i>Microdon
+radiatus</i>, are found, and a reptile named <i>Macrorhyncus</i>. Among the
+mollusks, a remarkable ribbed <i>Melania</i>, of the section <i>Chilira</i>, occurs.</p>
+
+<p>Immediately below is the great and conspicuous stratum, 12 feet thick, long
+familiar to geologists under the local name of "Cinder-bed," formed of a
+vast accumulation of shells of <i>Ostrea distorta</i> <span class="pagenum"><a id="page232"></a>[p.232]</span>(<a href="#img229">fig. 240.</a>). In
+the uppermost part of this bed Mr. Forbes discovered the first echinoderm
+as yet known in the Purbeck series, a species of <i>Hemicidaris</i>, a genus
+characteristic of the Oolitic period. It was accompanied by a species of
+<i>Perna</i>. Below the Cinder-bed freshwater strata are again seen, filled in
+many places with species of <i>Cypris</i>, <i>Valvata</i>, <i>Paludina</i>, <i>Planorbis</i>,
+<i>Lymnea</i>, <i>Physa</i>, and <i>Cyclas</i>, all different from any we had previously
+seen above. Thick siliceous beds of chert, filled with these fossils, occur
+in a beautiful state of preservation, often converted into chalcedony.
+Among these Mr. Forbes met with gyrogonites (the spore vesicles of
+<i>Char�</i>), plants never before discovered in rocks older than the Eocene.
+Again, beneath these freshwater strata, a very thin band of greenish
+shales, with marine shells and impressions of leaves, like those of a large
+<i>Zostera</i>, succeeds, forming the base of the Middle Purbeck.</p>
+
+<a id="img229" name="img229"></a>
+<div class="floatleft smaller width100">
+<p>Fig. 240.</p>
+<img src="images/img229.jpg" width="100" height="079" alt="" title="">
+<p>Ostrea distorta. Cinder-bed.</p></div>
+
+<p><i>Lower Purbeck.</i>&mdash;Beneath the thin marine band last mentioned, purely
+freshwater marls occur, containing species of <i>Cypris</i>, <i>Valvata</i>, and
+<i>Lymnea</i>, different from those of the Middle Purbeck. This is the beginning
+of the Inferior division, which is about 80 feet thick. Below the marls are
+seen more than 30 feet of brackish-water beds, at Meup's Bay, abounding in
+a species of <i>Serpula</i>, allied to, if not identical with, <i>Serpula
+coacervites</i>, found in the Wealden of Hanover. There are also shells of the
+genus <i>Rissoa</i> (of the subgenus <i>Hydrobia</i>), and a little <i>Cardium</i> of the
+subgenus <i>Protocardium</i>, in the same beds, together with <i>Cypris</i>. Some of
+the cypris-bearing shales are strangely contorted and broken up, at the
+west end of the Isle of Purbeck. The great dirt-bed or vegetable soil
+containing the roots and stools of <i>Cycade�</i>, which I shall presently
+describe, underlies these marls, resting upon the lowest freshwater
+limestone, a rock about 8 feet thick, containing <i>Cyclades</i>, <i>Valvata</i>, and
+<i>Lymnea</i>, of the same species as those of the uppermost part of the Lower
+Purbeck. This rock rests upon the top beds of the Portland stone, which is
+purely marine, and between which and the Purbecks there is no passage.</p>
+
+<p>The most remarkable of all the varied successions of beds enumerated in the
+above list, is that called by the quarrymen "the dirt," or "black dirt,"
+which was evidently an ancient vegetable soil. It is from 12 to 18 inches
+thick, is of a dark brown or black colour, and contains a large proportion
+of earthy lignite. Through it are dispersed rounded fragments of stone,
+from 3 to 9 inches in diameter, in such numbers that it almost deserves the
+name of gravel. Many silicified trunks of coniferous trees, and the remains
+of plants allied to <i>Zamia</i> and <i>Cycas</i>, are buried in this dirt-bed (see
+figure of living <i>Zamia</i>, <a href="#img230">fig. 241.</a>).</p>
+
+<p>These plants must have become fossil on the spots where they grew. The
+stumps of the trees stand erect for a height of from 1 to 3 feet, and even
+in one instance to 6 feet, with their roots attached to the soil at about
+the same distances from one another as the trees in a <span class="pagenum"><a id="page233"></a>[p.233]</span>modern
+forest.<a name="FNanchor_T_4" id="FNanchor_T_4"></a><a href="#Footnote_T_4" class="fnanchor">[233-A]</a> The carbonaceous matter is most abundant immediately around
+the stumps, and round the remains of fossil <i>Cycade�</i>.<a name="FNanchor_T_5" id="FNanchor_T_5"></a><a href="#Footnote_T_5" class="fnanchor">[233-B]</a></p>
+
+<a id="img230" name="img230"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 241.</p>
+<img src="images/img230.jpg" width="350" height="199" alt="" title="">
+<p>Zamia spiralis; Southern Australia.<a name="FNanchor_T_6" id="FNanchor_T_6"></a><a href="#Footnote_T_6" class="fnanchor">[233-C]</a></p></div>
+
+<p>Besides the upright stumps above mentioned, the dirt-bed contains the stems
+of silicified trees laid prostrate. These are partly sunk into the black
+earth, and partly enveloped by a calcareous slate which covers the
+dirt-bed. The fragments of the prostrate trees are rarely more than 3 or 4
+feet in length; but by joining many of them together, trunks have been
+restored, having a length from the root to the branches of from 20 to 23
+feet, the stems being undivided for 17 or 20 feet, and then forked. The
+diameter of these near the roots is about 1 foot.<a name="FNanchor_T_7" id="FNanchor_T_7"></a><a href="#Footnote_T_7" class="fnanchor">[233-D]</a> Root-shaped
+cavities were observed by Professor Henslow to descend from the bottom of
+the dirt-bed into the subjacent freshwater stone, which, though now solid,
+must have been in a soft and penetrable state when the trees grew.<a name="FNanchor_T_8" id="FNanchor_T_8"></a><a href="#Footnote_T_8" class="fnanchor">[233-E]</a></p>
+
+<a id="img231" name="img231"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 242.</p>
+<img src="images/img231.jpg" width="450" height="123" alt="" title="">
+<p>Section in Isle of Portland, <span class="wosp05">Dorset. (Buckland</span> and
+De la Beche.)</p></div>
+
+<p>The thin layers of calcareous slate (<a href="#img231">fig. 242.</a>) were evidently deposited
+tranquilly, and would have been horizontal but for the protrusion of the
+stumps of the trees, around the top of each of which they form
+hemispherical concretions.</p>
+
+<p><span class="pagenum"><a id="page234"></a>[p.234]</span>The dirt-bed is by no means confined to the island of Portland,
+where it has been most carefully studied, but is seen in the same relative
+position in the cliffs east of Lulworth Cove, in Dorsetshire, where, as the
+strata have been disturbed, and are now inclined at an angle of 45�, the
+stumps of the trees are also inclined at the same angle in an opposite
+direction&mdash;a beautiful illustration of a change in the position of beds
+originally horizontal (see <a href="#img232">fig. 243.</a>). Traces of the dirt-bed have also
+been observed by Dr. Buckland, about two miles north of Thame, in
+Oxfordshire; and by Dr. Fitton, in the cliffs of the Boulonnois, on the
+French coast; but, as might be expected, this freshwater deposit is of
+limited extent when compared to most marine formations.</p>
+
+<a id="img232" name="img232"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 243.</p>
+<img src="images/img232.jpg" width="450" height="194" alt="" title="">
+<p>Section in cliff east of Lulworth <span class="wosp05">Cove. (Buckland</span>
+and De la Beche.)</p></div>
+
+<p>From the facts above described, we may infer, first, that the superior beds
+of the Oolite, called "the Portland," which are full of marine shells, were
+overspread with fluviatile mud, which became dry land, and covered by a
+forest, throughout a portion of the space now occupied by the south of
+England, the climate being such as to admit the growth of the <i>Zamia</i> and
+<i>Cycas</i>. 2dly. This land at length sank down and was submerged with its
+forests beneath a body of fresh water, from which sediment was thrown down
+enveloping fluviatile shells. 3dly. The regular and uniform preservation of
+this thin bed of black earth over a distance of many miles, shows that the
+change from dry land to the state of a freshwater lake or estuary, was not
+accompanied by any violent denudation, or rush of water, since the loose
+black earth, together with the trees which lay prostrate on its surface,
+must inevitably have been swept away had any such violent catastrophe then
+taken place.</p>
+
+<p>The dirt-bed has been described above in its most simple form, but in some
+sections the appearances are more complicated. The forest of the dirt-bed
+was not everywhere the first vegetation which grew in this region. Two
+other beds of carbonaceous clay, one of them containing <i>Cycade�</i>, in an
+upright position, have been found below it, and one above it<a name="FNanchor_T_9" id="FNanchor_T_9"></a><a href="#Footnote_T_9" class="fnanchor">[234-A]</a>, which
+implies other oscillations in the level of the same ground, and its
+alternate occupation by land and water more than once.</p>
+
+<p><span class="pagenum"><a id="page235"></a>[p.235]</span><i>Table showing the changes of medium in which the strata were
+formed, from the Lower Greensand to the Portland Stone inclusive, in the
+south-east of England.</i></p>
+
+
+<table  border="0" cellpadding="2" summary="TABLE SHOWING THE CHANGES OF MEDIUM IN WHICH THE STRATA FROM LOWER GREENSAND TO PORTLAND
+WERE FORMED IN THE SOUTH-EAST OF ENGLAND.">
+<colgroup>
+    <col width="3%">
+    <col width="25%">
+    <col width="10%">
+    <col width="3%">
+    <col width="56%">
+</colgroup>
+
+<tr>
+  <td class="td-right tdtx-top">1.</td>
+  <td class="td-left tdtx-top tdp-left1">Marine</td>
+  <td colspan="2" rowspan="2">&nbsp;</td>
+  <td class="td-left tdtx-mid tdp-left">Lower greensand.</td>
+</tr>
+
+<tr>
+  <td style="padding-top: 1em;" class="td-right tdtx-top">2.</td>
+  <td style="padding-top: 1em;" class="td-left tdtx-top tdp-left1">Freshwater</td>
+  <td style="padding-top: 1em;" class="td-left tdtx-mid tdp-left">Weald clay.</td>
+</tr>
+
+<tr>
+  <td class="td-right tdtx-top" style="padding-top: 1.5em;">3.</td>
+  <td class="td-left tdtx-top tdp-left1" style="padding-top: 1.5em;">Freshwater<br>Brackish<br>Freshwater</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 30pt; font-weight: 800; padding-left: 0.2em; padding-top: 0.3em;" class="tdtx-top">}</td>
+  <td rowspan="5">&nbsp;</td>
+  <td style="padding-top: 1em;" class="td-left tdtx-mid tdp-left">Hastings sand.</td>
+</tr>
+
+<tr>
+  <td  style="padding-top: 1em;" class="td-right tdtx-top">4.</td>
+  <td  style="padding-top: 1em;" class="td-left tdtx-top tdp-left1">Freshwater</td>
+  <td>&nbsp;</td>
+  <td  style="padding-top: 1em;" class="td-left tdtx-mid tdp-left">Upper Purbeck.</td>
+</tr>
+
+<tr>
+  <td class="td-right tdtx-top" style="padding-top: 2em;">5.</td>
+  <td class="td-left tdtx-top tdp-left1" style="padding-top: 2em;">Freshwater<br>Brackis<br>Marine<br>Brackish<br>Marine<br>
+  Freshwater<br>Marine</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 80pt; font-weight: 100;" class="tdtx-top">}</td>
+  <td class="td-left tdtx-mid tdp-left" style="padding-top: 1.5em;">Middle Purbeck.</td>
+</tr>
+
+<tr>
+  <td class="td-right tdtx-top" style="padding-top: 1.7em;">6.</td>
+  <td class="td-left tdtx-top tdp-left1" style="padding-top: 1.7em;">Freshwater<br>Brackish<br>Land<br>Freshwater<br>
+  Land (dirt-bed)<br>Freshwater<br>Land<br>Freshwater<br>
+  Land<br>Freshwater</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 105pt; font-weight: 100; line-height: 45%;" class="tdtx-mid">}</td>
+  <td class="td-left tdtx-mid tdp-left" style="padding-top: 1.6em;">Lower Purbeck.</td>
+</tr>
+
+<tr>
+  <td  style="padding-top: 1em;" class="td-right tdtx-top">7.</td>
+  <td  style="padding-top: 1em;" class="td-left tdtx-top tdp-left1">Marine</td>
+  <td>&nbsp;</td>
+  <td  style="padding-top: 1em;" class="td-left tdtx-top tdp-left">Portland stone.</td>
+</tr>
+</table>
+
+
+<p>The annexed tabular view will enable the reader to take in at a glance the
+successive changes from sea to river, and from river to sea, or from these
+again to a state of land, which have occurred in this part of England
+between the Cretaceous and Oolitic periods. That there have been at least
+four changes in the species of testacea during the deposition of the
+Wealden, seems to follow from the observations recently made by Professor
+E. Forbes, so that, should we hereafter find the signs of many more
+alternate occupations of the same area by different elements, it is no more
+than we might expect. Even during a small part of a zoological period, not
+sufficient to allow time for many species to die out, we find that the same
+area has been laid dry, and then submerged, and then again laid dry, as in
+the deltas of the Po and Ganges, the history of which has been brought to
+light by Artesian borings.<a name="FNanchor_T_10" id="FNanchor_T_10"></a><a href="#Footnote_T_10" class="fnanchor">[235-A]</a> We also know that similar revolutions
+have occurred within the present century (1819) in the delta of the Indus
+in Cutch<a name="FNanchor_T_11" id="FNanchor_T_11"></a><a href="#Footnote_T_11" class="fnanchor">[235-B]</a>, where land has been laid permanently under the waters both
+of the river and sea, without its soil or shrubs having been swept away.
+Even, independently of any vertical movements of the ground, we see in the
+principal deltas, such as that of the Mississippi, that the sea extends its
+salt waters annually for many months over considerable spaces, which, at
+other seasons, are occupied by the river during its inundations.</p>
+
+<p>It will be observed that the division of the Purbecks into upper, middle,
+and lower, has been made by Professor E. Forbes, strictly on the principle
+of the entire distinctness of the species of organic remains which they
+include. The lines of demarcation are not lines of disturbance, nor
+indicated by any striking physical characters or mineral changes. The
+features which attract the eye in the Purbecks, such as the dirt-beds, the
+dislocated strata at Lulworth, and the Cinder-bed, do not indicate any
+breaks in the distribution of organized beings. "The causes which led to a
+complete change of life three times during the deposition of the freshwater
+and brackish strata must," says this naturalist, "be sought for, not simply
+in either a <span class="pagenum"><a id="page236"></a>[p.236]</span>rapid or a sudden change of their area into land or
+sea, but in the great lapse of time which intervened between the epochs of
+deposition at certain periods during their formation."</p>
+
+<p>Each dirt-bed may, no doubt, be the memorial of many thousand years or
+centuries, because we find that 2 or 3 feet of vegetable soil is the only
+monument which many a tropical forest has left of its existence ever since
+the ground on which it now stands was first covered with its shade. Yet,
+even if we imagined the fossil soils of the Lower Purbeck to represent as
+many ages, we need not expect on that account to find them constituting the
+lines of separation between successive strata characterized by different
+zoological types. The preservation of a layer of vegetable soil, when in
+the act of being submerged, must be regarded as a rare exception to a
+general rule. It is of so perishable a nature, that it must usually be
+carried away by the denuding waves or currents of the sea or by a river;
+and many dirt-beds were probably formed in succession, and annihilated in
+the Wealden, besides those few which now remain.</p>
+
+<a id="img233" name="img233"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 244.</p>
+<img src="images/img233.jpg" width="100" height="124" alt="" title="">
+<p style="text-align: justify;">Cone from the Isle of Purbeck, resembling the
+<i>Dammara</i> of the <span class="wosp05">Moluccas. (Fitton.)</span></p></div>
+
+<p>The plants of the Wealden, so far as our knowledge extends at present,
+consist chiefly of Ferns, Conifer� (see <a href="#img233">fig. 244.</a>), and Cycade�, without
+any exogens; the whole more allied to the Oolitic than to the Cretaceous
+vegetation, although some of the species seem to be common to the chalk.
+But the vertebrate and invertebrate animals indicate, in like manner, a
+relationship to both these periods, though a nearer affinity to the
+Oolitic. Mr. Brodie has found the remains of beetles and several insects of
+the homopterous and trichopterous orders, some of which now live on plants,
+like those of the Wealden, while others hover over the surface of our
+present rivers. But no bones of mammalia have been met with among those of
+land-reptiles. Yet, as the reader will learn, in Chapter XX., that the
+relics of marsupial quadrupeds have been detected in still older beds, and,
+as it was so long before a single portion of the jaw of an iguanodon was
+met with in the Tilgate quarries (see <a href="#page228">p. 228.</a>), we need by no means despair
+of discovering hereafter some evidence of the existence of warm-blooded
+quadrupeds at this era. It is, at least, too soon to infer, on mere
+negative evidence, that the mammalia were foreign to this fauna.</p>
+
+<p>In regard to the geographical extent of the Wealden, it cannot be
+accurately laid down; because so much of it is concealed beneath the newer
+marine formations. It has been traced about 200 English miles from west to
+east, from Lulworth Cove to near Boulogne, in France; and about 220 miles
+from north-west to south-east, from Whitchurch, in Buckinghamshire, to
+Beauvais, in France. If the formation be continuous throughout this space,
+which is very doubtful, it does not follow that the whole was
+contemporaneous; because, in all likelihood, the physical geography of the
+region underwent frequent change throughout the whole period, and the
+estuary may <span class="pagenum"><a id="page237"></a>[p.237]</span>have altered its form, and even shifted its place.
+Dr. Dunker, of Cassel, and H. Von Meyer, in an excellent monograph on the
+Wealdens of Hanover and Westphalia, have shown that they correspond so
+closely, not only in their fossils, but also in their mineral characters,
+with the English series, that we can scarcely hesitate to refer the whole
+to one great delta. Even then, the magnitude of the deposit may not exceed
+that of many modern rivers. Thus, the delta of the Quorra or Niger, in
+Africa, stretches into the interior for more than 170 miles, and occupies,
+it is supposed, a space of more than 300 miles along the coast, thus
+forming a surface of more than 25,000 square miles, or equal to about one
+half of England.<a name="FNanchor_T_12" id="FNanchor_T_12"></a><a href="#Footnote_T_12" class="fnanchor">[237-A]</a> Besides, we know not, in such cases, how far the
+fluviatile sediment and organic remains of the river and the land may be
+carried out from the coast, and spread over the bed of the sea. I have
+shown, when treating of the Mississippi, that a more ancient delta,
+including species of shells, such as now inhabit Louisiana, has been
+upraised, and made to occupy a wide geographical area, while a newer delta
+is forming<a name="FNanchor_T_13" id="FNanchor_T_13"></a><a href="#Footnote_T_13" class="fnanchor">[237-B]</a>; and the possibility of such movements, and their
+effects, must not be lost sight of when we speculate on the origin of the
+Wealden.</p>
+
+<p>If it be asked where the continent was placed from the ruins of which the
+Wealden strata were derived, and by the drainage of which a great river was
+fed, we are half tempted to speculate on the former existence of the
+Atlantis of Plato. The story of the submergence of an ancient continent,
+however fabulous in history, must have been true again and again as a
+geological event.</p>
+
+<p>The real difficulty consists in the persistence of a large hydrographical
+basin, from whence a great body of fresh water was poured into the sea,
+precisely at a period when the neighbouring area of the Wealden was
+gradually going downwards 1000 feet or more perpendicularly. If the
+adjoining land participated in the movement, how could it escape being
+submerged, or how could it retain its size and altitude so as to continue
+to be the source of such an inexhaustible supply of fresh water and
+sediment? In answer to this question, we are fairly entitled to suggest
+that the neighbouring land may have been stationary, or may even have
+undergone a contemporaneous slow upheaval. There may have been an ascending
+movement in one region, and a descending one in a contiguous parallel zone
+of country; just as the northern part of Scandinavia is now rising, while
+the middle portion (that south of Stockholm) is unmoved, and the southern
+extremity in Scania is sinking, or at least has sunk within the historical
+period.<a name="FNanchor_T_14" id="FNanchor_T_14"></a><a href="#Footnote_T_14" class="fnanchor">[237-C]</a> We must, nevertheless, conclude, if we adopt the above
+hypothesis, that the depression of the land became general throughout a
+large part of Europe at the close of the Wealden period, a subsidence which
+brought in the cretaceous ocean.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page238"></a>[p.238]</span>CHAPTER XIX.</h2>
+
+<h4>DENUDATION OF THE CHALK AND WEALDEN.</h4>
+
+<div class="blq1">
+<p class="indentm2">Physical geography of certain districts composed of Cretaceous and Wealden
+strata &mdash; Lines of inland chalk-cliffs on the Seine in
+Normandy &mdash; Outstanding pillars and needles of chalk &mdash; Denudation of
+the chalk and Wealden in Surrey, Kent, and Sussex &mdash; Chalk once
+continuous from the North to the South Downs &mdash; Anticlinal axis and
+parallel ridges &mdash; Longitudinal and transverse valleys &mdash; Chalk
+escarpments &mdash; Rise and denudation of the strata gradual &mdash; Ridges
+formed by harder, valleys by softer beds &mdash; Why no alluvium, or wreck of
+the chalk, in the central district of the Weald &mdash; At what periods the
+Weald valley was denuded &mdash; Land has most prevailed where denudation has
+been greatest &mdash; Elephant bed, Brighton.</p></div>
+
+
+<p><span class="smcap">All</span> the fossiliferous formations may be studied by the geologist in two
+distinct points of view: first, in reference to their position in the
+series, their mineral character and fossils; and, secondly, in regard to
+their physical geography, or the manner in which they now enter, as mineral
+masses, into the external structure of the earth; forming the bed of lakes
+and seas, or the surface and foundation of hills and valleys, plains and
+table-lands. Some account has already been given on the first head of the
+Tertiary, the Cretaceous, and Wealden strata; and we may now proceed to
+consider certain features in the physical geography of these groups as they
+occur in parts of England and France.</p>
+
+<p>The hills composed of white chalk in the S.E. of England have a smooth
+rounded outline, and being usually in the state of sheep pastures, are free
+from trees or hedgerows; so that we have an opportunity of observing how
+the valleys by which they are drained ramify in all directions, and become
+wider and deeper as they descend. Although these valleys are now for the
+most part dry, except during heavy rains and the melting of snow, they may
+have been due to aqueous denudation, as explained in the sixth chapter;
+having been excavated when the chalk emerged gradually from the sea. This
+opinion is confirmed by the occasional occurrence of long lines of inland
+cliffs, in which the strata are cut off abruptly in steep and often
+vertical precipices. The true nature of such escarpments is nowhere more
+obvious than in parts of Normandy, where the river Seine and its
+tributaries flow through deep winding valleys, hollowed out of chalk
+horizontally stratified. Thus, for example, if we follow the Seine for a
+distance of about 30 miles from Andelys to Elb&oelig;uf, we find the valley
+flanked on both sides by a deep slope of chalk, with numerous beds of
+flint, the formation being laid open for a thickness of about 250 and 300
+feet. Above the chalk is an overlying mass of sand, gravel, and clay, from
+30 to 100 feet thick. The two opposite slopes of the hills <i>a</i> and <i>b</i>,
+where the chalk appears at <span class="pagenum"><a id="page239"></a>[p.239]</span>the surface, are from 2 to 4 miles
+apart, and they are often perfectly smooth and even, like the steepest of
+our downs in England; but at many points they are broken by one, two, or
+more ranges of vertical and even overhanging cliffs of bare white chalk
+with flints. At some points detached needles and pinnacles stand in the
+line of the cliffs, or in front of them, as at <i>c</i>, <a href="#img234">fig. 245.</a> On the right
+bank of the Seine, at Andelys, one range, about 2 miles long, is seen
+varying from 50 to 100 feet in perpendicular height, and having its
+continuity broken by a number of dry valleys or coombs, in one of which
+occurs a detached rock or needle, called the T�te d'Homme (see <a href="#img235">figs. 246</a>,
+<a href="#img236">247.</a>). The top of this rock presents a precipitous face towards every point
+of the compass; its vertical height being more than 20 feet on the side of
+the downs, and 40 towards the Seine, the average diameter of the pillar
+being 36 feet. Its composition is the same as that of the larger cliffs in
+its neighbourhood, namely, white chalk, having occasionally a crystalline
+texture like marble, with layers of flint in nodules and tabular masses.
+The flinty beds often project in relief 4 or 5 feet beyond the white chalk,
+which is generally in a state of slow decomposition, either exfoliating or
+being covered with white powder, like the chalk cliffs on the English
+coast; and, as in them, this superficial powder contains in some places
+common salt.</p>
+
+<a id="img234" name="img234"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 245.</p>
+<img src="images/img234.jpg" width="450" height="127" alt="" title="">
+<p>Section across Valley of Seine.</p></div>
+
+<a id="img235" name="img235"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 246.</p>
+<img src="images/img235.jpg" width="450" height="314" alt="" title="">
+<p>View of the T�te d'Homme, Andelys, seen from above.</p></div>
+
+<p>Other cliffs are situated on the right bank of the Seine, opposite
+Tournedos, between Andelys and Pont de l'Arche, where the precipices are
+from 50 to 80 feet high: several of their summits terminate <span class="pagenum"><a id="page240"></a>[p.240]</span>in
+pinnacles; and one of them, in particular, is so completely detached as to
+present a perpendicular face 50 feet high towards the sloping down. On
+these cliffs several ledges are seen, which mark so many levels at which
+the waves of the sea may be supposed to have encroached for a long period.
+At a still greater height, immediately above the top of this range, are
+three much smaller cliffs, each about 4 feet high, with as many intervening
+terraces, which are continued so as to sweep in a semicircular form round
+an adjoining coomb, like those in Sicily before described (<a href="#page76">p. 76.</a>).</p>
+
+<a id="img236" name="img236"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 247.</p>
+<img src="images/img236.jpg" width="450" height="299" alt="" title="">
+<p>Side view of the T�te <span class="wosp05">d'Homme. White</span> chalk with
+flints.</p></div>
+
+<a id="img237" name="img237"></a>
+<div class="figcenter smaller width300">
+<p class="martop2">Fig. 248.</p>
+<img src="images/img237.jpg" width="300" height="247" alt="" title="">
+<p>Chalk pinnacle at Senneville.</p></div>
+
+<a id="img238" name="img238"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 249.</p>
+<img src="images/img238.jpg" width="350" height="290" alt="" title="">
+<p>Roches d'Orival, Elb&oelig;uf.</p></div>
+
+<p>If we then descend the river from Vatteville to a place called Senneville,
+we meet with a singular needle about 50 feet high, perfectly isolated on
+the escarpment of chalk on the right bank of the Seine (see <a href="#img237">fig. 248.</a>).
+Another conspicuous range of inland cliffs is situated about 12 miles below
+on the left bank of the Seine, beginning at Elb&oelig;uf, and comprehending
+the Roches d'Orival (see <a href="#img238">fig. 249.</a>). Like those before described, it has an
+irregular surface, often overhanging, <span class="pagenum"><a id="page241"></a>[p.241]</span>and with beds of flint
+projecting several feet. Like them, also, it exhibits a white powdery
+surface, and consists entirely of horizontal chalk with flints. It is 40
+miles inland, its height, in some parts, exceeding 200 feet, and its base
+only a few feet above the level of the Seine. It is broken, in one place,
+by a pyramidal mass or needle, 200 feet high, called the Roche de Pignon,
+which stands out about 25 feet in front of the upper portion of the main
+cliffs, with which it is united by a narrow ridge about 40 feet lower than
+its summit (see <a href="#img239">fig. 250.</a>). Like the detached rocks before mentioned at
+Senneville, Vatteville, and Andelys, it may be compared to those needles of
+chalk which occur on the coast of Normandy, as well as in the Isle of Wight
+and in Purbeck<a name="FNanchor_U_1" id="FNanchor_U_1"></a><a href="#Footnote_U_1" class="fnanchor">[241-A]</a> (see <a href="#img240">fig. 251.</a>).</p>
+
+<a id="img239" name="img239"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 250.</p>
+<img src="images/img239.jpg" width="450" height="292" alt="" title="">
+<p>View of the Roche de Pignon, seen from the south.</p></div>
+
+<a id="img240" name="img240"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 251.</p>
+<img src="images/img240.jpg" width="400" height="244" alt="" title="">
+<p>Needle and Arch of Etretat, in the chalk cliffs of
+Normandy. Height of Arch 100 <span class="wosp05">feet. (Passy.)</span><a name="FNanchor_U_2" id="FNanchor_U_2"></a><a href="#Footnote_U_2" class="fnanchor">[241-B]</a></p></div>
+
+<p>The foregoing description and drawings will show, that the evidence of
+certain escarpments of the chalk having been originally sea-cliffs, is far
+more full and satisfactory in France than in England. If it be asked why,
+in the interior of our own country, we meet with no ranges of precipices
+equally vertical and overhanging, and no isolated pillars or needles, we
+may reply that the greater hardness of the chalk in Normandy may, no doubt,
+be the chief cause of this difference. <span class="pagenum"><a id="page242"></a>[p.242]</span>But the frequent absence
+of all signs of littoral denudation in the valley of the Seine itself is a
+negative fact of a far more striking and perplexing character. The cliffs,
+after being almost continuous for miles, are then wholly wanting for much
+greater distances, being replaced by a green sloping down, although the
+beds remain of the same composition, and are equally horizontal; and
+although we may feel assured that the manner of the upheaval of the land,
+whether intermittent or not, must have been the same at those intermediate
+points where no cliffs exist, as at others where they are so fully
+developed. But, in order to explain such apparent anomalies, the reader
+must refer again to the theory of denudation, as expounded in the 6th
+chapter; where it was shown, first, that the undermining force of the waves
+and marine currents varies greatly at different parts of every coast;
+secondly, that precipitous rocks have often decomposed and crumbled down;
+and thirdly, that many terraces and small cliffs may now lie concealed
+beneath a talus of detrital matter.</p>
+
+<p><i>Denudation of the Weald Valley.</i>&mdash;No district is better fitted to
+illustrate the manner in which a great series of strata may have been
+upheaved and gradually denuded than the country intervening between the
+North and South Downs. This region, of which a ground plan is given in the
+accompanying map (<a href="#img241">fig. 252.</a>), comprises within it the whole of Sussex, and
+parts of the counties of Kent, Surrey, and Hampshire. The space in which
+the formations older than the White Chalk, or those from the Gault to the
+Hastings sand inclusive, crop out, is bounded everywhere by a great
+escarpment of chalk, which is continued on the opposite side of the channel
+in the Bas Boulonnais in France, where it forms the semicircular boundary
+of a tract in which older strata also appear at the surface. The whole of
+this district may therefore be considered geologically as one and the same.</p>
+
+<a id="img241" name="img241"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 252.</p>
+<img src="images/img241.jpg" width="450" height="318" alt="" title="">
+<p>Geological Map of the south-east of England and part of France,
+exhibiting the denudation of the Weald.</p></div>
+
+<span class="pagenum"><a id="page243"></a>[p.243]</span>
+<a id="img242" name="img242"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 253.</p>
+<img src="images/img242.jpg" width="500" height="038" alt="" title="">
+<p>Section from the London to the Hampshire basin across the valley
+of the Weald.</p>
+<ul class="leftal smaller martopm05 add3em min1em">
+<li>1. Tertiary strata.</li>
+<li>2. Chalk and firestone.</li>
+<li>3. Gault.</li>
+<li>4. Lower greensand.</li>
+<li>5. Weald clay.</li>
+<li>6. Hastings sands.</li>
+</ul></div>
+
+<a id="img243" name="img243"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 254.</p>
+<img src="images/img243.jpg" width="500" height="059" alt="" title="">
+<p class="ftsize95">Highest point of North Downs, 880 feet.<a name="FNanchor_U_3" id="FNanchor_U_3"></a><a href="#Footnote_U_3" class="fnanchor">[243-A]</a></p>
+<p class="martopm05">Section of the country from the confines of the basin of London to that of
+Hants, with the principal heights above the level of the sea on a true
+scale.<a name="FNanchor_U_4" id="FNanchor_U_4"></a><a href="#Footnote_U_4" class="fnanchor">[243-B]</a></p></div>
+
+<p>The space here inclosed within the escarpment of the chalk affords an
+example of what has been sometimes called a "valley of elevation" (more
+properly "of denudation"); where the strata, partially removed by aqueous
+excavation, dip away on all sides from a central <span class="pagenum"><a id="page244"></a>[p.244]</span>axis. Thus, it
+is supposed that the area now occupied by the Hastings sand (No. 6.) was
+once covered by the Weald clay (No. 5.), and this again by the Greensand
+(No. 4.), and this by the Gault (No. 3.); and, lastly, that the Chalk (No.
+2.) extended originally over the whole space between the North and the
+South Downs. This theory will be better understood by consulting the
+annexed diagram (<a href="#img242">fig. 253.</a>), where the dark lines represent what now
+remains, and the fainter ones those portions of rock which are believed to
+have been carried away.</p>
+
+<p>At each end of the diagram the tertiary strata (No. 1.) are exhibited
+reposing on the chalk. In the middle are seen the Hastings sands (No. 6.)
+forming an anticlinal axis, on each side of which the other formations are
+arranged with an opposite dip. It has been necessary, however, in order to
+give a clear view of the different formations, to exaggerate the
+proportional height of each in comparison to its horizontal extent; and a
+true scale is therefore subjoined in another diagram (<a href="#img243">fig. 254.</a>), in order
+to correct the erroneous impression which might otherwise be made on the
+reader's mind. In this section the distance between the North and South
+Downs is represented to exceed forty miles; for the Valley of the Weald is
+here intersected in its longest diameter, in the direction of a line
+between Lewes and Maidstone.</p>
+
+<p>Through the central portion, then, of the district supposed to be denuded
+runs a great anticlinal line, having a direction nearly east and west, on
+both sides of which the beds 5, 4, 3, and 2, crop out in succession. But,
+although, for the sake of rendering the physical structure of this region
+more intelligible, the central line of elevation has alone been introduced,
+as in the diagrams of Smith, Mantell, Conybeare, and others, geologists
+have always been well aware that numerous minor lines of dislocation and
+flexure run parallel to the great central axis.</p>
+
+<p>In the central area of the Hastings sand the strata have undergone the
+greatest displacement; one fault being known, where the vertical shift of a
+bed of calcareous grit is no less than 60 fathoms.<a name="FNanchor_U_5" id="FNanchor_U_5"></a><a href="#Footnote_U_5" class="fnanchor">[244-A]</a> Much of the
+picturesque scenery of this district arises from the depth of the narrow
+valleys and ridges to which the sharp bends and fractures of the strata
+have given rise; but it is also in part to be attributed to the excavating
+power exerted by water, especially on the interstratified argillaceous
+beds.</p>
+
+<p>Besides the series of longitudinal valleys and ridges in the Weald, there
+are valleys which run in a transverse direction, passing through the chalk
+to the basin of the Thames on the one side, and to the English Channel on
+the other. In this manner the chain of the North Downs is broken by the
+rivers Wey, Mole, Darent, Medway, and Stour; the South Downs by the Arun,
+Adur, Ouse, and Cuckmere.<a name="FNanchor_U_6" id="FNanchor_U_6"></a><a href="#Footnote_U_6" class="fnanchor">[244-B]</a> If these transverse hollows could be
+filled up, all the rivers, observes Mr. Conybeare, would be forced to take
+an easterly course, and to <span class="pagenum"><a id="page245"></a>[p.245]</span>empty themselves into the sea by
+Romney Marsh and Pevensey Levels.<a name="FNanchor_U_7" id="FNanchor_U_7"></a><a href="#Footnote_U_7" class="fnanchor">[245-A]</a></p>
+
+<p>Mr. Martin has suggested that the great cross fractures of the chalk, which
+have become river channels, have a remarkable correspondence on each side
+of the valley of the Weald; in several instances the gorges in the North
+and South Downs appearing to be directly opposed to each other. Thus, for
+example, the defiles of the Wey in the North Downs, and of the Arun in the
+South, seemed to coincide in direction; and, in like manner, the Ouse
+corresponds to the Darent, and the Cuckmere to the Medway.<a name="FNanchor_U_8" id="FNanchor_U_8"></a><a href="#Footnote_U_8" class="fnanchor">[245-B]</a></p>
+
+<a id="img244" name="img244"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 255.</p>
+<img src="images/img244.jpg" width="500" height="144" alt="" title="">
+<p>View of the chalk escarpment of the South <span class="wosp05">Downs.
+Taken</span> from the Devil's Dike, looking towards the west and south-west.</p>
+<ul class="martopm05 smaller leftal add2em min1em">
+<li><i>a.</i> The town of Steyning is hidden by this point.</li>
+<li><i>b.</i> Edburton church.</li>
+<li><i>c.</i> Road.</li>
+<li><i>d.</i> River Adur.</li>
+</ul></div>
+
+<p>Although these coincidences may, perhaps, be accidental, it is by no means
+improbable, as hinted by the author above mentioned, that great amount of
+elevation towards the centre of the Weald district gave rise to transverse
+fissures. And as the longitudinal valleys were connected with that linear
+movement which caused the anticlinal lines running east and west, so the
+cross fissures might have been occasioned by the intensity of the upheaving
+force towards the centre of the line.</p>
+
+<p>But before treating of the manner in which the upheaving movement may have
+acted, I shall endeavour to make the reader more intimately acquainted with
+the leading geographical features of the district, so far as they are of
+geological interest.</p>
+
+<p>In whatever direction we travel from the tertiary strata of the basins of
+London and Hampshire towards the valley of the Weald, we first ascend a
+slope of white chalk, with flints, and then find ourselves on the summit of
+a declivity <span class="pagenum"><a id="page246"></a>[p.246]</span>consisting, for the most part, of different members
+of the chalk formation; below which the upper greensand, and sometimes,
+also, the gault, crop out. This steep declivity is the great escarpment of
+the chalk before mentioned, which overhangs a valley excavated chiefly out
+of the argillaceous or marly bed, termed Gault (No. 3.). The escarpment is
+continuous along the southern termination of the North Downs, and may be
+traced from the sea, at Folkestone, westward to Guildford and the
+neighbourhood of Petersfield, and from thence to the termination of the
+South Downs at Beachy Head. In this precipice or steep slope the strata are
+cut off abruptly, and it is evident that they must originally have extended
+farther. In the woodcut (<a href="#img244">fig. 255.</a> <a href="#page245">p. 245.</a>), part of the escarpment of the
+South Downs is faithfully represented, where the denudation at the base of
+the declivity has been somewhat more extensive than usual, in consequence
+of the upper and lower greensand being formed of very incoherent materials,
+the upper, indeed, being extremely thin and almost wanting.</p>
+
+<a id="img245" name="img245"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 256.</p>
+<img src="images/img245.jpg" width="500" height="172" alt="" title="">
+<p>Chalk escarpment, as seen from the hill above Steyning, Sussex.
+The castle and village of Bramber in the foreground.</p></div>
+
+<p>The geologist cannot fail to recognize in this view the exact likeness of a
+sea cliff; and if he turns and looks in an opposite direction, or eastward,
+towards Beachy Head (see <a href="#img245">fig. 256.</a>), he will see the same line of heights
+prolonged. Even those who are not accustomed to speculate on the former
+changes which the surface has undergone may fancy the broad and level plain
+to resemble the flat sands which were laid dry by the receding tide, and
+the different projecting masses of chalk to be the headlands of a coast
+which separated the different bays from each other.</p>
+
+<p>In regard to the transverse valleys before mentioned, as intersecting the
+chalk hills, some idea of them may be derived from the subjoined sketch
+(<a href="#img246">fig. 257.</a>), of the gorge of the river Adur, taken from the summit of the
+chalk downs, at a point in the bridle-way leading from the towns of Bramber
+and Steyning to Shoreham. If the reader will refer again to the view given
+in a former woodcut (<a href="#img244">fig. 255.</a> <a href="#page245">p. 245.</a>), he will there see the exact point
+where the gorge of which I am now speaking interrupts the chalk escarpment.
+A projecting hill, at the point <i>a</i>, hides the town of Steyning, near which
+the valley commences where the Adur passes directly to the sea at Old
+Shoreham. The river flows through a nearly level plain, <span class="pagenum"><a id="page247"></a>[p.247]</span>as do
+most of the others which intersect the hills of Surrey, Kent, and Sussex;
+and it is evident that these openings, so far at least as they are due to
+aqueous erosion, have not been produced by the rivers, many of which, like
+the Ouse near Lewes, have filled up arms of the sea, instead of deepening
+the hollows which they traverse.</p>
+
+<a id="img246" name="img246"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 257.</p>
+<img src="images/img246.jpg" width="500" height="114" alt="" title="">
+<p>Transverse Valley of the Adur in the South Downs.</p>
+<ul class="smaller martopm05 leftal add2em min1em">
+<li><i>a.</i> Town of Steyning.</li>
+<li><i>b.</i> River Adur.</li>
+<li><i>c.</i> Old Shoreham.</li>
+</ul></div>
+
+<p>Now, in order to account for the manner in which the five groups of strata,
+2, 3, 4, 5, 6, represented in the map, <a href="#img241">fig. 252.</a> and in the section <a href="#img242">fig.
+253.</a>, may have been brought into their present position, the following
+hypothesis has been very generally adopted:&mdash;Suppose the five formations to
+lie in horizontal stratification at the bottom of the sea; then let a
+movement from below press them upwards into the form of a flattened dome,
+and let the crown of this dome be afterwards cut off, so that the incision
+should penetrate to the lowest of the five groups. The different beds would
+then be exposed on the surface, in the manner exhibited in the map, f<a href="#img241">ig.
+252.</a><a name="FNanchor_U_9" id="FNanchor_U_9"></a><a href="#Footnote_U_9" class="fnanchor">[247-A]</a></p>
+
+<p>The quantity of denudation or removal by water of stratified masses assumed
+to have once reached continuously from the North to the South Downs is so
+enormous, that the reader may at first be startled by the boldness of the
+hypothesis. But the difficulty vanishes when once sufficient time is
+allowed for the gradual and successive rise of the strata, during which the
+waves and currents of the ocean might slowly accomplish an operation, which
+no sudden diluvial rush of waters could possibly have effected.</p>
+
+<p>Among other proofs of the action of water, it may be stated that the great
+longitudinal valleys follow the outcrop of the softer and <span class="pagenum"><a id="page248"></a>[p.248]</span>more
+incoherent beds, while ridges or lines of cliff usually occur at those
+points where the strata are composed of harder stone. Thus, for example,
+the chalk with flints, together with the subjacent upper greensand, which
+is often used for building, under the provincial name of "firestone," has
+been cut into a steep cliff on that side on which the sea encroached. This
+escarpment bounds a deep valley, excavated chiefly out of the soft
+argillaceous or marly bed, termed gault (No. 3.). In some places the upper
+greensand is in a loose and incoherent state, and there it has been as much
+denuded as the gault; as, for example, near Beachy Head; but farther to the
+westward it is of great thickness, and contains hard beds of blue chert and
+calcareous sandstone or firestone. Here, accordingly, we find that it
+produces a corresponding influence on the scenery of the country; for it
+runs out like a step beyond the foot of the chalk-hills, and constitutes a
+lower terrace, varying in breadth from a quarter of a mile to three miles,
+and following the sinuosities of the chalk escarpment.<a name="FNanchor_U_10" id="FNanchor_U_10"></a><a href="#Footnote_U_10" class="fnanchor">[248-A]</a></p>
+
+<a id="img247" name="img247"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 258.</p>
+<img src="images/img247.jpg" width="350" height="096" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> Chalk with flints.</li>
+<li><i>b.</i> Chalk without flints.</li>
+<li><i>c.</i> Upper greensand, or firestone.</li>
+<li><i>d.</i> Gault.</li>
+</ul></div>
+
+<p>It is impossible to desire a more satisfactory proof that the escarpment is
+due to the excavating power of water during the rise of the strata; for I
+have shown, in my account of the coast of Sicily, in what manner the
+encroachments of the sea tend to efface that succession of terraces which
+must otherwise result from the intermittent upheaval of a coast preyed upon
+by the waves.<a name="FNanchor_U_11" id="FNanchor_U_11"></a><a href="#Footnote_U_11" class="fnanchor">[248-B]</a> During the interval between two elevatory movements,
+the lower terrace will usually be destroyed, wherever it is composed of
+incoherent materials; whereas the sea will not have time entirely to sweep
+away another part of the same terrace, or lower platform, which happens to
+be composed of rocks of a harder texture, and capable of offering a firmer
+resistance to the erosive action of water. As the yielding clay termed
+gault would be readily washed away, we find its outcrop marked everywhere
+by a valley which skirts the base of the chalk hills, and which is usually
+bounded on the opposite side by the lower greensand; but as the upper beds
+of this last formation are most commonly loose and incoherent, they also
+have usually disappeared and increased the breadth of the valley. But in
+those districts where chert, limestone, and other solid materials enter
+largely into the composition of this formation (No. 4.), they give rise to
+a range of hills parallel to the chalk, which sometimes rival the
+escarpment of the chalk itself in height, or even surpass it, as in Leith
+Hill, near Dorking. This ridge often presents a steep escarpment towards
+the soft argillaceous deposit called the <span class="pagenum"><a id="page249"></a>[p.249]</span>Weald clay (No. 5.; see
+the strong lines in <a href="#img242">fig. 253.</a> <a href="#page243">p. 243.</a>), which usually forms a broad valley,
+separating the lower greensand from the Hastings sands or Forest ridge; but
+where subordinate beds of sandstone of a firmer texture occur, the
+uniformity of the plain of No. 5. is broken by waving irregularities and
+hillocks.</p>
+
+<p>It will be easy to show how closely the superficial inequalities agree with
+those which we might naturally expect to originate during the gradual rise
+of the Wealden district. Suppose the line of the most energetic movement to
+have coincided with what is now the central ridge of the Weald valley; in
+that case the first land which emerged must have been situated where the
+Forest ridge is now placed. Here many shoals and reefs may first have
+existed, and islands of chalk devoured in the course of ages by the ocean
+(see <a href="#img242">fig. 253.</a>); so that the top of the shattered dome which first appeared
+above water may have been utterly destroyed, and the masses represented by
+the fainter lines (<a href="#img242">fig. 253.</a>) removed.</p>
+
+<a id="img248" name="img248"></a>
+<div class="figcenter smaller width500">
+<img src="images/img248.jpg" width="500" height="185" alt="" title="">
+<p>The dotted lines represent the sea-level.</p></div>
+
+<p>The upper greensand is represented (<a href="#img248">fig. 259.</a>) as forming on the left hand
+a single precipice with the chalk; while on the right there are two cliffs,
+with an intervening terrace, as before described in <a href="#img247">fig. 258.</a> Two strips of
+land would then remain on each side of a channel, presenting ranges of
+white cliffs facing each other. A powerful current might then scoop out a
+channel in the gault (No. 2.). This softer bed would yield with ease in
+proportion as parts of it were brought up from time to time and exposed to
+the fury of the waves, so that large spaces occupied by the harder
+formation or greensand (No. 3.) would be laid bare. This last rock,
+opposing a more effectual resistance, would next emerge; while the chalk
+cliffs, at the base of which the gault is rapidly undermined, would recede
+farther from each other, after which four parallel strips of land, or rows
+of islands, would be caused, which are represented by the masses which in
+<a href="#img248">fig. 260.</a> rise above the dotted line indicating the sea-level. In this
+diagram, however, the inclination of the upper surface of the formations
+(Nos. 1. and 3.), is exaggerated. Originally this surface must have been
+level, like the submarine terraces produced by denudation, and described
+before (<a href="#page74">p. 74.</a> and <a href="#page77">77.</a>); but they were afterwards more and more tilted by
+that general movement to which the region of the Weald owes its structure.
+At length, by the farther elevation of the dome-shaped mass, the clay (No.
+4.) would be brought <span class="pagenum"><a id="page250"></a>[p.250]</span>within reach of the waves, which would
+probably gain the more easy access to the subjacent deposit by the rents
+which would be caused in No. 3., and in the central part of the ridge where
+the uplifting force had been exerted with the greatest energy. The opposite
+cliffs, in which the greensand (No. 3.) terminates, would now begin to
+recede from each other, having at their base a yielding stratum of clay
+(No. 4.). Lastly, the sea would penetrate to the sand (No. 5.), and then
+the state of things indicated in the dark lines of the upper section (<a href="#img242">fig.
+253.</a>), would be consummated.</p>
+
+<a id="img249" name="img249"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 261.</p>
+<img src="images/img249.jpg" width="500" height="338" alt="" title="">
+<p>The Coomb, near Lewes.</p></div>
+
+<p>It was stated that there are many lines of flexure and dislocation, running
+east and west, or parallel to the central axis of the Wealden. They are
+numerous in the district of the Hastings sand, and sometimes occur in the
+chalk itself. One of the latter kind has given rise to the ravine called
+the Coomb, near Lewes, and was first traced out by Dr. Mantell, in whose
+company I examined it. This coomb is seen on the eastern side of the valley
+of the Ouse, in the suburbs of the town of Lewes. The steep declivities on
+each side are covered with green turf, as is the bottom, which is perfectly
+dry. No outward signs of disturbance are visible; and the connection of the
+hollow with subterranean movements would not have been suspected by the
+geologist, had not the evidence of great convulsions been clearly exposed
+in the escarpment of the valley of the Ouse, and the numerous chalk pits
+worked at the termination of the Coomb. By the aid of these we discover
+that the ravine coincides precisely with a line of fault, on one side of
+which the chalk with flints (<i>a</i>, <a href="#img250">fig. 262.</a>), appears at the summit of the
+hill, while it is thrown down to the bottom on the other.</p>
+
+<p>Mr. Martin, in his work on the geology of Western Sussex, published in
+1828, threw much light on the structure of the Wealden by tracing out
+continuously for miles the direction of many anticlinal <span class="pagenum"><a id="page251"></a>[p.251]</span>lines and
+cross fractures; and the same course of investigation has since been
+followed out in greater detail by Mr. Hopkins. The mathematician
+last-mentioned has shown that the observed direction of the lines of
+flexure and dislocation in the Weald district coincide with those which
+might have been anticipated theoretically on mechanical principles, if we
+assume certain simple conditions under which the strata were lifted up by
+an expansive subterranean force. He finds by calculation that if this force
+was applied so as to act uniformly upwards within an elliptic area, the
+longitudinal fissures thereby produced would nearly coincide with the
+outlines of the ellipse, forming cracks, which are portions of smaller
+concentric ellipses, parallel to the margin of the larger one. These
+longitudinal fissures would also be intercepted by others running at right
+angles to them, and both lines of fracture may have been produced at the
+same time.<a name="FNanchor_U_12" id="FNanchor_U_12"></a><a href="#Footnote_U_12" class="fnanchor">[251-A]</a> In this illustration it is supposed that the expansive
+force acted simultaneously and with equal intensity at every point within
+the upheaved area, and not with greater energy along the central axis or
+region of principal elevation.</p>
+
+<a id="img250" name="img250"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 262.</p>
+<img src="images/img250.jpg" width="400" height="067" alt="" title="">
+<p>Fault in the cliff hills near <span class="wosp05">Lewes. Mantell.</span></p>
+<ul class="smaller martopm05 leftal add1em min1em">
+<li><i>a.</i> Chalk with flints.</li>
+<li><i>b.</i> Lower chalk.<a name="FNanchor_U_13" id="FNanchor_U_13"></a><a href="#Footnote_U_13" class="fnanchor">[251-B]</a></li>
+</ul></div>
+
+<p>The geologist cannot fail to derive great advantage in his speculations
+from the mathematical investigation of a problem of this kind, where
+results free from all uncertainty are obtained on the assumption of certain
+simple conditions. Such results, when once ascertained by mathematical
+methods, may serve as standard cases, to which others occurring in nature
+of a more complicated kind may be referred. In order that a uniform force
+should cause the strata to attain in the centre of the ellipse a height so
+far exceeding that which they have reached round the margin, it is
+necessary to assume that the mass of upheaved strata offered originally a
+very unequal degree of resistance to the subterranean force. This may have
+happened either from their being more fractured in one place than in
+another, or from being pressed down by a less weight of incumbent strata;
+as if we suppose, what is far from improbable, that great denudation had
+taken place in the middle of the Wealden before the final and principal
+upheaval occurred. It is suggested that the beds may have been acted upon
+somewhat in the manner of a carpet spread out loosely on a floor, and
+nailed down round the edges, which would swell into the shape of a dome if
+pressed up equally at every point by air admitted from beneath. But when we
+are reasoning on the particular phenomena of the Weald, we have no
+geological data for determining whether it be more probable that originally
+the resistance to be overcome was <span class="pagenum"><a id="page252"></a>[p.252]</span>so extremely unequal in
+different places, or whether the subterranean force, instead of being
+everywhere uniform, was not applied with very different degrees of
+intensity beneath distinct portions of the upraised area.</p>
+
+<p>The opinion that both the longitudinal and transverse lines of fracture may
+have been produced simultaneously, accords well with that expressed by M.
+Thurmann, in his work on the anticlinal ridges and valleys of elevation of
+the Bernese Jura.<a name="FNanchor_U_14" id="FNanchor_U_14"></a><a href="#Footnote_U_14" class="fnanchor">[252-A]</a> For the accuracy of his map and sections I can
+vouch, from personal examination, in 1835, of part of the region surveyed
+by him. Among other results, at which this author arrived, it appears that
+the breadth of all the numerous anticlinal ridges and dome-shaped masses in
+the Jura is invariably great in proportion to the number of the formations
+exposed to view; or, in other words, to the depth to which the superimposed
+groups of secondary strata have been laid open. (See <a href="#img076">fig. 71.</a> <a href="#page55">p. 55.</a> for
+structure of Jura.) He also remarks, that the anticlinal lines are
+occasionally oblique and cross each other, in which case the greatest
+dislocation of the beds takes place. Some of the cross fractures are
+imagined by him to have been contemporaneous, others subsequent to the
+longitudinal ones.</p>
+
+<p>I have assumed, in the former part of this chapter, that the rise of the
+Weald was gradual, whereas many geologists have attributed its elevation to
+a single effort of subterranean violence. There appears to them such a
+unity of effect in this and other lines of deranged strata in the
+south-east of England, such as that of the Isle of Wight, as is
+inconsistent with the supposition of a great number of separate movements
+recurring after long intervals of time. But we know that earthquakes are
+repeated throughout a long series of ages in the same spots, like volcanic
+eruptions. The oldest lavas of Etna were poured out many thousands, perhaps
+myriads of years before the newest, and yet they, and the movements
+accompanying their emission, have produced a symmetrical mountain; and if
+rivers of melted matter thus continue to flow in the same direction, and
+towards the same point, for an indefinite lapse of ages, what difficulty is
+there in conceiving that the subterranean volcanic force, occasioning the
+rise or fall of certain parts of the earth's crust, may, by reiterated
+movements, produce the most perfect unity of result?</p>
+
+<p><i>Alluvium of the Weald.</i>&mdash;Our next inquiry may be directed to the alluvium
+strewed over the surface of the supposed area of denudation. Has any wreck
+been left behind of the strata removed? To this we may answer, that the
+chalk downs even on their summits are covered every where with gravel
+composed of unrounded and partially rounded chalk flints, such as might
+remain after masses of white chalk had been softened and removed by water.
+This superficial accumulation of the hard or siliceous materials of the
+disintegrated strata may be due in some degree to pluvial action; for
+during extraordinary rains a rush of water charged with calcareous matter,
+of a milk-white colour, may be seen to descend even gently sloping hills of
+chalk. If a layer no thicker than the tenth of an inch be removed once in a
+century, <span class="pagenum"><a id="page253"></a>[p.253]</span>a considerable mass may in the course of indefinite ages
+melt away, leaving nothing save a layer of flinty nodules to attest its
+former existence. These unrolled flints may remain mixed with others more
+or less rounded, which the waves left originally on the surface of the
+chalk, when it first emerged from the sea. A stratum of fine clay sometimes
+covers the surface of slight depressions and the bottom of valleys in the
+white chalk, which may represent the aluminous residue of the rock, after
+the pure carbonate of lime has been dissolved by rain water, charged with
+excess of carbonic acid derived from decayed vegetable matter.<a name="FNanchor_U_15" id="FNanchor_U_15"></a><a href="#Footnote_U_15" class="fnanchor">[253-A]</a></p>
+
+<p>Although flint gravel is so abundant on the chalk itself, it is usually
+wanting in the deep longitudinal valleys at the foot of the chalk
+escarpment, although, in some few instances, the detritus of the chalk has
+been traced in patches over the gault, and even the lower greensand, for a
+distance of several miles from the escarpment of the North and South Downs.
+But no vestige of the chalk and its flints has been seen on the central
+ridge of the Weald or the Hastings sands, but merely gravel derived from
+the rocks immediately subjacent. This distribution of alluvium, and
+especially the absence of chalk detritus in the central district, agrees
+well with the theory of denudation before set forth; for to return to <a href="#img248">fig.
+259.</a>, if the chalk (No. 1.) were once continuous and covered every where
+with flint gravel, this superficial covering would be the first to be
+carried away from the highest part of the dome long before any of the gault
+(No. 2.) was laid bare. Now if some ruins of the chalk remain at first on
+the gault, these would be, in a great degree, cleared away before any part
+of the lower greensand (No. 3.) is denuded. Thus in proportion to the
+number and thickness of the groups removed in succession, is the
+probability lessened of our finding any remnants of the highest group
+strewed over the bared surface of the lowest.</p>
+
+<p>As an exception to the general rule of the small distance to which any
+wreck of the chalk can be traced from the escarpments of the North and
+South Downs, I may mention a thick bed of chalk flints which occurs near
+Barcombe, about three miles to the north of Lewes (see <a href="#img251">fig. 263.</a>), a place
+which I visited with Dr. Mantell, to whom I am indebted for the
+accompanying section. Even here it will be seen that the gravel reaches no
+farther than the Weald Clay. The same section shows one of the minor east
+and west anticlinal lines before alluded to (<a href="#page244">p. 244.</a>).</p>
+
+<a id="img251" name="img251"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 263.</p>
+<img src="images/img251.jpg" width="500" height="105" alt="" title="">
+<p>Section from the north escarpment of the South Downs to Barcombe.</p>
+<ul class="smaller martopm05 leftal add1em min1em">
+<li>1. Gravel composed of partially rounded chalk flints.</li>
+<li>2. Chalk with and without flints.</li>
+<li>3. Lowest chalk or chalk marl (upper greensand wanting).</li>
+<li>4. Gault.</li>
+<li>5. Lower greensand.</li>
+<li>6. Weald clay.</li>
+</ul></div>
+
+<p><span class="pagenum"><a id="page254"></a>[p.254]</span><i>At what period the Weald Valley was denuded.</i>&mdash;If we inquire at
+what geological period the denudation of the Weald was effected, we shall
+immediately perceive that the question is limited to this point, whether it
+took place during or subsequent to the deposition of the Eocene strata of
+the south of England. For in the basins of London and Hampshire the Eocene
+strata are conformable to the chalk, being horizontal where the beds of
+chalk are horizontal, and vertical where they are vertical, so that both
+series of rocks appear to have participated in nearly the same movements.
+At the eastern extremity of the Isle of Wight, some beds even of the
+freshwater series have been thrown on their edges, like those of the London
+clay. Nevertheless we can by no means infer that all the tertiary deposits
+of the London and Hampshire basins once extended like the chalk over the
+entire valley of the Weald, because the denudation of the chalk and
+greensand may have been going on in the centre of that area, while
+contiguous parts of the sea were sufficiently deep to receive and retain
+the matter derived from that waste. Thus while the waves and currents were
+excavating the longitudinal valleys D and C (<a href="#img252">fig. 264.</a>), the deposits <i>a</i>
+may have been thrown down to the bottom of the contiguous deep water E, the
+sediment being drifted through transverse fissures, as before explained. In
+this case, the rise of the formations Nos. 1, 2, 3, 4, 5, may have been
+going on contemporaneously with the excavation of the valleys C and D, and
+with the accumulation of the tertiary strata <i>a</i>.</p>
+
+<a id="img252" name="img252"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 264.</p>
+<img src="images/img252.jpg" width="400" height="065" alt="" title=""></div>
+
+<p>This idea receives some countenance from the fact of the tertiary strata,
+near their junction with the chalk of the London and Hampshire basins,
+often consisting of dense beds of sand and shingle, as at Blackheath and in
+the Addington Hills near Croydon. They also contain occasionally freshwater
+shells and the remains of land animals and plants, which indicate the
+former presence of land at no great distance, some part of which may have
+occupied the centre of the Weald.</p>
+
+<p>Such masses of well-rolled pebbles occurring in the lowest Eocene strata,
+or those called "the plastic clay and sands" before described (No. 3. <i>b</i>,
+Tab. <a href="#page197">p. 197.</a>), imply the neighbourhood of an ancient shore. They also
+indicate the destruction of pre-existing chalk with flints. At the same
+time fossil shells of the genera <i>Melania</i>, <i>Cyclas</i>, and <i>Unio</i>, appearing
+here and there in beds of the same age, together with plants and the bones
+of land animals, bear testimony to contiguous land, which probably
+constituted islands scattered over the space now occupied by the tertiary
+basins of the Seine and Thames. The stage of denudation represented in <a href="#img248">fig.
+259.</a>, <a href="#page249">p. 249.</a>, may explain the state of things prevailing at points where
+such islands existed. By the alternate rising and sinking of the white
+chalk and older beds, a large area may have become overspread with gravelly
+sandy, and <span class="pagenum"><a id="page255"></a>[p.255]</span>clayey beds of fluvio-marine and shallow-water origin,
+before any of the London clay proper (or Calcaire grossier in France) were
+superimposed. This may account for the fact that patches of "plastic clay
+and sand" (No. 3. <i>b</i>, Tab. <a href="#page197">p. 197.</a>), are scattered over the surface of the
+chalk, reaching in some places to great heights, and approaching even the
+edges of the escarpments. We must suppose that subsequently a gradual
+subsidence took place in certain areas, which allowed the London clay
+proper to accumulate over the Lower Eocene sands and clays, in a deep sea.
+During this sinking down (the vertical amount of which equalled 800, and in
+parts of the Isle of Wight, according to Mr. Prestwich, 1800 feet), the
+work of denudation would be unceasing, being always however confined to
+those areas where land or islands existed. At length, when the Bagshot sand
+had been in its turn thrown down on the London clay, the space covered by
+these two formations was again upraised from the sea to about the height
+which it has since retained. During this upheaval, the waves would again
+exert their power, not only on the white chalk and lower cretaceous and
+Wealden strata, but also on the Eocene formations of the London basin,
+excavating valleys and undermining cliffs as the strata emerged from the
+deep.</p>
+
+<p>There are grounds, as before stated (<a href="#page205">p. 205.</a>), for presuming that the
+tertiary area of London was converted into land before that of Hampshire,
+and for this reason it contains no marine Eocene deposits so modern as
+those of Barton Cliff, or the still newer freshwater and fluvio-marine beds
+of Hordwell and the Isle of Wight. These last seem unequivocally to
+demonstrate the local inequality of the upheaving and depressing movements
+of the period alluded to; for we find, in spite of the evidence afforded in
+Alum and White Cliff Bays, of continued depression to the extent of 1800 or
+2000 feet, that at the close of the Eocene period a dense formation of
+freshwater strata was produced. The fossils of these strata bear testimony
+to rivers draining adjacent lands, and the existence of numerous quadrupeds
+on those lands. Instead of such phenomena, the signs of an open sea might
+naturally have been expected as the consequence of so much subsidence, had
+not the depression been accompanied or followed by upheaval in a region
+immediately adjoining.</p>
+
+<p>When we attempt to speculate on the geographical changes which took place
+in the earlier part of the Eocene epoch, and to restore in imagination the
+former state of the physical geography of the south-east of England, we
+shall do well to bear in mind that wherever there are proofs of great
+denudation, there also the greatest area of land has probably existed. In
+the same space, moreover, the oscillations of level, and the alternate
+submergence and emergence of coasts, may be presumed to have been most
+frequent; for these fluctuations facilitate the wasting and removing power
+of waves, currents, and rivers.</p>
+
+<p>We should also remember that there is always a tendency in the last
+denuding operations, to efface all signs of preceding denudation, or at
+least all those marks of waste from which alone a geologist can ascertain
+the date of the removal of the missing strata within the denuded area. It
+may often be difficult to settle the chronology even <span class="pagenum"><a id="page256"></a>[p.256]</span>of the last
+of a series of such acts of removal, but it must be, in the nature of
+things, almost always impossible to assign a date to each of the antecedent
+denudations. If we wish to determine the times of the destruction of rocks,
+we must look any where rather than to the spaces once occupied by the
+missing rocks. We must inquire to what regions the ruins of the white
+chalk, greensand, Wealden, and other strata which have disappeared were
+transported. We are then led at once to the examination of all the deposits
+newer than the chalk, and first to the oldest of these, the Lower Eocene,
+and its sand, shingle, and clay. In them, so largely developed in the
+immediate neighbourhood of the denuded area, we discover the wreck we are
+in search of, regularly stratified, and inclosing, in some of its layers,
+organic remains of a littoral, and sometimes fluviatile character. What
+more can we desire? The shores must have consisted of chalk, greensand, and
+Wealden, since these were the only superficial rocks in the south-east of
+England, at the commencement of the Eocene epoch. The waves of the sea,
+therefore, and the rivers were grinding down chalk-flints and chert from
+the greensand into shingle and sand, or were washing away calcareous and
+argillaceous matter from the cretaceous and Wealden beds, during the whole
+of the Eocene period. Thus we obtain the date of a great part at least of
+that enormous amount of denudation of which we have such striking monuments
+in the space intervening between the North and South Downs.</p>
+
+<a id="img253" name="img253"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 265.</p>
+<img src="images/img253.jpg" width="450" height="342" alt="" title="">
+<ul class="smaller leftal add1em min2em">
+<li>A. Chalk with layers of flint dipping slightly to the south.</li>
+<li><i>b.</i> Ancient beach, consisting of fine sand, from one to four feet thick, covered by shingle from five
+to eight feet thick of pebbles of chalk-flint, granite, and other rocks, with broken shells of recent
+marine species, and bones of cetacea.</li>
+<li><i>c.</i> Elephant bed, about fifty feet thick, consisting of layers of white chalk rubble, with broken chalk-flints,
+in which deposit are found bones of ox, deer, horse, and mammoth.</li>
+<li><i>d.</i> Sand and shingle of modern beach.</li>
+</ul></div>
+
+<p>There have been some movements of land on a smaller scale since the Eocene
+period in the south-east of England. One of the latest of these happened in
+the Pleistocene, or even perhaps as late as the Post-Pliocene period. The
+formation called by Dr. Mantell the Elephant <span class="pagenum"><a id="page257"></a>[p.257]</span>Bed, at the foot of
+the chalk cliffs at Brighton, is not merely a talus of calcareous rubble
+collected at the base of an inland cliff, but exhibits every appearance of
+having been spread out in successive horizontal layers by water in motion.</p>
+
+<p>The deposit alluded to skirts the shores between Brighton and Rottingdean,
+and another mass apparently of the same age occurs at Dover. The phenomena
+appear to me to suggest the following conclusions:&mdash;First, the
+south-eastern part of England had acquired its actual configuration when
+the ancient chalk cliff A <i>a</i> was formed, the beach of sand and shingle <i>b</i>
+having then been thrown up at the base of the cliff. Afterwards the whole
+coast, or at least that part of it where the elephant bed now extends,
+subsided to the depth of 50 or 60 feet; and during the period of
+submergence successive layers of white calcareous rubble <i>c</i> were
+accumulated, so as to cover the ancient beach <i>b</i>. Subsequently, the coast
+was again raised, so that the ancient shore was elevated to a level
+somewhat higher than its original position.<a name="FNanchor_U_16" id="FNanchor_U_16"></a><a href="#Footnote_U_16" class="fnanchor">[257-A]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XX.</h2>
+
+<h4>OOLITE AND LIAS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Subdivisions of the Oolitic or Jurassic group &mdash; Physical geography of
+the Oolite in England and France &mdash; Upper Oolite &mdash; Portland stone
+and fossils &mdash; Lithographic stone of Solenhofen &mdash; Middle Oolite,
+coral rag &mdash; Zoophytes &mdash; Nerin�an limestone &mdash; Diceras
+limestone &mdash; Oxford clay, Ammonites and Belemnites &mdash; Lower Oolite,
+Crinoideans &mdash; Great Oolite and Bradford clay &mdash; Stonesfield
+slate &mdash; Fossil mammalia, placental and marsupial &mdash; Resemblance to
+an Australian fauna &mdash; Doctrine of progressive
+development &mdash; Collyweston slates &mdash; Yorkshire Oolitic
+coal-field &mdash; Brora coal &mdash; Inferior Oolite and fossils.</p></div>
+
+
+<p><i><span class="smcap">Oolitic or Jurassic Group.</span></i>&mdash;Below the freshwater group called the
+Wealden, or, where this is wanting, immediately beneath the Cretaceous
+formation, a great series of marine strata, commonly called "the Oolite,"
+occurs in England and many other parts of Europe. This group has been so
+named, because, in the countries where it was first examined, the
+limestones belonging to it had an oolitic structure (see <a href="#page12">p. 12.</a>). These
+rocks occupy in England a zone which is nearly 30 miles in average breadth,
+and extends across the island, from Yorkshire in the north-east, to
+Dorsetshire in the south-west. Their mineral characters are not uniform
+throughout this <span class="pagenum"><a id="page258"></a>[p.258]</span>region; but the following are the names of the
+principal subdivisions observed in the central and south-eastern parts of
+England:&mdash;</p>
+
+
+<table  border="0" cellpadding="2" summary="PRINCIPAL SUBDIVISIONS OF THE JURASSIC
+GROUP IN THE CENTRAL AND SOUTH-EASTERN PARTS OF ENGLAND.">
+<colgroup>
+    <col width="25%">
+    <col width="10%">
+    <col width="3%">
+    <col width="56%">
+</colgroup>
+
+<tr>
+  <td colspan="4" class="td-center tdtx-top ftsize105">OOLITE.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left">Upper</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 20pt; font-weight: 600;" class="tdtx-top">{</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="td-left tdtx-top tdp-left"><i>a.</i> Portland stone and sand.<br><i>b.</i> Kimmeridge clay.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left">Middle</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 20pt; font-weight: 600;" class="tdtx-top">{</td>
+  <td class="td-left tdtx-top tdp-left"><i>c.</i> Coral rag.<br><i>d.</i> Oxford clay.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left" style="padding-top: 0.4em;">Lower</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 40pt; font-weight: 100;" class="tdtx-top">{</td>
+  <td style="padding-top: 0.7em;" class="td-left tdtx-top tdp-left"><i>e.</i> Cornbrash and Forest marble.<br><i>f.</i> Great Oolite and Stonesfield slate.<br>
+  <i>g.</i> Fuller's earth.<br><i>h.</i> Inferior Oolite.</td>
+</tr>
+
+<tr>
+  <td colspan="4" class="td-center tdtx-top">The Lias then succeeds to the Inferior Oolite.</td>
+</tr>
+</table>
+
+
+<p>The Upper oolitic system of the above table has usually the Kimmeridge clay
+for its base; the Middle oolitic system, the Oxford clay. The Lower system
+reposes on the Lias, an argillo-calcareous formation, which some include in
+the Lower Oolite, but which will be treated of separately in the next
+chapter. Many of these subdivisions are distinguished by peculiar organic
+remains; and though varying in thickness, may be traced in certain
+directions for great distances, especially if we compare the part of
+England to which the above-mentioned type refers with the north-east of
+France, and the Jura mountains adjoining. In that country, distant above
+400 geographical miles, the analogy to the English type, notwithstanding
+the thinness, or occasional absence of the clays, is more perfect than in
+Yorkshire or Normandy.</p>
+
+<p><i>Physical geography.</i>&mdash;The alternation, on a grand scale, of distinct
+formations of clay and limestone, has caused the oolitic and liassic series
+to give rise to some marked features in the physical outline of parts of
+England and France. Wide valleys can usually be traced throughout the long
+bounds of country where the argillaceous strata crop out; and between these
+valleys the limestones are observed, composing ranges of hills, or more
+elevated grounds. These ranges terminate abruptly on the side on which the
+several clays rise up from beneath the calcareous strata.</p>
+
+<a id="img254" name="img254"></a>
+<div class="figcenter smaller">
+<p>Fig. 266.</p>
+<img src="images/img254.jpg" width="450" height="092" alt="" title=""></div>
+
+<p>The annexed diagram will give the reader an idea of the configuration of
+the surface now alluded to, such as may be seen in passing from London to
+Cheltenham, or in other parallel lines, from east to west, in the southern
+part of England. It has been necessary, however, in this drawing, greatly
+to exaggerate the inclination of the beds, and the height of the several
+formations, as compared to their horizontal extent. It will be remarked,
+that the lines of cliff, or escarpment, face towards the west in the great
+calcareous eminences formed by the Chalk and the Upper, Middle, and Lower
+Oolites; and at the base of which we have respectively the Gault,
+Kimmeridge clay, Oxford clay, and Lias. This last forms, generally, a broad
+vale <span class="pagenum"><a id="page259"></a>[p.259]</span>at the foot of the escarpment of inferior oolite, but where
+it acquires considerable thickness, and contains solid beds of marlstone,
+it occupies the lower part of the escarpment.</p>
+
+<p>The external outline of the country which the geologist observes in
+travelling eastward from Paris to Metz is precisely analogous, and is
+caused by a similar succession of rocks intervening between the tertiary
+strata and the Lias; with this difference, however, that the escarpments of
+Chalk, Upper, Middle, and Lower Oolites, face towards the east instead of
+the west.</p>
+
+<p>The Chalk crops out from beneath the tertiary sands and clays of the Paris
+basin, near Epernay, and the Gault from beneath the Chalk and Upper
+Greensand at Clermont-en-Argonne; and passing from this place by Verdun and
+Etain to Metz, we find two limestone ranges, with intervening vales of
+clay, precisely resembling those of southern and central England, until we
+reach the great plain of Lias at the base of the Inferior Oolite at Metz.</p>
+
+<p>It is evident, therefore, that the denuding causes have acted similarly
+over an area several hundred miles in diameter, sweeping away the softer
+clays more extensively than the limestones, and undermining these last so
+as to cause them to form steep cliffs wherever the harder calcareous rock
+was based upon a more yielding and destructible clay. This denudation
+probably occurred while the land was slowly rising out of the sea.<a name="FNanchor_V_1" id="FNanchor_V_1"></a><a href="#Footnote_V_1" class="fnanchor">[259-A]</a></p>
+
+
+<h3><i>Upper Oolite.</i></h3>
+
+<p>The Portland stone has already been mentioned as forming in Dorsetshire the
+foundation on which the freshwater limestone of the Lower Purbeck reposes
+(see <a href="#page232">p. 232.</a>). It supplies the well-known building stone of which St.
+Paul's and so many of the principal edifices of London are constructed.
+This upper member, characterized by peculiar marine fossils, rests on a
+dense bed of sand, called the Portland sand, below which is the Kimmeridge
+clay. In England these Upper Oolite formations are almost wholly confined
+to the southern counties. Corals are rare in them, although one species is
+found plentifully at Tisbury, in Wiltshire, in the Portland sand converted
+into flint and chert, the original calcareous matter being replaced by
+silex (<a href="#img255">fig. 267.</a>).</p>
+
+<a id="img255" name="img255"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 267.</p>
+<img src="images/img255.jpg" width="250" height="326" alt="" title="">
+<p><i>Columnaria oblonga</i>, Blainv.</p>
+<p>As seen on a polished slab of chert from the sand of the Upper Oolite,
+Tisbury.</p></div>
+
+<p>Among the characteristic fossils of the Upper Oolite, may be mentioned the
+<i>Ostrea deltoidea</i> (<a href="#img256">fig. 269.</a>), found in the Kimmeridge clay throughout
+England and the north of France, and also in Scotland, near Brora. The
+<i>Gryph�a virgula</i> (<a href="#img256">fig. 268.</a>), also met with in the same clay near Oxford,
+is so abundant in the Upper Oolite of parts of France as to have caused the
+deposit to be termed "marnes � gryph�es virgules." Near <span class="pagenum"><a id="page260"></a>[p.260]</span>Clermont,
+in Argonne, a few leagues from St. Menehould, where these indurated marls
+crop out from beneath the gault, I have seen them, on decomposing, leave
+the surface of every ploughed field literally strewed over with this fossil
+oyster.</p>
+
+<a id="img256" name="img256"></a>
+<div class="figcenter smaller width350">
+<img src="images/img256.jpg" width="350" height="213" alt="" title="">
+<p>Upper Oolite: Kimmeridge clay. <sup>1</sup>/<sub>4</sub> nat. size.</p>
+<p>Fig. 268. <i>Gryph�a virgula.</i></p>
+<p class="martopm05">Fig. 269. <i>Ostrea deltoidea.</i></p></div>
+
+<a id="img257" name="img257"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 270.</p>
+<img src="images/img257.jpg" width="250" height="216" alt="" title="">
+<p><i>Trigonia gibbosa.</i> <sup>1</sup>/<sub>2</sub> nat. size. <i>a.</i> the hinge.</p>
+<p>Portland Oolite, Tisbury.</p></div>
+
+<p>The Kimmeridge clay consists, in great part, of a bituminous shale,
+sometimes forming an impure coal several hundred feet in thickness. In some
+places in Wiltshire it much resembles peat; and the bituminous matter may
+have been, in part at least, derived from the decomposition of vegetables.
+But as impressions of plants are rare in these shales, which contain
+ammonites, oysters, and other marine shells, the bitumen may perhaps be of
+animal origin.</p>
+
+<p>The celebrated lithographic stone of Solenhofen, in Bavaria, belongs to one
+of the upper divisions of the oolite, and affords a remarkable example of
+the variety of fossils which may be preserved under favourable
+circumstances, and what delicate impressions of the tender parts of certain
+animals and plants may be retained where the sediment is of extreme
+fineness. Although the number of testacea in this slate is small, and the
+plants few, and those all marine, Count Munster had determined no less than
+237 species of fossils when I saw his collection in 1833; and among them no
+less than seven <i>species</i> of flying lizards, or pterodactyls, six saurians,
+three tortoises, sixty species of fish, forty-six of crustacea, and
+twenty-six of insects. These insects, among which is a libellula, or
+dragon-fly, must have been blown out to sea, probably from the same land to
+which the flying lizards, and other contemporaneous reptiles, resorted.</p>
+
+
+<h3><i>Middle Oolite.</i></h3>
+
+<p><i>Coral Rag.</i>&mdash;One of the limestones of the Middle Oolite has been called
+the "Coral Rag," because it consists, in part, of continuous beds of
+petrified corals, for the most part retaining the position in which they
+grew at the bottom of the sea. They belong chiefly to the genera
+<i>Caryophyllia</i> (<a href="#img258">fig. 271.</a>), <i>Agaricia</i>, and <i>Astrea</i>, and sometimes form
+masses of coral 15 feet thick. In the annexed figure of an <i>Astrea</i>, from
+this formation, it will be seen that the cup-shaped cavities are deepest on
+the right-hand side, and that they grow more and more shallow, till those
+on the left side are nearly filled up. The last-named stars are supposed to
+be Polyparia of advanced age. <span class="pagenum"><a id="page261"></a>[p.261]</span>These coralline strata extend
+through the calcareous hills of the N.W. of Berkshire, and north of Wilts,
+and again recur in Yorkshire, near Scarborough.</p>
+
+<a id="img258" name="img258"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 271.</p>
+<img src="images/img258.jpg" width="250" height="345" alt="" title="">
+<p><i>Caryophyllia annularis</i>, Parkin. Coral rag,
+Steeple Ashton.</p></div>
+
+<a id="img259" name="img259"></a>
+<div class="floatright smaller width250">
+<p>Fig 272.</p>
+<img src="images/img259.jpg" width="250" height="177" alt="" title="">
+<p><i>Astrea</i><span class="wosp05">. Coral</span> rag.</p></div>
+
+<p class="nofloat">One of the limestones of the Jura, referred to the age of the English coral
+rag, has been called "Nerin�an limestone" (Calcaire � N�rin�es) by M.
+Thirria; <i>Nerin�a</i> being an extinct genus of univalve shells, much
+resembling the <i>Cerithium</i> in external form. The annexed section (<a href="#img260">fig.
+273.</a>) shows the curious form of the hollow part of each whorl, and also the
+perforation which passes up the middle of the columella. <i>N. Goodhallii</i>
+(<a href="#img261">fig. 274.</a>) is another English species of the same genus, from a formation
+which seems to form a passage from the Kimmeridge clay to the coral
+rag.<a name="FNanchor_V_2" id="FNanchor_V_2"></a><a href="#Footnote_V_2" class="fnanchor">[261-A]</a></p>
+
+<a id="img260" name="img260"></a>
+<div class="floatleft smaller width125">
+<p>Fig. 273.</p>
+<img src="images/img260.jpg" width="125" height="479" alt="" title="">
+<p><i>Nerin�a hieroglyphica.</i> Coral rag.</p></div>
+
+<a id="img261" name="img261"></a>
+<div class="floatright smaller width300">
+<p>Fig. 274.</p>
+<img src="images/img261.jpg" width="300" height="350" alt="" title="">
+<p><i>Nerin�a Goodhallii</i>, Fitton. Coral rag, Weymouth.
+<sup>1</sup>/<sub>4</sub> nat. size.</p></div>
+
+<p class="nofloat">A division of the oolite in the Alps, regarded by most geologists as coeval
+with the English coral rag, has been often named "Calcaire � Dicerates," or
+"Diceras limestone," from its containing abundantly a bivalve shell (see
+<a href="#img262">fig. 275.</a>) of a genus allied to the <i>Chama</i>.</p>
+
+<span class="pagenum"><a id="page262"></a>[p.262]</span>
+<a id="img262" name="img262"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 275.</p>
+<img src="images/img262.jpg" width="200" height="218" alt="" title="">
+<p>Cast of <i>Diceras arietina</i>. Coral rag, France.</p></div>
+
+<a id="img263" name="img263"></a>
+<div class="floatright smaller width200">
+<p>Fig. 276.</p>
+<img src="images/img263.jpg" width="200" height="294" alt="" title="">
+<p><i>Cidaris coronata.</i> Coral rag.</p></div>
+
+<p class="nofloat"><i>Oxford Clay.</i>&mdash;The coralline limestone, or "coral rag," above described,
+and the accompanying sandy beds, called "calcareous grits" of the Middle
+Oolite, rests on a thick bed of clay, called the Oxford clay, sometimes not
+less than 500 feet thick. In this there are no corals, but great abundance
+of cephalopoda of the genera Ammonite and Belemnite. (See <a href="#img264">fig. 277.</a>) In
+some of the clay of very fine texture ammonites are very perfect, although
+somewhat compressed, and are seen to be furnished on each side of the
+aperture with a single horn-like projection (see <a href="#img265">fig. 278.</a>). These were
+discovered in the cuttings of the Great Western Railway, near Chippenham,
+in 1841, and have been described by Mr. Pratt.<a name="FNanchor_V_3" id="FNanchor_V_3"></a><a href="#Footnote_V_3" class="fnanchor">[262-A]</a></p>
+
+<a id="img264" name="img264"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 277.</p>
+<img src="images/img264.jpg" width="350" height="032" alt="" title="">
+<p><i>Belemnites hastatus.</i> Oxford Clay.</p></div>
+
+<a id="img265" name="img265"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 278.</p>
+<img src="images/img265.jpg" width="350" height="399" alt="" title="">
+<p><i>Ammonites Jason</i>, <span class="wosp05">Reinecke. Syn.</span> <i>A. Elizabeth�</i>,
+Pratt. Oxford clay, Christian Malford, Wiltshire.</p></div>
+
+<span class="pagenum"><a id="page263"></a>[p.263]</span>
+<a id="img266" name="img266"></a>
+<div class="figcenter smaller width225">
+<p class="martop2">Fig. 279.</p>
+<img src="images/img266.jpg" width="100" height="526" alt="" title="">
+<p><i>Belemnites Puzosianus</i>, D'Orb. Oxford Clay, Christian Malford.</p>
+<ul class="martopm05 smaller leftal min1em">
+<li><i>a, a.</i> projecting processes of the shell or phragmocone.</li>
+<li><i>b, c.</i> broken exterior of a conical shell called the phragmocone,
+which is chambered within, or composed of a series of shallow concave
+cells pierced by a siphuncle.</li>
+<li><i>c, d.</i> The guard or osselet, which is commonly called
+the belemnite.</li>
+</ul></div>
+
+<p>Similar elongated processes have been also observed to extend from the
+shells of some belemnites discovered by Dr. Mantell in the same clay (see
+<a href="#img266">fig. 279.</a>), who, by the aid of this and other specimens, has been able to
+throw much light on the structure of this singular extinct form of
+cuttle-fish.<a name="FNanchor_V_4" id="FNanchor_V_4"></a><a href="#Footnote_V_4" class="fnanchor">[263-A]</a></p>
+
+
+<h3><i>Lower Oolite.</i></h3>
+
+<p>The upper division of this series, which is more extensive than the
+preceding or Middle Oolite, is called in England the Cornbrash. It consists
+of clays and calcareous sandstones, which pass downwards into the Forest
+marble, an argillaceous limestone, abounding in marine fossils. In some
+places, as at Bradford, this limestone is replaced by a mass of clay. The
+sandstones of the Forest Marble of Wiltshire are often ripple-marked and
+filled with fragments of broken shells and pieces of drift-wood, having
+evidently been formed on a coast. Rippled slabs of fissile oolite are used
+for roofing, and have been traced over a broad band of country from
+Bradford, in Wilts, to Tetbury, in Gloucestershire. These calcareous
+tile-stones are separated from each other by thin seams of clay, which have
+been deposited upon them, and have taken their form, preserving the
+undulating ridges and furrows of the sand in such complete integrity, that
+the impressions of small footsteps, apparently of crabs, which walked over
+the soft wet sands, are still visible. In the same stone the claws of
+crabs, fragments of echini, and other signs of a neighbouring beach are
+observed.<a name="FNanchor_V_5" id="FNanchor_V_5"></a><a href="#Footnote_V_5" class="fnanchor">[263-B]</a></p>
+
+<p><i>Great Oolite.</i>&mdash;Although the name of coral-rag has been appropriated, as
+we have seen, to a member of the Upper Oolite before described, some
+portions of the Lower Oolite are equally intitled in many places to be
+called coralline limestones. Thus the Great Oolite near Bath contains
+various corals, among which the <i>Eunomia radiata</i> <span class="pagenum"><a id="page264"></a>[p.264]</span>(<a href="#img267">fig. 280.</a>) is
+very conspicuous, single individuals forming masses several feet in
+diameter; and having probably required, like the large existing brain-coral
+(<i>Meandrina</i>) of the tropics, many centuries before their growth was
+completed.</p>
+
+<a id="img267" name="img267"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 280.</p>
+<img src="images/img267.jpg" width="400" height="178" alt="" title="">
+<p><i>Eunomia radiata</i>, Lamouroux.</p>
+<ul class="smaller martopm05 leftal add1em min1em">
+<li><i>a.</i> section transverse to the tubes.</li>
+<li><i>b.</i> vertical section, showing the radiation of the tubes.</li>
+<li><i>c.</i> portion of interior of tubes magnified, showing striated surface.</li>
+</ul></div>
+
+<a id="img268" name="img268"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 281.</p>
+<img src="images/img268.jpg" width="400" height="213" alt="" title="">
+<p><i>Apiocrinites rotundus</i>, or Pear Encrinite;
+<span class="wosp05">Miller. Fossil</span> at Bradford, Wilts.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Stem of <i>Apiocrinites</i>, and one of the articulations, natural size.</li>
+<li><i>b.</i> Section at Bradford of great oolite and overlying clay, containing
+the fossil encrinites. See text.</li>
+<li><i>c.</i> Three perfect individuals of Apiocrinites, represented as they
+grew on the surface of the Great Oolite.</li>
+<li><i>d.</i> Body of the <i>Apiocrinites rotundus</i>.</li>
+</ul></div>
+
+<p>Different species of <i>Crinoideans</i>, or stone-lilies, are also common in the
+same rocks with corals; and, like them, must have enjoyed a firm bottom,
+where their root, or base of attachment, remained undisturbed for years
+(<i>c</i>, <a href="#img268">fig. 281.</a>). Such fossils, therefore, are almost confined to the
+limestones; but an exception occurs at Bradford, near Bath, where they are
+enveloped in clay. In this case, however, it appears that the solid upper
+surface of the "Great Oolite" had supported, for a time, a thick submarine
+forest of these beautiful zoophytes, until the clear and still water was
+invaded by a current charged with mud, which threw down the stone-lilies,
+and broke most of their stems short off near the point of attachment. The
+stumps still remain in their original position; but the numerous
+articulations once composing the stem, arms, and body of the zoophyte, were
+scattered at random through the argillaceous deposit <span class="pagenum"><a id="page265"></a>[p.265]</span>in which
+some now lie prostrate. These appearances are represented in the section
+<i>b</i>, <a href="#img268">fig. 281.</a>, where the darker strata represent the Bradford clay, which
+some geologists class with the Forest marble, others with the Great Oolite.
+The upper surface of the calcareous stone below is completely incrusted
+over with a continuous pavement, formed by the stony roots or attachments
+of the Crinoidea; and besides this evidence of the length of time they had
+lived on the spot, we find great numbers of single joints, or circular
+plates of the stem and body of the encrinite, covered over with <i>serpul�</i>.
+Now these <i>serpul�</i> could only have begun to grow after the death of some
+of the stone-lilies, parts of whose skeletons had been strewed over the
+floor of the ocean before the irruption of argillaceous mud. In some
+instances we find that, after the parasitic <i>serpul�</i> were full grown, they
+had become incrusted over with a coral, called <i>Berenicea diluviana</i>; and
+many generations of these polyps had succeeded each other in the pure water
+before they became fossil.</p>
+
+<a id="img269" name="img269"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 282.</p>
+<img src="images/img269.jpg" width="400" height="212" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> Single plate or articulation of an Encrinite overgrown with <i>serpul�</i> and <span class="wosp05">corals. Natural</span> size
+Bradford clay.</li>
+<li><i>b.</i> Portion of the same magnified, showing the coral <i>Berenicea diluviana</i>
+covering one of the <i>serpul�</i>.</li>
+</ul></div>
+
+<p>We may, therefore, perceive distinctly that, as the pines and cycadeous
+plants of the ancient "dirt bed," or fossil forest, of the Lower Purbeck
+were killed by submergence under fresh water, and soon buried beneath muddy
+sediment, so an invasion of argillaceous matter put a sudden stop to the
+growth of the Bradford Encrinites, and led to their preservation in marine
+strata.<a name="FNanchor_V_6" id="FNanchor_V_6"></a><a href="#Footnote_V_6" class="fnanchor">[265-A]</a></p>
+
+<p>Such differences in the fossils as distinguish the calcareous and
+argillaceous deposits from each other, would be described by naturalists as
+arising out of a difference in the <i>stations</i> of species; but besides
+these, there are variations in the fossils of the higher, middle, and lower
+part of the oolitic series, which must be ascribed to that great law of
+change in organic life by which distinct assemblages of species have been
+adapted, at successive geological periods, to the varying conditions of the
+habitable surface. In a single district it is difficult to decide how far
+the limitation of species to certain minor <span class="pagenum"><a id="page266"></a>[p.266]</span>formations has been
+due to the local influence of <i>stations</i>, or how far it has been caused by
+time or the creative and destroying law above alluded to. But we recognize
+the reality of the last-mentioned influence, when we contrast the whole
+oolitic series of England with that of parts of the Jura, Alps, and other
+distant regions, where there is scarcely any lithological resemblance; and
+yet some of the same fossils remain peculiar in each country to the Upper,
+Middle, and Lower Oolite formations respectively. Mr. Thurmann has shown
+how remarkably this fact holds true in the Bernese Jura, although the
+argillaceous divisions, so conspicuous in England, are feebly represented
+there, and some entirely wanting.</p>
+
+<a id="img270" name="img270"></a>
+<div class="floatleft width150 smaller">
+<p>Fig. 283.</p>
+<img src="images/img270.jpg" width="150" height="130" alt="" title="">
+<p><i>Terebratula digona.</i> Bradford <span class="wosp05">clay. Nat.</span> size.</p></div>
+
+<p>The Bradford clay above alluded to is sometimes 60 feet thick, but, in many
+places, it is wanting; and, in others, where there are no limestones, it
+cannot easily be separated from the clays of the overlying "forest marble"
+and underlying "fuller's earth."</p>
+
+<p>The calcareous portion of the Great Oolite consists of several shelly
+limestones, one of which, called the Bath Oolite, is much celebrated as a
+building stone. In parts of Gloucestershire, especially near
+Minchinhampton, the Great Oolite, says Mr. Lycett, "must have been
+deposited in a shallow sea, where strong currents prevailed, for there are
+frequent changes in the mineral character of the deposit, and some beds
+exhibit false stratification. In others, heaps of broken shells are mingled
+with pebbles of rocks foreign to the neighbourhood, and with fragments of
+abraded madrepores, dicotyledonous wood, and crabs' claws. The shelly
+strata, also, have occasionally suffered denudation, and the removed
+portions have been replaced by clay."<a name="FNanchor_V_7" id="FNanchor_V_7"></a><a href="#Footnote_V_7" class="fnanchor">[266-A]</a> In such shallow-water beds
+cephalopoda are rare, and, instead of ammonites and belemnites, numerous
+genera of carnivorous trachelipods appear. Out of one hundred and forty-two
+species of univalves obtained from the Minchinhampton beds, Mr. Lycett
+found no less than forty-one to be carnivorous. They belong principally to
+the genera <i>Buccinum</i>, <i>Pleurotoma</i>, <i>Rostellaria</i>, <i>Murex</i>, and <i>Fusus</i>,
+and exhibit a proportion of zoophagous species not very different from that
+which obtains in warm seas of the recent period. These conchological
+results are curious and unexpected, since it was imagined that we might
+look in vain for the carnivorous trachelipods in rocks of such high
+antiquity as the Great Oolite, and it was a received doctrine that they did
+not begin to appear in considerable numbers till the Eocene period when
+those two great families of cephalopoda, the ammonites and belemnites, had
+become extinct.</p>
+
+<p><i>Stonesfield slate.</i>&mdash;The slate of Stonesfield has been shown by Mr.
+Lonsdale to lie at the base of the Great Oolite.<a name="FNanchor_V_8" id="FNanchor_V_8"></a><a href="#Footnote_V_8" class="fnanchor">[266-B]</a> It is a slightly
+<span class="pagenum"><a id="page267"></a>[p.267]</span>oolitic shelly limestone, forming large spheroidal masses
+imbedded in sand, only 6 feet thick, but very rich in organic remains. It
+contains some pebbles of a rock very similar to itself, and which may be
+portions of the deposit, broken up on a shore at low water or during
+storms, and redeposited. The remains of belemnites, trigoni�, and other
+marine shells, with fragments of wood, are common, and impressions of
+ferns, cycade�, and other plants. Several insects, also, and, among the
+rest, the wing-covers of beetles, are perfectly preserved (see <a href="#img271">fig. 284.</a>),
+some of them approaching nearly to the genus <i>Buprestis</i>.<a name="FNanchor_V_9" id="FNanchor_V_9"></a><a href="#Footnote_V_9" class="fnanchor">[267-A]</a> The
+remains, also, of many genera of reptiles, such as <i>Plesiosaur</i>,
+<i>Crocodile</i>, and <i>Pterodactyl</i>, have been discovered in the same limestone.</p>
+
+<a id="img271" name="img271"></a>
+<div class="figcenter smaller width100">
+<p>Fig. 284.</p>
+<img src="images/img271.jpg" width="100" height="273" alt="" title="">
+<p>Elytron of <i>Buprestis</i>? Stonesfield.</p></div>
+
+<a id="img272" name="img272"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 285.</p>
+<img src="images/img272.jpg" width="400" height="205" alt="" title="">
+<p>Bone of a reptile, formerly supposed to be the
+ulna of a Cetacean; from the Great Oolite of Enstone, near Woodstock.</p></div>
+
+<p>But the remarkable fossils for which the Stonesfield slate is most
+celebrated, are those referred to the mammiferous class. The student should
+be reminded that in all the rocks described in the preceding chapters as
+older than the Eocene, no bones of any land quadruped, or of any cetacean,
+have been discovered. Yet we have seen that terrestrial plants were not
+rare in the lower cretaceous formation, and that in the Wealden there was
+evidence of freshwater sediment on a large scale, containing various
+plants, and even ancient vegetable soils with the roots and erect stumps of
+trees. We had also in the same Wealden many land-reptiles and
+winged-insects, which renders the absence of terrestrial quadrupeds the
+more striking. The want, however, of any bones of whales, seals, dolphins,
+and other aquatic mammalia, whether in the chalk or in the upper or middle
+oolite, is certainly still more remarkable. Formerly, indeed, a bone from
+the great oolite of Enstone, near Woodstock, in Oxfordshire, was cited, on
+the authority of Cuvier, as referable to this class. Dr. Buckland, who
+stated this in his Bridgewater Treatise<a name="FNanchor_V_10" id="FNanchor_V_10"></a><a href="#Footnote_V_10" class="fnanchor">[267-B]</a>, had the kindness to send me
+the supposed ulna of a whale, that Mr. Owen might examine into its claims
+to be considered as cetaceous. It is <span class="pagenum"><a id="page268"></a>[p.268]</span>the opinion of that eminent
+comparative anatomist that it cannot have belonged to the cetacea, because
+the fore-arm in these marine mammalia is invariably much flatter, and
+devoid of all muscular depressions and ridges, one of which is so prominent
+in the middle of this bone, represented in the above cut (<a href="#img272">fig. 285.</a>). In
+saurians, on the contrary, such ridges exist for the attachment of muscles;
+and to some animal of that class the bone is probably referable.</p>
+
+<a id="img273" name="img273"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 286.</p>
+<img src="images/img273.jpg" width="450" height="161" alt="" title="">
+<p><i>Amphitherium Prevostii</i><span class="wosp05">. Stonesfield</span> Slate.</p>
+<ul class="smaller martopm05 leftal add1em min1em">
+<li><i>a</i>. coronoid process.</li>
+<li><i>b</i>. condyle.</li>
+<li><i>c</i>. angle of jaw.</li>
+<li><i>d</i>. double-fanged molars.</li>
+</ul></div>
+
+<p>These observations are made to prepare the reader to appreciate more justly
+the interest felt by every geologist in the discovery in the Stonesfield
+slate of no less than seven specimens of lower jaws of mammiferous
+quadrupeds, belonging to three different species and to two distinct
+genera, for which the names of <i>Amphitherium</i> and <i>Phascolotherium</i> have
+been adopted. When Cuvier was first shown one of these fossils in 1818, he
+pronounced it to belong to a small ferine mammal, with a jaw much
+resembling that of an opossum, but differing from all known ferine genera,
+in the great number of the molar teeth, of which it had at least ten in a
+row. Since that period, a much more perfect specimen of the same fossil,
+obtained by Dr. Buckland (see <a href="#img273">fig. 286.</a>), has been examined by Mr. Owen,
+who finds that the jaw contained on the whole twelve molar teeth, with the
+socket of a small canine, and three small incisors, which are <i>in situ</i>,
+altogether amounting to sixteen teeth on each side of the lower jaw.</p>
+
+<a id="img274" name="img274"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 287.</p>
+<img src="images/img274.jpg" width="200" height="074" alt="" title="">
+<p><i>Amphitherium Broderipii</i>. Natural <span class="wosp05">size.
+Stonesfield</span> Slate.</p></div>
+
+<p>The only question which could be raised respecting the nature of these
+fossils was, whether they belonged to a mammifer, a reptile, or a fish. Now
+on this head the osteologist observes that each of the seven half jaws is
+composed of but one single piece, and not of two or more separate bones, as
+in fishes and most reptiles, or of two bones, united by a suture, as in
+some few species belonging to those classes. The condyle, moreover (<i>b</i>,
+<a href="#img273">fig. 286.</a>), or articular surface, by which the lower jaw unites with the
+upper, is convex in the Stonesfield specimens, and not concave as in fishes
+and reptiles. The coronoid process (<i>a</i>, <a href="#img273">fig. 286.</a>) is well developed,
+whereas it is wanting or very small, in the inferior classes of vertebrata.
+Lastly, the molar teeth in the <i>Amphitherium</i> and <i>Phascolotherium</i>
+<span class="pagenum"><a id="page269"></a>[p.269]</span>have complicated crowns, and two roots (see <i>d</i>, <a href="#img273">fig. 286.</a>),
+instead of being simple and with single fangs.<a name="FNanchor_V_11" id="FNanchor_V_11"></a><a href="#Footnote_V_11" class="fnanchor">[269-A]</a></p>
+
+<a id="img275" name="img275"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 288.</p>
+<img src="images/img275.jpg" width="300" height="091" alt="" title="">
+<p><i>Tupaia Tana.</i> Right ramus of lower jaw, natural
+size. A recent insectivorous mammal from Sumatra.</p></div>
+
+<a id="img276" name="img276"></a>
+<div class="figcenter smaller width300">
+<img src="images/img276.jpg" width="300" height="252" alt="" title="">
+<p>Part of lower jaw of <i>Tupaia Tana</i>; twice natural size.</p>
+<p>Fig. 289. End view seen from behind, showing the very slight inflection
+of the angle at <i>c</i>.</p>
+<p class="martopm05">Fig. 290. Side view of same.</p></div>
+
+<a id="img277" name="img277"></a>
+<div class="figcenter smaller width300">
+<img src="images/img277.jpg" width="300" height="230" alt="" title="">
+<p>Part of lower jaw of <i>Didelphis Azar�</i>; recent, <span class="wosp05">Brazil.
+Natural</span> size.</p>
+<p>Fig. 291. End view seen from behind, showing the inflection of the angle
+of the jaw, <i>c. d.</i></p>
+<p class="martopm05">Fig. 292. Side view of same.</p></div>
+
+<p>The only question, therefore, which could fairly admit of controversy was
+limited to this point, whether the fossil mammalia found in the lower
+oolite of Oxfordshire ought to be referred to the marsupial quadrupeds, or
+to the ordinary placental series. Cuvier had long ago pointed out a
+peculiarity in the form of the angular process (<i>c</i>, <a href="#img277">figs. 291.</a> and <a href="#img277">292.</a>)
+of the lower jaw, as a character of the genus <i>Didelphys</i>; and Mr. Owen has
+since established its generality in the entire marsupial series. In all
+these pouched quadrupeds, this process is turned inwards, as at <i>c d</i>, <a href="#img277">fig.
+291.</a> in the Brazilian opossum, whereas in the placental series, as at <i>c</i>,
+<a href="#img276">figs. 290.</a> and <a href="#img276">289.</a> there is an almost entire absence of such inflection.
+The <i>Tupaia Tana</i> of Sumatra has been selected by my friend Mr. Waterhouse,
+for this illustration, because that small insectivorous quadruped bears a
+great resemblance to those of the Stonesfield <i>Amphitherium</i>. By clearing
+away the matrix from the specimen of <i>Amphitherium Prevostii</i> above
+represented (<a href="#img273">fig. 286.</a>), Mr. Owen ascertained that the angular process
+(<i>c</i>) bent inwards in a slighter degree than in any of the known
+marsupialia; in short, the inflection does not exceed that of the mole or
+hedgehog. This fact turns the scale in favour of its affinities to the
+placental insectivora. Nevertheless, the <i>Amphitherium</i> offers some points
+of approximation in its osteology to the marsupials, especially to the
+<i>Myrmecobius</i>, a small insectivorous quadruped of Australia, which has nine
+molars on each side of the lower jaw, besides a canine and three
+incisors.<a name="FNanchor_V_12" id="FNanchor_V_12"></a><a href="#Footnote_V_12" class="fnanchor">[269-B]</a></p>
+
+<p><span class="pagenum"><a id="page270"></a>[p.270]</span>Another species of <i>Amphitherium</i> has been found at Stonesfield
+(<a href="#img274">fig. 287.</a> <a href="#page268">p. 268.</a>), which differs from the former (<a href="#img273">fig. 286.</a>) principally
+in being larger.</p>
+
+<a id="img278" name="img278"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 293.</p>
+<img src="images/img278.jpg" width="350" height="104" alt="" title="">
+<p><i>Phascolotherium Bucklandi</i>, Owen.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> natural size.</li>
+<li><i>b.</i> molar of same magnified.</li>
+</ul></div>
+
+<p>The second mammiferous genus discovered in the same slates was named
+originally by Mr. Broderip <i>Didelphys Bucklandi</i> (see <a href="#img278">fig. 293.</a>), and has
+since been called <i>Phascolotherium</i> by Owen. It manifests a much stronger
+likeness to the marsupials in the general form of the jaw, and in the
+extent and position of its inflected angle, while the agreement with the
+living genus <i>Didelphys</i> in the number of the premolar and molar teeth, is
+complete.<a name="FNanchor_V_13" id="FNanchor_V_13"></a><a href="#Footnote_V_13" class="fnanchor">[270-A]</a></p>
+
+<p>On reviewing, therefore, the whole of the osteological evidence, it will be
+seen that we have every reason to presume that the <i>Amphitherium</i> and
+<i>Phascolotherium</i> of Stonesfield represent both the placental and marsupial
+classes of mammalia; and if so, they warn us in a most emphatic manner, not
+to found rash generalizations respecting the non-existence of certain
+classes of animals at particular periods of the past, on mere negative
+evidence. The singular accident of our having as yet found nothing but the
+lower jaws of seven individuals, and no other bones of their skeletons, is
+alone sufficient to demonstrate the fragmentary manner in which the
+memorials of an ancient terrestrial fauna are handed down to us. We can
+scarcely avoid suspecting that the two genera above described, may have
+borne a like insignificant proportion to the entire assemblage of
+warm-blooded quadrupeds which flourished in the islands of the oolitic sea.</p>
+
+<p>Mr. Owen has remarked that as the marsupial genera, to which the
+<i>Phascolotherium</i> is most nearly allied, are now confined to New South
+Wales and Van Diemen's Land, so also is it in the Australian seas, that we
+find the <i>Cestracion</i>, a cartilaginous fish which has a bony palate, allied
+to those called <i>Acrodus</i> and <i>Psammodus</i> (see <a href="#img292">figs. 307</a>, <a href="#img293">308.</a> <a href="#page275">p. 275.</a>), so
+common in the oolite and lias. In the same Australian seas, also, near the
+shore, we find the living <i>Trigonia</i>, a genus of mollusca so frequently met
+with in the Stonesfield slate. So, also, the Araucarian pines are now
+abundant, together with ferns, in Australia and its islands, as they were
+in Europe in the oolitic period. Many botanists incline to the opinion,
+that the <i>Thuja</i>, <i>Pine</i>, <i>Cycas</i>, <i>Zamia</i>, in short, all the gymnogens,
+belong to a less highly developed type of flowering plants than do the
+exogens; but even if this be admitted, no naturalist can ascribe a low
+standard of organization to the oolitic flora, since we meet with endogens
+of the most perfect structure <span class="pagenum"><a id="page271"></a>[p.271]</span>in oolitic rocks, both above and
+below the Stonesfield slate, as, for example, the <i>Podocarya</i> of Buckland,
+a fruit allied to the <i>Pandanus</i>, found in the Inferior Oolite (see <a href="#img279">fig.
+294.</a>), and the <i>Carpolithes conica</i> of the Coral rag. The doctrine,
+therefore, of a regular series of progressive development at successive
+eras in the animal and vegetable kingdoms, from beings of a more simple to
+those of a more complex organization, receives a check, if not a
+refutation, from the facts revealed to us by the study of the Lower
+Oolites.</p>
+
+<a id="img279" name="img279"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 294.</p>
+<img src="images/img279.jpg" width="200" height="173" alt="" title="">
+<p>Portion of a fossil fruit of <i>Podocarya</i> magnified. (Buckland's
+Bridgew. Treat. Pl. 63.) Inferior Oolite, Charmouth, Dorset.</p></div>
+
+<p>The Stonesfield slate, in its range from Oxfordshire to the north-east, is
+represented by flaggy and fissile sandstones, as at Collyweston in
+Northamptonshire, where, according to the researches of Messrs. Ibbetson
+and Morris, it contains many shells, such as <i>Trigonia angulata</i>, also
+found at Stonesfield. But the Northamptonshire strata of this age assume a
+more marine character, or appear at least to have been formed farther from
+land. They inclose, however, some fossil ferns, such as <i>Pecopteris
+polypodioides</i>, of species common to the oolites of the Yorkshire
+coast<a name="FNanchor_V_14" id="FNanchor_V_14"></a><a href="#Footnote_V_14" class="fnanchor">[271-A]</a>, where rocks of this age put on all the aspect of a true
+coal-field; thin seams of coal having actually been worked in them for more
+than a century.</p>
+
+<a id="img280" name="img280"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 295.</p>
+<img src="images/img280.jpg" width="350" height="222" alt="" title="">
+<p><i>Pterophyllum comptum</i><span class="wosp05">. (Syn.</span> <i>Cycadites
+comptus</i><span class="wosp05">.) Upper</span> sandstone and shale, Gristhorpe, near Scarborough.</p></div>
+
+<p>In the north-west of Yorkshire, the formation alluded to consists of an
+upper and a lower carbonaceous shale, abounding in impressions of plants,
+divided by a limestone considered by many geologists as the representative
+of the Great Oolite; but the scarcity of marine fossils makes all
+comparisons with the subdivisions adopted in the south extremely difficult.
+A rich harvest of fossil ferns has been obtained from the upper
+carbonaceous shales and sandstones at Gristhorpe, near Scarborough (see
+<a href="#img280">figs. 295</a>, <a href="#img281">296.</a>). The lower shales are well exposed in the sea-cliffs at
+Whitby, and are chiefly characterized <span class="pagenum"><a id="page272"></a>[p.272]</span>by ferns and cycade�. They
+contain, also, a species of calamite, and a fossil called <i>Equisetum
+columnare</i>, which maintains an upright position in sandstone strata over a
+wide area. Shells of the genus <i>Cypris</i> and <i>Unio</i>, collected by Mr. Bean
+from these Yorkshire coal-bearing beds, point to the estuary or fluviatile
+origin of the deposit.</p>
+
+<a id="img281" name="img281"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 296.</p>
+<img src="images/img281.jpg" width="350" height="174" alt="" title="">
+<p><i>Hemitelites Brownii</i>, Goepp. Syn. <i>Phlebopteris contigua</i>,
+Lind. &amp; Hutt. Upper carbonaceous strata, Lower Oolite,
+Gristhorpe, Yorkshire.</p></div>
+
+<p>At Brora, in Sutherlandshire, a coal formation, probably coeval with the
+above, or belonging to some of the lower divisions of the Oolitic period,
+has been mined extensively for a century or more. It affords the thickest
+stratum of pure vegetable matter hitherto detected in any secondary rock in
+England. One seam of coal of good quality has been worked 3<span class="smaller"><sup>1</sup>/<sub>2</sub></span> feet thick,
+and there are several feet more of pyritous coal resting upon it.</p>
+
+<p><i>Inferior Oolite.</i>&mdash;Between the Great and Inferior Oolite, near Bath, an
+argillaceous deposit called "the fuller's earth," occurs, but is wanting in
+the north of England. The Inferior Oolite is a calcareous freestone,
+usually of small thickness, which sometimes rests upon, or is replaced by,
+yellow sands, called the sands of the Inferior Oolite. These last, in their
+turn, repose upon the lias in the south and west of England.</p>
+
+<p>Among the characteristic shells of the Inferior Oolite, I may instance
+<i>Terebratula spinosa</i> (<a href="#img282">fig. 297.</a>), and <i>Pholadomya fidicula</i> (<a href="#img283">fig. 298.</a>).
+The extinct genus <i>Pleurotomaria</i> is also a form very common in this
+division as well as in the Oolitic system generally. It resembles the
+<i>Trochus</i> in form, but is marked by a singular cleft (<i>a</i>, <a href="#img284">fig. 299.</a>) on
+the right side of the mouth.</p>
+
+<a id="img282" name="img282"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 297.</p>
+<img src="images/img282.jpg" width="150" height="130" alt="" title="">
+<p><i>Terebratula spinosa.</i> Inferior Oolite.</p></div>
+
+<a id="img283" name="img283"></a>
+<div class="floatright smaller width300">
+<p>Fig. 298.</p>
+<img src="images/img283.jpg" width="300" height="138" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Pholadomya fidicula</i>, <sup>1</sup>/<sub>3</sub> nat. size. Inf. Ool.</li>
+<li><i>b.</i> Heart-shaped anterior termination of the same.</li>
+</ul></div>
+
+<a id="img284" name="img284"></a>
+<div class="nofloat figcenter smaller width150">
+<p>Fig. 299.</p>
+<img src="images/img284.jpg" width="150" height="144" alt="" title="">
+<p><i>Pleurotomaria ornata.</i> Ferruginous Oolite,
+<span class="wosp05">Normandy. Inferior</span> Oolite, England.</p></div>
+
+<p>As illustrations of shells having a great vertical range, I may <span class="pagenum"><a id="page273"></a>[p.273]</span>
+allude to <i>Trigonia clavellata</i>, found in the Upper and Inferior Oolite,
+and <i>T. costata</i>, common to the Upper, Middle, and Lower Oolite; also
+<i>Ostrea Marshii</i> (<a href="#img285">fig. 300.</a>), common to the Cornbrash of Wilts and the
+Inferior Oolite of Yorkshire; and <i>Ammonites striatulus</i> (<a href="#img286">fig. 301.</a>) common
+to the Inferior Oolite and Lias.</p>
+
+<a id="img285" name="img285"></a>
+<div class="floatleft smaller width300">
+<p>Fig. 300.</p>
+<img src="images/img285.jpg" width="300" height="193" alt="" title="">
+<p><i>Ostrea Marshii.</i> <sup>1</sup>/<sub>2</sub> nat. size. Middle and
+Lower Oolite.</p></div>
+
+<a id="img286" name="img286"></a>
+<div class="floatright smaller width200">
+<p>Fig. 301.</p>
+<img src="images/img286.jpg" width="200" height="180" alt="" title="">
+<p><i>Ammonites striatulus</i>, Sow. <sup>1</sup>/<sub>3</sub> nat. size.
+Inferior Oolite and Lias.</p></div>
+
+<p class="nofloat">Such facts by no means invalidate the general rule, that certain fossils
+are good chronological tests of geological periods; but they serve to
+caution us against attaching too much importance to single species, some of
+which may have a wider, others a more confined vertical range. We have
+before seen that, in the successive tertiary formations, there are species
+common to older and newer groups, yet these groups are distinguishable from
+one another by a comparison of the whole assemblage of fossil shells proper
+to each.</p>
+
+
+
+
+<hr class="sep2">
+<h2><a id="chaxxi" name="chaxxi">CHAPTER XXI</a>.</h2>
+
+<h4>OOLITE AND LIAS&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Mineral character of Lias &mdash; Name of Gryphite limestone &mdash; Fossil
+shells and fish &mdash; Ichthyodorulites &mdash; Reptiles of the
+Lias &mdash; Ichthyosaur and Plesiosaur &mdash; Marine Reptile of the Galapagos
+Islands &mdash; Sudden destruction and burial of fossil animals in
+Lias &mdash; Fluvio-marine beds in Gloucestershire and insect
+limestone &mdash; Origin of the Oolite and Lias, and of alternating
+calcareous and argillaceous formations &mdash; Oolitic coal-field of
+Virginia, in the United States.</p></div>
+
+
+<p><span class="smcap"><i>Lias.</i></span>&mdash;The English provincial name of Lias has been very generally
+adopted for a formation of argillaceous limestone, marl, and clay, which
+forms the base of the Oolite, and is classed by many geologists as part of
+that group. They pass, indeed, into each other in some places, as near
+Bath, a sandy marl called the marlstone of the Lias being interposed, and
+partaking of the mineral characters of the upper lias and inferior oolite.
+These last-mentioned divisions have also some fossils in common, such as
+the <i>Avicula in�quivalvis</i> (<a href="#img287">fig. 302.</a>). Nevertheless the Lias may be traced
+throughout a great part of Europe as a separate and independent group, of
+considerable <span class="pagenum"><a id="page274"></a>[p.274]</span>thickness, varying from 500 to 1000 feet, containing
+many peculiar fossils, and having a very uniform lithological aspect.
+Although usually conformable to the oolite, it is sometimes, as in the
+Jura, unconformable. In the environs of Lons-le-Saulnier, for instance, in
+the department of Jura, the strata of lias are inclined at an angle of
+about 45�, while the incumbent oolitic marls are horizontal.</p>
+
+<a id="img287" name="img287"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 302.</p>
+<img src="images/img287.jpg" width="150" height="119" alt="" title="">
+<p><i>Avicula in�quivalvis</i>, Sow.</p></div>
+
+<p>The peculiar aspect which is most characteristic of the Lias in England,
+France, and Germany, is an alternation of thin beds of blue or grey
+limestone with a surface becoming light-brown when weathered, these beds
+being separated by dark-coloured narrow argillaceous partings, so that the
+quarries of this rock, at a distance, assume a striped and riband-like
+appearance.<a name="FNanchor_W_1" id="FNanchor_W_1"></a><a href="#Footnote_W_1" class="fnanchor">[274-A]</a></p>
+
+<p>Although the prevailing colour of the limestone of this formation is blue,
+yet some beds of the lower lias are of a yellowish white colour, and have
+been called white lias. In some parts of France, near the Vosges mountains,
+and in Luxembourg, M. E. de Beaumont has shown that the lias containing
+<i>Gryph�a arcuata</i>, <i>Plagiostoma giganteum</i> (see <a href="#img288">fig. 303.</a>), and other
+characteristic fossils, becomes arenaceous; and around the Hartz, in
+Westphalia and Bavaria, the inferior parts of the lias are sandy, and
+sometimes afford a building stone.</p>
+
+<a id="img288" name="img288"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 303.</p>
+<img src="images/img288.jpg" width="350" height="282" alt="" title="">
+<p><i>Plagiostoma giganteum</i><span class="wosp05">. Lias.</span></p></div>
+
+<a id="img289" name="img289"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 304.</p>
+<img src="images/img289.jpg" width="200" height="138" alt="" title="">
+<p><i>Gryph�a incurva</i>, Sow. (<i>G. arcuata</i>, Lam.)</p></div>
+
+<a id="img290" name="img290"></a>
+<div class="floatright smaller width300">
+<p>Fig. 305.</p>
+<img src="images/img290.jpg" width="300" height="156" alt="" title="">
+<p><i>Nautilus truncatus</i><span class="wosp05">. Lias.</span></p></div>
+
+<p class="nofloat">The name of Gryphite limestone has sometimes been applied to the lias, in
+consequence of the great number of shells which it contains of a species of
+oyster, or <i>Gryph�a</i> (<a href="#img289">fig. 304.</a>, see also <a href="#img035">fig. 30.</a> <a href="#page29">p. 29.</a>). Many
+cephalopoda, also, such as <i>Ammonite</i>, <i>Belemnite</i>, and <i>Nautilus</i> (<a href="#img290">fig.
+305.</a>), prove the marine origin of the formation.</p>
+
+<span class="pagenum"><a id="page275"></a>[p.275]</span>
+<a id="img291" name="img291"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 306.</p>
+<img src="images/img291.jpg" width="400" height="194" alt="" title="">
+<p>Scales of <i>Lepidotus gigas</i><span class="wosp05">, Agas.</span></p>
+<p class="martopm05"><i>a.</i> two of the scales detached.</p></div>
+
+<p>The fossil fish resemble generically those of the oolite, belonging all,
+according to M. Agassiz, to extinct genera, and differing remarkably from
+the ichthyolites of the Cretaceous period. Among them is a species of
+<i>Lepidotus</i> (<i>L. gigas</i>, Agas.) (<a href="#img291">fig. 306.</a>), which is found in the lias of
+England, France, and Germany.<a name="FNanchor_W_2" id="FNanchor_W_2"></a><a href="#Footnote_W_2" class="fnanchor">[275-A]</a> This genus was before mentioned (<a href="#page229">p.
+229.</a>) as occurring in the Wealden, and is supposed to have frequented both
+rivers and coasts. The teeth of a species of <i>Acrodus</i>, also, are very
+abundant in the lias (<a href="#img292">fig. 307.</a>).</p>
+
+<a id="img292" name="img292"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 307.</p>
+<img src="images/img292.jpg" width="400" height="115" alt="" title="">
+<p><i>Acrodus nobilis</i>, Agas. (tooth); commonly called fossil leach.
+Lias, Lyme Regis, and Germany.</p></div>
+
+<a id="img293" name="img293"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 308.</p>
+<img src="images/img293.jpg" width="450" height="150" alt="" title="">
+<p><i>Hybodus reticulatus</i>, <span class="wosp05">Agas. Lias,</span> Lyme Regis.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Part of fin, commonly called Ichthyodorulite.</li>
+<li><i>b.</i> Tooth.</li>
+</ul></div>
+
+<p>But the remains of fish which have excited more attention than any others,
+are those large bony spines called <i>ichthyodorulites</i> (<i>a</i>, <a href="#img293">fig. 308.</a>),
+which were once supposed by some naturalists to be jaws, and by others
+weapons, resembling those of the living <i>Balistes</i> and <i>Silurus</i>; but which
+M. Agassiz has shown to be neither the one nor the other. The spines, in
+the genera last mentioned, articulate with the backbone, whereas there are
+no signs of any such articulation <span class="pagenum"><a id="page276"></a>[p.276]</span>in the ichthyodorulites. These
+last appear to have been bony spines which formed the anterior part of the
+dorsal fin, like that of the living genera <i>Cestracion</i> and <i>Chim�ra</i> (see
+<i>a</i>, <a href="#img294">fig. 309.</a>). In both of these genera, the posterior concave face is
+armed with small spines like that of the fossil <i>Hybodus</i> <a href="#img293">(fig. 308.</a>), one
+of the shark family found fossil at Lyme Regis. Such spines are simply
+imbedded in the flesh, and attached to strong muscles. "They serve," says
+Dr. Buckland, "as in the <i>Chim�ra</i> (<a href="#img294">fig. 309.</a>), to raise and depress the
+fin, their action resembling that of a moveable mast, raising and lowering
+backwards the sail of a barge."<a name="FNanchor_W_3" id="FNanchor_W_3"></a><a href="#Footnote_W_3" class="fnanchor">[276-A]</a></p>
+
+<a id="img294" name="img294"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 309.</p>
+<img src="images/img294.jpg" width="350" height="193" alt="" title="">
+<p><i>Chim�ra monstrosa.</i><a name="FNanchor_W_4" id="FNanchor_W_4"></a><a href="#Footnote_W_4" class="fnanchor">[276-B]</a></p>
+<p><i>a.</i> Spine forming anterior part of the dorsal fin.</p></div>
+
+<p><i>Reptiles of the Lias.</i>&mdash;It is not, however, the fossil fish which form the
+most striking feature in the organic remains of the Lias; but the reptiles,
+which are extraordinary for their number, size, and structure. Among the
+most singular of these are several species of <i>Ichthyosaurus</i> and
+<i>Plesiosaurus</i>. The genus <i>Ichthyosaurus</i>, or fish-lizard, is not confined
+to this formation, but has been found in strata as high as the chalk-marl
+and gault of England, and as low as the muschelkalk of Germany, a formation
+which immediately succeeds the lias in the descending order.<a name="FNanchor_W_5" id="FNanchor_W_5"></a><a href="#Footnote_W_5" class="fnanchor">[276-C]</a> It is
+evident from their fish-like vertebr�, their paddles, resembling those of a
+porpoise or whale, the length of their tail, and other parts of their
+structure, that the habits of the Ichthyosaurs were aquatic. Their jaws and
+teeth show that they were carnivorous; and the half-digested remains of
+fishes and reptiles, found within their skeletons, indicate the precise
+nature of their food.<a name="FNanchor_W_6" id="FNanchor_W_6"></a><a href="#Footnote_W_6" class="fnanchor">[276-D]</a></p>
+
+<p>A specimen of the hinder fin or paddle of <i>Ichthyosaurus communis</i> was
+discovered in 1840 at Barrow-on-Soar, by Sir P. Egerton, which distinctly
+exhibits on its posterior margin the remains of cartilaginous rays that
+bifurcate as they approach the edge, like those in the fin of a fish (see
+<i>a</i>, <a href="#img297">fig. 312.</a>). It had previously been supposed, says Mr. Owen, that the
+locomotive organs of the Ichthyosaurus were enveloped, while living, in a
+smooth integument, like that of the turtle and porpoise, which has no other
+support than is afforded by the bones and ligaments within; but it now
+appears that the fin was <span class="pagenum"><a id="page277"></a>[p.277]</span>much larger, expanding far beyond its
+osseous framework, and deviating widely in its fish-like rays from the
+ordinary reptilian type. In <a href="#img297">fig. 312.</a> the posterior bones, or digital
+ossicles of the paddle, are seen near <i>b</i>; and beyond these is the dark
+carbonized integument of the terminal half of the fin, the outline of which
+is beautifully defined.<a name="FNanchor_W_7" id="FNanchor_W_7"></a><a href="#Footnote_W_7" class="fnanchor">[277-A]</a> Mr. Owen believes that, besides the
+fore-paddles, these short-and stiff-necked saurians were furnished with a
+tail-fin without bones and purely tegumentary, expanding in a vertical
+direction; an organ of motion which enabled them to turn their heads
+rapidly.<a name="FNanchor_W_8" id="FNanchor_W_8"></a><a href="#Footnote_W_8" class="fnanchor">[277-B]</a></p>
+
+<a id="img295" name="img295"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 310.</p>
+<img src="images/img295.jpg" width="500" height="111" alt="" title="">
+<p><i>Ichthyosaurus communis</i>, restored by Conybeare and Cuvier.</p>
+<p class="martopm05"><i>a.</i> costal vertebr�.</p></div>
+
+<a id="img296" name="img296"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 311.</p>
+<img src="images/img296.jpg" width="500" height="116" alt="" title="">
+<p><i>Plesiosaurus dolichodeirus</i>, restored by Rev. W. D. Conybeare.</p>
+<p class="martopm05"><i>a.</i> cervical vertebra.</p></div>
+
+<span class="pagenum"><a id="page278"></a>[p.278]</span>
+<a id="img297" name="img297"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 312.</p>
+<img src="images/img297.jpg" width="450" height="275" alt="" title="">
+<p>Posterior part of hind fin or paddle of <i>Ichthyosaurus communis</i>.</p></div>
+
+<p>Mr. Conybeare was enabled, in 1824, after examining many skeletons nearly
+perfect, to give an ideal restoration of the osteology of this genus, and
+of that of the <i>Plesiosaurus</i>.<a name="FNanchor_W_9" id="FNanchor_W_9"></a><a href="#Footnote_W_9" class="fnanchor">[278-A]</a> (See <a href="#img295">figs. 310</a>, <a href="#img296">311.</a>) The latter
+animal had an extremely long neck and small head, with teeth like those of
+the crocodile, and paddles analogous to those of the <i>Ichthyosaurus</i>, but
+larger. It is supposed to have lived in shallow seas and estuaries, and to
+have breathed air like the Ichthyosaur, and our modern cetacea.<a name="FNanchor_W_10" id="FNanchor_W_10"></a><a href="#Footnote_W_10" class="fnanchor">[278-B]</a> Some
+of the reptiles above mentioned were of formidable dimensions. One specimen
+of <i>Ichthyosaurus platyodon</i>, from the lias at Lyme, now in the British
+Museum, must have belonged to an animal more than 24 feet in length; and
+another of the <i>Plesiosaurus</i>, in the same collection, is 11 feet long. The
+form of the <i>Ichthyosaurus</i> may have fitted it to cut through the waves
+like the porpoise; but it is supposed that the <i>Plesiosaurus</i>, at least the
+long-necked species (<a href="#img296">fig. 311.</a>), was better suited to fish in shallow
+creeks and bays defended from heavy breakers.</p>
+
+<p>In many specimens both of Ichthyosaur and Plesiosaur the bones of the head,
+neck, and tail, are in their natural position, while those of the rest of
+the skeleton are detached and in confusion. Mr. Stutchburg has suggested
+that their bodies after death became inflated with gases, and, while the
+abdominal viscera were decomposing, the bones, though disunited, were
+retained within the tough dermal covering as in a bag, until the whole,
+becoming water-logged, sank to the bottom.<a name="FNanchor_W_11" id="FNanchor_W_11"></a><a href="#Footnote_W_11" class="fnanchor">[278-C]</a> As they belonged to
+individuals of all ages they are supposed, by Dr. Buckland, to have
+experienced a violent death; and the same conclusion might also be drawn
+from their having escaped the attacks of their own predaceous race, or of
+fishes, found fossil in the same beds.</p>
+
+<a id="img298" name="img298"></a>
+<div class="figcenter smaller width450">
+<p>Fig 313.</p>
+<img src="images/img298.jpg" width="450" height="225" alt="" title="">
+<p><i>Amblyrhynchus cristatus</i>, <span class="wosp05">Bell. Length</span> varying
+from 3 to 4 <span class="wosp05">feet. The</span> only existing marine lizard now known.</p>
+<p><i>a.</i> Tooth, natural size and magnified.</p></div>
+
+<p>For the last twenty years, anatomists have agreed that these extinct
+saurians must have inhabited the sea; and it was argued that, as there are
+now chelonians, like the tortoise, living in fresh water, <span class="pagenum"><a id="page279"></a>[p.279]</span>and
+others, as the turtle, frequenting the ocean, so there may have been
+formerly some saurians proper to salt, others to fresh water. The common
+crocodile of the Ganges is well known to frequent equally that river and
+the brackish and salt water near its mouth; and crocodiles are said in like
+manner to be abundant both in the rivers of the Isla de Pinos (or Isle of
+Pines), south of Cuba, and in the open sea round the coast. More recently a
+saurian has been discovered of aquatic habits and exclusively marine. This
+creature was found in the Galapagos Islands, during the visit of H. M. S.
+Beagle to that archipelago, in 1835, and its habits were then observed by
+Mr. Darwin. The islands alluded to are situated under the equator, nearly
+600 miles to the westward of the coast of South America. They are volcanic,
+some of them being 3000 or 4000 feet high; and one of them, Albemarle
+Island, 75 miles long. The climate is mild; very little rain falls; and, in
+the whole archipelago, there is only one rill of fresh water that reaches
+the coast. The soil is for the most part dry and harsh, and the vegetation
+scanty. The birds, reptiles, plants, and insects are, with very few
+exceptions, of species found no where else in the world, although all
+partake, in their general form, of a South American type. Of the mammalia,
+says Mr. Darwin, one species alone appears to be indigenous, namely, a
+large and peculiar kind of mouse; but the number of lizards, tortoises, and
+snakes is so great, that it may be called a land of reptiles. The variety,
+indeed, of species is small; but the individuals of each are in wonderful
+abundance. There is a turtle, a large tortoise (<i>Testudo Indicus</i>), four
+lizards, and about the same number of snakes, but no frogs or toads. Two of
+the lizards belong to the family <i>Iguanid�</i> of Bell, and to a peculiar
+genus (<i>Amblyrhynchus</i>) established by that naturalist, and so named from
+their obtusely truncated head and short snout.<a name="FNanchor_W_12" id="FNanchor_W_12"></a><a href="#Footnote_W_12" class="fnanchor">[279-A]</a> Of these lizards one
+is terrestrial in its habits, and burrows in the ground, swarming
+everywhere on the land, having a round tail, and a mouth somewhat
+resembling in form that of the tortoise. The other is aquatic, and has its
+tail flattened laterally for swimming (see <a href="#img298">fig. 313.</a>). "This marine
+saurian," says <span class="pagenum"><a id="page280"></a>[p.280]</span>Mr. Darwin, "is extremely common on all the
+islands throughout the archipelago. It lives exclusively on the rocky
+sea-beaches, and I never saw one even ten yards inshore. The usual length
+is about a yard, but there are some even 4 feet long. It is of a dirty
+black colour, sluggish in its movements on the land; but, when in the
+water, it swims with perfect ease and quickness by a serpentine movement of
+its body and flattened tail, the legs during this time being motionless,
+and closely collapsed on its sides. Their limbs and strong claws are
+admirably adapted for crawling over the rugged and fissured masses of lava
+which everywhere form the coast. In such situations, a group of six or
+seven of these hideous reptiles may oftentimes be seen on the black rocks,
+a few feet above the surf, basking in the sun with outstretched legs. Their
+stomachs, on being opened, were found to be largely distended with minced
+sea-weed, of a kind which grows at the bottom of the sea at some little
+distance from the coast. To obtain this, the lizards go out to sea in
+shoals. One of these animals was sunk in salt water, from the ship, with a
+heavy weight attached to it, and on being drawn up again after an hour it
+was quite active and unharmed. It is not yet known by the inhabitants where
+this animal lays its eggs; a singular fact, considering its abundance, and
+that the natives are well acquainted with the eggs of the terrestrial
+<i>Amblyrhynchus</i>, which is also herbivorous."<a name="FNanchor_W_13" id="FNanchor_W_13"></a><a href="#Footnote_W_13" class="fnanchor">[280-A]</a></p>
+
+<p>In those deposits now forming by the sediment washed away from the wasting
+shores of the Galapagos Islands the remains of saurians, both of the land
+and sea, as well as of chelonians and fish, may be mingled with marine
+shells, without any bones of land quadrupeds or batrachian reptiles; yet
+even here we should expect the remains of marine mammalia to be imbedded in
+the new strata, for there are seals, besides several kinds of cetacea, on
+the Galapagian shores; and, in this respect, the parallel between the
+modern fauna, above described, and the ancient one of the lias, would not
+hold good.</p>
+
+<p><i>Sudden destruction of saurians.</i>&mdash;It has been remarked, and truly, that
+many of the fish and saurians, found fossil in the lias, must have met with
+sudden death and immediate burial; and that the destructive operation,
+whatever may have been its nature, was often repeated.</p>
+
+<p>"Sometimes," says Dr. Buckland, "scarcely a single bone or scale has been
+removed from the place it occupied during life; which could not have
+happened had the uncovered bodies of these saurians been left, even for a
+few hours, exposed to putrefaction, and to the attacks of fishes, and other
+smaller animals at the bottom of the sea."<a name="FNanchor_W_14" id="FNanchor_W_14"></a><a href="#Footnote_W_14" class="fnanchor">[280-B]</a> Not only are the
+skeletons of the Ichthyosaurs entire, but sometimes the contents of their
+stomachs still remain between their ribs, as before remarked, so that we
+can discover the particular species of fish on which they lived, and the
+form of their excrements. Not unfrequently there are layers of these
+coprolites, at different depths in the <span class="pagenum"><a id="page281"></a>[p.281]</span>lias, at a distance from
+any entire skeletons of the marine lizards from which they were derived;
+"as if," says Sir H. De la Beche, "the muddy bottom of the sea received
+small sudden accessions of matter from time to time, covering up the
+coprolites and other exuvi� which had accumulated during the
+intervals."<a name="FNanchor_W_15" id="FNanchor_W_15"></a><a href="#Footnote_W_15" class="fnanchor">[281-A]</a> It is farther stated that, at Lyme Regis, those surfaces
+only of the coprolites which lay uppermost at the bottom of the sea have
+suffered partial decay, from the action of water before they were covered
+and protected by the muddy sediment that has afterwards permanently
+enveloped them.<a name="FNanchor_W_16" id="FNanchor_W_16"></a><a href="#Footnote_W_16" class="fnanchor">[281-B]</a></p>
+
+<p>Numerous specimens of the pen-and-ink fish (<i>Sepia loligo</i>, Lin.; <i>Loligo
+vulgaris</i>, Lam.) have also been met with in the lias at Lyme, with the
+ink-bags still distended, containing the ink in a dried state, chiefly
+composed of carbon, and but slightly impregnated with carbonate of lime.
+These cephalopoda, therefore, must, like the saurians, have been soon
+buried in sediment; for, if long exposed after death, the membrane
+containing the ink would have decayed.<a name="FNanchor_W_17" id="FNanchor_W_17"></a><a href="#Footnote_W_17" class="fnanchor">[281-C]</a></p>
+
+<p>As we know that river fish are sometimes stifled, even in their own
+element, by muddy water during floods, it cannot be doubted that the
+periodical discharge of large bodies of turbid fresh water into the sea may
+be still more fatal to marine tribes. In the Principles of Geology I have
+shown that large quantities of mud and drowned animals have been swept down
+into the sea by rivers during earthquakes, as in Java, in 1699; and that
+undescribable multitudes of dead fishes have been seen floating on the sea
+after a discharge of noxious vapours during similar convulsions.<a name="FNanchor_W_18" id="FNanchor_W_18"></a><a href="#Footnote_W_18" class="fnanchor">[281-D]</a>
+But, in the intervals between such catastrophes, strata may have
+accumulated slowly in the sea of the lias, some being formed chiefly of one
+description of shell, such as ammonites, others of gryphites.</p>
+
+<p>From the above remarks the reader will infer that the lias is for the most
+part a marine deposit. Some members, however, of the series, especially in
+the lowest part of it, have an estuary character, and must have been formed
+within the influence of rivers. In Gloucestershire, where there is a good
+type of the lias of the West of England, it may be divided into an upper
+mass of shale with a base of marlstone, and a lower series of shales with
+underlying limestones and shales. We learn from the researches of the Rev.
+P. B. Brodie<a name="FNanchor_W_19" id="FNanchor_W_19"></a><a href="#Footnote_W_19" class="fnanchor">[281-E]</a>, that in the superior of these two divisions numerous
+remains of insects and plants have been detected in several places, mingled
+with marine shells; but in the inferior division similar fossils are still
+more plentiful. One band, rarely exceeding a foot in thickness, has been
+named the "insect limestone." It passes upwards into a shale containing
+<i>Cypris</i> and <i>Estheria</i>, and is charged with the wing-cases of several
+genera of coleoptera, and with some nearly entire beetles, of which the
+eyes are preserved. The nervures of the wings of neuropterous <span class="pagenum"><a id="page282"></a>[p.282]</span>
+insects (<a href="#img299">fig. 314.</a>) are beautifully perfect in this bed. Ferns, with leaves
+of monocotyledonous plants, and freshwater shells, such as <i>Cyclas</i> and
+<i>Unio</i>, accompany the insects in some places, while in others marine shells
+predominate, the fossils varying apparently as we examine the bed nearer or
+farther from the ancient land, or the source whence the fresh water was
+derived. There are two, or even three, bands of "insect limestone" in
+several sections, and they have been ascertained by Mr. Brodie to retain
+the same lithological and zoological characters when traced from the centre
+of Warwickshire to the borders of the southern part of Wales. After
+studying 300 specimens of these insects from the lias, Mr. Westwood
+declares that they comprise both wood-eating and herb-devouring beetles of
+the Linnean genera <i>Elater</i>, <i>Carabus</i>, &amp;c., besides grasshoppers
+(<i>Gryllus</i>), and detached wings of dragon-flies and may-flies, or insects
+referable to the Linnean genera <i>Libellula</i>, <i>Ephemera</i>, <i>Hemerobius</i>, and
+<i>Panorpa</i>, in all belonging to no less than twenty-four families. The size
+of the species is usually small, and such as taken alone would imply a
+temperate climate; but many of the associated organic remains of other
+classes must lead to a different conclusion.</p>
+
+<a id="img299" name="img299"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 314.</p>
+<img src="images/img299.jpg" width="200" height="090" alt="" title="">
+<p>Wing of a neuropterous insect, from the Lower Lias,
+<span class="wosp05">Gloucestershire. (Rev.</span> B. Brodie.)</p></div>
+
+<p><i>Fossil plants.</i>&mdash;Among the vegetable remains of the Lias, several species
+of <i>Zamia</i> have been found at Lyme Regis, and the remains of coniferous
+plants at Whitby. Fragments of wood are common, and often converted into
+limestone. That some of this wood, though now petrified, was soft when it
+first lay at the bottom of the sea, is shown by a specimen now in the
+museum of the Geological Society (see <a href="#img300">fig. 315.</a>), which has the form of an
+<i>ammonite</i> indented on its surface.</p>
+
+<a id="img300" name="img300"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 315.</p>
+<img src="images/img300.jpg" width="200" height="104" alt="" title=""></div>
+
+<p>M. Ad. Brongniart enumerates forty-seven liassic acrogens, most of them
+ferns; and fifty gymnogens, of which thirty-nine are cycads, and eleven
+conifers. Among the cycads the predominance of <i>Zamites</i> and <i>Nilsonia</i>,
+and among the ferns the numerous genera with leaves having reticulated
+veins (as in <a href="#img281">fig. 296.</a> <a href="#page272">p. 272.</a>), are mentioned as botanical characteristics
+of this era.<a name="FNanchor_W_20" id="FNanchor_W_20"></a><a href="#Footnote_W_20" class="fnanchor">[282-A]</a></p>
+
+<p><i>Origin of the Oolite and Lias.</i>&mdash;If we now endeavour to restore, in
+imagination, the ancient condition of the European area at the period of
+the Oolite and Lias, we must conceive a sea in which the growth of coral
+reefs and shelly limestones, after proceeding without interruption for
+ages, was liable to be stopped suddenly by the deposition of clayey
+sediment. Then, again, the argillaceous matter, devoid of corals, was
+deposited for ages, and attained a thickness of hundreds of feet, until
+another period arrived when the same space <span class="pagenum"><a id="page283"></a>[p.283]</span>was again occupied by
+calcareous sand, or solid rocks of shell and coral, to be again succeeded
+by the recurrence of another period of argillaceous deposition. Mr.
+Conybeare has remarked of the entire group of Oolite and Lias, that it
+consists of repeated alternations of clay, sandstone, and limestone,
+following each other in the same order. Thus the clays of the lias are
+followed by the sands of the inferior oolite, and these again by shelly and
+coralline limestone (Bath oolite, &amp;c.); so, in the middle oolite, the
+Oxford clay is followed by calcareous grit and "coral rag;" lastly, in the
+upper oolite, the Kimmeridge clay is followed by the Portland sand and
+limestone.<a name="FNanchor_W_21" id="FNanchor_W_21"></a><a href="#Footnote_W_21" class="fnanchor">[283-A]</a> The clay beds, however, as Sir H. De la Beche remarks,
+can be followed over larger areas than the sands or sandstones.<a name="FNanchor_W_22" id="FNanchor_W_22"></a><a href="#Footnote_W_22" class="fnanchor">[283-B]</a> It
+should also be remembered that while the oolitic system becomes arenaceous,
+and resembles a coal-field in Yorkshire, it assumes, in the Alps, an almost
+purely calcareous form, the sands and clays being omitted; and even in the
+intervening tracts, it is more complicated and variable than appears in
+ordinary descriptions. Nevertheless, some of the clays and intervening
+limestones do, in reality, retain a pretty uniform character, for distances
+of from 400 to 600 miles from east to west and north to south.</p>
+
+<p>According to M. Thirria, the entire oolitic group in the department of the
+Haute-Sa�ne, in France, may be equal in thickness to that of England; but
+the importance of the argillaceous divisions is in the inverse ratio to
+that which they exhibit in England, where they are about equal to twice the
+thickness of the limestones, whereas, in the part of France alluded to,
+they reach only about a third of that thickness.<a name="FNanchor_W_23" id="FNanchor_W_23"></a><a href="#Footnote_W_23" class="fnanchor">[283-C]</a> In the Jura the
+clays are still thinner; and in the Alps they thin out and almost vanish.</p>
+
+<p>In order to account for such a succession of events, we may imagine, first,
+the bed of the ocean to be the receptacle for ages of fine argillaceous
+sediment, brought by oceanic currents, which may have communicated with
+rivers, or with part of the sea near a wasting coast. This mud ceases, at
+length, to be conveyed to the same region, either because the land which
+had previously suffered denudation is depressed and submerged, or because
+the current is deflected in another direction by the altered shape of the
+bed of the ocean and neighbouring dry land. By such changes the water
+becomes once more clear and fit for the growth of stony zoophytes.
+Calcareous sand is then formed from comminuted shell and coral, or, in some
+cases, arenaceous matter replaces the clay; because it commonly happens
+that the finer sediment, being first drifted farthest from coasts, is
+subsequently overspread by coarse sand, after the sea has grown shallower,
+or when the land, increasing in extent, whether by upheaval or by sediment
+filling up parts of the sea, has approached nearer to the spots first
+occupied by fine mud.</p>
+
+<p>In order to account for another great formation, like the Oxford <span class="pagenum"><a id="page284"></a>[p.284]</span>
+clay, again covering one of coral limestone, we must suppose a sinking down
+like that which is now taking place in some existing regions of coral
+between Australia and South America. The occurrence of subsidences, on so
+vast a scale, may have caused the bed of the ocean and the adjoining land,
+throughout great parts of the European area, to assume a shape favourable
+to the deposition of another set of clayey strata; and this change may have
+been succeeded by a series of events analogous to that already explained,
+and these again by a third series in similar order. Both the ascending and
+descending movements may have been extremely slow, like those now going on
+in the Pacific; and the growth of every stratum of coral, a few feet of
+thickness, may have required centuries for its completion, during which
+certain species of organic beings disappeared from the earth, and others
+were introduced in their place; so that, in each set of strata, from the
+Upper Oolite to the Lias, some peculiar and characteristic fossils were
+embedded.</p>
+
+
+<h3><i>Oolite and Lias of the United States.</i></h3>
+
+<a id="img301" name="img301"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 316.</p>
+<img src="images/img301.jpg" width="500" height="107" alt="" title="">
+<p>Section showing the geological position of the James River, or East
+Virginian Coal-field.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li>A. Granite, gneiss, &amp;c.</li>
+<li>B. Coal-measures.</li>
+<li>C. Tertiary strata.</li>
+<li>D. Drift or <i>ancient alluvium</i>.</li>
+</ul></div>
+
+<p>There are large tracts on the globe, as in Russia and the United States,
+where all the members of the oolitic series are unrepresented. In the state
+of Virginia, however, at the distance of about 13 miles eastward of
+Richmond, the capital of that State, there is a regular coal-field
+occurring in a depression of the granite rocks (see section, <a href="#img301">fig. 316.</a>),
+which Professor W. B. Rogers first correctly referred to the age of the
+lower part of the Jurassic group. This opinion I was enabled to confirm
+after collecting a large number of fossil plants, fish, and shells, and
+examining the coal-field throughout its whole area. It extends 26 miles
+from north to south, and from 4 to 12, from east to west. The plants
+consist chiefly of zamites, calamites, and equisetums, and these last are
+very commonly met with in a vertical position more or less compressed
+perpendicularly. It is clear that they grew in the places where they now
+lie buried in strata of hardened sand and mud. I found them maintaining
+their erect attitude, at points many miles distant from others, in beds
+both above and between the seams of coal. In order to explain this fact we
+must suppose such shales and sandstones to have been gradually accumulated
+during the slow and repeated subsidence of the whole region.</p>
+
+<p>It is worthy of remark that the <i>Equisetum columnare</i> of these Virginian
+rocks appears to be undistinguishable from the species <span class="pagenum"><a id="page285"></a>[p.285]</span>found in
+the oolitic sandstones near Whitby in Yorkshire, where it also is met with
+in an upright position. One of the American ferns, <i>Pecopteris
+Whitbyensis</i>, is also a species common to the Yorkshire oolites.<a name="FNanchor_W_24" id="FNanchor_W_24"></a><a href="#Footnote_W_24" class="fnanchor">[285-A]</a>
+These Virginian coal-measures are composed of grits, sandstones, and
+shales, exactly resembling those of older or primary date in America and
+Europe, and they rival or even surpass the latter in the richness and
+thickness of the seams. One of these, the main seam, is in some places from
+30 to 40 feet thick, composed of pure bituminous coal. On descending a
+shaft 800 feet deep, in the Blackheath mines in Chesterfield county, I
+found myself in a chamber more than 40 feet high, caused by the removal of
+this coal. Timber props of great strength supported the roof, but they were
+seen to bend under the incumbent weight. The coal is like the finest kinds
+shipped at Newcastle, and when analysed yields the same proportions of
+carbon and hydrogen, a fact worthy of notice when we consider that this
+fuel has been derived from an assemblage of plants very distinct
+specifically, and in part generically, from those which have contributed to
+the formation of the ancient or paleozoic coal.</p>
+
+<p>The fossil fish of these Richmond strata belong to the liassic genus
+<i>Tetragonolepis</i>, and to a new genus which I have called <i>Dictyopyge</i>.
+Shells are very rare, as usually in all coal-bearing deposits, but a
+species of <i>Posidonomya</i> is in such profusion in some shaley beds as to
+divide them like the plates of mica in micaceous shales (see <a href="#img302">fig. 317.</a>).</p>
+
+<a id="img302" name="img302"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 317.</p>
+<img src="images/img302.jpg" width="350" height="250" alt="" title="">
+<ul class="leftal smaller add1em min1em">
+<li><i>a.</i> <i>Posidonomya.</i></li>
+<li><i>b.</i> young of same.</li>
+</ul>
+<p class="martopm05">Oolitic coal-shale, Richmond, Virginia.</p></div>
+
+<p>In India, especially in Cutch, a formation occurs clearly referable to the
+oolitic and liassic type, as shown by the shells, corals, and plants; and
+there also coal has been procured from one member of the group.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page286"></a>[p.286]</span>CHAPTER XXII.</h2>
+
+<h4>TRIAS OR NEW RED SANDSTONE GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">Distinction between New and Old Red Sandstone &mdash; Between Upper and Lower
+New Red &mdash; The Trias and its three divisions &mdash; Most largely
+developed in Germany &mdash; Keuper and its
+fossils &mdash; Muschelkalk &mdash; Fossil plants of Bunter &mdash; Triassic
+group in England &mdash; Bone-bed of Axmouth and Aust &mdash; Red Sandstone of
+Warwickshire and Cheshire &mdash; Footsteps of <i>Chirotherium</i> in England and
+Germany &mdash; Osteology of the <i>Labyrinthodon</i> &mdash; Identification of this
+Batrachian with the Chirotherium &mdash; Origin of Red Sandstone and
+Rock-salt &mdash; Hypothesis of saline volcanic exhalations &mdash; Theory of
+the precipitation of salt from inland lakes or lagoons &mdash; Saltness of
+the Red Sea &mdash; New Red Sandstone in the United States &mdash; Fossil
+footprints of birds and reptiles in the Valley of the
+Connecticut &mdash; Antiquity of the Red Sandstone containing them.</p></div>
+
+
+<p><span class="smcap">Between</span> the Lias and the Coal, or Carboniferous group, there is interposed,
+in the midland and western counties of England, a great series of red
+loams, shales, and sandstones, to which the name of the New Red Sandstone
+formation was first given, to distinguish it from other shales and
+sandstones called the "Old Red" (<i>c</i>, <a href="#img303">fig. 318.</a>), often identical in
+mineral character, which lie immediately beneath the coal (<i>b</i>).</p>
+
+<a id="img303" name="img303"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 318.</p>
+<img src="images/img303.jpg" width="450" height="079" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> New red sandstone.</li>
+<li><i>b.</i> Coal.</li>
+<li><i>c.</i> Old red.</li>
+</ul></div>
+
+<p>The name of "Red Marl" has been incorrectly applied to the red clays of
+this formation, as before explained (<a href="#page13">p. 13.</a>), for they are remarkably free
+from calcareous matter. The absence, indeed, of carbonate of lime, as well
+as the scarcity of organic remains, together with the bright red colour of
+most of the rocks of this group, causes a strong contrast between it and
+the Jurassic formations before described.</p>
+
+<p>Before the distinctness of the fossil remains characterizing the upper and
+lower part of the English New Red had been clearly recognized, it was found
+convenient to have a common name for all the strata intermediate in
+position between the Lias and Coal; and the term "Poikilitic" was proposed
+by Messrs. Conybeare and Buckland<a name="FNanchor_X_1" id="FNanchor_X_1"></a><a href="#Footnote_X_1" class="fnanchor">[286-A]</a>, from &#960;&#959;&#953;&#954;&#953;&#955;&#959;&#962;, poikilos,
+<i>variegated</i>, some of the most characteristic strata of this group having
+been called <i>variegated</i> by Werner, from their exhibiting spots and streaks
+of light-blue, green, and buff colour, in a red base.</p>
+
+<p><span class="pagenum"><a id="page287"></a>[p.287]</span>A single term, thus comprehending both Upper and Lower New Red, or
+the Triassic and Permian groups of modern classifications, may still be
+useful in describing districts where we have to speak of masses of red
+sandstone and shale, referable, in part, to both these eras, but which, in
+the absence of fossils, it is impossible to divide.</p>
+
+
+<h3><i>Trias or Upper New Red Sandstone Group.</i></h3>
+
+<p>The accompanying table will explain the subdivisions generally adopted for
+the uppermost of the two systems above alluded to, and the names given to
+them in England and on the Continent.</p>
+
+
+<table  border="0" cellpadding="2" summary="SUBDIVISIONS OF TRIAS/UPPER NEW
+RED SANDSTONE IN ENGLAND AND ON THE CONTINENT.">
+<colgroup>
+    <col width="17%">
+    <col width="4%">
+    <col width="1%">
+    <col width="4%">
+    <col width="25%">
+    <col width="4%">
+    <col width="1%">
+    <col width="4%">
+    <col width="15%">
+    <col width="4%">
+    <col width="1%">
+    <col width="1%">
+    <col width="4%">
+    <col width="15%">
+</colgroup>
+
+<tr>
+  <td colspan="7">&nbsp;</td>
+  <td colspan="7" class="td-center tdtx-top tdp-left borbot">Synonyms.</td>
+</tr>
+
+<tr>
+  <td colspan="8">&nbsp;</td>
+  <td class="td-left tdtx-top tdp-left">German.</td>
+  <td colspan="4">&nbsp;</td>
+  <td class="td-left tdtx-top tdp-left">French.</td>
+</tr>
+
+<tr>
+  <td rowspan="5" class="tdtx-mid td-left">Trias or Upper New Red Sandstone</td>
+  <td rowspan="5">&nbsp;</td>
+  <td rowspan="5" class="borright">&nbsp;</td>
+  <td rowspan="5">&nbsp;</td>
+  <td class="tdtx-mid td-left"><i>a.</i> Saliferous and gypseous shales and sandstone</td>
+  <td rowspan="5">&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td rowspan="5">&nbsp;</td>
+  <td class="tdtx-mid td-left">Keuper</td>
+  <td rowspan="5">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td rowspan="5">&nbsp;</td>
+  <td class="tdtx-mid td-left">Marnes iris�es.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left"><i>b.</i> (wanting in England)</td>
+  <td>&nbsp;</td>
+  <td class="tdtx-mid td-left">Muschelkalk</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td class="tdtx-mid td-left">Muschelkalk, ou calcaire coquillier.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left"><i>c.</i> Sandstone and quartzose conglomerate</td>
+  <td class="borleft">&nbsp;</td>
+  <td class="tdtx-mid td-left">Bunter-sandstein</td>
+  <td class="borleft">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdtx-mid td-left">Gr�s bigarr�.</td>
+</tr>
+</table>
+
+
+<p>I shall first describe this group as it occurs in South Western and North
+Western Germany, for it is far more fully developed there than in England
+or France. It has been called the Trias by German writers, or the Triple
+Group, because it is separable into three distinct formations, called the
+"Keuper," the "Muschelkalk," and the "Bunter-sandstein."</p>
+
+<a id="img304" name="img304"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 319.</p>
+<img src="images/img304.jpg" width="200" height="150" alt="" title="">
+<p><i>Equisetites columnaris</i><span class="wosp05">. (Syn.</span> <i>Equisetum
+columnare</i><span class="wosp05">.) Fragment</span> of stem, and small portion of same <span class="wosp05">magnified.
+Keuper.</span></p></div>
+
+<p><i>The Keuper</i>, the first or newest of these, is 1000 feet thick in
+W�rtemberg, and is divided by Alberti into sandstone, gypsum, and
+carbonaceous slate-clay.<a name="FNanchor_X_2" id="FNanchor_X_2"></a><a href="#Footnote_X_2" class="fnanchor">[287-A]</a> Remains of Reptiles, called <i>Nothosaurus</i>
+and <i>Phytosaurus</i>, have been found in it with <i>Labyrinthodon</i>; the detached
+teeth, also, of placoid fish and of rays, and of the genera <i>Saurichthys</i>
+and <i>Gyrolepis</i> (<a href="#img310">figs. 325</a>, <a href="#img311">326</a>, <a href="#page289">p. 289.</a>). The plants of the Keuper are
+generically very analogous to those of the lias and oolite, consisting of
+ferns, equisetaceous plants, cycads, and conifers, with a few doubtful
+monocotyledons. A few species, such as <i>Equisetites columnaris</i>, are common
+to this group, and the oolite.</p>
+
+<p><i>The Muschelkalk</i> consists chiefly of a compact, greyish limestone, but
+includes beds of dolomite in many places, together with gypsum and
+rock-salt. This limestone, a rock wholly unrepresented in England, abounds
+in fossil shells, as the name implies. Among the cephalopoda there are no
+belemnites, and no ammonites with foliated sutures, as in the incumbent
+lias and oolite, but a genus allied to the Ammonite, called <i>Ceratite</i> by
+De Haan, in which the descending lobes (see <i>a</i>, <i>b</i>, <i>c</i>, <a href="#img305">fig. 320.</a>)
+terminate in a few small denticulations <span class="pagenum"><a id="page288"></a>[p.288]</span>pointing inwards. Among
+the bivalve shells, the <i>Posidonia minuta</i>, Goldf. (<i>Posidonomya minuta</i>,
+Bronn) (see <a href="#img306">fig. 321.</a>), is abundant, ranging through the Keuper,
+Muschelkalk, and Bunter-sandstein; and <i>Avicula socialis</i>, <a href="#img307">fig. 322.</a>,
+having a similar range, is very characteristic of the Muschelkalk in
+Germany, France, and Poland.</p>
+
+<a id="img305" name="img305"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 320.</p>
+<img src="images/img305.jpg" width="450" height="260" alt="" title="">
+<p><i>Ceratites nodosus</i><span class="wosp05">. Muschelkalk.</span></p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Side view.</li>
+<li><i>b.</i> Front view.</li>
+<li><i>c.</i> Partially denticulated outline of the septa dividing the chambers.</li>
+</ul></div>
+
+<a id="img306" name="img306"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 321.</p>
+<img src="images/img306.jpg" width="150" height="122" alt="" title="">
+<p><i>Posidonia minuta</i>, Goldf. (<i>Posidonomya minuta</i>, Bronn.)</p></div>
+
+<a id="img307" name="img307"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 322.</p>
+<img src="images/img307.jpg" width="300" height="060" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Avicula socialis.</i></li>
+<li><i>b.</i> Side view of same.</li>
+</ul>
+<p class="martopm05">Characteristic of the Muschelkalk.</p></div>
+
+<p>The abundance of the heads and stems of lily encrinites, <i>Encrinus
+liliiformis</i> (or <i>Encrinites moniliformis</i>), show the slow manner in which
+some beds of this limestone have been formed in clear sea-water.</p>
+
+<a id="img308" name="img308"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 323.</p>
+<img src="images/img308.jpg" width="250" height="195" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Voltzia heterophylla.</i> (Syn. <i>Voltzia brevifolia</i>.)</li>
+<li><i>b.</i> portion of same magnified to show fructification. Sulzbad.</li>
+</ul>
+<p class="martopm05">Bunter-sandstein.</p></div>
+
+<p><i>The Bunter-sandstein</i> consists of various coloured sandstones, dolomites,
+and red-clays, with some beds, especially in the Hartz, of calcareous
+pisolite or roe-stone, the whole sometimes attaining a thickness of more
+than 1000 feet. The sandstone of the Vosges, according to Von Meyer, is
+proved, by the presence of <i>Labyrinthodon</i>, to belong to this lowest member
+of the Triassic group. At Sulzbad (or Soultz-les-bains), near Strasburg, on
+the flanks of the Vosges, many plants have been obtained from the "bunter,"
+especially conifers of the extinct genus <i>Voltzia</i>, peculiar to this
+period, in which even the fructification has been preserved. (See <a href="#img308">fig.
+323.</a>)</p>
+
+<p>Out of thirty species of ferns, cycads, conifers, and other plants,
+enumerated by M. Ad. Brongniart, in 1849, as coming from the "gr�s
+bigarr�," or Bunter, not one is common to the Keuper.<a name="FNanchor_X_3" id="FNanchor_X_3"></a><a href="#Footnote_X_3" class="fnanchor">[288-A]</a></p>
+
+<p><span class="pagenum"><a id="page289"></a>[p.289]</span>The footprints of a reptile (<i>Labyrinthodon</i>) have been observed
+on the clays of this member of the Trias, near Hildburghausen, in Saxony,
+impressed on the upper surface of the beds, and standing out as casts in
+relief from the under sides of incumbent slabs of sandstone. To these I
+shall again allude in the sequel; they attest, as well as the accompanying
+ripple-marks, and the cracks which traverse the clays, the gradual
+formation in shallow water, and sometimes between high and low water, of
+the beds of this formation.</p>
+
+
+<h3><i>Triassic group in England.</i></h3>
+
+<p>In England the Lias is succeeded by conformable strata of red and green
+marl, or clay. There intervenes, however, both in the neighbourhood of
+Axmouth, in Devonshire, and in the cliffs of Westbury and Aust, in
+Gloucestershire, on the banks of the Severn, a dark-coloured stratum, well
+known by the name of the "bone-bed." It abounds in the remains of saurians
+and fish, and was formerly classed as the lowest bed of the Lias; but Sir
+P. Egerton has shown that it should be referred to the Upper New Red
+Sandstone, for it contains an assemblage of fossil fish which are either
+peculiar to this stratum, or belong to species well known in the
+Muschelkalk of Germany. These fish belong to the genera <i>Acrodus</i>,
+<i>Hybodus</i>, <i>Gyrolepis</i>, and <i>Saurichthys</i>.</p>
+
+<p>Among those common to the English bone-bed and the Muschelkalk of Germany
+are <i>Hybodus plicatilis</i> (<a href="#img309">fig. 324.</a>), <i>Saurichthys apicalis</i> (<a href="#img310">fig. 325.</a>),
+<i>Gyrolepis tenuistriatus</i> (<a href="#img311">fig. 326.</a>), and <i>G. Albertii</i>. Remains of
+saurians have also been found in the bone-bed, and plates of an <i>Encrinus</i>.</p>
+
+<a id="img309" name="img309"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 324.</p>
+<img src="images/img309.jpg" width="300" height="114" alt="" title="">
+<p><i>Hybodus plicatilis</i><span class="wosp05">. Teeth. Bone-bed,</span>
+Aust and Axmouth.</p></div>
+
+<a id="img310" name="img310"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 325.</p>
+<img src="images/img310.jpg" width="150" height="233" alt="" title="">
+<p><i>Saurichthys apicalis.</i> Tooth; nat. size, and
+<span class="wosp05">magnified. Axmouth.</span></p></div>
+
+<a id="img311" name="img311"></a>
+<div class="floatright smaller width150">
+<p>Fig. 326.</p>
+<img src="images/img311.jpg" width="150" height="166" alt="" title="">
+<p><i>Gyrolepis tenuistriatus.</i> Scale; nat. size, and
+<span class="wosp05">magnified. Axmouth.</span></p></div>
+
+<p class="nofloat">The strata of red and green marl, which follow the bone-bed in the
+descending order at Axmouth and Aust, are destitute of organic remains; as
+is the case, for the most part, in the corresponding beds in almost every
+part of England. But fossils have lately been found at a few localities in
+sandstones of this formation, in Worcestershire and Warwickshire, and among
+them the bivalve shell called <i>Posidonia minuta</i>, Goldf., before mentioned
+(<a href="#img306">fig. 321.</a> <a href="#page288">p. 288.</a>).</p>
+
+<p>The upper member of the English "New Red" containing this <span class="pagenum"><a id="page290"></a>[p.290]</span>shell,
+in those parts of England, is, according to Messrs. Murchison and
+Strickland, 600 feet thick, and consists chiefly of red marl or slate, with
+a band of sandstone. Spines of <i>Hybodus</i>, called <i>ichthyodorulites</i>, teeth
+of fishes, and footprints of reptiles, with remains of a saurian called
+<i>Rhyncosaurus</i>, were observed by the same geologists in these
+strata.<a name="FNanchor_X_4" id="FNanchor_X_4"></a><a href="#Footnote_X_4" class="fnanchor">[290-A]</a></p>
+
+<p>In Cheshire and Lancashire the gypseous and saliferous red shales and loams
+of the Trias are between 1000 and 1500 feet thick. In some places
+lenticular masses of rock-salt are interpolated between the argillaceous
+beds, the origin of which will be spoken of in the sequel.</p>
+
+<a id="img312" name="img312"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 327.</p>
+<img src="images/img312.jpg" width="200" height="215" alt="" title="">
+<p>Single footstep of <i>Chirotherium</i>. Bunter
+Sandstein, Saxony; one eighth of nat. size.</p></div>
+
+<a id="img313" name="img313"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 328.</p>
+<img src="images/img313.jpg" width="400" height="065" alt="" title="">
+<p>Line of footsteps on slab of <span class="wosp05">sandstone.
+Hildburghausen,</span> in Saxony.</p></div>
+
+<p>The lower division or English representative of the "Bunter" attains a
+thickness of 600 feet in the counties last mentioned. Besides red and green
+shales and red sandstones, it comprises much soft white quartzose
+sandstone, in which the trunks of silicified trees have been met with at
+Allesley Hill, near Coventry. Several of them were a foot and a half in
+diameter, and some yards in length, decidedly of coniferous wood, and
+showing rings of annual growth.<a name="FNanchor_X_5" id="FNanchor_X_5"></a><a href="#Footnote_X_5" class="fnanchor">[290-B]</a> Impressions, also, of the footsteps
+of animals have been detected in Lancashire and Cheshire in this formation.
+Some of the most remarkable occur a few miles from Liverpool, in the
+whitish quartzose sandstone of Storton Hill, on the west side of the
+Mersey. They bear a close resemblance to tracks first observed in a member
+of the Upper New Red Sandstone, at the village of Hesseberg, near
+Hildburghausen, in Saxony, to which I have already alluded. For many years
+these footprints have been referred to a large unknown quadruped,
+provisionally named <i>Chirotherium</i> by Professor Kaup, because the marks
+both of the fore and hind feet resembled impressions made by a human hand.
+(See <a href="#img312">fig. 327.</a>) The footmarks at Hesseberg are partly concave and partly in
+relief; the former, or the depressions, are seen upon the upper surface of
+the sandstone slabs, but those in relief are only upon the lower surfaces,
+being in fact natural casts, formed in the subjacent footprints as in
+moulds. The larger impressions, which seem to be those of the hind foot,
+are generally 8 inches in length, and 5 in width, and one was 12 inches
+long. Near each large footstep, and at a regular distance (about an inch
+<span class="pagenum"><a id="page291"></a>[p.291]</span>and a half), before it, a smaller print of a fore foot, 4 inches
+long and 3 inches wide, occurs. The footsteps follow each other in pairs,
+each pair in the same line, at intervals of 14 inches from pair to pair.
+The large as well as the small steps show the great toes alternately on the
+right and left side; each step makes the print of five toes, the first or
+great toe being bent inwards like a thumb. Though the fore and hind foot
+differ so much in size, they are nearly similar in form.</p>
+
+<p>The similar footmarks afterwards observed in a rock of corresponding age at
+Storton Hill, were imprinted on five thin beds of clay, superimposed one
+upon the other in the same quarry, and separated by beds of sandstone. On
+the lower surface of the sandstone strata, the solid casts of each
+impression are salient, in high relief, and afford models of the feet,
+toes, and claws of the animals which trod on the clay.</p>
+
+<p>As neither in Germany nor in England any bones or teeth had been met with
+in the same identical strata as the footsteps, anatomists indulged, for
+several years, in various conjectures respecting the mysterious animals
+from which they might have been derived. Professor Kaup suggested that the
+unknown quadruped might have been allied to the <i>Marsupialia</i>; for in the
+kangaroo the first toe of the fore foot is in a similar manner set
+obliquely to the others, like a thumb, and the disproportion between the
+fore and hind feet is also very great. But M. Link conceived that some of
+the four species of animals of which the tracks had been found in Saxony
+might have been gigantic <i>Batrachians</i>; and Dr. Buckland designated some of
+the footsteps as those of a small web-footed animal, probably crocodilean.</p>
+
+<p>In the course of these discussions several naturalists of Liverpool, in
+their report on the Storton quarries, declared their opinion that each of
+the thin seams of clay in which the sandstone casts were moulded had formed
+successively a surface above water, over which the <i>Chirotherium</i> and other
+animals walked, leaving impressions of their footsteps, and that each layer
+had been afterwards submerged by a sinking down of the surface, so that a
+new beach was formed at low water above the former, on which other tracks
+were then made. The repeated occurrence of ripple-marks at various heights
+and depths in the red sandstone of Cheshire had been explained in the same
+manner. It was also remarked that impressions of such depth and clearness
+could only have been made by animals walking on the land, as their weight
+would have been insufficient to make them sink so deeply in yielding clay
+under water. They must therefore have been air-breathers.</p>
+
+<p>When the inquiry had been brought to this point, the reptilian remains
+discovered in the Trias, both of Germany and England, were carefully
+examined by Mr. Owen. He found, after a microscopic investigation of the
+teeth from the German sandstone called Keuper, and from the sandstone of
+Warwick and Leamington, that <span class="pagenum"><a id="page292"></a>[p.292]</span>neither of them could be referred to
+true saurians, although they had been named <i>Mastodonsaurus</i> and
+<i>Phytosaurus</i> by J�ger (<a href="#img314">fig. 329.</a>). It appeared that they were of the
+<i>Batrachian</i> order, and attested the former existence of frogs of gigantic
+dimensions in comparison with any now living. Both the Continental and
+English fossil teeth exhibited a most complicated texture, differing from
+that previously observed in any reptile, whether recent or extinct, but
+most nearly analogous to the <i>Ichthyosaurus</i>. A section of one of these
+teeth exhibits a series of irregular folds, resembling the labyrinthic
+windings of the surface of the brain; and from this character Mr. Owen has
+proposed the name <i>Labyrinthodon</i> for the new genus. By his permission, the
+annexed representation (<a href="#img315">fig. 330.</a>) of part of one is given from his
+"Odontography," plate 64. A. The entire length of this tooth is supposed to
+have been about three inches and a half, and the breadth at the base one
+inch and a half.</p>
+
+<a id="img314" name="img314"></a>
+<div class="figcenter smaller width100">
+<p>Fig. 329.</p>
+<img src="images/img314.jpg" width="100" height="157" alt="" title="">
+<p>Tooth of <i>Labyrinthodon</i>; nat. <span class="wosp05">size. Warwick</span>
+sandstone.</p></div>
+
+<a id="img315" name="img315"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 330.</p>
+<img src="images/img315.jpg" width="450" height="383" alt="" title="">
+<p>Transverse section of tooth of <i>Labyrinthodon Jaegeri</i>, Owen
+(<i>Mastodonsaurus Jaegeri</i>, Meyer); nat. size, and a segment magnified.</p>
+<p class="martopm05"><i>a.</i> Pulp cavity, from which the processes of pulp and dentine radiate.</p></div>
+
+<p>When Mr. Owen had satisfied himself, from an inspection of the cranium,
+jaws, and teeth, that a gigantic <i>Batrachian</i> had existed at the period of
+the Trias or Upper New Red Sandstone, he soon found, from the examination
+of various bones derived from the same formation, that he could define
+three species of <i>Labyrinthodon</i>, and that in this genus the hind
+extremities were much larger than the anterior ones. This circumstance,
+coupled with the fact of the <i>Labyrinthodon</i> having existed at the period
+when the <i>Chirotherian</i> footsteps were made, was the first step towards the
+identification of those tracks with the newly discovered <i>Batrachian</i>. It
+was at the same time observed that the footmarks of <i>Chirotherium</i> were
+more like those <span class="pagenum"><a id="page293"></a>[p.293]</span>of toads than of any other living animal; and,
+lastly, that the size of the three species of <i>Labyrinthodon</i> corresponded
+with the size of three different kinds of footprints which had already been
+supposed to belong to three distinct <i>Chirotheria</i>. It was moreover
+inferred, with confidence, that the <i>Labyrinthodon</i> was an <i>air-breathing</i>
+reptile from the structure of the nasal cavity, in which the posterior
+outlets were at the back part of the mouth, instead of being directly under
+the anterior or external nostrils. It must have respired air after the
+manner of saurians, and may therefore have imprinted on the shore those
+footsteps, which, as we have seen, could not have originated from an animal
+walking under water.</p>
+
+<p>It is true that the structure of the foot is still wanting, and that a more
+connected and complete skeleton is required for demonstration; but the
+circumstantial evidence above stated is strong enough to produce the
+conviction that the <i>Chirotherium</i> and <i>Labyrinthodon</i> are one and the
+same.</p>
+
+<p>In order to show the manner in which one of these formidable <i>Batrachians</i>
+may have impressed the mark of its feet upon the shore, Mr. Owen has
+attempted a restoration, of which a reduced copy is annexed.</p>
+
+<a id="img316" name="img316"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 331.</p>
+<img src="images/img316.jpg" width="450" height="161" alt="" title="">
+<p><i>Labyrinthodon pachygnathus</i>, Owen.</p></div>
+
+<p>The only bones of this species at present known are those of the head, the
+pelvis, and part of the scapula, which are shown by stronger lines in the
+above figure. There is reason for believing that the head was not smooth
+externally, but protected by bony scutella.</p>
+
+
+<h3><i>Origin of Red Sandstone and Rock Salt.</i></h3>
+
+<p>We have seen that, in various parts of the world, red and mottled clays,
+and sandstones, of several distinct geological epochs, are found associated
+with salt, gypsum, magnesian limestone, or with one or all of these
+substances. There is, therefore, in all likelihood, a general cause for
+such a coincidence. Nevertheless, we must not forget that there are dense
+masses of red and variegated sandstones and clays, thousands of feet in
+thickness, and of vast horizontal extent, wholly devoid of saliferous or
+gypseous matter. There are also deposits of gypsum and of muriate of soda,
+as in the blue clay formation of Sicily, without any accompanying red
+sandstone or red clay.</p>
+
+<p>To account for deposits of red mud and red sand, we have simply <span class="pagenum"><a id="page294"></a>[p.294]</span>
+to suppose the disintegration of ordinary crystalline or metamorphic
+schists. Thus, in the eastern Grampians of Scotland, as, for example, in
+the north of Forfarshire, the mountains of gneiss, mica-schist, and
+clay-slate, are overspread with alluvium, derived from the disintegration
+of those rocks; and the mass of detritus is stained by oxide of iron, of
+precisely the same colour as the Old Red Sandstone of the adjoining
+Lowlands. Now this alluvium merely requires to be swept down to the sea, or
+into a lake, to form strata of red sandstone and red marl, precisely like
+the mass of the "Old Red" or New Red systems of England, or those tertiary
+deposits of Auvergne (see <a href="#page182">p. 182.</a>), before described, which are in
+lithological characters quite undistinguishable. The pebbles of gneiss in
+the Eocene red sandstone of Auvergne point clearly to the rocks from which
+it has been derived. The red colouring matter may, as in the Grampians,
+have been furnished by the decomposition of hornblende, or mica, which
+contain oxide of iron in large quantity.</p>
+
+<p>It is a general fact, and one not yet accounted for, that scarcely any
+fossil remains are preserved in stratified rocks in which this oxide of
+iron abounds; and when we find fossils in the New or Old Red Sandstone in
+England, it is in the grey, and usually calcareous beds, that they occur.</p>
+
+<p>The gypsum and saline matter, occasionally interstratified with such red
+clays and sandstones of various ages, primary, secondary, and tertiary,
+have been thought by some geologists to be of volcanic origin. Submarine
+and subaerial exhalations often occur in regions of earthquakes and
+volcanos far from points of actual eruption, and charged with sulphur,
+sulphuric salts, and with common salt or muriate of soda. In a word, they
+are vents by which all the products which issue in a state of sublimation
+from the craters of active volcanos, obtain a passage from the interior of
+the earth to the surface. That such gaseous emanations and mineral springs,
+impregnated with the ingredients before enumerated, and often intensely
+heated, continue to flow out unaltered in composition and temperature for
+ages, is well known. But before we can decide on their real instrumentality
+in producing in the course of ages beds of gypsum, salt, and dolomite, we
+require to know what are the chemical changes actually in progress in seas
+where this volcanic agency is at work.</p>
+
+<p>Yet the origin of rock-salt is a problem of so much interest in theoretical
+geology as to demand a full discussion of another hypothesis advanced on
+the subject; namely, that which attributes the precipitation of the salt to
+evaporation, whether of inland lakes or of lagoons communicating with the
+ocean.</p>
+
+<p>At Northwich, in Cheshire, two beds of salt, in great part unmixed with
+earthy matter, attain the extraordinary thickness of 90 and even 100 feet.
+The upper surface of the highest bed is very uneven, forming cones and
+irregular figures. Between the two masses there intervenes a bed of
+indurated clay, traversed with veins of salt. The highest bed thins off
+towards the south-west, losing 15 feet in <span class="pagenum"><a id="page295"></a>[p.295]</span>thickness in the course
+of a mile.<a name="FNanchor_X_6" id="FNanchor_X_6"></a><a href="#Footnote_X_6" class="fnanchor">[295-A]</a> The horizontal extent of these particular masses in
+Cheshire and Lancashire is not exactly known; but the area, containing
+saliferous clays and sandstones, is supposed to exceed 150 miles in
+diameter, while the total thickness of the trias in the same region is
+estimated by Mr. Ormerod at more than 1700 feet. Ripple-marked sandstones,
+and the footprints of animals, before described, are observed at so many
+levels that we may safely assume the whole area to have undergone a slow
+and gradual depression during the formation of the Red Sandstone. The
+evidence of such a movement, wholly independent of the presence of salt
+itself, is very important in reference to the theory under consideration.</p>
+
+<p>In the "Principles of Geology" (chap. 28.), I published a map, furnished to
+me by the late Sir Alexander Burnes, of that singular flat region called
+the Runn of Cutch, near the delta of the Indus, which is 7000 square miles
+in area, or equal in extent to about one-fourth of Ireland. It is neither
+land nor sea, but is dry during a part of every year, and again covered by
+salt water during the monsoons. Some parts of it are liable, after long
+intervals, to be overflowed by river-water. Its surface supports no grass,
+but is encrusted over, here and there, by a layer of salt, about an inch in
+depth, caused by the evaporation of sea-water. Certain tracts have been
+converted into dry land by upheaval during earthquakes since the
+commencement of the present century, and, in other directions, the
+boundaries of the Runn have been enlarged by subsidence. That successive
+layers of salt might be thrown down, one upon the other, over thousands of
+square miles, in such a region, is undeniable. The supply of brine from the
+ocean would be as inexhaustible as the supply of heat from the sun to cause
+evaporation. The only assumption required to enable us to explain a great
+thickness of salt in such as area is, the continuance, for an indefinite
+period, of a subsiding movement, the country preserving all the time a
+general approach to horizontality. Pure salt could only be formed in the
+central parts of basins, where no sand could be drifted by the wind, or
+sediment be brought by currents. Should the sinking of the ground be
+accelerated, so as to let in the sea freely, and deepen the water, a
+temporary suspension of the precipitation of salt would be the only result.
+On the other hand, if the area should dry up, ripple-marked sands and the
+footprints of animals might be formed, where salt had previously
+accumulated. According to this view the thickness of the salt, as well as
+of the accompanying beds of mud and sand, becomes a mere question of time,
+or requires simply a repetition of similar operations.</p>
+
+<p>Mr. Hugh Miller, in an able discussion of this question, refers to Dr.
+Frederick Parrot's account, in his journey to Ararat (1836), of the salt
+lakes of Asia. In several of these lakes west of the river Manech, "the
+water, during the hottest season of the year, is covered on its surface
+with a crust of salt nearly an inch thick, which is collected <span class="pagenum"><a id="page296"></a>[p.296]</span>
+with shovels into boats. The crystallization of the salt is effected by
+rapid evaporation from the sun's heat and the supersaturation of the water
+with muriate of soda; the lake being so shallow that the little boats trail
+on the bottom and leave a furrow behind them, so that the lake must be
+regarded as a wide pan of enormous superficial extent, in which the brine
+can easily reach the degree of concentration required."</p>
+
+<p>Another traveller, Major Harris, in his "Highlands of Ethiopia," describes
+a salt lake, called the Bahr Assal, near the Abyssinian frontier, which
+once formed the prolongation of the Gulf of Tadjara, but was afterwards cut
+off from the gulf by a broad bar of lava or of land upraised by an
+earthquake. "Fed by no rivers, and exposed in a burning climate to the
+unmitigated rays of the sun, it has shrunk into an elliptical basin, seven
+miles in its transverse axis, half filled with smooth water of the deepest
+c�rulian hue, and half with a solid sheet of glittering snow-white salt,
+the offspring of evaporation." "If," says Mr. Hugh Miller, "we suppose,
+instead of a barrier of lava, that sand-bars were raised by the surf on a
+flat arenaceous coast during a slow and equable sinking of the surface, the
+waters of the outer gulf might occasionally topple over the bar, and supply
+fresh brine when the first stock had been exhausted by evaporation.<a name="FNanchor_X_7" id="FNanchor_X_7"></a><a href="#Footnote_X_7" class="fnanchor">[296-A]</a></p>
+
+<p>We may add that the permanent impregnation of the waters of a large shallow
+basin with salt, beyond the proportion which is usual in the ocean, would
+cause it to be uninhabitable by mollusca or fish, as is the case in the
+Dead Sea, and the muriate of soda might remain in excess, even though it
+were occasionally replenished by irruptions of the sea. Should the saline
+deposit be eventually submerged, it might, as we have seen from the example
+of the Runn of Cutch, be covered by a freshwater formation containing
+fluviatile organic remains; and in this way the apparent anomaly of beds of
+sea-salt and clays devoid of marine fossils, alternating with others of
+freshwater origin, may be explained.</p>
+
+<p>Dr. G. Buist, in a recent communication to the Bombay Geographical Society
+(vol. ix.), has asked how it happens that the Red Sea should not exceed the
+open ocean in saltness, by more than 1/10th per cent. The Red Sea receives
+no supply of water from any quarter save through the Straits of
+Babelmandeb; and there is not a single river or rivulet flowing into it
+from a circuit of 4000 miles of shore. The countries around are all
+excessively sterile and arid, and composed, for the most part, of burning
+deserts. From the ascertained evaporation in the sea itself, Dr. Buist
+computes that nearly 8 feet of pure water must be carried off from the
+whole of its surface annually, this being probably equivalent to 1/100th
+part of its whole volume. The Red Sea, therefore, ought to have 1 per cent.
+added annually to its saline contents; and as these constitute 4 per cent.
+by weight, or 2<span class="smaller"><sup>1</sup>/<sub>2</sub></span> per cent. in volume of its entire mass, it ought,
+assuming the average depth to be 800 feet, which is supposed to be far
+beyond the truth, to have <span class="pagenum"><a id="page297"></a>[p.297]</span>been converted into one solid salt
+formation in less than 3000 years.<a name="FNanchor_X_8" id="FNanchor_X_8"></a><a href="#Footnote_X_8" class="fnanchor">[297-A]</a> Does the Red Sea receive a supply
+of water from the ocean, through the narrow Straits of Babelmandeb,
+sufficient to balance the loss by evaporation? And is there an undercurrent
+of heavier saline water annually flowing outwards? If not, in what manner
+is the excess of salt disposed of? An investigation of this subject by our
+nautical surveyors may perhaps aid the geologist in framing a true theory
+of the origin of rock-salt.</p>
+
+<p><i>On the New Red Sandstone of the valley of the Connecticut River in the
+United States.</i></p>
+
+<p>In a depression of the granitic or hypogene rocks in the States of
+Massachusetts and Connecticut, strata of red sandstone, shale, and
+conglomerate are found occupying an area more than 150 miles in length from
+north to south, and about 5 to 10 miles in breadth, the beds dipping to the
+eastward at angles varying from 5 to 50 degrees. The extreme inclination of
+50 degrees is rare, and only observed in the neighbourhood of masses of
+trap which have been intruded into the red sandstone while it was forming,
+or before the newer parts of the deposit had been completed. Having
+examined this series of rocks in many places, I feel satisfied that they
+were formed in shallow water, and for the most part near the shore, and
+that some of the beds were from time to time raised above the level of the
+water, and laid dry, while a newer series, composed of similar sediment,
+was forming. The red flags of thin-bedded sandstone are often
+ripple-marked, and exhibit on their under sides casts of cracks formed in
+the underlying red and green shales. These last must have shrunk by drying
+before the sand was spread over them. On some shales of the finest texture
+impressions of rain drops may be seen, and casts of them in the incumbent
+argillaceous sandstones. Having observed similar markings produced by
+showers, of which the precise date was known, on the recent red mud of the
+Bay of Fundy, and casts in relief of the same, on layers of dried mud
+thrown down by subsequent tides, I feel no doubt in regard to the origin of
+some of the ancient Connecticut impressions. I have also seen on the
+mud-flats of the Bay of Fundy the footmarks of birds (<i>Tringa minuta</i>),
+which daily run along the borders of that estuary at low water, and which I
+have described in my Travels.<a name="FNanchor_X_9" id="FNanchor_X_9"></a><a href="#Footnote_X_9" class="fnanchor">[297-B]</a> Similar layers of red mud, now
+hardened and compressed into shale, are laid open on the banks of the
+Connecticut, and retain faithfully the impressions and casts of the feet of
+numerous birds and reptiles which walked over them at the time when they
+were deposited, probably in the Triassic Period.</p>
+
+<p>According to Professor Hitchcock, the footprints of no less than thirty-two
+species of bipeds, and twelve of quadrupeds, have been already detected in
+these rocks. Thirty of these are believed to be those of birds, four of
+lizards, two of chelonians, and six of batrachians. <span class="pagenum"><a id="page298"></a>[p.298]</span>The tracks
+have been found in more than twenty places, scattered through an extent of
+nearly 80 miles from north to south, and they are repeated through a
+succession of beds attaining at some points a thickness of more than 1000
+feet, which may have been thousands of years in forming.<a name="FNanchor_X_10" id="FNanchor_X_10"></a><a href="#Footnote_X_10" class="fnanchor">[298-A]</a></p>
+
+<a id="img317" name="img317"></a>
+<div class="floatleft smaller width125">
+<p>Fig. 332.</p>
+<img src="images/img317.jpg" width="100" height="411" alt="" title="">
+<p>Footprints of a bird. Turner's Falls, Valley of the
+<span class="wosp05">Connecticut. (See</span> Dr. Deane, Mem. of Amer. Acad. vol. iv. 1849.)</p></div>
+
+<p>As considerable scepticism is naturally entertained in regard to the nature
+of the evidence derived from footprints, it may be well to enumerate some
+facts respecting them on which the faith of the geologist may rest. When I
+visited the United States in 1842, more than 2000 impressions had been
+observed by Professor Hitchcock, in the district alluded to, and all of
+them were indented on the upper surface of the layers, while the
+corresponding casts, standing out in relief, were always on the lower
+surfaces or planes of the strata. If we follow a single line of marks we
+find them uniform in size, and nearly uniform in distance from each other,
+the toes of two successive footprints, turning alternately right and left
+(see <a href="#img317">fig. 332.</a>). Such single lines indicate a biped; and there is generally
+such a deviation from a straight line, in any three successive prints, as
+we remark in the tracks left by birds. There is also a striking relation
+between the distance separating two footprints in one series and the size
+of the impressions; in other words, an obvious proportion between the
+length of the stride and the dimension of the creature which walked over
+the mud. If the marks are small, they may be half an inch asunder; if
+gigantic, as, for example, where the toes are 20 inches long, they are
+occasionally 4 feet and a half apart. The bipedal impressions are for the
+most part trifid, and show the same number of joints as exist in the feet
+of living tridactylous birds. Now such birds have three phalangeal bones
+for the inner toe, four for the middle and five for the outer one (see <a href="#img317">fig.
+332.</a>); but the impression of the terminal joint is that of the nail only.
+The fossil footprints exhibit regularly, where the joints are seen, the
+same number; and we see in each continuous line of tracks the three-jointed
+and five-jointed toes placed alternately outwards, first on the one side
+and then on the other. It is not often that the matrix has been fine enough
+to retain impressions of the integument or skin of the foot; but in one
+fine specimen found at Turner's Falls on the Connecticut, by Dr. Deane,
+these markings are well preserved, and have been recognized by Mr. Owen as
+resembling the skin of the ostrich, and not that of reptiles.<a name="FNanchor_X_11" id="FNanchor_X_11"></a><a href="#Footnote_X_11" class="fnanchor">[298-B]</a> Much
+care is required to ascertain <span class="pagenum"><a id="page299"></a>[p.299]</span>the precise layer of a laminated
+rock on which an animal has walked, because the impression usually extends
+downwards through several lamin�; and if the upper layer originally trodden
+upon is wanting, one or more joints, or even in some cases an entire toe,
+which sank less deep into the soft ground, may disappear, and yet the
+remainder of the footprint be well defined.</p>
+
+<p>The size of several of the fossil impressions of the Connecticut red
+sandstone so far exceeds that of any living ostrich, that naturalists at
+first were extremely adverse to the opinion of their having been made by
+birds, until the bones and almost entire skeleton of the <i>Dinornis</i> and of
+other feathered giants of New Zealand were discovered. Their dimensions
+have at least destroyed the force of this particular objection. The
+magnitude of the impressions of the feet of a heavy animal, which has
+walked on soft mud, increases for some distance below the surface
+originally trodden upon. In order, therefore, to guard against
+exaggeration, the casts rather than the mould are relied on. These casts
+show that some of the fossil birds had feet four times as large as the
+ostrich, but not perhaps larger than the <i>Dinornis</i>.</p>
+
+<p>Some of the quadrupedal footprints which accompany those of birds are
+analogous to European <i>Chirotheria</i>, and with a similar disproportion
+between the hind and fore feet. Others resemble that remarkable reptile,
+the <i>Rhyncosaurus</i> of the English Trias, a creature having some relation in
+its osteology both to chelonians and birds. Other imprints, again, are like
+those of turtles.</p>
+
+<p>Among the supposed bipedal tracks, a single distinct example only has been
+observed of feet in which there are four toes directed forwards. In this
+case a series of four footprints is seen, each 22 inches long and 12 wide,
+with joints much resembling those in the toes of birds. Professor Agassiz
+has suggested that it might have belonged to a gigantic bipedal batrachian;
+but the evidence on this subject is too defective to warrant such a bold
+conjecture, and if we were to give the reins to our imagination, we might
+as well conceive a bird having four toes projecting forwards as a huge
+two-legged frog. Nor should we forget that some quadrupeds place the hind
+foot so precisely on the spot just quitted by the fore foot, as to produce
+a single line of imprints like a biped.</p>
+
+<p>No bones have as yet been met with, whether of reptiles or birds, in the
+rocks of the Connecticut, but there are numerous coprolites; and an
+ingenious argument has been derived by Mr. Dana, from the analysis of these
+bodies, and the proportion they contain of uric acid, phosphate of lime,
+carbonate of lime, and organic matter, to show that, like guano, they are
+the droppings of birds, rather than of reptiles.<a name="FNanchor_X_12" id="FNanchor_X_12"></a><a href="#Footnote_X_12" class="fnanchor">[299-A]</a></p>
+
+<p>Mr. Darwin, in his "Journal of a Voyage in the Beagle," informs us that the
+"South American ostriches, although they live on vegetable matter, such as
+roots and grass, are repeatedly seen at Bahia Blanca <span class="pagenum"><a id="page300"></a>[p.300]</span>(lat. 39�
+S.), on the coast of Buenos Ayres, coming down at low water to the
+extensive mud-banks which are then dry, for the sake, as the Gauchos say,
+of feeding on small fish." They readily take to the water, and have been
+seen at the bay of San Blas, and at Port Valdez, in Patagonia, swimming
+from island to island.<a name="FNanchor_X_13" id="FNanchor_X_13"></a><a href="#Footnote_X_13" class="fnanchor">[300-A]</a> It is therefore evident, that in our times a
+South American mud-bank might be trodden simultaneously by ostriches,
+alligators, tortoises, and frogs; and the impressions left, in the
+nineteenth century, by the feet of these various tribes of animals, would
+not differ from each other more entirely than do those attributed to birds,
+saurians, chelonians, and batrachians, in the rocks of the Connecticut.</p>
+
+<p>To determine the exact age of the red sandstone and shale containing these
+ancient footprints in the United States, is not possible at present. No
+fossil shells have yet been found in the deposit, nor plants in a
+determinable state. The fossil fish are numerous and very perfect; but they
+are of a peculiar type, which was originally referred to the genus
+<i>Pal�oniscus</i>, but has since, with propriety, been ascribed, by Sir Philip
+Egerton, to a new genus. To this he has given the name of <i>Ischypterus</i>,
+from the great size and strength of the fulcral rays of the dorsal fin
+(from &#953;&#963;&#967;&#8058;&#962;; strength, and &#960;&#964;&#949;&#961;&#8056;&#957;, a fin). They differ
+from <i>Pal�oniscus</i>, as Mr. Redfield first pointed out, by having the
+vertebral column prolonged to a more limited extent into the upper lobe of
+the tail, or, in the language of M. Agassiz, they are less heterocercal.
+The teeth also, according to Sir P. Egerton, who, in 1844, examined for me
+a fine series of specimens which I procured at Durham, Connecticut, differ
+from those of <i>Pal�oniscus</i> in being strong and conical.</p>
+
+<p>That the sandstones containing these fish are of older date than the strata
+containing coal, before described (<a href="#page284">p. 284.</a>) as occurring near Richmond in
+Virginia, is highly probable. These were shown to be as old at least as the
+oolite and lias. The higher antiquity of the Connecticut beds cannot be
+proved by direct superposition, but may be presumed from the general
+structure of the country. That structure proves them to be newer than the
+movements to which the Appalachian or Alleghany chain owes its flexures,
+and this chain includes the ancient coal formation among its contorted
+rocks. The unconformable position of this <i>New Red</i> with ornithichnites on
+the edges of the inclined primary or paleozoic rocks of the Appalachians is
+seen at 4. of the section, <a href="#img358">fig. 379.</a> <a href="#page328">p. 327.</a> The absence of fish with
+decidedly heterocercal tails may afford an argument against the Permian age
+of the formation; and the opinion that the red sandstone is triassic,
+seems, on the whole, the best that we can embrace in the present state of
+our knowledge.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page301"></a>[p.301]</span>CHAPTER XXIII.</h2>
+
+<h4>PERMIAN OR MAGNESIAN LIMESTONE GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">Fossils of Magnesian Limestone and Lower New Red distinct from the
+Triassic &mdash; Term Permian &mdash; English and German
+equivalents &mdash; Marine shells and corals of English Magnesian
+limestone &mdash; Pal�oniscus and other fish of the marl
+slate &mdash; Thecodont Saurians of dolomitic conglomerate of
+Bristol &mdash; Zechstein and Rothliegendes of Thuringia &mdash; Permian
+Flora &mdash; Its generic affinity to the carboniferous &mdash; Psaronites or
+tree-ferns.</p></div>
+
+
+<p><span class="smcap">When</span> the use of the term "Poikilitic" was explained in the last chapter, I
+stated, that in some parts of England it is scarcely possible to separate
+the red marls and sandstones so called (originally named "the New Red"),
+into two distinct geological systems. Nevertheless, the progress of
+investigation, and a careful comparison of English rocks between the lias
+and the coal with those occupying a similar geological position in Germany
+and Russia, has enabled geologists to divide the Poikilitic formation; and
+has even shown that the lowermost of the two divisions is more closely
+connected, by its fossil remains, with the carboniferous group than with
+the trias. If, therefore, we are to draw a line between the secondary and
+primary fossiliferous strata, as between the tertiary and secondary, it
+must run through the middle of what was once called the "New Red," or
+Poikilitic group. The inferior half of this group will rank as Primary or
+Paleozoic, while its upper member will form the base of the Secondary
+series. For the lower, or Magnesian Limestone division of English
+geologists, Sir R. Murchison has proposed the name of Permian, from Perm, a
+Russian government where these strata are more extensively developed than
+elsewhere, occupying an area twice the size of France, and containing an
+abundant and varied suite of fossils.</p>
+
+<p>Mr. King, in his valuable monograph, recently published, of the Permian
+fossils of England, has given a table of the following six members of the
+Permian system of the north of England, with what he conceives to be the
+corresponding formations in Thuringia.<a name="FNanchor_Y_1" id="FNanchor_Y_1"></a><a href="#Footnote_Y_1" class="fnanchor">[301-A]</a></p>
+
+
+<table  border="0" cellpadding="2" summary="CORRESPONDING FORMATIONS OF THE PERMIAN SYSTEM
+OF THE NORTH OF ENGLAND AND THURINGIA." style="width: 80%; margin-left: 10%;">
+<colgroup>
+    <col width="60%">
+    <col width="40%">
+</colgroup>
+
+<tr>
+  <td class="td-center tdtx-top smaller">North of England.</td>
+  <td class="td-center tdtx-top smaller">Thuringia.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top tdp-left2 padtop1">1. Crystalline or concretionary, and non-crystalline limestone.</td>
+  <td class="td-left tdtx-top tdp-left padtop1">1. Stinkstein.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top tdp-left2">2. Brecciated and pseudo-brecciated limestone.</td>
+  <td class="td-left tdtx-top tdp-left">2. Rauchwacke.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top tdp-left2">3. Fossiliferous limestone.</td>
+  <td class="td-left tdtx-top tdp-left">3. Dolomit, or Upper Zechstein.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top tdp-left2">4. Compact limestone.</td>
+  <td class="td-left tdtx-top tdp-left">4. Zechstein, or Lower Zechstein.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top tdp-left2">5. Marl-slate.</td>
+  <td class="td-left tdtx-top tdp-left">5. Mergel-schiefer, or Kupferschiefer.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top tdp-left2">6. Inferior sandstones of various colours.</td>
+  <td class="td-left tdtx-top tdp-left">6. Rothliegendes.</td>
+</tr>
+</table>
+
+
+<p><span class="pagenum"><a id="page302"></a>[p.302]</span>I shall proceed, therefore, to treat briefly of these
+subdivisions, beginning with the highest, and referring the reader, for a
+fuller description of the lithological character of the whole group, as it
+occurs in the north of England, to a valuable memoir by Professor Sedgwick,
+published in 1835.<a name="FNanchor_Y_2" id="FNanchor_Y_2"></a><a href="#Footnote_Y_2" class="fnanchor">[302-A]</a></p>
+
+<p><i>Crystalline or concretionary limestone</i> (No. 1.).&mdash;This formation is seen
+upon the coast of Durham and Yorkshire, between the Wear and the Tees.
+Among its characteristic fossils are <i>Schizodus Schlotheimi</i> (<a href="#img318">fig. 333.</a>)
+and <i>Mytilus septifer</i> (<a href="#img320">fig. 335.</a>).</p>
+
+<a id="img318" name="img318"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 333.</p>
+<img src="images/img318.jpg" width="200" height="148" alt="" title="">
+<p><i>Schizodus Schlotheimi</i>, Geinitz. Syn. <i>Axinus
+obscurus</i>, Sow. Crystalline limestone, Permian.</p></div>
+
+<a id="img319" name="img319"></a>
+<div class="floatright smaller width200">
+<p>Fig. 334.</p>
+<img src="images/img319.jpg" width="200" height="139" alt="" title="">
+<p><i>Schizodus truncatus</i>, King; to show <span class="wosp05">hinge.
+Permian.</span></p></div>
+
+<a id="img320" name="img320"></a>
+<div class="nofloat figcenter smaller width200">
+<p>Fig. 335.</p>
+<img src="images/img320.jpg" width="200" height="281" alt="" title="">
+<p><i>Mytilus septifer</i>, King. Syn. <i>Modiola
+acuminata</i>, James Sow. Permian crystalline limestone.</p></div>
+
+<p>These shells occur at Hartlepool and Sunderland, where the rock assumes an
+oolitic and botryoidal character. Some of the beds in this division are
+ripple-marked; and Mr. King imagines that the absence of corals and the
+character of the shells indicate shallow water. In some parts of the coast
+of Durham, where the rock is not crystalline, it contains as much as
+forty-four per cent. of carbonate of magnesia, mixed with carbonate of
+lime. In other places,&mdash;for it is extremely variable in structure,&mdash;it
+consists chiefly of carbonate of lime, and has concreted into globular and
+hemispherical masses, varying from the size of a marble to that of a
+cannon-ball, and radiating from the centre. Occasionally earthy and
+pulverulent beds pass into compact limestone or hard granular dolomite. The
+stratification is very irregular, in some places well-defined, in others
+obliterated by the concretionary action which has re-arranged the materials
+of the rocks subsequently to their original deposition. Examples of this
+are seen at Pontefract and Ripon in Yorkshire.</p>
+
+<p><i>The brecciated limestone</i> (No. 2.) contains no fragments of foreign rocks,
+but seems composed of the breaking-up of the Permian limestone itself,
+about the time of its consolidation. Some of the angular masses in
+Tynemouth Cliff are 2 feet in diameter. This breccia is considered by
+Professor Sedgwick as one of the forms of the preceding limestone, No. 1.,
+rather than as regularly underlying it. The fragments are angular and never
+water-worn, and appear to have been re-cemented on the spot where they were
+formed. It is, therefore, suggested that they may have been due to those
+internal movements of the mass which produced the concretionary structure;
+but the subject is very obscure, and after studying the phenomenon in the
+Marston Rocks, on the coast of Durham, I found it impossible <span class="pagenum"><a id="page303"></a>[p.303]</span>to
+form any positive opinion on the subject. The well-known brecciated
+limestones of the Pyrenees appeared to me to present the nearest analogy,
+but on a much smaller scale.</p>
+
+<p><i>The fossiliferous limestone</i> (No. 3.) is regarded by Mr. King as a
+deep-water formation, from the numerous delicate corals which it includes.
+One of these, <i>Fenestella retiformis</i> (<a href="#img321">fig. 336.</a>), is a very variable
+species, and has received many different names. It sometimes attains a
+large size, measuring 8 inches in width. The same zoophyte is also found
+abundantly in the Permian of Germany.</p>
+
+<a id="img321" name="img321"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 336.</p>
+<img src="images/img321.jpg" width="450" height="207" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Fenestella retiformis</i>, Schlot.</li>
+<li>Syn. <i>Gorgonia infundibuliformis</i>, Goldf.; <i>Retepora flustracea</i>, Phillips.</li>
+<li><i>b.</i> Part of the same highly magnified.</li>
+</ul>
+<p>Magnesian limestone, Humbleton Hill, near Sunderland.<a name="FNanchor_Y_3" id="FNanchor_Y_3"></a><a href="#Footnote_Y_3" class="fnanchor">[303-A]</a></p></div>
+
+<p>Shells of the genera <i>Spirifer</i> and <i>Productus</i>, which do not occur in
+strata newer than the Permian, are abundant in this division of the series
+in the ordinary yellow magnesian limestone. (See <a href="#img322">figs. 337</a>, <a href="#img323">338.</a>)</p>
+
+<a id="img322" name="img322"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 337.</p>
+<img src="images/img322.jpg" width="250" height="225" alt="" title="">
+<p><i>Productus calvus</i>, Sow. Min. Con. Syn. <i>Productus
+horridus</i>, Bronn's Index, &amp;c., King's Monogr., &amp;c.; <i>Lept�na</i>, Dalman.</p>
+<p class="martopm05">Magnesian Limestone.</p></div>
+
+<a id="img323" name="img323"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 338.</p>
+<img src="images/img323.jpg" width="250" height="135" alt="" title="">
+<p><i>Spirifer undulatus</i>, Sow. Min. Con. Syn.
+<i>Triogonotreta undulata</i>, King's Monogr.</p>
+<p class="martopm05">Magnesian Limestone.</p></div>
+
+<p><i>The compact limestone</i> (No. 4.) also contains organic remains, especially
+corallines, and is intimately connected with the preceding. Beneath it lies
+the <i>marl-slate</i> (No. 5.), which consists of hard, calcareous shales,
+marl-slate, and thin-bedded limestones. At East Thickley, in Durham, where
+it is thirty feet thick, this slate has yielded many fine specimens of
+fossil fish of the genera <i>Pal�oniscus</i>, <i>Pygopterus</i>, <i>C&oelig;lacanthus</i>,
+and <i>Platysomus</i>, genera which are all found in the coal-measures of the
+carboniferous epoch, and which therefore, says Mr. King, probably lived at
+no great distance from <span class="pagenum"><a id="page304"></a>[p.304]</span>the shore. But the Permian species are
+peculiar, and, for the most part, identical with those found in the
+marl-slate or copper-slate of Thuringia.</p>
+
+<a id="img324" name="img324"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 339.</p>
+<img src="images/img324.jpg" width="400" height="125" alt="" title="">
+<p>Restored outline of a fish of the genus
+<i>Pal�oniscus</i>, Agass. <i>Pal�othrissum</i>, Blainville.</p></div>
+
+<p>The <i>Pal�oniscus</i> above mentioned belongs to that division of fishes which
+M. Agassiz has called "Heterocercal," which have their tails unequally
+bilobate, like the recent shark and sturgeon, and the vertebral column
+running along the upper caudal lobe. (See <a href="#img325">fig. 340.</a>) The "Homocercal" fish,
+which comprise almost all the 8000 species at present known in the living
+creation, have the tail-fin either single or equally divided; and the
+vertebral column stops short, and is not prolonged into either lobe. (See
+<a href="#img326">fig. 341.</a>)</p>
+
+<a id="img325" name="img325"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 340.</p>
+<img src="images/img325.jpg" width="250" height="139" alt="" title="">
+<p>Shark.</p>
+<p class="martopm05"><i>Heterocercal.</i></p></div>
+
+<a id="img326" name="img326"></a>
+<div class="floatright smaller width250">
+<p>Fig. 341.</p>
+<img src="images/img326.jpg" width="250" height="153" alt="" title="">
+<p>Shad. (<i>Clupea</i>, Herring tribe.)</p>
+<p class="martopm05"><i>Homocercal.</i></p></div>
+
+<p class="nofloat">Now it is a singular fact, first pointed out by Agassiz, that the
+heterocercal form, which is confined to a small number of genera in the
+existing creation, is universal in the Magnesian limestone, and all the
+more ancient formations. It characterizes the earlier periods of the
+earth's history, when the organization of fishes made a greater approach to
+that of saurian reptiles than at later epochs. In all the strata above the
+Magnesian limestone the homocercal tail predominates.</p>
+
+<p>A full description has been given by Sir Philip Egerton of the species of
+fish characteristic of the marl-slate in Mr. King's monograph before
+referred to, where figures of the ichthyolites which are very entire and
+well preserved, will be found. Even a single scale is usually so
+characteristically marked as to indicate the genus, and sometimes even the
+particular species. They are often scattered through the beds singly, and
+maybe useful to a geologist in determining the age of the rock.</p>
+
+<span class="pagenum"><a id="page305"></a>[p.305]</span>
+<a id="img327" name="img327"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 342.</p>
+<img src="images/img327.jpg" width="150" height="138" alt="" title="">
+<p><i>Pal�oniscus comtus</i>, <span class="wosp05">Agassiz. Scale</span>
+<span class="wosp05">magnified. Marl-slate.</span></p></div>
+
+<a id="img328" name="img328"></a>
+<div class="floatright smaller width150">
+<p>Fig. 343.</p>
+<img src="images/img328.jpg" width="150" height="155" alt="" title="">
+<p><i>Pal�oniscus elegans</i>, <span class="wosp05">Sedg. Under</span> surface of
+scale <span class="wosp05">magnified. Marl-slate.</span></p></div>
+
+<a id="img329" name="img329"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 344.</p>
+<img src="images/img329.jpg" width="150" height="171" alt="" title="">
+<p><i>Pal�oniscus glaphyrus</i>, <span class="wosp05">Ag. Under</span> surface of
+scale <span class="wosp05">magnified. Marl-slate.</span></p></div>
+
+<a id="img330" name="img330"></a>
+<div class="floatright smaller width150">
+<p>Fig. 345.</p>
+<img src="images/img330.jpg" width="150" height="099" alt="" title="">
+<p><i>C&oelig;lacanthus caudalis</i>, <span class="wosp05">Egerton. Scale</span> showing
+granulated surface <span class="wosp05">magnified. Marl-slate.</span></p></div>
+
+<a id="img331" name="img331"></a>
+<div class="nofloat figcenter smaller width500">
+<p>Scales of <span class="wosp05">fish. Magnesian</span> limestone.</p>
+<img src="images/img331.jpg" width="500" height="130" alt="" title="">
+<p>Fig. 346. <i>Pygopterus mandibularis</i>, <span class="wosp05">Ag. Marl-slate.</span></p>
+<ul class="martopm05 smaller leftal add6em min1em">
+<li><i>a.</i> Outside of scale magnified.</li>
+<li><i>b.</i> Under surface of same.</li>
+</ul>
+<p>Fig. 347. <i>Acrolepis Sedgwickii</i>, <span class="wosp05">Ag. Marl-slate.</span></p></div>
+
+<p>The <i>inferior sandstones</i> (No. 6. Tab. <a href="#page301">p. 301.</a>), which lie beneath the
+marl-slate, consist of sandstone and sand, separating the magnesian
+limestone from the coal, in Yorkshire and Durham. In some instances, red
+marl and gypsum have been found associated with these beds. They have been
+classed with the magnesian limestone by Professor Sedgwick, as being nearly
+co-extensive with it in geographical range, though their relations are very
+obscure. In some regions we find it stated that the imbedded plants are all
+specifically identical with those of the carboniferous series; and, if so,
+they probably belong to that epoch; for the true Permian flora appears,
+from the researches of MM. Murchison and de Verneuil in Russia, and of
+Colonel von Gutbier in Saxony, to be, with few exceptions, distinct from
+that of the coal (see <a href="#page307">p. 307.</a>).</p>
+
+<p><i>Dolomitic conglomerate of Bristol.</i>&mdash;Near Bristol, in Somersetshire, and
+in other counties bordering the Severn, the unconformable beds of the Lower
+New Red, resting immediately upon the Coal, consist of a conglomerate
+called "dolomitic," because the pebbles of older rocks are cemented
+together by a red or yellow base of dolomite or magnesian limestone. This
+conglomerate or breccia, for the imbedded fragments are sometimes angular,
+occurs in patches over the whole of the downs near Bristol, filling up the
+hollows and irregularities in the mountain limestone, and being principally
+composed at every spot of the debris of those rocks on which it immediately
+rests. At one point we find pieces of coal shale, in another of mountain
+limestone, recognizable by its peculiar shells and zoophytes. <span class="pagenum"><a id="page306"></a>[p.306]</span>
+Fractured bones, also, and teeth of saurians, are dispersed through some
+parts of the breccia.</p>
+
+<p>These saurians (which until the discovery of the <i>Archegosaurus</i> in the
+coal were the most ancient examples of fossil reptiles) are all
+distinguished by having the teeth implanted deeply in the jaw-bone, and in
+distinct sockets, instead of being soldered, as in frogs, to a simple
+alveolar parapet. In the dolomitic conglomerate near Bristol the remains of
+species of two distinct genera have been found, called <i>Thecodontosaurus</i>
+and <i>Pal�osaurus</i> by Dr. Riley and Mr. Stutchbury<a name="FNanchor_Y_4" id="FNanchor_Y_4"></a><a href="#Footnote_Y_4" class="fnanchor">[306-A]</a>; the teeth of
+which are conical, compressed, and with finely serrated edges (<a href="#img332">figs. 348</a>
+and <a href="#img333">349.</a>).</p>
+
+<a id="img332" name="img332"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 348.</p>
+<img src="images/img332.jpg" width="200" height="324" alt="" title="">
+<p>Tooth of <i>Pal�osaurus</i> platyodon, nat. size.</p></div>
+
+<a id="img333" name="img333"></a>
+<div class="floatright smaller width150">
+<p>Fig. 349.</p>
+<img src="images/img333.jpg" width="150" height="341" alt="" title="">
+<p>Tooth of <i>Thecodontosaurus</i>, 3 times magnified.</p></div>
+
+<p class="nofloat">In Russia, also, Thecodont saurians occur, in beds of the Permian age, of
+several genera, while others named <i>Protorosaurus</i> are met with in the
+Zechstein of Thuringia. This family of reptiles is allied to the living
+monitor, and its appearance in a primary or paleozoic formation, observes
+Mr. Owen, is opposed to the doctrine of the progressive development of
+reptiles from fish, or from simpler to more complex forms; for, if they
+existed at the present day, these monitors would take rank at the head of
+the Lacertian order.<a name="FNanchor_Y_5" id="FNanchor_Y_5"></a><a href="#Footnote_Y_5" class="fnanchor">[306-B]</a></p>
+
+<p>In Russia the Permian rocks are composed of white limestone, with gypsum
+and white salt; and of red and green grits, with occasionally copper ore;
+also magnesian limestones, marlstones, and conglomerates.</p>
+
+<p>The country of Mansfeld, in Thuringia, may be called the classic ground of
+the Lower New Red, or Magnesian Limestone, or Permian formation, on the
+Continent. It consists there principally of, first, the Zechstein,
+corresponding to the upper portion of our English series; and, secondly,
+the marl-slate, with fish of species identical with those of the bed so
+called in Durham. This slaty marlstone is richly impregnated with copper
+pyrites, for which it is extensively worked. Magnesian limestone, gypsum,
+and rock-salt, occur among the superior strata of this group. At its base
+lies the Rothliegendes, supposed to correspond with the Inferior or Lower
+New Red Sandstone <span class="pagenum"><a id="page307"></a>[p.307]</span>above mentioned, which occupies a similar place
+in England between the marl-slate and coal. Its local name of
+Rothliegendes, <i>red-lyer</i>, or "Roth-todt-liegendes," <i>red-dead-lyer</i>, was
+given by the workmen in the German mines from its red colour, and because
+the copper has <i>died out</i> when they reach this rock, which is not
+metalliferous. It is, in fact, a great deposit of red sandstone and
+conglomerate, with associated porphyry, basaltic trap, and amygdaloid.</p>
+
+<p><i>Permian Flora.</i>&mdash;We learn from the recent investigation of Colonel von
+Gutbier, that in the Permian rocks of Saxony no less than sixty species of
+fossil plants have been met with, forty of which have not yet been found
+elsewhere. Two or three of these, as <i>Calamites gigas</i>, <i>Sphenopteris
+erosa</i>, and <i>S. lobata</i>, are also met with in the government of Perm in
+Russia. Seven others, and among them <i>Neuropteris Loshii</i>, <i>Pecopteris
+arborescens</i>, and <i>P. similis</i>, with several species of <i>Walchia</i>
+(Lycopodites), are common to the coal-measures.</p>
+
+<p>Among the genera also enumerated by Colonel Gutbier are <i>Asterophyllites</i>
+and <i>Annularia</i>, so characteristic of the carboniferous period; also
+<i>Lepidodendron</i>, which is common to the Permian of Saxony, Thuringia, and
+Russia, although not abundant. <i>Noeggerathia</i> (see <a href="#img334">fig. 350.</a>), supposed by
+A. Brongniart to be allied to <i>Cycas</i>, is another link between the Permian
+and carboniferous vegetation. Conifer�, of the Araucarian division, also
+occur; but these are likewise met with both in older and newer rocks. The
+plants called <i>Sigillaria</i> and <i>Stigmaria</i>, so marked a feature in the
+carboniferous period, are as yet wanting.</p>
+
+<a id="img334" name="img334"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 350.</p>
+<img src="images/img334.jpg" width="150" height="386" alt="" title="">
+<p><i>Noeggerathia cuneifolia.</i> Ad. Brongniart.<a name="FNanchor_Y_6" id="FNanchor_Y_6"></a><a href="#Footnote_Y_6" class="fnanchor">[307-A]</a></p></div>
+
+<p>Among the remarkable fossils of the rothliegendes, or lowest part of the
+Permian in Saxony and Bohemia, are the silicified trunks of tree-ferns
+called generically <i>Psaronius</i>. Their bark was surrounded by a dense mass
+of air-roots, which often constituted a great addition to the original
+stem, so as to double or quadruple its diameter. The same remark holds good
+in regard to certain living extra-tropical arborescent ferns, particularly
+those of New Zealand.</p>
+
+<p>Psaronites are also found in the uppermost coal of Autun in France, and in
+the upper coal-measures of the State of Ohio in the United States, but
+specifically different from those of the rothliegendes. They serve to
+connect the Permian flora with the more modern portion of the preceding or
+carboniferous group. Upon the whole, it is <span class="pagenum"><a id="page308"></a>[p.308]</span>evident that the
+Permian plants approach nearer to the carboniferous ones than to the
+triassic; and the same may be said of the Permian fauna.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XXIV.</h2>
+
+<h4>THE COAL, OR CARBONIFEROUS GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">Carboniferous strata in the south-west of England &mdash; Superposition of
+Coal-measures to Mountain limestone &mdash; Departure from this type in North
+of England and Scotland &mdash; Section in South Wales &mdash; Underclays with
+Stigmaria &mdash; Carboniferous Flora &mdash; Ferns, Lepidodendra, Calamites,
+Asterophyllites, Sigillari�,Stigmari� &mdash; Conifer� &mdash; Endogens
+&mdash; Absence of Exogens &mdash; Coal, how formed &mdash; Erect fossil
+trees &mdash; Parkfield Colliery &mdash; St. Etienne, Coal-field &mdash;
+Oblique trees or snags &mdash; Fossil forests in Nova Scotia &mdash; Brackish
+water and marine strata &mdash; Origin of Clay-iron-stone.</p></div>
+
+
+<p><span class="smcap">The</span> next group which we meet with in the descending order is the
+Carboniferous, commonly called "The Coal;" because it contains many beds of
+that mineral, in a more or less pure state, interstratified with
+sandstones, shales, and limestones. The coal itself, even in Great Britain
+and Belgium, where it is most abundant, constitutes but an insignificant
+portion of the whole mass. In the north of England, for example, the
+thickness of the coal-bearing strata has been estimated at 3000 feet, while
+the various coal-seams, 20 or 30 in number, do not in the aggregate exceed
+60 feet.<a name="FNanchor_Z_1" id="FNanchor_Z_1"></a><a href="#Footnote_Z_1" class="fnanchor">[308-A]</a></p>
+
+<p>The carboniferous formation comprises two very distinct members: 1st, that
+usually called the Coal-measures, of mixed freshwater, terrestrial, and
+marine origin, often including seams of coal; 2dly, that named in England
+the Mountain or Carboniferous limestone, of purely marine origin, and
+containing corals, shells, and encrinites.</p>
+
+<p>In the south-western part of our island, in Somersetshire and South Wales,
+the three divisions usually spoken of by English geologists are:</p>
+
+
+<table  border="0" cellpadding="2" summary="DIVISION OF THE CARBONIFEROUS FORMATION
+IN SOMERSETSHIRE AND SOUTH WALES.">
+<colgroup>
+    <col width="30%">
+    <col width="7%">
+    <col width="3%">
+    <col width="60%">
+</colgroup>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left2">1. Coal-measures</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 20pt; font-weight: 600;" class="tdtx-top td-center">{</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="td-left tdtx-mid tdp-left2">Strata of shale, sandstone, and grit, with occasional seams
+  of coal, from 600 to 12,000 feet thick.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left2" style="padding-top: 0.7em;">2. Millstone grit</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 40pt; font-weight: 100;" class="tdtx-top td-center">{</td>
+  <td class="td-left tdtx-mid tdp-left2">A coarse quartzose sandstone passing into a conglomerate,
+  sometimes used for millstones, with beds of shale; usually
+  devoid of coal; occasionally above 600 feet thick.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left2">3. Mountain or Carboniferous limestone</td>
+  <td valign="middle" style="white-space: nowrap; font-size: 20pt; font-weight: 600;" class="tdtx-top td-center">}</td>
+  <td class="td-left tdtx-mid tdp-left2">A calcareous rock containing marine shells and corals;
+  devoid of coal; thickness variable, sometimes 900 feet.</td>
+</tr>
+</table>
+
+
+<p>The millstone grit may be considered as one of the coal sandstones
+<span class="pagenum"><a id="page309"></a>[p.309]</span>of coarser texture than usual, with some accompanying shales, in
+which coal plants are occasionally found. In the north of England some
+bands of limestone, with pectens, oysters, and other marine shells, occur
+in this grit, just as in the regular coal-measures, and even a few seams of
+coal. I shall treat, therefore, of the whole group, as consisting of two
+divisions only, the Coal-measures and Mountain Limestone. The latter is
+found in the southern British coal-fields, at the base of the system, or
+immediately in contact with the subjacent Old Red Sandstone; but as we
+proceed northwards to Yorkshire and Northumberland it begins to alternate
+with true coal-measures, the two deposits forming together a series of
+strata about 1000 feet in thickness. To this mixed formation succeeds the
+great mass of genuine mountain limestone.<a name="FNanchor_Z_2" id="FNanchor_Z_2"></a><a href="#Footnote_Z_2" class="fnanchor">[309-A]</a> Farther north, in the
+Fifeshire coal-field in Scotland, we observe a still wider departure from
+the type of the south of England, or a more complete intercalation of dense
+masses of marine limestones with sandstones, and shales containing coal.</p>
+
+
+<h3>COAL-MEASURES.</h3>
+
+<p>In South Wales the coal-measures have been ascertained by actual
+measurement to attain the extraordinary thickness of 12,000 feet, the beds
+throughout, with the exception of the coal itself, appearing to have been
+formed in water of moderate depth, during a slow but perhaps intermittent
+depression of the ground, in a region to which rivers were bringing a
+never-failing supply of muddy sediment and sand. The same area was
+sometimes covered with vast forests, such as we see in the deltas of great
+rivers in warm climates, which are liable to be submerged beneath fresh or
+salt water should the ground sink vertically a few feet.</p>
+
+<p>In one section near Swansea, in South Wales, where the total thickness of
+strata is 3246 feet, we learn from Sir H. De la Beche that there are ten
+principal masses of sandstone. One of these is 500 feet thick, and the
+whole of them make together a thickness of 2125 feet. They are separated by
+masses of shale, varying in thickness from 10 to 50 feet. The intercalated
+coal-beds, sixteen in number, are generally from 1 to 5 feet thick, one of
+them, which has two or three layers of clay interposed, attaining 9
+feet.<a name="FNanchor_Z_3" id="FNanchor_Z_3"></a><a href="#Footnote_Z_3" class="fnanchor">[309-B]</a> At other points in the same coal-field the shales predominate
+over the sandstones. The horizontal extent of some seams of coal is much
+greater than that of others, but they all present one characteristic
+feature, in having, each of them, what is called its <i>underclay</i>. These
+underclays, co-extensive with every layer of coal, consist of arenaceous
+shale, sometimes called firestone, because it can be made into bricks which
+stand the fire of <span class="pagenum"><a id="page310"></a>[p.310]</span>a furnace. They vary in thickness from 6 inches
+to more than 10 feet; and Mr. Logan first announced to the scientific world
+in 1841 that they were regarded by the colliers in South Wales as an
+essential accompaniment of each of the one hundred seams of coal met with
+in their coal-field. They are said to form the <i>floor</i> on which the coal
+rests; and some of them have a slight admixture of carbonaceous matter,
+while others are quite blackened by it.</p>
+
+<p>All of them, as Mr. Logan pointed out, are characterized by inclosing a
+peculiar species of fossil vegetable called <i>Stigmaria</i>, to the exclusion
+of other plants. It was also observed that, while in the overlying shales
+or "roof" of the coal, ferns and trunks of trees abound without any
+<i>Stigmari�</i>, and are flattened and compressed, those singular plants in the
+underclays always retain their natural forms, branching freely, and sending
+out their slender leaves, as they were formerly styled, through the mud in
+all directions. Several species of <i>Stigmaria</i> had long been known to
+botanists, and described by them, before their position under each seam of
+coal was pointed out. It was conjectured that they might be aquatic,
+perhaps floating plants, which sometimes extended their branches and leaves
+freely in fluid mud, and which were finally enveloped in the same mud.</p>
+
+
+<h3>CARBONIFEROUS FLORA.</h3>
+
+<p>These statements will suffice to convince the reader that we cannot arrive
+at a satisfactory theory of the origin of coal till we understand the true
+nature of <i>Stigmaria</i>; and in order to explain what is now known of this
+plant, and of others which have contributed by their decay to produce coal,
+it will be necessary to offer a brief preliminary sketch of the whole
+carboniferous flora, an assemblage of fossil plants, with which we are
+better acquainted than with any other which flourished antecedently to the
+tertiary epoch. It should also be remarked that G�ppert has ascertained
+that the remains of every family of plants scattered through the
+coal-measures are sometimes met with in the pure coal itself, a fact which
+adds greatly to the geological interest attached to this flora.</p>
+
+<p><i>Ferns.</i>&mdash;The number of species of carboniferous plants hitherto described
+amounts, according to M. Ad. Brongniart, to about 500. These may perhaps be
+a fragment only of the entire flora, but they are enough to show that the
+state of the vegetable world was then extremely different from that now
+established. We are struck at the first glance with the similarity of many
+of the ferns to those now living, and the dissimilarity of almost all the
+other fossils except the conifer�. Among the ferns, as in the case of
+<i>Pecopteris</i> for example (<a href="#img335">fig. 351.</a>), it is not always easy to decide
+whether they should be referred to different genera from those established
+for the classification of living species; whereas, in regard to most of the
+other contemporary tribes, with the exception of the conifer�, it is often
+difficult <span class="pagenum"><a id="page311"></a>[p.311]</span>to guess the family, or even the class, to which they
+belong. The ferns of the carboniferous period are generally without organs
+of fructification, but in some specimens these are well preserved. In the
+general absence of such characters, they have been divided into genera,
+distinguished chiefly by the branching of the fronds, and the way in which
+the veins of the leaves are disposed. The larger portion are supposed to
+have been of the size of ordinary European ferns, but some were decidedly
+arborescent, especially the group called <i>Caulopteris</i>, by Lindley, and the
+<i>Psaronius</i> of the upper or newest coal-measures, before alluded to (<a href="#page307">p.
+307.</a>).</p>
+
+<a id="img335" name="img335"></a>
+<div class="floatleft smaller width150">
+<p>Fig. 351.</p>
+<img src="images/img335.jpg" width="150" height="341" alt="" title="">
+<p><i>Pecopteris lonchitica.</i> (Foss. Flo. 153.)</p></div>
+
+<a id="img336" name="img336"></a>
+<div class="floatright smaller width200">
+<p>Fig. 352.</p>
+<img src="images/img336.jpg" width="200" height="341" alt="" title="">
+<ul class="smaller leftal add3em min1em">
+<li><i>a.</i> <i>Sphenopteris crenata.</i></li>
+<li><i>b.</i> The same, magnified.</li>
+</ul>
+<p class="martopm05">(Foss. Flo. 101.)</p></div>
+
+<a id="img337" name="img337"></a>
+<div class="nofloat figcenter smaller width200">
+<p>Fig. 353.</p>
+<img src="images/img337.jpg" width="200" height="299" alt="" title="">
+<p><i>Caulopteris prim�va</i>, Lindley.</p></div>
+
+<p>All the recent tree-ferns belong to one tribe (<i>Polypodiace�</i>), and to a
+small number only of genera in that tribe, in which the surface of the
+trunk is marked with scars, or cicatrices, left after the fall of the
+fronds. These scars resemble those of <i>Caulopteris</i> (see <a href="#img337">fig. 353.</a>). No
+less than 250 ferns have already been obtained from the coal strata; and
+even if we make some reduction on the ground of varieties which have been
+mistaken, in the absence of their fructification, for species, still the
+result is singular, because the whole of Europe affords at present no more
+than 50 indigenous species.</p>
+
+<span class="pagenum"><a id="page312"></a>[p.312]</span>
+<a id="img338" name="img338"></a>
+<div class="figcenter smaller width400">
+<img src="images/img338.jpg" width="400" height="386" alt="" title="">
+<p>Living tree-ferns of different <span class="wosp05">genera. (Ad.</span> Brong.)</p>
+<ul class="smaller martopm05 leftal add1em min1em">
+<li>Fig. 354. Tree-fern from Isle of Bourbon.</li>
+<li>Fig. 355. <i>Cyathea glauca</i>, Mauritius.</li>
+<li>Fig. 356. Tree fern from Brazil.</li>
+</ul></div>
+
+<a id="img339" name="img339"></a>
+<div class="figcenter smaller width400">
+<img src="images/img339.jpg" width="400" height="270" alt="" title="">
+<p><i>Lepidodendron Sternbergii</i><span class="wosp05">. Coal-measures,</span>
+near Newcastle.</p>
+<ul class="smaller leftal martopm05 add1em min3em">
+<li>Fig. 357. Branching trunk, 49 feet long, supposed to have belonged to
+<i>L. Sternbergii</i>. (Foss. Flo. 203.)</li>
+<li>Fig. 358. Branching stem with bark and leaves of <i>L. Sternbergii</i>.
+(Foss. Flo. 4.)</li>
+<li>Fig. 359. Portion of same nearer the root; natural size. (Ibid.)</li>
+</ul></div>
+
+<p><i>Lepidodendra.</i>&mdash;These fossils belong to the family of <i>Lycopodiums</i>, yet
+most of them grew to the size of large trees. The annexed figures represent
+a large fossil <i>Lepidodendron</i>, 49 feet long, found in Jarrow Colliery,
+near Newcastle, lying in shale parallel to the planes of stratification.
+Fragments of others, found in the same shale, indicate, by the size of the
+rhomboidal scars which cover them, a still greater magnitude. The living
+club-mosses, of which there are about 200 species, are abundant in tropical
+climates, where one species is sometimes met with attaining a height of 3
+feet. They usually creep on <span class="pagenum"><a id="page313"></a>[p.313]</span>the ground, but some stand erect, as
+the <i>L. densum</i>, from New Zealand (<a href="#img340">fig. 360.</a>).</p>
+
+<a id="img340" name="img340"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 360.</p>
+<img src="images/img340.jpg" width="400" height="274" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Lycopodium densum</i>; banks of R. Thames, New Zealand.</li>
+<li><i>b.</i> branch, natural size.</li>
+<li><i>c.</i> part of same, magnified.</li>
+</ul></div>
+
+<p>In the carboniferous strata of Coalbrook Dale, and in many other
+coal-fields, elongated cylindrical bodies, called fossil cones, named by M.
+Adolphe Brongniart <i>Lepidostrobus</i>, are met with. (See <a href="#img341">fig. 361.</a>) They
+often form the nucleus of concretionary balls of clay-iron-stone, and are
+well preserved, exhibiting a conical axis, around which a great quantity of
+scales were compactly imbricated. The opinion of M. Brongniart is now
+generally adopted, that the <i>Lepidostrobus</i> is the fruit of
+<i>Lepidodendron</i>.</p>
+
+<a id="img341" name="img341"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 361.</p>
+<img src="images/img341.jpg" width="400" height="069" alt="" title="">
+<p><i>Lepidostrobus ornatus</i>, Brong.; half nat. <span class="wosp05">size.
+Shropshire.</span></p></div>
+
+<a id="img342" name="img342"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 362.</p>
+<img src="images/img342.jpg" width="250" height="218" alt="" title="">
+<p><i>Calamites cann�formis</i>, Schlot. (Foss. Flo. <span class="wosp05">79.)
+Lower</span> end with rootlets.</p></div>
+
+<a id="img343" name="img343"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 363.</p>
+<img src="images/img343.jpg" width="250" height="258" alt="" title="">
+<p><i>Calamites Suckowii</i>, Brong.; natural <span class="wosp05">size. Common</span>
+in coal throughout Europe.</p></div>
+
+<p><i>Equisetace�.</i>&mdash;To this family belong two species of the genus
+<i>Equisetites</i>, allied to the living "horse-tail" which now grows in marshy
+grounds. Other species, which have jointed stems, depart more widely from
+<i>Equisetum</i>, but are yet of analogous organization. <span class="pagenum"><a id="page314"></a>[p.314]</span>They differed
+from it principally in being furnished with a thin bark, which is
+represented in the stem of <i>C. Suckowii</i> (<a href="#img343">fig. 363.</a>), in which it will be
+seen that the striped external pattern does not agree with that left on the
+stone where the bark is stripped off; so that if the two impressions were
+seen separately, they might be mistaken for two distinct species.</p>
+
+<p>The tallest living "horse-tails" are only 2 or 3 feet high in Europe, and
+even in tropical climates only attain, as in the case of <i>Equisetum
+giganteum</i>, discovered by Humboldt and Bonpland, in South America, a height
+of about 5 feet, the stem being an inch in diameter. Several of the
+Calamites of the coal acquired the height and dimensions of small trees.</p>
+
+<a id="img344" name="img344"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 364.</p>
+<img src="images/img344.jpg" width="400" height="255" alt="" title="">
+<p><i>Asterophyllites foliosa</i><span class="wosp05">. (Foss.</span> Flo. <span class="wosp05">25.)
+Coal-measures,</span> Newcastle.</p></div>
+
+<p><i>Asterophyllites.</i>&mdash;In this family, M. Brongniart includes several genera,
+and among them <i>Calamodendron</i>, <i>Asterophyllites</i>, and <i>Annularia</i>. The
+graceful plant, represented in the annexed figure, is supposed to be the
+branch of a shrub called <i>Calamodendron</i>, a new genus, divided off by
+Brongniart from the <i>Calamites</i> of former authors. Its pith and medullary
+rays seem to show that it was dicotyledonous, and it appears to have been
+allied, by the nature of its tissue, to the gymnogens, or, still more, to
+the <i>Sigillaria</i>, which will next be mentioned.</p>
+
+<p><i>Sigillaria.</i>&mdash;A large portion of the trees of the carboniferous period
+belonged to this genus, of which about thirty-five species are known. The
+structure, both internal and external, was very peculiar, and, with
+reference to existing types, very anomalous. They were formerly referred,
+by M. Ad. Brongniart, to ferns, which they resemble in the scalariform
+texture of their vessels, and, in some degree, in the form of the
+cicatrices left by the base of the leafstalks which have fallen off (see
+<a href="#img345">fig. 365.</a>). But with these points of analogy to cryptogamia, they combine
+an internal organization much resembling that of cycads, and some of them
+are ascertained to have had long linear leaves, quite unlike those of
+ferns. They grew to a great height, from 30 to 60, or even 70 feet, with
+regular cylindrical stems, and without branches, although some species were
+<span class="pagenum"><a id="page315"></a>[p.315]</span>dichotomous towards the top. Their fluted trunks, from 1 to 5
+feet in diameter, appear to have decayed rapidly in the interior, so as to
+become hollow, when standing; when, therefore, they were thrown prostrate
+on the mud, they were squeezed down and flattened. Hence, we find the bark
+of the two opposite sides (now converted into bright shining coal) to
+constitute two horizontal layers, one upon the other, half an inch, or an
+inch, in thickness. These same trunks, when they are placed obliquely or
+vertically to the planes of stratification, retain their original rounded
+form, and are uncompressed, the cylinder of bark having been filled with
+sand, which now affords a cast of the interior.</p>
+
+<a id="img345" name="img345"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 365.</p>
+<img src="images/img345.jpg" width="250" height="401" alt="" title="">
+<p><i>Sigillaria l�vigata</i>, Brong.</p></div>
+
+<p><i>Stigmaria.</i>&mdash;This fossil, the importance of which has already been pointed
+out, was formerly conjectured to be an aquatic plant. It is now ascertained
+to be the root of <i>Sigillaria</i>. The connection of the roots with the stem,
+previously suspected, on botanical grounds, by Brongniart, was first
+proved, by actual contact, in the Lancashire coal-field, by Mr. Binney. The
+fact has lately been shown, even more distinctly, by Mr. Richard Brown, in
+his description of the <i>Stigmari�</i> occurring in the underclays of the
+coal-seams of the Island of Cape Breton, in Nova Scotia.</p>
+
+<a id="img346" name="img346"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 366.</p>
+<img src="images/img346.jpg" width="450" height="172" alt="" title="">
+<p>Stigmaria attached to a trunk of <i>Sigillaria</i>.<a name="FNanchor_Z_4" id="FNanchor_Z_4"></a><a href="#Footnote_Z_4" class="fnanchor">[315-A]</a></p></div>
+
+<p>In a specimen of one of these, represented in the annexed figure (<a href="#img346">fig.
+366.</a>), the spread of the roots was 16 feet, and some of them sent out
+rootlets, in all directions, into the surrounding clay.</p>
+
+<p>The manner of attachment of the fibres to the stem resembles that of a ball
+and socket joint, the base of each rootlet being concave, and fitting on to
+a tubercle (see <a href="#img347">figs. 367</a> and <a href="#img348">368.</a>). Rows of these tubercles are arranged
+spirally round each root, which have always a medullary cavity and woody
+texture, much resembling that <span class="pagenum"><a id="page316"></a>[p.316]</span>of <i>Sigillaria</i>, the structure of
+the vessels being, like it, scalariform.</p>
+
+<a id="img347" name="img347"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 367.</p>
+<img src="images/img347.jpg" width="150" height="068" alt="" title="">
+<p>Surface of another individual of same species,
+showing form of <span class="wosp05">tubercles. (Foss.</span> Flo. 34.)</p></div>
+
+<a id="img348" name="img348"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 368.</p>
+<img src="images/img348.jpg" width="350" height="204" alt="" title="">
+<p><i>Stigmaria ficoides</i>, <span class="wosp05">Brong. One</span> fourth of nat.
+<span class="wosp05">size. (Foss.</span> Flo. 32.)</p></div>
+
+<p><i>Conifers.</i>&mdash;The coniferous trees of this period are referred to five
+genera; the woody structure of some of them showing that they were allied
+to the Araucarian division of pines, more than to any of our common
+European firs. Some of their trunks exceeded 44 feet in height.</p>
+
+<p><i>Endogens.</i>&mdash;Hitherto but few monocotyledonous plants have been discovered
+in the coal-strata. Most of these consist of fruits referred by some
+botanists to palms. The three-sided nuts, called <i>Trigonocarpum</i>, seven
+species of which are known, appear to have the best claim to rank as palms,
+although M. Ad. Brongniart entertains some doubt even as to their being
+monocotyledons.</p>
+
+
+<h3><i>Exogens.</i></h3>
+
+<p>The entire absence, so far as our paleontological investigations have
+hitherto gone, of ordinary dicotyledons or exogens in the coal measures, is
+most remarkable. Hence, M. Adolphe Brongniart has called this period the
+age of acrogens, in consequence of the vast preponderance of ferns and
+<i>Lepidodendra</i>.<a name="FNanchor_Z_5" id="FNanchor_Z_5"></a><a href="#Footnote_Z_5" class="fnanchor">[316-A]</a> Nevertheless, a forest of the period, now under
+consideration, may have borne a considerable resemblance to those woody
+regions of New Zealand, in which ferns, arborescent and herbaceous, and
+lycopodiums, with many conifer�, abound.</p>
+
+<p>The comparative proportion of living ferns and <i>Araucari�</i>, in Norfolk
+Island, to all the other plants, appears to be very similar to that
+formerly borne by these tribes respectively in a forest of the coal-period.</p>
+
+<p>I have already stated that Professor G�ppert, after examining the fossil
+vegetables of the coal-fields of Germany, has detected, in beds of pure
+coal, remains of plants of every family hitherto known to occur fossil in
+the coal. Many seams, he remarks, are rich in <i>Sigillaria</i>,
+<i>Lepidodendron</i>, and <i>Stigmaria</i>, the latter in such abundance, as to
+appear to form the bulk of the coal. In some places, almost all the plants
+are calamites, in others ferns.<a name="FNanchor_Z_6" id="FNanchor_Z_6"></a><a href="#Footnote_Z_6" class="fnanchor">[316-B]</a></p>
+
+<p><span class="pagenum"><a id="page317"></a>[p.317]</span><i>Coal, how formed&mdash;Erect trees.</i>&mdash;I shall now consider the manner
+in which the above-mentioned plants are imbedded in the strata, and how
+they may have contributed to produce coal. "Some of the plants of our
+coal," says Dr. Buckland, "grew on the identical banks of sand, silt, and
+mud, which, being now indurated to stone and shale, form the strata that
+accompany the coal; whilst other portions of these plants have been drifted
+to various distances from the swamps, savannahs, and forests that gave them
+birth, particularly those that are dispersed through the sandstones, or
+mixed with fishes in the shale beds." "At Balgray, three miles north of
+Glasgow," says the same author, "I saw in the year 1824, as there still may
+be seen, an unequivocal example of the stumps of several stems of large
+trees, standing close together in their native place, in a quarry of
+sandstone of the coal formation."<a name="FNanchor_Z_7" id="FNanchor_Z_7"></a><a href="#Footnote_Z_7" class="fnanchor">[317-A]</a></p>
+
+<p>Between the years 1837 and 1840, six fossil trees were discovered in the
+coal-field of Lancashire, where it is intersected by the Bolton railway.
+They were all in a vertical position, with respect to the plane of the bed,
+which dips about 15� to the south. The distance between the first and the
+last was more than 100 feet, and the roots of all were imbedded in a soft
+argillaceous shale. In the same plane with the roots is a bed of coal,
+eight or ten inches thick, which has been ascertained to extend across the
+railway, or to the distance of at least ten yards. Just above the covering
+of the roots, yet beneath the coal seam, so large a quantity of the
+<i>Lepidostrobus variabilis</i> was discovered inclosed in nodules of hard clay,
+that more than a bushel was collected from the small openings around the
+base of the trees (see figure of this genus, <a href="#page313">p. 313.</a>). The exterior trunk
+of each was marked by a coating of friable coal, varying from one quarter
+to three quarters of an inch in thickness; but it crumbled away on removing
+the matrix. The dimensions of one of the trees is 15<span class="smaller"><sup>1</sup>/<sub>2</sub></span> feet in
+circumference at the base, 7<span class="smaller"><sup>1</sup>/<sub>2</sub></span> feet at the top, its height being 11 feet.
+All the trees have large spreading roots, solid and strong, sometimes
+branching, and traced to a distance of several feet, and presumed to extend
+much farther. Mr. Hawkshaw, who has described these fossils, thinks that,
+although they were hollow when submerged, they may have consisted
+originally of hard wood throughout; for solid dicotyledonous trees, when
+prostrated in tropical forests, as in Venezuela, on the shore of the
+Caribbean Sea, were observed by him to be destroyed in the interior, so
+that little more is left than an outer shell, consisting chiefly of the
+bark. This decay, he says, goes on most rapidly in low and flat tracks, in
+which there is a deep rich soil and excessive moisture, supporting tall
+forest-trees and large palms, below which bamboos, canes, and minor palms
+flourish luxuriantly. Such tracts, from their lowness, would be most easily
+submerged, and their dense vegetation might then give rise to a seam of
+coal.<a name="FNanchor_Z_8" id="FNanchor_Z_8"></a><a href="#Footnote_Z_8" class="fnanchor">[317-B]</a></p>
+
+<p>In a deep valley near Capel-Coelbren, branching from the higher part of the
+Swansea valley, four stems of upright <i>Sigillari�</i> were <span class="pagenum"><a id="page318"></a>[p.318]</span>seen, in
+1838, piercing through the coal-measures of S. Wales; one of them was 2
+feet in diameter, and one 13 feet and a half high, and they were all found
+to terminate downwards in a bed of coal. "They appear," says Sir H. De la
+Beche, "to have constituted a portion of a subterranean forest at the epoch
+when the lower carboniferous strata were formed.<a name="FNanchor_Z_9" id="FNanchor_Z_9"></a><a href="#Footnote_Z_9" class="fnanchor">[318-A]</a></p>
+
+<p>In a colliery near Newcastle, say the authors of the Fossil Flora, a great
+number of <i>Sigillari�</i> were placed in the rock as if they had retained the
+position in which they grew. Not less than thirty, some of them 4 or 5 feet
+in diameter, were visible within an area of 50 yards square, the interior
+being sandstone, and the bark having been converted into coal. The roots of
+one individual were found imbedded in shale; and the trunk, after
+maintaining a perpendicular course and circular form for the height of
+about 10 feet, was then bent over so as to become horizontal. Here it was
+distended laterally, and flattened so as to be only one inch thick, the
+flutings being comparatively distinct.<a name="FNanchor_Z_10" id="FNanchor_Z_10"></a><a href="#Footnote_Z_10" class="fnanchor">[318-B]</a> Such vertical stems are
+familiar to our miners, under the name of coal-pipes. One of them, 72 feet
+in length, was discovered, in 1829, near Gosforth, about five miles from
+Newcastle, in coal-grit, the strata of which it penetrated. The exterior of
+the trunk was marked at intervals with knots, indicating the points at
+which branches had shot off. The wood of the interior had been converted
+into carbonate of lime; and its structure was beautifully shown by cutting
+transverse slices, so thin as to be transparent. (See <a href="#page40">p. 40.</a>)</p>
+
+<p>These "coal-pipes" are much dreaded by our miners, for almost every year in
+the Bristol, Newcastle, and other coal-fields, they are the cause of fatal
+accidents. Each cylindrical cast of a tree, formed of solid sandstone, and
+increasing gradually in size towards the base, and being without branches,
+has its whole weight thrown downwards, and receives no support from the
+coating of friable coal which has replaced the bark. As soon, therefore, as
+the cohesion of this external layer is overcome, the heavy column falls
+suddenly in a perpendicular or oblique direction from the roof of the
+gallery whence coal has been extracted, wounding or killing the workman who
+stands below. It is strange to reflect how many thousands of these trees
+fell originally in their native forests in obedience to the law of gravity;
+and how the few which continued to stand erect, obeying, after myriads of
+ages, the same force, are cast down to immolate their human victims.</p>
+
+<p>It has been remarked, that if, instead of working in the dark, the miner
+was accustomed to remove the upper covering of rock from each seam of coal,
+and to expose to the day the soils on which ancient forests grew, the
+evidence of their former growth would be obvious. Thus in South
+Staffordshire a seam of coal was laid bare in the year 1844, in what is
+called an open work at Parkfield Colliery, near <span class="pagenum"><a id="page319"></a>[p.319]</span>Wolverhampton. In
+the space of about a quarter of an acre the stumps of no less than 73 trees
+with their roots attached appeared, as shown in the annexed plan (<a href="#img349">fig.
+369.</a>), some of them more than 8 feet in circumference. The trunks, broken
+off close to the root, were lying prostrate in every direction, often
+crossing each other. One of them measured 15, another 30 feet in length,
+and others less. They were invariably flattened to the thickness of one or
+two inches, and converted into coal. Their roots formed part of a stratum
+of coal 10 inches thick, which rested on a layer of clay 2 inches thick,
+below which was a second forest, resting on a 2-foot seam of coal. Five
+feet below this again was a third forest with large stumps of
+<i>Lepidodendra</i>, <i>Calamites</i>, and other trees.</p>
+
+<a id="img349" name="img349"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 369.</p>
+<img src="images/img349.jpg" width="350" height="275" alt="" title="">
+<p>Ground-plan of a fossil forest, Parkfield Colliery, near Wolverhampton,
+showing the position of 73 trees in a quarter of an acre.<a name="FNanchor_Z_11" id="FNanchor_Z_11"></a><a href="#Footnote_Z_11" class="fnanchor">[319-A]</a></p></div>
+
+<p>In the account given, in 1821, by M. Alex. Brongniart of the coal-mine of
+Treuil, at St. Etienne, near Lyons, he states, that distinct horizontal
+strata of micaceous sandstone are traversed by vertical trunks of
+monocotyledonous vegetables, resembling bamboos or large <i>Equiseta</i>.<a name="FNanchor_Z_12" id="FNanchor_Z_12"></a><a href="#Footnote_Z_12" class="fnanchor">[319-B]</a>
+Since the consolidation of the stone, there has been here and there a
+sliding movement, which has broken the continuity of the stems, throwing
+the upper parts of them on one side, so that they are often not continuous
+with the lower.</p>
+
+<p>From these appearances it was inferred that we have here the monuments of a
+submerged forest. I formerly objected to this conclusion, suggesting that,
+in that case, all the roots ought to have been found at one and the same
+level, and not scattered irregularly through the mass. I also imagined that
+the soil to which the roots were attached should have been different from
+the sandstone in which the trunks are enclosed. Having, however, seen
+calamites near Pictou, in Nova Scotia, buried at various heights in
+sandstone and in similar erect attitudes, I have now little doubt that M.
+Brongniart's view <span class="pagenum"><a id="page320"></a>[p.320]</span>was correct. These plants seem to have grown on
+a sandy soil, liable to be flooded from time to time, and raised by new
+accessions of sediment, as may happen in swamps near the banks of a large
+river in its delta. Trees which delight in marshy grounds are not injured
+by being buried several feet deep at their base; and other trees are
+continually rising up from new soils, several feet above the level of the
+original foundation of the morass. In the banks of the Mississippi, when
+the water has fallen, I have seen sections of a similar deposit in which
+portions of the stumps of trees with their roots <i>in situ</i> appeared at many
+different heights.<a name="FNanchor_Z_13" id="FNanchor_Z_13"></a><a href="#Footnote_Z_13" class="fnanchor">[320-A]</a></p>
+
+<a id="img350" name="img350"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 370.</p>
+<img src="images/img350.jpg" width="450" height="416" alt="" title="">
+<p>Section showing the erect position of fossil trees
+in coal sandstone at St. <span class="wosp05">Etienne. (Alex.</span> Brongniart.)</p></div>
+
+<p>When I visited, in 1843, the quarries of Treuil above-mentioned, the fossil
+trees seen in <a href="#img350">fig. 370.</a> were removed, but I obtained proofs of other
+forests of erect trees in the same coal-field.</p>
+
+<a id="img351" name="img351"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 371.</p>
+<img src="images/img351.jpg" width="300" height="212" alt="" title="">
+<p>Inclined position of a fossil tree, cutting through horizontal beds
+of sandstone, Craigleith quarry, <span class="wosp05">Edinburgh. Angle</span>
+of inclination from <i>a</i> to <i>b</i> 27�.</p></div>
+
+<p><i>Snags.</i>&mdash;In 1830, a slanting trunk was exposed in Craigleith quarry, near
+Edinburgh, the total length of which exceeded 60 feet. Its diameter at the
+top was about 7 inches, and near the base it measured 5 feet in its
+greater, and 2 feet in its lesser width. The bark was converted into a thin
+coating of the purest and finest coal, forming a striking contrast in
+colour with the white quartzose sandstone in which it lay. The annexed
+figure represents a portion of this tree, about 15 feet long, which I saw
+exposed in 1830, when <span class="pagenum"><a id="page321"></a>[p.321]</span>all the strata had been removed from one
+side. The beds which remained were so unaltered and undisturbed at the
+point of junction, as clearly to show that they had been tranquilly
+deposited round the tree, and that the tree had not subsequently pierced
+through them, while they were yet in a soft state. They were composed
+chiefly of siliceous sandstone, for the most part white; and divided into
+lamin� so thin, that from six to fourteen of them might be reckoned in the
+thickness of an inch. Some of these thin layers were dark, and contained
+coaly matter; but the lowest of the intersected beds were calcareous. The
+tree could not have been hollow when imbedded, for the interior still
+preserved the woody texture in a perfect state, the petrifying matter
+being, for the most part, calcareous.<a name="FNanchor_Z_14" id="FNanchor_Z_14"></a><a href="#Footnote_Z_14" class="fnanchor">[321-A]</a> It is also clear, that the
+lapidifying matter was not introduced laterally from the strata through
+which the fossil passes, as most of these were not calcareous. It is well
+known that, in the Mississippi and other great American rivers, where
+thousands of trees float annually down the stream, some sink with their
+roots downwards, and become fixed in the mud. Thus placed, they have been
+compared to a lance in rest; and so often do they pierce through the bows
+of vessels which run against them, that they render the navigation
+extremely dangerous. Mr. Hugh Miller mentions four other huge trunks
+exposed in quarries near Edinburgh, which lay diagonally across the strata
+at an angle of about 30�, with their lower or heavier portions downwards,
+the roots of all, save one, rubbed off by attrition. One of these was 60
+and another 70 feet in length, and from 4 to 6 feet in diameter.</p>
+
+<a id="img352" name="img352"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 372.</p>
+<img src="images/img352.jpg" width="500" height="057" alt="" title="">
+<p>Section of the cliffs of the South Joggins, near Minudie, Nova Scotia.</p></div>
+
+<p>The number of years for which the trunks of trees, when constantly
+submerged, can resist decomposition, is very great; as we might suppose
+from the durability of wood, in artificial piles, permanently covered by
+water. Hence these fossil snags may not imply a rapid accumulation of beds
+of sand, although the channel of a river or part of a lagoon is often
+filled up in a very few years.</p>
+
+<p><i>Nova Scotia.</i>&mdash;One of the finest examples in the world of a succession of
+fossil forests of the carboniferous period, laid open to view in a natural
+section, is that seen in the lofty cliffs bordering the Chignecto Channel,
+a branch of the Bay of Fundy, in Nova Scotia.<a name="FNanchor_Z_15" id="FNanchor_Z_15"></a><a href="#Footnote_Z_15" class="fnanchor">[321-B]</a></p>
+
+
+<p><span class="pagenum"><a id="page322"></a>[p.322]</span>In the annexed section (<a href="#img352">fig. 372.</a>), which I examined in July,
+1842, the beds from <i>c</i> to <i>i</i> are seen all dipping the same way, their
+average inclination being at an angle of 24� S.S.W. The vertical height of
+the cliffs is from 150 to 200 feet; and between <i>d</i> and <i>g</i>, in which space
+I observed seventeen trees in an upright position, or, to speak more
+correctly, at right angles to the planes of stratification, I counted
+nineteen seams of coal, varying in thickness from 2 inches to 4 feet. At
+low tide a fine horizontal section of the same beds is exposed to view on
+the beach. The thickness of the beds alluded to, between <i>d</i> and <i>g</i>, is
+about 2,500 feet, the erect trees consisting chiefly of large <i>Sigillari�</i>,
+occurring at ten distinct levels, one above the other; but Mr. Logan, who
+afterwards made a more detailed survey of the same line of cliffs, found
+erect trees at seventeen levels, extending through a vertical thickness of
+4,515 feet of strata; and he estimated the total thickness of the
+carboniferous formation, with and without coal, at no less than 14,570
+feet, every where devoid of marine organic remains.<a name="FNanchor_Z_16" id="FNanchor_Z_16"></a><a href="#Footnote_Z_16" class="fnanchor">[322-A]</a> The usual height
+of the buried trees seen by me was from 6 to 8 feet; but one trunk was
+about 25 feet high and 4 feet in diameter, with a considerable bulge at the
+base. In no instance could I detect any trunk intersecting a layer of coal,
+however thin; and most of the trees terminated downwards in seams of coal.
+Some few only were based in clay and shale, none of them in sandstone. The
+erect trees, therefore, appeared in general to have grown on beds of coal.
+In some of the underclays I observed <i>Stigmaria</i>.</p>
+
+<a id="img353" name="img353"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 373.</p>
+<img src="images/img353.jpg" width="300" height="218" alt="" title="">
+<p>Fossil tree at right angles to planes of stratification.
+Coal measures, Nova Scotia.</p></div>
+
+<p>In regard to the plants, they belonged to the same genera, and most of them
+to the same species, as those met with in the distant coal-fields of
+Europe. In the sandstone, which filled their interiors, I frequently
+observed fern leaves, and sometimes fragments of <i>Stigmaria</i>, which had
+evidently entered together with sediment after the trunk had decayed and
+become hollow, and while it was still standing under water. Thus the tree,
+<i>a b</i>, <a href="#img353">fig. 373.</a>, the same which is represented at <i>a</i>, <a href="#img354">fig. 374.</a>, or in
+the bed <i>e</i> in the larger section, <a href="#img352">fig. 372.</a>, is a hollow trunk 5 feet 8
+inches in length, traversing various strata, and cut off at the top by a
+layer of clay 2 feet thick <span class="pagenum"><a id="page323"></a>[p.323]</span>on which rests a seam of coal (<i>b</i>,
+<a href="#img354">fig. 374.</a>) 1 foot thick. On this coal again stood two large trees (<i>c</i> and
+<i>d</i>), while at a greater height the trees <i>f</i> and <i>g</i> rest upon a thin seam
+of coal (<i>e</i>), and above them is an underclay, supporting the 4-foot coal.</p>
+
+<a id="img354" name="img354"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 374.</p>
+<img src="images/img354.jpg" width="400" height="249" alt="" title="">
+<p>Erect fossil <span class="wosp05">trees. Coal-measures,</span> Nova Scotia.</p></div>
+
+<p>If we now return to the tree first mentioned (<a href="#img353">fig. 373.</a>), we find the
+diameter (<i>a b</i>) 14 inches at the top and 16 inches at the bottom, the
+length of the trunk 5 feet 8 inches. The strata in the interior consisted
+of a series entirely different from those on the outside. The lowest of the
+three outer beds which it traversed consisted of purplish and blue shale
+(<i>c</i>, <a href="#img353">fig. 373.</a>), 2 feet thick, above which was sandstone (<i>d</i>) 1 foot
+thick, and, above this, clay (<i>e</i>) 2 feet 8 inches. But, in the interior,
+were nine distinct layers of different composition: at the bottom, first,
+shale 4 inches, then sandstone 1 foot, then shale 4 inches, then sandstone
+4 inches, then shale 11 inches, then clay (<i>f</i>) with nodules of ironstone 2
+inches, then pure clay 2 feet, then sandstone 3 inches, and, lastly, clay 4
+inches. Owing to the outward slope of the face of the cliff, the section
+(<a href="#img353">fig. 373.</a>) was not exactly perpendicular to the axis of the tree; and
+hence, probably, the apparent sudden termination at the base without a
+stump and roots.</p>
+
+<p>In this example the layers of matter in the inside of the tree are more
+numerous than those without; but it is more common in the coal-measures of
+all countries to find a cylinder of pure sandstone,&mdash;the cast of the
+interior of a tree, intersecting a great many alternating beds of shale and
+sandstone, which originally enveloped the trunk as it stood erect in the
+water. Such a want of correspondence in the materials outside and inside,
+is just what we might expect if we reflect on the difference of time at
+which the deposition of sediment will take place in the two cases; the
+imbedding of the tree having gone on for many years before its decay had
+made much progress.</p>
+
+<p>The high tides of the Bay of Fundy, rising more than 60 feet, are so
+destructive as to undermine and sweep away continually the whole face of
+the cliffs, and thus a new crop of erect trees is brought into view every
+three or four years. They are known to extend over a space between two and
+three miles from north to south, and more than twice that distance from
+east to west, being seen in the banks of streams intersecting the
+coal-field.</p>
+
+<p><span class="pagenum"><a id="page324"></a>[p.324]</span>In Cape Breton, Mr. Richard Brown has observed in the Sydney
+coal-field a total thickness of coal-measures, without including the
+underlying millstone grit, of 1843 feet, dipping at an angle of 8�. He has
+published minute details of the whole series, showing at how many different
+levels erect trees occur, consisting of <i>Sigillaria</i>, <i>Lepidodendron</i>,
+<i>Calamite</i>, and other genera. In one place eight erect trunks, with roots
+and rootlets attached to them, were seen at the same level, within a
+horizontal space 80 feet in length. Beds of coal of various thickness are
+interstratified. Some of the associated strata are ripple-marked, with
+impressions of rain-drops. Taking into account forty-one clays filled with
+roots of <i>Stigmaria</i> in their natural position, and eighteen layers of
+upright trees at other levels, there is, on the whole, clear evidence of at
+least fifty-nine fossil forests, ranged one above the other, in this
+coal-field, in the above-mentioned thickness of strata.<a name="FNanchor_Z_17" id="FNanchor_Z_17"></a><a href="#Footnote_Z_17" class="fnanchor">[324-A]</a></p>
+
+<p>The fossil shells in Cape Breton and in the Nova Scotia section (<a href="#img352">fig.
+372.</a>), consisting of <i>Cypris</i>, <i>Unio</i> (?), <i>Modiola</i>, <i>Microconchus
+carbonarius</i> (see <a href="#img355">fig. 375.</a>), and <i>Spirorbis</i>, seem to indicate brackish
+water; but we ought never to be surprised if, in pursuing the same stratum,
+we come to a fresh or purely marine deposit; for this will depend upon our
+taking a direction higher up or lower down the ancient river or delta
+deposit. When the Purbeck beds of the Wealden were described in Chap.
+XVIII., I endeavoured to explain the intimate connection of strata formed
+at a river's mouth, or in the tranquil lagoons of the delta, or in the sea,
+after a slight submergence of the land, with its dirt-beds.</p>
+
+<p>In the English coal-fields the same association of fresh, or rather
+brackish water with marine strata, in close connection with beds of coal of
+terrestrial origin, has been frequently recognized. Thus, for example, a
+deposit near Shrewsbury, probably formed in brackish water, has been
+described by Sir R. Murchison as the youngest member of the carboniferous
+series of that district, at the point where the coal-measures are in
+contact with the Permian or "Lower New Red." It consists of shales and
+sandstones about 150 feet thick, with coal and traces of plants; including
+a bed of limestone, varying from 2 to 9 feet in thickness, which is
+cellular, and resembles some lacustrine limestones of France and Germany.
+It has been traced for 30 miles in a straight line, and can be recognized
+at still more distant points. The characteristic fossils are a small
+bivalve, having the form of a <i>Cyclas</i>, a small <i>Cypris</i> (<a href="#img355">fig. 376.</a>), and
+the microscopic shell of an annelid of an extinct genus called
+<i>Microconchus</i> (<a href="#img355">fig. 375.</a>), allied to <i>Serpula</i> or <i>Spirorbis</i>.</p>
+
+<p>In the lower coal-measures of Coalbrook Dale, the strata, according to Mr.
+Prestwich, often change completely within very short distances, beds of
+sandstone passing horizontally into clay, and clay into sandstone. The
+coal-seams often wedge out or disappear; and sections, at places nearly
+contiguous, present marked lithological distinctions. In this single field,
+in which the strata are from 700 to 800 feet <span class="pagenum"><a id="page325"></a>[p.325]</span>thick, between forty
+and fifty species of terrestrial plants have been discovered, besides
+several fishes and trilobites of forms distinct from those occurring in the
+Silurian strata. Also upwards of forty species of mollusca, among which are
+two or three referred to the freshwater genus <i>Unio</i>, and others of marine
+forms, such as <i>Nautilus</i>, <i>Orthoceras</i>, <i>Spirifer</i>, and <i>Productus</i>. Mr.
+Prestwich suggests that the intermixture of beds containing freshwater
+shells with others full of marine remains, and the alternation of coarse
+sandstone and conglomerate with beds of fine clay or shale containing the
+remains of plants, may be explained by supposing the deposit of Coalbrook
+Dale to have originated in a bay of the sea or estuary into which flowed a
+considerable river subject to occasional freshes.<a name="FNanchor_Z_18" id="FNanchor_Z_18"></a><a href="#Footnote_Z_18" class="fnanchor">[325-A]</a></p>
+
+<a id="img355" name="img355"></a>
+<div class="figcenter smaller width450">
+<p>Freshwater Fossils&mdash;Coal.</p>
+<img src="images/img355.jpg" width="450" height="237" alt="" title="">
+<p>Fig. 375.</p>
+<ul class="martopm05 smaller leftal add3em min1em">
+<li><i>a.</i> <i>Microconchus carbonarius</i>.</li>
+<li><i>b.</i> var. of same; nat. size, and magnified.</li>
+</ul>
+<p>Fig. 376. <i>Cypris inflata</i>, natural size, and magnified. Murchison.<a name="FNanchor_Z_19" id="FNanchor_Z_19"></a><a href="#Footnote_Z_19" class="fnanchor">[325-B]</a></p></div>
+
+<p>In the Edinburgh coal-field, at Burdiehouse, fossil fishes, mollusca, and
+cypris, very similar to those in Shropshire and Staffordshire, have been
+found by Dr. Hibbert.<a name="FNanchor_Z_20" id="FNanchor_Z_20"></a><a href="#Footnote_Z_20" class="fnanchor">[325-C]</a> In the coal-field also of Yorkshire there are
+freshwater strata, some of which contain shells referred to the genus
+<i>Unio</i>; but in the midst of the series there is one thin but very widely
+spread stratum, abounding in fishes and marine shells, such as <i>Ammonites
+Listeri</i> (<a href="#img356">fig. 377.</a>), <i>Orthoceras</i>, and <i>Avicula papyracea</i>, Goldf. (<a href="#img357">fig.
+378.</a>)<a name="FNanchor_Z_21" id="FNanchor_Z_21"></a><a href="#Footnote_Z_21" class="fnanchor">[325-D]</a></p>
+
+<a id="img356" name="img356"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 377.</p>
+<img src="images/img356.jpg" width="200" height="174" alt="" title="">
+<p><i>Ammonites Listeri</i>, Sow.</p></div>
+
+<a id="img357" name="img357"></a>
+<div class="floatright smaller width200">
+<p>Fig. 378.</p>
+<img src="images/img357.jpg" width="200" height="196" alt="" title="">
+<p><i>Avicula papyracea</i>, Goldf. (<i>Pecten papyraceus</i>, Sow.)</p></div>
+
+<p class="nofloat">No similarly intercalated layer of marine shells has been noticed in the
+neighbouring coal-field of Newcastle, where, as in South <span class="pagenum"><a id="page326"></a>[p.326]</span>Wales
+and Somersetshire, the marine deposits are entirely below those containing
+terrestrial and freshwater remains.<a name="FNanchor_Z_22" id="FNanchor_Z_22"></a><a href="#Footnote_Z_22" class="fnanchor">[326-A]</a></p>
+
+<p><i>Clay-iron-stone.</i>&mdash;Bands and nodules of clay-iron-stone are common in
+coal-measures, and are formed, says Sir H. De la Beche, of carbonate of
+iron, mingled mechanically with earthy matter, like that constituting the
+shales. Mr. Hunt, of the Museum of Practical Geology, instituted a series
+of experiments to illustrate the production of this substance, and found
+that decomposing vegetable matter, such as would be distributed through all
+coal strata, prevented the farther oxidation of the proto-salts of iron,
+and converted the peroxide into protoxide by taking a portion of its oxygen
+to form carbonic acid. Such carbonic acid, meeting with the protoxide of
+iron in solution, would unite with it and form a carbonate of iron; and
+this mingling with fine mud, when the excess of carbonic acid was removed,
+might form beds or nodules of argillaceous iron-stone.<a name="FNanchor_Z_23" id="FNanchor_Z_23"></a><a href="#Footnote_Z_23" class="fnanchor">[326-B]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XXV.</h2>
+
+<h4>CARBONIFEROUS GROUP&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Coal-fields of the United States &mdash; Section of the country between the
+Atlantic and Mississippi &mdash; Position of land in the carboniferous period
+eastward of the Alleghanies &mdash; Mechanically formed rocks thinning out
+westward, and limestones thickening &mdash; Uniting of many coal-seams into
+one thick one &mdash; Horizontal coal at Brownsville, Pennsylvania &mdash; Vast
+extent and continuity of single seams of coal &mdash; Ancient river-channel
+in Forest of Dean coal-field &mdash; Absence of earthy matter in
+coal &mdash; Climate of carboniferous period &mdash; Insects in
+coal &mdash; Rarity of air-breathing animals &mdash; Great number of fossil
+fish &mdash; First discovery of the skeletons of fossil
+reptiles &mdash; Footprints of reptilians &mdash; Mountain limestone &mdash; Its
+corals and marine shells.</p></div>
+
+
+<p><span class="smcap">It</span> was stated in the last chapter that a great uniformity prevails in the
+fossil plants of the coal-measures of Europe and North America; and I may
+add that four-fifths of those collected in Nova Scotia have been identified
+with European species. Hence the former existence at the remote period
+under consideration (the carboniferous) of a continent or chain of islands
+where the Atlantic now rolls its waves seems a fair inference. Nor are
+there wanting other and independent proofs of such an ancient land situated
+to the eastward of the present Atlantic coast of North America; for the
+geologist deduces the same conclusion from the mineral composition of the
+carboniferous and some older groups of rocks as they are developed on the
+eastern flanks of the Alleghanies, contrasted with their character in the
+low country to the westward of those mountains.</p>
+
+<p>The annexed diagram (<a href="#img358">fig. 379.</a>) will assist the reader in understanding
+<span class="pagenum"><a id="page328"></a>[p.328]</span>the phenomena now alluded to, although I must guard him against
+supposing that it is a true section. A great number of details have of
+necessity been omitted, and the scale of heights and horizontal distances
+are unavoidably falsified.</p>
+
+<a id="img358" name="img358"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 379.<br>Diagram explanatory of the geological structure of
+a part of the United States between the Atlantic and the Mississippi.</p>
+<p>Length from E. to W. 850 miles.</p>
+<img src="images/img358.jpg" width="500" height="139" alt="" title="">
+<ul class="smaller leftal add1em min2em">
+<li>A B. Atlantic plain.</li>
+<li>B C. Atlantic slope.</li>
+<li>C D. Alleghanies or Appalachian chain.</li>
+<li>D E. Appalachian coal-field west of the mountains.</li>
+<li>E F. Dome-shaped outcrop of strata on the Ohio, older than the coal.</li>
+<li>F G. Illinois coal-field.</li>
+<li><i>h.</i> Falls and rapids of the rivers at the junction of the hypogene
+and newer formations.</li>
+<li><i>i</i>, <i>k</i>, <i>l</i>, <i>m</i>. Parallel folds of Appalachians becoming successively more
+open, and flatter in going from E. to W.</li>
+</ul>
+<p><i>References to the different Formations.</i></p>
+<ul class="smaller leftal add1em min2em">
+<li>1. Miocene tertiary.</li>
+<li>2. Eocene tertiary.</li>
+<li>3. Cretaceous strata.</li>
+<li>4. Red sandstone with ornithichnites (new red or trias?) usually much
+invaded by trap.</li>
+<li>5. Coal-measures (bituminous coal).</li>
+<li>5' Anthracitic coal-measures.</li>
+<li>5'' Carboniferous limestone of the Illinois coal-field, wanting
+in the Appalachian.</li>
+<li>6. Old red or Devonian, Olive slate, &amp;c.</li>
+<li>7. Primary fossiliferous or Silurian strata.</li>
+<li>8. Hypogene strata, or gneiss, mica schist, &amp;c., with granite veins.</li>
+</ul>
+<p><i>Note.</i> The dotted lines at <i>i</i> and <i>k</i> express portions of rock removed
+by denudation, the amount of which may be estimated by supposing similar
+lines prolonged from other points where different strata end abruptly
+at the surface.</p>
+<p><i>N.B.</i> The lower section at ** joins on to the upper one at *.</p></div>
+
+<p>Starting from the shores of the Atlantic, on the eastern side of the
+Continent, we first come to a low region (<span class="smcap">A B</span>), which was called the
+alluvial plain by the first geographers. It is occupied by tertiary and
+cretaceous strata, before described (pp. <a href="#page171">171.</a> <a href="#page206">206.</a> and <a href="#page224">224.</a>), which are
+nearly horizontal. The next belt, from <span class="smcap">B</span> to <span class="smcap">C</span>, consists of granitic rocks
+(hypogene), chiefly gneiss and mica-schist, covered occasionally with
+unconformable red sandstone, No. 4. (New Red or Trias?), remarkable for its
+ornithichnites (see <a href="#page328">p. 327.</a>). Sometimes, also, this sandstone rests on the
+edges of the disturbed paleozoic rocks (as seen in the section). The region
+(<span class="smcap">B C</span>), sometimes called the "Atlantic Slope," corresponds nearly in average
+width with the low and flat plain (<span class="smcap">A</span>, <span class="smcap">B</span>), and is characterized by hills of
+moderate height, contrasting strongly, in their rounded shape and altitude,
+with the long, steep, and lofty parallel ridges of the Alleghany mountains.
+The outcrop of the strata in these ridges, like the two belts of hypogene
+and newer rocks (<span class="smcap">A B</span>, and <span class="smcap">B C</span>), above alluded to, when laid down on a
+geological map, exhibit long stripes of different colours, running in a
+N.E. and S.W. direction, in the same way as the lias, chalk, and other
+secondary formations in the middle and eastern half of England.</p>
+
+<p>The narrow and parallel zones of the Appalachians here mentioned, consist
+of strata, folded into a succession of convex and concave flexures,
+subsequently laid open by denudation. The component rocks are of great
+thickness, all referable to the Silurian, Devonian, and Carboniferous
+formations. There is no principal or central axis, as in the Pyrenees and
+many other chains&mdash;no nucleus to which all the minor ridges conform; but
+the chain consists of many nearly equal and parallel foldings, having what
+is termed an anticlinal and synclinal arrangement (see above, <a href="#page48">p. 48.</a>). This
+system of hills extends, geologically considered, from Vermont to Alabama,
+being more than 1000 miles long, from 50 to 150 miles broad, and varying in
+height from 2000 to 6000 feet. Sometimes the whole assemblage of ridges
+runs perfectly straight for a distance of more than 50 miles, after which
+all of them wheel round together, and take a new direction, at an angle of
+20 or 30 degrees to the first.</p>
+
+<p>We are indebted to the state surveyors of Virginia and Pennsylvania, Prof.
+W. B. Rogers and his brother Prof. H. D. Rogers, for the important
+discovery of a clue to the general law of structure prevailing throughout
+this range of mountains, which, however simple it may appear when once made
+out and clearly explained, might long have been overlooked; amidst so great
+a mass of complicated details. It appears that the bending and fracture of
+the beds is greatest on the south-eastern or Atlantic side of the chain,
+and the strata become less and less disturbed as we go westward, until at
+length they regain their original or horizontal position. By reference to
+the section (<a href="#img358">fig. 379.</a>), it will be seen that on the eastern side, or in
+the ridges <span class="pagenum"><a id="page329"></a>[p.329]</span>and troughs nearest the Atlantic, south-eastern dips
+predominate, in consequence of the beds having been folded back upon
+themselves, as in <i>i</i>, those on the north-western side of each arch having
+been inverted. The next set of arches (such as <i>k</i>) are more open, each
+having its western side steepest; the next (<i>l</i>) opens out still more
+widely, the next (<i>m</i>) still more, and this continues until we arrive at
+the low and level part of the Appalachian coal-field (<span class="smcap">D E</span>).</p>
+
+<p>In nature or in a true section, the number of bendings or parallel folds is
+so much greater that they could not be expressed in a diagram without
+confusion. It is also clear that large quantities of rock have been removed
+by aqueous action or denudation, as will appear if we attempt to complete
+all the curves in the manner indicated by the dotted lines at <i>i</i> and <i>k</i>.</p>
+
+<p>The movements which imparted so uniform an order of arrangement to this
+vast system of rocks must have been, if not contemporaneous, at least parts
+of one and the same series, depending on some common cause. Their
+geological date is well defined, at least within certain limits, for they
+must have taken place after the deposition of the carboniferous strata (No.
+5.), and before the formation of the red sandstone (No. 4.). The greatest
+disturbing and denuding forces have evidently been exerted on the
+south-eastern side of the chain; and it is here that igneous or plutonic
+rocks are observed to have invaded the strata, forming dykes, some of which
+run for miles in lines parallel to the main direction of the Appalachians,
+or N.N.E. and S.S.W.</p>
+
+<p>The thickness of the carboniferous rocks in the region <span class="smcap">C</span> is very great, and
+diminishes rapidly as we proceed to the westward. The surveys of
+Pennsylvania and Virginia show that the south-east was the quarter whence
+the coarser materials of these strata were derived, so that the ancient
+land lay in that direction. The conglomerate which forms the general base
+of the coal-measures is 1500 feet thick in the Sharp Mountain, where I saw
+it (at <span class="smcap">C</span>) near Pottsville; whereas it has only a thickness of 500 feet,
+about thirty miles to the north-west, and dwindles gradually away when
+followed still farther in the same direction, till its thickness is reduced
+to 30 feet.<a name="FNanchor_AA_1" id="FNanchor_AA_1"></a><a href="#Footnote_AA_1" class="fnanchor">[329-A]</a> The limestones, on the other hand, of the coal-measures,
+augment as we trace them westward. Similar observations have been made in
+regard to the Silurian and Devonian formations in New York; the sandstones
+and all the mechanically-formed rocks thinning out as they go westward, and
+the limestones thickening, as it were, at their expense. It is, therefore,
+clear that the ancient land was to the east, where the Atlantic now is; the
+deep sea, with its banks of coral and shells to the west, or where the
+hydrographical basin of the Mississippi is now situated.</p>
+
+<p>In that region, near Pottsville, where the thickness of the coal-measures
+is greatest, there are thirteen seams of anthracitic coal, several of them
+more than 2 yards thick. Some of the lowest of these alternate with beds of
+white grit and conglomerate of coarser grain <span class="pagenum"><a id="page330"></a>[p.330]</span>than I ever saw
+elsewhere, associated with pure coal. The pebbles of quartz are often of
+the size of a hen's egg. On following these pudding-stones and grits for
+several miles from Pottsville, by Tamaqua, to the Lehigh Summit Mine, in
+company with Mr. H. D. Rogers, in 1841, he pointed out to me that the
+coarse-grained strata and their accompanying shales gradually thin out,
+until seven seams of coal, at first widely separated, are brought nearer
+and nearer together, until they successively unite; so that at last they
+form one mass, between 40 and 50 feet thick. I saw this enormous bed of
+anthracitic coal quarried in the open air at Mauch Chunk (or the Bear
+Mountain), the overlying sandstone, 40 feet thick, having been removed
+bodily from the top of the hill, which, to use the miner's expression, had
+been "scalped." The accumulation of vegetable matter now constituting this
+vast bed of anthracite, may perhaps, before it was condensed by pressure
+and the discharge of its hydrogen, oxygen, and other volatile ingredients,
+have been between 200 and 300 feet thick. The origin of such a vast
+thickness of vegetable remains, so unmixed with earthy ingredients, can, I
+think, be accounted for in no other way, than by the growth, during
+thousands of years, of trees and ferns, in the manner of peat,&mdash;a theory
+which the presence of the Stigmaria <i>in situ</i> under each of the seven
+layers of anthracite, fully bears out. The rival hypothesis, of the
+drifting of plants into a sea or estuary, leaves the absence of sediment,
+or, in this case, of sand and pebbles, wholly unexplained.</p>
+
+<a id="img359" name="img359"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 380.</p>
+<img src="images/img359.jpg" width="500" height="078" alt="" title=""></div>
+
+<a id="img360" name="img360"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 381.</p>
+<img src="images/img360.jpg" width="500" height="089" alt="" title=""></div>
+
+<p>But the student will naturally ask, what can have caused so many seams of
+coal, after they had been persistent for miles, to come together and blend
+into one single seam, and that one equal in the aggregate to the thickness
+of the several separate seams? Often had the same question been put by
+English miners before a satisfactory answer was given to it by the late Mr.
+Bowman. The following is his solution of the problem. Let <i>a a'</i>, <a href="#img359">fig.
+380.</a>, be a mass of vegetable matter, capable, when condensed, of forming a
+3-foot seam of coal. It rests on the underclay <i>b b'</i>, filled with roots of
+trees <i>in situ</i>, and it supports a growing forest (<span class="smcap">C D</span>). Suppose that part
+of the same forest <span class="smcap">D E</span> had become submerged by the ground sinking down 25
+feet, so that the trees have been partly thrown down and <span class="pagenum"><a id="page331"></a>[p.331]</span>partly
+remain erect in water, slowly decaying, their stumps and the lower parts of
+their trunks being enveloped in layers of sand and mud, which are gradually
+filling up the lake <span class="smcap">D F</span>. When this lake or lagoon has at length been
+entirely silted up and converted into land, say, in the course of a
+century, the forest <span class="smcap">C D</span> will extend once more continuously over the whole
+area <span class="smcap">C F</span>, as in <a href="#img360">fig. 381.</a>, and another mass of vegetable matter
+(<i>g g'</i>), forming 3 feet more of coal, may accumulate from <span class="smcap">C</span> to <span class="smcap">F</span>.
+We then find in the region <span class="smcap">F</span>, two seams of coal (<i>a'</i> and <i>g'</i>)
+each 3 feet thick, and separated by 25 feet of sandstone and shale, with
+erect trees based upon the lower coal, while, between <span class="smcap">D</span> and <span class="smcap">C</span>,
+we find these two seams united into a 2-yard coal. It may be objected that
+the uninterrupted growth of plants during the interval of a century will
+have caused the vegetable matter in the region <span class="smcap">C D</span> to be thicker
+than the two distinct seams <i>a'</i> and <i>g'</i> at <span class="smcap">F</span>; and no doubt
+there would actually be a slight excess representing one generation of
+trees with the remains of other plants, forming half an inch or an inch of
+coal; but this would not prevent the miner from affirming that the seam <i>a g</i>,
+throughout the area <span class="smcap">C D</span>, was equal to the two seams <i>a'</i> and <i>g'</i>
+at <span class="smcap">F</span>.</p>
+
+<p>The reader has seen, by reference to the section (<a href="#img358">fig. 379.</a> <a href="#page328">p. 327.</a>), that
+the strata of the Appalachian coal-field assume an horizontal position west
+of the mountains. In that less elevated country, the coal-measures are
+intersected by three great navigable rivers, and are capable of supplying
+for ages, to the inhabitants of a densely peopled region, an inexhaustible
+supply of fuel. These rivers are the Monongahela, the Alleghany, and the
+Ohio, all of which lay open on their banks the level seams of coal. Looking
+down the first of these at Brownsville, we have a fine view of the main
+seam of bituminous coal 10 feet thick, commonly called the Pittsburg seam,
+breaking out in the steep cliff at the water's edge; and I made the
+accompanying sketch of its appearance from the bridge over the river (see
+<a href="#img361">fig. 382.</a>). Here the coal, 10 feet thick, is covered by carbonaceous shale
+(<i>b</i>), and this again by micaceous sandstone (<i>c</i>). Horizontal galleries
+may be driven everywhere at very slight expense, and so worked as to drain
+themselves, while the cars, laden with coal and attached to each other,
+glide down on a railway, so as to deliver their burden into barges moored
+to the river's bank. The same seam is seen at a distance, on the right bank
+(at <i>a</i>), and may be followed the whole way to Pittsburg, fifty miles
+distant. As it is nearly horizontal, while the river descends it crops out
+at a continually increasing, but never at an inconvenient, height above the
+Monongahela. Below the great bed of coal at Brownsville is a fire-clay 18
+inches thick, and below this, several beds of limestone, below which again
+are other coal seams. I have also shown in my sketch another layer of
+workable coal (at <i>d d</i>), which breaks out on the slope of the hills at a
+greater height. Here almost every proprietor can open a coal-pit on his own
+land, and the stratification being very regular, he may calculate with
+precision the depth at which coal may be won.</p>
+
+<p>The Appalachian coal-field, of which these strata form a part <span class="pagenum"><a id="page332"></a>[p.332]</span>
+(from <span class="smcap">C</span> to <span class="smcap">E</span>, section, <a href="#img358">fig. 379.</a>, <a href="#page328">p. 327.</a>), is remarkable for its vast
+area; for, according to Professor H. D. Rogers, it stretches continuously
+from N.E. to S.W., for a distance of 720 miles, its greatest width being
+about 180 miles. On a moderate estimate, its superficial area amounts to
+63,000 square miles.</p>
+
+<a id="img361" name="img361"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 382.</p>
+<img src="images/img361.jpg" width="500" height="246" alt="" title="">
+<p>View of the great Coal Seam on the Monongahela at Brownsville,
+Pennsylvania, U. S.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Ten-foot seam of coal.</li>
+<li><i>b.</i> Black bituminous or carbonaceous shale, 10 feet thick.</li>
+<li><i>c.</i> Micaceous sandstone.</li>
+<li><i>d d.</i> Upper seam of coal, 6 feet thick.</li>
+</ul></div>
+
+<p>This coal formation, before its original limits were reduced by <span class="pagenum"><a id="page333"></a>[p.333]</span>
+denudation, must have measured 900 miles in length, and in some places more
+than 200 miles in breadth. By again referring to the section (<a href="#img358">fig. 379.</a>, <a href="#page328">p.
+327.</a>), it will be seen that the strata of coal are horizontal to the
+westward of the mountains in the region <span class="smcap">D E</span>, and become more and more
+inclined and folded as we proceed eastward. Now it is invariably found, as
+Professor H. D. Rogers has shown by chemical analysis, that the coal is
+most bituminous towards its western limit, where it remains level and
+unbroken, and that it becomes progressively debituminized as we travel
+south-eastward towards the more bent and distorted rocks. Thus, on the
+Ohio, the proportion of hydrogen, oxygen, and other volatile matters,
+ranges from forty to fifty per cent. Eastward of this line, on the
+Monongahela, it still approaches forty per cent., where the strata begin to
+experience some gentle flexures. On entering the Alleghany Mountains, where
+the distinct anticlinal axes begin to show themselves, but before the
+dislocations are considerable, the volatile matter is generally in the
+proportion of eighteen or twenty per cent. At length, when we arrive at
+some insulated coal-fields (5', <a href="#img358">fig. 379.</a>) associated with the boldest
+flexures of the Appalachian chain, where the strata have been actually
+turned over, as near Pottsville, we find the coal to contain only from six
+to twelve per cent. of bitumen, thus becoming a genuine anthracite.<a name="FNanchor_AA_2" id="FNanchor_AA_2"></a><a href="#Footnote_AA_2" class="fnanchor">[333-A]</a></p>
+
+<p>It appears from the researches of Liebig and other eminent chemists, that
+when wood and vegetable matter are buried in the earth, exposed to
+moisture, and partially or entirely excluded from the air, they decompose
+slowly and evolve carbonic acid gas, thus parting with a portion of their
+original oxygen. By this means, they become gradually converted into
+lignite or wood-coal, which contains a larger proportion of hydrogen than
+wood does. A continuance of decomposition changes this lignite into common
+or bituminous coal, chiefly by the discharge of carburetted hydrogen, or
+the gas by which we illuminate our streets and houses. According to
+Bischoff, the inflammable gases which are always escaping from mineral
+coal, and are so often the cause of fatal accidents in mines, always
+contain carbonic acid, carburetted hydrogen, nitrogen, and olefiant gas.
+The disengagement of all these gradually transforms ordinary or bituminous
+coal into anthracite, to which the various names of splint coal, glance
+coal, culm, and many others, have been given.</p>
+
+<p>We have seen that, in the Appalachian coal-field, there is an intimate
+connection between the extent to which the coal has parted with its gaseous
+contents, and the amount of disturbance which the strata have undergone.
+The coincidence of these phenomena may be attributed partly to the greater
+facility afforded for the escape of volatile matter, where the fracturing
+of the rocks had produced an infinite number of cracks and crevices, and
+also to the heat of the gases and water penetrating these cracks, when the
+great movements took place, which have rent and folded the Appalachian
+strata. It <span class="pagenum"><a id="page334"></a>[p.334]</span>is well known that, at the present period, thermal
+waters and hot vapours burst out from the earth during earthquakes, and
+these would not fail to promote the disengagement of volatile matter from
+the carboniferous rocks.</p>
+
+<p><i>Continuity of seams of coal.</i>&mdash;As single seams of coal are continuous over
+very wide areas, it has been asked, how forests could have prevailed
+uninterruptedly over such wide spaces, without being oftener flooded by
+turbid rivers, or, when submerged, denuded by marine currents. It appears,
+from the description of the Cape Breton coal-field, by Mr. Richard Brown,
+that false stratification is common in the beds of sand, and some partial
+denudation of these, at least, must often have taken place during the
+accumulation of the carboniferous series.</p>
+
+<p>In the Forest of Dean, ancient river-channels are found, which pass through
+beds of coal, and in which rounded pebbles of coal occur. They are of older
+date than the overlying and undisturbed coal-measures. The late Mr. Buddle,
+who described them to me, told me he had seen similar phenomena in the
+Newcastle coal-field. Nevertheless, instances of these channels are much
+more rare than we might have anticipated, especially when we remember how
+often the roots of trees (<i>Stigmari�</i>) have been torn up, and drifted in
+broken fragments into the grits and sandstones. The prevalence of a
+downward movement is, no doubt, the principal cause which has saved so many
+extensive seams of coal from destruction by fluviatile action.</p>
+
+<p>The purity of the coal, or its non-intermixture with earthy matter,
+presents another theoretical difficulty to many geologists, who are
+inclined to believe that the trees and smaller plants of the carboniferous
+period grew in extensive swamps, rather than on land not liable to be
+inundated. It appears, however, that in the alluvial plain and delta of the
+Mississippi, extensive "cypress swamps," as they are called, densely
+covered with various trees, occur, into which no matter held in mechanical
+suspension is ever introduced during the greatest inundations, inasmuch as
+they are all surrounded by a dense marginal belt of reeds, canes, and
+brushwood. Through this thick barrier the river-water must pass, so that it
+is invariably well filtered before it can reach the interior of the
+forest-covered area, within which, vegetable matter is continually
+accumulating from the decay of trees and semi-aquatic plants. In proof of
+this, I may observe, that whenever any part of a swamp is dried up, during
+an unusually hot season, and the wood set on fire, pits are burnt into the
+ground many feet deep, or as far down as the fire can descend without
+meeting with water, and it is then found that scarcely any residuum or
+earthy matter is left.<a name="FNanchor_AA_3" id="FNanchor_AA_3"></a><a href="#Footnote_AA_3" class="fnanchor">[334-A]</a> At the bottom of these "cypress swamps" of
+the Mississippi, a bed of clay is found, with roots of the tall cypress
+(<i>Taxodium distichum</i>), just as the underclays of the coal are filled with
+<i>Stigmaria</i>.</p>
+
+<p><span class="pagenum"><a id="page335"></a>[p.335]</span><i>Climate of Coal Period.</i>&mdash;So long as the botanist taught that a
+tropical climate was implied by the carboniferous flora, geologists might
+well be at a loss to reconcile the preservation of so much vegetable matter
+with a high temperature; for heat hastens the decomposition of fallen
+leaves and trunks of trees, whether in the atmosphere or in water.<a name="FNanchor_AA_4" id="FNanchor_AA_4"></a><a href="#Footnote_AA_4" class="fnanchor">[335-A]</a>
+It is well known that peat, so abundant in the bogs of high latitudes,
+ceases to grow in the swamps of warmer regions. It seems, however, to have
+become a more and more received opinion, that the coal-plants do not, on
+the whole, indicate a climate resembling that now enjoyed in the equatorial
+zone. Tree-ferns range as far south as the southern part of New Zealand,
+and Araucarian pines occur in Norfolk Island. A great predominance of ferns
+and lycopodiums indicates warmth, moisture, equability of temperature, and
+freedom from frost, rather than intense heat; and we know too little of the
+sigillari�, calamites, asterophyllites, and other peculiar forms of the
+carboniferous period, to be able to speculate with confidence on the kind
+of climate they may have required.</p>
+
+<p>No doubt, we are entitled to presume, from the corals and cephalopoda of
+the mountain limestone, that a warm temperature characterized the northern
+seas in the carboniferous era; but the absence of cold may have given rise
+(as at present in the seas of the Bermudas, under the influence of the gulf
+stream) to a very wide geographical range of stone-building corals and
+shell-bearing cuttle-fish, without its being necessary to call in the aid
+of tropical heat.<a name="FNanchor_AA_5" id="FNanchor_AA_5"></a><a href="#Footnote_AA_5" class="fnanchor">[335-B]</a></p>
+
+
+<h3>CARBONIFEROUS REPTILES.</h3>
+
+<p>Where we have evidence in a single coal-field, as in that of Nova Scotia,
+or South Wales, of fifty or even a hundred ancient forests buried one above
+the other, with the roots of trees still in their original position, and
+with some of the trunks still remaining erect, we are apt to wonder that
+until the year 1844 no remains of contemporaneous air-breathing creatures,
+except a few insects, had been discovered. No vertebrated animals more
+highly organized than fish, no mammalia or birds, no saurians, frogs,
+tortoises, or snakes, were yet known in rocks of such high antiquity. In
+the coal-field of Coalbrook Dale mention had been made of two species of
+beetles of the family <i>Curculionid�</i>, and of a neuropterous insect
+resembling the genus <i>Corydalis</i>, with another related to the
+<i>Phasmid�</i>.<a name="FNanchor_AA_6" id="FNanchor_AA_6"></a><a href="#Footnote_AA_6" class="fnanchor">[335-C]</a> In other coal-measures in Europe we find notice of a
+scorpion and of a moth allied to <i>Tinea</i>, also of one air-breathing
+crustacean, or land-crab. Yet Agassiz had already described in his great
+work on fossil fishes more than one hundred and fifty species of
+ichthyolites from the coal strata, ninety-four belonging to the families of
+shark and ray, and fifty-eight to the class of ganoids. Some of these fish
+are very remote in their organization from any <span class="pagenum"><a id="page336"></a>[p.336]</span>now living,
+especially those of the family called <i>Sauroid</i> by Agassiz; as
+<i>Megalichthys</i>, <i>Holoptychius</i>, and others, which are often of great size,
+and all predaceous. Their osteology, says M. Agassiz, reminds us in many
+respects of the skeletons of saurian reptiles, both by the close sutures of
+the bones of the skull, their large conical teeth striated longitudinally
+(see <a href="#img362">fig. 383.</a>), the articulations of the spinous processes with the
+vertebr�, and other characters. Yet they do not form a family intermediate
+between fish and reptiles, but are true <i>fish</i>, though doubtless more
+highly organized than any living fish.<a name="FNanchor_AA_7" id="FNanchor_AA_7"></a><a href="#Footnote_AA_7" class="fnanchor">[336-A]</a></p>
+
+<a id="img362" name="img362"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 383.</p>
+<img src="images/img362.jpg" width="200" height="379" alt="" title="">
+<p><i>Holoptychius Hibberti</i>, Ag. Fifeshire coal-field; natural size.</p></div>
+
+<p>The annexed figure represents a large tooth of the <i>Megalichthys</i>, found by
+Mr. Horner in the Cannel coal of Fifeshire. It probably inhabited an
+estuary, like many of its contemporaries, and frequented both rivers and
+the sea.</p>
+
+<a id="img363" name="img363"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 384.</p>
+<img src="images/img363.jpg" width="300" height="473" alt="" title="">
+<p><i>Archegosaurus minor</i>, <span class="wosp05">Goldfuss. Fossil</span> reptile
+from the coal-measures, Saarbr�ck.</p></div>
+
+<p>At length, in 1844, the first skeleton of a true reptile was announced from
+the coal of M�nster-Appel in Rhenish Bavaria, by H. von Meyer, under the
+name of <i>Apateon pedestris</i>, the animal being supposed to be nearly related
+to the salamanders. Three years later, in 1847, Prof. von Dechen found in
+the coal-field of Saarbr�ck, at the village of Lebach, between Strasburg
+and Treves, the skeletons of no less than three distinct species of
+air-breathing reptiles, which were described by the late Prof. Goldfuss
+under the generic name of <i>Archegosaurus</i>. The ichthyolites and plants
+found in the same strata, left no doubt that these remains belonged to the
+true coal period. The skulls, teeth, and the greater portions of the
+skeleton, nay, even a large part of the skin, of two of these reptiles have
+been faithfully preserved in the centre <span class="pagenum"><a id="page337"></a>[p.337]</span>of spheroidal concretions
+of clay-iron-stone. The largest of these lizards, <i>Archegosaurus Decheni</i>,
+must have been 3 feet 6 inches long. The annexed drawing represents the
+smallest of the three of the natural size. They were considered by Goldfuss
+as saurians, but by Herman von Meyer as most nearly allied to the
+<i>Labyrinthodon</i>, and therefore connected with the batrachians, as well as
+the lizards. The remains of the extremities leave no doubt that they were
+quadrupeds, "provided," says Von Meyer, "with hands and feet terminating in
+distinct toes; but these limbs were weak, serving only for swimming or
+creeping." The same anatomist has pointed out certain points of analogy
+between their bones and those of the <i>Proteus anguinus</i>; and Mr. Owen has
+observed to me that they make an approach to the <i>Proteus</i> in the shortness
+of their ribs. Two of these ancient reptiles retain a large part of the
+outer skin, which consisted of long, narrow, wedge-shaped, tile-like, and
+horny scales, arranged in rows (see <a href="#img364">fig. 385.</a>).</p>
+
+<a id="img364" name="img364"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 385.</p>
+<img src="images/img364.jpg" width="250" height="085" alt="" title="">
+<p>Imbricated covering of skin of <i>Archegosaurus medius</i>, Goldf.;
+magnified.<a name="FNanchor_AA_8" id="FNanchor_AA_8"></a><a href="#Footnote_AA_8" class="fnanchor">[337-A]</a></p></div>
+
+<p><i>Cheirotherian footprints in coal measures, United States.</i>&mdash;In 1844, the
+very year when the Apateon or Salamander of the coal was first met with in
+the country between the Moselle and the Rhine, Dr. King published an
+account of the footprints of a large reptile discovered by him in North
+America. These occur in the coal strata of Greensburg, in Westmoreland
+County, Pennsylvania; and I had an opportunity of examining them in 1846. I
+was at once convinced of their genuineness, and declared my conviction on
+that point, on which doubts had been entertained both in Europe and the
+United States. The footmarks were first observed standing out in relief
+from the lower surface of slabs of sandstone, resting on thin layers of
+fine unctuous clay. I brought away one of these masses, which is
+represented in the accompanying drawing (<a href="#img365">fig. 386.</a>). It displays, together
+with footprints, the casts of cracks (<i>a</i>, <i>a'</i>) of various sizes. The
+origin of such cracks in clay, and casts of the same, has before been
+explained, and referred to the drying and shrinking of mud, and the
+subsequent pouring of sand into open crevices. It will be seen that some of
+the cracks, as at <i>b</i>, <i>c</i>, traverse the footprints, and produce distortion
+in them, as might have been expected, for the mud must have been soft when
+the animal walked over it and left the impressions; whereas, when it
+afterwards dried up and shrank, it would be too hard to receive such
+indentations.</p>
+
+<p>No less than twenty-three footsteps were observed by Dr. King in the same
+quarry before it was abandoned, the greater part of them so arranged (see
+<a href="#img366">fig. 387.</a>) on the surface of one stratum as to imply that they were made
+successively by the same animal. Everywhere there was a double row of
+tracks, and in each row they occur in <span class="pagenum"><a id="page338"></a>[p.338]</span>pairs, each pair consisting
+of a hind and fore foot, and each being at nearly equal distances from the
+next pair. In each parallel row the toes turn the one set to the right, the
+other to the left. In the European <i>Cheirotherium</i>, before mentioned (<a href="#page290">p.
+290.</a>), both the hind and fore feet have each five toes, and the size of the
+hind foot is about five times as large as the fore foot. In the American
+fossil the posterior footprint is not even twice as large as the anterior,
+and the number of toes is unequal, being five in the hinder and four in the
+anterior foot. In this, as in the European <i>Cheirotherium</i>, one toe stands
+out like a thumb, and these thumb-like toes turn the one set to the right,
+and the other to the left. The American <i>Cheirotherium</i> was evidently a
+broader animal, and belonged to a distinct genus from that of the triassic
+age in Europe.<a name="FNanchor_AA_9" id="FNanchor_AA_9"></a><a href="#Footnote_AA_9" class="fnanchor">[338-A]</a></p>
+
+<a id="img365" name="img365"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 386.</p>
+<img src="images/img365.jpg" width="400" height="550" alt="" title="">
+<p><i>Scale one-sixth the original.</i> Slab of sandstone from the
+coal-measures of Pennsylvania, with footprints of air-breathing
+reptile and casts of cracks.</p></div>
+
+<p>We may assume that the reptile which left these prints on the <span class="pagenum"><a id="page339"></a>[p.339]</span>
+ancient sands of the coal-measures was an air-breather, because its weight
+would not have been sufficient under water to have made impressions so deep
+and distinct. The same conclusion is also borne out by the casts of the
+cracks above described, for they show that the clay had been exposed to the
+air and sun, so as to have dried and shrunk.</p>
+
+<a id="img366" name="img366"></a>
+<div class="figcenter smaller width325">
+<p>Fig. 387.</p>
+<img src="images/img366.jpg" width="325" height="575" alt="" title="">
+<p>Series of reptilian footprints in the coal-strata
+of Westmoreland County, Pennsylvania.</p>
+<p class="martopm05"><i>a.</i> Mark of nail?</p></div>
+
+<p>The geological position of the sandstone of Greensburg is perfectly clear,
+being situated in the midst of the Appalachian coal-field, <span class="pagenum"><a id="page340"></a>[p.340]</span>having
+the main bed of coal, called the Pittsburg seam, above mentioned (<a href="#page331">p. 331.</a>),
+3 yards thick, 100 feet above it, and worked in the neighbourhood, with
+several other seams of coal at lower levels. The impressions of
+<i>Lepidodendron</i>, <i>Sigillaria</i>, <i>Stigmaria</i>, and other characteristic
+carboniferous plants, are found both above and below the level of the
+reptilian footsteps.</p>
+
+<p>Analogous footprints of a large reptile of still older date have since been
+found (1849), by Mr. Isaac Lea, in the lowest beds of the coal formation at
+Pottsville, near Philadelphia, so that we may now be said to have the
+footmarks of two reptilians of the coal period, and the skeletons of
+four.<a name="FNanchor_AA_10" id="FNanchor_AA_10"></a><a href="#Footnote_AA_10" class="fnanchor">[340-A]</a></p>
+
+
+<h3>CARBONIFEROUS OR MOUNTAIN LIMESTONE.</h3>
+
+<p>We have already seen that this rock lies sometimes entirely beneath the
+coal-measures, while, in other districts, it alternates with the shales and
+sandstone of the coal. In both cases it is destitute of land plants, and
+usually charged with corals, which are often of large size; and several
+species belong to the lamelliferous class of Lamarck, which enter largely
+into the structure of coral reefs now growing. There are also a great
+number of <i>Crinoidea</i> (see <a href="#img367">fig. 388.</a>), and a few <i>Echinoderms</i>, associated
+with the zoophytes above mentioned. The <i>Brachiopoda</i> constitute a large
+proportion of the Mollusca, many species being referable to two extinct
+genera, <i>Spirifer</i> (or <i>Spirifera</i>) (<a href="#img368">fig. 389.</a>), and <i>Productus</i>
+(<i>Lept�na</i>) (<a href="#img369">fig. 390.)</a>.</p>
+
+<a id="img367" name="img367"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 388.</p>
+<img src="images/img367.jpg" width="150" height="310" alt="" title="">
+<p><i>Cyathocrinites planus</i>, <span class="wosp05">Miller. Mountain</span> limestone.</p></div>
+
+<a id="img368" name="img368"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 389.</p>
+<img src="images/img368.jpg" width="200" height="152" alt="" title="">
+<p><i>Spirifer glaber</i>, Sow. Mountain limestone.</p></div>
+
+<a id="img369" name="img369"></a>
+<div class="floatright smaller width200">
+<p>Fig. 390.</p>
+<img src="images/img369.jpg" width="200" height="151" alt="" title="">
+<p><i>Productus Martini</i>, Sow. (<i>P. semireticulatus</i>,
+Flem.) Mountain limestone.</p></div>
+
+<p class="nofloat">Among the spiral univalve shells the extinct genus <i>Euomphalus</i> (see <a href="#img370">fig.
+391.</a>) is one of the commonest fossils of the Mountain limestone. In the
+interior it is often divided into chambers (see <a href="#img370">fig. 391. <i>d</i></a>); the septa
+or partitions not being perforated, as in foraminiferous shells, or in
+those having siphuncles, like the Nautilus. The animal appears, like the
+recent <i>Bulimus decollatus</i>, to have retreated at different periods of
+<span class="pagenum"><a id="page341"></a>[p.341]</span>its growth, from the internal cavity previously formed, and to
+have closed all communication with it by a septum. The number of chambers
+is irregular, and they are generally wanting in the innermost whorl.</p>
+
+<a id="img370" name="img370"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 391.</p>
+<img src="images/img370.jpg" width="400" height="400" alt="" title="">
+<p><i>Euomphalus pentagulatus</i>, Min. <span class="wosp05">Con. Mountain</span>
+limestone.</p>
+<p class="martopm05"><i>a.</i> Upper side; <i>b.</i> lower, or umbilical side; <i>c.</i> view showing mouth
+which is less pentagonal in older individuals; <i>d.</i> view of polished
+section, showing internal chambers.</p></div>
+
+<a id="img371" name="img371"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 392.</p>
+<img src="images/img371.jpg" width="300" height="142" alt="" title="">
+<p>Portion of <i>Orthoceras laterale</i>, <span class="wosp05">Phillips.
+Mountain</span> limestone.</p></div>
+
+<p>There are also many univalve and bivalve shells of existing genera in the
+Mountain limestone, such as <i>Turritella</i>, <i>Buccinum</i>, <i>Patella</i>,
+<i>Isocardia</i>, <i>Nucula</i>, and <i>Pecten</i>.<a name="FNanchor_AA_11" id="FNanchor_AA_11"></a><a href="#Footnote_AA_11" class="fnanchor">[341-A]</a> But the <i>Cephalopoda</i> depart,
+in general, more widely from living forms, some being generically distinct
+from all those found in strata newer than the coal. In this number may be
+mentioned <i>Orthoceras</i>, a siphuncled and chambered shell, like a <i>Nautilus</i>
+uncoiled and straightened. Some species of this genus are several feet long
+(<a href="#img371">fig. 392.</a>). The <i>Goniatite</i> is another genus, nearly allied to the
+<i>Ammonite</i>, from which it differs in having the lobes of the septa free
+from lateral denticulations, or crenatures; so that the outline of these is
+continuous and uninterrupted (see <i>a</i>, <a href="#img372">fig. 393.</a>). Their siphon is small,
+and in the form of the stri� of growth they resemble <i>Nautili</i>. Another
+extinct generic form of <span class="pagenum"><a id="page342"></a>[p.342]</span>Cephalopod, abounding in the Mountain
+limestone, and not found in strata of later date, is the <i>Bellerophon</i>
+(<a href="#img373">fig. 394.</a>), of which the shell, like the living Argonaut, was without
+chambers.</p>
+
+<a id="img372" name="img372"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 393.</p>
+<img src="images/img372.jpg" width="300" height="208" alt="" title="">
+<p><i>Goniatites evolutus</i>, Phillips.<a name="FNanchor_AA_12" id="FNanchor_AA_12"></a><a href="#Footnote_AA_12" class="fnanchor">[342-A]</a> Mountain
+limestone.</p></div>
+
+<a id="img373" name="img373"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 394.</p>
+<img src="images/img373.jpg" width="250" height="229" alt="" title="">
+<p><i>Bellerophon costatus</i>, Sow.<a name="FNanchor_AA_13" id="FNanchor_AA_13"></a><a href="#Footnote_AA_13" class="fnanchor">[342-B]</a> Mountain
+limestone.</p></div>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XXVI.</h2>
+
+<h4>OLD RED SANDSTONE, OR DEVONIAN GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">Old Red Sandstone of Scotland, and borders of Wales &mdash; Fossils usually
+rare &mdash; "Old Red" in Forfarshire &mdash; Ichthyolites of
+Caithness &mdash; Distinct lithological type of Old Red in Devon and
+Cornwall &mdash; Term "Devonian" &mdash; Organic remains of intermediate
+character between those of the Carboniferous and Silurian
+systems &mdash; Corals and shells &mdash; Devonian strata of Westphalia, the
+Eifel, Russia, and the United States &mdash; Coral reef at Falls of the
+Ohio &mdash; Devonian flora.</p></div>
+
+
+<p><span class="smcap">It</span> was stated in Chap. XXII. that the Carboniferous formation is surmounted
+by one called the "New Red," and underlaid by another called the "Old Red
+Sandstone."<a name="FNanchor_AB_1" id="FNanchor_AB_1"></a><a href="#Footnote_AB_1" class="fnanchor">[342-C]</a> The British strata of the last mentioned series were
+first recognized in Herefordshire and Scotland as of great thickness, and
+immediately subjacent to the coal; but they were in general so barren of
+organic remains, that it was difficult to find paleontological characters
+of sufficient importance to distinguish them as an independent group. In
+Scotland, and on the borders of Wales, the "Old Red" consists chiefly of
+red sandstone, conglomerate, and shale, with few fossils; but limestones of
+the same age, peculiarly rich in organic remains, were at length found in
+Devonshire.</p>
+
+<p>I shall first advert to the characters of the group as developed in
+Herefordshire, Worcestershire, Shropshire, and South Wales. Its thickness
+has been estimated at 8000 feet, and it has been subdivided into&mdash;</p>
+
+<p class="ftsize95">1st. A quartzose conglomerate passing downwards into chocolate-red and
+green sandstone and marl.</p>
+
+<p class="ftsize95 martopm1">2d. Cornstone and marl&mdash;red and green argillaceous spotted marls, with
+irregular courses of impure concretionary limestone, provincially called
+Cornstone.</p>
+
+<p><span class="pagenum"><a id="page343"></a>[p.343]</span>Here, as usual, fossils are extremely rare in the clays and
+sandstones in which the red oxide of iron prevails; but remains of fishes
+of the genera <i>Cephalaspis</i> and <i>Onchus</i> have been discovered in the
+Cornstone.</p>
+
+<p>The whole of the northern part of Scotland, from Cape Wrath to the southern
+flank of the Grampians, has been well described by Mr. Miller as consisting
+of a nucleus of granite, gneiss, and other hypogene rocks, which seem as if
+set in a sandstone frame.<a name="FNanchor_AB_2" id="FNanchor_AB_2"></a><a href="#Footnote_AB_2" class="fnanchor">[343-A]</a> The beds of the Old Red Sandstone
+constituting this frame, may once perhaps have extended continuously over
+the entire Grampians before the upheaval of that mountain range; for one
+band of the sandstone follows the course of the Moray Frith far into the
+interior of the great Caledonian valley; and detached hills and island-like
+patches occur in several parts of the interior, capping some of the higher
+summits in Sutherlandshire, and appearing in Morayshire like oases among
+the granite rocks of Strathspey. On the western coast of Ross-shire, the
+Old Red forms those three immense insulated hills before described (<a href="#page67">p.
+67.</a>), where beds of horizontal sandstone, 3000 feet high, rest
+unconformably on a base of gneiss, attesting the vast denudation which has
+taken place.</p>
+
+<p>But in order to observe the uppermost part of the Old Red, we must travel
+south of the Grampians, and examine its junction with the bottom of the
+Carboniferous series in Fifeshire. This upper member may be seen in Dura
+Den, south of Cupar, to consist of a belt of yellow sandstone, in which Dr.
+Fleming first discovered scales of <i>Holoptychius</i>, and in which species of
+fish of the genera <i>Pterichthys</i>, <i>Pamphractus</i>, and others, have been met
+with. (For genus <i>Pterichthys</i>, see <a href="#img379">fig. 400.</a> <a href="#page345">p. 345.</a>)</p>
+
+<p>The beds next below the yellow sandstone are well seen in the large zone of
+Old Red which skirts the southern flank of the Grampians from Stonehaven to
+the Frith of Clyde. It there forms, together with trap, the Sidlaw Hills
+and the strata of the valley of Strathmore. A section of this region has
+been already given (<a href="#page48">p. 48.</a>), extending from the foot of the Grampians in
+Forfarshire to the sea at Arbroath, a distance of about 20 miles, where the
+entire series of strata is several thousand feet thick, and may be divided
+into three principal masses: 1st, and uppermost, red and mottled marls,
+cornstone, and sandstone (Nos. 1. and 2. of the section); 2d, Conglomerate,
+often of vast thickness (No. 3. ibid.); 3d, Roofing and paving stone,
+highly micaceous, and containing a slight admixture of carbonate of lime
+(No. 4. ibid.). In the first of these divisions, which may be considered as
+succeeding the yellow sandstone of Fifeshire before mentioned, a gigantic
+species of fish of the genus <i>Holoptychius</i> has been found at Clashbinnie
+near Perth. Some scales (see <a href="#img374">fig. 395.</a>) have been seen which measured 3
+inches in length by 2<span class="smaller"><sup>1</sup>/<sub>2</sub></span> in breadth.</p>
+
+<p>At the top of the next division, or immediately under the conglomerate
+<span class="pagenum"><a id="page344"></a>[p.344]</span>(No. 3. <a href="#page48">p. 48.</a>), there have been found in Forfarshire some
+remarkable crustaceans, with several fish of the genus named by Agassiz
+<i>Cephalaspis</i>, or "buckler-headed," from the extraordinary shield which
+covers the head (see <a href="#img375">fig. 396.</a>), and which has often been mistaken for that
+of a trilobite, of the division <i>Asaphus</i>.</p>
+
+<a id="img374" name="img374"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 395.</p>
+<img src="images/img374.jpg" width="300" height="295" alt="" title="">
+<p>Scale of <i>Holoptychius nobilissimus</i>, Agas. Clashbinnie. Nat. size.</p></div>
+
+<p>Species of the same genus are considered in England as characteristic of
+the second or Cornstone division (<a href="#page343">p. 343.</a>).</p>
+
+<a id="img375" name="img375"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 396.</p>
+<img src="images/img375.jpg" width="400" height="200" alt="" title="">
+<p><i>Cephalaspis Lyellii</i>, <span class="wosp05">Agass. Length</span> 6<span class="smaller"><sup>3</sup>/<sub>4</sub></span> inches.
+From a specimen in my collection found at Glammiss, in Forfarshire. See
+other figures, Agassiz, vol. ii. tab. 1. <i>a</i>. and 1. <i>b</i>.</p>
+<ul class="martopm05 smaller leftal add1em min2em">
+<li><i>a.</i> One of the peculiar scales with which the head is covered when perfect. These
+scales are generally removed, as in the specimen above figured.</li>
+<li><i>b, c.</i> Scales from different parts of the body and tail.</li>
+</ul></div>
+
+<a id="img376" name="img376"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 397.</p>
+<img src="images/img376.jpg" width="200" height="197" alt="" title="">
+<p><i>Eggs of gasteropodous mollusk?</i> Lower beds of Old
+Red, Ley's Mill, Forfarshire.</p></div>
+
+<a id="img377" name="img377"></a>
+<div class="floatright smaller width300">
+<p>Fig. 398.</p>
+<img src="images/img377.jpg" width="300" height="185" alt="" title="">
+<p><i>Fucoids and eggs of gasteropodous mollusk?</i> Lower Old Red, Fife.</p></div>
+
+<p class="nofloat">In the same grey paving-stones and coarse roofing-slates, in which the
+<i>Cephalaspis</i> occurs, in Forfarshire and Kincardineshire, the remains of
+marine plants or fucoids abound. They are frequently accompanied by groups
+of hexagonal, or nearly hexagonal markings, which consist of small
+flattened carbonaceous bodies, placed in a slight depression of the
+sandstone or shale. (See <a href="#img376">figs. 397</a> and <a href="#img377">398.</a>) They much resemble in form the
+spawn of the recent Natica (see <span class="pagenum"><a id="page345"></a>[p.345]</span><a href="#img378">fig. 399.</a>), in which the eggs are
+arranged in a thin layer of sand, and seem to have acquired a polygonal
+form by pressing against each other. The substance of the egg, if
+fossilized, might give rise to small pellicles of carbonaceous matter.</p>
+
+<a id="img378" name="img378"></a>
+<div class="figcenter smaller width125">
+<p>Fig. 399.</p>
+<img src="images/img378.jpg" width="100" height="091" alt="" title="">
+<p>Fragment of spawn of British species of <i>Natica</i>.</p></div>
+
+<p>These fossils I have met with, both to the north of Strathmore, in the
+vertical shale beneath the conglomerate, and in the same beds in the Sidlaw
+hills, at all the points where <a href="#img016">fig. 4.</a> is introduced in the section, <a href="#page48">p. 48.</a></p>
+
+<a id="img379" name="img379"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 400.</p>
+<img src="images/img379.jpg" width="300" height="308" alt="" title="">
+<p><i>Pterichthys</i>, Agassiz; upper side, showing mouth;
+as restored by H. Miller.<a name="FNanchor_AB_3" id="FNanchor_AB_3"></a><a href="#Footnote_AB_3" class="fnanchor">[345-A]</a></p></div>
+
+<p>Beds of red shale and red sandstone, sometimes associated with
+pudding-stone (older than No. 3., <a href="#img067">fig. 62.</a> <a href="#page48">p. 48.</a>), and destitute of
+organic remains, separate, in the region of Strathmore, the above-described
+fossiliferous strata from the older crystalline rocks of the Grampians.
+But, in the north of Scotland, we find, at the base of the Old Red, other
+grey slaty sandstones, in the counties of Banff, Nairn, Moray, Cromarty,
+Caithness, and in Orkney, rich in ichthyolites of peculiar forms, belonging
+to the genera <i>Pterichthys</i> (<a href="#img379">fig. 400.</a>), <i>Coccosteus</i>, <i>Diplopterus</i>,
+<i>Dipterus</i>, <i>Cheiracanthus</i>, and others of Agassiz.</p>
+
+<p>Five species of <i>Pterichthys</i> have been found in this lowest division of
+the Old Red. The wing-like appendages, whence the genus is named, were
+first supposed by Mr. Miller to be paddles, like those of the turtle; but
+Agassiz regards them as weapons of defence, like the occipital spines of
+the River Bull-head (<i>Cottus gobio</i>, Linn.); and considers the tail to have
+been the only organ of motion. The genera <i>Dipterus</i> and <i>Diplopterus</i> are
+so named, because their two dorsal fins are so placed as to front the anal
+and ventral fins, so as to appear like two pairs of wings. They have bony
+enamelled scales.</p>
+
+<p><i>South Devon and Cornwall.</i>&mdash;A great step was made in the classification of
+the slaty and calciferous strata of South Devon and Cornwall in 1837, when
+a large portion of the beds, previously referred to the "transition" or
+most ancient fossiliferous series, were found to belong in reality to the
+period of the Old Red Sandstone. For this reform we are indebted to the
+labours of Professor Sedgwick and Sir R. Murchison, assisted by a
+suggestion of Mr. Lonsdale, who, in 1837, after examining the South
+Devonshire fossils, perceived that some of them agreed with those of the
+Carboniferous group, others with those of the Silurian, while many could
+not be assigned to either <span class="pagenum"><a id="page346"></a>[p.346]</span>system, the whole taken together
+exhibiting a peculiar and intermediate character. But these paleontological
+observations alone would not have enabled us to assign, with accuracy, the
+true place in the geological series of these slate-rocks and limestones of
+South Devon, had not Messrs. Sedgwick and Murchison, in 1836 and 1837,
+discovered that the culmiferous or anthracitic shales of North Devon
+belonged to the Coal, and not, as preceding observers had imagined, to the
+transition period.</p>
+
+<p>As the strata of South Devon here alluded to are far richer in organic
+remains than the red sandstones of contemporaneous date in Herefordshire
+and Scotland, the new name of the "Devonian system" was proposed as a
+substitute for that of Old Red Sandstone.</p>
+
+<p>The rocks of this group in South Devon consist, in great part, of green
+chloritic slates, alternating with hard quartzose slates and sandstones.
+Here and there calcareous slates are interstratified with blue crystalline
+limestone, and in some divisions conglomerates, passing into red sandstone.</p>
+
+<p>The link supplied by the whole assemblage of imbedded fossils, connecting
+as it does the paleontology of the Silurian and Carboniferous groups, is
+one of the highest interest, and equally striking, whether we regard the
+<i>genera</i> of corals or of shells. The <i>species</i> are almost all distinct.</p>
+
+<p>Among the more abundant corals, we find the genera <i>Favosites</i> and
+<i>Cyathophyllum</i>, common on the one hand to the Mountain limestone, and on
+the other to the Silurian system. Some few even of the <i>species</i> are common
+to the Devonian and Silurian groups, as, for example, <i>Favosites
+polymorpha</i> (<a href="#img380">fig. 401.</a>), very abundant in South Devon.</p>
+
+<a id="img380" name="img380"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 401.</p>
+<img src="images/img380.jpg" width="400" height="199" alt="" title="">
+<p><i>Favosites polymorpha</i>, Goldf., S. <span class="wosp05">Devon. From</span> a
+polished specimen.</p>
+<p class="martopm05"><i>a.</i> portion of the same, magnified to show the pores.</p></div>
+
+<p>The <i>Cyathophyllum c�spitosum</i> (<a href="#img382">fig. 402.</a>) and <i>Porites pyriformis</i> (<a href="#img403">fig.
+424.</a> <a href="#page356">p. 356.</a>) are more peculiarly characteristic of the Devonian rocks.</p>
+
+<p>In regard to the shells, all the brachiopodous genera, such as
+<i>Terebratula</i>, <i>Orthis</i>, <i>Spirifer</i>, <i>Atrypa</i>, and <i>Productus</i>, which are
+found in the Mountain limestone, occur, together with those of the Silurian
+system, except the <i>Pentamerus</i>. Some forms, however, seem exclusively
+Devonian, as for example, <i>Calceola sandalina</i> (<a href="#img382">fig. 403.</a>) and <span class="pagenum"><a id="page347"></a>[p.347]</span>
+<i>Strygocephalus Burtini</i> (<a href="#img383">fig. 404.</a>), which have been met with both in the
+Eifel, in Germany, and in Devonshire, in the very lowest Devonian beds.</p>
+
+<a id="img381" name="img381"></a>
+<div class="figcenter smaller width175">
+<p>Fig. 402.</p>
+<img src="images/img381.jpg" width="150" height="236" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Cyathophyllum c�spitosum</i>, Goldf., Plymouth.</li>
+<li><i>b.</i> a terminal star.</li>
+<li><i>c.</i> vertical section exhibiting transverse plates, and part
+of another branch.</li>
+</ul></div>
+
+<p>Among the peculiar lamellibranchiate bivalves, also common to Devonshire
+and the Eifel, we find <i>Megalodon cucullatus</i> (<a href="#img384">fig. 405.</a>). Several spiral
+univalves are abundant, among which are many species of <i>Pleurotomaria</i> and
+<i>Euomphalus</i>. Among the Cephalopoda we find <i>Bellerophon</i> and <i>Orthoceras</i>,
+as in the Silurian and Carboniferous groups, and <i>Goniatite</i> and
+<i>Cyrtoceras</i>, as in the Carboniferous. In some of the upper Devonian beds,
+a shell, resembling a flattened <i>Goniatite</i>, occurs, called <i>Clymenia</i>, by
+Munster (<i>Endosiphonites</i>, Ansted.<a name="FNanchor_AB_4" id="FNanchor_AB_4"></a><a href="#Footnote_AB_4" class="fnanchor">[347-A]</a>).</p>
+
+<a id="img382" name="img382"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 403.</p>
+<img src="images/img382.jpg" width="350" height="142" alt="" title="">
+<p><i>Calceola sandalina</i>,<span class="wosp05"> Lam. Eifel;</span>
+also South Devon.</p>
+<ul class="smaller leftal add1em min1em martopm05">
+<li><i>a.</i> both valves united.</li>
+<li><i>b.</i> inner side of opercular valve.</li>
+</ul></div>
+
+<a id="img383" name="img383"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 404.</p>
+<img src="images/img383.jpg" width="400" height="148" alt="" title="">
+<p><i>Strygocephalus Burtini</i><span class="wosp05">. (</span><i>Terebratula porrecta</i>,
+<span class="wosp05">Sow.) Eifel;</span> also South Devon.</p>
+<ul class="smaller leftal add1em min1em martopm05">
+<li><i>a.</i> valves united.</li>
+<li><i>b</i>. side view of same.</li>
+<li><i>c.</i> interior of larger valve, showing thick partition, and thinner
+one continued from it.</li>
+</ul></div>
+
+<a id="img384" name="img384"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 405.</p>
+<img src="images/img384.jpg" width="400" height="276" alt="" title="">
+<p><i>Megalodon cucullatus</i>, <span class="wosp05">Sow. Eifel;</span>
+also Bradley, S. Devon.</p>
+<ul class="smaller leftal add1em min1em martopm05">
+<li><i>a.</i> the valves united.</li>
+<li><i>b.</i> interior of valve, showing the large cardinal tooth.</li>
+</ul></div>
+
+<span class="pagenum"><a id="page348"></a>[p.348]</span>
+<a id="img385" name="img385"></a>
+<div class="figcenter smaller width400">
+<p class="martop2">Fig. 406.</p>
+<img src="images/img385.jpg" width="400" height="264" alt="" title="">
+<p><i>Clymenia linearis</i>, <span class="wosp05">Munster.
+(</span><i>Endosiphonites carinatus</i>, <span class="wosp05">Ansted.) Cornwall.</span></p></div>
+
+<p>A peculiar species of trilobite, called <i>Brontes flabellifer</i> (<a href="#img386">fig. 407.</a>),
+is found in the Devonian strata of the Eifel and in South Devon. It should
+be observed, however, that the head in the specimen here figured by
+Goldfuss, the most perfect which could be obtained, is incomplete, and a
+restoration has been attempted by Mr. Salter in <a href="#img387">fig. 408.</a>, from data
+supplied by other species of the same genus occurring in older rocks.</p>
+
+<a id="img386" name="img386"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 407.</p>
+<img src="images/img386.jpg" width="200" height="372" alt="" title="">
+<p><i>Brontes flabellifer</i>, Goldf. Eifel; also S. Devon.</p></div>
+
+<a id="img387" name="img387"></a>
+<div class="floatright smaller width200">
+<p>Fig. 408.</p>
+<img src="images/img387.jpg" width="200" height="122" alt="" title="">
+<p>Restored outline of head of <i>Brontes flabellifer</i>.</p></div>
+
+<p class="nofloat">For determining the true equivalents of the Devonian group in the Rhenish
+provinces and adjacent parts of Germany, we are indebted to the labours of
+Messrs. Sedgwick and Murchison, in 1839, from which it appears that rocks
+of that age emerge from beneath the coal-field of Westphalia, and are also
+found in troughs among the Silurian rocks in Nassau. Many of the
+limestones, particularly those on the river Lahn, are identical, both in
+structure and in coralline remains, with the beautiful marbles of
+Babbacombe, Torquay, and Plymouth.</p>
+
+<p>The limestones of the Eifel, long ago celebrated for their fossils, and
+which lie in a basin supported by Silurian rocks, are found to be referable
+to the lower part of the Devonian system.</p>
+
+<p>In Russia, also, Messrs. Murchison and De Verneuil have shown (1840) that
+the "Old Red" group occupies a wide area south from St. Petersburg. It was
+formerly supposed to be the New Red Sandstone, on account of its saliferous
+and gypseous beds; but it is <span class="pagenum"><a id="page349"></a>[p.349]</span>now proved to be the Old Red by
+containing ichthyolites of genera which characterize this group in the
+British Isles, as, for example, <i>Holoptychius</i>, <i>Coccosteus</i>,
+<i>Diplopterus</i>, &amp;c.<a name="FNanchor_AB_5" id="FNanchor_AB_5"></a><a href="#Footnote_AB_5" class="fnanchor">[349-A]</a>, associated with mollusca found in the Devonian
+of Western Europe. Among the fish are also many species of sharks of the
+Cestraciont division, a fact worthy of notice, because the squaloid fishes
+of the present day offer the highest organization of the brain and of the
+generative organs, and make, in these respects, the nearest approach to the
+higher vertebrate classes.</p>
+
+
+<h3><i>Devonian Strata in the United States.</i></h3>
+
+<p>The position of this formation between the carboniferous rocks of
+Pennsylvania and Ohio, is pointed out in the section, <a href="#img358">fig. 379.</a> <a href="#page328">p. 327.</a>,
+and it is a remark of M. de Verneuil that in no European country is there
+so complete and uninterrupted a development of the Devonian system as in
+North America. At the falls of the Ohio, at Louisville, in Kentucky, there
+is a grand display of one of the limestones of this period, resembling a
+modern coral reef. A wide extent of surface is exposed in a series of
+horizontal ledges, at all seasons, when the water is not high; and the
+softer parts of the stone having decomposed and wasted away, the harder
+calcareous corals stand out in relief, and many of them send out branches
+from their erect stems precisely as if they were living. Among other
+species I observed large masses, not less than 5 feet in diameter, of
+<i>Favosites gothlandica</i>, with its beautiful honeycomb structure well
+displayed, and, by the side of it, the <i>Favistella</i>, combining a similar
+honeycombed form with the star of the <i>Astrea</i>. There was also the
+cup-shaped <i>Cyathophyllum</i>, and the delicate network of the <i>Fenestella</i>,
+and that elegant and well-known European species of fossil, called "the
+chain coral," <i>Catenipora escharoides</i>, with a profusion of others (see
+<a href="#img402">fig. 423.</a> <a href="#page355">p. 355.</a>). These coralline forms were mingled with the joints,
+stems, and occasionally the heads, of lily encrinites. Although hundreds of
+fine specimens have been detached from these rocks, to enrich the museums
+of Europe and America, another crop is constantly working its way out,
+under the action of the stream, and of the sun and rain, in the warm season
+when the channel is laid dry. The waters of the Ohio, when I visited the
+spot in April, 1846, were more than 40 feet below their highest level, and
+20 feet above their lowest, so that large spaces of bare rock were exposed
+to view.<a name="FNanchor_AB_6" id="FNanchor_AB_6"></a><a href="#Footnote_AB_6" class="fnanchor">[349-B]</a></p>
+
+
+<h3><i>Devonian Flora.</i></h3>
+
+<p>With the exception of the fucoids above mentioned (<a href="#page344">p. 344.</a>), but little is
+known with certainty of the plants of the Devonian group. Those found in
+the department of La Sarthe in France, and in various parts of Brittany,
+formerly referred to the Devonian era, have been <span class="pagenum"><a id="page350"></a>[p.350]</span>shown (in 1850),
+by M. de Verneuil, to belong to the carboniferous series. The same may be
+said of the species of <i>Lepidodendron</i>, <i>Knorria</i>, <i>Calamite</i>, <i>Sagenaria</i>,
+and other genera recently figured (1850), by Mr. F. A. R�mer, from the
+formation called "Greywack� � Posodonomyes" in the Hartz.<a name="FNanchor_AB_7" id="FNanchor_AB_7"></a><a href="#Footnote_AB_7" class="fnanchor">[350-A]</a> They are
+accompanied by <i>Goniatites reticulatus</i> Phillips, <i>G. intercostatus</i> Phil.,
+and other mountain limestone species, and had been previously assigned to
+the oldest part of the carboniferous series by Messrs. Murchison and
+Sedgwick.</p>
+
+<p>If hereafter we should become well acquainted with the land plants of the
+Devonian era, we may confidently expect that nearly all of them will agree
+generically with those of the carboniferous period, but the species will be
+as different as are the Devonian vertebrate and invertebrate animals from
+the fossil species of the Coal.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XXVII.</h2>
+
+<h4>SILURIAN GROUP.</h4>
+
+<div class="blq1">
+<p class="indentm2">Silurian strata formerly called transition &mdash; Term
+grauwack� &mdash; Subdivisions of Upper and Lower Silurian &mdash; Ludlow
+formation and fossils &mdash; Wenlock formation, corals and
+shells &mdash; Caradoc and Llandeilo beds &mdash; Graptolites &mdash;
+Lingula &mdash; Trilobites &mdash; Cystide� &mdash; Vast
+thickness of Silurian strata in North Wales &mdash; Unconformability of
+Caradoc sandstone &mdash; Silurian strata of the United States &mdash; Amount
+of specific agreement of fossils with those of Europe &mdash; Great number of
+brachiopods &mdash; Deep-sea origin of Silurian strata &mdash; Absence of
+fluviatile formations &mdash; Mineral character of the most ancient
+fossiliferous rocks.</p></div>
+
+
+<p><span class="smcap">We</span> come next in the descending order to the most ancient of the primary
+fossiliferous rocks, that series which comprises the greater part of the
+strata formerly called "transition" by Werner, for reasons explained in
+Chap. VIII., pp. <a href="#page91">91</a> and <a href="#page92">92.</a> Geologists have also applied to these older
+strata the general name of "grauwack�," by which the German miners
+designate a particular variety of sandstone, usually an aggregate of small
+fragments of quartz, flinty slate (or Lydian stone), and clay-slate
+cemented together by argillaceous matter. Far too much importance has been
+attached to this kind of rock, as if it belonged to a certain epoch in the
+earth's history, whereas a similar sandstone or grit is found sometimes in
+the Old Red, and in the Millstone Grit of the Coal, and sometimes in
+certain Cretaceous and even Eocene formations in the Alps.</p>
+
+<p>The name of <i>Silurian</i> was first proposed by Sir Roderick Murchison, for a
+series of fossiliferous strata lying below the Old Red Sandstone, and
+occupying that part of Wales and some contiguous counties of England, which
+once constituted the kingdom of the <i>Silures</i>, a tribe of ancient Britons.
+The strata have been divided <span class="pagenum"><a id="page351"></a>[p.351]</span>into Upper and Lower Silurian, and
+these again in the region alluded to admit of several well-marked
+subdivisions, all of them explained in the following table.</p>
+
+
+<table  border="0" cellpadding="2" summary="DIVISION AND CHARACTERISTICS OF SILURIAN ROCKS
+IN ENGLAND.">
+<colgroup>
+    <col width="15%">
+    <col width="3%">
+    <col width="1%">
+    <col width="3%">
+    <col width="15%">
+    <col width="3%">
+    <col width="1%">
+    <col width="1%">
+    <col width="3%">
+    <col width="15%">
+    <col width="3%">
+    <col width="1%">
+    <col width="3%">
+    <col width="10%">
+    <col width="3%">
+    <col width="1%">
+    <col width="1%">
+    <col width="3%">
+    <col width="15%">
+</colgroup>
+
+<tr>
+  <td colspan="19" class="td-center tdtx-mid ftsize110">UPPER SILURIAN ROCKS.</td>
+</tr>
+
+<tr>
+  <td colspan="9">&nbsp;</td>
+  <td class="td-center tdtx-mid smaller">Prevailing Lithological characters.</td>
+  <td colspan="3">&nbsp;</td>
+  <td class="td-center tdtx-mid smaller">Thickness in Feet.</td>
+  <td colspan="3">&nbsp;</td>
+  <td colspan="2" class="td-center tdtx-mid smaller">Organic Remains.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td colspan="19">&nbsp;</td>
+</tr>
+
+<tr>
+  <td rowspan="7" class="tdtx-mid td-left">1. Ludlow<br>formation</td>
+  <td rowspan="7">&nbsp;</td>
+  <td rowspan="7" class="borright">&nbsp;</td>
+  <td rowspan="7">&nbsp;</td>
+  <td class="tdtx-mid td-left">Tilestones.</td>
+  <td rowspan="7" colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td rowspan="7">&nbsp;</td>
+  <td class="tdtx-mid td-left">Finely laminated reddish and green sandstones and shales.</td>
+  <td rowspan="7">&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td rowspan="7">&nbsp;</td>
+  <td class="tdtx-mid td-center">800?</td>
+  <td rowspan="7" colspan="2">&nbsp;</td>
+  <td rowspan="7" class="borright">&nbsp;</td>
+  <td rowspan="7">&nbsp;</td>
+  <td rowspan="7" class="tdtx-mid td-left">Marine mollusca of almost every order, the Brachiopoda most
+  abundant. Serpula, Corals, Sauroid fish, Fuci.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left">Upper Ludlow.</td>
+  <td class="borright">&nbsp;</td>
+  <td class="tdtx-mid td-left">Micaceous grey sandstone.</td>
+  <td rowspan="5" class="borleft">&nbsp;</td>
+  <td rowspan="5" class="tdtx-mid td-center">2000</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left">Aymestry limestone.</td>
+  <td class="borright">&nbsp;</td>
+  <td class="tdtx-mid td-left">Argillaceous limestone.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left">Lower Ludlow.</td>
+  <td class="borright">&nbsp;</td>
+  <td class="tdtx-mid td-left">Shale, with concretions of limestone.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td colspan="19">&nbsp;</td>
+</tr>
+
+<tr>
+  <td rowspan="3" class="tdtx-mid td-left">2. Wenlock formation.</td>
+  <td rowspan="3">&nbsp;</td>
+  <td rowspan="3" class="borright">&nbsp;</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="tdtx-mid td-left">Wenlock limestone.</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td rowspan="3" colspan="2">&nbsp;</td>
+  <td class="tdtx-mid td-left">Concretionary limestone.</td>
+  <td rowspan="3">&nbsp;</td>
+  <td rowspan="3" class="borleft">&nbsp;</td>
+  <td rowspan="3">&nbsp;</td>
+  <td rowspan="3" class="tdtx-mid td-center">1800</td>
+  <td rowspan="3" colspan="2">&nbsp;</td>
+  <td rowspan="3" class="borright">&nbsp;</td>
+  <td rowspan="3">&nbsp;</td>
+  <td rowspan="3" class="tdtx-mid td-left">Marine mollusca of various orders as before, Crustaceans
+  of the Trilobite family.<br>Oldest bones of fish yet known.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left">Wenlock shale.</td>
+  <td class="borleft">&nbsp;</td>
+  <td class="tdtx-mid td-left">Argillaceous shale.</td>
+</tr>
+
+<tr>
+  <td colspan="19" class="td-center tdtx-mid martop2 ftsize110">LOWER SILURIAN ROCKS.</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left">3. Caradoc formation.</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="tdtx-mid td-left">Caradoc sandstones.</td>
+  <td rowspan="2" colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="tdtx-mid td-left">Flags of shelly limestone and sandstone, thick bedded white freestone.</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td rowspan="3">&nbsp;</td>
+  <td class="tdtx-mid td-center">2500</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdtx-mid td-left">Crinoidea, Corals, Mollusca, chiefly Brachiopoda, Trilobites.</td>
+</tr>
+
+<tr class="ftsizexs">
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td>&nbsp;</td>
+  <td colspan="5">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="tdtx-mid td-left">4. Llandeilo<br>formation.</td>
+  <td class="borright">&nbsp;</td>
+  <td class="tdtx-mid td-left">Llandeilo flags.</td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdtx-mid td-left">Dark coloured calcareous flags.</td>
+  <td class="borleft">&nbsp;</td>
+  <td class="tdtx-mid td-center">1200</td>
+  <td colspan="4">&nbsp;</td>
+  <td class="tdtx-mid td-left">Mollusca, Trilobites.</td>
+</tr>
+</table>
+
+
+<h3>UPPER SILURIAN ROCKS.</h3>
+
+<p><i>Ludlow formation.</i>&mdash;This member of the Upper Silurian group, as will be
+seen by the above table, is of great thickness, and subdivided into four
+parts,&mdash;the Tilestone, the Upper and Lower Ludlow, and the intervening
+Aymestry limestone. Each of these may be distinguished near the town of
+Ludlow, and at other places in Shropshire and Herefordshire, by peculiar
+organic remains.</p>
+
+<p>1. <i>Tilestones.</i>&mdash;This uppermost division was originally classed by Sir R.
+Murchison with the Old Red Sandstone, because they decompose into a red
+soil throughout the Silurian region. At the same time he regarded the
+tilestones as a transition group forming a passage from Silurian to Old
+Red. It is now ascertained that the fossils agree in great part
+specifically, and in general character entirely, with those of the
+succeeding formation.</p>
+
+<p>2. <i>Upper Ludlow.</i>&mdash;The next division, called the Upper Ludlow, consists of
+grey calcareous sandstone, decomposing into soft mud, and contains, among
+other shells, the <i>Lingula cornea</i>, which is common to it and the lowest,
+or tilestone beds of the Old Red. But <span class="pagenum"><a id="page352"></a>[p.352]</span>the <i>Orthis orbicularis</i> is
+peculiar to the Upper Ludlow, and very common; and the lowest or mudstone
+beds, are loaded for a thickness of 30 feet with <i>Terebratula navicula</i>
+(<a href="#img389">fig. 410.</a>), in vast numbers. Among the cephalopodous mollusca occur the
+genera <i>Bellerophon</i> and <i>Orthoceras</i>, and among the crustacea the
+<i>Homalonotus</i> (<a href="#img397">fig. 418.</a> <a href="#page354">p. 354.</a>). A coral called <i>Favosites polymorpha</i>,
+Goldf. (<a href="#img331">fig. 401.</a> <a href="#page346">p. 346.</a>) is found both in this subdivision and in the
+Devonian system.</p>
+
+<a id="img388" name="img388"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 409.</p>
+<img src="images/img388.jpg" width="200" height="081" alt="" title="">
+<p><i>Orthis orbicularis</i>, J. <span class="wosp05">Sow. Delbury.</span>
+Upper Ludlow.</p></div>
+
+<a id="img389" name="img389"></a>
+<div class="floatright smaller width200">
+<p>Fig. 410.</p>
+<img src="images/img389.jpg" width="200" height="105" alt="" title="">
+<p><i>Terebratula navicula</i>, J. Sow. Aymestry
+limestone; also in Upper and Lower Ludlow.</p></div>
+
+<p class="nofloat">Among the fossil shells are species of <i>Lept�na</i>, <i>Orthis</i>, <i>Terebratula</i>,
+<i>Avicula</i>, <i>Trochus</i>, <i>Orthoceras</i>, <i>Bellerophon</i>, and others.<a name="FNanchor_AC_1" id="FNanchor_AC_1"></a><a href="#Footnote_AC_1" class="fnanchor">[352-A]</a></p>
+
+<p>Some of the Upper Ludlow sandstones are ripple-marked, thus affording
+evidence of gradual deposition; and the same may be said of the
+accompanying fine argillaceous shales which are of great thickness, and
+have been provincially named "mudstones." In these shales many zoophytes
+are found enveloped in an erect position, having evidently become fossil on
+the spots where they grew at the bottom of the sea. The facility with which
+these rocks, when exposed to the weather, are resolved into mud, proves
+that, notwithstanding their antiquity, they are nearly in the state in
+which they were first thrown down.</p>
+
+<p>The scales, spines (<i>ichthyodorulites</i>), jaws, and teeth of fish of the
+genera <i>Onchus</i>, <i>Plectrodus</i>, and others of the same family, have been met
+with in the Upper Ludlow rocks.</p>
+
+<a id="img390" name="img390"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 411.</p>
+<img src="images/img390.jpg" width="400" height="200" alt="" title="">
+<p><i>Pentamerus Knightii</i>, <span class="wosp05">Sow. Aymestry.</span></p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> view of both valves united.</li>
+<li><i>b.</i> longitudinal section through both valves, showing the central
+plate or septum; half nat. size.</li>
+</ul></div>
+
+<p>3. <i>Aymestry limestone.</i>&mdash;The next group is a subcrystalline and
+argillaceous limestone, which is in some places 50 feet thick, and
+distinguished around Aymestry by the abundance of <i>Pentamerus Knightii</i>,
+Sow. (<a href="#img390">fig. 411.</a>), also found in the Lower Ludlow. This <span class="pagenum"><a id="page353"></a>[p.353]</span>genus of
+brachiopoda has only been found in the Silurian strata. The name was
+derived from &#960;&#949;&#957;&#964;&#949;, <i>pente</i>, five, and &#956;&#949;&#961;&#959;&#962;, <i>meros</i>, a
+part, because both valves are divided by a central septum, making four
+chambers, and in one valve the septum itself contains a small chamber,
+making five; but neither the structure of this shell, nor the connection of
+the animal with its several parts, are as yet understood. Messrs. Murchison
+and De Verneuil discovered this species dispersed in myriads through a
+white limestone of upper Silurian age, on the banks of the Is, on the
+eastern flank of the Urals in Russia.</p>
+
+<a id="img391" name="img391"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 412.</p>
+<img src="images/img391.jpg" width="150" height="228" alt="" title="">
+<p><i>Lingula Lewisii</i>, J. Sow. Abberley Hills.</p></div>
+
+<p>Three other abundant shells in the Aymestry limestone are, 1st, <i>Lingula
+Lewisii</i> (<a href="#img391">fig. 412.</a>); 2d, <i>Terebratula Wilsoni</i>, Sow. (<a href="#img392">fig. 413.</a>), which is
+also common to the Lower Ludlow and Wenlock limestone; 3d, <i>Atrypa
+reticularis</i>, Lin. (<a href="#img435">fig. 414.</a>), which has a very wide range, being found in
+every part of the Silurian system, except the Llandeilo flags.</p>
+
+<a id="img392" name="img392"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 413.</p>
+<img src="images/img392.jpg" width="350" height="091" alt="" title="">
+<p><i>Terebratula Wilsoni</i>, <span class="wosp05">Sow. Aymestry.</span></p></div>
+
+<a id="img393" name="img393"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 414.</p>
+<img src="images/img393.jpg" width="350" height="230" alt="" title="">
+<p><i>Atrypa reticularis.</i> <span class="wosp05">Linn. Syn.</span> <i>Terebratula
+affinis</i>, Min. Con. Aymestry.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> upper valve.</li>
+<li><i>b.</i> lower.</li>
+<li><i>c.</i> anterior margin of the valves.</li>
+</ul></div>
+
+<p>4. <i>Lower Ludlow shale.</i>&mdash;A dark grey argillaceous deposit, containing,
+among other fossils, the new genera of chambered shells, the <i>Phragmoceras</i>
+of Broderip, and the <i>Lituites</i> of Breyn (see <a href="#img394">figs. 415</a>, <a href="#img395">416.</a>). The latter
+is partly straight and partly convoluted, nearly as in <i>Spirula</i>.</p>
+
+<span class="pagenum"><a id="page354"></a>[p.354]</span>
+<a id="img394" name="img394"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 415.</p>
+<img src="images/img394.jpg" width="250" height="196" alt="" title="">
+<p><i>Phragmoceras ventricosum</i>, J. Sow. (<i>Orthoceras ventricosum</i>,
+Stein.) Aymestry; <sup>1</sup>/<sub>4</sub> nat. size.</p></div>
+
+<a id="img395" name="img395"></a>
+<div class="floatright smaller width250">
+<p>Fig. 416.</p>
+<img src="images/img395.jpg" width="250" height="224" alt="" title="">
+<p><i>Lituites giganteus</i>, J. Sow. Near Ludlow; also in
+the Aymestry and Wenlock limestones; <sup>1</sup>/<sub>4</sub> nat. size.</p></div>
+
+<a id="img396" name="img396"></a>
+<div class="nofloat figcenter smaller width250">
+<p class="martop2">Fig. 417.</p>
+<img src="images/img396.jpg" width="250" height="133" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> Fragment of <i>Orthoceras Ludense</i>, J. Sow.</li>
+<li><i>b.</i> Polished section, showing <span class="wosp05">siphuncle. Ludlow.</span></li>
+</ul></div>
+
+<p>The <i>Orthoceras Ludense</i> (<a href="#img396">fig. 417.</a>), as well as the shell last mentioned,
+is peculiar to this member of the series. The <i>Homalonotus
+delphinocephalus</i> (<a href="#img397">fig. 418.</a>) is common to this division and to the Wenlock
+limestone. This crustacean belongs to a group of trilobites which has been
+met with in the Silurian rocks only, and in which the tripartite character
+of the dorsal crust is almost lost.</p>
+
+<a id="img397" name="img397"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 418.</p>
+<img src="images/img397.jpg" width="150" height="335" alt="" title="">
+<p><i>Homalonotus delphinocephalus</i>, K�nig.<a name="FNanchor_AC_2" id="FNanchor_AC_2"></a><a href="#Footnote_AC_2" class="fnanchor">[354-A]</a>
+Dudley Castle; <sup>1</sup>/<sub>2</sub> nat. size.</p></div>
+
+<p>A species of Graptolite, <i>G. Ludensis</i>, Murch. (<a href="#img398">fig. 419.</a>), a form of
+zoophyte which has not yet been met with in strata newer than the Silurian,
+occurs in the Lower Ludlow.</p>
+
+<p><i>Wenlock formation.</i>&mdash;We next come to the Wenlock formation, which has been
+divided (see Table, <a href="#page351">p. 351.</a>) into</p>
+
+<p>1. Wenlock limestone, formerly well known to collectors by the name of the
+Dudley limestone, which forms a continuous ridge, ranging for about 20
+miles from S.W. to N.E., about a mile distant from the nearly parallel
+escarpment of the Aymestry limestone. The prominence of this rock in
+Shropshire, like that of Aymestry, is due to its solidity, and to the
+softness <span class="pagenum"><a id="page355"></a>[p.355]</span>of the shales above and below. It is divided into large
+concretional masses of pure limestone, and abounds in trilobites, among
+which the prevailing species are <i>Phacops caudatus</i> (<a href="#img401">fig. 422.</a>) and
+<i>Calymene Blumenbachii</i>, commonly called the Dudley trilobite. The latter
+is often found coiled up like a wood-louse (see <a href="#img399">fig. 420.</a>).</p>
+
+<a id="img398" name="img398"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 419.</p>
+<img src="images/img398.jpg" width="150" height="016" alt="" title="">
+<p>Fig. 419. <i>Graptolithus Ludensis</i>, Murchison. Lower Ludlow.</p></div>
+
+<a id="img399" name="img399"></a>
+<div class="figcenter smaller width125">
+<p class="martop2">Fig. 420.</p>
+<img src="images/img399.jpg" width="125" height="112" alt="" title="">
+<p><i>Calymene Blumenbachii</i>, Brong. Wenlock, L. Ludlow, and Aym. limest.</p></div>
+
+<a id="img400" name="img400"></a>
+<div class="figcenter smaller width150">
+<p class="martop2">Fig. 421.</p>
+<img src="images/img400.jpg" width="150" height="104" alt="" title="">
+<p><i>Lept�na depressa</i><span class="wosp05">. Wenlock.</span></p></div>
+
+<a id="img401" name="img401"></a>
+<div class="figcenter smaller width150">
+<p class="martop2">Fig. 422.</p>
+<img src="images/img401.jpg" width="150" height="236" alt="" title="">
+<p><i>Phacops caudatus</i>, Brong. Wenlock, Aym. limest., and L. Ludlow.</p></div>
+
+<p><i>Lept�na depressa</i>, Sow., is common in this rock, but also ranges through
+the Lower Ludlow, Wenlock shale, and Caradoc Sandstone.</p>
+
+<a id="img402" name="img402"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 423.</p>
+<img src="images/img402.jpg" width="150" height="223" alt="" title="">
+<p><i>Catenipora escharoides.</i></p></div>
+
+<p>Among the corals in which this formation is very rich, the <i>Catenipora
+escharoides</i>, Lam. (<a href="#img402">fig. 423.</a>), or chain coral, may be pointed out as one
+very easily recognized, and widely spread in Europe, ranging through all
+parts of the Silurian group, from the Aymestry limestone to the bottom of
+the series.</p>
+
+<p>Another coral, the <i>Porites pyriformis</i>, is also met with in profusion; a
+species common to the Devonian rocks.</p>
+
+<p><i>Cystiphyllum Siluriense</i> (<a href="#img404">fig. 425.</a>) is a species peculiar to the Wenlock
+limestone. This new genus, the name of which is derived from &#954;&#965;&#963;&#964;&#953;&#962;,
+a <i>bladder</i>, and &#966;&#965;&#955;&#955;&#959;&#957;, a <i>leaf</i>, was instituted by Mr.
+Lonsdale for corals of the Silurian and Devonian groups. It is composed of
+small bladder-like cells (see <a href="#img404">fig. 425. <i>b.</i></a>).</p>
+
+<p>2. The Wenlock Shale, which exceeds 700 feet in thickness, contains many
+species of brachiopoda, such as a small variety of the <span class="pagenum"><a id="page356"></a>[p.356]</span><i>Lingula
+Lewisii</i> (<a href="#img391">fig. 412.</a>), and the <i>Atrypa reticularis</i> (<a href="#img393">fig. 414.</a>) before
+mentioned, and it will be seen that several other fossils before enumerated
+range into this shale.</p>
+
+<a id="img403" name="img403"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 424.</p>
+<img src="images/img403.jpg" width="250" height="111" alt="" title="">
+<p><i>Porites pyriformis</i>, Ehren. Wenlock limest. and
+<span class="wosp05">shale. Also</span> in Aymestry limestone, and L. Ludlow.</p>
+<p class="martopm05"><i>a.</i> Vertical section, showing transverse lamell�.</p></div>
+
+<a id="img404" name="img404"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 425.</p>
+<img src="images/img404.jpg" width="250" height="108" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> <i>Cystiphyllum Siluriense</i>, <span class="wosp05">Lonsd. Wenlock.</span></li>
+<li><i>b.</i> Section of portion, showing cells.</li>
+</ul></div>
+
+
+<h3>LOWER SILURIAN ROCKS.</h3>
+
+<p>The Lower Silurian rocks have been subdivided into two portions.</p>
+
+<p>1. The Caradoc sandstone, which abuts against the trappean chain called the
+Caradoc Hills, in Shropshire. Its thickness is estimated at 2500 feet, and
+the larger proportion of its fossils are specifically distinct from those
+of the Upper Silurian rocks. Among them we find many trilobites and shells
+of the genera <i>Orthoceras</i>, <i>Nautilus</i>, and <i>Bellerophon</i>; and among the
+Brachiopoda the <i>Pentamerus oblongus</i> and <i>P. l�vis</i> (<a href="#img405">fig. 426.</a>), which are
+very abundant and peculiar to this bed; also <i>Orthis grandis</i> (<a href="#img406">fig. 427.</a>),
+and a fossil of well-defined form, <i>Tentaculites annulatus</i>, Schlot. (<a href="#img407">fig.
+428.</a>), which Mr. Salter has shown to be referable to the Annelids and to
+the same tribe as <i>Serpula</i>.</p>
+
+<a id="img405" name="img405"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 426.</p>
+<img src="images/img405.jpg" width="350" height="272" alt="" title="">
+<p><i>Pentamerus l�vis</i>, <span class="wosp05">Sow. Caradoc</span> Sandstone.
+Perhaps the young of <i>Pentamerus oblongus</i>.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a, b.</i> Views of the shell itself, from figures in Murchison's Sil. Syst.</li>
+<li><i>c.</i> Cast with portion of shell remaining, and with the hollow of the
+central septum filled with spar.</li>
+<li><i>d.</i> Internal cast of a valve, the space once occupied by the septum
+being represented by a hollow in which is seen a cast of the chamber
+within the septum.</li>
+</ul></div>
+
+<span class="pagenum"><a id="page357"></a>[p.357]</span>
+<a id="img406" name="img406"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 427.</p>
+<img src="images/img406.jpg" width="250" height="192" alt="" title="">
+<p>Cast of <i>Orthis grandis</i>, J. Sow. Horderley; two-thirds of nat. size.</p></div>
+
+<a id="img407" name="img407"></a>
+<div class="figcenter smaller width250">
+<p class="martop2">Fig. 428.</p>
+<img src="images/img407.jpg" width="250" height="143" alt="" title="">
+<p><i>Tentaculites scalaris</i>, Schlot. Eastnor Park; nat. size,
+and magnified.</p></div>
+
+<p>The most ancient bony remains of fish yet discovered in Great Britain are
+those obtained from the Wenlock limestones; but coprolites referred to fish
+occur still lower in the Silurian series in Wales.</p>
+
+<a id="img408" name="img408"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 429.</p>
+<img src="images/img408.jpg" width="150" height="219" alt="" title="">
+<p><i>Ogygia Buchii</i>, Burmeister. Syn. <i>Asaphus Buchii</i>, Brong.
+<sup>1</sup>/<sub>4</sub> nat. size. Radnorshire.</p></div>
+
+<p>2. The <i>Llandeilo flags</i>, so named from a town in Caermarthenshire, form
+the base of the Silurian system, consisting of dark-coloured micaceous
+grit, frequently calcareous, and distinguished by containing the large
+trilobites <i>Asaphus Buchii</i> and <i>A. tyrannus</i>, Murch., both of which are
+peculiar to these rocks. Several species of Graptolites (<a href="#img409">fig. 430.</a>) occur
+in these beds.</p>
+
+<a id="img409" name="img409"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 430.</p>
+<img src="images/img409.jpg" width="200" height="133" alt="" title="">
+<p><i>a</i>, <i>b</i>. <i>Graptolithus Murchisonii</i>, Beck.
+Llandeilo flags.</p></div>
+
+<a id="img410" name="img410"></a>
+<div class="figcenter smaller width200">
+<p class="martop2">Fig. 431.</p>
+<img src="images/img410.jpg" width="200" height="042" alt="" title="">
+<p><i>G. foliaceus</i>, <i>Murchison</i>. Llandeilo flags.</p></div>
+
+<p>In the fine shales of this formation Graptolites are very abundant. I
+collected these same bodies in great numbers in Sweden and Norway in
+1835-6, both in the higher and lower shales of the Silurian system; and was
+informed by Dr. Beck of Copenhagen, that they were fossil zoophytes related
+to the genera <i>Pennatula</i> and <i>Virgularia</i>, of which the living species now
+inhabit mud and slimy sediment. The most eminent naturalists still hold to
+this opinion.</p>
+
+<p>A species of <i>Lingula</i> is met with in the lowest part of the Llandeilo
+beds; and it is remarkable that this brachiopod is among the earliest, if
+not the most ancient animal form detected in the lowest Silurian of North
+America. These inhabitants of the seas, of so remote an epoch, belonged so
+strictly to the living genus <i>Lingula</i>, as to demonstrate, like the
+pteriform ferns of the coal, through what incalculable periods of time the
+same plan and type of organization has sometimes prevailed.</p>
+
+<p>Among the forms of trilobite extremely characteristic of the Lower Silurian
+throughout Europe and North America, the <i>Trinucleus</i> may be mentioned.
+This family of crustaceans appears to have swarmed in the Silurian seas,
+just as crabs, shrimps, and other genera of <span class="pagenum"><a id="page358"></a>[p.358]</span>crustaceans abound in
+our own. Burmeister, in his work on the organization of trilobites,
+supposes them to have swum at the surface of the water in the open sea and
+near coasts, feeding on smaller marine animals, and to have had the power
+of rolling themselves into a ball as a defence against injury. They
+underwent various transformations analogous to those of living crustaceans.
+M. Barrande, author of a work on the Silurian rocks of Bohemia, has traced
+the same species from the young state just after its escape from the egg to
+the adult form, through various metamorphoses, each having the appearance
+of a distinct species. Yet, notwithstanding the numerous species of
+preceding naturalists which he has thus succeeded in uniting into one, he
+announces a forthcoming work in which descriptions and figures of 250
+species of Trilobite will be given.</p>
+
+<a id="img411" name="img411"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 432.</p>
+<img src="images/img411.jpg" width="350" height="355" alt="" title="">
+<p><i>Trinucleus ornatus</i>, Burm.</p></div>
+
+<p><i>Cystide�.</i>&mdash;Among the additions which recent research has made to the
+paleontology of the oldest Silurian rocks, none are more remarkable than
+the radiated animals called <i>Cystide�</i>. Their structure and relations were
+first elucidated in an essay published by Von Buch at Berlin in 1845. They
+are usually met with as spheroidal bodies covered with polygonal plates,
+with a mouth on the upper side, and a point of attachment for a stem <i>b</i>
+(which is almost always broken off) on the lower. (See <a href="#img412">fig. 433.</a>) They are
+considered by Professor E. Forbes as intermediate between the crinoids and
+echinoderms. The <i>Sph�ronites</i> here represented (<a href="#img412">fig. 433.</a>) occurs in the
+Llandeilo beds in Wales.<a name="FNanchor_AC_3" id="FNanchor_AC_3"></a><a href="#Footnote_AC_3" class="fnanchor">[358-A]</a></p>
+
+<a id="img412" name="img412"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 433.</p>
+<img src="images/img412.jpg" width="200" height="204" alt="" title="">
+<p><i>Sph�ronites balticus</i>, Eichwald. (Of the family
+<i>Cystide�</i>.)</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> mouth.</li>
+<li><i>b.</i> point of attachment of stem.</li>
+</ul>
+<p class="martopm05">Lower Silurian, Shole's Hook and Bala.</p></div>
+
+<p><i>Thickness and unconformability of Silurian strata.</i>&mdash;According to the
+observation of our government surveyors in North Wales, the Lower Silurian
+strata of that region attain, in conjunction with the <span class="pagenum"><a id="page359"></a>[p.359]</span>
+contemporaneous volcanic rocks, the extraordinary thickness of 27,000 feet.
+One of the groups, called the trappean, consisting of slates and associated
+volcanic ash and greenstone, is 15,000 feet thick. Another series, called
+the Bala group, composed of slates and grits with an impure limestone rich
+in organic remains, is 9,000 feet thick.<a name="FNanchor_AC_4" id="FNanchor_AC_4"></a><a href="#Footnote_AC_4" class="fnanchor">[359-A]</a></p>
+
+<p>Throughout North Wales the Wenlock shales rest unconformably upon the
+Caradoc sandstones; and the Caradoc is in its turn unconformable to the
+Llandeilo beds, showing a considerable interval of time between the
+deposition of this group and that of the formations next above and below
+it. The Caradoc sandstone in the neighbourhood of the Longmynd Hills in
+Shropshire, appears to Professor E. Forbes to have been a deep-sea deposit
+formed around the margin of high and steep land. That land consisted partly
+of upraised Llandeilo flags and partly of rocks of still older date.<a name="FNanchor_AC_5" id="FNanchor_AC_5"></a><a href="#Footnote_AC_5" class="fnanchor">[359-B]</a></p>
+
+<p>Such evidence of the successive disturbance of strata during the Silurian
+period in Great Britain is what we might look for when we have discovered
+the signs of so grand a series of volcanic eruptions as the contemporaneous
+greenstones and tuffs of the Welsh mountains afford.</p>
+
+
+<h3><i>Silurian Strata of the United States.</i></h3>
+
+<p>The position of some of these strata, where they are bent and highly
+inclined in the Appalachian chain, or where they are nearly horizontal to
+the west of that chain, is shown in the section, <a href="#img358">fig. 379.</a> <a href="#page328">p. 327.</a> But
+these formations can be studied still more advantageously north of the same
+line of section, in the states of New York, Ohio, and other regions north
+and south of the great Canadian lakes. Here they are found, as in Russia,
+in horizontal position, and are more rich in well-preserved fossils than in
+almost any spot in Europe. The American strata may readily be divided into
+Upper and Lower Silurian, corresponding in age and fossils to the European
+divisions bearing the same names. The subordinate members of the New York
+series, founded on lithological and geographical considerations, are most
+useful in the United States, but even there are only of local importance.
+Some few of them, however, tally very exactly with English divisions, as
+for example the limestone, over which the Niagara is precipitated at the
+great cataract, which, with its underlying shales, agrees paleontologically
+with the Wenlock limestone and shale of Siluria. There is also a marked
+general correspondence in the succession of fossil forms, and even species,
+as we trace the organic remains downwards from the highest to the lowest
+beds.</p>
+
+<p>Mr. D. Sharpe, in his report on the mollusca collected by me from these
+strata in North America<a name="FNanchor_AC_6" id="FNanchor_AC_6"></a><a href="#Footnote_AC_6" class="fnanchor">[359-C]</a>, has concluded that the number of species
+common to the Silurian rocks, on both sides of the Atlantic, <span class="pagenum"><a id="page360"></a>[p.360]</span>is
+between 30 and 40 per cent.; a result which, although no doubt liable to
+future modification, when a larger comparison shall have been made, proves,
+nevertheless, that many of the species had a wide geographical range. It
+seems that comparatively few of the gasteropods and lamellibranchiate
+bivalves of North America can be identified specifically with European
+fossils, while no less than two-fifths of the brachiopoda are the same. In
+explanation of these facts, it is suggested, that most of the recent
+brachiopoda (especially the orthidiform ones) are inhabitants of deep
+water, and may have had a wider geographical range than shells living near
+shore. The predominance of bivalve mollusca of this peculiar class has
+caused the Silurian period to be sometimes styled the age of brachiopods.</p>
+
+<p><i>Whether the Silurian rocks are of deep-water origin.</i>&mdash;The grounds relied
+upon by Professor E. Forbes, for inferring that the larger part of the
+Silurian Fauna is indicative of a sea more than 70 fathoms deep, are the
+following: first, the small size of the greater number of conchifera;
+secondly, the paucity of pectinibranchiata (or spiral univalves); thirdly,
+the great number of floaters, such as <i>Bellerophon</i>, <i>Orthoceras</i>, &amp;c.;
+fourthly, the abundance of orthidiform brachiopoda; fifthly, the absence or
+great rarity of fossil fish.</p>
+
+<p>It is doubtless true that some living <i>Terebratul�</i>, on the coast of
+Australia, inhabit shallow water; but all the known species, allied in form
+to the extinct <i>Orthis</i>, inhabit the depths of the sea. It should also be
+remarked that Mr. Forbes, in advocating these views, was well aware of the
+existence of shores, bounding the Silurian sea in Shropshire, and of the
+occurrence of littoral species of this early date in the northern
+hemisphere. Such facts are not inconsistent with his theory; for he has
+shown, in another work, how, on the coast of Lycia, deep-sea strata are at
+present forming in the Mediterranean, in the vicinity of high and steep
+land.</p>
+
+<p>Had we discovered the ancient delta of some large Silurian river, we should
+doubtless have known more of the shallow, and brackish water, and
+fluviatile animals, and of the terrestrial flora of the period under
+consideration. To assume that there were no such deltas in the Silurian
+world, would be almost as gratuitous an hypothesis, as for the inhabitants
+of the coral islands of the Pacific to indulge in a similar generalization
+respecting the actual condition of the globe.<a name="FNanchor_AC_7" id="FNanchor_AC_7"></a><a href="#Footnote_AC_7" class="fnanchor">[360-A]</a></p>
+
+
+<h3><i>Mineral Character of Silurian Strata.</i></h3>
+
+<p>In lithological character, the Silurian strata vary greatly when we trace
+them through Europe and North America. The shales called mudstones are as
+little altered from some deposits, found in recent submarine banks, as are
+those of many tertiary formations. We meet with red sandstone and red marl,
+with gypsum and salt, of Upper Silurian date, in the Niagara district,
+which might be mistaken for trias. The whitish granular sandstone at the
+base of the <span class="pagenum"><a id="page361"></a>[p.361]</span>Silurian series in Sweden resembles the tertiary
+siliceous grit of Fontainebleau. The Calcareous Grit, oolite, and pisolite
+of Upper Silurian age in Gothland, are described by Sir R. Murchison as
+singularly like rocks of the oolitic period near Cheltenham; and, not to
+cite more examples, the Wenlock or Dudley limestone often resembles a
+modern coral-reef. If, therefore, uniformity of aspect has been thought
+characteristic of rocks of this age, the idea must have arisen from the
+similarity of feature acquired by strata subject to metamorphic action.
+This influence, seeing that the causes of change are always shifting the
+theatre of their principal development, must be multiplied throughout a
+wider geographical area by time, and become more general in any given
+system of rocks in proportion to their antiquity. We are now acquainted
+with dense groups of Eocene slates in the Alps, which were once mistaken by
+experienced geologists for Transition or Silurian formations. The error
+arose from attaching too great importance to mineral character as a test of
+age, for the tertiary slates in question having acquired that crystalline
+texture which is in reality most prevalent in the most ancient sedimentary
+formations.</p>
+
+
+<h3>CAMBRIAN GROUP.</h3>
+
+<p>Below the Silurian strata in North Wales, and in the region of the
+Cumberland lakes, there are some slaty rocks, devoid of organic remains, or
+in which a few obscure traces only of fossils have been detected (for which
+the names of Cambrian and Cumbrian have been proposed). Whether these will
+ever be entitled by the specific distinctness of their fossils to rank as
+independent groups, we have not yet sufficient data to determine.</p>
+
+<hr>
+
+
+<h3>TABULAR VIEW OF FOSSILIFEROUS STRATA,</h3>
+
+<p class="center"><i>Showing the Order of Superposition or Chronological Succession of the
+principal European Groups</i>.</p>
+
+
+<table  border="0" cellpadding="2" summary="TABULAR VIEW OF FOSSILIFEROUS STRATA.">
+<colgroup>
+    <col width="20%">
+    <col width="2%">
+    <col width="1%">
+    <col width="2%">
+    <col width="32%">
+    <col width="6%">
+    <col width="1%">
+    <col width="1%">
+    <col width="2%">
+    <col width="33%">
+</colgroup>
+
+<tr>
+  <td colspan="10" class="td-center ftsize105 hweight">I. POST-TERTIARY.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">A. POST-PLIOCENE.</td>
+</tr>
+
+<tr>
+  <td class="td-center smaller">Periods and Groups.</td>
+  <td colspan="3">&nbsp;</td>
+  <td class="td-center smaller">Examples.</td>
+  <td colspan="4">&nbsp;</td>
+  <td class="td-center smaller">Observations.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">1. Recent.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Peat mosses and shell-marl, with bones of land animals,
+    human remains, and works of art.</li>
+    <li>Newer parts of modern deltas and coral reefs.</li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">All the imbedded shells, freshwater and marine, of living
+  species, with occasional human remains and works of art.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">2. Post-Pliocene.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Clay, marl, and volcanic tuff of Ischia, <a href="#page113">p. 113.</a></li>
+    <li>Loess of the Rhine, <a href="#page117">p. 117.</a></li>
+    <li>Newer part of boulder formation, with erratics, <a href="#page124">p. 124.</a></li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">All the shells of living species. No human remains or works
+  of art. Bones of quadrupeds, partly of extinct species.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop2 ftsize105"><span class="pagenum"><a id="page362"></a>[p.362]</span>II. TERTIARY.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">B. PLIOCENE.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">3. Newer Pliocene or Pleistocene.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td >&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Boulder formation or drift of northern Europe and North
+    America, chaps. 11. &amp; 12.</li>
+    <li>Cavern deposits and osseous breccias, <a href="#page153">p. 153.</a></li>
+    <li>Fluvio-marine crag of Norwich, <a href="#page148">p. 148.</a></li>
+    <li>Limestone of Girgenti, in Sicily, <a href="#page152">p. 152.</a></li>
+  </ul></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Three-fourths of the fossil shells of existing species.</li>
+    <li>A majority of the mammalia extinct; but the genera corresponding
+    with those now surviving in the same great geographical and zoological
+    province, <a href="#page157">p. 157.</a></li>
+    <li>During part of this period icebergs frequent in the seas of
+    the northern hemisphere, and glaciers on hills of moderate height.</li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">4. Older Pliocene.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Red and Coralline crag of Suffolk, <a href="#page162">p. 162.</a></li>
+    <li>Subapennine beds, <a href="#page166">p. 166.</a></li>
+  </ul></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>A third or more of the species of mollusca extinct.</li>
+    <li>Nearly, if not all, the mammalia extinct.</li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">C. MIOCENE.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">5. Miocene.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Faluns of Touraine, <a href="#page168">p. 168.</a></li>
+    <li>Part of Bordeaux beds, <a href="#page171">p. 171.</a></li>
+    <li>Part of Molasse of Switzerland, <a href="#page171">p. 171.</a></li>
+  </ul></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>About two-thirds of the species of shells extinct.</li>
+    <li>The recent species of shells often not found in the adjoining
+    seas, but in warmer latitudes.</li>
+    <li>All the mammalia extinct.</li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">D. EOCENE.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">6. Upper Eocene.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Upper marine of Paris basin, Fontainebleau sandstone, <a href="#page175">p. 175.</a></li>
+    <li>Upper freshwater and millstone of same.</li>
+    <li>Kleyn Spauwen beds, <a href="#page176">p. 176.</a></li>
+    <li>Hermsdorf tile-clay, near Berlin.</li>
+    <li>Mayence tertiary strata, <a href="#page177">p. 177.</a></li>
+    <li>Freshwater beds of Limagne d'Auvergne, <a href="#page181">p. 181.</a></li>
+  </ul></td>
+  <td rowspan="5">&nbsp;</td>
+  <td rowspan="5" class="borleft">&nbsp;</td>
+  <td rowspan="5" colspan="2">&nbsp;</td>
+  <td rowspan="5" class="tdul"><ul>
+    <li>Fossil shells of the Eocene period, with very few exceptions, extinct.
+    Those which are identified with living species rarely belong
+    to neighbouring regions</li>
+    <li>All the mammalia of extinct species, and the greater part of them of
+    extinct genera.</li>
+    <li>Plants of Upper Eocene, indicating a south European
+    or Mediterranean climate; those of Lower Eocene, a tropical climate.</li>
+  </ul></td>
+</tr>
+
+<tr class="ftsizexs">
+  <td colspan="5">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">7. Middle Eocene.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Paris gypsum with Paleotherium, &amp;c., <a href="#page191">p. 191.</a></li>
+    <li>Freshwater and fluvio-marine beds of Headon Hill, Isle of Wight,
+    <a href="#page197">p. 197.</a></li>
+    <li>Barton beds, Hants, <a href="#page198">p. 198.</a></li>
+    <li>Calcaire Grossier, Paris, <a href="#page193">p. 193.</a></li>
+    <li>Bagshot and Bracklesham beds, Surrey and Sussex, <a href="#page198">p. 198.</a></li>
+  </ul></td>
+</tr>
+
+<tr class="ftsizexs">
+  <td colspan="5">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">8. Lower Eocene.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>London clay proper of Highgate Hill and Sheppey,&mdash;Bognor
+    beds, Sussex, <a href="#page200">p. 200.</a></li>
+    <li>Sables inf�rieurs, and lits coquilliers of Paris basin, <a href="#page196">p. 196.</a></li>
+    <li>Mottled and plastic clays and sands of the Hampshire and
+    London basins, <a href="#page203">p. 203.</a></li>
+    <li>Sables inf�rieurs and argiles plastiques of Paris basin, <a href="#page196">p. 196.</a></li>
+    <li>Nummulitic formation of the Alps, <a href="#page205">p. 205.</a></li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center ftsize105 martop2"><span class="pagenum"><a id="page363"></a>[p.363]</span>III. SECONDARY.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">E. CRETACEOUS.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center">� UPPER CRETACEOUS.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">9. Maestricht beds.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Yellowish white limestone of Maestricht, <a href="#page209">p. 209.</a></li>
+    <li>Coralline limestone of Faxoe, Denmark, <a href="#page210">p. 210.</a></li>
+  </ul></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Ammonite, Baculite, and Belemnite, associated with Cypr�a, Oliva, Mitra, Trochus,
+  &amp;c. Large marine saurians.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">10. Upper White Chalk.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">White chalk with flints of North and South Downs,&mdash;
+  Surrey and Sussex, <a href="#page211">p. 211.</a></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">Marine limestone formed in part of decomposed corals.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">11. Lower White Chalk.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Chalk without flints, and chalk marl, ibid.</td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="3">&nbsp;</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">12. Upper Greensand.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Loose sand, with bright green particles, ibid.</li>
+    <li>Firestone of Merstham, Kent, <a href="#page218">p. 218.</a></li>
+    <li>Marly stone, with layers of chert, south of Isle of Wight.</li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="3">&nbsp;</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">13. Gault.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Dark blue marl at base of chalk escarpment,&mdash;Kent and
+  Sussex, <a href="#page218">p. 218.</a></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Numerous extinct genera of conchiferous cephalopoda, Hamite,
+  Scaphite, Ammonite, &amp;c.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1">�� LOWER CRETACEOUS.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">14. Lower Greensand.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Sand with green matter,&mdash;Weald of Kent and Sussex, <a href="#page219">p. 219.</a></li>
+    <li>White, yellowish, and ferruginous sand, with concretions
+    of limestone and chert,&mdash;Atherfield, Isle of Wight.</li>
+    <li>Limestone called Kentish Rag</li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">Species of shells, &amp;c., nearly all distinct from those of
+  Upper Cretaceous; most of the genera the same.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center ftsize101 martop1">F. WEALDEN.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">15. Weald Clay.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Clay with occasional bands of limestone,&mdash;Weald of Kent,
+  Surrey, and Sussex, <a href="#page227">p. 227.</a></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Of freshwater origin. Shells of pulmoniferous mollusca, and of
+  Cypris. Land reptiles.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">16. Hastings Sand.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Sand with calciferous grit and clay,&mdash;Hastings, Sussex,
+  Cuckfield, Kent, <a href="#page229">p. 229.</a></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Freshwater with intercalated bed of brackish and salt water
+  origin. Shells of fluviatile and lacustrine genera. Reptiles
+  of the genera Pterodactyle, Iguanodon, Megalosaurus,
+  Plesiosaurus, Trionyx, and Emys.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">17. Purbeck Beds.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Limestones, calcareous slates and marls, <a href="#page231">p. 231.</a></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Chiefly freshwater, and divisible into three groups, each
+  containing distinct species of freshwater mollusca and
+  of entomostraca. Alternations of deposits formed in fresh,
+  brackish, and marine water, and of ancient soils formed on
+  land and retaining roots of trees. Plants chiefly cycads and
+  conifers, <a href="#page231">p. 231.</a></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center ftsize101 martop1"><span class="pagenum"><a id="page364"></a>[p.364]</span>G. OOLITE.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">18. Upper Oolite.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Portland  building stone, <a href="#page259">p. 259.</a></li>
+    <li><i>b.</i> Portland sand.</li>
+    <li><i>c.</i> Kimmeridge clay, Dorsetshire, <a href="#page260">p. 260.</a></li>
+  </ul></td>
+  <td rowspan="5">&nbsp;</td>
+  <td  rowspan="5"class="borleft">&nbsp;</td>
+  <td rowspan="5" colspan="2">&nbsp;</td>
+  <td rowspan="5" class="tdul"><ul>
+    <li>Ammonites and Belemnites numerous.</li>
+    <li>Large saurians, as Pterodactyles, Plesiosaurs, Ichthyosaurs.</li>
+    <li>No cetaceans yet known, but three species of terrestrial
+    mammalia, <a href="#page267">p. 267</a>, <a href="#page268">268.</a> Preponderance of ganoid
+    fish. The plants chiefly cycads, conifers, and ferns, with a few palms.</li>
+  </ul></td>
+</tr>
+
+<tr class="ftsizexs">
+  <td colspan="5">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">19. Middle Oolite.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Coral Rag, <a href="#page260">p. 260.</a> Calcareous freestones, oolitic,                     }
+    often full of corals. Oxfordshire.</li>
+    <li><i>b.</i> Oxford clay&mdash;Dark blue clay,&mdash;Oxfordshire and
+    midland counties, <a href="#page262">p. 262.</a></li>
+  </ul></td>
+</tr>
+
+<tr class="ftsizexs">
+  <td colspan="5">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">20. Lower Oolite.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Cornbrash and forest marble, Wiltshire, <a href="#page263">p. 263.</a></li>
+    <li><i>b.</i> Great oolite and Stonesfield slate,&mdash;Bath, Bradford,
+    Stonesfield near Woodstock, Oxfordshire, <a href="#page266">p. 266.</a></li>
+    <li><i>c.</i> Fuller's earth,&mdash;Clay containing fuller's earth near
+    Bath, <a href="#page272">p. 272.</a></li>
+    <li><i>d.</i> Inferior oolite, calcareous freestone, and yellow sands,&mdash;Cotteswold
+    Hills, Dundry Hill, near Bristol, <a href="#page272">p. 272.</a></li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center ftsize101 martop1">H. LIAS.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">21. Lias.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Argillaceous limestone, marl and clay,&mdash;Lyme Regis,
+  Dorsetshire, <a href="#page273">p. 273.</a></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Mollusca, reptiles, and fish of genera analogous to the oolitic.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">I. TRIAS.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">22. Upper Trias.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Keuper of Germany, or variegated marls&mdash;Red, grey,
+  green, blue, and white marls and sandstones with gypsum&mdash;W�rtemberg,
+  bone-bed of Axmouth, Dorset, <a href="#page289">p. 289.</a></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">Batrachian reptiles, <i>e.g.</i> Labyrinthodon, Rhyncosaurus,
+  &amp;c. Cephalopoda: Ceratites. No Belemnites. Plants:
+  Ferns, Cycads, Conifers.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">23. Middle Trias or Muschelkalk.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Compact greyish limestone with beds of dolomite and
+  gypsum,&mdash;North of Germany, <a href="#page287">p. 287.</a>
+  Wanting in England.</td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">With Equisetites and Calamite.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">24. Lower Trias.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Variegated or Bunter sandstone of Germans&mdash;Red
+    and white spotted sandstone with gypsum and rock-salt, <a href="#page288">p. 288.</a></li>
+    <li>Part of New Red sandstone of Cheshire with rock-salt, <a href="#page294">p. 294.</a></li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">Plants different for the most part from those of the Upper Trias.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop2 ftsize105">IV. PRIMARY.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">K. PERMIAN.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">25. Upper Permian.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Yellow magnesian limestone, Yorkshire and Durham, <a href="#page301">p. 301.</a></li>
+    <li>Zechstein of Thuringia, Upper part of Permian beds, Russia.</li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">Organic remains, both animal and vegetable, more allied
+  to primary than to secondary periods.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs"><span class="pagenum"><a id="page365"></a>[p.365]</span>&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">26. Lower Permian.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Marl slate of Durham and Thuringia.</li>
+    <li><i>b.</i> Lower New Red sandstone of north of England
+    and Rothliegendes of Germany.</li>
+    <li><i>a.</i> and <i>b.</i> Lower part of Permian beds, Russia, <a href="#page301">p. 301.</a></li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">Thecodont saurians. Heterocercal fish of genus Pal�oniscus,
+  &amp;c.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">L. CARBONIFEROUS.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">27. Coal measures.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Strata of sandstone and shale, with beds of coal,&mdash;S.
+    Wales and Northumberland, <a href="#page309">p. 309.</a></li>
+    <li><i>b.</i> Millstone grit,&mdash;S. Wales, Bristol coal-field,
+    Yorkshire, <a href="#page308">p. 308.</a></li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Great thickness of strata of fluvio-marine origin, with
+    beds of coal of vegetable origin, based on soils retaining
+    the roots of trees.</li>
+    <li>Oldest of known reptiles or Archegosaurus. Sauroid fish.</li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">28. Mountain limestone.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Carboniferous or mountain limestone, with marine shells and corals.</li>
+    <li>Mendip Hills, and many parts of Ireland, <a href="#page340">p. 340.</a></li>
+  </ul></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Brachiopoda of genus Productus.</li>
+    <li>Cephalopoda of genera Cyrtoceras, Goniatite, Orthoceras.</li>
+    <li>Crustaceans of the genus Phillipsia.</li>
+    <li>Crinoideans abundant.</li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">M. DEVONIAN.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">29. Upper Devonian.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Yellow sandstone of Dura Den, Fife.</li>
+    <li><i>b.</i> Red sandstone and marl with cornstone of Herefordshire
+    and Forfarshire.</li>
+    <li>Paving and roofing-stone, Forfarshire.</li>
+    <li>Upper part of Devonian beds of South Devon.</li>
+  </ul></td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Tribe of fish with hard coverings like chelonians, Pterichthys,
+    Pamphractus, &amp;c.; also of genera Cephalaspis, Holoptichius, &amp;c.</li>
+    <li>No reptiles yet known.</li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">30. Lower Devonian.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdnul">Grey sandstone with Ichthyolites,&mdash;Caithness, Cromarty,
+  and Orkney, Lower part of Devonian beds of South Devon,
+  and green chloritic slates of Cornwall, limestone of
+  Gerolstein, Eifel.</td>
+  <td>&nbsp;</td>
+  <td class="borleft">&nbsp;</td>
+  <td colspan="2">&nbsp;</td>
+  <td class="tdnul">Fish, partly of same genera, but of distinct species from
+  those in Upper Devonian; Glyptolepis, Dipterus, also
+  Osteolepis, Coccosteus, &amp;c.</td>
+</tr>
+
+<tr>
+  <td colspan="10" class="td-center martop1 ftsize101">N. SILURIAN.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid">31. Upper Silurian.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Tilestone of Brecon and Caermarthen.</li>
+    <li><i>b.</i> Limestone and shale, Ludlow, Shropshire.</li>
+    <li><i>c.</i> Wenlock or Dudley limestone.</li>
+  </ul></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Oldest of fossil fish yet discovered.</li>
+    <li>Trilobites and Graptolites abundant.</li>
+    <li>Brachiopoda very numerous.</li>
+    <li>Cephalopoda: Bellerophon, Orthoceras.</li>
+  </ul></td>
+</tr>
+
+<tr>
+  <td colspan="10" class="ftsizexs">&nbsp;</td>
+</tr>
+
+<tr>
+  <td rowspan="2" class="td-left tdtx-mid">32. Lower Silurian.</td>
+  <td>&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li><i>a.</i> Caradoc sandstone, Caer Caradoc, Shropshire.</li>
+    <li><i>b.</i> Llandeilo flags, calcareous flags and schists,&mdash;Builth,
+    Radnorshire, Llandeilo, Caermarthenshire.</li>
+  </ul></td>
+  <td colspan="2">&nbsp;</td>
+  <td class="borright">&nbsp;</td>
+  <td>&nbsp;</td>
+  <td class="tdul"><ul>
+    <li>Same genera of invertebrate animals as in Upper Silurian,
+    but species chiefly distinct. Trinucleus caractaci, Cystide�, <a href="#page358">p. 358.</a></li>
+    <li>No land plants yet known.</li>
+    <li>Footprints of tortoise, see note, <a href="#page360">p. 360.</a></li>
+  </ul></td>
+</tr>
+</table>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page366"></a>[p.366]</span>CHAPTER XXVIII.</h2>
+
+<h4>VOLCANIC ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Trap rocks &mdash; Name, whence derived &mdash; Their igneous origin at first
+doubted &mdash; Their general appearance and character &mdash; Volcanic cones
+and craters, how formed &mdash; Mineral composition and texture of volcanic
+rocks &mdash; Varieties of felspar &mdash; Hornblende and
+augite &mdash; Isomorphism &mdash; Rocks, how to be studied &mdash; Basalt,
+greenstone, trachyte, porphyry, scoria, amygdaloid, lava,
+tuff &mdash; Alphabetical list, and explanation of names and synonyms, of
+volcanic rocks &mdash; Table of the analyses of minerals most abundant in the
+volcanic and hypogene rocks.</p></div>
+
+
+<p><span class="smcap">The</span> aqueous or fossiliferous rocks having now been described, we have next
+to examine those which may be called volcanic, in the most extended sense
+of that term. Suppose <i>a a</i> in the annexed diagram, to represent the
+crystalline formations, such as the granitic and metamorphic; <i>b b</i> the
+fossiliferous strata; and <i>c c</i> the volcanic rocks. These last are
+sometimes found, as was explained in the first chapter, breaking through
+<i>a</i> and <i>b</i>, sometimes overlying both, and occasionally alternating with
+the strata <i>b b</i>. They also are seen, in some instances, to pass insensibly
+into the unstratified division of <i>a</i>, or the Plutonic rocks.</p>
+
+<a id="img413" name="img413"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 434.</p>
+<img src="images/img413.jpg" width="450" height="072" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li><i>a.</i> Hypogene formations, stratified and unstratified.</li>
+<li><i>b.</i> Aqueous formations.</li>
+<li><i>c.</i> Volcanic rocks.</li>
+</ul></div>
+
+<p>When geologists first began to examine attentively the structure of the
+northern and western parts of Europe, they were almost entirely ignorant of
+the phenomena of existing volcanos. They also found certain rocks, for the
+most part without stratification, and of a peculiar mineral composition, to
+which they gave different names, such as basalt, greenstone, porphyry, and
+amygdaloid. All these, which were recognized as belonging to one family,
+were called "trap" by Bergmann, from <i>trappa</i>, Swedish for a flight of
+steps&mdash;a name since adopted very generally into the nomenclature of the
+science; for it was observed that many rocks of this class occurred in
+great tabular masses of unequal extent, so as to form a succession of
+terraces or steps on the sides of hills. This configuration appears to be
+derived from two causes. First, the abrupt original terminations of sheets
+of melted matter, which have spread, whether on the land or bottom of the
+sea, over a level surface. For we know, in the case of lava flowing from a
+volcano, that a stream, when it has ceased to flow, and grown solid, very
+commonly ends in a steep slope, as at <i>a</i>, <a href="#img414">fig. 435.</a> But, secondly, the
+step-like appearance arises more frequently <span class="pagenum"><a id="page367"></a>[p.367]</span>from the mode in
+which horizontal masses of igneous rock, such as <i>b c</i>, intercalated
+between aqueous strata, have, subsequently to their origin, been exposed,
+at different heights, by denudation. Such an outline, it is true, is not
+peculiar to trap rocks; great beds of limestone, and other hard kinds of
+stone, often presenting similar terraces and precipices: but these are
+usually on a smaller scale, or less numerous, than the volcanic <i>steps</i>, or
+form less decided features in the landscape, as being less distinct in
+structure and composition from the associated rocks.</p>
+
+<a id="img414" name="img414"></a>
+<div class="floatleft smaller width200">
+<p>Fig. 435.</p>
+<img src="images/img414.jpg" width="200" height="128" alt="" title="">
+<p>Step-like appearance of trap.</p></div>
+
+<p>Although the characters of trap rocks are greatly diversified, the beginner
+will easily learn to distinguish them as a class from the aqueous
+formations. Sometimes they present themselves, as already stated, in
+tabular masses, which are not divided into strata: sometimes in shapeless
+lumps and irregular cones, forming chains of small hills. Often they are
+seen in dikes and wall-like masses, intersecting fossiliferous beds. The
+rock is occasionally found divided into columns, often decomposing into
+balls of various sizes, from a few inches to several feet in diameter. The
+decomposing surface very commonly assumes a coating of a rusty iron colour,
+from the oxidation of ferruginous matter, so abundant in the traps in which
+augite or hornblende occur; or, in the felspathic varieties of trap, it
+acquires a white opaque coating, from the bleaching of the mineral called
+felspar. On examining any of these volcanic rocks, where they have not
+suffered disintegration, we rarely fail to detect a crystalline arrangement
+in one or more of the component minerals. Sometimes the texture of the mass
+is cellular or porous, or we perceive that it has once been full of pores
+and cells, which have afterwards become filled with carbonate of lime, or
+other infiltrated mineral.</p>
+
+<p>Most of the volcanic rocks produce a fertile soil by their disintegration.
+It seems that their component ingredients, silica, alumina, lime, potash,
+iron, and the rest, are in proportions well fitted for vegetation. As they
+do not effervesce with acids, a deficiency of calcareous matter might at
+first be suspected; but although <i>the carbonate</i> of lime is rare, except in
+the nodules of amygdaloids, yet it will be seen that lime sometimes enters
+largely into the composition of augite and hornblende. (See Table, <a href="#page377">p. 377.</a>)</p>
+
+<p><i>Cones and Craters.</i>&mdash;In regions where the eruption of volcanic matter has
+taken place in the open air, and where the surface has never since been
+subjected to great aqueous denudation, cones and craters constitute the
+most striking peculiarity of this class of formations. Many hundreds of
+these cones are seen in central France, in the ancient provinces of
+Auvergne, Velay, and Vivarais, where they observe, for the most part, a
+linear arrangement, and form chains of hills. Although none of the
+eruptions have happened within the historical era, the streams of lava may
+still be traced distinctly descending from many of the craters, and
+following the lowest <span class="pagenum"><a id="page368"></a>[p.368]</span>levels of the existing valleys. The origin
+of the cone and crater-shaped hill is well understood, the growth of many
+having been watched during volcanic eruptions. A chasm or fissure first
+opens in the earth, from which great volumes of steam and other gases are
+evolved. The explosions are so violent as to hurl up into the air fragments
+of broken stone, parts of which are shivered into minute atoms. At the same
+time melted stone or <i>lava</i> usually ascends through the chimney or vent by
+which the gases make their escape. Although extremely heavy, this lava is
+forced up by the expansive power of entangled gaseous fluids, chiefly steam
+or aqueous vapour, exactly in the same manner as water is made to boil over
+the edge of a vessel when steam has been generated at the bottom by heat.
+Large quantities of the lava are also shot up into the air, where it
+separates into fragments, and acquires a spongy texture by the sudden
+enlargement of the included gases, and thus forms <i>scori�</i>, other portions
+being reduced to an impalpable powder or dust. The showering down of the
+various ejected materials round the orifice of eruption gives rise to a
+conical mound, in which the successive envelopes of sand and scori� form
+layers, dipping on all sides from a central axis. In the mean time a
+hollow, called a <i>crater</i>, has been kept open in the middle of the mound by
+the continued passage upwards of steam and other gaseous fluids. The lava
+sometimes flows over the edge of the crater, and thus thickens and
+strengthens the sides of the cone; but sometimes it breaks it down on one
+side, and often it flows out from a fissure at the base of the hill (see
+<a href="#img415">fig. 436.</a>).<a name="FNanchor_AD_1" id="FNanchor_AD_1"></a><a href="#Footnote_AD_1" class="fnanchor">[368-A]</a></p>
+
+<a id="img415" name="img415"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 436.</p>
+<img src="images/img415.jpg" width="400" height="130" alt="" title="">
+<p>Part of the chain of extinct volcanos called the Monts Dome,
+<span class="wosp05">Auvergne. (Scrope.)</span></p></div>
+
+<p><i>Composition and nomenclature.</i>&mdash;Before speaking of the connection between
+the products of modern volcanos and the rocks usually styled trappean, and
+before describing the external forms of both, and the manner and position
+in which they occur in the earth's crust, it will be desirable to treat of
+their mineral composition and names. The varieties most frequently spoken
+of are basalt, greenstone, syenitic greenstone, clinkstone, claystone, and
+trachyte; while those founded chiefly on peculiarities of texture, are
+porphyry, amygdaloid, lava, tuff, scori�, and pumice. It may be stated
+generally, that all these are mainly composed of two minerals, or families
+of simple minerals, <i>felspar</i> and <i>hornblende</i>; some almost entirely of
+hornblende, others of felspar.</p>
+
+<p>These two minerals may be regarded as two groups, rather than <span class="pagenum"><a id="page369"></a>[p.369]</span>
+species. Felspar, for example, may be, first, common felspar, that is to
+say, potash-felspar, in which the alkali is potash (see table, <a href="#page377">p. 377.</a>);
+or, secondly, albite, that is to say, soda-felspar, where the alkali is
+soda instead of potash; or, thirdly, Labrador-felspar (Labradorite), which
+differs not only in its iridescent hues, but also in its angle of fracture
+or cleavage, and its composition. We also read much of two other kinds,
+called glassy felspar and compact felspar, which, however, cannot rank as
+varieties of equal importance, for both the albitic and common felspar
+appear sometimes in transparent or <i>glassy</i> crystals; and as to compact
+felspar, it is a compound of a less definite nature, sometimes containing
+both soda and potash; and which might be called a felspathic paste, being
+the residuary matter after portions of the original matrix have
+crystallized.</p>
+
+<p>The other group, or <i>hornblende</i>, consists principally of two varieties;
+first, hornblende, and, secondly, augite, which were once regarded as very
+distinct, although now some eminent mineralogists are in doubt whether they
+are not one and the same mineral, differing only as one crystalline form of
+native sulphur differs from another.</p>
+
+<p>The history of the changes of opinion on this point is curious and
+instructive. Werner first distinguished augite from hornblende; and his
+proposal to separate them obtained afterwards the sanction of Ha�y, Mohs,
+and other celebrated mineralogists. It was agreed that the form of the
+crystals of the two species were different, and their structure, as shown
+by <i>cleavage</i>, that is to say, by breaking or cleaving the mineral with a
+chisel, or a blow of the hammer, in the direction in which it yields most
+readily. It was also found by analysis that augite usually contained more
+lime, less alumina, and no fluoric acid; which last, though not always
+found in hornblende, often enters into its composition in minute quantity.
+In addition to these characters, it was remarked as a geological fact, that
+augite and hornblende are very rarely associated together in the same rock;
+and that when this happened, as in some lavas of modern date, the
+hornblende occurs in the mass of the rock, where crystallization may have
+taken place more slowly, while the augite merely lines cavities where the
+crystals may have been produced rapidly. It was also remarked, that in the
+crystalline slags of furnaces, augitic forms were frequent, the hornblendic
+entirely absent; hence it was conjectured that hornblende might be the
+result of slow, and augite of rapid cooling. This view was confirmed by the
+fact, that Mitscherlich and Berthier were able to make augite artificially,
+but could never succeed in forming hornblende. Lastly, Gustavus Rose fused
+a mass of hornblende in a porcelain furnace, and found that it did not, on
+cooling, assume its previous shape, but invariably took that of augite. The
+same mineralogist observed certain crystals in rocks from Siberia which
+presented a hornblende <i>cleavage</i>, while they had the external form of
+augite.</p>
+
+<p>If, from these data, it is inferred that the same substance may assume the
+crystalline forms of hornblende or augite indifferently, according to the
+more or less rapid cooling of the melted mass, it is <span class="pagenum"><a id="page370"></a>[p.370]</span>nevertheless
+certain that the variety commonly called augite, and recognized by a
+peculiar crystalline form, has usually more lime in it, and less alumina,
+than that called hornblende, although the quantities of these elements do
+not seem to be always the same. Unquestionably the facts and experiments
+above mentioned show the very near affinity of hornblende and augite; but
+even the convertibility of one into the other by melting and
+recrystallizing, does not perhaps demonstrate their absolute identity. For
+there is often some portion of the materials in a crystal which are not in
+perfect chemical combination with the rest. Carbonate of lime, for example,
+sometimes carries with it a considerable quantity of silex into its own
+form of crystal, the silex being mechanically mixed as sand, and yet not
+preventing the carbonate of lime from assuming the form proper to it. This
+is an extreme case, but in many others some one or more of the ingredients
+in a crystal may be excluded from perfect chemical union; and, after
+fusion, when the mass recrystallizes, the same elements may combine
+perfectly or in new proportions, and thus a new mineral may be produced. Or
+some one of the gaseous elements of the atmosphere, the oxygen for example,
+may, when the melted matter reconsolidates, combine with some one of the
+component elements.</p>
+
+<p>The different quantity of the impurities or refuse above alluded to, which
+may occur in all but the most transparent and perfect crystals, may partly
+explain the discordant results at which experienced chemists have arrived
+in their analysis of the same mineral. For the reader will find that a
+mineral determined to be the same by its physical characters, crystalline
+form, and optical properties, has often been declared by skilful analyzers
+to be composed of distinct elements. (See the table at <a href="#page377">p. 377.</a>) This
+disagreement seemed at first subversive of the atomic theory, or the
+doctrine that there is a fixed and constant relation between the
+crystalline form and structure of a mineral, and its chemical composition.
+The apparent anomaly, however, which threatened to throw the whole science
+of mineralogy into confusion, was in a great degree reconciled to fixed
+principles by the discoveries of Professor Mitscherlich at Berlin, who
+ascertained that the composition of the minerals which had appeared so
+variable, was governed by a general law, to which he gave the name of
+<i>isomorphism</i> (from &#953;&#963;&#959;&#962;, <i>isos</i>, equal, and &#956;&#959;&#961;&#966;&#951;,
+<i>morphe</i>, form). According to this law, the ingredients of a given species
+of mineral are not absolutely fixed as to their kind and quality; but one
+ingredient may be replaced by an equivalent portion of some analogous
+ingredient. Thus, in augite, the lime may be in part replaced by portions
+of protoxide of iron, or of manganese, while the form of the crystal, and
+the angle of its cleavage planes, remain the same. These vicarious
+substitutions, however, of particular elements cannot exceed certain
+defined limits.</p>
+
+<p>Having been led into this digression on the recent progress of mineralogy,
+I may here observe that the geological student must endeavour as soon as
+possible to familiarize himself with the characters <span class="pagenum"><a id="page371"></a>[p.371]</span>of five at
+least of the most abundant simple minerals of which rocks are composed.
+These are, felspar, quartz, mica, hornblende, and carbonate of lime. This
+knowledge cannot be acquired from books, but requires personal inspection,
+and the aid of a teacher. It is well to accustom the eye to know the
+appearance of rocks under the lens. To learn to distinguish felspar from
+quartz is the most important step to be first aimed at. In general we may
+know the felspar because it can be scratched with the point of a knife,
+whereas the quartz, from its extreme hardness, receives no impression. But
+when these two minerals occur in a granular and uncrystallized state, the
+young geologist must not be discouraged if, after considerable practice, he
+often fails to distinguish them by the eye alone. If the felspar is in
+crystals, it is easily recognized by its cleavage: but when in grains the
+blow-pipe must be used, for the edges of the grains can be rounded in the
+flame, whereas those of <i>quartz</i> are infusible. If the geologist is
+desirous of distinguishing the three varieties of felspar above enumerated,
+or hornblende from augite, it will often be necessary to use the reflecting
+goniometer as a test of the angle of cleavage, and shape of the crystal.
+The use of this instrument will not be found difficult.</p>
+
+<p>The external characters and composition of the felspars are extremely
+different from those of augite or hornblende; so that the volcanic rocks in
+which either of these minerals decidedly predominates, are easily
+recognized. But there are mixtures of the two elements in every possible
+proportion, the mass being sometimes exclusively composed of felspar, at
+other times solely of augite, or, again, of both in equal quantities.
+Occasionally, the two extremes, and all the intermediate gradations, may be
+detected in one continuous mass. Nevertheless there are certain varieties
+or compounds which prevail so largely in nature, and preserve so much
+uniformity of aspect and composition, that it is useful in geology to
+regard them as distinct rocks, and to assign names to them, such as basalt,
+greenstone, trachyte, and others, already mentioned.</p>
+
+<p><i>Basalt.</i>&mdash;As an example of rocks in which augite greatly prevails, basalt
+may first be mentioned. Although we are more familiar with this term than
+with that of any other kind of trap, it is difficult to define it, the name
+having been used so vaguely. It has been very generally applied to any trap
+rock of a black, bluish, or leaden-grey colour, having a uniform and
+compact texture. Most strictly, it consists of an intimate mixture of
+augite, felspar, and iron, to which a mineral of an olive green colour,
+called olivine, is often superadded, in distinct grains or nodular masses.
+The iron is usually magnetic, and is often accompanied by another metal,
+titanium. Augite is the predominant mineral, the felspar being in much
+smaller proportions. There is no doubt that many of the fine-grained and
+dark-coloured trap rocks, called basalt, contained hornblende in the place
+of augite; but this will be deemed of small importance after the remarks
+above made. Other minerals are occasionally found in basalt; and this rock
+may pass insensibly into almost every variety of trap, especially <span class="pagenum"><a id="page372"></a>[p.372]</span>
+into greenstone, clinkstone, and wack�, which will be presently described.</p>
+
+<p><i>Greenstone</i>, or <i>Dolerite</i>, is usually defined as a granular rock, the
+constituent parts of which are hornblende and imperfectly crystallized
+felspar; the felspar being more abundant than in basalt; and the grains or
+crystals of the two minerals more distinct from each other. This name may
+also be extended to those rocks in which augite is substituted for
+hornblende (the dolorite of some authors), or to those in which albite
+replaces common felspar, forming the rock sometimes called Andesite.</p>
+
+<p><i>Syenitic greenstone.</i>&mdash;The highly crystalline compounds of the same two
+minerals, felspar and hornblende, having a granitiform texture, and with
+occasionally some quartz accompanying, may be called Syenitic greenstone, a
+rock which frequently passes into ordinary trap, and as frequently into
+granite.</p>
+
+<p><i>Trachyte.</i>&mdash;A porphyritic rock of a whitish or greyish colour, composed
+principally of glassy felspar, with crystals of the same, generally with
+some hornblende and some titaniferous iron. In composition it is extremely
+different from basalt, this being a felspathic, as the other is an augitic,
+rock. It has a peculiar rough feel, whence the name &#964;&#961;&#945;&#967;&#965;&#962;,
+<i>trachus</i>, rough. Some varieties of trachyte contain crystals of quartz.</p>
+
+<a id="img416" name="img416"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 437.</p>
+<img src="images/img416.jpg" width="250" height="245" alt="" title="">
+<p>Porphyry.<br>
+White crystals of felspar in a dark base of hornblende and felspar.</p></div>
+
+<p><i>Porphyry</i> is merely a certain form of rock, very characteristic of the
+volcanic formations. When distinct crystals of one or more minerals are
+scattered through an earthy or compact base, the rock is termed a porphyry
+(see <a href="#img416">fig. 437.</a>). Thus trachyte is porphyritic; for in it, as in many modern
+lavas, there are crystals of felspar; but in some porphyries the crystals
+are of augite, olivine, or other minerals. If the base be greenstone,
+basalt, or pitchstone, the rock may be denominated greenstone-porphyry,
+pitchstone-porphyry, and so forth.</p>
+
+<p><i>Amygdaloid.</i>&mdash;This is also another form of igneous rock, admitting of
+every variety of composition. It comprehends any rock in which round or
+almond-shaped nodules of some mineral, such as agate, calcedony, calcareous
+spar, or zeolite, are scattered through a base of wack�, basalt,
+greenstone, or other kind of trap. It derives its name from the Greek word
+<i>amygdala</i>, an almond. The origin of this structure cannot be doubted, for
+we may trace the process of its formation in modern lavas. Small pores or
+cells are caused by bubbles of steam and gas confined in the melted matter.
+After or during consolidation, these empty spaces are gradually filled up
+by matter separating from the mass, or infiltered by water permeating the
+rock. As these bubbles have been sometimes lengthened by the flow of the
+lava before it finally cooled, the contents of such cavities <span class="pagenum"><a id="page373"></a>[p.373]</span>have
+the form of almonds. In some of the amygdaloidal traps of Scotland, where
+the nodules have decomposed, the empty cells are seen to have a glazed or
+vitreous coating, and in this respect exactly resemble scoriaceous lavas,
+or the slags of furnaces.</p>
+
+<a id="img417" name="img417"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 438.</p>
+<img src="images/img417.jpg" width="250" height="264" alt="" title="">
+<p>Scoriaceous lava in part converted into an
+amygdaloid.</p>
+<p class="martopm05">Montagne de la Veille, Department of Puy de Dome, France.</p></div>
+
+<p>The annexed figure represents a fragment of stone taken from the upper part
+of a sheet of basaltic lava in Auvergne. One half is scoriaceous, the pores
+being perfectly empty; the other part is amygdaloidal, the pores or cells
+being mostly filled up with carbonate of lime, forming white kernels.</p>
+
+<p><i>Scori�</i> and <i>Pumice</i> may next be mentioned as porous rocks, produced by
+the action of gases on materials melted by volcanic heat. <i>Scori�</i> are
+usually of a reddish-brown and black colour, and are the cinders and slags
+of basaltic or augitic lavas. <i>Pumice</i> is a light, spongy, fibrous
+substance, produced by the action of gases on trachytic and other lavas;
+the relation, however, of its origin to the composition of lava is not yet
+well understood. Von Buch says that it never occurs where only
+Labrador-felspar is present.</p>
+
+<p><i>Lava.</i>&mdash;This term has a somewhat vague signification, having been applied
+to all melted matter observed to flow in streams from volcanic vents. When
+this matter consolidates in the open air, the upper part is usually
+scoriaceous, and the mass becomes more and more stony as we descend, or in
+proportion as it has consolidated more slowly and under greater pressure.
+At the bottom, however, of a stream of lava, a small portion of scoriaceous
+rock very frequently occurs, formed by the first thin sheet of liquid
+matter, which often precedes the main current, or in consequence of the
+contact with water in or upon the damp soil.</p>
+
+<p>The more compact lavas are often porphyritic, but even the scoriaceous part
+sometimes contains imperfect crystals, which have been derived from some
+older rocks, in which the crystals pre-existed, but were not melted, as
+being more infusible in their nature.</p>
+
+<p>Although melted matter rising in a crater, and even that which enters rents
+on the side of a crater, is called lava, yet this term belongs more
+properly to that which has flowed either in the open air or on the bed of a
+lake or sea. If the same fluid has not reached the surface, but has been
+merely injected into fissures below ground, it is called trap.</p>
+
+<p>There is every variety of composition in lavas; some are trachytic, as in
+the Peak of Teneriffe; a great number are basaltic, as in Vesuvius and
+Auvergne; others are andesitic, as those of Chili; some <span class="pagenum"><a id="page374"></a>[p.374]</span>of the
+most modern in Vesuvius consist of green augite, and many of those of Etna
+of augite and Labrador-felspar.<a name="FNanchor_AD_2" id="FNanchor_AD_2"></a><a href="#Footnote_AD_2" class="fnanchor">[374-A]</a></p>
+
+<p><i>Trap tuff, volcanic tuff.</i>&mdash;Small angular fragments of the scori� and
+pumice, above mentioned, and the dust of the same, produced by volcanic
+explosions, form the tuffs which abound in all regions of active volcanos,
+where showers of these materials, together with small pieces of other rocks
+ejected from the crater, fall down upon the land or into the sea. Here they
+often become mingled with shells, and are stratified. Such tuffs are
+sometimes bound together by a calcareous cement, and form a stone
+susceptible of a beautiful polish. But even when little or no lime is
+present, there is a great tendency in the materials of ordinary tuffs to
+cohere together.</p>
+
+<p>Besides the peculiarity of their composition, some tuffs, or <i>volcanic
+grits</i>, as they have been termed, differ from ordinary sandstones by the
+angularity of their grains. When the fragments are coarse, the rock is
+styled a volcanic <i>breccia</i>. <i>Tufaceous conglomerates</i> result from the
+intermixture of rolled fragments or pebbles of volcanic and other rocks
+with tuff.</p>
+
+<p>According to Mr. Scrope, the Italian geologists confine the term <i>tuff</i>, or
+tufa, to felspathose mixtures, and those composed principally of pumice,
+using the term <i>peperino</i> for the basaltic tuffs.<a name="FNanchor_AD_3" id="FNanchor_AD_3"></a><a href="#Footnote_AD_3" class="fnanchor">[374-B]</a> The peperinos thus
+distinguished are usually brown, and the tuffs grey or white.</p>
+
+<p>We meet occasionally with extremely compact beds of volcanic materials,
+interstratified with fossiliferous rocks. These may sometimes be tuffs,
+although their density or compactness is such as to cause them to resemble
+many of those kinds of trap which are found in ordinary dikes. The
+chocolate-coloured mud, which was poured for weeks out of the crater of
+Graham's Island, in the Mediterranean, in 1831, must, when unmixed with
+other materials, have constituted a stone heavier than granite. Each cubic
+inch of the impalpable powder which has fallen for days through the
+atmosphere, during some modern eruptions, has been found to weigh, without
+being compressed, as much as ordinary trap rocks, and to be often identical
+with these in mineral composition.</p>
+
+<p>The fusibility of the igneous rocks generally exceeds that of other rocks,
+for there is much alkaline matter and lime in their composition, which
+serves as a flux to the large quantity of silica, which would be otherwise
+so refractory an ingredient.</p>
+
+<p>It is remarkable that, notwithstanding the abundance of this silica,
+quartz, that is, crystalline silica, is usually wanting in the volcanic
+rocks, or is present only as an occasional mineral, like mica. The elements
+of mica, as of quartz, occur in lava and trap; but the circumstances under
+which these rocks are formed are evidently unfavourable to the development
+of mica and quartz, minerals so characteristic of the hypogene formations.</p>
+
+<p>It would be tedious to enumerate all the varieties of trap and lava
+<span class="pagenum"><a id="page375"></a>[p.375]</span>which have been regarded by different observers as sufficiently
+abundant to deserve distinct names, especially as each investigator is too
+apt to exaggerate the importance of local varieties which happen to prevail
+in districts best known to him. It will be useful, however, to subjoin
+here, in the form of a glossary, an alphabetical list of the names and
+synonyms most commonly in use, with brief explanations, to which I have
+added a table of the analysis of the simple minerals most abundant in the
+volcanic and hypogene rocks.</p>
+
+
+<h3><i>Explanation of the names, synonyms, and mineral composition of the more
+abundant volcanic rocks.</i></h3>
+
+<div class="blq3">
+<p class="indentm3"><span class="smcap">Amphibolite.</span> <i>See</i> <a href="#hornbr">Hornblende rock</a>, amphibole being Ha�y's name for
+hornblende.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Amygdaloid.</span> A particular form of volcanic rock; <i>see</i> <a href="#page372">p. 372.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Augite rock.</span> A kind of basalt or greenstone, composed wholly or principally
+of granular augite. (<i>Leonhard's Mineralreich</i>, 2d edition, p. 85.)</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Augitic-porphyry.</span> Crystals of Labrador-felspar and of augite, in a green or
+dark grey base. (<i>Rose</i>, <i>Ann. des Mines</i>, tom. 8. p. 22. 1835.)</p>
+
+<p class="indentm3"><span class="smcap">Basalt.</span> Chiefly augite&mdash;an intimate mixture of augite and felspar with
+magnetic iron, olivine, &amp;c. <i>See</i> <a href="#page371">p. 371.</a> The yellowish green mineral
+called olivine, can easily be distinguished from yellowish felspar by its
+infusibility, and having no cleavage. The edges turn brown in the flame of
+the blow-pipe.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Basanite.</span> Name given by Alex. Brongniart to a rock, having a base of
+basalt, with more or less distinct crystals of augite disseminated through
+it.</p>
+
+<p class="indentm3"><span class="smcap">Claystone</span> and <span class="smcap">Claystone-porphyry</span>. An earthy and compact stone, usually of a
+purplish colour, like an indurated clay; passes into hornstone; generally
+contains scattered crystals of felspar and sometimes of quartz.</p>
+
+<p class="indentm3 martopm1"><span class="smcap"><a id="clinkst" name="clinkst">Clinkstone</a>.</span> <i>Syn.</i> Phonolite, fissile Petrosilex; a greenish or greyish
+rock, having a tendency to divide into slabs and columns; hard, with clean
+fracture, ringing under the hammer; principally composed of compact
+felspar, and, according to Gmelin, of felspar and mesotype. (<i>Leonhard</i>,
+<i>Mineralreich</i>, p. 102.) A rock much resembling clinkstone, and called by
+some Petrosilex, contains a considerable percentage of quartz and felspar.
+As both trachyte and basalt pass into clinkstone, the rock so called must
+be very various in composition.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Compact Felspar</span>, which has also been called Petrosilex; the rock so called
+includes the hornstone of some mineralogists, is allied to clinkstone, but
+is harder, more compact, and translucent. It is a varying rock, of which
+the chemical composition is not well defined, and is perhaps the same as
+that of clay. (<i>MacCulloch's Classification of Rocks</i>, p. 481.) Dr.
+MacCulloch says, that it contains both potash and soda.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Cornean.</span> A variety of claystone allied to hornstone. A fine homogeneous
+paste, supposed to consist of an aggregate of felspar, quartz, and
+hornblende, with occasionally epidote, and perhaps chlorite; it passes into
+compact felspar and hornstone. (<i>De la Beche</i>, <i>Geol. Trans.</i> second
+series, vol. 2. p. 3.)</p>
+
+<p class="indentm3"><span class="smcap"><a id="dialrock" name="dialrock">Diallage rock</a>.</span> <i>Syn</i>. Euphotide, Gabbro, and some Ophiolites. Compounded of
+felspar and diallage, sometimes with the addition of serpentine, or mica,
+or quartz. (<i>MacCulloch. ibid</i>. p. 648.)</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Diorite.</span> A kind of <a href="#greenst">greenstone</a>, which see. Components, felspar and
+hornblende in grains. According to <i>Rose</i>, <i>Ann. des Mines</i>, tom. 8. p. 4.,
+<i>diorite</i> consists of albite and hornblende.</p>
+
+<p class="indentm3 martopm1"><span class="pagenum"><a id="page376"></a>[p.376]</span><span class="smcap">Dioritic-porphyry.</span> A porphyritic greenstone, composed of crystals of
+albite and hornblende, in a greenish or blackish base. (<i>Rose</i>, <i>ibid.</i> p.
+10.)</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Dolerite.</span> Formerly defined as a synonym of <a href="#greenst">greenstone</a>, which see. But,
+according to Rose (<i>ibid.</i> p. 32.), its composition is black augite and
+Labrador-felspar; according to Leonhard (<i>Mineralreich</i>, &amp;c. p. 77.),
+augite, Labrador-felspar, and magnetic iron.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Domite.</span> An earthy <i>trachyte</i>, found in the Puy de Dome, in Auvergne.</p>
+
+<p class="indentm3"><span class="smcap">Euphotide.</span> A mixture of grains of Labrador-felspar and diallage. (<i>Rose</i>,
+<i>ibid.</i> p. 19.) According to some, this rock is defined to be a mixture of
+augite or hornblende, and saussurite, a mineral allied to jade. (<i>Allan's
+Mineralogy</i>, p. 158.) <i>See</i> <a href="#dialrock">Diallage rock</a>.</p>
+
+<p class="indentm3"><span class="smcap">Felspar-porphyry.</span> <i>Syn.</i> Hornstone-porphyry; a base of felspar, with
+crystals of felspar, and crystals and grains of quartz. <i>See</i> also
+<a href="#hornst">Hornstone</a>.</p>
+
+<p class="indentm3"><span class="smcap">Gabbro</span>, <i>see</i> <a href="#dialrock">Diallage rock</a>.</p>
+
+<p class="indentm3 martopm1"><span class="smcap"><a id="greenst" name="greenst">Greenstone</a>.</span> <i>Syn.</i> Dolerite and diorite; components, hornblende and
+felspar, or augite and felspar in grains. See above, <a href="#page372">p. 372.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Greystone.</span> (Graustein of Werner.) Lead grey and greenish rock, composed of
+felspar and augite, the felspar being more than seventy-five per cent.
+(<i>Scrope</i>, <i>Journ. of Sci.</i> No. 42. p. 221.) Greystone lavas are
+intermediate in composition between basaltic and trachytic lavas.</p>
+
+<p class="indentm3"><span class="smcap"><a id="hornbr" name="hornbr">Hornblende Rock</a>.</span> A greenstone, composed principally of granular hornblende,
+or augite. (<i>Leonhard</i>, <i>Mineralreich</i>, &amp;c., p. 85.)</p>
+
+<p class="indentm3 martopm1"><span class="smcap"><a id="hornst" name="hornst">Hornstone</a>, Hornstone-porphyry.</span> A kind of felspar porphyry (<i>Leonhard</i>,
+<i>ibid.</i>), with a base of hornstone, a mineral approaching near to flint,
+differing from compact felspar in being infusible.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Hypersthene Rock</span>, a mixture of grains of Labrador-felspar and hypersthene
+(<i>Rose</i>, <i>Ann. des Mines</i>, tom. 8. p. 13.), having the structure of syenite
+or granite; abundant among the traps of Skye. Some geologists consider it a
+greenstone, in which hypersthene replaces hornblende.</p>
+
+<p class="indentm3"><span class="smcap">Laterite.</span> A red jaspery rock, composed of silicate of alumina and oxide of
+iron. Abundant in the Deccan, in India; and referred to the trap formation;
+from Later, a brick or tile.</p>
+
+<p class="indentm3"><span class="smcap">Melaphyre.</span> A variety of black porphyry, the base being black augite with
+crystals of felspar; from &#956;&#949;&#955;&#945;&#962;, <i>melas</i>, black.</p>
+
+<p class="indentm3"><span class="smcap"><a id="obsidian" name="obsidian">Obsidian</a>.</span> Vitreous lava like melted glass, nearly allied to pitchstone.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Ophiolite</span>, sometimes same as Diallage rocks (<i>Leonhard</i>, p. 77.); sometimes
+a kind of serpentine.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Ophite.</span> A green porphyritic rock composed chiefly of hornblende, with
+crystals of that mineral in a base of the same, mixed with some felspar. It
+passes into serpentine by a mixture of talc. (<i>Burat's d'Aubuisson</i>, tom.
+ii. p. 63.)</p>
+
+<p class="indentm3"><span class="smcap">Pearlstone.</span> A volcanic rock, having the lustre of mother of pearl; usually
+having a nodular structure; intimately related to obsidian, but less
+glassy.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Peperino.</span> A form of volcanic tuff, composed of basaltic scori�. <i>See</i> <a href="#page374">p.
+374.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Petrosilex.</span> <i>See</i> <a href="#clinkst">Clinkstone</a> and Compact Felspar.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Phonolite.</span> <i>Syn.</i> of <a href="#clinkst">Clinkstone</a>, which see.</p>
+
+<p class="indentm3 martopm1"><span class="smcap"><a id="pitst" name="pitst">Pitchstone</a>.</span> Vitreous lava, less glassy than obsidian; a blackish green rock
+resembling glass, having a resinous lustre and appearance of pitch;
+composition various, usually felspar and augite; passes into basalt; occurs
+in veins, and in Arran forms a dike thirty feet wide, cutting through
+sandstone; forms the outer walls of some basaltic dikes.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Porphyry.</span> Any rock in which detached crystals of felspar, or of one or more
+minerals, are diffused through a base. <i>See</i> <a href="#page372">p. 372.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Pozzolana.</span> A kind of tuff. <i>See</i> <a href="#page36">p. 36.</a></p>
+
+<p class="indentm3 martopm1"><span class="pagenum"><a id="page377"></a>[p.377]</span><span class="smcap">Pumice.</span> A light, spongy, fibrous form of trachyte. <i>See</i> <a href="#page373">p. 373.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Pyroxenic-porphyry</span>, same as augitic-porphyry, pyroxene being Ha�y's name
+for augite.</p>
+
+<p class="indentm3"><span class="smcap">Scori�.</span> <i>Syn.</i> volcanic cinders; reddish brown or black porous form of
+lava. <i>See</i> <a href="#page373">p. 373.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Serpentine.</span> A greenish rock, in which there is much magnesia; usually
+contains diallage, which is nearly allied to the simple mineral called
+serpentine. Occurs sometimes, though rarely, in dikes, altering the
+contiguous strata; is indifferently a member of the trappean or hypogene
+series.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Syenitic-greenstone</span>; composition, crystals or grains of felspar and
+hornblende. <i>See</i> <a href="#page372">p. 372.</a></p>
+
+<p class="indentm3"><span class="smcap">Tephrine</span>, synonymous with lava. Name proposed by Alex. Brongniart.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Toadstone.</span> A local name in Derbyshire for a kind of <a href="#wacke">wack�</a>, which see.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Trachyte.</span> Chiefly composed of glassy felspar, with crystals of glassy
+felspar. <i>See</i> <a href="#page372">p. 372.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Trap tuff.</span> <i>See</i> <a href="#page374">p. 374.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Trass.</span> A kind of tuff or mud poured out by lake craters during eruptions;
+common in the Eifel, in Germany.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Tufaceous Conglomerate.</span> <i>See</i> <a href="#page374">p. 374.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Tuff.</span> <i>Syn.</i> Trap-tuff, volcanic tuff. <i>See</i> <a href="#page374">p. 374.</a></p>
+
+<p class="indentm3"><span class="smcap">Vitreous lava.</span> <i>See</i> <a href="#pitst">Pitchstone</a> and <a href="#obsidian">Obsidian</a>.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Volcanic Tuff.</span> <i>See</i> <a href="#page374">p. 374.</a></p>
+
+<p class="indentm3"><span class="smcap"><a id="wacke" name="wacke">Wack�</a>.</span> A soft and earthy variety of trap, having an argillaceous aspect. It
+resembles indurated clay, and when scratched exhibits a shining streak.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Whinstone.</span> A Scotch provincial term for greenstone and other hard trap
+rocks.</p></div>
+
+
+<h3>ANALYSIS OF MINERALS MOST ABUNDANT IN THE VOLCANIC AND HYPOGENE ROCKS.</h3>
+
+
+<table  border="0" cellpadding="4" summary="ANALYSIS OF MINERALS MOST ABUNDANT IN THE VOLCANIC AND HYPOGENE ROCKS.">
+<colgroup>
+    <col width="17%">
+    <col width="9%">
+    <col width="9%">
+    <col width="9%">
+    <col width="8%">
+    <col width="9%">
+    <col width="8%">
+    <col width="9%">
+    <col width="11%">
+    <col width="11%">
+</colgroup>
+
+<tr class="smaller td-center">
+  <td class="bortop">&nbsp;</td>
+  <td class="bortop">Silica.</td>
+  <td class="bortop">Alumina.</td>
+  <td class="bortop">Magnesia.</td>
+  <td class="bortop">Lime.</td>
+  <td class="bortop">Potash.</td>
+  <td class="bortop">Soda.</td>
+  <td class="bortop">Iron Oxide.</td>
+  <td class="bortop">Manganese.</td>
+  <td class="bortop">Remainder.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Actinolite (Bergman)</td>
+  <td class="td-center bormid">64�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">22�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">3�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Albite (Rose)</td>
+  <td class="td-center bormid">68�84</td>
+  <td class="td-center bormid">20�53</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">a trace</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">9�12</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 4 analyses)</td>
+  <td class="td-center bormid">69�45</td>
+  <td class="td-center bormid">19�44</td>
+  <td class="td-center bormid">0�13</td>
+  <td class="td-center bormid">0�22</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">9�95</td>
+  <td class="td-center bormid">a trace</td>
+  <td class="td-center bormid">a trace</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Augite (Rose)</td>
+  <td class="td-center bormid">53�36</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">4�99</td>
+  <td class="td-center bormid">22�19</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">17�38</td>
+  <td class="td-center bormid">0�09</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 4 analyses)</td>
+  <td class="td-center bormid">53�57</td>
+  <td class="td-center bormid">1�</td>
+  <td class="td-center bormid">11�26</td>
+  <td class="td-center bormid">20�9</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">10�75</td>
+  <td class="td-center bormid">0�67</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Carbonate of Lime (Biot)</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">56�33</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">43�05 C.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Chiastolite (Landgrabe)</td>
+  <td class="td-center bormid">68�49</td>
+  <td class="td-center bormid">30�17</td>
+  <td class="td-center bormid">4�12</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">2�7</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">0�27 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Chlorite (Vauquelin)</td>
+  <td class="td-center bormid">26�</td>
+  <td class="td-center bormid">18�5</td>
+  <td class="td-center bormid">8�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">2�</td>
+  <td class="td-center bormid">43�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 3 analyses)</td>
+  <td class="td-center bormid">27�43</td>
+  <td class="td-center bormid">17�9</td>
+  <td class="td-center bormid">14�56</td>
+  <td class="td-center bormid">0�50</td>
+  <td class="td-center bormid">1�56</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">30�63</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">6�92 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Diallage (Klaproth)</td>
+  <td class="td-center bormid">60�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">27�5</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">10�5</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 3 analyses)</td>
+  <td class="td-center bormid">43�33</td>
+  <td class="td-center bormid">2�2</td>
+  <td class="td-center bormid">26�41</td>
+  <td class="td-center bormid">5�58</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">11�53</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">8�54 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Epidote (Vauquelin)</td>
+  <td class="td-center bormid">37�</td>
+  <td class="td-center bormid">21�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">15�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">24�</td>
+  <td class="td-center bormid">1�5</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Felspar, common (Vauq.)</td>
+  <td class="td-center bormid">62�83</td>
+  <td class="td-center bormid">17�02</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">3�</td>
+  <td class="td-center bormid">13�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">1�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (Rose)</td>
+  <td class="td-center bormid">66�75</td>
+  <td class="td-center bormid">17�5</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">1�25</td>
+  <td class="td-center bormid">12�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">0�75</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 7 analyses)</td>
+  <td class="td-center bormid">64�04</td>
+  <td class="td-center bormid">18�94</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">0�76</td>
+  <td class="td-center bormid">13�66</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">0�74</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Garnet (Klaproth)</td>
+  <td class="td-center bormid">35�75</td>
+  <td class="td-center bormid">27�25</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">36�</td>
+  <td class="td-center bormid">0�25</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (Phillips)</td>
+  <td class="td-center bormid">43�</td>
+  <td class="td-center bormid">16�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">20�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">16�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Hornblende (Klap.)</td>
+  <td class="td-center bormid">42�</td>
+  <td class="td-center bormid">12�</td>
+  <td class="td-center bormid">2�25</td>
+  <td class="td-center bormid">11�</td>
+  <td class="td-center bormid">a trace</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">30�</td>
+  <td class="td-center bormid">0�25</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (Bonsdorff.)</td>
+  <td class="td-center bormid">45�69</td>
+  <td class="td-center bormid">12�18</td>
+  <td class="td-center bormid">18�79</td>
+  <td class="td-center bormid">13�85</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">7�32</td>
+  <td class="td-center bormid">0�22</td>
+  <td class="td-center bormid">1�5 F.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Hypersthene (Klaproth)</td>
+  <td class="td-center bormid">54�25</td>
+  <td class="td-center bormid">2�25</td>
+  <td class="td-center bormid">14�</td>
+  <td class="td-center bormid">1�5</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">24�5</td>
+  <td class="td-center bormid">a trace</td>
+  <td class="td-center bormid">1� W.</td>
+  <td class="td-center bormid"></td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Labrador-felspar (Klap.)</td>
+  <td class="td-center bormid">55�75</td>
+  <td class="td-center bormid">26�5</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">11�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">4�</td>
+  <td class="td-center bormid">1�25</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">0�5 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Leucite (Klap.)</td>
+  <td class="td-center bormid">53�75</td>
+  <td class="td-center bormid">24�62</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">21�35</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Mesotype (Gehlen)</td>
+  <td class="td-center bormid">54�64</td>
+  <td class="td-center bormid">19�70</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">1�61</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">15�09</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">9�83 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Mica (Klaproth)</td>
+  <td class="td-center bormid">42�5</td>
+  <td class="td-center bormid">11�5</td>
+  <td class="td-center bormid">9�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">10�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">22�</td>
+  <td class="td-center bormid">2�</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (Vauquelin)</td>
+  <td class="td-center bormid">50�</td>
+  <td class="td-center bormid">35�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">1�33</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">7�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 3 analyses)</td>
+  <td class="td-center bormid">45�83</td>
+  <td class="td-center bormid">22�58</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">11�08</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">14�</td>
+  <td class="td-center bormid">1�45</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Olivine (Klaproth)</td>
+  <td class="td-center bormid">50�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">38�5</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">12�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Schorl or Tourmaline (Gmelin)</td>
+  <td class="td-center bormid">35�48</td>
+  <td class="td-center bormid">34�75</td>
+  <td class="td-center bormid">4�68</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">0�48</td>
+  <td class="td-center bormid">1�75</td>
+  <td class="td-center bormid">17�44</td>
+  <td class="td-center bormid">1�89</td>
+  <td class="td-center bormid">4�02 B.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 6 analyses)</td>
+  <td class="td-center bormid">36�03</td>
+  <td class="td-center bormid">35�82</td>
+  <td class="td-center bormid">4�44</td>
+  <td class="td-center bormid">0�28</td>
+  <td class="td-center bormid">0�71</td>
+  <td class="td-center bormid">1�96</td>
+  <td class="td-center bormid">13�71</td>
+  <td class="td-center bormid">1�62</td>
+  <td class="td-center bormid">&mdash;</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Serpentine (Hisinger)</td>
+  <td class="td-center bormid">43�07</td>
+  <td class="td-center bormid">0�25</td>
+  <td class="td-center bormid">40�37</td>
+  <td class="td-center bormid">0�5</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">1�17</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">12�45 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 5 analyses)</td>
+  <td class="td-center bormid">37�29</td>
+  <td class="td-center bormid">4�97</td>
+  <td class="td-center bormid">36�8</td>
+  <td class="td-center bormid">2�89</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">3�14</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">12�77 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">Steatite (Vauquelin)</td>
+  <td class="td-center bormid">64�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">22�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">3�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">5� W.</td>
+</tr>
+
+<tr>
+  <td class="td-left bormid">&mdash;&mdash; (mean of 3 anal. by Klap.)</td>
+  <td class="td-center bormid">48�3</td>
+  <td class="td-center bormid">6�18</td>
+  <td class="td-center bormid">26�65</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">2�</td>
+  <td class="td-center bormid">&mdash;</td>
+  <td class="td-center bormid">9�5 W.</td>
+</tr>
+
+<tr>
+  <td class="td-left borbot1">Talc. (Klaproth)</td>
+  <td class="td-center borbot1">61�75</td>
+  <td class="td-center borbot1">&mdash;</td>
+  <td class="td-center borbot1">30�5</td>
+  <td class="td-center borbot1">&mdash;</td>
+  <td class="td-center borbot1">2�75</td>
+  <td class="td-center borbot1">&mdash;</td>
+  <td class="td-center borbot1">2�5</td>
+  <td class="td-center borbot1">&mdash;</td>
+  <td class="td-center borbot1">&mdash;</td>
+</tr>
+</table>
+
+
+<p class="smaller">In the last column of the above Table, the letters B. C. F. W. represent
+Boracic acid, Carbonic acid, Fluoric acid, and Water.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page378"></a>[p.378]</span>CHAPTER XXIX.</h2>
+
+<h4>VOLCANIC ROCKS&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Trap dikes &mdash; sometimes project &mdash; sometimes leave fissures vacant by
+decomposition &mdash; Branches and veins of trap &mdash; Dikes more crystalline
+in the centre &mdash; Foreign fragments of rock imbedded &mdash; Strata altered
+at or near the contact &mdash; Obliteration of organic
+remains &mdash; Conversion of chalk into marble &mdash; and of coal into
+coke &mdash; Inequality in the modifying influence of dikes &mdash; Trap
+interposed between strata &mdash; Columnar and globular
+structure &mdash; Relation of trappean rocks to the products of active
+volcanos &mdash; Submarine lava and ejected matter corresponds generally to
+ancient trap &mdash; Structure and physical features of Palma and some other
+extinct volcanos.</p></div>
+
+
+<p><span class="smcap">Having</span> in the last chapter spoken of the composition and mineral characters
+of volcanic rocks, I shall next describe the manner and position in which
+they occur in the earth's crust, and their external forms. Now the leading
+varieties, such as basalt, greenstone, trachyte, porphyry, and the rest,
+are found sometimes in dikes penetrating stratified and unstratified
+formations, sometimes in shapeless masses protruding through or overlying
+them, or in horizontal sheets intercalated between strata.</p>
+
+<p><i>Volcanic dikes.</i>&mdash;Fissures have already been spoken of as occurring in all
+kinds of rocks, some a few feet, others many yards in width, and often
+filled up with earth or angular pieces of stone, or with sand and pebbles.
+Instead of such materials, suppose a quantity of melted stone to be driven
+or injected into an open rent, and there consolidated, we have then a
+tabular mass resembling a wall, and called a trap dike. It is not uncommon
+to find such dikes passing through strata of soft materials, such as tuff
+or shale, which, being more perishable than the trap, are often washed away
+by the sea, rivers, or rain, in which case the dike stands prominently out
+in the face of precipices, or on the level surface of a country. (See the
+annexed figure.<a name="FNanchor_AE_1" id="FNanchor_AE_1"></a><a href="#Footnote_AE_1" class="fnanchor">[378-A]</a>)</p>
+
+<a id="img418" name="img418"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 439.</p>
+<img src="images/img418.jpg" width="300" height="221" alt="" title="">
+<p>Dike in inland valley, near the Brazen Head, Madeira.</p></div>
+
+<p>In the islands of Arran, Skye, and other parts of Scotland, where
+sandstone, conglomerate, and other hard rocks are traversed by dikes of
+trap, the converse of the above phenomenon is seen. The dike having
+decomposed more rapidly than the containing rock, has once more left open
+the original <span class="pagenum"><a id="page379"></a>[p.379]</span>fissure, often for a distance of many yards inland
+from the sea-coast, as represented in the annexed view (<a href="#img419">fig. 440.</a>). In
+these instances, the greenstone of the dike is usually more tough and hard
+than the sandstone; but chemical action, and chiefly the oxidation of the
+iron, has given rise to the more rapid decay.</p>
+
+<a id="img419" name="img419"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 440.</p>
+<img src="images/img419.jpg" width="200" height="251" alt="" title="">
+<p>Fissures left vacant by decomposed trap. Strathaird,
+<span class="wosp05">Skye. (MacCulloch.)</span></p></div>
+
+<p>There is yet another case, by no means uncommon in Arran and other parts of
+Scotland, where the strata in contact with the dike, and for a certain
+distance from it, have been hardened, so as to resist the action of the
+weather more than the dike itself, or the surrounding rocks. When this
+happens, two parallel walls of indurated strata are seen protruding above
+the general level of the country, and following the course of the dike.</p>
+
+<a id="img420" name="img420"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 441.</p>
+<img src="images/img420.jpg" width="200" height="168" alt="" title="">
+<p>Trap veins in Airdnamurchan.</p></div>
+
+<p>As fissures sometimes send off branches, or divide into two or more
+fissures of equal size, so also we find trap dikes bifurcating and
+ramifying, and sometimes they are so tortuous as to be called veins, though
+this is more common in granite than in trap. The accompanying sketch (<a href="#img420">fig.
+441.</a>) by Dr. MacCulloch represents part of a sea-cliff in Argyleshire,
+where an overlying mass of trap, <i>b</i>, sends out some veins which terminate
+downwards. Another trap vein, <i>a a</i>, cuts through both the limestone, <i>c</i>,
+and the trap, <i>b</i>.</p>
+
+<p>In <a href="#img421">fig. 442.</a>, a ground plan is given of a ramifying dike of greenstone,
+which I observed cutting through sandstone on the beach near Kildonan
+Castle, in Arran. The larger branch varies from 5 to 7 feet in width, which
+will afford a scale of measurement for the whole.</p>
+
+<a id="img421" name="img421"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 442.</p>
+<img src="images/img421.jpg" width="350" height="137" alt="" title="">
+<p>Ground plan of greenstone dike traversing <span class="wosp05">sandstone. Arran.</span></p></div>
+
+<p>In the Hebrides and other countries, the same masses of trap which occupy
+the surface of the country far and wide, concealing the subjacent
+stratified rocks, are seen also in the sea cliffs, prolonged downwards in
+veins or dikes, which probably unite with other masses <span class="pagenum"><a id="page380"></a>[p.380]</span>of igneous
+rock at a greater depth. The largest of the dikes represented in the
+annexed diagram, and which are seen in part of the coast of Skye, is no
+less than 100 feet in width.</p>
+
+<a id="img422" name="img422"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 443.</p>
+<img src="images/img422.jpg" width="350" height="076" alt="" title="">
+<p>Trap dividing and covering sandstone near Suishnish in
+<span class="wosp05">Skye. (MacCulloch.)</span></p></div>
+
+<p>Every variety of trap-rock is sometimes found in these dikes, as basalt,
+greenstone, felspar-porphyry, and more rarely trachyte. The amygdaloidal
+traps also occur, and even tuff and breccia, for the materials of these
+last may be washed down into open fissures at the bottom of the sea, or
+during eruptions on the land may be showered into them from the air.</p>
+
+<p>Some dikes of trap may be followed for leagues uninterruptedly in nearly a
+straight direction, as in the north of England, showing that the fissures
+which they fill must have been of extraordinary length.</p>
+
+<p><i>Dikes more crystalline in the centre.</i>&mdash;In many cases trap at the edges or
+sides of a dike is less crystalline or more earthy than in the centre, in
+consequence of the melted matter having cooled more rapidly by coming in
+contact with the cold sides of the fissure; whereas, in the centre, the
+matter of the dike being kept long in a fluid or soft state, the crystals
+are slowly formed. In the ancient part of Vesuvius, called Somma, a thin
+band of half-vitreous lava is found at the edge of some dikes. At the
+junction of greenstone dikes with limestone, a <i>sahlband</i>, or selvage, of
+serpentine is occasionally observed.</p>
+
+<a id="img423" name="img423"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 444.</p>
+<p class="martopm05">Syenitic greenstone dike of N�sodden, Christiania.</p>
+<img src="images/img423.jpg" width="250" height="178" alt="" title="">
+<p><i>b.</i> imbedded fragment of crystalline schist surrounded by a band of
+greenstone.</p></div>
+
+<p>On the left shore of the fiord of Christiania, in Norway, I examined, in
+company with Professor Keilhau, a remarkable dike of syenitic greenstone,
+which is traced through Silurian strata, until at length, in the promontory
+of N�sodden, it enters mica-schist. <a href="#img423">Fig. 444.</a> represents a ground plan,
+where the dike appears 8 paces in width. In the middle it is highly
+crystalline and granitiform, of a purplish colour, and containing a few
+crystals of mica, and strongly contrasted with the whitish mica-schist,
+between which and the syenitic rock there is usually on each side a
+distinct black band, 18 inches wide, of dark greenstone. When first seen,
+these bands have the appearance of two accompanying dikes; yet they are, in
+fact, only the different form which the syenitic materials have assumed
+where near to or in contact with the <span class="pagenum"><a id="page381"></a>[p.381]</span>mica-schist. At one point,
+<i>a</i>, one of the sahlbands terminates for a space; but near this there is a
+large detached block, <i>b</i>, having a gneiss-like structure, consisting of
+hornblende and felspar, which is included in the midst of the dike. Round
+this a smaller encircling zone is seen, of dark basalt, or fine-grained
+greenstone, nearly corresponding to the larger ones which border the dike,
+but only 1 inch wide.</p>
+
+<p>It seems, therefore, evident that the fragment, <i>b</i>, has acted on the
+matter of the dike, probably by causing it to cool more rapidly, in the
+same manner as the walls of the fissure have acted on a larger scale. The
+facts, also, illustrate the facility with which a granitiform syenite may
+pass into ordinary rocks of the volcanic family.</p>
+
+<a id="img424" name="img424"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 445.</p>
+<img src="images/img424.jpg" width="250" height="165" alt="" title="">
+<p>Greenstone dike, with fragments of gneiss. Sorgenfri, Christiania.</p></div>
+
+<p>The fact above alluded to, of a foreign fragment, such as <i>b</i>, <a href="#img423">fig. 444.</a>,
+included in the midst of the trap, as if torn off from some subjacent rock
+or the walls of a fissure, is by no means uncommon. A fine example is seen
+in another dike of greenstone, 10 feet wide, in the northern suburbs of
+Christiania, in Norway, of which the annexed figure is a ground plan. The
+dike passes through shale, known by its fossils to belong to the Silurian
+series. In the black base of greenstone are angular and roundish pieces of
+gneiss, some white, others of a light flesh-colour, some without
+lamination, like granite, others with lamin�, which, by their various and
+often opposite directions, show that they have been scattered at random
+through the matrix. These imbedded pieces of gneiss measure from 1 to about
+8 inches in diameter.</p>
+
+<p><i>Rocks altered by volcanic dikes.</i>&mdash;After these remarks on the form and
+composition of dikes themselves, I shall describe the alterations which
+they sometimes produce in the rocks in contact with them. The changes are
+usually such as the intense heat of melted matter and the entangled gases
+might be expected to cause.</p>
+
+<p><i>Plas-Newydd.</i>&mdash;A striking example, near Plas-Newydd, in Anglesea, has been
+described by Professor Henslow.<a name="FNanchor_AE_2" id="FNanchor_AE_2"></a><a href="#Footnote_AE_2" class="fnanchor">[381-A]</a> The dike is 134 feet wide, and
+consists of a rock which is a compound of felspar and augite (dolerite of
+some authors). Strata of shale and argillaceous limestone, through which it
+cuts perpendicularly, are altered to a distance of 30, or even, in some
+places, to 35 feet from the edge of the dike. The shale, as it approaches
+the trap, becomes gradually more compact, and is most indurated where
+nearest the junction. Here it loses part of its schistose structure, but
+the separation into parallel layers is still discernible. In several places
+the shale is converted into hard porcellanous jasper. In the most hardened
+part of the mass the fossil shells, principally <i>Producti</i>, are nearly
+obliterated; <span class="pagenum"><a id="page382"></a>[p.382]</span>yet even here their impressions may frequently be
+traced. The argillaceous limestone undergoes analogous mutations, losing
+its earthy texture as it approaches the dike, and becoming granular and
+crystalline. But the most extraordinary phenomenon is the appearance in the
+shale of numerous crystals of analcime and garnet, which are distinctly
+confined to those portions of the rock affected by the dike.<a name="FNanchor_AE_3" id="FNanchor_AE_3"></a><a href="#Footnote_AE_3" class="fnanchor">[382-A]</a> Some
+garnets contain as much as 20 per cent. of lime, which they may have
+derived from the decomposition of the fossil shells or Producti. The same
+mineral has been observed, under very analogous circumstances, in High
+Teesdale, by Professor Sedgwick, where it also occurs in shale and
+limestone, altered by basalt.<a name="FNanchor_AE_4" id="FNanchor_AE_4"></a><a href="#Footnote_AE_4" class="fnanchor">[382-B]</a></p>
+
+<p><i>Antrim.</i>&mdash;In several parts of the county of Antrim, in the north of
+Ireland, chalk with flints is traversed by basaltic dikes. The chalk is
+there converted into granular marble near the basalt, the change sometimes
+extending 8 or 10 feet from the wall of the dike, being greatest near the
+point of contact, and thence gradually decreasing till it becomes
+evanescent. "The extreme effect," says Dr. Berger, "presents a dark brown
+crystalline limestone, the crystals running in flakes as large as those of
+coarse primitive (<i>metamorphic</i>) limestone; the next state is saccharine,
+then fine grained and arenaceous; a compact variety, having a porcellanous
+aspect and a bluish-grey colour, succeeds: this, towards the outer edge,
+becomes yellowish-white, and insensibly graduates into the unaltered chalk.
+The flints in the altered chalk usually assume a grey yellowish
+colour."<a name="FNanchor_AE_5" id="FNanchor_AE_5"></a><a href="#Footnote_AE_5" class="fnanchor">[382-C]</a> All traces of organic remains are effaced in that part of
+the limestone which is most crystalline.</p>
+
+<a id="img425" name="img425"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 446.</p>
+<img src="images/img425.jpg" width="400" height="127" alt="" title="">
+<p>Basaltic dikes in chalk in island of Rathlin, Antrim. Ground plan,
+as seen on the <span class="wosp05">beach. (Conybeare</span> and Buckland.
+<a name="FNanchor_AE_6" id="FNanchor_AE_6"></a><a href="#Footnote_AE_6" class="fnanchor">[382-D]</a>)</p></div>
+
+<p>The annexed drawing (<a href="#img425">fig. 446.</a>) represents three basaltic dikes traversing
+the chalk, all within the distance of 90 feet. The chalk contiguous to the
+two outer dikes is converted into a finely granular marble, <i>m m</i>, as are
+the whole of the masses between the outer dikes and the central one. The
+entire contrast in the composition and colour of the intrusive and invaded
+rocks, in these cases, renders the phenomena peculiarly clear
+and interesting.</p>
+
+<p>Another of the dikes of the north-east of Ireland has converted a mass of
+red sandstone into hornstone.<a name="FNanchor_AE_7" id="FNanchor_AE_7"></a><a href="#Footnote_AE_7" class="fnanchor">[382-E]</a> By another, the slate clay <span class="pagenum"><a id="page383"></a>[p.383]</span>
+of the coal measures has been indurated, and has assumed the character of
+flinty slate<a name="FNanchor_AE_8" id="FNanchor_AE_8"></a><a href="#Footnote_AE_8" class="fnanchor">[383-A]</a>; and in another place the slate clay of the lias has
+been changed into flinty slate, which still retains numerous impressions of
+ammonites.<a name="FNanchor_AE_9" id="FNanchor_AE_9"></a><a href="#Footnote_AE_9" class="fnanchor">[383-B]</a></p>
+
+<p>It might have been anticipated that beds of coal would, from their
+combustible nature, be effected in an extraordinary degree by the contact
+of melted rock. Accordingly, one of the greenstone dikes of Antrim, on
+passing through a bed of coal, reduces it to a cinder for the space of 9
+feet on each side.<a name="FNanchor_AE_10" id="FNanchor_AE_10"></a><a href="#Footnote_AE_10" class="fnanchor">[383-C]</a></p>
+
+<p>At Cockfield Fell, in the north of England, a similar change is observed.
+Specimens taken at the distance of about 30 yards from the trap are not
+distinguishable from ordinary pit coal; those nearer the dike are like
+cinders, and have all the character of coke; while those close to it are
+converted into a substance resembling soot.<a name="FNanchor_AE_11" id="FNanchor_AE_11"></a><a href="#Footnote_AE_11" class="fnanchor">[383-D]</a></p>
+
+<p>As examples might be multiplied without end, I shall merely select one or
+two others, and then conclude. The rock of Stirling Castle is a calcareous
+sandstone, fractured and forcibly displaced by a mass of greenstone which
+has evidently invaded the strata in a melted state. The sandstone has been
+indurated, and has assumed a texture approaching to hornstone near the
+junction. In Arthur's Seat and Salisbury Craig, near Edinburgh, a sandstone
+which comes in contact with greenstone is converted into a jaspideous
+rock.<a name="FNanchor_AE_12" id="FNanchor_AE_12"></a><a href="#Footnote_AE_12" class="fnanchor">[383-E]</a></p>
+
+<p>The secondary sandstones in Skye are converted into solid quartz in several
+places, where they come in contact with veins or masses of trap; and a bed
+of quartz, says Dr. MacCulloch, found near a mass of trap, among the coal
+strata of Fife, was in all probability a stratum of ordinary sandstone,
+having been subsequently indurated and turned into quartzite by the action
+of heat.<a name="FNanchor_AE_13" id="FNanchor_AE_13"></a><a href="#Footnote_AE_13" class="fnanchor">[383-F]</a></p>
+
+<p>But although strata in the neighbourhood of dikes are thus altered in a
+variety of cases, shale being turned into flinty slate or jasper, limestone
+into crystalline marble, sandstone into quartz, coal into coke, and the
+fossil remains of all such strata wholly and in part obliterated, it is by
+no means uncommon to meet with the same rocks, even in the same districts,
+absolutely unchanged in the proximity of volcanic dikes.</p>
+
+<p>This great inequality in the effects of the igneous rocks may often arise
+from an original difference in their temperature, and in that of the
+entangled gases, such as is ascertained to prevail in different lavas, or
+in the same lava near its source and at a distance from it. The power also
+of the invaded rocks to conduct heat may vary, according to their
+composition, structure, and the fractures which they may have experienced,
+and perhaps, also, according to the quantity of water (so capable of being
+heated) which they contain. It must happen in some cases that the component
+materials are mixed <span class="pagenum"><a id="page384"></a>[p.384]</span>in such proportions as prepare them readily
+to enter into chemical union, and form new minerals; while in other cases
+the mass may be more homogeneous, or the proportions less adapted for such
+union.</p>
+
+<p>We must also take into consideration, that one fissure may be simply filled
+with lava, which may begin to cool from the first; whereas in other cases
+the fissure may give passage to a current of melted matter, which may
+ascend for days or months, feeding streams which are overflowing the
+country above, or are ejected in the shape of scori� from some crater. If
+the walls of a rent, moreover, are heated by hot vapour before the lava
+rises, as we know may happen on the flanks of a volcano, the additional
+caloric supplied by the dike and its gases will act more powerfully.</p>
+
+<a id="img426" name="img426"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 447.</p>
+<img src="images/img426.jpg" width="400" height="170" alt="" title="">
+<p>Trap interposed between displaced beds of limestone and shale, at White
+Force, High Teesdale, <span class="wosp05">Durham. (Sedgwick.</span><a name="FNanchor_AE_14" id="FNanchor_AE_14"></a><a href="#Footnote_AE_14" class="fnanchor">[384-A]</a>)</p></div>
+
+<p><i>Intrusion of trap between strata.</i>&mdash;In proof of the mechanical force which
+the fluid trap has sometimes exerted on the rocks into which it has
+intruded itself, I may refer to the Whin-Sill, where a mass of basalt, from
+60 to 80 feet in height, represented by <i>a</i>, <a href="#img426">fig. 447.</a>, is in part wedged
+in between the rocks of limestone, <i>b</i>, and shale, <i>c</i>, which have been
+separated from the great mass of limestone and shale, <i>d</i>, with which they
+were united.</p>
+
+<p>The shale in this place is indurated; and the limestone, which at a
+distance from the trap is blue, and contains fossil corals, is here
+converted into granular marble without fossils.</p>
+
+<p>Masses of trap are not unfrequently met with intercalated between strata,
+and maintaining their parallelism to the planes of stratification
+throughout large areas. They must in some places have forced their way
+laterally between the divisions of the strata, a direction in which there
+would be the least resistance to an advancing fluid, if no vertical rents
+communicated with the surface, and a powerful hydrostatic pressure was
+caused by gases propelling the lava upwards.</p>
+
+<p><i>Columnar and globular structure.</i>&mdash;One of the characteristic forms of
+volcanic rocks, especially of basalt, is the columnar, where large masses
+are divided into regular prisms, sometimes easily separable, but in other
+cases adhering firmly together. The columns vary in the number of angles,
+from three to twelve; but they have most commonly from five to seven sides.
+They are often divided transversely, at nearly equal distances, like the
+joints in a vertebral column, as in the Giant's Causeway, in Ireland. They
+vary exceedingly <span class="pagenum"><a id="page385"></a>[p.385]</span>in respect to length and diameter. Dr.
+MacCulloch mentions some in Skye which are about 400 feet long; others, in
+Morven, not exceeding an inch. In regard to diameter, those of Ailsa
+measure 9 feet, and those of Morven an inch or less.<a name="FNanchor_AE_15" id="FNanchor_AE_15"></a><a href="#Footnote_AE_15" class="fnanchor">[385-A]</a> They are
+usually straight, but sometimes curved; and examples of both these occur in
+the island of Staffa. In a horizontal bed or sheet of trap the columns are
+vertical; in a vertical dike they are horizontal. Among other examples of
+the last-mentioned phenomenon is the mass of basalt, called the Chimney, in
+St. Helena (see <a href="#img427">fig. 448.</a>), a pile of hexagonal prisms, 64 feet high,
+evidently the remainder of a narrow dike, the walls of rock which the dike
+originally traversed having been removed down to the level of the sea. In
+<a href="#img428">fig. 449.</a> a small portion of this dike is represented on a less reduced
+scale.<a name="FNanchor_AE_16" id="FNanchor_AE_16"></a><a href="#Footnote_AE_16" class="fnanchor">[385-B]</a></p>
+
+<a id="img427" name="img427"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 448.</p>
+<img src="images/img427.jpg" width="250" height="311" alt="" title="">
+<p>Volcanic dike composed of horizontal <span class="wosp05">prisms. St.</span> Helena.</p></div>
+
+<a id="img428" name="img428"></a>
+<div class="floatright smaller width200">
+<p>Fig. 449.</p>
+<img src="images/img428.jpg" width="200" height="155" alt="" title="">
+<p>Small portion of the dyke in Fig. 448.</p></div>
+
+<a id="img429" name="img429"></a>
+<div class="nofloat smaller figcenter width450">
+<p>Fig. 450.</p>
+<img src="images/img429.jpg" width="450" height="219" alt="" title="">
+<p>Lava of La Coupe d'Ayzac, near Antraigue, in the province of Ard�che.</p></div>
+
+<p>It being assumed that columnar trap has consolidated from a fluid state,
+the prisms are said to be always at right angles to the <i>cooling surfaces</i>.
+If these surfaces, therefore, instead of being either perpendicular, or
+horizontal, are curved, the columns ought to be inclined at every angle to
+the horizon; and there is a beautiful exemplification of this phenomenon in
+one of the valleys of the Vivarais, a mountainous district in the South of
+France, where, in the midst of a region of gneiss, a geologist encounters
+unexpectedly several volcanic cones of loose sand and scori�. From the
+crater of one of <span class="pagenum"><a id="page386"></a>[p.386]</span>these cones called La Coupe d'Ayzac, a stream of
+lava descends and occupies the bottom of a narrow valley, except at those
+points where the river Volant, or the torrents which join it, have cut away
+portions of the solid lava. The accompanying sketch (<a href="#img429">fig. 450.</a>) represents
+the remnant of the lava at one of the points where a lateral torrent joins
+the main valley of the Volant. It is clear that the lava once filled the
+whole valley up to the dotted line <i>d a</i>; but the river has gradually swept
+away all below that line, while the tributary torrent has laid open a
+transverse section; by which we perceive, in the first place, that the lava
+is composed, as usual in this country, of three parts: the uppermost, at
+<i>a</i>, being scoriaceous; the second, <i>b</i>, presenting irregular prisms; and
+the third, <i>c</i>, with regular columns, which are vertical on the banks of
+the Volant, where they rest on a horizontal base of gneiss, but which are
+inclined at an angle of 45� at <i>g</i>, and then horizontal at <i>f</i>, their
+position having been every where determined, according to the law before
+mentioned, by the concave form of the original valley.</p>
+
+<a id="img430" name="img430"></a>
+<div class="figcenter smaller width200">
+<p>Fig 451.</p>
+<img src="images/img430.jpg" width="200" height="246" alt="" title="">
+<p>Columnar basalt in the Vicentin. (Fortis.)</p></div>
+
+<p>In the annexed figure (<a href="#img430">451.</a>) a view is given of some of the inclined and
+curved columns which present themselves on the sides of the valleys in the
+hilly region north of Vicenza, in Italy, and at the foot of the higher
+Alps.<a name="FNanchor_AE_17" id="FNanchor_AE_17"></a><a href="#Footnote_AE_17" class="fnanchor">[386-A]</a> Unlike those of the Vivarais, last mentioned, the basalt of
+this country was evidently submarine, and the present valleys have since
+been hollowed out by denudation.</p>
+
+<p>The columnar structure is by no means peculiar to the trap rocks in which
+hornblende or augite predominate; it is also observed in clinkstone,
+trachyte, and other felspathic rocks of the igneous class, although in
+these it is rarely exhibited in such regular polygonal forms.</p>
+
+<a id="img431" name="img431"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 452.</p>
+<img src="images/img431.jpg" width="350" height="264" alt="" title="">
+<p>Basaltic pillars of the K�segrotte, Bertrich-Baden, half way between
+Treves and Coblentz. Height of grotto, from 7 to 8 feet.</p></div>
+
+<p><span class="pagenum"><a id="page387"></a>[p.387]</span>It has been already stated that basaltic columns are often
+divided by cross joints. Sometimes each segment, instead of an angular,
+assumes a spheroidal form, so that a pillar is made up of a pile of balls,
+usually flattened, as in the Cheese-grotto at Bertrich-Baden, in the Eifel,
+near the Moselle (<a href="#img431">fig. 452.</a>). The basalt, there, is part of a small stream
+of lava, from 30 to 40 feet thick, which has proceeded from one of several
+volcanic craters, still extant, on the neighbouring heights. The position
+of the lava bordering the river in this valley might be represented by a
+section like that already given at <a href="#img429">fig. 450.</a> <a href="#page385">p. 385.</a>, if we merely supposed
+inclined strata of slate and the argillaceous sandstone called greywack� to
+be substituted for gneiss.</p>
+
+<p>In some masses of decomposing greenstone, basalt, and other trap rocks, the
+globular structure is so conspicuous that the rock has the appearance of a
+heap of large cannon balls.</p>
+
+<a id="img432" name="img432"></a>
+<div class="figcenter smaller width150">
+<p>Fig. 453.</p>
+<img src="images/img432.jpg" width="150" height="271" alt="" title="">
+<p>Globiform pitchstone. Chiaja di Luna, Isle of <span class="wosp05">Ponza. (Scrope.)</span></p></div>
+
+<p>A striking example of this structure occurs in a resinous trachyte or
+pitchstone-porphyry in one of the Ponza islands, which rise from the
+Mediterranean, off the coast of Terracina and Gaeta. The globes vary from a
+few inches to three feet in diameter, and are of an ellipsoidal form (see
+<a href="#img432">fig. 453.</a>). The whole rock is in a state of decomposition, "and when the
+balls," says Mr. Scrope, "have been exposed a short time to the weather,
+they scale off at a touch into numerous concentric coats, like those of a
+bulbous root, inclosing a compact nucleus. The lamin� of this nucleus have
+not been so much loosened by decomposition; but the application of a ruder
+blow will produce a still further exfoliation."<a name="FNanchor_AE_18" id="FNanchor_AE_18"></a><a href="#Footnote_AE_18" class="fnanchor">[387-A]</a></p>
+
+<p>A fissile texture is occasionally assumed by clinkstone and other trap
+rocks, so that they have been used for roofing houses. Sometimes the
+prismatic and slaty structure is found in the same mass. The causes which
+give rise to such arrangements are very obscure, but are supposed to be
+connected with changes of temperature during the cooling of the mass, as
+will be pointed out in the sequel. (See Chaps. <a href="#chaxxxv">XXXV.</a> and <a href="#chaxxxvi">XXXVI.</a>)</p>
+
+
+<h3><i>Relation of Trappean Rocks to the products of active Volcanos.</i></h3>
+
+<p>When we reflect on the changes above described in the strata near their
+contact with trap dikes, and consider how great is the analogy in
+composition and structure of the rocks called trappean and the lavas of
+active volcanos, it seems difficult at first to understand how so much
+doubt could have prevailed for half a century as to whether <span class="pagenum"><a id="page388"></a>[p.388]</span>trap
+was of igneous or aqueous origin. To a certain extent, however, there was a
+real distinction between the trappean formations and those to which the
+term volcanic was almost exclusively confined. The trappean rocks first
+studied in the north of Germany, and in Norway, France, Scotland, and other
+countries, were either such as had been formed entirely under deep water,
+or had been injected into fissures and intruded between strata, and which
+had never flowed out in the air, or over the bottom of a shallow sea. When
+these products, therefore, of submarine or subterranean igneous action were
+contrasted with loose cones of scori�, tuff, and lava, or with narrow
+streams of lava in great part scoriaceous and porous, such as were observed
+to have proceeded from Vesuvius and Etna, the resemblance seemed remote and
+equivocal. It was, in truth, like comparing the roots of a tree with its
+leaves and branches, which, although they belong to the same plant, differ
+in form, texture, colour, mode of growth, and position. The external cone,
+with its loose ashes and porous lava, may be likened to the light foliage
+and branches, and the rocks concealed far below, to the roots. But it is
+not enough to say of the volcano,</p>
+
+<div class="left20">
+<p class="poem"><span class="poem1">"quantum vertice in auras</span><br>
+�therias, tantum radice in Tartara tendit,"</p></div>
+
+<p>for its roots do literally reach downwards to Tartarus, or to the regions
+of subterranean fire; and what is concealed far below, is probably always
+more important in volume and extent than what is visible above ground.</p>
+
+<a id="img433" name="img433"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 454.</p>
+<img src="images/img433.jpg" width="200" height="145" alt="" title="">
+<p>Strata intersected by a trap dike, and covered with alluvium.</p></div>
+
+<p>We have already stated how frequently dense masses of strata have been
+removed by denudation from wide areas (see <a href="#chavi">Chap. VI.</a>); and this fact
+prepares us to expect a similar destruction of whatever may once have
+formed the uppermost part of ancient submarine or subaerial volcanos, more
+especially as those superficial parts are always of the lightest and most
+perishable materials. The abrupt manner in which dikes of trap usually
+terminate at the surface (see <a href="#img433">fig. 454.</a>), and the water-worn pebbles of
+trap in the alluvium which covers the dike, prove incontestably that
+whatever was uppermost in these formations has been swept away. It is easy,
+therefore, to conceive that what is gone in regions of trap may have
+corresponded to what is now visible in active volcanos.</p>
+
+<p>It will be seen in the following chapters, that in the earth's crust there
+are volcanic tuffs of all ages, containing marine shells, which bear
+witness to eruptions at many successive geological periods. These tuffs,
+and the associated trappean rocks, must not be compared to lava and scori�
+which had cooled in the open air. Their counterparts must be sought in the
+products of modern submarine volcanic eruptions. If it be objected that we
+have no opportunity of studying <span class="pagenum"><a id="page389"></a>[p.389]</span>these last, it may be answered,
+that subterranean movements have caused, almost everywhere in regions of
+active volcanos, great changes in the relative level of land and sea, in
+times comparatively modern, so as to expose to view the effects of volcanic
+operations at the bottom of the sea.</p>
+
+<p>Thus, for example, the recent examination of the igneous rocks of Sicily,
+especially those of the Val di Noto, has proved that all the more ordinary
+varieties of European trap have been there produced under the waters of the
+sea, at a modern period; that is to say, since the Mediterranean has been
+inhabited by a great proportion of the existing species of testacea.</p>
+
+<p>These igneous rocks of the Val di Noto, and the more ancient trappean rocks
+of Scotland and other countries, differ from subaerial volcanic formations
+in being more compact and heavy, and in forming sometimes extensive sheets
+of matter intercalated between marine strata, and sometimes stratified
+conglomerates, of which the rounded pebbles are all trap. They differ also
+in the absence of regular cones and craters, and in the want of conformity
+of the lava to the lowest levels of existing valleys.</p>
+
+<p>It is highly probable, however, that insular cones did exist in some parts
+of the Val di Noto: and that they were removed by the waves, in the same
+manner as the cone of Graham island, in the Mediterranean, was swept away
+in 1831, and that of Ny�e, off Iceland, in 1783.<a name="FNanchor_AE_19" id="FNanchor_AE_19"></a><a href="#Footnote_AE_19" class="fnanchor">[389-A]</a> All that would
+remain in such cases, after the bed of the sea has been upheaved and laid
+dry, would be dikes and shapeless masses of igneous rock, cutting through
+sheets of lava which may have spread over the level bottom of the sea, and
+strata of tuff, formed of materials first scattered far and wide by the
+winds and waves, and then deposited. Trap conglomerates also, to which the
+action of the waves must give rise during the denudation of such volcanic
+islands, will emerge from the deep whenever the bottom of the sea becomes
+land.</p>
+
+<p>The proportion of volcanic matter which is originally submarine must always
+be very great, as those volcanic vents which are not entirely beneath the
+sea, are almost all of them in islands, or, if on continents, near the
+shore. This may explain why extended sheets of trap so often occur, instead
+of narrow threads, like lava streams. For, a multitude of causes tend, near
+the land, to reduce the bottom of the sea to a nearly uniform level,&mdash;the
+sediment of rivers,&mdash;materials transported by the waves and currents of the
+sea from wasting cliffs,&mdash;showers of sand and scori� ejected by volcanos,
+and scattered by the wind and waves. When, therefore, lava is poured out on
+such a surface, it will spread far and wide in every direction in a liquid
+sheet, which may afterwards, when raised up, form the tabular capping of
+the land.</p>
+
+<p>As to the absence of porosity in the trappean formations, the appearances
+are in a great degree deceptive, for all amygdaloids are, as <span class="pagenum"><a id="page390"></a>[p.390]</span>
+already explained, porous rocks, into the cells of which mineral matter,
+such as silex, carbonate of lime, and other ingredients, have been
+subsequently introduced (see <a href="#page373">p. 373.</a>); sometimes, perhaps, by secretion
+during the cooling and consolidation of lavas.</p>
+
+<p>In the Little Cumbray, one of the Western Islands, near Arran, the
+amygdaloid sometimes contains elongated cavities filled with brown spar;
+and when the nodules have been washed out, the interior of the cavities is
+glazed with the vitreous varnish so characteristic of the pores of slaggy
+lavas. Even in some parts of this rock which are excluded from air and
+water, the cells are empty, and seem to have always remained in this state,
+and are therefore undistinguishable from some modern lavas.<a name="FNanchor_AE_20" id="FNanchor_AE_20"></a><a href="#Footnote_AE_20" class="fnanchor">[390-A]</a></p>
+
+<p>Dr. MacCulloch, after examining with great attention these and the other
+igneous rocks of Scotland, observes, "that it is a mere dispute about
+terms, to refuse to the ancient eruptions of trap the name of submarine
+volcanos; for they are such in every essential point, although they no
+longer eject fire and smoke."<a name="FNanchor_AE_21" id="FNanchor_AE_21"></a><a href="#Footnote_AE_21" class="fnanchor">[390-B]</a> The same author also considers it not
+improbable that some of the volcanic rocks of the same country may have
+been poured out in the open air.<a name="FNanchor_AE_22" id="FNanchor_AE_22"></a><a href="#Footnote_AE_22" class="fnanchor">[390-C]</a></p>
+
+<p>Although the principal component minerals of subaerial lavas are the same
+as those of intrusive trap, and both the columnar and globular structure
+are common to both, there are, nevertheless, some volcanic rocks which
+never occur as lava, such as greenstone, clinkstone, the more crystalline
+porphyries, and those traps in which quartz and mica appear as constituent
+parts. In short, the intrusive trap rocks, forming the intermediate step
+between lava and the plutonic rocks, depart in their characters from lava
+in proportion as they approximate to granite.</p>
+
+<p>These views respecting the relations of the volcanic and trap rocks will be
+better understood when the reader has studied, in the 33d chapter, what is
+said of the plutonic formations.</p>
+
+
+<h3>FORM, STRUCTURE, AND ORIGIN OF VOLCANIC MOUNTAINS.</h3>
+
+<p>The origin of volcanic cones with crater-shaped summits has been alluded to
+in the last chapter (<a href="#page368">p. 368.</a>), and more fully explained in the "Principles
+of Geology" (chaps. xxiv. to xxvii.), where Vesuvius, Etna, Santorin, and
+Barren Island were described. The more ancient portions of those mountains
+or islands, formed long before the times of history, exhibit the same
+external features and internal structure which belong to most of the
+extinct volcanos of still higher antiquity.</p>
+
+<p>The island of Palma, for example, one of the Canaries, offers an excellent
+illustration of what, in common with many others, I regard as the ruins of
+a large dome-shaped mass formed by a series of eruptions proceeding from a
+crater at the summit, this crater having <span class="pagenum"><a id="page391"></a>[p.391]</span>been since replaced by a
+larger cavity, the origin of which has afforded geologists an ample field
+for discussion and speculation.</p>
+
+<a id="img434" name="img434"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 455.</p>
+<img src="images/img434.jpg" width="500" height="188" alt="" title="">
+<p>View of the Isle of Palma, and of the entrance into the central
+cavity or <span class="wosp05">Caldera. From</span> Von Buch's "Canary Islands."</p></div>
+
+<a id="img435" name="img435"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 456.</p>
+<img src="images/img435.jpg" width="500" height="575" alt="" title="">
+<p>Map of the Caldera of Palma and the great ravine, called "Barranco de
+las <span class="wosp05">Angustias." From</span> Survey of Capt. Vidal, R.N., 1837.</p></div>
+
+<p>Von Buch, in his excellent account of the Canaries, has given us a graphic
+picture of this island, which consists chiefly of a single <span class="pagenum"><a id="page392"></a>[p.392]</span>
+mountain (<a href="#img434">fig. 455.</a>). This mountain has the general form of a great
+truncated cone, with a huge and deep cavity in the middle, about six miles
+in diameter, called by the inhabitants "the Caldera," or cauldron. The
+range of precipices surrounding the Caldera are no less than 4000 feet in
+their average height; at one point, where they are highest, they are 7730
+feet above the level of the sea. The external flanks of the cone incline
+gently in every direction towards the base of the island, and are in part
+cultivated; but the walls and bottom of the Caldera present on all sides
+rugged and uncultivated rocks, almost completely devoid of vegetation. So
+steep are these walls, that there is no part by which they can be
+descended, and the only entrance is by a great ravine, or Barranco, as it
+is called (see <i>b b'</i>, map, <a href="#img435">fig. 456.</a>), which extends from the sea to the
+interior of the great cavity, and by its jagged, broken, and precipitous
+sides, exhibits to the geologist a transverse section of the rocks of which
+the whole mountain is composed. By this means, we learn that the cone is
+made up of a great number of sloping beds, which dip outwards in every
+direction from the centre of the void space, or from the hollow axis of the
+cone. The beds consist chiefly of sheets of basalt, alternating with
+conglomerates; the materials of the latter being in part rounded, as if
+rolled by water in motion. The inclination of all the beds corresponds to
+that of the external slope of the island, being greatest towards the
+Caldera, and least steep when they are nearest the sea. There are a great
+number of tortuous veins, and many dikes of lava or trap, chiefly basaltic,
+and most of them vertical, which cut through the sloping beds laid open to
+view in the great gorge or Barranco. These dikes and veins are more and
+more abundant as we approach the Caldera, being therefore most numerous
+where the slope of the beds is greatest.</p>
+
+<p>Assuming the cone to be a pile of volcanic materials ejected by a long
+succession of eruptions (a point on which all geologists are agreed), we
+have to account for the Caldera and the great Barranco. I conceive that the
+cone itself may be explained, in accordance with what we know of the
+ordinary growth of volcanos<a name="FNanchor_AE_23" id="FNanchor_AE_23"></a><a href="#Footnote_AE_23" class="fnanchor">[392-A]</a>, by supposing most of the eruptions to
+have taken place from one or more central vents, at or near the summit of
+the cone, before it was truncated. From this culminating point, sheets of
+lava flowed down one after the other, and showers of ashes or ejected
+stones. The volcano may, in the earlier stages of its growth, have been in
+great part submerged, like Stromboli, in the sea; and, therefore, some of
+the fragments of rock cast out of its crater may not only have been rolled
+by torrents sweeping down the mountain's side, but have also been rounded
+by the waves of the sea, as we see happen on the beach near Catania, on
+which the modern lavas of Etna are broken up. The increased number of
+dykes, as we approach the axis of the cone, agrees well with the hypothesis
+of the eruptions having been most frequent towards the centre.</p>
+
+<p>There are three known causes or modes of operation, which may <span class="pagenum"><a id="page393"></a>[p.393]</span>
+have conduced towards the vast size of the Caldera. First, the summit of a
+conical mountain may have fallen in, as happened in the case of Capacurcu,
+one of the Andes, according to tradition, in the year 1462, and of many
+other volcanic mountains.<a name="FNanchor_AE_24" id="FNanchor_AE_24"></a><a href="#Footnote_AE_24" class="fnanchor">[393-A]</a> Sections seem wanting, to supply us with
+all the data required for judging fairly of the tenability of this
+hypothesis. It appears, however, from Captain Vidal's survey (see <a href="#img435">fig.
+456.</a>), that a hill of considerable height rises up from the bottom of the
+Caldera, the structure of which, if it be any where laid open, might
+doubtless throw much light on this subject. Secondly, an original crater
+may have been enlarged by a vast gaseous explosion, never followed by any
+subsequent eruption. A serious objection to this theory arises from our not
+finding that the exterior of the cone supports a mass of ruins, such as
+ought to cover it, had so enormous a volume of matter, partly made up of
+the solid contents of the dikes, been blown out into the air. In that case,
+an extensive bed of angular fragments of stone, and of fine dust, might be
+looked for, enveloping the entire exterior of the mountain up to the very
+rim of the Caldera, and ought nowhere to be intersected by a dike. The
+absence of such a formation has induced Von Buch to suppose that the
+missing portion of the cone was engulphed. It should, however, be
+remembered, that in existing volcanos, large craters, two or three miles in
+diameter, are sometimes formed by explosions, or by the discharge of great
+volumes of steam.</p>
+
+<p>There is yet another cause to which the extraordinary dimensions of the
+Caldera may, in part at least, be owing; namely, aqueous denudation. Von
+Buch has observed, that the existence of a single deep ravine, like the
+Great Barranco, is a phenomenon common to many extinct volcanos, as well as
+to some active ones. Now, it will be seen by Captain Vidal's map (<a href="#img435">fig. 456.</a>
+<a href="#page391">p. 391.</a>), that the sea-cliff at Point Juan Graje, 780 feet high, now
+constituting the coast at the entrance of the great ravine, is continuous
+with an inland cliff which bounds the same ravine on its north-western
+side. No one will dispute that the precipice, at the base of which the
+waves are now beating, owes its origin to the undermining power of the sea.
+It is natural, therefore, to attribute the extension of the same cliff to
+the former action of the waves, exerted at a time when the relative level
+of the island and the ocean were different from what they are now. But if
+the waves and tides had power to remove the rocks once filling a great
+gorge which is 7 miles long, and, in its upper part, 2000 feet deep, can we
+doubt that the same power may have cleared out much of the solid mass now
+missing in the Great Caldera?</p>
+
+<p>The theory advanced to account for the configuration of Palma, commonly
+called the "elevation crater theory," is this. All the alternating masses
+of basalt and conglomerate, intersected in the Barranco, or abruptly cut
+off in the escarpment or walls of the Caldera, were at first disposed in
+horizontal masses on the level floor of the ocean, and traversed, when in
+that position, by all the basaltic dikes which now cut through them. At
+length they were suddenly <span class="pagenum"><a id="page394"></a>[p.394]</span>uplifted by the explosive force of
+elastic vapours, which raised the mass bodily, so as to tilt the beds on
+all sides away from the centre of elevation, causing at the same time an
+opening at the culminating point. Besides many other objections which may
+be urged against this hypothesis, it leaves unexplained the unbroken
+continuity of the rim of the Caldera, which is uninterrupted in all places
+save one<a name="FNanchor_AE_25" id="FNanchor_AE_25"></a><a href="#Footnote_AE_25" class="fnanchor">[394-A]</a>, namely, that where the great gorge or Barranco occurs.</p>
+
+<p>As a more natural way of explaining the phenomenon, the following series of
+events may be imagined. The principal vent, from which a large part of the
+materials of the cone were poured or thrown out, was left empty after the
+last escape of vapour, when the volcano became extinct. We learn from Mr.
+Dana's valuable work on the geology of the United States' Exploring
+Expedition, published in 1849, that two of the principal volcanos of the
+Sandwich Islands, Mounts Loa and Kea in Owyhee, are huge flattened volcanic
+cones, 15,000 feet high (see <a href="#img436">fig. 457.</a>), each equalling two and a half
+Etnas in their dimensions.</p>
+
+<a id="img436" name="img436"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 457.</p>
+<img src="images/img436.jpg" width="500" height="043" alt="" title="">
+<p>Mount Loa, in the Sandwich <span class="wosp05">Islands. (Dana)</span></p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Crater at the summit.</li>
+<li><i>b.</i> The lateral crater of Kilauea.</li>
+</ul>
+<p class="martopm05">The dotted lines indicate a supposed column of solid rock caused
+by the lava consolidating after eruptions.</p></div>
+
+<p>From the summits of these lofty though featureless hills, and from vents
+not far below their summits, successive streams of lava, often 2 miles or
+more in width, and sometimes 26 miles long, have flowed. They have been
+poured out one after the other, some of them in recent times, in every
+direction from the apex of the cone, down slopes varying on an average from
+4 degrees to 8 degrees; but at some places considerably steeper.<a name="FNanchor_AE_26" id="FNanchor_AE_26"></a><a href="#Footnote_AE_26" class="fnanchor">[394-B]</a>
+Sometimes deep rents open on the sides of these cones, which are filled by
+streams of lava passing over them, the liquid matter in such cases probably
+uniting in the fissure with other lava melted in subterranean reservoirs
+below, and thus explaining the origin of one great class of lateral dikes,
+on Etna, Palma, and other cones.</p>
+
+<p>If the flattened domes, such as those here alluded to in the Sandwich
+Islands, instead of being inland, and above water, were situated in
+mid-ocean, like the Island of St. Paul, and for the most part submerged
+(see <a href="#img437">figs. 458</a>, <a href="#img438">459</a>, <a href="#img439">460.</a>), and if a gradual upheaval of such a dome should
+then take place, the denuding power of the sea could scarcely fail to play
+an important part in modifying the form of the volcanic mountain as it
+rose. The crater will almost invariably have one side much lower than all
+the others, namely, that side towards which the prevailing winds never
+blow, and to which, therefore, showers of dust and scori� are rarely
+carried during eruptions. There will also be one point on this windward or
+lowest side more depressed than all the rest, by which the sea may enter as
+often as the tide rises, or as often <span class="pagenum"><a id="page395"></a>[p.395]</span>as the wind blows from that
+quarter. For the same reason that the sea continues to keep open a single
+entrance into the lagoon of an atoll or annular coral reef, it will not
+allow this passage into the crater to be stopped up, but scour it out, at
+low tide, or as often as the wind changes. The channel, therefore, will
+always be deepened in proportion as the island rises above the level of the
+sea, at the rate perhaps of a few feet or yards in a century.</p>
+
+<a id="img437" name="img437"></a>
+<div class="figcenter class width500">
+<p>Fig. 458.</p>
+<img src="images/img437.jpg" width="500" height="524" alt="" title="">
+<p>Map of the Island of St. Paul, in the Indian Ocean, lat. 38� 44� S.,
+long. 77� 37� E., surveyed by Capt. Blackwood, R. N., 1842.</p></div>
+
+<a id="img438" name="img438"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 459.</p>
+<img src="images/img438.jpg" width="500" height="256" alt="" title="">
+<p>View of the Crater of the Island of St. Paul.</p></div>
+
+<p>The island of St. Paul may perhaps be motionless; but if, like many
+<span class="pagenum"><a id="page396"></a>[p.396]</span>other parts of the earth's crust, it should begin to undergo a
+gradual upheaval, or if, as has happened to the shores of the Bay of Bai�,
+its level should oscillate, with a tendency upon the whole to increased
+elevation, the same power which has cut away part of the cone, and caused
+the cliffs now seen on the north-east side of the island, would have power
+to undermine the walls of the crater, and enlarge its diameter, keeping
+open the channel, by which it enters into it. This ravine might be
+excavated to the depth of 180 feet (the present depth of the crater), and
+its length might be extended to many miles according to the size of the
+submerged part of the cone. The crater is only a mile in diameter, and the
+surrounding cliffs, where loftiest, only 800 feet high, so that the size of
+this cone and crater is insignificant when compared to those in the
+Sandwich Islands, and I have merely selected it because it affords an
+example of a class of insular volcanos, into the craters of which the sea
+now enters by a single passage. The crater of Vesuvius in 1822 was 2000
+feet deep; and if it were a half submerged cone, like St. Paul, the
+excavating power of the ocean might in conjunction with gaseous explosions
+and co-operating with a gradual upheaving force, give rise to a caldera on
+as grand a scale as that exhibited by Palma.</p>
+
+<a id="img439" name="img439"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 460.</p>
+<img src="images/img439.jpg" width="500" height="075" alt="" title="">
+<p>Side view of the Island of St. Paul (N.E. <span class="wosp05">side).
+Nine-pin</span> rocks two miles distant. (Captain Blackwood.)</p></div>
+
+<p>If, after the geographical changes above supposed, the volcanic fires long
+dormant should recover their energy, they might, as in the case of
+Teneriffe, Vesuvius, Santorin, and Barren Island, discharge from the old
+central vent, long sealed up at the bottom of the caldera, new floods of
+lava and clouds of elastic vapours. Should this happen, a new cone will be
+built up in the middle of the cavity or circular bay, formed, partly by
+explosion, partly perhaps by engulphment, and partly by aqueous denudation.
+In the island of Palma this last phase of volcanic activity has never
+occurred; but the subterranean heat is still in full operation beneath the
+Canary Islands, so that we know not what future changes it may be destined
+to undergo.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page397"></a>[p.397]</span>CHAPTER XXX.</h2>
+
+<h4>ON THE DIFFERENT AGES OF THE VOLCANIC ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Tests of relative age of volcanic rocks &mdash; Test by superposition and
+intrusion &mdash; Dike of Quarrington Hill, Durham &mdash; Test by alteration
+of rocks in contact &mdash; Test by organic remains &mdash; Test of age by
+mineral character &mdash; Test by included fragments &mdash; Volcanic rocks of
+the Post-Pliocene period &mdash; Basalt of Bay of Trezza in
+Sicily &mdash; Post-Pliocene volcanic rocks near Naples &mdash; Dikes of
+Somma &mdash; Igneous formations of the Newer Pliocene period &mdash; Val di
+Noto in Sicily.</p></div>
+
+
+<p><span class="smcap">Having</span> referred the sedimentary strata to a long succession of geological
+periods, we have next to consider how far the volcanic formations can be
+classed in a similar chronological order. The tests of relative age in this
+class of rocks are four:&mdash;1st, superposition and intrusion, with or without
+alteration of the rocks in contact; 2d, organic remains; 3d, mineral
+character; 4th, included fragments of older rocks.</p>
+
+<a id="img440" name="img440"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 461.</p>
+<img src="images/img440.jpg" width="400" height="075" alt="" title=""></div>
+
+<p><i>Tests by superposition, &amp;c.</i>&mdash;If a volcanic rock rests upon an aqueous
+deposit, the former must be the newest of the two, but the like rule does
+not hold good where the aqueous formation rests upon the volcanic, for
+melted matter, rising from below, may penetrate a sedimentary mass without
+reaching the surface, or may be forced in conformably between two strata,
+as <i>b</i> at <span class="smcap">D</span> in the annexed figure (<a href="#img440">fig. 461.</a>), after which it may cool down
+and consolidate. Superposition, therefore, is not of the same value as a
+test of age in the unstratified volcanic rocks as in fossiliferous
+formations. We can only rely implicitly on this test where the volcanic
+rocks are contemporaneous, not where they are intrusive. Now they are said
+to be contemporaneous if produced by volcanic action, which was going on
+simultaneously with the deposition of the strata with which they are
+associated. Thus in the section at <span class="smcap">D</span> (<a href="#img440">fig. 461.</a>), we may perhaps ascertain
+that the trap <i>b</i> flowed over the fossiliferous bed <i>c</i>, and that, after
+its consolidation, <i>a</i> was deposited upon it, <i>a</i> and <i>c</i> both belonging to
+the same geological period. But if the stratum <i>a</i> be altered by <i>b</i> at the
+point of contact, we must then conclude the trap to have been intrusive, or
+if, in pursuing <i>b</i> for some distance, we find at length that it cuts
+through the stratum <i>a</i>, and then overlies it as at <span class="smcap">E</span>.</p>
+
+<p>We may, however, be easily deceived in supposing a volcanic rock to be
+intrusive, when in reality it is contemporaneous; for a sheet of lava, as
+it spreads over the bottom of the sea, cannot rest everywhere <span class="pagenum"><a id="page398"></a>[p.398]</span>
+upon the same stratum, either because these have been denuded, or because,
+if newly thrown down, they thin out in certain places, thus allowing the
+lava to cross their edges. Besides, the heavy igneous fluid will often, as
+it moves along, cut a channel into beds of soft mud and sand. Suppose the
+submarine lava <span class="smcap">F</span> to have come in contact in this manner with the strata
+<i>a</i>, <i>b</i>, <i>c</i>, and that after its consolidation, the strata <i>d</i>, <i>e</i>, are
+thrown down in a nearly horizontal position, yet so as to lie unconformably
+to <span class="smcap">F</span>, the appearance of subsequent intrusion will here be complete,
+although the trap is in fact contemporaneous. We must not, therefore,
+hastily infer that the rock <span class="smcap">F</span> is intrusive, unless we find the
+strata <i>d</i> or <i>e</i> to have been altered at their junction, as if
+by heat.</p>
+
+<a id="img441" name="img441"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 462.</p>
+<img src="images/img441.jpg" width="200" height="114" alt="" title=""></div>
+
+<p>When trap dikes were described in the preceding chapter, they were shown to
+be more modern than all the strata which they traverse. A basaltic dike at
+Quarrington Hill, near Durham, passes through coal-measures, the strata of
+which are inclined, and shifted so that those on the north side of the dike
+are 24 feet above the level of the corresponding beds on the south side
+(see section, <a href="#img442">fig. 463.</a>). But the horizontal beds of overlying Red
+Sandstone and Magnesian Limestone are not cut through by the dike. Now here
+the coal-measures were not only deposited, but had subsequently been
+disturbed, fissured, and shifted, before the fluid trap now forming the
+dike was introduced into a rent. It is also clear that some of the upper
+edges of the coal strata, together with the upper part of the dike, had
+been subsequently removed by denudation before the lower New Red Sandstone
+and Magnesian Limestone were superimposed. Even in this case, however,
+although the date of the volcanic eruption is brought within narrow limits,
+it cannot be defined with precision; it may have happened either at the
+close of the Carboniferous period, or early in that of the Lower New Red
+Sandstone, or between these two periods, when the state of the animate
+creation and the physical geography of Europe were gradually changing from
+the type of the Carboniferous era to that of the Permian.</p>
+
+<a id="img442" name="img442"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 463.</p>
+<img src="images/img442.jpg" width="400" height="169" alt="" title="">
+<p>Section at Quarrington Hill, east of <span class="wosp05">Durham. (Sedgwick.)</span></p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Magnesian Limestone (Permian).</li>
+<li><i>b.</i> Lower New Red Sandstone.</li>
+<li><i>c.</i> Coal strata.</li>
+</ul></div>
+
+<p><span class="pagenum"><a id="page399"></a>[p.399]</span>The test of age by superposition is strictly applicable to all
+stratified volcanic tuffs, according to the rules already explained in the
+case of other sedimentary deposits. (See <a href="#page96">p. 96.</a>)</p>
+
+<p><i>Test of age by organic remains.</i>&mdash;We have seen how, in the vicinity of
+active volcanos, scori�, pumice, fine sand, and fragments of rock are
+thrown up into the air, and then showered down upon the land, or into
+neighbouring lakes or seas. In the tuffs so formed shells, corals, or any
+other durable organic bodies which may happen to be strewed over the bottom
+of a lake or sea will be imbedded, and thus continue as permanent memorials
+of the geological period when the volcanic eruption occurred. Tufaceous
+strata thus formed in the neighbourhood of Vesuvius, Etna, Stromboli, and
+other volcanos now active in islands or near the sea, may give information
+of the relative age of these tuffs at some remote future period when the
+fires of these mountains are extinguished. By such evidence we can
+distinctly establish the coincidence in age of volcanic rocks, and the
+different primary, secondary, and tertiary fossiliferous strata already
+considered.</p>
+
+<p>The tuffs now alluded to are not exclusively marine, but include, in some
+places, freshwater shells; in others, the bones of terrestrial quadrupeds.
+The diversity of organic remains in formations of this nature is perfectly
+intelligible, if we reflect on the wide dispersion of ejected matter during
+late eruptions, such as that of the volcano of Coseguina, in the province
+of Nicaragua, January 19. 1835. Hot cinders and fine scori� were then cast
+up to a vast height, and covered the ground as they fell to the depth of
+more than 10 feet, and for a distance of 8 leagues from the crater in a
+southerly direction. Birds, cattle, and wild animals were scorched to death
+in great numbers, and buried in these ashes. Some volcanic dust fell at
+Chiapa, upwards of 1200 miles to windward of the volcano, a striking proof
+of a counter current in the upper region of the atmosphere; and some on
+Jamaica, about 700 miles distant to the north-east. In the sea, also, at
+the distance of 1100 miles from the point of eruption, Captain Eden of the
+Conway sailed 40 miles through floating pumice, among which were some
+pieces of considerable size.<a name="FNanchor_AF_1" id="FNanchor_AF_1"></a><a href="#Footnote_AF_1" class="fnanchor">[399-A]</a></p>
+
+<p><i>Test of age by mineral composition.</i>&mdash;As sediment of homogeneous
+composition, when discharged from the mouth of a large river, is often
+deposited simultaneously over a wide space, so a particular kind of lava,
+flowing from a crater during one eruption, may spread over an extensive
+area; as in Iceland in 1783, when the melted matter, pouring from Skaptar
+Jokul, flowed in streams in opposite directions, and caused a continuous
+mass, the extreme points of which were 90 miles distant from each other.
+This enormous current of lava varied in thickness from 100 feet to 600
+feet, and in breadth from that of a narrow river gorge to 15 miles.<a name="FNanchor_AF_2" id="FNanchor_AF_2"></a><a href="#Footnote_AF_2" class="fnanchor">[399-B]</a>
+Now, if such a mass should afterwards be divided into separate fragments by
+<span class="pagenum"><a id="page400"></a>[p.400]</span>denudation, we might still perhaps identify the detached portions
+by their similarity in mineral composition. Nevertheless, this test will
+not always avail the geologist; for, although there is usually a prevailing
+character in lava emitted during the same eruption, and even in the
+successive currents flowing from the same volcano, still, in many cases,
+the different parts even of one lava-stream, or, as before stated, of one
+continuous mass of trap, vary so much in mineral composition and texture as
+to render these characters of minor importance when compared to their value
+in the chronology of the fossiliferous rocks.</p>
+
+<p>It will, however, be seen in the description which follows, of the European
+trap rocks of different ages, that they had often a peculiar lithological
+character, resembling the differences before remarked as existing between
+the modern lavas of Vesuvius, Etna, and Chili. (See <a href="#page378">p. 378.</a>)</p>
+
+<p>It has been remarked that in Auvergne, the Eifel, and other countries where
+trachyte and basalt are both present, the trachytic rocks are for the most
+part older than the basaltic. These rocks do, indeed, sometimes alternate
+partially, as in the volcano of Mont Dor, in Auvergne; but the great mass
+of trachyte occupies in general an inferior position, and is cut through
+and overflowed by basalt. It can by no means be inferred that trachyte
+predominated greatly at one period of the earth's history and basalt at
+another, for we know that trachytic lavas have been formed at many
+successive periods, and are still emitted from many active craters; but it
+seems that in each region, where a long series of eruptions have occurred,
+the more felspathic lavas have been first emitted, and the escape of the
+more augitic kinds has followed. The hypothesis suggested by Mr. Scrope
+may, perhaps, afford a solution of this problem. The minerals, he observes,
+which abound in basalt are of greater specific gravity than those composing
+the felspathic lavas; thus, for example, hornblende, augite, and olivine
+are each more than three times the weight of water; whereas common felspar,
+albite, and Labrador felspar, have each scarcely more than 2<span class="smaller"><sup>1</sup>/<sub>2</sub></span> times the
+specific gravity of water; and the difference is increased in consequence
+of there being much more iron in a metallic state in basalt and greenstone
+than in trachyte and other felspathic lavas and traps. If, therefore, a
+large quantity of rock be melted up in the bowels of the earth by volcanic
+heat, the denser ingredients of the boiling fluid may sink to the bottom,
+and the lighter remaining above would in that case be first propelled
+upwards to the surface by the expansive power of gases. Those materials,
+therefore, which occupied the lowest place in the subterranean reservoir
+will always be emitted last, and take the uppermost place on the exterior
+of the earth's crust.</p>
+
+<p><i>Test by included fragments.</i>&mdash;We may sometimes discover the relative age
+of two trap rocks, or of an aqueous deposit and the trap on which it rests,
+by finding fragments of one included in the other, in cases such as those
+before alluded to, where the evidence of superposition alone would be
+insufficient. It is also not uncommon to find <span class="pagenum"><a id="page401"></a>[p.401]</span>conglomerates
+almost exclusively composed of rolled pebbles of trap, associated with
+stratified rocks in the neighbourhood of masses of intrusive trap. If the
+pebbles agree generally in mineral character with the latter, we are then
+enabled to determine the age of the intrusive rock by knowing that of the
+fossiliferous strata associated with the conglomerate. The origin of such
+conglomerates is explained by observing the shingle beaches composed of
+trap pebbles in modern volcanic islands, or at the base of Etna.</p>
+
+<p><i>Post-Pliocene Period (including the Recent).</i>&mdash;I shall now select examples
+of contemporaneous volcanic rocks of successive geological periods, to show
+that igneous causes have been in activity in all past ages of the world,
+and that they have been ever shifting the places where they have broken out
+at the earth's surface.</p>
+
+<p>One portion of the lavas, tuffs, and trap dikes of Etna, Vesuvius, and the
+Island of Ischia, has been produced within the historical era; another, and
+a far more considerable part, originated at times immediately antecedent,
+when the waters of the Mediterranean were already inhabited by the existing
+species of testacea. The southern and eastern flanks of Etna are skirted by
+a fringe of alternating sedimentary and volcanic deposits, of submarine
+origin, as at Adern�, Trezza, and other places. Of sixty-five species of
+fossil shells which I procured in 1828 from this formation, near Trezza, it
+was impossible to distinguish any from species now living in the
+neighbouring sea.</p>
+
+<a id="img443" name="img443"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 464.</p>
+<img src="images/img443.jpg" width="400" height="256" alt="" title="">
+<p>View of the Isle of Cyclops in the Bay of Trezza.<a name="FNanchor_AF_3" id="FNanchor_AF_3"></a><a href="#Footnote_AF_3" class="fnanchor">[401-A]</a></p></div>
+
+<p>The Cyclopian Islands, called by the Sicilians Dei Faraglioni, in the sea
+cliffs of which these beds of clay, tuff, and associated lava are laid open
+to view, are situated in the Bay of Trezza, and may be regarded as the
+extremity of a promontory severed from the main land. Here numerous proofs
+are seen of submarine eruptions, by which the argillaceous and sandy strata
+were invaded and cut through, and tufaceous breccias formed. Inclosed in
+these breccias are many angular <span class="pagenum"><a id="page402"></a>[p.402]</span>and hardened fragments of
+laminated clay in different states of alteration by heat, and intermixed
+with volcanic sands.</p>
+
+<p>The loftiest of the Cyclopian islets, or rather rocks, is about 200 feet in
+height, the summit being formed of a mass of stratified clay, the lamin� of
+which are occasionally subdivided by thin arenaceous layers. These strata
+dip to the N.W., and rest on a mass of columnar lava (see <a href="#img443">fig. 464.</a>) in
+which the tops of the pillars are weathered, and so rounded as to be often
+hemispherical. In some places in the adjoining and largest islet of the
+group, which lies to the north-eastward of that represented in the drawing
+(<a href="#img443">fig. 464.</a>), the overlying clay has been greatly altered, and hardened by
+the igneous rock, and occasionally contorted in the most extraordinary
+manner; yet the lamination has not been obliterated, but, on the contrary,
+rendered much more conspicuous, by the indurating process.</p>
+
+<a id="img444" name="img444"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 465.</p>
+<img src="images/img444.jpg" width="300" height="476" alt="" title="">
+<p>Contortions of strata in the largest of the Cyclopian Islands.</p></div>
+
+<p>In the annexed woodcut (<a href="#img444">fig. 465.</a>) I have represented a portion of the
+altered rock, a few feet square, where the alternating thin lamin� of sand
+and clay have put on the appearance which we often observe in some of the
+most contorted of the metamorphic schists.</p>
+
+<p>A great fissure, running from east to west, nearly divides this larger
+island into two parts, and lays open its internal structure. In the section
+thus exhibited, a dike of lava is seen, first cutting through an older mass
+of lava, and then penetrating the superincumbent tertiary strata. In one
+place the lava ramifies and terminates in thin veins, from a few feet to a
+few inches in thickness. (See <a href="#img445">fig. 466.</a>)</p>
+
+<p>The arenaceous lamin� are much hardened at the point of contact, and the
+clays are converted into siliceous schist. In this island the altered rocks
+assume a honeycombed structure on their weathered surface, singularly
+contrasted with the smooth and even outline which the same beds present in
+their usual soft and yielding state.</p>
+
+<p>The pores of the lava are sometimes coated, or entirely filled, with
+carbonate of lime, and with a zeolite resembling analcime, which has been
+called cyclopite. The latter mineral has also been found in small fissures
+traversing the altered marl, showing that the same cause <span class="pagenum"><a id="page403"></a>[p.403]</span>which
+introduced the minerals into the cavities of the lava, whether we suppose
+sublimation or aqueous infiltration, conveyed it also into the open rents
+of the contiguous sedimentary strata.</p>
+
+<a id="img445" name="img445"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 466.</p>
+<img src="images/img445.jpg" width="350" height="329" alt="" title="">
+<p>Post-Pliocene strata invaded by lava, Isle of Cyclops
+(horizontal section).</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Lava.</li>
+<li><i>b.</i> Laminated clay and sand.</li>
+<li><i>c.</i> The same altered.</li>
+</ul></div>
+
+<p><i>Post-Pliocene formations near Naples.</i>&mdash;I have traced in the "Principles
+of Geology" the history of the changes which the volcanic region of
+Campania is known to have undergone during the last 2000 years. The
+aggregate effect of igneous operations during that period is far from
+insignificant, comprising as it does the formation of the modern cone of
+Vesuvius since the year 79, and the production of several minor cones in
+Ischia, together with that of Monte Nuovo in the year 1538. Lava-currents
+have also flowed upon the land and along the bottom of the sea&mdash;volcanic
+sand, pumice, and scori� have been showered down so abundantly, that whole
+cities were buried&mdash;tracts of the sea have been filled up or converted into
+shoals&mdash;and tufaceous sediment has been transported by rivers and
+land-floods to the sea. There are also proofs, during the same recent
+period, of a permanent alteration of the relative levels of the land and
+sea in several places, and of the same tract having, near Puzzuoli, been
+alternately upheaved and depressed to the amount of more than 20 feet. In
+connection with these convulsions, there are found, on the shores of the
+Bay of Bai�, recent tufaceous strata, filled with articles fabricated by
+the hands of man, and mingled with marine shells.</p>
+
+<p>It was also stated in this work (<a href="#page113">p. 113.</a>), that when we examine this same
+region, it is found to consist largely of tufaceous strata, of a date
+anterior to human history or tradition, which are of such thickness as to
+constitute hills from 500 to more than 2000 feet in height. These
+post-pliocene strata, containing recent marine shells, alternate with
+distinct currents and sheets of lava which were of contemporaneous origin;
+and we find that in Vesuvius itself, the <span class="pagenum"><a id="page404"></a>[p.404]</span>ancient cone called
+Somma is of far greater volume than the modern cone, and is intersected by
+a far greater number of dikes. In contrasting this ancient part of the
+mountain with that of modern date, one principal point of difference is
+observed; namely, the greater frequency in the older cone of fragments of
+altered sedimentary rocks ejected during eruptions. We may easily conceive
+that the first explosions would act with the greatest violence, rending and
+shattering whatever solid masses obstructed the escape of lava and the
+accompanying gases, so that great heaps of ejected pieces of rock would
+naturally occur in the tufaceous breccias formed by the earliest eruptions.
+But when a passage had once been opened, and an habitual vent established,
+the materials thrown out would consist of liquid lava, which would take the
+form of sand and scori�, or of angular fragments of such solid lavas as may
+have choked up the vent.</p>
+
+<p>Among the fragments which abound in the tufaceous breccias of Somma, none
+are more common than a saccharoid dolomite, supposed to have been derived
+from an ordinary limestone altered by heat and volcanic vapours.</p>
+
+<p>Carbonate of lime enters into the composition of so many of the simple
+minerals found in Somma, that M. Mitscherlich, with much probability,
+ascribes their great variety to the action of the volcanic heat on
+subjacent masses of limestone.</p>
+
+<p><i>Dikes of Somma.</i>&mdash;The dikes seen in the great escarpment which Somma
+presents towards the modern cone of Vesuvius are very numerous. They are
+for the most part vertical, and traverse at right angles the beds of lava,
+scori�, volcanic breccia, and sand, of which the ancient cone is composed.
+They project in relief several inches, or sometimes feet, from the face of
+the cliff, being extremely compact, and less destructible than the
+intersected tuffs and porous lavas. In vertical extent they vary from a few
+yards to 500 feet, and in breadth from 1 to 12 feet. Many of them cut all
+the inclined beds in the escarpment of Somma from top to bottom, others
+stop short before they ascend above half way, and a few terminate at both
+ends, either in a point or abruptly. In mineral composition they scarcely
+differ from the lavas of Somma, the rock consisting of a base of leucite
+and augite, through which large crystals of augite and some of leucite are
+scattered.<a name="FNanchor_AF_4" id="FNanchor_AF_4"></a><a href="#Footnote_AF_4" class="fnanchor">[404-A]</a> Examples are not rare of one dike cutting through
+another, and in one instance a shift or fault is seen at the point of
+intersection.</p>
+
+<p>In some cases, however, the rents seem to have been filled laterally, when
+the walls of the crater had been broken by star-shaped cracks, as seen in
+the accompanying woodcut (<a href="#img446">fig. 467.</a>). But the shape of these rents is an
+exception to the general rule; for nothing is more remarkable than the
+usual parallelism of the opposite sides of the dikes, which correspond
+almost as regularly as the two opposite faces <span class="pagenum"><a id="page405"></a>[p.405]</span>of a wall of
+masonry. This character appears at first the more inexplicable, when we
+consider how jagged and uneven are the rents caused by earthquakes in
+masses of heterogeneous composition, like those composing the cone of
+Somma. In explanation of this phenomenon, M. Necker refers us to Sir W.
+Hamilton's account of an eruption of Vesuvius in the year 1779, who records
+the following facts:&mdash;"The lavas, when they either boiled over the crater,
+or broke out from the conical parts of the volcano, constantly formed
+channels as regular as if they had been cut by art down the steep part of
+the mountain; and, whilst in a state of perfect fusion, continued their
+course in those channels, which were sometimes full to the brim, and at
+other times more or less so, according to the quantity of matter in motion.</p>
+
+<a id="img446" name="img446"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 467.</p>
+<img src="images/img446.jpg" width="450" height="291" alt="" title="">
+<p>Dikes or veins at the Punta del Nasone on <span class="wosp05">Somma.
+(Necker.</span><a name="FNanchor_AF_5" id="FNanchor_AF_5"></a><a href="#Footnote_AF_5" class="fnanchor">[405-A]</a>)</p></div>
+
+<p>"These channels, upon examination after an eruption, I have found to be in
+general from two to five or six feet wide, and seven or eight feet deep.
+They were often hid from the sight by a quantity of scori� that had formed
+a crust over them; and the lava, having been conveyed in a covered way for
+some yards, came out fresh again into an open channel. After an eruption, I
+have walked in some of those subterraneous or covered galleries, which were
+exceedingly curious, the sides, top, and bottom <i>being worn perfectly
+smooth and even</i> in most parts, by the violence of the currents of the
+red-hot lavas which they had conveyed for many weeks successively."<a name="FNanchor_AF_6" id="FNanchor_AF_6"></a><a href="#Footnote_AF_6" class="fnanchor">[405-B]</a></p>
+
+<p>Now, the walls of a vertical fissure, through which lava has ascended in
+its way to a volcanic vent, must have been exposed to the same erosion as
+the sides of the channels before adverted to. The prolonged and uniform
+friction of the heavy fluid, as it is forced and made to flow upwards,
+cannot fail to wear and smooth down the surfaces on which it rubs, and the
+intense heat must melt all such masses as project and obstruct the passage
+of the incandescent fluid.</p>
+
+<p><span class="pagenum"><a id="page406"></a>[p.406]</span>The texture of the Vesuvian dikes is different at the edges and in
+the middle. Towards the centre, observes M. Necker, the rock is larger
+grained, the component elements being in a far more crystalline state;
+while at the edge the lava is sometimes vitreous, and always finer grained.
+A thin parting band, approaching in its character to pitchstone,
+occasionally intervenes, on the contact of the vertical dike and
+intersected beds. M. Necker mentions one of these at the place called Primo
+Monte, in the Atrio del Cavallo; and when on Somma, in 1828, I saw three or
+four others in different parts of the great escarpment. These phenomena are
+in perfect harmony with the results of the experiments of Sir James Hall
+and Mr. Gregory Watt, which have shown that a glassy texture is the effect
+of sudden cooling, and that, on the contrary, a crystalline grain is
+produced where fused minerals are allowed to consolidate slowly and
+tranquilly under high pressure.</p>
+
+<p>It is evident that the central portion of the lava in a fissure would,
+during consolidation, part with its heat more slowly than the sides,
+although the contrast of circumstances would not be so great as when we
+compare the lava at the bottom and at the surface of a current flowing in
+the open air. In this case the uppermost part, where it has been in contact
+with the atmosphere, and where refrigeration has been most rapid, is always
+found to consist of scoriform, vitreous, and porous lava; while at a
+greater depth the mass assumes a more lithoidal structure, and then becomes
+more and more stony as we descend, until at length we are able to recognize
+with a magnifying glass the simple minerals of which the rock is composed.
+On penetrating still deeper, we can detect the constituent parts by the
+naked eye, and in the Vesuvian currents distinct crystals of augite and
+leucite become apparent.</p>
+
+<p>The same phenomenon, observes M. Necker, may readily be exhibited on a
+smaller scale, if we detach a piece of liquid lava from a moving current.
+The fragment cools instantly, and we find the surface covered with a
+vitreous coat; while the interior, although extremely fine-grained, has a
+more stony appearance.</p>
+
+<p>It must, however, be observed, that although the lateral portions of the
+dikes are finer grained than the central, yet the vitreous parting layer
+before alluded to is rare in Vesuvius. This may, perhaps, be accounted for,
+as the above-mentioned author suggests, by the great heat which the walls
+of a fissure may acquire before the fluid mass begins to consolidate, in
+which case the lava, even at the sides, would cool very slowly. Some
+fissures, also, may be filled from above, as frequently happens in the
+volcanos of the Sandwich Islands, according to the observations of Mr.
+Dana; and in this case the refrigeration at the sides would be more rapid
+than when the melted matter flowed upwards from the volcanic foci, in an
+intensely heated state. Mr. Darwin informs me that in St. Helena almost
+every dike has a vitreous selvage.</p>
+
+<p>The rock composing the dikes both in the modern and ancient part of
+Vesuvius is far more compact than that of ordinary lava, for <span class="pagenum"><a id="page407"></a>[p.407]</span>the
+pressure of a column of melted matter in a fissure greatly exceeds that in
+an ordinary stream of lava; and pressure checks the expansion of those
+gases which give rise to vesicles in lava.</p>
+
+<p>There is a tendency in almost all the Vesuvian dikes to divide into
+horizontal prisms, a phenomenon in accordance with the formation of
+vertical columns in horizontal beds of lava; for in both cases the
+divisions which give rise to the prismatic structure are at right angles to
+the cooling surfaces.</p>
+
+<p><i>Newer Pliocene Period&mdash;Val di Noto.</i>&mdash;I have already alluded (see <a href="#page150">p. 150.</a>)
+to the igneous rocks which are associated with a great marine formation of
+limestone, sand, and marl, in the southern part of Sicily, as at Vizzini
+and other places. In this formation, which was shown to belong to the Newer
+Pliocene period, large beds of oysters and corals repose upon lava, and are
+unaltered at the point of contact. In other places we find dikes of igneous
+rock intersecting the fossiliferous beds, and converting the clays into
+siliceous schist, the lamin� being contorted and shivered into innumerable
+fragments at the junction, as near the town of Vizzini.</p>
+
+<p>The volcanic formations of the Val di Noto usually consist of the most
+ordinary variety of basalt, with or without olivine. The rock is sometimes
+compact, often very vesicular. The vesicles are occasionally empty, both in
+dikes and currents, and are in some localities filled with calcareous spar,
+arragonite, and zeolites. The structure is, in some places, spheroidal; in
+others, though rarely, columnar. I found dikes of amygdaloid, wack�, and
+prismatic basalt, intersecting the limestone at the bottom of the hollow
+called Gozzo degli Martiri, below Melilli.</p>
+
+<a id="img447" name="img447"></a>
+<div class="figcenter smaller width350">
+<img src="images/img447.jpg" width="350" height="237" alt="" title="">
+<p>Fig. 468. Fig. 469. Ground-plan of dikes near Palagonia.</p>
+<ul class="martopm05 smaller leftal add1em min2em">
+<li><i>a.</i> Lava.</li>
+<li><i>b.</i> Peperino, consisting of volcanic sand, mixed with
+fragments of lava and limestone.</li>
+</ul></div>
+
+<p><i>Dikes.</i>&mdash;Dikes of vesicular and amygdaloidal lava are also seen traversing
+marine tuff or peperino, west of Palagonia, some of the pores of the lava
+being empty, while others are filled with carbonate of lime. In such cases,
+we may suppose the peperino to have resulted from showers of volcanic sand
+and scori�, together with fragments of limestone, thrown out by a submarine
+explosion, similar to that which gave rise to Graham Island in 1831. When
+the mass <span class="pagenum"><a id="page408"></a>[p.408]</span>was, to a certain degree, consolidated, it may have been
+rent open, so that the lava ascended through fissures, the walls of which
+were perfectly even and parallel. After the melted matter that filled the
+rent in <a href="#img447">fig. 468.</a> had cooled down, it must have been fractured and shifted
+horizontally by a lateral movement.</p>
+
+<p>In the second figure (<a href="#img447">fig. 469.</a>), the lava has more the appearance of a
+vein which forced its way through the peperino. It is highly probable that
+similar appearances would be seen, if we could examine the floor of the sea
+in that part of the Mediterranean where the waves have recently washed away
+the new volcanic island; for when a superincumbent mass of ejected
+fragments has been removed by denudation, we may expect to see sections of
+dikes traversing tuff, or, in other words, sections of the channels of
+communication by which the subterranean lavas reached the surface.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XXXI.</h2>
+
+<h4>ON THE DIFFERENT AGES OF THE VOLCANIC ROCKS&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Volcanic rocks of the Older Pliocene period &mdash; Tuscany &mdash; Rome
+&mdash; Volcanic region of Olot in Catalonia &mdash; Cones and
+lava-currents &mdash; Ravines and ancient gravel-beds &mdash; Jets of air
+called Bufadors &mdash; Age of the Catalonian volcanos &mdash; Miocene
+period &mdash; Brown-coal of the Eifel and contemporaneous trachytic
+breccias &mdash; Age of the brown-coal &mdash; Peculiar characters of the
+volcanos of the upper and lower Eifel &mdash; Lake craters &mdash; Trass
+&mdash; Hungarian volcanos.</p></div>
+
+
+<p><i><span class="smcap">Older</span> Pliocene period&mdash;Tuscany.</i>&mdash;In Tuscany, as at Radicofani, Viterbo,
+and Aquapendente, and in the Campagna di Roma, submarine volcanic tuffs are
+interstratified with the Older Pliocene strata of the Subapennine hills, in
+such a manner as to leave no doubt that they were the products of eruptions
+which occurred when the shelly marls and sands of the Subapennine hills
+were in the course of deposition.</p>
+
+<p><i>Catalonia.</i>&mdash;Geologists are far from being able, as yet, to assign to each
+of the volcanic groups scattered over Europe a precise chronological place
+in the tertiary series; but I shall describe here, as probably referable to
+some part of the Pliocene period, a district of extinct volcanos near Olot,
+in the north of Spain, which is little known, and which I visited in the
+summer of 1830.</p>
+
+<p>The whole extent of country occupied by volcanic products in Catalonia is
+not more than fifteen geographical miles from north to south, and about six
+from east to west. The vents of eruption range entirely within a narrow
+band running north and south; and the branches, which are represented as
+extending eastward in the map, are formed simply of two lava-streams&mdash;those
+of Castell Follit and Cellent.</p>
+
+<span class="pagenum"><a id="page409"></a>[p.409]</span>
+<a id="img448" name="img448"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 470.</p>
+<img src="images/img448.jpg" width="450" height="558" alt="" title="">
+<p>Volcanic district of Catalonia.</p></div>
+
+<p>Dr. Maclure, the American geologist, was the first who made known the
+existence of these volcanos<a name="FNanchor_AG_1" id="FNanchor_AG_1"></a><a href="#Footnote_AG_1" class="fnanchor">[409-A]</a>; and, according to his description, the
+volcanic region extended over twenty square leagues, from Amer to Massanet.
+I searched in vain in the environs of Massanet, in the Pyrenees, for traces
+of a lava-current; and I can say, with confidence, that the adjoining map
+gives a correct view of the true area of the volcanic action.</p>
+
+<p><i>Geological structure of the district.</i>&mdash;The eruptions have burst entirely
+through fossiliferous rocks, composed in great part of grey and greenish
+sandstone and conglomerate, with some thick beds of nummulitic limestone.
+The conglomerate contains pebbles of quartz, limestone, and Lydian stone.
+This system of rocks is very extensively spread throughout Catalonia; one
+of its members being a red sandstone, to which the celebrated salt-rock of
+Cardona, usually considered as of the cretaceous era, is subordinate.</p>
+
+<p>Near Amer, in the Valley of the Ter, on the southern borders of the region
+delineated in the map, primary rocks are seen, consisting of gneiss,
+mica-schist, and clay-slate. They run in a line nearly parallel to the
+Pyrenees, and throw off the fossiliferous strata from their flanks, causing
+them to dip to the north and north-west. This <span class="pagenum"><a id="page410"></a>[p.410]</span>dip, which is
+towards the Pyrenees, is connected with a distinct axis of elevation, and
+prevails through the whole area described in the map, the inclination of
+the beds being sometimes at an angle of between 40 and 50 degrees.</p>
+
+<p>It is evident that the physical geography of the country has undergone no
+material change since the commencement of the era of the volcanic
+eruptions, except such as has resulted from the introduction of new hills
+of scori�, and currents of lava upon the surface. If the lavas could be
+remelted and poured out again from their respective craters, they would
+descend the same valleys in which they are now seen, and re-occupy the
+spaces which they at present fill. The only difference in the external
+configuration of the fresh lavas would consist in this, that they would
+nowhere be intersected by ravines, or exhibit marks of erosion by running
+water.</p>
+
+<p><i>Volcanic cones and lavas.</i>&mdash;There are about fourteen distinct cones with
+craters in this part of Spain, besides several points whence lavas may have
+issued; all of them arranged along a narrow line running north and south,
+as will be seen in the map. The greatest number of perfect cones are in the
+immediate neighbourhood of Olot, some of which (Nos. 2, 3. and 5.) are
+represented in the annexed woodcut; and the level plain on which that town
+stands has clearly been produced by the flowing down of many lava-streams
+from those hills into the bottom of a valley, probably once of considerable
+depth, like those of the surrounding country.</p>
+
+<a id="img449" name="img449"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 471.</p>
+<img src="images/img449.jpg" width="500" height="343" alt="" title="">
+<p>View of the Volcanos around Olot in Catalonia.</p></div>
+
+<p>In this drawing an attempt is made to represent, by the shading of the
+landscape, the different geological formations of which the country is
+composed.<a name="FNanchor_AG_2" id="FNanchor_AG_2"></a><a href="#Footnote_AG_2" class="fnanchor">[410-A]</a> The white line of mountains (No. 1.) in the distance
+<span class="pagenum"><a id="page411"></a>[p.411]</span>is the Pyrenees, which are to the north of the spectator, and
+consist of hypogene and ancient fossiliferous rocks. In front of these are
+the fossiliferous formations (No. 4.) which are in shade. The hills 2, 3.
+5. are volcanic cones, and the rest of the ground on which the sunshine
+falls is strewed over with volcanic ashes and lava.</p>
+
+<p>The Fluvia, which flows near the town of Olot, has cut to the depth of only
+40 feet through the lavas of the plain before mentioned. The bed of the
+river is hard basalt; and at the bridge of Santa Madalena are seen two
+distinct lava-currents, one above the other, separated by a horizontal bed
+of scori� 8 feet thick.</p>
+
+<p>In one place, to the south of Olot, the even surface of the plain is broken
+by a mound of lava, called the "Bosque de Tosca," the upper part of which
+is scoriaceous, and covered with enormous heaps of fragments of basalt,
+more or less porous. Between the numerous hummocks thus formed are deep
+cavities, having the appearance of small craters. The whole precisely
+resembles some of the modern currents of Etna, or that of C�me, near
+Clermont; the last of which, like the Bosque de Tosca, supports only a
+scanty vegetation.</p>
+
+<p>Most of the Catalonian volcanos are as entire as those in the neighbourhood
+of Naples, or on the flanks of Etna. One of these, called Montsacopa (No.
+3. <a href="#img449">fig. 471.</a>), is of a very regular form, and has a circular depression or
+crater at the summit. It is chiefly made up of red scori�,
+undistinguishable from that of the minor cones of Etna. The neighbouring
+hills of Olivet (No. 2.) and Garrinada (No. 5.) are of similar composition
+and shape. The largest crater of the whole district occurs farther to the
+east of Olot, and is called Santa Margarita. It is 455 feet deep, and about
+a mile in circumference. Like Astroni, near Naples, it is richly covered
+with wood, wherein game of various kinds abounds.</p>
+
+<a id="img450" name="img450"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 472.</p>
+<img src="images/img450.jpg" width="250" height="121" alt="" title="">
+<ul class="smaller leftal min1em">
+<li><i>a.</i> Secondary conglomerate.</li>
+<li><i>b.</i> Thin seams of volcanic sand and scori�.</li>
+</ul></div>
+
+<p>Although the volcanos of Catalonia have broken out through sandstone,
+shale, and limestone, as have those of the Eifel, in Germany, to be
+described in the sequel, there is a remarkable difference in the nature of
+the ejections composing the cones in these two regions. In the Eifel, the
+quantity of pieces of sandstone and shale thrown out from the vents is
+often so immense as far to exceed in volume the scori�, pumice, and lava;
+but I sought in vain in the cones near Olot for a single fragment of any
+extraneous rock; and Don Francisco Bolos, an eminent botanist of Olot,
+informed me that he had never been able to detect any. Volcanic sand and
+ashes are not confined to the cones, but have been sometimes scattered by
+the wind over the country, and drifted into narrow valleys, as is seen
+between Olot and Cellent, where the annexed section (<a href="#img450">fig. 472.</a>) is exposed.
+The light cindery volcanic matter rests in thin regular layers, just as it
+alighted on the slope formed by the solid conglomerate. No flood could have
+passed through <span class="pagenum"><a id="page412"></a>[p.412]</span>the valley since the scori� fell, or these would
+have been for the most part removed.</p>
+
+<a id="img451" name="img451"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 473.</p>
+<img src="images/img451.jpg" width="450" height="230" alt="" title="">
+<p>Section above the bridge of Cellent.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Scoriaceous lava.</li>
+<li><i>b.</i> Schistose basalt.</li>
+<li><i>c.</i> Columnar basalt.</li>
+<li><i>d.</i> Scoria, vegetable soil, and alluvium.</li>
+<li><i>e.</i> Nummulitic limestone.</li>
+<li><i>f.</i> Micaceous grey sandstone.</li>
+</ul></div>
+
+<p>The currents of lava in Catalonia, like those of Auvergne, the Vivarais,
+Iceland, and all mountainous countries, are of considerable depth in narrow
+defiles, but spread out into comparatively thin sheets in places where the
+valleys widen. If a river has flowed on nearly level ground, as in the
+great plain near Olot, the water has only excavated a channel of slight
+depth; but where the declivity is great, the stream has cut a deep section,
+sometimes by penetrating directly through the central part of a
+lava-current, but more frequently by passing between the lava and the
+secondary rock which bounds the valley. Thus, in the accompanying section,
+at the bridge of Cellent, six miles east of Olot, we see the lava on one
+side of the small stream; while the inclined stratified rocks constitute
+the channel and opposite bank. The upper part of the lava at that place, as
+is usual in the currents of Etna and Vesuvius, is scoriaceous; farther down
+it becomes less porous, and assumes a spheroidal structure; still lower it
+divides in horizontal plates, each about 2 inches in thickness, and is more
+compact. Lastly, at the bottom is a mass of prismatic basalt about 5 feet
+thick. The vertical columns often rest immediately on the subjacent
+secondary rocks; but there is sometimes an intervention of such sand and
+scori� as cover the country during volcanic eruptions, and which when
+unprotected, as here, by superincumbent lava, is washed away from the
+surface of the land. Sometimes, the bed <i>d</i> contains a few pebbles and
+angular fragments of rock; in other places fine earth, which may have
+constituted an ancient vegetable soil.</p>
+
+<p>In several localities, beds of sand and ashes are interposed between the
+lava and subjacent stratified rock, as may be seen if we follow the course
+of the lava-current which descends from Las Planas towards Amer, and stops
+two miles short of that town. The river there has often cut through the
+lava, and through 18 feet of underlying <span class="pagenum"><a id="page413"></a>[p.413]</span>limestone. Occasionally
+an alluvium, several feet thick, is interspersed between the igneous and
+marine formation; and it is interesting to remark that in this, as in other
+beds of pebbles occupying a similar position, there are no rounded
+fragments of lava; whereas in the most modern gravel-beds of rivers of this
+country, volcanic pebbles are abundant.</p>
+
+<p>The deepest excavation made by a river through lava, which I observed in
+this part of Spain, is that seen in the bottom of a valley near San Feliu
+de Paller�ls, opposite the Castell de Stolles. The lava there has filled up
+the bottom of a valley, and a narrow ravine has been cut through it to the
+depth of 100 feet. In the lower part the lava has a columnar structure. A
+great number of ages were probably required for the erosion of so deep a
+ravine; but we have no reason to infer that this current is of higher
+antiquity than those of the plain near Olot. The fall of the ground, and
+consequent velocity of the stream, being in this case greater, a more
+considerable volume of rock may have been removed in the same time.</p>
+
+<a id="img452" name="img452"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 474.</p>
+<img src="images/img452.jpg" width="450" height="242" alt="" title="">
+<p>Section at Castell Follit.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li>A. Church and town of Castell Follit, overlooking precipices of basalt.</li>
+<li>B. Small island, on each side of which branches of the river Teronel
+flow to meet the Fluvia.</li>
+<li><i>c.</i> Precipice of basaltic lava, chiefly columnar, about
+130 feet in height.</li>
+<li><i>d.</i> Ancient alluvium, underlying the lava-current.</li>
+<li><i>e.</i> Inclined strata of secondary sandstone.</li>
+</ul></div>
+
+<p>I shall describe one more section to elucidate the phenomena of this
+district. A lava-stream, flowing from a ridge of hills on the east of Olot,
+descends a considerable slope, until it reaches the valley of the river
+Fluvia. Here, for the first time, it comes in contact with running water,
+which has removed a portion, and laid open its internal structure in a
+precipice about 130 feet in height, at the edge of which stands the town of
+Castell Follit.</p>
+
+<p>By the junction of the rivers Fluvia and Teronel, the mass of lava has been
+cut away on two sides; and the insular rock <span class="smcap">B</span> (<a href="#img452">fig. 474.</a>) has been left,
+which was probably never so high as the cliff <span class="smcap">A</span>, as it may have constituted
+the lower part of the sloping side of the original current.</p>
+
+<p>From an examination of the vertical cliffs, it appears that the upper part
+of the lava on which the town is built is scoriaceous, <span class="pagenum"><a id="page414"></a>[p.414]</span>passing
+downwards into a spheroidal basalt; some of the huge spheroids being no
+less than 6 feet in diameter. Below this is a more compact basalt, with
+crystals of olivine. There are in all five distinct ranges of basalt, the
+uppermost spheroidal, and the rest prismatic, separated by thinner beds not
+columnar, and some of which are schistose. These were probably formed by
+successive flows of lava, whether during the same eruption or at different
+periods. The whole mass rests on alluvium, ten or twelve feet in thickness,
+composed of pebbles of limestone and quartz, but without any intermixture
+of igneous rocks; in which circumstance alone it appears to differ from the
+modern gravel of the Fluvia.</p>
+
+<p><i>Bufadors.</i>&mdash;The volcanic rocks near Olot have often a cavernous structure,
+like some of the lavas of Etna; and in many parts of the hill of Batet, in
+the environs of the town, the sound returned by the earth, when struck, is
+like that of an archway. At the base of the same hill are the mouths of
+several subterranean caverns, about twelve in number, which are called in
+the country "bufadors," from which a current of cold air issues during
+summer, but which in winter is said to be scarcely perceptible. I visited
+one of these bufadors in the beginning of August, 1830, when the heat of
+the season was unusually intense, and found a cold wind blowing from it,
+which may easily be explained; for as the external air, when rarefied by
+heat, ascends, the pressure of the colder and heavier air of the caverns in
+the interior of the mountain causes it to rush out to supply its place.</p>
+
+<p>In regard to the age of these Spanish volcanos, attempts have been made to
+prove, that in this country, as well as in Auvergne and the Eifel, the
+earliest inhabitants were eye-witnesses to the volcanic action. In the year
+1421, it is said, when Olot was destroyed by an earthquake, an eruption
+broke out near Amer, and consumed the town. The researches of Don Francisco
+Bolos have, I think, shown, in the most satisfactory manner, that there is
+no good historical foundation for the latter part of this story; and any
+geologist who has visited Amer must be convinced that there never was any
+eruption on that spot. It is true that, in the year above mentioned, the
+whole of Olot, with the exception of a single house, was cast down by an
+earthquake; one of those shocks which, at distant intervals during the last
+five centuries, have shaken the Pyrenees, and particularly the country
+between Perpignan and Olot, where the movements, at the period alluded to,
+were most violent.</p>
+
+<p>The annihilation of the town may, perhaps, have been due to the cavernous
+nature of the subjacent rocks; for Catalonia is beyond the line of those
+European earthquakes which have, within the period of history, destroyed
+towns throughout extensive areas.</p>
+
+<p>As we have no historical records, then, to guide us in regard to the
+extinct volcanos, we must appeal to geological monuments. The annexed
+diagram will present to the reader, in a synoptical form, the results
+obtained from numerous sections.</p>
+
+<p>The more modern alluvium (<i>d</i>) is partial, and has been formed by <span class="pagenum"><a id="page415"></a>[p.415]</span>
+the action of rivers and floods upon the lava; whereas the older gravel
+(<i>b</i>) was strewed over the country before the volcanic eruptions. In
+neither have any organic remains been discovered; so that we can merely
+affirm, as yet, that the volcanos broke out after the elevation of some of
+the newest rocks of the nummulitic (Eocene?) series of Catalonia, and
+before the formation of an alluvium (<i>d</i>) of unknown date. The integrity of
+the cones merely shows that the country has not been agitated by violent
+earthquakes, or subjected to the action of any great transient flood since
+their origin.</p>
+
+<a id="img453" name="img453"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 475.</p>
+<img src="images/img453.jpg" width="450" height="127" alt="" title="">
+<p>Superposition of rocks in the volcanic district of Catalonia.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Sandstone and nummulitic limestone.</li>
+<li><i>b.</i> Older alluvium without volcanic pebbles.</li>
+<li><i>c.</i> Cones of scori� and lava.</li>
+<li><i>d.</i> Newer alluvium.</li>
+</ul></div>
+
+<p>East of Olot, on the Catalonian coast, marine tertiary strata occur, which,
+near Barcelona, attain the height of about 500 feet. From the shells which
+I collected, these strata appear to correspond in age with the Subapennine
+beds; and it is not improbable that their upheaval from beneath the sea
+took place during the period of volcanic eruption round Olot. In that case
+these eruptions may have occurred at the close of the Older Pliocene era,
+but perhaps subsequently, for their age is at present quite uncertain.</p>
+
+<p><i>Miocene period&mdash;Volcanic rocks of the Eifel.</i>&mdash;The chronological relations
+of the volcanic rocks of the Lower Rhine and the Eifel are also involved in
+a considerable degree of ambiguity; but we know that some portion of them
+were coeval with the deposition of a tertiary formation, called
+"Brown-Coal" by the Germans, which probably belongs to the Miocene, if not
+referable to the Upper Eocene, epoch.</p>
+
+<p>This Brown-Coal is seen on both sides of the Rhine, in the neighbourhood of
+Bonn, resting unconformably on highly inclined and vertical strata of
+Silurian and Devonian rocks. Its position, and the space occupied by the
+volcanic rocks, both of the Westerwald and Eifel, will be seen by referring
+to the map in the next page (<a href="#img454">fig. 476.</a>), for which I am indebted to Mr.
+Horner, whose residence in the country has enabled him to verify the maps
+of MM. Noeggerath and Von Oeynhausen, from which that now given has been
+principally compiled.</p>
+
+<p>The Brown-Coal formation consists of beds of loose sand, sandstone, and
+conglomerate, clay with nodules of clay-ironstone, and occasionally silex.
+Layers of light brown, and sometimes black lignite, are interstratified
+with the clays and sands, and often irregularly diffused through them. They
+contain numerous impressions of <span class="pagenum"><a id="page416"></a>[p.416]</span>leaves and stems of trees, and
+are extensively worked for fuel, whence the name of the formation.</p>
+
+<a id="img454" name="img454"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 476. Map of the volcanic region of the Upper and Lower Eifel.</p>
+<img src="images/img454.jpg" width="500" height="569" alt="" title="">
+<p><i>N.B.</i> The country in that part of the map which is left blank is
+composed of inclined Silurian and Devonian rocks.</p></div>
+
+<p>In several places, layers of trachytic tuff are interstratified, and in
+these tuffs are leaves of plants identical with those found in the
+brown-coal, showing that, during the period of the accumulation of the
+latter, some volcanic products were ejected.</p>
+
+<p>The varieties of wood in the lignite are said to belong entirely to
+dicotyledonous trees; but among the impressions of leaves, collected by Mr.
+Horner, some were referred by Mr. Lindley to a palm, perhaps of the genus
+<i>Cham�rops</i>, and others resembled the <i>Cinnamomum dulce</i>, and <i>Podocarpus
+macrophylla</i>, which would also indicate a warm climate.<a name="FNanchor_AG_3" id="FNanchor_AG_3"></a><a href="#Footnote_AG_3" class="fnanchor">[416-A]</a></p>
+
+<p>The other organic remains of the brown-coal are principally fishes; they
+are found in a bituminous shale, called paper-coal, from being <span class="pagenum"><a id="page417"></a>[p.417]</span>
+divisible into extremely thin leaves. The individuals are very numerous;
+but they appear to belong to about five species, which M. Agassiz informs
+me are all extinct, and hitherto peculiar to this brown-coal. They belong
+to the freshwater genera <i>Leuciscus</i>, <i>Aspius</i>, and <i>Perca</i>. The remains of
+frogs also, of an extinct species, have been discovered in the paper-coal;
+and a complete series may be seen in the museum at Bonn, from the most
+imperfect state of the tadpole to that of the full-grown animal. With these
+a salamander, scarcely distinguishable from the recent species, has been
+found, and several remains of insects.</p>
+
+<p>The brown-coal was evidently a freshwater formation; but fossil shells have
+been scarcely ever found in it; although near Marienforst, in the vicinity
+of Bonn, large blocks have been met with of a white opaque chert,
+containing numerous casts of freshwater shells, which appear to belong to
+<i>Planorbis rotundatus</i> and <i>Limnea longiscata</i>, two species common both to
+the Middle and Upper Eocene periods. It is very probable that the
+brown-coal may be connected in age with those fluvio-marine formations
+which are found in higher parts of the valley of the Rhine, as at Mayence
+before mentioned (<a href="#page177">p. 177.</a>).</p>
+
+<p>A vast deposit of gravel, chiefly composed of pebbles of white quartz, but
+containing also a few fragments of other rocks, lies over the brown-coal
+formation, forming sometimes only a thin covering, at others attaining a
+thickness of more than 100 feet. This gravel is very distinct in character
+from that now forming the bed of the Rhine. It is called "Kiesel gerolle"
+by the Germans, often reaches great elevations, and is covered in several
+places with volcanic ejections. It is evident that the country has
+undergone great changes in its physical geography since this gravel was
+formed; for its position has scarcely any relation to the existing drainage
+of the country, and all the more modern volcanic rocks of the same region
+are posterior to it in date.</p>
+
+<p>Some of the newest beds of volcanic sand, pumice, and scori� are
+interstratified near Andernach and elsewhere with the loam called loess,
+which was before described as being full of land and freshwater shells of
+recent species, and referable to the Post-Pliocene period. I have before
+hinted (see <a href="#page118">p. 118.</a>) that this intercalation of volcanic matter between
+beds of loess may possibly be explained without supposing the last
+eruptions of the Lower Eifel to have taken place so recently as the era of
+the deposition of the loess; but farther researches should be directed to
+the investigation of this curious point.</p>
+
+<p>The igneous rocks of the Westerwald, and of the mountains called the
+Siebengebirge, consist partly of basaltic and partly of trachytic lavas,
+the latter being in general the more ancient of the two. There are many
+varieties of trachyte, some of which are highly crystalline, resembling a
+coarse-grained granite, with large separate crystals of felspar. Trachytic
+tuff is also very abundant. These formations, some of which were certainly
+contemporaneous with the origin of the brown-coal, were the first of a long
+series of eruptions, the <span class="pagenum"><a id="page418"></a>[p.418]</span>more recent of which happened when the
+country had acquired nearly all its present geographical features.</p>
+
+<p><i>Newer volcanos of the Eifel.&mdash;Lake-craters.</i>&mdash;As I recognized in the more
+modern volcanos of the Eifel characters distinct from any previously
+observed by me in those of France, Italy, or Spain, I shall briefly
+describe them. The fundamental rocks of the district are grey and red
+sandstones and shales, with some associated limestones, replete with
+fossils of the Devonian or Old Red Sandstone group. The volcanos broke out
+in the midst of these inclined strata, and when the present systems of
+hills and valleys had already been formed. The eruptions occurred sometimes
+at the bottom of deep valleys, sometimes on the summit of hills, and
+frequently on intervening platforms. In travelling through this district we
+often fall upon them most unexpectedly, and may find ourselves on the very
+edge of a crater before we had been led to suspect that we were approaching
+the site of any igneous outburst. Thus, for example, on arriving at the
+village of Gemund, immediately south of Daun, we leave the stream, which
+flows at the bottom of a deep valley in which strata of sandstone and shale
+crop out. We then climb a steep hill, on the surface of which we see the
+edges of the same strata dipping inwards towards the mountain. When we have
+ascended to a considerable height, we see fragments of scori� sparingly
+scattered over the surface; till, at length, on reaching the summit, we
+find ourselves suddenly on the edge of a <i>tarn</i>, or deep circular
+lake-basin.</p>
+
+<a id="img455" name="img455"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 477.</p>
+<img src="images/img455.jpg" width="500" height="183" alt="" title="">
+<p>The Gemunder Maar.</p></div>
+
+<a id="img456" name="img456"></a>
+<div class="figcenter smaller width500">
+<p class="martop2">Fig. 478.</p>
+<img src="images/img456.jpg" width="500" height="104" alt="" title="">
+<ul class="smaller leftal add8em">
+<li><i>a.</i> Village of Gemund.</li>
+<li><i>b.</i> Gemunder Maar.</li>
+<li><i>c.</i> Weinfelder Maar.</li>
+<li><i>d.</i> Schalkenmehren Maar.</li>
+</ul></div>
+
+<p>This, which is called the Gemunder Maar, is the first of three lakes which
+are in immediate contact, the same ridge forming the barrier of two
+neighbouring cavities (see <a href="#img455">fig. 477.</a>). On viewing the first of these, we
+recognize the ordinary form of a crater, for which <span class="pagenum"><a id="page419"></a>[p.419]</span>we have been
+prepared by the occurrence of scori� scattered over the surface of the
+soil. But on examining the walls of the crater we find precipices of
+sandstone and shale which exhibit no signs of the action of heat; and we
+look in vain for those beds of lava and scori�, dipping in opposite
+directions on every side, which we have been accustomed to consider as
+characteristic of volcanic craters. As we proceed, however, to the opposite
+side of the lake, and afterwards visit the craters <i>c</i> and <i>d</i> (<a href="#img456">fig. 478.</a>),
+we find a considerable quantity of scori� and some lava, and see the whole
+surface of the soil sparkling with volcanic sand, and strewed with ejected
+fragments of half-fused shale, which preserves its laminated texture in the
+interior, while it has a vitrified or scoriform coating.</p>
+
+<p>A few miles to the south of the lakes above mentioned occurs the Pulvermaar
+of Gillenfeld, an oval lake of very regular form, and surrounded by an
+unbroken ridge of fragmentary materials, consisting of ejected shale and
+sandstone, and preserving a uniform height of about 150 feet above the
+water. The side slope in the interior is at an angle of about 45 degrees;
+on the exterior, of 35 degrees. Volcanic substances are intermixed very
+sparingly with the ejections, which in this place entirely conceal from
+view the stratified rocks of the country.<a name="FNanchor_AG_4" id="FNanchor_AG_4"></a><a href="#Footnote_AG_4" class="fnanchor">[419-A]</a></p>
+
+<a id="img457" name="img457"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 479.</p>
+<img src="images/img457.jpg" width="400" height="126" alt="" title="">
+<p>Outline of Mosenberg, Upper Eifel.</p></div>
+
+<p>The Meerfelder Maar is a cavity of far greater size and depth, hollowed out
+of similar strata; the sides presenting some abrupt sections of inclined
+secondary rocks, which in other places are buried under vast heaps of
+pulverized shale. I could discover no scori� amongst the ejected materials,
+but balls of olivine and other volcanic substances are mentioned as having
+been found.<a name="FNanchor_AG_5" id="FNanchor_AG_5"></a><a href="#Footnote_AG_5" class="fnanchor">[419-B]</a> This cavity, which we must suppose to have discharged an
+immense volume of gas, is nearly a mile in diameter, and is said to be more
+than one hundred fathoms deep. In the neighbourhood is a mountain called
+the Mosenberg, which consists of red sandstone and shale in its lower
+parts, but supports on its summit a triple volcanic cone, while a distinct
+current of lava is seen descending the flanks of the mountain. The edge of
+the crater of the largest cone reminded me much of the form and characters
+of that of Vesuvius; but I was much struck with the precipitous and almost
+overhanging wall or parapet which the scori� presented towards the
+exterior, as at <i>a b</i> (<a href="#img457">fig. 479.</a>); which I can only explain by supposing
+that fragments of red-hot lava, as they fell <span class="pagenum"><a id="page420"></a>[p.420]</span>round the vent, were
+cemented together into one compact mass, in consequence of continuing to be
+in a half-melted state.</p>
+
+<p>If we pass from the Upper to the Lower Eifel, from <span class="smcap">A</span> to <span class="smcap">B</span> (see map, <a href="#page416">p.
+416.</a>), we find the celebrated lake-crater of Laach, which has a greater
+resemblance than any of those before mentioned to the Lago di Bolsena, and
+others in Italy&mdash;being surrounded by a ridge of gently sloping hills,
+composed of loose tuffs, scori�, and blocks of a variety of lavas.</p>
+
+<p>One of the most interesting volcanos on the left bank of the Rhine is
+called the Roderberg. It forms a circular crater nearly a quarter of a mile
+in diameter, and 100 feet deep, now covered with fields of corn. The highly
+inclined strata of ancient sandstone and shale rise even to the rim of one
+side of the crater; but they are overspread by quartzose gravel, and this
+again is covered by volcanic scori� and tufaceous sand. The opposite wall
+of the crater is composed of cinders and scorified rock, like that at the
+summit of Vesuvius. It is quite evident that the eruption in this case
+burst through the sandstone and alluvium which immediately overlies it; and
+I observed some of the quartz pebbles mixed with scori� on the flanks of
+the mountain, as if they had been cast up into the air, and had fallen
+again with the volcanic ashes. I have already observed, that a large part
+of this crater has been filled up with loess (<a href="#page118">p. 118.</a>).</p>
+
+<p>The most striking peculiarity of a great many of the craters above
+described, is the absence of any signs of alteration or torrefaction in
+their walls, when these are composed of regular strata of ancient sandstone
+and shale. It is evident that the summits of hills formed of the
+above-mentioned stratified rocks have, in some cases, been carried away by
+gaseous explosions, while at the same time no lava, and often a very small
+quantity only of scori�, has escaped from the newly formed cavity. There
+is, indeed, no feature in the Eifel volcanos more worthy of note, than the
+proofs they afford of very copious a�riform discharges, unaccompanied by
+the pouring out of melted matter, except, here and there, in very
+insignificant volume. I know of no other extinct volcanos where gaseous
+explosions of such magnitude have been attended by the emission of so small
+a quantity of lava. Yet I looked in vain in the Eifel for any appearances
+which could lend support to the hypothesis, that the sudden rushing out of
+such enormous volumes of gas had ever lifted up the stratified rocks
+immediately around the vent, so as to form conical masses, having their
+strata dipping outwards on all sides from a central axis, as is assumed in
+the theory of elevation craters, alluded to at the end of Chap. XXIX.</p>
+
+<p><i>Trass.</i>&mdash;In the Lower Eifel, eruptions of trachytic lava preceded the
+emission of currents of basalt, and immense quantities of pumice were
+thrown out wherever trachyte issued. The tufaceous alluvium called <i>trass</i>,
+which has covered large areas in this region and choked up some valleys now
+partially re-excavated, is unstratified. Its base consists almost entirely
+of pumice, in which are included fragments of basalt and other lavas,
+pieces of burnt shale, slate, and sandstone, <span class="pagenum"><a id="page421"></a>[p.421]</span>and numerous trunks
+and branches of trees. If this trass was formed during the period of
+volcanic eruptions it may perhaps have originated in the manner of the moya
+of the Andes.</p>
+
+<p>We may easily conceive that a similar mass might now be produced, if a
+copious evolution of gases should occur in one of the lake basins. The
+water might remain for weeks in a state of violent ebullition, until it
+became of the consistency of mud, just as the sea continued to be charged
+with red mud round Graham's Island, in the Mediterranean, in the year 1831.
+If a breach should then be made in the side of the cone, the flood would
+sweep away great heaps of ejected fragments of shale and sandstone, which
+would be borne down into the adjoining valleys. Forests might be torn up by
+such a flood, and thus the occurrence of the numerous trunks of trees
+dispersed irregularly through the trass, can be explained.</p>
+
+<p><i>Hungary.</i>&mdash;M. Beudant, in his elaborate work on Hungary, describes five
+distinct groups of volcanic rocks, which although nowhere of great extent,
+form striking features in the physical geography of that country, rising as
+they do abruptly from extensive plains composed of tertiary strata. They
+may have constituted islands in the ancient sea, as Santorin and Milo now
+do in the Grecian Archipelago; and M. Beudant has remarked that the mineral
+products of the last-mentioned islands resemble remarkably those of the
+Hungarian extinct volcanos, where many of the same minerals as opal,
+calcedony, resinous silex (<i>silex resinite</i>), pearlite, obsidian, and
+pitchstone abound.</p>
+
+<p>The Hungarian lavas are chiefly felspathic, consisting of different
+varieties of trachyte; many are cellular, and used as millstones; some so
+porous and even scoriform as to resemble those which have issued in the
+open air. Pumice occurs in great quantity; and there are conglomerates, or
+rather breccias, wherein fragments of trachyte are bound together by
+pumiceous tuff, or sometimes by silex.</p>
+
+<p>It is probable that these rocks were permeated by the waters of hot
+springs, impregnated, like the Geysers, with silica; or in some instances,
+perhaps, by aqueous vapours, which, like those of Lancerote, may have
+precipitated hydrate of silica.</p>
+
+<p>By the influence of such springs or vapours the trunks and branches of
+trees washed down during floods, and buried in tuffs on the flanks of the
+mountains, are supposed to have become silicified. It is scarcely possible,
+says M. Beudant, to dig into any of the pumiceous deposits of these
+mountains without meeting with opalized wood, and sometimes entire
+silicified trunks of trees of great size and weight.</p>
+
+<p>It appears from the species of shells collected principally by M. Bou�, and
+examined by M. Deshayes, that the fossil remains imbedded in the volcanic
+tuffs, and in strata alternating with them in Hungary, are of the Miocene
+type, and not identical, as was formerly supposed, with the fossils of the
+Paris basin.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page422"></a>[p.422]</span>CHAPTER XXXII.</h2>
+
+<h4>ON THE DIFFERENT AGES OF THE VOLCANIC ROCKS&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Volcanic rocks of the Pliocene and Miocene periods continued &mdash;
+Auvergne &mdash; Mont Dor &mdash; Breccias and alluviums of Mont Perrier,
+with bones of quadrupeds &mdash; River dammed up by lava-current &mdash;
+Range of minor cones from Auvergne to the Vivarais &mdash; Monts Dome
+&mdash; Puy de C�me &mdash; Puy de Pariou &mdash; Cones not denuded by
+general flood &mdash; Velay &mdash; Bones of quadrupeds buried in scori�
+&mdash; Cantal &mdash; Eocene volcanic rocks &mdash; Tuffs near Clermont
+&mdash; Hill of Gergovia &mdash; Trap of Cretaceous period &mdash; Oolitic
+period &mdash; New Red Sandstone period &mdash; Carboniferous period
+&mdash; Old Red Sandstone period &mdash; "Rock and Spindle" near St.
+Andrews &mdash; Silurian period &mdash; Cambrian volcanic rocks.</p></div>
+
+
+<p><i><span class="smcap">Tertiary</span> Volcanic Rocks.&mdash;Auvergne.</i>&mdash;The extinct volcanos of Auvergne and
+Cantal in Central France seem to have commenced their eruptions in the
+Upper Eocene period, but to have been most active during the Miocene and
+Pliocene eras. I have already alluded to the grand succession of events, of
+which there is evidence in Auvergne since the last retreat of the sea (see
+<a href="#page178">p. 178.</a>).</p>
+
+<p>The earliest monuments of the tertiary period in that region are lacustrine
+deposits of great thickness (2. <a href="#img458">fig. 480.</a> <a href="#page424">p. 424.</a>), in the lowest
+conglomerates of which are rounded pebbles of quartz, mica-schist, granite,
+and other non-volcanic rocks, without the slightest intermixture of igneous
+products. To these conglomerates succeed argillaceous and calcareous marls
+and limestones (3. <a href="#img458">fig. 480.</a>) containing Upper Eocene shells and bones of
+mammalia, the higher beds of which sometimes alternate with volcanic tuff
+of contemporaneous origin. After the filling up or drainage of the ancient
+lakes, huge piles of trachytic and basaltic rocks, with volcanic breccias,
+accumulated to a thickness of several thousand feet, and were superimposed
+upon granite, or the contiguous lacustrine strata. The greater portion of
+these igneous rocks appear to have originated during the Miocene and
+Pliocene periods; and extinct quadrupeds of those eras, belonging to the
+genera Mastodon, Rhinoceros, and others, were buried in ashes and beds of
+alluvial sand and gravel, which owe their preservation to overspreading
+sheets of lava.</p>
+
+<p>In Auvergne the most ancient and conspicuous of the volcanic masses is Mont
+Dor, which rests immediately on the granitic rocks standing apart from the
+freshwater strata.<a name="FNanchor_AH_1" id="FNanchor_AH_1"></a><a href="#Footnote_AH_1" class="fnanchor">[422-A]</a> This great mountain rises suddenly to the height
+of several thousand feet above the surrounding platform, and retains the
+shape of a flattened and somewhat irregular cone, all the sides sloping
+more or less rapidly, until their inclination is gradually lost in the high
+plain around. This cone is composed of layers of scori�, pumice-stones, and
+their fine detritus, <span class="pagenum"><a id="page423"></a>[p.423]</span>with interposed beds of trachyte and basalt,
+which descend often in uninterrupted sheets, till they reach and spread
+themselves round the base of the mountain.<a name="FNanchor_AH_2" id="FNanchor_AH_2"></a><a href="#Footnote_AH_2" class="fnanchor">[423-A]</a> Conglomerates, also,
+composed of angular and rounded fragments of igneous rocks, are observed to
+alternate with the above; and the various masses are seen to dip off from
+the central axis, and to lie parallel to the sloping flanks of the
+mountain.</p>
+
+<p>The summit of Mont Dor terminates in seven or eight rocky peaks, where no
+regular crater can now be traced, but where we may easily imagine one to
+have existed, which may have been shattered by earthquakes, and have
+suffered degradation by aqueous agents. Originally, perhaps, like the
+highest crater of Etna, it may have formed an insignificant feature in the
+great pile, and may frequently have been destroyed and renovated.</p>
+
+<p>According to some geologists, this mountain, as well as Vesuvius, Etna, and
+all large volcanos, has derived its dome-like form not from the
+preponderance of eruptions from one or more central points, but from the
+upheaval of horizontal beds of lava and scori�. I have explained my reasons
+for objecting to this view at the close of Chap. XXIX., when speaking of
+Palma, and in the Principles of Geology.<a name="FNanchor_AH_3" id="FNanchor_AH_3"></a><a href="#Footnote_AH_3" class="fnanchor">[423-B]</a> The average inclination of
+the dome-shaped mass of Mont Dor is 8� 6', whereas in Mounts Loa and Kea,
+before mentioned, in the Sandwich Islands (see <a href="#img436">fig. 457.</a> <a href="#page394">p. 394.</a>), the
+flanks of which have been raised by recent lavas, we find from Mr. Dana's
+description that the one has a slope of 6� 30', the other of 7� 46'. We
+may, therefore, reasonably question whether there is any absolute necessity
+for supposing that the basaltic currents of the ancient French volcano were
+at first more horizontal than they are now. Nevertheless it is highly
+probable that during the long series of eruptions required to give rise to
+so vast a pile of volcanic matter, which is thickest at the summit or
+centre of the dome, some dislocation and upheaval took place; and during
+the distension of the mass, beds of lava and scori� may, in some places,
+have acquired a greater, in others a less inclination, than that which at
+first belonged to them.</p>
+
+<p>Respecting the age of the great mass of Mont Dor, we cannot come at present
+to any positive decision, because no organic remains have yet been found in
+the tuffs, except impressions of the leaves of trees of species not yet
+determined. We may certainly conclude, that the earliest eruptions were
+posterior in origin to those grits, and conglomerates of the freshwater
+formation of the Limagne, which contain no pebbles of volcanic rocks;
+while, on the other hand, some eruptions took place before the great lakes
+were drained; and others occurred after the desiccation of those lakes, and
+when deep valleys had already been excavated through freshwater strata.</p>
+
+<p>In the annexed section, I have endeavoured to explain the geological
+structure of a portion of Auvergne, which I re-examined in 1843.<a name="FNanchor_AH_4" id="FNanchor_AH_4"></a><a href="#Footnote_AH_4" class="fnanchor">[423-C]</a>
+<span class="pagenum"><a id="page424"></a>[p.424]</span>It may convey some idea to the reader of the long and complicated
+series of events, which have occurred in that country, since the first
+lacustrine strata (No. 2.) were deposited on the granite (No. 1.). The
+changes of which we have evidence are the more striking, because they imply
+great denudation, without there being any proofs of the intervention of the
+sea during the whole period. It will be seen that the upper freshwater beds
+(No. 3.), once formed in a lake, must have suffered great destruction
+before the excavation of the valleys of the Couze and Allier had begun. In
+these freshwater beds, Upper Eocene fossils, as described in Chap. XV.,
+have been found. The basaltic dike 4' is one of many examples of the
+intrusion of volcanic matter through the Eocene freshwater beds, and may
+have been of Upper Eocene or Miocene date, giving rise, when it reached the
+surface and overflowed, to such platforms of basalt, as often cap the
+tertiary hills in Auvergne, and one of which (4) is seen on Mont Perrier.</p>
+
+<a id="img458" name="img458"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 480.</p>
+<img src="images/img458.jpg" width="500" height="099" alt="" title="">
+<p>Section from the valley of the Couze at Nechers, through Mont Perrier
+and Issoire to the Valley of the Allier, and the Tour de Boulade, Auvergne.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li>10. Lava-current of Tartaret near its termination at Nechers.</li>
+<li>9. Bone-bed, red sandy clay under the lava of Tartaret.</li>
+<li>8. Bone-bed of the Tour de Boulade.</li>
+<li>7. Alluvium newer than No. 6.</li>
+<li>6. Alluvium with bones of hippopotamus.</li>
+<li>5 <i>c.</i> Trachytic breccia resembling 5 <i>a.</i></li>
+<li>5 <i>b.</i> Upper bone-bed of Perrier, gravel, &amp;c.</li>
+<li>5 <i>a.</i> Pumiceous breccia and conglomerate, angular
+masses of trachyte, quartz, pebbles, &amp;c.</li>
+<li>5. Lower bone-bed of Perrier, ochreous sand and gravel.</li>
+<li>4 <i>a.</i> Basaltic dyke.</li>
+<li>4. Basaltic platform.</li>
+<li>3. Upper freshwater beds, limestone, marl, gypsum, &amp;c.</li>
+<li>2. Lower freshwater formation, red clay, green sand, &amp;c.</li>
+<li>1. Granite.</li>
+</ul></div>
+
+<p>It not unfrequently happens that beds of gravel containing bones of extinct
+mammalia are detected under these very ancient sheets of basalt, as between
+No. 4. and the freshwater strata, No. 3., at <span class="smcap">A</span>, from which it is clear that
+the surface of 3 formed at that period the lowest level at which the waters
+then draining the country flowed. Next in age to this basaltic platform
+comes a patch of ochreous sand and gravel (No. 5.), containing many bones
+of quadrupeds. Upon this rests a pumiceous breccia and conglomerate, with
+angular masses of trachyte, and some quartz pebbles. This deposit is
+followed by 5 <i>b</i>, which is similar to 5, and 5 <i>c</i> similar to the
+trachytic breccia 5 <i>a</i>. These two breccias are supposed, from their
+similarity to others found on Mount Dor, to have descended from the flanks
+of that mountain during eruptions; and the interstratified alluvial
+deposits contain the remains of mastodon, rhinoceros, tapir, deer, beaver,
+and quadrupeds of other genera referable to about forty species, all of
+which are extinct. I formerly supposed them to belong to the same era as
+the Miocene faluns of Touraine; but, whether they may not rather be
+<span class="pagenum"><a id="page425"></a>[p.425]</span>ascribed to the older Pliocene epoch is a question which farther
+inquiries and comparisons must determine.</p>
+
+<p>Whatever be their date in the tertiary series, they are quadrupeds which
+inhabited the country when the formations 5 and 5 <i>c</i> originated. Probably
+they were drowned during floods, such as rush down the flanks of volcanos
+during eruptions, when great bodies of steam are emitted from the crater,
+or when, as we have seen, both on Etna and in Iceland in modern times,
+large masses of snow are suddenly melted by lava, causing a deluge of water
+to bear down fragments of igneous rocks mixed with mud, to the valleys and
+plains below.</p>
+
+<p>It will be seen that the valley of the Issoire, down which these ancient
+inundations swept, was first excavated at the expense of the formations 2,
+3, and 4, and then filled up by the masses 5 and 5 <i>c</i>, after which it was
+re-excavated before the more modern alluviums (Nos. 6. and 7.) were formed.
+In these again other fossil mammalia of distinct species have been detected
+by M. Bravard, the bones of an hippopotamus having been found among the
+rest.</p>
+
+<p>At length, when the valley of the Allier was eroded at Issoire down to its
+lowest level, a talus of angular fragments of basalt and freshwater
+limestone (No. 8.) was formed, called the bone-bed of the Tour de Boulade,
+from which a great many other mammalia have been collected by MM. Bravard
+and Pomel. In this assemblage the <i>Elephas primigenius</i>, <i>Rhinoceros
+tichorinus</i>, <i>Deer</i> (including rein-deer), <i>Equus</i>, <i>Bos</i>, <i>Antelope</i>,
+<i>Felis</i>, and <i>Canis</i>, were included. Even this deposit seems hardly to be
+the newest in the neighbourhood, for if we cross from the town of Issoire
+(see <a href="#img458">fig. 480.</a>) over Mont Perrier to the adjoining valley of the Couze, we
+find another bone-bed (No. 9.), overlaid by a current of lava (No. 10.).</p>
+
+<p>The history of this lava-current, which terminates a few hundred yards
+below the point No. 10., in the suburbs of the village of Nechers, is
+interesting. It forms a long narrow stripe more than 13 miles in length, at
+the bottom of the valley of the Couze, which flows out of a lake at the
+foot of Mont Dor. This lake is caused by a barrier thrown across the
+ancient channel of the Couze, consisting partly of the volcanic cone called
+the Puy de Tartaret, formed of loose scori�, from the base of which has
+issued the lava-current before mentioned. The materials of the dam which
+blocked up the river, and caused the Lac de Chambon, are also, in part,
+derived from a land-slip which may have happened at the time of the great
+eruption which formed the cone.</p>
+
+<p>This cone of Tartaret affords an impressive monument of the very different
+dates at which the igneous eruptions of Auvergne have happened; for it was
+evidently thrown up at the bottom of the existing valley, which is bounded
+by lofty precipices composed of sheets of ancient columnar trachyte and
+basalt, which once flowed at very high levels from Mont Dor.<a name="FNanchor_AH_5" id="FNanchor_AH_5"></a><a href="#Footnote_AH_5" class="fnanchor">[425-A]</a></p>
+
+<p><span class="pagenum"><a id="page426"></a>[p.426]</span>When we follow the course of the river Couze, from its source in
+the lake of Chambon, to the termination of the lava-current at Nechers, a
+distance of thirteen miles, we find that the torrent has in most places cut
+a deep channel through the lava, the lower portion of which is columnar. In
+some narrow gorges it has even had power to remove the entire mass of
+basaltic rock, though the work of erosion must have been very slow, as the
+basalt is tough and hard, and one column after another must have been
+undermined and reduced to pebbles, and then to sand. During the time
+required for this operation, the perishable cone of Tartaret, composed of
+sand and ashes, has stood uninjured, proving that no great flood or deluge
+can have passed over this region in the interval between the eruption of
+Tartaret and our own times.</p>
+
+<p>If we now return to the section (<a href="#img458">fig. 480.</a>), I may observe that the
+lava-current of Tartaret, which has diminished greatly in height and volume
+near its termination, presents here a steep and perpendicular face 25 feet
+in height towards the river. Beneath it is the alluvium No. 9., consisting
+of a red sandy clay, which must have covered the bottom of the valley when
+the current of melted rock flowed down. The bones found in this alluvium,
+which I obtained myself, consisted of a species of field-mouse, <i>Arvicola</i>,
+and the molar tooth of an extinct horse, <i>Equus fossilis</i>. The other
+species, obtained from the same bed, are referable to the genera <i>Sus</i>,
+<i>Bos</i>, <i>Cervus</i>, <i>Felis</i>, <i>Canis</i>, <i>Martes</i>, <i>Talpa</i>, <i>Sorex</i>, <i>Lepus</i>,
+<i>Sciurus</i>, <i>Mus</i>, and <i>Lagomys</i>, in all no less than forty-three species,
+all closely allied to recent animals, yet nearly all of them, according to
+M. Bravard, showing some points of difference, like those which Mr. Owen
+discovered in the case of the horse above alluded to. The bones, also, of a
+frog, snake, and lizard, and of several birds, were associated with the
+fossils before enumerated, and several recent land shells, such as
+<i>Cyclostoma elegans</i>, <i>Helix hortensis</i>, <i>H. nemoralis</i>, <i>H. lapicida</i>, and
+<i>Clausilia rugosa</i>. If the animals were drowned by floods, which
+accompanied the eruptions of the Puy de Tartaret, they would give an
+exceedingly modern geological date to that event, which must, in that case,
+have belonged to the Newer-Pliocene, or, perhaps, the Post-Pliocene period.
+That the current, which has issued from the Puy de Tartaret, may
+nevertheless be very ancient in reference to the events of human history,
+we may conclude, not only from the divergence of the mammiferous fauna from
+that of our day, but from the fact that a Roman bridge of such form and
+construction as continued in use down to the fifth century, but which may
+be older, is now seen at a place about a mile and a half from St. Nectaire.
+This ancient bridge spans the river Couze with two arches, each about 14
+feet wide. These arches spring from the lava of Tartaret, on both banks,
+showing that a ravine precisely like that now existing, had already been
+excavated by the river through that lava thirteen or fourteen centuries
+ago.</p>
+
+<p>In Central France there are several hundred minor cones, like that of
+Tartaret, a great number of which, like Monte Nuovo, near Naples, may have
+been principally due to a single eruption. Most of these <span class="pagenum"><a id="page427"></a>[p.427]</span>cones
+range in a linear direction from Auvergne to the Vivarais, and they were
+faithfully described so early as the year 1802, by M. de Montlosier. They
+have given rise chiefly to currents of basaltic lava. Those of Auvergne
+called the Monts Dome, placed on a granitic platform, form an irregular
+ridge (see <a href="#img415">fig. 436.</a>), about 18 miles in length, and 2 in breadth. They are
+usually truncated at the summit, where the crater is often preserved
+entire, the lava having issued from the base of the hill. But frequently
+the crater is broken down on one side, where the lava has flowed out. The
+hills are composed of loose scori�, blocks of lava, lapilli, and
+pozzuolana, with fragments of trachyte and granite.</p>
+
+<p><i>Puy de C�me.</i>&mdash;The Puy de C�me and its lava-current, near Clermont, may be
+mentioned as one of these minor volcanos. This conical hill rises from the
+granitic platform, at an angle of about 40�, to the height of more than 900
+feet. Its summit presents two distinct craters, one of them with a vertical
+depth of 250 feet. A stream of lava takes its rise at the western base of
+the hill, instead of issuing from either crater, and descends the granitic
+slope towards the present site of the town of Pont Gibaud. Thence it pours
+in a broad sheet down a steep declivity into the valley of the Sioule,
+filling the ancient river-channel for the distance of more than a mile. The
+Sioule, thus dispossessed of its bed, has worked out a fresh one between
+the lava and the granite of its western bank; and the excavation has
+disclosed, in one spot, a wall of columnar basalt about 50 feet
+high.<a name="FNanchor_AH_6" id="FNanchor_AH_6"></a><a href="#Footnote_AH_6" class="fnanchor">[427-A]</a></p>
+
+<p>The excavation of the ravine is still in progress, every winter some
+columns of basalt being undermined and carried down the channel of the
+river, and in the course of a few miles rolled to sand and pebbles.
+Meanwhile the cone of C�me remains stationary, its loose materials being
+protected by a dense vegetation, and the hill standing on a ridge not
+commanded by any higher ground whence floods of rain-water may descend.</p>
+
+<p><i>Puy Rouge.</i>&mdash;At another point, farther down the course of the Sioule, we
+find a second illustration of the same phenomenon in the Puy Rouge, a
+conical hill to the north of the village of Pranal. The cone is composed
+entirely of red and black scori�, tuff, and volcanic bombs. On its western
+side there is a worn-down crater, whence a powerful stream of lava has
+issued, and flowed into the valley of the Sioule. The river has since
+excavated a ravine through the lava and subjacent gneiss, to the depth of
+400 feet.</p>
+
+<p>On the upper part of the precipice forming the left side of this ravine, we
+see a great mass of black and red scoriaceous lava; below this a thin bed
+of gravel, evidently an ancient river-bed, now at an elevation of 50 feet
+above the channel of the Sioule. The gravel again rests upon gneiss, which
+has been eroded to the depth of 50 feet. It is quite evident in this case,
+that, while the basalt was gradually undermined and carried away by the
+force of running water, the cone whence the lava issued escaped
+destruction, because it stood <span class="pagenum"><a id="page428"></a>[p.428]</span>upon a platform of gneiss several
+hundred feet above the level of the valley in which the force of running
+water was exerted.</p>
+
+<p><i>Puy de Pariou.</i>&mdash;The brim of the crater of the Puy de Pariou, near
+Clermont, is so sharp, and has been so little blunted by time, that it
+scarcely affords room to stand upon. This and other cones in an equally
+remarkable state of integrity have stood, I conceive uninjured, not <i>in
+spite</i> of their loose porous nature, as might at first be naturally
+supposed, but in consequence of it. No rills can collect where all the rain
+is instantly absorbed by the sand and scori�, as is remarkably the case on
+Etna; and nothing but a waterspout breaking directly upon the Puy de Pariou
+could carry away a portion of the hill, so long as it is not rent or
+engulphed by earthquakes.</p>
+
+<p>Hence it is conceivable that even those cones which have the freshest
+aspect, and most perfect shape, may lay claim to very high antiquity. Dr.
+Daubeny has justly observed, that had any of these volcanos been in a state
+of activity in the age of Julius C�sar, that general, who encamped upon the
+plains of Auvergne, and laid siege to its principal city (Gergovia, near
+Clermont), could hardly have failed to notice them. Had there been any
+record of their eruptions in the time of Pliny or Sidonius Apollinaris, the
+one would scarcely have omitted to make mention of it in his Natural
+History, nor the other to introduce some allusion to it among the
+descriptions of this his native province. This poet's residence was on the
+borders of the Lake Aidat, which owed its very existence to the damming up
+of a river by one of the most modern lava-currents.<a name="FNanchor_AH_7" id="FNanchor_AH_7"></a><a href="#Footnote_AH_7" class="fnanchor">[428-A]</a></p>
+
+<p><i>Velay.</i>&mdash;The observations of M. Bertrand de Doue have not yet established
+that any of the most ancient volcanos of Velay were in action during the
+Eocene period. There are beds of gravel in Velay, as in Auvergne, covered
+by lava at different heights above the channels of the existing rivers. In
+the highest and most ancient of these alluviums the pebbles are exclusively
+of granitic rocks; but in the newer, which are found at lower levels, and
+which originated when the valleys had been cut to a greater depth, an
+intermixture of volcanic rocks has been observed.</p>
+
+<p>At St. Privat d'Allier a bed of volcanic scori� and tuff was discovered by
+Dr. Hibbert, inclosed between two sheets of basaltic lava; and in this tuff
+were found the bones of several quadrupeds, some of them adhering to masses
+of slaggy lava. Among other animals were <i>Rhinoceros leptorhinus</i>, <i>Hy�na
+spel�a</i>, and a species allied to the spotted hy�na of the Cape, together
+with four undetermined species of deer.<a name="FNanchor_AH_8" id="FNanchor_AH_8"></a><a href="#Footnote_AH_8" class="fnanchor">[428-B]</a> The manner of the occurrence
+of these bones reminds us of the published accounts of an eruption of
+Coseguina, 1835, in Central America (see <a href="#page399">p. 399.</a>), during which hot cinders
+and scori� fell and scorched to death great numbers of wild and domestic
+animals and birds.</p>
+
+<p><i>Plomb du Cantal.</i>&mdash;In regard to the age of the igneous rocks of <span class="pagenum"><a id="page429"></a>[p.429]</span>
+the Cantal, we can at present merely affirm, that they overlie the Eocene
+lacustrine strata of that country (see Map, <a href="#page179">p. 179.</a>). They form a great
+dome-shaped mass, having an average slope of only 4�, which has evidently
+been accumulated, like the cone of Etna, during a long series of eruptions.
+It is composed of trachytic, phonolitic, and basaltic lavas, tuffs, and
+conglomerates, or breccias, forming a mountain several thousand feet in
+height. Dikes also of phonolite, trachyte, and basalt are numerous,
+especially in the neighbourhood of the large cavity, probably once a
+crater, around which the loftiest summits of the Cantal are ranged
+circularly, few of them, except the Plomb du Cantal, rising far above the
+border or ridge of this supposed crater. A pyramidal hill, called the Puy
+Griou, occupies the middle of the cavity.<a name="FNanchor_AH_9" id="FNanchor_AH_9"></a><a href="#Footnote_AH_9" class="fnanchor">[429-A]</a> It is clear that the
+volcano of the Cantal broke out precisely on the site of the lacustrine
+deposit before described (<a href="#page188">p. 188.</a>), which had accumulated in a depression
+of a tract composed of micaceous schist. In the breccias, even to the very
+summit of the mountain, we find ejected masses of the freshwater beds, and
+sometimes fragments of flint, containing Eocene shells. Valleys radiate in
+all directions from the central heights of the mountain, increasing in size
+as they recede from those heights. Those of the Cer and Jourdanne, which
+are more than 20 miles in length, are of great depth, and lay open the
+geological structure of the mountain. No alternation of lavas with
+undisturbed Eocene strata has been observed, nor any tuffs containing
+freshwater shells, although some of these tuffs include fossil remains of
+terrestrial plants, said to imply several distinct restorations of the
+vegetation of the mountain in the intervals between great eruptions. On the
+northern side of the Plomb du Cantal, at La Vissiere, near Murat, is a
+spot, pointed out on the Map (<a href="#page179">p. 179.</a>), where freshwater limestone and marl
+are seen covered by a thickness of about 800 feet of volcanic rock. Shifts
+are here seen in the strata of limestone and marl.<a name="FNanchor_AH_10" id="FNanchor_AH_10"></a><a href="#Footnote_AH_10" class="fnanchor">[429-B]</a></p>
+
+<p><i>Eocene period.</i>&mdash;In treating of the lacustrine deposits of Central France,
+in the fifteenth chapter, it was stated that, in the arenaceous and pebbly
+group of the lacustrine basins of Auvergne, Cantal, and Velay, no volcanic
+pebbles had ever been detected, although massive piles of igneous rocks are
+now found in the immediate vicinity. As this observation has been confirmed
+by minute research, we are warranted in inferring that the volcanic
+eruptions had not commenced when the older subdivisions of the freshwater
+groups originated.</p>
+
+<p>In Cantal and Velay no decisive proofs have yet been brought to light that
+any of the igneous outbursts happened during the deposition of the
+freshwater strata; but there can be no doubt that in Auvergne some volcanic
+explosions took place before the drainage of the lakes, and at a time when
+the Upper Eocene species of animals and plants still flourished. Thus, for
+example, at Pont du Chateau, near Clermont, a section is seen in a
+precipice on the right bank of <span class="pagenum"><a id="page430"></a>[p.430]</span>the river Allier, in which beds of
+volcanic tuff alternate with a freshwater limestone, which is in some
+places pure, but in others spotted with fragments of volcanic matter, as if
+it were deposited while showers of sand and scori� were projected from a
+neighbouring vent.<a name="FNanchor_AH_11" id="FNanchor_AH_11"></a><a href="#Footnote_AH_11" class="fnanchor">[430-A]</a></p>
+
+<p>Another example occurs in the Puy de Marmont, near Veyres, where a
+freshwater marl alternates with volcanic tuff containing Eocene shells. The
+tuff or breccia in this locality is precisely such as is known to result
+from volcanic ashes falling into water, and subsiding together with ejected
+fragments of marl and other stratified rocks. These tuffs and marls are
+highly inclined, and traversed by a thick vein of basalt, which, as it
+rises in the hill, divides into two branches.</p>
+
+<p><i>Gergovia.</i>&mdash;The hill of Gergovia, near Clermont, affords a third example.
+I agree with MM. Dufr�noy and Jobert that there is no alternation here of a
+contemporaneous sheet of lava with freshwater strata, in the manner
+supposed by some other observers<a name="FNanchor_AH_12" id="FNanchor_AH_12"></a><a href="#Footnote_AH_12" class="fnanchor">[430-B]</a>; but the position and contents of
+some of the associated tuffs, prove them to have been derived from volcanic
+eruptions which occurred during the deposition of the lacustrine strata.</p>
+
+<a id="img459" name="img459"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 481.</p>
+<img src="images/img459.jpg" width="450" height="262" alt="" title="">
+<p>Hill of Gergovia.</p></div>
+
+<p>The bottom of the hill consists of slightly inclined beds of white and
+greenish marls, more than 300 feet in thickness, intersected by a dike of
+basalt, which may be studied in the ravine above the village of Merdogne.
+The dike here cuts through the marly strata at a considerable angle,
+producing, in general, great alteration and confusion in them for some
+distance from the point of contact. Above the white and green marls, a
+series of beds of limestone and marl, containing freshwater shells, are
+seen to alternate with volcanic tuff. In the lowest part of this division,
+beds of pure marl alternate with compact fissile tuff, resembling some of
+the subaqueous tuffs of Italy and Sicily called <i>peperinos</i>. Occasionally
+fragments of scori� are <span class="pagenum"><a id="page431"></a>[p.431]</span>visible in this rock. Still higher is
+seen another group of some thickness, consisting exclusively of tuff, upon
+which lie other marly strata intermixed with volcanic matter. Among the
+species of fossil shells which I found in these strata were <i>Melania
+inquinata</i>, a <i>Unio</i>, and a <i>Melanopsis</i>, but they were not sufficient to
+enable me to determine with precision the age of the formation.</p>
+
+<p>There are many points in Auvergne where igneous rocks have been forced by
+subsequent injection through clays and marly limestones, in such a manner
+that the whole has become blended in one confused and brecciated mass,
+between which and the basalt there is sometimes no very distinct line of
+demarcation. In the cavities of such mixed rocks we often find calcedony,
+and crystals of mesotype, stilbite, and arragonite. To formations of this
+class may belong some of the breccias immediately adjoining the dike in the
+hill of Gergovia; but it cannot be contended that the volcanic sand and
+scori� interstratified with the marls and limestones in the upper part of
+that hill were introduced, like the dike, subsequently, by intrusion from
+below. They must have been thrown down like sediment from water, and can
+only have resulted from igneous action, which was going on
+contemporaneously with the deposition of the lacustrine strata.</p>
+
+<p>The reader will bear in mind that this conclusion agrees well with the
+proofs, adverted to in the fifteenth chapter, of the abundance of silex,
+travertin, and gypsum precipitated when the upper lacustrine strata were
+formed; for these rocks are such as the waters of mineral and thermal
+springs might generate.</p>
+
+<p><i>Cretaceous period.</i>&mdash;Although we have no proof of volcanic rocks erupted
+in England during the deposition of the chalk and greensand, it would be an
+error to suppose that no theatres of igneous action existed in the
+cretaceous period. M. Virlet, in his account of the geology of the Morea,
+<a href="#page205">p. 205.</a>, has clearly shown that certain traps in Greece, called by him
+ophiolites, are of this date; as those, for example, which alternate
+conformably with cretaceous limestone and greensand between Kastri and
+Damala in the Morea. They consist in great part of diallage rocks and
+serpentine, and of an amygdaloid with calcareous kernels, and a base of
+serpentine.</p>
+
+<p>In certain parts of the Morea, the age of these volcanic rocks is
+established by the following proofs: first, the lithographic limestones of
+the Cretaceous era are cut through by trap, and then a conglomerate occurs,
+at Nauplia and other places, containing in its calcareous cement many
+well-known fossils of the chalk and greensand, together with pebbles formed
+of rolled pieces of the same ophiolite, which appear in the dikes above
+alluded to.</p>
+
+<p><i>Period of Oolite and Lias.</i>&mdash;Although the green and serpentinous trap
+rocks of the Morea belong chiefly to the Cretaceous era, as before
+mentioned, yet it seems that some eruptions of similar rocks began during
+the Oolitic period<a name="FNanchor_AH_13" id="FNanchor_AH_13"></a><a href="#Footnote_AH_13" class="fnanchor">[431-A]</a>; and it is probable, that a large part of
+<span class="pagenum"><a id="page432"></a>[p.432]</span>the trappean masses, called ophiolites in the Apennines, and
+associated with the limestone of that chain, are of corresponding age.</p>
+
+<p>That part of the volcanic rocks of the Hebrides, in our own country,
+originated contemporaneously with the Oolite which they traverse and
+overlie, has been ascertained by Prof. E. Forbes, in 1850.</p>
+
+<p><i>Trap of the New Red Sandstone period.</i>&mdash;In the southern part of
+Devonshire, trappean rocks are associated with New Red Sandstone, and,
+according to Sir H. De la Beche, have not been intruded subsequently into
+the sandstone, but were produced by contemporaneous volcanic action. Some
+beds of grit, mingled with ordinary red marl, resemble sands ejected from a
+crater; and in the stratified conglomerates occurring near Tiverton are
+many angular fragments of trap porphyry, some of them one or two tons in
+weight, intermingled with pebbles of other rocks. These angular fragments
+were probably thrown out from volcanic vents, and fell upon sedimentary
+matter then in the course of deposition.<a name="FNanchor_AH_14" id="FNanchor_AH_14"></a><a href="#Footnote_AH_14" class="fnanchor">[432-A]</a></p>
+
+<p><i>Carboniferous period.</i>&mdash;Two classes of contemporaneous trap rocks have
+been ascertained by Dr. Fleming to occur in the coal-field of the Forth in
+Scotland. The newest of these, connected with the higher series of
+coal-measures, is well exhibited along the shores of the Forth, in
+Fifeshire, where they consist of basalt with olivine, amygdaloid,
+greenstone, wack�, and tuff. They appear to have been erupted while the
+sedimentary strata were in a horizontal position, and to have suffered the
+same dislocations which those strata have subsequently undergone. In the
+volcanic tuffs of this age are found not only fragments of limestone,
+shale, flinty slate, and sandstone, but also pieces of coal.</p>
+
+<p>The other or older class of carboniferous traps are traced along the south
+margin of Stratheden, and constitute a ridge parallel with the Ochils, and
+extending from Stirling to near St. Andrews. They consist almost
+exclusively of greenstone, becoming, in a few instances, earthy and
+amygdaloidal. They are regularly interstratified with the sandstone, shale,
+and ironstone of the lower Coal-measures, and, on the East Lomond, with
+Mountain Limestone.</p>
+
+<p>I examined these trap rocks in 1838, in the cliffs south of St. Andrews,
+where they consist in great part of stratified tuffs, which are curved,
+vertical, and contorted, like the associated coal-measures. In the tuff I
+found fragments of carboniferous shale and limestone, and intersecting
+veins of greenstone. At one spot, about two miles from St. Andrews, the
+encroachment of the sea on the cliffs has isolated several masses of trap,
+one of which (<a href="#img460">fig. 482.</a>) is aptly called the "rock and spindle,"<a name="FNanchor_AH_15" id="FNanchor_AH_15"></a><a href="#Footnote_AH_15" class="fnanchor">[432-B]</a> for
+it consists of a pinnacle of tuff, which may be compared to a distaff, and
+near the base is a mass of columnar greenstone, in which the pillars
+radiate from a centre, and appear at a distance like the spokes of a wheel.
+The largest diameter of this <span class="pagenum"><a id="page433"></a>[p.433]</span>wheel is about twelve feet, and the
+polygonal terminations of the columns are seen round the circumference (or
+tire, as it were, of the wheel), as in the accompanying figure. I conceive
+this mass to be the extremity of a string or vein of greenstone, which
+penetrated the tuff. The prisms point in every direction, because they were
+surrounded on all sides by cooling surfaces, to which they always, arrange
+themselves at right angles, as before explained (<a href="#page385">p. 385.</a>).</p>
+
+<a id="img460" name="img460"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 482.</p>
+<img src="images/img460.jpg" width="350" height="570" alt="" title="">
+<p>Rock and Spindle, St. Andrews.</p>
+<ul class="martopm05 smaller leftal add1em min1em">
+<li><i>a.</i> Unstratified tuff.</li>
+<li><i>b.</i> Columnar greenstone.</li>
+<li><i>c.</i> Stratified tuff.</li>
+</ul></div>
+
+<a id="img461" name="img461"></a>
+<div class="floatleft smaller width125">
+<p class="martop2">Fig. 483.</p>
+<img src="images/img461.jpg" width="100" height="100" alt="" title="">
+<p>Columns of Greenstone, seen endwise.</p></div>
+
+<p><span class="pagenum"><a id="page434"></a>[p.434]</span>A trap dike was pointed out to me by Dr. Fleming, in the parish of
+Flisk, in the northern part of Fifeshire, which cuts through the grey
+sandstone and shale, forming the lowest part of the Old Red Sandstone. It
+may be traced for many miles, passing through the amygdaloidal and other
+traps of the hill called Normans Law. In its course it affords a good
+exemplification of the passage from the trappean into the plutonic, or
+highly crystalline texture. Professor Gustavus Rose, to whom I submitted
+specimens of this dike, finds the rock, which he calls dolerite, to consist
+of greenish black augite and Labrador felspar, the latter being the most
+abundant ingredient. A small quantity of magnetic iron, perhaps
+titaniferous, is also present. The result of this analysis is interesting,
+because both the ancient and modern lavas of Etna consist in like manner of
+augite, Labradorite, and titaniferous iron.</p>
+
+<p><i>Trap of the Old Red sandstone period.</i>&mdash;By referring to the section
+explanatory of the structure of Forfarshire, already given (<a href="#page48">p. 48.</a>), the
+reader will perceive that beds of conglomerate, No. 3., occur in the middle
+of the Old Red sandstone system, 1, 2, 3, 4. The pebbles in these
+conglomerates are sometimes composed of granitic and quartz rocks,
+sometimes exclusively of different varieties of trap, which, although
+purposely omitted in the above section, are often found either intruding
+themselves in amorphous masses and dikes into the old fossiliferous
+tilestones, No. 4., or alternating with them in conformable beds. All the
+different divisions of the red sandstone, 1, 2, 3, 4, are occasionally
+intersected by dikes, but they are very rare in Nos. 1. and 2., the upper
+members of the group consisting of red shale and red sandstone. These
+phenomena, which occur at the foot of the Grampians, are repeated in the
+Sidlaw Hills; and it appears that in this part of Scotland, volcanic
+eruptions were most frequent in the earlier part of the Old Red
+sandstone period.</p>
+
+<p>The trap rocks alluded to consist chiefly of felspathic porphyry and
+amygdaloid, the kernels of the latter being sometimes calcareous, often
+calcedonic, and forming beautiful agates. We meet also with claystone,
+clinkstone, greenstone, compact felspar, and tuff. Some of these rocks
+flowed as lavas over the bottom of the sea, and enveloped quartz pebbles
+which were lying there, so as to form conglomerates with a base of
+greenstone, as is seen in Lumley Den, in the Sidlaw Hills. On either side
+of the axis of this chain of hills (see section, <a href="#page48">p. 48.</a>), the beds of
+massive trap, and the tuffs composed of volcanic sand and ashes, dip
+regularly to the south-east or north-west, conformably with the shales and
+sandstones.</p>
+
+<p><i>Silurian period.</i>&mdash;It appears from the investigations of Sir R. Murchison
+in Shropshire, that when the lower Silurian strata of that county were
+accumulating, there were frequent volcanic eruptions beneath the sea; and
+the ashes and scori� then ejected gave rise to a peculiar kind of tufaceous
+sandstone or grit, dissimilar to the other rocks of the Silurian series,
+and only observable in places where syenitic and other trap rocks protrude.
+These tuffs occur on the flanks of the Wrekin and Caer Caradoc, and contain
+Silurian fossils, <span class="pagenum"><a id="page435"></a>[p.435]</span>such as casts of encrinites, trilobites, and
+mollusca. Although fossiliferous, the stone resembles a sandy claystone of
+the trap family.<a name="FNanchor_AH_16" id="FNanchor_AH_16"></a><a href="#Footnote_AH_16" class="fnanchor">[435-A]</a></p>
+
+<p>Thin layers of trap, only a few inches thick, alternate, in some parts of
+Shropshire and Montgomeryshire, with sedimentary strata of the lower
+Silurian system. This trap consists of slaty porphyry and granular felspar
+rock, the beds being traversed by joints like those in the associated
+sandstone, limestone, and shale, and having the same strike and dip.<a name="FNanchor_AH_17" id="FNanchor_AH_17"></a><a href="#Footnote_AH_17" class="fnanchor">[435-B]</a></p>
+
+<p>In Radnorshire there is an example of twelve bands of stratified trap,
+alternating with Silurian schists and flagstones, in a thickness of 350
+feet. The bedded traps consist of felspar-porphyry, clinkstone, and other
+varieties; and the interposed Llandeilo flags are of sandstone and shale,
+with trilobites and graptolites.<a name="FNanchor_AH_18" id="FNanchor_AH_18"></a><a href="#Footnote_AH_18" class="fnanchor">[435-C]</a></p>
+
+<p>The vast thickness of contemporaneous trappean rocks of lower Silurian date
+in North Wales, explored by our government surveyors, has been already
+alluded to.<a name="FNanchor_AH_19" id="FNanchor_AH_19"></a><a href="#Footnote_AH_19" class="fnanchor">[435-D]</a></p>
+
+<p><i>Cambrian volcanic rocks.</i>&mdash;Professor Sedgwick, in his account of the
+geology of Cumberland, has described various trap rocks which accompany the
+green slates of the Cambrian system, beneath all the rocks containing
+organic remains. Different felspathic and porphyritic rocks and greenstones
+occur, not only in dikes, but in conformable beds; and there is
+occasionally a passage from these igneous rocks to some of the green
+quartzose slates. Professor Sedgwick supposes these porphyries to have
+originated contemporaneously with the stratified chloritic slates, the
+materials of the slates having been supplied, in part at least, by
+submarine eruptions oftentimes repeated.<a name="FNanchor_AH_20" id="FNanchor_AH_20"></a><a href="#Footnote_AH_20" class="fnanchor">[435-E]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page436"></a>[p.436]</span>CHAPTER XXXIII.</h2>
+
+<h4>PLUTONIC ROCKS&mdash;GRANITE.</h4>
+
+<div class="blq1">
+<p class="indentm2">General aspect of granite &mdash; Decomposing into spherical masses &mdash;
+Rude columnar structure &mdash; Analogy and difference of volcanic and
+plutonic formations &mdash; Minerals in granite, and their arrangement
+&mdash; Graphic and porphyritic granite &mdash; Mutual penetration of
+crystals of quartz and felspar &mdash; Occasional minerals &mdash; Syenite
+&mdash; Syenitic, talcose, and schorly granites &mdash; Eurite &mdash;
+Passage of granite into trap &mdash; Examples near Christiania and in
+Aberdeenshire &mdash; Analogy in composition of trachyte and granite
+&mdash; Granite veins in Glen Tilt, Cornwall, the Valorsine, and other
+countries &mdash; Different composition of veins from main body of granite
+&mdash; Metalliferous veins in strata near their junction with granite
+&mdash; Apparent isolation of nodules of granite &mdash; Quartz veins
+&mdash; Whether plutonic rocks are ever overlying &mdash; Their exposure at
+the surface due to denudation.</p></div>
+
+
+<p><span class="smcap">The</span> plutonic rocks may be treated of next in order, as they are most nearly
+allied to the volcanic class already considered. I have described, in the
+first chapter, these plutonic rocks as the unstratified division of the
+crystalline or hypogene formations, and have stated that they differ from
+the volcanic rocks, not only by their more crystalline texture, but also by
+the absence of tuffs and breccias, which are the products of eruptions at
+the earth's surface, or beneath seas of inconsiderable depth. They differ
+also by the absence of pores or cellular cavities, to which the expansion
+of the entangled gases gives rise in ordinary lava. From these and other
+peculiarities it has been inferred, that the granites have been formed at
+considerable depths in the earth, and have cooled and crystallized slowly
+under great pressure, where the contained gases could not expand. The
+volcanic rocks, on the contrary, although they also have risen up from
+below, have cooled from a melted state more rapidly upon or near the
+surface. From this hypothesis of the great depth at which the granites
+originated, has been derived the name of "Plutonic rocks." The beginner
+will easily conceive that the influence of subterranean heat may extend
+downwards from the crater of every active volcano to a great depth below,
+perhaps several miles or leagues, and the effects which are produced deep
+in the bowels of the earth may, or rather must be, distinct; so that
+volcanic and plutonic rocks, each different in texture, and sometimes even
+in composition, may originate simultaneously, the one at the surface, the
+other far beneath it.</p>
+
+<p>By some writers, all the rocks now under consideration have been
+comprehended under the name of granite, which is, then, understood to
+embrace a large family of crystalline and compound rocks, usually found
+underlying all other formations; whereas we have seen that trap very
+commonly overlies strata of different ages. Granite often preserves a very
+uniform character throughout a wide range of territory, forming hills of a
+peculiar rounded form, usually clad with <span class="pagenum"><a id="page437"></a>[p.437]</span>a scanty vegetation. The
+surface of the rock is for the most part in a crumbling state, and the
+hills are often surmounted by piles of stones like the remains of a
+stratified mass, as in the annexed figure, and sometimes like heaps of
+boulders, for which they have been mistaken. The exterior of these stones,
+originally quadrangular, acquires a rounded form by the action of air and
+water, for the edges and angles waste away more rapidly than the sides. A
+similar spherical structure has already been described as characteristic of
+basalt and other volcanic formations, and it must be referred to analogous
+causes, as yet but imperfectly understood.</p>
+
+<a id="img462" name="img462"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 484.</p>
+<img src="images/img462.jpg" width="400" height="145" alt="" title="">
+<p>Mass of granite near the Sharp Tor, Cornwall.</p></div>
+
+<p>Although it is the general peculiarity of granite to assume no definite
+shapes, it is nevertheless occasionally subdivided by fissures, so as to
+assume a cuboidal, and even a columnar, structure. Examples of these
+appearances may be seen near the Land's End, in Cornwall. (See <a href="#img463">figure.</a>)</p>
+
+<a id="img463" name="img463"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 485.</p>
+<img src="images/img463.jpg" width="400" height="408" alt="" title="">
+<p>Granite having a cuboidal and rude columnar structure,
+Land's End, Cornwall.</p></div>
+
+<p>The plutonic formations also agree with the volcanic, in having veins or
+ramifications proceeding from central masses into the adjoining <span class="pagenum"><a id="page438"></a>[p.438]</span>
+rocks, and causing alterations in these last, which will be presently
+described. They also resemble trap in containing no organic remains; but
+they differ in being more uniform in texture, whole mountain masses of
+indefinite extent appearing to have originated under conditions precisely
+similar. They also differ in never being scoriaceous or amygdaloidal, and
+never forming a porphyry with an uncrystalline base, or alternating with
+tuffs. Nor do they form conglomerates, although there is sometimes an
+insensible passage from a fine to a coarse-grained granite, and
+occasionally patches of a fine texture are imbedded in a coarser variety.</p>
+
+<a id="img464" name="img464"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 486.</p>
+<img src="images/img464.jpg" width="350" height="155" alt="" title="">
+<p><span class="wosp05">Gneiss. (See</span> description, <a href="#page464">p. 464.</a>)</p></div>
+
+<p>Felspar, quartz, and mica are usually considered as the minerals essential
+to granite, the felspar being most abundant in quantity, and the proportion
+of quartz exceeding that of mica. These minerals are united in what is
+termed a confused crystallization; that is to say, there is no regular
+arrangement of the crystals in granite, as in gneiss (see <a href="#img464">fig. 486.</a>),
+except in the variety termed graphic granite, which occurs mostly in
+granitic veins. This variety is a compound of felspar and quartz, so
+arranged as to produce an imperfect laminar structure. The crystals of
+felspar appear to have been first formed, leaving between them the space
+now occupied by the darker-coloured quartz. This mineral, when a section is
+made at right angles to the alternate plates of felspar and quartz,
+presents broken lines, which have been compared to Hebrew characters.</p>
+
+<a id="img465" name="img465"></a>
+<div class="figcenter smaller width350">
+<img src="images/img465.jpg" width="350" height="154" alt="" title="">
+<p>Graphic granite.</p>
+<ul class="smaller martopm05 leftal add1em min1em">
+<li>Fig. 487. Section parallel to the lamin�.</li>
+<li>Fig. 488. Section transverse to the lamin�.</li>
+</ul></div>
+
+<p>As a general rule, quartz, in a compact or amorphous state, forms a
+vitreous mass, serving as the base in which felspar and mica have <span class="pagenum"><a id="page439"></a>[p.439]</span>
+crystallized; for although these minerals are much more fusible than silex,
+they have often imprinted their shapes upon the quartz. This fact,
+apparently so paradoxical, has given rise to much ingenious speculation. We
+should naturally have anticipated that, during the cooling of the mass, the
+flinty portion would be the first to consolidate; and that the different
+varieties of felspar, as well as garnets and tourmalines, being more easily
+liquefied by heat, would be the last. Precisely the reverse has taken place
+in the passage of most granitic aggregates from a fluid to a solid state,
+crystals of the more fusible minerals being found enveloped in hard,
+transparent, glassy quartz, which has often taken very faithful casts of
+each, so as to preserve even the microscopically minute striations on the
+surface of prisms of tourmaline. Various explanations of this phenomenon
+have been proposed by MM. de Beaumont, Fournet, and Durocher. They refer to
+M. Gaudin's experiments on the fusion of quartz, which show that silex, as
+it cools, has the property of remaining in a viscous state, whereas alumina
+never does. This "gelatinous flint" is supposed to retain a considerable
+degree of plasticity long after the granitic mixture has acquired a low
+temperature; and M. E. de Beaumont suggests, that electric action may
+prolong the duration of the viscosity of silex. Occasionally, however, we
+find the quartz and felspar mutually imprinting their forms on each other,
+affording evidence of the simultaneous crystallization of both.<a name="FNanchor_AI_1" id="FNanchor_AI_1"></a><a href="#Footnote_AI_1" class="fnanchor">[439-A]</a></p>
+
+<a id="img466" name="img466"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 489.</p>
+<img src="images/img466.jpg" width="400" height="200" alt="" title="">
+<p>Porphyritic <span class="wosp05">granite. Land's</span> End, Cornwall.</p></div>
+
+<p><i>Porphyritic granite.</i>&mdash;This name has been sometimes given to that variety
+in which large crystals of felspar, sometimes more than 3 inches in length,
+are scattered through an ordinary base of granite. An example of this
+texture may be seen in the granite of the Land's End, in Cornwall (<a href="#img466">fig.
+489.</a>). The two larger prismatic crystals in this drawing represent felspar,
+smaller crystals of which are also seen, similar in form, scattered through
+the base. In this base also appear black specks of mica, the crystals of
+which have a more or less perfect hexagonal outline. The remainder of the
+mass is quartz, the translucency of which is strongly contrasted to the
+opaqueness of the white felspar and black mica. But neither the
+transparency of the quartz, nor the silvery lustre of the mica, can be
+expressed in the engraving.</p>
+
+<p><span class="pagenum"><a id="page440"></a>[p.440]</span>The uniform mineral character of large masses of granite seems to
+indicate that large quantities of the component elements were thoroughly
+mixed up together, and then crystallized under precisely similar
+conditions. There are, however, many accidental, or "occasional," minerals,
+as they are termed, which belong to granite. Among these black schorl or
+tourmaline, actinolite, zircon, garnet, and fluor spar, are not uncommon;
+but they are too sparingly dispersed to modify the general aspect of the
+rock. They show, nevertheless, that the ingredients were not everywhere
+exactly the same; and a still greater variation may be traced in the
+ever-varying proportions of the felspar, quartz, and mica.</p>
+
+<p><i>Syenite.</i>&mdash;When hornblende is the substitute for mica, which is very
+commonly the case, the rock becomes Syenite: so called from the celebrated
+ancient quarries of Syene in Egypt. It has all the appearance of ordinary
+granite, except when mineralogically examined in hand specimens, and is
+fully entitled to rank as a geological member of the same plutonic family
+as granite. Syenite, however, after maintaining the granitic character
+throughout extensive regions, is not uncommonly found to lose its quartz,
+and to pass insensibly into syenitic greenstone, a rock of the trap family.
+Werner considered syenite as a binary compound of felspar and hornblende,
+and regarded quartz as merely one of its occasional minerals.</p>
+
+<p><i>Syenitic-granite.</i>&mdash;The quadruple compound of quartz, felspar, mica, and
+hornblende, may be so termed. This rock occurs in Scotland and in Guernsey.</p>
+
+<p><i>Talcose granite</i>, or Protogine of the French, is a mixture of felspar,
+quartz, and talc. It abounds in the Alps, and in some parts of Cornwall,
+producing by its decomposition the china clay, more than 12,000 tons of
+which are annually exported from that country for the potteries.<a name="FNanchor_AI_2" id="FNanchor_AI_2"></a><a href="#Footnote_AI_2" class="fnanchor">[440-A]</a></p>
+
+<p><i>Schorl rock, and schorly granite.</i>&mdash;The former of these is an aggregate of
+schorl, or tourmaline, and quartz. When felspar and mica are also present,
+it may be called schorly granite. This kind of granite is comparatively
+rare.</p>
+
+<p><i>Eurite.</i>&mdash;A rock in which all the ingredients of granite are blended into
+a finely granular mass. Crystals of quartz and mica are sometimes scattered
+through the base of Eurite.</p>
+
+<p><i>Pegmatite.</i>&mdash;A name given by French writers to a variety of granite; a
+granular mixture of quartz and felspar; frequent in granite veins; passes
+into graphic granite.</p>
+
+<p>All these granites pass into certain kinds of trap, a circumstance which
+affords one of many arguments in favour of what is now the prevailing
+opinion, that the granites are also of igneous origin. The contrast of the
+most crystalline form of granite, to that of the most common and earthy
+trap, is undoubtedly great; but each member of the volcanic class is
+capable of becoming porphyritic, and the base of the porphyry may be more
+and more crystalline, until the mass <span class="pagenum"><a id="page441"></a>[p.441]</span>passes to the kind of
+granite most nearly allied in mineral composition.</p>
+
+<p>The minerals which constitute alike the granitic and volcanic rocks
+consist, almost exclusively, of seven elements, namely, silica, alumina,
+magnesia, lime, soda, potash, and iron; and these may sometimes exist in
+about the same proportions in a porous lava, a compact trap, or a
+crystalline granite. It may perhaps be found, on farther examination&mdash;for
+on this subject we have yet much to learn&mdash;that the presence of these
+elements in certain proportions is more favourable than in others to their
+assuming a crystalline or true granitic structure; but it is also
+ascertained by experiment, that the same materials may, under different
+circumstances, form very different rocks. The same lava, for example, may
+be glassy, or scoriaceous, or stony, or porphyritic, according to the more
+or less rapid rate at which it cools; and some trachytes and
+syenitic-greenstones may doubtless form granite and syenite, if the
+crystallization take place slowly.</p>
+
+<p>It has also been suggested that the peculiar nature and structure of
+granite may be due to its retaining in it that water which is seen to
+escape from lavas when they cool slowly, and consolidate in the atmosphere.
+Boutigny's experiments have shown that melted matter, at a white heat,
+requires to have its temperature lowered before it can vapourize water; and
+such discoveries, if they fail to explain the manner in which granites have
+been formed, serve at least to remind us of the entire distinctness of the
+conditions under which plutonic and volcanic rocks must be produced.<a name="FNanchor_AI_3" id="FNanchor_AI_3"></a><a href="#Footnote_AI_3" class="fnanchor">[441-A]</a></p>
+
+<p>It would be easy to multiply examples and authorities to prove the
+gradation of the granitic into the trap rocks. On the western side of the
+fiord of Christiania, in Norway, there is a large district of trap, chiefly
+greenstone-porphyry, and syenitic-greenstone, resting on fossiliferous
+strata. To this, on its southern limit, succeeds a region equally extensive
+of syenite, the passage from the volcanic to the plutonic rock being so
+gradual that it is impossible to draw a line of demarcation between them.</p>
+
+<p>"The ordinary granite of Aberdeenshire," says Dr. MacCulloch, "is the usual
+ternary compound of quartz, felspar, and mica; but sometimes hornblende is
+substituted for the mica. But in many places a variety occurs which is
+composed simply of felspar and hornblende; and in examining more minutely
+this duplicate compound, it is observed in some places to assume a fine
+grain, and at length to become undistinguishable from the greenstones of
+the trap family. It also passes in the same uninterrupted manner into a
+basalt, and at length into a soft claystone, with a schistose tendency on
+exposure, in no respect differing from those of the trap islands of the
+western coast."<a name="FNanchor_AI_4" id="FNanchor_AI_4"></a><a href="#Footnote_AI_4" class="fnanchor">[441-B]</a> The same author mentions, that in Shetland, a
+granite composed of hornblende, mica, felspar, and quartz, graduates in an
+equally perfect manner into basalt.<a name="FNanchor_AI_5" id="FNanchor_AI_5"></a><a href="#Footnote_AI_5" class="fnanchor">[441-C]</a></p>
+
+<p><span class="pagenum"><a id="page442"></a>[p.442]</span>In Hungary there are varieties of trachyte, which, geologically
+speaking, are of modern origin, in which crystals, not only of mica, but of
+quartz, are common, together with felspar and hornblende. It is easy to
+conceive how such volcanic masses may, at a certain depth from the surface,
+pass downwards into granite.</p>
+
+<a id="img467" name="img467"></a>
+<div class="figcenter smaller width400">
+<img src="images/img467.jpg" width="400" height="212" alt="" title="">
+<p>Junction of granite and argillaceous schist in Glen <span class="wosp05">Tilt.
+(MacCulloch.)</span><a name="FNanchor_AI_6" id="FNanchor_AI_6"></a><a href="#Footnote_AI_6" class="fnanchor">[442-A]</a></p></div>
+
+<p>I have already hinted at the close analogy in the forms of certain granitic
+and trappean veins; and it will be found that strata penetrated by plutonic
+rocks have suffered changes very similar to those exhibited near the
+contact of volcanic dikes. Thus, in Glen Tilt, in Scotland, alternating
+strata of limestone and argillaceous schist come in contact with a mass of
+granite. The contact does not take place as might have been looked for, if
+the granite had been formed there before the strata were deposited, in
+which case the section would have appeared as in <a href="#img467">fig. 490.</a>; but the union
+is as represented in <a href="#img467">fig. 491.</a>, the undulating outline of the granite
+intersecting different strata, and occasionally intruding itself in
+tortuous veins into the beds of clay-slate and limestone, from which it
+differs so remarkably in composition. The limestone is sometimes changed in
+character by the proximity of the granitic mass or its veins, and acquires
+a more compact texture, like that of hornstone or chert, with a splintery
+fracture, effervescing feebly with acids.</p>
+
+<p>The annexed diagram (<a href="#img468">fig. 492.</a>) represents another junction, in the same
+district, where the granite sends forth so many veins as to reticulate the
+limestone and schist, the veins diminishing towards their termination to
+the thickness of a leaf of paper or a thread. In some places fragments of
+granite appear entangled, as it were, in the limestone, and are not visibly
+connected with any larger mass; while sometimes, on the other hand, a lump
+of the limestone is found in the midst of the granite. The ordinary colour
+of the limestone of Glen Tilt is lead blue, and its texture large-grained
+and highly crystalline; but where it approximates to the granite,
+particularly where it is penetrated by the smaller veins, the crystalline
+texture disappears, and it assumes an appearance exactly resembling that of
+hornstone. The associated argillaceous schist often passes into hornblende
+slate, where it approaches very near to the granite.<a name="FNanchor_AI_7" id="FNanchor_AI_7"></a><a href="#Footnote_AI_7" class="fnanchor">[442-B]</a></p>
+
+<span class="pagenum"><a id="page443"></a>[p.443]</span>
+<a id="img468" name="img468"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 492.</p>
+<img src="images/img468.jpg" width="450" height="437" alt="" title="">
+<p>Junction of granite and limestone in Glen <span class="wosp05">Tilt. (MacCulloch.)</span></p>
+<ul class="smaller martopm05 leftal add1em min1em">
+<li><i>a.</i> Granite.</li>
+<li><i>b.</i> Limestone.</li>
+<li><i>c.</i> Blue argillaceous schist.</li>
+</ul></div>
+
+<p>The conversion of the limestone in these and many other instances into a
+siliceous rock, effervescing slowly with acids, would be difficult of
+explanation, were it not ascertained that such limestones are always
+impure, containing grains of quartz, mica, or felspar disseminated through
+them. The elements of these minerals, when the rock has been subjected to
+great heat, may have been fused, and so spread more uniformly through the
+whole mass.</p>
+
+<a id="img469" name="img469"></a>
+<div class="figcenter smaller width200">
+<p>Fig. 493.</p>
+<img src="images/img469.jpg" width="200" height="260" alt="" title="">
+<p>Granite veins traversing clay slate. Table Mountain,
+Cape of Good Hope.<a name="FNanchor_AI_8" id="FNanchor_AI_8"></a><a href="#Footnote_AI_8" class="fnanchor">[443-A]</a></p></div>
+
+<p>In the plutonic, as in the volcanic rocks, there is every gradation from a
+tortuous vein to the most regular form of a dike, such as intersect the
+tuffs and lavas of Vesuvius and Etna. Dikes of granite may be seen, among
+other places, on the southern flank of Mount Battock, one of the Grampians,
+the opposite walls sometimes preserving an exact parallelism for a
+considerable distance.</p>
+
+<p>As a general rule, however, granite veins in all quarters of the globe are
+more sinuous in their course than those of trap. They present similar
+shapes at the most northern point of Scotland, and the southernmost
+extremity of Africa, as the annexed drawings will show.</p>
+
+<p><span class="pagenum"><a id="page444"></a>[p.444]</span>It is not uncommon for one set of granite veins to intersect
+another; and sometimes there are three sets, as in the environs of
+Heidelberg, where the granite on the banks of the river Necker is seen to
+consist of three varieties, differing in colour, grain, and various
+peculiarities of mineral composition. One of these, which is evidently the
+second in age, is seen to cut through an older granite; and another, still
+newer, traverses both the second and the first.</p>
+
+<p>In Shetland there are two kinds of granite. One of them, composed of
+hornblende, mica, felspar, and quartz, is of a dark colour, and is seen
+underlying gneiss. The other is a red granite, which penetrates the dark
+variety everywhere in veins.<a name="FNanchor_AI_9" id="FNanchor_AI_9"></a><a href="#Footnote_AI_9" class="fnanchor">[444-A]</a></p>
+
+<a id="img470" name="img470"></a>
+<div class="figcenter smaller width250">
+<p>Fig. 494.</p>
+<img src="images/img470.jpg" width="250" height="188" alt="" title="">
+<p>Granite veins traversing gneiss, Cape <span class="wosp05">Wrath.
+(MacCulloch.)</span><a name="FNanchor_AI_10" id="FNanchor_AI_10"></a><a href="#Footnote_AI_10" class="fnanchor">[444-B]</a></p></div>
+
+<a id="img471" name="img471"></a>
+<div class="figcenter smaller width450">
+<p class="martop2">Fig. 495.</p>
+<img src="images/img471.jpg" width="450" height="199" alt="" title="">
+<p>Granite veins traversing gneiss at Cape Wrath, in
+<span class="wosp05">Scotland. (MacCulloch.)</span></p></div>
+
+<p>The accompanying sketches will explain the manner in which granite veins
+often ramify and cut each other (<a href="#img470">figs. 494.</a> and <a href="#img471">495.</a>). They represent the
+manner in which the gneiss at Cape Wrath, in Sutherlandshire, is
+intersected by veins. Their light colour, strongly contrasted with that of
+the hornblende-schist, here associated with the gneiss, renders them very
+conspicuous.</p>
+
+<p>Granite very generally assumes a finer grain, and undergoes a change in
+mineral composition, in the veins which it sends into contiguous rocks.
+Thus, according to Professor Sedgwick, the main body of the Cornish granite
+is an aggregate of mica, quartz, and felspar; but the veins are sometimes
+without mica, being a granular aggregate of quartz and felspar. In other
+varieties quartz prevails to the almost entire exclusion both of felspar
+and mica; in others, the mica and quartz both disappear, and the vein is
+simply composed of white granular felspar.<a name="FNanchor_AI_11" id="FNanchor_AI_11"></a><a href="#Footnote_AI_11" class="fnanchor">[444-C]</a></p>
+
+<p><span class="pagenum"><a id="page445"></a>[p.445]</span><a href="#img472">Fig. 496.</a> is a sketch of a group of granite veins in Cornwall,
+given by Messrs. Von Oeynhausen and Von Dechen.<a name="FNanchor_AI_12" id="FNanchor_AI_12"></a><a href="#Footnote_AI_12" class="fnanchor">[445-A]</a> The main body of the
+granite here is of a porphyritic appearance, with large crystals of
+felspar; but in the veins it is fine-grained, and without these large
+crystals. The general height of the veins is from 16 to 20 feet, but some
+are much higher.</p>
+
+<a id="img472" name="img472"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 496.</p>
+<img src="images/img472.jpg" width="500" height="265" alt="" title="">
+<p>Granite veins passing through hornblende slate,
+Carnsilver Cove, Cornwall.</p></div>
+
+<p>In the Valorsine, a valley not far from Mont Blanc in Switzerland, an
+ordinary granite, consisting of felspar, quartz, and mica, sends forth
+veins into a talcose gneiss (or stratified protogine), and in some places
+lateral ramifications are thrown off from the principal veins at right
+angles (see <a href="#img473">fig. 497.</a>), the veins, especially the minute ones, being finer
+grained than the granite in mass.</p>
+
+<a id="img473" name="img473"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 497.</p>
+<img src="images/img473.jpg" width="350" height="191" alt="" title="">
+<p>Veins of granite in talcose <span class="wosp05">gneiss. (L.</span>
+A. Necker.)</p></div>
+
+<p>It is here remarked, that the schist and granite, as they approach, seem to
+exercise a reciprocal influence on each other, for both undergo a
+modification of mineral character. The granite, still remaining
+unstratified, becomes charged with green particles; and the talcose gneiss
+assumes a granitiform structure without losing its stratification.<a name="FNanchor_AI_13" id="FNanchor_AI_13"></a><a href="#Footnote_AI_13" class="fnanchor">[445-B]</a></p>
+
+<p><span class="pagenum"><a id="page446"></a>[p.446]</span>Professor Keilhau drew my attention to several localities in the
+country near Christiania, where the mineral character of gneiss appears to
+have been affected by a granite of much newer origin, for some distance
+from the point of contact. The gneiss, without losing its laminated
+structure, seems to have become charged with a larger quantity of felspar,
+and that of a redder colour, than the felspar usually belonging to the
+gneiss of Norway.</p>
+
+<p>Granite, syenite, and those porphyries which have a granitiform structure,
+in short all plutonic rocks, are frequently observed to contain metals, at
+or near their junction with stratified formations. On the other hand, the
+veins which traverse stratified rocks are, as a general law, more
+metalliferous near such junctions than in other positions. Hence it has
+been inferred that these metals may have been spread in a gaseous form
+through the fused mass, and that the contact of another rock, in a
+different state of temperature, or sometimes the existence of rents in
+other rocks in the vicinity, may have caused the sublimation of the
+metals.<a name="FNanchor_AI_14" id="FNanchor_AI_14"></a><a href="#Footnote_AI_14" class="fnanchor">[446-A]</a></p>
+
+<p>There are many instances, as at Markerud, near Christiania, in Norway,
+where the strike of the beds has not been deranged throughout a large area
+by the intrusion of granite, both in large masses and in veins. This fact
+is considered by some geologists to militate against the theory of the
+forcible injection of granite in a fluid state. But it may be stated in
+reply, that ramifying dikes of trap, which almost all now admit to have
+been once fluid, pass through the same fossiliferous strata, near
+Christiania, without deranging their strike or dip.<a name="FNanchor_AI_15" id="FNanchor_AI_15"></a><a href="#Footnote_AI_15" class="fnanchor">[446-B]</a></p>
+
+<a id="img474" name="img474"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 498.</p>
+<img src="images/img474.jpg" width="350" height="197" alt="" title="">
+<p>General view of junction of granite and schist of the
+<span class="wosp05">Valorsine. (L.</span> A. Necker.)</p></div>
+
+<p>The real or apparent isolation of large or small masses of granite detached
+from the main body, as at <i>a b</i>, <a href="#img474">fig. 498.</a>, and above, <a href="#img468">fig. 492.</a>, and <i>a</i>,
+<a href="#img473">fig. 497.</a>, has been thought by some writers to be irreconcilable with the
+doctrine usually taught respecting veins; but many of them may, in fact, be
+sections of root-shaped prolongations of granite; while, in other cases,
+they may in reality be detached portions of rock having the plutonic
+structure. For there may have been spots in the midst of the invaded
+strata, in which there was an assemblage of materials more fusible than the
+rest, or more fitted to combine readily into some form of granite.</p>
+
+<p><span class="pagenum"><a id="page447"></a>[p.447]</span>Veins of pure quartz are often found in granite, as in many
+stratified rocks, but they are not traceable, like veins of granite or
+trap, to large bodies of rock of similar composition. They appear to have
+been cracks, into which siliceous matter was infiltered. Such segregation,
+as it is called, can sometimes be shown to have clearly taken place long
+subsequently to the original consolidation of the containing rock. Thus,
+for example, in the gneiss of Tronstad Strand, near Drammen, in Norway, the
+annexed section is seen on the beach. It appears that the alternating
+strata of whitish granitiform gneiss, and black hornblende-schist, were
+first cut through by a greenstone dike, about 2<span class="smaller"><sup>1</sup>/<sub>2</sub></span> feet wide; then the
+crack <i>a b</i> passed through all these rocks, and was filled up with quartz.
+The opposite walls of the vein are in some parts incrusted with transparent
+crystals of quartz, the middle of the vein being filled up with common
+opaque white quartz.</p>
+
+<a id="img475" name="img475"></a>
+<div class="figcenter smaller width300">
+<p>Fig. 499.</p>
+<img src="images/img475.jpg" width="300" height="196" alt="" title="">
+<p><i>a, b.</i> Quartz vein passing through gneiss and
+greenstone, Tronstad Strand, near Christiania.</p></div>
+
+<a id="img476" name="img476"></a>
+<div class="figcenter smaller width350">
+<p class="martop2">Fig. 500.</p>
+<img src="images/img476.jpg" width="350" height="101" alt="" title="">
+<p>Euritic porphyry alternating with primary
+fossiliferous strata, near Christiania.</p></div>
+
+<p>We have seen that the volcanic formations have been called overlying,
+because they not only penetrate others, but spread over them. Mr. Necker
+has proposed to call the granites the underlying igneous rocks, and the
+distinction here indicated is highly characteristic. It was indeed supposed
+by some of the earlier observers, that the granite of Christiania, in
+Norway, was intercalated in mountain masses between the primary or
+paleozoic strata of that country, so as to overlie fossiliferous shale and
+limestone. But although the granite sends veins into these fossiliferous
+rocks, and is decidedly posterior in origin, its actual superposition in
+mass has been disproved by Professor Keilhau, whose observations on this
+controverted point I had opportunities in 1837 of verifying. There are,
+however, on a smaller scale, certain beds of euritic porphyry, some a few
+feet, others many yards in thickness, which pass into granite, and deserve
+perhaps to be classed as plutonic rather than trappean rocks, which may
+truly be described as interposed conformably between fossiliferous strata,
+as the porphyries (<i>a c</i>, <a href="#img476">fig. 500.</a>), which divide the bituminous shales
+and argillaceous limestones, <i>f f</i>. But some of these same porphyries are
+partially unconformable, as <i>b</i>, and may lead us to suspect that the others
+also, <span class="pagenum"><a id="page448"></a>[p.448]</span>notwithstanding their appearance of interstratification,
+have been forcibly injected. Some of the porphyritic rocks above mentioned
+are highly quartzose, others very felspathic. In proportion as the masses
+are more voluminous, they become more granitic in their texture, less
+conformable, and even begin to send forth veins into contiguous strata. In
+a word, we have here a beautiful illustration of the intermediate
+gradations between volcanic and plutonic rocks, not only in their
+mineralogical composition and structure, but also in their relations of
+position to associated formations. If the term overlying can in this
+instance be applied to a plutonic rock, it is only in proportion as that
+rock begins to acquire a trappean aspect.</p>
+
+<p>It has been already hinted that the heat, which in every active volcano
+extends downwards to indefinite depths, must produce simultaneously very
+different effects near the surface, and far below it; and we cannot suppose
+that rocks resulting from the crystallizing of fused matter under a
+pressure of several thousand feet, much less miles, of the earth's crust
+can resemble those formed at or near the surface. Hence the production at
+great depths of a class of rocks analogous to the volcanic, and yet
+differing in many particulars, might almost have been predicted, even had
+we no plutonic formations to account for. How well these agree, both in
+their positive and negative characters, with the theory of their deep
+subterranean origin, the student will be able to judge by considering the
+descriptions already given.</p>
+
+<p>It has, however, been objected, that if the granitic and volcanic rocks
+were simply different parts of one great series, we ought to find in
+mountain chains volcanic dikes passing upwards into lava, and downwards
+into granite. But we may answer, that our vertical sections are usually of
+small extent; and if we find in certain places a transition from trap to
+porous lava, and in others a passage from granite to trap, it is as much as
+could be expected of this evidence.</p>
+
+<p>The prodigious extent of denudation which has been already demonstrated to
+have occurred at former periods, will reconcile the student to the belief
+that crystalline rocks of high antiquity, although deep in the earth's
+crust when originally formed, may have become uncovered and exposed at the
+surface. Their actual elevation above the sea may be referred to the same
+causes to which we have attributed the upheaval of marine strata, even to
+the summits of some mountain chains. But to these and other topics, I shall
+revert when speaking, in the next chapter, of the relative ages of
+different masses of granite.</p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page449"></a>[p.449]</span>CHAPTER XXXIV.</h2>
+
+<h4>ON THE DIFFERENT AGES OF THE PLUTONIC ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Difficulty in ascertaining the precise age of a plutonic rock &mdash; Test
+of age by relative position &mdash; Test by intrusion and alteration
+&mdash; Test by mineral composition &mdash; Test by included fragments
+&mdash; Recent and Pliocene plutonic rocks, why invisible &mdash; Tertiary
+plutonic rocks in the Andes &mdash; Granite altering Cretaceous rocks
+&mdash; Granite altering Lias in the Alps and in Skye &mdash; Granite of
+Dartmoor altering Carboniferous strata &mdash; Granite of the Old Red
+Sandstone period &mdash; Syenite altering Silurian strata in Norway &mdash;
+Blending of the same with gneiss &mdash; Most ancient plutonic rocks
+&mdash; Granite protruded in a solid form &mdash; On the probable age of
+the granites of Arran, in Scotland.</p></div>
+
+
+<p><span class="smcap">When</span> we adopt the igneous theory of granite, as explained in the last
+chapter, and believe that different plutonic rocks have originated at
+successive periods beneath the surface of the planet, we must be prepared
+to encounter greater difficulty in ascertaining the precise age of such
+rocks, than in the case of volcanic and fossiliferous formations. We must
+bear in mind, that the evidence of the age of each contemporaneous volcanic
+rock was derived, either from lavas poured out upon the ancient surface,
+whether in the sea or in the atmosphere, or from tuffs and conglomerates,
+also deposited at the surface, and either containing organic remains
+themselves, or intercalated between strata containing fossils. But all
+these tests fail when we endeavour to fix the chronology of a rock which
+has crystallized from a state of fusion in the bowels of the earth. In that
+case, we are reduced to the following tests; 1st, relative position; 2dly,
+intrusion, and alteration of the rocks in contact; 3dly, mineral
+characters; 4thly, included fragments.</p>
+
+<p><i>Test of age by relative position.</i>&mdash;Unaltered fossiliferous strata of
+every age are met with reposing immediately on plutonic rocks; as at
+Christiania, in Norway, where the Newer Pliocene deposits rest on granite;
+in Auvergne, where the freshwater Eocene strata, and at Heidelberg, on the
+Rhine, where the New Red sandstone, occupy a similar place. In all these,
+and similar instances, inferiority in position is connected with the
+superior antiquity of granite. The crystalline rock was solid before the
+sedimentary beds were superimposed, and the latter usually contain in them
+rounded pebbles of the subjacent granite.</p>
+
+<p><i>Test by intrusion and alteration.</i>&mdash;But when plutonic rocks send veins
+into strata, and alter them near the point of contact, in the manner before
+described (<a href="#page442">p. 442.</a>), it is clear that, like intrusive traps, they are newer
+than the strata which they invade and alter. Examples of the application of
+this test will be given in the sequel.</p>
+
+<p><i>Test by mineral composition.</i>&mdash;Notwithstanding a general uniformity in the
+aspect of plutonic rocks, we have seen in the last <span class="pagenum"><a id="page450"></a>[p.450]</span>chapter that
+there are many varieties, such as Syenite, Talcose granite, and others. One
+of these varieties is sometimes found exclusively prevailing throughout an
+extensive region, where it preserves a homogeneous character; so that
+having ascertained its relative age in one place, we can easily recognize
+its identity in others, and thus determine from a single section the
+chronological relations of large mountain masses. Having observed, for
+example, that the syenitic granite of Norway, in which the mineral called
+zircon abounds, has altered the Silurian strata wherever it is in contact,
+we do not hesitate to refer other masses of the same zircon-syenite in the
+south of Norway to the same era.</p>
+
+<p>Some have imagined that the age of different granites might, to a great
+extent, be determined by their mineral characters alone; syenite, for
+instance, or granite with hornblende, being more modern than common or
+micaceous granite. But modern investigations have proved these
+generalizations to have been premature. The syenitic granite of Norway
+already alluded to may be of the same age as the Silurian strata, which it
+traverses and alters, or may belong to the Old Red sandstone period;
+whereas the granite of Dartmoor, although consisting of mica, quartz, and
+felspar, is newer than the coal. (See <a href="#page456">p. 456.</a>)</p>
+
+<p><i>Test by included fragments.</i>&mdash;This criterion can rarely be of much
+importance, because the fragments involved in granite are usually so much
+altered, that they cannot be referred with certainty to the rocks whence
+they were derived. In the White Mountains, in North America, according to
+Professor Hubbard, a granite vein traversing granite, contains fragments of
+slate and trap, which must have fallen into the fissure when the fused
+materials of the vein were injected from below<a name="FNanchor_AJ_1" id="FNanchor_AJ_1"></a><a href="#Footnote_AJ_1" class="fnanchor">[450-A]</a>, and thus the granite
+is shown to be newer than certain superficial slaty and trappean
+formations.</p>
+
+<p><i>Recent and Pliocene plutonic rocks, why invisible.</i>&mdash;The explanation
+already given in the 29th and in the last chapter, of the probable relation
+of the plutonic to the volcanic formations, will naturally lead the reader
+to infer, that rocks of the one class can never be produced at or near the
+surface without some members of the other being formed below
+simultaneously, or soon afterwards. It is not uncommon for lava-streams to
+require more than ten years to cool in the open air; and where they are of
+great depth, a much longer period. The melted matter poured from Jorullo,
+in Mexico, in the year 1759, which accumulated in some places to the height
+of 550 feet, was found to retain a high temperature half a century after
+the eruption.<a name="FNanchor_AJ_2" id="FNanchor_AJ_2"></a><a href="#Footnote_AJ_2" class="fnanchor">[450-B]</a> We may conceive, therefore, that great masses of
+subterranean lava may remain in a red-hot or incandescent state in the
+volcanic foci for immense periods, and the process of refrigeration may be
+extremely gradual. Sometimes, indeed, this process may be retarded for an
+indefinite period, by the accession of fresh supplies of heat; for we find
+that the lava in the crater of Stromboli, one of the <span class="pagenum"><a id="page451"></a>[p.451]</span>Lipari
+Islands, has been in a state of constant ebullition for the last two
+thousand years; and we may suppose this fluid mass to communicate with some
+caldron or reservoir of fused matter below. In the Isle of Bourbon, also,
+where there has been an emission of lava once in every two years for a long
+period, the lava below can scarcely fail to have been permanently in a
+state of liquefaction. If then it be a reasonable conjecture, that about
+2000 volcanic eruptions occur in the course of every century, either above
+the waters of the sea or beneath them<a name="FNanchor_AJ_3" id="FNanchor_AJ_3"></a><a href="#Footnote_AJ_3" class="fnanchor">[451-A]</a>, it will follow, that the
+quantity of plutonic rock generated, or in progress during the Recent
+epoch, must already have been considerable.</p>
+
+<p>But as the plutonic rocks originate at some depth in the earth's crust,
+they can only be rendered accessible to human observation, by subsequent
+upheaval and denudation. Between the period when a plutonic rock
+crystallizes in the subterranean regions, and the era of its protrusion at
+any single point of the surface, one or two geological periods must usually
+intervene. Hence, we must not expect to find the Recent or Newer Pliocene
+granites laid open to view, unless we are prepared to assume that
+sufficient time has elapsed since the commencement of the Newer Pliocene
+period for great upheaval and denudation. A plutonic rock, therefore, must,
+in general, be of considerable antiquity relatively to the fossiliferous
+and volcanic formations, before it becomes extensively visible. As we know
+that the upheaval of land has been sometimes accompanied in South America
+by volcanic eruptions and the emission of lava, we may conceive the more
+ancient plutonic rocks to be forced upwards to the surface by the newer
+rocks of the same class formed successively below,&mdash;subterposition in the
+plutonic, like superposition in the sedimentary rocks, being usually
+characteristic of a newer origin.</p>
+
+<p>In the accompanying diagram (<a href="#img477">fig. 501.</a>), an attempt is made to show the
+inverted order in which sedimentary and plutonic formations may occur in
+the earth's crust.</p>
+
+<p>The oldest plutonic rock, No. I., has been upheaved at successive periods
+until it has become exposed to view in a mountain-chain. This protrusion of
+No. I. has been caused by the igneous agency which produced the newer
+plutonic rocks Nos. II. III. and IV. Part of the primary fossiliferous
+strata, No. 1., have also been raised to the surface by the same gradual
+process. It will be observed that the Recent <i>strata</i> No. 4., and the
+Recent <i>granite</i> or plutonic rock No. IV., are the most remote from each
+other in position, although of contemporaneous date. According to this
+hypothesis, the convulsions of many periods will be required before
+<i>Recent</i> granite will be upraised so as to form the highest ridges and
+central axes of mountain-chains. During that time the <i>Recent</i> strata No.
+4. might be covered by a great many newer sedimentary formations.</p>
+
+<a id="img477" name="img477"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 501.</p>
+<img src="images/img477.jpg" width="500" height="167" alt="" title="">
+<p>Diagram showing the relative position which the plutonic and
+sedimentary formations of different ages may occupy.</p>
+
+<table  class="martopm05" border="0" cellpadding="2" summary="PLUTONIC AND SEDIMENTARY FORMATIONS OF DIFFERENT AGES.">
+<colgroup>
+    <col width="20%">
+    <col width="30%">
+    <col width="50%">
+</colgroup>
+<tr>
+  <td class="td-right">I. </td>
+  <td class="td-left">Primary plutonic.</td>
+  <td class="td-left">4. Recent strata.</td>
+</tr>
+
+<tr>
+  <td class="td-right">II.</td>
+  <td class="td-left">Secondary plutonic.</td>
+  <td class="td-left">3. Tertiary strata.</td>
+</tr>
+
+<tr>
+  <td class="td-right">III.</td>
+  <td class="td-left">Tertiary plutonic.</td>
+  <td class="td-left">2. Secondary strata.</td>
+</tr>
+
+<tr>
+  <td class="td-right">IV.</td>
+  <td class="td-left">Recent plutonic.</td>
+  <td class="td-left">1. Primary fossiliferous strata.</td>
+</tr>
+</table>
+
+<p class="martopm05">The metamorphic rocks are not indicated in this diagram; but the student
+will infer, from what has been said in Chap. XXXII., that some portions of
+the stratified formations Nos. 1. and 2. invaded by granite will have
+become metamorphic.</p></div>
+
+<p><i>Eocene granite and plutonic rocks.</i>&mdash;In a former part of this volume (<a href="#page205">p.
+205.</a>), the great nummulitic formation of the Alps and <span class="pagenum"><a id="page453"></a>[p.453]</span>Pyrenees
+was referred to the Eocene period, and it follows that those vast movements
+which have raised fossiliferous rocks from the level of the sea to the
+height of more than 10,000 feet above its level have taken place since the
+commencement of the tertiary epoch. Here, therefore, if anywhere, we might
+expect to find hypogene formations of Eocene date breaking out in the
+central axis or most disturbed region of the loftiest chain in Europe.
+Accordingly, in the Swiss Alps, even the <i>flysch</i>, or upper portion of the
+nummulitic series, has been occasionally invaded by plutonic rocks, and
+converted into crystalline schists of the hypogene class. There can be
+little doubt that even the talcose granite of Mont Blanc itself has been in
+a fused or pasty state since the <i>flysch</i> was deposited at the bottom of
+the sea; and the question as to its age is not so much whether it be a
+secondary or tertiary granite, as whether it should be assigned to the
+Eocene or Miocene epoch.</p>
+
+<p>Great upheaving movements have been experienced in the region of the Andes,
+during the Post-Pliocene period. In some part, therefore, of this chain, we
+may expect to discover tertiary plutonic rocks laid open to view. What we
+already know of the structure of the Chilian Andes seems to realize this
+expectation. In a transverse section, examined by Mr. Darwin, between
+Valparaiso and Mendoza, the Cordillera was found to consist of two separate
+and parallel chains, formed of sedimentary rocks of different ages, the
+strata in both resting on plutonic rocks, by which they have been altered.
+In the western or oldest range, called the Peuquenes, are black calcareous
+clay-slates, rising to the height of nearly 14,000 feet above the sea, in
+which are shells of the genera <i>Gryph�a</i>, <i>Turritella</i>, <i>Terebratula</i>, and
+<i>Ammonite</i>. These rocks are supposed to be of the age of the central parts
+of the secondary series of Europe. They are penetrated and altered by dikes
+and mountain masses of a plutonic rock, which has the texture of ordinary
+granite, but rarely contains quartz, being a compound of albite and
+hornblende.</p>
+
+<p>The second or eastern chain consists chiefly of sandstones and
+conglomerates, of vast thickness, the materials of which are derived from
+the ruins of the western chain. The pebbles of the conglomerates are, for
+the most part, rounded fragments of the fossiliferous slates before
+mentioned. The resemblance of the whole series to certain tertiary deposits
+on the shores of the Pacific, not only in mineral character, but in the
+imbedded lignite and silicified woods, leads to the conjecture that they
+also are tertiary. Yet these strata are not only associated with trap rocks
+and volcanic tuffs, but are also altered by a granite consisting of quartz,
+felspar, and talc. They are traversed, moreover, by dikes of the same
+granite, and by numerous veins of iron, copper, arsenic, silver, and gold;
+all of which can be traced to the underlying granite.<a name="FNanchor_AJ_4" id="FNanchor_AJ_4"></a><a href="#Footnote_AJ_4" class="fnanchor">[453-A]</a> We have,
+therefore, strong ground to presume that the plutonic rock, here exposed on
+a large scale in the Chilian Andes, is of later date than certain tertiary
+formations.</p>
+
+<p><span class="pagenum"><a id="page454"></a>[p.454]</span>But the theory adopted in this work of the subterranean origin of
+the hypogene formations would be untenable, if the supposed fact here
+alluded to, of the appearance of tertiary granite at the surface was not a
+rare exception to the general rule. A considerable lapse of time must
+intervene between the formation in the nether regions of plutonic and
+metamorphic rocks, and their emergence at the surface. For a long series of
+subterranean movements must occur before such rocks can be uplifted into
+the atmosphere or the ocean; and, before they can be rendered visible to
+man, some strata which previously covered them must usually have been
+stripped off by denudation.</p>
+
+<p>We know that in the Bay of Bai�, in 1538, in Cutch in 1819, and on several
+occasions in Peru and Chili, since the commencement of the present century,
+the permanent upheaval or subsidence of land has been accompanied by the
+simultaneous emission of lava at one or more points in the same volcanic
+region. From these and other examples it may be inferred that the rising or
+sinking of the earth's crust, operations by which sea is converted into
+land, and land into sea, are a part only of the consequences of
+subterranean igneous action. It can scarcely be doubted that this action
+consists, in a great degree, of the baking, and occasionally the
+liquefaction, of rocks, causing them to assume, in some cases a larger, in
+others a smaller volume than before the application of heat. It consists
+also in the generation of gases, and their expansion by heat, and the
+injection of liquid matter into rents formed in superincumbent rocks. The
+prodigious scale on which these subterranean causes have operated in Sicily
+since the deposition of the Newer Pliocene strata will be appreciated, when
+we remember that throughout half the surface of that island such strata are
+met with, raised to the height of from 50 to that of 2000 and even 3000
+feet above the level of the sea. In the same island also the older rocks
+which are contiguous to these marine tertiary strata must have undergone,
+within the same period, a similar amount of upheaval.</p>
+
+<p>The like observations may be extended to nearly the whole of Europe, for,
+since the commencement of the Eocene period, the entire European area,
+including some of the central and very lofty portions of the Alps
+themselves, as I have elsewhere shown<a name="FNanchor_AJ_5" id="FNanchor_AJ_5"></a><a href="#Footnote_AJ_5" class="fnanchor">[454-A]</a>, has, with the exception of a
+few districts, emerged from the deep to its present altitude; and even
+those tracts, which were already dry land before the Eocene era, have
+almost everywhere acquired additional height. A large amount of subsidence
+has also occurred during the same period, so that the extent of the
+subterranean spaces which have either become the receptacles of sunken
+fragments of the earth's crust, or have been rendered capable of supporting
+other fragments at a much greater height than before, must be so great that
+they probably equal, if not exceed in volume, the entire continent of
+Europe. We are entitled, therefore, to ask what amount of change of
+equivalent importance <span class="pagenum"><a id="page455"></a>[p.455]</span>can be proved to have occurred in the
+earth's crust within an equal quantity of time anterior to the Eocene
+epoch. They who contend for the more intense energy of subterranean causes
+in the remoter eras of the earth's history, may find it more difficult to
+give an answer to this question than they anticipated.</p>
+
+<p>The principal effect of volcanic action in the nether regions, during the
+tertiary period, seems to have consisted in the upheaval to the surface of
+hypogene formations of an age anterior to the carboniferous. The repetition
+of another series of movements, of equal violence, might upraise the
+plutonic and metamorphic rocks of many secondary periods; and if the same
+force should still continue to act, the next convulsions might bring up to
+the day the <i>tertiary</i> and <i>recent</i> hypogene rocks. In the course of such
+changes many of the existing sedimentary strata would suffer greatly by
+denudation, others might assume a metamorphic structure, or become melted
+down into plutonic and volcanic rocks. Meanwhile the deposition of a vast
+thickness of new strata would not fail to take place during the upheaval
+and partial destruction of the older rocks. But I must refer the reader to
+the last chapter but one of this volume for a fuller explanation of these
+views.</p>
+
+<a id="img478" name="img478"></a>
+<div class="floatleft smaller width250">
+<p>Fig. 502.</p>
+<img src="images/img478.jpg" width="250" height="134" alt="" title=""></div>
+
+<p><i>Cretaceous period.</i>&mdash;It will be shown in the next chapter that chalk, as
+well as lias, has been altered by granite in the eastern Pyrenees. Whether
+such granite be cretaceous or tertiary cannot easily be decided. Suppose
+<i>b, c, d</i>, to be three members of the Cretaceous series, the lowest of
+which, <i>b</i>, has been altered by the granite A, the modifying influence not
+having extended so far as <i>c</i>, or having but slightly affected its lowest
+beds. Now it can rarely be possible for the geologist to decide whether the
+beds d existed at the time of the intrusion of A, and alteration of <i>b</i> and
+<i>c</i>, or whether they were subsequently thrown down upon <i>c</i>.</p>
+
+<p>As some Cretaceous rocks, however, have been raised to the height of more
+than 9000 feet in the Pyrenees, we must not assume that plutonic formations
+of the same age may not have been brought up and exposed by denudation, at
+the height of 2000 or 3000 feet on the flanks of that chain.</p>
+
+<p><i>Period of Oolite and Lias.</i>&mdash;In the department of the Hautes Alpes, in
+France, near Vizille, M. Elie de Beaumont traced a black argillaceous
+limestone, charged with belemnites, to within a few yards of a mass of
+granite. Here the limestone begins to put on a granular texture, but is
+extremely fine-grained. When nearer the junction it becomes grey, and has a
+saccharoid structure. In another locality, near Champoleon, a granite
+composed of quartz, black mica, and rose-coloured felspar, is observed
+partly to overlie the secondary rocks, producing an alteration which
+extends for about 30 feet downwards, diminishing in the beds which lie
+farthest from the <span class="pagenum"><a id="page456"></a>[p.456]</span>granite. (See <a href="#img479">fig. 503.</a>) In the altered mass
+the argillaceous beds are hardened, the limestone is saccharoid, the grits
+quartzose, and in the midst of them is a thin layer of an imperfect
+granite. It is also an important circumstance that near the point of
+contact, both the granite and the secondary rocks become metalliferous, and
+contain nests and small veins of blende, galena, iron, and copper pyrites.
+The stratified rocks become harder and more crystalline, but the granite,
+on the contrary, softer and less perfectly crystallized near the
+junction.<a name="FNanchor_AJ_6" id="FNanchor_AJ_6"></a><a href="#Footnote_AJ_6" class="fnanchor">[456-A]</a></p>
+
+<a id="img479" name="img479"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 503.</p>
+<img src="images/img479.jpg" width="350" height="360" alt="" title="">
+<p>Junction of granite with Jurassic or Oolite strata in the Alps,
+near Champoleon.</p></div>
+
+<p>Although the granite is incumbent in the above section (<a href="#img479">fig. 503.</a>), we
+cannot assume that it overflowed the strata, for the disturbances of the
+rocks are so great in this part of the Alps that they seldom retain the
+position which they must originally have occupied.</p>
+
+<p>A considerable mass of syenite, in the Isle of Skye, is described by Dr.
+MacCulloch as intersecting limestone and shale, which are of the age of the
+lias.<a name="FNanchor_AJ_7" id="FNanchor_AJ_7"></a><a href="#Footnote_AJ_7" class="fnanchor">[456-B]</a> The limestone, which, at a greater distance from the granite,
+contains shells, exhibits no traces of them near its junction, where it has
+been converted into a pure crystalline marble.<a name="FNanchor_AJ_8" id="FNanchor_AJ_8"></a><a href="#Footnote_AJ_8" class="fnanchor">[456-C]</a></p>
+
+<p>At Predazzo, in the Tyrol, secondary strata, some of which are limestones
+of the Oolitic period, have been traversed and altered by plutonic rocks,
+one portion of which is an augitic porphyry, which passes insensibly into
+granite. The limestone is changed into granular marble, with a band of
+serpentine at the junction.<a name="FNanchor_AJ_9" id="FNanchor_AJ_9"></a><a href="#Footnote_AJ_9" class="fnanchor">[456-D]</a></p>
+
+<p><i>Carboniferous period.</i>&mdash;The granite of Dartmoor, in Devonshire, was
+formerly supposed to be one of the most ancient of the plutonic rocks, but
+is now ascertained to be posterior in date to the culm-measures of that
+county, which, from their position, and as containing true coal-plants, are
+regarded by Professor Sedgwick and Sir R. Murchison as members of the true
+carboniferous series. This granite, like the syenitic granite of
+Christiania, has broken through the stratified formations without much
+changing their strike. Hence, on the north-west side of Dartmoor, the
+successive members of the culm-measures abut against the granite, and
+become metamorphic as they <span class="pagenum"><a id="page457"></a>[p.457]</span>approach. These strata are also
+penetrated by granite veins, and plutonic dikes, called "elvans."<a name="FNanchor_AJ_10" id="FNanchor_AJ_10"></a><a href="#Footnote_AJ_10" class="fnanchor">[457-A]</a>
+The granite of Cornwall is probably of the same date, and, therefore, as
+modern as the Carboniferous strata, if not much newer.</p>
+
+<p><i>Silurian period.</i>&mdash;It has long been known that the granite near
+Christiania, in Norway, is of newer origin than the Silurian strata of that
+region. Von Buch first announced, in 1813, the discovery of its
+posteriority in date to limestones containing orthocerata and trilobites.
+The proofs consist in the penetration of granite veins into the shale and
+limestone, and the alteration of the strata, for a considerable distance
+from the point of contact, both of these veins and the central mass from
+which they emanate. (See <a href="#page447">p. 447.</a>) Von Buch supposed that the plutonic rock
+alternated with the fossiliferous strata, and that large masses of granite
+were sometimes incumbent upon the strata; but this idea was erroneous, and
+arose from the fact that the beds of shale and limestone often dip towards
+the granite up to the point of contact, appearing as if they would pass
+under it in mass, as at <i>a</i>, <a href="#img480">fig. 504.</a>, and then again on the opposite side
+of the same mountain, as at <i>b</i>, dip away from the same granite. When the
+junctions, however, are carefully examined, it is found that the plutonic
+rock intrudes itself in veins, and nowhere covers the fossiliferous strata
+in large overlying masses, as is so commonly the case with trappean
+formations.<a name="FNanchor_AJ_11" id="FNanchor_AJ_11"></a><a href="#Footnote_AJ_11" class="fnanchor">[457-B]</a></p>
+
+<a id="img480" name="img480"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 504.</p>
+<img src="images/img480.jpg" width="450" height="099" alt="" title=""></div>
+
+<p>Now this granite, which is more modern than the Silurian strata of Norway,
+also sends veins in the same country into an ancient formation of gneiss;
+and the relations of the plutonic rock and the gneiss, at their junction,
+are full of interest when we duly consider the wide difference of epoch
+which must have separated their origin.</p>
+
+<a id="img481" name="img481"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 505.</p>
+<img src="images/img481.jpg" width="450" height="120" alt="" title="">
+<p>Granite sending veins into Silurian strata and
+Gneiss,&mdash;Christiania, Norway.</p></div>
+
+<p>The length of this interval of time is attested by the following
+facts:&mdash;The fossiliferous, or Silurian beds, rest unconformably upon the
+truncated edges of the gneiss, the inclined strata of which had been
+disturbed and denuded before the sedimentary beds were superimposed (see
+<a href="#img481">fig. 505.</a>). The signs of denudation are twofold; <span class="pagenum"><a id="page458"></a>[p.458]</span>first, the
+surface of the gneiss is seen occasionally, on the removal of the newer
+beds, containing organic remains, to be worn and smoothed; secondly,
+pebbles of gneiss have been found in some of the transition strata. Between
+the origin, therefore, of the gneiss and the granite there intervened,
+first, the period when the strata of gneiss were inclined; secondly, the
+period when they were denuded; thirdly, the period of the deposition of the
+transition deposits. Yet the granite produced, after this long interval, is
+often so intimately blended with the ancient gneiss, at the point of
+junction, that it is impossible to draw any other than an arbitrary line of
+separation between them; and where this is not the case, tortuous veins of
+granite pass freely through gneiss, ending sometimes in threads, as if the
+older rock had offered no resistance to their passage. It seems necessary,
+therefore, to conceive that the gneiss was softened and more or less melted
+when penetrated by the granite. But had such junctions alone been visible,
+and had we not learnt, from other sections, how long a period elapsed
+between the consolidation of the gneiss and the injection of this granite,
+we might have suspected that the gneiss was scarcely solidified, or had not
+yet assumed its complete metamorphic character, when invaded by the
+plutonic rock. From this example we may learn how impossible it is to
+conjecture whether certain granites in Scotland, and other countries, which
+send veins into gneiss and other metamorphic rocks, are primary, or whether
+they may not belong to some secondary or tertiary period.</p>
+
+<p><i>Oldest granites.</i>&mdash;It is not half a century since the doctrine was very
+general that all granitic rocks were <i>primitive</i>, that is to say, that they
+originated before the deposition of the first sedimentary strata, and
+before the creation of organic beings (see above, <a href="#page9">p. 9.</a>). But so greatly
+are our views now changed, that we find it no easy task to point out a
+single mass of granite demonstrably more ancient than all the known
+fossiliferous deposits. Could we discover some Lower Cambrian strata
+resting immediately on granite, there being no alterations at the point of
+contact, nor any intersecting granitic veins, we might then affirm the
+plutonic rock to have originated before the oldest known fossiliferous
+strata. Still it would be presumptuous to suppose that when a small part
+only of the globe has been investigated, we are acquainted with the oldest
+fossiliferous strata in the crust of our planet. Even when these are found,
+we cannot assume that there never were any antecedent strata containing
+organic remains, which may have become metamorphic. If we find pebbles of
+granite in a conglomerate of the Lower Cambrian system, we may then feel
+assured that the parent granite was formed before the Lower Cambrian
+formation. But if the incumbent strata be merely Silurian or Upper
+Cambrian, the fundamental granite, although of high antiquity, may be
+posterior in date to <i>known</i> fossiliferous formations.</p>
+
+<p><i>Protrusion of solid granite.</i>&mdash;In part of Sutherlandshire, near Brora,
+common granite, composed of felspar, quartz, and mica, is in immediate
+contact with Oolitic strata, and has clearly been elevated <span class="pagenum"><a id="page459"></a>[p.459]</span>to the
+surface at a period subsequent to the deposition of those strata.<a name="FNanchor_AJ_12" id="FNanchor_AJ_12"></a><a href="#Footnote_AJ_12" class="fnanchor">[459-A]</a>
+Professor Sedgwick and Sir R. Murchison conceive that this granite has been
+upheaved in a solid form; and that in breaking through the submarine
+deposits, with which it was not perhaps originally in contact, it has
+fractured them so as to form a breccia along the line of junction. This
+breccia consists of fragments of shale, sandstone, and limestone, with
+fossils of the oolite, all united together by a calcareous cement. The
+secondary strata, at some distance from the granite, are but slightly
+disturbed, but in proportion to their proximity the amount of dislocation
+becomes greater.</p>
+
+<p>If we admit that solid hypogene rocks, whether stratified or unstratified,
+have in such cases been driven upwards so as to pierce through yielding
+sedimentary deposits, we shall be enabled to account for many geological
+appearances otherwise inexplicable. Thus, for example, at Weinb�hla and
+Hohnstein, near Meissen, in Saxony, a mass of granite has been observed
+covering strata of the Cretaceous and Oolitic periods for the space of
+between 300 and 400 yards square. It appears clearly from a recent Memoir
+of Dr. B. Cotta on this subject<a name="FNanchor_AJ_13" id="FNanchor_AJ_13"></a><a href="#Footnote_AJ_13" class="fnanchor">[459-B]</a>, that the granite was thrust into
+its actual position when solid. There are no intersecting veins at the
+junction&mdash;no alteration as if by heat, but evident signs of rubbing, and a
+breccia in some places, in which pieces of granite are mingled with broken
+fragments of the secondary rocks. As the granite overhangs both the lias
+and chalk, so the lias is in some places bent over strata of the cretaceous
+era.</p>
+
+<p><i>Relative age of the granites of Arran.</i>&mdash;In this island, the largest in
+the Firth of Clyde, being twenty miles in length from north to south, the
+four great classes of rocks, the fossiliferous, volcanic, plutonic, and
+metamorphic, are all conspicuously displayed within a very small area, and
+with their peculiar characters strongly contrasted. In the north of the
+island the granite rises to the height of nearly 3000 feet above the sea,
+terminating in mountainous peaks. (See section, <a href="#img482">fig. 506.</a>) On the flanks of
+the same mountains are chloritic-schists, blue roofing-slate, and other
+rocks of the metamorphic order (No. 1.), into which the granite (No. 2.)
+sends veins. This granite, therefore, is newer than the hypogene schists
+(No. 1.), which it penetrates.</p>
+
+<p>These schists are highly inclined. Upon them rest beds of conglomerate and
+sandstone (No. 3.), which are referable to the Old Red formation, to which
+succeed various shales and limestones (No. 4.) containing the fossils of
+the Carboniferous period, upon which are other strata of sandstone and
+conglomerate (upper part of No. 4.), in which no fossils have been met
+with, which it is conjectured may belong to the New Red sandstone period.
+All the preceding formations are cut through by the volcanic rocks (No.
+5.), which consist of greenstone, basalt, pitchstone, claystone-porphyry,
+and other varieties. These appear either in the form of dikes, or in
+<span class="pagenum"><a id="page460"></a>[p.460]</span>dense masses from 50 to 700 feet in thickness, overlying the
+strata (No. 4.). They sometimes pass into syenite of so crystalline a form,
+that it may rank as a plutonic formation; and in one region, at
+Ploverfield, in Glen Cloy, a fine-grained granite (6. <i>a</i>) is seen
+associated with the trap formation, and sending veins into the sandstone or
+into the upper strata of No. 4. This interesting discovery of granite in
+the southern region of Arran, at a point where it is separated from the
+northern mass of granite by a great thickness of secondary strata and
+overlying trap, was made by Mr. L. A. Necker of Geneva, during his survey
+of Arran in 1839. We also learn from the recent investigations of Prof. A.
+C. Ramsay, that a similar fine-grained granite (No. 6. <i>b</i>) appears in the
+interior of the northern granitic district, forming the nucleus of it, and
+sending veins into the older coarse-grained granite (No. 2.). The trap
+dikes which penetrate the older granite are cut off, according to Mr.
+Ramsay, at the junction of the fine grained.</p>
+
+<p>It is not improbable that the granite (No. 6. <i>b</i>) may be of the same age
+as that of Ploverfield (No. 6. <i>a</i>), and this again may belong to the same
+geological epoch as the trap formations (No. 5.). If there be any
+difference of date, it would seem that the fine-grained granite must be
+newer than the trappean rocks. But, on the other hand, the coarser granite
+(No. 2.) may be the oldest rock in Arran, with the exception of the
+hypogene slates (No. 1.), into which it sends veins.</p>
+
+<a id="img482" name="img482"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 506. General Section of Arran from north to south.</p>
+<img src="images/img482.jpg" width="500" height="064" alt="" title="">
+<ul class="smaller leftal add1em min1em">
+<li>1. Metamorphic or Hypogene schists, the oldest formations in Arran.</li>
+<li>2. Coarse-grained granite sending veins into the schists, No. 1.</li>
+<li>3. Old Red Sandstone and Conglomerate containing pebbles exclusively
+derived from the rocks, No 1., without any intermixture of granitic
+fragments.</li>
+<li>4. Carboniferous strata and red sandstone (New Red?).</li>
+<li>5. Trap, overlying and in dikes, passing occasionally into Syenites
+of the Plutonic class.</li>
+<li>6. <i>a.</i> Fine-grained granite, associated with the overlying
+trap, No. 5.</li>
+<li>6. <i>b.</i> Similar fine-grained granite, sending veins into the older
+granite, No. 2., and cutting off the trappean dikes, <i>c</i>, <i>d</i>.<a name="FNanchor_AJ_14" id="FNanchor_AJ_14"></a><a href="#Footnote_AJ_14" class="fnanchor">[461-A]</a></li>
+</ul></div>
+
+<p>An objection may perhaps at first be started to this conclusion, derived
+from the curious and striking fact, the importance of which was first
+emphatically pointed out by Dr. MacCulloch, that no pebbles of granite
+occur in the conglomerates of the red sandstone in Arran, although these
+conglomerates are several hundred feet in thickness, and lie at the foot of
+lofty granite mountains, which tower above them. As a general rule, all
+such aggregates of pebbles and sand are mainly composed of the wreck of
+pre-existing rocks occurring in the immediate vicinity. The total absence
+therefore of granitic pebbles has justly been a theme of wonder to those
+geologists who have successively visited Arran, and they have carefully
+searched there, as I have done myself, to find an exception, but in vain.
+The rounded masses consist exclusively of quartz, chlorite-schist, and
+other members of the metamorphic series; nor in the newer conglomerates of
+No. 4. have any granitic fragments been discovered. Are we then entitled to
+affirm that the coarse-grained granite (No. 2.), like the fine-grained
+variety (No. 6. <i>a</i>), is more modern than all the other rocks of the
+island? This we cannot assume at present, but we may confidently infer that
+when the various beds of sandstone and conglomerate were formed, no granite
+had reached the surface, or had been exposed to denudation in Arran. It is
+clear that the crystalline schists were ground into sand and shingle when
+the strata No. 3. were deposited, and at that time the waves had never
+acted upon the granite, which now sends its veins into the schist. May we
+then conclude, that the schists suffered denudation before they were
+invaded <span class="pagenum"><a id="page462"></a>[p.462]</span>by granite? This opinion, although not inadmissible, is
+by no means fully borne out by the evidence. For at the time when the Old
+Red sandstone originated, the metamorphic strata may have formed islands in
+the sea, as in <a href="#img483">fig. 507.</a>, over which the breakers rolled, or from which
+torrents and rivers descended, carrying down gravel and sand. The plutonic
+rock or granite (B) may even then have been previously injected at a
+certain depth below, and yet may never have been exposed to denudation.</p>
+
+<a id="img483" name="img483"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 507.</p>
+<img src="images/img483.jpg" width="400" height="073" alt="" title=""></div>
+
+<p>As to the time and manner of the subsequent protrusion of the
+coarse-grained granite (No. 2.), this rock may have been thrust up bodily,
+in a solid form, during that long series of igneous operations which
+produced the trappean and plutonic formations (Nos. 5., 6. <i>a</i>, and 6.
+<i>b</i>).</p>
+
+<p>We have shown that these eruptions, whatever their date, were posterior to
+the deposition of all the fossiliferous strata of Arran. We can also prove
+that subsequently both the granitic and trappean rocks underwent great
+aqueous denudation, which they probably suffered during their emergence
+from the sea. The fact is demonstrated by the abrupt truncation of numerous
+dikes, such as those at <i>c</i>, <i>d</i>, <i>e</i>, which are cut off on the surface of
+the granite and trap. The overlying trap also ceases very abruptly on
+approaching the boundary of the great hypogene region, and terminates in a
+steep escarpment facing towards it as at <i>f</i>, <a href="#img482">fig. 506.</a> When in its
+original fluid state it could not have come thus suddenly to an end, but
+must have filled up the hollow now separating it from the hypogene rocks,
+had such a hollow then existed. This necessity of supposing that both the
+trap and the conglomerate once extended farther, and that veins such as
+<i>c</i>, <i>d</i>, <a href="#img482">fig. 506.</a>, were once prolonged farther upwards, prepares us to
+believe that the whole of the northern granite may at one time have been
+covered by newer formations, under the pressure of which, before its
+protrusion, it assumed its highly crystalline texture.</p>
+
+<p>The theory of the protrusion in a solid form of the northern nucleus of
+granite is confirmed by the manner in which the hypogene slates (No. 1.)
+and the beds of conglomerate (No. 3.) dip away from it on all sides. In
+some places indeed the slates are inclined towards the granite, but this
+exception might have been looked for, because these hypogene strata have
+undergone disturbances at more than one geological epoch, and may at some
+points, perhaps, have their original order of position inverted. The high
+inclination, therefore, and the qu�qu�versal dip of the beds around the
+borders of the granitic boss, and the comparative horizontality of the
+fossiliferous strata in the southern part of the island, are facts which
+all accord with the hypothesis of a great amount of movement at that point
+where the granite <span class="pagenum"><a id="page463"></a>[p.463]</span>is supposed to have been thrust up bodily, and
+where we may conceive it to have been distended laterally by the repeated
+injection of fresh supplies of melted materials.<a name="FNanchor_AJ_15" id="FNanchor_AJ_15"></a><a href="#Footnote_AJ_15" class="fnanchor">[463-A]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2><a id="chaxxxv" name="chaxxxv">CHAPTER XXXV</a>.</h2>
+
+<h4>METAMORPHIC ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">General character of metamorphic rocks &mdash; Gneiss &mdash;
+Hornblende-schist &mdash; Mica-schist &mdash; Clay-slate &mdash; Quartzite
+&mdash; Chlorite-schist &mdash; Metamorphic limestone &mdash; Alphabetical
+list and explanation of other rocks of this family &mdash; Origin of the
+metamorphic strata &mdash; Their stratification is real and distinct from
+cleavage &mdash; Joints and slaty cleavage &mdash; Supposed causes of these
+structures &mdash; How far connected with crystalline action.</p></div>
+
+
+<p><span class="smcap">We</span> have now considered three distinct classes of rocks: first, the aqueous,
+or fossiliferous; secondly, the volcanic; and, thirdly, the plutonic, or
+granitic; and we have now, lastly, to examine those crystalline (or
+hypogene) strata to which the name of <i>metamorphic</i> has been assigned. The
+last-mentioned term expresses, as before explained, a theoretical opinion
+that such strata, after having been deposited from water, acquired, by the
+influence of heat and other causes, a highly crystalline texture. They who
+still question this opinion may call the rocks under consideration the
+stratified hypogene, or schistose hypogene formations.</p>
+
+<p>These rocks, when in their most characteristic or normal state, are wholly
+devoid of organic remains, and contain no distinct fragments of other
+rocks, whether rounded or angular. They sometimes break out in the central
+parts of narrow mountain chains, but in other cases extend over areas of
+vast dimensions, occupying, for example, nearly the whole of Norway and
+Sweden, where, as in Brazil, they appear alike in the lower and higher
+grounds. In Great Britain, those members of the series which approach most
+nearly to granite in their composition, as gneiss, mica-schist, and
+hornblende-schist, are confined to the country north of the rivers Forth
+and Clyde.</p>
+
+<p>Many attempts have been made to trace a general order of succession or
+superposition in the members of this family; gneiss, for example, having
+been often supposed to hold invariably a lower geological position than
+mica-schist. But although such an order may prevail throughout limited
+districts, it is by no means universal, nor even general, throughout the
+globe. To this subject, however, I <span class="pagenum"><a id="page464"></a>[p.464]</span>shall again revert, in the
+last chapter of this volume, when the chronological relations of the
+metamorphic rocks are pointed out.</p>
+
+<p>The following may be enumerated as the principal members of the metamorphic
+class:&mdash;gneiss, mica-schist, hornblende-schist, clay-slate,
+chlorite-schist, hypogene or metamorphic limestone, and certain kinds of
+quartz-rock or quartzite.</p>
+
+<a id="img484" name="img484"></a>
+<div class="figcenter smaller width400">
+<p>Fig. 508.</p>
+<img src="images/img484.jpg" width="400" height="179" alt="" title="">
+<p>Fragment of gneiss, natural size; section at right
+angles to planes of stratification.</p></div>
+
+<p><i>Gneiss.</i>&mdash;The first of these, gneiss, may be called stratified granite,
+being formed of the same materials as granite, namely, felspar, quartz, and
+mica. In the specimen here figured, the white layers consist almost
+exclusively of granular felspar, with here and there a speck of mica and
+grain of quartz. The dark layers are composed of grey quartz and black
+mica, with occasionally a grain of felspar intermixed. The rock splits most
+easily in the plane of these darker layers, and the surface thus exposed is
+almost entirely covered with shining spangles of mica. The accompanying
+quartz, however, greatly predominates in quantity, but the most ready
+cleavage is determined by the abundance of mica in certain parts of the
+dark layer.</p>
+
+<p>Instead of these thin lamin�, gneiss is sometimes simply divided into thick
+beds, in which the mica has only a slight degree of parallelism to the
+planes of stratification.</p>
+
+<p>The term "gneiss," however, in geology is commonly used in a wider sense,
+to designate a formation in which the above-mentioned rock prevails, but
+with which any one of the other metamorphic rocks, and more especially
+hornblende-schist, may alternate. These other members of the metamorphic
+series are, in this case, considered as subordinate to the true gneiss.</p>
+
+<p>The different varieties of rock allied to gneiss, into which felspar enters
+as an essential ingredient, will be understood by referring to what was
+said of granite. Thus, for example, hornblende may be superadded to mica,
+quartz, and felspar, forming a syenitic gneiss; or talc may be substituted
+for mica, constituting talcose gneiss, a rock composed of felspar, quartz,
+and talc, in distinct crystals or grains (stratified protogine of the
+French).</p>
+
+<p><i>Hornblende-schist</i> is usually black, and composed principally of
+hornblende, with a variable quantity of felspar, and sometimes grains of
+quartz. When the hornblende and felspar are nearly in equal <span class="pagenum"><a id="page465"></a>[p.465]</span>
+quantities, and the rock is not slaty, it corresponds in character with the
+greenstones of the trap family, and has been called "primitive greenstone."
+It may be termed hornblende rock. Some of these hornblendic masses may
+really have been volcanic rocks, which have since assumed a more
+crystalline or metamorphic texture.</p>
+
+<p><i>Mica-schist</i>, or <i>Micaceous schist</i>, is, next to gneiss, one of the most
+abundant rocks of the metamorphic series. It is slaty, essentially composed
+of mica and quartz, the mica sometimes appearing to constitute the whole
+mass. Beds of pure quartz also occur in this formation. In some districts,
+garnets in regular twelve-sided crystals form an integrant part of
+mica-schist. This rock passes by insensible gradations into clay-slate.</p>
+
+<p><i>Clay-slate</i>, or <i>Argillaceous schist</i>.&mdash;This rock resembles an indurated
+clay or shale, is for the most part extremely fissile, often affording good
+roofing slate. It may consist of the ingredients of gneiss, or of an
+extremely fine mixture of mica and quartz, or talc and quartz. Occasionally
+it derives a shining and silky lustre from the minute particles of mica or
+talc which it contains. It varies from greenish or bluish-grey to a lead
+colour. It may be said of this, more than of any other schist, that it is
+common to the metamorphic and fossiliferous series, for some clay-slates
+taken from each division would not be distinguishable by mineralogical
+characters.</p>
+
+<p><i>Quartzite</i>, or <i>Quartz rock</i>, is an aggregate of grains of quartz, which
+are either in minute crystals, or in many cases slightly rounded, occurring
+in regular strata, associated with gneiss or other metamorphic rocks.
+Compact quartz, like that so frequently found in veins, is also found
+together with granular quartzite. Both of these alternate with gneiss or
+mica-schist, or pass into those rocks by the addition of mica, or of
+felspar and mica.</p>
+
+<p><i>Chlorite-schist</i> is a green slaty rock, in which chlorite is abundant in
+foliated plates, usually blended with minute grains of quartz, or sometimes
+with felspar or mica. Often associated with, and graduating into, gneiss
+and clay-slate.</p>
+
+<p><i>Hypogene</i>, or <i>Metamorphic limestone</i>.&mdash;This rock, commonly called
+<i>primary limestone</i>, is sometimes a thick bedded white crystalline granular
+marble used in sculpture; but more frequently it occurs in thin beds,
+forming a foliated schist much resembling in colour and appearance certain
+varieties of gneiss and mica-schist. It alternates with both these rocks,
+and in like manner with argillaceous schist. It then usually contains some
+crystals of mica, and occasionally quartz, felspar, hornblende, and talc.
+This member of the metamorphic series enters sparingly into the structure
+of the hypogene districts of Norway, Sweden, and Scotland, but is largely
+developed in the Alps.</p>
+
+<p>Before offering any farther observations on the probable origin of the
+metamorphic rocks, I subjoin, in the form of a glossary, a brief
+explanation of some of the principal varieties and their synonymies.</p>
+
+<div class="blq3">
+<p class="indentm3"><span class="pagenum"><a id="page466"></a>[p.466]</span><span class="smcap">Actinolite-schist.</span> A slaty foliated rock, composed chiefly of
+actinolite, (an emerald-green mineral, allied to hornblende,) with some
+admixture of felspar, or quartz, or mica.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Ampelite.</span> Aluminous slate (Brongniart); occurs both in the metamorphic and
+fossiliferous series.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Amphibolite.</span> <a href="#hornbr1">Hornblende rock</a>, which see.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Argillaceous-schist</span>, or <span class="smcap">Clay-slate</span>. <i>See</i> <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Arkose.</span> Term used by Brongniart for granular <a href="#quartzit">Quartzite</a>, which see.</p>
+
+<p class="indentm3"><span class="smcap">Chiastolite-slate</span> scarcely differs from clay-slate, but includes numerous
+crystals of Chiastolite; in considerable thickness in Cumberland.
+Chiastolite occurs in long slender rhomboidal crystals. For composition,
+see Table, <a href="#page377">p. 377.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Chlorite-schist.</span> A green slaty rock, in which chlorite, a green scaly
+mineral, is abundant. <i>See</i> <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Clay-slate</span>, or <span class="smcap">Argillaceous-schist</span>. <i>See</i> <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3"><span class="smcap">Eurite</span> and <span class="smcap">Euritic Porphyry</span>. A base of compact felspar, with grains of
+laminar felspar, and often mica and other minerals disseminated
+(Brongniart). M. D'Aubuisson regards eurite as an extremely fine-grained
+granite, in which felspar predominates, the whole forming an apparently
+homogeneous rock. Eurite has been already mentioned as a plutonic rock, but
+occurs also in beds subordinate to gneiss or mica-slate.</p>
+
+<p class="indentm3"><span class="smcap">Gneiss.</span> A stratified or laminated rock, same composition as granite. <i>See</i>
+<a href="#page464">p. 464.</a></p>
+
+<p class="indentm3"><span class="smcap"><a id="hornbr1" name="hornbr1">Hornblende Rock</a></span>, or <span class="smcap">Amphibolite</span>. Composed of hornblende and felspar. The
+same composition as hornblende-schist, stratified, but not fissile. <i>See</i>
+<a href="#page376">p. 376.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Hornblende-schist</span>, or <span class="smcap">Slate</span>. Composed chiefly of hornblende, with
+occasionally some felspar. <i>See</i> <a href="#page464">p. 464.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Hornblendic</span> or <span class="smcap">Syenitic-Gneiss</span>. Composed of felspar, quartz, and
+hornblende.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Hypogene Limestone.</span> <i>See</i> <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3"><span class="smcap">Marble.</span> <i>See</i> <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Mica-schist</span>, or <span class="smcap">Micaceous-schist</span>. A slaty rock, composed of mica and quartz
+in variable proportions. <i>See</i> <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Mica-slate.</span> <i>See</i> <span class="smcap">Mica-schist</span>, <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3"><span class="smcap">Phyllade.</span> D'Aubuisson's term for clay-slate, from
+&#966;&#965;&#955;&#955;&#945;&#962;, a heap of leaves.</p>
+
+<p class="indentm3 martopm1"><span class="smcap">Primary Limestone.</span> <i>See</i> <span class="smcap">Hypogene Limestone</span>, <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Protogine.</span> <i>See</i> <span class="smcap">Talcose-gneiss</span>, <a href="#page464">p. 464.</a>; when unstratified it is
+Talcose-granite.</p>
+
+<p class="indentm3"><span class="smcap">Quartz Rock</span>, or <span class="smcap"><a id="quartzit" name="quartzit">Quartzite</a></span>. A stratified rock; an aggregate of grains of
+quartz. <i>See</i> <a href="#page465">p. 465.</a></p>
+
+<p class="indentm3"><span class="smcap">Serpentine</span> occurs in both divisions of the hypogene series, as a stratified
+or unstratified rock; contains much magnesia; is chiefly composed of the
+mineral called serpentine, mixed with diallage, talc, and steatite. The
+pure varieties of this rock, called noble serpentine, consist of a hydrated
+silicate of magnesia, generally of a greenish colour: this base is commonly
+mixed with oxide of iron.</p>
+
+<p class="indentm3"><span class="smcap">Talcose-gneiss.</span> Same composition as talcose-granite or protogine, but
+either stratified or laminated. <i>See</i> <a href="#page464">p. 464.</a></p>
+
+<p class="indentm3 martopm1"><span class="smcap">Talcose-schist</span> consists chiefly of talc, or of talc and quartz, or of talc
+and felspar, and has a texture something like that of clay-slate.</p>
+
+<p class="indentm3"><span class="smcap">Whitestone.</span> Same as Eurite.</p></div>
+
+
+<h3><span class="pagenum"><a id="page467"></a>[p.467]</span><i>Origin of the Metamorphic Strata.</i></h3>
+
+<p>Having said thus much of the mineral composition of the metamorphic rocks,
+I may combine what remains to be said of their structure and history with
+an account of the opinions entertained of their probable origin. At the
+same time, it may be well to forewarn the reader that we are here entering
+upon ground of controversy, and soon reach the limits where positive
+induction ends, and beyond which we can only indulge in speculations. It
+was once a favourite doctrine, and is still maintained by many, that these
+rocks owe their crystalline texture, their want of all signs of a
+mechanical origin, or of fossil contents, to a peculiar and nascent
+condition of the planet at the period of their formation. The arguments in
+refutation of this hypothesis will be more fully considered when I show, in
+the last chapter of this volume, to how many different ages the metamorphic
+formations are referable, and how gneiss, mica-schist, clay-slate, and
+hypogene limestone (that of Carrara for example), have been formed, not
+only since the first introduction of organic beings into this planet, but
+even long after many distinct races of plants and animals had passed away
+in succession.</p>
+
+<p>The doctrine respecting the crystalline strata, implied in the name
+metamorphic, may properly be treated of in this place; and we must first
+inquire whether these rocks are really entitled to be called stratified in
+the strict sense of having been originally deposited as sediment from
+water. The general adoption by geologists of the term stratified, as
+applied to these rocks, sufficiently attests their division into beds very
+analogous, at least in form, to ordinary fossiliferous strata. This
+resemblance is by no means confined to the existence in both of an
+occasional slaty structure, but extends to every kind of arrangement which
+is compatible with the absence of fossils, and of sand, pebbles,
+ripple-mark, and other characters which the metamorphic theory supposes to
+have been obliterated by plutonic action. Thus, for example, we behold
+alike in the crystalline and fossiliferous formations an alternation of
+beds varying greatly in composition, colour, and thickness. We observe, for
+instance, gneiss alternating with layers of black hornblende-schist, or
+with granular quartz, or limestone; and the interchange of these different
+strata may be repeated for an indefinite number of times. In the like
+manner, mica-schist alternates with chlorite-schist, and with granular
+limestone in thin layers.</p>
+
+<p>As in fossiliferous formations strata of pure siliceous sand alternate with
+micaceous sand and with layers of clay, so in the crystalline or
+metamorphic rocks we have beds of pure quartzite alternating with
+mica-schist and clay-slate. As in the secondary and tertiary series we meet
+with limestone alternating again and again with micaceous or argillaceous
+sand, so we find in the hypogene, gneiss and mica-schist alternating with
+pure and impure granular limestones.</p>
+
+<p><span class="pagenum"><a id="page468"></a>[p.468]</span>It has also been shown that the ripple-mark is very commonly
+repeated throughout a considerable thickness of fossiliferous strata; so in
+mica-schist and gneiss, there is sometimes an undulation of the lamin� on a
+minute scale, which may, perhaps, be a modification of similar inequalities
+in the original deposit.</p>
+
+<p>In the crystalline formations also, as in many of the sedimentary before
+described, single strata are sometimes made up of lamin� placed diagonally,
+such lamin� not being regularly parallel to the planes of cleavage.</p>
+
+<a id="img485" name="img485"></a>
+<div class="floatleft smaller width300">
+<p>Fig. 509.</p>
+<img src="images/img485.jpg" width="300" height="187" alt="" title="">
+<p>Lamination of clay-slate, Montagne de Seguinat,
+near Gavarnie, in the Pyrenees.</p></div>
+
+<p>This disposition of the layers is illustrated in the accompanying diagram,
+in which I have represented carefully the stratification of a coarse
+argillaceous schist, which I examined in the Pyrenees, part of which
+approaches in character to a green and blue roofing slate, while part is
+extremely quartzose, the whole mass passing downwards into micaceous
+schist. The vertical section here exhibited is about 3 feet in height, and
+the layers are sometimes so thin that fifty may be counted in the thickness
+of an inch. Some of them consist of pure quartz.</p>
+
+<p>The inference drawn from the phenomena above described in favour of the
+aqueous origin of clay-slate and other crystalline strata, is greatly
+strengthened by the fact that many of these metamorphic rocks occasionally
+alternate with, and sometimes pass by intermediate gradations into, rocks
+of a decidedly mechanical origin, and exhibiting traces of organic remains.
+The fossiliferous formations, moreover, into which this passage is
+effected, are by no means invariably of the same age nor of the highest
+antiquity, as will be afterwards explained.</p>
+
+<p><i>Stratification of the metamorphic rocks distinct from cleavage.</i>&mdash;The beds
+into which gneiss, mica-schist, and hypogene limestone divide, exhibit most
+commonly, like ordinary strata, a want of perfect geometrical parallelism.
+For this reason, therefore, in addition to the alternate recurrence of
+layers of distinct materials, the stratified arrangement of the crystalline
+rocks cannot be explained away by supposing it to be simply a divisional
+structure like that to which we owe some of the slates used for writing and
+roofing. <i>Slaty cleavage</i>, as it has been called, has in many cases been
+produced by the regular deposition of thin plates of fine sediment one upon
+another; but there are many instances where it is decidedly unconnected
+with such a mode of origin, and where it is not even confined to the
+aqueous formations. Some kinds of trap, for example, as clinkstone, split
+into lamin�, and are used for roofing.</p>
+
+<p>There are, says Professor Sedgwick, three distinct forms of structure
+exhibited in certain rocks throughout large districts: viz.&mdash;First,
+<span class="pagenum"><a id="page469"></a>[p.469]</span>stratification; secondly, joints; and thirdly, slaty cleavage;
+the two last having no connection with true bedding, and having been
+superinduced by causes absolutely independent of gravitation. All these
+different structures must have different names, even though there be some
+cases where it is impossible, after carefully studying the appearances, to
+decide upon the class to which they belong.<a name="FNanchor_AK_1" id="FNanchor_AK_1"></a><a href="#Footnote_AK_1" class="fnanchor">[469-A]</a></p>
+
+<p><i>Joints.</i>&mdash;Now, in regard to the second of these forms of structure or
+joints, they are natural fissures which often traverse rocks in straight
+and well-determined lines. They afford to the quarryman, as Sir R.
+Murchison observes, when speaking of the phenomena, as exhibited in
+Shropshire and the neighbouring counties, the greatest aid in the
+extraction of blocks of stone; and, if a sufficient number cross each
+other, the whole mass of rock is split into symmetrical blocks.<a name="FNanchor_AK_2" id="FNanchor_AK_2"></a><a href="#Footnote_AK_2" class="fnanchor">[469-B]</a> The
+faces of the joints are for the most part smoother and more regular than
+the surfaces of true strata. The joints are straight-cut chinks, often
+slightly open, often passing, not only through layers of successive
+deposition, but also through balls of limestone or other matter which have
+been formed by concretionary action, since the original accumulation of the
+strata. Such joints, therefore, must often have resulted from one of the
+last changes superinduced upon sedimentary deposits.<a name="FNanchor_AK_3" id="FNanchor_AK_3"></a><a href="#Footnote_AK_3" class="fnanchor">[469-C]</a></p>
+
+<p>In the annexed diagram the flat surfaces of rock A, B, C, represent exposed
+faces of joints, to which the walls of other joints, J J, are parallel. S S
+are the lines of stratification; D D are lines of slaty cleavage, which
+intersect the rock at a considerable angle to the planes of stratification.</p>
+
+<a id="img486" name="img486"></a>
+<div class="figcenter smaller widht400">
+<p>Fig. 510.</p>
+<img src="images/img486.jpg" width="400" height="178" alt="" title="">
+<p>Stratification, joints, and cleavage.</p></div>
+
+<p>Joints, according to Professor Sedgwick, are distinguishable from lines of
+slaty cleavage in this, that the rock intervening between two joints has no
+tendency to cleave in a direction parallel to the planes of the joints,
+whereas a rock is capable of indefinite subdivision in the direction of its
+slaty cleavage. In some cases where the strata are curved, the planes of
+cleavage are still perfectly parallel. This has been observed in the slate
+rocks of part of Wales (see <a href="#img487">fig. 511.</a>), <span class="pagenum"><a id="page470"></a>[p.470]</span>which consist of a hard
+greenish slate. The true bedding is there indicated by a number of parallel
+stripes, some of a lighter and some of a darker colour than the general
+mass. Such stripes are found to be parallel to the true planes of
+stratification, wherever these are manifested by ripple-mark, or by beds
+containing peculiar organic remains. Some of the contorted strata are of a
+coarse mechanical structure, alternating with fine-grained crystalline
+chloritic slates, in which case the same slaty cleavage extends through the
+coarser and finer beds, though it is brought out in greater perfection in
+proportion as the materials of the rock are fine and homogeneous. It is
+only when these are very coarse that the cleavage planes entirely vanish.
+These planes are usually inclined at a very considerable angle to the
+planes of the strata. In the Welsh chains, for example, the average angle
+is as much as from 30� to 40�. Sometimes the cleavage planes dip towards
+the same point of the compass as those of stratification, but more
+frequently to opposite points. It may be stated as a general rule, that
+when beds of coarser materials alternate with those composed of finer
+particles, the slaty cleavage is either entirely confined to the
+fine-grained rock, or is very imperfectly exhibited in that of coarser
+texture. This rule holds, whether the cleavage is parallel to the planes of
+stratification or not.</p>
+
+<a id="img487" name="img487"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 511.</p>
+<img src="images/img487.jpg" width="450" height="090" alt="" title="">
+<p>Parallel planes of cleavage intersecting curved <span class="wosp05">strata. (Sedgwick.)</span></p></div>
+
+<p>In the Swiss and Savoy Alps, as Mr. Bakewell has remarked, enormous masses
+of limestone are cut through so regularly by nearly vertical partings, and
+these are often so much more conspicuous than the seams of stratification,
+that an inexperienced observer will almost inevitably confound them, and
+suppose the strata to be perpendicular in places where in fact they are
+almost horizontal.<a name="FNanchor_AK_4" id="FNanchor_AK_4"></a><a href="#Footnote_AK_4" class="fnanchor">[470-A]</a></p>
+
+<p>Now these joints are supposed to be analogous to those partings which have
+been already observed to separate volcanic and plutonic rocks into cuboidal
+and prismatic masses. On a small scale we see clay and starch when dry
+split into similar shapes, which is often caused by simple contraction,
+whether the shrinking be due to the evaporation of water, or to a change of
+temperature. It is well known that many sandstones and other rocks expand
+by the application of moderate degrees of heat, and then contract again on
+cooling; and there can be no doubt that large portions of the earth's crust
+have, in the course of past ages, been subjected again and again to very
+different degrees of heat and cold. These alternations of temperature have
+probably contributed largely to the production of joints in rocks.</p>
+
+<p>In some countries, as in Saxony, where masses of basalt rest on <span class="pagenum"><a id="page471"></a>[p.471]</span>
+sandstone, the aqueous rock has for the distance of several feet from the
+point of junction assumed a columnar structure similar to that of the trap.
+In like manner some hearthstones, after exposure to the heat of a furnace
+without being melted, have become prismatic. Certain crystals also acquire
+by the application of heat a new internal arrangement, so as to break in a
+new direction, their external form remaining unaltered.</p>
+
+<p>Sir R. Murchison observes, that in referring both joints and slaty cleavage
+to crystalline action, we are borne out by a well-known analogy in which
+crystallization has in like manner given rise to two distinct kinds of
+structure in the same body. Thus, for example, in a six-sided prism of
+quartz, the planes of cleavage are distinct from those of the prism. It is
+impossible to cleave the crystals parallel to the plane of the prism, just
+as slaty rocks cannot be cleaved parallel to the joints; but the quartz
+crystal, like the older schists, may be cleaved <i>ad infinitum</i> in the
+direction of the cleavage planes.<a name="FNanchor_AK_5" id="FNanchor_AK_5"></a><a href="#Footnote_AK_5" class="fnanchor">[471-A]</a></p>
+
+<p>It seems, therefore, that the fissures called joints may have been the
+result of different causes, as of some modification of crystalline action,
+or simple contraction during consolidation, or during a change of
+temperature. And there are cases where joints may have been due to
+mechanical violence, and the strain exerted on strata during their
+upheaval, or when they have sunk down below their former level. Professor
+Phillips has suggested that the previous existence of divisional planes may
+often have determined, and must greatly have modified, the lines and points
+of fracture caused in rocks by those forces to which they owe their
+elevation or dislocations. These lines and points being those of least
+resistance, cannot fail to have influenced the direction in which the solid
+mass would give way on the application of external force.</p>
+
+<p>Professor Phillips has also remarked that in some slaty rocks the form of
+the outline of fossil shells and trilobites has been much changed by
+distortion, which has taken place in a longitudinal, transverse, or oblique
+direction. This change, he adds, seems to be the result of a "creeping
+movement" of the particles of the rock along the planes of cleavage, its
+direction being always uniform over the same tract of country, and its
+amount in space being sometimes measurable, and being as much as a quarter
+or even half an inch. The hard shells are not affected, but only those
+which are thin.<a name="FNanchor_AK_6" id="FNanchor_AK_6"></a><a href="#Footnote_AK_6" class="fnanchor">[471-B]</a> Mr. D. Sharpe, following up the same line of
+inquiry, came to the conclusion, that the present distorted forms of the
+shells in certain British slate rocks may be accounted for by supposing
+that the rocks in which they are imbedded have undergone compression in a
+direction perpendicular to the planes of cleavage, and a corresponding
+expansion in the direction of the dip of the cleavage.<a name="FNanchor_AK_7" id="FNanchor_AK_7"></a><a href="#Footnote_AK_7" class="fnanchor">[471-C]</a></p>
+
+<p>Mr. Darwin infers from his observations, that in South America the strike
+of the cleavage planes is very uniform over wide regions, <span class="pagenum"><a id="page472"></a>[p.472]</span>and
+that it corresponds with the strike of the planes of foliation in the
+gneiss and mica-schists of the same parts of Chili, Tierra del Fuego, &amp;c.
+The explanation which he suggests, is based upon a combination of
+mechanical and crystalline forces. The planes, he says, of cleavage, and
+even the foliation of mica-schist and gneiss, may be intimately connected
+with the planes of different tension to which the area was long subjected,
+<i>after</i> the main fissures or axis of upheavement had been formed, but
+<i>before</i> the final consolidation of the mass and the total cessation of all
+molecular movement.<a name="FNanchor_AK_8" id="FNanchor_AK_8"></a><a href="#Footnote_AK_8" class="fnanchor">[472-A]</a></p>
+
+<p>I have already stated that some extremely fine slates are perfectly
+parallel to the planes of stratification, as those of the Niesen, for
+example, near the Lake of Thun, in Switzerland, which contain fucoids, and
+are no doubt due to successive aqueous deposition. Even where the slates
+are oblique to the general planes of the strata, it by no means follows as
+a matter of course that they have been caused by crystalline action, for
+they may be the result of that diagonal lamination which I have before
+described (<a href="#page17">p. 17.</a>). In this case, however, there is usually much
+irregularity, whereas cleavage planes oblique to the true stratification,
+which are referred to a crystalline action, are often perfectly
+symmetrical, and observe a strict geometrical parallelism, even when the
+strata are contorted, as already described (<a href="#page470">p. 470.</a>).</p>
+
+<p>Professor Sedgwick, speaking of the planes of slaty cleavage, where they
+are decidedly distinct from those of sedimentary deposition, declares his
+opinion that no retreat of parts, no contraction in the dimensions of rocks
+in passing to a solid state, can account for the phenomenon. It must be
+referred to crystalline or polar forces acting simultaneously, and somewhat
+uniformly, in given directions, on large masses having a homogeneous
+composition.</p>
+
+<p>Sir John Herschel, in allusion to slaty cleavage, has suggested, "that if
+rocks have been so heated as to allow a commencement of crystallization;
+that is to say, if they have been heated to a point at which the particles
+can begin to move amongst themselves, or at least on their own axes, some
+general law must then determine the position in which these particles will
+rest on cooling. Probably that position will have some relation to the
+direction in which the heat escapes. Now, when all, or a majority of
+particles of the same nature, have a general tendency to one position, that
+must of course determine a cleavage plane. Thus we see the infinitesimal
+crystals of fresh precipitated sulphate of barytes, and some other such
+bodies, arrange themselves alike in the fluid in which they float; so as,
+when stirred, all to glance with one light, and give the appearance of
+silky filaments. Some sorts of soap, in which insoluble margarates<a name="FNanchor_AK_9" id="FNanchor_AK_9"></a><a href="#Footnote_AK_9" class="fnanchor">[472-B]</a>
+exist, exhibit the same phenomenon when mixed with water; and what occurs
+in our experiments on a minute scale may occur in nature on a great
+one."<a name="FNanchor_AK_10" id="FNanchor_AK_10"></a><a href="#Footnote_AK_10" class="fnanchor">[472-C]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page473"></a>[p.473]</span><a id="chaxxxvi" name="chaxxxvi">CHAPTER XXXVI</a>.</h2>
+
+<h4>METAMORPHIC ROCKS&mdash;<i>continued</i>.</h4>
+
+<div class="blq1">
+<p class="indentm2">Strata near some intrusive masses of granite converted into rocks identical
+with different members of the metamorphic series &mdash; Arguments hence
+derived as to the nature of plutonic action &mdash; Time may enable this
+action to pervade denser masses &mdash; From what kinds of sedimentary rock
+each variety of the metamorphic class may be derived &mdash; Certain
+objections to the metamorphic theory considered &mdash; Lamination of
+trachyte and obsidian due to motion &mdash; Whether some kinds of gneiss
+have become schistose by a similar action.</p></div>
+
+
+<p><span class="smcap">It</span> has been seen that geologists have been very generally led to infer,
+from the phenomena of joints and slaty cleavage, that mountain masses, of
+which the sedimentary origin is unquestionable, have been acted upon
+simultaneously by vast crystalline forces. That the structure of
+fossiliferous strata has often been modified by some general cause since
+their original deposition, and even subsequently to their consolidation and
+dislocation, is undeniable. These facts prepare us to believe that still
+greater changes may have been worked out by a greater intensity, or more
+prolonged development of the same agency, combined, perhaps, with other
+causes. Now we have seen that, near the immediate contact of granitic veins
+and volcanic dikes, very extraordinary alterations in rocks have taken
+place, more especially in the neighbourhood of granite. It will be useful
+here to add other illustrations, showing that a texture undistinguishable
+from that which characterizes the more crystalline metamorphic formations,
+has actually been superinduced in strata once fossiliferous.</p>
+
+<p>In the southern extremity of Norway there is a large district, on the west
+side of the fiord of Christiania, in which granite or syenite protrudes in
+mountain masses through fossiliferous strata, and usually sends veins into
+them at the point of contact. The stratified rocks, replete with shells and
+zoophytes, consist chiefly of shale, limestone, and some sandstone, and all
+these are invariably altered near the granite for a distance of from 50 to
+400 yards. The aluminous shales are hardened and have become flinty.
+Sometimes they resemble jasper. Ribboned jasper is produced by the
+hardening of alternate layers of green and chocolate-coloured schist, each
+stripe faithfully representing the original lines of stratification. Nearer
+the granite the schist often contains crystals of hornblende, which are
+even met with in some places for a distance of several hundred yards from
+the junction; and this black hornblende is so abundant that eminent
+geologists, when passing through the country, have confounded it with the
+ancient hornblende-schist, subordinate to the great gneiss formation of
+Norway. Frequently, between the granite and the hornblende slate, above
+mentioned, grains of mica and crystalline <span class="pagenum"><a id="page474"></a>[p.474]</span>felspar appear in the
+schist, so that rocks resembling gneiss and mica-schist are produced.
+Fossils can rarely be detected in these schists, and they are more
+completely effaced in proportion to the more crystalline texture of the
+beds, and their vicinity to the granite. In some places the siliceous
+matter of the schist becomes a granular quartz; and when hornblende and
+mica are added, the altered rock loses its stratification, and passes into
+a kind of granite. The limestone, which at points remote from the granite
+is of an earthy texture, blue colour, and often abounds in corals, becomes
+a white granular marble near the granite, sometimes siliceous, the granular
+structure extending occasionally upwards of 400 yards from the junction;
+and the corals being for the most part obliterated, though sometimes
+preserved, even in the white marble. Both the altered limestone and
+hardened slate contain garnets in many places, also ores of iron, lead, and
+copper, with some silver. These alterations occur equally, whether the
+granite invades the strata in a line parallel to the general strike of the
+fossiliferous beds, or in a line at right angles to their strike, as will
+be seen by the accompanying ground plan.<a name="FNanchor_AL_1" id="FNanchor_AL_1"></a><a href="#Footnote_AL_1" class="fnanchor">[474-A]</a></p>
+
+<a id="img488" name="img488"></a>
+<div class="figcenter smaller width450">
+<p>Fig. 512.</p>
+<img src="images/img488.jpg" width="450" height="230" alt="" title="">
+<p>Altered zone of fossiliferous slate and limestone
+near <span class="wosp05">granite. Christiania.</span></p>
+<p><i>The arrows indicate the dip, and the straight lines the strike,
+of the beds.</i></p></div>
+
+<p>The indurated and ribboned schists above mentioned bear a strong
+resemblance to certain shales of the coal found at Russell's Hall, near
+Dudley, where coal-mines have been on fire for ages. Beds of shale of
+considerable thickness, lying over the burning coal, have been baked and
+hardened so as to acquire a flinty fracture, the layers being alternately
+green and brick-coloured.</p>
+
+<p>The granite of Cornwall, in like manner, sends forth veins into a coarse
+argillaceous-schist, provincially termed killas. This killas is converted
+into hornblende-schist near the contact with the veins. These appearances
+are well seen at the junction of the granite and killas, in St. Michael's
+Mount, a small island nearly 300 feet high, situated in the bay, at a
+distance of about three miles from Penzance.</p>
+
+<p>The granite of Dartmoor, in Devonshire, says Sir H. De la Beche, <span class="pagenum"><a id="page475"></a>[p.475]</span>
+has intruded itself into the slate and slaty sandstone called greywack�,
+twisting and contorting the strata, and sending veins into them. Hence some
+of the slate rocks have become "micaceous; others more indurated, and with
+the characters of mica-slate and gneiss; while others again appear
+converted into a hard-zoned rock strongly impregnated with felspar."<a name="FNanchor_AL_2" id="FNanchor_AL_2"></a><a href="#Footnote_AL_2" class="fnanchor">[475-A]</a></p>
+
+<p>We learn from the investigations of M. Dufr�noy, that in the eastern
+Pyrenees there are mountain masses of granite posterior in date to the
+formations called lias and chalk of that district, and that these
+fossiliferous rocks are greatly altered in texture, and often charged with
+iron-ore, in the neighbourhood of the granite. Thus in the environs of St.
+Martin, near St. Paul de F�nouillet, the chalky limestone becomes more
+crystalline and saccharoid as it approaches the granite, and loses all
+trace of the fossils which it previously contained in abundance. At some
+points, also, it becomes dolomitic, and filled with small veins of
+carbonate of iron, and spots of red iron-ore. At Ranci� the lias nearest
+the granite is not only filled with iron-ore, but charged with pyrites,
+tremolite, garnet, and a new mineral somewhat allied to felspar, called,
+from the place in the Pyrenees where it occurs, "couzeranite."</p>
+
+<p>Now the alterations above described as superinduced in rocks by volcanic
+dikes and granite veins, prove incontestably that powers exist in nature
+capable of transforming fossiliferous into crystalline strata&mdash;powers
+capable of generating in them a new mineral character, similar, nay, often
+absolutely identical, with that of gneiss, mica-schist, and other
+stratified members of the hypogene series. The precise nature of these
+altering causes, which may provisionally be termed plutonic, is in a great
+degree obscure and doubtful; but their reality is no less clear, and we
+must suppose the influence of heat to be in some way connected with the
+transmutation, if, for reasons before explained, we concede the igneous
+origin of granite.</p>
+
+<p>The experiments of Gregory Watt, in fusing rocks in the laboratory, and
+allowing them to consolidate by slow cooling, prove distinctly that a rock
+need not be perfectly melted in order that a re-arrangement of its
+component particles should take place, and a partial crystallization
+ensue.<a name="FNanchor_AL_3" id="FNanchor_AL_3"></a><a href="#Footnote_AL_3" class="fnanchor">[475-B]</a> We may easily suppose, therefore, that all traces of shells
+and other organic remains may be destroyed; and that new chemical
+combinations may arise, without the mass being so fused as that the lines
+of stratification should be wholly obliterated.</p>
+
+<p>We must not, however, imagine that heat alone, such as may be applied to a
+stone in the open air, can constitute all that is comprised in plutonic
+action. We know that volcanos in eruption not only emit fluid lava, but
+give off steam and other heated gases, which rush out in enormous volume,
+for days, weeks, or years continuously, and are even disengaged from lava
+during its consolidation. When the materials of granite, therefore, came in
+contact with the fossiliferous stratum <span class="pagenum"><a id="page476"></a>[p.476]</span>in the bowels of the earth
+under great pressure, the contained gases might be unable to escape; yet
+when brought into contact with rocks, might pass through their pores with
+greater facility than water is known to do (<a href="#page35">p. 35.</a>). These a�riform fluids,
+such as sulphuretted hydrogen, muriatic acid, and carbonic acid, issue in
+many places from rents in rocks, which they have discoloured and corroded,
+softening some and hardening others. If the rocks are charged with water,
+they would pass through more readily; for, according to the experiments of
+Henry, water, under an hydrostatic pressure of 96 feet, will absorb three
+times as much carbonic acid gas as it can under the ordinary pressure of
+the atmosphere. Although this increased power of absorption would be
+diminished, in consequence of the higher temperature found to exist as we
+descend in the earth, yet Professor Bischoff has shown that the heat by no
+means augments in such a proportion as to counteract the effect of
+augmented pressure.<a name="FNanchor_AL_4" id="FNanchor_AL_4"></a><a href="#Footnote_AL_4" class="fnanchor">[476-A]</a> There are other gases, as well as the carbonic
+acid, which water absorbs, and more rapidly in proportion to the amount of
+pressure. Now even the most compact rocks may be regarded, before they have
+been exposed to the air and dried, in the light of sponges filled with
+water; and it is conceivable that heated gases brought into contact with
+them, at great depths, may be absorbed readily, and transfused through
+their pores. Although the gaseous matter first observed would soon be
+condensed, and part with its heat, yet the continual arrival of fresh
+supplies from below might, in the course of ages, cause the temperature of
+the water, and with it that of the containing rock, to be materially
+raised.</p>
+
+<p>M. Fournet, in his description of the metalliferous gneiss near Clermont,
+in Auvergne, states that all the minute fissures of the rock are quite
+saturated with free carbonic acid gas, which rises plentifully from the
+soil there and in many parts of the surrounding country. The various
+elements of the gneiss, with the exception of the quartz, are all softened;
+and new combinations of the acid, with lime, iron, and manganese, are
+continually in progress.<a name="FNanchor_AL_5" id="FNanchor_AL_5"></a><a href="#Footnote_AL_5" class="fnanchor">[476-B]</a></p>
+
+<p>Another illustration of the power of subterranean gases is afforded by the
+stufas of St. Calogero, situated in the largest of the Lipari Islands.
+Here, according to the description published by Hoffmann, horizontal strata
+of tuff, extending for 4 miles along the coast, and forming cliffs more
+than 200 feet high, have been discoloured in various places, and strangely
+altered by the "all-penetrating vapours." Dark clays have become yellow, or
+often snow-white; or have assumed a chequered or brecciated appearance,
+being crossed with ferruginous red stripes. In some places the fumaroles
+have been found by analysis to consist partly of sublimations of oxide of
+iron; but it also appears that veins of chalcedony and opal, and others of
+fibrous gypsum, have resulted from these volcanic exhalations.<a name="FNanchor_AL_6" id="FNanchor_AL_6"></a><a href="#Footnote_AL_6" class="fnanchor">[476-C]</a></p>
+
+<p><span class="pagenum"><a id="page477"></a>[p.477]</span>The reader may also refer to M. Virlet's account of the corrosion
+of hard, flinty, and jaspideous rocks near Corinth, by the prolonged agency
+of subterranean gases<a name="FNanchor_AL_7" id="FNanchor_AL_7"></a><a href="#Footnote_AL_7" class="fnanchor">[477-A]</a>; and to Dr. Daubeny's description of the
+decomposition of trachytic rocks in the Solfatara, near Naples, by
+sulphuretted hydrogen and muriatic acid gases.<a name="FNanchor_AL_8" id="FNanchor_AL_8"></a><a href="#Footnote_AL_8" class="fnanchor">[477-B]</a></p>
+
+<p>Although in all these instances we can only study the phenomena as
+exhibited at the surface, it is clear that the gaseous fluids must have
+made their way through the whole thickness of porous or fissured rocks,
+which intervene between the subterranean reservoirs of gas and the external
+air. The extent, therefore, of the earth's crust, which the vapours have
+permeated and are now permeating, may be thousands of fathoms in thickness,
+and their heating and modifying influence may be spread throughout the
+whole of this solid mass.</p>
+
+<p>We learn from Professor Bischoff that the steam of a hot spring at
+Aix-la-Chapelle, although its temperature is only from 133� to 167� F., has
+converted the surface of some blocks of black marble into a doughy mass. He
+conceives, therefore, that steam in the bowels of the earth having a
+temperature equal or even greater than the melting point of lava, and
+having an elasticity of which even Papin's digester can give but a faint
+idea, may convert rocks into liquid matter.<a name="FNanchor_AL_9" id="FNanchor_AL_9"></a><a href="#Footnote_AL_9" class="fnanchor">[477-C]</a></p>
+
+<p>The above observations are calculated to meet some of the objections which
+have been urged against the metamorphic theory on the ground of the small
+power of rocks to conduct heat; for it is well known that rocks, when dry
+and in the air, differ remarkably from metals in this respect. It has been
+asked how the changes which extend merely for a few feet from the contact
+of a dike could have penetrated through mountain masses of crystalline
+strata several miles in thickness. Now it has been stated that the plutonic
+influence of the syenite of Norway has sometimes altered fossiliferous
+strata for a distance of a quarter of a mile, both in the direction of
+their dip and of their strike. (See <a href="#img488">fig. 512.</a> <a href="#page474">p. 474.</a>) This is undoubtedly
+an extreme case; but is it not far more philosophical to suppose that this
+influence may, under favourable circumstances, affect denser masses, than
+to invent an entirely new cause to account for effects merely differing in
+quantity, and not in kind? The metamorphic theory does not require us to
+affirm that some contiguous mass of granite has been the altering power;
+but merely that an action, existing in the interior of the earth at an
+unknown depth, whether thermal, electrical, or other, analogous to that
+exerted near intruding masses of granite, has, in the course of vast and
+indefinite periods, and when rising perhaps from a large heated surface,
+reduced strata thousands of yards thick to a state of semi-fusion, so that
+on cooling they have become crystalline, like gneiss. Granite may have been
+another result of the same action in a higher state of intensity, by which
+a thorough fusion has been produced; <span class="pagenum"><a id="page478"></a>[p.478]</span>and in this manner the
+passage from granite into gneiss may be explained.</p>
+
+<p>Some geologists are of opinion, that the alternate layers of mica and
+quartz, or mica and felspar, or lime and felspar, are so much more
+distinct, in certain metamorphic rocks, than the ingredients composing
+alternate layers in many sedimentary deposits, that the similar particles
+must be supposed to have exerted a molecular attraction for each other, and
+to have thus congregated together in layers more distinct in mineral
+composition than before they were crystallized.</p>
+
+<p>In considering, then, the various data already enumerated, the forms of
+stratification in metamorphic rocks, their passage on the one hand into the
+fossiliferous, and on the other into the plutonic formations, and the
+conversions which can be ascertained to have occurred in the vicinity of
+granite, we may conclude that gneiss and mica-schist may be nothing more
+than altered micaceous and argillaceous sandstones that granular quartz may
+have been derived from siliceous sandstone, and compact quartz from the
+same materials. Clay-slate may be altered shale, and granular marble may
+have originated in the form of ordinary limestone, replete with shells and
+corals, which have since been obliterated; and, lastly, calcareous sands
+and marls may have been changed into impure crystalline limestones.</p>
+
+<p>"Hornblende-schist," says Dr. MacCulloch, "may at first have been mere
+clay; for clay or shale is found altered by trap into Lydian stone, a
+substance differing from hornblende-schist almost solely in compactness and
+uniformity of texture."<a name="FNanchor_AL_10" id="FNanchor_AL_10"></a><a href="#Footnote_AL_10" class="fnanchor">[478-A]</a> "In Shetland," remarks the same author,
+"argillaceous-schist (or clay-slate), when in contact with granite, is
+sometimes converted into hornblende-schist, the schist becoming first
+siliceous, and ultimately, at the contact, hornblende-schist."<a name="FNanchor_AL_11" id="FNanchor_AL_11"></a><a href="#Footnote_AL_11" class="fnanchor">[478-B]</a></p>
+
+<p>The anthracite and plumbago associated with hypogene rocks may have been
+coal; for not only is coal converted into anthracite in the vicinity of
+some trap dikes, but we have seen that a like change has taken place
+generally even far from the contact of igneous rocks, in the disturbed
+region of the Appalachians.<a name="FNanchor_AL_12" id="FNanchor_AL_12"></a><a href="#Footnote_AL_12" class="fnanchor">[478-C]</a> At Worcester, in the state of
+Massachusetts, 45 miles due west of Boston, a bed of plumbago and impure
+anthracite occurs, interstratified with mica-schist. It is about 2 feet in
+thickness, and has been made use of both as fuel, and in the manufacture of
+lead pencils. At the distance of 30 miles from the plumbago, there occurs,
+on the borders of Rhode Island, an impure anthracite in slates, containing
+impressions of coal-plants of the genera <i>Pecopteris</i>, <i>Neuropteris</i>,
+<i>Calamites</i>, &amp;c. This anthracite is intermediate in character between that
+of Pennsylvania and the plumbago of Worcester, in which last the gaseous or
+volatile matter (hydrogen, oxygen, and nitrogen) is to the carbon only in
+the proportion of 3 per cent. After traversing the country in various
+<span class="pagenum"><a id="page479"></a>[p.479]</span>directions, I came to the conclusion that the carboniferous
+shales or slates with anthracite and plants, which in Rhode Island often
+pass into mica-schist, have at Worcester assumed a perfectly crystalline
+and metamorphic texture; the anthracite having been nearly transmuted into
+that state of pure carbon which is called plumbago or graphite.<a name="FNanchor_AL_13" id="FNanchor_AL_13"></a><a href="#Footnote_AL_13" class="fnanchor">[479-A]</a></p>
+
+<p>The total absence of any trace of fossils has inclined many geologists to
+attribute the origin of crystalline strata to a period antecedent to the
+existence of organic beings. Admitting, they say, the obliteration, in some
+cases, of fossils by plutonic action, we might still expect that traces of
+them would oftener occur in certain ancient systems of slate, in which, as
+in Cumberland, some conglomerates occur. But in urging this argument, it
+seems to have been forgotten that there are stratified formations of
+enormous thickness, and of various ages, and some of them very modern, all
+formed after the earth had become the abode of living creatures, which are,
+nevertheless, in certain districts, entirely destitute of all vestiges of
+organic bodies. In some, the traces of fossils may have been effaced by
+water and acids, at many successive periods; and it is clear, that, the
+older the stratum, the greater is the chance of its being
+non-fossiliferous, even if it has escaped all metamorphic action.</p>
+
+<p>It has been also objected to the metamorphic theory, that the chemical
+composition of the secondary strata differs essentially from that of the
+crystalline schists, into which they are supposed to be convertible.<a name="FNanchor_AL_14" id="FNanchor_AL_14"></a><a href="#Footnote_AL_14" class="fnanchor">[479-B]</a>
+The "primary" schists, it is said, usually contain a considerable
+proportion of potash or of soda, which the secondary clays, shales, and
+slates do not, these last being the result of the decomposition of
+felspathic rocks, from which the alkaline matter has been abstracted during
+the process of decomposition. But this reasoning proceeds on insufficient
+and apparently mistaken data; for a large portion of what is usually called
+clay, marl, shale, and slate does actually contain a certain, and often a
+considerable, proportion of alkali; so that it is difficult, in many
+countries, to obtain clay or shale sufficiently free from alkaline
+ingredients to allow of their being burnt into bricks or used for pottery.</p>
+
+<p>Thus the argillaceous shales and slates of the Old Red sandstone, in
+Forfarshire and other parts of Scotland, are so much charged with alkali,
+derived from triturated felspar, that, instead of hardening when exposed to
+fire, they sometimes melt into a glass. They contain no lime, but appear to
+consist of extremely minute grains of the various ingredients of granite,
+which are distinctly visible in the coarser-grained varieties, and in
+almost all the interposed sandstones. These laminated clays and shales
+might certainly, if crystallized, resemble in composition many of the
+primary strata.</p>
+
+<p>There is also potash in fossil vegetable remains, and soda in the salts by
+which strata are sometimes so largely impregnated, as in Patagonia.</p>
+
+<p><span class="pagenum"><a id="page480"></a>[p.480]</span>Another objection has been derived from the alternation of highly
+crystalline strata with others having a less crystalline texture. The heat,
+it is said, in its ascent from below, must have traversed the less altered
+schists before it reached a higher and more crystalline bed. In answer to
+this, it may be observed, that if a number of strata differing greatly in
+composition from each other be subjected to equal quantities of heat, there
+is every probability that some will be more fusible than others. Some, for
+example, will contain soda, potash, lime, or some other ingredient capable
+of acting as a flux; while others may be destitute of the same elements,
+and so refractory as to be very slightly affected by a degree of heat
+capable of reducing others to semi-fusion. Nor should it be forgotten that,
+as a general rule, the less crystalline rocks do really occur in the upper,
+and the more crystalline in the lower part of each metamorphic series.</p>
+
+<p>There are geologists, however, of high authority, who admit the metamorphic
+origin of gneiss and mica-schist even on a grand scale in some
+mountain-chains, and who nevertheless believe that gneiss has in some
+instances been an eruptive rock, deriving its lamination from motion when
+in a fluid or viscous state. Mr. Scrope, in his description of the Ponza
+Islands, ascribes "the zoned structure of the Hungarian perlite (a
+semi-vitreous trachyte) to its having subsided, in obedience to the impulse
+of its own gravity, down a slightly inclined plane, while possessed of an
+imperfect fluidity. In the islands of Ponza and Palmarola, the direction of
+the zones is more frequently vertical than horizontal, because the mass was
+impelled from below upwards."<a name="FNanchor_AL_15" id="FNanchor_AL_15"></a><a href="#Footnote_AL_15" class="fnanchor">[480-A]</a> In like manner, Mr. Darwin attributes
+the lamination and fissile structure of volcanic rocks of the trachytic
+series, including some obsidians in Ascension, Mexico, and elsewhere, to
+their having moved when liquid in the direction of the lamin�. The zones
+consist sometimes of layers of air-cells drawn out and lengthened in the
+supposed direction of the moving mass. He compares this division into
+parallel zones, thus caused by the stretching of a pasty mass as it flowed
+slowly onwards, to the zoned or ribboned structure of ice, which Professor
+James Forbes has so ably explained, showing that it is due to the fissuring
+of a viscous body in motion.<a name="FNanchor_AL_16" id="FNanchor_AL_16"></a><a href="#Footnote_AL_16" class="fnanchor">[480-B]</a> Mr. Darwin also imagines the lamination
+or <i>foliation</i>, as he terms it, of gneiss and mica-schist in South America
+to be the extreme result of that process of which cleavage is the first
+effect.<a name="FNanchor_AL_17" id="FNanchor_AL_17"></a><a href="#Footnote_AL_17" class="fnanchor">[480-C]</a></p>
+
+<p>M. Elie de Beaumont, while he regards the greater part of the gneiss and
+mica-schist of the Alps as sedimentary strata altered by plutonic action,
+still conceives that some of the Alpine gneiss may have been erupted, or,
+in other words, may be granite drawn out into parallel lamin� in the manner
+of trachyte as above alluded to.<a name="FNanchor_AL_18" id="FNanchor_AL_18"></a><a href="#Footnote_AL_18" class="fnanchor">[480-D]</a></p>
+
+<p>Opinions such as these, and others which might be cited, prove the
+difficulty of arriving at clear theoretical views on this subject. I
+<span class="pagenum"><a id="page481"></a>[p.481]</span>may also add another difficulty. In many extensive regions
+experienced geologists have been at a loss to decide which of two sets of
+divisional planes were referable to cleavage and which to stratification;
+and that, too, where the rocks are of undisputed aqueous origin. After much
+doubt, they have sometimes discovered that they had at first mistaken the
+lines of cleavage for those of deposition, because the former were by far
+the most marked of the two. Now if such slaty masses should become highly
+crystalline, and be converted into gneiss, hornblende-schist, or any other
+member of the hypogene class, the cleavage planes would be more likely to
+remain visible than those of stratification.</p>
+
+<p>But although the cause last-mentioned may, in some instances, be a "vera
+causa," as applied to gneiss and mica-schist, I believe it to be an
+exception to the general rule. Nor would it, I conceive, produce that kind
+of irregular parallelism in the lamin� which belongs to so many of the
+hypogene rocks of the Grampians, Pyrenees, and the White mountains of North
+America, where I have chiefly studied them.</p>
+
+<p>But it will be impossible for the reader duly to appreciate the propriety
+of the term metamorphic, as applied to the strata formerly called
+primitive, until I have shown, in the next chapter, at how many distinct
+periods these crystalline strata have been formed.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XXXVII.</h2>
+
+<h4>ON THE DIFFERENT AGES OF THE METAMORPHIC ROCKS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Age of each set of metamorphic strata twofold &mdash; Test of age by
+fossils and mineral character not available &mdash; Test by superposition
+ambiguous &mdash; Conversion of dense masses of fossiliferous strata into
+metamorphic rocks &mdash; Limestone and shale of Carrara &mdash;
+Metamorphic strata of modern periods in the Alps of Switzerland and Savoy
+&mdash; Why the visible crystalline strata are none of them very modern
+&mdash; Order of succession in metamorphic rocks &mdash; Uniformity of
+mineral character &mdash; Why the metamorphic strata are less calcareous
+than the fossiliferous.</p></div>
+
+
+<p><span class="smcap">According</span> to the theory adopted in the last chapter, the age of each set of
+metamorphic strata is twofold&mdash;they have been deposited at one period, they
+have become crystalline at another. We can rarely hope to define with
+exactness the date of both these periods, the fossils having been destroyed
+by plutonic action, and the mineral characters being the same, whatever the
+age. Superposition itself is an ambiguous test, especially when we desire
+to determine the period of crystallization. Suppose, for example, we are
+convinced that certain metamorphic strata in the Alps, which are covered by
+cretaceous beds, are altered lias; this lias may have assumed its
+crystalline texture in the cretaceous or in some tertiary period, the
+Eocene for example. If in the latter, it should be called Eocene when
+regarded as a metamorphic rock, although it be liassic when considered in
+reference to <span class="pagenum"><a id="page482"></a>[p.482]</span>the era of its deposition. According to this view,
+the superposition of chalk does not prevent the subjacent <i>metamorphic</i>
+rock from being Eocene. If, however, in the progress of science, we should
+succeed in ascertaining the twofold chronological relations of the
+metamorphic formations, it might be useful to adopt a twofold terminology.
+We might call the strata above alluded to Liassic-Eocene, or
+Liassic-Cretaceous strata of the Hypogene class; the first term referring
+to the era of deposition, the second to that of crystallization.</p>
+
+<p>When discussing the ages of the plutonic rocks, we have seen that examples
+occur of various primary, secondary, and tertiary deposits converted into
+metamorphic strata, near their contact with granite. There can be no doubt
+in these cases that strata, once composed of mud, sand, and gravel, or of
+clay, marl, and shelly limestone, have for the distance of several yards,
+and in some instances several hundred feet, been turned into gneiss,
+mica-schist, hornblende-schist, chlorite-schist, quartz rock, statuary
+marble, and the rest. (See the two <a href="#chaxxxv">preceding Chapters</a>.)</p>
+
+<p>But when the metamorphic action has operated on a grander scale, it tends
+entirely to destroy all monuments of the date of its development. It may be
+easy to prove the identity of two different parts of the same stratum; one,
+where the rock has been in contact with a volcanic or plutonic mass, and
+has been changed into marble or hornblende-schist, and another not far
+distant, where the same bed remains unaltered and fossiliferous; but when
+we have to compare two portions of a mountain chain&mdash;the one metamorphic,
+and the other unaltered&mdash;all the labour and skill of the most practised
+observers are required. I shall mention one or two examples of alteration
+on a grand scale, in order to explain to the student the kind of reasoning
+by which we are led to infer that dense masses of fossiliferous strata have
+been converted into crystalline rocks.</p>
+
+<p><i>Northern Apennines&mdash;Carrara.</i>&mdash;The celebrated marble of Carrara, used in
+sculpture, was once regarded as a type of primitive limestone. It abounds
+in the mountains of Massa Carrara, or the "Apuan Alps," as they have been
+called, the highest peaks of which are nearly 6000 feet high. Its great
+antiquity was inferred from its mineral texture, from the absence of
+fossils, and its passage downwards into talc-schist and garnetiferous
+mica-schist; these rocks again graduating downwards into gneiss, which is
+penetrated, at Forno, by granite veins. Now the researches of MM. Savi,
+Bou�, Pareto, Guidoni, De la Beche, Hoffmann, and Pilla, have demonstrated
+that this marble, once supposed to be formed before the existence of
+organic beings, is, in fact, an altered limestone of the Oolitic period,
+and the underlying crystalline schists are secondary sandstones and shales,
+modified by plutonic action. In order to establish these conclusions it was
+first pointed out, that the calcareous rocks bordering the Gulf of Spezia,
+and abounding in Oolitic fossils, assume a texture like that of Carrara
+marble, in proportion as they are more and more invaded by certain trappean
+and plutonic rocks, such as diorite, euphotide, serpentine, and granite,
+occurring in the same country.</p>
+
+<p>It was then observed that, in places where the secondary formations
+<span class="pagenum"><a id="page483"></a>[p.483]</span>are unaltered, the uppermost consist of common Apennine limestone
+with nodules of flint, below which are shales, and at the base of all,
+argillaceous and siliceous sandstones. In the limestone, fossils are
+frequent, but very rare in the underlying shale and sandstone. Then a
+gradation was traced laterally from these rocks into another and
+corresponding series, which is completely metamorphic; for at the top of
+this we find a white granular marble, wholly devoid of fossils, and almost
+without stratification, in which there are no nodules of flint, but in its
+place siliceous matter disseminated through the mass in the form of prisms
+of quartz. Below this, and in place of the shales, are talc-schists,
+jasper, and hornstone; and at the bottom, instead of the siliceous and
+argillaceous sandstones, are quartzite and gneiss.<a name="FNanchor_AM_1" id="FNanchor_AM_1"></a><a href="#Footnote_AM_1" class="fnanchor">[483-A]</a> Had these
+secondary strata of the Apennines undergone universally as great an amount
+of transmutation, it would have been impossible to form a conjecture
+respecting their true age; and then, according to the common method of
+geological classification, they would have ranked as primary rocks. In that
+case the date of their origin would have been thrown back to an era
+antecedent to the deposition of the Lower Silurian or Cambrian strata,
+although in reality they were formed in the Oolitic period, and altered at
+some subsequent and perhaps much later epoch.</p>
+
+<p><i>Alps of Switzerland.</i>&mdash;In the Alps, analogous conclusions have been drawn
+respecting the alteration of strata on a still more extended scale. In the
+eastern part of that chain, some of the primary fossiliferous strata, as
+well as the older secondary formations, together with the oolitic and
+cretaceous rocks, are distinctly recognizable. Tertiary deposits also
+appear in a less elevated position on the flanks of the Eastern Alps; but
+in the Central or Swiss Alps, the primary fossiliferous and older secondary
+formations disappear, and the Cretaceous, Oolitic, Liassic, and at some
+points even the Eocene strata, graduate insensibly into metamorphic rocks,
+consisting of granular limestone, talc-schist, talcose-gneiss, micaceous
+schist, and other varieties. In regard to the age of this vast assemblage
+of crystalline strata, we can merely affirm that some of the upper portions
+are altered newer secondary, and some of them even Eocene deposits; but we
+cannot avoid suspecting that the disappearance both of the older secondary
+and primary fossiliferous rocks may be owing to their having been all
+converted in this region into crystalline schist.</p>
+
+<p>It is difficult to convey to those who have never visited the Alps a just
+idea of the various proofs which concur to produce this conviction. In the
+first place, there are certain regions where Oolitic, Cretaceous, and
+Eocene strata have been turned into granular marble, gneiss, and other
+metamorphic schists, near their contact with granite. This fact shows
+undeniably that plutonic causes continued to be in operation in the Alps
+down to a late period, even after the deposition of some of the nummulitic
+or older Eocene formations. <span class="pagenum"><a id="page484"></a>[p.484]</span>Having established this point, we are
+the more willing to believe that many inferior fossiliferous rocks,
+probably exposed for longer periods to a similar action, may have become
+metamorphic to a still greater extent.</p>
+
+<p>We also discover in parts of the Swiss Alps dense masses of secondary and
+even tertiary strata, which have assumed that semi-crystalline texture
+which Werner called transition, and which naturally led his followers, who
+attached great importance to mineral characters taken alone, to class them
+as transition formations, or as groups older than the lowest secondary
+rocks. (See <a href="#page92">p. 92.</a>) Now, it is probable that these strata have been
+affected, although in a less intense degree, by that same plutonic action
+which has entirely altered and rendered metamorphic so many of the
+subjacent formations; for in the Alps, this action has by no means been
+confined to the immediate vicinity of granite. Granite, indeed, and other
+plutonic rocks, rarely make their appearance at the surface,
+notwithstanding the deep ravines which lay open to view the internal
+structure of these mountains. That they exist below at no great depth we
+cannot doubt, and we have already seen (<a href="#page445">p. 445.</a>) that at some points, as in
+the Valorsine, near Mont Blanc, granite and granitic veins are observable,
+piercing through talcose gneiss, which passes insensibly upwards into
+secondary strata.</p>
+
+<p>It is certainly in the Alps of Switzerland and Savoy, more than in any
+other district in Europe, that the geologist is prepared to meet with the
+signs of an intense development of plutonic action; for here we find the
+most stupendous monuments of mechanical violence, by which strata thousands
+of feet thick have been bent, folded, and overturned. (See <a href="#page58">p. 58.</a>) It is
+here that marine secondary formations of a comparatively modern date, such
+as the Oolitic and Cretaceous, have been upheaved to the height of 12,000,
+and some Eocene strata to elevations of 10,000 feet above the level of the
+sea; and even deposits of the Miocene era have been raised 4000 or 5000
+feet, so as to rival in height the loftiest mountains in Great Britain.</p>
+
+<p>If the reader will consult the works of many eminent geologists who have
+explored the Alps, especially those of MM. De Beaumont, Studer, Necker,
+Bou�, and Murchison, he will learn that they all share, more or less fully,
+in the opinions above expressed. It has, indeed, been stated by MM. Studer
+and Hugi, that there are complete alternations on a large scale of
+secondary strata, containing fossils, with gneiss and other rocks, of a
+perfectly metamorphic structure. I have visited some of the most remarkable
+localities referred to by these authors; but although agreeing with them
+that there are passages from the fossiliferous to the metamorphic series
+far from the contact of granite or other plutonic rocks, I was unable to
+convince myself that the distinct alternations of highly crystalline, with
+unaltered strata above alluded to, might not admit of a different
+explanation. In one of the sections described by M. Studer in the highest
+of the Bernese Alps, namely in the Roththal, a valley bordering the line of
+perpetual snow on the northern side of the Jungfrau, there <span class="pagenum"><a id="page485"></a>[p.485]</span>occurs
+a mass of gneiss 1000 feet thick, and 15,000 feet long, which I examined,
+not only resting upon, but also again covered by strata containing oolitic
+fossils. These anomalous appearances may partly be explained by supposing
+great solid wedges of intrusive gneiss to have been forced in laterally
+between strata to which I found them to be in many sections unconformable.
+The superposition, also, of the gneiss to the oolite may, in some cases, be
+due to a reversal of the original position of the beds in a region where
+the convulsions have been on so stupendous a scale.</p>
+
+<p>On the Sattel also, at the base of the Gestellihorn, above Enzen, in the
+valley of Urbach, near Meyringen, some of the intercalations of gneiss
+between fossiliferous strata may, I conceive, be ascribed to mechanical
+derangement. Almost any hypothesis of repeated changes of position may be
+resorted to in a region of such extraordinary confusion. The secondary
+strata may first have been vertical, and then certain portions may have
+become metamorphic (the plutonic influence ascending from below), while
+intervening strata remained unchanged. The whole series of beds may then
+again have been thrown into a nearly horizontal position, giving rise to
+the superposition of crystalline upon fossiliferous formations.</p>
+
+<p>It was remarked, in Chap. XXXIV., that as the hypogene rocks, both
+stratified and unstratified, crystallize originally at a certain depth
+beneath the surface, they must always, before they are upraised and exposed
+at the surface, be of considerable antiquity, relatively to a large portion
+of the fossiliferous and volcanic rocks. They may be forming at all
+periods; but before any of them can become visible, they must be raised
+above the level of the sea, and some of the rocks which previously
+concealed them must have been removed by denudation.</p>
+
+<p><i>Order of succession in metamorphic rocks.</i>&mdash;There is no universal and
+invariable order of superposition in metamorphic rocks, although a
+particular arrangement may prevail throughout countries of great extent,
+for the same reason that it is traceable in those sedimentary formations
+from which crystalline strata are derived. Thus, for example, we have seen
+that in the Apennines, near Carrara, the descending series, where it is
+metamorphic, consists of, 1st, saccharine marble; 2dly, talcose-schist; and
+3dly, of quartz-rock and gneiss; where unaltered, of, 1st, fossiliferous
+limestone; 2dly, shale; and 3dly, sandstone.</p>
+
+<p>But if we investigate different mountain chains, we find gneiss,
+mica-schist, hornblende-schist, chlorite-schist, hypogene, limestone, and
+other rocks, succeeding each other, and alternating with each other, in
+every possible order. It is, indeed, more common to meet with some variety
+of clay-slate forming the uppermost member of a metamorphic series than any
+other rock; but this fact by no means implies, as some have imagined, that
+all clay-slates were formed at the close of an imaginary period, when the
+deposition of the crystalline strata gave way to that of ordinary
+sedimentary deposits. Such clay-slates, in fact, are variable in
+composition, and sometimes <span class="pagenum"><a id="page486"></a>[p.486]</span>alternate with fossiliferous strata,
+so that they may be said to belong almost equally to the sedimentary and
+metamorphic order of rocks. It is probable that had they been subjected to
+more intense plutonic action, they would have been transformed into
+hornblende-schist, foliated chlorite-schist, scaly talcose-schist,
+mica-schist, or other more perfectly crystalline rocks, such as are usually
+associated with gneiss.</p>
+
+<p><i>Uniformity of mineral character in Hypogene rocks.</i>&mdash;Humboldt has
+emphatically remarked, that when we pass to another hemisphere, we see new
+forms of animals and plants, and even new constellations in the heavens;
+but in the rocks we still recognize our old acquaintances,&mdash;the same
+granite, the same gneiss, the same micaceous schist, quartz-rock, and the
+rest. It is certainly true that there is a great and striking general
+resemblance in the principal kinds of hypogene rocks, although of very
+different ages and countries; but it has been shown that each of these are,
+in fact, geological families of rocks, and not definite mineral compounds.
+They are much more uniform in aspect than sedimentary strata, because these
+last are often composed of fragments varying greatly in form, size, and
+colour, and contain fossils of different shapes and mineral composition,
+and acquire a variety of tints from the mixture of various kinds of
+sediment. The materials of such strata, if melted and made to crystallize,
+would be subject to chemical laws, simple and uniform in their action, the
+same in every climate, and wholly undisturbed by mechanical and organic
+causes.</p>
+
+<p>Nevertheless, it would be a great error to assume that the hypogene rocks,
+considered as aggregates of simple minerals, are really more homogeneous in
+their composition than the several members of the sedimentary series. In
+the first place, different assemblages of hypogene rocks occur in different
+countries; and, secondly, in any one district, the rocks which pass under
+the same name are often extremely variable in their component ingredients,
+or at least in the proportions in which each of these are present. Thus,
+for example, gneiss and mica-schist, so abundant in the Grampians, are
+wanting in Cumberland, Wales, and Cornwall; in parts of the Swiss and
+Italian Alps, the gneiss and granite are talcose, and not micaceous, as in
+Scotland; hornblende prevails in the granite of Scotland&mdash;schorl in that of
+Cornwall&mdash;albite in the plutonic rocks of the Andes&mdash;common felspar in
+those of Europe. In one part of Scotland, the mica-schist is full of
+garnets; in another it is wholly devoid of them: while in South America,
+according to Mr. Darwin, it is the gneiss, and not the mica-schist, which
+is most commonly garnetiferous. And not only do the proportional quantities
+of felspar, quartz, mica, hornblende, and other minerals, vary in hypogene
+rocks bearing the same name; but what is still more important, the
+ingredients, as we have seen, of the same simple mineral are not always
+constant (<a href="#page369">p. 369.</a>, and table, <a href="#page377">p. 377.</a>).</p>
+
+<p><i>The Metamorphic strata, why less calcareous than the fossiliferous.</i>&mdash;It
+has been remarked, that the quantity of calcareous matter in metamorphic
+strata, or, indeed, in the hypogene formations generally, <span class="pagenum"><a id="page487"></a>[p.487]</span>is far
+less than in fossiliferous deposits. Thus the crystalline schists of the
+Grampians in Scotland, consisting of gneiss, mica-schist,
+hornblende-schist, and other rocks, many thousands of yards in thickness,
+contain an exceedingly small proportion of interstratified calcareous beds,
+although these have been the objects of careful search for economical
+purposes. Yet limestone is not wanting in the Grampians, and it is
+associated sometimes with gneiss, sometimes with mica-schist, and in other
+places with other members of the metamorphic series. But where limestone
+occurs abundantly, as at Carrara, and in parts of the Alps, in connection
+with hypogene rocks, it usually forms one of the superior members of the
+crystalline group.</p>
+
+<p>The scarcity, then, of carbonate of lime in the plutonic and metamorphic
+rocks generally, seems to be the result of some general cause. So long as
+the hypogene rocks were believed to have originated antecedently to the
+creation of organic beings, it was easy to impute the absence of lime to
+the non-existence of those mollusca and zoophytes by which shells and
+corals are secreted; but when we ascribe the crystalline formations to
+plutonic action, it is natural to inquire whether this action itself may
+not tend to expel carbonic acid and lime from the materials which it
+reduces to fusion or semi-fusion. Although we cannot descend into the
+subterranean regions where volcanic heat is developed, we can observe in
+regions of spent volcanos, such as Auvergne and Tuscany, hundreds of
+springs, both cold and thermal, flowing out from granite and other rocks,
+and having their waters plentifully charged with carbonate of lime. The
+quantity of calcareous matter which these springs transfer, in the course
+of ages, from the lower parts of the earth's crust to the superior or newly
+formed parts of the same, must be considerable.<a name="FNanchor_AM_2" id="FNanchor_AM_2"></a><a href="#Footnote_AM_2" class="fnanchor">[487-A]</a></p>
+
+<p>If the quantity of siliceous and aluminous ingredients brought up by such
+springs were great, instead of being utterly insignificant, it might be
+contended that the mineral matter thus expelled implies simply the
+decomposition of ordinary subterranean rocks; but the prodigious excess of
+carbonate of lime over every other element must, in the course of time,
+cause the crust of the earth below to be almost entirely deprived of its
+calcareous constituents, while we know that the same action imparts to
+newer deposits, ever forming in seas and lakes, an excess of carbonate of
+lime. Calcareous matter is poured into these lakes, and the ocean, by a
+thousand springs and rivers; so that part of almost every new calcareous
+rock chemically precipitated, and of many reefs of shelly and coralline
+stone, must be derived from mineral matter subtracted by plutonic agency,
+and driven up by gas and steam from fused and heated rocks in the bowels of
+the earth.</p>
+
+<p>Not only carbonate of lime, but also free carbonic acid gas is given off
+plentifully from the soil and crevices of rocks in regions of active and
+spent volcanos, as near Naples, and in Auvergne. By this process, fossil
+shells or corals may often lose their carbonic acid, and the residual lime
+may enter into the composition of augite, hornblende, garnet, <span class="pagenum"><a id="page488"></a>[p.488]</span>and
+other hypogene minerals. That the removal of the calcareous matter of
+fossil shells is of frequent occurrence, is proved by the fact of such
+organic remains being often replaced by silex or other minerals, and
+sometimes by the space once occupied by the fossil being left empty, or
+only marked by a faint impression. We ought not indeed to marvel at the
+general absence of organic remains from the crystalline strata, when we
+bear in mind how often fossils are obliterated, wholly or in part, even in
+tertiary formations&mdash;how often vast masses of sandstone and shale, of
+different ages, and thousands of feet thick, are devoid of fossils&mdash;how
+certain strata may first have been deprived of a portion of their fossils
+when they became semi-crystalline, or assumed the <i>transition</i> state of
+Werner&mdash;and how the remaining organic remains have been effaced when they
+were rendered metamorphic. Some rocks of the last-mentioned class,
+moreover, must have been exposed again and again to renewed plutonic
+action.</p>
+
+
+
+
+<hr class="sep2">
+<h2>CHAPTER XXXVIII.</h2>
+
+<h4>MINERAL VEINS.</h4>
+
+<div class="blq1">
+<p class="indentm2">Werner's doctrine that mineral veins were fissures filled from above
+&mdash; Veins of segregation &mdash; Ordinary metalliferous veins or lodes
+&mdash; Their frequent coincidence with faults &mdash; Proofs that they
+originated in fissures in solid rock &mdash; Veins shifting other veins
+&mdash; Polishing of their walls &mdash; Shells and pebbles in lodes
+&mdash; Evidence of the successive enlargement and re-opening of veins
+&mdash; Fournet's observations in Auvergne &mdash; Dimensions of veins
+&mdash; Why some alternately swell out and contract &mdash; Filling of
+lodes by sublimation from below &mdash; Chemical and electrical action
+&mdash; Relative age of the precious metals &mdash; Copper and lead veins
+in Ireland older than Cornish tin &mdash; Lead vein in lias, Glamorganshire
+&mdash; Gold in Russia &mdash; Connection of hot springs and mineral veins
+&mdash; Concluding remarks.</p></div>
+
+
+<p><span class="smcap">The</span> manner in which metallic substances are distributed through the earth's
+crust, and more especially the phenomena of those nearly vertical and
+tabular masses of ore called mineral veins, from which the larger part of
+the precious metals used by man are obtained,&mdash;these are subjects of the
+highest practical importance to the miner, and of no less theoretical
+interest to the geologist.</p>
+
+<p>The views entertained respecting metalliferous veins have been modified,
+or, rather, have undergone an almost complete revolution, since the middle
+of the last century, when Werner, as director of the School of Mines, at
+Freiberg in Saxony, first attempted to generalize the facts then known. He
+taught that mineral veins had originally been open fissures which were
+gradually filled up with crystalline and metallic matter, and that many of
+them, after being once filled, had been again enlarged or re-opened. He
+also pointed out that veins thus formed are not all referable to one era,
+but are of various geological dates.</p>
+
+<p><span class="pagenum"><a id="page489"></a>[p.489]</span>Such opinions, although slightly hinted at by earlier writers, had
+never before been generally received, and their announcement by one of high
+authority and great experience constituted an era in the science.
+Nevertheless, I have shown, when tracing, in another work, the history and
+progress of geology, that Werner was far behind some of his predecessors in
+his theory of the volcanic rocks, and less enlightened than his
+contemporary, Dr. Hutton, in his speculations as to the origin of
+granite.<a name="FNanchor_AN_1" id="FNanchor_AN_1"></a><a href="#Footnote_AN_1" class="fnanchor">[489-A]</a> According to him, the plutonic formations, as well as the
+crystalline schists, were substances precipitated from a chaotic fluid in
+some primeval or nascent condition of the planet; and the metals,
+therefore, being closely connected with them, had partaken, according to
+him, of a like mysterious origin. He also held that the trap rocks were
+aqueous deposits, and that dikes of porphyry, greenstone, and basalt, were
+fissures filled with their several contents from above. Hence he naturally
+inferred that mineral veins had derived their component materials from an
+incumbent ocean, rather than from a subterranean source; that these
+materials had been first dissolved in the waters above, instead of having
+risen up by sublimation from lakes and seas of igneous matter below.</p>
+
+<p>In proportion as the hypothesis of a primeval fluid, or "chaotic
+menstruum," was abandoned, in reference to the plutonic formations, and
+when all geologists had come to be of one mind as to the true relation of
+the volcanic and trappean rocks, reasonable hopes began to be entertained
+that the phenomena of mineral veins might be explained by known causes, or
+by chemical, thermal, and electrical agency still at work in the interior
+of the earth. The grounds of this conclusion will be better understood when
+the geological facts brought to light by mining operations have been
+described and explained.</p>
+
+<p><i>On different kinds of mineral veins.</i>&mdash;Every geologist is familiarly
+acquainted with those veins of quartz which abound in hypogene strata,
+forming lenticular masses of limited extent. They are sometimes observed,
+also, in sandstones and shales. Veins of carbonate of lime are equally
+common in fossiliferous rocks, especially in limestones. Such veins appear
+to have once been chinks or small cavities, caused, like cracks in clay, by
+the shrinking of the mass, which has consolidated from a fluid state, or
+has simply contracted its dimensions in passing from a higher to a lower
+temperature. Siliceous, calcareous, and occasionally metallic matters, have
+sometimes found their way simultaneously into such empty spaces, by
+infiltration from the surrounding rocks, or by segregation, as it is often
+termed. Mixed with hot water and steam, metallic ores may have permeated a
+pasty matrix until they reached those receptacles formed by shrinkage, and
+thus gave rise to that irregular assemblage of veins, called by the Germans
+a "stockwerk," in allusion to the different floors on which the mining
+operations are in such cases carried on.</p>
+
+<p>The more ordinary or regular veins are usually worked in vertical <span class="pagenum"><a id="page490"></a>[p.490]</span>
+shafts, and have evidently been fissures produced by mechanical violence.
+They traverse all kinds of rocks, both hypogene and fossiliferous, and
+extend downwards to indefinite or unknown depths. We may assume that they
+correspond with such rents as we see caused from time to time by the shock
+of an earthquake. Metalliferous veins, referable to such agency, are
+occasionally a few inches wide, but more commonly 3 or 4 feet. They hold
+their course continuously in a certain prevailing direction for miles or
+leagues, passing through rocks varying in mineral composition.</p>
+
+<a id="img489" name="img489"></a>
+<div class="floatleft smaller width275">
+<img src="images/img489.jpg" width="275" height="585" alt="" title="">
+<p>Vertical sections of the mine of Huel Peever, Redruth, Cornwall.</p></div>
+
+<p><i>That metalliferous veins were fissures.</i>&mdash;As some intelligent miners,
+after an attentive study of metalliferous veins, have been unable to
+reconcile many of their characteristics with the hypothesis of fissures, I
+shall begin by stating the evidence in its favour. The most striking fact
+perhaps which can be adduced in its support is, the coincidence of a
+considerable proportion of mineral veins with <i>faults</i>, or those
+dislocations of rocks which are indisputably due to mechanical force, as
+above explained (<a href="#page62">p. 62.</a>). There are even proofs in almost every mining
+district of a succession of faults, by which the opposite walls of rents,
+now the receptacles of metallic substances, have suffered displacement.
+Thus, for example, suppose <i>a a</i>, <a href="#img489">fig. 513.</a>, to be a tin lode in Cornwall,
+the term <i>lode</i> being applied to veins containing metallic ores. This lode,
+running east and west, is a yard wide, and is shifted by a copper lode (<i>b
+b</i>), of similar width.</p>
+
+<p>The first fissure (<i>a a</i>) has been filled with various materials, partly of
+chemical origin, such as quartz, fluor-spar, <span class="pagenum"><a id="page491"></a>[p.491]</span>peroxide of tin,
+sulphuret of copper, arsenical pyrites, bismuth, and sulphuret of nickel,
+and partly of mechanical origin, comprising clay and angular fragments or
+detritus of the intersected rocks. The plates of quartz and the ores are,
+in some places, parallel to the vertical sides or walls of the vein, being
+divided from each other by alternating layers of clay, or other earthy
+matter. Occasionally the metallic ores are disseminated in detached masses
+among the veinstones.</p>
+
+<p>It is clear that, after the gradual introduction of the tin and other
+substances, the second rent (<i>b b</i>) was produced by another fracture
+accompanied by a displacement of the rocks along the plane of <i>b b</i>. This
+new opening was then filled with minerals, some of them resembling those in
+<i>a a</i>, as fluor-spar (or fluate of lime) and quartz; others different, the
+copper being plentiful and the tin wanting or very scarce.</p>
+
+<p>We must next suppose the shock of a third earthquake to occur, breaking
+asunder all the rocks along the line c <i>c</i>, <a href="#img489">fig. 514.</a>; the fissure in this
+instance, being only 6 inches wide, and simply filled with clay, derived,
+probably, from the friction of the walls of the rent, or partly, perhaps,
+washed in from above. This new movement has heaved the rock in such a
+manner as to interrupt the continuity of the copper vein (<i>b b</i>), and, at
+the same time, to shift or heave laterally in the same direction a portion
+of the tin vein which had not previously been broken.</p>
+
+<p>Again, in <a href="#img489">fig. 515.</a> we see evidence of a fourth fissure (<i>d d</i>), also
+filled with clay, which has cut through the tin vein (<i>a a</i>), and has
+lifted it slightly upwards towards the south. The various changes here
+represented are not ideal, but are exhibited in a section obtained in
+working an old Cornish mine, long since abandoned, in the parish of
+Redruth, called Huel Peever, and described both by Mr. Williams and Mr.
+Carne.<a name="FNanchor_AN_2" id="FNanchor_AN_2"></a><a href="#Footnote_AN_2" class="fnanchor">[491-A]</a> The principal movement here referred to, or that of <i>c c</i>,
+<a href="#img489">fig. 515.</a>, extends through a space of no less than 84 feet; but in this, as
+in the case of the other three, it will be seen that the outline of the
+country above, or the geographical features of Cornwall, are not affected
+by any of the dislocations, a powerful denuding force having clearly been
+exerted subsequently to all the faults. (See above, <a href="#page69">p. 69.</a>) It is commonly
+said in Cornwall, that there are eight distinct systems of veins which can
+in like manner be referred to as many successive movements or fractures;
+and the German miners of the Hartz Mountains speak also of eight systems of
+veins, referable to as many periods.</p>
+
+<p>Besides the proofs of mechanical action already explained, the opposite
+walls of veins are frequently polished and striated, as if they had
+undergone great friction, and this even in cases where there has been no
+shift. We may attribute such rubbing to a vibratory motion known to
+accompany earthquakes, and to produce trituration on the opposite walls of
+rents. Similar movements have sometimes occurred <span class="pagenum"><a id="page492"></a>[p.492]</span>in mineral veins
+which had been wholly or partially filled up; for included pieces of rock,
+detached from the sides, are found to be rounded, polished, and striated.</p>
+
+<p>That a great many veins communicated originally with the surface of the
+country above, or with the bed of the sea, is proved by the occurrence in
+them of well rounded pebbles, agreeing with those in superficial alluviums,
+as in Auvergne and Saxony. In Bohemia, such pebbles have been met with at
+the depth of 180 fathoms. In Cornwall, Mr. Carne mentions true pebbles of
+quartz and slate in a tin lode of the Relistran Mine, at the depth of 600
+feet below the surface. They were cemented by oxide of tin and bisulphuret
+of copper, and were traced over a space more than 12 feet long and as many
+wide.<a name="FNanchor_AN_3" id="FNanchor_AN_3"></a><a href="#Footnote_AN_3" class="fnanchor">[492-A]</a> Marine fossil shells, also, have been found at great depths,
+having probably been engulphed during submarine earthquakes. Thus, a
+gryph�a is stated by M. Virlet to have been met with in a lead-mine near
+S�mur, in France, and a madrepore in a compact vein of cinnabar in
+Hungary.<a name="FNanchor_AN_4" id="FNanchor_AN_4"></a><a href="#Footnote_AN_4" class="fnanchor">[492-B]</a></p>
+
+<p>When different sets or systems of veins occur in the same country, those
+which are supposed to be of contemporaneous origin, and which are filled
+with the same kind of metals, often maintain a general parallelism of
+direction. Thus, for example, both the tin and copper veins in Cornwall run
+nearly east and west, while the lead-veins run north and south; but there
+is no general law of direction common to different mining districts. The
+parallelism of the veins is another reason for regarding them as ordinary
+fissures, for we observe that contemporaneous trap dikes, admitted by all
+to be masses of melted matter which have filled rents, are often parallel.
+Assuming, then, that veins are simply fissures in which chemical and
+mechanical deposits have accumulated, we may next consider the proofs of
+their having been filled gradually and often during successive
+enlargements. I have already spoken of parallel layers of clay, quartz, and
+ore. Werner himself observed, in a vein near Gersdorff, in Saxony, no less
+than thirteen beds of different minerals, arranged with the utmost
+regularity on each side of the central layer. This layer was formed of two
+beds of calcareous spar, which had evidently lined the opposite walls of a
+vertical cavity. The thirteen beds followed each other in corresponding
+order, consisting of fluor-spar, heavy spar, galena, &amp;c. In these cases,
+the central mass has been last formed, and the two plates which coat the
+outer walls of the rent on each side are the oldest of all. If they consist
+of crystalline precipitates, they may be explained by supposing the fissure
+to have remained unaltered in its dimensions, while a series of changes
+occurred in the nature of the solutions which rose up from below; but such
+a mode of deposition, in the case of many successive and parallel layers,
+appears to be exceptional.</p>
+
+<p>If a veinstone consist of crystalline matter, the points of the crystals
+are always turned inwards, or towards the centre of the <span class="pagenum"><a id="page493"></a>[p.493]</span>vein; in
+other words, they point in that direction where there was most space for
+the development of the crystals. Thus each new layer receives the
+impression of the crystals of the preceding layer, and imprints its
+crystals on the one which follows, until at length the whole of the vein is
+filled: the two layers which meet dovetail the points of their crystals the
+one into the other. But in Cornwall, some lodes occur where the vertical
+plates, or <i>combs</i>, as they are there called, exhibit crystals so
+dovetailed as to prove that the same fissure has been often enlarged. Sir
+H. De la Beche gives the following curious and instructive example (<a href="#img490">fig.
+516.</a>) from a copper-mine in granite, near Redruth.<a name="FNanchor_AN_5" id="FNanchor_AN_5"></a><a href="#Footnote_AN_5" class="fnanchor">[493-A]</a> Each of the
+plates or combs (<i>a</i>, <i>b</i>, <i>c</i>, <i>d</i>, <i>e</i>, <i>f</i>) are double, having the
+points of their crystals turned inwards along the axis of the comb. The
+sides or walls (2, 3, 4, 5, and 6) are parted by a thin covering of
+ochreous clay, so that each comb is readily separable from another by a
+moderate blow of the hammer. The breadth of each represents the whole width
+of the fissure at six successive periods, and the outer walls of the vein,
+where the first narrow rent was formed, consisted of the granitic surfaces
+1 and 7.</p>
+
+<a id="img490" name="img490"></a>
+<div class="figcenter smaller width350">
+<p>Fig. 516.</p>
+<img src="images/img490.jpg" width="350" height="225" alt="" title="">
+<p>Copper lode, near Redruth, enlarged at six successive periods.</p></div>
+
+<p>A somewhat analogous interpretation is applicable to numbers of other
+cases, where clay, sand, or angular detritus, alternate with ores and
+veinstones. Thus, we may imagine the sides of a fissure to be encrusted
+with siliceous matter, as Von Buch observed, in Lancerote, the walls of a
+volcanic crater formed in 1731 to be traversed by an open rent in which hot
+vapours had deposited hydrate of silica, the incrustation nearly extending
+to the middle.<a name="FNanchor_AN_6" id="FNanchor_AN_6"></a><a href="#Footnote_AN_6" class="fnanchor">[493-B]</a> Such a vein may then be filled with clay or sand, and
+afterwards re-opened, the new rent dividing the argillaceous deposit, and
+allowing a quantity of rubbish to fall down. Various metals and spars may
+then be precipitated from aqueous solutions among the interstices of this
+heterogeneous mass.</p>
+
+<p>That such changes have repeatedly occurred, is demonstrated by occasional
+cross-veins, implying the oblique fracture of previously formed chemical
+and mechanical deposits. Thus, for example, M. Fournet, in his description
+of some mines in Auvergne worked under his superintendence, observes, that
+the granite of that country was first penetrated by veins of granite, and
+then dislocated, <span class="pagenum"><a id="page494"></a>[p.494]</span>so that open rents crossed both the granite and
+the granitic veins. Into such openings, quartz, accompanied by sulphurets
+of iron and arsenical pyrites, was introduced. Another convulsion then
+burst open the rocks along the old line of fracture, and the first set of
+deposits were cracked and often shattered, so that the new rent was filled,
+not only with angular fragments of the adjoining rocks, but with pieces of
+the older veinstones. Polished and striated surfaces on the sides or in the
+contents of the vein also attest the reality of these movements. A new
+period of repose then ensued, during which various sulphurets were
+introduced, together with hornstone quartz, by which angular fragments of
+the older quartz before mentioned were cemented into a breccia. This period
+was followed by other dilatations of the same veins, and other sets of
+mineral deposits, until, at last, pebbles of the basaltic lavas of
+Auvergne, derived from superficial alluviums, probably of Miocene or older
+Pliocene date, were swept into the veins. I have not space to enumerate all
+the changes minutely detailed by M. Fournet, but they are valuable, both to
+the miner and geologist, as showing how the supposed signs of violent
+catastrophes may be the monuments, not of one paroxysmal shock, but of
+reiterated movements.</p>
+
+<p>Such repeated enlargement and re-opening of veins might have been
+anticipated, if we adopt the theory of fissures, and reflect how few of
+them have ever been sealed up entirely, and that a country with fissures
+only partially filled must naturally offer much feebler resistance along
+the old lines of fracture than any where else. It is quite otherwise in the
+case of dikes, where each opening has been the receptacle of one continuous
+and homogeneous mass of melted matter, the consolidation of which has taken
+place under considerable pressure. Trappean dikes can rarely fail to
+strengthen the rocks at the points where before they were weakest; and if
+the upheaving force is again exerted in the same direction, the crust of
+the earth will give way anywhere rather than at the precise points where
+the first rents were produced.</p>
+
+<p>A large proportion of metalliferous veins have their opposite walls nearly
+parallel, and sometimes over a wide extent of country. There is a fine
+example of this in the celebrated vein of Andreasberg in the Hartz, which
+has been worked for a depth of 500 yards perpendicularly, and 200
+horizontally, retaining almost every where a width of 3 feet. But many
+lodes in Cornwall and elsewhere are extremely variable in size, being 1 or
+2 inches in one part, and then 8 or 10 feet in another, at the distance of
+a few fathoms, and then again narrowing as before. Such alternate swelling
+and contraction is so often characteristic as to require explanation. The
+walls of fissures in general, observes Sir H. De la Beche, are rarely
+perfect planes throughout their entire course, nor could we well expect
+them to be so, since they commonly pass through rocks of unequal hardness
+and different mineral composition. If, therefore, the opposite sides of
+such irregular fissures slide upon each other, that is to say, if there be
+a fault, as in the case of so many mineral <span class="pagenum"><a id="page495"></a>[p.495]</span>veins, the parallelism
+of the opposite walls is at once entirely destroyed, as will be readily
+seen by studying the annexed diagrams.</p>
+
+<a id="img491" name="img491"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 517.</p>
+<img src="images/img491.jpg" width="500" height="032" alt="" title=""></div>
+
+<a id="img492" name="img492"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 518.</p>
+<img src="images/img492.jpg" width="500" height="043" alt="" title=""></div>
+
+<a id="img493" name="img493"></a>
+<div class="figcenter smaller width500">
+<p>Fig. 519.</p>
+<img src="images/img493.jpg" width="500" height="048" alt="" title=""></div>
+
+<p>Let <i>a b</i>, <a href="#img491">fig. 517.</a>, be a line of fracture traversing a rock, and let <i>a
+b</i>, <a href="#img492">fig. 518.</a>, represent the same line. Now, if we cut a piece of paper
+representing this line, and then move the lower portion of this cut paper
+sideways from <i>a</i> to <i>a'</i>, taking care that the two pieces of paper still
+touch each other at the points 1, 2, 3, 4, 5, we obtain an irregular
+aperture at <i>c</i>, and isolated cavities at <i>d d d</i>, and when we compare such
+figures with nature we find that, with certain modifications, they
+represent the interior of faults and mineral veins. If, instead of sliding
+the cut paper to the right hand, we move the lower part towards the left,
+about the same distance that it was previously slid to the right, we obtain
+considerable variation in the cavities so produced, two long irregular open
+spaces, <i>f f</i>, <a href="#img493">fig. 519.</a>, being then formed. This will serve to show to
+what slight circumstances considerable variations in the character of the
+openings between unevenly fractured surfaces may be due, such surfaces
+being moved upon each other, so as to have numerous points of contact.</p>
+
+<a id="img494" name="img494"></a>
+<div class="floatright smaller width200">
+<p>Fig. 520.</p>
+<img src="images/img494.jpg" width="186" height="409" alt="" title=""></div>
+
+<p>Most lodes are perpendicular to the horizon, or nearly so; but some of them
+have a considerable inclination or "hade," as it is termed, the angles of
+dip varying from 15� to 45�. The course of a vein is frequently very
+straight; but if tortuous, it is found to be choked up with clay, stones,
+and pebbles, at points where it departs most widely from verticality. Hence
+at places, such as <i>a</i>, <a href="#img494">fig. 520.</a>, the miner complains that the ores are
+"nipped," or greatly reduced in quantity, the space for their free
+deposition having been interfered with in consequence of the pre-occupancy
+of the lode by earthy materials. When lodes are many fathoms wide, they are
+usually filled for the most part with earthy matter, and fragments of rock,
+through which the ores are much disseminated. The metallic substances
+frequently coat or encircle detached pieces of rock, which our miners call
+"horses" or "riders." That we should find some mineral veins which split
+into branches is also natural, for we observe the same in regard to open
+fissures.</p>
+
+<p><i>Chemical deposits in veins.</i>&mdash;If we now turn from the mechanical to the
+chemical agencies which have been instrumental in the production of mineral
+veins, it may be remarked that those parts of <span class="pagenum"><a id="page496"></a>[p.496]</span>fissures which were
+not choked up with the ruins of fractured rocks must always have been
+filled with water; and almost every vein has probably been the channel by
+which hot springs, so common in countries of volcanos and earthquakes, have
+made their way to the surface. For we know that the rents in which ores
+abound extend downwards to vast depths, where the temperature of the
+interior of the earth is more elevated. We also know that mineral veins are
+most metalliferous near the contact of plutonic and stratified formations,
+especially where the former send veins into the latter, a circumstance
+which indicates an original proximity of veins at their inferior extremity
+to igneous and heated rocks. It is moreover acknowledged that even those
+mineral and thermal springs which, in the present state of the globe, are
+far from volcanos, are nevertheless observed to burst out along great lines
+of upheaval and dislocation of rocks.<a name="FNanchor_AN_7" id="FNanchor_AN_7"></a><a href="#Footnote_AN_7" class="fnanchor">[496-A]</a> It is also ascertained that
+all the substances with which hot springs are impregnated agree with those
+discharged in a gaseous form from volcanos. Many of these bodies occur as
+veinstones; such as silex, carbonate of lime, sulphur, fluor-spar, sulphate
+of barytes, magnesia, oxide of iron, and others. I may add that, if veins
+have been filled with gaseous emanations from masses of melted matter,
+slowly cooling in the subterranean regions, the contraction of such masses
+as they pass from a plastic to a solid state would, according to the
+experiments of Deville on granite (a rock which may be taken as a
+standard), produce a reduction in volume amounting to 10 per cent. The slow
+crystallization, therefore, of such plutonic rocks supplies us with a force
+not only capable of rending open the incumbent rocks by causing a failure
+of support, but also of giving rise to faults whenever one portion of the
+earth's crust subsides slowly while another contiguous to it happens to
+rest on a different foundation, so as to remain unmoved.</p>
+
+<p>Although we are led to infer, from the foregoing reasoning, that there has
+often been an intimate connection between metalliferous veins and hot
+springs holding mineral matter in solution, yet we must not on that account
+expect that the contents of hot springs and mineral veins would be
+identical. On the contrary, M. E. de Beaumont has judiciously observed that
+we ought to find in veins those substances which, being least soluble, are
+not discharged by hot springs,&mdash;or that class of simple and compound bodies
+which the thermal waters ascending from below would first precipitate on
+the walls of a fissure, as soon as their temperature began slightly to
+diminish. The higher they mount towards the surface, the more will they
+cool, till they acquire the average temperature of springs, being in that
+case chiefly charged with the most soluble substances, such as the alkalis,
+soda and potash. These are not met with in veins, although they enter so
+largely into the composition of granitic rocks.<a name="FNanchor_AN_8" id="FNanchor_AN_8"></a><a href="#Footnote_AN_8" class="fnanchor">[496-B]</a></p>
+
+<p>To a certain extent, therefore, the arrangement and distribution of
+metallic matter in veins may be referred to ordinary chemical <span class="pagenum"><a id="page497"></a>[p.497]</span>
+action, or to those variations in temperature, which waters holding the
+ores in solution must undergo, as they rise upwards from great depths in
+the earth. But there are other phenomena which do not admit of the same
+simple explanation. Thus, for example, in Derbyshire, veins containing ores
+of lead, zinc, and copper, but chiefly lead, traverse alternate beds of
+limestone and greenstone. The ore is plentiful where the walls of the rent
+consist of limestone, but is reduced to a mere string when they are formed
+of greenstone, or "toadstone," as it is called provincially. Not that the
+original fissure is narrower where the greenstone occurs, but because more
+of the space is there filled with veinstones, and the waters at such points
+have not parted so freely with their metallic contents.</p>
+
+<p>"Lodes in Cornwall," says Mr. Robert W. Fox, "are very much influenced in
+their metallic riches by the nature of the rock which they traverse, and
+they often change in this respect very suddenly, in passing from one rock
+to another. Thus many lodes which yield abundance of ore in granite, are
+unproductive in clay-slate, or killas, and <i>vice vers�</i>. The same
+observation applies to killas and the granitic porphyry called elvan.
+Sometimes, in the same continuous vein, the granite will contain copper,
+and the killas tin, or <i>vice vers�</i>."<a name="FNanchor_AN_9" id="FNanchor_AN_9"></a><a href="#Footnote_AN_9" class="fnanchor">[497-A]</a> Mr. Fox, after ascertaining
+the existence at present of electric currents in some of the metalliferous
+veins in Cornwall, has speculated on the probability of the same cause
+having acted originally on the sulphurets and muriates of copper, tin,
+iron, and zinc, dissolved in the hot water of fissures, so as to determine
+the peculiar mode of their distribution. After instituting experiments on
+this subject, he even endeavoured to account for the prevalence of an east
+and west direction in the principal Cornish lodes by their position at
+right angles to the earth's magnetism; but Mr. Henwood and other
+experienced miners have pointed out objections to the theory; and it must
+be owned that the direction of veins in different mining districts varies
+so entirely that it seems to depend on lines of fracture, rather than on
+the laws of voltaic electricity. Nevertheless, as different kinds of rock
+would be often in different electrical conditions, we may readily believe
+that electricity must often govern the arrangement of metallic precipitates
+in a rent.</p>
+
+<p>"I have observed," says Mr. R. Fox, "that when the chloride of tin in
+solution is placed in the voltaic circuit, part of the tin is deposited in
+a metallic state at the negative pole, and part at the positive one, in the
+state of a peroxide, such as it occurs in our Cornish mines. This
+experiment may serve to explain why tin is found contiguous to, and
+intermixed with, copper ore, and likewise separated from it, in other parts
+of the same lode."<a name="FNanchor_AN_10" id="FNanchor_AN_10"></a><a href="#Footnote_AN_10" class="fnanchor">[497-B]</a></p>
+
+<p><i>Relative age of the different metals.</i>&mdash;After duly reflecting on the facts
+above described, we cannot doubt that mineral veins, like eruptions of
+granite or trap, are referable to many distinct periods of <span class="pagenum"><a id="page498"></a>[p.498]</span>the
+earth's history, although it may be more difficult to determine the precise
+age of veins; because they have often remained open for ages, and because,
+as we have seen, the same fissure, after having been once filled, has
+frequently been re-opened or enlarged. But besides this diversity of age,
+it has been supposed by some geologists that certain metals have been
+produced exclusively in earlier, others in more modern times,&mdash;that tin,
+for example, is of higher antiquity than copper, copper than lead or
+silver, and all of them more ancient than gold. I shall first point out
+that the facts once relied upon in support of some of these views are
+contradicted by later experience, and then consider how far any
+chronological order of arrangement can be recognized in the position of the
+precious and other metals in the earth's crust. In the first place, it is
+not true that veins in which tin abounds are the oldest lodes worked in
+Great Britain. The government survey of Ireland has demonstrated, that in
+Wexford veins of copper and lead (the latter as usual being argentiferous)
+are much older than the tin of Cornwall. In each of the two countries a
+very similar series of geological changes has occurred at two distinct
+epochs,&mdash;in Wexford, before the Devonian strata were deposited; in
+Cornwall, after the carboniferous epoch. To begin with the Irish mining
+district: We have granite in Wexford, traversed by granite veins, which
+veins also intrude themselves into the Silurian strata, the same Silurian
+rocks as well as the veins having been denuded before the Devonian beds
+were superimposed. Next we find, in the same county, that elvans, or
+straight dikes of porphyritic granite, have cut through the granite and the
+veins before mentioned, but have not penetrated the Devonian rocks.
+Subsequently to these elvans, veins of copper and lead were produced, being
+of a date certainly posterior to the Silurian, and anterior to the
+Devonian; for they do not enter the latter, and, what is still more
+decisive, streaks or layers of derivative copper have been found near
+Wexford in the Devonian, not far from points where mines of copper are
+worked in the Silurian strata.<a name="FNanchor_AN_11" id="FNanchor_AN_11"></a><a href="#Footnote_AN_11" class="fnanchor">[498-A]</a></p>
+
+<p>Although the precise age of such copper lodes cannot be defined, we may
+safely affirm that they were either filled at the close of the Silurian or
+commencement of the Devonian period. Besides copper, lead, and silver,
+there is some gold in these ancient or primary metalliferous veins. A few
+fragments also of tin found in Wicklow in the drift are supposed to have
+been derived from veins of the same age.<a name="FNanchor_AN_12" id="FNanchor_AN_12"></a><a href="#Footnote_AN_12" class="fnanchor">[498-B]</a></p>
+
+<p>Next, if we turn to Cornwall, we find there also the monuments of a very
+analogous sequence of events. First the granite was formed; then, about the
+same period, veins of fine-grained granite, often tortuous (see <a href="#img472">fig. 496.</a>,
+<a href="#page445">p. 445.</a>), penetrating both the outer crust of granite and the adjoining
+fossiliferous or primary rocks, including <span class="pagenum"><a id="page499"></a>[p.499]</span>the coal-measures;
+thirdly, elvans, holding their course straight through granite, granitic
+veins, and fossiliferous slates; fourthly, veins of tin also containing
+copper, the first of those eight systems of fissures of different ages
+already alluded to, <a href="#page491">p. 491.</a> Here, then, the tin lodes are newer than the
+elvans. It has indeed been stated by some Cornish miners that the elvans
+are in some few instances posterior to the oldest tin-bearing lodes, but
+the observations of Sir H. De la Beche during the survey led him to an
+opposite conclusion, and he has shown how the cases referred to in
+corroboration can be otherwise interpreted.<a name="FNanchor_AN_13" id="FNanchor_AN_13"></a><a href="#Footnote_AN_13" class="fnanchor">[499-A]</a> We may, therefore,
+assert that the most ancient Cornish lodes are younger than the
+coal-measures of that part of England, and it follows that they are of a
+much later date than the Irish copper and lead of Wexford and some
+adjoining counties. How much later it is not so easy to declare, although
+probably they are not newer than the beginning of the Permian period, as no
+tin lodes have been discovered in any red sandstone of the Poikilitic
+group, which overlies the coal in the south-west of England.</p>
+
+<p>There are lead veins in the Mendip hills which extend through the mountain
+limestone into the Permian or Dolomitic conglomerate, and others in
+Glamorganshire which enter the lias. Those worked near Frome, in
+Somersetshire, have been traced into the Inferior Oolite. In Bohemia, the
+rich veins of silver of Joachimsthal cut through basalt containing olivine,
+which overlies tertiary lignite, in which are leaves of dicotyledonous
+trees. This silver, therefore, is decidedly a tertiary formation. In regard
+to the age of the gold of the Ural Mountains, in Russia, which, like that
+of California, is obtained chiefly from auriferous alluvium, we can merely
+affirm that it occurs in veins of quartz in the schistose and granitic
+rocks of that chain. Sir R. Murchison observes, that no gold has yet been
+found in the Permian conglomerates which lie at the base of the Ural
+Mountains, although large quantities of iron and copper detritus are mixed
+with the rolled pebbles of these same Permian strata. Hence it seems that
+the Uralian quartz veins, containing gold and platinum, were not exposed to
+aqueous denudation during the Permian era. But we cannot feel sure, from
+any data yet before us, that such auriferous veins of quartz may not be as
+old as the tin lodes of Cornwall, in which, as well as the more ancient
+copper lodes of Ireland, some gold has been detected. We are also unable at
+present to assign to the gold veins of Brazil, Peru, or California, their
+respective geological dates. But, although enough is known to show that
+Ovid's line about the "Age of Gold," "Aurea prima sata est �tas," would, by
+no means, be an apt motto for a treatise on mining, it would be equally
+rash in the present state of our inquiries to affirm, as some have done,
+that gold was the last-formed of metals.</p>
+
+<p>It has been remarked by M. de Beaumont, that lead and some other metals are
+found in dikes of basalt and greenstone, as well as <span class="pagenum"><a id="page500"></a>[p.500]</span>in mineral
+veins connected with trap rocks, whereas tin is met with in granite and in
+veins associated with the granitic series. If this rule hold true
+generally, the geological position of tin in localities accessible to the
+miners will belong, for the most part, to rocks older than those bearing
+lead. The tin veins will be of higher relative antiquity for the same
+reason that the "underlying" igneous formations or granites which are
+visible to man are older, on the whole, than the overlying or trappean
+formations.</p>
+
+<p>If different sets of fissures, originating simultaneously at different
+levels in the earth's crust, and communicating, some of them, with
+volcanic, others with heated plutonic masses, be filled with different
+metals, it will follow that those formed farthest from the surface will
+usually require the longest time before they can be exposed superficially.
+In order to bring them into view, or within reach of the miner, a greater
+amount of upheaval and denudation must take place in proportion as they
+have lain deeper when first formed. A considerable series of geological
+revolutions must intervene before any part of the fissure, which has been
+for ages in the proximity of the plutonic rocks, so as to receive the gases
+discharged from it when it was cooling, can emerge into the atmosphere. But
+I need not enlarge on this subject, as the reader will remember what was
+said in the 30th, 34th, and 37th chapters, on the chronology of the
+volcanic and hypogene formations.</p>
+
+<hr>
+
+<p><i>Concluding Remarks.</i>&mdash;The theory of the origin of the hypogene rocks, at a
+variety of successive periods, as expounded in two of the chapters just
+cited, and still more the doctrine that such rocks may be now in the daily
+course of formation, has made and still makes its way, but slowly, into
+favour. The disinclination to embrace it has arisen partly from an inherent
+obscurity in the very nature of the evidence of plutonic action when
+developed on a great scale, at particular periods. It has also sprung, in
+some degree, from extrinsic considerations; many geologists having been
+unwilling to believe the doctrine of the transmutation of fossiliferous
+into crystalline rocks, because they were desirous of finding proofs of a
+beginning, and of tracing back the history of our terraqueous system to
+times anterior to the creation of organic beings. But if these expectations
+have been disappointed, if we have found it impossible to assign a limit to
+that time throughout which it has pleased an Omnipotent and Eternal Being
+to manifest his creative power, we have at least succeeded beyond all hope
+in carrying back our researches to times antecedent to the existence of
+man. We can prove that man had a beginning, and that, all the species now
+contemporary with man, and many others which preceded, had also a
+beginning, and that, consequently, the present state of the organic world
+has not gone on from all eternity, as some philosophers have maintained.</p>
+
+<p>It can be shown that the earth's surface has been remodelled again and
+again; mountain chains have been raised or sunk; valleys formed, <span class="pagenum"><a id="page501"></a>[p.501]</span>
+filled up, and then re-excavated; sea and land have changed places; yet
+throughout all these revolutions, and the consequent alterations of local
+and general climate, animal and vegetable life has been sustained. This has
+been accomplished without violation of the laws now governing the organic
+creation, by which limits are assigned to the variability of species. The
+succession of living beings appears to have been continued not by the
+transmutation of species, but by the introduction into the earth from time
+to time of new plants and animals, and each assemblage of new species must
+have been admirably fitted for the new states of the globe as they arose,
+or they would not have increased and multiplied and endured for indefinite
+periods.<a name="FNanchor_AN_14" id="FNanchor_AN_14"></a><a href="#Footnote_AN_14" class="fnanchor">[501-A]</a></p>
+
+<p>Astronomy had been unable to establish the plurality of habitable worlds
+throughout space, however favourite a subject of conjecture and
+speculation; but geology, although it cannot prove that other planets are
+peopled with appropriate races of living beings, has demonstrated the truth
+of conclusions scarcely less wonderful,&mdash;the existence on our own planet of
+so many habitable surfaces, or worlds as they have been called, each
+distinct in time, and peopled with its peculiar races of aquatic and
+terrestrial beings.</p>
+
+<p>The proofs now accumulated of the close analogy between extinct and recent
+species are such as to leave no doubt on the mind that the same harmony of
+parts and beauty of contrivance which we admire in the living creation, has
+equally characterized the organic world at remote periods. Thus as we
+increase our knowledge of the inexhaustible variety displayed in living
+nature, and admire the infinite wisdom and power which it displays, our
+admiration is multiplied by the reflection, that it is only the last of a
+great series of pre-existing creations, of which we cannot estimate the
+number or limit in times past.<a name="FNanchor_AN_15" id="FNanchor_AN_15"></a><a href="#Footnote_AN_15" class="fnanchor">[501-B]</a></p>
+
+
+
+
+<hr class="sep2">
+<h2><span class="pagenum"><a id="page502"></a>[p.502]</span>INDEX.</h2>
+
+
+<h3>A.</h3>
+<ul>
+<li class="martop04">�gean Sea, mud of, <a href="#page35">35.</a></li>
+  <li class="add2em">animal life in depths of, <a href="#page137">137.</a></li>
+
+<li class="martop04">Agassiz, M., cited, <a href="#page192">192.</a> <a href="#page276">276.</a> <a href="#page300">300.</a> <a href="#page335">335.</a> <a href="#page344">344.</a> <a href="#page345">345.</a></li>
+  <li class="add2em">on parallel roads, <a href="#page87">87.</a></li>
+  <li class="add2em">on fossil fishes of molasse and faluns, <a href="#page171">171.</a></li>
+  <li class="add2em">on fossil fish of Lias, <a href="#page275">275.</a></li>
+  <li class="add2em">on fossil fish in Permian marl-slate, <a href="#page304">304.</a></li>
+  <li class="add2em">on fish from Sheppey, <a href="#page202">202.</a></li>
+  <li class="add2em">on foot-prints, <a href="#page299">299.</a></li>
+  <li class="add2em">on fishes of brown coal, <a href="#page417">417.</a></li>
+  <li class="add2em">on glaciers, <a href="#page140">140.</a> <a href="#page143">143.</a></li>
+
+<li class="martop04">Age of formation determined by fragments of older rock, <a href="#page101">101.</a></li>
+  <li class="add2em">of metamorphic rocks, <a href="#page482">482.</a></li>
+  <li class="add2em">test of, in plutonic rocks by relative position, <a href="#page449">449.</a></li>
+  <li class="add2em">of Spanish volcanos, <a href="#page414">414.</a></li>
+  <li class="add2em">of volcanic rocks, how tested, <a href="#page397">397</a>-<a href="#page400">400.</a></li>
+
+<li class="martop04">Aix-la-Chapelle, hot spring at, <a href="#page477">477.</a></li>
+
+<li class="martop04">Alabaster defined, <a href="#page13">13.</a></li>
+
+<li class="martop04">Alabama, cretaceous shingle of, <a href="#page225">225.</a></li>
+
+<li class="martop04">Alberti on the Keuper, <a href="#page287">287.</a></li>
+
+<li class="martop04">Alexander, Capt., marine shells in crag, found by, <a href="#page149">149.</a></li>
+
+<li class="martop04">Alluvium, term explained, <a href="#page79">79.</a></li>
+  <li class="add2em">in Auvergne, <a href="#page80">80.</a></li>
+  <li class="add2em">of the Wealden, <a href="#page252">252.</a></li>
+
+<li class="martop04">Alps, nummulitic formation of, <a href="#page205">205.</a></li>
+  <li class="add2em">curved strata of, <a href="#page58">58.</a></li>
+  <li class="add2em">Swiss and Savoy, cleavage of, <a href="#page470">470.</a></li>
+  <li class="add2em">of Switzerland, <a href="#page483">483.</a></li>
+
+<li class="martop04">Alpine blocks on the Jura, <a href="#page142">142.</a></li>
+  <li class="add2em">erratics, <a href="#page140">140.</a></li>
+
+<li class="martop04">Altered rocks, <a href="#page381">381.</a> <a href="#page456">456.</a></li>
+  <li class="add2em">by subterranean gases, <a href="#page476">476.</a></li>
+
+<li class="martop04">Alternations of rocks, <a href="#page14">14.</a></li>
+  <li class="add2em">of marine and freshwater formations, <a href="#page32">32.</a></li>
+
+<li class="martop04">Alumine in rocks, <a href="#page11">11.</a></li>
+
+<li class="martop04"><i>Amblyrhynchus cristatus</i>, <a href="#page279">279.</a></li>
+
+<li class="martop04">America, North, lithodomi in beaches of, <a href="#page78">78.</a></li>
+  <li class="add2em">South, cretaceous strata, <a href="#page225">225.</a></li>
+  <li class="add2em">South, gradual rise of parts of, <a href="#page46">46.</a></li>
+  <li class="add2em">South, fossils of, <a href="#page157">157.</a></li>
+
+<li class="martop04">Amygdaloid, <a href="#page372">372.</a></li>
+
+<li class="martop04">Amphitherium, <a href="#page268">268.</a></li>
+
+<li class="martop04">Andelys, chalk cliffs at, <a href="#page239">239.</a></li>
+
+<li class="martop04">Andernach, strata near, <a href="#page417">417.</a></li>
+
+<li class="martop04">Andes, plutonic rocks of, <a href="#page453">453.</a></li>
+  <li class="add2em">rocks drifted from to Chiloe, <a href="#page144">144.</a></li>
+
+<li class="martop04">Anthracite in Rhode Island, <a href="#page478">478.</a></li>
+
+<li class="martop04">Anticlinal line, <a href="#page48">48.</a> <a href="#page57">57.</a></li>
+
+<li class="martop04">Antrim, rocks altered by dikes in, <a href="#page382">382.</a></li>
+
+<li class="martop04">Antwerp, strata like Suffolk crag near, <a href="#page166">166.</a></li>
+
+<li class="martop04"><i>Apateon pedestris</i>, a carboniferous reptile, <a href="#page336">336.</a></li>
+
+<li class="martop04">Appalachian coal-field, <a href="#page329">329.</a></li>
+
+<li class="martop04">Appalachians, altered rocks in, <a href="#page478">478.</a></li>
+
+<li class="martop04">Apennines, limestone in, <a href="#page482">482.</a></li>
+
+<li class="martop04"><i>Apteryx</i> in New Zealand, <a href="#page158">158.</a></li>
+
+<li class="martop04">Aqueous rocks defined, <a href="#page2">2.</a></li>
+  <li class="add2em">rocks, mineral character of, <a href="#page97">97.</a></li>
+  <li class="add2em">deposits, superposition of, <a href="#page96">96.</a></li>
+
+<li class="martop04">Arbroath, section from, to the Grampians, <a href="#page48">48.</a></li>
+
+<li class="martop04">Archegosaurus, figure of, <a href="#page337">337.</a></li>
+
+<li class="martop04">Archiac, M., cited, <a href="#page143">143.</a></li>
+  <li class="add2em">on fossils in chalk, <a href="#page221">221.</a></li>
+  <li class="add2em">on shells in French Lower Eocene, <a href="#page196">196.</a></li>
+
+<li class="martop04">Ard�che, lava in, <a href="#page385">385.</a></li>
+
+<li class="martop04">Arenaceous rocks described, <a href="#page11">11.</a></li>
+
+<li class="martop04">Argillaceous rocks, <a href="#page11">11.</a></li>
+  <li class="add2em">schist, <a href="#page465">465.</a></li>
+
+<li class="martop04">Argile plastique, or Lower Eocene, <a href="#page196">196.</a></li>
+
+<li class="martop04">Argyleshire, trap-vein in cliff, <a href="#page379">379.</a></li>
+
+<li class="martop04">Arran, age of granite in, <a href="#page459">459.</a></li>
+  <li class="add2em">section of, <a href="#page460">461.</a></li>
+  <li class="add2em">dike of greenstone in, <a href="#page379">379.</a></li>
+
+<li class="martop04">Arthur's Seat, altered strata of, <a href="#page383">383.</a></li>
+
+<li class="martop04">Ashby-de-la-Zouch, fault in coal-field of, <a href="#page69">69.</a></li>
+
+<li class="martop04">Ascension, lamination of volcanic rocks in, <a href="#page480">480.</a></li>
+
+<li class="martop04">Asterophyllites, <a href="#page314">314.</a></li>
+
+<li class="martop04">Asti, formations at, <a href="#page167">167.</a></li>
+
+<li class="martop04">Atherfield, cretaceous strata of, <a href="#page219">219.</a></li>
+
+<li class="martop04">Augite, <a href="#page369">369.</a></li>
+
+<li class="martop04">Aurillac, freshwater strata of, <a href="#page188">188.</a></li>
+
+<li class="martop04">Austen, Mr., R. A. C., on phosphate of lime, <a href="#page219">219.</a></li>
+
+<li class="martop04">Australian cave-breccias, <a href="#page155">155.</a></li>
+
+<li class="martop04">Auvergne freshwater formations, <a href="#page186">186.</a></li>
+  <li class="add2em">succession of changes in, <a href="#page180">180.</a></li>
+  <li class="add2em">lacustrine strata, <a href="#page181">181.</a></li>
+  <li class="add2em">mineral veins of, <a href="#page493">493.</a></li>
+  <li class="add2em">indusial limestone, <a href="#page184">184.</a></li>
+  <li class="add2em">extinct volcanos of, <a href="#page422">422.</a></li>
+  <li class="add2em">alluvium in, <a href="#page80">80.</a></li>
+
+<li class="martop04">Aymestry limestone, <a href="#page352">352.</a></li>
+</ul>
+
+<h3>B.</h3>
+<ul>
+<li class="martop04">Bagshot sands, <a href="#page199">199.</a></li>
+
+<li class="martop04">Bacillaria, fossil in tripoli, <a href="#page25">25.</a></li>
+
+<li class="martop04">Bai�, Bay of, strata in, <a href="#page403">403.</a></li>
+
+<li class="martop04">Bakewell, Mr., on cleavages of Alps, <a href="#page470">470.</a></li>
+
+<li class="martop04">Balgray, near Glasgow, stumps of trees in coal, <a href="#page317">317.</a></li>
+
+<li class="martop04">Bahia Blanca, fossil remains at, <a href="#page148">148.</a></li>
+
+<li class="martop04">Baltic, brackish water strata on coast of, <a href="#page114">114.</a></li>
+
+<li class="martop04">Barcombe, chalk flints near, <a href="#page253">253.</a></li>
+
+<li class="martop04">Barton Cliff, <a href="#page198">198.</a></li>
+
+<li class="martop04">Barrande, M., on trilobites, <a href="#page358">358.</a></li>
+
+<li class="martop04">Basterot, M. de, on tertiaries of south of France, <a href="#page105">105.</a></li>
+
+<li class="martop04">Basalt, <a href="#page371">371.</a></li>
+  <li class="add2em">columnar in the Eifel, <a href="#page387">387.</a></li>
+  <li class="add2em">columnar, near Vicenza, <a href="#page386">386.</a></li>
+  <li class="add2em">columnar, structure of, <a href="#page384">384.</a></li>
+
+<li class="martop04">Basset, term explained, <a href="#page56">56.</a></li>
+
+<li class="martop04">Batrachian, eggs of, in Old Red, Scotland, Postscript, <a href="#pagex">x.</a></li>
+
+<li class="martop04">Bayfield, Capt., on fossil shells in Canada, <a href="#page134">134.</a></li>
+  <li class="add2em">on inland cliffs in Gulf of St. Lawrence, <a href="#page78">78.</a></li>
+
+<li class="martop04">Bean, Mr., shells similar to those in Norwich crag found in Yorkshire by, <a href="#page149">149.</a></li>
+
+<li class="martop04">Bean, Mr., on fossil shells from oolite, <a href="#page272">272.</a></li>
+
+<li class="martop04">Beachy Head, chalk cliffs near, <a href="#page246">246.</a></li>
+
+<li class="martop04">Beaumont, M. E. de, on rocks of Hautes Alpes, <a href="#page455">455.</a></li>
+  <li class="add2em">on lamination of volcanic rocks, <a href="#page480">480.</a></li>
+<li class="add2em"><span class="pagenum"><a id="page503"></a>[p.503]</span>on Swiss Alps, <a href="#page484">484.</a></li>
+  <li class="add2em">on quartz, <a href="#page439">439.</a></li>
+  <li class="add2em">on oolite formation in France, <a href="#page221">221.</a></li>
+
+<li class="martop04">Beck, Dr., on kelp, <a href="#page217">217.</a></li>
+  <li class="add2em">on graptolites, <a href="#page357">357.</a></li>
+  <li class="add2em">cited, <a href="#page162">162.</a> <a href="#page186">186.</a></li>
+
+<li class="martop04">Belemnite in Oxford clay, <a href="#page262">262.</a></li>
+
+<li class="martop04">Berger, Dr., on rocks altered by dikes, <a href="#page382">382.</a></li>
+
+<li class="martop04">Bergmann on trap, <a href="#page366">366.</a></li>
+
+<li class="martop04">Berlin, tertiary strata near, <a href="#page177">177.</a></li>
+
+<li class="martop04">Bermuda Islands, lagoons in, <a href="#page216">216.</a></li>
+  <li class="add2em">rocks of, <a href="#page78">78.</a></li>
+
+<li class="martop04">Bernese Alps, gneiss in, <a href="#page484">484.</a></li>
+
+<li class="martop04">Berthier, on augite and hornblende, <a href="#page369">369.</a></li>
+
+<li class="martop04">Beudant, M., on Hungary, <a href="#page421">421.</a></li>
+
+<li class="martop04">Beyrich, Prof., on tertiary strata near Berlin, <a href="#page177">177.</a></li>
+
+<li class="martop04">Biaritz, calcareous cliffs of, <a href="#page72">72.</a></li>
+
+<li class="martop04">Bilin, tripoli, composed of infusoria, <a href="#page25">25.</a></li>
+
+<li class="martop04">Binney, Mr., on stigmaria and sigillaria, <a href="#page315">315.</a></li>
+
+<li class="martop04">Birds, footprints of, <a href="#page298">298.</a></li>
+  <li class="add2em">fossil, scarcity of, Postscript, <a href="#pagexix">xix.</a></li>
+
+<li class="martop04">Bischoff, Prof., experiments on heat, <a href="#page476">476.</a></li>
+  <li class="add2em">on steam at a high temperature, <a href="#page477">477.</a></li>
+
+<li class="martop04">Blainville, on number of genera of mollusca, <a href="#page28">28.</a></li>
+
+<li class="martop04">Boase, Dr., cited, <a href="#page479">479.</a></li>
+
+<li class="martop04">Boblaye, M., on inland cliffs, <a href="#page73">73.</a></li>
+  <li class="add2em">cited, <a href="#page431">431.</a></li>
+
+<li class="martop04">Bog-iron ore, <a href="#page26">26.</a></li>
+
+<li class="martop04">Borrowdale, black-lead of, <a href="#page38">38.</a></li>
+
+<li class="martop04">Bordeaux, tertiary deposits of, <a href="#page171">171.</a></li>
+
+<li class="martop04">Bosquet, M., on Maestricht beds, <a href="#page210">210.</a></li>
+
+<li class="martop04">Bothnia, Gulf of, land upheaved, <a href="#page45">45.</a></li>
+
+<li class="martop04">Bou�, M., on arrangement of rocks, <a href="#page95">95.</a></li>
+  <li class="add2em">on fossil shells in Hungary, <a href="#page421">421.</a></li>
+  <li class="add2em">on Carrara marble, <a href="#page482">482.</a></li>
+  <li class="add2em">on Swiss Alps, <a href="#page484">484.</a></li>
+
+<li class="martop04">Bonelli, on strata in Italy, <a href="#page106">106.</a></li>
+
+<li class="martop04">Boulder formation in Canada, <a href="#page133">133.</a></li>
+  <li class="add2em">period, fauna of, <a href="#page126">126.</a></li>
+  <li class="add2em">formation, mineral ingredients of, <a href="#page126">126.</a></li>
+  <li class="add2em">formation in England, <a href="#page130">130.</a></li>
+
+<li class="martop04">Boulders, <a href="#page123">123.</a></li>
+  <li class="add2em">striated, <a href="#page136">136.</a></li>
+
+<li class="martop04">Boutigny, M., cited, <a href="#page441">441.</a></li>
+
+<li class="martop04">Bowen, Lieut. A., R.N., drawings of rocks in Gulf of St. Lawrence, <a href="#page78">78.</a></li>
+
+<li class="martop04">Bowerbank, Mr., on fossil flora of Sheppey, <a href="#page200">200.</a></li>
+
+<li class="martop04">Bowman, Mr., on coal-seams, <a href="#page330">330.</a></li>
+
+<li class="martop04">Bracklesham Bay, characteristic shells of, <a href="#page199">199.</a></li>
+
+<li class="martop04">Brash, term, explained, <a href="#page81">81.</a></li>
+
+<li class="martop04">Bravard, M., on Auvergne mammalia, <a href="#page188">188.</a> <a href="#page425">425.</a></li>
+
+<li class="martop04">Breccia on ancient coast lines, <a href="#page73">73.</a></li>
+
+<li class="martop04">Brickenden, Captain, on Elgin fossils, Postscript, <a href="#pageix">ix.</a></li>
+
+<li class="martop04">Brighton, elephant bed of, <a href="#page256">256.</a></li>
+
+<li class="martop04">Bristol, dolomitic conglomerate near, <a href="#page305">305.</a></li>
+  <li class="add2em">section of strata near, <a href="#page102">102.</a></li>
+
+<li class="martop04">Brocchi, on Subapennines, <a href="#page105">105</a>. <a href="#page167">167.</a></li>
+
+<li class="martop04">Brockedon, Mr., on black-lead, <a href="#page38">38.</a></li>
+
+<li class="martop04">Broderip, Mr., cited, <a href="#page270">270.</a></li>
+
+<li class="martop04">Brodie, Rev. P.B., on fossil insects, <a href="#page281">281.</a></li>
+  <li class="add2em">cited, <a href="#page207">207.</a></li>
+
+<li class="martop04">Bromley, oyster-bed near, <a href="#page204">204.</a></li>
+
+<li class="martop04">Brongniart, M. Adolphe, on Eocene flora, <a href="#page200">200.</a></li>
+  <li class="add2em">on flora of cretaceous period, <a href="#page223">223.</a></li>
+  <li class="add2em">on fossil plants in lias, <a href="#page282">282.</a></li>
+  <li class="add2em">on plants of Bunter sandstein, <a href="#page288">288.</a></li>
+  <li class="add2em">on fossil fir-cones, <a href="#page313">313.</a></li>
+  <li class="add2em">on Permian flora, <a href="#page307">307.</a></li>
+  <li class="add2em">on sigillaria, <a href="#page314">314.</a></li>
+  <li class="add2em">on asterophyllites, <a href="#page314">314.</a></li>
+  <li class="add2em">on stigmaria, <a href="#page315">315.</a></li>
+  <li class="add2em">age of acrogens, <a href="#page316">316.</a></li>
+  <li class="add2em">on endogens, <a href="#page316">316.</a></li>
+
+<li class="martop04">Brongniart, M. Alex., on Paris tertiaries, <a href="#page104">104.</a></li>
+  <li class="add2em">on Eocene formation, <a href="#page175">175.</a></li>
+  <li class="add2em">on shells of nummulitic formation, <a href="#page205">205.</a></li>
+  <li class="add2em">on coal mine near Lyons, <a href="#page319">319.</a></li>
+
+<li class="martop04">Brora, coal formation, <a href="#page272">272.</a></li>
+
+<li class="martop04">Brora, granite near, <a href="#page458">458.</a></li>
+
+<li class="martop04">Brown, Mr. Richard, on stigmari�, <a href="#page315">315.</a></li>
+  <li class="add2em">on coal formation, <a href="#page415">415.</a></li>
+  <li class="add2em">on Cape Breton coal-field, <a href="#page324">324.</a> <a href="#page334">334.</a></li>
+  <li class="add2em">on carboniferous rain-prints, Postscript, <a href="#pagexii">xii.</a></li>
+
+<li class="martop04">Buckland, Dr., on cave at Kirkdale, <a href="#page154">154.</a></li>
+  <li class="add2em">on coal plants, <a href="#page317">317.</a></li>
+  <li class="add2em">on coprolites in chalk, <a href="#page216">216.</a></li>
+  <li class="add2em">on fish of Lias, <a href="#page276">276.</a></li>
+  <li class="add2em">on footprints, <a href="#page291">291.</a></li>
+  <li class="add2em">on mountains of Caernarvonshire, <a href="#page130">130.</a></li>
+  <li class="add2em">on oyster bed near Bromley, <a href="#page204">204.</a></li>
+  <li class="add2em">on parallel roads, <a href="#page87">87.</a></li>
+  <li class="add2em">on term Poikilitic, <a href="#page286">286.</a></li>
+  <li class="add2em">on saurians of Lias, <a href="#page278">278.</a></li>
+  <li class="add2em">on sudden destruction of saurians, <a href="#page280">280.</a></li>
+  <li class="add2em">cited, <a href="#page155">155.</a> <a href="#page231">231.</a> <a href="#page233">233.</a> <a href="#page267">267.</a> <a href="#page268">268.</a></li>
+
+<li class="martop04">Buddle, Mr., on creeps in coal mines, <a href="#page50">50.</a></li>
+  <li class="add2em">on ancient river-channels of coal period, <a href="#page334">334.</a></li>
+
+<li class="martop04">Buist, Dr. G., on saltness of Red Sea, <a href="#page296">296.</a></li>
+
+<li class="martop04">Bunbury, Mr. C. J. F., on plants of coal-field, <a href="#page285">285.</a></li>
+
+<li class="martop04">Bunter sandstein, <a href="#page288">288.</a></li>
+
+<li class="martop04">Burmeister on trilobites, <a href="#page358">358.</a></li>
+
+<li class="martop04">Burnes, Sir A., cited, <a href="#page295">295.</a></li>
+</ul>
+
+
+<h3>C.</h3>
+<ul>
+<li class="martop04">Caernarvonshire, ancient glaciers of, <a href="#page130">130.</a></li>
+
+<li class="martop04">Calamites, figures of, <a href="#page313">313.</a></li>
+  <li class="add2em">near Pictou, <a href="#page319">319.</a></li>
+
+<li class="martop04">Calcaire grossier, <a href="#page193">193.</a></li>
+  <li class="add2em">siliceux, <a href="#page195">195.</a></li>
+
+<li class="martop04">Calcareous rocks, <a href="#page12">12.</a></li>
+  <li class="add2em">rocks of Gulf of Spezia, <a href="#page482">482.</a></li>
+  <li class="add2em">cliffs of Biaritz, <a href="#page72">72.</a></li>
+
+<li class="martop04">Caldcleugh, Mr., cited, <a href="#page399">399.</a></li>
+
+<li class="martop04">Caldera of Palma, <a href="#page392">392.</a></li>
+
+<li class="martop04">Cambrian group, <a href="#page361">361.</a></li>
+  <li class="add2em">volcanic rocks, <a href="#page435">435.</a></li>
+
+<li class="martop04">Campagna di Roma, tuffs of, <a href="#page408">408.</a></li>
+
+<li class="martop04">Canada, shells in drift of, <a href="#page134">134.</a></li>
+
+<li class="martop04">Cantal, freshwater formation of, <a href="#page188">188.</a></li>
+  <li class="add2em">igneous rocks of, <a href="#page429">429.</a></li>
+  <li class="add2em">freshwater beds of, <a href="#page429">429.</a></li>
+
+<li class="martop04">Cape Breton, coal measures of, <a href="#page324">324.</a></li>
+  <li class="add2em">Wrath, granite veins in, <a href="#page444">444.</a></li>
+
+<li class="martop04">Caradoc sandstone, <a href="#page356">356.</a></li>
+
+<li class="martop04">Carbonaceous shale, <a href="#page271">271.</a></li>
+
+<li class="martop04">Carbonate of lime scarce in metamorphic rocks, <a href="#page487">487.</a></li>
+
+<li class="martop04">Carbonate of lime in rocks, how tested, <a href="#page12">12.</a></li>
+
+<li class="martop04">Carboniferous group, <a href="#page308">308.</a></li>
+  <li class="add2em">flora, <a href="#page310">310.</a></li>
+  <li class="add2em">period, plutonic rocks of, <a href="#page456">456.</a></li>
+  <li class="add2em">period, volcanic rocks of, <a href="#page432">432.</a></li>
+  <li class="add2em">reptiles, <a href="#page335">335.</a></li>
+
+<li class="martop04">Carne, Mr., on Cornish lodes, <a href="#page491">491.</a> <a href="#page492">492.</a></li>
+
+<li class="martop04">Carrara marble, <a href="#page482">482.</a></li>
+
+<li class="martop04"><i>Caryophyllia c�spitosa</i>, bed of, in Sicily, <a href="#page151">151.</a></li>
+
+<li class="martop04">Castrogiovanni, bent strata near, <a href="#page58">58.</a></li>
+
+<li class="martop04">Catalonia, volcanic region of, <a href="#page408">408.</a></li>
+
+<li class="martop04">Cautley, Captain, on Sew�lik hills, <a href="#page173">173.</a></li>
+
+<li class="martop04">Caves in Europe, <a href="#page155">155.</a></li>
+  <li class="add2em">at Kirkdale, <a href="#page154">154.</a></li>
+  <li class="add2em">in Sicily, <a href="#page153">153.</a></li>
+  <li class="add2em">in Australia, <a href="#page156">156.</a></li>
+
+<li class="martop04">Central France, Upper Eocene of, <a href="#page178">178.</a></li>
+
+<li class="martop04">Cetacea, fossil, rarity of, Postscript, <a href="#pagexxi">xxi.</a></li>
+
+<li class="martop04">Chalk, pinnacle of, near Sherringham, <a href="#page129">129.</a></li>
+  <li class="add2em">of Faxoe, <a href="#page210">210.</a> and Postscript, <a href="#pagexv">xv.</a></li>
+  <li class="add2em">white, fossils of, <a href="#page26">26.</a></li>
+  <li class="add2em">white, section of, <a href="#page211">211.</a></li>
+  <li class="add2em">white, extent and origin of, <a href="#page215">215.</a></li>
+  <li class="add2em">white, animal origin of, <a href="#page216">216.</a></li>
+  <li class="add2em">pebbles in, <a href="#page217">217.</a></li>
+  <li class="add2em">difference of, in north and south of Europe, <a href="#page221">221.</a></li>
+
+<li class="martop04"><span class="pagenum"><a id="page504"></a>[p.504]</span>Chalk cliffs, inland, on Seine, <a href="#page238">238.</a></li>
+  <li class="add2em">needles of, in Normandy, <a href="#page241">241.</a></li>
+  <li class="add2em">flints, bed of, near Barcombe, <a href="#page253">253.</a></li>
+
+<li class="martop04">Chambers, Mr., cited, <a href="#page88">88.</a></li>
+
+<li class="martop04">Chamisso, cited, <a href="#page217">217.</a></li>
+
+<li class="martop04">Chara, in freshwater strata, <a href="#page31">31.</a></li>
+  <li class="add2em">in flints of Cantal, <a href="#page189">189.</a></li>
+  <li class="add2em">in Eocene strata of France, <a href="#page176">176.</a></li>
+  <li class="add2em">in Purbeck beds, <a href="#page232">232.</a></li>
+
+<li class="martop04">Charlesworth, Mr. E., cited, on Crag, <a href="#page162">162.</a></li>
+
+<li class="martop04">Charpentier, M., on Alpine glaciers, <a href="#page140">140.</a></li>
+  <li class="add2em">on Swiss glaciers, <a href="#page143">143.</a></li>
+
+<li class="martop04">Cheirotherium, footprints of, <a href="#page290">290.</a> <a href="#page337">337.</a></li>
+
+<li class="martop04">Chemical and mechanical deposits, <a href="#page33">33.</a></li>
+
+<li class="martop04">Chili, earthquake in, <a href="#page61">61.</a></li>
+  <li class="add2em">gold mines in, <a href="#page472">472.</a></li>
+
+<li class="martop04">Chiloe, rocks drifted from Andes to, <a href="#page144">144.</a></li>
+
+<li class="martop04">Chlorite schist, <a href="#page465">465.</a></li>
+
+<li class="martop04">Christiania, dike near, <a href="#page380">380.</a></li>
+  <li class="add2em">trap rocks, passage of granite into, at, <a href="#page441">441.</a></li>
+  <li class="add2em">granite near, <a href="#page457">457.</a></li>
+  <li class="add2em">gneiss near, <a href="#page446">446.</a></li>
+  <li class="add2em">intrusion of granite into beds near, <a href="#page446">446.</a></li>
+
+<li class="martop04">Chronological groups, <a href="#page101">101.</a></li>
+
+<li class="martop04">Cinder-bed, Purbeck, <a href="#page231">231.</a></li>
+
+<li class="martop04">Claiborne, marine shells of, <a href="#page206">206.</a></li>
+
+<li class="martop04">Clausen, Mr., cited, <a href="#page158">158.</a></li>
+
+<li class="martop04">Clay, defined, <a href="#page11">11.</a></li>
+
+<li class="martop04">Clay-slate, <a href="#page465">465.</a> <a href="#page468">468.</a></li>
+
+<li class="martop04">Clay-ironstone, <a href="#page326">326.</a></li>
+
+<li class="martop04">Clays, plastic, <a href="#page203">203.</a></li>
+
+<li class="martop04">Cleavage of rocks, <a href="#page468">468.</a></li>
+
+<li class="martop04">Climate of drift period, <a href="#page139">139.</a></li>
+  <li class="add2em">of coal period, <a href="#page335">335.</a></li>
+
+<li class="martop04">Coal, zigzag flexures of, near Mons</li>
+  <li class="add2em">group, <a href="#page308">308.</a></li>
+  <li class="add2em">measures, <a href="#page308">308.</a> <a href="#page309">309.</a></li>
+  <li class="add2em">how formed, <a href="#page317">317.</a></li>
+  <li class="add2em">pipes, danger of, <a href="#page318">318.</a></li>
+  <li class="add2em">mine, near Lyons, <a href="#page319">319.</a></li>
+  <li class="add2em">seam at Brownsville, Pennsylvania, view of, <a href="#page332">332.</a></li>
+  <li class="add2em">conversion of into lignite, <a href="#page333">333.</a></li>
+  <li class="add2em">formation at Brora, <a href="#page272">272.</a></li>
+  <li class="add2em">seams, continuity of, <a href="#page334">334.</a></li>
+  <li class="add2em">period, climate of, <a href="#page335">335.</a></li>
+  <li class="add2em">strata, footprints of reptiles in, <a href="#page337">337.</a></li>
+
+<li class="martop04">Coal-field at Burdiehouse, <a href="#page325">325.</a></li>
+  <li class="add2em">of Ashby-de-la-Zouch, <a href="#page69">69.</a></li>
+  <li class="add2em">United States, diagram of, <a href="#page328">327.</a></li>
+  <li class="add2em">of Yorkshire, fossils of, <a href="#page325">325.</a></li>
+
+<li class="martop04">Coalbrook Dale, beetles in coal of, <a href="#page335">335.</a></li>
+  <li class="add2em">fossil cones in, <a href="#page313">313.</a></li>
+  <li class="add2em">coal measures of, <a href="#page324">324.</a></li>
+  <li class="add2em">faults in, <a href="#page62">62.</a></li>
+
+<li class="martop04">Cockfield Fell, rocks altered by dikes, <a href="#page383">383.</a></li>
+
+<li class="martop04">Columbia, vinegar river of, <a href="#page191">191.</a></li>
+
+<li class="martop04">Colchester, Mr., on mammalian remains at Kyson, <a href="#page203">203.</a></li>
+
+<li class="martop04">C�me, ravine in lava of, <a href="#page427">427.</a></li>
+
+<li class="martop04">Cones in Val di Noto, <a href="#page389">389.</a></li>
+  <li class="add2em">and craters, absence of, in England, <a href="#page6">6.</a></li>
+  <li class="add2em">and craters, <a href="#page367">367.</a></li>
+
+<li class="martop04">Conifers, fossil trees, <a href="#page316">316.</a></li>
+
+<li class="martop04">Concretionary structure, <a href="#page37">37.</a></li>
+
+<li class="martop04">Conglomerate, or pudding-stone, <a href="#page11">11.</a></li>
+  <li class="add2em">dolomitic, <a href="#page305">305.</a></li>
+  <li class="add2em">vertical in Scotland, &amp;c., <a href="#page47">47.</a></li>
+
+<li class="martop04">Connecticut, valley of the, <a href="#page297">297.</a></li>
+  <li class="add2em">beds, antiquity of, <a href="#page300">300.</a></li>
+
+<li class="martop04">Conrad, Mr., on cretaceous rocks, <a href="#page224">224.</a></li>
+
+<li class="martop04">Conybeare, Mr., cited, <a href="#page64">64.</a> <a href="#page69">69.</a> <a href="#page244">244.</a> <a href="#page274">274.</a></li>
+  <li class="add2em">on Plesiosaurus, <a href="#page278">278.</a></li>
+  <li class="add2em">on oolite and lias, <a href="#page283">283.</a></li>
+  <li class="add2em">on term Poikilitic, <a href="#page286">286.</a></li>
+  <li class="add2em">on crocodiles, <a href="#page201">201.</a></li>
+
+<li class="martop04">Cook, Capt., on <i>Fucus giganteus</i>, <a href="#page217">217.</a></li>
+
+<li class="martop04">Coprolites in chalk, <a href="#page216">216.</a></li>
+
+<li class="martop04">Coralline crag, fossils in, <a href="#page164">164.</a></li>
+
+<li class="martop04">Coral islands and reefs, <a href="#page34">34.</a> <a href="#page46">46.</a></li>
+  <li class="add2em">rag of Oolite, <a href="#page260">260.</a></li>
+
+<li class="martop04">Corals, figures of, in crag, <a href="#page165">165.</a></li>
+  <li class="add2em">of Devonian system, <a href="#page346">346.</a></li>
+  <li class="add2em">of Devonian strata in United States, <a href="#page349">349.</a></li>
+  <li class="add2em">in Wenlock formation, <a href="#page355">355.</a></li>
+
+<li class="martop04">Corinth, corrosion of rocks by gases near, <a href="#page477">477.</a></li>
+
+<li class="martop04">Cornbrash, <a href="#page263">263.</a></li>
+
+<li class="martop04">Cornwall, granite veins in, <a href="#page445">445.</a> <a href="#page474">474.</a></li>
+  <li class="add2em">mineral veins in, <a href="#page490">490.</a> <a href="#page494">494.</a></li>
+  <li class="add2em">tin of, newer than Irish copper, <a href="#page499">499.</a></li>
+
+<li class="martop04">Cotta, Dr. B., on granite in Saxony, <a href="#page459">459.</a></li>
+
+<li class="martop04">Crag coralline, fossils in, <a href="#page164">164.</a></li>
+  <li class="add2em">comparison of faluns and, <a href="#page170">170.</a></li>
+  <li class="add2em">of Suffolk, red and coralline, <a href="#page105">105.</a> <a href="#page162">162.</a></li>
+  <li class="add2em">fluvio-marine, Norwich, <a href="#page148">148.</a></li>
+
+<li class="martop04">Craigleith fossil trees, <a href="#page40">40.</a></li>
+  <li class="add2em">quarry, slanting tree in, <a href="#page320">320.</a></li>
+
+<li class="martop04">Crater of Island of St. Paul, <a href="#page395">395.</a></li>
+
+<li class="martop04">Craven fault, <a href="#page64">64.</a></li>
+
+<li class="martop04">Creeps in coal-mines described, <a href="#page52">52.</a></li>
+
+<li class="martop04">Credneria in Quadersandstein, Postscript, <a href="#pagexvi">xvi.</a></li>
+
+<li class="martop04">Cretaceous rocks of Pyrenees, <a href="#page455">455.</a></li>
+  <li class="add2em">group, 209. 219. and Postscript, <a href="#pagexvi">xvi.</a></li>
+  <li class="add2em">strata in South America and India, <a href="#page225">225.</a></li>
+  <li class="add2em">period, plutonic rocks of, <a href="#page455">455.</a></li>
+  <li class="add2em">volcanic rocks, <a href="#page431">431.</a></li>
+  <li class="add2em">rocks in United States, <a href="#page224">224.</a></li>
+
+<li class="martop04">Crocodiles near Cuba, <a href="#page279">279.</a></li>
+
+<li class="martop04">Croizet, M., on Auvergne fossil mammalia, <a href="#page188">188.</a></li>
+
+<li class="martop04">Cromer, contorted drift near, <a href="#page129">129.</a></li>
+
+<li class="martop04">"Crop out," term explained, <a href="#page55">55.</a></li>
+
+<li class="martop04">Crust of earth defined, <a href="#page2">2.</a></li>
+
+<li class="martop04">Crystalline limestone, <a href="#page302">302.</a></li>
+  <li class="add2em">rocks, erroneously termed primitive, <a href="#page9">9.</a></li>
+  <li class="add2em">schists defined, <a href="#page7">7.</a></li>
+
+<li class="martop04">Curved strata, <a href="#page47">47.</a></li>
+  <li class="add2em">strata, experiments to illustrate, <a href="#page49">49.</a></li>
+
+<li class="martop04">Cutch, Runn of, <a href="#page295">295.</a></li>
+
+<li class="martop04">Cuvier, M., on Eocene formation, <a href="#page175">175.</a></li>
+  <li class="add2em">on Amphitherium, <a href="#page268">268.</a></li>
+  <li class="add2em">cited, <a href="#page192">192.</a></li>
+  <li class="add2em">on tertiary strata near Paris, <a href="#page104">104.</a></li>
+  <li class="add2em">on fossils of Montmartre, <a href="#page191">191.</a></li>
+
+<li class="martop04">Cyclopian Islands, <a href="#page401">401.</a></li>
+
+<li class="martop04">Cypris in Lias, <a href="#page281">281.</a></li>
+  <li class="add2em">in Wealden, <a href="#page228">228.</a></li>
+  <li class="add2em">in marl of Auvergne, <a href="#page183">183.</a></li>
+
+<li class="martop04">Cystide� in Silurian rocks, <a href="#page358">358.</a></li>
+</ul>
+
+
+<h3>D.</h3>
+<ul>
+<li class="martop04">Dana, Mr., on coprolites of birds, <a href="#page299">299.</a></li>
+  <li class="add2em">on coral reef in Sandwich Islands, <a href="#page216">216.</a></li>
+  <li class="add2em">on volcanos of Sandwich Islands, <a href="#page394">394.</a> <a href="#page406">406.</a> <a href="#page423">423.</a></li>
+
+<li class="martop04">Dartmoor, granite of, <a href="#page456">456.</a></li>
+
+<li class="martop04">Darwin, Mr., cited, <a href="#page217">217.</a></li>
+  <li class="add2em">on boulders and glaciers in South America, <a href="#page144">144.</a></li>
+  <li class="add2em">on cleavage in South America, <a href="#page471">471.</a></li>
+  <li class="add2em">on coral islands of Pacific, <a href="#page216">216.</a></li>
+  <li class="add2em">on dike in St. Helena, <a href="#page406">406.</a></li>
+  <li class="add2em">on habits of ostrich, <a href="#page299">299.</a> and Postscript, <a href="#pagexx">xx.</a></li>
+  <li class="add2em">on fossils in South America, <a href="#page148">148.</a></li>
+  <li class="add2em">on <i>Fucus giganteus</i>, <a href="#page217">217.</a></li>
+  <li class="add2em">on gradual rise of part of S. America, <a href="#page46">46.</a></li>
+  <li class="add2em">on lamination of volcanic rocks, <a href="#page480">480.</a></li>
+  <li class="add2em">on parallel roads, <a href="#page87">87.</a></li>
+  <li class="add2em">on plutonic rocks of Andes, <a href="#page453">453.</a></li>
+  <li class="add2em">on recent strata near Lima, <a href="#page115">115.</a></li>
+  <li class="add2em">on saurians in Galapagos Islands, <a href="#page279">279.</a></li>
+  <li class="add2em">on sinking of coral reefs, <a href="#page46">46.</a></li>
+  <li class="add2em">on Welsh glaciers, <a href="#page131">131.</a></li>
+
+<li class="martop04">Daubeny, Dr., on the Solfatara, <a href="#page477">477.</a></li>
+<li class="add2em"><span class="pagenum"><a id="page505"></a>[p.505]</span>on volcanos in Auvergne, <a href="#page428">428.</a></li>
+
+<li class="martop04">Dax, inland cliff at, <a href="#page72">72.</a></li>
+
+<li class="martop04">Deane, Dr., on footprints, <a href="#page298">298.</a></li>
+
+<li class="martop04">Dean, forest of, coal in, <a href="#page334">334.</a></li>
+
+<li class="martop04">Dechen, Prof. von, on reptiles in Saarbr�ck coal-field, <a href="#page336">336.</a></li>
+
+<li class="martop04">De Koninck, cited, <a href="#page176">176.</a> <a href="#page178">178.</a></li>
+
+<li class="martop04">De la Beche, Sir H., cited, <a href="#page231">231.</a> <a href="#page233">233.</a> <a href="#page281">281.</a></li>
+  <li class="add2em">on Carrara marble, <a href="#page482">482.</a></li>
+  <li class="add2em">on clay beds, <a href="#page283">283.</a></li>
+  <li class="add2em">on clay-ironstone, <a href="#page326">326.</a></li>
+  <li class="add2em">on coal-measures near Swansea, <a href="#page309">309.</a></li>
+  <li class="add2em">on fossil trees, S. Wales, <a href="#page318">318.</a></li>
+  <li class="add2em">on granite of Dartmoor, <a href="#page474">474.</a></li>
+  <li class="add2em">on mineral veins, <a href="#page493">493.</a> <a href="#page495">495.</a> <a href="#page498">498.</a></li>
+  <li class="add2em">on term supracretaceous, <a href="#page103">103.</a></li>
+  <li class="add2em">on trap of New Red Sandstone period, <a href="#page432">432.</a></li>
+
+<li class="martop04">Deluge, <a href="#page4">4.</a></li>
+
+<li class="martop04">Denudation explained, <a href="#page66">66.</a></li>
+  <li class="add2em">of the Weald Valley, <a href="#page242">242.</a></li>
+  <li class="add2em">terraces of, in Sicily, <a href="#page75">75.</a></li>
+
+<li class="martop04">Derbyshire, lead veins of, <a href="#page497">497.</a></li>
+
+<li class="martop04">Deshayes, M., identification of shells, <a href="#page176">176.</a></li>
+  <li class="add2em">on fossil shells in Hungary, <a href="#page421">421.</a></li>
+  <li class="add2em">on Lower Eocene shells, <a href="#page196">196.</a></li>
+  <li class="add2em">on tertiary classification, <a href="#page110">110.</a></li>
+
+<li class="martop04">Desmarest, cited, <a href="#page183">183.</a></li>
+  <li class="add2em">on trappean rocks, <a href="#page91">91.</a></li>
+
+<li class="martop04">Desnoyers, M., on Faluns of Touraine, <a href="#page106">106.</a></li>
+
+<li class="martop04">Desor, M., on glacial fauna in N. America, <a href="#page133">133.</a></li>
+
+<li class="martop04">Devonian flora, <a href="#page349">349</a>.</li>
+  <li class="add2em">strata in United States, <a href="#page349">349.</a></li>
+  <li class="add2em">system, term explained, <a href="#page346">346.</a></li>
+
+<li class="martop04">Diagonal, or cross stratification, <a href="#page16">16.</a></li>
+
+<li class="martop04">Dicotyledonous leaves in chalk, Postscript, <a href="#pagexvi">xvi.</a></li>
+
+<li class="martop04">Dike in St. Helena, <a href="#page406">406.</a></li>
+
+<li class="martop04">Dikes at Palagonia in Sicily, <a href="#page407">407.</a></li>
+  <li class="add2em">trappean, crystalline in centre, <a href="#page380">380.</a></li>
+  <li class="add2em">defined, <a href="#page6">6.</a></li>
+  <li class="add2em">in Scotland, <a href="#page378">378.</a></li>
+  <li class="add2em">of Somma, <a href="#page404">404.</a></li>
+
+<li class="martop04">Diluvium, popular explanation of term, <a href="#page132">132.</a></li>
+
+<li class="martop04">Dip, term explained, <a href="#page53">53.</a></li>
+
+<li class="martop04">Dolerite, or greenstone, <a href="#page372">372.</a></li>
+
+<li class="martop04">Dolomite defined, <a href="#page13">13.</a></li>
+
+<li class="martop04">Dolomitic conglomerate, <a href="#page305">305.</a></li>
+
+<li class="martop04">Doue, M. B. de, on volcanos of Velay, <a href="#page428">428.</a></li>
+
+<li class="martop04">Drift contorted, near Cromer, <a href="#page129">129.</a></li>
+  <li class="add2em">in Ireland, <a href="#page131">131.</a></li>
+  <li class="add2em">in Norfolk, <a href="#page126">126.</a></li>
+  <li class="add2em">meteorites in, <a href="#page145">145.</a></li>
+  <li class="add2em">northern, in Scotland, <a href="#page125">125.</a></li>
+  <li class="add2em">northern, in North Wales, <a href="#page130">130.</a></li>
+  <li class="add2em">of Scandinavia, North Germany, and Russia, <a href="#page121">121.</a></li>
+  <li class="add2em">period, climate of, <a href="#page139">139.</a></li>
+  <li class="add2em">period, subsidence in, <a href="#page135">135.</a></li>
+  <li class="add2em">shells in Canada, <a href="#page134">134.</a></li>
+
+<li class="martop04">Dudley limestone, <a href="#page354">354.</a></li>
+  <li class="add2em">shales of coal near, <a href="#page474">474.</a></li>
+
+<li class="martop04">Dufr�noy, M., on granite of Pyrenees, <a href="#page475">475.</a></li>
+
+<li class="martop04">Duff, Mr. P., on reptile of Old Red, Postscript, <a href="#pageix">ix.</a></li>
+  <li class="add2em">on hill of Gergovia, <a href="#page430">430.</a></li>
+
+<li class="martop04">Dunker, Dr., on Wealden of Hanover, <a href="#page237">237.</a></li>
+</ul>
+
+
+<h3>E.</h3>
+<ul>
+<li class="martop04">Echinoderms of coralline crag, <a href="#page166">166.</a></li>
+
+<li class="martop04">Echinus, figure of, <a href="#page23">23.</a></li>
+
+<li class="martop04">Egerton, Mr., on fossils of Southern India, <a href="#page225">225.</a></li>
+
+<li class="martop04">Egerton, Sir P., on fish of marl slate, <a href="#page304">304.</a></li>
+  <li class="add2em">on fossil fish of Connecticut beds, <a href="#page300">300.</a></li>
+  <li class="add2em">on fossils of Isle of Wight, <a href="#page198">198.</a></li>
+  <li class="add2em">on saurians and fish in New Red Sandstone, <a href="#page289">289.</a></li>
+  <li class="add2em">on Ichthyosaurus, <a href="#page276">276.</a></li>
+
+<li class="martop04">Eggs, fossil, of snake, <a href="#page120">120.</a></li>
+
+<li class="martop04">Ehrenberg, Prof., on bog-iron ore, <a href="#page26">26.</a></li>
+  <li class="add2em">on infusoria, <a href="#page24">24.</a></li>
+
+<li class="martop04">Elephant bed, Brighton, <a href="#page256">256.</a></li>
+
+<li class="martop04"><i>Elephas primigenius</i>, jaw figured, <a href="#page159">159.</a></li>
+
+<li class="martop04">Elvans of Ireland and Cornwall, <a href="#page498">498.</a></li>
+  <li class="add2em">term explained, <a href="#page457">457.</a></li>
+
+<li class="martop04">Encrinites, figure of, <a href="#page264">264.</a></li>
+
+<li class="martop04">Endogens, <a href="#page316">316.</a></li>
+
+<li class="martop04">Eocene, foraminifera, <a href="#page194">194.</a></li>
+  <li class="add2em">formations, <a href="#page174">174.</a></li>
+  <li class="add2em">formations in England, <a href="#page197">197.</a></li>
+  <li class="add2em">granite, <a href="#page451">451.</a></li>
+  <li class="add2em">lower, in France, <a href="#page176">176</a>-<a href="#page191">191.</a></li>
+  <li class="add2em">middle, in France, <a href="#page191">191.</a></li>
+  <li class="add2em">strata, in United States, <a href="#page206">206.</a></li>
+  <li class="add2em">upper, near Louvain, <a href="#page177">177.</a></li>
+  <li class="add2em">term defined, <a href="#page111">111.</a></li>
+  <li class="add2em">upper, of Central France, <a href="#page178">178.</a></li>
+  <li class="add2em">volcanic rocks, <a href="#page429">429.</a></li>
+
+<li class="martop04">Equisetace�, <a href="#page313">313.</a></li>
+
+<li class="martop04">Equisetum of Virginian oolite, <a href="#page284">284.</a></li>
+
+<li class="martop04"><i>Equisetum</i> giganteum, <a href="#page314">314.</a></li>
+
+<li class="martop04">Erman on meteoric iron in Russia, <a href="#page145">145.</a></li>
+
+<li class="martop04">Erratics, Alpine, <a href="#page140">140.</a></li>
+  <li class="add2em">northern origin of, <a href="#page123">123.</a></li>
+
+<li class="martop04">Escher, M., on boulders of Jura, <a href="#page143">143.</a></li>
+
+<li class="martop04">Etna, deposits of, <a href="#page401">401.</a></li>
+
+<li class="martop04">Eurite, <a href="#page440">440.</a></li>
+
+<li class="martop04">Euritic porphyry described, <a href="#page447">447.</a></li>
+
+<li class="martop04">Exogens, <a href="#page316">316.</a></li>
+</ul>
+
+
+<h3>F.</h3>
+<ul>
+<li class="martop04">Faluns of Touraine, <a href="#page106">106.</a> <a href="#page168">168.</a></li>
+
+<li class="martop04">Faluns, comparison of, and crag, <a href="#page170">170.</a></li>
+
+<li class="martop04">Falconer, Dr., on Sew�lik Hills, <a href="#page173">173.</a></li>
+
+<li class="martop04">Falkland Islands, <a href="#page88">88.</a></li>
+
+<li class="martop04">Farnham, phosphate of lime near, <a href="#page219">219.</a></li>
+
+<li class="martop04">Fault, term explained, <a href="#page62">62.</a></li>
+
+<li class="martop04">Faults, origin of, <a href="#page64">64.</a></li>
+
+<li class="martop04">Faxoe, chalk of, <a href="#page210">210.</a> and Postscript, <a href="#pagexv">xv.</a></li>
+
+<li class="martop04">Felixstow, remains of cetacea found near, <a href="#page166">166.</a></li>
+
+<li class="martop04">Felspar, <a href="#page369">369.</a></li>
+
+<li class="martop04">Ferns in coal-measures, <a href="#page310">310.</a></li>
+
+<li class="martop04">Fife, altered rock in, <a href="#page383">383.</a></li>
+
+<li class="martop04">Fifeshire, trap dike in, <a href="#page434">434.</a></li>
+  <li class="add2em">Megalichthys found in Cannel coal in, <a href="#page336">336.</a></li>
+
+<li class="martop04">Fishes, fossil, of Upper Cretaceous, <a href="#page214">214.</a></li>
+  <li class="add2em">of Old Red Sandstone, <a href="#page343">343.</a></li>
+  <li class="add2em">of Wealden, <a href="#page229">229.</a></li>
+  <li class="add2em">fossil, of brown coal, <a href="#page416">416.</a></li>
+
+<li class="martop04">Fissures filled with metallic matter, <a href="#page490">490.</a></li>
+  <li class="add2em"><i>See</i> <a href="#mineralv">mineral veins</a>.</li>
+
+<li class="martop04">Fitton, Dr., on division of lower cretaceous formation, <a href="#page219">219.</a></li>
+  <li class="add2em">cited, <a href="#page227">227.</a> <a href="#page231">231.</a> <a href="#page233">233.</a> <a href="#page237">237.</a> <a href="#page244">244.</a> <a href="#page247">247.</a></li>
+
+<li class="martop04">Fleming, Dr., on scales of fish in Old Red, <a href="#page343">343.</a></li>
+  <li class="add2em">on trap-rocks in coal-field of Forth, <a href="#page432">432.</a></li>
+  <li class="add2em">on trap dike in Fifeshire, <a href="#page434">434.</a></li>
+
+<li class="martop04">Flora, carboniferous, <a href="#page310">310.</a></li>
+  <li class="add2em">cretaceous, <a href="#page223">223.</a></li>
+  <li class="add2em">Devonian, <a href="#page349">349.</a></li>
+  <li class="add2em">of London Clay, <a href="#page200">200.</a></li>
+  <li class="add2em">permian, <a href="#page305">305.</a> <a href="#page307">307.</a></li>
+
+<li class="martop04">Fl�tz, term explained, <a href="#page91">91.</a></li>
+
+<li class="martop04">Flysch, explanation of term, <a href="#page206">206.</a></li>
+
+<li class="martop04">Footprints of birds, <a href="#page297">297.</a> and Postscript, <a href="#pagexx">xx.</a></li>
+  <li class="add2em">of reptilians, <a href="#page337">337.</a></li>
+  <li class="add2em">fossil, <a href="#page289">289.</a> <a href="#page290">290.</a> <a href="#page291">291.</a> <a href="#page297">297.</a></li>
+
+<li class="martop04">Foraminifera in chalk, <a href="#page26">26.</a></li>
+  <li class="add2em">Eocene, <a href="#page194">194.</a></li>
+
+<li class="martop04">Forbes, Prof. E., on Caradoc sandstone, <a href="#page359">359.</a></li>
+  <li class="add2em">on Cystide�, <a href="#page358">358.</a></li>
+  <li class="add2em">on shells in crag deposits, <a href="#page162">162.</a></li>
+  <li class="add2em">on cretaceous fossil shells, <a href="#page224">224.</a></li>
+  <li class="add2em">on fossils of the faluns, <a href="#page169">169.</a></li>
+  <li class="add2em">on fossils in drift in South Ireland, <a href="#page131">131.</a></li>
+  <li class="add2em">on deep-sea origin of Silurian strata, <a href="#page360">360.</a></li>
+  <li class="add2em">on echinoderms of coralline crag, <a href="#page166">166.</a></li>
+<li class="add2em"><span class="pagenum"><a id="page506"></a>[p.506]</span>on fauna of boulder period, <a href="#page125">125.</a></li>
+  <li class="add2em">on migrations of mollusca in glacial period, <a href="#page166">166.</a></li>
+  <li class="add2em">on fossils of Purbeck group, <a href="#page231">231.</a> <a href="#page233">233.</a></li>
+  <li class="add2em">on strata at Atherfield, <a href="#page219">219.</a></li>
+  <li class="add2em">on changes of Wealden testacea, <a href="#page235">235.</a></li>
+  <li class="add2em">on volcanic rocks of Oolite period, <a href="#page432">432.</a></li>
+  <li class="add2em">on depth of animal life in �gean, <a href="#page35">35.</a> <a href="#page137">137.</a></li>
+  <li class="add2em">cited, <a href="#page225">225.</a></li>
+
+<li class="martop04">Forbes, Prof. James, on zones in volcanic rocks, <a href="#page480">480.</a></li>
+  <li class="add2em">on the Alps, <a href="#page143">143.</a></li>
+
+<li class="martop04">Forchhammer, on scratched limestone, <a href="#page122">122.</a></li>
+
+<li class="martop04">Forest, fossil, in Norfolk, <a href="#page127">127.</a> <a href="#page130">130.</a></li>
+
+<li class="martop04">Forfarshire, Old Red Sandstone in, <a href="#page479">479.</a></li>
+
+<li class="martop04">Formation, term defined, <a href="#page3">3.</a></li>
+
+<li class="martop04">Fossil, term defined, <a href="#page4">4.</a></li>
+
+<li class="martop04">Fossils of chalk and greensand, figures of, <a href="#page212">212.</a></li>
+  <li class="add2em">in chalk at Faxoe, <a href="#page210">210.</a></li>
+  <li class="add2em">of coralline crag, <a href="#page164">164.</a></li>
+  <li class="add2em">of Devonian system, <a href="#page346">346.</a> and Postscript, <a href="#pagex">x.</a> <a href="#pagexi">xi.</a></li>
+  <li class="add2em">of Eocene strata in United States, <a href="#page207">207.</a></li>
+  <li class="add2em">in faluns of Touraine, <a href="#page169">169.</a></li>
+  <li class="add2em">freshwater and marine, <a href="#page27">27.</a></li>
+  <li class="add2em">of Isle of Wight, <a href="#page198">198.</a></li>
+  <li class="add2em">of Lias, <a href="#page274">274.</a></li>
+  <li class="add2em">of Ludlow formation, <a href="#page352">352.</a></li>
+  <li class="add2em">of mountain limestone, <a href="#page340">340.</a></li>
+  <li class="add2em">of London Clay, <a href="#page200">200.</a></li>
+  <li class="add2em">of Maestricht beds, <a href="#page209">209.</a></li>
+  <li class="add2em">of Lower Greensand, <a href="#page220">220.</a></li>
+  <li class="add2em">of New Red Sandstone, <a href="#page287">287.</a> and Postscript, <a href="#pagexiii">xiii.</a></li>
+  <li class="add2em">of Oolite, <a href="#page259">259.</a> <a href="#page266">266.</a></li>
+  <li class="add2em">of Red Crag, <a href="#page164">164.</a></li>
+  <li class="add2em">of Silurian rocks, <a href="#page353">353.</a> and Postscript, <a href="#pagevii">vii.</a></li>
+  <li class="add2em">of Solenhofen, <a href="#page260">260.</a></li>
+  <li class="add2em">of Upper Greensand, <a href="#page218">218.</a></li>
+  <li class="add2em">of Wealden, <a href="#page236">236.</a></li>
+  <li class="add2em">test of the age of formations, <a href="#page98">98.</a></li>
+
+<li class="martop04">Fossil fish of Permian limestone, <a href="#page303">303.</a></li>
+  <li class="add2em">of Connecticut beds, <a href="#page300">300.</a></li>
+  <li class="add2em">of Richmond, U. S., strata, <a href="#page285">285.</a></li>
+  <li class="add2em">of Old Red Sandstone, <a href="#page343">343.</a></li>
+  <li class="add2em">scales of Permian, figured, <a href="#page305">305.</a></li>
+  <li class="add2em">footsteps, <a href="#page289">289.</a> <a href="#page290">290.</a> <a href="#page291">291.</a></li>
+  <li class="add2em">ferns in carbonaceous shale, <a href="#page271">271.</a></li>
+  <li class="add2em">forest in Nova Scotia, <a href="#page321">321.</a></li>
+  <li class="add2em">forest near Wolverhampton, <a href="#page319">319.</a></li>
+  <li class="add2em">forest in Isle of Portland, <a href="#page233">233.</a></li>
+  <li class="add2em">plants in Wealden, <a href="#page230">230.</a></li>
+  <li class="add2em">plants of Lias, <a href="#page282">282.</a></li>
+  <li class="add2em">plants of Bunter sandstein, <a href="#page288">288.</a></li>
+  <li class="add2em">trees erect, <a href="#page317">317.</a></li>
+  <li class="add2em">wood, petrifaction of, <a href="#page39">39.</a></li>
+  <li class="add2em">wood perforated by Teredina, <a href="#page24">24.</a></li>
+  <li class="add2em">remains in caves, <a href="#page154">154.</a></li>
+  <li class="add2em">shells from Etna, <a href="#page401">401.</a></li>
+  <li class="add2em">shells near Grignon, <a href="#page193">193.</a></li>
+  <li class="add2em">shells of Mayence strata, <a href="#page178">178.</a></li>
+  <li class="add2em">shells in Virginia, <a href="#page172">172.</a></li>
+
+<li class="martop04">Fossiliferous strata, tabular view of, <a href="#page361">361.</a></li>
+
+<li class="martop04">Fournet, M., on mineral veins of Auvergne, <a href="#page493">493.</a></li>
+  <li class="add2em">on disintegration of rocks, <a href="#page476">476.</a></li>
+  <li class="add2em">on quartz, <a href="#page439">439.</a></li>
+
+<li class="martop04">Fox, Mr. R. W., <a href="#page472">472.</a></li>
+  <li class="add2em">on Cornish lodes, <a href="#page497">497.</a></li>
+
+<li class="martop04">Fox, Rev. Mr., on extinct quadrupeds of Isle of Wight, <a href="#page198">198.</a></li>
+
+<li class="martop04">Freshwater beds of Isle of Wight, <a href="#page197">197.</a></li>
+  <li class="add2em">deposits in valley of Thames, <a href="#page146">146.</a></li>
+  <li class="add2em">land shells numerous in, <a href="#page27">27.</a></li>
+
+<li class="martop04">Freshwater formations of Auvergne, <a href="#page186">186.</a></li>
+
+<li class="martop04">Freshwater formation, how distinguished from marine, <a href="#page27">27.</a> <a href="#page28">28.</a> <a href="#page30">30.</a></li>
+  <li class="add2em">remains of fish in, <a href="#page32">32.</a></li>
+  <li class="add2em">associated with Norfolk drift, <a href="#page127">127.</a></li>
+  <li class="add2em">Chara in, <a href="#page31">31.</a></li>
+  <li class="add2em">Cypris in, <a href="#page31">31.</a></li>
+
+<li class="martop04">Freshwater shells in brown coal near Bonn, <a href="#page417">417.</a></li>
+
+<li class="martop04"><i>Fucus giganteus</i>, <a href="#page217">217.</a></li>
+  <li class="add2em"><i>vesiculosus</i>, growth of, in Jutland, <a href="#page217">217.</a></li>
+  <li class="add2em"><i>vesiculosus</i> in Lym-Fiord, <a href="#page33">33.</a></li>
+
+<li class="martop04">Fundy, Bay of, impressions in red mud of, <a href="#page297">297.</a></li>
+</ul>
+
+
+<h3>G.</h3>
+<ul>
+<li class="martop04">Gaillonella fossil in Tripoli, <a href="#page25">25.</a></li>
+  <li class="add2em">ferruginea in bog-iron ore, <a href="#page26">26.</a></li>
+
+<li class="martop04">Galapagos Islands, animals of, <a href="#page279">279.</a></li>
+
+<li class="martop04">Garnets in altered rock, <a href="#page382">382.</a></li>
+
+<li class="martop04">Gases, subterranean rocks altered by, <a href="#page476">476.</a></li>
+
+<li class="martop04">Gault, <a href="#page218">218.</a></li>
+
+<li class="martop04">Gavarnie, flexures of strata, <a href="#page59">59.</a></li>
+
+<li class="martop04">Geology defined, <a href="#page1">1.</a></li>
+
+<li class="martop04">Gergovia, hill of, <a href="#page430">430.</a></li>
+
+<li class="martop04">Giant's Causeway, columns at, <a href="#page384">384.</a></li>
+
+<li class="martop04">Gibbes, R. W., cited, <a href="#page207">207.</a></li>
+
+<li class="martop04">Glacial phenomena, northern, origin of, <a href="#page132">132.</a></li>
+
+<li class="martop04">Glaciers, Alpine, <a href="#page140">140.</a></li>
+
+<li class="martop04">Glaciers on Caernarvonshire mountains, <a href="#page130">130.</a></li>
+
+<li class="martop04">Glasgow, marine strata near, <a href="#page148">148.</a></li>
+
+<li class="martop04">Glen Roy, parallel roads of, <a href="#page86">86.</a></li>
+
+<li class="martop04">Glen Tilt, granite of, <a href="#page442">442.</a></li>
+
+<li class="martop04">Gneiss, altered by granite, <a href="#page445">445.</a></li>
+  <li class="add2em">in Bernese Alps, <a href="#page484">484.</a></li>
+  <li class="add2em">at Cape Wrath, <a href="#page444">444.</a></li>
+  <li class="add2em">near Christiania, <a href="#page446">446.</a></li>
+  <li class="add2em">described, <a href="#page464">464.</a></li>
+
+<li class="martop04">Gold, age of, in Ireland, <a href="#page498">498.</a></li>
+  <li class="add2em">age of, in Ural Mountains, <a href="#page499">499.</a></li>
+
+<li class="martop04">Goldfuss, Prof., on reptiles in coal-field, <a href="#page336">336.</a></li>
+
+<li class="martop04">G�ppert, Prof., on beds of coal, <a href="#page316">316.</a></li>
+  <li class="add2em">on petrifaction, <a href="#page40">40.</a></li>
+
+<li class="martop04">Graham's Island, <a href="#page389">389.</a> <a href="#page407">407.</a></li>
+
+<li class="martop04">Grampians, old red conglomerates in, <a href="#page47">47.</a></li>
+
+<li class="martop04">Granite described, <a href="#page7">7.</a> <a href="#page436">436.</a> <a href="#page438">438.</a> <a href="#page444">444.</a></li>
+  <li class="add2em">passage of into trap, <a href="#page441">441.</a></li>
+  <li class="add2em">porphyritic, <a href="#page439">439.</a></li>
+  <li class="add2em">and limestone, junction of in Glen Tilt, <a href="#page442">442.</a></li>
+  <li class="add2em">syenitic, <a href="#page440">440.</a></li>
+  <li class="add2em">talcose, <a href="#page440">440.</a></li>
+  <li class="add2em">schorly, <a href="#page440">440.</a></li>
+  <li class="add2em">of Cornwall and Dartmoor, <a href="#page474">474.</a></li>
+  <li class="add2em">of Swiss Alps, <a href="#page484">484.</a></li>
+  <li class="add2em">rocks in connection with mineral veins, <a href="#page500">500.</a></li>
+  <li class="add2em">of Saxony, <a href="#page459">459.</a></li>
+
+<li class="martop04">Granites, oldest, <a href="#page458">458.</a></li>
+  <li class="add2em">varieties of, <a href="#page444">444.</a></li>
+  <li class="add2em">veins in Cornwall, <a href="#page445">445.</a></li>
+  <li class="add2em">veins in Cape Wrath, <a href="#page444">444.</a></li>
+  <li class="add2em">veins in Table Mountain, <a href="#page443">443.</a></li>
+  <li class="add2em">vein in White Mountains, <a href="#page450">450.</a></li>
+  <li class="add2em">of Arran, age of, <a href="#page459">459.</a></li>
+  <li class="add2em">near Christiania, <a href="#page457">457.</a></li>
+  <li class="add2em">dikes in Mount Battock, <a href="#page443">443.</a></li>
+
+<li class="martop04">Graphite, powder of, consolidated by pressure, <a href="#page38">38.</a></li>
+
+<li class="martop04">Graptolites, <a href="#page357">357.</a></li>
+
+<li class="martop04">Grateloup, M., on fossils in chalk, <a href="#page223">223.</a></li>
+
+<li class="martop04">Grauwacke, term explained, <a href="#page350">350.</a></li>
+
+<li class="martop04">Greenland, sinking of coast, <a href="#page46">46.</a></li>
+
+<li class="martop04">Greensand, upper, <a href="#page218">218.</a></li>
+  <li class="add2em">fossils of, <a href="#page212">212.</a></li>
+
+<li class="martop04">Greensburg, Pennsylvania, footprints of reptile in coal strata at, <a href="#page337">337.</a></li>
+
+<li class="martop04">Greenstone or Dolerite, <a href="#page372">372.</a></li>
+  <li class="add2em">dike of, in Arran, <a href="#page379">379.</a></li>
+
+<li class="martop04">Gr�s de Beauchamp, Paris Basin, <a href="#page193">193.</a></li>
+
+<li class="martop04">Grignon, fossil shells near, <a href="#page193">193.</a></li>
+
+<li class="martop04">Grit defined, <a href="#page11">11.</a></li>
+
+<li class="martop04">Guadaloupe, human skeleton of, <a href="#page115">115.</a></li>
+
+<li class="martop04">Guidoni on Carrara marble, <a href="#page482">482.</a></li>
+
+<li class="martop04">Gutbier, Col. von, on Permian flora, <a href="#page305">305.</a> <a href="#page307">307.</a></li>
+
+<li class="martop04">Gryph�a, fossil figure of, <a href="#page22">22.</a></li>
+
+<li class="martop04">Gypseous marls, <a href="#page186">186.</a></li>
+  <li class="add2em">series, <a href="#page191">191.</a></li>
+
+<li class="martop04">Gypsum defined, <a href="#page13">13.</a></li>
+</ul>
+
+
+<h3><span class="pagenum"><a id="page507"></a>[p.507]</span>H.</h3>
+<ul>
+<li class="martop04">Hall, Sir Jas., experiments on fused minerals, <a href="#page406">406.</a></li>
+  <li class="add2em">on curved strata, <a href="#page48">48.</a></li>
+  <li class="add2em">Capt. B., cited, <a href="#page378">378.</a> <a href="#page401">401.</a> <a href="#page443">443.</a></li>
+
+<li class="martop04">Hamilton, Sir W., on eruption of Vesuvius, <a href="#page405">405.</a></li>
+
+<li class="martop04">Harris, Major, on salt lake in Ethiopia, <a href="#page296">296.</a></li>
+
+<li class="martop04">Hartz, Bunter sandstein of, <a href="#page288">288.</a></li>
+
+<li class="martop04">Hastings, Lady, fossils collected by, <a href="#page198">198.</a></li>
+
+<li class="martop04">Hastings sand, <a href="#page229">229.</a></li>
+  <li class="add2em">bed, shells of, <a href="#page229">229.</a></li>
+
+<li class="martop04">Hautes Alpes, rocks of, <a href="#page455">455.</a></li>
+
+<li class="martop04">Ha�y cited, <a href="#page369">369.</a></li>
+
+<li class="martop04">Hawkshaw, Mr., on fossil trees in coal, <a href="#page317">317.</a></li>
+
+<li class="martop04">Hayes, T. L., on icebergs, <a href="#page123">123.</a></li>
+
+<li class="martop04">H�bert, M., cited on Upper Eocene beds, <a href="#page176">176.</a></li>
+
+<li class="martop04">Hebrides, dikes of trap in, <a href="#page379">379.</a></li>
+
+<li class="martop04">Heidelberg, varieties of granite near, <a href="#page444">444.</a></li>
+
+<li class="martop04">Henfrey, Mr. A., on food of Mastodon, <a href="#page138">138.</a></li>
+
+<li class="martop04">Henslow, Prof., on fossil cetacea in Suffolk, <a href="#page166">166.</a></li>
+  <li class="add2em">on fossil forests, <a href="#page233">233.</a></li>
+  <li class="add2em">on dike and altered rock near Plas Newydd, <a href="#page381">381.</a></li>
+
+<li class="martop04">Henry, Mr., cited, <a href="#page476">476.</a></li>
+
+<li class="martop04">Herschel, Sir J., on slaty cleavage, <a href="#page472">472.</a></li>
+
+<li class="martop04">Hertfordshire pudding-stone, <a href="#page35">35.</a></li>
+
+<li class="martop04">Hibbert, Dr., on volcanic rocks, <a href="#page428">428.</a></li>
+  <li class="add2em">on coal field at Burdiehouse, <a href="#page325">325.</a></li>
+  <li class="add2em">cited, <a href="#page419">419.</a></li>
+
+<li class="martop04">High Teesdale, garnets in altered rock at, <a href="#page382">382.</a></li>
+
+<li class="martop04">Hildburghausen, footprints of reptile at, <a href="#page289">289.</a> <a href="#page290">290.</a></li>
+
+<li class="martop04">Hippurite limestone, <a href="#page221">221.</a></li>
+
+<li class="martop04">Hitchcock, Prof., on footprints, <a href="#page297">297.</a></li>
+
+<li class="martop04">Hoffmann, Mr., on Lipari Islands, cited, <a href="#page476">476.</a></li>
+  <li class="add2em">on cave near Palermo, <a href="#page74">74.</a></li>
+  <li class="add2em">on Carrara marble, <a href="#page482">482.</a></li>
+
+<li class="martop04">Hooghly river, analysis of water, <a href="#page41">41.</a></li>
+
+<li class="martop04">Hopkins, Mr., on fractures in Weald, <a href="#page251">251.</a></li>
+
+<li class="martop04">Horizontality of strata, <a href="#page15">15.</a></li>
+  <li class="add2em">of roads of Lochaber, <a href="#page88">88.</a></li>
+
+<li class="martop04">Hornblende, <a href="#page369">369.</a></li>
+  <li class="add2em">schist, <a href="#page464">464.</a> <a href="#page478">478.</a></li>
+
+<li class="martop04">Horner, Mr., on geology of Eifel, <a href="#page415">415.</a></li>
+  <li class="add2em">on Megalichthys, <a href="#page336">336.</a></li>
+
+<li class="martop04">Hubbard, Prof., on granite vein in White Mountains, <a href="#page450">450.</a></li>
+
+<li class="martop04">Hugi, M., on Swiss Alps, <a href="#page484">484.</a></li>
+
+<li class="martop04">Humboldt, cited, <a href="#page314">314.</a></li>
+  <li class="add2em">on uniform character of rocks, <a href="#page486">486.</a></li>
+
+<li class="martop04">Hungary, trachyte of, <a href="#page442">442.</a></li>
+  <li class="add2em">volcanic rocks of, <a href="#page421">421.</a></li>
+
+<li class="martop04">Hunt, Mr., experiments on clay-ironstone, <a href="#page326">326.</a></li>
+
+<li class="martop04">Hutton, opinions of, <a href="#page60">60.</a></li>
+
+<li class="martop04">Huttonian theory, <a href="#page92">92.</a></li>
+
+<li class="martop04">Hypogene, term defined, <a href="#page9">9.</a></li>
+  <li class="add2em">rocks, mineral character of, <a href="#page485">485.</a></li>
+  <li class="add2em">or metamorphic limestone, <a href="#page465">465.</a></li>
+</ul>
+
+
+<h3>I.</h3>
+<ul>
+<li class="martop04">Ibbetson, Capt., on chalk Isle of Wight, <a href="#page215">215.</a></li>
+
+<li class="martop04">Ice, rocks drifted by, <a href="#page122">122.</a></li>
+
+<li class="martop04">Icebergs, stranding of, <a href="#page129">129.</a> <a href="#page137">137.</a></li>
+
+<li class="martop04">Iceland, icebergs drifted to, <a href="#page137">137.</a></li>
+
+<li class="martop04">Ichthyolites of Old Red Sandstone, <a href="#page349">349.</a></li>
+
+<li class="martop04"><i>Ichthyosaurus communis</i>, figure of, <a href="#page277">277.</a></li>
+
+<li class="martop04">Igneous rocks, <a href="#page6">6.</a></li>
+  <li class="add2em">of Siebengebirge and Westerwald, <a href="#page417">417.</a></li>
+  <li class="add2em">rocks of Val di Noto, <a href="#page389">389.</a></li>
+
+<li class="martop04"><i>Iguanodon Mantelli</i>, <a href="#page227">227.</a> <a href="#page229">229.</a></li>
+
+<li class="martop04">India, cretaceous system in, <a href="#page225">225.</a></li>
+  <li class="add2em">freshwater deposits of, <a href="#page173">173.</a></li>
+  <li class="add2em">oolitic formation in, <a href="#page285">285.</a></li>
+
+<li class="martop04">Indusial limestone, Auvergne, <a href="#page184">184.</a></li>
+
+<li class="martop04">Infusoria in tripoli, <a href="#page24">24.</a></li>
+
+<li class="martop04">Inland sea-cliffs in South of England, <a href="#page71">71.</a></li>
+
+<li class="martop04">Insects in Lias, <a href="#page281">281.</a></li>
+
+<li class="martop04">Ireland, drift in, <a href="#page131">131.</a></li>
+
+<li class="martop04">Ischia, volcanic cones in, <a href="#page403">403.</a></li>
+  <li class="add2em">Post-Pliocene strata of, <a href="#page113">113.</a></li>
+
+<li class="martop04">Isle of Wight, freshwater beds of, <a href="#page197">197.</a></li>
+
+<li class="martop04">Isomorphism, theory of, <a href="#page370">370.</a></li>
+</ul>
+
+
+<h3>J.</h3>
+<ul>
+<li class="martop04">Jackson, Dr. C. T., analysis of fossil bones, <a href="#page138">138.</a></li>
+
+<li class="martop04">James, Capt., on fossils in drift South Ireland, <a href="#page131">131.</a></li>
+
+<li class="martop04">Java, stream of sulphureous water, <a href="#page191">191.</a></li>
+
+<li class="martop04">Jobert, M., on hill of Gergovia, <a href="#page430">430.</a></li>
+
+<li class="martop04">Joints, <a href="#page469">469.</a></li>
+
+<li class="martop04">Jorullo, lava stream of, <a href="#page450">450.</a></li>
+
+<li class="martop04">Jura, alpine blocks on, <a href="#page142">142.</a></li>
+  <li class="add2em">limestone, <a href="#page261">261.</a></li>
+  <li class="add2em">structure of, <a href="#page55">55.</a></li>
+</ul>
+
+
+<h3>K.</h3>
+<ul>
+<li class="martop04">Kangaroo, fossil and recent, jaws figured, <a href="#page156">156.</a></li>
+
+<li class="martop04">Kaup, Prof., on footprints of Cheirotherium, <a href="#page290">290.</a></li>
+
+<li class="martop04">Kaye, Mr., on fossils of Southern India, <a href="#page225">225.</a></li>
+
+<li class="martop04">Keeling Island, fragment of greenstone in, <a href="#page217">217.</a></li>
+
+<li class="martop04">Keilhau, Prof., cited, <a href="#page457">457.</a> <a href="#page474">474.</a></li>
+  <li class="add2em">on dike of greenstone, <a href="#page380">380.</a></li>
+  <li class="add2em">on gneiss near Christiania, <a href="#page446">446.</a></li>
+  <li class="add2em">on granite, <a href="#page447">447.</a></li>
+
+<li class="martop04">Kelloway rock, <a href="#page34">34.</a></li>
+
+<li class="martop04">Kentish chalk, sand-galls in, <a href="#page82">82.</a></li>
+
+<li class="martop04">Keuper, the, <a href="#page287">287.</a></li>
+
+<li class="martop04">Killas in granite of Cornwall, <a href="#page474">474.</a></li>
+
+<li class="martop04">Kimmeridge clay, <a href="#page260">260.</a> and Postscript, <a href="#pagexxi">xxi.</a></li>
+
+<li class="martop04">King, Dr., on footprints of reptile, <a href="#page337">337.</a></li>
+
+<li class="martop04">King, Mr., on Permian group and fossils, <a href="#page301">301.</a> <a href="#page302">302.</a></li>
+
+<li class="martop04">Kirkdale, cave at, <a href="#page154">154.</a></li>
+
+<li class="martop04">Kotzebue cited, <a href="#page217">217.</a></li>
+
+<li class="martop04">Kyson, in Suffolk, strata of, <a href="#page202">202.</a></li>
+</ul>
+
+
+<h3>L.</h3>
+<ul>
+<li class="martop04">Labyrinthodon, <a href="#page292">292.</a> <a href="#page288">288.</a> <a href="#page289">289.</a></li>
+
+<li class="martop04">Lacustrine strata of Auvergne, <a href="#page181">181.</a></li>
+
+<li class="martop04">Lagoons at mouth of rivers, <a href="#page33">33.</a></li>
+  <li class="add2em">of Bermuda Islands, <a href="#page216">216.</a></li>
+
+<li class="martop04">Lake craters of Eifel, <a href="#page419">419.</a></li>
+  <li class="add2em">crater of Laach, <a href="#page420">420.</a></li>
+
+<li class="martop04">Lamarck on bivalve mollusca, <a href="#page29">29.</a></li>
+
+<li class="martop04">Land, rising and sinking, <a href="#page45">45.</a></li>
+
+<li class="martop04">Laterite, <a href="#page376">376.</a></li>
+
+<li class="martop04">Lava, <a href="#page373">373.</a></li>
+  <li class="add2em">current, Auvergne, <a href="#page425">425.</a></li>
+  <li class="add2em">relation to trap, <a href="#page387">387.</a></li>
+  <li class="add2em">stream of Jorullo, <a href="#page450">450.</a></li>
+  <li class="add2em">of Stromboli, <a href="#page450">450.</a></li>
+
+<li class="martop04">Lea, Mr., footprints of reptile discovered by, <a href="#page340">340.</a></li>
+
+<li class="martop04">Lead, veins of, in Permian rocks, <a href="#page499">499.</a></li>
+
+<li class="martop04">Lehman on classification of rocks, <a href="#page90">90.</a></li>
+
+<li class="martop04">Leibnitz, theory of, <a href="#page94">94.</a></li>
+
+<li class="martop04">Lepidodendra, <a href="#page312">312.</a></li>
+
+<li class="martop04">Lewes, coomb near, <a href="#page250">250.</a></li>
+
+<li class="martop04">Lias, <a href="#page273">273.</a></li>
+  <li class="add2em">period, Volcanic rocks, <a href="#page431">431.</a></li>
+  <li class="add2em">at Lyme Regis, <a href="#page281">281.</a></li>
+  <li class="add2em">plutonic rocks of, <a href="#page455">455.</a></li>
+  <li class="add2em">and oolite, origin of, <a href="#page282">282.</a></li>
+  <li class="add2em">fossil plants of, <a href="#page282">282.</a></li>
+
+<li class="martop04">Liebig, Prof., on conversion of coal into lignite, <a href="#page333">333.</a></li>
+  <li class="add2em">on preservation of fossil bones in caverns, <a href="#page155">155.</a></li>
+
+<li class="martop04">Lima, recent strata of, <a href="#page115">115.</a></li>
+
+<li class="martop04">Limagne d'Auvergne, freshwater formations of, <a href="#page187">187.</a></li>
+
+<li class="martop04">Lime, scarcity of, in metamorphic rocks, <a href="#page487">487.</a></li>
+
+<li class="martop04">Limestone, brecciated, <a href="#page302">302.</a></li>
+  <li class="add2em">crystalline, <a href="#page302">302.</a></li>
+  <li class="add2em">compact, <a href="#page303">303.</a></li>
+<li class="add2em"><span class="pagenum"><a id="page508"></a>[p.508]</span>fossiliferous, <a href="#page303">303.</a></li>
+  <li class="add2em">hippurite, <a href="#page221">221.</a></li>
+  <li class="add2em">indusial, Auvergne, <a href="#page184">184.</a></li>
+  <li class="add2em">of Jura, <a href="#page261">261.</a></li>
+  <li class="add2em">magnesian, <a href="#page301">301.</a></li>
+  <li class="add2em">mountain fossils of, <a href="#page340">340.</a></li>
+  <li class="add2em">primary or metamorphic, <a href="#page465">465.</a></li>
+  <li class="add2em">in Germany, of Devonian system, <a href="#page348">348.</a></li>
+
+<li class="martop04">Lindley, Dr., cited, <a href="#page223">223.</a></li>
+  <li class="add2em">on leaves in lignite, <a href="#page416">416.</a></li>
+
+<li class="martop04">Link, M., on footprints, <a href="#page291">291.</a></li>
+
+<li class="martop04">Lipari Islands, rocks altered by gases in, <a href="#page476">476.</a></li>
+
+<li class="martop04">Lisbon, marine tertiary strata near, <a href="#page171">171.</a></li>
+
+<li class="martop04">Lithodomi in beaches of N. America, <a href="#page78">78.</a></li>
+  <li class="add2em">in inland cliffs, <a href="#page73">73.</a></li>
+
+<li class="martop04">Llandeilo flags, <a href="#page357">357.</a></li>
+
+<li class="martop04">Loam defined, <a href="#page13">13.</a></li>
+
+<li class="martop04">Lochaber, parallel roads of, <a href="#page86">86.</a></li>
+
+<li class="martop04">Lodes. <i>See</i> <a href="#mineralv">Mineral Veins</a>, <a href="#page490">490.</a></li>
+
+<li class="martop04">Loess of valley of Rhine, <a href="#page117">117.</a></li>
+  <li class="add2em">fossil land shells of, figured, <a href="#page120">120.</a></li>
+
+<li class="martop04">Logan, Mr., on coal measures of South Wales, <a href="#page310">310.</a></li>
+  <li class="add2em">on fossil forest in Nova Scotia, <a href="#page322">322.</a></li>
+  <li class="add2em">on reptilian foot-prints in lowest Silurian in Canada, Postscript, <a href="#pageviii">viii.</a></li>
+
+<li class="martop04">London clay, <a href="#page200">200.</a></li>
+
+<li class="martop04">Lonsdale, Mr., cited, <a href="#page152">152.</a>; on corals, <a href="#page173">173.</a></li>
+  <li class="add2em">on corals of Normandy, <a href="#page170">170.</a></li>
+  <li class="add2em">on corals in Wenlock formation, <a href="#page355">355.</a></li>
+  <li class="add2em">on fossils in white chalk, <a href="#page26">26.</a></li>
+  <li class="add2em">on old red sandstone of S. Devon, <a href="#page345">345.</a></li>
+  <li class="add2em">on Stonesfield slate, <a href="#page266">266.</a></li>
+
+<li class="martop04">Louvain, Eocene strata near, <a href="#page177">177.</a></li>
+
+<li class="martop04">Lov�n on shells of Norway, <a href="#page114">114.</a></li>
+
+<li class="martop04">Ludlow formation, <a href="#page351">351.</a></li>
+
+<li class="martop04">Lund, cited, <a href="#page158">158.</a></li>
+
+<li class="martop04">Lycett, Mr., on shells of oolite, <a href="#page266">266.</a></li>
+
+<li class="martop04">Lyme Regis, lias at, <a href="#page281">281.</a></li>
+
+<li class="martop04">Lym-Fiord invaded by the sea, <a href="#page33">33.</a></li>
+  <li class="add2em">kelp in, <a href="#page217">217.</a></li>
+
+<li class="martop04">Lyons, coal mine near, <a href="#page319">319.</a></li>
+</ul>
+
+
+<h3>M.</h3>
+<ul>
+<li class="martop04">Macacus, in Eocene formation, <a href="#page203">203.</a></li>
+
+<li class="martop04">Maclaren, Mr., on erratic blocks in Pentlands, <a href="#page125">125.</a></li>
+
+<li class="martop04">Maclure, Dr., on volcanos in Catalonia, <a href="#page409">409.</a></li>
+
+<li class="martop04">MacCulloch, Dr., cited, <a href="#page442">442.</a></li>
+  <li class="add2em">on altered rock in Fife, <a href="#page383">383.</a></li>
+  <li class="add2em">on basaltic columns in Skye, <a href="#page385">385.</a></li>
+  <li class="add2em">on denudation, <a href="#page67">67.</a></li>
+  <li class="add2em">on granite of Aberdeenshire, <a href="#page441">441.</a></li>
+  <li class="add2em">on igneous rocks of Scotland, <a href="#page390">390.</a></li>
+  <li class="add2em">on Isle of Skye, <a href="#page36">36.</a> <a href="#page456">456.</a></li>
+  <li class="add2em">on hornblende schist, <a href="#page478">478.</a></li>
+  <li class="add2em">on overlying rocks, <a href="#page8">8.</a></li>
+  <li class="add2em">on parallel roads, <a href="#page87">87.</a></li>
+  <li class="add2em">on pebbles of granite, <a href="#page460">460.</a></li>
+  <li class="add2em">on trap vein in Argyleshire, <a href="#page379">379.</a></li>
+
+<li class="martop04">Madeira, view of dike in inland valley in, <a href="#page378">378.</a></li>
+
+<li class="martop04">Maestricht beds, <a href="#page209">209.</a></li>
+
+<li class="martop04">Magnesian limestone, concretionary structure of, <a href="#page37">37.</a></li>
+  <li class="add2em">defined, <a href="#page13">13.</a></li>
+  <li class="add2em">groups, <a href="#page301">301.</a></li>
+
+<li class="martop04">Maidstone, fossils in white chalk of, <a href="#page214">214.</a></li>
+
+<li class="martop04">Mammalia, extinct, above drift in United States, <a href="#page138">138.</a></li>
+  <li class="add2em">extinct, of basin of Mississippi, <a href="#page116">116.</a></li>
+  <li class="add2em">fossil teeth of, figured, <a href="#page160">160.</a></li>
+
+<li class="martop04">Mammat's "Geological Facts" cited, <a href="#page69">69.</a></li>
+
+<li class="martop04">Mammifer in trias near Stuttgart, Postscript, <a href="#pagexiii">xiii.</a></li>
+
+<li class="martop04">Mansfield in Thuringia, Permian formation at, <a href="#page306">306.</a></li>
+
+<li class="martop04">Mantell, Dr., cited, <a href="#page217">217.</a> <a href="#page229">229.</a> <a href="#page231">231.</a> <a href="#page251">251.</a></li>
+  <li class="add2em">on belemnite, <a href="#page263">263.</a></li>
+  <li class="add2em">on chalk flints, <a href="#page253">253.</a></li>
+  <li class="add2em">on Brighton elephant bed, <a href="#page257">257.</a></li>
+  <li class="add2em">on freshwater beds of Isle of Wight, <a href="#page198">198.</a></li>
+  <li class="add2em">on iguanodon, <a href="#page227">227.</a></li>
+  <li class="add2em">on Wealden group, <a href="#page226">226.</a></li>
+  <li class="add2em">on reptile in Old Red, Postscript, <a href="#pagex">x.</a></li>
+
+<li class="martop04">Marble defined, <a href="#page12">12.</a></li>
+
+<li class="martop04">Marl defined, <a href="#page13">13.</a></li>
+  <li class="add2em">in Lake Superior, <a href="#page36">36.</a></li>
+  <li class="add2em">red and green in England, <a href="#page289">289.</a></li>
+
+<li class="martop04">Marl-slate defined, <a href="#page13">13.</a></li>
+
+<li class="martop04">Martin, Mr., cited, <a href="#page250">250.</a></li>
+  <li class="add2em">on cross fractures in chalk, <a href="#page245">245.</a></li>
+
+<li class="martop04">Martins, Mr. C., on glaciers of Spitzbergen, <a href="#page136">136.</a></li>
+
+<li class="martop04">Map to illustrate denudation of Weald, <a href="#page242">242.</a></li>
+
+<li class="martop04">Map of Eocene beds of central France, <a href="#page179">179.</a></li>
+
+<li class="martop04">Massachusetts, plumbago in, <a href="#page478">478.</a></li>
+
+<li class="martop04"><i>Mastodon angustidens</i>, jaw, figure of, <a href="#page159">159.</a></li>
+
+<li class="martop04"><i>Mastodon giganteus</i>, in United States, <a href="#page137">137.</a></li>
+
+<li class="martop04">Mayence tertiary strata, <a href="#page177">177.</a></li>
+
+<li class="martop04">Mediterranean and Red Sea, distinct species in, <a href="#page100">100.</a></li>
+  <li class="add2em">deposits forming in, <a href="#page99">99.</a></li>
+
+<li class="martop04">Megalichthys in Cannel coal of Fifeshire, <a href="#page336">336.</a></li>
+
+<li class="martop04">Megatherium in South America, <a href="#page158">158.</a></li>
+
+<li class="martop04">Menai Straits, marine shells in drift, <a href="#page130">130.</a></li>
+
+<li class="martop04">Mendips, denudation in, <a href="#page68">68.</a></li>
+
+<li class="martop04">Metalliferous veins. <i>See</i> <a href="#mineralv">Mineral Veins</a>.</li>
+
+<li class="martop04">Metals, supposed relative ages of, <a href="#page497">497.</a></li>
+
+<li class="martop04">Metamorphic rocks, <a href="#page463">463.</a></li>
+  <li class="add2em">defined, <a href="#page8">8.</a></li>
+  <li class="add2em">why less calcareous than fossiliferous, <a href="#page487">487.</a></li>
+  <li class="add2em">order of succession, <a href="#page485">485.</a></li>
+  <li class="add2em">glossary of, <a href="#page466">466.</a></li>
+
+<li class="martop04">Metamorphic strata, origin of, <a href="#page467">467.</a></li>
+
+<li class="martop04">Metamorphic structure, origin of, <a href="#page477">477.</a></li>
+
+<li class="martop04">Meteorites in drift, <a href="#page145">145.</a></li>
+
+<li class="martop04">Mexico, lamination of volcanic rocks in, <a href="#page480">480.</a></li>
+
+<li class="martop04">Meyer, M. H. von, cited, <a href="#page147">147.</a></li>
+  <li class="add2em">on fossil mammalia of Rhine, <a href="#page178">178.</a></li>
+  <li class="add2em">on reptile in coal, <a href="#page336">336.</a> <a href="#page337">337.</a></li>
+  <li class="add2em">on sandstone of Vosges, <a href="#page288">288.</a></li>
+  <li class="add2em">on Wealden of Hanover and Westphalia, <a href="#page237">237.</a></li>
+
+<li class="martop04">Mica schist, <a href="#page465">465.</a></li>
+
+<li class="martop04">Micaceous sandstone, origin of, <a href="#page14">14.</a></li>
+
+<li class="martop04">Microlestes antiquus, triassic mammifer, Postscr., <a href="#pagexiv">xiv.</a></li>
+
+<li class="martop04">Miller, Mr. H., on origin of rock salt, <a href="#page295">295.</a></li>
+  <li class="add2em">on old red sandstone, <a href="#page343">343.</a></li>
+  <li class="add2em">on fossil trees of coal near Edinburgh, <a href="#page321">321.</a></li>
+
+<li class="martop04">Minchinhampton, fossil shells at, <a href="#page266">266.</a></li>
+
+<li class="martop04">Mineral character of aqueous rocks, <a href="#page97">97.</a></li>
+  <li class="add2em">composition, test of age of volcanic rocks, <a href="#page399">399.</a></li>
+  <li class="add2em"><a id="mineralsp" name="mineralsp">springs</a>, connected with mineral veins, <a href="#page496">496.</a></li>
+  <li class="add2em">veins and faults, <a href="#page488">488.</a> <a href="#page490">490.</a></li>
+  <li class="add2em">of different ages, <a href="#page490">490.</a> <a href="#page498">498.</a> <a href="#page499">499.</a></li>
+  <li class="add2em"><a id="mineralv" name="mineralv">veins</a>, pebbles in, <a href="#page492">492.</a></li>
+  <li class="add2em">subsequently enlarged and re-opened, <a href="#page492">492.</a></li>
+  <li class="add2em">veins, various forms of, <a href="#page489">489.</a></li>
+  <li class="add2em">veins near granite, <a href="#page496">496.</a></li>
+
+<li class="martop04">Mineralization of organic remains, <a href="#page38">38.</a></li>
+
+<li class="martop04">Miocene formations, <a href="#page168">168.</a></li>
+  <li class="add2em">in United States, <a href="#page171">171.</a></li>
+  <li class="add2em">period, volcanic rocks of, <a href="#page415">415.</a></li>
+  <li class="add2em">term defined, <a href="#page111">111.</a></li>
+
+<li class="martop04">Mississippi, fluviatile strata and delta of, <a href="#page115">115.</a> <a href="#page116">116.</a></li>
+
+<li class="martop04">Mitchell, Sir T., on Australian caves, <a href="#page156">156.</a></li>
+
+<li class="martop04">Mitscherlich, Prof., on augite and hornblende, <a href="#page369">369.</a></li>
+  <li class="add2em">on isomorphism, <a href="#page370">370.</a></li>
+  <li class="add2em">on mineral composition of Somma, <a href="#page404">404.</a></li>
+
+<li class="martop04">Modon, lithodomi in cliff at, <a href="#page73">73.</a></li>
+
+<li class="martop04">Molasse of Switzerland, <a href="#page171">171.</a></li>
+
+<li class="martop04">Mons, flexures of coal at, <a href="#page53">53.</a></li>
+
+<li class="martop04">Mont Blanc, granite of, <a href="#page453">453.</a></li>
+
+<li class="martop04">Mont Dor, Auvergne, <a href="#page422">422.</a></li>
+
+<li class="martop04">Monte Calvo, section of, <a href="#page18">18.</a></li>
+
+<li class="martop04">Montlosier, M., on Auvergne volcanos, <a href="#page427">427.</a></li>
+
+<li class="martop04">Moraine, term explained, <a href="#page123">123.</a></li>
+
+<li class="martop04">Moraines of glaciers, <a href="#page141">141.</a></li>
+
+<li class="martop04">Morea, inland sea-cliffs of, <a href="#page73">73.</a></li>
+  <li class="add2em">trap of, <a href="#page431">431.</a></li>
+
+<li class="martop04">Morris, Mr., cited, <a href="#page177">177.</a></li>
+  <li class="add2em">on fossils at Brentford, <a href="#page147">147.</a></li>
+
+<li class="martop04"><span class="pagenum"><a id="page509"></a>[p.509]</span>Morton, Dr., on cretaceous rocks, <a href="#page224">224.</a></li>
+
+<li class="martop04">Morven, basaltic columns in, <a href="#page385">385.</a></li>
+
+<li class="martop04">Mosasaurus in St. Peter's Mount, <a href="#page210">210.</a></li>
+
+<li class="martop04">Mountain limestone, fossils of, <a href="#page340">340.</a></li>
+
+<li class="martop04">Munster, Count, on fossils of Solenhofen, <a href="#page260">260.</a></li>
+
+<li class="martop04">Murchison, Sir R., cited, <a href="#page248">248.</a> <a href="#page324">324.</a></li>
+  <li class="add2em">on new red sandstone, <a href="#page290">290.</a></li>
+  <li class="add2em">on age of Alps, <a href="#page206">206.</a></li>
+  <li class="add2em">on age of gold in Russia, <a href="#page499">499.</a></li>
+  <li class="add2em">on erratic blocks of Alps, <a href="#page144">144.</a></li>
+  <li class="add2em">on granite, <a href="#page456">456.</a> <a href="#page459">459.</a></li>
+  <li class="add2em">on primary strata in Russia, <a href="#page124">124.</a></li>
+  <li class="add2em">on joints and cleavage, <a href="#page469">469.</a> <a href="#page471">471.</a></li>
+  <li class="add2em">on old red sandstone of S. Devon, <a href="#page345">345.</a> <a href="#page348">348.</a></li>
+  <li class="add2em">on pentamerus, <a href="#page353">353.</a></li>
+  <li class="add2em">on Permian flora, <a href="#page305">305.</a></li>
+  <li class="add2em">on Silurian strata of Shropshire, <a href="#page434">434.</a></li>
+  <li class="add2em">on Swiss Alps, <a href="#page484">484.</a></li>
+  <li class="add2em">on term Permian, <a href="#page301">301.</a></li>
+  <li class="add2em">on term Silurian, <a href="#page350">350.</a></li>
+  <li class="add2em">on tilestones, <a href="#page351">351.</a></li>
+
+<li class="martop04">Muschelkalk, <a href="#page287">287.</a></li>
+</ul>
+
+
+<h3>N.</h3>
+<ul>
+<li class="martop04">Naples, post-pliocene formations near, <a href="#page403">403.</a></li>
+  <li class="add2em">recent strata near, <a href="#page112">112.</a></li>
+
+<li class="martop04">Navarino, lithodomi found in cliff at, <a href="#page73">73.</a></li>
+
+<li class="martop04">Necker, M. L. A., cited, <a href="#page445">445.</a></li>
+  <li class="add2em">on composition of cone of Somma, <a href="#page404">404.</a></li>
+  <li class="add2em">on granite in Arran, <a href="#page460">460.</a></li>
+  <li class="add2em">on granitic rocks, <a href="#page447">447.</a></li>
+  <li class="add2em">on Swiss Alps, <a href="#page484">484.</a></li>
+  <li class="add2em">terms granite underlying, <a href="#page8">8.</a></li>
+
+<li class="martop04">Nelson, Lieut., drawing of Bermuda, <a href="#page79">79.</a></li>
+  <li class="add2em">on Bermuda Island, <a href="#page216">216.</a></li>
+
+<li class="martop04">Neptunian theory, <a href="#page91">91.</a></li>
+
+<li class="martop04">Newcastle coal field, great faults in, <a href="#page64">64.</a></li>
+
+<li class="martop04">Newcastle, fossil tree near, <a href="#page312">312.</a> <a href="#page318">318.</a></li>
+
+<li class="martop04">New Jersey, <i>Mastodon giganteus</i> in, <a href="#page137">137.</a></li>
+
+<li class="martop04">New red sandstone, distinction from old, <a href="#page286">286.</a></li>
+  <li class="add2em">its subdivisions, <a href="#page287">287.</a></li>
+  <li class="add2em">of United States, <a href="#page297">297.</a></li>
+  <li class="add2em">trap of, <a href="#page432">432.</a></li>
+
+<li class="martop04">New Zealand, absence of quadrupeds, <a href="#page158">158.</a></li>
+
+<li class="martop04">Niagara, recent shells in valley of, <a href="#page138">138.</a></li>
+
+<li class="martop04">Noeggerath, M., cited, <a href="#page415">415.</a></li>
+
+<li class="martop04">Nomenclature, changes of, <a href="#page93">93.</a></li>
+
+<li class="martop04">Norfolk, buried forest, <a href="#page127">127.</a> <a href="#page130">130.</a> <a href="#page147">147.</a></li>
+  <li class="add2em">drift, <a href="#page126">126.</a></li>
+
+<li class="martop04">Normandy chalk, cliffs, and needles, <a href="#page241">241.</a></li>
+
+<li class="martop04">Northwich, beds of salt at, <a href="#page294">294.</a></li>
+
+<li class="martop04">Norwich crag, fluvio-marine, <a href="#page148">148.</a></li>
+  <li class="add2em">sand-pipes near, <a href="#page82">82.</a></li>
+
+<li class="martop04">Nova Scotia, coal seams of Cape Breton, <a href="#page315">315.</a></li>
+  <li class="add2em">fossil forest of coal in, <a href="#page321">321.</a></li>
+
+<li class="martop04">Nummulites, figures of, <a href="#page200">200.</a> <a href="#page205">205.</a></li>
+
+<li class="martop04">Nummulitic formation, <a href="#page205">205.</a></li>
+
+<li class="martop04">Nyst, M., cited, <a href="#page176">176.</a></li>
+</ul>
+
+
+<h3>O.</h3>
+<ul>
+<li class="martop04">Oeynhausen, M. von, on Cornish granite veins, <a href="#page445">445.</a></li>
+
+<li class="martop04">Olot, extinct volcanos near, <a href="#page408">408.</a></li>
+
+<li class="martop04">Old red sandstone, <a href="#page342">342.</a></li>
+  <li class="add2em">in Forfarshire, <a href="#page478">478.</a></li>
+  <li class="add2em">trap of, <a href="#page434">434.</a></li>
+
+<li class="martop04">Oolite, <a href="#page257">257.</a></li>
+  <li class="add2em">and lias, origin of, <a href="#page282">282.</a></li>
+  <li class="add2em">inferior, fossils of, <a href="#page272">272.</a></li>
+  <li class="add2em">in France, <a href="#page259">259.</a></li>
+  <li class="add2em">plutonic rocks of, <a href="#page455">455.</a></li>
+  <li class="add2em">term defined, <a href="#page12">12.</a></li>
+  <li class="add2em">volcanic rocks of, <a href="#page431">431.</a></li>
+
+<li class="martop04">Oolitic group in France, <a href="#page283">283.</a></li>
+
+<li class="martop04">Orbigny, M. d', cited, <a href="#page222">222.</a></li>
+  <li class="add2em">on fossils of nummulitic limestone, <a href="#page206">206.</a></li>
+  <li class="add2em">on subdivisions of cretaceous series, <a href="#page209">209.</a></li>
+
+<li class="martop04">Organic remains, criterion of age of formation, <a href="#page98">98.</a></li>
+  <li class="add2em">test of age of volcanic rocks, <a href="#page399">399.</a></li>
+
+<li class="martop04">Ormerod, Mr., on trias of Cheshire, <a href="#page295">295.</a></li>
+
+<li class="martop04">Overlying, term applied to volcanic rocks, <a href="#page8">8.</a></li>
+
+<li class="martop04">Owen, Prof., cited, <a href="#page155">155.</a> <a href="#page166">166.</a> <a href="#page229">229.</a> <a href="#page267">267.</a> <a href="#page268">268.</a> <a href="#page270">270.</a> <a href="#page291">291.</a></li>
+  <li class="add2em">on amphitherium, <a href="#page269">269.</a></li>
+  <li class="add2em">on birds in New Zealand, <a href="#page158">158.</a></li>
+  <li class="add2em">on caves in England, <a href="#page154">154.</a></li>
+  <li class="add2em">on footprints, <a href="#page298">298.</a></li>
+  <li class="add2em">on fossils in Australia, <a href="#page156">156.</a></li>
+  <li class="add2em">on fossil monkey, <a href="#page202">202.</a></li>
+  <li class="add2em">on fossil quadrupeds, <a href="#page157">157.</a></li>
+  <li class="add2em">on ichthyosaurus, <a href="#page276">276.</a></li>
+  <li class="add2em">on reptile in coal, <a href="#page337">337.</a></li>
+  <li class="add2em">on serpent of Bracklesham, <a href="#page199">199.</a></li>
+  <li class="add2em">on snake at Sheppey, <a href="#page201">201.</a></li>
+  <li class="add2em">on thecodont saurians, <a href="#page306">306.</a></li>
+  <li class="add2em">on zeuglodon, <a href="#page207">207.</a> <a href="#page208">208.</a></li>
+  <li class="add2em">on reptile in Silurian rocks, Postscript, <a href="#pageviii">viii.</a></li>
+
+<li class="martop04">Oxford clay, <a href="#page262">262.</a></li>
+
+<li class="martop04">Oyster beds, <a href="#page204">204.</a></li>
+</ul>
+
+
+<h3>P.</h3>
+<ul>
+<li class="martop04">Pacific, coral reefs of, <a href="#page215">215.</a></li>
+
+<li class="martop04">Pal�ontology, term explained, <a href="#page103">103.</a></li>
+
+<li class="martop04">Palagonia, dikes at, <a href="#page407">407.</a></li>
+
+<li class="martop04"><i>Paleotherium magnum</i>, figure of, <a href="#page192">192.</a></li>
+  <li class="add2em">tooth of, <a href="#page193">193.</a></li>
+
+<li class="martop04">Palermo, caves near, <a href="#page74">74.</a></li>
+
+<li class="martop04">Palma, Isle of, map and view of, <a href="#page391">391.</a></li>
+
+<li class="martop04">Parallel roads, <a href="#page86">86.</a></li>
+
+<li class="martop04">Pareto, M., on Carrara marble, <a href="#page482">482.</a></li>
+
+<li class="martop04">Paris basin, <a href="#page93">93.</a></li>
+
+<li class="martop04">Parkinson, Mr., on crag, <a href="#page105">105.</a></li>
+
+<li class="martop04">Parrot, Dr. F., on salt lakes of Asia, <a href="#page295">295.</a></li>
+
+<li class="martop04">Pebbles in chalk, <a href="#page217">217.</a></li>
+
+<li class="martop04">Pegmatite, <a href="#page440">440.</a></li>
+
+<li class="martop04"><i>Pentamerus Knightii</i>, <a href="#page352">352.</a></li>
+
+<li class="martop04">Pentland hills, Mr. Maclaren on, <a href="#page125">125.</a></li>
+
+<li class="martop04">Pepys, Mr., cited, <a href="#page41">41.</a></li>
+
+<li class="martop04">Permian flora, distinct from coal, <a href="#page305">305.</a></li>
+  <li class="add2em">formation in Thuringia, <a href="#page306">306.</a></li>
+  <li class="add2em">group, term explained, <a href="#page301">301.</a></li>
+
+<li class="martop04">Petrifaction of fossil wood, <a href="#page39">39.</a></li>
+
+<li class="martop04">Petrifaction, process of, <a href="#page43">43.</a></li>
+
+<li class="martop04">Philippi, Dr., on fossil shells near Naples, <a href="#page113">113.</a></li>
+  <li class="add2em">on marine shells in caves of Sicily, <a href="#page154">154.</a></li>
+  <li class="add2em">on tertiary shells of Sicily, <a href="#page150">150.</a></li>
+
+<li class="martop04">Phillips, Prof., cited, <a href="#page274">274.</a> <a href="#page309">309.</a></li>
+  <li class="add2em">on cleavage, <a href="#page471">471.</a></li>
+  <li class="add2em">on terminology, <a href="#page103">103.</a></li>
+
+<li class="martop04">Phillips, Mr. W., on kaolin of China, <a href="#page11">11.</a></li>
+
+<li class="martop04">Phosphate of lime, <a href="#page219">219.</a></li>
+
+<li class="martop04">Phryganea, figure of, <a href="#page185">185.</a></li>
+  <li class="add2em">indusi� of, <a href="#page186">186.</a></li>
+
+<li class="martop04">Pictou, Nova Scotia, calamites near, <a href="#page319">319.</a></li>
+
+<li class="martop04">Pilla, M., on age of Carrara marble, <a href="#page482">482.</a></li>
+
+<li class="martop04">Planitz, tripoli of, <a href="#page26">26.</a></li>
+
+<li class="martop04">Plas Newydd, rock altered by dike near, <a href="#page381">381.</a></li>
+
+<li class="martop04">Plastic clays, <a href="#page203">203.</a></li>
+
+<li class="martop04">Playfair, cited, <a href="#page45">45.</a> <a href="#page92">92.</a> <a href="#page383">383.</a></li>
+  <li class="add2em">on faults, <a href="#page62">62.</a></li>
+  <li class="add2em">on Huttonian theory of stratification, <a href="#page60">60.</a></li>
+
+<li class="martop04">Plesiosaurus, figure of, <a href="#page277">277.</a></li>
+
+<li class="martop04">Plieninger, Professor, on triassic mammifer, Postscript, <a href="#pagexiii">xiii.</a></li>
+
+<li class="martop04">Pliocene, newer period, <a href="#page121">121.</a></li>
+  <li class="add2em">newer, strata, <a href="#page146">146.</a></li>
+  <li class="add2em">strata in Sicily, <a href="#page150">150.</a></li>
+  <li class="add2em">older, in United States, <a href="#page171">171.</a></li>
+  <li class="add2em">strata, <a href="#page161">161.</a></li>
+  <li class="add2em">period, volcanic rocks of, <a href="#page407">407.</a> <a href="#page408">408.</a></li>
+<li class="add2em"><span class="pagenum"><a id="page510"></a>[p.510]</span>term defined, <a href="#page111">111.</a></li>
+
+<li class="martop04">Plomb du Cantal, described, <a href="#page429">429.</a></li>
+
+<li class="martop04">Plumbago in Massachusetts, <a href="#page478">478.</a></li>
+
+<li class="martop04">Plutonic rocks, <a href="#page7">7.</a> <a href="#page446">446.</a></li>
+  <li class="add2em">age of, <a href="#page439">439.</a></li>
+  <li class="add2em">of carboniferous period, <a href="#page456">456.</a></li>
+  <li class="add2em">of oolite and lias, <a href="#page455">455.</a></li>
+  <li class="add2em">recent and pliocene, <a href="#page450">450.</a></li>
+  <li class="add2em">of Silurian period, <a href="#page457">457.</a></li>
+  <li class="add2em">age, how tested, <a href="#page449">449.</a></li>
+
+<li class="martop04">Plutonic and sedimentary rocks, diagram of, <a href="#page451">452.</a></li>
+
+<li class="martop04">Poggendorf, cited, <a href="#page476">476.</a></li>
+
+<li class="martop04">Poikilitic formation, <a href="#page301">301.</a></li>
+  <li class="add2em">term explained, <a href="#page286">286.</a></li>
+
+<li class="martop04">Pomel, M., on mammalia of Auvergne, <a href="#page188">188.</a> <a href="#page425">425.</a></li>
+
+<li class="martop04">Ponza Islands, structure of, <a href="#page387">387.</a> <a href="#page480">480.</a></li>
+
+<li class="martop04">Porphyritic granite, <a href="#page439">439.</a></li>
+
+<li class="martop04">Porphyry, <a href="#page372">372.</a></li>
+
+<li class="martop04">Portland, Isle of, fossil forest in, <a href="#page233">233.</a></li>
+
+<li class="martop04">Portland stone, <a href="#page259">259.</a></li>
+
+<li class="martop04">Post-pliocene formations, <a href="#page111">111.</a></li>
+  <li class="add2em">period, volcanic rocks, <a href="#page401">401.</a></li>
+
+<li class="martop04">Potsdam sandstone, reptilian, Postscript, <a href="#pagevii">vii.</a> <a href="#pagexviii">xviii.</a></li>
+
+<li class="martop04">Pottsville, coal seams near, <a href="#page329">329.</a></li>
+  <li class="add2em">footprints of reptile near, <a href="#page340">340.</a></li>
+
+<li class="martop04">Pozzolana, <a href="#page36">36.</a></li>
+
+<li class="martop04">Pratt, Mr., on ammonites, <a href="#page262">262.</a></li>
+  <li class="add2em">on extinct quadrupeds of Isle of Wight, <a href="#page198">198.</a></li>
+
+<li class="martop04">Predazzo, altered rocks at, <a href="#page456">456.</a></li>
+
+<li class="martop04">Prestwich, Mr., cited, <a href="#page69">69.</a></li>
+  <li class="add2em">on English Eocene strata, <a href="#page197">197.</a> <a href="#page198">198.</a> <a href="#page200">200.</a></li>
+  <li class="add2em">on coal measures of Coalbrook Dale, <a href="#page62">62.</a> <a href="#page324">324.</a></li>
+
+<li class="martop04">Prevost, M. C., on Paris basin, <a href="#page175">175.</a> <a href="#page176">176.</a> <a href="#page195">195.</a></li>
+
+<li class="martop04">Progressive development, theory of, Postscript, <a href="#pagexvi">xvi.</a></li>
+
+<li class="martop04">Psaronites in Germany and France, <a href="#page307">307.</a></li>
+
+<li class="martop04">Pumice, <a href="#page373">373.</a></li>
+
+<li class="martop04">Purbeck beds, <a href="#page231">231.</a></li>
+
+<li class="martop04">Puy de Tartaret, <a href="#page425">425.</a></li>
+
+<li class="martop04">Puy de Pariou, <a href="#page428">428.</a></li>
+
+<li class="martop04">Puzzuoli, elevation and depression of land at, <a href="#page403">403.</a></li>
+
+<li class="martop04">Pyrenees, cretaceous rocks of, <a href="#page455">455.</a></li>
+  <li class="add2em">curvatures of strata, <a href="#page58">58.</a></li>
+  <li class="add2em">granite of, <a href="#page475">475.</a></li>
+  <li class="add2em">nummulitic formation of, <a href="#page205">205.</a></li>
+</ul>
+
+
+<h3>Q.</h3>
+<ul>
+<li class="martop04">Quadrumana fossil, Postscript, <a href="#pagexvii">xvii.</a></li>
+
+<li class="martop04">Quarrington Hill, basaltic dike near, <a href="#page398">398.</a></li>
+
+<li class="martop04">Quartz, <a href="#page438">438.</a></li>
+
+<li class="martop04">Quartzite, or quartz rock, <a href="#page465">465.</a></li>
+</ul>
+
+
+<h3>R.</h3>
+<ul>
+<li class="martop04">Radnorshire, stratified trap of, <a href="#page425">425.</a></li>
+
+<li class="martop04">Rain-prints, fossil in coal shale, Postscript, <a href="#pagexii">xii.</a></li>
+
+<li class="martop04">Ramsay, Prof. A. C., on denudation, <a href="#page68">68.</a></li>
+  <li class="add2em">on granite in Arran, <a href="#page460">460.</a></li>
+  <li class="add2em">on section near Bristol, <a href="#page102">102.</a></li>
+  <li class="add2em">on Welsh glaciers, <a href="#page131">131.</a></li>
+
+<li class="martop04">Recent strata defined, <a href="#page112">112.</a></li>
+  <li class="add2em">near Naples, <a href="#page112">112.</a></li>
+
+<li class="martop04">Redfield, Mr., on glacial fauna in America, <a href="#page133">133.</a></li>
+  <li class="add2em">on fossil fish, <a href="#page300">300.</a></li>
+
+<li class="martop04">Red sandstone, origin of, <a href="#page293">293.</a></li>
+
+<li class="martop04">Red Sea and Mediterranean, distinct species in, <a href="#page100">100.</a></li>
+
+<li class="martop04">Red Sea, saltness of, <a href="#page296">296.</a></li>
+
+<li class="martop04">Reptiles, carboniferous, <a href="#page335">335.</a> <a href="#page336">336.</a></li>
+  <li class="add2em">of lias, <a href="#page276">276.</a></li>
+  <li class="add2em">fossil eggs of, <a href="#page120">120.</a></li>
+
+<li class="martop04">Reptile, in Lower Silurian, Postscript, <a href="#pagevii">vii.</a></li>
+  <li class="add2em">in Old Red Sandstone of Morayshire, Postscript, <a href="#pageix">ix.</a></li>
+
+<li class="martop04">Rhine, valley, loess of, <a href="#page117">117.</a></li>
+
+<li class="martop04">Ripple-mark, formation of, <a href="#page19">19.</a></li>
+
+<li class="martop04">River channels, ancient, <a href="#page334">334.</a></li>
+
+<li class="martop04">River, excavation through lava by, <a href="#page413">413.</a></li>
+  <li class="add2em">terraces, <a href="#page85">85.</a></li>
+
+<li class="martop04">Rock, term defined, <a href="#page2">2.</a></li>
+
+<li class="martop04">Rocks, four classes of, contemporaneous, <a href="#page9">9.</a></li>
+  <li class="add2em">classification of, <a href="#page90">90.</a></li>
+  <li class="add2em">composed of fossil zoophytes and shells, <a href="#page24">24.</a></li>
+  <li class="add2em">trappean, <a href="#page91">91.</a></li>
+
+<li class="martop04">Roderberg, extinct volcano of, <a href="#page420">420.</a></li>
+
+<li class="martop04">Rogers, Prof. H. D., on coal field, United States, <a href="#page328">328.</a></li>
+  <li class="add2em">cited, <a href="#page340">340.</a></li>
+  <li class="add2em">on reptilian footprints in coal, Postscript, <a href="#pagexi">xi.</a></li>
+
+<li class="martop04">Rogers, Prof. W. B., on oolitic coal field, United States, <a href="#page284">284.</a> <a href="#page328">328.</a></li>
+
+<li class="martop04">Rome, formations at, <a href="#page168">168.</a></li>
+
+<li class="martop04">R�mer, F., on chalk in Texas, <a href="#page225">225.</a></li>
+  <li class="add2em">M. F. A., on flora of Hartz, <a href="#page350">350.</a></li>
+
+<li class="martop04">Rose, Prof. G., cited, <a href="#page374">374.</a> <a href="#page434">434.</a></li>
+  <li class="add2em">on hornblende, <a href="#page369">369.</a></li>
+
+<li class="martop04">Rosenlaui, limestone scratched by glacier of, <a href="#page122">122.</a></li>
+
+<li class="martop04">Ross, Captain, on greenstone in Keeling Island, <a href="#page217">217.</a></li>
+
+<li class="martop04">Ross-shire, denudation in, <a href="#page67">67.</a></li>
+
+<li class="martop04">Rothliegendes, lower, or Permian, <a href="#page306">306.</a></li>
+
+<li class="martop04">Rozet, M., cited, <a href="#page191">191.</a></li>
+
+<li class="martop04">Rubble, term explained, <a href="#page81">81.</a></li>
+
+<li class="martop04">Russia, erratic blocks in, <a href="#page124">124.</a></li>
+  <li class="add2em">fossil meteoric iron in, <a href="#page145">145.</a></li>
+  <li class="add2em">Permian rocks in, <a href="#page306">306.</a></li>
+</ul>
+
+
+<h3>S.</h3>
+<ul>
+<li class="martop04">Saarbr�ck coal field, reptile found in, <a href="#page336">336.</a></li>
+
+<li class="martop04">St. Abb's Head, curved strata near, <a href="#page49">49.</a></li>
+
+<li class="martop04">St. Andrews, trap rocks in cliffs near, <a href="#page432">432.</a> <a href="#page433">433.</a></li>
+
+<li class="martop04">St. Helena, basalt in, <a href="#page385">385.</a> <a href="#page406">406.</a></li>
+
+<li class="martop04">St. Lawrence, gulf of, inland beaches and cliffs, <a href="#page78">78.</a></li>
+
+<li class="martop04">St. Mihiel, inland cliffs near, <a href="#page77">77.</a></li>
+
+<li class="martop04">St. Paul, island of, <a href="#page394">394.</a></li>
+
+<li class="martop04">St. Peter's Mount, Maestricht, fossils in, <a href="#page210">210.</a></li>
+  <li class="add2em">sand-pipes in, <a href="#page83">83.</a></li>
+
+<li class="martop04">Salisbury Crag, altered strata of, <a href="#page383">383.</a></li>
+
+<li class="martop04">Salt rock, origin of, <a href="#page294">294.</a></li>
+  <li class="add2em">precipitation of, <a href="#page294">294.</a></li>
+  <li class="add2em">at Northwich, <a href="#page294">294.</a></li>
+  <li class="add2em">lakes of Asia, <a href="#page296">296.</a></li>
+
+<li class="martop04">Salter, Mr., on fossil of Caradoc sandstone, <a href="#page356">356.</a></li>
+
+<li class="martop04">Sand-pipes near Maestricht, <a href="#page83">83.</a></li>
+  <li class="add2em">or sand-galls, term explained, <a href="#page82">82.</a></li>
+  <li class="add2em">near Norwich, <a href="#page82">82.</a></li>
+
+<li class="martop04">Sandstone, siliceous, <a href="#page218">218.</a></li>
+  <li class="add2em">with cracks in Wealden, <a href="#page230">230.</a></li>
+
+<li class="martop04">Sandwich Islands, coral reef in, <a href="#page216">216.</a></li>
+  <li class="add2em">volcanos of, <a href="#page394">394.</a> <a href="#page406">406.</a> <a href="#page423">423.</a></li>
+
+<li class="martop04">Saurians of lias, <a href="#page278">278.</a></li>
+  <li class="add2em">thecodont, <a href="#page306">306.</a></li>
+
+<li class="martop04">Saussure, M., on moraines, <a href="#page141">141.</a></li>
+  <li class="add2em">on vertical conglomerates, <a href="#page47">47.</a></li>
+
+<li class="martop04">Savi, M., on Carrara marble, <a href="#page482">482.</a></li>
+
+<li class="martop04">Saxony, granite in, <a href="#page459">459.</a></li>
+
+<li class="martop04">Schist, hornblende, and mica, <a href="#page464">464.</a> <a href="#page465">465.</a></li>
+  <li class="add2em">argillaceous, <a href="#page465">465.</a></li>
+  <li class="add2em">chlorite, <a href="#page465">465.</a></li>
+
+<li class="martop04">Schorl rock and schorly granite, <a href="#page440">440.</a></li>
+
+<li class="martop04">Scoresby on icebergs, <a href="#page122">122.</a></li>
+
+<li class="martop04">Scori�, <a href="#page373">373.</a></li>
+
+<li class="martop04">Scotland, carboniferous traps of, <a href="#page432">432.</a></li>
+  <li class="add2em">northern drift in, <a href="#page125">125.</a></li>
+  <li class="add2em">old red sandstone of, <a href="#page343">343.</a></li>
+
+<li class="martop04">Scrope, Mr., cited, <a href="#page181">181.</a> <a href="#page263">263.</a> <a href="#page419">419.</a> <a href="#page423">423.</a> <a href="#page425">425.</a> <a href="#page427">427.</a> <a href="#page430">430.</a></li>
+  <li class="add2em">on globular structure of traps, <a href="#page287">387.</a></li>
+  <li class="add2em">on Ponza Islands, <a href="#page480">480.</a></li>
+  <li class="add2em">on trachyte, basalt, and tuff, <a href="#page374">374.</a> <a href="#page400">400.</a></li>
+
+<li class="martop04">Sea cliffs, inland, <a href="#page71">71.</a></li>
+
+<li class="martop04">Section of Wealden, <a href="#page243">243.</a></li>
+
+<li class="martop04">Section of white chalk from England to France, <a href="#page211">211.</a></li>
+
+<li class="martop04">Section of volcanic rocks, Auvergne, <a href="#page424">424.</a></li>
+
+<li class="martop04">Sedgwick, Prof., cited, <a href="#page309">309.</a> <a href="#page383">383.</a></li>
+<li class="add2em"><span class="pagenum"><a id="page511"></a>[p.511]</span>on brecciated limestone, <a href="#page302">302.</a></li>
+  <li class="add2em">on concretionary magnesian limestone, <a href="#page37">37.</a></li>
+  <li class="add2em">on Devonian group, <a href="#page348">348.</a></li>
+  <li class="add2em">on garnets in altered rock, <a href="#page382">382.</a></li>
+  <li class="add2em">on granite, <a href="#page456">456.</a> <a href="#page459">459.</a></li>
+  <li class="add2em">on Permian sandstones, <a href="#page305">305.</a></li>
+  <li class="add2em">on joints and cleavage, <a href="#page469">469.</a> <a href="#page471">471.</a></li>
+  <li class="add2em">on mineral composition of granite, <a href="#page444">444.</a></li>
+  <li class="add2em">on old red of Devon and Cornwall, <a href="#page345">345.</a></li>
+  <li class="add2em">on structure of rocks, <a href="#page468">468.</a></li>
+  <li class="add2em">on trap rocks of Cumberland, <a href="#page435">435.</a></li>
+
+<li class="martop04">Segregation in mineral veins, <a href="#page489">489.</a></li>
+
+<li class="martop04">Semi-opal, infusoria in, <a href="#page26">26.</a></li>
+
+<li class="martop04">Serpul�, on volcanic rocks, in Sicily, <a href="#page151">151.</a></li>
+
+<li class="martop04">Sew�lik Hills, freshwater deposits, <a href="#page173">173.</a></li>
+
+<li class="martop04">Shale, carbonaceous, <a href="#page271">271.</a></li>
+  <li class="add2em">defined, <a href="#page11">11.</a></li>
+
+<li class="martop04">Shales of coal near Dudley, <a href="#page474">474.</a></li>
+
+<li class="martop04">Sharpe, Mr. D., on mollusca in Silurian strata, <a href="#page359">359.</a></li>
+  <li class="add2em">on slaty cleavage, <a href="#page471">471.</a></li>
+
+<li class="martop04">Shells, fossil, in Purbeck, <a href="#page231">231.</a></li>
+  <li class="add2em">fossil, useful in classification, <a href="#page109">109.</a></li>
+  <li class="add2em">in Canada drift, <a href="#page134">134.</a></li>
+  <li class="add2em">recent, in valley of Niagara, <a href="#page138">138.</a></li>
+  <li class="add2em">species of, near Lisbon, <a href="#page171">171.</a></li>
+
+<li class="martop04">Sheppey, Isle of, fossil flora of, <a href="#page200">200.</a></li>
+
+<li class="martop04">Sherringham, mass of chalk in drift, <a href="#page129">129.</a></li>
+
+<li class="martop04">Shetland, granite of, <a href="#page441">441.</a> <a href="#page444">444.</a></li>
+  <li class="add2em">hornblende schist of, <a href="#page478">478.</a></li>
+
+<li class="martop04">Shrewsbury, coal deposit near, <a href="#page324">324.</a></li>
+
+<li class="martop04">Sicily, Fiume Salso in, <a href="#page191">191.</a></li>
+  <li class="add2em">inland cliffs in, <a href="#page74">74.</a></li>
+  <li class="add2em">newer pliocene strata of, <a href="#page150">150.</a></li>
+  <li class="add2em">terraces of denudation in, <a href="#page75">75.</a></li>
+
+<li class="martop04">Sidlaw Hills, trap of old red sandstone, <a href="#page434">434.</a></li>
+
+<li class="martop04">Siebengebirge, igneous rocks of, <a href="#page417">417.</a></li>
+
+<li class="martop04">Sienna, formations at, <a href="#page167">167.</a></li>
+
+<li class="martop04">Sigillaria, <a href="#page314">314.</a> <a href="#page318">318.</a></li>
+
+<li class="martop04">Siliceous limestone defined, <a href="#page12">12.</a></li>
+  <li class="add2em">rocks defined, <a href="#page11">11.</a></li>
+
+<li class="martop04">Silliman, Prof., cited, <a href="#page450">450.</a></li>
+
+<li class="martop04">Silurian, name explained, <a href="#page350">350.</a></li>
+  <li class="add2em">period, plutonic rocks of, <a href="#page457">457.</a></li>
+  <li class="add2em">rocks, table of, <a href="#page351">351.</a></li>
+  <li class="add2em">strata, mineral character of, <a href="#page360">360.</a></li>
+  <li class="add2em">strata of United States, <a href="#page359">359.</a></li>
+  <li class="add2em">strata, thickness of, <a href="#page358">358.</a></li>
+  <li class="add2em">strata, reptile in, Postscript, <a href="#pagevii">vii.</a></li>
+  <li class="add2em">volcanic rocks, <a href="#page434">434.</a></li>
+
+<li class="martop04">Simpson, Mr., on ice islands, <a href="#page129">129.</a></li>
+
+<li class="martop04">Sivatherium described, <a href="#page173">173.</a></li>
+
+<li class="martop04">Skaptar Jokul, eruption of, <a href="#page399">399.</a></li>
+
+<li class="martop04">Skye, rocks of, <a href="#page383">383.</a> <a href="#page456">456.</a></li>
+  <li class="add2em">basaltic columns in, <a href="#page385">385.</a></li>
+  <li class="add2em">dikes in Isle of, <a href="#page380">380.</a></li>
+  <li class="add2em">sandstone in, <a href="#page36">36.</a></li>
+
+<li class="martop04">Slaty cleavage, <a href="#page468">468.</a></li>
+
+<li class="martop04">Slickensides, term defined, <a href="#page61">61.</a></li>
+
+<li class="martop04">Smith, Mr., of Jordan Hill, on Pleistocene, <a href="#page134">134.</a></li>
+  <li class="add2em">on shells near Lisbon, <a href="#page171">171.</a></li>
+
+<li class="martop04">Snags, fossil, <a href="#page320">320.</a></li>
+
+<li class="martop04">Snakes' eggs, fossil at Tonna near Gotha, <a href="#page120">120.</a></li>
+
+<li class="martop04">Solenhofen, lithographic stone of, <a href="#page260">260.</a></li>
+
+<li class="martop04">Solfatara, decomposition of rocks in the, <a href="#page477">477.</a></li>
+
+<li class="martop04">Somma, <a href="#page404">404.</a></li>
+  <li class="add2em">lava at, <a href="#page380">380.</a></li>
+
+<li class="martop04">Sopwith, Mr. T., models by, <a href="#page57">57.</a></li>
+
+<li class="martop04">Sortino, cave in valley of, <a href="#page154">154.</a></li>
+
+<li class="martop04">South Devon and Cornwall, old red of, <a href="#page315">315.</a></li>
+
+<li class="martop04">South Downs, view of, <a href="#page245">245.</a></li>
+
+<li class="martop04">Sowerby, Mr. G., cited, <a href="#page162">162.</a></li>
+
+<li class="martop04">Spatangus, figure of, <a href="#page23">23.</a></li>
+
+<li class="martop04">Spezia, gulf of, calcareous rocks in, <a href="#page482">482.</a></li>
+
+<li class="martop04">Spitzbergen, glaciers of, <a href="#page136">136.</a></li>
+
+<li class="martop04">Sponges, figures of, in chalk, <a href="#page213">213.</a></li>
+
+<li class="martop04">Spongilla of Lamarck, in tripoli, <a href="#page25">25.</a></li>
+
+<li class="martop04">Springs, mineral. See <a href="#mineralsp">Mineral Springs</a>, <a href="#page490">490.</a></li>
+
+<li class="martop04">Staffa, basaltic columns in, <a href="#page385">385.</a></li>
+
+<li class="martop04">Steno on classification of rocks, <a href="#page90">90.</a></li>
+
+<li class="martop04">Stigmaria, <a href="#page310">310.</a> <a href="#page315">315.</a></li>
+  <li class="add2em">in fossil forest, Nova Scotia, <a href="#page322">322.</a></li>
+
+<li class="martop04">Stirling Castle, rock of, altered by dike, <a href="#page383">383.</a></li>
+
+<li class="martop04">Stokes, Mr., on petrifaction, <a href="#page43">43.</a></li>
+
+<li class="martop04">Stonesfield slate, <a href="#page266">266.</a></li>
+
+<li class="martop04">Stonesfield, fossil mammalia, <a href="#page268">268.</a> and Postscript, <a href="#pagexviii">xviii.</a></li>
+
+<li class="martop04">Storton Hill, footprints at, <a href="#page291">291.</a></li>
+
+<li class="martop04">Strata, term defined, <a href="#page2">2.</a></li>
+  <li class="add2em">arrangement of, determined by fossils, <a href="#page21">21.</a> <a href="#page22">22.</a></li>
+  <li class="add2em">consolidation of, <a href="#page34">34.</a></li>
+  <li class="add2em">curved and vertical, <a href="#page47">47.</a> <a href="#page58">58.</a></li>
+  <li class="add2em">elevation of, above the sea, <a href="#page44">44.</a></li>
+  <li class="add2em">fossiliferous, tabular view of, <a href="#page361">361.</a></li>
+  <li class="add2em">horizontality of, <a href="#page15">15.</a> <a href="#page45">45.</a></li>
+  <li class="add2em">metamorphic origin of, <a href="#page467">467.</a></li>
+  <li class="add2em">mineral composition of, <a href="#page10">10.</a></li>
+  <li class="add2em">outcrop of, <a href="#page56">56.</a></li>
+  <li class="add2em">tertiary classification of, <a href="#page134">134.</a></li>
+
+<li class="martop04">Stratification, forms of, <a href="#page13">13.</a> <a href="#page16">16.</a> <a href="#page47">47.</a></li>
+  <li class="add2em">unconformable, <a href="#page59">59.</a></li>
+
+<li class="martop04">Strickland, Mr., on new red sandstone, <a href="#page290">290.</a></li>
+
+<li class="martop04">Strike, term explained, <a href="#page53">53.</a></li>
+
+<li class="martop04">Stromboli, lava of, <a href="#page450">450.</a></li>
+
+<li class="martop04">Studer, M., on Swiss Alps, <a href="#page484">484.</a></li>
+  <li class="add2em">on boulders of Jura, <a href="#page143">143.</a></li>
+
+<li class="martop04">Stutchbury, Mr., cited, <a href="#page306">306.</a></li>
+
+<li class="martop04">Subapennine strata, <a href="#page105">105.</a> <a href="#page166">166.</a></li>
+
+<li class="martop04">Subsidence in drift period, <a href="#page135">135.</a></li>
+
+<li class="martop04">Suffolk crag, <a href="#page162">162.</a></li>
+
+<li class="martop04">Sullivan, Capt., chart of Falkland Islands, <a href="#page88">88.</a></li>
+
+<li class="martop04">Superior, Lake, marl in, <a href="#page36">36.</a></li>
+
+<li class="martop04">Superposition of aqueous deposits, <a href="#page96">96.</a></li>
+  <li class="add2em">of volcanic rocks, test of age, <a href="#page328">327.</a></li>
+
+<li class="martop04">Supracretaceous, term explained, <a href="#page103">103.</a></li>
+
+<li class="martop04">Sussex marble, <a href="#page228">228.</a></li>
+
+<li class="martop04">Swansea, coal measures near, <a href="#page309">309.</a></li>
+  <li class="add2em">valley stems of <i>Sigillaria</i>, <a href="#page317">317.</a></li>
+
+<li class="martop04">Sydney coal field, Cape Breton, <a href="#page324">324.</a></li>
+
+<li class="martop04">Syenite, <a href="#page440">440.</a></li>
+
+<li class="martop04">Syenitic granite, <a href="#page440">440.</a></li>
+  <li class="add2em">greenstone, <a href="#page372">372.</a></li>
+
+<li class="martop04">Synclinal line, term defined, <a href="#page48">48.</a></li>
+</ul>
+
+
+<h3>T.</h3>
+<ul>
+<li class="martop04">Table Mountain, strata horizontal, <a href="#page45">45.</a></li>
+  <li class="add2em">Mountain, granite veins in, <a href="#page443">443.</a></li>
+
+<li class="martop04">Talcose granite, <a href="#page440">440.</a></li>
+
+<li class="martop04">Tartaret, Puy de, cone of, <a href="#page425">425.</a></li>
+
+<li class="martop04">Teeth of fossil mammalia, figures of, <a href="#page160">160.</a></li>
+
+<li class="martop04">Teredina, fossil wood bored by, <a href="#page24">24.</a></li>
+
+<li class="martop04">Teredo navalis boring wood, <a href="#page23">23.</a></li>
+
+<li class="martop04">Terra del Fuego, <a href="#page139">139.</a></li>
+  <li class="add2em"><i>Fucus giganteus</i> in, <a href="#page217">217.</a></li>
+
+<li class="martop04">Tertiary, term explained, <a href="#page104">104.</a></li>
+  <li class="add2em">strata, tabular view of, <a href="#page362">362.</a></li>
+
+<li class="martop04">Touraine, faluns of, <a href="#page168">168.</a></li>
+
+<li class="martop04">Trachyte, <a href="#page372">372.</a></li>
+  <li class="add2em">of Hungary, <a href="#page442">442.</a></li>
+
+<li class="martop04">Trachytic rocks, older than basalt, <a href="#page400">400.</a></li>
+
+<li class="martop04">Transition, term explained, <a href="#page92">92.</a></li>
+
+<li class="martop04">Trap, term explained, <a href="#page366">366.</a></li>
+  <li class="add2em">dike in Fifeshire, <a href="#page434">434.</a></li>
+  <li class="add2em">globular structure of, <a href="#page387">387.</a></li>
+  <li class="add2em">intrusion of, between strata, <a href="#page384">384.</a></li>
+  <li class="add2em">various ages of, <a href="#page432">432.</a> <a href="#page434">434.</a></li>
+  <li class="add2em">passage of granite into, <a href="#page441">441.</a></li>
+  <li class="add2em">in Radnorshire, <a href="#page435">435.</a></li>
+  <li class="add2em">rocks, relation to lava, <a href="#page387">387.</a></li>
+  <li class="add2em">rocks, lithological character of, <a href="#page400">400.</a></li>
+  <li class="add2em">in Lower Eifel, <a href="#page420">420.</a></li>
+
+<li class="martop04">Trappean rocks, <a href="#page91">91.</a></li>
+
+<li class="martop04">Trap-tuff, <a href="#page374">374.</a></li>
+
+<li class="martop04">Tertiary deposits, <a href="#page171">171.</a> <a href="#page177">177.</a> <a href="#page178">178.</a></li>
+
+<li class="martop04">Texas, chalk in, <a href="#page225">225.</a></li>
+
+<li class="martop04"><span class="pagenum"><a id="page512"></a>[p.512]</span>Thames valley, freshwater deposits in, <a href="#page146">146.</a></li>
+
+<li class="martop04">Thecodont Saurians, <a href="#page306">306.</a></li>
+  <li class="add2em">Saurians, age of, Postscript, <a href="#pagexv">xv.</a></li>
+
+<li class="martop04">Thirria, M., on oolitic group in France, <a href="#page283">283.</a></li>
+
+<li class="martop04">Thurmann, M., cited, <a href="#page55">55.</a> <a href="#page252">252.</a> <a href="#page266">266.</a></li>
+
+<li class="martop04"><i>Thuja occidentalis</i> in stomach of mastodon, <a href="#page138">138.</a></li>
+
+<li class="martop04">Till, term explained, <a href="#page121">121.</a></li>
+  <li class="add2em">origin of, <a href="#page123">123.</a></li>
+
+<li class="martop04">Tilestone, <a href="#page351">351.</a></li>
+
+<li class="martop04">Tilgate Forest, remains in, <a href="#page229">229.</a></li>
+
+<li class="martop04">Tin, veins of, in Cornwall, <a href="#page490">490.</a> <a href="#page498">498.</a></li>
+
+<li class="martop04">Tiverton trap, porphyry near, <a href="#page432">432.</a></li>
+
+<li class="martop04">Travertin, how deposited, <a href="#page34">34.</a></li>
+
+<li class="martop04">Tree ferns in Permian formation, <a href="#page307">307.</a></li>
+
+<li class="martop04">Trias, or new red sandstone, <a href="#page286">286.</a> <a href="#page289">289.</a> and Postsc., <a href="#pagexiii">xiii.</a></li>
+  <li class="add2em">in Cheshire and Lancashire, <a href="#page290">290.</a> <a href="#page295">295.</a></li>
+
+<li class="martop04">Trilobite in Devonian strata, <a href="#page348">348.</a></li>
+
+<li class="martop04">Trilobites of Lower Silurian, <a href="#page357">357.</a></li>
+
+<li class="martop04">Trimmer, Mr., on sand-galls, <a href="#page82">82.</a></li>
+  <li class="add2em">on shells in drift near Menai Straits, <a href="#page130">130.</a></li>
+
+<li class="martop04">Tripoli composed of infusoria, <a href="#page24">24.</a></li>
+
+<li class="martop04">Tuff, volcanic, and trap, <a href="#page6">6.</a> <a href="#page374">374.</a></li>
+
+<li class="martop04">Tuffs on Wrekin and Caer Caradoc, <a href="#page434">434.</a></li>
+
+<li class="martop04">Tuomey, Mr., cited, <a href="#page208">208.</a></li>
+
+<li class="martop04">Turner, Dr., cited, <a href="#page41">41.</a> <a href="#page42">42.</a></li>
+
+<li class="martop04">Tuscany, volcanic rocks of, <a href="#page408">408.</a></li>
+
+<li class="martop04">Tynedale fault, <a href="#page64">64.</a></li>
+
+<li class="martop04">Tynemouth Cliff, limestone at, <a href="#page302">302.</a></li>
+</ul>
+
+
+<h3>U.</h3>
+<ul>
+<li class="martop04">Uddevalla, shells of, compared with those near Naples, <a href="#page108">108.</a></li>
+
+<li class="martop04">Underlying, term applied to granite, <a href="#page8">8.</a></li>
+
+<li class="martop04">United States, coal field of, <a href="#page326">326.</a></li>
+  <li class="add2em">cretaceous formation in, <a href="#page224">224.</a></li>
+  <li class="add2em">Devonian strata in, <a href="#page349">349.</a></li>
+  <li class="add2em">Eocene strata in, <a href="#page206">206.</a></li>
+  <li class="add2em">older Pliocene and Miocene formations in, <a href="#page171">171.</a></li>
+  <li class="add2em">oolite and lias of, <a href="#page284">284.</a></li>
+  <li class="add2em">Silurian strata of, <a href="#page359">359.</a></li>
+
+<li class="martop04">Upsala, strata containing Baltic shells near, <a href="#page124">124.</a></li>
+</ul>
+
+
+<h3>V.</h3>
+<ul>
+<li class="martop04">Val di Noto, composition of, <a href="#page407">407.</a></li>
+  <li class="add2em">igneous rocks of, <a href="#page389">389.</a></li>
+  <li class="add2em">inland cliffs in, <a href="#page76">76.</a></li>
+
+<li class="martop04">Valleys, origin of, <a href="#page70">70.</a></li>
+  <li class="add2em">transverse of Weald, <a href="#page244">244.</a></li>
+
+<li class="martop04">Valorsine granite, <a href="#page445">445.</a></li>
+
+<li class="martop04">Veins, mineral. See <a href="#mineralv">Mineral Veins</a>, <a href="#page488">488.</a></li>
+
+<li class="martop04">Veinstones in parallel layers, <a href="#page493">493.</a></li>
+
+<li class="martop04">Velay, volcanos of, <a href="#page428">428.</a></li>
+
+<li class="martop04">Venetz, M., on Alpine glaciers, <a href="#page140">140.</a></li>
+
+<li class="martop04">Verneuil, M. de, on Devonian Flora, <a href="#page350">350.</a></li>
+  <li class="add2em">on horizontal strata in Russia, <a href="#page124">124.</a></li>
+  <li class="add2em">on the old red sandstone in Russia, <a href="#page348">348.</a></li>
+  <li class="add2em">on <i>Pentamerus Knightii</i>, <a href="#page353">353.</a></li>
+  <li class="add2em">on Permian flora, <a href="#page305">305.</a></li>
+
+<li class="martop04">Vesuvius, eruption of, <a href="#page405">405.</a></li>
+
+<li class="martop04">Vicenza, basaltic columns near, <a href="#page386">386.</a></li>
+
+<li class="martop04">Vidal, Capt., survey by, <a href="#page393">393.</a></li>
+
+<li class="martop04">Virginia, U. S., fossil shells in, <a href="#page172">172.</a></li>
+
+<li class="martop04">Virlet, M., on corrosion of rocks by gases, <a href="#page477">477.</a></li>
+  <li class="add2em">on geology of Morea, <a href="#page431">431.</a></li>
+  <li class="add2em">on inland cliffs, <a href="#page73">73.</a></li>
+
+<li class="martop04">Volcanic mountains, form of, <a href="#page5">5.</a> <a href="#page390">390.</a></li>
+  <li class="add2em">dikes, <a href="#page378">378.</a></li>
+
+<li class="martop04">Volcanic rocks, age of, <a href="#page397">397.</a></li>
+  <li class="add2em">described, <a href="#page5">5.</a> <a href="#page385">385.</a></li>
+  <li class="add2em">analysis of minerals in, <a href="#page377">377.</a></li>
+  <li class="add2em">Cambrian, <a href="#page435">435.</a></li>
+  <li class="add2em">composition and nomenclature, <a href="#page368">368.</a></li>
+  <li class="add2em">of Hungary, <a href="#page421">421.</a></li>
+  <li class="add2em">post-pliocene period, <a href="#page401">401.</a></li>
+  <li class="add2em">test of age of, <a href="#page400">400.</a></li>
+  <li class="add2em">Silurian, <a href="#page434">434.</a></li>
+
+<li class="martop04">Volcanic tuff, <a href="#page374">374.</a></li>
+
+<li class="martop04">Volcanos of Auvergne, <a href="#page422">422.</a></li>
+  <li class="add2em">extinct, <a href="#page408">408.</a> <a href="#page420">420.</a> <a href="#page422">422.</a></li>
+  <li class="add2em">newer, of Eifel, <a href="#page418">418.</a></li>
+  <li class="add2em">in Spain, age of, <a href="#page414">414.</a></li>
+  <li class="add2em">round Olot in Catalonia, <a href="#page410">410.</a></li>
+
+<li class="martop04">Von Buch, Baron, cited, <a href="#page373">373.</a> <a href="#page456">456.</a> <a href="#page457">457.</a></li>
+  <li class="add2em">on boulders of Jura, <a href="#page143">143.</a></li>
+  <li class="add2em">on Canary Islands, <a href="#page392">392.</a></li>
+  <li class="add2em">on Cystide�, <a href="#page358">358.</a></li>
+  <li class="add2em">on land rising, <a href="#page45">45.</a></li>
+
+<li class="martop04">Von Dechen, M., on granite veins in Cornwall, <a href="#page445">445.</a></li>
+  <li class="add2em">Oeynhausen, M., cited, <a href="#page415">415.</a></li>
+</ul>
+
+
+<h3>W.</h3>
+<ul>
+<li class="martop04">Waller quoted, <a href="#page93">93.</a></li>
+
+<li class="martop04">Warren, Dr. J. C., on skeleton of <i>Mastodon giganteus</i>, <a href="#page138">138.</a></li>
+
+<li class="martop04">Waterhouse, Mr., cited, <a href="#page188">188.</a> <a href="#page269">269.</a></li>
+  <li class="add2em">on triassic mammifer, Postscript, <a href="#pagexiv">xiv.</a></li>
+
+<li class="martop04">Watt, Mr. G., experiments on fused rocks, <a href="#page406">406.</a> <a href="#page475">475.</a></li>
+
+<li class="martop04">Weald clay, <a href="#page227">227.</a></li>
+
+<li class="martop04">Weald valley, denuded at what period, <a href="#page254">254.</a></li>
+
+<li class="martop04">Wealden, term explained, <a href="#page225">225.</a> <a href="#page226">226.</a></li>
+  <li class="add2em">the fracture and upheaval of, <a href="#page251">251.</a></li>
+  <li class="add2em">extent of formation, <a href="#page236">236.</a></li>
+  <li class="add2em">period, changes during, <a href="#page235">235.</a></li>
+
+<li class="martop04">Wealden, plants and animals of, <a href="#page229">229.</a> <a href="#page236">236.</a></li>
+
+<li class="martop04">Webster, Mr. T., cited, <a href="#page105">105.</a> <a href="#page231">231.</a> <a href="#page233">233.</a></li>
+
+<li class="martop04">Wellington Valley, caves in, <a href="#page156">156.</a></li>
+
+<li class="martop04">Wener Lake, horizontal Silurian strata of, <a href="#page45">45.</a></li>
+
+<li class="martop04">Wenlock formation, <a href="#page354">354.</a></li>
+
+<li class="martop04">Werner on classification of rocks, <a href="#page90">90.</a></li>
+  <li class="add2em">on mineral veins, <a href="#page488">488.</a></li>
+  <li class="add2em">on volcanic rocks, <a href="#page369">369.</a></li>
+
+<li class="martop04">Westerwald, igneous rocks of, <a href="#page417">417.</a></li>
+
+<li class="martop04">Westwood, Mr., on beetles in lias, <a href="#page282">282.</a></li>
+
+<li class="martop04">Whin-Sill, intrusion of trap between strata, <a href="#page384">384.</a></li>
+
+<li class="martop04">White chalk, <a href="#page211">211.</a></li>
+
+<li class="martop04">White mountains, granite vein in, <a href="#page450">450.</a></li>
+
+<li class="martop04">Wigham, Mr., on fossils near Norwich, <a href="#page149">149.</a></li>
+
+<li class="martop04">Wolverhampton, fossil forest near, <a href="#page319">319.</a></li>
+
+<li class="martop04">Wood, Mr. Searles, on fossils of crag, <a href="#page162">162.</a></li>
+  <li class="add2em">on fossils of Isle of Wight, <a href="#page198">198.</a></li>
+  <li class="add2em">on number of shells in crag, <a href="#page149">149.</a></li>
+  <li class="add2em">on cetacea of crag, <a href="#page166">166.</a></li>
+  <li class="add2em">cited, <a href="#page170">170.</a> <a href="#page177">177.</a></li>
+
+<li class="martop04">Woodward, Mr., on mammoth bones, Norfolk, <a href="#page147">147.</a></li>
+
+<li class="martop04">Wrekin, trap of, <a href="#page70">70.</a></li>
+
+<li class="martop04">Wyman, Dr., cited, <a href="#page208">208.</a></li>
+</ul>
+
+
+<h3>Z.</h3>
+<ul>
+<li class="martop04"><i>Zamia</i>, at Lyme Regis, <a href="#page282">282.</a></li>
+
+<li class="martop04"><i>Zamia spiralis</i>, figure of, <a href="#page233">233.</a></li>
+
+<li class="martop04">Zechstein, <a href="#page306">306.</a></li>
+
+<li class="martop04"><i>Zeuglodon cetoides</i>, <a href="#page207">207.</a> and Postscript, <a href="#pagexxi">xxi.</a></li>
+</ul>
+
+
+<p class="center1 ftsize95 martop2"><span class="smcap">London</span>:</p>
+<p class="center1 ftsize90 martopm05"><span class="smcap">Spottiswoodes</span> and <span class="smcap">Shaw</span>,<br>
+New-street-Square.</p>
+
+
+
+
+<hr class="sep2">
+<p class="teri martop4"><span class="pagenum1"><a id="pageA"></a>[p.A]</span><span class="smcap">Albemarle Street</span>,<br>
+<i>July 5, 1851</i>.</p>
+
+
+<p class="center1 ftsize120 martop2"><b>MR. MURRAY'S</b></p>
+
+<p class="fextra">List of Recent Works</p>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">HISTORY OF THE ROMAN STATE;</p>
+<p class="ftsize101">FROM 1815-1850. BY LUGIA CARLO FARINI.</p>
+<p class="ftsize50 fweight">TRANSLATED FROM THE ITALIAN</p>
+<p class="ftsize104 wosp05 hweight">BY THE RIGHT HON. W. E. GLADSTONE, M.P.</p>
+<p class="ftsize95">2 <span class="wosp05">Vols. 8vo. 24<i>s.</i></span></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE EXPOSITION OF 1851;</p>
+<p class="ftsize101">OR, VIEWS OF THE INDUSTRY, THE SCIENCE, AND THE GOVERNMENT OF ENGLAND.</p>
+<p class="ftsize104 wosp05 hweight">BY CHARLES BABBAGE, ESQ.,</p>
+<p class="ftsize95 martopm05">Author of the "Economy of Manufactures and Machinery."</p>
+<p class="ftsize95"><i>Second Edition</i>, with an <span class="wosp05">Appendix. 8vo. 6<i>s.</i></span> 6<i>d.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE DOVECOTE AND THE AVIARY;</p>
+<p class="ftsize101">OR, THE NATURAL HISTORY OF PIGEONS AND OTHER DOMESTIC BIRDS, WITH HINTS
+FOR THEIR MANAGEMENT.</p>
+<p class="ftsize104 wosp05 hweight">BY THE REV. EDMUND SAUL DIXON, M.A.,</p>
+<p class="ftsize95 martopm05">Author of "Ornamental and Domestic Poultry."</p>
+<p class="ftsize95">With Numerous <span class="wosp05">Woodcuts. Fcap.</span> <span class="wosp05">8vo. 7<i>s</i>.</span> 6<i>d</i>.</p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">MEMOIR OF THE LIFE OF THE LATE BISHOP STANLEY.</p>
+<p class="ftsize101">PREFIXED TO A SELECTION FROM HIS ADDRESSES AND CHARGES.</p>
+<p class="ftsize104 wosp05 hweight">BY THE REV. ARTHUR PENRHYN STANLEY, M.A.</p>
+<p class="ftsize95">8vo. 10<i>s.</i> 6<i>d.</i></p>
+</div>
+
+<p>"The memoir is executed with feeling, and, as might be expected from the
+biographer of Dr. Arnold, with great skill. Mr. Stanley brings out into
+strong relief the more attractive parts of his father's character, and
+suggests the best defence&mdash;namely, the consistent uprightness and perfect
+sincerity of his motives&mdash;for the more questionable policy, on some
+memorable occasions, of the bishop."</p>
+
+<p class="teri martopm05"><i>Morning Chronicle.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;<span class="pagenum1"><a id="pageB"></a>[p.B]</span></p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">A PASTORAL LETTER ON THE STATE OF THE CHURCH,</p>
+<p class="ftsize104 wosp05 hweight">BY HENRY LORD BISHOP OF EXETER.</p>
+<p class="ftsize95"><i>Eighth</i> <span class="wosp05"><i>Edition.</i> 8vo. 4<i>s.</i></span></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE ACTS OF THE SYNOD OF EXETER.</p>
+<p class="ftsize101">HOLDEN IN THE CHAPTER HOUSE OF THE CATHEDRAL CHURCH OF EXETER.</p>
+<p class="ftsize95"><span class="smcap">On June</span> 25, 26, and 27, 1851.</p>
+<p class="ftsize95">8vo.</p>
+<p class="ftsize95">&#8258; <i>The Sermon may be had separately, price 1s.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE EVANGELICAL AND TRACTARIAN MOVEMENTS.</p>
+<p class="ftsize104 wosp05 hweight">BY ARCHDEACON WILBERFORCE.</p>
+<p class="ftsize95">(A Charge delivered to and published by Request of the Clergy.)</p>
+<p class="ftsize95 wosp05">8vo. 1<i>s.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">A HISTORY OF ERASTIANISM.</p>
+<p class="ftsize104 wosp05 hweight">BY ARCHDEACON WILBERFORCE.</p>
+<p class="ftsize95 wosp05">16mo. 3<i>s.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">CATHOLIC SAFEGUARDS</p>
+<p class="ftsize102">AGAINST THE ERRORS, CORRUPTIONS, AND NOVELTIES OF THE CHURCH OF ROME.</p>
+<p class="ftsize101">BEING DISCOURSES AND TRACTS SELECTED FROM THE WORKS OF EMINENT DIVINES OF THE
+CHURCH OF ENGLAND WHO LIVED DURING THE 17TH CENTURY; WITH
+PREFACE, RECORDS, AND A CAREFULLY COMPILED INDEX.</p>
+<p class="ftsize104 wosp05 hweight">BY REV. JAMES BROGDEN, M.A.</p>
+<p class="ftsize95">3 <span class="wosp05">Vols. 8vo. 36<i>s.</i></span></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">RECORDS OF THE SUPREMACY OF THE CROWN,</p>
+<p class="ftsize102">AND THE CIVIL AND RELIGIOUS LIBERTIES OF THE PEOPLE OF ENGLAND.</p>
+<p class="ftsize104 wosp05 hweight">BY REV. JAMES BROGDEN.</p>
+<p class="ftsize95 wosp05">8vo. 4<i>s.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;<span class="pagenum1"><a id="pageC"></a>[p.C]</span></p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">HOR� �GYPTIAC�;</p>
+<p class="ftsize102">OR, THE CHRONOLOGY OF ANCIENT EGYPT.</p>
+<p class="ftsize95">DISCOVERED FROM ASTRONOMICAL AND HIEROGLYPHIC RECORDS UPON ITS MONUMENTS
+INCLUDING MANY DATES FOUND IN COEVAL INSCRIPTIONS.</p>
+<p class="ftsize104 wosp05 hweight">BY REGINALD STUART POOLE, ESQ.</p>
+<p class="ftsize95">With <span class="wosp05">Plates. 8vo. 10<i>s.</i></span> 6<i>d.</i></p>
+</div>
+
+<p>"The substance of Mr. Poole's valuable work appeared originally in a series
+of papers in this journal. Since their publication the author has devoted
+further time and attention to the subject; and it may safely be asserted
+that in their present amended and enlarged form, they are among the most
+important contributions that have yet been made to the study of Egyptian
+Chronology and history. We are indebted for the publication of the present
+valuable work to the liberality of the Duke of Northumberland, whose warm
+and generous support of literature and art deserves our grateful
+acknowledgments."</p>
+
+<p class="teri martopm05"><i>Literary Gazette.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">LAVENGRO;</p>
+<p class="ftsize101">THE SCHOLAR&mdash;THE GIPSY&mdash;AND THE PRIEST.</p>
+<p class="ftsize104 wosp05 hweight">BY GEORGE BORROW, ESQ.</p>
+<p class="ftsize95 martopm05">Author of "The Bible in Spain," "The Gipsies of Spain," &amp;c. &amp;c.</p>
+<p class="ftsize95">With a <span class="wosp05">Portrait. 3</span> <span class="wosp05">Vols. Post</span> <span class="wosp05">8vo. 30<i>s.</i></span></p>
+</div>
+
+<p>"We trust our extracts have exhibited enough of one at least of the many
+aspects of 'Lavengro' to convince the reader that neither is it a work to
+be read cursorily, nor to be handled easily, by any of the silver-fork
+school of critics. These volumes are indeed replete with life, with earnest
+sympathy for all genuine workers, with profound insight into the wants and
+wishes of the poor and uneducated, and a lofty disdain of the conventional
+'shams' and pretensions which fetter the spirits or impede the energies of
+mankind. Nor is a feeling for the beautiful less conspicuous in its pages.
+A quiet market-town, environed by green meadows or bosomed in tufted trees;
+an old mercantile and ecclesiastical city, with a history stretching from
+the times of the C�sars to the times of George III.; the treeless plain,
+the broad river, the holt, the dingle, the blacksmith's forge, are all in
+their turn sketched freely and vividly by Mr. Borrow's pencil. In his
+portraitures of ruder life he is unsurpassed; a dog-fight, a prize-fight,
+an ale-house kitchen, Greenwich Fair, a savage group of wandering tinkers,
+are delineated in words as Wilkie or Hogarth might have depicted them in
+colours. We are embarrassed by the riches spread before us.</p>
+
+<p class="martopm05">"We have not touched upon the gipsy scenes in 'Lavengro' because in any
+work of Mr. Borrow's these will naturally be the first to draw the reader's
+attention. Neither have we aimed at abridging or forestalling any portions
+of a book which has a panoramic unity of its own, and of which scarcely a
+page is without its proper interest. If we have succeeded in persuading our
+readers to regard Mr. Borrow as partly an historian and partly as a poet,
+as well as to look for more in his volumes than mere excitement or
+amusement, our purpose is attained, and we may securely commend him to the
+goodly company he will find therein. 'Lavengro,' however, is not concluded;
+a fourth volume will explain and gather up much of what is now somewhat
+obscure and fragmentary, and impart a more definite character to the
+philological and physiological hints comprised in those now before us.
+Enough, indeed, and more than enough, is written to prove that the author
+possesses, in no ordinary measure, 'the vision and the faculty divine' for
+discerning and discriminating what is noble in man and what is beautiful in
+nature. We trust Mr. Borrow will speedily bring forth the remaining acts of
+his 'dream of adventure,' and with good heart and hope pursue his way
+rejoicing, regardless of the misconceptions or misrepresentations of
+critics who judge through a mist of conventionalities, and who themselves,
+whether travelled or untravelled, have not, like Lavengro, grappled with
+the deeper thoughts and veracities of human life."&mdash;<i>Tait's Magazine.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;<span class="pagenum1"><a id="pageD"></a>[p.D]</span></p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">ENGLAND IN THE NINETEENTH CENTURY:</p>
+<p class="ftsize101">POLITICAL, SOCIAL, AND INDUSTRIAL.</p>
+<p class="ftsize104 wosp05 hweight">BY WILLIAM JOHNSTON, ESQ.</p>
+<p class="ftsize95">2 <span class="wosp05">Vols. Post</span> <span class="wosp05">8vo. 18<i>s.</i></span></p>
+</div>
+
+<p>"This book is a somewhat undigested mass of valuable matter, interspersed
+occasionally with reflections of much interest and observations of
+considerable originality. The author is unquestionably a man of talent; he
+writes with vigour and smartness; he has taken pains in the collection of
+most of his materials; and his statistics are arranged with great care and
+managed with unusual skill. In this point he is much superior to his
+prototype and apparent master, Mr. Alison."</p>
+
+<p>"Mr. Johnston's work is readable and well-written, abounding with
+information of many kinds."&mdash;<i>Edinburgh Review.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE SAXON IN IRELAND:</p>
+<p class="ftsize101">BEING NOTES OF THE RAMBLES OF AN ENGLISHMAN IN THE WEST OF IRELAND
+IN SEARCH OF A SETTLEMENT.</p>
+<p class="ftsize95">With <span class="wosp05">Map. Post</span> <span class="wosp05">8vo. 9</span><i>s.</i> 6<i>d.</i></p>
+</div>
+
+<p>"A valuable testimony to the capabilities of Ireland."&mdash;<i>Observer.</i></p>
+
+<p Class="martopm05">"Let the intending emigrant devote a few hours to the perusal of this
+volume. The work possesses deeper interest than even could be claimed for
+it from its fascinating descriptions."&mdash;<i>Illustrated News.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">SLEEP AND DREAMS:</p>
+<p class="ftsize101">TWO LECTURES DELIVERED AT THE BRISTOL LITERARY AND PHILOSOPHICAL
+INSTITUTION.</p>
+<p class="ftsize104 wosp05 hweight">BY JOHN ADDINGTON SYMONDS, M.D.,</p>
+<p class="ftsize95">Consulting Physician to the Bristol General Hospital.</p>
+<p class="ftsize95"><span class="wosp05">8vo. 2<i>s.</i></span> 6<i>d.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize110 martop2 hweight">THE PALACES OF</p>
+<p class="ftsize120 hweight">NINEVEH AND PERSEPOLIS RESTORED.</p>
+<p class="ftsize101">AN ESSAY ON ANCIENT ASSYRIAN AND PERSIAN ARCHITECTURE.</p>
+<p class="ftsize104 wosp05 hweight">BY JAMES FERGUSSON ESQ.,</p>
+<p class="ftsize95">With <span class="wosp05">Woodcuts. 8vo. 16<i>s.</i></span></p>
+</div>
+
+<p>"This book contains many things of general interest relating to one of the
+most wonderful discoveries that has occurred in the history of the world.
+Mr. Fergusson writes very dispassionately. What he has said deserves
+serious consideration."&mdash;<i>Gentleman's Magazine.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">SHALL WE KEEP THE CRYSTAL PALACE</p>
+<p class="ftsize101">AND HAVE RIDING AND WALKING IN ALL WEATHERS, AMONG FLOWERS, SCULPTURE,
+AND FOUNTAINS?</p>
+<p class="ftsize104 wosp05 hweight">BY DENARIUS.</p>
+<p class="ftsize95 wosp05">8vo. 6<i>d.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;<span class="pagenum1"><a id="pageE"></a>[p.E]</span></p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">MEMOIRS OF ROBERT PLUMER WARD.</p>
+<p class="ftsize101">WITH HIS CORRESPONDENCE, DIARIES, AND LITERARY REMAINS.</p>
+<p class="ftsize104 wosp05 hweight">BY THE HON. EDMUND PHIPPS.</p>
+<p class="ftsize95">With <span class="wosp05">Portrait. 2</span> <span class="wosp05">Vols. 8vo. 28<i>s.</i></span></p>
+</div>
+
+<p>"The most valuable portions of Mr. Ward's diary are its illustrations of
+the character of the Duke of Wellington. The great soldier, then in the
+flush of his military triumph, was also in the prime of his power and
+activity; and Mr. Ward gives us an insight into his business habits, his
+method of arguing public questions, his ready resource and never-tiring
+energy, which possesses occasionally a striking interest."&mdash;<i>Examiner.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE MILITARY EVENTS IN ITALY, 1848-9.</p>
+<p class="ftsize101">TRANSLATED FROM THE GERMAN.</p>
+<p class="ftsize104 wosp05 hweight">BY THE RIGHT HON. THE EARL OF ELLESMERE.</p>
+<p class="ftsize95">With a <span class="wosp05">Map. Post</span> <span class="wosp05">8vo. 9<i>s.</i></span></p>
+</div>
+
+<p>"Military history is, as the Earl of Ellesmere declares, a rare article in
+English literature; and, therefore, he thought that the most authentic
+extant narrative of the operations implied in the title page of the present
+book, written by an impartial Swiss, would not be an unwelcome addition to
+the British library. His lordship has judged rightly; the work of which he
+has presented a version is a worthy labour, and the events to which it
+relates are of the last importance. It is written with judgment, and has
+been translated with care."&mdash;<i>Morning Chronicle.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">A TRANSPORT VOYAGE TO THE MAURITIUS,</p>
+<p class="ftsize101">BY WAY OF THE CAPE OF GOOD HOPE AND ST. HELENA.</p>
+<p class="ftsize104 wosp05 hweight">BY THE AUTHOR OF "PADDIANA."</p>
+<p class="ftsize95">Post 8vo. 9<i>s.</i> 6<i>d.</i></p>
+</div>
+
+<p>"This book reminds us of one of those pleasant fellows, whom one sometimes
+meets with in company, who has an anecdote or a story ready � propos of
+everything, whose fund of amusing tales is inexhaustible, and who rattling
+on from one thing to another, will keep a whole table in a roar, or a whole
+drawing-room in high glee. Even such is our author. He gossips on and on,
+telling now of one adventure, and then of another; his volume is a perfect
+chaos of racy reminiscences graphically told."&mdash;<i>John Bull.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">ADMIRALTY MANUAL OF SCIENTIFIC ENQUIRY</p>
+<p class="ftsize101">FOR THE USE OF OFFICERS AND TRAVELLERS IN GENERAL.</p>
+<p class="ftsize101">BY PROFESSORS WHEWELL, AIRY, OWEN, SIR W. HOOKER, CAPT. BEECHEY,
+J. R. HAMILTON, ESQ., SIR JOHN HERSCHEL, &amp;c.</p>
+<p class="ftsize104 wosp05 hweight">EDITED BY SIR JOHN F. HERSCHEL, BART.</p>
+<p class="ftsize95">Second <span class="wosp05">Edition. Post</span> <span class="wosp05">8vo. 10<i>s.</i></span> 6<i>d.</i></p>
+<p class="ftsize101">&#8258; <i>Published by Authority of the Lords Commissioners of the Admiralty.</i></p>
+</div>
+
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;<span class="pagenum1"><a id="pageF"></a>[p.F]</span></p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">LIVES OF THE CHIEF JUSTICES OF ENGLAND.</p>
+<p class="ftsize101">FROM THE NORMAN CONQUEST TO THE DEATH OF LORD MANSFIELD.</p>
+<p class="ftsize104 wosp05 hweight">BY LORD CHIEF JUSTICE CAMPBELL.</p>
+<p class="ftsize95">2 <span class="wosp05">Vols. 8vo. 30<i>s.</i></span></p>
+</div>
+
+<p>"There is, indeed, in Lord Campbell's works much instruction; his subjects
+have been so happily selected, that it was scarcely possible that there
+should not be. An eminent lawyer and statesman could not write the lives of
+great statesmen and lawyers without interweaving curious information, and
+suggesting valuable principles of judgment and useful practical maxims: but
+it is not for these that his works will be read. Their principal merit is
+their easy animated flow of interesting narrative. No one possesses better
+than Lord Campbell the art of telling a story: of passing over what is
+commonplace; of merely suggesting what may be inferred; of explaining what
+is obscure; and of placing in strong light the details of what is
+interesting."&mdash;<i>Edinburgh Review.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE FORTY-FIVE.</p>
+<p class="ftsize101">BEING A NARRATIVE OF THE REBELLION IN SCOTLAND OF 1745;</p>
+<p class="ftsize104 wosp05 hweight">BY LORD MAHON.</p>
+<p class="ftsize95">Post<span class="wosp05"> 8vo. 3<i>s.</i></span></p>
+</div>
+
+<p>"This is a very comprehensive and lively sketch of the famous 'Rebellion'
+so vividly remembered, even after the lapse of a century, by the people of
+Scotland. The incidents of that unfortunate invasion from first to last,
+from the landing of Charles (July 25th) in Borrodale, with the 'seven men
+of Moidart,' to the fatal battle of Culloden (16th April, 1746), are
+minutely and faithfully recorded; but we have no doubt the reader will be
+most and mainly interested in the personal history and adventures of the
+Pretender himself. The character of the Prince is admirably drawn, and
+generously vindicated from the calumnies heaped upon him by his adversaries
+after his fall. It will perhaps surprise some to learn, that he was so
+illiterate as scarcely to be master of the most common elements of
+education. 'His letters,' says Lord Mahon, 'which I have seen among the
+Stuart papers, are written in a large, rude, rambling hand, like a
+schoolboy's. In spelling they are still more deficient.' We recommend Lord
+Mahon's narrative as a very agreeable sketch of a stirring and eventful
+period."&mdash;<i>Edinburgh Advertiser.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">A HISTORY OF GREECE.</p>
+<p class="ftsize101">FROM THE EARLIEST PERIOD TO THE END OF THE PELOPONNESIAN WAR.</p>
+<p class="ftsize104 wosp05 hweight">BY GEORGE GROTE, ESQ.</p>
+<p class="ftsize95">Vols. <span class="wosp05">I.-VIII. With</span> <span class="wosp05">Maps. 8vo. 16<i>s.</i></span> each.</p>
+<i>The Work may be obtained in Portions, as it was published</i>:&mdash;
+</div>
+
+<ul class="lihei1 add2em min2em">
+<li class="add4em"><span class="smcap">Vols.</span> I.-II.</li>
+  <li><span class="smcap">Legendary Greece.</span></li>
+  <li><span class="smcap">Grecian History to the Reign of Peisistratus at Athens.</span></li>
+<li class="add4em martop1"><span class="smcap">Vols.</span> III.-IV.</li>
+  <li><span class="smcap">History of Early Athens, and the Legislation of Solon.</span></li>
+  <li><span class="smcap">Grecian Colonies.</span></li>
+  <li><span class="smcap">View of the Contemporary Nations surrounding Greece.</span></li>
+  <li><span class="smcap">Grecian History down to the first Persian Invasion, and the Battle of
+Marathon.</span></li>
+<li class="add4em martop1"><span class="smcap">Vols.</span> V.-VI.</li>
+  <li><span class="smcap">Persian War and Invasion of Greece by Xerxes.</span></li>
+  <li><span class="smcap">Period between the Persian and the Peloponnesian Wars.</span></li>
+  <li><span class="smcap">Peloponnesian War down to the Expedition of the Athenians against Syracuse.</span></li>
+<li class="add4em martop1"><span class="smcap">Vols.</span> VII.-VIII.</li>
+  <li><span class="smcap">The Peace of Nikias down to the Battle of Knidus [b.c. 421 to 394.]</span></li>
+  <li><span class="smcap">Socrates and the Sophists.</span></li>
+</ul>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;<span class="pagenum1"><a id="pageG"></a>[p.G]</span></p>
+
+<div class="center1">
+<p class="ftsize110 martop2 hweight">KUGLER'S HANDBOOK ILLUSTRATED.</p>
+<p class="ftsize120 hweight">THE SCHOOLS OF PAINTING IN ITALY.</p>
+<p class="ftsize101 martopm05">FROM THE EARLIEST TIMES.</p>
+<p class="ftsize95">TRANSLATED FROM THE GERMAN BY A LADY, AND EDITED WITH NOTES</p>
+<p class="ftsize104 wosp05 hweight">BY SIR CHARLES LOCK EASTLAKE,</p>
+<p class="ftsize95 martopm05">President of the Royal Academy.</p>
+<p class="ftsize95"><i>A New Edition.</i> 2 Vols. Post 8vo. 24<i>s.</i></p>
+</div>
+
+<p>"We cannot leave this subject (<i>Christian Art, its present state and its
+prospects</i>), without reverting to Sir C. Eastlake's edition of Kugler's
+Handbook of Painting, not for the sake of reviewing it,&mdash;for it is a work
+now of established reputation,&mdash;but for the purpose of recommending it as
+being upon the whole by far the best manual we are acquainted with, for
+every one who, without the opportunity of foreign and particularly Italian
+travel, desires to make a real study of art. Its method, its chronological
+arrangement, and its generally judicious criticism, make it most
+instructive to a learner. We may add that the present edition is enlarged
+just where the former one needed enlargement, and the Handbook is now far
+more satisfactory as to the early religious schools than it was before. The
+edition is beautifully got up, and so profusely and judiciously illustrated
+by one hundred woodcuts drawn by Scharf, that it would be next to
+impossible to speak too highly in its praise, even were its matter less
+valuable and important than it is."&mdash;<i>The Ecclesiastic.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">CHRISTIANITY IN CEYLON:</p>
+<p class="ftsize101">ITS INTRODUCTION AND PROGRESS UNDER THE PORTUGUESE, DUTCH,
+BRITISH, AND AMERICAN MISSIONS.</p>
+<p class="ftsize104 wosp05 hweight">BY SIR JAMES EMERSON TENNENT, K.C.S., LL.D.</p>
+<p class="ftsize95">With Illustrations. 8vo. 14<i>s.</i></p>
+</div>
+
+<p>"To those who take either a religious or a philosophical interest in the
+subject, Sir Emerson Tennent's volume may be safely recommended, as a
+clear, succinct, sensible, and flowing account. The work also possesses a
+living animation arising from the author's knowledge of the country and the
+people."&mdash;<i>Spectator.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+
+<div class="center1">
+<p class="ftsize110 martop2 hweight">THE LEXINGTON PAPERS.</p>
+<p class="ftsize120 hweight">THE COURTS OF LONDON AND VIENNA</p>
+<p class="ftsize101">IN THE 17TH CENTURY.</p>
+<p class="ftsize101">EXTRACTED FROM THE PRIVATE AND OFFICIAL CORRESPONDENCE OF LORD LEXINGTON,
+WHILE BRITISH MINISTER AT VIENNA, 1694-98.</p>
+<p class="ftsize104 wosp05 hweight">EDITED BY THE HON. H. MANNERS SUTTON.</p>
+<p class="ftsize95">8vo. 14<i>s.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">THE LAW AND PRACTICE OF NAVAL COURTS-MARTIAL.</p>
+<p class="ftsize104 wosp05 hweight">BY WILLIAM HICKMAN, R.N.,</p>
+<p class="ftsize95">Late Secretary to Commodore Sir Charles Hotham, K.C.B.</p>
+<p class="ftsize95">8vo. 10<i>s.</i> 6<i>d.</i></p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;<span class="pagenum1"><a id="pageH"></a>[p.H]</span></p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">A MANUAL OF ELEMENTARY GEOLOGY;</p>
+<p class="ftsize101 martopm05">OR, THE ANCIENT CHANGES OF THE EARTH AND ITS INHABITANTS, AS ILLUSTRATED
+BY ITS GEOLOGICAL MONUMENTS.</p>
+<p class="ftsize104 wosp05 hweight">BY SIR CHARLES LYELL, F.R.S., P.G.S.</p>
+<p class="ftsize95">Third Edition, thoroughly revised, and illustrated with 520 Woodcuts. 8vo. 12<i>s.</i></p>
+</div>
+
+<p>"The production of one of our most eminent geologists in an age of many.
+Though styled a 'third edition,' it is in reality a new book. This could
+not be otherwise if the task were well done; for the science of which Sir
+Charles Lyell treats is assuming new aspects every year. It is continually
+advancing and ever growing. As it advances, its steps become firmer and
+surer; as it grows, its framework becomes more compact, and its
+organization more perfect. They who take up the hammer to follow it must
+toil with unflagging tread to keep pace with its onward progress. If they
+lag behind, they can scarcely hope to overtake. None among its votaries has
+marked each movement more minutely, or weighed its value and purpose more
+judiciously, than the distinguished author of this Manual. He has indeed
+done his task well, and both the beginner and the experienced investigator
+will find his book an invaluable guide and companion."&mdash;<i>Literary Gazette.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize101 martop2">COMMENTARIES ON</p>
+<p class="ftsize120 hweight">THE WAR IN RUSSIA AND GERMANY OF 1813-14.</p>
+<p class="ftsize104 wosp05 hweight">BY COLONEL THE HON. GEORGE CATHCART,</p>
+<p class="ftsize95">Deputy-Lieutenant of the Tower of London.</p>
+<p class="ftsize95 martop05">With Plans. 8vo. 14<i>s.</i></p>
+</div>
+
+<p>"As a Treatise on the Science of War, these Commentaries ought to find
+their way into the hands of every soldier. In them is to be found an
+accurate record of events of which no military man should be
+ignorant."&mdash;<i>Morning Chronicle.</i></p>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<div class="center1">
+<p class="ftsize120 martop2 hweight">MODERN DOMESTIC COOKERY.</p>
+<p class="ftsize101">FOUNDED UPON PRINCIPLES OF ECONOMY AND PRACTICAL
+KNOWLEDGE.</p>
+<p class="ftsize95">AND ADAPTED FOR THE USE OF PRIVATE FAMILIES.</p>
+<p class="ftsize95">With 100 Woodcuts. Post 8vo. 6<i>s.</i></p>
+</div>
+
+<p>"The advanced state of cookery having rendered Mrs. Rundell's work
+obsolete, the publisher has caused it to be remodelled and improved to such
+an extent as to give it a claim to the title of an original production. The
+receipts of the late Miss Emma Roberts have been revised and added to the
+work; and it has had the advantage of being subjected besides to the
+careful inspection of a 'professional gentleman'&mdash;Economy combined with
+excellence&mdash;is the aim, end, and object which it cannot be doubted will be
+obtained if its prescriptions are attended to. It is fuller than the former
+<i>Domestic Cookery</i>, of which it is an improved and amended edition&mdash;it is
+more simple and comprehensible in its language; it contains several
+diagrams not to be found in its predecessor; and it possesses various minor
+qualities, which increase its value in a tenfold degree, and make it, to
+say the least, equal to any other book of the kind in the English
+language."&mdash;<i>Observer.</i></p>
+
+
+<hr class="sep2">
+<p class="teri martop4"><span class="pagenum1"><a id="pageI"></a>[p.I]</span><span class="smcap">Albemarle Street</span>,<br>
+<i>July 5, 1851</i>.</p>
+
+<p class="center1 ftsize120 martop2">MR. MURRAY'S</p>
+
+<p class="fextra">List of Works in the Press.</p>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Selections from the Despatches of the Duke of
+Wellington.</p>
+<p class="ftsize104">BY THE LATE COL. GURWOOD, C.B., K.C.T.S.</p>
+<p class="ftsize85">A New <span class="wosp05">Edition. One</span> <span class="wosp05">Volume. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">History of England, from the Peace of Utrecht.</p>
+<p class="ftsize95">VOLS. 5 &amp; 6&mdash;THE FIRST YEARS OF THE AMERICAN WAR: 1763&mdash;1780.</p>
+<p class="ftsize104">BY LORD MAHON, M.P.</p>
+<p class="ftsize85">2 <span class="wosp05">Vols. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Lives of the Friends and Contemporaries of Lord
+Chancellor Clarendon.</p>
+<p class="ftsize95">ILLUSTRATIVE OF PORTRAITS IN HIS GALLERY; WITH AN ACCOUNT OF THE ORIGIN OF THE
+COLLECTION; AND A DESCRIPTIVE CATALOGUE OF THE PICTURES.</p>
+<p class="ftsize104">BY LADY THERESA LEWIS.</p>
+<p class="ftsize85">With <span class="wosp05">Portraits. 2</span> <span class="wosp05">Vols. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">The Treasures of Art in Great Britain.</p>
+<p class="ftsize95">BEING AN ACCOUNT OF THE CHIEF COLLECTIONS OF PAINTINGS, SCULPTURE, MSS.
+MINIATURES, &amp;c., &amp;c.,</p>
+<p class="ftsize95">OBTAINED FROM PERSONAL INSPECTION DURING VISITS IN 1836 AND 1850.</p>
+<p class="ftsize50">(BEING A REVISED AND GREATLY ENLARGED VERSION OF "ART AND ARTISTS IN ENGLAND.")</p>
+<p class="ftsize104">BY DR. WAAGEN,</p>
+<p class="ftsize85">Director of the Royal Gallery of Pictures at Berlin.</p>
+<p class="ftsize85">2 <span class="wosp05">Vols. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2"><span class="pagenum1"><a id="pageJ"></a>[p.J]</span>The Grenville Papers;</p>
+<p class="ftsize50">BEING</p>
+<p class="ftsize95">THE PRIVATE CORRESPONDENCE OF RICHARD GRENVILLE, EARL TEMPLE, K.G.,
+AND HIS BROTHER, THE RIGHT HONOURABLE GEORGE GRENVILLE,
+THEIR FRIENDS AND CONTEMPORARIES,</p>
+<p class="ftsize50">FORMERLY PRESERVED AT STOWE&mdash;NOW FOR THE FIRST TIME MADE PUBLIC.</p>
+</div>
+
+<p class="hroena">&mdash;&mdash;&mdash;<b>&#9830;</b>&mdash;&mdash;&mdash;</p>
+
+<p class="center1"><i>Among the contents of this highly important accession to the History of Great Britain in the middle of the
+Eighteenth Century, will be found Letters from</i></p>
+
+<ul class="lihei1 add4em">
+<li class="ftsize110">H. M. KING GEORGE THE THIRD.</li>
+<li class="add2em smaller">H. R. H. WILLIAM DUKE OF CUMBERLAND.</li>
+<li class="ftsize110 martop1">DUKES OF:&mdash;</li>
+  <li class="add2em smaller">NEWCASTLE.</li>
+  <li class="add2em smaller">DEVONSHIRE.</li>
+  <li class="add2em smaller">GRAFTON.</li>
+  <li class="add2em smaller">BEDFORD.</li>
+<li class="ftsize110 martop1">MARQUESS:&mdash;</li>
+  <li class="add2em smaller">GRANBY.</li>
+<li class="ftsize110 martop1">EARLS:&mdash;</li>
+  <li class="add2em smaller">BUTE.</li>
+  <li class="add2em smaller">TEMPLE.</li>
+  <li class="add2em smaller">SANDWICH.</li>
+  <li class="add2em smaller">EGREMONT.</li>
+  <li class="add2em smaller">HALIFAX.</li>
+  <li class="add2em smaller">HARDWICKE.</li>
+  <li class="add2em smaller">CHATHAM.</li>
+  <li class="add2em smaller">MANSFIELD.</li>
+  <li class="add2em smaller">NORTHINGTON.</li>
+  <li class="add2em smaller">SUFFOLK.</li>
+  <li class="add2em smaller">HILLSBOROUGH.</li>
+  <li class="add2em smaller">HERTFORD.</li>
+<li class="ftsize110 martop1">LORDS:&mdash;</li>
+  <li class="add2em smaller">LYTTLETON.</li>
+  <li class="add2em smaller">CAMDEN.</li>
+  <li class="add2em smaller">HOLLAND.</li>
+  <li class="add2em smaller">CLIVE.</li>
+  <li class="add2em smaller">GEORGE SACKVILLE.</li>
+<li class="add6em">&mdash;&mdash;</li>
+  <li class="add2em smaller">MARSHAL CONWAY.</li>
+  <li class="add2em smaller">HORACE WALPOLE (EARL OF ORFORD).</li>
+  <li class="add2em smaller">EDMUND BURKE.</li>
+  <li class="add2em smaller">GEORGE GRENVILLE.</li>
+  <li class="add2em smaller">JOHN WILKES.</li>
+  <li class="add2em smaller">WILLIAM GERARD HAMILTON.</li>
+  <li class="add2em smaller">AUGUSTUS HERVEY.</li>
+  <li class="add2em smaller">MR. JENKINSON (first EARL OF LIVERPOOL).</li>
+  <li class="add2em smaller">MR. WHATELY.</li>
+  <li class="add2em smaller">MR. WEDDERBURN (EARL OF ROSLYN).</li>
+  <li class="add2em smaller">MR. CHARLES YORKE.</li>
+  <li class="add2em smaller">MR. HANS STANLEY.</li>
+  <li class="add2em smaller">MR. CHARLES TOWNSEND.</li>
+  <li class="add2em smaller">MR. CALCRAFT.</li>
+  <li class="add2em smaller">MR. RIGBY.</li>
+  <li class="add2em smaller">MR. KNOX.</li>
+  <li class="add2em smaller">MR. CHARLES LLOYD.</li>
+</ul>
+
+<div class="center1">
+<p class="ftsize50 martop1">AND THE</p>
+<p class="ftsize115"><i>AUTHOR OF THE LETTERS OF JUNIUS</i>.</p>
+<p class="ftsize50">INCLUDING ALSO,</p>
+<p class="ftsize115 hweight">Mr. Grenville's Diary of Political Events;</p>
+<p class="ftsize95">PARTICULARLY DURING THE PERIOD OF HIS ADMINISTRATION AS FIRST LORD
+OF THE TREASURY, FROM 1763 TO 1765.</p>
+<p class="ftsize104">EDITED BY WILLIAM JAMES SMITH, <span class="smcap">Esq</span>.</p>
+<p class="ftsize85">8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Personal Narrative of an Englishman Domesticated
+in Abyssinia.</p>
+<p class="ftsize104">BY MANSFIELD PARKYNS, <span class="smcap">Esq</span>.</p>
+<p class="ftsize85">With <span class="wosp05">Illustrations. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2"><span class="pagenum1"><a id="pageK"></a>[p.K]</span>Lives of the Three Devereux, Earls of Essex,</p>
+<p class="ftsize50"><span class="smcap">From 1540 to 1646.</span></p>
+<p class="ftsize95">1. THE EARL MARSHALL OF IRELAND.&mdash;2. THE FAVOURITE.&mdash;3. THE GENERAL OF
+THE PARLIAMENT.</p>
+<p class="ftsize50">FOUNDED UPON LETTERS AND DOCUMENTS CHIEFLY UNPUBLISHED.</p>
+<p class="ftsize104">BY THE HON. CAPTAIN DEVEREUX, R.N.</p>
+<p class="ftsize85">2 <span class="wosp05">Vols. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">The Present State of the Republic of the Rio de la
+Plata (Buenos Ayres).</p>
+<p class="ftsize95">ITS GEOGRAPHY, RESOURCES, STATISTICS, COMMERCE, DEBT, ETC., DESCRIBED.</p>
+<p class="ftsize50">WITH THE HISTORY OF THE CONQUEST OF THE COUNTRY BY THE SPANIARDS.</p>
+<p class="ftsize104">BY SIR WOODBINE PARISH, F.R.S., K.C.H, F.G.S.,</p>
+<p class="ftsize85">Formerly Her Majesty's Consul General and Charg� d' Affaires at Buenos Ayres.</p>
+<p class="ftsize85">With New Map and <span class="wosp05">Illustrations. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Contrasts of Foreign and English Society;</p>
+<p class="ftsize95">OR, RECORDS AND RECOLLECTIONS OF A RESIDENCE IN VARIOUS PARTS
+OF THE CONTINENT AND ENGLAND.</p>
+<p class="ftsize104">BY MRS. AUSTIN.</p>
+<p class="ftsize85">2 <span class="wosp05">Vols. Post</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">The Hand;</p>
+<p class="ftsize95">ITS MECHANISM AND ENDOWMENTS, AS EVINCING DESIGN.</p>
+<p class="ftsize104">BY THE LATE SIR CHARLES BELL.</p>
+<p class="ftsize85"><i>A New Edition.</i><span class="wosp05"> Woodcuts. Post</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Naval and Military Technological Dictionary.</p>
+<p class="ftsize95">ENGLISH AND FRENCH.&mdash;FRENCH AND ENGLISH.</p>
+<p class="ftsize50">FOR THE USE OF SOLDIERS, SAILORS, AND ENGINEERS.</p>
+<p class="ftsize104">BY COLONEL BURN, <span  class="ftsize85">Assistant Inspector of Artillery.</span></p>
+<p class="ftsize85">Small 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2"><span class="pagenum1"><a id="pageL"></a>[p.L]</span>The Life and Reminiscences of Thomas Stothard, R.A.</p>
+<p class="ftsize104">BY MRS. BRAY.</p>
+<p class="ftsize85">With numerous Illustrations from his Chief Works, drawn on Wood by <span class="smcap">G. Scharf</span>, Jun., and printed
+in a novel and beautiful style.</p>
+<p class="ftsize85">With a <span class="wosp05">Portrait. Small</span> 4to.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Life and Works of Alexander Pope.</p>
+<p class="ftsize95">EDITED WITH NOTES.</p>
+<p class="ftsize104">BY THE RIGHT HON. JOHN WILSON CROKER.</p>
+<p class="ftsize85"><span class="wosp05">Portraits. 4</span> <span class="wosp05">vols. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Dictionary of Greek and Roman Geography.</p>
+<p class="ftsize104">BY WILLIAM SMITH, LL.D.</p>
+<p class="ftsize85">With an Historical <span class="wosp05">Atlas. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">A Church Dictionary.</p>
+<p class="ftsize104">BY WALTER FARQUHAR HOOK, D.D., Vicar of Leeds.</p>
+<p class="ftsize85"><i>Sixth Edition</i>, revised and <span class="wosp05">enlarged. One</span> <span class="wosp05">Volume. 8vo.</span></p>
+</div>
+
+<p>"In this edition, besides the addition of many new articles, all those
+relating to important Doctrinal and Liturgical Subjects have been enlarged.
+The authorities on which statements have been made, are given, with copious
+extracts from the works of our Standard Divines. Special reference has been
+made to the Romish Controversy. Attention has also been paid to the
+subjects of Ecclesiastical and Civil Law, and to the Statute Law of England
+in Church Matters."&mdash;<i>Extract from the Preface.</i></p>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">History of Ancient Pottery;</p>
+<p class="ftsize95">EGYPTIAN, ASIATIC, GREEK, ROMAN, ETRUSCAN, AND CELTIC.</p>
+<p class="ftsize104">BY SAMUEL BIRCH, F.S.A.</p>
+<p class="ftsize85">Assistant Keeper of the Antiquities in the British Museum.</p>
+<p class="ftsize85">With <span class="wosp05">Illustrations. 8vo.</span></p>
+<p class="ftsize50"><span class="smcap">Uniform with</span> "MARRYAT'S MODERN POTTERY AND PORCELAIN."</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">A Sketch of Madeira in 1850.</p>
+<p class="ftsize104">BY EDWARD VERNON HARCOURT.</p>
+<p class="ftsize95">A HANDBOOK FOR THE USE OF TRAVELLERS OR INVALIDS VISITING THE ISLAND.</p>
+<p class="ftsize85">With a Map and <span class="wosp05">Woodcuts. Post</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2"><span class="pagenum1"><a id="pageM"></a>[p.M]</span>The History of Herodotus.</p>
+<p class="ftsize50">A NEW ENGLISH VERSION. TRANSLATED FROM THE TEXT OF GAISFORD, AND EDITED</p>
+<p class="ftsize104">BY REV. GEORGE RAWLINSON, M.A., <span class="ftsize95">Exeter College, Oxford.</span></p>
+<p class="ftsize50">ASSISTED BY</p>
+<p class="ftsize104">COLONEL RAWLINSON, C.B., AND SIR J. G. WILKINSON, F.R.S.,</p>
+<p class="ftsize95">WITH COPIOUS NOTES AND APPENDICES, ILLUSTRATING THE HISTORY AND GEOGRAPHY OF
+HERODOTUS, FROM THE MOST RECENT SOURCES OF INFORMATION,</p>
+<p class="ftsize50">EMBODYING THE CHIEF RESULTS, HISTORICAL AND ETHNOGRAPHICAL, WHICH HAVE BEEN ARRIVED AT
+IN THE PROGRESS OF CUNEIFORM AND HIEROGLYPHICAL DISCOVERY.</p>
+<p class="ftsize85">4 <span class="wosp05">Vols. 8vo.</span></p>
+</div>
+
+<p>The translation itself has been undertaken from a conviction of the entire
+inadequacy of any existing version to the wants of the time. The gross
+unfaithfulness of Beloe, and the extreme unpleasantness of his style,
+render his translation completely insufficient in an age which dislikes
+affectation and requires accuracy; while the only other complete English
+versions which exist are at once too close to the original to be perused
+with any pleasure by the general reader, and also defective in respect of
+scholarship.</p>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">A Treatise on Naval Gunnery,</p>
+<p class="ftsize95">FOR THE USE OF OFFICERS AND FOR THE TRAINING OF SEAMEN GUNNERS.</p>
+<p class="ftsize95">WITH DESCRIPTIONS OF THE GUNS INTRODUCED SINCE THE LATE WAR.</p>
+<p class="ftsize104">BY LIEUT.-GEN. SIR HOWARD DOUGLAS, <span class="smcap">Bart.</span>, G.C.B.</p>
+<p class="ftsize85"><i>Third Edition</i>, <span class="wosp05">revised. Plates. 8vo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Considerations on Steam Warfare and Naval
+Shell-Firing;</p>
+<p class="ftsize104">BY LIEUT.-GEN. SIR HOWARD DOUGLAS, BART.</p>
+<p class="ftsize85">8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Letters and Journals of General Sir Hudson Lowe,</p>
+<p class="ftsize95">REVEALING THE TRUE HISTORY OF NAPOLEON AT ST. HELENA.</p>
+<p class="ftsize50">PARTLY COMPILED AND ARRANGED</p>
+<p class="ftsize104">BY THE LATE SIR NICHOLAS HARRIS NICOLAS.</p>
+<p class="ftsize85">With <span class="wosp05">Portrait. 3</span> <span class="wosp05">Vols. 8vo.</span></p>
+</div>
+
+<p>"From these papers the world will at last learn, as it ought long ago to
+have learnt, the <i>truth</i>, and the <i>whole truth</i>, respecting the captivity
+of Napoleon."&mdash;<i>Quarterly Review.</i></p>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2"><span class="pagenum1"><a id="pageN"></a>[p.N]</span>Home Sermons;</p>
+<p class="ftsize95">OR, SERMONS WRITTEN FOR SUNDAY READING IN FAMILIES.</p>
+<p class="ftsize104">BY REV. JOHN PENROSE, M.A.,</p>
+<p class="ftsize85">8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">History of Greece for Schools.</p>
+<p class="ftsize95">ON THE PLAN OF "MRS. MARKHAM'S HISTORIES."</p>
+<p class="ftsize85">With <span class="wosp05">Woodcuts. Post</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">State Papers of Henry the Eighth's Reign,</p>
+<p class="ftsize95">COMPRISING THE CORRESPONDENCE BETWEEN THE ENGLISH GOVERNMENT AND
+THE CONTINENTAL POWERS,</p>
+<p class="ftsize50">FROM THE PERIOD OF THE ELECTION OF CHARLES V. TO THE DEATH OF HENRY VIII.</p>
+<p class="ftsize85">With <span class="wosp05">Indexes. Vols.</span> <span class="wosp05">VI-XI. 4to.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">The Official Handbook.</p>
+<p class="ftsize95">BEING A MANUAL OF HISTORICAL AND POLITICAL REFERENCE FOR ALL CLASSES.</p>
+<p class="ftsize85">One <span class="wosp05">Volume. Fcap.</span> 8vo.</p>
+</div>
+
+<p>The design of this Work is to show concisely the machinery by which the
+<span class="smcap">Government</span> of the country is carried on, giving such a succinct account of
+the duties, emoluments, and authorities of the various <span class="smcap">Public Departments</span>,
+with their political relations, as will, it is hoped, render the volume a
+useful manual of reference to all strangers and Foreigners desirous to make
+themselves acquainted with British Institutions.</p>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">The British Museum;</p>
+<p class="ftsize95">HANDBOOK TO THE ANTIQUITIES AND SCULPTURE THERE.</p>
+<p class="ftsize104">BY W. S. W. VAUX, M.A., F.S.A.,</p>
+<p class="ftsize75">Assistant in the Department of Antiquities in the British Museum.</p>
+<p class="ftsize85">With <span class="wosp05">Woodcuts. Post</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2"><span class="pagenum1"><a id="pageO"></a>[p.O]</span>Handbook of Chronology.</p>
+<p class="ftsize95">ALPHABETICALLY ARRANGED TO FACILITATE REFERENCE.</p>
+<p class="ftsize85">One Volume, 8vo.</p>
+</div>
+
+<p>This work will enable the student or general reader, or man of the world,
+to put his finger at once upon the date of any particular event by means of
+a careful <i>alphabetical</i> classified arrangement of the various elaborate
+chronologies which have been given to the world. It has been prepared with
+such care as will render it&mdash;it is hoped&mdash;a trustworthy book of reference.</p>
+
+<p class="martopm05">It contains the dates of the events which mark the rise, progress, decline,
+and fall of states; and the changes in the fortunes of nations. Alliances,
+wars, battles, sieges, and treaties of peace; geographical discoveries, the
+settlement of colonies, and their subsequent story;&mdash;with all occurrences
+of general historic interest&mdash;are recorded in it. It further includes the
+years of the leading incidents in the lives of men eminent for worth,
+knowledge, rank, or fame; and of the writings, &amp;c., &amp;c., by which they are
+chiefly known; discoveries in every department of science; and inventions
+and improvements, mechanical, social, domestic, and economical.</p>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Handbook for Syria and the Holy Land.</p>
+<p class="ftsize85">With <span class="wosp05">Maps. Post</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<p class="center1 ftsize115 hweight martop2">Handbook for England and Wales;</p>
+
+<p>Giving an account of the <span class="smcap">Places</span> and <span class="smcap">Objects</span> best worth visiting in England,
+more especially those rendered interesting by Historical Associations, or
+likely to attract the notice of intelligent strangers and passing
+travellers; arranged in connexion with the most frequented Roads and
+Railways in England. Showing, at the same time, the way of seeing them to
+the best advantage, with the least expenditure of time and money.</p>
+
+<p class="center1"><i>This work will appear in portions, as follows</i>:&mdash;</p>
+
+<ul class="lihei1 add2em ftsize95 min3em">
+<li><span class="smcap">Part I.&mdash;The Eastern Counties; including Essex, Suffolk, Norfolk,
+Cambridge, and Lincoln.</span><span class="wosp05"> (</span><i>Nearly Ready.</i>)</li>
+<li><span class="smcap">Part II.&mdash;Midland Counties; Herts, Bedford, Northampton, Leicester, Bucks,
+Nottinghamshire.</span></li>
+<li><span class="smcap">Part III.&mdash;Derbyshire and Yorkshire.</span></li>
+<li><span class="smcap">Part IV.&mdash;Durham, Northumberland, Staffordshire, Cheshire, Lancashire,
+Cumberland, the Lakes.</span></li>
+<li><span class="smcap">Part V.&mdash;Berks, Bucks, Oxfordshire, Warwick, Gloucester, Worcester,
+Hereford, Shropshire, Cheshire.</span></li>
+<li><span class="smcap">Part VI.&mdash;North and South Wales.</span></li>
+<li><span class="smcap">Part VII.&mdash;Devon and Cornwall.</span><span class="wosp05"> (</span>Ready.)</li>
+<li><span class="smcap">Part VIII.&mdash;Somerset, Wilts, Dorset.</span></li>
+<li><span class="smcap">Part IX.&mdash;Hampshire, Isle of Wight, Sussex, Surrey, Kent.</span></li>
+</ul>
+
+<div class="center1">
+<p class="ftsize50 martop05">ALSO,</p>
+<p class="ftsize115">A CONDENSED HANDBOOK OF ALL ENGLAND</p>
+<p class="ftsize95">IN ONE VOLUME.</p>
+<p class="ftsize85">With Map and <span class="wosp05">Plans. Post</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2"><span class="pagenum1"><a id="pageP"></a>[p.P]</span>Handbook of Architecture.</p>
+<p class="ftsize95">BEING A CONCISE AND POPULAR ACCOUNT OF THE DIFFERENT STYLES PREVAILING
+IN ALL AGES AND COUNTRIES OF THE WORLD.</p>
+<p class="ftsize50">WITH A DESCRIPTION OF THE MOST REMARKABLE BUILDINGS.</p>
+<p class="ftsize104">BY JAMES FERGUSSON, <span class="smcap">Esq.</span>,</p>
+<p class="ftsize85">Author of "Indian Architecture," "Palaces of Nineveh and Persepolis Restored."</p>
+<p class="ftsize85">With very numerous Illustrations on <span class="wosp05">Wood. 8vo.</span></p>
+<p class="ftsize85">Uniform with "<span class="smcap">Kugler's Handbook of Painting</span>."</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Handbook to the Cathedrals of England.</p>
+<p class="ftsize95">CONTAINING A SHORT DESCRIPTION OF EACH.</p>
+<p class="ftsize104">BY THE REV. G. A. POOLE, M.A., <span class="ftsize85">Vicar of Welford.</span></p>
+<p class="ftsize85">With Illustrative <span class="wosp05">Woodcuts. Small</span> 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Handbook for the Environs of London;</p>
+<p class="ftsize95">WITH HINTS FOR EXCURSIONS BY RAIL&mdash;RIVER&mdash;AND ROAD.</p>
+<p class="ftsize104">BY PETER CUNNINGHAM, F.S.A.</p>
+<p class="ftsize85">Post 8vo.</p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">Handbook of Modern London;</p>
+<p class="ftsize95">OR, LONDON AS IT IS.</p>
+<p class="ftsize50">GIVING FULL DESCRIPTIONS OF ALL PLACES AND OBJECTS OF INTEREST IN THE
+METROPOLIS AND ITS VICINITY.</p>
+<p class="ftsize85">With a Clue-Map of London, Plans, <span class="wosp05">&amp;c. 18mo.</span></p>
+</div>
+
+<hr class="sep3">
+
+<div class="center1">
+<p class="ftsize115 hweight martop2">A Popular Account of Nineveh and its Remains.</p>
+<p class="ftsize104">BY AUSTEN H. LAYARD, D.C.L.</p>
+<p class="ftsize95">ABRIDGED AND CONDENSED FROM HIS LARGER WORK.</p>
+<p class="ftsize85">With Numerous <span class="wosp05">Woodcuts. Post</span> 8vo.</p>
+</div>
+
+<hr>
+
+<p class="center1 ftsize50">BRADBURY AND EVANS, PRINTERS, WHITEFRIARS.</p>
+
+
+<hr class="sep2">
+<h5>FOOTNOTES:</h5>
+
+<div class="footnote indent03">
+<p><a name="Footnote_A_1" id="Footnote_A_1"></a><a href="#FNanchor_A_1"><span class="label">v-A</span></a> Postscript to 4th edition of the Manual, price 6<i>d.</i></p>
+
+<p><a name="Footnote_A_2" id="Footnote_A_2"></a><a href="#FNanchor_A_2"><span class="label">vi-A</span></a> As it is impossible to enable the reader to recognize rocks and
+minerals at sight by aid of verbal descriptions or figures, he will do well
+to obtain a well-arranged collection of specimens, such as may be procured
+from Mr. Tennant (149. Strand), teacher of Mineralogy at King's College,
+London.</p>
+
+<p><a name="Footnote_B_1" id="Footnote_B_1"></a><a href="#FNanchor_B_1"><span class="label">vii-A</span></a> Travels in North America by the Author, vol. ii. chap. 22.</p>
+
+<p><a name="Footnote_B_2" id="Footnote_B_2"></a><a href="#FNanchor_B_2"><span class="label">vii-B</span></a> Ibid. 1842.</p>
+
+<p><a name="Footnote_B_3" id="Footnote_B_3"></a><a href="#FNanchor_B_3"><span class="label">viii-A</span></a> Quart. Journ. Geol. Soc. 1851, vol. vii. p. 250.</p>
+
+<p><a name="Footnote_B_4" id="Footnote_B_4"></a><a href="#FNanchor_B_4"><span class="label">ix-A</span></a> The generally received determination of the age of this rock is
+probably correct; but as there are no overlying coal-measures and no
+well-known Devonian fossils in the whitish stone of Elgin, and as I have
+not personally explored the geology of that district, I cannot speak as
+confidently as in regard to the age of the Montreal Chelonian.</p>
+
+<p><a name="Footnote_B_5" id="Footnote_B_5"></a><a href="#FNanchor_B_5"><span class="label">xii-A</span></a> H. D. Rogers, Proceedings of Amer. Assoc. of Science, Albany, 1851.</p>
+
+<p><a name="Footnote_B_6" id="Footnote_B_6"></a><a href="#FNanchor_B_6"><span class="label">xii-B</span></a> See Memoir by the Author, Quart. Journ. Geol. Soc., vol. vii. p.
+240.</p>
+
+<p><a name="Footnote_B_7" id="Footnote_B_7"></a><a href="#FNanchor_B_7"><span class="label">xiii-A</span></a> W�rtembergisch. Naturwissen. Jahreshefte, 3 Jahr. Stuttgart, 1847.</p>
+
+<p><a name="Footnote_B_8" id="Footnote_B_8"></a><a href="#FNanchor_B_8"><span class="label">xiii-B</span></a> Nov. Act. Acad. C�sar. Leopold. Nat. Cur. 1850, p. 902. For
+figures, see ibid. plate xxi. figs. 14, 15, 16, 17.</p>
+
+<p><a name="Footnote_B_9" id="Footnote_B_9"></a><a href="#FNanchor_B_9"><span class="label">xiv-A</span></a> See Manual, <a href="#page268">p. 268.</a></p>
+
+<p><a name="Footnote_B_10" id="Footnote_B_10"></a><a href="#FNanchor_B_10"><span class="label">xv-A</span></a> Manual, <a href="#page289">p. 289.</a></p>
+
+<p><a name="Footnote_B_11" id="Footnote_B_11"></a><a href="#FNanchor_B_11"><span class="label">xv-B</span></a> Ibid. <a href="#page268">p. 268.</a></p>
+
+<p><a name="Footnote_B_12" id="Footnote_B_12"></a><a href="#FNanchor_B_12"><span class="label">xvi-A</span></a> For Terminology, see Note, p. 223.</p>
+
+<p><a name="Footnote_B_13" id="Footnote_B_13"></a><a href="#FNanchor_B_13"><span class="label">xvi-B</span></a> Quart. Journ. vol. vii. Memoirs, p. 111.</p>
+
+<p><a name="Footnote_B_14" id="Footnote_B_14"></a><a href="#FNanchor_B_14"><span class="label">xvii-A</span></a> Principles, 1st ed. chaps. v. and ix.</p>
+
+<p><a name="Footnote_B_15" id="Footnote_B_15"></a><a href="#FNanchor_B_15"><span class="label">xvii-B</span></a> Ibid. p. 153.</p>
+
+<p><a name="Footnote_B_16" id="Footnote_B_16"></a><a href="#FNanchor_B_16"><span class="label">xxi-A</span></a> Preface to 5th ed. of Studies of University of Cambridge.</p>
+
+<p><a name="Footnote_B_17" id="Footnote_B_17"></a><a href="#FNanchor_B_17"><span class="label">xxii-A</span></a> Principles, 4th ed. 1835, vol. i. p. 231, and vol. i. chap. 9.
+subsequent ed.</p>
+
+<p><a name="Footnote_B_18" id="Footnote_B_18"></a><a href="#FNanchor_B_18"><span class="label">xxii-B</span></a> In my Anniversary Address, for 1851, to the Geological Society,
+the reader will find a full discussion of the facts and arguments which
+bear on the theory of progressive development.&mdash;Quart. Journ. Geol. Soc.,
+vol. vii.</p>
+
+<p><a name="Footnote_C_1" id="Footnote_C_1"></a><a href="#FNanchor_C_1"><span class="label">3-A</span></a> See Principles of Geology, by the Author, Index, "Nile," "Rivers,"
+&amp;c.</p>
+
+<p><a name="Footnote_C_2" id="Footnote_C_2"></a><a href="#FNanchor_C_2"><span class="label">4-A</span></a> See <a href="#page18">p. 18.</a></p>
+
+<p><a name="Footnote_C_3" id="Footnote_C_3"></a><a href="#FNanchor_C_3"><span class="label">4-B</span></a> See Geograph. Journ. vol. iv. p. 64.</p>
+
+<p><a name="Footnote_D_1" id="Footnote_D_1"></a><a href="#FNanchor_D_1"><span class="label">11-A</span></a> The kaolin of China consists of 71�15 parts of silex, 15�86 of
+alumine, 1�92 of lime, and 6�73 of water (W. Phillips, Mineralogy, p. 33.);
+but other porcelain clays differ materially, that of Cornwall being
+composed, according to Boase of nearly equal parts of silica and alumine,
+with 1 per cent. of magnesia. (Phil. Mag. vol. x. 1837.)</p>
+
+<p><a name="Footnote_D_2" id="Footnote_D_2"></a><a href="#FNanchor_D_2"><span class="label">11-B</span></a> See W. Phillips's Mineralogy, "Alumine."</p>
+
+<p><a name="Footnote_D_3" id="Footnote_D_3"></a><a href="#FNanchor_D_3"><span class="label">14-A</span></a> Consult Index to Principles of Geology, "Stratification,"
+"Currents," "Deltas," "Water," &amp;c.</p>
+
+<p><a name="Footnote_D_4" id="Footnote_D_4"></a><a href="#FNanchor_D_4"><span class="label">21-A</span></a> Siau. Edin. New Phil. Journ. vol. xxxi.; and Darwin, Volc. Islands,
+p. 134.</p>
+
+<p><a name="Footnote_E_1" id="Footnote_E_1"></a><a href="#FNanchor_E_1"><span class="label">28-A</span></a> See Synoptic Table in Blainville's Malacologie.</p>
+
+<p><a name="Footnote_E_2" id="Footnote_E_2"></a><a href="#FNanchor_E_2"><span class="label">29-A</span></a> Gray, Phil. Trans., 1835, p. 302.</p>
+
+<p><a name="Footnote_E_3" id="Footnote_E_3"></a><a href="#FNanchor_E_3"><span class="label">31-A</span></a> For figures of recent species, see below, <a href="#page183">p. 183.</a>, and figs. of
+fossils, see <a href="#page228">p. 228.</a></p>
+
+<p><a name="Footnote_E_4" id="Footnote_E_4"></a><a href="#FNanchor_E_4"><span class="label">32-A</span></a> See Index of Principles, "Fossilization."</p>
+
+<p><a name="Footnote_E_5" id="Footnote_E_5"></a><a href="#FNanchor_E_5"><span class="label">33-A</span></a> See Principles, Index, "Lym-Fiord."</p>
+
+<p><a name="Footnote_E_6" id="Footnote_E_6"></a><a href="#FNanchor_E_6"><span class="label">33-B</span></a> See below, Chap. XVIII., on the Wealden.</p>
+
+<p><a name="Footnote_F_1" id="Footnote_F_1"></a><a href="#FNanchor_F_1"><span class="label">34-A</span></a> See Principles, Index, "Calcareous Springs," &amp;c.</p>
+
+<p><a name="Footnote_F_2" id="Footnote_F_2"></a><a href="#FNanchor_F_2"><span class="label">34-B</span></a> Ibid. "Travertin," "Coral Reefs," &amp;c.</p>
+
+<p><a name="Footnote_F_3" id="Footnote_F_3"></a><a href="#FNanchor_F_3"><span class="label">35-A</span></a> Report Brit. Ass. 1843, p. 178.</p>
+
+<p><a name="Footnote_F_4" id="Footnote_F_4"></a><a href="#FNanchor_F_4"><span class="label">36-A</span></a> Dr. MacCulloch, Syst. of Geol. vol. i. p. 123.</p>
+
+<p><a name="Footnote_F_5" id="Footnote_F_5"></a><a href="#FNanchor_F_5"><span class="label">36-B</span></a> Princ. of Geol., Index, "Superior Lake."</p>
+
+<p><a name="Footnote_F_6" id="Footnote_F_6"></a><a href="#FNanchor_F_6"><span class="label">37-A</span></a> De la Beche, Geol. Researches, p. 95., and Geol. Observer (1851), p.
+686.</p>
+
+<p><a name="Footnote_F_7" id="Footnote_F_7"></a><a href="#FNanchor_F_7"><span class="label">41-A</span></a> Vol. i. p. 399. first series.</p>
+
+<p><a name="Footnote_F_8" id="Footnote_F_8"></a><a href="#FNanchor_F_8"><span class="label">41-B</span></a> Piddington, Asiat. Research. vol. xviii. p. 226.</p>
+
+<p><a name="Footnote_F_9" id="Footnote_F_9"></a><a href="#FNanchor_F_9"><span class="label">42-A</span></a> Jam. Ed. New Phil. Journ. No. 30. p. 246.</p>
+
+<p><a name="Footnote_F_10" id="Footnote_F_10"></a><a href="#FNanchor_F_10"><span class="label">43-A</span></a> Stokes, Geol. Trans., vol. v. p. 212. second series.</p>
+
+<p><a name="Footnote_F_11" id="Footnote_F_11"></a><a href="#FNanchor_F_11"><span class="label">43-B</span></a> Ibid.</p>
+
+<p><a name="Footnote_G_1" id="Footnote_G_1"></a><a href="#FNanchor_G_1"><span class="label">46-A</span></a> In the first three editions of my Principles of Geology, I expressed
+many doubts as to the validity of the alleged proofs of a gradual rise of
+land in Sweden; but after visiting that country, in 1834, I retracted these
+objections, and published a detailed statement of the observations which
+led me to alter my opinion in the Phil. Trans. 1835, Part I. See also the
+Principles, 4th and subsequent editions.</p>
+
+<p><a name="Footnote_G_2" id="Footnote_G_2"></a><a href="#FNanchor_G_2"><span class="label">46-B</span></a> See his Journal of a Naturalist in Voyage of the Beagle, and his
+work on Coral Reefs.</p>
+
+<p><a name="Footnote_G_3" id="Footnote_G_3"></a><a href="#FNanchor_G_3"><span class="label">46-C</span></a> See chapters xxviii. to xxxi. inclusive.</p>
+
+<p><a name="Footnote_G_4" id="Footnote_G_4"></a><a href="#FNanchor_G_4"><span class="label">48-A</span></a> Edin. Trans. vol. vii. pl. 3.</p>
+
+<p><a name="Footnote_G_5" id="Footnote_G_5"></a><a href="#FNanchor_G_5"><span class="label">50-A</span></a> Proceedings of Geol. Soc. vol. iii. p. 148.</p>
+
+<p><a name="Footnote_G_6" id="Footnote_G_6"></a><a href="#FNanchor_G_6"><span class="label">53-A</span></a> See plan by M. Chevalier, Burat's D'Aubuisson, tom. ii. p. 334.</p>
+
+<p><a name="Footnote_G_7" id="Footnote_G_7"></a><a href="#FNanchor_G_7"><span class="label">55-A</span></a> See M. Thurmann's work, "Essai sur les Soul�vemens Jurassiques du
+Porrentruy, Paris, 1832," with whom I examined part of these mountains in
+1835.</p>
+
+<p><a name="Footnote_G_8" id="Footnote_G_8"></a><a href="#FNanchor_G_8"><span class="label">57-A</span></a> I am indebted to the kindness of T. Sopwith, Esq., for three models
+which I have copied in the above diagrams; but the beginner may find it by
+no means easy to understand such copies, although, if he were to examine
+and handle the originals, turning them about in different ways, he would at
+once comprehend their meaning as well as the import of others far more
+complicated, which the same engineer has constructed to illustrate
+<i>faults</i>.</p>
+
+<p><a name="Footnote_G_9" id="Footnote_G_9"></a><a href="#FNanchor_G_9"><span class="label">60-A</span></a> Biographical account of Dr. Hutton.</p>
+
+<p><a name="Footnote_G_10" id="Footnote_G_10"></a><a href="#FNanchor_G_10"><span class="label">60-B</span></a> See above, p. 49. and section.</p>
+
+<p><a name="Footnote_G_11" id="Footnote_G_11"></a><a href="#FNanchor_G_11"><span class="label">60-C</span></a> Playfair, ibid.; see his Works, Edin. 1822, vol. iv. p. 81.</p>
+
+<p><a name="Footnote_G_12" id="Footnote_G_12"></a><a href="#FNanchor_G_12"><span class="label">62-A</span></a> Playfair, Illust. of Hutt. Theory, � 42.</p>
+
+<p><a name="Footnote_G_13" id="Footnote_G_13"></a><a href="#FNanchor_G_13"><span class="label">62-B</span></a> Geol. Trans. second series, vol. v. p. 452.</p>
+
+<p><a name="Footnote_G_14" id="Footnote_G_14"></a><a href="#FNanchor_G_14"><span class="label">64-A</span></a> Conybeare and Phillips, Outlines, &amp;c. p. 376.</p>
+
+<p><a name="Footnote_G_15" id="Footnote_G_15"></a><a href="#FNanchor_G_15"><span class="label">64-B</span></a> Phillips, Geology, Lardner's Cyclop. p. 41.</p>
+
+<p><a name="Footnote_G_16" id="Footnote_G_16"></a><a href="#FNanchor_G_16"><span class="label">65-A</span></a> See the results of the "Geological Survey of Great Britain;"
+Memoirs, vols. i. and ii., by Sir H. De la Beche, Mr. A. C. Ramsay, and Mr.
+John Phillips.</p>
+
+<p><a name="Footnote_H_1" id="Footnote_H_1"></a><a href="#FNanchor_H_1"><span class="label">67-A</span></a> Western Islands, vol. ii. p. 93. pl. 31. fig. 4.</p>
+
+<p><a name="Footnote_H_2" id="Footnote_H_2"></a><a href="#FNanchor_H_2"><span class="label">69-A</span></a> See Mammat's Geological Facts, &amp;c. p. 90. and plate.</p>
+
+<p><a name="Footnote_H_3" id="Footnote_H_3"></a><a href="#FNanchor_H_3"><span class="label">69-B</span></a> Conybeare's Report to Brit. Assoc. 1842, p. 381.</p>
+
+<p><a name="Footnote_H_4" id="Footnote_H_4"></a><a href="#FNanchor_H_4"><span class="label">70-A</span></a> Prestwich, Geol. Trans. second series, vol. v. pp. 452. 473.</p>
+
+<p><a name="Footnote_H_5" id="Footnote_H_5"></a><a href="#FNanchor_H_5"><span class="label">75-A</span></a> Section given by Dr. Christie, Edin. New Phil. Journ. No. xxiii.,
+called by mistake the Cave of Mardolce, by the late M. Hoffmann. See
+account by Mr. S. P. Pratt, F. G. S. Proceedings of Geol. Soc. No. 32.
+1833.</p>
+
+<p><a name="Footnote_H_6" id="Footnote_H_6"></a><a href="#FNanchor_H_6"><span class="label">78-A</span></a> I was directed by M. Deshayes to this spot, which I visited in June,
+1833.</p>
+
+<p><a name="Footnote_H_7" id="Footnote_H_7"></a><a href="#FNanchor_H_7"><span class="label">78-B</span></a> See Trans. of Geol. Soc., second series, vol. v. plate v.</p>
+
+<p><a name="Footnote_I_1" id="Footnote_I_1"></a><a href="#FNanchor_I_1"><span class="label">82-A</span></a> Trimmer, Proceedings of Geol. Soc. vol. iv. p. 7. 1842.</p>
+
+<p><a name="Footnote_I_2" id="Footnote_I_2"></a><a href="#FNanchor_I_2"><span class="label">83-A</span></a> See Lyell on Sand-pipes, &amp;c., Phil. Mag., third series, vol. xv. p.
+257., Oct. 1839.</p>
+
+<p><a name="Footnote_I_3" id="Footnote_I_3"></a><a href="#FNanchor_I_3"><span class="label">84-A</span></a> Principles of Geology, 7th ed. p. 506., 8th ed. 509.</p>
+
+<p><a name="Footnote_I_4" id="Footnote_I_4"></a><a href="#FNanchor_I_4"><span class="label">85-A</span></a> Second Visit to the U. S. vol. ii. chap. 34.</p>
+
+<p><a name="Footnote_I_5" id="Footnote_I_5"></a><a href="#FNanchor_I_5"><span class="label">88-A</span></a> "Ancient Sea Margins," p. 114., by R. Chambers.</p>
+
+<p><a name="Footnote_J_1" id="Footnote_J_1"></a><a href="#FNanchor_J_1"><span class="label">91-A</span></a> See Principles, vol. i. chap. iv.</p>
+
+<p><a name="Footnote_K_1" id="Footnote_K_1"></a><a href="#FNanchor_K_1"><span class="label">103-A</span></a> For tertiary, Sir H. De la Beche has used the term
+"supracretaceous," a name implying that the strata so called are superior
+in position to the chalk.</p>
+
+<p><a name="Footnote_K_2" id="Footnote_K_2"></a><a href="#FNanchor_K_2"><span class="label">103-B</span></a> Professor Phillips has adopted these terms: Cainozoic, from
+&#954;&#945;&#953;&#957;&#959;&#962;, <i>cainos</i>, recent, and &#950;&#969;&#959;&#957;, <i>zoon</i>, animal; Mesozoic,
+from &#956;&#949;&#963;&#959;&#962;, <i>mesos</i>, middle, &amp;c.; Paleozoic, from
+&#960;&#945;&#955;&#945;&#953;&#959;&#962;, <i>palaios</i>, ancient, &amp;c.</p>
+
+<p><a name="Footnote_K_3" id="Footnote_K_3"></a><a href="#FNanchor_K_3"><span class="label">103-C</span></a> Professor Phillips has adopted these terms: Cainozoic, from
+&#954;&#945;&#953;&#957;&#959;&#962;, <i>cainos</i>, recent, and &#950;&#969;&#959;&#957;, <i>zoon</i>, animal; Mesozoic,
+from &#956;&#949;&#963;&#959;&#962;, <i>mesos</i>, middle, &amp;c.; Paleozoic, from
+&#960;&#945;&#955;&#945;&#953;&#959;&#962;, <i>palaios</i>, ancient, &amp;c.</p>
+
+<p><a name="Footnote_K_4" id="Footnote_K_4"></a><a href="#FNanchor_K_4"><span class="label">103-D</span></a> Professor Phillips has adopted these terms: Cainozoic, from
+&#954;&#945;&#953;&#957;&#959;&#962;, <i>cainos</i>, recent, and &#950;&#969;&#959;&#957;, <i>zoon</i>, animal; Mesozoic,
+from &#956;&#949;&#963;&#959;&#962;, <i>mesos</i>, middle, &amp;c.; Paleozoic, from
+&#960;&#945;&#955;&#945;&#953;&#959;&#962;, <i>palaios</i>, ancient, &amp;c.</p>
+
+<p><a name="Footnote_K_5" id="Footnote_K_5"></a><a href="#FNanchor_K_5"><span class="label">103-E</span></a> Pal�ontology is the science which treats of fossil remains, both
+animal and vegetable. Etym. &#960;&#945;&#955;&#945;&#953;&#959;&#962;, <i>palaios</i>, ancient,
+&#959;&#957;&#964;&#945;, <i>onta</i>, beings, and &#955;&#959;&#947;&#959;&#962;, <i>logos</i>, a discourse.</p>
+
+<p><a name="Footnote_L_1" id="Footnote_L_1"></a><a href="#FNanchor_L_1"><span class="label">110-A</span></a> See Princ. of Geol. vol. iii. 1st ed.</p>
+
+<p><a name="Footnote_L_2" id="Footnote_L_2"></a><a href="#FNanchor_L_2"><span class="label">112-A</span></a> See Principles, Index, "Serapis."</p>
+
+<p><a name="Footnote_L_3" id="Footnote_L_3"></a><a href="#FNanchor_L_3"><span class="label">113-A</span></a> Geol. Quart. Journ. vol. ii. Memoirs, p. 15.</p>
+
+<p><a name="Footnote_L_4" id="Footnote_L_4"></a><a href="#FNanchor_L_4"><span class="label">114-A</span></a> Quart. Geol. Journ. 4 Mems. p. 48.</p>
+
+<p><a name="Footnote_L_5" id="Footnote_L_5"></a><a href="#FNanchor_L_5"><span class="label">115-A</span></a> Journal, p. 451.</p>
+
+<p><a name="Footnote_L_6" id="Footnote_L_6"></a><a href="#FNanchor_L_6"><span class="label">116-A</span></a> See Principles, 8th ed. pp. 260-268.</p>
+
+<p><a name="Footnote_L_7" id="Footnote_L_7"></a><a href="#FNanchor_L_7"><span class="label">117-A</span></a> Lyell's Second Visit to the United States, vol. ii. chap. xxxiv.</p>
+
+<p><a name="Footnote_L_8" id="Footnote_L_8"></a><a href="#FNanchor_L_8"><span class="label">119-A</span></a> Princ. of Geol. 3d edition, 1834, vol. iii. p. 414.</p>
+
+<p><a name="Footnote_L_9" id="Footnote_L_9"></a><a href="#FNanchor_L_9"><span class="label">120-A</span></a> Proceedings Geol. Soc. No. 43. p. 222.</p>
+
+<p><a name="Footnote_M_1" id="Footnote_M_1"></a><a href="#FNanchor_M_1"><span class="label">122-A</span></a> Chap. xvi. and the references there given.</p>
+
+<p><a name="Footnote_M_2" id="Footnote_M_2"></a><a href="#FNanchor_M_2"><span class="label">122-B</span></a> Voyage in 1822, p. 233.</p>
+
+<p><a name="Footnote_M_3" id="Footnote_M_3"></a><a href="#FNanchor_M_3"><span class="label">123-A</span></a> T. L. Hayes, Boston Journ. Nat. Hist. 1844.</p>
+
+<p><a name="Footnote_M_4" id="Footnote_M_4"></a><a href="#FNanchor_M_4"><span class="label">124-A</span></a> See paper by the author, Phil. Trans. 1835, p. 15.</p>
+
+<p><a name="Footnote_M_5" id="Footnote_M_5"></a><a href="#FNanchor_M_5"><span class="label">125-A</span></a> See above, section, p. 48.</p>
+
+<p><a name="Footnote_M_6" id="Footnote_M_6"></a><a href="#FNanchor_M_6"><span class="label">125-B</span></a> Geol. of Fife, &amp;c. p. 220.</p>
+
+<p><a name="Footnote_M_7" id="Footnote_M_7"></a><a href="#FNanchor_M_7"><span class="label">129-A</span></a> For a full account of the drift of East Norfolk, see a paper by the
+author, Phil. Mag. No. 104. May, 1840.</p>
+
+<p><a name="Footnote_M_8" id="Footnote_M_8"></a><a href="#FNanchor_M_8"><span class="label">130-A</span></a> Quart. Journ. Geol. Soc. vol. vii. p. 22.</p>
+
+<p><a name="Footnote_M_9" id="Footnote_M_9"></a><a href="#FNanchor_M_9"><span class="label">131-A</span></a> Forbes, Memoirs of Geol. Survey of Great Britain, vol. i. p. 377.</p>
+
+<p><a name="Footnote_N_1" id="Footnote_N_1"></a><a href="#FNanchor_N_1"><span class="label">134-A</span></a> Geol. Trans. 2d series, vol. vi. p. 135. Mr. Smith of Jordanhill
+had arrived at similar conclusions as to climate from the shells of the
+Scotch Pleistocene deposits.</p>
+
+<p><a name="Footnote_N_2" id="Footnote_N_2"></a><a href="#FNanchor_N_2"><span class="label">134-B</span></a> Proceedings of Geol. Soc. No. 63. p. 119.</p>
+
+<p><a name="Footnote_N_3" id="Footnote_N_3"></a><a href="#FNanchor_N_3"><span class="label">135-A</span></a> Travels in N. America, vol. ii. p. 141.</p>
+
+<p><a name="Footnote_N_4" id="Footnote_N_4"></a><a href="#FNanchor_N_4"><span class="label">135-B</span></a> Ibid. p. 99. chap. xix.</p>
+
+<p><a name="Footnote_N_5" id="Footnote_N_5"></a><a href="#FNanchor_N_5"><span class="label">136-A</span></a> Bulletin Soc. G�ol. de France, tom. iv. 2de s�r. p. 1121.</p>
+
+<p><a name="Footnote_N_6" id="Footnote_N_6"></a><a href="#FNanchor_N_6"><span class="label">138-A</span></a> See Travels in N. America, vol. i. chap. ii.</p>
+
+<p><a name="Footnote_N_7" id="Footnote_N_7"></a><a href="#FNanchor_N_7"><span class="label">140-A</span></a> Agassiz, Etudes sur les Glaciers.</p>
+
+<p><a name="Footnote_N_8" id="Footnote_N_8"></a><a href="#FNanchor_N_8"><span class="label">143-A</span></a> Archiac, Hist. des Progr�s, &amp;c. vol. ii. p. 249.</p>
+
+<p><a name="Footnote_N_9" id="Footnote_N_9"></a><a href="#FNanchor_N_9"><span class="label">143-B</span></a> See Elements of Geology, 2d ed. 1841.</p>
+
+<p><a name="Footnote_N_10" id="Footnote_N_10"></a><a href="#FNanchor_N_10"><span class="label">144-A</span></a> Darwin's Journal, p. 283.</p>
+
+<p><a name="Footnote_N_11" id="Footnote_N_11"></a><a href="#FNanchor_N_11"><span class="label">144-B</span></a> More recently Sir R. Murchison, having revisited the Alps, has
+declared his opinion that "the great granitic blocks of Mont Blanc were
+translated to the Jura when the intermediate country was under
+water."&mdash;Paper read to Geol. Soc. London, May 30, 1849.</p>
+
+<p><a name="Footnote_O_1" id="Footnote_O_1"></a><a href="#FNanchor_O_1"><span class="label">147-A</span></a> Morris, Geol. Soc. Proceed., 1849.</p>
+
+<p><a name="Footnote_O_2" id="Footnote_O_2"></a><a href="#FNanchor_O_2"><span class="label">147-B</span></a> Woodward's Geology of Norfolk.</p>
+
+<p><a name="Footnote_O_3" id="Footnote_O_3"></a><a href="#FNanchor_O_3"><span class="label">148-A</span></a> Zool. of Beagle, part 1. pp. 9. 111.</p>
+
+<p><a name="Footnote_O_4" id="Footnote_O_4"></a><a href="#FNanchor_O_4"><span class="label">149-A</span></a> Owen, Brit. Foss. Mamm. 271. <i>Mastodon longirostris</i>, Kaup, see
+<i>ibid.</i></p>
+
+<p><a name="Footnote_O_5" id="Footnote_O_5"></a><a href="#FNanchor_O_5"><span class="label">152-A</span></a> I am indebted to Mr. Lonsdale for the details above given
+respecting the structure of this coral.</p>
+
+<p><a name="Footnote_O_6" id="Footnote_O_6"></a><a href="#FNanchor_O_6"><span class="label">155-A</span></a> Owen, Brit. Foss. Mam. xxvi., and Buckland, Rel. Dil. 19. 24.</p>
+
+<p><a name="Footnote_O_7" id="Footnote_O_7"></a><a href="#FNanchor_O_7"><span class="label">155-B</span></a> See Principles of Geology.</p>
+
+<p><a name="Footnote_O_8" id="Footnote_O_8"></a><a href="#FNanchor_O_8"><span class="label">158-A</span></a> See Principles of Geology, chaps. xli. to xliv.</p>
+
+<p><a name="Footnote_P_1" id="Footnote_P_1"></a><a href="#FNanchor_P_1"><span class="label">162-A</span></a> See paper by E. Charlesworth, Esq.; London and Ed. Phil. Mag. No.
+xxxviii. p. 81., Aug. 1835.</p>
+
+<p><a name="Footnote_P_2" id="Footnote_P_2"></a><a href="#FNanchor_P_2"><span class="label">162-B</span></a> See Monograph on the Crag Mollusca. Searles Wood, Paleont. Soc.
+1848.</p>
+
+<p><a name="Footnote_P_3" id="Footnote_P_3"></a><a href="#FNanchor_P_3"><span class="label">163-A</span></a> In regarding the Suffolk crag, both red and coralline, as older
+Pliocene instead of Miocene, I am only returning to the classification
+adopted by me in the Principles and Elements of Geology up to the year
+1838.</p>
+
+<p><a name="Footnote_P_4" id="Footnote_P_4"></a><a href="#FNanchor_P_4"><span class="label">166-A</span></a> E. Forbes, Mem. Geol. Survey, Gt. Brit., vol. i. 386.</p>
+
+<p><a name="Footnote_P_5" id="Footnote_P_5"></a><a href="#FNanchor_P_5"><span class="label">172-A</span></a> Proceedings of the Geol. Soc. vol. iv. part 3. 1845, p. 547.</p>
+
+<p><a name="Footnote_Q_1" id="Footnote_Q_1"></a><a href="#FNanchor_Q_1"><span class="label">175-A</span></a> Bulletin des Sci. de la Soc. Philom., May, 1825, p. 74.</p>
+
+<p><a name="Footnote_Q_2" id="Footnote_Q_2"></a><a href="#FNanchor_Q_2"><span class="label">176-A</span></a> H�bert. Bulletin. 1849, vol. vi. 2d series, p. 459.</p>
+
+<p><a name="Footnote_Q_3" id="Footnote_Q_3"></a><a href="#FNanchor_Q_3"><span class="label">181-A</span></a> Scrope, Geology of Central France, p. 15.</p>
+
+<p><a name="Footnote_Q_4" id="Footnote_Q_4"></a><a href="#FNanchor_Q_4"><span class="label">183-A</span></a> See Desmarest's Crustacea, plate 55.</p>
+
+<p><a name="Footnote_Q_5" id="Footnote_Q_5"></a><a href="#FNanchor_Q_5"><span class="label">185-A</span></a> I believe that the British specimen here figured is P. <i>rhombica</i>,
+Linn.</p>
+
+<p><a name="Footnote_Q_6" id="Footnote_Q_6"></a><a href="#FNanchor_Q_6"><span class="label">189-A</span></a> See Proceedings of Roy. Soc., No. 44. p. 233.</p>
+
+<p><a name="Footnote_Q_7" id="Footnote_Q_7"></a><a href="#FNanchor_Q_7"><span class="label">190-A</span></a> Lyell and Murchison, sur les D�p�ts Lacust. Tertiaries du Cantal,
+&amp;c. Ann. des Sci. Nat. Oct. 1829.</p>
+
+<p><a name="Footnote_R_1" id="Footnote_R_1"></a><a href="#FNanchor_R_1"><span class="label">191-A</span></a> Leyde Magaz. voor Wetensch Konst en Lett., partie v. cahier i. p.
+71. Cited by Rozet, Journ. de G�ologie, tom. i. p. 43.</p>
+
+<p><a name="Footnote_R_2" id="Footnote_R_2"></a><a href="#FNanchor_R_2"><span class="label">191-B</span></a> M. C. Prevost, Submersions It�ratives, &amp;c. Note 23.</p>
+
+<p><a name="Footnote_R_3" id="Footnote_R_3"></a><a href="#FNanchor_R_3"><span class="label">192-A</span></a> Cuvier, Oss. Foss., tom. iii. p. 255.</p>
+
+<p><a name="Footnote_R_4" id="Footnote_R_4"></a><a href="#FNanchor_R_4"><span class="label">194-A</span></a> This species is found both in the Paris and London basins.</p>
+
+<p><a name="Footnote_R_5" id="Footnote_R_5"></a><a href="#FNanchor_R_5"><span class="label">197-A</span></a> Coquilles caract�rist. des Terrains, 1831.</p>
+
+<p><a name="Footnote_R_6" id="Footnote_R_6"></a><a href="#FNanchor_R_6"><span class="label">197-B</span></a> Quarterly Geol. Journal, vol. iii. p. 353.</p>
+
+<p><a name="Footnote_R_7" id="Footnote_R_7"></a><a href="#FNanchor_R_7"><span class="label">199-A</span></a> Prestwich, Quart. Geol. Journ. vol. iii. p. 386.</p>
+
+<p><a name="Footnote_R_8" id="Footnote_R_8"></a><a href="#FNanchor_R_8"><span class="label">199-B</span></a> Pal�ont. Soc. Monograph. Rept. pt. ii. p. 61.</p>
+
+<p><a name="Footnote_R_9" id="Footnote_R_9"></a><a href="#FNanchor_R_9"><span class="label">202-A</span></a> For description of Eocene Cephalopoda, see Monograph by F. E.
+Edwards, Pal�ontograph. Soc. 1849.</p>
+
+<p><a name="Footnote_R_10" id="Footnote_R_10"></a><a href="#FNanchor_R_10"><span class="label">203-A</span></a> Annals of Nat. Hist. vol. iv. No. 23. Nov. 1839.</p>
+
+<p><a name="Footnote_R_11" id="Footnote_R_11"></a><a href="#FNanchor_R_11"><span class="label">206-A</span></a> Murchison, Quart. Journ. of Geol. Soc. vol. v., and Lyell, vol. vi.
+1850. Anniversary Address.</p>
+
+<p><a name="Footnote_R_12" id="Footnote_R_12"></a><a href="#FNanchor_R_12"><span class="label">206-B</span></a> See paper by the author, Quart. Journ. Geol. Soc. vol. iv, p. 12.;
+and Second Visit to the U. S. vol. ii. p. 59.</p>
+
+<p><a name="Footnote_R_13" id="Footnote_R_13"></a><a href="#FNanchor_R_13"><span class="label">206-C</span></a> Quart. Journ. Geol Soc. vol. vi. p. 32.</p>
+
+<p><a name="Footnote_R_14" id="Footnote_R_14"></a><a href="#FNanchor_R_14"><span class="label">207-A</span></a> See Memoir by R. W. Gibbes, Journ. of Acad. Nat. Sci. Philad. vol.
+i. 1847.</p>
+
+<p><a name="Footnote_R_15" id="Footnote_R_15"></a><a href="#FNanchor_R_15"><span class="label">208-A</span></a> Lyell, Quart. Journ. Geol. Soc. 1847, vol. iv. p. 15.</p>
+
+<p class="marbotm05"><a name="Footnote_S_1" id="Footnote_S_1"></a><a href="#FNanchor_S_1"><span class="label">209-A</span></a> M. Alcide d'Orbigny, in his valuable work entitled Pal�ontologie
+Fran�aise, has adopted new terms for the French subdivisions of the
+Cretaceous Series, which, so far as they can be made to tally with English
+equivalents, seem explicable thus:</p>
+
+<table  border="0" cellpadding="2" summary="CRETACEOUS SERIES IN FRANCE AND ENGLAND.">
+<colgroup>
+    <col width="20%">
+    <col width="80%">
+</colgroup>
+
+<tr>
+  <td class="td-left tdtx-top">Danien.</td>
+  <td class="td-left tdtx-top">Maestricht beds.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">Senonien.</td>
+  <td class="td-left tdtx-top">Upper and lower white chalk, and chalk marl.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">Turonien.</td>
+  <td class="td-left tdtx-top">Part of the chalk marl and the upper greensand, the latter being in
+  his last work (Cours El�mentaire) termed C�nomanien.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">Albien.</td>
+  <td class="td-left tdtx-top">Gault.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">Aptien.</td>
+  <td class="td-left tdtx-top">Upper part of lower greensand.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-top">Neocomien.</td>
+  <td class="td-left tdtx-top">Lower part of same.</td>
+</tr>
+</table>
+
+
+<p><a name="Footnote_S_2" id="Footnote_S_2"></a><a href="#FNanchor_S_2"><span class="label">211-A</span></a> See paper by the author, Trans. of Geol. Soc., vol. v. p. 246.,
+1840.</p>
+
+<p><a name="Footnote_S_3" id="Footnote_S_3"></a><a href="#FNanchor_S_3"><span class="label">211-B</span></a> Fitton, Geol. Trans., 2d series, vol. iv. p. 319.</p>
+
+<p><a name="Footnote_S_4" id="Footnote_S_4"></a><a href="#FNanchor_S_4"><span class="label">215-A</span></a> Proceedings of Geol. Soc., vol. iii. pp. 7, 8., 1842.</p>
+
+<p><a name="Footnote_S_5" id="Footnote_S_5"></a><a href="#FNanchor_S_5"><span class="label">216-A</span></a> Geol. Trans. Second Series, vol. iii. p. 232. plate 31. figs. 3.
+and 11.</p>
+
+<p><a name="Footnote_S_6" id="Footnote_S_6"></a><a href="#FNanchor_S_6"><span class="label">216-B</span></a> Geol. of U. S. Exploring Exped. p. 252. 1849.</p>
+
+<p><a name="Footnote_S_7" id="Footnote_S_7"></a><a href="#FNanchor_S_7"><span class="label">217-A</span></a> See Chapters X. and XI.</p>
+
+<p><a name="Footnote_S_8" id="Footnote_S_8"></a><a href="#FNanchor_S_8"><span class="label">217-B</span></a> Darwin, p. 549. Kotzebue's First Voyage, vol. iii. p. 155.</p>
+
+<p><a name="Footnote_S_9" id="Footnote_S_9"></a><a href="#FNanchor_S_9"><span class="label">217-C</span></a> Mantell, Geol. of S. E. of England, p. 96.</p>
+
+<p><a name="Footnote_S_10" id="Footnote_S_10"></a><a href="#FNanchor_S_10"><span class="label">219-A</span></a> Dr. Fitton, Quart. Geol. Journ., vol. i. p. 179., ii. p. 55., and
+iii. p. 289., where comparative sections and a valuable table showing the
+vertical range of the various fossils of the lower greensand at Atherfield
+is given.</p>
+
+<p><a name="Footnote_S_11" id="Footnote_S_11"></a><a href="#FNanchor_S_11"><span class="label">221-A</span></a> Archiac, sur la Form. Cr�tac�e du S. O. de la France, M�m. de la
+Soc. G�ol. de France, tom. ii.</p>
+
+<p><a name="Footnote_S_12" id="Footnote_S_12"></a><a href="#FNanchor_S_12"><span class="label">222-A</span></a> D'Orbigny's Pal�ontologie Fran�aise, pl. 533.</p>
+
+<p class="marbotm05"><a name="Footnote_S_13" id="Footnote_S_13"></a><a href="#FNanchor_S_13"><span class="label">223-A</span></a> In this and subsequent remarks on fossil plants I shall often use
+Dr. Lindley's terms, as most familiar in this country; but as those of M.
+A. Brongniart are much cited, it may be useful to geologists to give a
+table explaining the corresponding names of groups so much spoken of in
+pal�ontology.</p>
+
+<table  border="0" cellpadding="2" summary="CORRESPONDING GROUPS IN PAL�ONTOLOGY AFTER BRONGNIART AND LINDLEY." style="margin-left: 3%;">
+<colgroup>
+    <col width="10%">
+    <col width="3%">
+    <col width="7%">
+    <col width="30%">
+    <col width="15%">
+    <col width="35%">
+</colgroup>
+
+<tr>
+  <td colspan="3">&nbsp;</td>
+  <td class="td-center tdtx-top smaller">Brongniart.</td>
+  <td class="td-left tdtx-top tdp-left smaller">Lindley.</td>
+  <td>&nbsp;</td>
+</tr>
+
+<tr>
+  <td rowspan="2" class="td-center tdtx-mid tdp-right">Cryptogamic.</td>
+  <td rowspan="5">&nbsp;</td>
+  <td rowspan="2" valign="middle" style="white-space: nowrap; font-size: 30pt; font-weight: 300;" class="tdtx-top">{</td>
+  <td class="td-left tdtx-mid tdp-left">1. Cryptogamous amphigens, or cellular cryptogamic.</td>
+  <td class="td-left tdtx-mid tdp-left">Thallogens.</td>
+  <td class="td-left tdtx-mid tdp-left">Lichens, sea-weeds, fungi.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left">2. Cryptogamous acrogens.</td>
+  <td class="td-left tdtx-mid tdp-left">Acrogens.</td>
+  <td class="td-left tdtx-mid tdp-left">Mosses, equisetums, ferns, lycopodiums&mdash;Lepidodendron.</td>
+</tr>
+
+<tr>
+  <td rowspan="3" class="td-center tdtx-mid tdp-right">Phanerogamic.</td>
+  <td rowspan="3" valign="middle" style="white-space: nowrap; font-size: 60pt; font-weight: 100;" class="tdtx-top">{</td>
+  <td class="td-left tdtx-bot tdp-left">3. Dicotyledonous gymnosperms.</td>
+  <td class="td-left tdtx-bot tdp-left">Gymnogens.</td>
+  <td class="td-left tdtx-bot tdp-left">Conifers and Cycads.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left">4. Dicot. Angiosperms.</td>
+  <td class="td-left tdtx-mid tdp-left">Exogens.</td>
+  <td class="td-left tdtx-mid tdp-left">Composit�, leguminos�, umbellifer�, crucifer�, heaths, &amp;c.
+  All native European trees except conifers.</td>
+</tr>
+
+<tr>
+  <td class="td-left tdtx-mid tdp-left">5. Monocotyledons.</td>
+  <td class="td-left tdtx-mid tdp-left">Endogens.</td>
+  <td class="td-left tdtx-mid tdp-left">Palms, lilies, aloes, rushes, grasses, &amp;c.</td>
+</tr>
+</table>
+
+
+<p><a name="Footnote_S_14" id="Footnote_S_14"></a><a href="#FNanchor_S_14"><span class="label">223-B</span></a> A. Brongniart, Veget. Foss. Dict. Univ., p. 111., 1849.</p>
+
+<p><a name="Footnote_S_15" id="Footnote_S_15"></a><a href="#FNanchor_S_15"><span class="label">224-A</span></a> See a paper by the author, Quart. Journ. Geol. Soc., vol. i. p. 55.</p>
+
+<p><a name="Footnote_S_16" id="Footnote_S_16"></a><a href="#FNanchor_S_16"><span class="label">225-A</span></a> Proceed. Geol. Soc. iv. p. 391.</p>
+
+<p><a name="Footnote_S_17" id="Footnote_S_17"></a><a href="#FNanchor_S_17"><span class="label">225-B</span></a> See Forbes, Quart. Geol. Journ. vol. i. p. 79.</p>
+
+<p><a name="Footnote_T_1" id="Footnote_T_1"></a><a href="#FNanchor_T_1"><span class="label">227-A</span></a> Dr. Fitton, Geol. Trans. vol. iv. p. 320. Second Series.</p>
+
+<p><a name="Footnote_T_2" id="Footnote_T_2"></a><a href="#FNanchor_T_2"><span class="label">230-A</span></a> Mantell, Geol. of S. E. of England, p. 244.</p>
+
+<p><a name="Footnote_T_3" id="Footnote_T_3"></a><a href="#FNanchor_T_3"><span class="label">231-A</span></a> "On the Dorsetshire Purbecks," by Prof. E. Forbes, Edinb. Brit.
+Assoc., Aug. 1850.</p>
+
+<p><a name="Footnote_T_4" id="Footnote_T_4"></a><a href="#FNanchor_T_4"><span class="label">233-A</span></a> Mr. Webster first noticed the erect position of the trees and
+described the Dirt-bed.</p>
+
+<p><a name="Footnote_T_5" id="Footnote_T_5"></a><a href="#FNanchor_T_5"><span class="label">233-B</span></a> Fitton, Geol. Trans., Second Series, vol. iv. pp. 220, 221.</p>
+
+<p><a name="Footnote_T_6" id="Footnote_T_6"></a><a href="#FNanchor_T_6"><span class="label">233-C</span></a> See Flinders' Voyage.</p>
+
+<p><a name="Footnote_T_7" id="Footnote_T_7"></a><a href="#FNanchor_T_7"><span class="label">233-D</span></a> Fitton, ibid.</p>
+
+<p><a name="Footnote_T_8" id="Footnote_T_8"></a><a href="#FNanchor_T_8"><span class="label">233-E</span></a> Buckland and De la Beche, Geol. Trans., Second Series, vol. iv. p.
+16. Mr. Forbes has ascertained that the subjacent rock is a freshwater
+limestone, and not a portion of the Portland oolite, as was previously
+imagined.</p>
+
+<p><a name="Footnote_T_9" id="Footnote_T_9"></a><a href="#FNanchor_T_9"><span class="label">234-A</span></a> E. Forbes, ibid.</p>
+
+<p><a name="Footnote_T_10" id="Footnote_T_10"></a><a href="#FNanchor_T_10"><span class="label">235-A</span></a> See Principles of Geol., 8th ed. pp. 260-268.</p>
+
+<p><a name="Footnote_T_11" id="Footnote_T_11"></a><a href="#FNanchor_T_11"><span class="label">235-B</span></a> Ibid. p. 443.</p>
+
+<p><a name="Footnote_T_12" id="Footnote_T_12"></a><a href="#FNanchor_T_12"><span class="label">237-A</span></a> Fitton, Geol. of Hastings, p. 58.; who cites Lander's Travels.</p>
+
+<p><a name="Footnote_T_13" id="Footnote_T_13"></a><a href="#FNanchor_T_13"><span class="label">237-B</span></a> See above, p. 85.; and Second Visit to the U. S. vol. ii. chap.
+xxxiv.</p>
+
+<p><a name="Footnote_T_14" id="Footnote_T_14"></a><a href="#FNanchor_T_14"><span class="label">237-C</span></a> See the Author's Anniv. Address, Geol. Soc. 1850, Quart. Geol.
+Journ. vol. vi. p. 52.</p>
+
+<p><a name="Footnote_U_1" id="Footnote_U_1"></a><a href="#FNanchor_U_1"><span class="label">241-A</span></a> An account of these cliffs was read by the author to the British
+Assoc. at Glasgow, Sept. 1840.</p>
+
+<p><a name="Footnote_U_2" id="Footnote_U_2"></a><a href="#FNanchor_U_2"><span class="label">241-B</span></a> Seine-Inferieure, p. 142. and pl. 6. fig. 1.</p>
+
+<p><a name="Footnote_U_3" id="Footnote_U_3"></a><a href="#FNanchor_U_3"><span class="label">243-A</span></a> Botley Hill, near Godstone, in Surrey, was found by trigonometrical
+measurement to be 880 feet above the level of the sea; and Wrotham Hill,
+near Maidstone, which appears to be next in height of the North Downs, 795
+feet.</p>
+
+<p><a name="Footnote_U_4" id="Footnote_U_4"></a><a href="#FNanchor_U_4"><span class="label">243-B</span></a> My friend Dr. Mantell has kindly drawn up this scale at my request.</p>
+
+<p><a name="Footnote_U_5" id="Footnote_U_5"></a><a href="#FNanchor_U_5"><span class="label">244-A</span></a> Fitton, Geol. of Hastings, p. 55.</p>
+
+<p><a name="Footnote_U_6" id="Footnote_U_6"></a><a href="#FNanchor_U_6"><span class="label">244-B</span></a> Conybeare, Outlines of Geol., p. 81.</p>
+
+<p><a name="Footnote_U_7" id="Footnote_U_7"></a><a href="#FNanchor_U_7"><span class="label">245-A</span></a> Ibid., p. 145.</p>
+
+<p><a name="Footnote_U_8" id="Footnote_U_8"></a><a href="#FNanchor_U_8"><span class="label">245-B</span></a> Geol. of Western Sussex, p. 61.</p>
+
+<p><a name="Footnote_U_9" id="Footnote_U_9"></a><a href="#FNanchor_U_9"><span class="label">247-A</span></a> See illustrations of this theory by Dr. Fitton, Geol. Sketch of
+Hastings.</p>
+
+<p><a name="Footnote_U_10" id="Footnote_U_10"></a><a href="#FNanchor_U_10"><span class="label">248-A</span></a> Sir E. Murchison, Geol. Sketch of Sussex, &amp;c., Geol. Trans., Second
+Series, vol. ii. p. 98.</p>
+
+<p><a name="Footnote_U_11" id="Footnote_U_11"></a><a href="#FNanchor_U_11"><span class="label">248-B</span></a> See <a href="#img099">fig. 94.</a> <a href="#page76">p. 76.</a></p>
+
+<p><a name="Footnote_U_12" id="Footnote_U_12"></a><a href="#FNanchor_U_12"><span class="label">251-A</span></a> Geol. Soc. Proceed. No. 74. p. 363. 1841, and G. S. Trans. 2 Ser.
+v. 7.</p>
+
+<p><a name="Footnote_U_13" id="Footnote_U_13"></a><a href="#FNanchor_U_13"><span class="label">251-B</span></a> For farther information, see Mantell's Geol. of S. E. of England,
+p. 352.</p>
+
+<p><a name="Footnote_U_14" id="Footnote_U_14"></a><a href="#FNanchor_U_14"><span class="label">252-A</span></a> Soul�vemens Jurassiques. Paris, 1832.</p>
+
+<p><a name="Footnote_U_15" id="Footnote_U_15"></a><a href="#FNanchor_U_15"><span class="label">253-A</span></a> See above, p. 82.</p>
+
+<p><a name="Footnote_U_16" id="Footnote_U_16"></a><a href="#FNanchor_U_16"><span class="label">257-A</span></a> See Mantell's Geol. of S. E. of England, p. 32. After re-examining
+the elephant bed in 1834, I was no longer in doubt of its having been a
+regular subaqueous deposit. In 1828, Dr. Mantell discovered in the shingle
+below the chalk-rubble the jawbone of a whale 12 feet long, which must have
+belonged to an individual from 60 to 70 feet in length, Medals of Creation,
+p. 825.</p>
+
+<p><a name="Footnote_V_1" id="Footnote_V_1"></a><a href="#FNanchor_V_1"><span class="label">259-A</span></a> See Chapters VI. and XIX.</p>
+
+<p><a name="Footnote_V_2" id="Footnote_V_2"></a><a href="#FNanchor_V_2"><span class="label">261-A</span></a> Fitton, Geol. Trans., Second Series, vol. iv. pl. 23. fig. 12.</p>
+
+<p><a name="Footnote_V_3" id="Footnote_V_3"></a><a href="#FNanchor_V_3"><span class="label">262-A</span></a> S. P. Pratt, Annals of Nat. Hist., November, 1841.</p>
+
+<p><a name="Footnote_V_4" id="Footnote_V_4"></a><a href="#FNanchor_V_4"><span class="label">263-A</span></a> See Phil. Trans. 1850, p. 393.</p>
+
+<p><a name="Footnote_V_5" id="Footnote_V_5"></a><a href="#FNanchor_V_5"><span class="label">263-B</span></a> P. Scrope, Geol. Proceed., March, 1831.</p>
+
+<p><a name="Footnote_V_6" id="Footnote_V_6"></a><a href="#FNanchor_V_6"><span class="label">265-A</span></a> For a fuller account of these Encrinites, see Buckland's
+Bridgewater Treatise, vol. i. p. 429.</p>
+
+<p><a name="Footnote_V_7" id="Footnote_V_7"></a><a href="#FNanchor_V_7"><span class="label">266-A</span></a> Lycett, Quart. Geol. Journ. vol. iv. p. 183.</p>
+
+<p><a name="Footnote_V_8" id="Footnote_V_8"></a><a href="#FNanchor_V_8"><span class="label">266-B</span></a> Proceedings Geol. Soc. vol. i. p. 414.</p>
+
+<p><a name="Footnote_V_9" id="Footnote_V_9"></a><a href="#FNanchor_V_9"><span class="label">267-A</span></a> See Buckland's Bridgewater Treatise; and Brodie's Fossil Insects,
+where it is suggested that these elytra may belong to <i>Priomus</i>.</p>
+
+<p><a name="Footnote_V_10" id="Footnote_V_10"></a><a href="#FNanchor_V_10"><span class="label">267-B</span></a> Vol. i. p. 115.</p>
+
+<p><a name="Footnote_V_11" id="Footnote_V_11"></a><a href="#FNanchor_V_11"><span class="label">269-A</span></a> I have given a figure in the Principles of Geology, chap. ix., of
+another Stonesfield specimen of <i>Amphitherium Prevostii</i>, in which the
+sockets and roots of the teeth are finely exposed.</p>
+
+<p><a name="Footnote_V_12" id="Footnote_V_12"></a><a href="#FNanchor_V_12"><span class="label">269-B</span></a> A figure of this recent <i>Myrmecobius</i> will be found in the
+Principles, chap. ix.</p>
+
+<p><a name="Footnote_V_13" id="Footnote_V_13"></a><a href="#FNanchor_V_13"><span class="label">270-A</span></a> Owen's British Fossil Mammals, p. 62.</p>
+
+<p><a name="Footnote_V_14" id="Footnote_V_14"></a><a href="#FNanchor_V_14"><span class="label">271-A</span></a> Ibbetson and Morris, Report of Brit. Ass., 1847, p. 131.</p>
+
+<p><a name="Footnote_W_1" id="Footnote_W_1"></a><a href="#FNanchor_W_1"><span class="label">274-A</span></a> Conyb. and Phil. p. 261.</p>
+
+<p><a name="Footnote_W_2" id="Footnote_W_2"></a><a href="#FNanchor_W_2"><span class="label">275-A</span></a> Agassiz, Pois. Fos. vol. ii. tab. 28, 29.</p>
+
+<p><a name="Footnote_W_3" id="Footnote_W_3"></a><a href="#FNanchor_W_3"><span class="label">276-A</span></a> Bridgewater Treatise, p. 290.</p>
+
+<p><a name="Footnote_W_4" id="Footnote_W_4"></a><a href="#FNanchor_W_4"><span class="label">276-B</span></a> Agassiz, Poissons Fossiles, vol. iii. tab. C. fig. 1.</p>
+
+<p><a name="Footnote_W_5" id="Footnote_W_5"></a><a href="#FNanchor_W_5"><span class="label">276-C</span></a> Ibid. p. 168.</p>
+
+<p><a name="Footnote_W_6" id="Footnote_W_6"></a><a href="#FNanchor_W_6"><span class="label">276-D</span></a> Ibid. p. 187.</p>
+
+<p><a name="Footnote_W_7" id="Footnote_W_7"></a><a href="#FNanchor_W_7"><span class="label">277-A</span></a> Geol. Soc. Proceedings, vol. iii. p. 157. 1839.</p>
+
+<p><a name="Footnote_W_8" id="Footnote_W_8"></a><a href="#FNanchor_W_8"><span class="label">277-B</span></a> Geol. Trans. Second Series, vol. v. p. 511.</p>
+
+<p><a name="Footnote_W_9" id="Footnote_W_9"></a><a href="#FNanchor_W_9"><span class="label">278-A</span></a> Geol. Trans., Second Series, vol. i. pl. 49.</p>
+
+<p><a name="Footnote_W_10" id="Footnote_W_10"></a><a href="#FNanchor_W_10"><span class="label">278-B</span></a> Conybeare and De la Beche. Geol. Trans.; and Buckland, Bridgew.
+Treat., p. 203.</p>
+
+<p><a name="Footnote_W_11" id="Footnote_W_11"></a><a href="#FNanchor_W_11"><span class="label">278-C</span></a> Quart. Geol. Journ. vol. ii. p. 411.</p>
+
+<p><a name="Footnote_W_12" id="Footnote_W_12"></a><a href="#FNanchor_W_12"><span class="label">279-A</span></a> &#913;&#956;&#946;&#955;&#965;&#962;, <i>amblys</i>, blunt; and &#8165;&#965;&#947;&#967;&#959;&#962;,
+<i>rhynchus</i>, snout.</p>
+
+<p><a name="Footnote_W_13" id="Footnote_W_13"></a><a href="#FNanchor_W_13"><span class="label">280-A</span></a> Darwin's Journal, chap. xix.</p>
+
+<p><a name="Footnote_W_14" id="Footnote_W_14"></a><a href="#FNanchor_W_14"><span class="label">280-B</span></a> Bridgew. Treat., p. 125.</p>
+
+<p><a name="Footnote_W_15" id="Footnote_W_15"></a><a href="#FNanchor_W_15"><span class="label">281-A</span></a> Geological Researches, p. 334.</p>
+
+<p><a name="Footnote_W_16" id="Footnote_W_16"></a><a href="#FNanchor_W_16"><span class="label">281-B</span></a> Buckland, Bridgew. Treat., p. 307.</p>
+
+<p><a name="Footnote_W_17" id="Footnote_W_17"></a><a href="#FNanchor_W_17"><span class="label">281-C</span></a> Ibid.</p>
+
+<p><a name="Footnote_W_18" id="Footnote_W_18"></a><a href="#FNanchor_W_18"><span class="label">281-D</span></a> See Principles, <i>Index</i>, Lancerote, Graham Island, Calabria.</p>
+
+<p><a name="Footnote_W_19" id="Footnote_W_19"></a><a href="#FNanchor_W_19"><span class="label">281-E</span></a> A History of Fossil Insects, &amp;c. 1845. London.</p>
+
+<p><a name="Footnote_W_20" id="Footnote_W_20"></a><a href="#FNanchor_W_20"><span class="label">282-A</span></a> Tableau des Veg. Fos. 1849, p. 105.</p>
+
+<p><a name="Footnote_W_21" id="Footnote_W_21"></a><a href="#FNanchor_W_21"><span class="label">283-A</span></a> Con. and Phil., p. 166.</p>
+
+<p><a name="Footnote_W_22" id="Footnote_W_22"></a><a href="#FNanchor_W_22"><span class="label">283-B</span></a> Geol. Researches, p. 337.</p>
+
+<p><a name="Footnote_W_23" id="Footnote_W_23"></a><a href="#FNanchor_W_23"><span class="label">283-C</span></a> Burat's D'Aubuisson, tom. ii. p. 456.</p>
+
+<p><a name="Footnote_W_24" id="Footnote_W_24"></a><a href="#FNanchor_W_24"><span class="label">285-A</span></a> See description of the coal-field by the author, and the plants by
+C. J. F. Bunbury, Esq., Quart. Geol. Journ., vol. iii. p. 281.</p>
+
+<p><a name="Footnote_X_1" id="Footnote_X_1"></a><a href="#FNanchor_X_1"><span class="label">286-A</span></a> Buckland, Bridgew. Treat., vol. ii. p. 38.</p>
+
+<p><a name="Footnote_X_2" id="Footnote_X_2"></a><a href="#FNanchor_X_2"><span class="label">287-A</span></a> Monog. des Bunten Sandsteins.</p>
+
+<p><a name="Footnote_X_3" id="Footnote_X_3"></a><a href="#FNanchor_X_3"><span class="label">288-A</span></a> Tableau des Genres de Veg. Fos., Dict. Univ. 1849.</p>
+
+<p><a name="Footnote_X_4" id="Footnote_X_4"></a><a href="#FNanchor_X_4"><span class="label">290-A</span></a> Geol. Trans., Second Series, vol. v.</p>
+
+<p><a name="Footnote_X_5" id="Footnote_X_5"></a><a href="#FNanchor_X_5"><span class="label">290-B</span></a> Buckland, Proc. Geol. Soc. vol. ii. p. 439.; and Murchison and
+Strickland Geol. Trans., Second Ser., vol. v. p. 347.</p>
+
+<p><a name="Footnote_X_6" id="Footnote_X_6"></a><a href="#FNanchor_X_6"><span class="label">295-A</span></a> Ormerod, Quart. Geol. Journ. 1848, vol. iv. p. 277.</p>
+
+<p><a name="Footnote_X_7" id="Footnote_X_7"></a><a href="#FNanchor_X_7"><span class="label">296-A</span></a> Hugh Miller, First Impressions of England, 1847, pp. 183. 214.</p>
+
+<p><a name="Footnote_X_8" id="Footnote_X_8"></a><a href="#FNanchor_X_8"><span class="label">297-A</span></a> Buist, Trans. of Bombay Geograph. Soc. 1850, vol. ix. p. 38.</p>
+
+<p><a name="Footnote_X_9" id="Footnote_X_9"></a><a href="#FNanchor_X_9"><span class="label">297-B</span></a> Travels in North America, vol. ii. p. 168.</p>
+
+<p><a name="Footnote_X_10" id="Footnote_X_10"></a><a href="#FNanchor_X_10"><span class="label">298-A</span></a> Hitchcock, Mem. of Amer. Acad. New Ser., vol. iii. p. 129.</p>
+
+<p><a name="Footnote_X_11" id="Footnote_X_11"></a><a href="#FNanchor_X_11"><span class="label">298-B</span></a> This specimen is now in Dr. Mantell's museum.</p>
+
+<p><a name="Footnote_X_12" id="Footnote_X_12"></a><a href="#FNanchor_X_12"><span class="label">299-A</span></a> Amer. Journ. of Sci. vol. xlviii. p. 46.</p>
+
+<p><a name="Footnote_X_13" id="Footnote_X_13"></a><a href="#FNanchor_X_13"><span class="label">300-A</span></a> Journal of Voyage of Beagle, &amp;c. 2d edition, p. 89. 1845.</p>
+
+<p><a name="Footnote_Y_1" id="Footnote_Y_1"></a><a href="#FNanchor_Y_1"><span class="label">301-A</span></a> Pal�ontographical Society, 1848, London.</p>
+
+<p><a name="Footnote_Y_2" id="Footnote_Y_2"></a><a href="#FNanchor_Y_2"><span class="label">302-A</span></a> Trans. Geol. Soc. Lond., Second Series, vol. iii. p. 37.</p>
+
+<p><a name="Footnote_Y_3" id="Footnote_Y_3"></a><a href="#FNanchor_Y_3"><span class="label">303-A</span></a> King's Monograph, pl. 2.</p>
+
+<p><a name="Footnote_Y_4" id="Footnote_Y_4"></a><a href="#FNanchor_Y_4"><span class="label">306-A</span></a> See paper by Messrs. Riley and Stutchbury, Geol. Trans., Second
+Series, vol. v. p. 349., plate 29., figures 2. and 5.</p>
+
+<p><a name="Footnote_Y_5" id="Footnote_Y_5"></a><a href="#FNanchor_Y_5"><span class="label">306-B</span></a> Owen, Report on Reptiles, British Assoc., Eleventh Meeting, 1841,
+p. 197.</p>
+
+<p><a name="Footnote_Y_6" id="Footnote_Y_6"></a><a href="#FNanchor_Y_6"><span class="label">307-A</span></a> Murchison's Russia, vol. ii. pl. A. fig. 3.</p>
+
+<p><a name="Footnote_Z_1" id="Footnote_Z_1"></a><a href="#FNanchor_Z_1"><span class="label">308-A</span></a> Phillips; art. "Geology," Encyc. Britan.</p>
+
+<p><a name="Footnote_Z_2" id="Footnote_Z_2"></a><a href="#FNanchor_Z_2"><span class="label">309-A</span></a> Sedgwick, Geol. Trans., Second Series, vol. iv.; and Phillips,
+Geol. of Yorksh. part 2.</p>
+
+<p><a name="Footnote_Z_3" id="Footnote_Z_3"></a><a href="#FNanchor_Z_3"><span class="label">309-B</span></a> Memoirs of Geol. Survey, vol. i. p. 195.</p>
+
+<p><a name="Footnote_Z_4" id="Footnote_Z_4"></a><a href="#FNanchor_Z_4"><span class="label">315-A</span></a> The trunk in this case is referred by Mr. Brown to <i>Lepidodendron</i>,
+but his illustrations seem to show the usual markings assumed by
+<i>Sigillaria</i> near its base.</p>
+
+<p><a name="Footnote_Z_5" id="Footnote_Z_5"></a><a href="#FNanchor_Z_5"><span class="label">316-A</span></a> For terminology of classification of plants, see above, note, p.
+223.</p>
+
+<p><a name="Footnote_Z_6" id="Footnote_Z_6"></a><a href="#FNanchor_Z_6"><span class="label">316-B</span></a> Quart. Geol. Journ., vol. v., Mem., p. 17.</p>
+
+<p><a name="Footnote_Z_7" id="Footnote_Z_7"></a><a href="#FNanchor_Z_7"><span class="label">317-A</span></a> Anniv. Address to Geol. Soc., 1840.</p>
+
+<p><a name="Footnote_Z_8" id="Footnote_Z_8"></a><a href="#FNanchor_Z_8"><span class="label">317-B</span></a> Hawkshaw, Geol. Soc. Proceedings, Nos. 64. and 69.</p>
+
+<p><a name="Footnote_Z_9" id="Footnote_Z_9"></a><a href="#FNanchor_Z_9"><span class="label">318-A</span></a> Geol. Report on Cornwall, &amp;c. p. 143.</p>
+
+<p><a name="Footnote_Z_10" id="Footnote_Z_10"></a><a href="#FNanchor_Z_10"><span class="label">318-B</span></a> Lindley and Hutton, Foss. Flo. part 6. p. 150.</p>
+
+<p><a name="Footnote_Z_11" id="Footnote_Z_11"></a><a href="#FNanchor_Z_11"><span class="label">319-A</span></a> See papers by Messrs. Beckett and Ick. Proceed. in Geol. Soc., vol.
+iv. p. 287.</p>
+
+<p><a name="Footnote_Z_12" id="Footnote_Z_12"></a><a href="#FNanchor_Z_12"><span class="label">319-B</span></a> Annales des Mines, 1821.</p>
+
+<p><a name="Footnote_Z_13" id="Footnote_Z_13"></a><a href="#FNanchor_Z_13"><span class="label">320-A</span></a> Principles of Geol., 8th ed., p. 215.</p>
+
+<p><a name="Footnote_Z_14" id="Footnote_Z_14"></a><a href="#FNanchor_Z_14"><span class="label">321-A</span></a> See figures of texture, Witham, Foss. Veget., pl. 3.</p>
+
+<p><a name="Footnote_Z_15" id="Footnote_Z_15"></a><a href="#FNanchor_Z_15"><span class="label">321-B</span></a> See Lyell's Travels in N. America, vol. ii. p. 179.</p>
+
+<p><a name="Footnote_Z_16" id="Footnote_Z_16"></a><a href="#FNanchor_Z_16"><span class="label">322-A</span></a> Quart. Geol. Journ., vol. ii. p. 177.</p>
+
+<p><a name="Footnote_Z_17" id="Footnote_Z_17"></a><a href="#FNanchor_Z_17"><span class="label">324-A</span></a> Geol. Quart. Journ., vol. ii. p. 393.; and vol. vi. p. 115.</p>
+
+<p><a name="Footnote_Z_18" id="Footnote_Z_18"></a><a href="#FNanchor_Z_18"><span class="label">325-A</span></a> Prestwich, Geol. Trans., 2d Series, vol. v. p. 440. Murchison,
+Silurian System, p. 105.</p>
+
+<p><a name="Footnote_Z_19" id="Footnote_Z_19"></a><a href="#FNanchor_Z_19"><span class="label">325-B</span></a> Silurian System, p. 84.</p>
+
+<p><a name="Footnote_Z_20" id="Footnote_Z_20"></a><a href="#FNanchor_Z_20"><span class="label">325-C</span></a> Trans. Roy. Soc. Edin. vol. xiii. Horner, Edin. New Phil. Journ.,
+April, 1836.</p>
+
+<p><a name="Footnote_Z_21" id="Footnote_Z_21"></a><a href="#FNanchor_Z_21"><span class="label">325-D</span></a> Phillips; art. "Geology," Encyc. Metrop., p. 590.</p>
+
+<p><a name="Footnote_Z_22" id="Footnote_Z_22"></a><a href="#FNanchor_Z_22"><span class="label">326-A</span></a> Phillips; art. "Geology," Encyc. Metrop., p. 592.</p>
+
+<p><a name="Footnote_Z_23" id="Footnote_Z_23"></a><a href="#FNanchor_Z_23"><span class="label">326-B</span></a> Memoirs of Geol. Survey, pp. 51. 255, &amp;c.</p>
+
+<p><a name="Footnote_AA_1" id="Footnote_AA_1"></a><a href="#FNanchor_AA_1"><span class="label">329-A</span></a> H. D. Rogers, Trans. Assoc. Amer. Geol., 1840-42, p. 440.</p>
+
+<p><a name="Footnote_AA_2" id="Footnote_AA_2"></a><a href="#FNanchor_AA_2"><span class="label">333-A</span></a> Trans. of Ass. of Amer. Geol., p. 470.</p>
+
+<p><a name="Footnote_AA_3" id="Footnote_AA_3"></a><a href="#FNanchor_AA_3"><span class="label">334-A</span></a> Lyell's Second Visit to the U. S., vol. ii. p. 245. American Journ.
+of Sci., 2d series, vol. v. p. 17.</p>
+
+<p><a name="Footnote_AA_4" id="Footnote_AA_4"></a><a href="#FNanchor_AA_4"><span class="label">335-A</span></a> Principles of Geol., p. 696.</p>
+
+<p><a name="Footnote_AA_5" id="Footnote_AA_5"></a><a href="#FNanchor_AA_5"><span class="label">335-B</span></a> For changes in climate, see Principles of Geol., chaps. vii. and
+viii.</p>
+
+<p><a name="Footnote_AA_6" id="Footnote_AA_6"></a><a href="#FNanchor_AA_6"><span class="label">335-C</span></a> Geol. Trans., 2d series, vol. vi. p. 330.</p>
+
+<p><a name="Footnote_AA_7" id="Footnote_AA_7"></a><a href="#FNanchor_AA_7"><span class="label">336-A</span></a> Agassiz, Poiss. Foss., lib. 4. p. 62. and liv. 5. p. 88.</p>
+
+<p><a name="Footnote_AA_8" id="Footnote_AA_8"></a><a href="#FNanchor_AA_8"><span class="label">337-A</span></a> Goldfuss, Neue Jenaische Lit. Zeit., 1848; and Von Meyer, Quart.
+Geol. Journ., vol. iv. p. 51., memoirs.</p>
+
+<p><a name="Footnote_AA_9" id="Footnote_AA_9"></a><a href="#FNanchor_AA_9"><span class="label">338-A</span></a> See Lyell's Second Visit, &amp;c., vol. ii. p. 305.</p>
+
+<p><a name="Footnote_AA_10" id="Footnote_AA_10"></a><a href="#FNanchor_AA_10"><span class="label">340-A</span></a> These impressions, found by Mr. Lea, were imagined to be in a rock
+as ancient as the old red sandstone; but, according to Mr. H. D. Rogers,
+they are in the lowest part of the coal formation.</p>
+
+<p><a name="Footnote_AA_11" id="Footnote_AA_11"></a><a href="#FNanchor_AA_11"><span class="label">341-A</span></a> Phillips, Geol. of Yorksh., vol. ii. p. 208.</p>
+
+<p><a name="Footnote_AA_12" id="Footnote_AA_12"></a><a href="#FNanchor_AA_12"><span class="label">342-A</span></a> Phillips, Geol. of Yorksh., pl. 20. fig. 65.</p>
+
+<p><a name="Footnote_AA_13" id="Footnote_AA_13"></a><a href="#FNanchor_AA_13"><span class="label">342-B</span></a> Ibid., pl. 17. fig. 15.</p>
+
+<p><a name="Footnote_AB_1" id="Footnote_AB_1"></a><a href="#FNanchor_AB_1"><span class="label">342-C</span></a> See section, <a href="#img303">fig. 318.</a> <a href="#page287">p. 287.</a></p>
+
+<p><a name="Footnote_AB_2" id="Footnote_AB_2"></a><a href="#FNanchor_AB_2"><span class="label">343-A</span></a> The Old Red Sandstone, by Hugh Miller, 1841.</p>
+
+<p><a name="Footnote_AB_3" id="Footnote_AB_3"></a><a href="#FNanchor_AB_3"><span class="label">345-A</span></a> Old Red Sandstone. Plate 1. fig. 1. Mr. M.'s description of the
+fish is most graphic and correct.</p>
+
+<p><a name="Footnote_AB_4" id="Footnote_AB_4"></a><a href="#FNanchor_AB_4"><span class="label">347-A</span></a> Camb. Phil. Trans., vol. vi. pl. 8. fig. 2.</p>
+
+<p><a name="Footnote_AB_5" id="Footnote_AB_5"></a><a href="#FNanchor_AB_5"><span class="label">349-A</span></a> See Proceedings of Geol. Soc., and the anniversary speech of Dr.
+Buckland, P. G. S., for 1841.</p>
+
+<p><a name="Footnote_AB_6" id="Footnote_AB_6"></a><a href="#FNanchor_AB_6"><span class="label">349-B</span></a> Lyell's Second Visit to the United States, vol. ii. p. 277.</p>
+
+<p><a name="Footnote_AB_7" id="Footnote_AB_7"></a><a href="#FNanchor_AB_7"><span class="label">350-A</span></a> Memoir on the Hartz, Pal�ontographica of Dunker and Von Meyer, part
+iii.</p>
+
+<p><a name="Footnote_AC_1" id="Footnote_AC_1"></a><a href="#FNanchor_AC_1"><span class="label">352-A</span></a> Murchison, Silurian System, p. 198, 199.</p>
+
+<p><a name="Footnote_AC_2" id="Footnote_AC_2"></a><a href="#FNanchor_AC_2"><span class="label">354-A</span></a> Silurian System, pl. 7. bis. fig. 1. b.</p>
+
+<p><a name="Footnote_AC_3" id="Footnote_AC_3"></a><a href="#FNanchor_AC_3"><span class="label">358-A</span></a> Quart. Geol. Journ., vol. ii. p. 11.; and Memoirs of Geol. Survey,
+vol. ii. p. 518.</p>
+
+<p><a name="Footnote_AC_4" id="Footnote_AC_4"></a><a href="#FNanchor_AC_4"><span class="label">359-A</span></a> Quart. Geol. Journ., vol. iv. p. 300.</p>
+
+<p><a name="Footnote_AC_5" id="Footnote_AC_5"></a><a href="#FNanchor_AC_5"><span class="label">359-B</span></a> Ibid., 299.</p>
+
+<p><a name="Footnote_AC_6" id="Footnote_AC_6"></a><a href="#FNanchor_AC_6"><span class="label">359-C</span></a> Ibid., 145.</p>
+
+<p><a name="Footnote_AC_7" id="Footnote_AC_7"></a><a href="#FNanchor_AC_7"><span class="label">360-A</span></a> Since this was written, Mr. Logan has discovered chelonian
+footprints in the lowest fossiliferous beds of the Silurian series, near
+Montreal, in Canada. Professor Owen inclines to refer them to the genus
+<i>Emys</i>.&mdash;<i>Quart. Journ. G. S.</i>, vol. vii. p. lxxvi.</p>
+
+<p><a name="Footnote_AD_1" id="Footnote_AD_1"></a><a href="#FNanchor_AD_1"><span class="label">368-A</span></a> For a description and theory of active volcanos, see Principles of
+Geology, chaps. xxiv. to xxvii.</p>
+
+<p><a name="Footnote_AD_2" id="Footnote_AD_2"></a><a href="#FNanchor_AD_2"><span class="label">374-A</span></a> G. Rose, Ann. des Mines, tom. viii. p. 32.</p>
+
+<p><a name="Footnote_AD_3" id="Footnote_AD_3"></a><a href="#FNanchor_AD_3"><span class="label">374-B</span></a> Geol. Trans. vol. ii. p. 211. 2d series.</p>
+
+<p><a name="Footnote_AE_1" id="Footnote_AE_1"></a><a href="#FNanchor_AE_1"><span class="label">378-A</span></a> I have been favoured with this drawing by Captain B. Hall.</p>
+
+<p><a name="Footnote_AE_2" id="Footnote_AE_2"></a><a href="#FNanchor_AE_2"><span class="label">381-A</span></a> Cambridge Transactions, vol. i. p. 402.</p>
+
+<p><a name="Footnote_AE_3" id="Footnote_AE_3"></a><a href="#FNanchor_AE_3"><span class="label">382-A</span></a> Cambridge Trans., vol. i. p. 410.</p>
+
+<p><a name="Footnote_AE_4" id="Footnote_AE_4"></a><a href="#FNanchor_AE_4"><span class="label">382-B</span></a> Ibid. vol. ii. p. 175.</p>
+
+<p><a name="Footnote_AE_5" id="Footnote_AE_5"></a><a href="#FNanchor_AE_5"><span class="label">382-C</span></a> Dr. Berger, Geol. Trans., 1st series, vol. iii. p. 172.</p>
+
+<p><a name="Footnote_AE_6" id="Footnote_AE_6"></a><a href="#FNanchor_AE_6"><span class="label">382-D</span></a> Geol. Trans., 1st series, vol. iii. p. 210. and plate 10.</p>
+
+<p><a name="Footnote_AE_7" id="Footnote_AE_7"></a><a href="#FNanchor_AE_7"><span class="label">382-E</span></a> Ibid. p. 201.</p>
+
+<p><a name="Footnote_AE_8" id="Footnote_AE_8"></a><a href="#FNanchor_AE_8"><span class="label">383-A</span></a> Geol. Trans., 1st series, vol. iii. p. 205.</p>
+
+<p><a name="Footnote_AE_9" id="Footnote_AE_9"></a><a href="#FNanchor_AE_9"><span class="label">383-B</span></a> Ibid. p. 213.; and Playfair, Illust. of Hutt. Theory, p. 253.</p>
+
+<p><a name="Footnote_AE_10" id="Footnote_AE_10"></a><a href="#FNanchor_AE_10"><span class="label">383-C</span></a> Geol. Trans., 1st series, vol. iii. p. 206.</p>
+
+<p><a name="Footnote_AE_11" id="Footnote_AE_11"></a><a href="#FNanchor_AE_11"><span class="label">383-D</span></a> Sedgwick, Camb. Trans. vol. ii. p. 37.</p>
+
+<p><a name="Footnote_AE_12" id="Footnote_AE_12"></a><a href="#FNanchor_AE_12"><span class="label">383-E</span></a> Illust. of Hutt. Theory, � 253. and 261. Dr. MacCulloch, Geol.
+Trans., 1st series, vol. ii. p. 305.</p>
+
+<p><a name="Footnote_AE_13" id="Footnote_AE_13"></a><a href="#FNanchor_AE_13"><span class="label">383-F</span></a> Syst. of Geol. vol. i. p. 206.</p>
+
+<p><a name="Footnote_AE_14" id="Footnote_AE_14"></a><a href="#FNanchor_AE_14"><span class="label">384-A</span></a> Camb. Trans. vol. ii. p. 180.</p>
+
+<p><a name="Footnote_AE_15" id="Footnote_AE_15"></a><a href="#FNanchor_AE_15"><span class="label">385-A</span></a> MacCul. Syst. of Geol. vol. ii. p. 137.</p>
+
+<p><a name="Footnote_AE_16" id="Footnote_AE_16"></a><a href="#FNanchor_AE_16"><span class="label">385-B</span></a> Seale's Geognosy of St. Helena, plate 9.</p>
+
+<p><a name="Footnote_AE_17" id="Footnote_AE_17"></a><a href="#FNanchor_AE_17"><span class="label">386-A</span></a> Fortis. M�m. sur l'Hist. Nat. de l'Italie, tom. i. p. 233. plate 7.</p>
+
+<p><a name="Footnote_AE_18" id="Footnote_AE_18"></a><a href="#FNanchor_AE_18"><span class="label">387-A</span></a> Scrope, Geol. Trans. vol. ii. p. 205. 2d series.</p>
+
+<p><a name="Footnote_AE_19" id="Footnote_AE_19"></a><a href="#FNanchor_AE_19"><span class="label">389-A</span></a> See Princ. of Geol., <i>Index</i>, "Graham Island," "Ny�e,"
+"Conglomerates, volcanic," &amp;c.</p>
+
+<p><a name="Footnote_AE_20" id="Footnote_AE_20"></a><a href="#FNanchor_AE_20"><span class="label">390-A</span></a> MacCulloch, West. Isl., vol. ii. p. 487.</p>
+
+<p><a name="Footnote_AE_21" id="Footnote_AE_21"></a><a href="#FNanchor_AE_21"><span class="label">390-B</span></a> Syst. of Geol., vol. ii. p. 114.</p>
+
+<p><a name="Footnote_AE_22" id="Footnote_AE_22"></a><a href="#FNanchor_AE_22"><span class="label">390-C</span></a> Ibid.</p>
+
+<p><a name="Footnote_AE_23" id="Footnote_AE_23"></a><a href="#FNanchor_AE_23"><span class="label">392-A</span></a> See Principles, chaps. xxiv-xxvii.</p>
+
+<p><a name="Footnote_AE_24" id="Footnote_AE_24"></a><a href="#FNanchor_AE_24"><span class="label">393-A</span></a> See Principles, chaps. xxvi. and xxx.; 8th ed. p. 397-475.</p>
+
+<p><a name="Footnote_AE_25" id="Footnote_AE_25"></a><a href="#FNanchor_AE_25"><span class="label">394-A</span></a> See Principles of Geol. ch. xxiv. (8th ed. p. 355.).</p>
+
+<p><a name="Footnote_AE_26" id="Footnote_AE_26"></a><a href="#FNanchor_AE_26"><span class="label">394-B</span></a> See Lyell on Craters of Denudation, Quart. Geol. Journ. vol. vi. p.
+232.</p>
+
+<p><a name="Footnote_AF_1" id="Footnote_AF_1"></a><a href="#FNanchor_AF_1"><span class="label">399-A</span></a> Caldcleugh, Phil. Trans. 1836. p. 27., and Official Documents of
+Nicaragua.</p>
+
+<p><a name="Footnote_AF_2" id="Footnote_AF_2"></a><a href="#FNanchor_AF_2"><span class="label">399-B</span></a> See Principles, <i>Index</i>, "Skaptar Jokul."</p>
+
+<p><a name="Footnote_AF_3" id="Footnote_AF_3"></a><a href="#FNanchor_AF_3"><span class="label">401-A</span></a> This view of the Isle of Cyclops is from an original drawing by my
+friend the late Captain Basil Hall, R. N.</p>
+
+<p><a name="Footnote_AF_4" id="Footnote_AF_4"></a><a href="#FNanchor_AF_4"><span class="label">404-A</span></a> Consult the valuable memoir of M. L. A. Necker, M�m. de la Soc. de
+Phys. et d'Hist. Nat. de G�n�ve, tom. ii. part i. Nov. 1822.</p>
+
+<p><a name="Footnote_AF_5" id="Footnote_AF_5"></a><a href="#FNanchor_AF_5"><span class="label">405-A</span></a> From a drawing of M. Necker, in M�m. above cited.</p>
+
+<p><a name="Footnote_AF_6" id="Footnote_AF_6"></a><a href="#FNanchor_AF_6"><span class="label">405-B</span></a> Phil. Trans., vol. lxx., 1780.</p>
+
+<p><a name="Footnote_AG_1" id="Footnote_AG_1"></a><a href="#FNanchor_AG_1"><span class="label">409-A</span></a> Maclure, Journ. de Phys., vol. lxvi. p. 219., 1808; cited by
+Daubeny, Description of Volcanos, p. 24.</p>
+
+<p><a name="Footnote_AG_2" id="Footnote_AG_2"></a><a href="#FNanchor_AG_2"><span class="label">410-A</span></a> This view is taken from a sketch which I made on the spot in 1830.</p>
+
+<p><a name="Footnote_AG_3" id="Footnote_AG_3"></a><a href="#FNanchor_AG_3"><span class="label">416-A</span></a> Trans. of Geol. Soc., 2d series, vol. v.</p>
+
+<p><a name="Footnote_AG_4" id="Footnote_AG_4"></a><a href="#FNanchor_AG_4"><span class="label">419-A</span></a> Scrope, Edin. Journ. of Sci., June, 1826, p. 145.</p>
+
+<p><a name="Footnote_AG_5" id="Footnote_AG_5"></a><a href="#FNanchor_AG_5"><span class="label">419-B</span></a> Hibbert, Extinct Volcanos of the Rhine, p. 24.</p>
+
+<p><a name="Footnote_AH_1" id="Footnote_AH_1"></a><a href="#FNanchor_AH_1"><span class="label">422-A</span></a> See the map, <a href="#page179">p. 179.</a></p>
+
+<p><a name="Footnote_AH_2" id="Footnote_AH_2"></a><a href="#FNanchor_AH_2"><span class="label">423-A</span></a> Scrope's Central France, p. 98.</p>
+
+<p><a name="Footnote_AH_3" id="Footnote_AH_3"></a><a href="#FNanchor_AH_3"><span class="label">423-B</span></a> See chaps. xxiv., xxv., and xxvi., 7th and 8th editions.</p>
+
+<p><a name="Footnote_AH_4" id="Footnote_AH_4"></a><a href="#FNanchor_AH_4"><span class="label">423-C</span></a> See Quarterly Geol. Journ., vol. ii. p. 77.</p>
+
+<p><a name="Footnote_AH_5" id="Footnote_AH_5"></a><a href="#FNanchor_AH_5"><span class="label">425-A</span></a> For a view of Puy de Tartaret and Mont Dor, see Scrope's Volcanos
+of Central France.</p>
+
+<p><a name="Footnote_AH_6" id="Footnote_AH_6"></a><a href="#FNanchor_AH_6"><span class="label">427-A</span></a> Scrope's Central France, p. 60., and plate.</p>
+
+<p><a name="Footnote_AH_7" id="Footnote_AH_7"></a><a href="#FNanchor_AH_7"><span class="label">428-A</span></a> Daubeny on Volcanos, p. 14.</p>
+
+<p><a name="Footnote_AH_8" id="Footnote_AH_8"></a><a href="#FNanchor_AH_8"><span class="label">428-B</span></a> Edin. Journ. of Sci., No. iv. N. S. p. 276. Figures of some of
+these remains are given by M. Bertrand de Doue, Ann. De la Soc. d'Agricult.
+de Puy, 1828.</p>
+
+<p><a name="Footnote_AH_9" id="Footnote_AH_9"></a><a href="#FNanchor_AH_9"><span class="label">429-A</span></a> M�m. de la Soc. G�ol. de France, tom. i. p. 175.</p>
+
+<p><a name="Footnote_AH_10" id="Footnote_AH_10"></a><a href="#FNanchor_AH_10"><span class="label">429-B</span></a> See Lyell and Murchison, Ann. de Sci. Nat., Oct. 1829.</p>
+
+<p><a name="Footnote_AH_11" id="Footnote_AH_11"></a><a href="#FNanchor_AH_11"><span class="label">430-A</span></a> See Scrope's Central France, p. 21.</p>
+
+<p><a name="Footnote_AH_12" id="Footnote_AH_12"></a><a href="#FNanchor_AH_12"><span class="label">430-B</span></a> Ibid, p. 7.</p>
+
+<p><a name="Footnote_AH_13" id="Footnote_AH_13"></a><a href="#FNanchor_AH_13"><span class="label">431-A</span></a> Boblaye and Virlet, Morea, p. 23.</p>
+
+<p><a name="Footnote_AH_14" id="Footnote_AH_14"></a><a href="#FNanchor_AH_14"><span class="label">432-A</span></a> De la Beche, Geol. Proceedings, No. 41. p. 196.</p>
+
+<p><a name="Footnote_AH_15" id="Footnote_AH_15"></a><a href="#FNanchor_AH_15"><span class="label">432-B</span></a> "The rock," as English readers of Burn's poems may remember, is a
+Scotch term for distaff.</p>
+
+<p><a name="Footnote_AH_16" id="Footnote_AH_16"></a><a href="#FNanchor_AH_16"><span class="label">435-A</span></a> Murchison, Silurian System, &amp;c. p. 230.</p>
+
+<p><a name="Footnote_AH_17" id="Footnote_AH_17"></a><a href="#FNanchor_AH_17"><span class="label">435-B</span></a> Ibid., p. 272.</p>
+
+<p><a name="Footnote_AH_18" id="Footnote_AH_18"></a><a href="#FNanchor_AH_18"><span class="label">435-C</span></a> Ibid., p. 325.</p>
+
+<p><a name="Footnote_AH_19" id="Footnote_AH_19"></a><a href="#FNanchor_AH_19"><span class="label">435-D</span></a> Chap. XXVII. <a href="#page356">p. 356.</a></p>
+
+<p><a name="Footnote_AH_20" id="Footnote_AH_20"></a><a href="#FNanchor_AH_20"><span class="label">435-E</span></a> Geol. Trans., 2d series, vol. iv. p. 55.</p>
+
+<p><a name="Footnote_AI_1" id="Footnote_AI_1"></a><a href="#FNanchor_AI_1"><span class="label">439-A</span></a> Bulletin, 2d s�rie, iv. 1304.; and Archiac, Hist. des Progr�s de
+Geol., i. 38.</p>
+
+<p><a name="Footnote_AI_2" id="Footnote_AI_2"></a><a href="#FNanchor_AI_2"><span class="label">440-A</span></a> Boase on Primary Geology, p. 16.</p>
+
+<p><a name="Footnote_AI_3" id="Footnote_AI_3"></a><a href="#FNanchor_AI_3"><span class="label">441-A</span></a> Bulletin, vol. iv., 2d ser., pp. 1318. and 1320.</p>
+
+<p><a name="Footnote_AI_4" id="Footnote_AI_4"></a><a href="#FNanchor_AI_4"><span class="label">441-B</span></a> Syst. of Geol., vol. i. p. 157.</p>
+
+<p><a name="Footnote_AI_5" id="Footnote_AI_5"></a><a href="#FNanchor_AI_5"><span class="label">441-C</span></a> Ibid., p. 158.</p>
+
+<p><a name="Footnote_AI_6" id="Footnote_AI_6"></a><a href="#FNanchor_AI_6"><span class="label">442-A</span></a> Geol. Trans., 1st series, vol. iii. pl. 21.</p>
+
+<p><a name="Footnote_AI_7" id="Footnote_AI_7"></a><a href="#FNanchor_AI_7"><span class="label">442-B</span></a> MacCulloch, Geol. Trans., vol. iii. p. 259.</p>
+
+<p><a name="Footnote_AI_8" id="Footnote_AI_8"></a><a href="#FNanchor_AI_8"><span class="label">443-A</span></a> Capt. B. Hall, Trans. Roy. Soc. Edin., vol. vii.</p>
+
+<p><a name="Footnote_AI_9" id="Footnote_AI_9"></a><a href="#FNanchor_AI_9"><span class="label">444-A</span></a> MacCulloch, Syst. of Geol., vol. i. p. 58.</p>
+
+<p><a name="Footnote_AI_10" id="Footnote_AI_10"></a><a href="#FNanchor_AI_10"><span class="label">444-B</span></a> Western Islands, pl. 31.</p>
+
+<p><a name="Footnote_AI_11" id="Footnote_AI_11"></a><a href="#FNanchor_AI_11"><span class="label">444-C</span></a> On Geol. of Cornwall, Camb. Trans. vol. i. p. 124.</p>
+
+<p><a name="Footnote_AI_12" id="Footnote_AI_12"></a><a href="#FNanchor_AI_12"><span class="label">445-A</span></a> Phil. Mag. and Annals, No. 27. new series, March, 1829.</p>
+
+<p><a name="Footnote_AI_13" id="Footnote_AI_13"></a><a href="#FNanchor_AI_13"><span class="label">445-B</span></a> Necker, sur la Val. de Valorsine, M�m. de la Soc. de Phys. de
+G�n�ve, 1828. I visited, in 1832, the spot referred to in fig. 497.</p>
+
+<p><a name="Footnote_AI_14" id="Footnote_AI_14"></a><a href="#FNanchor_AI_14"><span class="label">446-A</span></a> Necker, Proceedings of Geol. Soc., No. 26. p. 392.</p>
+
+<p><a name="Footnote_AI_15" id="Footnote_AI_15"></a><a href="#FNanchor_AI_15"><span class="label">446-B</span></a> See Keilhau's G�a Norvegica; Christiania, 1838.</p>
+
+<p><a name="Footnote_AJ_1" id="Footnote_AJ_1"></a><a href="#FNanchor_AJ_1"><span class="label">450-A</span></a> Silliman's Journ., No. 69. p. 123.</p>
+
+<p><a name="Footnote_AJ_2" id="Footnote_AJ_2"></a><a href="#FNanchor_AJ_2"><span class="label">450-B</span></a> See "Principles," <i>Index</i>, "Jorullo."</p>
+
+<p><a name="Footnote_AJ_3" id="Footnote_AJ_3"></a><a href="#FNanchor_AJ_3"><span class="label">451-A</span></a> "Principles," <i>Index</i>, "Volcanic Eruptions."</p>
+
+<p><a name="Footnote_AJ_4" id="Footnote_AJ_4"></a><a href="#FNanchor_AJ_4"><span class="label">453-A</span></a> Darwin, pp. 390. 406.; second edition, p. 319.</p>
+
+<p><a name="Footnote_AJ_5" id="Footnote_AJ_5"></a><a href="#FNanchor_AJ_5"><span class="label">454-A</span></a> See map of Europe and explanation, in Principles, book i.</p>
+
+<p><a name="Footnote_AJ_6" id="Footnote_AJ_6"></a><a href="#FNanchor_AJ_6"><span class="label">456-A</span></a> Elie de Beaumont, sur les Montagnes de l'Oisans, &amp;c. M�m. de la
+Soc. d'Hist. Nat. de Paris, tom. v.</p>
+
+<p><a name="Footnote_AJ_7" id="Footnote_AJ_7"></a><a href="#FNanchor_AJ_7"><span class="label">456-B</span></a> See Murchison, Geol. Trans., 2d series, vol. ii. part ii. pp.
+311-321.</p>
+
+<p><a name="Footnote_AJ_8" id="Footnote_AJ_8"></a><a href="#FNanchor_AJ_8"><span class="label">456-C</span></a> Western Islands, vol. i. p. 330. plate 18., figs. 3, 4.</p>
+
+<p><a name="Footnote_AJ_9" id="Footnote_AJ_9"></a><a href="#FNanchor_AJ_9"><span class="label">456-D</span></a> Von Buch, Annales de Chimie, &amp;c.</p>
+
+<p><a name="Footnote_AJ_10" id="Footnote_AJ_10"></a><a href="#FNanchor_AJ_10"><span class="label">457-A</span></a> Proceedings of Geol. Soc., vol. ii. p. 562.</p>
+
+<p><a name="Footnote_AJ_11" id="Footnote_AJ_11"></a><a href="#FNanchor_AJ_11"><span class="label">457-B</span></a> See the G�a Norvegica and other works of Keilhau, with whom I
+examined this country.</p>
+
+<p><a name="Footnote_AJ_12" id="Footnote_AJ_12"></a><a href="#FNanchor_AJ_12"><span class="label">459-A</span></a> Murchison, Geol. Trans., 2d series, vol. ii. p. 307.</p>
+
+<p><a name="Footnote_AJ_13" id="Footnote_AJ_13"></a><a href="#FNanchor_AJ_13"><span class="label">459-B</span></a> Geognostische Wanderungen, Leipzig, 1838.</p>
+
+<p><a name="Footnote_AJ_14" id="Footnote_AJ_14"></a><a href="#FNanchor_AJ_14"><span class="label">461-A</span></a> In the above section I have attempted to represent the new
+discoveries made since 1839, by Mr. Necker and Mr. A. C. Ramsay, in regard
+to the plutonic formations, 6. <i>a</i>, and 6. <i>b</i>.</p>
+
+<p><a name="Footnote_AJ_15" id="Footnote_AJ_15"></a><a href="#FNanchor_AJ_15"><span class="label">463-A</span></a> For the geology of Arran consult the works of Drs. Hutton and
+MacCulloch, the Memoirs of Messrs. Von Dechen and Oeynhausen, that of
+Professor Sedgwick and Sir R. Murchison (Geol. Trans. 2d series), Mr. L. A.
+Necker's Memoir, read to the Royal Soc. of Edin. 20th April, 1840, and Mr.
+Ramsay's Geol. of Arran, 1841. I examined myself a large part of Arran in
+1836.</p>
+
+<p><a name="Footnote_AK_1" id="Footnote_AK_1"></a><a href="#FNanchor_AK_1"><span class="label">469-A</span></a> Geol. Trans., 2d series, vol. iii. p. 480.</p>
+
+<p><a name="Footnote_AK_2" id="Footnote_AK_2"></a><a href="#FNanchor_AK_2"><span class="label">469-B</span></a> The Silurian System of Rocks, as developed in Salop, Hereford, &amp;c.,
+p. 245.</p>
+
+<p><a name="Footnote_AK_3" id="Footnote_AK_3"></a><a href="#FNanchor_AK_3"><span class="label">469-C</span></a> Ibid., p. 246.</p>
+
+<p><a name="Footnote_AK_4" id="Footnote_AK_4"></a><a href="#FNanchor_AK_4"><span class="label">470-A</span></a> Introduction to Geology, chap. iv.</p>
+
+<p><a name="Footnote_AK_5" id="Footnote_AK_5"></a><a href="#FNanchor_AK_5"><span class="label">471-A</span></a> Silurian System of Rocks, &amp;c., p. 246.</p>
+
+<p><a name="Footnote_AK_6" id="Footnote_AK_6"></a><a href="#FNanchor_AK_6"><span class="label">471-B</span></a> Report, Brit. Ass., Cork, 1843, p. 60.</p>
+
+<p><a name="Footnote_AK_7" id="Footnote_AK_7"></a><a href="#FNanchor_AK_7"><span class="label">471-C</span></a> Quart. Geol. Journ., vol. iii. p. 87. 1847.</p>
+
+<p><a name="Footnote_AK_8" id="Footnote_AK_8"></a><a href="#FNanchor_AK_8"><span class="label">472-A</span></a> Geol. Obs. on S. America, 1846, p. 168.</p>
+
+<p><a name="Footnote_AK_9" id="Footnote_AK_9"></a><a href="#FNanchor_AK_9"><span class="label">472-B</span></a> Margaric acid is an oleaginous acid, formed from different animal
+and vegetable fatty substances. A margarate is a compound of this acid with
+soda, potash, or some other base, and is so named from its pearly lustre.</p>
+
+<p><a name="Footnote_AK_10" id="Footnote_AK_10"></a><a href="#FNanchor_AK_10"><span class="label">472-C</span></a> Letter to the author, dated Cape of Good Hope, Feb. 20. 1836.</p>
+
+<p><a name="Footnote_AL_1" id="Footnote_AL_1"></a><a href="#FNanchor_AL_1"><span class="label">474-A</span></a> Keilhau, G�a Norvegica, pp. 61-63.</p>
+
+<p><a name="Footnote_AL_2" id="Footnote_AL_2"></a><a href="#FNanchor_AL_2"><span class="label">475-A</span></a> Geol. Manual, p. 479.</p>
+
+<p><a name="Footnote_AL_3" id="Footnote_AL_3"></a><a href="#FNanchor_AL_3"><span class="label">475-B</span></a> Phil. Trans., 1804.</p>
+
+<p><a name="Footnote_AL_4" id="Footnote_AL_4"></a><a href="#FNanchor_AL_4"><span class="label">476-A</span></a> Poggendorf's Annalen, No. xvi., 2d series, vol. iii.</p>
+
+<p><a name="Footnote_AL_5" id="Footnote_AL_5"></a><a href="#FNanchor_AL_5"><span class="label">476-B</span></a> See Principles, <i>Index</i>, "Carbonated Springs," &amp;c.</p>
+
+<p><a name="Footnote_AL_6" id="Footnote_AL_6"></a><a href="#FNanchor_AL_6"><span class="label">476-C</span></a> Hoffmann's Liparischen Inseln, p. 38. Leipzig, 1832.</p>
+
+<p><a name="Footnote_AL_7" id="Footnote_AL_7"></a><a href="#FNanchor_AL_7"><span class="label">477-A</span></a> See Princ. of Geol.; and Bulletin de la Soc. G�ol. de France, tom.
+ii. p. 230.</p>
+
+<p><a name="Footnote_AL_8" id="Footnote_AL_8"></a><a href="#FNanchor_AL_8"><span class="label">477-B</span></a> See Princ. of Geol.; and Daubeny's Volcanos, p. 167.</p>
+
+<p><a name="Footnote_AL_9" id="Footnote_AL_9"></a><a href="#FNanchor_AL_9"><span class="label">477-C</span></a> Jam. Ed. New Phil. Journ., No. 51. p. 43.</p>
+
+<p><a name="Footnote_AL_10" id="Footnote_AL_10"></a><a href="#FNanchor_AL_10"><span class="label">478-A</span></a> Syst. of Geol., vol. i. p. 210.</p>
+
+<p><a name="Footnote_AL_11" id="Footnote_AL_11"></a><a href="#FNanchor_AL_11"><span class="label">478-B</span></a> Ibid., p. 211.</p>
+
+<p><a name="Footnote_AL_12" id="Footnote_AL_12"></a><a href="#FNanchor_AL_12"><span class="label">478-C</span></a> See above, pp. 327, 333.</p>
+
+<p><a name="Footnote_AL_13" id="Footnote_AL_13"></a><a href="#FNanchor_AL_13"><span class="label">479-A</span></a> See Lyell, Quart. Geol. Journ., vol. i. p. 199.</p>
+
+<p><a name="Footnote_AL_14" id="Footnote_AL_14"></a><a href="#FNanchor_AL_14"><span class="label">479-B</span></a> Dr. Boase, Primary Geology, p. 319.</p>
+
+<p><a name="Footnote_AL_15" id="Footnote_AL_15"></a><a href="#FNanchor_AL_15"><span class="label">480-A</span></a> Geol. Trans., 2d series, vol. ii. p. 227.</p>
+
+<p><a name="Footnote_AL_16" id="Footnote_AL_16"></a><a href="#FNanchor_AL_16"><span class="label">480-B</span></a> Darwin, Volcanic Islands, pp. 69, 70.</p>
+
+<p><a name="Footnote_AL_17" id="Footnote_AL_17"></a><a href="#FNanchor_AL_17"><span class="label">480-C</span></a> Geol. Obs. in S. America, p. 167. See also above, p. 471.</p>
+
+<p><a name="Footnote_AL_18" id="Footnote_AL_18"></a><a href="#FNanchor_AL_18"><span class="label">480-D</span></a> Bulletin, vol. iv. p. 1301.</p>
+
+<p><a name="Footnote_AM_1" id="Footnote_AM_1"></a><a href="#FNanchor_AM_1"><span class="label">483-A</span></a> See notices of Savi, Hoffmann, and others, referred to by Bou�,
+Bull. de la Soc. G�ol. de France, tom. v. p. 317.; and tom. iii. p. xliv.;
+also Pilla, cited by Murchison, Quart. Geol. Journ., vol. v. p. 266.</p>
+
+<p><a name="Footnote_AM_2" id="Footnote_AM_2"></a><a href="#FNanchor_AM_2"><span class="label">487-A</span></a> See Principles, <i>Index</i>, "Calcareous Springs."</p>
+
+<p><a name="Footnote_AN_1" id="Footnote_AN_1"></a><a href="#FNanchor_AN_1"><span class="label">489-A</span></a> Principles, &amp;c. chap. iv. 8th ed. p. 49.</p>
+
+<p><a name="Footnote_AN_2" id="Footnote_AN_2"></a><a href="#FNanchor_AN_2"><span class="label">491-A</span></a> Geol. Trans. vol. iv. p. 139.; Trans. Roy. Geol. Society Cornwall,
+vol. ii. p. 90.</p>
+
+<p><a name="Footnote_AN_3" id="Footnote_AN_3"></a><a href="#FNanchor_AN_3"><span class="label">492-A</span></a> Carne, Trans. of Geol. Soc. Cornwall, vol. iii. p. 238.</p>
+
+<p><a name="Footnote_AN_4" id="Footnote_AN_4"></a><a href="#FNanchor_AN_4"><span class="label">492-B</span></a> Fournet, Etudes sur les D�pots Metalliferes.</p>
+
+<p><a name="Footnote_AN_5" id="Footnote_AN_5"></a><a href="#FNanchor_AN_5"><span class="label">493-A</span></a> Geol. Rep. on Cornwall, p. 340.</p>
+
+<p><a name="Footnote_AN_6" id="Footnote_AN_6"></a><a href="#FNanchor_AN_6"><span class="label">493-B</span></a> Principles, ch. xxvii. 8th ed. p. 422.</p>
+
+<p><a name="Footnote_AN_7" id="Footnote_AN_7"></a><a href="#FNanchor_AN_7"><span class="label">496-A</span></a> See Dr. Daubeny's Volcanos.</p>
+
+<p><a name="Footnote_AN_8" id="Footnote_AN_8"></a><a href="#FNanchor_AN_8"><span class="label">496-B</span></a> Bulletin, iv. p. 1278.</p>
+
+<p><a name="Footnote_AN_9" id="Footnote_AN_9"></a><a href="#FNanchor_AN_9"><span class="label">497-A</span></a> R. W. Fox on Mineral Veins, p. 10.</p>
+
+<p><a name="Footnote_AN_10" id="Footnote_AN_10"></a><a href="#FNanchor_AN_10"><span class="label">497-B</span></a> Ibid. p. 38.</p>
+
+<p><a name="Footnote_AN_11" id="Footnote_AN_11"></a><a href="#FNanchor_AN_11"><span class="label">498-A</span></a> I am indebted to Sir H. De la Beche for this information. See also
+maps and sections of Irish Survey.</p>
+
+<p><a name="Footnote_AN_12" id="Footnote_AN_12"></a><a href="#FNanchor_AN_12"><span class="label">498-B</span></a> Sir H. De la Beche, MS. notes on Irish Survey.</p>
+
+<p><a name="Footnote_AN_13" id="Footnote_AN_13"></a><a href="#FNanchor_AN_13"><span class="label">499-A</span></a> Report on Geology of Cornwall, p. 310.</p>
+
+<p><a name="Footnote_AN_14" id="Footnote_AN_14"></a><a href="#FNanchor_AN_14"><span class="label">501-A</span></a> See Principles of Geol., Book 3.</p>
+
+<p><a name="Footnote_AN_15" id="Footnote_AN_15"></a><a href="#FNanchor_AN_15"><span class="label">501-B</span></a> See the author's Anniv. Address to the Geol. Soc. 1837. Proceedings
+of G. S. No. 49. p. 520.</p></div>
+
+
+<hr class="sep1 martop1 marbot1">
+
+
+<div class="box">
+<p class="center ftsize105"><b>Transcriber's Notes:</b></p>
+
+<p class="marbotm05 hweigth">Illustrations have been moved from the middle of a paragraph to the closest
+paragraph break, the following illustrations have been moved to another page:</p>
+<ul class="add3em min3em ftsize95">
+<li><a href="#img157">figure 155</a>: moved from page 179 to <a href="#page178">page 178</a></li>
+<li><a href="#img298">figure 313</a>: moved from page 279 to <a href="#page278">page 278</a></li>
+<li><a href="#img358">figure 379</a>: moved from page 327 to <a href="#page328">page 328</a></li>
+<li><a href="#img477">figure 501</a>: moved from page 452 to <a href="#page451">page 451</a></li>
+<li><a href="#img482">figure 506</a>: moved from page 461 to <a href="#page460">page 460</a></li>
+</ul>
+
+<p>Missing page numbers correspond to moved illustrations and blank pages.</p>
+
+<p>Not all illustrations show the original natural size mentioned in
+the figure captions, they have been rescaled.</p>
+
+<p>In the <a href="#Footnote_AA_7">footnote 336-A</a> lib. or liv. might be printed wrong.</p>
+
+<p>On <a href="#page185">page 185</a> a footnote anchor was added to footnote <a href="#img162">fig. 160</a> 185-A.</p>
+
+<p>On <a href="#page215">page 215</a> an potential anchor for footnote 215-A was guessed and
+added.</p>
+
+<p>On <a href="#page245">page 245</a> an anchor for footnote 245-A was added.</p>
+
+<p>On <a href="#page280">page 280</a> a footnote anchor 280-B was added.</p>
+
+<p>Other than the corrections listed below, printer's inconsistencies in
+spelling, punctuation, hyphenation, and ligature usage have been retained.</p>
+
+<p>The use of capital letters in names, scientific classifications, locations,
+and time periods/eras is not consistent in this book, they have been kept
+as printed and only changed when an obvious error occurred.</p>
+
+<p>The system of abbreviations and punctuation in citations and figure
+captions can vary, the text has been kept as printed and only changed when
+an obvious error occurred.</p>
+
+<p>The punctuation in the index was inconsistent, all commas in listings for
+page numbers have been changed into full stops, they are not specially
+mentioned/marked in the list of changes. The alphabetic order in the
+index is sometimes inconsistent but has been kept as printed.</p>
+
+<p>Pal�om�ryx (<a href="#page178">page 178</a>) is known in the literature by Paleomeryx
+(http://www.paleodatabase.org) as well as Palaeomeryx.</p>
+
+<p>Pal�oniscus is known in the literature as Palaeoniscus.</p>
+
+<p>Inoceramus Cuvieri is today known as Inoceramus cuvieri (ref: Cretaceous
+Fossils of North America).</p>
+
+<p>Different spelling of Ashby de la Zouch (text) and Ashby-de-la-Zouch
+(index) was retained.</p>
+
+<p>Older or unusual forms of spelling of some German and French towns and
+locations have been retained (<i>e.g.</i> Bertrich-Baden&mdash;Bad Bertrich,
+Roderberg&mdash;Rodderberg, Gemunder Maar&mdash;Gem�nder Maar, Boulade&mdash;Boulaide,
+Pont Gibaud&mdash;Pontgibaud, Saarbr�ck&mdash;Saarbr�cken).</p>
+
+<p class="marbotm05 hweigth">The following words have been retained in both versions:</p>
+<ul class="add3em min3em ftsize95">
+<li>Agas. and Agass.</li>
+<li>brachiopod, brachiopods and brachiopoda (as well as with capital
+letters or lower case)</li>
+<li>Bunter Sandstein and Bunter-Sandstein (as well as various combinations
+with Bunter, bunter, sandstein, Sandstein)</li>
+<li>Cheirotherium and Chirotherium as cheirotherian and chirotherian</li>
+<li>Didelphis and Didelphys</li>
+<li>dike/s and dyke/s</li>
+<li>foot-print/s and footprint/s</li>
+<li>foot-marks and footmarks</li>
+<li>gault and Gault</li>
+<li>G/grauwacke and G/grauwack� and their English translations (greywacke)</li>
+<li>greensand and Greensand as well as their variations</li>
+<li>Holoptichius (e.g. Lyell) and Holoptychius (general usage)</li>
+<li>Ichthyolites and Icthyolites</li>
+<li>iron-stones and ironstones</li>
+<li>jaw-bone and jawbone</li>
+<li>Keuper and keuper</li>
+<li>Lias and lias</li>
+<li>Li�ge and Liege</li>
+<li>Muschelkalk and muschelkalk</li>
+<li>non-fossiliferous and nonfossiliferous</li>
+<li>Old Red Sandstone and old red sandstone with all variations</li>
+<li>P/pal�o** and P/paleo** with all variations from paleontological to
+paleozoic</li>
+<li>Pozzolana and Pozzuolana (recent form)</li>
+<li>prim�val and primeval</li>
+<li>qu�qu�versal and qua-quaversal</li>
+<li>Rhinoceros tichorhinus and Rhinoceros tichorinus</li>
+<li>scoria and scori�</li>
+<li>S�nonien and Senonien</li>
+<li>tilestone/s and T/tile-stone/s</li>
+</ul>
+
+<p class="marbotm05 hweigth">The following misprints have been corrected:</p>
+<ul class="add3em min3em ftsize95">
+<li>changed "to recognise rocks" into "to recognize rocks" <a href="#pagevi">page vi</a></li>
+<li>changed "a fresh-water or" into "a freshwater or" <a href="#pageviii">page viii</a></li>
+<li>changed "belong to gasterodous" into "belong to gasteropodous" <a href="#pagex">page x</a></li>
+<li>changed "Ova in a carbonised state." into "Ova in a carbonized state."
+<a href="#pagexi">page xi</a> (<a href="#img004">fig. 523a</a>)</li>
+<li>changed "W�rtembergisch. Naturwissen Jahreshefte" into "W�rtembergisch.
+Naturwissen. Jahreshefte" <a href="#Footnote_B_7">footnote xiii-A</a></li>
+<li>changed "by Herman von Meyer" into "by Herman von Meyer." <a href="#pagexiv">page xiv</a>
+(<a href="#img011">fig. 530</a>)</li>
+<li>changed "near Stuttgart, Wurtemberg." into "near Stuttgart,
+W�rtemberg." <a href="#pagexiv">page xiv</a></li>
+<li>changed "is characterised by" into "is characterized by" <a href="#pagexvi">page xvi</a></li>
+<li>changed "genus Sauricthys, Hybodus," into "genus Saurichthys, Hybodus,"
+<a href="#pagexv">page xv</a></li>
+<li>changed "Sauricthys Mougeotii, is" into "Saurichthys Mougeotii, is"
+<a href="#pagexv">page xv</a></li>
+<li>changed "in the Quader Sand-stein and" into "in the Quadersandstein
+and" <a href="#pagexvi">page xvi</a></li>
+<li>changed "of organisation in fossils" into "of organization in fossils"
+<a href="#pagexix">page xix</a></li>
+<li>changed "or to Plerodactyles" into "or to Pterodactyles" <a href="#pagexix">page xix</a></li>
+<li>changed "class Aves have hither to" into "class Aves have hitherto"
+<a href="#pagexix">page xix</a></li>
+<li>changed "bored by teredina" into "bored by Teredina" <a href="#pagexxiii">page xxiii</a></li>
+<li>changed "near St. Andrew's" into "near St. Andrews" <a href="#pagexxix">page xxix</a></li>
+<li>changed "Sub-marine lava" and into "Submarine lava and" <a href="#pagexxix">page xxix</a></li>
+<li>changed "Granite of Dartmore altering" into "Granite of Dartmoor
+altering" <a href="#pagexxx">page xxx</a></li>
+<li>changed "Concluding remarks 489" into "Concluding remarks 488" <a href="#pagexxxi">page xxxi</a></li>
+<li>changed "occasionally characterised" by into "occasionally
+characterized" by <a href="#page3">page 3</a></li>
+<li>changed "are all characterised" into "are all characterized" <a href="#page5">page 5</a></li>
+<li>changed "Loire, and Ard�che," into "Loire, and Ard�che," <a href="#page5">page 5</a></li>
+<li>changed "Giants' Causeway, called" into "Giant's Causeway, called" <a href="#page6">page 6</a></li>
+<li>changed "cooled and crystallised," into "cooled and crystallized," <a href="#page7">page 7</a></li>
+<li>changed "by Dr. Mac Culloch" into "by Dr. MacCulloch" <a href="#page8">page 8</a></li>
+<li>changed "afterwards super-imposed, and" into "afterwards superimposed,
+and" <a href="#page9">page 9</a></li>
+<li>changed "causes, while super-imposed" into "causes, while superimposed"
+<a href="#page9">page 9</a></li>
+<li>changed "(Green-sand formation.)" into "(Greensand formation.)" <a href="#page16">page 16</a></li>
+<li>changed "annexed fig. (7.)," into "annexed fig. 7.," <a href="#page18">page 18</a></li>
+<li>changed "(Green-sand formation?)" into "(Greensand formation?)" <a href="#page18">page 18</a></li>
+<li>changed "bored by teredina" into "bored by Teredina" <a href="#page21">page 21</a></li>
+<li>changed "great bed of tripoli, Bilin." into "great bed of Tripoli,
+Bilin." <a href="#page25">page 25</a> (<a href="#img028">figs. 19/20</a>)</li>
+<li>changed figure number figure "34" into figure "33" <a href="#page29">page 29</a></li>
+<li>changed "information from icthyolites" into "information from
+ichthyolites" <a href="#page32">page 32</a></li>
+<li>changed "confined to vein-stones." into "confined to veinstones." <a href="#page34">page 34</a></li>
+<li>changed "the drying and skrinking" into "the drying and shrinking"
+<a href="#page63">page 63</a></li>
+<li>changed "conglomerate, N. 2. clay," into" conglomerate, No. 2. clay,"
+<a href="#page67">page 67</a></li>
+<li>changed "described by Dr. Macculloch," into "described by Dr.
+MacCulloch," <a href="#page67">page 67</a></li>
+<li>changed "of Ross-shire. (Macculloch.)" into "of Ross-shire.
+(MacCulloch.)" <a href="#page67">page 67</a> (<a href="#img095">fig. 90</a>)</li>
+<li>changed "Dax, near Bourdeaux" into "Dax, near Bordeaux" <a href="#page72">page 72</a></li>
+<li>changed "indicate the intermittance" into "indicate the intermittence"
+<a href="#page74">page 74</a></li>
+<li>changed figure number "96" to figure "93" <a href="#page75">page 75</a></li>
+<li>changed "Modica, precipitious" into "Modica, precipitous" <a href="#page77">page 77</a></li>
+<li>changed "them by Dr. Macculloch," into "them by Dr. MacCulloch," <a href="#page86">page 86</a></li>
+<li>changed "Dr. Macculloch and" into "Dr. MacCulloch and" <a href="#page87">page 87</a></li>
+<li>changed "have ever re-appeared" into "have ever reappeared" <a href="#page98">page 98</a></li>
+<li>changed "fossilisation of certain" into "fossilization of certain"
+<a href="#page106">page 106</a></li>
+<li>changed "hills called Bruder Holz" into "hills called Bruderholz"
+<a href="#page120">page 120</a></li>
+<li>changed "near Stuttgardt, in" into "near Stuttgart, in" <a href="#page120">page 120</a></li>
+<li>changed "stones have travelled" into "stones have travelled." <a href="#page121">page 121</a></li>
+<li>changed "already characterised by" into "already characterized by"
+<a href="#page124">page 124</a></li>
+<li>changed "neighbourhood of Upsal," into "neighbourhood of Upsala,"
+<a href="#page124">page 124</a></li>
+<li>changed "Isles of sub-aerial glaciers." into "Isles of subaerial
+glaciers." <a href="#page130">page 130</a></li>
+<li>added "BOULDER FORMATION&mdash;continued." to chapter heading <a href="#page131">page 131</a></li>
+<li>changed "its materials rearranged" into "its materials re-arranged"
+<a href="#page136">page 136</a></li>
+<li>changed "chapters 7 and 8.," into "chapters 7. and 8.," <a href="#page139">page 139</a></li>
+<li>changed "to coexist in" into "to co-exist in" <a href="#page147">page 147</a></li>
+<li>changed "class of warm-blodded" into "class of warm-blooded" <a href="#page148">page 148</a></li>
+<li>changed "speces of deer" into "species of deer" <a href="#page154">page 154</a></li>
+<li>changed "skeletons of Magatherium," into "skeletons of Megatherium,"
+<a href="#page157">page 157</a></li>
+<li>changed "student to recognise the" into "student to recognize the"
+<a href="#page159">page 159</a></li>
+<li>changed "b. nat. size of a and b." into "c. nat. size of a and b."
+<a href="#page161">page 161</a> (<a href="#img146">fig. 141</a>)</li>
+<li>changed "overan are a" into "over an area" <a href="#page162">page 162</a></li>
+<li>changed "concretionary rearrangement of" into "concretionary
+re-arrangement of" page <a href="#page164">164</a></li>
+<li>changed "Faseicularia aurantium" into "Fascicularia aurantium" <a href="#page165">page 165</a>
+(<a href="#img150">fig. 148</a>)</li>
+<li>changed "v. exterior." into "a. exterior." <a href="#page165">page 165</a> (<a href="#img150">fig. 148.</a>)</li>
+<li>changed "climates, such a" into "climates, such as" <a href="#page165">page 165</a></li>
+<li>changed "clayslate, and various" into "clay-slate, and various" <a href="#page169">page 169</a></li>
+<li>changed "from the Appenines" into "from the Apennines" <a href="#page168">page 168</a></li>
+<li>changed "17 per cent," into "17 per cent.," <a href="#page172">page 172</a></li>
+<li>changed "beds (Sables inferieurs" into "beds (Sables inf�rieurs" <a href="#page175">page 175</a></li>
+<li>changed "inferieurs et argiles" into "inf�rieurs et argiles" <a href="#page175">page 175</a></li>
+<li>changed "Upper Marine or Fontainbleau" into "Upper Marine or
+Fontainebleau" <a href="#page177">page 177</a></li>
+<li>changed "M. de Koninck of Li�ge" into "M. De Koninck of Li�ge" <a href="#page178">page 178</a></li>
+<li>changed "or Caddice-fly" into "or Caddis-fly" <a href="#page185">page 185</a></li>
+<li>changed "lake of the Lemagne" into "lake of the Limagne" <a href="#page187">page 187</a></li>
+<li>changed "Bagshot and Brocklesham division" into "Bagshot and
+Bracklesham division" <a href="#page190">page 190</a></li>
+<li>changed "Nome of them" into "None of them" <a href="#page192">page 192</a></li>
+<li>changed "genera Emys and Trionix." into "genera Emys and Trionyx."
+<a href="#page192">page 192</a></li>
+<li>changed "Sables Moyens. divide" into "Sables Moyens, divide" <a href="#page193">page 193</a></li>
+<li>changed "of the English Eocenestrata," into "of the English Eocene
+strata," <a href="#page197">page 197</a></li>
+<li>changed "Headen Hill, on" into "Headon Hill, on" <a href="#page197">page 197</a></li>
+<li>changed "Egerton has recognised" into "Egerton has recognized" <a href="#page198">page 198</a></li>
+<li>changed "brown and blueish gray" into "brown and blueish grey" <a href="#page200">page 200</a></li>
+<li>changed "beds Nos. 1, 2. are" into "beds Nos. 1, 2., are" <a href="#page208">page 208</a></li>
+<li>changed "places for mill-stones." into "places for millstones." <a href="#page208">page 208</a></li>
+<li>changed "of D'Orbigny before" into "of d'Orbigny before" <a href="#page208">page 208</a></li>
+<li>changed "sea-cliffs at Stevensklint" into "sea-cliffs at Stevens Klint"
+<a href="#page210">page 210</a></li>
+<li>changed "and Ostrea, vesicularis." into "and Ostrea vesicularis."
+<a href="#page215">page 215</a></li>
+<li>changed "bivalves (figs. 203. 205," into "bivalves (figs. 203, 205,"
+<a href="#page216">page 216</a></li>
+<li>changed "the Dammura of" into "the Dammara of" <a href="#page216">page 216</a></li>
+<li>changed "afterwards recognised by" into "afterwards recognized by"
+<a href="#page216">page 216</a></li>
+<li>changed "of the Radack achipelago," into "of the Radack archipelago,"
+<a href="#page217">page 217</a></li>
+<li>changed "observations of Ferdinand Roemer;" into "observations of
+Ferdinand R�mer;" <a href="#page224">page 224</a></li>
+<li>changed "the marl-stones are" into "the marlstones are" <a href="#page224">page 224</a></li>
+<li>changed "Wealden (see Nos. 5" into "Wealden (see Nos. 5." <a href="#page225">page 225</a></li>
+<li>changed "purely fresh-water origin." into "purely freshwater origin."
+<a href="#page226">page 227</a></li>
+<li>changed "Auvergne (see above, p. 183.)" into "Auvergne (see above, p.
+183.)." <a href="#page228">page 228</a></li>
+<li>changed "genera Trioynx and Emys," into "genera Trionyx and Emys,"
+<a href="#page229">page 229</a></li>
+<li>changed "See Flinder's Voyage." into "See Flinders' Voyage."
+<a href="#Footnote_T_4">footnote 233-A</a></li>
+<li>changed "Author's Annivers. Address," into "Author's Anniv. Address,"
+<a href="#Footnote_T_14">footnote 237-C</a></li>
+<li>changed "those from the Gualt" into "those from the Gault" <a href="#page242">page 242</a></li>
+<li>changed "eological Map of" into "Geological Map of" <a href="#page242">page 242</a> (<a href="#img241">fig. 252</a>)</li>
+<li>changed "(fig. 254.), where" into "(fig. 253.), where" <a href="#page244">page 244</a></li>
+<li>changed "in the north" into "in the North" <a href="#page245">page 245</a></li>
+<li>changed "In the wood-cut" into "In the woodcut" <a href="#page246">page 246</a></li>
+<li>changed "South Downs at Beachy head." into "South Downs at Beachy Head."
+<a href="#page246">page 246</a></li>
+<li>changed "fail to recognise in" into "fail to recognize in" <a href="#page246">page 246</a></li>
+<li>changed "voll. ii. p. 98." into "vol. ii. p. 98." <a href="#Footnote_U_10">footnote 248-A</a></li>
+<li>changed "of clay aud limestone," into "of clay and limestone," <a href="#page258">page 258</a></li>
+<li>changed "Coral rag," into "Coral rag." <a href="#page261">page 261</a> (<a href="#img260">fig. 273</a>)</li>
+<li>changed "in their orginal" into "in their original" <a href="#page264">page 264</a></li>
+<li>changed "says Mr Lycett," into "says Mr. Lycett," <a href="#page266">page 266</a></li>
+<li>changed "such as Pleiosaur," into "such as Plesiosaur," <a href="#page267">page 267</a></li>
+<li>changed "obtained by Dr Buckland" into "obtained by Dr. Buckland"
+<a href="#page268">page 268</a></li>
+<li>changed "that the Thuia," into "that the Thuja," <a href="#page270">page 270</a></li>
+<li>changed "Buckland's Bridgw. Treat." into "Buckland's Bridgew. Treat."
+<a href="#page271">page 271</a> (<a href="#img279">fig. 294</a>)</li>
+<li>changed "lower shales are wel" into "lower shales are well" <a href="#page271">page 271</a></li>
+<li>changed "the Oolitic system generally" into "the Oolitic system
+generally." <a href="#page272">page 272</a></li>
+<li>changed "1/3 nat size." into "1/3 nat. size." <a href="#page273">page 273</a> (<a href="#img286">fig. 301</a>)</li>
+<li>changed "(G. arcuata, Lam)" into "(G. arcuata, Lam.)" <a href="#page274">page 274</a> (<a href="#img289">fig. 304</a>)</li>
+<li>changed "their own predacious race" into "their own predaceous race"
+<a href="#page278">page 278</a></li>
+<li>changed "both of Icthyosaur and Plesiosaur" into "both of Ichthyosaur
+and Plesiosaur" <a href="#page278">page 278</a></li>
+<li>changed "for swimming (see fig. 313.)" into "for swimming (see fig.
+313.)." <a href="#page279">page 279</a></li>
+<li>changed "Sir H. de la Beche," into "Sir H. De la Beche," <a href="#page281">page 281</a></li>
+<li>changed "of the Haute Sa�ne," into "of the Haute-Sa�ne," <a href="#page283">page 283</a></li>
+<li>changed "in Germany-Keupar" into "in Germany-Keuper" <a href="#page286">page 286</a></li>
+<li>changed "Buckland, Bridg. Treat.," into "Buckland, Bridgew. Treat.,"
+<a href="#Footnote_X_1">footnote 286-A</a></li>
+<li>changed calcaire coquillier into "calcaire coquillier." <a href="#page287">page 287</a></li>
+<li>changed "W�rttemberg, and is" into "W�rtemberg, and is" <a href="#page287">page 287</a></li>
+<li>changed "genera Sauricthys and Gyrolepis" into "genera Saurichthys and
+Gyrolepis" <a href="#page287">page 287</a></li>
+<li>changed "near Strazburg, on" into "near Strasburg, on" <a href="#page288">page 288</a></li>
+<li>changed "the "gres bigarr�," or" into "the "gr�s bigarr�," or" <a href="#page288">page 288</a></li>
+<li>changed "vol. v. p. 347" into "vol. v. p. 347." <a href="#Footnote_X_5">footnote 290-B</a></li>
+<li>changed "in the gray, and" into "in the grey, and" <a href="#page294">page 294</a></li>
+<li>changed "with ornithicnites on" into "with ornithichnites on" <a href="#page300">page 300</a></li>
+<li>changed "and botroidal character." into "and botryoidal character."
+<a href="#page302">page 302</a></li>
+<li>changed "the icthyolites which" into "the ichthyolites which" <a href="#page304">page 304</a></li>
+<li>changed "Pygopteris mandibularis" into "Pygopterus mandibularis" <a href="#page305">page 305</a>
+(<a href="#img331">fig. 346</a>)</li>
+<li>changed "Gutbier are Asterophillites" into "Gutbier are Asterophyllites"
+<a href="#page307">page 307</a></li>
+<li>changed "Lepidodendra, Calamites, Asterophillites," into "Lepidodendra,
+Calamites, Asterophyllites," <a href="#page308">page 308</a></li>
+<li>changed "same bands of" into "some bands of" <a href="#page309">page 309</a></li>
+<li>changed "sometimes called fire-stone," into "sometimes called firestone,"
+<a href="#page309">page 309</a></li>
+<li>changed "Geol. Soc Proceedings," into "Geol. Soc. Proceedings,"
+<a href="#Footnote_Z_8">footnote 317-B</a></li>
+<li>changed "f. 4. feet oal" into "f. 4. feet coal." <a href="#page321">page 321</a> (<a href="#img353">fig. 372</a>)</li>
+<li>changed "at an angle of 8�," into "at an angle of 8�." <a href="#page324">page 324</a></li>
+<li>changed "genus called Michroconchus" into "genus called Microconchus"
+<a href="#page324">page 324</a></li>
+<li>changed "of Sigillaria, Lepidodrendon," into "of Sigillaria,
+Lepidodendron," <a href="#page324">page 324</a></li>
+<li>changed "frequently recognised. Thus," into "frequently recognized.
+Thus," <a href="#page324">page 324</a></li>
+<li>changed "be recognised at still" into "be recognized at still" <a href="#page324">page 324</a></li>
+<li>changed "Clay iron-stone.&mdash;Bands and nodules of clay iron-stone" into
+"Clay-iron-stone.&mdash;Bands and nodules of clay-iron-stone" <a href="#page326">page 326</a></li>
+<li>changed Dome-shaped out-crop of into Dome-shaped outcrop of <a href="#page328">page 327</a></li>
+<li>changed "ornithichnites (see p. 297.)." into "ornithichnites (see p.
+327.)." <a href="#page328">page 328</a></li>
+<li>changed "The out-crop of" into "The outcrop of" <a href="#page328">page 328</a></li>
+<li>changed "olifiant gas. The" into "olefiant gas. The" <a href="#page333">page 333</a></li>
+<li>changed "American Journ. of Sci," into "American Journ. of Sci.,"
+<a href="#Footnote_AA_3">footnote 334-A</a></li>
+<li>changed "a neucleus of granite," into "a nucleus of granite," <a href="#page343">page 343</a></li>
+<li>changed "Scale of Holoptychus nobilissimus," into "Scale of
+Holoptychius nobilissimus," <a href="#page344">page 344</a> (<a href="#img374">fig. 395</a>)</li>
+<li>changed "peculiar lamelli-branchiate" into "peculiar lamellibranchiate"
+<a href="#page347">page 347</a></li>
+<li>changed "south from St. Petersburgh." into "south from St. Petersburg."
+<a href="#page348">page 348</a></li>
+<li>changed "of the Astr�a." into "of the Astrea." <a href="#page349">page 349</a></li>
+<li>changed "lowest or mud-stone beds," into "lowest or mudstone beds,"
+<a href="#page352">page 352</a></li>
+<li>changed "showing siphuncle. Ludlow" into "showing siphuncle. Ludlow."
+<a href="#page354">page 354</a> (<a href="#img396">fig. 417</a>)</li>
+<li>changed "the Welch mountains afford." into "the Welsh mountains afford."
+<a href="#page359">page 359</a></li>
+<li>changed "Kleyn Spawen beds," into "Kleyn Spauwen beds," <a href="#page362">page 362</a></li>
+<li>changed "belong to neighboring" into "belong to neighbouring" <a href="#page362">page 362</a></li>
+<li>changed "with gypsum&mdash;Wirtemberg," into "with gypsum&mdash;W�rtemberg,"
+<a href="#page364">page 364</a></li>
+<li>changed "Crinoidians abundant" into "Crinoideans abundant" <a href="#page365">page 365</a></li>
+<li>changed "like chelonians, Ptericthys," into "like chelonians,
+Pterichthys," <a href="#page365">page 365</a></li>
+<li>changed "were recognised as" into "were recognized as" <a href="#page366">page 366</a></li>
+<li>changed "Their igneons origin" into "Their igneous origin" <a href="#page366">page 366</a></li>
+<li>changed "recognised by a peculiar" into "recognized by a peculiar"
+<a href="#page370">page 370</a></li>
+<li>changed "One half I scoriaceous," into "One half is scoriaceous,"
+<a href="#page373">page 373</a></li>
+<li>changed "others are Andesitic," into "others are andesitic," <a href="#page373">page 373</a></li>
+<li>changed "tom. 8. p. 22. 1835." into "tom. 8. p. 22. 1835.)" <a href="#page375">page 375</a></li>
+<li>changed "A green porphyritic rocks" into "A green porphyritic rock"
+<a href="#page376">page 376</a></li>
+<li>changed "Saussurite, a mineral" into "saussurite, a mineral" <a href="#page376">page 376</a></li>
+<li>changed "oxyde of iron." into "oxide of iron." <a href="#page376">page 376</a></li>
+<li>changed "of talc. Burat's" into "of talc. (Burat's" <a href="#page376">page 376</a></li>
+<li>changed "Sub-marine lava and" into "Submarine lava and" <a href="#page378">page 378</a></li>
+<li>changes "much as 20 per cent of" into "much as 20 per cent. of" <a href="#page382">page 382</a></li>
+<li>changed "of Hutt. Theory, s. 253." into "of Hutt. Theory, p. 253."
+<a href="#Footnote_AE_9">footnote 383-B</a></li>
+<li>changed "Giants' Causeway, in Ireland." into "Giant's Causeway, in
+Ireland." <a href="#page384">page 384</a></li>
+<li>changed "bottom of a shallow sea" into "bottom of a shallow sea."
+<a href="#page388">page 388</a></li>
+<li>changed "to larva and" into "to lava and" <a href="#page388">page 388</a></li>
+<li>changed "PORM, STRUCTURE, AND" into "FORM, STRUCTURE, AND" <a href="#page390">page 390</a></li>
+<li>changed "Baranco de las Angustias." into "Barranco de las Angustias."
+<a href="#page391">page 391</a></li>
+<li>changed "lie uncomformably to" into "lie unconformably to" <a href="#page398">page 398</a></li>
+<li>changed "trap-dikes of Etna," into "trap dikes of Etna," <a href="#page401">page 401</a></li>
+<li>changed "the accompanying wood-cut" into "the accompanying woodcut"
+<a href="#page404">page 404</a></li>
+<li>changed "in once instance" into "in one instance" <a href="#page404">page 404</a></li>
+<li>changed "Punto del Nasone on Somma" into "Punta del Nasone on Somma"
+<a href="#page405">page 405</a> (<a href="#img446">fig. 467</a>)</li>
+<li>changed "we recognise the ordinary" into "we recognize the ordinary"
+<a href="#page418">page 418</a></li>
+<li>changed "near St. Andrew's" into "near St. Andrews" <a href="#page422">page 422</a></li>
+<li>changed "crystals of mesotyge" into "crystals of mesotype" <a href="#page431">page 431</a></li>
+<li>changed "H. de la Beche during" into "H. De la Beche during" <a href="#page432">page 432</a></li>
+<li>changed "Geol. Trans, 2d" into "Geol. Trans., 2d" <a href="#Footnote_AH_20">footnote 435-E</a></li>
+<li>changed "silex, thay have" into "silex, they have" <a href="#page439">page 439</a></li>
+<li>changed "except when mineralogicaly" into "except when mineralogically"
+<a href="#page440">page 440</a></li>
+<li>changed "Bontigny's experiments have" into "Boutigny's experiments have"
+<a href="#page441">page 441</a></li>
+<li>changed "mineral camposition-Test" into "mineral composition-Test"
+<a href="#page449">page 449</a></li>
+<li>changed "Granite of Dartmore altering" into "Granite of Dartmoor
+altering" <a href="#page449">page 449</a></li>
+<li>changed "are many vareties" into "are many varieties" <a href="#page450">page 450</a></li>
+<li>changed "the gritz quartzose" into "the grits quartzose" <a href="#page456">page 456</a></li>
+<li>changed "ay at smome" into "may at some" <a href="#page462">page 462</a></li>
+<li>changed "and their synonymes." into "and their synonymies." <a href="#page465">page 465</a></li>
+<li>changed "These aeriform fluids," into "These a�riform fluids," <a href="#page476">page 476</a></li>
+<li>changed "fumeroles have been" into "fumaroles have been" <a href="#page476">page 476</a></li>
+<li>changed "its being nonfossiliferous," into "its being non-fossiliferous,"
+<a href="#page479">page 479</a></li>
+<li>changed "have become matamorphic" into "have become metamorphic" <a href="#page484">page 484</a></li>
+<li>changed "MM. Studer, and Hugi," into "MM. Studer and Hugi," <a href="#page484">page 484</a></li>
+<li>changed "hornblende-schist, chlorine-schist," into "hornblende-schist,
+chlorite-schist," <a href="#page485">page 485</a></li>
+<li>changed "enlarged or reopened." into "enlarged or re-opened." <a href="#page488">page 488</a></li>
+<li>changed "vein of Andreasburg" into "vein of Andreasberg" <a href="#page494">page 494</a></li>
+<li>changed "greenstone, or "toad-stone,"" into "greenstone, or "toadstone,""
+<a href="#page497">page 497</a></li>
+<li>changed "can be recognised in" into "can be recognized in" <a href="#page498">page 498</a></li>
+<li>changed "H. de la Beche during" into "H. De la Beche during" <a href="#page499">page 499</a></li>
+<li>changed "Lithodomi in beaches" into "lithodomi in beaches," <a href="#page502">page 502</a></li>
+<li>changed "Barrarde, M., on trilobites, 358." into "Barrande, M., on
+trilobites, 358." <a href="#page502">page 502</a></li>
+<li>changed "Argile plastiqne, or" into "Argile plastique, or" <a href="#page502">page 502</a></li>
+<li>changed "or inland" into "on inland" <a href="#page502">page 502</a></li>
+<li>changed "on cornish lodes," into "on Cornish lodes," <a href="#page503">page 503</a></li>
+<li>changed "on Sewalik hills," into "on Sew�lik hills," <a href="#page503">page 503</a></li>
+<li>changed "Caryophillia cespitosa, bed" into "Caryophyllia c�spitosa,
+bed" <a href="#page503">page 503</a></li>
+<li>changed "Cystidi� in Silurian rocks, 358." into "Cystide� in Silurian
+rocks, 358." <a href="#page504">page 504</a></li>
+<li>changed "Decken, Prof. von, on reptiles in Saarbr�ck coalfield, 336."
+into "Dechen, Prof. von, on reptiles in Saarbr�ck coal-field, 336."
+<a href="#page505">page 505</a></li>
+<li>changed "France, 176-196." into "France, 176-191." <a href="#page505">page 505</a></li>
+<li>changed "Dou�, M. B. de, on" into "Doue, M. B. de, on" <a href="#page505">page 505</a></li>
+<li>changed "Desroyers, M., on" into "Desnoyers, M., on" <a href="#page505">page 505</a></li>
+<li>changed "on Icthyosaurus, 276." into "on Ichthyosaurus, 276." <a href="#page505">page 505</a></li>
+<li>changed "hill of Gergovla," into "hill of Gergovia," <a href="#page505">page 505</a></li>
+<li>changed "on Cystidi�, 358." into "on Cystide�, 358." <a href="#page505">page 505</a></li>
+<li>changed "Glenroy, parallel" into "Glen Roy, parallel" <a href="#page506">page 506</a></li>
+<li>changed "sienitic, 440." into "syenitic, 440." <a href="#page506">page 506</a></li>
+<li>changed "vesiculosus in Lym-fiord, 33." into "vesiculosus in Lym-Fiord,
+33." <a href="#page506">page 506</a></li>
+<li>changed "Hamilton. Sir W.," into "Hamilton, Sir W.," <a href="#page507">page 507</a></li>
+<li>changed "Hooghley river, analysis" into "Hooghly river, analysis"
+<a href="#page507">page 507</a></li>
+<li>changed "Icthyolites of Old" into "Ichthyolites of Old" <a href="#page507">page 507</a></li>
+<li>changed "Icthyosaurus communis, figure" into "Ichthyosaurus communis,
+figure" <a href="#page507">page 507</a></li>
+<li>changed "period, Volcanic rocks," into "period. Volcanic rocks," <a href="#page507">page 507</a></li>
+<li>changed "Kentish chalk, sandgalls" into "Kentish chalk, sand-galls"
+<a href="#page507">page 507</a></li>
+<li>changed "Limestone, fosslliferous," into "Limestone, fossiliferous,"
+<a href="#page508">page 508</a></li>
+<li>changed "Lochabar, parallel roads" into "Lochaber, parallel roads"
+<a href="#page508">page 508</a></li>
+<li>changed "in cannel coal" into "in Cannel coal" <a href="#page508">page 508</a></li>
+<li>changed "enlarged and reopened, 492." into "enlarged and re-opened,
+492." <a href="#page508">page 508</a></li>
+<li>changed "teeth of. figured," into "teeth of, figured," <a href="#page508">page 508</a></li>
+<li>changed "Mammifer in trlas" into "Mammifer in trias" <a href="#page508">page 508</a></li>
+<li>changed "on Stonefield slate, 266." into "on Stonesfield slate, 266."
+<a href="#page508">page 508</a></li>
+<li>changed "Mososaurus in St. Peter's" into "Mosasaurus in St. Peter's"
+<a href="#page509">page 509</a></li>
+<li>changed "Oeynhansen, M. von, on" into "Oeynhausen, M. von, on" <a href="#page509">page 509</a></li>
+<li>changed "Saarbruck coal field," into "Saarbr�ck coal field," <a href="#page510">page 510</a></li>
+<li>changed "sandpipes near," into "sand-pipes near," <a href="#page509">page 509</a></li>
+<li>changed "St. Andrew's, trap" into "St. Andrews, trap" <a href="#page510">page 510</a></li>
+<li>changed "Plutonic rocks, 7-446." into "Plutonic rocks, 7. 446." <a href="#page510">page 510</a></li>
+<li>changed "Rose, Frof. G.," into "Rose, Prof. G.," <a href="#page510">page 510</a></li>
+<li>changed "of Colebrook Dale," into "of Coalbrook Dale," <a href="#page510">page 510</a></li>
+<li>changed "sandpipes in, 83." into "sand-pipes in, 83." <a href="#page510">page 510</a></li>
+<li>changed "Sandpipes near Maestricht" into "Sand-pipes near Maestricht"
+<a href="#page510">page 510</a></li>
+<li>changed "or sandgalls, term" into "or sand-galls, term" <a href="#page510">page 510</a></li>
+<li>changed "Seacliffs, inland, 71." into "Sea cliffs, inland, 71." <a href="#page510">page 510</a></li>
+<li>changed "Sedgewick, Prof., cited," into "Sedgwick, Prof., cited,"
+<a href="#page510">page 510</a></li>
+<li>changed "Sedgewick, Prof., on" into "Sedgwick, Prof., on" <a href="#page511">page 511</a></li>
+<li>changed "Sewalik Hills, freshwater" into "Sew�lik Hills, freshwater"
+<a href="#page511">page 511</a></li>
+<li>changed "Skapter Jokul, eruption" into "Skaptar Jokul, eruption" <a href="#page511">page 511</a></li>
+<li>changed "Sub-Apennine strata, 105. 166." into "Subapennine strata, 105,
+166." <a href="#page511">page 511</a></li>
+<li>changed "on sand galls, 82." into "on sand-galls, 82." <a href="#page512">page 512</a></li>
+<li>added Header "W." in index <a href="#page512">page 512</a></li>
+<li>changed "Wenlok formation, 354." into "Wenlock formation, 354." <a href="#page512">page 512</a></li>
+<li>changed "Whin-Sil, intrusion of" into "Whin-Sill, intrusion of" <a href="#page512">page 512</a></li>
+<li>changed "on Cystid�, 358." into "on Cystide�, 358." <a href="#page512">page 512</a></li>
+<li>changed "in 'Lavengro.' because" into "in 'Lavengro' because"
+<a href="#pageC">Advertisements</a></li>
+<li>changed "Vols. I-VIII. With" into "Vols. I.-VIII. With" <a href="#pageF">Advertiesements</a></li>
+<li>changed "early religous schools" into "early religious schools"
+<a href="#pageG">Advertisements</a></li>
+<li>changed "its organisation more" into "its organization more"
+<a href="#pageH">Advertisements</a></li>
+<li>changed "with unfagging tread" into "with unflagging tread" <a href="#pageH">Advertisements</a></li>
+<li>changed "of time and money" into "of time and money." <a href="#pageO">Advertisements</a></li>
+<li>changed "A CONDENSED HAND-BOOK OF ALL ENGLAND" into "A CONDENSED
+HANDBOOK OF ALL ENGLAND" <a href="#pageO">Advertisements</a></li>
+<li>changed "Leicester, Bucks Nottinghamshire." into "Leicester, Bucks,
+Nottinghamshire." <a href="#pageO">Advertisements</a></li>
+<li>changed "Warwick, Glocester, Worcester," into "Warwick, Gloucester,
+Worcester," <a href="#pageO">Advertisements</a></li>
+</ul>
+</div>
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of Project Gutenberg's A Manual of Elementary Geology, by Charles Lyell
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author	Roger Frank <rfrank@pglaf.org>	2025-10-14 20:01:28 -0700
committer	Roger Frank <rfrank@pglaf.org>	2025-10-14 20:01:28 -0700
commit	f78f42eaff969a336c839dab881ca4850b21930e (patch)
tree	d8570385812c2b99b296f3c5ef323df547817bea /34350-h