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If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Man and the Glacial Period - -Author: G. Frederick Wright - -Release Date: January 18, 2016 [EBook #50957] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK MAN AND THE GLACIAL PERIOD *** - - - - -Produced by Tom Cosmas from materials provided at The Internet Archive. - - - - - - - - -Transcriber's Note - - -Italic text is denoted by _underscores_. - - - - -THE INTERNATIONAL SCIENTIFIC SERIES - -VOLUME LXIX - - -THE - -INTERNATIONAL SCIENTIFIC SERIES. - -Each book complete in One Volume, 12mo, and bound in Cloth. - - 1. THE FORMS OF WATER IN CLOUDS AND RIVERS, ICE AND GLACIERS. By J. - Tyndall, LL. D., F. R. S. With 35 Illustrations. $1.50. - - 2. PHYSICS AND POLITICS; or, Thoughts on the Application of the - Principles of "Natural Selection" and "Inheritance" to Political - Society. 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D., F. G. S. A. - - - PROFESSOR IN OBERLIN THEOLOGICAL SEMINARY - FORMERLY ASSISTANT ON THE UNITED STATES GEOLOGICAL SURVEY - AUTHOR OF THE ICE AGE IN NORTH AMERICA. - LOGIC OF CHRISTIAN EVIDENCES, ETC. - - - _WITH AN APPENDIX ON TERTIARY MAN_ - By PROF. HENRY W. HAYNES - - - FULLY ILLUSTRATED - - - _SECOND EDITION_ - - - NEW YORK - D. APPLETON AND COMPANY - - 1895 - - -Copyright, 1892, - -By D. APPLETON AND COMPANY. - - - - Electrotyped and Printed - at the Appleton Press, U. S. A. - - -TO - -JUDGE C. C. BALDWIN - -PRESIDENT OF THE WESTERN RESERVE HISTORICAL SOCIETY - -CLEVELAND - -THIS VOLUME IS DEDICATED - -IN RECOGNITION OF - -HIS SAGACIOUS AND UNFAILING INTEREST IN - -THE INVESTIGATIONS WHICH HAVE MADE IT POSSIBLE - - - - -PREFACE TO THE SECOND EDITION. - - -Since, as stated in the Introduction (page 1), the plan of this volume -permitted only "a concise presentation of the facts," it was impossible -to introduce either full references to the illimitable literature of -the subject or detailed discussion of all disputed points. The facts -selected, therefore, were for the most part those upon which it was -supposed there would be pretty general agreement. - -The discussion upon the subject of the continuity of the Glacial period -was, however, somewhat elaborate (see pages 106-121, 311, 324, 332), -and was presented with excessive respect for the authority of those who -maintain the opposite view; all that was claimed (page 110) being that -one might maintain the _unity_ or _continuity_ of the Glacial period -"without forfeiting his right to the respect of his fellow-geologists." -But it already appears that there was no need of this extreme modesty of -statement. On the contrary, the vigorous discussion of the subject which -has characterized the last two years reveals a decided reaction against -the theory that there has been more than one Glacial epoch in Quaternary -times; while there have been brought to light many most important if not -conclusive facts in favour of the theory supported in the volume. - -In America the continuity of the Glacial period has been maintained -during the past two years with important new evidence, among others -by authorities of no less eminence and special experience in glacial -investigations than Professor Dana,[A] Mr. Warren Upham,[B] and Professor -Edward H. Williams, Jr.[C] Professor Williams's investigations on the -attenuated border of the glacial deposits in the Lehigh, the most -important upper tributary to the Delaware Valley, Pa., are of important -significance, since the area which he so carefully studied lies wholly -south of the terminal moraine of Lewis and Wright, and belongs to the -portion of the older drift which Professors Chamberlin and Salisbury -have been most positive in assigning to the first Glacial epoch, which -they have maintained was separated from the second epoch by a length of -time sufficient for the streams to erode rock gorges in the Delaware and -Lehigh Rivers from two hundred to three hundred feet in depth.[D] But -Professor Williams has found that the rock gorges of the Lehigh, and -even of its southern tributaries, had been worn down approximately to -the present depth of that of the Delaware before this earliest period of -glaciation, and that the gorges were filled with the earliest glacial -_débris_. - -[Footnote A: American Journal of Science, vol. xlvi, pp. 327, 330.] - -[Footnote B: American Journal of Science, vols, xlvi, pp. 114-121; xlvii, -pp. 358-365; American Geologist, vols, x, pp. 339-362, especially pp. -361, 362; xiii, pp. 114, 278; Bulletin of the Geological Society of -America, vol. v, pp. 71-86, 87-100.] - -[Footnote C: Bulletin of the Geological Society of America, vol. v, pp. -13-16, 281-296; American Journal of Science, vol. xlvii, pp. 33-36.] - -[Footnote D: See especially Chamberlin, in the American Journal of -Science, vol. xlv, p. 192; Salisbury, in the American Geologist, vol. xi, -p. 18.] - -A similar relation of the glacial deposits of the attenuated border to -the preglacial erosion of the rock gorges of the Alleghany and upper -Ohio Rivers has been brought to light by the joint investigations of Mr. -Frank Leverett and myself in western Pennsylvania, in the vicinity of -Warren, Pa., where, in an area which was affected by only the earliest -glaciation, glacial deposits are found filling the rock channels of -old tributaries to the Alleghany to a depth of from one hundred and -seventy to two hundred and fifty feet, and carrying the preglacial -erosion at that point very closely, if not quite, down to the present -rock bottoms of all the streams. This removes from Professor Chamberlin -a most important part of the evidence of a long interglacial period to -which he had appealed; he having maintained[E] that "the higher glacial -gravels antedated those of the moraine-forming epoch by the measure of -the erosion of the channel through the old drift and the rock, whose mean -depth here is about three hundred feet, of which perhaps two hundred and -fifty feet may be said to be rock," adding that the "excavation that -intervened between the two epochs in other portions of the Alleghany, -Monongahela, and upper Ohio valleys is closely comparable with this." - -[Footnote E: Bulletin 58 of the United States Geological Survey, p. 35; -American Journal of Science, vol. xlv, p. 195.] - -These observations of Mr. Leverett and myself seem to demonstrate the -position maintained in the volume (page 218), namely, that the inner -precipitous rock gorges of the upper Ohio and its tributaries are mainly -_pre_glacial, rather than _inter_glacial. The only way in which Professor -Chamberlin can in any degree break the force of this discovery is by -assuming that in preglacial times the present narrow rock gorges of the -Alleghany and the Ohio were not continuous, but that (as indicated in -the present volume on page 206) the drainage of various portions of that -region was by northern outlets to the Lake Erie basin, leaving, on this -supposition, the _cols_ between two or three drainage areas to be lowered -in glacial or interglacial time. - -On the theory of continuity the erosion of these _cols_ would have been -rapidly effected by the reversed drainage consequent upon the arrival -of the ice-front at the southern shore of the Lake Erie basin. During -all the time elapsing thereafter, until the ice had reached its southern -limit, the stream was also augmented by the annual partial melting of -the advancing glacier which was constantly bringing into the valley -the frozen precipitation of the far north. The distance is from thirty -to seventy miles, so that a moderately slow advance of the ice at that -stage would afford time for a great amount of erosion before sufficient -northern gravel had reached the region to begin the filling of the -gorge.[F] - -[Footnote F: See an elaborate discussion of the subject in its new phases -by Chamberlin and Leverett, in the American Journal of Science, vol. -xlvii, pp. 247-283.] - -Mr. Leverett also presented an important paper before the Geological -Society of America at its meeting at Madison, Wis., in August, 1893, -adducing evidence which, he thinks, goes to prove that the post-glacial -erosion in the earlier drift in the region of Rock River, Ill., was -seven or eight times as much as that in the later drift farther north; -while Mr. Oscar H. Hershey arrives at nearly the same conclusions from -a study of the buried channels in northwestern Illinois.[G] But even -if these estimates are approximately correct--which is by no means -certain--they only prove the length of the Glacial period, and not -necessarily its discontinuity. - -[Footnote G: American Geologist, vol. xii, p. 314f. Other important -evidence to a similar effect is given by Mr. Leverett, in an article on -The Glacial Succession in Ohio, Journal of Geology, vol. i, pp. 129-146.] - -At the same time it should be said that these investigations in western -Pennsylvania somewhat modify a portion of the discussion in the present -volume concerning the effects of the Cincinnati ice-dam. It now appears -that the full extent of the gravel terraces of glacial origin in the -Alleghany River had not before been fully appreciated, since they are -nearly continuous on the two-hundred-foot rock shelf, and are often -as much as eighty feet thick. It seems probable, therefore, that the -Alleghany and upper Ohio gorge was filled with glacial gravel to a depth -of about two hundred and fifty or three hundred feet, as far down at -least as Wheeling, W. Va. If this was the case, it would obviate the -necessity of bringing in the Cincinnati ice-dam (as set forth in pages -212-216) to account directly for all the phenomena in that region, except -as this obstruction at Cincinnati would greatly facilitate the silting up -of the gorge. The simple accumulation of glacial gravel in the Alleghany -gorge would of itself dam up the Monongahela at Pittsburg, so as to -produce the results detailed by Professor White on page 215.[H] - -[Footnote H: For a full discussion of these topics, see paper by -Professor B. C. Jillson, Transactions of the Academy of Science and -Art of Pittsburg, December 8, 1893; G. F. Wright, American Journal of -Science, vol. xlvii, pp. 161-187; especially pp. 177, 178; The Popular -Science Monthly, vol. xlv, pp. 184-198.] - -Of European authorities who have recently favoured the theory of the -continuity of the Quaternary Glacial period, as maintained in the volume, -it is enough to mention the names of Prestwich,[I] Hughes,[J] Kendall,[K] -Lamplugh,[L] and Wallace,[M] of England; Falsan,[N] of France; Holst,[O] -of Sweden; Credner[P] and Diener,[Q] of Germany; and Nikitin[R] and -Kropotkin,[S] of Russia.[T] Among leading authorities still favouring a -succession of Glacial epochs are: Professor James Geikie,[U] of Scotland; -Baron de Geer,[V] of Sweden; and Professor Felix Wahnschaffe,[W] of -Germany. - -[Footnote I: Quarterly Journal of the Geological Society for August, -1887.] - -[Footnote J: American Geologist, vol. viii, p. 241.] - -[Footnote K: Transactions of the Leeds Geological Association for -February 10, 1893.] - -[Footnote L: Quarterly Journal of the Geological Society, August, 1891.] - -[Footnote M: Fortnightly Review, November, 1893, p. 633; reprinted in The -Popular Science Monthly, vol. xliv, p. 790.] - -[Footnote N: La Période glaciaire (Félix Alcan. Paris, 1889).] - -[Footnote O: American Geologist, vol. viii, p. 242.] - -[Footnote P: Ibid., p. 241.] - -[Footnote Q: Ibid., p. 242.] - -[Footnote R: Congrès International d'Archéologie, Moscow, 1892.] - -[Footnote S: Nineteenth Century, January, 1894, p. 151, note.] - -[Footnote T: The volume The Glacial Geology of Great Britain and Ireland, -edited from the unpublished MSS. of the late Henry Carvill Lewis (London, -Longmans, Green & Co., 1894), adds much important evidence in favour of -the continuity of the Glacial epoch; see especially pp. 187, 460, 461, -466.] - -[Footnote U: Transactions of the Royal Society of Edinburgh, vol. xxxvii, -Part I, pp. 127-150.] - -[Footnote V: American Geologist, vol. viii, p. 246.] - -[Footnote W: Forschungen zur deutschen Landes und Volkskunde von Dr. A. -Kirchhoff. Bd. vi, Heft i.] - -When the first edition was issued, two years ago, there seemed to be -a general acceptance of all the facts detailed in it which directly -connected man with the Glacial period both in America and in Europe; -and, indeed, I had studiously limited myself to such facts as had been -so long and so fully before the public that there would seem to be no -necessity for going again into the details of evidence relating to them. -It appears, however, that this confidence was ill-founded; for the -publication of the book seems to have been the signal for a confident -challenge, by Mr. W. H. Holmes, of all the American evidence, with -intimations that the European also was very likely equally defective.[X] -In particular Mr. Holmes denies the conclusiveness of the evidence of -glacial man adduced by Dr. Abbott and others at Trenton, N. J.; Dr. -Metz, at Madisonville, Ohio; Mr. Mills, at Newcomerstown, Ohio; and Miss -Babbitt, at Little Falls, Minn. - -[Footnote X: Journal of Geology, vol. i, pp. 15-37, 147-163; American -Geologist, vol. xi, pp. 219-240.] - -The sum of Mr. Holmes's effort amounts, however, to little more than -the statement that, with a limited amount of time and labour, neither he -nor his assistants had been able to find any implements in undisturbed -gravel in any of these places; and the suggestion of various ways in -which he thinks it possible that the observers mentioned may have been -deceived as to the original position of the implements found. But, as -had been amply and repeatedly published,[Y] Professor J. D. Whitney, -Professor Lucien Carr, Professor N. S. Shaler, Professor F. W. Putnam, -of Harvard University, besides Dr. C. C. Abbott, all expressly and with -minute detail describe finding implements in the undisturbed gravel at -Trenton, which no one denies to be of glacial origin. In the face of -such testimony, which had been before the public and freely discussed -for several years, it is an arduous undertaking for Mr. Holmes to claim -that none of the implements have been found in place, because he and -his assistants (whose opportunities for observation had scarcely been -one twentieth part as great as those of the others) failed to find any. -To see how carefully the original observations were made, one has but -to read the reports to Professor Putnam which have from time to time -appeared in the Proceedings of the Peabody Museum and of the Boston -Society of Natural History,, and which are partially summed up in the -thirty-second chapter of Dr. Abbott's volume on Primitive Industry. - -[Footnote Y: Proceedings of the Boston Society of Natural History, vol. -xxi, January 19, 1881; Report of the Peabody Museum, vol. ii, pp. 44-47; -chap, xxxii of Abbott's Primitive Industry; American Geologist, vol. xi, -pp. 180-184.] - -In the case of the discovery at Newcomerstown, Mr. Holmes is peculiarly -unfortunate in his efforts to present the facts, since, in endeavouring -to represent the conditions under which the implement was found by Mr. -Mills, he has relied upon an imaginary drawing of his own, in which an -utterly impossible state of things is pictured. The claim of Mr. Holmes -in this case, as in the other, is that possibly the gravel in which the -implements were found had been disturbed. In some cases, as in Little -Falls and at Madison ville, he thinks the implements may have worked down -to a depth of several feet by the overturning of trees or by the decay -of the tap-root of trees. A sufficient answer to these suggestions is, -that Mr. Holmes is able to find no instance in which the overturning of -trees has disturbed the soil to a depth of more than three or four feet, -while some of the implements in these places had been found buried from -eight to sixteen feet. Even if, as Mr. Chamberlin suggests,[Z] fifty -generations of trees have decayed on the spot since the retreat of the -ice, it is difficult to see how that would help the matter, since the -effect could not be cumulative, and fifty upturnings of three or four -feet would not produce the results of one upturning of eight feet. -Moreover, at Trenton, where the upturning of trees and the decaying of -tap-roots would have been as likely as anywhere to bury implements, -none of those of flint or jasper (which occur upon the surface by tens -of thousands) are buried more than a foot in depth; while the argillite -implements occur as low down as fifteen or twenty feet. This limitation -of flint and jasper implements to the surface is conclusively shown not -only by Dr. Abbott's discoveries, but also by the extensive excavations -at Trenton of Mr. Ernest Volk, whose collections formed so prominent -a part of Professor Putnam's Palæolithic exhibit at the Columbian -Exposition at Chicago. In the village sites explored by Mr. Volk, -argillite was the exclusive material of the implements found in the lower -strata of gravel. Similar results are indicated by the excavations of Mr. -H. C. Mercer at Point Pleasant, Pa., about twenty miles above Trenton, -where, in the lower strata, the argillite specimens are sixty-one times -more numerous than the jasper are. - -[Footnote Z: American Geologist, vol. xi, p. 188.] - -To discredit the discoveries at Trenton and Newcomerstown, Mr. Holmes -relies largely upon the theory that portions of gravel from the surface -had slid down to the bottom of the terrace, carrying implements with -them, and forming a talus, which, he thinks, Mr. Mills, Dr. Abbott, -and the others have mistaken for undisturbed strata of gravel. In his -drawings Mr. Holmes has even represented the gravel at Newcomerstown -as caving down into a talus without disturbing the strata to any great -extent, and at the same time he speaks slightingly of the promise which I -had made to publish a photograph of the bank as it really was. In answer, -it is sufficient to give, first, the drawing made at the time by Mr. -Mills, to show the general situation of the gravel bank at Newcomerstown, -in which the implement figured on page 252 was found; and, secondly, an -engraving from a photograph of the bank, taken by Mr. Mills after the -discovery of the implement, but before the talus had obscured its face. -The implement was found by Mr. Mills with its point projecting from a -fresh exposure of the terrace, just after a mass, loosened by his own -efforts, had fallen away. The gravel is of such consistency that every -sign of stratification disappears when it falls down, and there could be -no occasion for a mistake even by an ordinary observer, while Mr. Mills -was a well-trained geologist and collector, making his notes upon the -spot.[AA] - -[Footnote AA: The Popular Science Monthly, vol. xliii, pp. 29-39.] - -[Illustration: Height of Terrace exposed, 25 feet. Palæolith was found -14-3/4 feet from surface.] - -[Illustration: Terrace in Newcomerstown, showing where W. C. Mills found -the Palæolithic implement.] - -I had thought at first that Mr. Holmes had made out a better case against -the late Miss Babbitt's discoveries at Little Falls (referred to on -page 254), but in the American Geologist for May, 1894, page 363, Mr. -Warren Upham, after going over the evidence, expresses it as still his -conviction that Mr. Holmes's criticism fails to shake the force of the -original evidence, so that I do not see any reason for modifying any of -the statements made in the body of the book concerning the implements -supposed to have been found in glacial deposits. Yet if I had expected -such an avalanche of criticism of the evidence as has been loosened, I -should at the time have fortified my statements by fuller references, -and should possibly have somewhat enlarged the discussion. But this -seemed then the less necessary, from the fact that Mr. McGee had, in most -emphatic manner, indorsed nearly every item of the evidence adduced by -me, and much more, in an article which appeared in The Popular Science -Monthly four years before the publication of the volume (November, 1888). -In this article he had said: - -"But it is in the aqueo-glacial gravels of the Delaware River at Trenton, -which were laid down contemporaneously with the terminal moraine one -hundred miles farther northward, and which have been so thoroughly -studied by Abbott, that the most conclusive proof of the existence of -glacial man is found" (p. 23). "Excluding all doubtful cases, there -remains a fairly consistent body of testimony indicating the existence of -a widely distributed human population upon the North. American continent -during the later Ice epoch" (p. 24). "However the doubtful cases may be -neglected, the testimony is cumulative, parts of it are unimpeachable, -and the proof of the existence of glacial man seems conclusive" (p. 25). - -In view of the grossly erroneous statements made by Mr. McGee concerning -the Nampa image (described on pages 298, 299), it is necessary for -me to speak somewhat more fully of this important discovery. The -details concerning the evidence were drawn out by me at length in two -communications to the Boston Society of Natural History (referred to on -page 297), which fill more than thirty pages of closely printed matter, -while two or three years before the appearance of the volume the facts -had been widely published in the New York Independent, the Scientific -American, The Nation, Scribner's Magazine, and the Atlantic Monthly, -and in Washington at a meeting of the Geological Society of America -in 1890. In the second communication to the Boston Society of Natural -History an account was given of a personal visit to the Snake River -Valley, largely for the purpose of further investigation of the evidence -brought to my notice by Mr. Charles Francis Adams, and of the conditions -under which the figurine was found. Among the most important results -of this investigation was the discovery of numerous shells under the -lava deposits, which Mr. Dall, of the United States Geological Survey, -identified for me as either post-Tertiary or late Pliocene; thus throwing -the superficial lava deposits of the region into the Quaternary period, -and removing from the evidence the antecedent improbability which would -bear so heavily against it if we were compelled to suppose that the -lava of the Snake River region was all of Tertiary or even of early -Quaternary age. Furthermore, the evidence of the occurrence of a great -_débâcle_ in the Snake River Valley during the Glacial period, incident -upon the bursting of the banks of Lake Bonneville, goes far to remove -antecedent presumptions against the occurrence of human implements in -such conditions as those existing at Nampa (see below, pp. 233-237). - -Mr. McGee's misunderstanding of the evidence on one point is so gross, -that I must make special reference to it. He says[AB] that this image -"is alleged to have been pounded out of volcanic tuff by a heavy drill, -... under a thick Tertiary lava bed." The statement of facts on page -298 bears no resemblance to this representation. It is there stated -that there were but fifteen feet of lava, and that near the surface; -that below this there was nothing but alternating beds of clay and -quicksand, and that the lava is post-Tertiary. The sand-pump I should -perhaps have described more fully in the book, as I had already done in -the communication to the Boston Society of Natural History. It was a -tube eight feet long, with a valve at the bottom three and a half inches -in diameter on the inside. Through this it was the easiest thing in the -world for the object, which is only one inch and a half long, to be -brought up in the quicksand without injury. - -[Footnote AB: Literary Northwest, vol. ii, p. 275.] - -The baseless assertions of Mr. McGee, involving the honesty of Messrs. -Kurtz and Duffes, are even less fortunate and far more reprehensible. "It -is a fact," says Mr. McGee, "that one of the best-known geologists of the -world chanced to visit Nampa while the boring was in progress, and the -figurine and the pretty fiction were laid before him. He recognized the -figurine as a toy such as the neighbouring Indians give their children, -and laughed at the story; whereupon the owner of the object enjoined -secrecy, pleading: 'Don't give me away; I've fooled a lot of fellows -already, and I'd like to fool some more.'"[AC] This well-known geologist, -on being challenged by Professor Claypole[AD] to give "a full, exact, -and certified statement of the conversation" above referred to, proved -to be Major Powell, who responded with the following statement: "In the -fall of 1889 the writer visited Boise City, in Idaho [twenty miles from -Nampa]. While stopping at a hotel, some gentlemen called on him to show -him a figurine which they said they had found in sinking an artesian -well in the neighbourhood, at a depth, if I remember rightly, of more -than three hundred feet.... When this story was told the writer, he -simply jested with those who claimed to have found it. He had known the -Indians that live in the neighbourhood, had seen their children play with -just such figurines, and had no doubt that the little image had lately -belonged to some Indian child, and said the same. While stopping at the -hotel different persons spoke about it, and it was always passed off as -a jest; and various comments were made about it by various people, some -of them claiming that it had given them much sport, and that a good many -tenderfeet had looked at it, and believed it to be genuine; and they -seemed rather pleased that I had detected the hoax."[AE] - -[Footnote AC: American Anthropologist, vol. vi, p. 94: repeated by Mr. -McGee in the Literary Northwest, vol. ii, p. 276.] - -[Footnote AD: The Popular Science Monthly, vol. xlii, p. 773.] - -[Footnote AE: Ibid., vol. xliii, pp. 322, 323.] - -Thus it appears that Major Powell has made no such statement, at least -in public, as Mr. McGee attributes to him. It should be said, also, that -Major Powell's memory is very much at fault when he affirms that there -is a close resemblance between this figurine and some of the children's -playthings among the Pocatello Indians. On the contrary, it would have -been even more of a surprise to find it in the hands of these children -than to find it among the prehistoric deposits on the Pacific coast. - -To most well-informed people it is sufficient to know that no less -high authorities than Mr. Charles Francis Adams and Mr. G. M. Gumming, -General Manager for the Union Pacific line for that district, carefully -investigated the evidence at the time of the discovery, and, knowing -the parties, were entirely satisfied with its sufficiency. It was -also subjected to careful examination by Professor F. W. Putnam, who -discerned, in a deposit of an oxide of iron on various parts of the -image, indubitable evidence that it was a relic which had lain for a long -time in some such condition as was assigned to it in the bottom of the -well--all of which is detailed in the papers referred to below, on page -297. - -Finally, the discovery, both in its character and conditions, is in so -many respects analogous to those made under Table Mountain, near Sonora, -Cal. (described on pages 294-297), that the evidence of one locality adds -cumulative force to that of the other. The strata underneath the lava in -which these objects were found are all indirectly, but pretty certainly, -connected with the Glacial period.[AF] No student of glacial archæology, -therefore, can hereafter afford to disregard these facts from the Pacific -coast. - -[Footnote AF: See below, p. 349.] - -Oberlin, Ohio, _June 2, 1894_. - - - - -PREFACE TO THE FIRST EDITION. - - -The wide interest manifested in my treatise upon The Ice Age in North -America and its Bearing upon the Antiquity of Man (of which a third -edition was issued a year ago), seemed to indicate the desirability of -providing for the public a smaller volume discussing the broader question -of man's entire relation to the Glacial period in Europe as well as in -America. When the demand for such a volume became evident, I set about -preparing for the task by spending, first, a season in special study -of the lava-beds of the Pacific coast, whose relations to the Glacial -period and to man's antiquity are of such great interest; and, secondly, -a summer in Europe, to enable me to compare the facts bearing upon the -subject on both continents. - -Of course, the chapters of the present volume relating to America cover -much of the same ground gone over in the previous treatise; but the -matter has been entirely rewritten and very much condensed, so as to give -due proportions to all parts of the subject. It will interest some to -know that most of the new material in this volume was first wrought over -in my second course of Lowell Institute Lectures, given in Boston during -the month of March last. - -I am under great obligations to Mr. Charles Francis Adams for his aid in -prosecuting investigations upon the Pacific coast of America; and also to -Dr. H. W. Crosskey, of Birmingham, England, and to Mr. G. W. Lamplugh, -of Bridlington, as well as to Mr. C. E. De Rance and Mr. Clement Reid, -of the British Geological Survey, besides many others in England who -have facilitated my investigations; but pre-eminently to Prof. Percy F. -Kendall, of Stockport, who consented to prepare for me the portion of -Chapter VI which relates to the glacial phenomena of the British Isles. I -have no doubt of the general correctness of the views maintained by him, -and little doubt, also, that his clear and forcible presentation of the -facts will bring about what is scarcely less than a revolution in the -views generally prevalent relating to the subject of which he treats. - -For the glacial facts relating to France and Switzerland I am indebted -largely to M. Falsan's valuable compendium, La Période Glaciaire. - -It goes without saying, also, that I am under the deepest obligation -to the works of Prof. James Geikie upon The Great Ice Age and upon -Prehistoric Europe, and to the remarkable volume of the late Mr. James -Croll upon Climate and Time, as well as to the recent comprehensive -geological treatises of Sir Archibald Geikie and Prof. Prestwich. -Finally, I would express my gratitude for the great courtesy of Prof. -Fraipont, of Liége, in assisting me to an appreciation of the facts -relating to the late remarkable discovery of two entire skeletons of -Paleolithic man in the grotto of Spy. - -Comparative completeness is also given to the volume by the appendix on -the question of man's existence during the Tertiary period, prepared by -the competent hand of Prof. Henry W. Haynes, of Boston. - -I trust this brief treatise will be useful not only in _interesting_ -the general public, but in giving a clear view of the present state of -progress in one department of the inquiries concerning man's antiquity. -If the conclusions reached are not as positive as could be wished, still -it is both desirable and important to see what degree of indefiniteness -rests upon the subject, in order that rash speculations may be avoided -and future investigations directed in profitable lines. - -G. Frederick Wright. - -Oberlin, Ohio, _May 1, 1892_. - - - - -CONTENTS. - - - PAGES - CHAPTER I. - Introductory 1-8 - - CHAPTER II. - Existing Glaciers 9-42 - In Europe; in Asia; in Oceanica; in South America; - on the Antarctic Continent; in North America. - - CHAPTER III. - Glacial Motion 43-50 - - CHAPTER IV. - Signs of Past Glaciation 51-65 - - CHAPTER V. - Ancient Glaciers in the Western Hemisphere 66-128 - New England; New York, New Jersey, and Pennsylvania; - the Mississippi Basin; west of the Rocky Mountains. - - CHAPTER VI. - Ancient Glaciers in the Eastern Hemisphere 129-192 - Central and Southern Europe; the British Isles--the - Preglacial Level of the Land, the Great Glacial Centres, - the Confluent Glaciers, the East Anglian Glacier, - the so-called Great Submergence; Northern Europe; - Asia; Africa. - - CHAPTER VII. - Drainage Systems in the Glacial Period 193-241 - In America--Preglacial Erosion, Buried Outlets and - Channels, Ice-dams, Ancient River Terraces; in Europe. - - CHAPTER VIII. - Relics of Man in the Glacial Period 242-301 - In Glacial Terraces of the United States; in Glacial - Terraces of Europe; in Cave Deposits in the British - Isles; in Cave Deposits on the Continent; Extinct - Animals associated with Man; Earliest Man on the - Pacific Coast of North America. - - CHAPTER IX. - The Cause of the Glacial Period 302-331 - - CHAPTER X. - The Date of the Glacial Period 332-364 - - Appendix on the Tertiary Man 365-374 - - Index 375-385 - - - - -LIST OF ILLUSTRATIONS. - - - FIG. PAGE - - 1. Zermatt Glacier 2 - 2. Formation of veined structure 3 - 3, 4. Formation of marginal fissures and veins 4 - 5. Fissures and seracs 4 - 6. Section across glacial valley, showing old lateral moraines 5 - 7. Mont Blanc glacier region 10 - 8. Svartisen Glacier 13 - 9. Floating berg 18 - 10. Iceberg in the Antarctic Ocean 20 - 11. Map of southeastern Alaska 22 - 12. Map of Glacier Bay, Alaska 25 - 13. Front of Muir Glacier 26 - 14. Map of glaciers in the St. Elias Alps 31 - 15. Map of Greenland 33 - 16. Diagram showing the character of glacial motion 43 - 17. Line of most rapid glacial motion 45 - 18. Diagram showing retardation of the bottom of a glacier 46 - 19. Bed-rock scored with glacial marks 52 - 20. Scratched stone from the till of Boston 54 - 21. Typical section of till in Seattle, Wash. 55 - 22. Ideal section showing how the till overlies the stratified - rocks 56 - 23. Vessel Rock, a glacial boulder 56 - 24. Map of Rhône Glacier 58 - 25. Conglomerate boulder found in Boone County, Ky. 63 - 26. Mohegan Rock 72 - 27. Drumlins in Goffstown, N. H. 73 - 28. Map of drumlins in the vicinity of Boston 75 - 29. Section of kame 77 - 30. Map of kames in Andover, Mass. 78 - 31. Longitudinal kames near Hingham, Mass. 79 - 32. Map showing the kames of Maine and southeastern New Hampshire 81 - 33. Western face of the Kettle Moraine near Eagle, Wis. 99 - 34. Section of the east-and-west glacial furrows on Kelly's - Island 103 - 35. Same as the preceding 105 - 36. Section of till near Germantown, Ohio 108 - 37. Moraines of Grape Creek, Col. 123 - 38. Map of North America in the Ice period 127 - 39. Quartzite boulder on Mont Lachat 128 - 40. Map showing glaciated areas in North America and Europe 130 - 41. Maps showing lines of _débris_ extending from the Alps into - the plains of the Po 134 - 42. Section of the Cefn Cave 148 - 43. Map showing moraine between Speeton and Flamborough 156 - 44. Diagram-section near Cromer 166 - 45. Section through the westerly chalk bluff at Trimingham, - Norfolk 162 - 46. Section across Wales 172 - 47. Section of cliff at Flamborough Head 176 - 48. Enlarged section of the shelly sand and surrounding clay - at _B_ in preceding figure 177 - 49. Map showing the glaciated area of Europe 184 - 50. Map showing old channel and mouth of the Hudson 195 - 51. New York Harbor in preglacial times 197 - 52. Section across the valley of the Cuyahoga River 200 - 53. Map of Mississippi River from Fort Snelling to Minneapolis 209 - 54. Map showing the effect of the glacial dam at Cincinnati 213 - 55. Map of Lake Erie-Ontario 219 - 56. Map of Cuyahoga Lake 221 - 57. Section of the lake ridges near Sandusky, Ohio 223 - 58. Map showing stages of recession of the ice in Minnesota 225 - 59. Glacial terrace on Raccoon Creek, in Ohio 227 - 60. Ideal section across a river-bed in drift region 229 - 61. Map of Lakes Bonneville and Lahontan 234 - 62. Parallel roads of Glen Roy 239 - 63. Map showing glacial terraces on the Delaware and - Schuylkill Rivers 243 - 64. Palæolith found by Abbott in New Jersey 244 - 65. Section across the Delaware River at Trenton, N. J. 245 - 66. Section of the Trenton gravel 246 - 67. Face view of argillite implement found by Dr. C. C. Abbott - in 1876. 247 - 68. Argillite implement found by Dr. C. C. Abbott, March, 1879 248 - 69. Chipped pebble of black chert found by Dr. C. L. Metz, - October, 1885 249 - 70. Map showing glaciated area in Ohio 250 - 71. Palæoliths from Newcomerstown and Amiens (face view) 252 - 72. Edge view of the preceding 253 - 73. Section across the Mississippi Valley at Little Falls, Minn. 254 - 74. Quartz implement found by Miss F. E. Babbitt, 1878, at Little - Falls, Minn 255 - 75. Argillite implement found by H. T. Cresson, 1887 259 - 76. General view of Baltimore and Ohio Railroad cut, - Claymont, Del. 260 - 77. Section across valley of the Somme 262 - 78. Mouth of Kent's Hole 268 - 79. Engis skull (reduced) 274 - 80. Comparison of forms of skulls 276 - 81. Skull of the Man of Spy 277 - 82. Tooth of Machairodus neogæus 281 - 83. Perfect tooth of an Elephas 281 - 84. Skull of Hyena spelæa 282 - 85. Celebrated skeleton of mammoth in St. Petersburg Museum 283 - 86. Molar tooth of mammoth 284 - 87. Tooth of Mastodon Americanus 284 - 88. Skeleton of Mastodon Americanus 286 - 89. Skeleton of Rhinoceros tichorhinus 287 - 90. Skull of cave-bear 287 - 91. Skeleton of the Irish elk 288 - 92. Musk-sheep 289 - 93. Reindeer 290 - 94. Section across Table Mountain, Tuolumne County, Cal. 294 - 95. Calaveras skull 295 - 96. Three views of Nampa image, drawn to scale 298 - 97. Map showing Pocatello, Nampa, and the valley of Snake River 299 - 98. Section across the channel of the Stanislaus River 300 - 99. Diagram showing effect of precession 308 - 100. Map showing course of currents in the Atlantic Ocean 314 - 101. Map showing how the land clusters about the north pole 319 - 102. Diagram showing oscillations of land-surface and ice-surface - during the Glacial epoch 323 - 103. Diagram of eccentricity and precession 333 - 104. Map of the Niagara River below the Falls 334 - 105. Section of strata along the Niagara Gorge 336 - 106. Map showing the recession of the Horseshoe Falls since 1842 338 - 107. Section of kettle-hole near Pomp's Pond, Andover, Mass. 345 - 108. Flint-flakes collected by Abbé Bourgeois 368 - - -MAPS. - - TO FACE PAGE - - Contour and glacial map of the British Isles _Frontispiece._ - - Map showing the glacial geology of the United States 66 - - Map of glacial movements in France and Switzerland 132 - - - - -MAN AND THE GLACIAL PERIOD. - - - - -CHAPTER I. - -INTRODUCTORY. - - -That glaciers now exist in the Alps, in the Scandinavian range, in -Iceland, in the Himalayas, in New Zealand, in Patagonia, and in the -mountains of Washington, British Columbia, and southeastern Alaska, and -that a vast ice-sheet envelops Greenland and the Antarctic Continent, -are statements which can be verified by any one who will take the -trouble to visit those regions. That, at a comparatively recent date, -these glaciers extended far beyond their present limits, and that others -existed upon the highlands of Scotland and British America, and at one -time covered a large part of the British Isles, the whole of British -America, and a considerable area in the northern part of the United -States, are inferences drawn from phenomena which are open to every one's -observations. That man was in existence and occupied both Europe and -America during this great expansion of the northern glaciers is proved -by evidence which is now beyond dispute. It is the object of the present -volume to make a concise presentation of the facts which have been -rapidly accumulating during the past few years relating to the Glacial -period and to its connection with human history. - -Before speaking of the number and present extent of existing glaciers, -it will be profitable, however, to devote a little attention to the -definition of terms. - -[Illustration: Fig. 1.--Zermatt Glacier (Agassiz).] - -A _glacier_ is a mass of ice so situated and of such size as to have -motion in itself. The conditions determining the character and rate -of this motion will come up for statement and discussion later. It is -sufficient here to say that ice has a capacity of movement similar to -that possessed by such plastic substances as cold molasses, wax, tar, or -cooling lava. - -The limit of a glacier's _motion_ is determined by the forces which fix -the point at which its final melting takes place. This will therefore -depend upon both the warmth of the weather and upon the amount of ice. -If the ice is abundant, it will move farther into the region of warm -temperature than it will if it is limited in supply. - -Upon ascending a glacier far enough, one reaches a comparatively -motionless part corresponding to the lake out of which a river often -flows. Technically this is called the _névé_. - -_Glacial ice_ is formed from snow where the annual fall is in excess -of the melting power of the sun at that point. Through the influence -of pressure, such as a boy applies to a snow-ball (but which in the -_névé_-field arises from the weight of the accumulating mass), the lower -strata of the _névé_ are gradually transformed into ice. This process, is -also assisted by the moisture which percolates through the snowy mass, -and which is furnished both by the melting of the surface snow and by -occasional rains. - -The division between the _névé_ and the glacier proper is not always -easily determined. The beginnings of the glacial movement--that is, of -the movement of the ice-stream flowing out of the _névé_-field--are -somewhat like the beginnings of the movement of the water from a great -lake into its outlet. The _névé_ is the reservoir from which the glacier -gets both its supply of ice and the impulse which gives it its first -movement. There can not be a glacier without a _névé_-field, as there can -not be a river without a drainage basin. But there may be a _névé_-field -without a glacier--that is, a basin may be partially filled with snow -which never melts completely away, while the equilibrium of forces is -such that the ice barely reaches to the outlet from which the tongue-like -projection (to which the name glacier would be applied) fails to emerge -only because of the lack of material. - -[Illustration: Fig. 2.--Illustrates the formation of veined structure by -pressure at the junction of two branches.] - -A glacier is characterised by both _veins_ and _fissures_. The veins -give it a banded or stratified appearance, blue alternating with -lighter-coloured portions of ice. As these bands are not arranged with -any apparent uniformity in the glacier, their explanation has given -rise to much discussion. Sometimes the veins are horizontal, sometimes -vertical, and at other times at an angle with the line of motion. On -close investigation, however, it is found that the veins are always -at right angles to the line of greatest pressure. This leads to the -conclusion that pressure is the cause of the banded structure. The -blue strata in the ice are those from which the particles of air have -been expelled by pressure; the lighter portions are those in which the -particles are less thoroughly compacted. Snow is but pulverized ice, and -differs in colour from the compact mass for the same reason that almost -all rocks and minerals change their colour when ground into a powder. - -[Illustration: Figs. 3, 4.--Illustrate the formation of marginal fissures -and veins.] - -[Illustration: Fig. 5.--_c_, _c_, show fissures and seracs where the -glacier moves down the steeper portion of its incline; _s_, _s_, show the -vertical structure produced by pressure on the gentler slopes.] - -The _fissures_, which, when of large size, are called _crevasses_, are -formed in those portions of a glacier where, from some cause, the ice -is subjected to slight tension. This occurs especially where, through -irregularities in the bottom, the slope of the descent is increased. The -ice, then, instead of moving in a continuous stream at the top, cracks -open along the line of tension, and wedge-shaped fissures are formed -extending from the top down to a greater or less distance, according to -the degree of tension. Usually, however, the ice remains continuous in -the lower strata, and when the slope is diminished the pressure reunites -the faces of the fissure, and the surface becomes again comparatively -smooth. Where there are extensive areas of tension, the surface of the -ice sometimes becomes exceedingly broken, presenting a tangled mass of -towers, domes, and pinnacles of ice called _seracs_. - -[Illustration: Fig. 6.--Section across Glacial Valley, showing old -Lateral Moraines.] - -Like running water, moving ice is a powerful agent in _transporting_ -rocks and earthy _débris_ of all grades of fineness; but, owing to the -different consistencies of ice and water, there are great differences in -the mode and result of transportation by them. While water can hold in -suspension only the very finest material, ice can bear upon its surface -rocks of the greatest magnitude, and can roll or shove along under it -boulders and pebbles which would be Unaffected except by torrential -currents of water. We find, therefore, a great amount of earthy material -of all sizes upon the top of a glacier, which has reached it very much as -_débris_ reaches the bed of a river, namely, by falling down upon it from -overhanging cliffs, or by land-slides of greater or less extent. Such -material coming into a river would either disappear beneath its surface, -or would form a line of _débris_ along the banks; in both cases awaiting -the gradual erosion and transportation which running water is able to -effect. But, in case of a glacier, the material rests upon the surface of -the ice, and at once begins to partake of its motion, while successive -accessions of material keep up the supply at any one point, so as to form -a train of boulders and other _débris_, extending below the point as far -as the glacial motion continues. - -Such a line of _débris_ is called a _moraine_. When it forms along the -edge of the ice, it is called a _lateral_ moraine. It is easy to see -that, where glaciers come out from two valleys which are tributary to -a larger valley, their inner sides must coalesce below the separating -promontory, and the two lateral moraines will become united and will -move onward in the middle of the surface of the glacier. Such lines of -_débris_ are called _medial_ moraines. These are characteristic of all -extensive glaciers formed by the union of tributaries. There is no limit -to the number of medial moraines, except in the number of tributaries. - -A medial moraine, when of sufficient thickness, protects the ice -underneath it from melting; so that the moraine will often appear to -be much larger than it really is: what seems to be a ridge of earthy -material being in reality a long ridge of ice, thinly covered with earthy -_débris_, sliding down the slanting sides as the ice slowly wastes away -Large blocks of stone in the same manner protect the ice from melting -underneath, and are found standing on pedestals of ice, often several -feet in height. An interesting feature of these blocks is that, when the -pedestal fails, the block uniformly falls towards the sun, since that is -the side on which the melting has proceeded most rapidly. - -If the meteorological forces are so balanced that the foot of a glacier -remains at the same place for any great length of time, there must be a -great accumulation of earthy _débris_ at the stationary point, since the -motion of the ice is constantly bearing its lines of lateral and medial -moraine downwards to be deposited, year by year, at the melting line -along the front. - -Such accumulations are called _terminal_ moraines, and the process of -their formation may be seen at the foot of almost any large glacier. The -pile of material thus confusedly heaped up in front of some of the larger -glaciers of the world is enormous. - -The melting away of the lower part of a glacier gives rise also to -several other characteristic phenomena. Where the foot of a glacier -chances to be on comparatively level land, the terminal moraine often -covers a great extent of ice, and protects it from melting for an -indefinite period of time. When the ice finally melts away and removes -the support from the overlying morainic _débris_, this settles down in -a very irregular manner, leaving enclosed depressions to which there -is no natural outlet. These depressions, from their resemblance to a -familiar domestic utensil, are technically known as _kettle-holes_. The -terminal moraines of ancient glaciers may often be traced by the relative -abundance of these kettle-holes. - -The streams of water arising both from the rainfall and from the melting -of the ice also produce a peculiar effect about the foot of an extensive -glacier. Sometimes these streams cut long, open channels near the end -of the glacier, and sweep into it vast quantities of morainic material, -which is pushed along by the torrential current, and, after being -abraded, rolled, and sorted, is deposited in a delta about its mouth, or -left stranded in long lines between the ice-walls which have determined -its course. At other times the stream has disappeared far back in the -glacier, and plunged into a crevasse (technically called a _moulin_), -whence it flows onwards as a subglacial stream. But in this case the -deposits might closely resemble those of the previous description. In -both cases, when the ice has finally melted away, peculiar ridge-like -deposits of sorted material remain, to mark the temporary line of -drainage. These exist abundantly in most regions which have been covered -with glacial ice, and are referred to in Scotland as _kames_, in Ireland -as _eskers_, and in Sweden as _osars_. In this volume we shall call them -_kames_, and the deltas spread out in front of them will be referred to -as _kame-plains_. - -With this preliminary description of glacial phenomena, we will proceed -to give, first, a brief enumeration and description of the ice-fields -which are still existing in the world; second, the evidences of the -former existence of far more extensive ice-fields; and, third, the -relation of the Glacial period to some of the vicissitudes which have -attended the life of man in the world. - -The geological period of which we shall treat is variously designated by -different writers. By some it is simply called the "post-Tertiary," or -"Quaternary"; by others the term "post-Pliocene" is used, to indicate -more sharply its distinction from the latter portion of the Tertiary -period; by others this nicety of distinction is expressed by the term -"Pleistocene." But, since the whole epoch was peculiarly characterised -by the presence of glaciers, which have not even yet wholly disappeared, -we may properly refer to it altogether under the descriptive name of -"Glacial" period. - - - - -CHAPTER II. - -EXISTING GLACIERS. - - -_In Europe._--Our specific account of existing glaciers naturally begins -with those of the Alps, where Hugi, Charpentier, Agassiz, Forbes, and -Guyot, before the middle of this century, first brought clearly to light -the reality and nature of glacial motion. - -According to Professor Heim, of Zürich, the total area covered by the -glaciers and ice-fields of the Alps is upwards of three thousand square -kilometres (about eleven hundred square miles). The Swiss Alps alone -contain nearly two-thirds of this area. Professor Heim enumerates 1,155 -distinct glaciers in the region. Of these, 144 are in France, 78 in -Italy, 471 in Switzerland, and 462 in Austria. - -Desor describes fourteen principal glacial districts in the Alps, the -westernmost of which is that of Mont Pelvoux, in Dauphiny, and the -easternmost that in the vicinity of the Gross Glockner, in Carinthia. The -most important of the Alpine systems are those which are grouped around -Mont Blanc, Monte Rosa, and the Finsteraarhorn, the two former peaks -being upwards of fifteen thousand feet in height, and the latter upwards -of fourteen thousand. The area covered by glaciers and snow-fields -in the Bernese Oberland, of which Finsteraarhorn is the culminating -point, is about three hundred and fifty square kilometres (a hundred -square miles), and contains the Aletsch Glacier, which is the longest -in Europe, extending twenty-one kilometres (about fourteen miles) from -the _névé_-field to its foot. The Mer de Glace, which descends from Mont -Blanc to the valley of Chamounix, has a length of about eight miles -below the _névé_-field. In all, there are estimated to be twenty-four -glaciers in the Alps which are upwards of four miles long, and six which -are upwards of eight miles in length. The principal of these are the Mer -de Glace, of Chamounix, on Mont Blanc; the Gorner Glacier, near Zermatt, -on Monte Rosa; the lower glacier of the Aar, in the Bernese Oberland; -and the Aletsch Glacier and Glacier of the Rhône, in Vallais; and the -Pasterzen, in Carinthia. - -[Illustration: Fig. 7.--Mount Blanc Glacier Region: _m_, Mer de Glace; -_g_, Du Géant; _l_, Leschaux; _t_, Taléfre; _B_, Bionassay; _b_, Bosson.] - -These glaciers adjust themselves to the width of the valleys down which -they flow, in some places being a mile or more in width, and at others -contracting into much narrower compass. The greatest depth which Agassiz -was able directly to measure in the Aar Glacier was two hundred and -sixty metres (five hundred and twenty-eight feet), but at another point -the depth was estimated by him to be four hundred and sixty metres (or -fifteen hundred and eighty-four feet). - -The glaciers of the Alps are mostly confined to the northern side and -to the higher portions of the mountain-chain, none of them descending -below the level of four thousand feet, and all of them varying slightly -in extent, from year to year, according as there are changes in the -temperature and in the amount of snow-fall. - -The Pyrenees, also, still maintain a glacial system, but it is of -insignificant importance. This is partly because the altitude is much -less than that of the Alps, the culminating point being scarcely more -than eleven thousand feet in height. Doubtless, also, it is partly due to -the narrowness of the range, which does not provide gathering-places for -the snow sufficiently extensive to produce large glaciers. The snow-fall -also is less upon the Pyrenees than upon the Alps. As a consequence of -all these conditions, the glaciers of the Pyrenees are scarcely more -than stationary _névé_-fields lingering upon the north side of the range. -The largest of these is near Bagnères de Luchon, and sends down a short, -river-like glacier. - -In Scandinavia the height of the mountains is also much less than that of -the Alps, but the moister climate and the more northern latitude favours -the growth of glaciers at a much lower level North of the sixty-second -degree of latitude, the plateaus over five thousand feet above the sea -pretty generally are gathering-places for glaciers. From the Justedal a -snow-field, covering five hundred and eighty square miles, in latitude -62°, twenty-four glaciers push outwards towards the German Sea, the -largest of which is five miles long and three-quarters of a mile wide. -The Fondalen snow-field, between latitudes 66° and 67°, covers an -area about equal to that of the Justedal; but, on account of its more -northern position, its glaciers descend through the valleys quite to the -ocean-level. The Folgofon snow-field is still farther south, but, though -occupying an area of only one hundred square miles, it sends down as many -as three glaciers to the sea-level. The total area of the Scandinavian -snow-fields is about five thousand square miles. - -In Sweden Dr. Svenonius estimates that there are, between latitudes 67° -and 68-1/2°, twenty distinct groups of glaciers, covering an area of four -hundred square kilometres (one hundred and forty-four square miles), and -he numbers upwards of one hundred distinct glaciers of small size. - -As is to be expected, the large islands in the Polar Sea north of Europe -and Asia are, to a great extent, covered with _névé_-fields, and numerous -glaciers push out from them to the sea in all directions, discharging -their surplus ice as bergs, which float away and cumber the waters with -their presence in many distant places. - -[Illustration: Fig. 8.--The Svartisen Glacier on the west coast of -Norway, just within the Arctic circle, at the head of a fiord ten miles -from the ocean. The foot of the Glacier is one mile wide, and a quarter -of a mile back from the water. Terminal moraine in front. (Photographed -by Dr. L. C. Warner.)] - -The island of Spitzbergen, in latitude 76° to 81°, is favourably situated -for the production of glaciers, by reason both of its high northern -latitude, and of its relation to the Gulf Stream, which conveys around -to it an excessive amount of moisture, thus ensuring an exceptionally -large snow-fall over the island. The mountainous character of the island -also favours the concentration of the ice-movement into glaciers of vast -size and power. Still, even here, much of the land is free from snow and -ice in summer. But upon the northern portion of the island there is an -extensive table-land, upwards of two thousand feet above the sea, over -which the ice-field is continuous. Four great glaciers here descend to -tide-water in Magdalena Bay. The largest of these presents at the front a -wall of ice seven thousand feet across and three hundred feet high; but, -as the depth of the water is not great, few icebergs of large size break -off and float away from it. - -Nova Zembla, though not in quite so high latitude, has a lower mean -temperature upon the coasts than Spitzbergen. Owing to the absence of -high lands and mountains, however, it is not covered with perpetual snow, -much less with glacial ice, but its level portions are "carpeted with -grasses and flowers," and sustain extensive forests of stunted trees. - -Franz-Josef Land, to the north of Nova Zembla, both contains high -mountains and supports glaciers of great size. Mr. Payer conducted a -sledge party into this land in 1874, and reported that a precipitous wall -of glacial ice, "of more than a hundred feet in height, formed the usual -edge of the coast." But the motion of the ice is very slow, and the ice -coarse-grained in structure, and it bears a small amount only of morainic -material. So low is here the line of perpetual snow, that the smaller -islands "are covered with caps of ice, so that a cross-section would -exhibit a regular flat segment of ice." It is interesting to note, also, -that "many ice-streams, descending from the high _névé_ plateau, spread -themselves out over the mountain-slopes," and are not, as in the Alps, -confined to definite valleys. - -Iceland seems to have been properly named, since a single one of the -snow-fields--that of Vatnajoküll, with an extreme elevation of only six -thousand feet--is estimated by Helland to cover one hundred and fifty -Norwegian square miles (about seven thousand English square miles), while -five other ice-fields (the Langjoküll, the Hofsjoküll, the Myrdalsjoküll, -the Drangajoküll, and the Glamujoküll) have a combined area of ninety-two -Norwegian or about four thousand five hundred English square miles. The -glaciers are supposed by Whitney to have been rapidly advancing for some -time past. - -_In Asia._--Notwithstanding its lofty mountains and its great extent -of territory lying in high latitudes, glaciers are for two reasons -relatively infrequent: 1. The land in the more northern latitudes is low. -2. The dryness of the atmosphere in the interior of the continent is such -that it unduly limits the snow-fall. Long before they reach the central -plateau of Asia, the currents of air which sweep over the continent from -the Indian Ocean have parted with their burdens of moisture, having left -them in a snowy mantle upon the southern flanks of the Himalayas. As a -result, we have the extensive deserts of the interior, where, on account -of the clear atmosphere, there is not snow enough to resist continuously -the intense activity of the unobstructed rays of the sun. - -In spite of their high latitude and considerable elevation above the -sea-level, glaciers are absent from the Ural Mountains, for the range is -too narrow to afford _névé_-fields of sufficient size to produce glaciers -of large extent. - -The Caucasus Mountains present more favourable conditions, and for a -distance of one hundred and twenty miles near their central portion -have an average height of 12,000 feet, with individual peaks rising to -a height of 16,000 feet or more; but, owing to their low latitude, the -line of perpetual snow scarcely reaches down to the 11,000-foot level. So -great are the snow-fields, however, above this height that many glaciers -push their way down through the narrow mountain-gorges as far as the -6,000-foot level. - -The Himalaya Mountains present many favourable conditions for the -development of glaciers of large size. The range is of great extent and -height, thus affording ample gathering-places for the snows, while the -relation of the mountains to the moisture-laden winds from the Indian -Ocean is such that they enjoy the first harvest of the clouds where -the interior of Asia gets only the gleanings. As is to be expected, -therefore, all the great rivers which course through the plains of -Hindustan have their rise in large glaciers far up towards the summits of -the northern mountains. The Indus and the Ganges are both glacial streams -in their origin, as are their larger tributary branches--the Basha, the -Shigar, and the Sutlej. Many of the glaciers in the higher levels of -the Himalaya Mountains where these streams rise have a length of from -twenty-five to forty miles, and some of them are as much as a mile and -a half in width and extend for a long distance, with an inclination as -small as one degree and a half or one hundred and thirty-eight feet to a -mile. - -In the Mustagh range of the western Himalayas there are two adjoining -glaciers whose united length is sixty-five miles, and another not far -away which is twenty-one miles long and from one to two miles wide in its -upper portion. Its lower portion terminates at an altitude of 16,000 feet -above tide, where it is three miles wide and two hundred and fifty feet -thick. - -_Oceanica._---Passing eastward to the islands of the Pacific Ocean, New -Zealand is the only one capable of supporting glaciers. Their existence -on this island seems the more remarkable because of its low latitude -(42° to 45°); but a grand range of mountains rises abruptly from the -water on the western coast of the southern island, culminating in Mount -Cook, 13,000 feet above the sea, and extending for a distance of about -one hundred miles. The extent and height of this chain, coupled with -the moisture of the winds, which sweep without obstruction over so -many leagues of the tropical Pacific, are specially favourable to the -production of ice-fields of great extent. Consequently we find glaciers -in abundance, some of which are not inferior in extent to the larger ones -of the Alps. The Tasman Glacier, described by Haas, is ten miles long -and nearly two miles broad at its termination, "the lower portion for a -distance of three miles being covered with morainic _detritus_." The -Mueller Glacier is about seven miles long and one mile broad in its lower -portion. - -_South America._--In America, existing glaciers are chiefly confined to -three principal centres, namely, to the Andes, south of the equator; to -the Cordilleras, north of central California; and to Greenland. - -In South America, however, the high mountains of Ecuador sustain a few -glaciers above the twelve-thousand-foot level. The largest of these are -upon the eastern slope of the mountains, giving rise to some of the -branches of the Amazon--indeed, on the flanks of Cotopaxi, Chimborazo, -and Illinissa there are some glaciers in close proximity to the equator -which are fairly comparable in size to those of the Alps. - -In Chili, at about latitude 35°, glaciers begin to appear at lower -levels, descending beyond the six-thousand-foot line, while south of this -both the increasing moisture of the winds and the decreasing average -temperature favour the increase of ice-fields and glaciers. Consequently, -as Darwin long ago observed, the line of perpetual snow here descends to -an increasingly lower level, and glaciers extend down farther and farther -towards the sea, until, in Tierra del Fuego, at about latitude 45°, they -begin to discharge their frozen contents directly into the tidal inlets. -Darwin's party surveyed a glacier entering the Gulf of Penas in latitude -46° 50', which was fifteen miles long, and, in one part, seven broad. At -Eyre's Sound, also, in about latitude 48°, they found immense glaciers -coming clown to the sea and discharging icebergs of great size, one of -which, as they encountered it floating outwards, was estimated to be "_at -least_ one hundred and sixty-eight feet in total height." - -In Tierra del Fuego, where the mountains are only from three thousand -to four thousand feet in height and in latitude less than 55°, Darwin -reports that "every valley is filled with streams of ice descending to -the sea-coast," and that the inlets penetrated by his party presented -miniature likenesses of the polar sea. - -[Illustration: Fig. 9.--Floating berg, showing the proportions above and -under the water. About seven feet under water to one above.] - -_Antarctic Continent._--Of the so-called Antarctic Continent little is -known; but icebergs of great size are frequently encountered up to 58° -south latitude, in the direction of Cape Horn, and as far as latitude -33° in the direction of Cape of Good Hope. Nearly all that is known -about this continent was discovered by Sir J. C. Ross during the period -extending from 1839 to 1843, when, between the parallels of 70° and 78° -south latitude, he encountered in his explorations a precipitous mountain -coast, rising from seven thousand to ten thousand feet above tide. -Through the valleys intervening between the mountain-ranges huge glaciers -descended, and "projected in many places several miles into the sea and -terminated in lofty, perpendicular cliffs. In a few places the rocks -broke through their icy covering, by which alone we could be assured that -land formed the nucleus of this, to appearance, enormous iceberg."[AG] - -[Footnote AG: Quoted by Whitney in Climatic Changes, p. 314.] - -Again, speaking of the region in the vicinity of the lofty volcanoes -Terror and Erebus, between ten thousand and twelve thousand feet high, -the same navigator says: - -"We perceived a low, white line extending from its extreme eastern -point, as far as the eye could discern, to the eastward. It presented -an extraordinary appearance, gradually increasing in height as we got -nearer to it, and proving at length to be a perpendicular cliff of ice, -between one hundred and fifty and two hundred feet above the level of -the sea, perfectly flat and level at the top, and without any fissures -or promontories on its even, seaward face. What was beyond it we could -not imagine; for, being much higher than our mast-head, we could not -see anything except the summit of a lofty range of mountains extending -to the southward as far as the seventy-ninth degree of latitude. These -mountains, being the southernmost land hitherto discovered, I felt -great satisfaction in naming after Sir Edward Parry.... Whether Parry -Mountains again take an easterly trending and form the base to which this -extraordinary mass of ice is attached, must be left for future navigators -to determine. If there be land to the southward it must be very remote, -or of much less elevation than any other part of the coast we have seen, -or it would have appeared above the barrier." - -This ice-cliff or barrier was followed by Captain Ross as far as 198° -west longitude, and found to preserve very much the same character during -the whole of that distance. On the lithographic view of this great -ice-sheet given in Ross's work it is described as "part of the South -Polar Barrier, one hundred and eighty feet above the sea-level, one -thousand feet thick, and four hundred and fifty miles in length." - -A similar vertical wall of ice was seen by D'Urville, off the coast of -Adelie Land. He thus describes it: "Its appearance was astonishing. We -perceived a cliff having a uniform elevation of from one hundred to one -hundred and fifty feet, forming a long line extending off to the west.... -Thus for more than twelve hours we had followed this wall of ice, and -found its sides everywhere perfectly vertical and its summit horizontal. -Not the smallest irregularity, not the most inconsiderable elevation, -broke its uniformity for the twenty leagues of distance which we followed -it during the day, although we passed it occasionally at a distance of -only two or three miles, so that we could make out with ease its smallest -irregularities. Some large pieces of ice were lying along the side of -this frozen coast; but, on the whole, there was open sea in the offing." -[AH] - -[Footnote AH: Whitney's Climatic Changes, pp. 315, 316.] - -[Illustration: Fig. 10.--Iceberg in the Antarctic Ocean.] - -_North America._--In North America living glaciers begin to appear in -the Sierra Nevada Mountains, in the vicinity of the Yosemite Park, in -central California. Here the conditions necessary for the production -of glaciers are favourable, namely, a high altitude, snow-fields of -considerable extent, and unobstructed exposure to the moisture-laden -currents of air from the Pacific Ocean. Sixteen glaciers of small size -have been noted among the summits to the east of the Yosemite; but none -of them descend much below the eleven-thousand-foot line, and none of -them are over a mile in length. Indeed, they are so small, and their -motion is so slight, that it is a question whether or not they are to be -classed with true glaciers. - -Owing to the comparatively low elevation of the Sierra Nevada north of -Tuolumne County, California, no other living glaciers are found until -reaching Mount Shasta, in the extreme northern part of the State. This -is a volcanic peak, rising fourteen thousand five hundred feet above the -sea, and having no peaks within forty miles of it as high as ten thousand -feet; yet so abundant is the snow-fall that as many as five glaciers are -found upon its northern side, some of them being as much as three miles -long and extending as low down as the eight-thousand-foot level. Upon the -southern side glaciers are so completely absent that Professor Whitney -ascended the mountain and remained in perfect ignorance of its glacial -system. In 1870 Mr. Clarence King first discovered and described them on -the northern side. - -North of California glaciers characterise the Cascade Range in increasing -numbers all the way to the Alaskan Peninsula. They are to be found upon -Diamond Peak, the Three Sisters, Mount Jefferson, and Mount Hood, in -Oregon, and appear in still larger proportions upon the flanks of Mount -Rainier (or Tacoma) and Mount Baker, in the State of Washington. The -glacier at the head of the White River Valley is upon the north side of -Rainier, and is the largest one upon that mountain, reaching down to -within five thousand feet of the sea-level, and being ten miles or more -in length. All the streams which descend the valleys upon this mountain -are charged with the milky-coloured water which betrays their glacial -origin. - -[Illustration: Fig. 11.--Map of Southeastern Alaska. The arrow-points -mark glaciers.] - -In British Columbia, Glacier Station, upon the Canadian Pacific Railroad, -in the Selkirk Mountains, is within half a mile of the handsome -Illicilliwaet Glacier, while others of larger size are found at no great -distance. The interior farther north is unexplored to so great an extent -that little can be definitely said concerning its glacial phenomena. The -coast of British Columbia is penetrated by numerous fiords, each of which -receives the drainage of a decaying glacier; but none are in sight of the -tourist-steamers which thread their way through the intricate network of -channels characterising this coast, until the Alaskan boundary is crossed -and the mouth of the Stickeen River is passed. - -A few miles up from the mouth of the Stickeen, however, glaciers of -large size come down to the vicinity of the river, both from the north -and from the south, and the attention of tourists is always attracted -by the abundant glacial sediment borne into the tide-water by the river -itself and discolouring the surface for a long distance beyond the -outlet. Northward from this point the tourist is rarely out of sight of -ice-fields. The Auk and Patterson Glaciers are the first to come into -view, but they do not descend to the water-level. On nearing Holcomb -Bay, however, small icebergs begin to appear, heralding the first of the -glaciers which descend beyond the water's edge. Taku Inlet, a little -farther north, presents glaciers of great size coming down to the -sea-level, while the whole length of Lynn Canal, from Juneau to Chilkat, -a distance of eighty miles, is dotted on both sides by conspicuous -glaciers and ice-fields. - -The Davidson Glacier, near the head of the canal, is one of the most -interesting for purposes of study. It comes down from an unknown -distance in the western interior, bearing two marked medial moraines upon -its surface. On nearing tide-level, the valley through which it flows is -about three-quarters of a mile in width; but, after emerging from the -confinement of the valley, the ice spreads out over a fan-shaped area -until the width of its front is nearly three miles. The supply of ice -not being sufficient to push the front of the glacier into deep water, -equilibrium between the forces of heat and cold is established near the -water's edge. Here, as from year to year the ice melts and deposits its -burdens of earthy _débris_, it has piled up a terminal moraine which -rises from two hundred to three hundred feet in height, and is now -covered with evergreen trees of considerable size. From Chilkat, at the -head of Lynn Canal, to the sources of the Yukon River, the distance is -only thirty-five miles, but the intervening mountain-chain is several -thousand feet in height and bears numerous glaciers upon its seaward side. - -About forty miles west of Lynn Canal, and separated from it by a range -of mountains of moderate height, is Glacier Bay, at the head of one of -whose inlets is the Muir Glacier, which forms the chief attraction for -the great number of tourists that now visit the coast of southeastern -Alaska during the summer season. This glacier meets tide-water in -latitude 58° 50', and longitude 136° 40' west of Greenwich. It received -its name from Mr. John Muir, who, in company with Rev. Mr. Young, made -a tour of the bay and discovered the glacier in 1879. It was soon found -that the bay could be safely navigated by vessels of large size, and from -that time on tourists in increasing number have been attracted to the -region. Commodious steamers now regularly run close up to the ice-front, -and lie-to for several hours, so that the passengers may witness the -"calving" of icebergs, and may climb upon the sides of the icy stream -and look into its deep crevasses and out upon its corrugated and broken -surface. - -[Illustration: Fig. 12.--Map of Glacier Bay. Alaska, and its -surroundings. Arrow-points indicate glaciated area.] - -The first persons who found it in their way to pay more than a tourist's -visit to this interesting object were Rev. J. L. Patton, Mr. Prentiss -Baldwin, and myself, who spent the entire month of August, 1886, encamped -at the foot of the glacier, conducting such observations upon it as -weather and equipment permitted. From that time till the summer of 1890 -no one else stopped off from the tourist steamers to bestow any special -study upon it. But during this latter season Mr. Muir returned to the -scene of his discovered wonder, and spent some weeks in exploring the -interior of the great ice-field. During the same season, also, Professors -H. F. Reid and H. Cushing, with a well-equipped party of young men, -spent two months or more in the same field, conducting observations and -experiments, of various kinds, relating to the extent, the motion, and -the general behaviour of the vast mass of moving ice. - -[Illustration: Fig. 13.--Shows central part of the front of Muir Glacier -one half mile distant. Near the lower left hand corner the ice is seen -one mile distant resting for about one half mile on gravel which it had -overrun. The ice is now retreating in the channel. (From photograph.)] - -The main body of the Muir Glacier occupies a vast amphitheatre, with -diameters ranging from thirty to forty miles, and covers an area of about -one thousand square miles. From one of the low mountains near its mouth I -could count twenty-six tributary glaciers which came together and became -confluent in the main stream of ice. Nine medial moraines marked the -continued course of as many main branches, which becoming united formed -the grand trunk of the glacier. Numerous rocky eminences also projected -above the surface of the ice, like islands in the sea, corresponding to -what are called "_nunataks_" in Greenland. The force of the ice against -the upper side of these rocky prominences is such as to push it in great -masses above the surrounding level, after the analogy of waves which -dash themselves into foam against similar obstructions. In front of the -_nunataks_ there is uniformly a depression, like the eddies which appear -in the current below obstacles in running water. - -Over some portions of the surface of the glacier there is a miniature -river system, consisting of a main stream, with numerous tributaries, -but all flowing in channels of deep blue ice. Before reaching the front -of the glacier, however, each one of these plunges down into a crevasse, -or _moulin_, to swell the larger current, which may be heard rushing -along in an impetuous course hundreds of feet beneath, and far out of -sight. The portion of the glacier in which there is the most rapid -motion is characterised by innumerable crags and domes and pinnacles of -ice, projecting above the general level, whose bases are separated by -fissures, extending in many cases more than a hundred feet below the -general level. These irregularities result from the combined effect -of the differential motion (as illustrated in the diagram on page 4), -and the influence of sunshine and warm air in irregularly melting the -unprotected masses. The description given in our introductory chapter of -medial moraines and ice-pillars is amply illustrated everywhere upon the -surface of the Muir Glacier. I measured one block of stone which was -twenty feet square and about the same height, standing on a pedestal of -ice three or four feet high. - -The mountains forming the periphery of this amphitheatre rise to a height -of several thousand feet; Mount Fairweather, upon the northwest, from -whose flanks probably a portion of the ice comes, being, in fact, more -than fifteen thousand feet high. The mouth of the amphitheatre is three -miles wide, in a line extending from shoulder to shoulder of the low -mountains which guard it. The actual water-front where the ice meets -tide-water is one mile and a half.[AI] Here the depth of the inlet is so -great that the front of the ice breaks off in icebergs of large size, -which float away to be dissolved at their leisure. At the water's edge -the ice presents a perpendicular front of from two hundred and fifty to -four hundred feet in height, and the depth of the water in the middle of -the inlet immediately in front of the ice is upwards of seven hundred -feet; thus giving a total height to the precipitous front of a thousand -feet. - -[Footnote AI: These are the measurements of Professor Reid. In my former -volume I have given the dimensions as somewhat smaller.] - -The formation of icebergs can here be studied to admirable advantage. -During the month in which we encamped in the vicinity the process -was going on continuously. There was scarcely an interval of fifteen -minutes during the whole time in which the air was not rent with the -significant boom connected with the "calving" of a berg. Sometimes this -was occasioned by the separation of a comparatively small mass of ice -from near the top of the precipitous wall, which would fall into the -water below with a loud splash. At other times I have seen a column of -ice from top to bottom of the precipice split off and fall over into the -water, giving rise to great waves, which would lash the shore with foam -two miles below. - -This manner of the production of icebergs differs from that which has -been ordinarily represented in the text-books, but it conforms to the law -of glacial motion, which we will describe a little later, namely, that -the upper strata of ice move faster than the lower. Hence the tendency -is constantly to push the upper strata forwards, so as to produce -a perpendicular or even projecting front, after the analogy of the -formation of breakers on the shelving shore of a large body of water. - -Evidently, however, these masses of ice which break off from above the -water do not reach the whole distance to the bottom of the glacier below -the water; so that a projecting foot of ice remains extending to an -indefinite distance underneath the surface. But at occasional intervals, -as the superincumbent masses of ice above the surface fall off and -relieve the strata below of their weight, these submerged masses suddenly -rise, often shooting up considerably higher than they ultimately remain -when coming to rest. The bergs formed by this latter process often bear -much earthy material upon them, which is carried away with the floating -ice, to be deposited finally wherever the melting chances to take place. - -Numerous opportunities are furnished about the front and foot of -this vast glacier to observe the manner of the formation of _kames_, -kettle-holes, and various other irregular forms into which glacial -_débris_ is accustomed to accumulate. Over portions of the decaying -foot of the glacier, which was deeply covered with morainic _débris_, -the supporting ice is being gradually removed through the influence of -subglacial streams or of abandoned tunnels, which permit the air to exert -its melting power underneath. In some places where old _moulins_ had -existed, the supporting ice is melting away, so that the superincumbent -mass of sand, gravel, and boulders is slowly sliding into a common -centre, like grain in a hopper. This must produce a conical hill, to -remain, after the ice has all melted away, a mute witness of the -impressive and complicated forces which have been so long in operation -for its production. - -In other places I have witnessed the formation of a long ridge of gravel -by the gradual falling in of the roof of a tunnel which had been occupied -by a subglacial stream, and over which there was deposited a great amount -of morainic material. As the roof gave way, this was constantly falling -to the bottom, where, being exempt from further erosive agencies, it must -remain as a gravel ridge or kame. - -In other places, still, there were vast masses of ice covering many -acres, and buried beneath a great depth of morainic material which had -been swept down upon it while joined to the main glacier. In the retreat -of the ice, however, these masses had become isolated, and the sand, -gravel, and boulders were sliding down the wasting sides and forming long -ridges of _débris_ along the bottom, which, upon the final melting of -the ice, will be left as a complicated network of ridges and knolls of -gravel, enclosing an equally complicated nest of kettle-holes. - -Beyond Cross Sound the Pacific coast is bounded for several hundred -miles by the magnificent semicircle of mountains known as the St. Elias -Alps, with Mount Crillon at the south, having an elevation of nearly -sixteen thousand feet, and St. Elias in the centre, rising to a greater -height. Everywhere along this coast, as far as the Alaskan Peninsula, -vast glaciers come down from the mountain-sides, and in many cases their -precipitous fronts form the shore-line for many miles at a time. Icy -Bay, just to the south of Mount St, Elias, is fitly named, on account of -the extent of the glaciers emptying into it and the number of icebergs -cumbering its waters. - -In the summer of 1890 a party, under the lead of Mr. I. C. Russell, of -the United States Geological Survey, made an unsuccessful attempt to -scale the heights of Mount St. Elias; but the information brought back -by them concerning the glaciers of the region amply repaid them for their -toil and expense, and consoled them for the failure of their immediate -object. - -[Illustration: Fig. 14.--By the courtesy of the National Geographical -Society.] - -Leaving Yakutat Bay, and following the route indicated upon the -accompanying map, they travelled on glacial ice almost the entire -distance to the foot of Mount St. Elias. The numerous glaciers coming -down from the summit of the mountain-ridge become confluent nearer the -shore, and spread out over an area of about a thousand square miles. This -is fitly named the Malaspina Glacier, after the Spanish explorer who -discovered it in 1792. - -It is not necessary to add further particulars concerning the results -of this expedition, since they are so similar to those already detailed -in connection with the Muir Glacier. A feature, however, of special -interest, pertains to the glacial lakes which are held in place by the -glacial ice at an elevation of thousands of feet above the sea. One of -considerable size is indicated upon the map just south of what was called -Blossom Island, which, however, is not an island, but simply a _nunatak_, -the ice here surrounding a considerable area of fertile land, which is -covered with dense forests and beautified by a brilliant assemblage of -flowering plants. In other places considerable vegetation was found upon -the surface of moraines, which were probably still in motion with the -underlying ice. - -_Greenland._--The continental proportions of Greenland, and the extent -to which its area is covered by glacial ice, make it by far the most -important accessible field for glacial observations. The total area of -Greenland can not be less than five hundred thousand square miles--equal -in extent to the portion of the United States east of the Mississippi -and north of the Ohio. It is now pretty evident that the whole of this -area, except a narrow border about the southern end, is covered by one -continuous sheet of moving ice, pressing outward on every side towards -the open water of the surrounding seas. - -For a long time it was the belief of many that a large region in the -interior of Greenland was free from ice, and was perhaps inhabited. -It was in part to solve this problem that Baron Nordenskiöld set out -upon his expedition of 1883. Ascending the ice-sheet from Disco Bay, in -latitude 69°, he proceeded eastward for eighteen days across a continuous -ice-field. Rivers were flowing in channels upon the surface like those -cut on land in horizontal strata of shale or sandstone, only that the -pure deep blue of the ice-walls was, by comparison, infinitely more -beautiful. These rivers were not, however, perfectly continuous. After -flowing for a distance in channels on the surface, they, one and all, -plunged with deafening roar into some yawning crevasse, to find their way -to the sea through subglacial channels. Numerous lakes with shores of ice -were also encountered. - -[Illustration: Fig. 15.--Map of Greenland. The arrow-points mark the -margin of the ice-field.] - -"On bending down the ear to the ice," says this explorer, "we could hear -on every side a peculiar subterranean hum, proceeding from rivers flowing -within the ice; and occasionally a loud, single report, like that of a -cannon, gave notice of the formation of a new glacier-cleft.... In the -afternoon we saw at some distance from us a well-defined pillar of mist, -which, when we approached it, appeared to rise from a bottomless abyss, -into which a mighty glacier-river fell. The vast, roaring water-mass had -bored for itself a vertical hole, probably down to the rock, certainly -more than two thousand feet beneath, on which the glacier rested."[AJ] - -[Footnote AJ: Geological Magazine, vol. ix, pp. 393, 399.] - -At the end of the eighteen days Nordenskiöld found himself about a -hundred and fifty miles from his starting-point, and about five thousand -feet above the sea. Here the party rested, and sent two Eskimos forward -on _skidor_--a kind of long wooden skate, with which they could move -rapidly over the ice, notwithstanding the numerous small, circular holes -which everywhere pitted the surface. These Eskimos were gone fifty-seven -hours, having slept only four hours of the period. It is estimated that -they made about a hundred and fifty miles, and attained an altitude of -six thousand feet. The ice is reported as rising in distinct terraces, -and as seemingly boundless beyond. If this is the case, two hundred miles -from Disco Bay, there would seem little hope of finding in Greenland -an interior freed from ice. So we may pretty confidently speak of that -continental body of land as still enveloped in an ice-sheet. Up to about -latitude 75°, however, the continent is fringed by a border of islands, -over which there is no continuous covering of ice. In south Greenland -the continuous ice-sheet is reached about thirty miles back from the -shore. - -A summary of the results of Greenland exploration was given by Dr. Kink -in 1886, from which it appears that since 1876 one thousand miles of -the coast-line have been carefully explored by entering every fiord and -attempting to reach the inland ice. According to this authority-- - -We are now able to demonstrate that a movement of ice from the central -regions of Greenland to the coast continually goes on, and must be -supposed to act upon the ground over which it is pushed so as to detach -and transport fragments of it for such a distance.... The plainest idea -of the ice-formation here in question is given by comparing it with an -inundation.... Only the marginal parts show irregularity; towards the -interior the surface grows more and more level and passes into a plain -very slightly rising in the same direction. It has been proved that, -ascending its extreme verge, where it has spread like a lava-stream over -the lower ground in front of it, the irregularities are chiefly met with -up to a height of 2,000 feet, but the distance from the margin in which -the height is reached varies much. While under 68-1/2° north latitude it -took twenty-four miles before this elevation was attained, in 72-1/2° the -same height was arrived at in half the distance.... - -A general movement of the whole mass from the central regions towards the -sea is still continued, but it concentrates its force to comparatively -few points in the most extraordinary degree. These points are represented -by the ice-fiords, through which the annual surplus ice is carried off -in the shape of bergs.... In Danish Greenland are found five of the -first, four of the second, and eight of the third (or least productive) -class, besides a number of inlets which only receive insignificant -fragments. Direct measurements of the velocity have now been applied on -three first-rate and one second-rate fiords, all situated between 69° -and 71° north latitude. The measurements have been repeated during the -coldest and the warmest season, and connected with surveying and other -investigations of the inlets and their environs. It is now proved that -the glacier branches which produce the bergs proceed incessantly at a -rate of thirty to fifty feet per diem, this movement being not at all -influenced by the seasons. . . . - -In the ice-fiord of Jakobshavn, which spreads its enormous bergs over -Disco Bay and probably far into the Atlantic, the productive part of the -glacier is 4,500 metres (about 2-1/2 miles) broad. The movement along its -middle line, which is quicker than on the sides nearer the shores, can -be rated at fifty feet per diem. The bulk of ice here annually forced -into the sea would, if taken on the shore, make a mountain two miles -long, two miles broad, and 1,000 feet high. The ice-fiord of Torsukatak -receives four or five branches of the glacier; the most productive of -them is about 9,000 metres broad (five miles), and moves between sixteen -and thirty-two feet per diem. The large Karajak Glacier, about 7,000 -metres (four miles) broad, proceeds at a rate of from twenty-two to -thirty-eight feet per diem. Finally, a glacier branch dipping into the -fiord of Jtivdliarsuk, 5,800 metres broad (three miles), moved between -twenty-four and forty-six feet per diem.[AK] - -[Footnote AK: See Transactions of the Edinburgh Geological Society for -February 18, 1886, vol. v, part ii, pp. 286-293.] - -The principal part of our information concerning the glaciers of -Greenland north of Melville Bay was obtained by Drs. Kane and Hayes, -in 1853 and 1854, while conducting an expedition in search of Sir -John Franklin and his unfortunate crew. Dr. Hayes conducted another -expedition to the same desolate region in 1860, while other explorers -have to some extent supplemented their observations. The largest glacier -which they saw enters the sea between latitude 79° and 80°, where it -presents a precipitous discharging front more than sixty miles in width -and hundreds of feet in perpendicular height. - -Dr. Kane gives his first impressions of this grand glacier in the -following vivid description: - -"I will not attempt to do better by florid description. Men only -rhapsodize about Niagara and the ocean. My notes speak simply of the -'long, ever-shining line of cliff diminished to a well-pointed wedge in -the perspective'; and, again, of 'the face of glistening ice, sweeping -in a long curve from the low interior, the facets in front intensely -illuminated by the sun.' But this line of cliff rose in a solid, -glassy wall three hundred feet above the water-level, with an unknown, -unfathomable depth below it; and its curved face, sixty miles in length -from Cape Agassiz to Cape Forbes, vanished into unknown space at not more -than a single day's railroad-travel from the pole. The interior, with -which it communicated and from which it issued, was an unsurveyed _mer de -glace_--an ice-ocean to the eye, of boundless dimensions. - -"It was in full sight--the mighty crystal bridge which connects the two -continents of America and Greenland. I say continents, for Greenland, -however insulated it may ultimately prove to be, is in mass strictly -continental. Its least possible axis, measured from Cape Farewell to the -line of this glacier, in the neighbourhood of the eightieth parallel, -gives a length of more than 1,200 miles, not materially less than that of -Australia from its northern to its southern cape. - -"Imagine, now, the centre of such a continent, occupied through nearly -its whole extent by a deep, unbroken sea of ice that gathers perennial -increase from the water-shed of vast snow-covered mountains and all the -precipitations of its atmosphere upon its own surface. Imagine this, -moving onwards like a great glacial river, seeking outlets at every fiord -and valley, rolling icy cataracts into the Atlantic and Greenland seas; -and, having at last reached the northern limit of the land that has borne -it up, pouring out a mighty frozen torrent into unknown arctic space! - -"It is thus, and only thus, that we must form a just conception of a -phenomenon like this great glacier. I had looked in my own mind for such -an appearance, should I ever be fortunate enough to reach the northern -coast of Greenland; but, now that it was before me, I could hardly -realize it. I had recognized, in my quiet library at home, the beautiful -analogies which Forbes and Studer have developed between the glacier and -the river. But I could not comprehend at first this complete substitution -of ice for water. - -"It was slowly that the conviction dawned on me that I was looking upon -the counterpart of the great river-system of Arctic Asia and America. Yet -here were no water-feeders from the south. Every particle of moisture had -its origin within the polar circle and had been converted into ice. There -were no vast alluvions, no forest or animal traces borne down by liquid -torrents. Here was a plastic, moving, semi-solid mass, obliterating life, -swallowing rocks and islands, and ploughing its way with irresistible -march through the crust of an investing sea."[AL] - -[Footnote AL: Arctic Explorations in the Years 1853, 1854, and 1855, vol. -i, pp. 225-228.] - -Much less is known concerning the eastern coast of Greenland than -about the western coast. For a long time it was supposed that there -might be a considerable population in the lower latitudes along the -eastern side. But that is now proved to be a mistake. The whole coast -is very inhospitable and difficult of approach. From latitude 65° to -latitude 69° little or nothing is known of it. In 1822-'23 Scoresby, -Cleavering, and Sabine hastily explored the coast from latitude 69° to -76°, and reported numerous glaciers descending to the sea-level through -extensive fiords, from which immense icebergs float out and render -navigation dangerous. In 1869 and 1870 the second North-German Expedition -partly explored the coast between latitude 73° and 77°. Mr. Payer, an -experienced Alpine explorer, who accompanied the expedition, reports the -country as much broken, and the glaciers as "subordinated in position to -the higher peaks, and having their moraines, both lateral and terminal, -like those of the Alpine ranges, and on a still grander scale." Petermann -Peak, in latitude 73°, is reported as 13,000 feet high. Captain Koldewey, -chief of the expedition, found extensive plateaus on the mainland, in -latitude 75°, to be "entirely clear of snow, although only sparsely -covered with vegetation." The mountains in this vicinity, also, rising to -a height of more than 2,000 feet, were free from snow in the summer. Some -of the fiords in this vicinity penetrate the continent through several -degrees of longitude. - -An interesting episode of this expedition was the experience of the crew -of the ship Hansa, which was caught in the ice and destroyed. The crew, -however, escaped by encamping on the ice-floe which had crushed the ship. -From this, as it slowly floated towards the south through several degrees -of latitude, they had opportunity to make many important observations -upon the continent itself. As viewed from this unique position the coast -had the appearance everywhere of being precipitous, with mountains of -considerable height rising in the background, from which numerous small -glaciers descended to the sea-level. - -In 1888 Dr. F. Nansen, with Lieutenant Sverdrup and four others, was -left by a whaler on the ice-pack bordering the east of Greenland about -latitude 65°, and in sight of the coast. For twelve days the party was -on the ice-pack floating south, and so actually reached the coast only -about latitude 64°. From this point they attempted to cross the inland -ice in a northwesterly direction towards Christianshaab. They soon -reached a height of 7,000 feet, and were compelled by severe northerly -storms to diverge from their course, taking a direction more to the west. -The greatest height attained was 9,500 feet, and the party arrived on the -western coast at Ameralik Fiord, a little south of Godhaab, about the -same latitude at which they entered. - -It thus appears that subsequent investigations have confirmed in a -remarkable manner the sagacious conclusions made by the eminent Scotch -geologist and glacialist Robert Brown in 1875, soon after his own -expedition to the country. "I look upon Greenland and its interior -ice-field," he writes, "in the light of a broad-lipped, shallow vessel, -but with chinks in the lips here and there, and the glacier like viscous -matter in it. As more is poured in, the viscous matter will run over the -edges, naturally taking the line of the chinks as its line of outflow. -The broad lips of the vessel are the outlying islands or 'outskirts'; -the viscous matter in the vessel the inland ice, the additional matter -continually being poured in in the form of the enormous snow covering, -which, winter after winter, for seven or eight months in the year, falls -almost continuously on it; the chinks are the fiords or valleys down -which the glaciers, representing the outflowing viscous matter, empty the -surplus of the vessel--in other words, the ice floats out in glaciers, -overflows the land in fact, down the valleys and fiords of Greenland -by force of the superincumbent weight of snow, just as does the grain -on the floor of a barn (as admirably described by Mr. Jamieson) when -another sackful is emptied on the top of the mound already on the floor. -'The floor is flat, and therefore does not conduct the grain in any -direction; the outward motion is due to the pressure of the particles -of grain on one another; and, given a floor of infinite extension and a -pile of sufficient amount, the mass would move outward to any distance, -and with a very slight pitch or slope it would slide forward along the -incline.' To this let me add that if the floor on the margin of the heap -of grain was undulating the stream of grain would take the course of -such undulations. The want, therefore, of much slope in a country and -the absence of any great mountain-range are of very little moment to the -movement of land-ice, _provided we have snow enough_" On another page Dr. -Brown had well said that "the country seems only a circlet of islands -separated from one another by deep fiords or straits, and bound together -on the landward side by the great ice covering which overlies the whole -interior.... No doubt under this ice there lies land, just as it lies -under the sea; but nowadays none can be seen, and as an insulating medium -it might as well be water." - -In his recently published volumes descriptive of the journey across -the Greenland ice-sheet, alluded to on page 39, Dr. Nansen sums up his -inferences in very much the same way: "The ice-sheet rises comparatively -abruptly from the sea on both sides, but more especially on the east -coast, while its central portion is tolerably flat. On the whole, the -gradient decreases the farther one gets into the interior, and the mass -thus presents the form of a shield with a surface corrugated by gentle, -almost imperceptible, undulations lying more or less north and south, -and with its highest point not placed symmetrically, but very decidedly -nearer the east coast than the west." - -From this rapid glance at the existing glaciers of the world we see that -a great ice age is not altogether a strange thing in the world. The lands -about the south pole and Greenland are each continental in dimensions, -and present at the present time accumulations of land-ice so extensive, -so deep, and so alive with motion as to prepare our minds for almost -anything that may be suggested concerning the glaciated condition of -other portions of the earth's surface. The _vera causa_ is sufficient -to accomplish anything of which glacialists have ever dreamed. It only -remains to enquire what the facts really are and over how great an extent -of territory the actual results of glacial action may be found. But we -will first direct more particular attention to some of the facts and -theories concerning glacial motion. - - - - -CHAPTER III. - -GLACIAL MOTION. - - -That glacial ice actually moves after the analogy of a semi-fluid has -been abundantly demonstrated by observation. In the year 1827 Professor -Hugi, of Soleure, built a hut far up upon the Aar Glacier in Switzerland, -in order to determine the rate of its motion. After three years he found -that it had moved 330 feet; after nine years, 2,354 feet; and after -fourteen years Louis Agassiz found that its motion had been 4,712 feet. -In 1841 Agassiz began a more accurate series of observation upon the same -glacier. Boring holes in the ice, he set across it a row of stakes which, -on visiting in 1842, he found to be no longer in a straight line. All had -moved downwards with varying velocity, those near the centre having moved -farther than the others. The displacements of the stakes were in order, -from side to side, as follows: 160 feet, 225 feet, 269 feet, 245 feet, -210 feet, and 125 feet. Agassiz followed up his observations for six -years, and in 1847 published the results in his celebrated work System -Glacière. - -[Illustration: Fig. 16.] - -But in August, 1841, the distinguished Swiss investigator had invited -Professor J. D. Forbes, of Edinburgh, to interest himself in solving the -problem of glacial motion. In response to this request, Professor Forbes -spent three weeks with Agassiz upon the Aar Glacier. Stimulated by the -interest of this visit, Forbes returned to Switzerland in 1842 and began -a series of independent investigations upon the Mer de Glace. After a -week's observations with accurate instruments, Forbes wrote to Professor -Jameson, editor of the Edinburgh New Philosophical Journal, that he had -already made it certain that "the central part of the glacier moves -faster than the edges in a very considerable proportion, quite contrary -to the opinion generally maintained." This letter was dated July 4, 1842, -but was not published until the October following, Agassiz's results, so -far as then determined, were, however, published in Comptes Rendus of -the 29th of August, 1842, two months before the publication of Forbes's -letter. But Agassiz's letter was dated twenty-seven days later than that -of Forbes. It becomes certain, therefore, that both Agassiz and Forbes, -independently and about the same time, discovered the fact that the -central portion of a glacier moves more rapidly than the sides. - -In 1857 Professor Tyndall began his systematic and fruitful observations -upon the Mer de Glace and other Alpine glaciers. Professor Forbes had -already demonstrated that, with an accurate instrument of observation, -the motion of a line of stakes might be observed after the lapse -of a single clay, or even of a few hours. As a result of Tyndall's -observations, it was found that the most rapid daily motion in the Mer de -Glace in 1857 was about thirty-seven inches. This amount of motion was -near the lower end of the glacier On ascending the glacier, the rate was -found in general to be diminished; but the diminution was not uniform -throughout the whole distance, being affected both by the size and by the -contour of the valley. The motion in the tributary glaciers was also much -less than that of the main glacier. - -This diminution of movement in the tributary glaciers was somewhat -proportionate to their increase in width. For example, the combined -width of the three tributaries uniting to form the Mer de Glace is 2,597 -yards; but a short distance below the junction of these tributaries the -total width of the Mer de Glace itself is only 893 yards, or one-third -that of the tributaries combined. Yet, though the depth of the ice is -probably here much greater than in the tributaries, the rapidity of -movement is between two and three times as great as that of any one of -the branches.[AM] - -[Footnote AM: See Tyndall's Forms of Water, pp. 78-82.] - -From Tyndall's observations it appears also that the line of most rapid -motion is not exactly in the middle of the channel, but is pushed by its -own momentum from one side to the other of the middle, so as always to be -nearer the concave side; in this respect conforming, as far as its nature -will permit, to the motion of water in a tortuous channel. - -[Illustration: Fig. 17.] - -It is easy to account for this differential motion upon the surface -of a glacier, since it is clear that the friction of the sides of the -channel must retard the motion of ice as it does that of water. It is -clear also that the friction of the bottom must retard the motion of ice -even more than it is known to do in the case of water. In the formation -of breakers, when the waves roll in upon a shallowing beach, every one -is familiar with the effect of the bottom upon the moving mass. Here -friction retards the lower strata of water, and the upper strata slide -over the lower, and, where the water is of sufficient depth and the -motion is sufficiently great, the crest breaks down in foam before the -ever-advancing tide. A similar phenomenon occurs when dams give way and -reservoirs suddenly pour their contents into the restricted channels -below. At such times the advancing water rolls onwards like the surf with -a perpendicular front, varying in height according to the extent of the -flood. - -Seasoning from these phenomena connected with moving water, it was -naturally suggested to Professor Tyndall that an analogous movement must -take place in a glacier. Choosing, therefore, a favourable place for -observation on the Mer de Glace where the ice emerged from a gorge, he -found a perpendicular side about one hundred and fifty feet in height -from bottom to top. In this face he drove stakes in a perpendicular line -from top to bottom. Upon subsequently observing them, Tyndall found, as -he expected, that there was a differential motion among them as in the -stakes upon the surface. The retarding effect of friction upon the bottom -was evident. The stake near the top moved forwards about three times as -fast as the one which was only four feet from the bottom. - -[Illustration: Fig. 18.] - -The most rapid motion (thirty-seven inches per day) observed by Professor -Tyndall upon the Alpine glaciers occurred in midsummer. In winter -the rate was only about one-half as great; but in the year 1875 the -Norwegian geologist, Helland, reported a movement of twenty metres (about -sixty-five feet) per day in the Jakobshavn Glacier which enters Disco -Bay, Greenland, about latitude 70°. For some time there was a disposition -on the part of many scientific men to doubt the correctness of Holland's -calculations. Subsequent observations have shown, however, that from the -comparatively insignificant glaciers of the Alps they were not justified -in drawing inferences with respect to the motion of the vastly larger -masses which come down to the sea through the fiords of Greenland. -The Jakobshavn Glacier was about two and a half miles in width and its -depth very likely more than a thousand feet, making a cross-section of -more than 1,400,000 square yards, whereas the cross-section of the Mer -de Glace at Montanvert is estimated to be but 190,000 square yards or -only about one-seventh the above estimate for the Greenland glacier. As -the friction of the sides would be no greater upon a large stream than -upon a small one, while upon the bottom it would be only in proportion -to the area, it is evident that we cannot tell beforehand how rapidly -an increase in the volume of the ice might augment the velocity of the -glacier. - -At any rate, all reasonable grounds for distrusting the accuracy of -Helland's estimates seem to have been removed by later investigations. -According to my own observations in the summer of 1886 upon the Muir -Glacier, Alaska, the central portions, a mile back from the front of -that vast ice-current, were moving from sixty-five to seventy feet per -day. These observations were taken with a sextant upon pinnacles of ice -recognizable from a baseline established upon the shore. It is fair -to add, however, that during the summer of 1890 Professor H. F. Reid -attempted to measure the motion of the same glacier by methods promising -greater accuracy than could be obtained by mine. He endeavoured to plant, -after the method of Tyndall, a line of stakes across the ice-current. But -with his utmost efforts, working inwards from both sides, he was unable -to accomplish his purpose, and so left unmeasured a quarter of a mile -or more of the most rapidly-moving portion of the glacier. His results, -therefore, of ten feet per day in the most rapidly-moving portion -observed cannot discredit my own observations on a portion of the stream -inaccessible by his method. A quarter of a mile in width near the centre -of so vast a glacier gives ample opportunity for a much greater rate of -motion than that observed by Professor Reid. Especially may this be true -in view of Tyndall's suggestion that the contour of the bottom over which -the ice flows may greatly affect the rate in certain places. A sudden -deepening of the channel may affect the motion of ice in a glacier as -much as it does that of water in a river. - -Other observations also amply sustain the conclusions of Helland. As -already stated, the Danish surveying party under Steenstrup, after -several years' work upon the southwestern coast of Greenland, have -ascertained that the numerous glaciers coming down to the sea in that -region and furnishing the icebergs incessantly floating down Baffin's -Bay, move at a rate of from thirty to fifty feet per day, while -Lieutenants Ryder and Bloch, of the Danish Navy, who spent the year 1887 -in exploring the coast in the vicinity of Upernavik, about latitude 73°, -found that the great glacier entering the fiord east of the village had a -velocity of ninety-nine feet per day during the month of August.[AN] - -[Footnote AN: Nature, December 29, 1887.] - -It is easier to establish the fact of glacial motion than to explain how -the motion takes place, for ice seems to be as brittle as glass. This, -however, is true of it only when compelled suddenly to change its form. -When subjected to slow and long-continued pressure it gradually yet -readily yields, and takes on new forms. From this capacity of ice, it has -come to be regarded by some as a really viscous substance, like tar or -cooling lava, and upon that theory Professor Forbes endeavours to explain -all glacial movement. - -The theory, however, seems to be contradicted by familiar facts; for -the iceman, after sawing a shallow groove across a piece of ice, can -then split it as easily as he would a piece of sandstone or wood. On the -glaciers themselves, likewise, the existence of innumerable crevasses -would seem to contradict the plastic theory of glacier motion; for, -wherever the slope of the glacier's bed increases, crevasses are formed -by the increased strain to which the ice is subjected. Crevasses are also -formed in rapidly-moving glaciers by the slight strain occasioned by the -more rapid motion of the middle portion. Still, in the words of Tyndall, -"it is undoubted that the glacier moves like a viscous body. The centre -flows past the sides, the top flows over the bottom, and the motion -through a curved valley corresponds to fluid motion."[AO] - -[Footnote AO: Forms of Water, p. 163.] - -To explain this combination of the seemingly contradictory qualities of -brittleness and viscosity in ice, physicists have directed attention -to the remarkable transformations which take place in water at the -freezing-point. Faraday discovered in 1850 that "when two pieces of -thawing ice are placed together they freeze together at the point of -contact.[AP] - -[Footnote AP: Ibid., p. 164.] - -"Place a number of fragments of ice in a basin of water and cause them -to touch each other; they freeze together where they touch. You can form -a chain of such fragments; and then, by taking hold of one end of the -chain, you can draw the whole series after it. Chains of icebergs are -sometimes formed in this way in the arctic seas."[AQ] - -[Footnote AQ: Ibid., pp. 164, 165.] - -This is really what takes place when a hard snow-ball is made by pressure -in the hand. So, by subjecting fragments of ice to pressure it is first -crumbled to powder, and then, as the particles are pressed together in -close contact, it resumes the nature of ice again, though in a different -form, taking now the shape of the mould in which it has been pressed. - -Thus it is supposed that, when the temperature of ice is near the -melting-point, the pressure of the superincumbent mass may produce at -certain points insensible disintegration, while, upon the removal of -the pressure by change of position, regulation instantly takes place, -and thus the phenomena which simulate plasticity are produced. As the -freezing-point of water is, within a narrow range, determined by the -amount of pressure to which it is subjected, it is not difficult to see -how these changes may occur. Pressure slightly lowers the freezing-point, -and so would liquefy the portions of ice subjected to greatest pressure, -wherever that might be in the mass of the glacier, and thus permit -a momentary movement of the particles, until they should recongeal -in adjusting themselves to spaces of less pressure.[AR] This is the -theory by which Professor James Thompson would account for the apparent -plasticity of glacial ice. - -[Footnote AR: Forms of Water, p. 168.] - - - - -CHAPTER IV. - -SIGNS OF PAST GLACIATION. - - -The facts from which we draw the inference that vast areas of the earth's -surface which are now free from glaciers were, at a comparatively -recent time, covered with them, are fourfold, and are everywhere -open to inspection. These facts are: 1. Scratches upon the rocks. 2. -Extensive unstratified deposits of clay and sand intermingled with -scratched stones and loose fragments of rock. 3. Transported boulders -left in such positions and of such size as to preclude the sufficiency -of water-carriage to account for them. 4. Extensive gravel terraces -bordering the valleys which emerge from the glaciated areas. We will -consider these in their order: - -1. The scratches upon the rocks. - -Almost anywhere in the region designated as having been covered with -ice during the Glacial period, the surface of the rocks when freshly -uncovered will be found to be peculiarly marked by grooves and scratches -more or less fine, and such as could not be produced by the action of -water. But, when we consider the nature of a glacier, these marks seem -to be just what would be produced by the pushing or dragging along of -boulders, pebbles, gravel, and particles of sand underneath a moving mass -of ice. - -Running water does indeed move gravel, pebbles, and boulders along with -the current, but these objects are not held by it in a firm grasp, such -as is required to make a groove or scratch in the rock. If, also, there -are inequalities in the compactness or hardness of the rock, the natural -action of running water is to hollow out the soft parts, and leave the -harder parts projecting. But, in the phenomena which we are attributing -to glacial action, there has been a movement which has steadily planed -down the surface of the underlying rock; polishing it, indeed, but also -grooving it and scratching it in a manner which could be accomplished -only by firmly held graving-tools. - -[Illustration: Fig. 19.--Bed-rock scored with glacial marks, near -Amherst, Ohio. (From a photograph by Chamberlin.)] - -This polishing and scratching can indeed be produced by various -agencies; as, for example, by the forces which fracture the earth's -crust, and shove one portion past another, producing what is called a -_slicken-side_. Or, again, avalanches or land-slides might be competent -to produce the results over limited and peculiarly situated areas. -Icebergs, also, and shore ice which is moved backwards and forwards -by the waves, would produce a certain amount of such grooving and -scratching. But the phenomena to which we refer are so extensive, and -occur in such a variety of situations, that the movement of glacial ice -is alone sufficient to afford a satisfactory explanation. Moreover, in -Alaska, Greenland, Norway, and Switzerland, and wherever else there are -living glaciers, it is possible to follow up these grooved and striated -surfaces till they disappear underneath the existing glaciers which are -now producing the phenomena. Thus by its tracks we can, as it were, -follow this monster to its lair with as great certainty as we could any -animal with whose footprints we had become familiar. - -2. The till, or boulder-clay. - -A second sign of the former existence of glaciers over any area consists -of an unstratified deposit of earthy material, of greater or less depth, -in which scratched pebbles and fragments of rock occur without any -definite arrangement. - -Moving water is a most perfect sieve. During floods, a river shoves -along over its bed gravel and pebbles of considerable size, whereas in -time of low-water the current may be so gentle as to transport nothing -but fine sand, and the clay will be carried still farther onwards, to -settle in the still water and form a delta about the river's mouth. The -transporting capacity of running water is in direct ratio to the sixth -power of its velocity. Other things being equal, if the velocity be -doubled, the size of the grains of sand or gravel which it transports -is increased sixty-four fold.[AS] So frequent are the changes in the -velocity of running water, that the stratification of its deposits is -almost necessary and universal. If large fragments of rocks or boulders -are found embedded in stratified clay, it is pretty surely a sign that -they have been carried to their position by floating ice. A small -mountain stream with great velocity may move a good-sized boulder, while -the Amazon, with its mighty but slow-moving current, would pass by it -forever without stirring it from its position. But the vast area which -is marked in our map as having been covered with ice during the Glacial -period is characterised by deep and extensive deposits of loose material -devoid of stratification, and composed of soil and rock gathered in -considerable part from other localities, and mixed in an indiscriminate -mass with material which has originated in the disintegration of the -underlying local strata. - -[Footnote AS: Le Conte's Geology, p. 19.] - -[Illustration: Fig. 20.--Scratched stone from the till of Boston. -Natural size about one foot and a half long by ten inches wide. (From -photograph.)] - -[Illustration: Fig. 21.--Typical section of till in Seattle. Washington -State, about two hundred feet above Puget Sound. This is on the height -between the sound and Lake Washington.] - -[Illustration: Fig. 22.--Ideal section, showing how the till overlies the -stratified rocks.] - -[Illustration: Fig. 23.--Vessel Rock, a glacial boulder in Gilsum. N. H. -(C. H. Hitchcock.)] - -3. Transported boulders. - -Where there is a current of water deep enough to float large masses of -ice, there is scarcely any limit to the size of boulders which may be -transported upon them, or to the distance to which the boulders may be -carried and dropped upon the bottom. The icebergs which break off from -the glaciers of Greenland may bear their burdens of rock far down into -the Atlantic, depositing them finally amidst the calcareous ooze and -the fine sediment from the Gulf Stream which is slowly covering the -area between Northern America and Europe. Northern streams like the St. -Lawrence, which are deeply frozen over with ice in the winter, and are -heavily flooded as the ice breaks up in the spring, afford opportunity -for much transportation of boulders in the direction of their current. -In attributing the transportation of a boulder to glacial ice, it is -necessary, therefore, to examine the contour of the country, so as to -eliminate from the problem the possibility of the effects having been -produced by floating ice. - -Another source of error against which one has to be on his guard arises -from the close resemblance of boulders resulting from disintegration -to those which have been transported by ice from distant places. Owing -to the fact that large masses of rocks, especially those which are -crystalline, are seldom homogeneous in their structure, it results that, -under the slow action of disintegrating and erosive agencies, the softer -parts often are completely removed before the harder nodules are sensibly -affected, and these may remain as a collection of boulders dotting the -surface. Such boulders are frequent in the granitic regions of North -Carolina and vicinity, where there has been no glacial transportation. -Several localities in Pennsylvania, also, south of the line of glacial -action as delineated by Professor Lewis and myself, had previously -been supposed to contain transported boulders of large size, but on -examination they proved in all cases to be resting upon undisturbed -strata of the parent rock, and were evidently the harder portions of -the rock left in loco by the processes of erosion spoken of. In New -England, also, it is possible that some boulders heretofore attributed to -ice-action may be simply the results of these processes of disintegration -and erosion. Whether they are or not can usually be determined by their -likeness or unlikeness to the rocks on which they rest; but oftentimes, -where a particular variety of rock is exposed over a broad area, it -is difficult to tell whether a boulder has suffered any extensive -transportation or not. - -One of the most interesting and satisfactory demonstrations of the -distribution of boulders by glacial ice was furnished by Guyot in -Switzerland in 1845. His observations and argument will be most readily -understood by reference to the accompanying map, taken from Lyell's clear -description.[AT] The Jura Mountains are separated from the Alps by a -valley, about eighty miles in width, which constitutes the main habitable -portion of Switzerland, and they rise upwards of two thousand feet above -it. But large Alpine boulders are found as high as two thousand feet -above the Lake Neufchâtel upon the flanks of the Jura Mountains beyond -Chasseron (at the point marked G on the map), and the whole valley is -dotted with Alpine boulders. Upon comparing these with the native rocks -in the Alps, Guyot in many cases was able to determine the exact centres -from which they were distributed, and the distribution is such as to -demonstrate that glacial ice was the medium of distribution. - -[Footnote AT: Antiquity of Man, p. 299.] - -[Illustration: Fig. 24.--Map showing the outline and course of flow of -the great Rhône Glacier (after Lyell).] - -For example, the dotted lines upon the map indicate the motion of the -transporting medium. On ascending the valley of the Rhône to A, the -diminutive representative of the ancient glacier is still found in -existence, and is at work transporting boulders and moraines according -to the law of ice-movement. Following down the valley from A, boulders -from the head of the Rhône Valley are found distributed as far as B at -Martigny, where the valley turns at right angles towards the north. It -is evident that floating ice in a stream of water would by its momentum -be carried to the left bank, so that if icebergs were the medium of -transportation we should expect to find the boulders from the right-hand -side of the Rhône Valley distributed towards the left end of the great -valley of Switzerland--that is, in the direction of Geneva. But, instead, -the boulders derived from C, D, and E, on the Bernese Oberland side, -instead of crossing the valley at B, continue to keep on the right-hand -side and are distributed over the main valley in the direction of the -river Aar. - -As is to be expected also, the direct northward motion of the ice from -B is stronger than the lateral movement to the right and left after it -emerges from the mouth of the Rhône Valley, at F, and consequently it has -pushed forwards in a straight line, so as to raise the Alpine boulders -to a greater height upon the Jura Mountains at G than anywhere else, the -upper limit of boulders at G being 1,500 feet higher than the limits at I -or K on the left and right, points distant about one hundred miles from -each other. All the boulders to the right of the line from B to G have -been derived from the right side of the Rhône, while all the boulders to -the left of that line have been derived from its left side. - -A boulder of talcose granite containing 61,000 French cubic feet, -measuring about forty feet in one direction, came, according to -Charpentier, from the point _n_, near the head of the Rhône Valley, and -must have travelled one hundred and fifty miles to reach its present -position. - -It scarcely needs to be added that the grooves and scratches upon the -rocks over the floor of this great valley of Switzerland indicate a -direction of the ice-movement corresponding to that implied in the -distribution of boulders. Thus, at K upon the map referred to, Lyell -reports that the abundant grooves and striæ upon the polished marble all -trend down the valley of the Aar.[AU] - -[Footnote AU: Antiquity of Man, p. 305.] - -Similar facts concerning the transportation of boulders have been -observed at Trogen, in Appenzel, where boulders derived from Trons, -one hundred miles distant, are found to keep upon the left bank of the -Rhine, however much the valley may wind about; and in some places, as at -Mayenfeld, it turns almost at right angles, as did the Rhône at Martigny. -Upon reaching the lower country at Lake Constance, these granite blocks -from the left side of the valley deploy out upon the same side and do not -cross over, as they would inevitably have done had they been borne along -by currents of water. - -In America Ave do not have quite so easy a field as is presented -in Switzerland for the discovery of crucial instances showing that -boulders have been transported by glacial ice rather than by floating -ice, for in Switzerland the glaciated area is comparatively small and -the diminutive remnants of former glaciers are still in existence, -furnishing a comprehensive object-lesson of great interest and convincing -power. Still, it is not difficult to find decisive instances of glacial -transportation even in the broad fields of America which now retain no -living remnants of the great continental ice-sheet. - -As every one who resides in or who visits New England knows, boulders are -scattered freely over all parts of that region, but for a long time the -theory suggested to account for their distribution was that of floating -ice during a period of submergence. One of the most convincing evidences -that the boulders were distributed by glacial ice rather than by icebergs -is found in Professor C. H. Hitchcock's discovery of boulders on the -summit of Mount Washington (over 6,000 feet above the sea), which he -was able to identify as derived from the ledges of light grey Bethlehem -gneiss, whose nearest outcrop is in Jefferson, several miles to the -northwest, and 3,000 or 4,000 feet lower than Mount Washington. However -difficult it may be to explain the movement of these boulders by glacial -ice, it is not impossible to do so, but the attempt to account for their -transportation by floating ice is utterly preposterous. No iceberg could -pick up boulders so far beneath the surface of the water, and even if it -could advance thus far in its work it could not by any possibility land -them afterwards upon the summit of Mount Washington. - -Among the most impressive instances of boulders evidently transported -by glacial ice, rather than by icebergs, were some which came to my -notice when, in company with the late Professor H. Carvill Lewis, I was -tracing the glacial boundary across the State of Pennsylvania. We had -reached the elevated plateau (two thousand feet above the sea) which -extends westwards and southwards from the peak of Pocono Mountain, in -Monroe County. This plateau consists of level strata of sandstone, the -southern part of which is characterised by a thin sandy soil, such as is -naturally formed by the disintegration of the underlying rock, and there -is no foreign material to be found in it. But, on going northwards to -the boundary of Tobyhanna township, we at once struck a large line of -accumulations, stretching from east to west, and rising to a height of -seventy or eighty feet. This was chiefly an accumulation of transported -boulders, resembling in its structure the terminal moraines which are -found at the front of glaciers in the Alps and in Alaska, and indeed -wherever active glaciers still remain. But here we were upon the summit -of the mountain, where there are no higher levels to the north of -us, down which the ice could flow. Besides, among these boulders we -readily recognised many of granite, which must have come either from -the Adirondack Mountains, two hundred miles to the north, or from the -Canadian highlands, still farther away. - -Limiting our observations simply to the boulders, we should indeed have -been at liberty to suppose that they had been transported across the -valley of the Mohawk or of the Great Lakes by floating ice during a -period of submergence. But we were forbidden to resort to this hypothesis -by the abrupt marginal line, running east and west, upon Pocono plateau, -along which these northern boulders ceased. South of this evident -terminal moraine there was no barrier, and there were no northern -boulders. On the theory of submergence, there was no reason for the -boundary-line so clearly manifested. Ice which had floated so far would -have floated farther. - -Still further, on going a few miles east of the Pocono plateau, one -descends into a parallel valley, lying between Pocono Mountain and Blue -Mountain, and one thousand feet below their level. But our marginal -southern boundary of transported granite rocks did not extend much -farther south in the valley than it did on the plateau, except where we -could trace the action of a running stream, evidently corresponding to -the subglacial rivers which pour forth from the front of every extensive -glacier. In these facts, therefore, we had a crucial test of the glacial -hypothesis, and, in view of them, could maintain, against all objectors, -the theory of the distant glacial transportation of boulders, even over -vast areas of the North American continent. - -Since that experience, I have traced this limit of southern boulders for -thousands of miles across the continent, according to the delineation -which may be seen in the map in a later chapter. If necessary, I could -indicate hundreds of places where the proof of glacial transportation -is almost as clear as that on the Pocono plateau in Pennsylvania. One -of the most interesting of these is on the hills in Kentucky, about -twelve miles south of the Ohio River, at Cincinnati, where I discovered -boulders of a conglomerate containing many pebbles of red jasper, which -can be identified as from a limited formation cropping out in Canada, -to the north of Lake Huron, six hundred or seven hundred miles distant. -That this was transported by glacial ice, and not by floating ice, is -evident from the fact that here, too, there was no barrier to the south, -requiring deposits to cease at that point, and from the further fact -that boulders of this material are found in increasing frequency all -the way from Kentucky to the parent ledges in Canada. With reference to -these boulders, as with reference to those found on the summit of Mount -Washington, we can reason, also, that any northerly subsidence permitting -a body of water to occupy the space between Kentucky and Lake Superior, -and deep enough to facilitate the movement across it of floating ice, -would render it impossible for the ice to have loaded itself with them. - -[Illustration: Fig. 25.--Conglomerate boulder found in Boone County, -Kentucky. (See text.)] - -The same line of reasoning is conclusive respecting the innumerable -boulders which cover the northern portion of Ohio, where I have my -residence. The whole State of Ohio, and indeed almost the entire -Mississippi basin between the Appalachian and the Rocky Mountains, is -completely covered, and to a great depth, with stratified rocks which -have been but slightly disturbed in the elevation of the continent; yet, -down to an irregular border-line running east and west, granitic boulders -everywhere occur in great numbers. In the locality spoken of in northern -Ohio the elevation of the country is from two hundred to five hundred -feet above the level of Lake Erie. The nearest outcrops of granitic rock -occur about four hundred miles to the north, in Canada. After the meeting -of the American Association for the Advancement of Science in Toronto -in the summer of 1889, I had the privilege of joining a company of -geologists in an excursion, conducted by members of the Canadian Survey, -to visit the region beyond Lake Nipissing, north of Lake Huron, where -the ancient Laurentian and Huronian rocks are most typically developed. -I took advantage of the trip to collect specimens of a great variety of -the granites and gneisses and metamorphic schists and trap-rock of the -region. On bringing them home I turned them over to the professor of -geology, who at once set his class at work to see if they could match my -fragments from Canada with corresponding fragments from the boulders of -the vicinity. To the great gratification, both of the pupils and myself, -they were able to do so in almost every case; and so they might have -done in any county or township to the south until reaching the limit of -glacier action which I had previously mapped. Here, at Oberlin, on the -north side of the water-shed, it is possible to imagine that we are on -the southern border of an ancient lake upon whose bosom floating ice -had brought these objects from their distant home in Canada. But this -theory would not apply to the portion of the State which is south of the -water-shed and which slopes rapidly towards the Gulf of Mexico. Yet the -distribution of boulders is practically uniform over the glaciated area -on both sides of the water-shed, constituting thus an indisputable proof -of the glacial theory. - -4th. As the significance of the gravel terraces which mark the lines of -outward drainage from the glaciated area cannot well be indicated in a -single paragraph, the reader is referred for further information upon -this point to the general statements respecting them throughout the next -chapter. - - - - -CHAPTER V. - -ANCIENT GLACIERS IN THE WESTERN HEMISPHERE. - - -_New England._ - -In North America all the indubitable signs of glacial action are found -over the entire area of New England, the southern coast being bordered -by a double line of terminal moraines. The outermost of these appears in -Nantucket, Martha's Vineyard, No Man's Land, Block Island, and through -the entire length of Long Island--from Montauk Point, through the centre -of the island, to Brooklyn, N. Y., and thence across Staten Island to -Perth Amboy in New Jersey. The interior line is nearly parallel with the -outer, and, beginning at the east end of Cape Cod, runs in a westerly -direction to Falmouth, and thence southwesterly through Wood's Holl, and -the Elizabeth Islands--these being, indeed, but the unsubmerged portions -of the moraine. On the mainland this interior line reappears near Point -Judith, on the south shore of Rhode Island, and, running slightly south -of west, serves to give character to the scenery at Watch Hill, and -thence crops out in the Sound as Fisher and Plum Islands, and farther -west forms the northern shore of Long Island to Port Jefferson. - -[Illustration: MAP SHOWING - -THE - -GLACIAL GEOLOGY - -OF THE - -UNITED STATES.] - -In these accumulations bordering the southern shore of New England, the -characteristic marks of glacial action can readily be detected even by -the casual observer, and prolonged examination will amply confirm the -first impression. The material of which they are composed is, for the -most part, foreign to the localities, and can be traced to outcrops -of rock at the north. The boulders scattered over the surface of Long -Island, for example, consist largely of granite, gneiss, hornblende, mica -slate, and red sandstone, which are easily recognised as fragments from -well-known quarries in Connecticut, Rhode Island, and Massachusetts; yet -they have been transported bodily across Long Island Sound, and deposited -in a heterogeneous mass through the entire length of the island. Not -only do they lie upon the surface, but, in digging into the lines of -hills which constitute the backbone of Long Island, these transported -boulders are found often to make up a large part of the accumulation. -Almost any of the railroad excavations in the city of Brooklyn present -an interesting object-lesson respecting the composition of a terminal -moraine. - -All these things are true also of the lines of moraine farther east, -as just described. Professor Shaler has traced to its source a belt -of boulders occurring extensively over southern Rhode Island, and -found that they have spread out pretty evenly over a triangular area -to the southward, in accordance with the natural course to be pursued -by an ice-movement. Nearly all of Plymouth County, in southeastern -Massachusetts, is composed of foreign material, much of which can be -traced to the hills and mountains to the north. Even Plymouth Rock is a -boulder from the direction of Boston, and the "rock-bound" shores upon -which the Pilgrims are poetically conceived to have landed are known, in -scientific prose, as piles of glacial rubbish dumped into the edge of the -sea by the great continental ice-sheet. - -The whole area of southeastern Massachusetts is dotted with conical -knolls of sand, gravel, and boulders, separated by circular masses of -peat or ponds of water, whose origin and arrangement can be accounted -for only by the peculiar agency of a decaying ice-front. Indeed, this -whole line of moraines, from the end of Cape Cod to Brooklyn, N. Y., -consists of a reticulated network of ridges and knolls, so deposited by -the ice as to form innumerable kettle-holes which are filled with water -where other conditions are favourable. Those which are dry are so because -of their elevation above the general level, and of the looseness of the -surrounding soil; while many have been filled with a growth of peat, so -that their original character as lakelets is disguised. - -As already described, these depressions, so characteristic of the -glaciated region, are, in the majority of cases, supposed to have -originated by the deposition of a great quantity of earthy material -around and upon the masses of ice belonging to the receding front of -the glacier, so that, when at length the ice melted away, a permanent -depression in the soil was left, without any outlet. - -To some extent, however, the kettle-holes may have been formed by the -irregular deposition of streams of water whose courses have crossed each -other, or where eddies of considerable force have been produced in any -way. The ordinary formation of kettle-holes can be observed in progress -on the foot of almost any glacier, or, indeed, on a small scale, during -the melting away of almost any winter's snow. Where, from any cause, a -stratum of dirt has accumulated upon a mass of compact snow or ice, it -will be found to settle down in an irregular manner; furrows will be -formed in various directions by currents of water, so that the melting -will proceed irregularly, and produce upon a miniature scale exactly what -I have seen on a large scale over whole square miles of the decaying foot -of the great Muir Glacier in Alaska. The effects of similar causes and -conditions we can see on a most enormous scale in the ten thousand lakes -and ponds and peat-bogs of the whole glaciated area both in North America -and in Europe. - -In addition to these two lines of evidence of glacial action in New -England, we should mention also the innumerable glacial grooves and -scratches upon the rocks which can be found on almost any freshly -uncovered surface. In New England the direction of these grooves is -ordinarily a little east of south. Upon the east coast of Massachusetts -and New Hampshire the scratches trend much more to the east than they -do over most of the interior. This is as it should be on the glacial -theory, since the ice would naturally move outwards in the line of least -resistance, which would, of course, be towards the open sea wherever -that is near. In the interior of New England the scratches upon the -rocks indicate a more southerly movement in the Connecticut Valley than -upon the mountains in the western part of Massachusetts. This also is as -it should be upon the glacial theory. The scratches upon the mountains -were made when the ice was at its greatest depth and when it moved -over the country in comparative disregard of minor irregularities of -surface, while in the valleys, at least in the later portion of the Ice -age, the movement would be obstructed except in one direction. In the -interpretation of the glacial grooves and scratches it should be borne in -mind that they often represent the work done during the closing stages -of the period. Just as the last shove of the carpenter's plane removes -the marks of the previous work, so the last rasping of a glacial movement -wears away the surfaces which have been previously polished and striated. - -In various places of New England it is interesting as well as instructive -to trace the direction of the ice-movement by the distribution of -boulders. My own attention was early attracted to numerous fragments -of gneiss in eastern Massachusetts containing beautiful crystals -of feldspar, which proved to be peculiar to the region of Lake -Winnepesaukee, a hundred miles to the north, and to a narrow belt -stretching thence to the southwestward. In ascending almost any of the -lower summits of the White Mountains one's attention can scarcely -fail of being directed to the difference between the material of which -the mountains are composed and that of the numerous boulders which lie -scattered over the surface. The local geologist readily recognises these -boulders as pilgrims that have wandered far from their homes to the -northward. - -Trains of boulders, such as those already described in Rhode Island, can -frequently be traced to some prominent outcrop of the rock in a hill or -mountain-peak from which they have been derived. One of the earliest -of these to attract attention occurs in the towns of Richmond, Lenox, -and Stockbridge, in the western part of Massachusetts. Here a belt of -peculiar boulders about four hundred feet wide is found to originate in -the town of Lebanon, N. Y., and to run continuously to the southeast -for a distance of nine miles. West of Fry's Hill, where the outcrop -occurs, no boulders of this variety of rock are to be found, while to -the southeast the boulders gradually diminish in size as their distance -from the outcrop increases. Near the outcrop boulders of thirty feet in -diameter occur, while nine miles away two feet is the largest diameter -observed. - -Sir Charles Lyell endeavoured to explain this train of boulders by the -action of icebergs during a period of submergence--supposing that, as -icebergs floated past or away from this hill in Lebanon, N. Y., they -were the means of the regular distribution described. It is needless to -repeat the difficulties arising in connection with such a theory, since -now both by observation and experiment we have become more familiar -with the movement of glacial ice. What we have already said about the -transportation of boulders over Switzerland by the Alpine glaciers, and -what is open to observation at the present time upon the large glaciers -of Alaska, closely agree with the facts concerning this Richmond train of -boulders, and we have no occasion to look further for a cause. - -Indeed, trains of boulders ought to appear almost everywhere over -the glaciated area; and so they do where all the circumstances are -favourable. But, readily to identify the train, requires that to furnish -the boulders there should be in the line of the ice-movement a projecting -mass of rock hard enough to offer considerable resistance to the abrading -agency of the ice and characteristic enough in its composition to be -readily recognised. Ship Rock, in Peabody, Mass., weighing about eleven -hundred tons, and Mohegan Rock, in Montville, Conn., weighing about ten -thousand tons, have ordinarily been pointed to as boulders illustrating -the power of ice-action. Their glacial character, however, has been -challenged from the fact that the variety of granite to which they -belong occurs in the neighbourhood, and indeed constitutes the bed-rock -upon which they rest.[AV] Some would therefore consider them, like some -of which we have already spoken, to be boulders which have originated -through the disintegration of great masses of rock, of which these were -harder nuclei that have longer resisted the ravages of the tooth of time. -It must be admitted that possibly this explanation is correct; but it -is scarcely probable that, in a region where there are so many other -evidences of glacial action, these boulders could have remained immovable -in presence of the onward progress of the ice-current that certainly -passed over them. - -[Footnote AV: Popular Science Monthly, vol. xxxvii, pp. 196-201.] - -However, as already seen, we are not left to doubt as to the movement -of some boulders of great size. That which now claims the reputation -of being the largest in New England is in Madison, N. H., and measures -thirty by forty by seventy-five feet. This can be traced to ledges of -Conway granite, about two miles away.[AW] Many boulders in the vicinity -of New Haven, Conn., can be identified, as from well-known trap-dykes, -sixteen miles or more to the north. The so-called Judge's Cave, on West -Rock, 365 feet above the adjoining valley and weighing a thousand tons, -is one of these. Professor Edward Orton[AX] describes a mass of Clinton -limestone near Freeport, Warren County, Ohio, as covering an area of -three-fourths of an acre, and as sixteen feet in thickness. It overlies -glacial clays and gravels, and must have been transported bodily from the -elevations containing this rock several miles to the northwest. - -[Footnote AW: See W. 0. Crosby's paper in Appalachia, vol. vi, pp. 59-70.] - -[Footnote AX: Geological Survey of Ohio, vol. iii, p. 385,] - -[Illustration: Fig. 26.--Mohegan Rock.] - -Portions of New England present the best illustrations anywhere afforded -in America of what are called "drumlins." These are "lenticular-shaped" -hills, composed of till, and containing, interspersed through their mass, -numerous scratched stones of all sizes. They vary in length from a few -hundred feet to a mile, and are usually from half to two-thirds as wide -as they are long. In height they vary from twenty-five to two hundred -feet. - -But, according to the description of Mr. Upham, whatever may be their -size and height, they are singularly alike in outline and form, usually -having steep sides, with gently sloping, rounded tops, and presenting a -very smooth and regular contour. From this resemblance in shape to an -elliptical convex lens, Professor Hitchcock has called them lenticular -hills to distinguish these deposits of till from the broadly flattened or -undulating sheets which are common throughout New England. - -[Illustration: Fig. 27.--Drumlins in Goffstown, N. H. (Hitchcock).] - -The trend, or direction of the longer axis, of these lenticular hills is -nearly the same for all of them comprised within any limited area, and is -approximately like the course of the striæ or glacial furrows marked upon -the neighbouring ledges. In eastern Massachusetts and New Hampshire, -within twenty-five miles of the coast, it is quite uniformly to the -southeast, or east-southeast. Farther inland, in both of these States, -it is generally from north to south, or a few degrees east of south; -while in the valley of the Connecticut River it is frequently a little to -the west of south. In New Hampshire, besides its accumulation in these -hills, the till is frequently amassed in slopes of similar lenticular -form. These have their position almost invariably upon either the south -or north side of the ledgy hills against which they rest, showing a -considerable deflection towards the southeast and northwest in the east -part of the State. It cannot be doubted that the trend of the lenticular -hills, and the direction taken by these slopes, have been determined -by the glacial current, which produced the striæ with which they are -parallel.[AY] - -[Footnote AY: Proceedings of the Boston Society of Natural History, vol. -xx, pp. 224, 225.] - -Drumlins are abundant in the vicinity of Boston, and constitute nearly -all the islands in Boston Harbour. On the mainland, Beacon Hill, Bunker -Hill, Green Hill, Powderhorn Hill, Tufts College Hill, Winter Hill, Mount -Ida, Corey Hill, Parker Hill, Wollaston Heights, Prospect Hill, and -Telegraph Hill are specimens. - -The northeastern corner of Massachusetts and the southeastern corner -of New Hampshire are largely covered with these peculiar-shaped -glacial deposits, while they are numerous as far west as Fitchburg, -in Massachusetts, and Ware, N. H., and in the northeastern part of -Connecticut. A little later, also, we shall refer to an interesting line -of them in central New York. Elsewhere in America, except in a portion of -Wisconsin, they rarely occur in such fine development as in New England. -In Europe they are best developed in portions of Ireland. - -One's first impression in examining an exposed section of a drumlin -would lead him to think that the mass was entirely unstratified; but -closer examination shows that there is a coarse stratification, but -evidently not produced by water-action. The accumulation has probably -taken place gradually by successive deposits underneath the glacier -itself. Professor William M. Davis has suggested a plausible explanation -which we will briefly state. - -[Illustration: Fig. 28.--Drumlins in the vicinity of Boston (Davis).] - -The frequency with which drumlins are found to rest upon a mass of -projecting rock, the general co-ordination of the direction of their -axes with the direction of the scratches upon the underlying rock, and -the abundance of scratched stones in them, all support the theory that -drumlins are formed underneath the ice-sheet, somewhat in the way that -islands and bars of silt are formed in the delta of a great river. The -movement of ice seems to have been concentrated in pretty definite -lines, often determined by the contour of the bottom, leaving a slacker -movement in intervening areas, which were evidently protected in some -cases by projecting masses of rock. In these areas of slower movement -there was naturally an accumulation at the same time that there was -vigorous erosion in the lines of more rapid movement. - -There was doubtless a continual transfer of material from the end of the -drumlin which abutted against the moving mass of ice to the lower end, -as there is in the formation of an island in a river. If time enough had -elapsed, the whole accumulation would have been levelled by the glacier -and spread over the broader area where the more rapid lines of movement -became confluent, and where the differential motion was less marked. -Drumlins are thus characteristic of areas in the glaciated region whose -floor was originally only moderately irregular, and where there was an -excessive amount of ground-moraine to be transported, and where the -movement did not continue indefinitely. It has been suggested, also, -that some of the long belts of territory in New England and central New -York covered by drumlins may represent old terminal moraines which were -subsequently surmounted by a readvance of the ice, and partially wrought -over into their present shape. - -It is in New England, also, that kames are to be found in better -development than anywhere else in America. These interesting remnants of -the Glacial age are clearly described by Mr. James Geikie. His account -will serve as well for New England as for Scotland. - -The sands and gravels have a tendency to shape themselves into mounds -and winding ridges, which give a hummocky and rapidly undulating outline -to the ground. Indeed, so characteristic is this appearance, that by it -alone we are often able to mark out the boundaries of the deposits with -as much precision as we could were all the vegetation and soil stripped -away and the various subsoils laid bare. Occasionally, ridges may be -tracked continuously for several miles, running like great artificial -ramparts across the country. These vary in breadth and height, some of -the more conspicuous ones being upward of four or five hundred feet -broad at the base, and sloping upward at an angle of twenty-five or even -thirty-five degrees, to a height of sixty feet and more above the general -surface of the ground. It is most common, however, to find mounds and -ridges confusedly intermingled, crossing and recrossing each other at all -angles, so as to enclose deep hollows and pits between. Seen from some -dominant point, such an assemblage of kames, as they are called, looks -like a tumbled sea--the ground now swelling into long undulations, now -rising suddenly into beautiful peaks and cones, and anon curving up in -sharp ridges that often wheel suddenly round so as to enclose a lakelet -of bright clear water.[AZ] - -[Footnote AZ: The Great Ice Age, pp. 210, 211.] - -[Illustration: Fig. 29.--Section of kame near Dover, New Hampshire. -Length, three hundred feet; height, forty feet; base, about forty feet -above the Cocheco River, or seventy-five feet above the sea. _a_, _a_, -gray clay; _b_, fine sand; _c_, _c_, coarse gravel containing pebbles -from six inches to one foot and a half in diameter; _d_, _d_, fine gravel -(Upham).] - -[Illustration: Fig. 30.--Kames in Andover Mass.] - -In New England attention was first directed to kames in 1842, by -President Edward Hitchcock, in a paper before the American Association -of Geologists and Naturalists, describing the gravel ridges in Andover, -Mass. In the accompanying plate is shown a portion of this kame system, -which has a double interest to me from the fact that it was while living -upon the banks of the Shawshin River, near where the kames and the river -intersect, that I began, in 1874, my special study of glacial deposits. -The Andover ridges are composed of imperfectly stratified water-worn -material, and are very sharply defined, from the town of Chelsea, back -from the coast into New Hampshire, for a distance of twenty-five miles. -The base of the ridges does not maintain a uniform level, but the system -descends into shallow valleys, and rises over elevations of one hundred -to two hundred feet, without interruption. This indifference to slight -changes of level is specially noticeable where the system crosses the -Merrimac River, just above the city of Lawrence. It is also represented -in the accompanying plate, where the base of the ridges in the immediate -valley of the Shawshin is fifty feet lower than the base of those a short -distance to the north, at the points marked _a_, _b_, and _c_. The ridges -here terminate at the surface in a sharp angle, and are above their base -forty-one feet at _a_, forty-nine feet at _b_, and ninety-one feet at -_c_. Between _c_ and _b_ there is an extensive peat-swamp, filling the -depression up to the level of an outlet through which the surplus water -has found a passage. - -[Illustration: Fig. 31.--Longitudinal kames near Hingham, Massachusetts. -The parallel ridges of gravel in the foreground run nearly east and west, -and coalesce at each end, near the edges of the picture, to form an -elongated kettle-hole. The ridges from fifty to sixty feet in height. The -kame-stream was here evidently emptying into the ocean a few miles to the -east (Bouvé).] - -Several systems of kames approximately parallel to this have been -traced out in Massachusetts and New Hampshire, while the remnants of -a very extensive system are found in the Connecticut Valley above the -Massachusetts line. But they abound in greatest profusion in the State -of Maine, where Professor George H. Stone has plotted them with much -care. The accompanying map gives only an imperfect representation of the -ramifying systems which he has traced out, and of the extent to which -they are independent of the present river-channels. One of the longest -of these extends more than one hundred miles, crossing the Penobscot -River nearly opposite Grand Lake, and terminating in an extensive delta -of gravel and sand in Cherryfield, nearly north of Mount Desert. This -is represented on our map by the shaded portion west of the Machias -River. Locally these ridges are variously designated as "horsebacks," -"hogbacks," or "whalebacks," but that in Andover, Mass., was for some -reason called "Indian Ridge." Nowhere else in the world are these ridges -better developed than in New England, except it be in southern Sweden, -where they have long been known and carefully mapped. - -[Illustration: Fig. 32.--The kames of Maine and southeastern New -Hampshire. (Stone.)] - -The investigations of Mr. W. 0. Crosby upon the composition of till in -eastern Massachusetts is sufficiently important in its bearings upon the -question of glacial erosion to merit notice at this point.[BA] The object -of his investigations was to determine how much of the so-called ground -moraine, or till, consisted of material disintegrated by mechanical -action, and how much by chemical action. The "residuary clay," which has -arisen from chemical decomposition, would properly be attributed to the -disintegrating agencies of preglacial times, while the clay, which is -strictly mechanical in its origin, remains to represent the true "grist" -or "rock flour" of the Glacial period. - -[Footnote BA: Proceedings of the Boston Society of Natural History, vol. -xxv (1890), pp. 115-140.] - -The results of Mr. Crosby's investigations show that "not more than -one-third of the _detritus_ composing the till of the Boston Basin was in -existence before the Ice age, and that the remaining two-thirds must be -attributed to the mechanical action of the ice-sheet and its accompanying -torrents of water. In other words, if we assume the average thickness -of the drift as thirty feet, the amount of glacial erosion can scarcely -fall below twenty feet. After scraping away the residuary clays and -half-decomposed material, the ice-sheet has cut more than an equal depth -into the solid rocks." - -Mr. Crosby's investigations also convinced him that the movement of the -till, or ground moraine, underneath the ice was not _en masse_, but that -"it must have experienced differential horizontal movements or flowing, -in which, normally, every particle or fragment slipped or was squeezed -forward with reference to those immediately below it, the velocity -diminishing downward through the friction of the underlying ledges.... -The glaciation was not limited to masses which were firmly caught between -the ice and the solid ledges, and it was in every case essentially a -slipping and not a rolling movement.... These differential horizontal -movements mean that the till acted as a lubricant for the ice-sheet; -and the clayey element, especially, co-operating in many cases with the -pent-up subglacial waters, must have greatly facilitated the onward -progress of the ice." He concludes, therefore, that the onward movement -of the vast ice-sheet greatly exceeded that of the main part of the -ground moraine, the ice-sheet slipping over the till, the whole being -in some degree analogous to that of a great land-slip. "In both cases -the progress of a somewhat yielding and mobile mass is facilitated by an -underlying clayey layer saturated with water." - - -_New York, New Jersey, and Pennsylvania._ - -West of New England the glacial phenomena over the northern part of the -United States are equally marked all the way to the Missouri River, and -the boundary-line of the glaciated region can be traced with little -difficulty. It emerges from New York Bay on Staten Island and enters New -Jersey at Perth Amboy. A well-formed moraine covers the northern part -of Staten Island, and upon the mainland marks the boundary from Perth -Amboy, around through Raritan, Plainfield, Chatham, Morris, and Hanover, -to Rockaway, and thence in a southwesterly direction to Belvidere, on -the Delaware River. That portion of New Jersey lying north of this -serpentine line of moraine hills is characterised by the presence of -transported boulders, by numerous lakes of evident glacial origin, and by -every other sign of glacial action, while south of it all these peculiar -characteristics are absent. The observant passenger upon the railroad -trains between New York and Philadelphia can easily recognise the -moraine as it is passed through on the Pennsylvania Railroad at Metuchen -and on the Bound Brook Railroad at Plainfield. Near Drakestown, in -Morris County, there is a mass of blue limestone measuring, as exposed, -thirty-six by thirty feet, and which was quarried for years before -discovering that it was a boulder brought with other drift material from -many miles to the northwest and lodged here a thousand feet above the sea. - -Across Pennsylvania the glacial boundary passes through Northampton, -Monroe, Luzerne, Columbia, Sullivan, Lycoming, Tioga, and Potter -Counties, where it enters the State of New York, running still in a -northwest direction through Allegany and Cattaraugus Counties to the -vicinity of Salamanca. Here it turns to the south nearly at a right -angle, running southwestward to Chautauqua County and re-entering -Pennsylvania in Warren County, and thence passing onward in the same -general direction through Crawford, Venango, Mercer, Butler, and Lawrence -Counties to the Ohio line in Columbiana County, about ten miles north of -the Ohio River. - -The occurrence of a well-defined terminal moraine to mark the glacial -boundary eastward from Pennsylvania led Professor Lewis and myself, who -made the survey of that State in 1880, to be rather too sanguine in -our expectations of finding an equally well-marked moraine everywhere -along the southern margin of the glaciated area; still, the results are -even more interesting than would have been the exact fulfilment of our -expectations, since they more fully revealed to us the great complexity -of effect which is capable of being brought about by ice-action. Before -proceeding farther with the details, therefore, it will be profitable -at this point to pause in the narrative and briefly record a few -generalisations that have forced themselves into prominence during the -years in which field-work has been in progress. - -Previous to our explorations in Pennsylvania it had been thought that the -indications of ice-action would extend much farther south in the valleys -than on the mountains, and this indeed would have been the case if the -glaciers in northern Pennsylvania had been of local origin; but our -experience very soon demonstrated that the great gathering-place of the -snows which produced the glacial movement in northern Pennsylvania could -not have been local, but that over the northern part of that State there -was distinct evidence of a continental movement of ice whose centre was -far beyond the Alleghanies. - -For example, we found that the evidences of direct glacial action -extended farther south upon the hills and plateaus than they did in the -narrow valleys, while everywhere on the very southern border of glacial -indications we found boulders that had been brought from the granitic -region of northern New York or central Canada. In eastern Pennsylvania -we found indeed a terminal moraine more or less distinctly marking the -southern border over the highlands. This was more specially true in -Northampton and Monroe Counties. - -In Northampton County it was very interesting to see long lines of hills, -a hundred or more feet in height and lying several hundred feet above -the Delaware River, composed entirely of glacial _débris_, much of which -had been brought bodily over the sharp summit of the Blue Ridge, or -Kittatinny Mountain, which rises as a continuous wall to the northwest -and is everywhere several hundred feet higher than the moraine in -Northampton County. The summit of Blue Ridge, also, as far south as the -glacial movement extended, shows evident signs of glacial abrasion, some -hundreds of feet evidently having been removed by that means, leaving a -well-defined shoulder, marking the limits of its southwestern border. -Resting upon the summit of the glaciated portion of the Blue Ridge, there -are also numerous boulders of Helderberg limestone, which must have been -brought from ledges at least five hundred feet lower than the places upon -which they now lie. - -In Monroe County the terminal moraine marking there the extreme limit -of the ice-movement is upon an extensive plateau of Pocono sandstone, -about eighteen hundred feet above sea-level, and five or six hundred -feet lower than the crest of the Alleghany Mountains, a short distance -to the north. The moraine hills are here well marked by the occurrence -of circular lakelets and kettle-holes (such as have been described -as characteristic of the shores and islands bordering the south of -New England); by the occurrence of granitic boulders, which must have -been brought from the Adirondacks or Canada; and by the various other -indications referred to on a previous page. - -As already intimated, the instructive point in our observations is the -fact that, between Kittatinny Mountain, in Northampton County, and Pocono -plateau, in Monroe County, there is a longitudinal depression, running -northeast by southwest, parallel with the ranges of the mountain system, -which is here about a thousand feet below the respective ridges on either -side. This, therefore, is one of the places where we should have expected -a considerable southern extension of the ice, if it had been largely due -to local causes. Now, while there is indeed a gradual southern trend down -the flanks of the mountain, yet, upon reaching the axis of the valley, -there appears at once a very marked change in the character of the -deposit, and the influence of powerful streams of water becomes manifest, -and it is evident, upon a slight inspection, that we have come upon a -line of drainage which sustained a peculiar relation to the continental -ice-sheet. - -From Stroudsburg, near the Delaware Water-Gap, to Weissport, on the -Lehigh River, a distance of about thirty miles, the valley between the -mountains is continuous, and the elevation at each end very nearly the -same. But about half-way between the two places, near Saylorsburg, there -is a river-parting from which the water now runs on the one hand north -to Stroudsburg, and thence to the Delaware River, and on the other hand -south, through Big and Aquonchichola Creeks, to the Lehigh River. The -river-parting is formed by a great accumulation of gravel, whose summit -is about two hundred feet above the level of the valleys into which -the creeks empty at either end; and there are numerous kettle-holes and -lakelets in the vicinity, such as characterize the glacial region in -general. - -In short, we are, without doubt, here on a well-marked terminal moraine -much modified by strong water-action in a valley of glacial drainage. -The gravel and boulders are all well water-worn, and the material is of -various kinds, including granite boulders from the far north, such as -characterise the terminal moraine on the highlands; but the pebbles are -not scratched, and the gravel is more or less stratified. It is evident -that we are here where a violent stream of water poured forth from that -portion of the ice-front which filled this valley, and which found its -only outlet in the direction of the Lehigh River. The gravel can be -traced in diminishing quantities to the southward, in accordance with -this theory, while to the northward there extends a series of gravel -ridges, or kames, such as we have shown naturally to owe their origin to -the accumulations taking place in ice-channels formed near the front of a -glacier as it slowly melts away. - -From similar occurrences of vast gravel accumulations in other valleys -stretching southward from the glacial margin, we came to expect that, -wherever there was an open, line of drainage from the glaciated region -southward, the point of intersection between the glacial margin and -the drainage valley would be marked by an excessive accumulation of -water-worn gravel, diminishing in coarseness and abundance down the -valleys in proportion to the distance from the glacial margin. - -For example, the Delaware River emerges from the glaciated region at -Belvidere, and there are there vast accumulations of gravel rising a -hundred or more feet above the present level of the river, while gravel -terraces, diminishing in height, mark the river below to tide-water at -Trenton. The Lehigh River leaves the glaciated region at Hickory Run, a -few miles above Mauch Chunk, but the gorge is so steep that there was -little opportunity either for the accumulation of gravel there or for its -preservation. Still, the transported gravel and boulders characteristic -of the melting floods pouring forth from a glacier, are found lining the -banks of the Lehigh all along the lower portion of its course. In the -Susquehanna River we have a better example at Beach Haven, in Luzerne -County, where there are very extensive accumulations of gravel resting -on the true glacial deposits of the valley, and extending down the river -in terraces of regularly diminishing height for many miles, and merging -into terraces of moderate elevation which line the Susquehanna Valley -throughout the rest of its course. Above Beach Haven the gravel deposits -in the trough of the river valley are more irregular, and betray the -modifying influence of the slowly decaying masses of ice which belonged -to the enveloping continental glacier. - -Westward from the north fork of the Susquehanna, similar extensive -accumulations of gravel occur at the intersection of Fishing Creek in -Columbia County, Muncy, Loyalsock, Lycoming, and Pine Creeks in Lycoming -County, all tributary to the Susquehanna River, and all evidently being -channels through which the melting floods of the ice-sheet brought -vast quantities of gravel down to the main stream. Williamsport, on -the West Branch of the Susquehanna, is built upon an extensive terrace -containing much granitic material, brought down from the glaciated region -by Lycoming Creek, when it was flooded with the waters melted from the -continental ice-sheet which had here surmounted the Alleghanies and -invaded the valley of the Susquehanna. - -Analogous deposits of unusual amounts of gravel, occurring in streams -flowing southward from the glaciated region, occur at Great Valley, -Little Valley, and Steamburg in Cattaraugus County, New York, and -at Russelburg and Garland in Warren County, Pennsylvania, also at -Titusville and Franklin in Venango County, and at Wampum in Lawrence -County, of the same State. - -As a rule, Professor Lewis and myself found it more difficult to -determine with accuracy the exact point to which the ice extended in -the axis of these south-flowing valleys than we did upon the highlands -upon either side; and, in looking for the positive indications of direct -ice-action in these lines of drainage, we were almost always led up -the valley to a considerable distance inside of the line. This arose -from our inexperience in interpreting the phenomena, or rather from -our inattention to the well-known determining facts in the problem. On -further reflection it readily appeared that this was as it should be. The -ice-front, instead of extending farther down in a narrow valley than on -the adjoining highlands (where they are of only moderate elevation) ought -not to extend so far, for the subglacial streams would not only wear away -the ice of themselves, but would admit the air into the tunnels formed by -them so as to melt the masses both from below and from above, and thus -cause a recession of the front. If we had understood this principle at -the beginning of our survey, it would have saved us much perplexity and -trouble. - -A single further illustration of this point will help to an understanding -of many references which will hereafter be made to the water deposits -which accumulated in the lines of drainage running southward from the -glaciated area. At Warren, Pa., Conewango Creek, which is the outlet -from Chautauqua Lake, enters the Alleghany River after flowing for a -number of miles in a deep valley with moderate slopes. In ascending the -creek from Warren, the gravel terraces, which rise twenty-five or thirty -feet above high-water mark, rapidly increase in breadth and height, and -the pebbles become more and more coarse. After a certain distance the -regular terraces begin to give place to irregular accumulations of gravel -in ridges and knobs. In the lower portion of the valley no pebbles -could be found which were scratched. Up the valley a few miles pebbles -were occasionally discovered which showed some slight indications of -having been scratched, but which had been subjected to such an amount of -abrasion by water-action as almost to erase the scratches. On reaching -Ackley's Station, the stream is found to be cutting through a regular -terminal moraine, extending across the valley and full of clearly marked -glaciated stones. Above this terminal moraine the terraces and gravel -ridges which had characterised the valley below disappear, giving place -to long stretches of level and swampy land, which had been subject to -overflow. - -Something similar to this so often appears, that there can be no -question as to its meaning, which is, that during the farthest extent -of the ice the front rested for a considerable period of time along the -line marked by the terminal moraine. During this period there occurred -both the accumulation of the moraine and of the gravel terraces in the -valley below, due to the vast flow of water emerging from the ice-front, -especially during the period when it was most rapidly melting away. Upon -the retreat of the ice, the moraine constituted a dam which has not yet -been wholly worn away. For a while the water was so effectually ponded -back by this as to form a lake, which has since become filled up with -sediment and accumulations of peat. From this it is evident, also, that -when the ice began to retreat, the retreat was so continuous and rapid -that no parallel terminal moraines were formed for many miles. - -Before leaving this section we will summarise the leading facts -concerning the glacial phenomena north of Pennsylvania and New Jersey. -From the observations of Professor Smock, it appears that, from the -southern margin the ascent to the summit of the ice-sheet was pretty -rapid; the depth one mile back from the margin being not much less -than a thousand feet. "Northward the angle of the slope diminished, and -the glacier surface approximated to a great level plain. The distance -between the high southwestern peaks of the Catskills and Pocono Knob -in Pennsylvania is sixty miles. The difference in the elevation of the -glacier could not have exceeded a thousand feet,"[BB] that is, the slope -of the surface was about seventeen feet to the mile. - -[Footnote BB: American Journal of Science, vol. cxxv, 1883, p. 339 _et -seq._] - -Professor Dana estimates the thickness of the ice in southern Connecticut -to have been between fifteen hundred and two thousand feet. Attempts to -calculate the thickness of the ice farther north, except from actual -discovery of glacial action on the summits of the mountains, are based -upon uncertain data with reference to the slope necessary to secure -glacial movement. In the Alps the lowest mean slopes down which glaciers -move are about two hundred and fifty feet to a mile; but in Greenland, -Jensen found the slope of the Frederickshaab Glacier to be only -seventy-five feet to the mile, while Helland found that of the Jakobshavn -Glacier to be only forty-five feet. - -It is doubtful if even that amount is necessary to secure a continental -movement of ice, since, as already remarked, it is unsafe to draw -inferences concerning the movements of large masses of ice from those of -smaller masses in more constricted areas. We have seen, from the glacial -deposits on the top of Mount Washington, that over the northern part of -New England the ice was more than a mile in depth. We have no direct -evidence of the depth of the stream which surrounded the Adirondack -Mountains. Nor, on the other hand, are we certain that the Catskills -were not completely enveloped in ice, though most observers, reasoning -from negative evidence, have supposed that to be the case. But from the -facts stated concerning the boulders along the glacial boundary in -Pennsylvania, it is certain that the ice was deep enough to surmount -the ridge of the Alleghanies where they are two thousand and more feet -in height. At the least calculation the ice must have been five hundred -feet thick, in order to secure the movement of which there is evidence -across the Appalachian range. Supposing this to be the height of the ice -above the sea on the crest of the Alleghanies, and that the slope of the -surface of the ice-sheet was as moderate as Professor Smock has estimated -it (namely seventeen feet to the mile), the ice would be upwards of -six thousand feet in thickness in the latitude of the Adirondacks, -which corresponds closely with the positive evidence Ave have from the -mountains in New England. - -A study of the map of New York will make it easy to understand the -distribution of some interesting glacial marks over the State. The -distance along the Hudson from the glacial boundary in the vicinity of -New York to the valley of the Mohawk is about one hundred and sixty -miles. Prom the glacial boundary at Salamanca, N. Y., to the same valley, -is not over eighty miles. It is easy to see, therefore, that when, in -advancing, the ice moved southward past the Adirondacks, the east end -of the valley of the Mohawk was reached and closed by the ice, while at -the west end of Lake Ontario the ice-front was still in Canada. Thus the -drainage, which naturally followed the course of the St. Lawrence, would -first be turned through the Mohawk. Afterwards, when the Mohawk had been -closed by ice, the vast amount of ponded water was compelled to seek a -temporary outlet over the lower passages leading into the Susquehanna or -into the Alleghany. - -A number of such passages exist. One can be traced along the line of the -old canal from Utica to Binghamton, whose highest level is not far from -eleven hundred feet. Another lies in a valley leading south of Cayuga -Lake, whose highest point, at Wilseyville, is nine hundred and forty -feet above tide. Another leads south to the Chemung River from Seneca -Lake, whose highest point, at Horseheads, is less than nine hundred feet -above tide. The cols farther west are somewhat more elevated; the one at -Portage, leading from the Genesee River into the Canisteo, being upwards -of thirteen hundred feet, and that of Dayton, leading from Cattaraugus -Creek into the Conewango, being about the same. Of other southern outlets -farther west we will speak later on. - -Fixing our minds now upon the region under consideration, in the southern -part of the State of New York, we can readily see that a glacial lake -must have existed in front of the ice while it was advancing, until it -had reached the river-partings between the Mohawk and the St. Lawrence -Rivers on the north and the Susquehanna and Alleghany Rivers on the -south. After the ice had attained its maximum extension, and was in -process of retreat, there would be a repetition of the phenomena, only -they would occur in the reverse order. The glacial markings which we see -are, of course, mainly those produced during the general retreat of the -ice. - -The Susquehanna River stretching out its arms--the Chenango and Chemung -Rivers--to the east and the west, evidently serves as a line of drainage -for the vast glacial floods. These floods have left, along their courses, -extensive elevated gravel terraces, with much material in them which -is not local, but which has been washed out of the direct glacial -deposits from the far north. The east-and-west line of the water-parting -throughout the State is characterised by excessive accumulations of -glaciated material, forming something like a terminal moraine, and is -designated by President Chamberlin as "the terminal moraine of the second -Glacial epoch," corresponding, as he thinks, to the interior line already -described as characterising the south shore of New England. - -In the central part of New York the remarkable series of "Finger Lakes," -tributary to Lake Ontario and emptying into it through the Oswego and -Genesee Rivers, all have a glacial origin. Probably, however, they are -not due in any great degree to glacial erosion, but they seem to occupy -north-and-south valleys which had been largely formed by streams running -towards the St. Lawrence when there was, by some means (probably through -the Mohawk River), a much deeper outlet than now exists, but which has -been filled up and obliterated by glacial _débris_. The ice-movement -naturally centred itself more or less in these north-and-south valleys, -and hence somewhat enlarged them, but probably did not deepen them. The -ice, however, did prevent them from becoming filled with sediment, and on -its final retreat gave place to water. - -Between these lakes and Lake Ontario, also, and extending east and west -nearly all the way from Syracuse to Rochester, there is a remarkable -series of hills, from one hundred to two or three hundred feet in height, -composed of glacial _débris_. But while the range extends east and west, -the axis of the individual hills lies nearly north and south. These are -probably remnants of a morainic accumulation which were made during -a pause in the first advance of the ice, and were finally sculptured -into their present shape by the onward movement of the ice. These are -really "drumlins," similar to those already described in northeastern -Massachusetts and southeastern New Hampshire. In the valley of central -New York these have determined the lines of drainage of the "Finger -Lakes," and formed dams across the natural outlets of nearly all of them. - -North of the State of New York the innumerable lakes in Canada are all -of glacial origin, being mostly due to depressions of the nature of -kettle-holes, or to the damming up of old outlets by glacial deposits. A -pretty well-marked line of moraine hills, formed probably as terminal -deposits in the later stages of the Ice age, runs from near the eastern -end of Lake Ontario to the Georgian Bay, passing south of Lake Simcoe. - - -_The Mississippi Basin._ - -The physical geography of the glaciated region north of the Ohio River is -so much simpler than that of New England and the Middle States, that its -characteristics can be briefly stated. Ohio, Indiana, and Illinois are -covered with nearly parallel strata of rock mostly of the Carboniferous -age. In general, the surface slopes gently to the west; the average -elevation of Ohio being about a thousand feet above tide, while that of -the Great Lakes to the north and of the middle portion of the Mississippi -Valley is less than six hundred feet. The glacial deposits are spread in -a pretty even sheet over the area which was reached by the ice in these -States, and the lines of moraine, of which a dozen or more have been -partially traced in receding order, are much less clearly marked than -they are in New England, or in Michigan, and the States farther to the -northwest. - -The line marking the southern limit attained by the ice of the Glacial -period in these three States is as follows: Entering Ohio in Columbiana -County, about ten miles north of the Ohio River, the glacial boundary -runs westward through New Lisbon to Canton in Stark County, and thence -to Millersburg in Holmes County. A few miles west of this place it -turns abruptly south, passing through Danville in Knox County, Newark -in Licking County, Lancaster in Fairfield County, to Adelphi in Ross -County. Thence bearing more westward it passes through Chillicothe -to southeastern Highland County and northwestern Adams, reaching the -Ohio River near Ripley, in Clermont County. Thence, following the -north bank of the Ohio River to Cincinnati, it crosses the river, and -after extending through the northern part of Boone County, Kentucky, -and recrossing the river to Indiana, not far from Rising Sun, it again -follows approximately the north bank of the river to within about ten -miles of Louisville, Ky., where it bends northward running through -Clarke, Scott, Jackson, Bartholomew, and Brown Counties to Martinsville, -in Morgan County, where it turns again west and south and follows -approximately the West Branch of the White River through Owen, Greene, -and Knox Counties, where it crosses the main stream of White River, and, -continuing through Gibson and Posey Counties, crosses the Wabash River -near New Harmony. - -In Illinois the line still continues southwesterly through White, -Gallatin, Saline, and Williamson Counties, where it reaches its southern -limit near Carbondale, in latitude 37° 40', and from this point trends -northwestward, approximately following the northeastern bluff of the -Mississippi River, to the vicinity of Carondelet, Mo., a short distance -south of St. Louis. - -Beyond the Mississippi the line follows approximately the course of the -Missouri River across Missouri, and continues westward to the vicinity of -Manhattan, in Kansas, where it turns northward, keeping about a hundred -miles west of the Missouri River, through eastern Kansas and Nebraska, -and striking the river near the mouth of the Niobrara, in South Dakota. -From there the line follows approximately the course of the Missouri -River to the vicinity of Fort Benton, in northwestern Montana, where the -line again bears more northward, running into British America. - -It is still in dispute whether the ice extended from the eastern centre -far enough west to join the ice-movement from the Rocky Mountain -plateau. Dr. George M. Dawson[BC] is of the opinion that it did not, but -that there was a belt of a hundred miles or more, east of the Rocky -Mountains, which was never covered by true glacial ice. Mr. Upham[BD] -is equally confident that the two ice-movements became confluent, -and united upon the western plateau of Manitoba. The opportunity -for such a difference of opinion arises in the difficulty sometimes -encountered of distinguishing between a direct glacial deposit and a -deposit taking place in water containing boulder-laden icebergs. Where -Mr. Upham supposes the ice-fields of the east and of the west to have -been confluent in western Manitoba, Dr. Dawson supposes there was an -extensive subsidence of the land sufficient to admit the waters of the -ocean. Leaving this question for the present undetermined, we will now -rapidly summarise the glacial phenomena west of the third meridian -from Washington (which corresponds nearly with the western boundary of -Pennsylvania), and east of the Rocky Mountains. - -[Footnote BC: Transactions of the Royal Society of Canada, vol. viii, -sec. iv, pp. 54-74.] - -[Footnote BD: American Geologist, vol. vi, September, 1890; Bulletin of -the Geological Society of America, vol. ii, pp. 243-276.] - -That the glacial movement extended to the southern boundary just -delineated is established by the presence down to that line of all the -signs of glacial action, and their absence beyond. Glacial groovings are -found upon the freshly uncovered rock surfaces at frequent intervals in -close proximity to the line all along its course, while granitic boulders -from the far north are scattered, with more or less regularity, over the -whole intervening space between this line and the Canadian highlands. -I have already referred to a boulder of jasper conglomerate found in -Boone County, Kentucky, which must have come from unique outcroppings of -this rock north of Lake Huron. Granitic boulders from the Lake Superior -region are also found in great abundance at the extreme margin mentioned -in southern Illinois. West of the Missouri River it is somewhat more -difficult to delineate the boundary with accuracy, on account of an -enveloping deposit of fine loam, technically called "loess." Loess is -very abundant in the whole valley of the Missouri River below Yankton, -South Dakota, being for a long distance in the vicinity of the river -a hundred feet or more in depth. Over northern Missouri and southern -Illinois the deposit is nearly continuous, but less in depth, and -everywhere in that region tends to hide from view the unstratified -glacial deposit continuously underlying it. - -A single instance of personal experience will illustrate the condition of -things. While going south from Chicago, in search of the southern limit -of glacial action, I stopped off from the train at Du Quoin, about forty -miles north of where I subsequently found the boundary. Here the whole -surface was covered with loess, two or three feet in depth. Below this -was a gravelly soil, three or four feet in thickness, which contained -many scratched pebbles of granite. A well which had recently been dug, -reached the rock at a depth of twenty feet, and revealed a beautifully -polished and scratched surface, betraying, beyond question, the action -of glacial ice. As we shall show a little later, it is probable that, -about the time the ice of the Glacial period had reached its maximum -development, this area, which is covered with loess, was depressed in -level, and remained under water during a considerable portion of the -period when the ice-front was retreating. - -[Illustration: Fig. 33.--Western face of the kettle-moraine, near Eagle, -Waukesha County, Wisconsin. (From a photograph by President T. C. -Chamberlain, United States Geological Survey.)] - -To such an extent is this portion of the area included in southern -Iowa, northern Missouri, southern Illinois, and the extreme southern -portions of Indiana and Ohio covered with loess, that it has been -difficult to determine the relation of its underlying glacial deposits -to the more irregular deposits found farther north. At an early period -of recent investigations, while making a geological survey of the State -of Wisconsin, President T. C. Chamberlin fixed upon the line of moraine -hills, which can be seen upon our map, running southward between Green -Bay and Lake Michigan, and sweeping around in a curve to the right, -passing south of Madison and northward along the line of Wisconsin -River, and in another curve to the left, around the southern end of Lake -Michigan, as the "terminal moraine of the second Glacial epoch." In -Wisconsin the character of this line of moraine hills had been discovered -and described by Colonel Charles Whittlesey, in 1866. It was first -named the "kettle-moraine," because of the frequent occurrence in it of -"kettle-holes." This line of moraine hills has been traced with a great -degree of confidence across the entire glaciated area, as shown upon our -map, but it is not everywhere equally distinct, and, as will be observed, -follows a very irregular course. - -Beginning in Ohio we find it coinciding nearly with the extreme glacial -boundary until it reaches the valley of the Scioto River, on the sixth -meridian west from Washington, where it begins to bear northward and -continues in that direction for a distance of sixty or seventy miles, -and then turns southward again in the valley of the Miami, having formed -between these two valleys a sort of medial moraine.[BE] A similar medial -moraine had also been noted by President Chamberlin between the valleys -of the Grand and Cuyahoga Rivers, in the eastern part of Ohio. Indeed, -for the whole distance across Ohio and Indiana, this moraine occurs in a -series of loops pointing to the south, corresponding in general to the -five gentle valleys which mark the territory, namely, those of the Grand -and Mahoning Rivers; the Sandusky and Scioto Rivers; the Great Miami -River; the White River; and the Maumee and Wabash Rivers. Everywhere, -however, over this area these morainic accumulations approximate pretty -closely to the extreme boundary of the glaciated region. - -[Footnote BE: See map at the beginning of the chapter.] - -In Illinois President Chamberlin's original determination of the moraine -fixed it near the southern end of Lake Michigan, as shown upon our map, -but Mr. Frank Leverett has subsequently demonstrated that there is a -concentric series of moraines south of this, reaching across the State, -(but somewhat obscured by superficial accumulations of loess referred to) -and extending nearly to the latitude of St. Louis. - -West of Wisconsin President Chamberlin's "terminal moraine of the second -Glacial epoch" bends southward through eastern Minnesota, and, sweeping -down through central Iowa, forms, near the middle of the northern part -of that State, a loop, having its southern extremity in the vicinity of -Des Moines. The western arm of this loop runs through Minnesota in a -northwesterly direction nearly parallel with the upper portion of the -valley of the Minnesota, until reaching the latitude of the head-waters -of that river, where, in the vicinity of the Sisseton Agency, in Dakota, -it turns to the south by an acute angle, and makes a loop in that State, -extending to the vicinity of Yankton, and with the valley of the James -River as its axis. The western arm of this loop follows pretty closely -the line of the eastern edge of the trough of the Missouri River, -constituting what is called the "Missouri Coteau," which continues on as -a well-marked line of hills running in a northwesterly direction far up -into the Dominion of Canada. - -One of the most puzzling glacial phenomena in the Mississippi Valley is -the driftless area which occupies the southeastern portion of Minnesota, -the southwestern part of Wisconsin, and the northwestern corner of Iowa, -as delineated upon our map. This is an area which, while being surrounded -on every side by all the characteristic marks of glaciation, is itself -conspicuous for their entire absence. Its rocks preserve no glacial -scratches and are covered by no deposits of till, while northern boulders -avoided it in their journey to more southern latitudes. - -The reason for all this is not evident in the topography of the region. -The land is not higher than that to the north of it, nor is there any -manifest protection to it by the highlands south of Lake Superior. Nor -yet is there any reason to suppose that any extensive changes of level in -former times seriously affected its relations to the surrounding country. -Professor Dana, however, has called attention to the fact that even now -it is in a region of comparatively light precipitation, suggesting that -the snow-fall over it may always have been insignificant in amount. But -this could scarcely account for the failure of the great ice-wave of the -north to overrun it. We are indebted again to the sagacity of President -Chamberlin in suggesting the true explanation. - -By referring to the map it will be noticed that this area sustains a -peculiar relation to the troughs of Lake Michigan and Lake Superior, -while from the arrangements of the moraines in front of these lakes it -will be seen that these lake basins were prominent factors in determining -the direction of the movement of the surplus ice from the north. It is -the more natural that they should do so because of their great depth, -their bottoms being in both cases several hundred feet below the present -water-level, reaching even below the level of the sea. - -These broad, deep channels seem to have furnished the readiest outlet for -the surplus ice of the North, and so to have carried both currents of ice -beyond this driftless area before they became again confluent. The slight -elevation south of Lake Superior served to protect the area on account of -the feebleness of direct movement made possible by the strength of these -diverging lateral ice-currents. The phenomenon is almost exactly what -occurs where a slight obstruction in a river causes an eddy and preserves -a low portion of land below it from submergence. A glance at the map -will make it easily credible that an ice-movement south of Manitoba, -becoming confluent with one from Lake Superior, pushed far down into the -Missouri Valley and spread eastward to the Mississippi River, south of -the unglaciated driftless area, and there became confluent with a similar -movement which had been directed by the valleys of Lake Michigan and Lake -Erie. There can be little doubt that President Chamberlin's explanation -is in the main correct, and we have in this another illustration of the -analogy between the behaviour of moving ice and that of moving water. - -[Illustration: Fig. 34.--Section of the east-and-west glacial furrows, -on Kelly's Island, preserved by Mr. Younglove. Fine sediment rests -immediately on the rock, with washed pebbles at the surface.] - -The accompanying illustrations will give a better idea than words can -do of the celebrated glacial grooves on the hard limestone islands -near Sandusky, in the western part of Lake Erie. Through the interest -aroused in them by an excursion of the American Association for the -Advancement of Science, while meeting in Cleveland, Ohio, in 1888, the -Kelly Island Lime and Transport Company, of which Mr. M. C. Younglove is -the president, has been induced to deed to the Western Reserve Historical -Society for preservation a portion of one of the most remarkable of the -grooves still remaining. - -The portion of the groove preserved is thirty-three feet across, and -the depth of the cut in the rock is seventeen feet below the line, -extending from rim to rim. Originally there was probably here a small -depression formed by preglacial water erosion, into which the ice crowded -the material, which became its graving-tool, and so the rasping and -polishing went on in increasing degree until this enormous furrow is -the result. The groove, however, is by no means simple, but presents a -series of corrugations merging into each other by beautiful curves. When -exposed for a considerable length it will resemble nothing else so much -as a collection of prostrate Corinthian columns lying side by side on a -concave surface. - -The direction of these grooves is a little south of west, corresponding -to that of the axis of the lake. This is nearly at right angles to the -course of the ice-scratches on the summit of the water-shed south of -this, between the lake and the Ohio River. The reason for this change -of direction can readily be seen by a little attention to the physical -geography. The highlands to the south of the lake rise about seven -hundred feet above it. When the Ice period was at its climax and overran -these highlands, the ice took its natural course at right angles to -the terminal moraine and flowed southeast according to the direction -indicated by the scratches on the summit; but when the supply of ice was -not sufficient to overrun the highlands, the obstruction in front turned -the course and the resultant was a motion towards Toledo and the Maumee -Valley, where in the vicinity of Fort Wayne an extensive terminal moraine -was formed. - -[Illustration: Fig. 35.--Same as the preceding. (Courtesy of M. C. -Younglove.)] - -The much-mooted question of a succession of glacial epochs finds the -most of its supporting facts in the portion of the glaciated area lying -west of Pennsylvania. That there have been frequent oscillations of the -glacial front over this area is certain. But it is a question whether -the glacial deposits south of this distinct line of moraine hills are so -different from those to the north of it as to necessitate the supposition -of two entirely distinct glacial epochs. This can be considered most -profitably here. - -The following are among the points with reference to which the phenomena -south of the moraine just delineated differ from those north of the line: - -1. The glacial deposits to the south appear to be distributed more -uniformly than those to the north. To the north the drift is often -accumulated in hills, and is dotted over with kettle-holes, while to the -south these are pretty generally absent. Any one travelling upon a line -of railroad which traverses these two portions of the glaciated area as -indicated upon our map can easily verify these statements. - -2. The amount of glacial erosion seems to be much less south of the line -of moraine hills delineated than north of them. Still, glacial striæ -are found, almost everywhere, close down to the extreme margin of the -glaciated area. - -3. The gravel deposits connected with the drainage of the Glacial period -are much less abundant south of the so-called "terminal moraine of the -second Glacial period" than they are north of it. South of this moraine -the water deposits attributed to the Glacial period are of such fine -silt as to indicate slow-moving currents over a gentle low slope of the -surface. - -4. The glacial deposits to the south are more deeply coloured than those -to the north, showing that they have been longer exposed to oxidising -agencies. Even the granitic boulders show the marks of greater age south -of this line, being disintegrated to a greater extent than those to the -north. - -5. And, finally, there occur, over a wide belt bordering the so-called -moraine hills of the second Glacial epoch, extensive intercalated beds -of vegetal deposits. Among the earliest of these to be discovered were -those of Montgomery County, Ohio, where, in 1870, Professor Orton, of the -Ohio Survey, found at Germantown a deposit of peat fourteen feet thick -underneath ninety-five feet of till, and there seem also to be glacial -deposits underneath the peat as well as over it. The upper portion of the -peat contains "much undecomposed sphagnous mosses, grasses, and sedges, -and both the peat and the clayey till above it" contain many fragments -of coniferous wood which can be identified as red cedar (_Juniperus -Virginianus_). In numerous other places in that portion of Ohio -fresh-appearing logs, branches, and twigs of wood are found underneath -the till, or mingled with it, much as boulders are. Near Darrtown, in -Butler County, Ohio, red cedar logs were found under a covering of -sixty-five feet of till, and so fresh that the perfume of the wood is -apparently as strong as ever. Similar facts occur in several other -counties in the glaciated area of southern Ohio and southern Indiana. -Professor Collett reports that all over southwestern Indiana peat, muck, -rotted stumps, branches, and leaves of trees are found from sixty to one -hundred and twenty feet below the surface, and that these accumulations -sometimes occur to a thickness of from two to twenty feet. - -[Illustration: Fig. 36.--Section of till near Germantown, Ohio, overlying -thick bed of peat. The man in the picture stands upon a shelf of peat -from which the till has been eroded by the stream. The dark spot at -the right hand of the picture, just above the water, is an exposure of -the peat. The thickness of the till is ninety-five feet. The partial -stratification spoken of in the text can be seen about the middle of the -picture. The furrows up and down had been made by recent rains. (United -States Geological Survey.) (Wright.)] - -Farther to the northwest similar phenomena occur. Professor N. H. -Winchell has described them most particularly in Fillmore and Mower -Counties, Minnesota, from which they extend through a considerable -portion of Iowa. In the above counties of Minnesota a stratum of peat -from eighteen inches to six or eight feet in thickness, with much wood, -is pretty uniformly encountered in digging wells, the depth varying from -twenty to fifty feet. This county is near the highest divide in the State -of Minnesota, and from it "flow the sources of the streams to the north, -south, and east." The wood encountered in this stratum indicates the -prevalence f coniferous trees, and the peat mosses indicate a cool and -moist climate. - -Nor are intercalated vegetable deposits absent from the vast region -farther north over the area that drains into Hudson Bay. At Barnesville, -in Clay County, Minnesota, which lies in the valley of the Red River of -the North, and also in Wilkin County in the same valley, tamarack wood -and sandy black mud containing many snail-shells have been found from -eight to twelve feet below a surface of till; and Dr. Robert Bell reports -the occurrence of limited deposits of lignite between layers of till, far -to the northwest, in Canada, and even upon the southern part of Hudson -Bay; while Mr. J. B. Tyrrell reports[BF] many indications of successive -periods of glaciation near the northern end of the Duck Mountain. The -most characteristic indications which he had witnessed consisted of -stratified beds of silt, containing fresh-water shells, with fragments of -plants and fish similar to those living in the lakes of the region at the -present time. - -[Footnote BF: Bulletin of the Geological Society of America, vol. i, pp. -395-410.] - -Reviewing these facts with reference to their bearing upon the point -under consideration, we grant, at the outset, that they do indicate a -successive retreat and readvance of the ice over extensive areas. This -is specially clear with respect to the vegetal deposits interstratified -with beds of glacial origin. But the question at issue concerning the -interpretation of these phenomena is, Do they necessarily indicate -absolutely distinct glacial epochs separated by a period in which the -ice had wholly disappeared from the glaciated area to the north? That -they do, is maintained by President Chamberlin and many others who have -wide acquaintance with the facts. That they do not certainly indicate a -complete disappearance of the ice during an extensive interglacial epoch, -is capable, however, of being maintained, without forfeiting one's rights -to the respect of his fellow-geologists. The opposite theory is thus -stated by Dr. Robert Bell: "It appears as if all the phenomena might be -referred to one general Glacial period, which was long continued, and -consequently accompanied by varying conditions of temperature, regional -oscillations of the surface, and changes in the distributions of sea and -land, and in the currents in the ocean. These changes would necessarily -give rise to local variations in the climate, and might permit of -vegetation for a time in regions which need not have been far removed -from extensive glaciers."[BG] - -[Footnote BG: Bulletin of the Geological Society of America, vol. i, pp. -287-310.] - -At my request, Professor J. E. Todd, of Iowa, whose acquaintance with the -region is extensive, has kindly written out for me his conclusions upon -this subject, which I am permitted to give in his own words: - -"I am not prepared to write as I would like concerning the forest-beds -and old soils. I will, however, offer the following as a partial report. -I have come to think that there is considerable confusion on the subject. -I believe there are five or six different things classed under one head. - -"1. _Recent Much and Soils._--The finest example I have found in the -whole Missouri Valley was twenty feet below silt and clay, in a basin -inside the outer moraine, near Grand View, South Dakota. From my -examination of the reported old soil near Albia, Iowa, I think the most -rational way of reconciling the conflicting statements concerning it is -that it also belongs to this class. - -"2. _Peat or Soil under Loess._--This does not signify much if the loess -was formed in a lake subject to orographic oscillations, or if, as I am -coming to believe, it is a fluviatile deposit of an oscillating river -like the Hoang-Ho on the great Chinese plain. It at least does not mean -an interglacial epoch. - -"3. _Wood and Dirt rearranged, not in situ._--This occurs either in -subaqueous or in subglacial deposits. I have found drift-wood in the -lower layers of the loess here, but not _in situ_. I have frequently -found traces of wood in till in Dakota, but always in an isolated -way. I think, from reading statements about the deposits in eastern -Iowa, that most if not all of the cases are of this sort. Two things -have conspired to lead to this error: one, the influence of Croll's -speculation; and the other, the easy inference of many well-diggers, -and especially well-borers, that what they pass through are always in -layers. In this way a log becomes a forest-bed. Scattered logs and muck -fragments occurring frequently in a region, though at different levels, -are readily imagined by an amateur geologist to be one continuous stratum -antedating the glacier or floods (as the case may be in that particular -region), when, in fact, it has been washed down from the margin of -the transporting agent and is contemporaneous with it. I suspect the -prevalence of wood in eastern Iowa may be traced to a depression of the -driftless region during the advance of the glacier, so as to bring the -western side of that area more into the grasp of glacial agencies. - -"4. _Peat between Subglacial Tills._--If cases of this sort are found, -they are in Illinois, Indiana, and Ohio. Professor Worthen insisted that -there were no interglacial soils or forest-beds in Illinois; and in the -cases mentioned in the State reports he repeatedly explains the sections -given by his assistants, so as to harmonize them with that statement. I -think he usually makes his explanations plausible. He was very confident -in referring most of them, to preglacial times. His views, I suppose, -will be published in the long-delayed volume, now about to be issued. - -"5. _Vegetable Matter between Glacial Till and Underlying Berg Till or -other Drift Deposits._--When one remembers that the front of the great -ice-sheet may have been as long in reaching its southern boundary as in -receding from it, and with as many advance and retrograde movements, we -can easily believe that much drift material would have outrun the ice and -have formed deposits so far ahead of it that vegetation would have grown -before the ice arrived to bury it. - -"6. _Preglacial Soils, etc._--I believe that this will be found to -include most in southern Ohio, if not in Illinois, as Worthen claimed." - -The phenomena of the Glacial period are too vast either to have appeared -or to have disappeared suddenly. By whatever cause the great accumulation -of ice was produced, the advance to the southward must have been slow -and its disappearance must have been gradual, though, as we shall show -a little later, the final retreat of the ice-front occupied but a short -time relatively to the whole period which has elapsed since. As we -shall show also, the advent of the Ice period was probably preceded and -accompanied by a considerable elevation of the northern part of the -continent Whether this elevation was contemporaneous upon both sides of -the continent is perhaps an open question; but with reference to the area -east of the Rocky Mountains, which is now under consideration, the centre -of elevation was somewhere south of Hudson Bay. Putting together what -we know, from the nature of the case, concerning the accumulation and -movement of glacial ice, and what we know from the relics of the great -glacial invasion, which have enabled us to determine its extent and the -vigour of its action, the course of events seems to have been about as -follows: - -Throughout the Tertiary period a warm climate had prevailed over British -America, Greenland, and indeed over all the lands in proximity to the -north pole, so far as explorers have been able to penetrate them. The -vegetation characterizing these regions during the Tertiary period -indicates a temperature about like that which now prevails in North -Carolina and Virginia. Whatever may be said in support of the theory -that the Glacial period was produced by astronomical causes, in view of -present facts those causes cannot be regarded as predominant; at most -they were only co-operative. The predominant cause of the Glacial period -was probably a late Tertiary or post-Tertiary elevation of the northern -part of the continents, accompanied with a subsidence in the central -portion. Of such a subsidence in the Isthmus of Panama indications are -thought to be afforded by the occurrence of late Tertiary or, more -probably, post-Tertiary sea-shells at a considerable elevation on the -divide along the Isthmus of Panama, between the Atlantic and Pacific -Oceans. Of this we shall speak more fully in a later chapter. - -Fixing our thoughts upon what is known as the Laurentian plateau, which, -though now in the neighbourhood of but two thousand feet above the sea, -was then much higher, we can easily depict in imagination the beginnings -of the great "Laurentide Glacier," which eventually extended to the -margin already delineated on the south and southwest in the United -States, and spread northward and eastward over an undetermined area. -Year after year and century after century the accumulating snows over -this elevated region consolidated into glacial ice and slowly pushed -outward the surplus reservoirs of cold. For a long time this process of -ice-accumulation may have been accompanied by the continued elevation of -the land, which, together with the natural effect of the enlarging area -of ice and snow, would tend to lower the temperature around the margin -and to increase still more the central area of accumulation. - -The vigour of movement in any direction was determined partly by the -shape of the valleys opening southward in which the ice-streams would -naturally concentrate, and partly by those meteorological conditions -which determine the extent of snow-fall over the local centres of glacial -dispersion. For example, the general map of North America in the Ice -period indicates that there were two marked subcentres of dispersion -for the great Laurentide Glacier, the eastern one being in Labrador and -the western one north of Lake Superior. In a general way the southern -boundary of the glaciated region in the United States presents the -appearance of portions of two circumferences of circles intersecting each -other near the eastern end of Lake Erie. These circles, I am inclined -to believe, represent the areas over which a semi-fluid (or a substance -like ice, which flows like a semi-fluid) would disperse itself from the -subcentres above mentioned. - -A study of the contour of the country shows that that also, in a general -way, probably had something to do with the lines of dispersion. The -western lobe of this glaciated area corresponds in its boundary pretty -closely with the Mississippi Valley, having the Ohio River approximately -as its eastern arm and the Missouri as its western, with the Mississippi -River nearly in its north and south axis. The eastern lobe has its -farthest extension in the axis of the Champlain and Hudson River Valleys, -its western boundary being thrown more and more northward as the line -proceeds to the west over the Alleghany Mountains until reaching the -longitude of the eastern end of Lake Erie; but this southern boundary is -by no means a water-level, nor is the contour of the country such that -it could ever have been a water-level. But it conforms in nearly every -particular to what would be the resultant arising from a pretty general -southward flow of a semi-fluid from the two subcentres mentioned, meeting -with the obstructions of the Adirondacks in northern New York and of the -broader Appalachian uplift in northern Pennsylvania. - -How far south the area of glacial accumulation may have extended cannot -be definitely ascertained, but doubtless at an early period of the great -Ice age the northern portions of the Appalachian range in New York, New -England, New Brunswick, and Nova Scotia became themselves centres of -dispersion, while only at the height of the period did all their glaciers -become confluent, so that there was one continuous ice-sheet. - -In the western portion of the area covered by the Laurentide Glacier, the -depression occupied by the Great Lakes, especially Lakes Michigan and -Superior, evidently had a marked influence in directing the flow of ice -during the stages which were midway between the culmination of the Ice -period and both its beginning and its end. This would follow from the -great depth of these lakes, the bottom of Lake Michigan being 286 feet -below sea-level, and that of Lake Superior 375 feet, making a total depth -of water of about 900 and 1,000 feet respectively. Into these oblong -depressions the ice would naturally gravitate until they were filled, -and they would become the natural channels of subsequent movement in the -direction of their longest diameters, while the great thickness of ice in -them would make them the conservative centres of glacial accumulation and -action after the ice had begun to retreat. - -These deductions from the known nature of ice and the known topography of -the region are amply sustained by a study of the detailed map showing the -glacial geology in the United States. But on this we can represent indeed -only the marks left by the ice at various stages of its retreat, since, -as already remarked, the marks of each stage of earlier advance would be -obliterated by later forward movements. We may presume, however, that -in general the marks left by the retreating ice correspond closely with -those actually made and obliterated by the advancing movement. - -From observations upon the glaciers of Switzerland and of Alaska, it -is found that neither the advance nor the retreat of these glaciers is -constant, but that, in obedience to meteorologic agencies not fully -understood, they advance and retreat in alternate periods, at one time -receding for a considerable distance, and at other times regaining the -lost ground and advancing over the area which has been uncovered by their -retreat. - -"M. Forel reports, from the data which he has collected with much care, -that there have been in this century five periods in the Alpine glaciers: -of enlargement, from 1800 (?) to 1815; of diminution, from 1815 to 1830; -of enlargement, from 1830 to 1845; of diminution, from 1845 to 1875; and -of enlargement again, from 1875 onward. He remarks further that these -periods correspond with those deduced by Mr. C. Lang for the variations -for the precipitations and temperature of the air; and, consequently, -that the enlargement of the glaciers has gone forward in the cold and -rainy period, and the diminution in the warm and the dry."[BH] - -[Footnote BH: American Journal of Science, vol. cxxxii, 1886, p. 77.] - -When, now, we attentively consider the combination of causes necessary to -produce the climatic conditions of the great Ice age of North America, we -shall be prepared to find far more extensive variations in the progress -of the continental glacier, both during its advance and during its -retreat, than are to be observed in any existing local glaciers. - -With respect to the arguments adduced in favor of a succession of glacial -epochs in America the following criticisms are pertinent: - -1. So far as we can estimate, a temporary retreat of the front, lasting -a few centuries, would be sufficient to account for the vegetable -accumulations that are found buried beneath the glacial deposits in -southern Ohio, Indiana, central Illinois, and Iowa, while a temporary -readvance of the ice would be sufficient to bury the vegetable remains -beneath a freshly accumulated mass of till. Thus, as Dr. Bell suggested, -the interglacial vegetal deposits do not necessarily indicate anything -more than a temporary oscillation of the ice-front, and do not carry -with them the necessity of supposing a disappearance of the ice from the -whole glaciated area. Thus the introduction of a whole Glacial period to -account for such limited phenomena is a violation of the well-known law -of parsimony, which requires us in our explanations of phenomena to be -content with the least cause which is sufficient to produce them. In the -present instance a series of comparatively slight oscillations of the -ice-front during a single glacial period would seem to be sufficient to -account for all the buried forests and masses of vegetal _débris_ that -occur either in the United States or in the Dominion of Canada. - -2. Another argument for the existence of two absolutely distinct glacial -periods in North America has been drawn from the greater oxidation of -the clays and the more extensive disintegration of certain classes of -the boulders found over the southern part of the glaciated area of the -Mississippi Valley, than has taken place in the more northerly regions. -Without questioning this statement of fact (which, however, I believe to -be somewhat exaggerated), it is not difficult to see that the effects -probably are just what would result from a single long glacial period -brought about by such causes as we have seen to be probably in operation -in America. For if one reflects upon the conditions existing when the -Glacial period began, he will see that, during the long ages of warm -climate which characterised the preceding period, the rocks must have -been extensively disintegrated through the action of subaërial agencies. -The extent to which this disintegration takes place can be appreciated -now only by those who reside outside of the glaciated area, where these -agencies have been in uninterrupted action. In the Appalachian range -south of the glaciated region the granitic masses and strata of gneiss -are sometimes found to be completely disintegrated to a depth of fifty or -sixty feet; and what seem to be beds of gravel often prove in fact to be -horizontal strata of gneiss from which the cementing material has been -removed by the slow action of acids brought down by the percolating water. - -Now, there can be no question that this process of disintegration had -proceeded to a vast extent before the Glacial period, so that, when the -ice began to advance, there was an enormous amount of partially oxidised -and disintegrated material ready to be scraped off with the first advance -of ice, and this is the material which would naturally be transported -farthest to the south; and thus, on the theory of a single glacial -period, we can readily account for the greater apparent age of the -glacial _débris_ near the margin. This _débris_ was old when the Glacial -period began. - -3. With reference to the argument for two distinct glacial periods drawn -from the smaller apparent amount of glacial erosion over the southern -part of the glaciated area, we have to remark that that would occur -in case of a single ice-invasion as well as in case of two distinct -ice-invasions, in which the later did not extend so far as the former. - -From the very necessity of the case, glacial erosion diminishes as the -limit of the extent of the glaciation is approached. At the very margin -of the glacier, motion has ceased altogether. Back one mile from the -margin only one mile of ice-motion has been active in erosion, while ten -miles back from its front there has been ten times as much moving ice -actually engaged in erosion, and in the extreme north several hundred -times as much ice, Thus it is evident that we do not need to resort to -two glacial periods to account for the relatively small amount of erosion -exhibited over the southern portion of our glaciated area. - -At the same time, it should be said that the indications of active -glacial erosion near the margin are by no means few or small. In Lawrence -County, Pennsylvania, on the very margin of the glaciated area, Mr. Max -Foshay[BI] has discovered very extensive glacial grooves, indicating much -vigour of ice-action even beyond the more extensive glacial deposits -which Professor Lewis and myself had fixed upon as the terminal moraine. -In Highland and Butler Counties, Ohio, and in southwestern Indiana and -southern Illinois, near the glacial margin, glacial grooves and striæ -are as clear and distinct in many cases as can anywhere be found; while -upon the surface of the limestone rocks within the limits of the city of -St. Louis, where the glacial covering is thin, and where disintegrating -agencies had had special opportunities to work, I found very clear -evidences of a powerful ice-movement, which had planed and scratched -the rock surface; and at Du Quoin, Illinois, as already related, the -fragments thrown up from the surface of the rock, fifty or sixty feet -below the top of the soil, were most beautifully planed and striated. -It should be observed, also, that this whole area is so deeply covered -with _débris_ that the extent of glacial erosion underneath is pretty -generally hid from view. - -[Footnote BI: Bulletin of the Geological Society, vol. ii, pp. 457-464.] - -4. The uniformity of the distribution of the glacial deposits over the -southern portion of the glaciated area in the Mississippi Valley is -partly an illusion, due to the fact that there was a vast amount of -deposition by water over that area during the earlier stages of the -ice-retreat. This has been due partly to the gentler slope which would -naturally characterise the borders of an area of elevation, and partly to -an extensive subsidence which seems to have begun soon after the ice had -reached its farthest extent of motion. - -It should be borne in mind that at all times a glacier is accompanied -by the issue of vast streams of water from its front, and that these -of course increase in volume when the climax has been reached and the -ameliorating influences begin to melt away the accumulated mass of ice -and to add the volume of its water to that produced by ordinary agencies. -As these subglacial streams of water poured out upon the more gentle -slopes of the area in front of the ice, they would distribute a vast -amount of fine material, which would settle into the hollow places and -tend to obscure the irregularities of the previous direct glacial deposit. - -Such an instance came clearly under my own observation in the vicinity of -Yankton, in South Dakota, where, upon visiting a locality some miles from -any river, and to which workmen were resorting for sand, I found that the -deposit occupied a kettle-hole, filling it to its brim, and had evidently -been superimposed by a temporary stream of water flowing over the region -while the ice was still in partial occupation of it. Thus, no doubt, in -many cases, the original irregularities of the direct glacial deposits -have been obliterated, even where there has been no general subsidence. - -But, in the area under consideration, the loess, or loam, is so extensive -that it is perhaps necessary to suppose that the central portions of the -Mississippi Valley were subjected to a subsidence amounting to about five -hundred feet; so that the glacial streams from the retreating ice-front -met the waters of the ocean in southern Illinois and Indiana; thus -accounting for the extensive fine silt which has done so much over that -region to obscure the glacial phenomena. - - -_West of the Rocky Mountains._ - -The glacial phenomena in the United States west of the Rocky Mountains -must be treated separately, since American geologists have ceased to -speak of an all-pervading ice-cap extending from the north pole. But, -as already said, the glaciation of North America has proceeded from -two definite centres of ice-accumulation, one of which we have been -considering in the pages immediately preceding. The great centre of -glacial dispersion east of the Rocky Mountains is the region south of -Hudson Bay, and the vast ice-field spreading out from that centre is -appropriately named the Laurentide Glacier. The movement of ice in this -glacial system was outward in all directions from the Laurentian hills, -and extended west several hundred miles, well on towards the eastern foot -of the Rocky Mountains. - -The second great centre of glacial dispersion occupies the vast -Cordilleran region of British Columbia, reaching from the Rocky Mountains -on the northeast to the Coast Range of the Pacific on the southwest, a -width of four hundred miles. The length is estimated by Dr. Dawson to -be twelve hundred miles. The principal centre of ice-accumulation lies -between the fifty-fifth and the fifty-ninth parallel. From this centre -the movement was in all directions, but chiefly to the northwest and to -the south. The movement of the Cordilleran glaciers extended northwest -to a distance of three hundred and fifty miles, leaving their moraines -far down in the Yukon Valley on the Lewes and Pelly Rivers.[BJ] Southward -the Cordilleran Glacier moved to a distance of six hundred miles, -extending to the Columbia River, in the eastern part of the State of -Washington. - -[Footnote BJ: See George M. Dawson, in Science, vol. xi, 1888, p. 186, -and American Geologist, September, 1890, pp. 153-162.] - -From this centre, also, the ice descended to the sea-level upon the -west, and filled all the channels between Vancouver's Island and the -mainland, as well as those in the Alexander Archipelago of Alaska. South -of Vancouver's Island a glacier pushed out through the straits of Juan de -Fuca to an unknown distance. All the islands in Puget Sound are composed -of glacial _débris_, resembling in every respect the terminal moraines -which have been described as constituting many of the islands south of -the New England coast. The ice-movement in Puget Sound, however, was -probably northward, resulting from glaciers which are now represented by -their diminutive descendants on the flanks of Mount Rainier. - -South of the Columbia River the country was never completely enveloped -by the ice, but glaciers extended far down in the valleys from all the -lofty mountain-peaks. In Idaho there are glacial signs from the summit -of the Rocky Mountains down to the westward of Lake Pend d'Oreille. In -the Yellowstone Park there are clear indications that the whole area was -enveloped in glacial ice. An immense boulder of granite, resting upon -volcanic deposits, may be found a little west of Inspiration Point, on -the Yellowstone Cañon. Abundant evidences of glacial action are also -visible down the Yellowstone River to the vicinity of Livingston, showing -that that valley must have been filled with glacial ice to a depth of -sixteen hundred feet. To the west the glaciers from the Yellowstone -Park extended to the border of Idaho, where a clearly marked terminal -moraine is to be found in the Tyghee Pass, leading over from the western -fork of the Madison River into Lewis Fork of the Snake River. South of -Yellowstone Park the Teton Mountains were an important centre for the -dispersion of local glaciers, but they did not descend upon the western -side much below the 6,000-foot level, and only barely came to the edge -of the great Snake River lava plains. To the east the movement from the -Teton Mountains joined that from various other lofty mountains, where -altogether they have left a most intricate system of glacial deposits, in -whose reticulations Jackson's Lake is held in place. - -[Illustration: Fig. 37.--Moraines of Grape Creek, Sangre del Cristo -Mountains, Colorado (after Stevenson).] - -In Utah extensive glaciers filled all the northern valleys of the Uintah -Mountains, and extended westward in the Wahsatch range to the vicinity of -Salt Lake City. The mountain region of Colorado, also, had its glaciers, -occupying the head-waters of the Arkansas, the Platte, the Gunnison, and -the Grand Rivers. The most southern point in the Rocky Mountains at which -signs of local glaciers have been noted is near the summits of the San -Juan range, in southwestern Colorado. Here a surface of about twenty-five -square miles, extending from an elevation of 12,000 feet down to 8,000 -feet, shows every sign of the former presence of moving ice. The greater -part of the glaciation in Colorado is confined to elevations above 10,000 -feet. - -The whole range of the Sierra Nevada through Oregon, and as far south as -the Yosemite Valley in California, formerly sustained glaciers of far -greater size than any which are now found in those mountains. In general -these glaciers were much longer on the western side of the Sierra Nevada -than on the eastern. On the eastern side glaciers barely came down to -Lake Tahoe and Lake Mono in California. The State of Nevada seems to -have been entirely free from glaciers, although it contains numerous -mountain-peaks more than ten thousand feet high. In the Yosemite Cañon -glaciers extended down the Merced River to the mouth of the cañon; while -in the Tuolumne River, a few miles to the north, the glaciers which still -linger about the peaks of Mount Dana filled the valley for a distance of -forty miles. - -It is a question among geologists whether or not the glaciation west -of the Rocky Mountains was contemporaneous with that of the eastern -part of the continent. The more prevalent opinion among those who have -made special study of the phenomena is that the development of the -Cordilleran glaciers was independent of that of the Laurentide system. -At any rate, the intense glaciation of the Pacific coast seems to have -been considerably later than that of the Atlantic region. Of this we will -speak more particularly in discussing the questions of the date and the -cause of the Glacial period. It is sufficient for us here simply to say -that, from his extensive field observations throughout the Cordilleran -region, Dr. George M. Dawson infers that there have been several -successive alternations of level on the Pacific coast corresponding to -successive glacial and interglacial epochs, and that when there was a -period of elevation west of the Rocky Mountains there was a period of -subsidence to the east, and _vice versa_. In short, he supposes that the -east and west for a long time played a game of seesaw, with the Rocky -Mountains as the fulcrum. We give his scheme in tabulated form. - -_Scheme of Correlation of the Phenomena of the Glacial Period in the -Cordilleran Region and in the Region of the Great Plains._ - - - CORDILLERAN REGION. REGION OF THE GREAT PLAINS. - - Cordilleran zone at a high Correlative subsidence and - elevation. Period of most severe submergence of the great plains, - glaciation and maximum development with possible contemporaneous - of the great Cordilleran Glacier. increased elevation of the - Laurentian axis and maximum - development of ice upon it. - Deposition of the lower - boulder-clay of the plains. - - Gradual subsidence of the Correlative elevation of the - Cordilleran region and decay of the western part, at least, of the - great glacier, with deposition of great plains, which was probably - the boulder-clay of the interior more or less irregular and led to - plateau and the Yukon basin, of the the production of extensive lakes - lower boulder-clay of the littoral in which interglacial deposits, - and probably also, at a later stage including peat, were formed. - (and with greater submergence), of - the interglacial silts of the same - region. - - Re-elevation of the Cordilleran Correlative subsidence of the - region to a level probably as high plains, which (at least in the - as or somewhat higher than the western part of the region) - present. Maximum of second period exceeded the first subsidence and - of glaciation. extended submergence to the base - of the Rocky Mountains near the - forty-ninth parallel. Formation of - second boulder-clay, and (at a - later stage) dispersion of large - erratics. - - Partial subsidence of the Correlative elevation of the - Cordilleran region, to a level plains, or at least of their - about 2,500 feet lower than the western portion, resulting in a - present. Long stage of stability. condition of equilibrium as - Glaciers of the second period between the plains and the - considerably reduced. Upper Cordillera, their _relative_ - boulder-clay of the coast probably levels becoming nearly as at - formed at this time, though perhaps present. Probable formation of the - in part during the second maximum Missouri coteau along a shore-line - of glaciation. during this period of rest. - - Renewed elevation of the Simultaneous elevation of the great - Cordilleran region, with one plains to about their present - well-marked pause, during which the level, with final exclusion of - littoral stood about 200 feet lower waters in connection with the sea. - than at present. Glaciers much Lake Agassiz formed and eventually - reduced, and diminishing in drained towards the close of this - consequence of general amelioration period. This simultaneous movement - of climate towards the close of the in elevation of both great areas - Glacial period. may probably have been connected - with a more general northern - elevation of land at the close of - the Glacial period. - -In New Zealand the marks of the Glacial period are unequivocal The -glaciers which now come down from the lofty mountains upon the South -Island of New Zealand to within a few hundred feet of the sea then -descended to the sea-level. The longest existing glacier in New Zealand -is sixteen miles, but formerly one of them had a length of seventy-eight -miles. One of the ancient moraines contains a boulder from thirty to -forty feet in diameter, and the amount of glacial _débris_ covering the -mountain-sides is said to be enormous. Reports have also been recently -brought of signs of ancient glaciers in Australia. - -[Illustration: Fig. 38.--Generalised view of the whole glaciated region -of North America. The area of motionless ground-ice is shown by the white -lines in northern part of Alaska.] - -According to Darwin, there are distinct signs of glaciation upon the -plains of Patagonia sixty or seventy miles east of the foot of the -mountains, and in the Straits of Magellan he found great masses of -unstratified glacial material containing boulders which were at least -one hundred and thirty miles away from their parent rock; while upon -the island of Chiloe he found embedded in "hardened mud" boulders which -must have come from the mountain-chains of the continent. Agassiz also -observed unquestionable glacial phenomena on various parts of the Fuegian -coast, and indeed everywhere on the continent south of latitude 37°. -Between Concepcion and Arauco, in latitude 37°, Agassiz observed, near -the sea-level, a glacial surface well marked with furrows and scratches, -and as well preserved, he says, "as any he had seen under the glaciers of -the present day." - -[Illustration: Fig. 39.--Quartzite boulder of 45 cubic metres, on Mont -Lachat, 800 metres above the valley of the Belley, in Ain, France -(Falsan).] - - - - -CHAPTER VI. - -ANCIENT GLACIERS IN THE EASTERN HEMISPHERE. - - -About two million square miles of northern Europe were covered with -perennial ice during the Glacial period. From the scratches upon the -rocks, and from the direction in which material has been transported, -it is evident that the main centre of radiation is to be found in the -mountains of Scandinavia, and that the glaciers still existing in Norway -are the lineal descendants of those of the great Ice age. - -So shallow are the Baltic Sea and the German Ocean, that their basins -were easily filled with ice, upon which Scandinavian boulders could be -transported westward to the east shore of England, southward into the -plains of Germany, and eastward far out upon the steppes of Russia. The -islands north of Scotland bear marks also of an ice-movement from the -direction of Norway. If Scotland itself was not overrun with Scandinavian -glaciers, the reason was that it had ice enough of its own, and from -its highlands set up a counter-movement, which successfully resisted -the invasion from the Scandinavian Peninsula. But, elsewhere in Europe, -Scandinavian ice moved freely outward to the extent of its capacity. -Then, as now also, the Alps furnished centres for ice-movement, but the -glaciers were limited to the upper portions of the valleys of the Rhône, -the Rhine, and the Danube upon the west and north, and to a still smaller -area upon the southern side. - -[Illustration: Fig. 40. - -MAP showing - -GLACIATED AREAS - -in North America and Europe.] - - -_Central and Southern Europe._ - -The main centres of ice-movement in the Alps during the Glacial period -are the same as those which furnish the lingering glaciers of the present -time. From the water-shed between the Rhine, the Rhône, and the Aar, -glaciers of immense size descended all the valleys now occupied by those -streams. The valley of the Rhône between the Bernese and the Pennine -Alps was filled with a glacier of immense depth, which was maintained -by fresh supplies from tributaries upon either side as far down as -Martigny. Glacial markings at the head of the Rhône Valley are found upon -the Schneestock,[BK] at an elevation above the sea of about 11,500 feet -(3,550 metres), or about 1,500 feet above the present surface of the -Rhône Glacier. At Fiesch, about twenty miles below, where tributaries -from the Bernese Oberland snow-fields were received, the thickness of -the glacier was upwards of 5,000 feet (1,680 metres). Near Martigny, -about fifty miles farther down the valley, where the glacier was abruptly -deflected to the north, the depth of the ice was still upwards of 1,600 -metres. From Martigny northward the thickness of the ice decreased -rapidly for a few miles, where, at the enlargement of the valley above -the head of Lake Geneva, it was less than 1,200 metres in thickness, and -spread out over the intervening plain as far as Chasseron, with a nearly -level surface, transporting, as we have before said, Alpine boulders -to the flanks of the Juras, and landing them about 3,000 feet (1,275 -metres) above the level of Lake Geneva. The width of the main valley is -here about fifty miles, making the slope of the surface of the ice about -twenty feet to the mile. - -[Footnote BK: A. Falsan's La Période Grlaciaire étudiée principalement en -France et en Suisse, chapitre xv.] - -From its "vomitory," at the head of Lake Geneva, the ice of the ancient -Rhône Glacier spread to the right and to the left, while its northern -boundary was abruptly terminated by the line of the Jura Mountains. The -law of glacial motion was, however, admirably illustrated in the height -to which the ice rose upon the flanks of the Jura. At Chasseron, in the -direct line of its onward motion, it rose to its highest point, while -both to the southwest and to the northeast, along the line of the Juras, -the ice-action was limited to constantly decreasing levels. - -Down the valley of the Rhône the direction of motion was determined by -the depression of Lake Geneva, at the lower end of which it received its -main tributary from Mont Blanc, which had come down from Chamouni through -the valley of the river Arve. From this point it was deflected by a spur -of the Jura Mountains more and more southward to the vicinity of Culoz, -near the mouth of Lake Bourget. Here the glacier coming down from the -western flanks of the Alps, through the upper valley of the Isère, past -Chambéry, became predominant, and deflected the motion to the west and -north, whither the ice extended to a line passing through Bourg, Lyons, -and Vienne, leaving upon one of the eminences on which Lyons is built a -boulder several feet in diameter, which is duly preserved and labelled -in the public park in that portion of the city. Farther south, glaciers -of less extent marked the Alps most of the way to the Mediterranean, but -they were not at all comparable in size to those from the central region. - -To the right of Lake Geneva the movement started by the Rhône Glacier -spread eastward, being joined in the vicinity of Berne by the confluent -ice-stream which descended from the north flank of the Bernese Oberland, -through the valley of the Aar. These united streams filled the whole -valley with ice as far down as Soleure.[BL] - -[Footnote BL: See map of Rhône Glacier, on p. 58.] - -[Illustration: MAP OF - -GLACIAL MOVEMENTS - -IN FRANCE AND - -SWITZERLAND.] - -Farther eastward, other ice-streams from the Alps became predominant, -one of which, moving down the Reuss, deployed out upon the country lying -north of Lucerne and Zug. Still farther down, the ancient glacier which -descended the Limmatt spread itself out over the hills and lowlands about -Zürich, one of its moraines of retrocession nearly dividing the lake into -two portions. - -Guyot and others have shown that the superficial deposits of this -portion of Switzerland are just such as would be distributed by glaciers -coming down from the above-mentioned Alpine valleys. Uniting together -north of Zürich, these glaciers pushed onward as far as the Rhine below -Schaffhausen. In Frickthal the glacial ice was still 1,200 feet thick, -and at Kaisterberg between 400 and 500 feet. - -At Lucerne there is a remarkable exposure of pot-holes, and a glaciated -surface such as could be produced only by the combined action of moving -ice and running water; thus furnishing to tourists an instructive -object-lesson. Among the remarkable instances of boulders transported -a long distance in Switzerland, is that of a block of granite carried -from the Valais to the vicinity of Soleure, a distance of one hundred -and fifteen miles, which weighs about 4,100 tons. "The celebrated -Pierre-à-Bot, above Neufchâtel, measures 50' × 20' × 40', and contains -about 40,000 cubic feet of stone; while the Pierre-des-Marmettes, near -Monthey, contains no less than 60,840 cubic feet." - -The ancient glacier of the Rhine, receiving its initial impulse in -the same centre as that of the Rhône, fully equalled it in all its -dimensions. Descending eastward from its source near the Schneestock -to Chur, a distance of fifty miles, it turned northward and continued -forty-five miles farther to the head of Lake Constance, where it spread -out in fan-shape, extending northwest to Thiengen, below Schaffhausen, -and covering a considerable area north and northeastward of the lake, -reaching in the latter direction Ulm, upon the Danube--the whole distance -of the movement being more than one hundred and fifty miles. Through -other valleys tributary to the Danube, glaciers descended upon the upper -plains of Bavaria, from the Tyrolese Alps to the vicinity of Munich. -From Gross Glockner as a centre in the Noric Alps, vast rivers of ice, -of which the Pasterzen Glacier is the remnant, poured far down into the -valleys of the Inn and the Enns on the north and into that of the Drave -on the southeast. Farther eastward in this part of Europe the mountains -seem to have been too low to have furnished centres for any general -dispersion of glacial ice. - -[Illustration: Fig. 41.--Map showing the Lines of _Débris_ extending -from the Alps into the Plains of the Po (after Lyell). _A._ Crest of -the Alpine water-shed; _B._ Névé-fields of the ancient glaciers; _C._ -Moraines of ancient glaciers.] - -Upon the south side of the Alps the ancient glaciers spread far out -upon the plains of Lombardy, where moraines of vast extent and of every -description enable the student to determine the exact limits of the -ancient ice-action. From the southern flanks of Mont Blanc and Monte -Rosa, and from the snow-fields of the western Alps, glaciers of great -volume descended into the valley of Dora Baltea (vale of Aosta), and -on emerging from the mountain valley Spread Out over the plains around -Ivrea, leaving moraine hills in some instances 1,500 feet in height. -The total length of this glacier was as much as one hundred and twenty -miles. From the snow-fields in the vicinity of Mont Cenis, also, glaciers -extended down the Dora Ripera to the vicinity of Turin, and down other -valleys to a less extent. The lateral moraines of the Diore, on the south -side of Mont Blanc, at the head of the Dora Baltea, are 2,000 feet above -the present river, and extend upon the left bank for a distance of twenty -miles. - -From the eastern Alps, glaciers descended through all the valleys of the -Italian lakes and deposited vast terminal moraines, which still obstruct -the drainage, and produce the charming lakes of that region. A special -historic interest pertains to the series of concentric moraines south of -Lake Garda, since it was in the reticulations of this glacial deposit -that the last great battle for Italian liberty was fought on June 24, -1859. Defeated in the engagements farther up the valley of the Po, the -Austrian general Benedek took his final stand to resist the united forces -of France and Italy behind an outer semicircle of the moraine hills south -of this lake (some of which are 500 or 600 feet above the surrounding -country), with his centre at Solferino, about ten miles from Peschera. -Here, behind this natural fortification, he awaited the enemy, who was -compelled to perform his manoeuvres on the open plain which spread out -on every side. But the natural fortifications furnished by the moraine -hills were too extensive to be defended by an army of moderate size. -The troops of Napoleon and Victor Immanuel concentrated at Solferino -and broke through the line. Thus the day was lost to the Austrians, and -they retired from Lombardy, leaving to Italy both the artificial and the -natural fortifications that guard the southern end of this important -entrance to the Tyrolese Alps. When once his attention is called to the -subject, the traveller upon the railroad cannot fail to notice this -series of moraines, as he enters it through a tunnel at Lonato on the -west, and emerges from it at Soma Campagna, eighteen or twenty miles -distant to the east. A monument celebrating the victory stands upon a -moraine hill about half-way between, at Martino della Battaglie. - -In other portions of central and southern Europe the mountains were too -low to furnish important centres for glacial movements. Still, to a -limited extent, the signs of ancient glaciers are seen in the mountains -of the Black Forest, in the Harz and Erzgebirge, and in the Carpathians -on the east and among the Apennines on the south. In Spain, also, there -were limited ice-fields on the higher portions of the Sierra Nevada -and in the mountains of Estremadura, and perhaps in some other places. -In France, small glaciers were to be found in the higher portions -of the Auvergne, of the Morvan, of the Vosges, and of the Cevennes; -while, from the Pyrenees, glaciers extended northward throughout nearly -their whole extent. The ice-stream descending from the central mass of -Maladetta through the upper valley of the Garonne, was joined by several -tributaries, and attained a length of about forty-five miles. - - -_The British Isles._ - -During the climax of the Glacial period the Hebrides to the north of -Scotland were covered with ice to a depth of 1,600 feet. How far westward -of this it moved out to the sea, it is of course impossible to tell. But -in the channels between the Hebrides and Scotland it is evident that -the water was completely expelled by the ice, and that, from a height -of 1,600 feet above the Hebrides to the northern shores of Scotland, -there was a continuous ice-field sloping southward at the rate of about -twenty-five feet a mile. - -Scotland itself was completely enveloped in glacial ice. Prevented by -the Scandinavian Glacier from moving eastward, the Scotch movement was -compelled to be westward and southward. On the southwest the ice-stream -reached the shores of Ireland, and became confluent with the glaciers -that enveloped that island, completely filling the Irish Sea. - -There are so many controverted points respecting the glacial geology of -England, and they have such an important bearing upon the main question -of this volume, that a pretty full discussion of them will be necessary. -I have recently been over enough of the ground myself to become satisfied -of the general correctness of the views entertained by my late colleague, -the lamented Professor Henry Carvill Lewis, whose death in 1888 took -place before the publication of his most mature conclusions. But the -lines of investigation to which he gave so powerful an impulse have since -been followed out by an active body of scientific observers. To give the -statement of facts greater precision and authority, I have committed -the preparation of it to the Secretary of the Northwest of England -Boulder Committee, Percy F. Kendall, F. G. S., Lecturer on Geology at -the Yorkshire College, Leeds, and at the Stockport Technical School, -England.[BM] - -[Footnote BM: Mr. Kendall's contribution extends to page 181.] - -"All the characteristic evidences of the action of land-ice can be found -in the greatest perfection in many parts of England and Wales. Drumlins, -kames, _roches moutonnées_, far-travelled erratics, terminal moraines, -and perched blocks, all occur. There are, besides, in the wide-spread -deposits of boulder-clay which cover so many thousands of square miles on -the low grounds lying on either side of the Pennine chain, evidences of -the operation of ice-masses of a size far exceeding that of the grandest -of existing European glaciers. But, while the proofs of protracted -and severe glaciation are thus patent, there are, nevertheless, many -apparently anomalous circumstances which arrest the attention when the -whole country is surveyed. The glacial phenomena appear to be strictly -limited to the country lying to the northward of a line extending from -the Bristol Channel to the mouth of the Thames; and within the glaciated -area there are many extensive tracts of land devoid of 'drift' or other -indications of ice-action. - -"By comparison with the phenomena displayed in the North American -continent, English glacial geology must seem puny and insignificant; but, -just as with the features of the 'Solid Geology,' we have compressed -within the narrow limits of our isles an epitome of the features which -across the Atlantic require a continent for their exposition. It has -resulted from this concentration that English geology requires a much -closer and more minute investigation. And the difficulty which has been -experienced by glacial geologists of dealing with an involved series of -facts has, in the absence of any clue leading to the co-ordination of a -vast series of more or less disconnected observations, resulted in the -adoption, to meet certain local anomalies, of explanations which were -very difficult if not impossible of reconciliation with facts observed -in adjacent areas. Thus, to account for shell-bearing drift extending up -to the water-shed on one side of a lofty range of hills, a submergence -of the land to a depth of 1,400 feet has been postulated; leaving for -independent explanation the fact, that the opposite slopes of the hills -and the low ground beyond were absolutely destitute of drift or of any -evidence of marine action. - -"In the following pages I must adopt a somewhat dogmatic tone, in order -to confine myself within the limits of space which are imposed; and trust -rather to the cohesion and consistency of the explanations offered and -to a few pregnant facts than to the weighing and contrasting of rival -theories. - -"The facts point conclusively to the action in the British Isles of -a series of glaciers radiating outward from the great hill chains or -clusters, and, as the refrigeration progressed, becoming confluent and -moving though in the same general direction, yet with less regard to the -minor inequalities of the ground. During these two stages many glaciers -must have debouched upon the sea-coast, with the consequent production of -icebergs, which floated off with loads of boulders and dispersed them in -the random fashion which is a necessary characteristic of transport by -floating ice. - -"With a further accentuation of the cold conditions the discharge of -bergs from terminal fronts which advanced into the extremely shallow -seas surrounding the British shores would be quite inadequate to relieve -the great press of ice, and a further coalescence of separate elements -must have resulted. In the case of enclosed seas--as, for example, the -Irish Sea--the continued inthrust of glacier-ice would expel the water -completely; and the conjoined ice-masses would take a direction of flow -the resultant of the momentum and direction of the constituent elements. -In other cases--as, for example, in the North Sea--extraneous ice -approaching the shores might cause a deflection of the flow of the native -glaciers, even though the foreign ice might never actually reach the -shore. - -"To such a system of confluent glaciers, and to the separate elements -out of which they grew, and into which, after the culmination, they were -resolved, I attribute the whole of the phenomena of the English and Welsh -drift. And only at one or two points upon the coast, and raised but -little above the sea-level, can I recognise any signs of marine action. - -"_The Preglacial Level of the Land._--There is very little direct -evidence bearing upon this point. In Norfolk the famous forest bed, with -its associated deposits, stands at almost precisely the level which it -occupied in preglacial times. At Sewerby, near Flamborough Head, there -is an ancient beach and 'buried cliff' which the sea is now denuding of -its swathing of drift-deposits, and its level can be seen to be almost -absolutely coincident with the present beach. Mr. Lamplugh, whose -description of the 'Drifts of Flamborough Head,'[BN] constitutes one of -the gems of glacial literature, considers that there is clear evidence -that the land stood at this level for a long period. The beach is covered -by a rain-wash of small extent, and that in turn by an ancient deposit -of blown sand, while the lowest member of the drift series of Yorkshire -covers the whole. Mr. Lamplugh thinks that the blown sand may indicate -a slight elevation of the land; but the beach appears to me to be the -storm beach, and the reduction in the force of the waves such as would -result from the approach of an ice-front a few miles to the seaward would -probably produce the necessary conditions. - -[Footnote BN: Quarterly Journal of the Geological Society, vol. xlvii.] - -"Six miles to the northward of Flamborough, at Speeton, a bed of -estuarine silt containing the remains of mollusca in the position of life -occurs at an altitude of ninety feet above high-water mark. Mr. Lamplugh -inclines to the opinion that this bed is of earlier date than the 'buried -cliff'; he also admits the possibility that its superior altitude may be -due to a purely local upward bulging of the soft Lower Cretaceous clays -upon which the estuarine bed rests by the weight of the adjacent lofty -chalk escarpment. - -"The evidence obtained from inland sections and borings in different -parts of England has been taken to indicate a greater altitude in -preglacial times. Thus, in Essex, deep-borings have revealed the -existence of deep drift-filled valleys, having their floors below -sea-level. The valley of the Mersey is a still better example. Numerous -borings have been made in the neighbourhood of Widnes and at other places -in the lower reaches of the river, making it clear that there is a -channel filled with drift and extending to 146 feet below mean sea-level. -This, with several other instances, has been taken to indicate a greater -altitude for the land in preglacial times, since a river could not -erode its channel to such a depth below sea-level. The argument appears -inconclusive for one principal reason: no mention is made of any river -gravels or other alluvium in the borings. Indeed, there is an explicit -statement that the deposits are all glacial, showing that the channel -must have been cleared out by ice. This, therefore, leaves open the -vital question, whether the deposits removed were marine or fluviatile. -It may be remarked that the great estuary of the Mersey has undoubtedly -been produced by a post-glacial (and probably post-Roman) movement of -depression. - -"_The Preglacial Climate._--In all speculations regarding the cause -of the Glacial epoch, due account must be taken of the undoubted fact -that it came on with extreme slowness and departed with comparative -suddenness. In the east of England an almost perfect and uninterrupted -sequence of deposits is preserved, extending from the early part of the -Pliocene period down to the present day. - -"These in descending order are: - -"1. Post-glacial sands, gravels, etc. - -"2. Glacial series. - -"3. The 'Forest Bed' and associated marine deposits. - -"4. Chillesford clay and sand. - -"5. The many successive stages of the Red Crag. (The Norwich Crag is a -local variation of the upper part of the Red Crag.) - -"6. The Coralline Crag. - -"The fossils preserved in these deposits, apart from the physical -indications, exhibit the climatal changes which accompanied their -deposition. The Coralline Crag contains a fauna consisting mainly -of species which now range to the Mediterranean, many of them being -restricted to the warm southern waters. Associated with these are a few -boreal forms, but they are represented in general by few individuals. -Here and there in the deposits of this age far-travelled stones are to -be found, but they are always accounted great rarities. - -"The Red Crag consists of an irregular assemblage of beaches and -sand-banks of widely different ages, but their sequence can be made out -with ease by a study of the fauna. In the oldest deposits, Mediterranean -species are very numerous, while the boreal forms are comparatively rare; -but in successive later deposits the proportions are very gradually -reversed, and from the overlying Chillesford series the Mediterranean -species are practically absent. The physical indications run _pari -passu_ with the paleontological, and in the newer beds of the Red Crag -far-travelled stones are common. - -"In the Forest Bed series there is a marine band--the _Leda myalis_ -bed--which contains an almost arctic assemblage of shells; while at about -the same horizon plant remains have been found, including such high -northern species as _Salix polaris_ and _Betula nana_. - -"The glacial deposits do not, in my opinion, contain anywhere in England -or Wales a genuine intrinsic fauna, such shells as occur in the East -Anglian glacial deposits having been derived in part from a contemporary -sea-bed, and, for the rest, from the older formations, down perhaps to -the Coralline Crag. In the post-glacial deposits we have hardly any trace -of a survival of the boreal forms, and I consider that the whole marine -fauna of the North Sea was entirely obliterated at the culmination of the -Glacial epoch, and that the repeopling in post-glacial times proceeded -mainly from the English Channel, into which the northern forms never -penetrated. - - -"_The Great Glacial Centres._ - -"Where such complex interactions have to be described as were produced -by the conflicting glaciers of the British Isles it is difficult to -deal consecutively with the phenomena of any one area, but with short -digressions in explanation of special points it may be possible to -accomplish a clear presentation of the facts. - -"_Wales._--The phenomena of South Wales are comparatively simple. Great -glaciers travelled due southward from the lofty Brecknock Beacons, -and left the characteristic _moutonnée_ appearance upon the rocky bed -over which they moved. The boulder-transport is in entire agreement -with the other indications, and there are no shells in the drift. The -facts awaiting explanation are the occurrence in the boulder-clays of -Glamorganshire, at altitudes up to four hundred feet, of flints, and of -igneous rocks somewhat resembling those of the Archæan series of the -Wrekin. At Clun, in Shropshire, a train of erratics (see map) has been -traced back to its source to the westward. On the west coast, in Cardigan -Bay, the boulders are all such as might have been derived from the -interior of Wales. At St. David's Peninsula, Pembrokeshire, striæ occur -coming in from the northwest, and, taken with the discovery of boulders -of northern rocks, may point to a southward extension of a great glacier -produced by confluent sheets that choked the Irish Sea. Information -is very scanty regarding large areas in mid-Wales, but such as can be -gathered seems to point to ice-shedding having taken place from a north -and south parting line. In North Wales, much admirable work has been done -which clearly indicates the neighbourhood of Great Arenig (Arenig Mawr) -as the radiant point for a great dispersal of blocks of volcanic rock of -a characteristic Welsh type. - -"_Ireland._--A brief reference must be made to Ireland, as the ice which -took origin there played an important part in bringing about some strange -effects in English glaciation, which would be inexplicable without a -recognition of the causes in operation across the Irish Sea. Ireland -is a great basin, surrounded by an almost continuous girdle of hills. -The rainfall is excessive, and the snow-fall was probably more than -proportionately great; therefore we might expect that an ice-sheet of -very large dimensions would result from this combination of favouring -conditions. The Irish ice-sheet appears to have moved outward from about -the centre of the island, but the main flow was probably concentrated -through the gaps in the encircling mountains. - -"_Galloway._--The great range of granite mountains in the southwestern -corner of Scotland seems to have given origin to an immense mass of ice -which moved in the main to the southward, and there are good grounds -for the belief that the whole ice-drainage of the area, even that which -gathered on the northern side of the water-shed, ultimately found its -way into the Irish Sea basin and came down coastwise and across the low -grounds of the Rinns of Galloway, being pushed down by the press of -Highland ice which entered the Firth of Clyde. It is a noteworthy fact -that marine shells occur in the drift in the course taken by the ice -coming on to the extremity of Galloway from the Clyde. - -"_The Lake District._--A radial flow of ice took place down the valleys -from about the centre of the Cumbrian hill-plexus, but movement to the -eastward was at first forbidden by the great rampart of the Cross Fell -escarpment, which stretches like a wall along the eastern side of the -Vale of Eden. - -"During the time when the Cumbrian glaciers had unobstructed access -to the Solway Frith, to the Irish Sea, and to Morecambe Bay, the -dispersal of boulders of characteristic local rocks would follow the -ordinary drainage-lines; but, as will be shown later, a state of affairs -supervened in the Irish Sea which resulted, in many cases, in a complete -reversal of the ice-flow. - -"_The Pennine Chain_ was the source of glaciers of majestic dimensions -upon both its flanks in the region north of Skipton, but to the southward -of that breach in the chain (see map) no evidence is obtainable of any -local glaciers. - - -"_The Confluent Glaciers._ - -"With the growth of ice-caps upon the great centres a condition of -affairs was brought about in the Irish Sea productive of results which -will readily be foreseen. The enormous volumes of ice poured into -the shallow sea from north, south, east, and west, resulted in such -a congestion as to necessitate the initiation of some new systems of -drainage. - -"_The Irish Sea Glacier._--The ice from Galloway, Cumbria, and Ireland -became confluent, forming what the late Professor Carvill Lewis termed -'the Irish Sea Glacier,' and took a direction to the southward. Here it -came in diametrical conflict with the northward-flowing element of the -Welsh sheet, which it arrested and mastered; and the Irish Sea Glacier -bifurcated, probably close upon the precipitous Welsh coast to the -eastward of the Little Orme's Head, and the two branches flowed coastwise -to eastward and westward, keeping near the shore-line. - -"The westerly branch swept round close to the coast in a southwesterly -direction, and completely overrode Anglesea; striating the rock-surfaces -from northeast to southwest (see map), and strewing the country with -its bottom-moraine, containing characteristic northern rocks, such -as the Galloway granites, the lavas and granites of the central and -western portions of the Lake District, and fragments of shells derived -from shell-banks in the Irish Sea. One episode of this phase of the -ice-movement was the invasion of the first line of hills between the -Menai Straits and Snowdon. The gravels and sands of Fridd-bryn-mawr, -Moel Tryfaen, and Moel-y-Cilgwyn, are the coarser washings of the -bottom-moraine, and consequently contain such rock-fragments and shells -as characterise it. From Moel-y-Cilgwyn southward, evidence is lacking -regarding the course taken by the glacier, but it probably passed over or -between the Rivals Mountains (Yr Eifl), and down Cardigan Bay at some -distance from the coast in confluence with the ice from mid-Wales; and, -as I have suggested, may have passed over St. David's Head. - -"Returning now towards the head of the glacier we may follow with -advantage its left bank downward. The ice-flow on the Cumberland coast -appears to have resembled very much that in North Wales. A great press of -ice from the northward (Galloway) seems to have had a powerful 'easting' -imparted to it by the conjoint influences of the thrust of the Irish ice -and the inflow of ice from the Clyde. Whatever may have been the cause, -the effect is clear: about Ravenglass cleavage took place, and a flow to -northward and to southward, each bending easterly. By far the larger mass -took a southerly course and bent round Black Combe, over Walney, and a -strip of the mainland about Barrow in Furness, and out into and across -Morecambe Bay. Its limits are marked in the field by the occurrence of -the same rocks which characterise it in Anglesea, viz., the granites of -Galloway and of west and central Cumbria. - -"The continued thrust shouldered in the glacier upon the mainland of -Lancashire, but the precise point of emergence has not yet been traced, -though it cannot be more than a few miles from the position indicated on -the map. I should here remark, that all along the boundaries the Irish -Sea Glacier was confluent with local ice, except, probably, in that part -of the Pennine chain to the southward of Skipton. Down to Skipton there -was a great mass of Pennine ice which was compelled to take an almost -due southerly course, and thus to run directly athwart the direction of -the main hills and valleys. A sharp easterly inflection of the Irish Sea -Glacier carried it up the valley of the Ribble, and thence, under the -shoulder of Pendle, to Burnley, where Scottish granites are found in the -boulder-clay. - -"On the summit of the Pennine water-shed, at Heald Moor, near Todmorden -(1,419 feet), boulder-clay has been found containing erratics belonging -to this dispersion; while in the gorge of the Yorkshire Calder, which -flows along the eastern side of the same hill, not a vestige of such a -deposit is to be found, saving a few erratic pebbles at a distance of -eight or ten miles, which were probably carried down by flood-wash from -the edge of the ice. - -"From this point the limits of the ice may be traced along the flanks of -the Pennine chain at an average altitude of about 1,100 feet. - -"At one place the erratics can be traced to a position which would -indicate the formation of an extra-morainic lake having its head at a -col about 1,000 feet above sea-level, separating it from the valley of -an eastward-flowing stream, the Wye, about twelve miles down which a few -granite blocks have been found. Other extra-morainic lakes must have -been formed, but very little information has been collected regarding -them. The Irish Sea Glacier can be shown to have spread across the whole -country to the westward of the line I have traced, and beyond the estuary -of the Dee. - -"I may now follow its boundaries on the Welsh coast, and pursue the line -to the final melting-place of the glacier. From the Little Orme's Head -the line of confluence with the native ice is pretty clearly defined. It -runs in, perhaps, half a mile from the shore, until the broad low tract -of the Vale of Clwyd is reached. Here the northern ice obtained a more -complete mastery, and pushed in even as far as Denbigh. This extreme -limit was probably attained as a mere temporary episode. Horizontal striæ -on a vertical face of limestone on the crags dominating the mouth of the -vale on the eastern side attest beyond dispute the action of a mass of -land-ice moving in from the north. - -"I may here remark, that in this district the deposits furnish a very -complete record of the events of the Glacial period. In the cliffs on -the eastern side of the Little Orme's Head, and at several other points -along the coast towards the east, a sequence may be observed as follows: - -"4. Boulder-clay with northern erratics and shells. - -"3. Sands and gravels with northern erratics and shells. - -"2. Boulder-clay with northern erratics and shells. - -"1. Boulder-clay with Welsh erratics and no shells. - -"A similar succession is to be seen in the Vale of Clwyd. The -interpretation is clear: In the early stages of glaciation the Welsh -ice spread without hindrance to, and laid down, bed No. 1; then the -northern ice came down, bringing its typical erratics and the scourings -of the sea-bottom, and laid down the variable series of clays, sands, and -gravels which constitute Nos. 2, 3, and 4 of the section. - -[Illustration: Fig. 42.--The Cefn Cave, in Vale of Clwyd. (Trimmer.) _a_, -Entrance; _b_, mud with pebbles and wood covered with stalagmite; _c_, -mud, bones, and angular fragments of limestone; _d_, sand and silt, with -fragments of marine shells; _e_, fissure; _f_, northern drift; _g_, cave -cleared of mud; _h_, river Elwy, 100 feet below; _i_, limestone rock.] - -"In the Vale of Clwyd an additional interest is imparted to the study of -the drift from the circumstance that the remains of man have been found -in deposits in caves sealed with drift-beds. The best example is the Cae -Gwyn caves, in which flint implements and the bones and teeth of various -extinct animals were found embedded in 'cave-earth' which was overlaid -by bedded deposits of shell-bearing drift, with erratics of the northern -type. - -"It has been supposed that the drift-deposits were marine accumulations; -but it is inconceivable that the cave could ever have been subjected to -wave-action without the complete scouring out of its contents. - -"To resume the delineation of the limits of the great Irish Sea Glacier: -From the Vale of Clwyd the boundary runs along the range of hills -parallel to the estuary of the Dee at an altitude of about nine hundred -feet. As it is traced to the southeast it gradually rises, until at -Frondeg, a few miles to the northward of the embouchure of the Yale of -Llangollen, it is at a height of 1,450 feet above sea-level. Thence it -falls to 1,150 feet at Gloppa, three miles to the westward of Oswestry, -and this is the most southerly point to which it has been definitely -traced on the Welsh border, though scattered boulders of northern rocks -are known to occur at Church Stretton. - -"Along the line from the Vale of Clwyd to Oswestry the boundary is -marked by a very striking series of moraine-mounds. They occur on the -extreme summits of lofty hills in a country generally almost driftless, -and their appearance is so unusual that one--Moel-y-crio--at least -has been mistaken for an artificial tumulus. The limitation of the -dispersal of northern erratics by these mounds is very clear and -sharp; and Mackintosh, in describing those at Frondeg, remarked that, -while no northern rocks extended to the westward of them, so no Welsh -erratics could be found to cross the line to the eastward. There are -Welsh erratics in the low grounds of Cheshire and Shropshire, but their -distribution is sporadic, and will be explained in a subsequent section. - -"Having thus followed around the edges of this glacier, it remains to -describe its termination. It is clear that the ice must have forced its -way over the low water-shed between the respective basins of the Dee and -the Severn. So soon as this ridge (less than 500 feet above the sea) -is crossed, we find the deposits laid down by the glacier change their -character, and sands and gravels attain a great predominance.[BO] Near -Bridgenorth, and, at other places, hills composed of such materials -attain an altitude of 200 feet. From Shrewsbury _via_ Burton, and thence, -in a semicircular sweep, through Bridgenorth and Enville, there is an -immense concentration of boulders and pebbles, such as to justify the -designation of a terminal moraine. To the southward, down the valley -of the Severn, existing information points to the occurrence merely of -such scattered pebbles as might have been carried down by floods. In the -district lying outside this moraine there is a most interesting series of -glacial deposits and of boulders of an entirely different character. (See -map.) - -[Footnote BO: Mackintosh, Q. J. G. S.] - -"From the neighbourhood of Lichfield, through some of the suburbs of -Birmingham, and over Frankley Hill and the Lickey Hills to Bromsgrove, -there is a great accumulation of Welsh erratics, from the neighbourhood, -probably, of Arenig Mawr. - -"The late Professor Carvill Lewis suggested that these Arenig rocks -might have been derived from some adjacent outcrop of Palæozoic rocks--a -suggestion having its justification in the discoveries that had been made -of Cumbrian rocks in the Midlands. To test the matter, an excavation was -made at a point selected on Frankley Hill, and a genuine boulder-clay -was found, containing erratics of the same type as those found upon the -surface. - -"The explanation has since been offered that this boulder-clay was a -marine deposit laid down during a period of submerge nee.[BP] Apart -from the difficulty that the boulder-clay displays none of the ordinary -characteristics of a marine deposition, but possesses a structure, -or rather absence of structure, in many respects quite inconsistent -with such an origin, and contains no shells or other remains of marine -creatures, it must be pointed out that no theory of marine notation -will explain the distribution of the erratics, and especially their -concentration in such numbers at a station sixty or seventy miles from -their source. - -[Footnote BP: Proceedings of the Birmingham Philosophical Society, vol. -vi, Part I, p. 181.] - -"Upon the land-ice hypothesis this difficulty disappears. During the -early stages of the Glacial period the Welsh ice had the whole of -the Severn Valley at its mercy, and a great glacier was thrust down -from Arenig, or some other point in central Wales, having an _initial -direction_, broadly speaking, from west to east. This glacier extended -across the valley of the Severn, sweeping past the Wrekin, whence it -carried blocks of the very characteristic rocks to be lodged as boulders -near Lichfield; and it probably formed its terminal moraine along the -line indicated. (See lozenge-shaped marks on the map.) As the ice in -the north gathered volume it produced the great Irish Sea Glacier, -which pressed inland and down the Vale of Severn in the manner I have -described, and brushed the relatively small Welsh stream out of its path, -and laid down its own terminal moraine in the space between the Welsh -border and the Lickey Hills. It seems probable that the Welsh stream -came mainly down the Vale of Llangollen, and thence to the Lickey Hills. -Boulders of Welsh rocks occur in the intervening tract by ones and twos, -with occasional large clusters, the preservation of any more connected -trail being rendered impossible by the great discharge of water from -the front of the Irish Sea Glacier, and the distributing action of the -glacier itself. - -"Within the area in England and Wales covered by the Irish Sea Glacier -all the phenomena point to the action of land-ice, with the inevitable -concomitants of subglacial streams, extra-morainic lakes, etc. There is -nothing to suggest marine conditions in any form except the occurrence -of shells or shell fragments; and these present so many features of -association, condition, and position inconsistent with, what we should -be led to expect from a study of recent marine life, that conchologists -are unanimous in declaring that not one single group of them is on the -site whereon the shells lived. It is a most significant fact--one out of -a hundred which could be cited did space permit--that in the ten thousand -square miles of, as it is supposed, recently elevated sea-bottom, not a -single example of a bivalve shell with its valves in apposition has ever -been found! Nor has a boulder or other stone been found encrusted with -those ubiquitous marine parasites, the barnacles. - -"The evidences of the action of land-ice within the area are everywhere -apparent in the constancy of direction of-- (1.) Striæ upon rock -surfaces. (2.) The terminal curvature of rocks. (3.) The 'pull-over' of -soft rocks. (4.) The transportal of local boulders. (5.) The orientation -of the long axes of large boulders. (6.) The false bedding of sands -and gravels. (7.) The elongation of drift-hills. (8.) The relations -of 'crag and tail.' There is a similar general constancy, too, in the -directions of the striæ upon large boulders. Upon the under side they run -longitudinally from southeast (or thereabouts) to northwest, while upon -the upper surface they originate at the opposite end, showing that the -scratches on the under side were produced by the stone being dragged from -northwest to southeast, while those on the top were the product of the -passage of stone-laden ice over it in the same direction. - -"Such an agreement cannot be fortuitous, but must be attributed to the -operation of some agent acting in close parallelism over the whole -area. To attribute such regularity to the action of marine currents is -to ignore the most elementary principles of marine hydrology. Icebergs -must, in the nature of things, be the most erratic of all agents, for -the direction of drift is determined--among other varying factors--by -the draught of the berg. A mass of small draught will be carried by -surface currents, while one of greater depth will be brought within the -influence of under-currents; and hence it not infrequently happens that -while floe-ice is drifting, say, to the southeast, giant bergs will go -crashing through it to the northwest. There are tidal influences also to -be reckoned with, and it is matter of common knowledge that flotsam and -jetsam travel back and forth, as they are alternately affected by ebb and -flood tide. - -"Bearing these facts in mind, it is surely too much to expect that -marine ice should transport boulders (how it picked up many of them also -requires explanation) with such unfailing regularity that it can be said -without challenge,[BQ] 'boulders in this district [South Lancashire and -Cheshire] never occur to the north or west of the parent rock.' The -same rule applies without a single authentic exception to the whole -area covered by the eastern branch of the Irish Sea Glacier; and hence -it comes about that not a single boulder of Welsh rock has ever been -recorded from Lancashire. - -[Footnote BQ: Brit. Assoc. Report, 1890, p. 343.] - -"_The Solway Glacier._--The pressure which forced much of the Irish Sea -ice against the Cumbrian coast-line caused, as has been described, a -cleavage of the flow near Ravenglass, and, having followed the southerly -branch to its termination in the midlands, the remaining moiety demands -attention. - -"The 'easting' motion carried it up the Solway Frith, its right flank -spreading over the low plain of northern Cumberland, which it strewed -with boulders of the well-known 'syenite' (granophyre) of Buttermere. -When this ice reached the foot of the Cross Fell escarpment, it suffered -a second bifurcation, one branch pushing to the eastward up the valley -of the Irthing and over into Tyneside, and the other turning nearly due -southward and forcing its way up the broad Vale of Eden. - -"Under the pressure of an enormous head of ice, this stream rose from -sea-level, turned back or incorporated the native Cumbrian Glacier -which stood in its path, and, having arrived almost at the water-shed -between the northern and the southern drainage, it swept round to the -eastward and crossed over the Pennine water-shed; not, however, by the -lowest pass, which is only some 1,400 feet above sea-level, but by the -higher pass of Stainmoor, at altitudes ranging from 1,800 to 2,000 -feet. The lower part of the course of this ice-flow is sufficiently -well characterised by boulders of the granite of the neighbourhood of -Dalbeattie in Galloway; but on its way up the Vale of Eden it gathered -several very remarkable rocks and posted them as way-stones to mark its -course. One of these rocks, the Permian Brockram, occurs nowhere _in -situ_ at altitudes exceeding 700 feet, yet in the course of its short -transit it was lifted about a thousand feet above its source. The Shap -granite (see radiant point on map) is on the northern side of the east -and west water-sheds of the Lake District, and reaches its extreme -elevation, (1,656 feet) on Wasdale Pike; yet boulders of it were carried -over Stainmoor, at an altitude of 1,800 feet literally by tens of -thousands. - -"This Stainmoor Glacier passed directly over the Pennine chain, past the -mouths of several valleys, and into Teesdale, which it descended and -spread out in the low grounds beyond. Pursuing its easterly course, it -abutted upon the lofty Cleveland Hills and separated into two streams, -one of which went straight out to sea at Hartlepool, while the other -turned to the southward and flowed down the Vale of York, being augmented -on its way by tributary glaciers coming down Wensleydale. The final -melting seems to have taken place somewhere a little to the southward -of York; but boulders of Shap granite by which its extension is -characterised have been found as far to the southward as Royston, near -Barnsley. - -"The other branch of the Solway Glacier--that which travelled due -eastward--passed up the valley of the Irthing, and over into that of the -Tyne, and out to sea at Tynemouth. It carried the Scottish granites with -it, and tributary masses joined on either hand, bringing characteristic -boulders with them. - -"The fate of those elements of the Solway Frith Glacier which reached -the sea is not left entirely to conjecture. The striated surfaces near -the coast of Northumberland indicate a coastwise flow of ice from the -northward--probably from the Frith of Forth--and the glaciers coming out -from the Tyne and Tees were deflected to the southward. - -"There is conclusive evidence that this ice rasped the cliffs of the -Yorkshire coast and pressed up into some of the valleys. Where it passed -the mouth of the Tees near Whitby it must have had a height of at least -800 feet, but farther down the coast it diminished in thickness. It -nowhere extended inland more than a mile or two, and for the most part -kept strictly to the coast-line. Along the whole coast are scattered -erratics derived from Galloway and the places lying in the paths of the -glaciers. In many places the cliffs exhibit signs of rough usage, the -rocks being crumpled and distorted by the violent impact of the ice. At -Filey Brigg a well-scratched surface has been discovered, the striation -being from a few degrees east of north. - -"At Speeton the evidence of ice-sheet or glacier-work is of the most -striking character. On the top of the cliffs of Cretaceous strata a line -of moraine-hills has been laid down, extending in wonderful perfection -for a distance of six miles. They consist of a mixture of sand, -gravel, and a species of clay-rubble, with occasional masses of true -boulder-clay, the whole showing the arched bedding so characteristic -of such accumulations. At the northerly end the moraine keeps close to -the edge of the chalk cliffs, which are there 400 feet high, and the -hills are frequently displayed in section; but as the elevation of the -cliffs declines they fall back from the edge of the cliffs and run quite -across the headland of Flamborough, and are again exposed in section in -Bridlington Bay. One remarkable and significant fact is pointed out, -namely, that behind this moraine, within half a mile and at a lower -level, the country is almost absolutely devoid of any drift whatever. - -[Illustration: Fig. 43.--Moraine between Speeton and Flamborough -(Lamplugh).] - -"The interpretation of these phenomena is as follows: When the -valley-glaciers reached the sea they suffered the deflection which has -been mentioned, partly as the result of the interference of ice from -the east of Scotland, but also influenced directly by the cause which -operated upon the Scottish ice and gave direction to it--that is, the -impact of a great glacier from Scandinavia, which almost filled the North -Sea, and turned in the eastward-flowing ice upon the British coast. - -"It is easy to see how this pressure must have forced the glacier-ice -against the Yorkshire coast, but vertical chalk cliffs 400 feet in -height are not readily surmounted by ice of any thickness, however -great, and so it coasted along and discharged its lateral moraine upon -the cliff-tops. As the cliffs diminished in height we find the moraine -farther inland, and, as I have pointed out, the ice completely overrode -Flamborough Head. Amongst the boulders at Flamborough are many of Shap -granite, a few Galloway granites, a profusion of Carboniferous rocks, -brought by the Tyne branch of the Sol way Glacier as well as by that of -Stainmoor, and, besides many torn from the cliffs of Yorkshire, a few -examples of unquestionable Scandinavian rocks, such as the well-known -_Rhomben-porphyr_. It is important to note that about ten to twenty -miles from the Yorkshire coast there is a tract of sea-bottom called -by trawlers 'the rough ground,' in allusion to the fact that it is -strewn with large boulders, amongst which are many of Shap granite. This -probably represents a moraine of the Teesdale Glacier, laid down at a -time when the Scandinavian Glacier was not at its greatest development. - -"On the south side of Flamborough Head the 'buried cliff' previously -alluded to occurs. The configuration of the country shows--and the -conclusion is established by numerous deep-borings--that the preglacial -coast-line takes a great sweep inland from here, and that the plain of -Holderness is the result of the banking-up of an immense thickness of -glacial _débris_. In the whole country reviewed, from Tynemouth to -Bridlington, wherever the ice came on to the land from the seaward, it -brought in shells and fragmentary patches of the sea-bottom involved in -its ground moraine. Space does not permit of a detailed description of -the several members of the Yorkshire Drift, and I pass on to deal in a -general way with the glacial phenomena of the eastern side of England. - -"_The East Anglian Glacier._--The influence of the Scandinavian ice is -clearly seen in the fact that the entire ice-movement down the east -coast south of Bridlington was all from the _seaward_. Clays, sands, and -gravels, the products of a continuous mass of land-ice coming from the -northeast are spread over the whole country, from the Trent to the high -grounds on the north of London overlooking the Thames. - -"The line of extreme extension of these drift-deposits runs from Finchley -(near London), in the south across Hertfordshire, through Cambridgeshire, -with outlying patches at Gogmagog and near Buckingham, and northwestward -over a large portion of Leicestershire into the upper waters of the -Trent, embracing the elevated region of Palæozoic rocks at Charnwood -Forest, near Leicester. - -"Reserving the consideration of the very involved questions connected -with the drifts of the upper part of the Trent Valley, I may pass -on to join the phenomena of the southeastern counties with those at -Flamborough Head. From Nottinghamshire the limits of the drift of the -East Anglian Glacier seem to run in a direction nearly due west to east, -for the great oolitic escarpment upon which Lincoln Cathedral is built -is absolutely driftless to the northward of the breach about Sleaford. -However, along the western flank of the oolitic range true boulder-clay -occurs, bordering and doubtless underlying the great fen-tract of -mid-Lincolnshire; and the great Lincolnshire Wolds appear to have been -completely whelmed beneath the ice. - -"The most remarkable of the deposits in this area is the Great Chalky -Boulder-Clay, which consists of clay containing much ground-up chalk, -and literally packed with well-striated boulders of chalk of all sizes, -from minute pebbles up to blocks a foot or more in diameter. Associated -with them are boulders of various foreign rocks, and many flints in a -remarkably fresh condition, and still retaining the characteristic white -coat, except where partially removed by glacial attrition. - -"One of the perplexing features of the glacial phenomena in the eastern -counties of England is the extension of true chalky boulder-clay to the -north London heights at Finchley and elsewhere; for only the faintest -traces are to be found in the gravel deposits of the Thames Valley of any -wash from such a deposit, or from a glacier carrying such materials. - -"It has been suggested that the deposit may have been laid down in an -extra-morainic lake, or in an extension of the North. Sea, but these -suggestions leave the difficulty just where it was. If a lake or sea -could exist without shores, a glacier-stream might equally dispense with -banks. Within the area of glaciation, defined above, abundant evidence -of the action of land-ice is obtainable, though striated surfaces are -extremely rare--a fact attributable to the softness of the chalk and -clays which occupy almost the whole area. Well-striated surfaces are -found on the harder rocks, as, for example, on the oolitic limestone at -Dunston, near Lincoln. - -"Mr. Skertchly has remarked that the proofs of the action of land-ice -are irrefragable. The Great Chalky Boulder-Clay covers an area of -3,000 square miles, and attains an altitude of 500 feet above the -sea-level, thus bespeaking, if the product of icebergs, 'an extensive -gathering-ground of chalk, having an elevation of more than 500 feet. -But where is it? Certainly not in Western Europe, for the chalk does not -attain so great an elevation except in a few isolated spots.'[BR] - -[Footnote BR: Geikie's Great Ice Age, p. 360.] - -[Illustration: Fig. 44.--Diagram-section near Cromer (Woodward). 6. -Gravel and sand (Middle Glacial) resting on contorted drift (loam, sand, -and marl, with large included boulders of chalk); 5. Cromer till: 4. -Laminated clay and sands (Leda myalis bed); 3. Fresh-water loams and -sands: 3_a_. Black fresh-water bed of Runton (upper fresh-water bed); 2. -Forest bed--laminated clays and sands, with roots and _débris_ of wood, -bones of mammalia, estuarine mollusca, etc., the upper part in places -penetrated by rootlets (rootlet bed); 2_a_. Weybourn crag; 1. Chalk with -flints; * Large included boulder of chalk.] - -"It has been further pointed out by Mr. Skertchly, that the condition of -the flints in this deposit furnishes strong evidence that they could not -have been carried by floating ice nor upon a glacier, for, in either of -the latter events, there must have been some exposure to the weather, -which, as he remarks, would have rendered them worthless to the makers of -gun-flints, whereas they are now regularly collected for their use. - -"The way in which the boulder-clay is related to the rocks upon which -it rests is a conclusive condemnation of any theory of floating ice; -for example, where it rests upon Oxford Clay, it contains the fossils -characteristic of that formation, as it is largely made up of the clay -itself. The exceptions to this rule are as suggestive as those cases -which conform to it. Each outcrop yields material to the boulder-clay to -the south westward, showing a pull-over from the northeast. - -"One of the most remarkable features of the drift of this part of -England is the inclusion of gigantic masses of rock transported for -a short distance from their native outcrop, very often with so small -a disturbance that they have been mapped as _in situ_. Examples of -chalk-masses 800 feet in length, and of considerable breadth and -thickness, have been observed in the cliffs near Cromer, in Norfolk, but -they are by no means restricted to situations near the coast. One example -is mentioned in which quarrying operations had been carried on for some -years before any suspicion was aroused that it was merely an erratic. -The huge boulders were probably dislodged from the parent rock by the -thrust of a great glacier, which first crumbled the beds, then sheared -off a prominent fold and carried it along. This explanation we owe to Mr. -Clement Reid.[BS] The drift-deposits of this region frequently contain -shells, but they rarely constitute what may be termed a consistent fauna, -usually showing such an association as could only be found where some -agent had been at work gathering together shells of different habitats -and geological age. - -[Footnote BS: See Geology of the Country around Cromer, and Geology of -Holderness, Memoirs of Geological Survey of England and Wales.] - -[Illustration: Fig. 45.--Section at right angles to the cliff through -the westerly chalk bluff at Trimingham, Norfolk, showing the manner in -which chalk masses are incorporated into the till (Clement Reid). Scale, -250 fret to an inch. A. Level of low-water spring-tides; B. Chalk, with -sandy bed at *; C. Forest-bed series, etc., seen in the cliffs a few -yards north and south of this point; D. Cromer till, stiff lead-colored -boulder-clay; E. Fine, chalky sands, much false-bedded; F. Contorted -drift, brown bouldery-clay with marked bedding- or fluxion-structure; G. -The bed, above the white line were seen and measured by more snow and -measured by Mr. Reid; * Chalk seen _in situ_ on beach. - -"If the ice-sheet, instead of flowing over the beds, happens to plough -into them or abut against them, it would bend up a boss of chalk, as at -Beeston. A more extensive disturbance, like that at Trimingham drives -before it a long ridge of the bads, and nips up the chalk, till, like -a cloth creased by the sliding of a heavy book, it is folded into an -inverted anticlinal. A slight increase of pressure, and the third stage -is reached--the top of the anticlinal being entirely sheared off, the -chalk boulder driven up an incline, and forced into the overlying -boulder-clays." (Clement Reid.)] - -"Attempts have been made to correlate the deposits over the whole area, -but with very indifferent success. A consideration of the consequences -of the invasion of the country by an ice-stream from the northeast will -prepare us for any conceivable complication of the deposits. - -"The main movement was against the drainage of the country, so that -the ice-front must have been frequently in water. There would be -aqueous deposition and erosion; the kneading up of morainic matter into -ground-moraine; irregularities of distribution and deposition due to ice -floating in an extra-morainic lake; flood-washes at different points of -overflow; and other confusing causes, which make it rather matter for -surprise that any order whatever is traceable. - -"I now turn to the valley of the Trent. We find that it occupies such a -position that it would be exposed, successively or simultaneously, to -the action of ice-streams of most diverse origin. I have shown that the -area to the westward of Lichfield was invaded at one period by a Welsh -glacier, and at a subsequent one by the Irish Sea Glacier, and both of -these streams entered the valley of the Trent or some of its affluents. -From the eastward, again, the great North Sea Glacier encroached in like -manner, carrying the Great Chalky Boulder-Clay even into the drainage -area of the westward-flowing rivers near Coventry. - -"The glacial geology of the Trent Valley from Burton to Nottingham has -been ably dealt with by Mr. R. M. Deeley,[BT] who recognises a succession -which may be generalised as follows: (1.) A lower series containing rocks -derived from the Pennine chain; (2.) A middle series containing rocks -from the eastward (chalky boulder-clay, etc.); and (3.) An upper series -with Pennine rocks. Mr. Deeley thinks the Pennine _débris_ may have -been brought by glaciers flowing down the valleys of the Dove, the Wye, -and the Derwent; but, while recognising the importance of the testimony -adduced, especially that of the boulders, I am compelled to reserve -judgment upon this point until something like moraines or other evidences -of local glaciers can be shown in those valleys. In their upper parts -there is not a sign of glaciation. Some of the deposits described must -have been laid down by land-ice; while the conformation of the country -shows that during some stages of glaciation a lake must have existed -into which the different elements of the converging glaciers must have -projected. This condition will account for the remarkable commingling of -boulders observed in some of the deposits. Welsh, Cumbrian, and Scottish -rocks occur in the western portion of the Trent Valley. The overflow of -the extra-morainic lake would find its way into the valleys of the Avon -and Severn, and may be taken to account for the abundance of flints in -some of the gravels. - -[Footnote BT: Quarterly Journal Geological Society, vol. xlii, p. 437.] - -"_The Isle of Man._--This little island in mid-seas constituted in the -early stages of the Glacial epoch an independent centre of glaciation, -and from some of its valleys ice-streams undoubtedly descended to the -sea; but with the growth of the great Irish Sea Glacier the native ice -was merged in the invading mass, and at the climax of the period the -whole island was completely buried, even to its highest peak (Snae Fell, -2,054 feet), beneath the ice. The effects of this general glaciation -are clearly seen in the mantle of unstratified drift material which -overspread the hills; in the _moutonnée_ appearance of the entire -island; and in the transport of boulders of local rocks. The striations -upon rock surfaces show a constancy of direction in agreement with the -boulder-transport which can be ascribed to no other agency than a great -continuous sheet of such dimensions as to ignore minor hills and valleys. - -"The disposition of the striæ is equally conclusive, for we find that on -a stepped escarpment of limestone both the horizontal and the vertical -faces are striated continuously and obliquely from the one on to the -other, showing that the ice had a power of accommodating itself to the -surface over which it passed that could not be displayed by floating ice. -There is a remarkable fact concerning the distribution of boulders on -this island which would strike the most superficial observers, namely, -that foreign rocks are confined to the low grounds. It might be argued -that the local ice always retained its individuality, and so kept the -foreign ice with its characteristic boulders at bay. But, apart from -the _a priori_ improbability of so small a hill-cluster achieving what -the Lake District could not accomplish, the fact that Snae Fell, an -isolated _conical_ hill, is swathed in drift from top to bottom, is -quite conclusive that the foreign ice must have got in. Why, then, did -it carry no stones with it? The following suggestion I make not without -misgivings, though there are many facts to which I might appeal that seem -strongly corroborative: - -"The hilly axis of the island runs in a general northeast and southwest -direction, and it rises from a great expanse of drift in the north with -singular abruptness, some of the hills being almost inaccessible to a -direct approach without actual climbing. I imagine that the ice which -bore down upon the northern end of the island was, so far as its lower -strata were concerned, unable to ascend so steep an acclivity, and was -cleft, and flowed to right and left. The upper ice, being of ice-sheet -origin, would be relatively clean, and this flowing straight over the -top of the obstruction would glaciate the country with such material as -was lying loose upon the ground or could be dislodged by mere pressure. -It would appear from published descriptions that the Isle of Arran -offers the same problem, and I would suggest the application of the same -solution to it. - -"Marine shells occur in the Manx drift, but only in such situations -as were reached by the ice-laden with foreign stones. They present -similar features of association of shells of different habitat, and -perhaps of geological age, to those already referred to as being common -characteristics of the shell-faunas of the drift of the mainland. Four -extinct species of mollusca have been recognised by me in the Manx drift. - -"The Manx drift is of great interest as showing, perhaps better than any -locality yet studied, those features of the distribution of boulders of -native rocks which attest so clearly the exclusive action of land-ice. -There are in the island many highly characteristic igneous rocks, and I -have found that boulders of these rocks never occur to the northward of -the parent mass, and very rarely in any direction except to the southwest. - -"Cumming observed in regard to one rock, the Foxdale granite, that -whereas the highest point at which it occurs _in situ_ was 657 feet -above sea-level, boulders of it occurred in profusion within 200 feet of -the summit of South Barrule (1,585 feet), a hill two miles only, in a -southwesterly direction, from the granite outcrop. - -"They also occur on the summit of Cronk-na-Irrey-Lhaa, 1,449 feet above -sea-level. The vertical uplift has been 728 and 792 feet respectively. - -"In the low grounds of the north of the island a finely developed -terminal moraine extends in a great sweep so as to obstruct the drainage -and convert thousands of acres of land into lake and morass, which is -only now yielding to artificial drainage. Many fine examples of drumlin -and esker mounds occur at low levels in different parts of the island; -and it was remarked nearly fifty years ago by Cumming, that their long -axes were parallel to the direction of ice-movement indicated by the -striated surfaces and the transport of boulders. - -"The foreign boulders are mainly from the granite mountains of Galloway, -but there are many flints, presumably from Antrim, a very small number -of Lake District rocks, and a remarkable rock containing the excessively -rare variety of hornblende, Riebeckite. This has now been identified with -a rock on Ailsa Crag, a tiny islet in the Frith of Clyde; and a Manx -geologist, the Rev. S. N. Harrison, has discovered a single boulder of -the highly characteristic pitchstone of Corriegills, in the Isle of Arran. - -"_The So-called Great Submergence._ - -"It may be convenient to adduce some additional facts which render the -theory of a great submergence of the country south of the Cheviots -untenable. - -"The sole evidence upon which it rests is the occurrence of shells, -mostly in an extremely fragmentary condition, in deposits occurring at -various levels up to about 1,400 feet above sea-level: A little space may -profitably be devoted to a criticism of this evidence. - -"_Moel Tryfaen_ ('The Hill of the Three Rocks').--This celebrated -locality is on the first rise of the ground between the Menai Straits and -the congeries of hills constituting 'Snowdonia'; and when we look to the -northward from the top of the hill (1,350 feet) we see the ground rising -from the straits in a series of gentle undulations whose smooth contours -would be found from a walk across the country to be due to the thick -mask of glacial deposits which obliterates the harsher features of the -solid rocks. - -"The deposits on Moel Tryfaen are exposed in a slate-quarry on the -northern aspect of the hill near the summit, and consist of two wedges -of structureless boulder-clay, each thinning towards the top of the -hill. The lower mass of clay, wherever it rests upon the rock, contains -streaks and irregular patches of eccentric form, of sharp, perfectly -angular fragments of slate; and the underlying rock may be seen to be -crushed and broken, its cleavage-laminæ being thrust over from northwest -to southeast--that is, _up-hill_. The famous 'shell-bed' is a thick -series of sands and gravels interosculated with the clays on the slope of -the hill, but occupying the entire section above the slate towards the -top. The bedding shows unmistakable signs of the action of water, both -regular stratification and false bedding being well displayed. The stones -occurring in the clays are mainly if not entirely Welsh, including some -from the interior of the country, and they are not infrequently of large -size--two or three tons' weight--and well scratched. - -"The stones found in the sands and gravels include a great majority of -local rocks, but besides these there have been recorded the following: - - Rock. Source. Highest Minimum - point uplift - _in situ_. in feet. - - Granite Eskdale, Cumberland 1,286 64 - Granite Criffel, Galloway ..... ... - Flint Antrim (?) 1,000 350 - To these I can add: - Granophyre Buttermere, Cumberland ..... ... - Eurite [BU] Ailsa Craig, Frith of Clyde 1,097 253 - -[Footnote BU: The altitude at which this rock occurs on Ailsa Craig -has not been announced, so 1 have put it as the extreme height of the -island.] - -"The shells in the Moel Tryfaen deposit have been fully described, so far -as the enumeration of species and relative frequency are concerned, but -little has been said as to their absolute abundance and their condition. -The shells are extremely rare, and daring a recent visit a party of five -persons, in an assiduous search of about two hours, succeeded in finding -_five whole shells_ and about two ounces of fragments. The opportunities -for collecting are as good as could be desired. The sections exposed have -an aggregate length of about a quarter of a mile, with a height varying -from ten to twenty feet of the shelly portion; and besides this there are -immense spoil-banks, upon whose rain-washed slopes fossil-collecting can -be carried on under the most favorable conditions. - -"I would here remark, that the occurrence of small seams of shelly -material of exceptional richness has impressed collectors with the idea -that they were dealing with a veritable shell-bed, when the facts would -bear a very different interpretation. A fictitious abundance is brought -about by a process of what may be termed 'concentration,' by the action -of a gently flowing current of water upon materials of different sizes -and different specific gravities. Shells when but recently vacated -consist of materials of rather high specific gravity, penetrated by pores -containing animal matter, so that the density of the whole mass is far -below that of rocks in general, and hence a current too feeble to move -pebbles would yet carry shells. Illustrations of this process may be -observed upon any shore in the concentration of fragments of coal, corks, -or other light material. - -"Regarding the interpretation of these facts: The commonly received -idea is, that the beds were laid down in the sea during a period of -submergence, and that the shells lived, not perhaps on the spot, but -somewhere near, and that the terminal curvature of the slate was produced -by the grounding of icebergs which also brought the boulders. But if -this hypothesis were accepted, it would be necessary to invest the -flotation of ice with a constancy of direction entirely at variance with -observed facts, for the phenomena of terminal curvature is shown" with -perfect persistence of direction wherever the boulder-clay rests upon the -rock; and, further, there is the highly significant fact, that neither -the sands and gravels nor the rock upon which they rest show any signs of -disturbance or contortion, such as must have been produced if floating -ice had been an operative agent. - -"The uplift of foreign rocks is equally significant; and when we take -into account the great distances from which they have been borne and -the frequency with which such an operation must have been repeated, the -inadequacy becomes apparent of Darwin's ingenious suggestion, that it -might have been effected by a succession of uplifts by shore-ice during -a period of slow subsidence; while the character and abundance of the -molluscan remains invest with a species of irony the application of the -term 'shell-bed' to the deposit. - -"I now turn to the alternative explanation (see _ante_, p. 145), viz., -that the whole of the phenomena were produced by a mass of land-ice which -was forced in upon Moel Tryfaen from the north or northwest, overpowering -any Welsh ice which obstructed its course. This view is in harmony with -the observations regarding the 'terminal curvature' of the slates, the -occurrence of sharp angular chips of slate in the boulder-clay, and the -coincidence of direction of these indications of movement with the carry -of foreign stones. The few shells and shell-crumbs in the sands and -gravels would, upon this hypothesis, be the infinitesimal relics of huge -shell-banks in the Irish Sea which were destroyed by the glacier and in -part incorporated in its ground-moraine or involved in the ice itself. -The sands and gravels would represent the wash which would take place -wherever, by the occurrence of a 'nunatak' or by approach to the edge of -the ice, water could have a free escape. - -"Two principal objections have been urged to the land-ice explanation -of the Moel Tryfaen deposits. An able critic asks, 'Can, then, ice walk -up-hill?' To this we answer, Given a sufficient 'head' behind it, and -ice can certainly achieve that feat, as every _roche moutonnée_ proves. -If it be granted that ice on the small scale can move up-hill, there is -no logical halting-place between the uplift of ten or twenty feet to -surmount a _roche moutonnée_, and an equally gradual elevation to the -height of Moel Tryfaen. Furthermore, the inland ice of Greenland is known -to extrude its ground-moraine on the 'weather-side' of the nunataks, and -the same action would account for the material uplifted on Moel Tryfaen. - -"The second objection brought forward was couched in somewhat these -terms: 'If the Lake District had its ice-sheet, surely Wales had one -also. Could not Snowdonia protect the heart of its own domain?' Of -course, Wales had its ice-sheet, and the question so pointedly raised -by the objector needs an answer; and though it is merely a question -of how much force is requisite to overcome a certain resistance (both -factors being unknown), still there are features in the case which render -it specially interesting and at the same time comparatively easy of -explanation. It seems rather like stating a paradox, yet the fact is, -that it was the proximity of Snowdon which, in my opinion, enabled the -foreign ice to invade Wales at that point. - -"A glance at the map will show that the 'radiant point' of the Welsh ice -was situated on or near Arenig Mawr, and that the great mass of Snowdon -stands quite on the periphery of the mountainous regions of North Wales, -so that it would oppose its bulk to fend off the native ice-sheet and -prevent it from extending seaward in that direction. - -[Illustration: Fig. 46.--Section across Wales to show the relationship of -native to foreign ice.] - -"As a consequence, the only Welsh ice in position to obstruct the onward -march of the invader would be such trifling valley-glaciers as could form -on the western slopes of Snowdon itself. - -"The peak of Snowdon is 3,570 feet above sea-level, and Arenig Mawr, -2,817 feet high, is eighteen miles to the eastward, and a broad, deep -valley with unobstructed access to Cardigan Bay intervenes; so, if any -ice from the central mass made its way over the Snowdonian range, it -performed a much more surprising feat than that involved in the ascent of -Moel Tryfaen from the westward. - -"The profile shows in diagrammatic form the probable relations of the -foreign to the native ice at the time when the Moel Tryfaen deposits were -laid down. - -"From what has been said regarding the great glaciers, it would seem -that ice advanced upon the land from the seaward in several parts of the -coast of England, Wales, and the Isle of Man. Now, it is in precisely -those parts of the country, and those alone, that the remains of marine -animals occur in the glacial deposits. If the dispersal of the shells -found in the drift had been effected by the means I have suggested, it -would follow, as an inevitable consequence, that wherever shells occur -there should also be boulders which have been brought from beyond the -sea. This I find to be the case, and in two instances the discovery of -shells was preliminary to the extension of the boundaries of the known -distribution of boulders of trans-marine origin. - -"The officers of the Geological Survey some years ago observed the -occurrence of 'obscure fragments of marine shells' in a deposit at -Whalley, Lancashire, in which they could find only local rocks. One case -such as this would be fatal to the theory of the _remanié_ origin of the -shells, but on visiting the section with Mr. W. A. Downham, I found, -amongst the very few stones which occurred in the shell-bearing sand at -the spot indicated, two well-marked examples of Cumbrian volcanic rocks, -and, at a little distance, large boulders of Scottish granites. - -"The second case is more striking. The announcement was made that shells -had been found on a hill called Gloppa near Oswestry, in Shropshire, and, -as it lay about five miles to the westward of Mackintosh's boundary of -the Irish Sea Glacier, and therefore well within the area of exclusively -Welsh boulders, it furnished an excellent opportunity of putting the -theory to the test. An examination of the boulders associated with the -shells showed that the whole suite of Galloway and Cumbrian erratics -such as belong to the Irish Sea Glacier were present in great abundance. -Not only this, but in the midst of the series of shell-bearing gravels I -observed a thin lenticular bed of greenish clay, which upon examination -was found to be crowded with well-scratched specimens of Welsh rocks; but -neither a morsel of shell nor a single pebble of a foreign rock could be -found, either by a careful examination in the field or by washing the -clay at home, and examining with a lens the sand and stones separated out. - -"The fact that predictions such as these have been verified affords a -very striking corroboration of the theory put forward; and, though shells -cannot be found in every deposit in which they might, _ex hypothesi_, -be found, yet the strict limitation of them to situations which conform -to those assigned upon theoretical grounds cannot be ascribed to mere -coincidence. If the land had ever been submerged during any part of -the Glacial epoch to a depth of 1,400 feet, it is inconceivable that -clear and indisputable evidence should not be found in abundance in the -sheltered valleys of the Lake District and Wales, which would have been -deep, quiet fiords, in which vast colonies of marine creatures would have -found harbour, as they do in the deep lochs of Scotland to-day. - -"It has been urged, in explanation of this absence of marine remains -in the great hill-centres, that the 'second glaciation' might have -destroyed them; but to do this would require that the ice should make a -clean and complete sweep of all the loose deposits both in the hollows -of the valleys and on the hill-sides, and further that it should destroy -all the shells and all the foreign stones which floated in during the -submergence. At the same time we should have to suppose that the drift -which lay in the paths of the great glaciers was not subjected to any -interference whatever. But, assuming that these difficulties were -explained, there would still remain the fact that the valleys which have -never been glaciated--as, for example, those of Derbyshire--show no -signs whatever of any marine deposits, nor of marine action in any form -whatever. - -"The sea leaves other traces also, besides shells, of its presence -in districts that have really been submerged, yet there are no signs -whatever to be found of them in all England, except the _post_-glacial -raised beaches. Furthermore, in all the area occupied by glacial -deposits there are no true sea-beaches, no cliffs nor sea-worn caves, -no barnacle-encrusted rocks, nor rocks bored by Pholas or Saxicava. Are -we to believe that these never existed; or that, having existed, they -have been obliterated by subsequent denudations? To make good the former -proposition, it would be necessary as a preliminary to show that the -movement of subsidence and re-elevation was so rapid, and the interval -between so brief, that no time was allowed for any marine erosion to -take place. If this were so, it would be the most stupendous catastrophe -of which we have any geological record; but we are not left in doubt -regarding the duration of the submerged condition, for the occurrence -of forty feet of gravel upon the summits of the hills indicates plainly -that, if they were accumulated by the sea, the land must have stood at -that level for a very long period, amply sufficient for the formation of -a well-marked coast-line. - -"The alternative proposition, that post-glacial denudation had removed -the traces of subsidence, is equally at variance with the evidence. -Post-glacial denudation has left kames and drumlins, and all the other -forms of glacial deposits, in almost perfect integrity; the small -kettle-holes are not yet filled up; and it is therefore quite out of the -question that the far more enduring features, such as sea-cliffs, shore -platforms, and beaches, should have been destroyed. - -"The only reasonable conclusion is, that these evidences of marine action -never existed, because the land in glacial times was never depressed -below its present level. If the level were different at all (as I think -may have been the case on the western side of England), it was higher, -and not lower. - -"The details of the submergence hypothesis have, so far as I am aware, -never been dealt with by its advocates, otherwise I cannot but think that -it would have been abandoned long since. It has been stated in general -terms that the subsidence was greatest in the north and diminished to -zero in the south, but no attempt was made to trace the evidence of -extreme subsidence across country and along the principal hill-ranges--in -fact, to see how it varied in every direction. - -"If we take a traverse of England, say from Flamborough Head upon the -east to Moel Tryfaen on the west, and accept as evidence of submergence -any true glacial deposits (except, as in the case of the interior of -Wales, the deposits are obviously the effects of purely local glaciers -and contain, therefore, no shells), we shall find that the subsidence, if -any, must have been not simply differential but sporadic. - -[Illustration: Fig. 47.--Section of the cliff on the east side of South -Sea Landing, Flamborough Head. Scale, 120 feet to 1 inch; length of -section 290 yards; average height, 125 feet. (See above map of moraine -between Speeton and Flamborough.) - -Explanation.--_4._ Brownish boulder-clay, a band of pebbles; _4a_, -in places about seven feet from top. _3._ Washed gravel, with thin -sand-seams, well-bedded, pebbles chiefly erratics. _2._ "Basement" -boulder-clay, with many included patches of sand, gravel, and silt; _2a_, -at _B_, one of these _2b_ contain shells. _1b_. Sand and silt, overlying -and in places interbedded with _1_. _1._ Rubble of angular and subangular -chalk-blocks and gravel, with occasional erratic, passes partly into -chalky boulder-clay, _1a_. _x_. White chalk, without flints, surface much -shaken.] - -"At Flamborough Head shelly drift attains an altitude of 400 feet, -but half a mile from the coast the country is practically driftless -even at lower levels. The Yorkshire Wolds were not submerged. On the -western flanks of the wolds drift comes in at about 100 to 150 feet, and -persists, probably, under the post-glacial warp, from which it again -protrudes on the western side of the valley of the Ouse, and however the -drift between there and the Pennine water-shed may be interpreted, it -shows not a sign of marine origin; but, even granting that it did, we -find that it does not reach within a thousand feet of the water-shed. -When the water-shed is crossed, however, abundant glacial deposits are -met with which are not to be differentiated from others at slightly lower -levels which contain shells. - -[Illustration: Fig. 48.--Enlarged section of the shelly sand and -surrounding clay at _B_ in preceding figure. Scale, 4 feet to 1 inch. - -Explanation.--_2._ "Basement" boulder-clay. _2a_. Pure compact blue and -brown clay of aqueous origin, bedding contorted and nearly obliterated, -but the mass is cut up by shearing planes. _2b_. Irregular seam, and -scattered streaks, of greenish-yellow sand with many marine shells. _2c_. -Patch of pale-yellow sand, different from _2b_, without trace of fossils.] - -"If we suppose that the line of our traverse crosses the Pennine Chain -at Heald Moor, we shall find that on the eastern side no traces of drift -occur above about 300 feet; while the very summit of the water-shed is -occupied by boulder-clay, and thence downward the trace is practically -continuous, and at about 1,000 feet and downward the drift contains -marine shells. Across the great plain of Lancashire and Cheshire -the 'marine' drift is fully developed--though it may be remarked in -parentheses that it contains a shallow-water fauna, albeit _ex hypothesi_ -deposited, in part at least, in a depth of 200 fathoms of water--and to -the Welsh border at Frondeg, where it again reaches a water-shed at an -altitude of 1,450 feet; but at 100 yards to the westward of the summit -all traces of subsidence disappear, and through the centre of Wales no -sign is visible; then we emerge on the western slopes at Moel Tryfaen, -and they assume their fullest dimensions, though only to finish abruptly -on the hill-top, and put in no appearance in the lower grounds which -extend from there to the sea. - -"The conclusions pointed to by the evidence (and, as I have endeavoured -to show, all the evidence which existed at the close of the Glacial -period is there still) are, that a subsidence of the Yorkshire Wolds -took place on the east, but not in the centre or west; that the Pennine -Chain was submerged on the western side to a depth of 1,400 feet, and -on the east to not more than 300 feet, even on opposite sides of the -same individual hill; that all the lowlands between, say, Bacup and the -Welsh border, were submerged, and that the hills near Frondeg partook of -this movement, but only on their eastern sides; that the centre of Wales -was exempt, but that the summit of Moel Tryfaen forms an isolated spot -submerged, while the surrounding country escaped. These absurdities might -be indefinitely multiplied, and they must follow unless it be admitted -that the phenomena are the results of glacial ice, and that ice can move -'up-hill.' - -"The south of England certainly has partaken of no movement of -subsidence. A line drawn from Bristol to London will leave all the true -glacial deposits to the northward, except a bed of very questionable -boulder-clay at Watchet, and a peculiar deposit of clayey rubble which -has been produced on the flanks of the Cornish hills probably, as the -late S. V. Wood, Jr, suggested, by the slipping of material over a -permanently frozen subsoil. - -"For the remainder of the southern area the evidence is plain that there -has been no considerable subsidence during glacial times. The presence -over large areas of chalk country of the 'clay with flints'--a deposit -produced by the gradual solution of the chalk and the accumulation in -situ of its insoluble residue--is absolute demonstration that for immense -periods of time the country has been exempt from any considerable aqueous -action. The enormous accumulations of china clay upon the granite bosses -of Cornwall and Devon tell the same tale. A few erratics have been found -at low levels at various points on the southern coasts, usually not -above the reach of the waves. These consist of rocks which may have been -floated by shore-ice from the Channel Islands or the French coast. - -"This imperfect survey of the evidence against the supposed submergence -has been rendered the more difficult by the fact that it is not -considered necessary to produce the evidence of marine shells in all -cases. Indeed, it has been argued that post-Tertiary beds covering -thousands of square miles might be absolutely destitute of shells without -prejudice to the theory of their formation in the sea. - -"But such a suggestion, one would think, could hardly come from anyone -familiar with marine Tertiary deposits, or even with the appearance of -modern sea-beaches. Admitting, however, for the purposes of argument, -that the beaches along a great extent of coast might be devoid of shells, -it cannot be argued that the deep waters were destitute of life; and -hence the boulder-clays, if of marine origin, should contain a great -abundance of shells and other remains, and, once entombed, it is beyond -belief that they could all be removed from such a deposit in the short -lapse of post-glacial time. - -"Now, some of the boulder-clays--as, for example, those of Lancashire -and Cheshire--are held to be of marine origin, and this is indeed -a vital necessity to the submergence theory; for, if these are not -marine deposits, neither are the other shelly deposits; but these -boulder-clays are absolutely indistinguishable from those lying within -the hill-centres, and, as it passes belief that such deposits could be of -diverse origin and yet possess an identical structure and arrangement, -then we should have a right to demand that these clays should have -enclosed shells and should still contain them, but they do not. - -"I may here mention that I am informed by Mr. W. Shone, F. G. S.--and -he was good enough to permit me to quote the statement--that the -boulder-clay of Cheshire and the shelly boulder-clay of Caithness are 'as -like as two peas.' The importance of this comparison lies in the fact -that, since Croll's classical description, all observers have agreed -that it was the product of land-ice which moved in upon the land out of -the Dornoch Firth. It was pointed out then, as since has been done for -England, that it was only where the direction of ice-movement was from -the seaward that any shells occur in the boulder-clay. - -"_The Dispersion of Erratics of Shap Granite._--So great a significance -attaches to the peculiar distribution of this remarkable rock, that I -may add a few details here which could not be conveniently introduced -elsewhere. - -"This granite occupies an area which lies just to the northward of the -water-shed between the basins of the Lime and the Eden, and its extreme -elevation is 1,656 feet. Boulders occur in large numbers as far to the -northward as Cross Fells, while, as already described, they pass over -Stainmoor and are dispersed in great numbers along the route taken by the -great Stainmoor branch of the Solway Glacier. But a considerable number -of the boulders also found their way to the southward, and a well-marked -trail can be followed down into Morecambe Bay; and at Hest Bank, to the -north of Lancaster, the boulder-clay contains many examples, together -with the 'mica-trap' of the Kendal and Sedbergh dykes and other local -rocks, but no shells or erratics from other sources than the country -draining into Morecambe Bay. To the southward the ice which bore these -rocks was deflected by the great Irish Sea Glacier, and, so far as -present information enables me to state, the Shap granite blocks mark the -course of the medial moraine between these two ice-streams. It has been -found near Garstang, at Longridge, and at Whalley, this being the exact -line of junction of the Irish Sea Glacier with the ice from Morecambe Bay -and the Pennine Chain. - -"It is a very remarkable and significant fact, that not a single -authentic occurrence of the rock across the boundary indicated has yet -been recorded." - - -_Northern Europe._ - -On passing over the shallow German Sea from England to the Continent, -the southern border of the Scandinavian ice-field is found south of -the Zuyder Zee, between Utrecht and Arnhem--the moraine hills in the -vicinity of Arnhem being quite marked, and a barren, sandy plain dotted -with boulders and irregular moraine hills extending most of the way to -the Zuyder Zee. From Arnhem the southern boundary of the great ice-field -runs "eastward across the Rhine Valley, along the base of the Westphalian -Hills, around the projecting promontory of the Hartz, and then southward -through Saxony to the roots of the Erzgebirge. Passing next southeastward -along the flanks of the Riesen and Sudeten chain, it sweeps across Poland -into Russia, circling round by Kiev, and northward by Nijni-Novgorod -towards the Urals."[BV] Thence the boundary passes northward to the -Arctic Ocean, a little east of the White Sea. - -[Footnote BV: A. Geikie's Text-Book of Geology, p. 885.] - -The depth of this northern ice-sheet is proved to have been upwards -of 1,400 feet where it met the Hartz Mountains, for it has deposited -northern _débris_ upon them to that height; while, as already shown, it -must have been over 2,000 feet in the main valley of Switzerland. In -Norway it is estimated that the ice was between 6,000 and 7,000 feet -thick. - -The amount of work done by the continental glaciers of Europe in the -erosion, transportation, and deposition of rock and earthy material is -immense. According to Helland, the average depth of the glacial deposits -over North Germany and northwestern Russia is 150 German feet, i. e., -about 135 English feet. As the deposition towards the margin of a glacier -must be commensurate with its erosion near the centre of movement, this -vast amount implies a still greater proportionate waste in the mountains -of Scandinavia, where the area diminishes with every contraction of -the circle. Two hundred and fifty feet is therefore not an extravagant -calculation for the amount of glacial erosion in the Scandinavian -Peninsula. - -It is not difficult to see how the Scandinavian mountains were able -to contribute so much soil to the plains of northern Germany and -northwestern Russia. Previous to the Glacial period, a warm climate -extended so far north as to permit the growth of semi-tropical vegetation -in Spitsbergen, Greenland, and the northern shores of British America. -Such a climate, with its abundant moisture and vegetation, afforded most -favourable conditions for the superficial disintegration of the rocks. -When, therefore, the cold of the Glacial period came on, the moving -currents of ice would have a comparatively easy task in stripping the -mantle of soil from the hills of Norway and Sweden, and transporting it -towards the periphery of its movement. Of course, erosion in Scandinavia -meant subglacial deposition beyond the Baltic. Doubtless, therefore, the -plains of northern Germany, with their great depth of soil, are true -glacial deposits, whose inequalities of surface have since been much -obliterated, through the general influences of the lapse of time, and by -the ceaseless activity of man. - -An interesting series of moraines in the north of Germany, bordering the -Baltic Sea, was discovered in 1888 by Professor Salisbury, of the United -States Geological Survey. Its course lies through Schleswig-Holstein, -Mecklenburg, Potsdam (about forty miles north of Berlin), thence swinging -more to the north, and following nearly the line between Pomerania and -West Prussia, crossing the Vistula about twenty miles south of Dantzic, -thence easterly to the Spirding See, near the boundary of Poland. - -Among the places where this moraine can be best seen are--"1. In Province -Holstein, the region about (especially north of) Eutin; 2. Province -Mecklenburg, north of Crivitz, and between Bütow and Kröpelin; 3. -Province Brandenburg, south of Reckatel, between Strassen and Bärenbusch, -south of Fürstenberg and north of Everswalde, and between Pyritz and -Solden; 4. Province Posen, east of Locknitz, and at numerous points to -the south, and especially about Falkenburg, and between Lompelburg and -Bärwalde. This is one of the best localities. 5. Province West Preussen, -east of Bütow; 6. Province Ost Preussen, between Horn and Widikin." - -Comparing these with the moraines of America, Professor Salisbury remarks: - -"In its composition from several members, in its variety of development, -in its topographic relations, in its topography, in its constitution, in -its associated deposits, and in its wide separation from the outermost -drift limit, this morainic belt corresponds to the extensive morainic -belt of America, which extends from Dakota to the Atlantic Ocean. That -the one formation corresponds to the other does not admit of doubt. In -all essential characteristics they are identical in character. What may -be their relations in time remains to be determined." - -[Illustration: Fig. 49.--Map showing the glaciated area of Europe -according to J. Geikie, and the moraines in Britain and Germany according -to Lewis and Salisbury.] - -The physical geography of Europe is so different from that of America, -that there was a marked difference in the secondary or incidental effects -of the Glacial period upon the two regions. In America the continental -area over which the glaciers spread is comparatively simple in its -outlines. East of the Rocky Mountains, as we have seen, the drainage -of the Glacial period was, for a time, nearly all concentrated in the -Mississippi basin, and the streams had a free course southward. - -But in Europe there was no free drainage to the south, except over -a small portion of the glaciated area in central Russia, about the -head-waters of the Dnieper, the Don, and the Volga; though the Danube -and the Rhône afforded free course for the waters of a portion of the -great Alpine glaciers. But all the great rivers of northern Europe -flow to the northward, and, with the exception of the Seine, they all -for a time encountered the front of the continental ice-sheet. This -circumstance makes it difficult to distinguish closely between the direct -glacial deposits in Europe and those which are more or less modified -by water-action. At first sight it would seem also somewhat hazardous -to attempt to correlate with any portion of the Glacial period the -deposition of the gravelly and loamy deposits in valleys, which, like -those of the Seine and Somme, lie entirely outside of the glaciated area. - -Upon close examination, however, the elements of doubt more and more -disappear. The Glacial period was one of great precipitation, and it -is natural to suppose that the area of excessive snow-fall extended -considerably beyond the limit of the ice-front. During that period -therefore, the rivers of central France must have been annually flooded -to an extent far beyond anything which is known at the present time. -Since these rivers flowed to the northward, at a period when, during -the long and severe winters, the annual accumulation of ice near their -mouths was excessive, ice-gorges of immense extent, such as now form -about the mouths of the Siberian rivers, would regularly occur. We are -not surprised, therefore, to find, even in these streams, abundant -indications of the indirect influence of the great northern ice-sheet. - -The indications referred to consist of high-level gravel terraces -occasionally containing boulders, of from four to five tons weight, which -have been transported for a considerable distance. The elevation of the -terraces above the present flood-plains of the Seine and Somme reaches -from 100 to 150 feet. We are not to suppose, however, that even in -glacial times the floods of the river Seine could have filled its present -valley to that height. The highest flood in this river known in historic -times rose only to a height of twenty-nine feet. Mr. Prestwich estimates -that, without taking into consideration the more rapid discharge, a flood -of sixty times this magnitude would be required to fill the present -valley to the level of the ancient gravels, while at Amiens the shape of -the valley of the Somme is such that five hundred times the mean average -of the stream would be required to reach the high-level gravels. The -conclusion, therefore, is that the troughs of these streams have been -largely formed by erosion since the deposition of the high-level gravels. - -Connected with these terrace gravels in northern France is a loamy -deposit, corresponding to the loess in other parts of Europe, and to a -similar deposit to which we have referred in describing the southwestern -part of the glaciated area in North America. In northern France this fine -silt overlies the high-level gravel deposits, and, as Mr. Prestwich has -pretty clearly shown, was deposited contemporaneously with them during -the early inundations and before the stream had eroded its channel to its -present level. - -The distribution of loess in Europe was doubtless connected with the -peculiar glacial conditions of the continent. Its typical development -is in the valley of the Rhine, where it is described by Professor -James Geikie "as a yellow or pale greyish-brown, fine-grained, and -more or less homogeneous, consistent, non-plastic loam, consisting of -an intimate admixture of clay and carbonate of lime. It is frequently -minutely perforated by long, vertical, root-like tubes which are lined -with carbonate of lime--a structure which imparts to the loess a strong -tendency to cleave or divide in vertical planes. Thus it usually presents -upright bluffs or cliffs upon the margins of streams and rivers which -intersect it. Very often it contains concretions or nodules of irregular -form.... Land-shells and the remains of land animals are the most common -fossils of the loess, but occasionally fresh-water shells and the bones -of fresh-water fish occur." - -"From the margins of the modern alluvial flats which form the bottoms -of the valleys it rises to a height of 200 or 300 feet above the -streams--sweeping up the slopes of the valleys, and imparting a rich -productiveness to many districts which would otherwise be comparatively -unfruitful. From the Rhienthal itself it extends into all the tributary -valleys--those of the Neckar, the Main, the Lahn, the Moselle, and the -Meuse, being more or less abundantly charged with it. It spreads, in -short, like a great winding-sheet over the country--lying thickly in the -valleys and dying off upon the higher slopes and plateaux. Wide and deep -accumulations appear likewise in the Rhône Valley, as also in several -other river-valleys of France, as in those of the Seine, the Saône, and -the Garonne, and the same is the case with many of the valleys of middle -Germany, such as those of the Fulda, the Werra, the Weser, and the upper -reaches of the great basin of the Elbe. It must not be supposed that the -loess is restricted to valleys and depressions in the surface of the -ground. - -"It is true that it attains in these its greatest thickness, but -extensive accumulations may often be followed far into the intermediate -hilly districts and over the neighbouring plateaux. Thus the Odenwald, -the Taunus, the Vogelgebirge, and other upland tracts, are cloaked with -loess up to a considerable height. Crossing into the drainage system of -the Danube, we find that this large river and many of its tributaries -flow through vast tracts of loess. Lower Bavaria is thickly coated with -it, and it attains a great development in Bohemia, Upper and Lower -Austria, and Moravia--in the latter country rising to an elevation of -1,300 feet. It is equally abundant in Hungary, Galicia, Bukowina, and -Transylvania. From the Danubian flat lands and the low grounds of Galicia -it stretches into the valleys of the Carpathians, up to heights of 800 -and 2,000 feet. In some cases it goes even higher--namely, to 3,000 -feet, according to Zeuschner, and to 4,000 or 5,000 feet, according to -Korzistka. These last great elevations, it will be understood, are in -the upper valleys of the northern Carpathians. In Roumania loess is -likewise plentiful, but it has not been observed south of the Balkans. -East of the Carpathians--that is to say, in the regions watered by the -Dniester, the Dnieper, and the Don--loess appears also to be wanting, -and to be represented by those great steppe-deposits which are known as -_Tchernozen_, or black earth."[BW] - -[Footnote BW: Prehistoric Europe, pp. 144-146.] - -The shells found in the loess indicate both a colder and a wetter climate -during its deposition than that which now exists. The relics of land -animals are infrequently found in the deposit, yet they do occur, but -mostly in fragmentary condition--the principal animals represented being -the mammoth, the rhinoceros, the reindeer, and the horse; which is about -the same variety as is found in the gravel deposits of the Glacial -period, both in western Europe and in America. - -A species of loess--differing, however, somewhat in color from that on -the Rhine--covers the plains of northeastern France up to an elevation of -700 feet above the the sea, where, as we have already said, it overlies -the high-level gravels of the Seine and the Somme. Above this height -the superficial soil in France is evidently merely the decomposed upper -surface of the native rock. - -The probable explanation of all these deposits, included under the term -"loess," is the same as that already given by Prestwich of the loamy -deposits of northern France. But in case of rivers, which, like the -Rhine, encountered the ice-front in their northward flow, a flooded -condition favouring the accumulation of loess was doubtless promoted by -the continental ice-barrier. In the case of the Danube and the Rhône, -however, where there was a free outlet away from the glaciated region, -the loess in the upper part of the valleys must have accumulated in -connection with glacial floods quite similar to those which we have -described as spreading over the imperfectly formed water-courses of the -Mississippi basin during the close of the Ice age. That the typical loess -is of glacial origin is pretty certainly shown, both by its distribution -in front of glaciers and by its evident mechanical origin when studied -under the microscope. It is, in short, the fine sediment which gives the -milky whiteness to glacial rivers. - -In central Russia there is a considerable area in which the glacial -conditions were, in one respect, similar to those in the northern part -of the Mississippi Valley in the United States. In both regions the -continental ice-sheet surmounted the river partings, and spread over the -upper portion of an extensive plain whose drainage was to the south. The -Dnieper, the Don, and the western branch of the Volga, like the Ohio -and the Mississippi, have their head-waters in the glaciated region. In -some other respects, also, there is a resemblance between the plains -bordering the glaciated region in central Russia and those which in -America border it in the Mississippi Valley. Mr. James Geikie is of the -opinion that the extensive belt of black earth adjoining the glaciated -area in Russia, and constituting the most productive agricultural portion -of the country, derives its fertility, as does much of the Mississippi -Valley, from the blanket of glacial silt spread pretty evenly over it. -Thus it would appear that in Europe, as in America, the ice of the -Glacial period was a most beneficent agent, preparing the face of the -earth for the permanent occupation of man. On both continents the seat -of empire is in the area once occupied by the advance of the great -ice-movements of that desolate epoch. - - -_Asia._ - -East of the Urals, in northern Asia, there is no evidence of moving ice -upon the land during the Glacial period; but at Yakutsk, in latitude 62° -north, the soil is frozen at the present time to an unknown depth, and -many of the Siberian rivers, as they approach and empty into the Arctic -Sea, flow between cliffs of perpetual ice or frozen ground. The changes -that came over this region during the Glacial period are impressively -indicated by the animal remains which have been preserved in these -motionless icy cliffs. In the early part of the period herds of mammoth -and woolly rhinoceros roamed over the plains of Siberia, and waged an -unequal warfare with the slowly converging and destructive forces. The -heads and tusks of these animals were so abundant in Siberia that they -long supplied all Russia with ivory, besides contributing no small -amount for export to other countries. "In 1872 and 1873 as many as 2,770 -mammoth-tusks, weighing from 140 to 160 pounds each, were entered at the -London clocks."[BX] So perfectly have the carcasses of these extinct -animals been preserved in the frozen soil of northern Siberia that when, -after the lapse of thousands of years, floods have washed them out from -the frozen cliffs, dogs and wolves and bears have fed upon their flesh -with avidity. In some instances even "portions of the food of these -animals were found in the cavities of the teeth. Microscopic examination -showed that they fed upon the leaves and shoots of the coniferous trees -which then clothed the plains of Siberia." A skeleton and parts of -the skin, and some of the softer portions of the body of a mammoth, -discovered in 1799 in the frozen cliff near the mouth of the Lena, was -carried to St. Petersburg in 1806, from which it was ascertained that -this huge animal was "covered with alight-coloured, curly, very thick-set -hair one to two inches in length, interspersed with darker-colored hair -and bristles from four to eighteen inches long."[BY] - -[Footnote BX: Prestwich's Geology, vol. ii, p. 460.] - -[Footnote BY: Prestwich's Geology, vol. ii, p. 460.] - -In the valleys of Sikkim and eastern Nepaul, in northern India, glaciers -formerly extended 6,000 feet lower than now, or to about the 5,000-foot -level, and in the western Himalayas to a still lower level. The higher -ranges of mountains in other portions of Asia also show many signs of -former glaciation. This is specially true of the Caucasus, where the -ancient glaciers were of vast extent. According, also, to Sir Joseph -Hooker, the cedars of Lebanon flourish upon an ancient moraine. Of the -glacial phenomena in other portions of Asia little is known. - - -_Africa._ - -Northern and even central Africa must likewise come in for their share -of attention. The Atlas Mountains, rising to a height of 13,000 feet, -though supporting none at the present time, formerly sustained glaciers -of considerable size. Moraines are found in several places as low as the -4,000-foot level, and one at an altitude of 4,000 feet is from 800 to 900 -feet high, and completely crosses and dams up the ravine down which the -glacier formerly came. - -Some have supposed that there are indubitable evidences of former -glaciation in the mountain-ranges of southwestern Africa between latitude -30° and 33°, but the evidence is not as unequivocal as we could wish, and -we will not pause upon it. - -The mountains of _Australia_, also, some of which rise to a height of -more than 7,000 feet, are supposed to have been once covered with glacial -ice down to the level of 5,800 feet, but the evidence is at present too -scanty to build upon. But in _New Zealand_ the glaciers now clustering -about the peaks in the middle of the South Island, culminating in Mount -Cook, are but diminutive representatives of their predecessors. This is -indicated by extensive moraines in the lower part of the valleys and by -the existence of numerous lakes, attributable, like so many in Europe and -North America, to the irregular deposition of morainic material by the -ancient ice-sheet.[BZ] - -[Footnote BZ: See With Axe and Rope in the New Zealand Alps, by G. E. -Mannering, 1891.] - - - - -CHAPTER VII. - -DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. - - -We will begin the consideration of this part of our subject, also, with -the presentation of the salient facts in North America, since that field -is simpler than any field in the Old World. - -The natural drainage basins of North America east of the Rocky Mountains -are readily described. The Mississippi River and its branches drain -nearly all the region lying between the Appalachian chain and the Rocky -Mountains and south of the Dominion of Canada and of the Great Lakes. -All the southern tributaries to the Great Lakes are insignificant, the -river partings on the south being reached in a very short distance. The -drainage of the rather limited basin of the Great Lakes is northeastward -through the St. Lawrence River, leaving nearly all of the Dominion of -Canada east of the Rocky Mountains to pour its surplus waters northward -into Hudson Bay and the Arctic Ocean. With the exception of the St. -Lawrence River, these are essentially permanent systems of drainage. To -understand the extent to which the ice of the Glacial period modified -these systems, we must first get before our minds a picture of the -country before the accumulation of ice began. - - -_Preglacial Erosion._ - -Reference has already been made to the elevated condition of the northern -and central parts of North America at the beginning of the Glacial -period. The direct proof of this preglacial elevation is largely derived -from the fiords and great lake basins of the continent. The word "fiord" -is descriptive of the deep and narrow inlets of the sea specially -characteristic of the coasts of Norway, Denmark. Iceland, and British -Columbia. Usually also fiords are connected with valleys extending still -farther inland, and occupied by streams. - -Fiords are probably due in great part to river erosion when the shores -stood at considerably higher level than now. Slowly, during the course -of ages, the streams wore out for themselves immense gorges, and were -assisted, perhaps, to some extent by the glaciers which naturally came -into existence during the higher continental elevation. The present -condition of fiords, occupied as they usually are by great depths of -sea-water, would be accounted for by recent subsidence of the land. In -short, fiords seem essentially to be submerged river gorges, partially -silted up near their mouths, or perhaps partially closed by terminal -moraines. - -It is not alone in northwestern Europe and British Columbia that fiords -are found, but they characterize as well the eastern coast of America -north of Maine, while even farther south, both on the Atlantic and on -the Pacific coast, some extensive examples exist, whose course has been -revealed only to the sounding-line of the Government survey. - -The most remarkable of the submerged fiords in the middle Atlantic region -of the United States is the continuation of the trough of Hudson River -beyond New York Bay. As long ago as 1844 the work of the United States -Coast Survey showed that there was a submarine continuation of this -valley, extending through the comparatively shallow waters eighty miles -or more seaward from Sandy Hook. - -[Illustration: Fig. 50.--Map showing old channel and mouth of the Hudson -(dewberry).] - -The more accurate surveys conducted from 1880 to 1884 have brought to -our knowledge the facts about this submarine valley almost as clearly -as those relating to the inland portion of it above New York city. -According to Mr. A. Lindenkohl,[CA] this submarine valley began to be -noticeable in the soundings ten miles southeast of Sandy Hook. The depth -of the water where the channel begins is nineteen fathoms (114 feet). -Ten miles out the channel has sunk ninety feet below the general depth -of the water on the bank, and continues at this depth for twenty miles -farther. This narrow channel continues with more or less variation for -a distance of seventy-five miles, where it suddenly enlarges to a width -of three miles and to a depth of 200 fathoms, or 1,200 feet, and extends -for a distance of twenty-five miles, reaching near that point a depth -of 474 fathoms, or 2,844 feet. According to Mr. Lindenkohl, this ravine -maintains for half its length "a vertical depth of more than 2,000 feet, -measuring from the top of its banks, and the banks have a nearly uniform -slope of about 14°." The mouth of the ravine opens out into the deep -basin of the central Atlantic. - -[Footnote CA: Bulletin of the Geological Society of America, vol. i, p. -564; American Journal of Science, June, 1891.] - -With little question there is brought to light in these remarkable -investigations a channel eroded by the extension of the Hudson River, -into the bordering shelf of the Atlantic basin at a time when the -elevation of the continent was much greater than now. This is shown to -have occurred in late Tertiary or post-Tertiary times by the fact that -the strata through which it is worn are the continuation of the Tertiary -deposits of New Jersey. The subsidence to its present level has probably -been gradual, and, according to Professor Cook, is still continuing at -the rate of two feet a century. - -Similar submarine channels are found extending out from the present -shore-line to the margin of the narrow shelf bordering the deep water of -the central Atlantic running from the mouth of the St. Lawrence River, -through St. Lawrence Bay, and through Delaware and Chesapeake Bays.[CB] -All these submerged fiords on the Atlantic coast were probably formed -during a continental elevation which commenced late in the Tertiary -period, and reached the amount of from 2,000 to 3,000 feet in the -northern part of the continent. - -[Footnote CB: See Lindenkohl in American Journal of Science, for June, -1891.] - -[Illustration: Fig. 51.--New York harbor in preglacial times looking -south, from south end of New York Island (Newberry).] - -To this period must probably be referred also the formation of the gorge, -or more properly fiord, of the Saguenay, which joins the St. Lawrence -below Quebec. The great depth of this fiord is certainly surprising, -since, according to Sir William Dawson, its bottom, for fifty miles above -the St. Lawrence, is 840 feet below the sea-level, while the bordering -cliffs are in some places 1,500 feet above the water. The average width -is something over a mile. - -It seems impossible to account for such a deep gorge extending so far -below the sea-level, except upon the supposition of a long-continued -continental elevation, which should allow the stream to form a cañon to -an extent somewhat comparable with that of the cañons of the Colorado and -other rivers in the far West. Then, upon the subsidence of the continent -to the present level, it would remain partially or wholly submerged, -as we find it at the present time. During the Glacial period it was so -filled with ice as to prevent silting up. The rivers entering the Pacific -Ocean, both in the United States and in British Columbia, are also lost -in submerged channels extending out to the deeper waters of the Pacific -basin in a manner closely similar to the Atlantic streams which have been -mentioned. - -During this continental elevation which preceded, accompanied, and -perhaps brought on the Glacial period, erosion must have proceeded with -great intensity along all the lines of drainage, and throughout the whole -region which is now covered, and to a considerable extent smoothed over, -by glacial deposits, and the whole country must have presented a very -different appearance from what it does now. - -A pretty definite idea of its preglacial condition can probably be formed -by studying the appearance of the regions outside of and adjoining that -which was covered by the continental glacier. The contrast between the -glaciated and the unglaciated region is striking in several respects -aside from the presence and absence of transported rocks and other -_débris_, but in nothing is it greater than in the extent of river -erosion which is apparent upon the surface. For example, upon the -western flanks of the Alleghanies the regions south of the glacial limit -is everywhere deeply channeled by streams. Indeed, so long have they -evidently been permitted to work in their present channels that, wherever -there have been waterfalls, they have receded to the very head-waters, -and no cataracts exist in them at the present time. Nor are there in the -unglaciated region any lakes of importance, such as characterize the -glaciated region. If there have been lakes, the lapse of time has been -sufficient for their outlets to lower their beds sufficiently to drain -the basins dry. - -On entering the glaciated area all this is changed. The ice-movement -has everywhere done much to wear down the hills and fill the valleys, -and, where there was _débris_ enough at command, it has obliterated the -narrow gorges originally occupied by the preglacial streams. Thus it has -completely changed the minor lines of superficial drainage, and in many -instances has produced most extensive and radical changes in the whole -drainage system of the region. In the glaciated area, channels buried -beneath glaciated _débris_ are of frequent occurrence, while many of the -streams which occupy their preglacial channels are flowing at a very much -higher level than formerly, the lower part of the channel having been -silted up by the superabundant _débris_ accessible since the glacial -movement began. - - -_Buried Outlets and Channels._ - -It is easy to see how the great number of shallow lakes which frequent -the glaciated region were formed by the irregular deposition of glacial -_débris_, but it is somewhat more difficult to trace out the connection -between the Glacial period and the Great Lakes of North America, several -of which are of such depth that their bottoms are some hundreds of feet -below the sea-level, Lake Erie furnishing the only exception. This -lake is so shallow that it is easy to see how its basin may have been -principally formed by river erosion, while it is evident that such -must have been the mode of its formation, since it is surrounded by -sedimentary strata lying nearly in a horizontal position. - -[Illustration: Fig. 52.--Section across the valley of the Cuyahoga River, -twenty miles above its mouth (Claypole).] - -That Lake Erie is really nothing but a "glacial mill-pond" is proved -also by much direct evidence, especially that derived from the depth of -the buried channels of the streams flowing into it from the south. Of -these, the Cuyahoga River, which enters the lake at Cleveland, has been -most fully investigated. In searching for oil, some years ago, borings -were made at many places for twenty-five miles above the mouth of the -river. As a result, it appeared that for the whole distance the rocky -bottom of the gorge was about two hundred feet below the present bottom -of the river, while the river itself is two or three hundred feet below -the general level of the country, occupying a trough about half a mile in -width, with steep, rocky sides. These facts indicate that at one time the -river must have found opportunity to discharge its contents at a level -two hundred feet below that of the present lake, while an examination -of the material filling up the bottom of the gorge to its present level -shows it to be glacial _débris_, thus proving that the silting up was -accomplished during the Glacial period. - -As the water of Lake Erie is for the most part less than one hundred -feet in depth, and is nowhere much more than two hundred feet deep, it -is clear that the preglacial outlet which drained it down to the level -of the rocky bottom of the Cuyahoga River must have destroyed the lake -altogether. Hence Ave may be certain that, before the Glacial period, the -area now covered by the lake was simply a broad, shallow valley through -which there coursed a single river of great magnitude, with tributary -branches occupying deep gorges. Professor J. W. Spencer has shown with -great probability that the old line of drainage from Lake Erie passed -through the lower part of the valley of Grand River, in Canada, and -entered Lake Ontario at its western extremity, and that during the great -Ice age this became so completely obstructed with glacial _débris_ as to -form an impenetrable dam, and to cause the pent-up water to flow through -the Niagara Valley, which chanced to furnish the lowest opening. - -In speaking of the present area of Lake Erie, however, as being then -occupied by a river valley, we do not mean to imply that it was not -afterwards greatly modified by glacial erosion; for undoubtedly this was -the case, whatever views we may have as to the relative efficiency of ice -and water in scooping out lake basins. - -In the case of Lake Erie, we need suppose no change of level to account -for the erosion of its basin, but only that, since the strata in which it -is situated were deposited, time enough had elapsed for a great river to -cut a gorge extending from the western end of Lake Ontario through to the -present bed of Lake Erie, and that here a great enlargement of the valley -was occasioned by the existence of deep beds of soft shale which could -easily be worn away by a ramifying system of tributary streams. Rivers -acting at present relative levels would be amply sufficient to produce -the results which are here manifest. - -But in the case of Lakes Ontario, Huron, Michigan, and Superior, whose -depths descend considerably below the sea-level, we must suppose that -they were, in the main, eroded when the continent was so much elevated -that their bottoms were brought above tide-level. The depth of Lake -Ontario implies the existence of an outlet more than four hundred feet -lower than at present, which, of course, could exist only when the -general elevation was more than four hundred feet greater than now. - -The existence of an outlet at that depth seems to be proved also by the -fact that at Syracuse, where numerous wells have been sunk to obtain -brine for the manufacture of salt, deposits of sand, gravel, and rolled -stones, four hundred and fifty feet thick, are penetrated without -reaching rock. Since this lies in the basin of Lake Ontario, it follows -that if the basin itself has been produced by river erosion, the land -must have been of sufficient height to permit an outlet through a valley, -or cañon, of the required depth, and this outlet must now be buried -beneath the abundant glacial _débris_ that covers the region. - -Professor Newberry, who has studied the vicinity carefully, is of the -opinion that there is ample opportunity for such a line of drainage -to have extended through the Mohawk Valley to the Hudson River. But, -at Little Falls, a spur of the Adirondack Mountains projects into the -valley, and the Archæan rocks over which the river runs are so prominent -and continuous that some have thought it impossible for the requisite -channel to have ever existed there. Extensive deposits of glacial -_débris_, however, are found in the vicinity, especially in places some -distance to the north, and in Professor Newberry's opinion the existence -of a buried channel around the obstruction upon the north side is by no -means improbable. - -The preglacial drainage of Lake Huron has not been determined with any -great degree of probability. Professor Spencer formerly supposed that it -passed from the southern end of the lake through London, in the western -part of Ontario, and reached the Erie basin near Port Stanley, and so -augmented the volume of the ancient river which eroded the buried cañon -from Lake Erie to Lake Ontario. But he now supposes, though the evidence -is by no means demonstrative, that the waters of Lake Huron passed into -Lake Ontario by means of a channel extending from Georgian Bay to the -vicinity of Toronto. - -With a fair degree of probability, the basin of Lake Superior is -supposed by Professor Newberry to have been joined to that of Lake -Michigan by some passage, now buried, considerably to the west of the -Strait of Mackinac, and thence to have had an outlet southward from the -vicinity of Chicago directly into the Mississippi River. Of this there -is considerable evidence furnished by deeply buried channels which have -been penetrated by borings in various places in Kankakee, Livingston, -and McLean Counties, Illinois; but the whole area extending from Lake -Michigan to the Mississippi is so deeply covered with glacial _débris_ -that the surface of the country gives no satisfactory indication of the -exact lines of preglacial drainage. - -Some of the most remarkable instances of ancient river channels buried -by the glacial deposits have been brought to light in southwestern Ohio, -where there has been great activity in boring for gas and oil. At St. -Paris, Champaign County, for example, in a locality where the surface -of the rock near by was known to be not far below the general level, a -boring was begun and continued to a depth of more than five hundred feet -without reaching rock, or passing out of glacial _débris_. - -Many years ago Professor Newberry collected sufficient facts to show that -pretty generally the ancient bed of the Ohio River was as much as 150 -feet below that over which it now flows. During a continental elevation -the erosion had proceeded to that extent, and then the channel had been -silted up during the Glacial period with the abundant material carried -down by the streams from the glaciated area. One of the evidences of -the preglacial depth of the channel of the Ohio was brought to light at -Cincinnati, where "gravel and sand have been found to extend to a depth -of over one hundred feet below low-water mark, and the bottom of the -trough has not been reached." In the valley of Mill Creek, also, "in the -suburbs of Cincinnati, gravel and sand were penetrated to the depth of -120 feet below the stream before reaching rock." But from the general -appearance of the channel, Professor J. F. James was led to surmise -that a rock bottom extended all the way across the present channel of -the Ohio, between Price Hill and Ludlow, Ky., a short distance below -Cincinnati, which would preclude the possibility of a preglacial outlet -at the depth disclosed in that direction. Mr. Charles J. Bates (who was -inspector of the masonry for the Cincinnati Southern Railroad while -building the bridge across the Ohio at this point) informs me that Mr. -James's surmise is certainly correct, and that his "in all probability" -may be displaced by "certainly," since the bedded rocks supposed by -Professor James to extend across the river a few feet below its present -bottom were found by the engineers to be in actual existence. - -In looking for an outlet for the waters of the upper Ohio which should -permit them to flow off at the low level reached in the channel at -Cincinnati, Professor James was led to inspect the valley extending -up Mill Creek to the north towards Hamilton, where it joins the Great -Miami. The importance of Mill Creek Valley is readily seen in the fact -that the canal and the railroads have been able to avoid heavy grades -by following it from Cincinnati to Hamilton. As a glance at a map will -show, it is also practically but a continuation of the northerly course -pursued by the Ohio for twenty miles before reaching Cincinnati. This, -therefore, was a natural place in which to look beneath the extensive -glacial _débris_ for the buried channel of the ancient Ohio, and here -in all probability it has been found. The borings which have been made -in Milk Creek Valley north of Cincinnati, show that the bedded rock -lies certainly thirty-four feet below the low-water mark of the Ohio -just below Cincinnati, while at Hamilton, twenty-five miles north of -Cincinnati, where the valley of the Great Miami is reached, the bedded -rock of the valley lies as much as ninety feet below present low-water -mark in the Ohio. - -Other indications of the greater depth of the preglacial gorge of the -Ohio are abundant. "At the junction of the Anderson with the Ohio, in -Indiana, a well was sunk ninety-four feet below the level of the Ohio -before rock was found." At Louisville, Ky., the occurrence of falls -in the Ohio seemed at first to discredit the theory in question, but -Professor Newberry was able to show that the falls at Louisville are -produced by the water's being now compelled to flow over a rocky point -projecting from the north side into the old valley, while to the south -there is ample opportunity for an old channel to have passed around this -point underneath the city on the south side. The lowlands upon which the -city stands are made lands, where glacial _débris_ has filled up the old -channel of the Ohio. - -Above Cincinnati the tributaries of the Ohio exhibit the same phenomena. -At New Philadelphia, Tuscarawas County, the borings for salt-wells show -that the Tuscarawas is running 175 feet above its ancient bed. The -Beaver, at the junction of the Mahoning and Shenango, is flowing 150 feet -above the bottom of its old trough, as is demonstrated by a large number -of oil-wells bored in the vicinity. Oil Creek is shown by the same proofs -to run from 75 to 100 feet above its old channel, and that channel had -sometimes vertical and even overhanging walls.[CC] - -[Footnote CC: Geological Survey of Ohio, vol. ii, pp. 13, 14.] - -The course of preglacial drainage in the upper basin of the Alleghany -River is worthy of more particular mention. Mr. Carll, of the -Pennsylvania Geological Survey, has adduced plausible reasons for -believing that previous to the Glacial period the drainage of the -valley of the upper Alleghany north of the neighbourhood of Tidioute, -in Warren County, instead of passing southward as now, was collected -into one great stream flowing northward through the region of Cassadaga -Lake to enter the Lake Erie basin at Dunkirk, N. Y. The evidence is -that between Tidioute and Warren the present Alleghany is shallow, and -flows over a rocky basin; but from Warren northward along the valley -of the Conewango, the bottom of the old trough lies at a considerably -lower level, and slopes to the north. Borings show that in thirteen -miles the slope of the preglacial floor of Conewango Creek to the north -is 136 feet. The actual height above tide of the old valley floor at -Fentonville, where the Conewango crosses the New York line, is only 964 -feet; while that of the ancient rocky floor of the Alleghany at Great -Bend, a few miles south of Warren, was 1,170 feet. Again, going nearer -the head-waters of the Alleghany, in the neighbourhood of Salamanca, -it is found that the ancient floor of the Alleghany is, at Carrollton, -70 feet lower than the ancient bed of the present stream at Great -Bend, about sixty miles to the south; while at Cole's Spring, in the -neighbourhood of Steamburg, Cattaraugus County, N. Y., there has been -an accumulation of 315 feet of drift in a preglacial valley whose rocky -floor is 155 feet below the ancient rocky floor at Great Bend. Unless -there has been a great change in levels, there must, therefore, have -been some other outlet than the present for the waters collecting in the -drainage basin to the north of Great Bend.[CD] - -[Footnote CD: For a criticism of Mr. Carll's views, see an article -on Pleistocene Fluvial Planes of Western Pennsylvania, by Mr. Frank -Leverett, in American Journal of Science, vol. xlii, pp. 200-212.] - -While there are numerous superficial indications of buried channels -running towards Lake Erie in this region, direct exploration has not -been made to confirm these theoretical conclusions. In the opinion of Mr. -Carll, Chautauqua Lake did not flow directly to the north, but, passing -through a channel nearly coincident with that now occupied by it, joined -the northerly flowing stream a few miles northeast from Jamestown.[CE] It -is probable, however, that Chautauqua did not then exist as a lake, since -the length of preglacial time would have permitted its outlet to wear a -continuous channel of great depth corresponding to that known to have -existed in the Conewango and upper Alleghany. - -[Footnote CE: Second Geological Survey of Pennsylvania, vol. iii.] - -The foregoing are but a few of the innumerable instances where the local -lines of drainage have been disturbed, and even permanently changed, -by the glacial deposits. Almost every lake in the glaciated region is -a witness to this disturbance of the established lines of drainage by -glacial action, while in numerous places where lakes do not now exist -they have been so recently drained that their shore-lines are readily -discernible. - -An interesting instance of the recent disappearance of one of these -glacial lakes is that of Runaway Pond, in northern Vermont. In the early -part of the century the Lamoille River had its source in a small lake -in Craftsbury, Orleans County. The sources of the Missisquoi River were -upon the same level just to the north, and the owner of a mill privilege -upon this latter stream, desiring to increase his power by obtaining -access to the water of the lake, began digging a ditch to turn it into -the Missisquoi, but no sooner had he loosened the thin rim of compact -material which formed the bottom and the sides of the inclosure, than the -water began to rush out through the underlying and adjacent quicksands. -This almost instantly enlarged the channel, and drained the whole body of -water oft 3 in an incredibly short time. As a consequence, the torrent -went rushing down through the narrow valley, sweeping everything before -it; and nothing but the unsettled condition of the country prevented a -disaster like that which occurred in 1889 at Johnstown, Pa. Doubtless -there are many other lakes held in position by equally slender natural -embankments. Artificial reservoirs are by no means the only sources of -such danger. - -The buried channel of the old Mississippi River in the vicinity of -Minneapolis is another instructive example of the instability of many -of the present lines of drainage. The gorge of the Mississippi River -extending from Fort Snelling to the Falls of St. Anthony at Minneapolis -is of post-glacial origin. One evidence of this is its narrowness when -contrasted with the breadth of the valley below Fort Snelling. Below -this point the main trough of the Mississippi has a width of from two to -eight miles, and the faces of the bluffs on either side show the marks -of extreme age. The tributary streams also have had time to wear gorges -proportionate to that of the main stream, and the agencies which oxidise -and discolor the rocks have had time to produce their full effects. But -from Fort Snelling up to Minneapolis, a distance of about seven miles, -the gorge is scarcely a quarter of a mile in width, and the faces of -the high, steep bluffs on either side are remarkably fresh looking by -comparison with those below; while the tributary gorges, of which that of -the Minnehaha River is a fair specimen, are very limited in their extent. - -Upon looking for the cause of this condition of things we observe that -the broad trough of the Mississippi River, which had characterised it all -the way below Fort Snelling, continues westward, without interruption, up -the valley of the present Minnesota River, and, what seems at first most -singular, it does not cease at the sources of the Minnesota, but, through -Lake Traverse and Big Stone Lake, is continuous with the trough of the -Red River of the North. - -[Illustration: Fig. 53.--Map of Mississippi River from Fort Snelling to -Minneapolis and the vicinity, showing the extent of the recession of the -Falls of St. Anthony since the great Ice age. Notice the greater breadth -of the valley of the Minnesota River as described in the text (Winchell).] - -Deferring, however, for a little the explanation of this, we will go -back to finish the history of the preglacial channel around the Falls -of St. Anthony. As early as the year 1876 Professor N. H. Winchell had -collected sufficient evidence from wells, one of which had been sunk to a -depth of one hundred and seventy-five feet, to show that the preglacial -course of the stream corresponding to the present Mississippi River ran -to the west of Minneapolis and of the Falls of Minnehaha, and joined -the main valley some distance above Fort Snelling, as shown in the -accompanying map. - -This condition of things was at one time very painfully brought to the -notice of the citizens of Minneapolis. A large part of the wealth of the -city at that time consisted of the commercial value of the water-power -furnished by the Falls of St. Anthony. To facilitate the discharge of -the waste water from their wheels, some mill-owners dug a tunnel through -the soft sandstone underlying the limestone strata over which the river -falls; but it very soon became apparent that the erosion was proceeding -with such rapidity that in a few years the recession of the falls would -be carried back to the preglacial channel, when the river would soon -scour out the channel and destroy their present source of wealth. The -citizens rallied to protect their property, and spent altogether as -much as half a million dollars in filling up the holes that had been -thoughtlessly made; but so serious was the task that they were finally -compelled to appeal for aid to the United States Government. Permanent -protection was provided by running a tunnel, some ways back from the -falls, completely across the channel, through the soft sandstone -underlying the limestone, and filling this up with cement hard enough -and compact enough to prevent the further percolation of the water from -above. - - -_Ice-Dams._ - -The foregoing changes in lines of drainage due to the Glacial period were -produced by deposits of earthy material in preglacial channels. Another -class of temporary but equally interesting changes were produced by the -ice itself acting directly as a barrier. - -Many such lakes on a small scale are still in existence in various parts -of the world. The Merjelen See in Switzerland is a well-known instance. -This is a small body of water held back by the great Aletsch Glacier, -in a little valley leading to that of the Fiesch Glacier, behind the -Eggischorn. At irregular intervals the ice-barrier gives way, and allows -the water to rush out in a torrent and flood the valley below. Afterwards -the ice closes up again, and the water reaccumulates in preparation for -another flood. - -Other instances in the Alps are found in the Mattmark See, which fills -the portion of the Saas Valley between Monte Rosa and the Rhône. This -body of water is held in place by the Allalin Glacier, which here crosses -the main valley. The Lac du Combal is held back by the Glacier de Miage -at the southern base of Mont Blanc. "A more famous case is that of the -Gietroz Glacier in the valley of Bagnes, south of Martigny. In 1818 -this lake had grown to be a mile long, and was 700 feet wide and 200 -feet deep. An attempt was made to drain it by cutting through the ice, -and about half the water was slowly drawn off in this way; but then the -barrier broke, and the rest of the lake was emptied in half an hour, -causing a dreadful flood in the valley below. In the Tyrol, the Vernagt -Glacier has many times caused disastrous floods by its inability to hold -up the lake formed behind it. In the northwestern Himalaya, the upper -branches of the Indus are sometimes held back in this way. A noted flood -occurred in 1835; it advanced twenty-five miles in an hour, and was felt -three hundred miles down-stream, destroying all the villages on the lower -plain, and strewing the fields with stones, sand, and mud."[CF] - -[Footnote CF: Professor William M. Davis in. Proceedings of the Boston -Society of Natural History, vol. xxi, pp. 350, 351.] - -In Greenland such temporary obstructions are frequent, forming lakes of -considerable size. Instances occur, in connection with the Jakobshavn and -the Frederickshaab Glaciers, and in the North Isortok and Alangordlia -Fiords. - -Frequently, also, bodies of water of considerable size are found in -depressions of the ice itself, even at high levels. I have myself seen -them covering more than an acre, and as much as a thousand feet above -the sea-level, upon the surface of the Muir Glacier, Alaska. They are -reported by Mr. I. C. Russell[CG] of larger size and at still higher -elevations upon the glaciers radiating from Mount St. Elias; while the -explorers of Greenland mention them of impressive size upon the surface -of its continental ice-sheet. - -[Footnote CG: See National Geographic Magazine, vol. iii, pp. 116-120.] - -With these facts in mind we can the more readily enter into the -description which will now be given of some temporary lakes of vast size -which were formed by direct ice-obstructions during portions of the -period. - -One of the most interesting of these is illustrated upon the accompanying -map, which will need little description. - -[Illustration: Fig. 54.--Map showing the effect of the glacial dam at -Cincinnati (Claypole). (From Transactions of the Edinburgh Geological -Society.)] - -While tracing the boundary-line of the glaciated area in the Mississippi -Valley during the summer of 1882, I discovered the existence of -unmistakable glacial deposits in Boone County, Kentucky, across the Ohio -River, from Cincinnati.[CH]; These deposits were upon the height of land -550 feet above the Ohio River, or nearly 1,000 feet above the sea, which -is about the height of the water-shed between the Licking and Kentucky -Rivers. As the Ohio River occupies a trough of erosion some hundreds of -feet in depth, and extending all the way from this point to the mountains -of western Pennsylvania, it would follow that the ice which conveyed -boulders across the Ohio River at Cincinnati, and deposited them upon -the highlands between the Licking and Kentucky Rivers, would so obstruct -the channel of the Ohio as to pond the water back, and hold it up to -the level of the lowest pass into the Ohio River farther down. Direct -evidences of obstruction by glacial ice appear also for a distance of -fifty or sixty miles, extending both ways, from Cincinnati. - -[Footnote CH: The existence of portions of this evidence had previously -been pointed out by Mr. Robert B. Warder and Dr. George Sutton (see -Geological Reports of Indiana, 1872 and 1878).] - -The consequences connected with this state of things are of the most -interesting character. - -The bottom of the Ohio River at Cincinnati is 432 feet above the -sea-level. A dam of 550 feet would raise the water in its rear to a -height of 982 feet above tide. This would produce a long, narrow lake, -of the width of the eroded trough of the Ohio, submerging the site -of Pittsburg to a depth of 281 feet, and creating slack water up the -Monongahela nearly to Grafton, West Virginia, and up the Alleghany as far -as Oil City. All the tributaries of the Ohio would likewise be filled -to this level. The length of this slack-water lake in the main valley, -to its termination up either the Alleghany or the Monongahela, was not -far from one thousand miles. The conditions were also peculiar in this, -that all the northern tributaries rose within the southern margin of the -ice-front, which lay at varying distances to the north. Down these there -must have poured during the summer months immense torrents of water to -strand boulder-laden icebergs on the summits of such high hills as were -lower than the level of the dam. - -Naturally enough, this hypothesis of a glacial dam at Cincinnati aroused -considerable discussion, and led to some differences of opinion. -Professors I. C. White and J. P. Lesley, whose field work has made them -perfectly familiar with the upper Ohio and its tributaries, at once -supported the theory, with a great number of facts concerning certain -high-level terraces along the Alleghany and Monongahela Rivers; while -additional facts of the same character have been brought to light by -myself and others. In general, it may be said that in numerous places -terraces occur at a height so closely corresponding to that of the -supposed dam at Cincinnati, that they certainly strongly suggest direct -dependence upon it. The upward limit of these terraces in the Monongahela -River is 1,065 feet, and they are found in various places in situations -which indicate that they were formed in still water of such long standing -as would require an obstruction below of considerable permanence. - -One of the most decisive cases adduced by Professor White occurs near -Morgantown, in West Virginia, of which he gives the following description: - -"Owing to the considerable elevation--275 feet--of the fifth terrace -above the present river-bed in the vicinity of Morgantown, its deposits -are frequently found far inland from the Monongahela, on tributary -streams. A very extensive deposit of this kind occurs on a tributary one -mile and a half northeast of Morgantown; and the region, which includes -three or four square miles, is significantly known as the 'Flats.' The -elevation of the 'Flats' is 275 feet above the river, or 1,065 feet above -tide. The deposits on this area consist almost entirely of clays and -fine, sandy material, there being very few boulders intermingled. The -depth of the deposit is unknown, since a well sunk on the land of Mr. -Baker passed through alternate beds of clay, fine sand, and muddy trash, -to a depth of sixty-five feet without reaching bed-rock. In some portions -of the clays which make up this deposit, the leaves of our common -forest-trees are found most beautifully preserved. - -"At Clarksburg, where the river unites with Elk Creek, there is a wide -stretch of terrace deposits, and the upper limit is there about 1,050 -feet above tide, or only 130 feet above low-water (920 feet); while at -Weston, forty miles above (by the river), these deposits cease at seventy -feet above low water, which is there 985 feet above tide. It will thus -be observed that the upper limit of the deposits retains a practical -horizontality from Morgantown to Weston, a distance of one hundred miles, -since the upper limit has the same elevation above tide (1,045 to 1,065 -feet) at every locality. - -"These deposits consist of rounded boulders of sandstone, with a large -amount of clay, quicksand, and other detrital matter. The country rock -in this region consists of the soft shales and limestones of the upper -coal-measures, and hence there are many 'low gaps' from the head of one -little stream to that of another, especially along the immediate region -of the river; and in every case the summits of these divides, where they -do not exceed an elevation of 1,050 feet above tide, are covered with -transported or terrace material; but where the summits go more than a -few feet above that level we find no transported material upon them, but -simply the decomposed country rock." - -Other noteworthy terraces naturally attributable to the Cincinnati -ice-dam are to be found in the valley of the Kanawha, in West Virginia, -and one of special significance on the pass between the valleys of the -Ohio and Monongahela, west of Clarksburg, West Virginia. According to -Professor White, there is at this latter place "a broad, level summit, -having an elevation of 1,100 feet, in a gap about 300 feet below the -enclosing hills. This gap, or valley, is covered by a deposit of fine -clay. The cut through it is about thirty feet, and one can observe the -succession of clays of all kinds and of different colours, from yellow on -the surface down to the finest white potter's clay at the level of the -railway, where the cut reaches bed-rock, thus proving that the region has -been submerged."[CI] - -[Footnote CI: Bulletin of the Geological Society of America, vol. i, p. -478.] - -Another crucial case I have myself described at Bellevue, in the angle -of the Ohio and Alleghany Rivers, about five miles below Pittsburg, -where the gravel terrace is nearly 300 feet above the river, making it -about 1,000 feet above the sea. A significant circumstance connected -with this terrace is that not only does its height correspond with that -of the supposed obstruction at Cincinnati, but it contains many pebbles -of Canadian origin, which could not have got into the valley of the -Alleghany before the Glacial period, and could only have reached their -present position by being brought down the Alleghany River upon floating -ice, or by the ordinary movement of gravel along the margin of a river. -Thus this terrace, while corresponding closely with the elevation of -those on the Monongahela River, is directly connected with the Glacial -period, and furnishes a twofold argument for our theory. - -A still stronger case occurs at Beech Flats, at the head of Ohio -Brush Creek, in the northwest corner of Pike County, Ohio, where, at -an elevation of about 950 feet above the sea, there is an extensive -flat-topped terrace just in front of the terminal moraine. This terrace -consists of fine loam, such as is derived from the glacial streams, but -which must have been deposited in still water. The occurrence of still -water at that elevation just in front of the continental ice-sheet is -best accounted for by the supposed dam at Cincinnati. Indeed, it is -extremely difficult to account for it in any other way. - -There are, however, two other methods of attempting to account for the -class of facts above cited in support of the ice-dam theory, of which the -most plausible is, that in connection with the Glacial period there was -a subsidence of the whole region to an extent of 1,100 feet. - -The principal objection heretofore alleged against this supposition is -that there are not corresponding signs of still-water action at the same -level on the other side of the Alleghany Mountains. This will certainly -be fatal to the subsidence theory, if it proves true. But it is possible -that sufficient search for such marks has not yet been made on the -eastern side of the mountains. - -The other theory to account for the facts is, that the terraces adduced -in proof of the Cincinnati ice-dam were left by the streams in the slow -process of lowering their beds from their former high levels. This is -the view advocated by President T. C. Chamberlin. But the freshness -of the leaves and fragments of wood, such as were noted by Professor -White at Morgantown, and the great extent of fine silt occasionally -resting upon the summits of the water-sheds, as described above, near -Clarksburg, bear strongly against it. Furthermore, to account for the -terrace described at Bellevue, which contains Canadian pebbles, President -Chamberlin is compelled to connect the deposit with his hypothetical -first Glacial epoch, and to assume that all the erosion of the Alleghany -and Monongahela Rivers, and indeed of the whole trough of the Ohio River, -took place in the interval between the "first" and the "second" Glacial -periods (for he would connect the glacial deposits upon the south side of -the river at Cincinnati with the first Glacial epoch)--all of which, it -would seem, is an unnecessary demand upon the forces of Nature, when the -facts are so easily accounted for by the simple supposition of the dam at -Cincinnati.[CJ] - -[Footnote CJ: See matter discussed more at length in the lee Age, pp. -326-350, 480-500; Bulletin of the United States Geological Survey, No. -58, pp. 76-100; Popular Science Monthly, vol. xlv, pp. 184-199. _Per -contra_, Mr. Frank Leverett, in American Geologist, vol. x, pp. 18-24.] - -[Illustration: Fig. 55.--Map showing the condition of things when the -ice-front had withdrawn about on hundred and twenty miles, and while -it still filled the valley of the Mohawk. The outlet was then through -the Wabash. Niagara was not yet born (Claypole). (Transactions of the -Edinburgh Geological Society.)] - -We have already described[CK] the various temporary lakes and lines of -drainage caused by the direct obstruction of the northward outlets to -the basin of the Great Lakes. In connection with the map, it will be -unnecessary to do anything more here than add a list of such temporary -southern outlets from the Erie-Ontario basin.[CL] The first is at Fort -Wayne, Indiana, through a valley connecting the Maumee River basin with -that of the Wabash. The channel here is well defined, and the high-level -gravel terraces down the Wabash River are a marked characteristic of the -valley. The elevation of this col above the sea is 740 feet. Similar -temporary lines of drainage existed from the St. Mary's River to the -Great Miami, at an elevation of 942 feet; from the Sandusky River to -the Scioto, through the Tymochtee Gap, at an elevation of 912 feet; -from Black River to the Killbuck (a tributary of the Muskingum) through -the Harrisville Gap, at 911 feet; from the Cuyahoga into the Tuscarawas -Valley, through the Akron Gap, at 971 feet; from Grand River into the -Mahoning, through the Orwell Gap, 938 feet; from Cattaraugus Creek, N. -Y., into the Alleghany Valley through the Dayton Gap, about 1,300 feet; -between Conneaut Creek and Shenango River, at Summit Station, 1,141 feet; -from the Genesee River, N. Y., into the head-waters of the Canisteo, a -branch of the Susquehanna, at Portageville, 1,314 feet; from Seneca Lake -to Chemung River, at Horseheads, 879 feet; from Cayuga Lake to the valley -of Cayuga Creek, at Spencer, N. Y., 1,000 feet; from Utica, N. Y., into -the Chenango Valley at Hamilton, about 900 feet. - -[Footnote CK: See pp. 92 seq., 199 _seq._] - -[Footnote CL: See also accompanying map.] - -[Illustration: Fig. 56.--Map illustrating a stage in the recession of the -ice in Ohio. For a section of the deposit in the bed of this lakelet, see -page 200. The gravel deposits formed at this stage along the outlet into -the Tuscarawas River are very clearly marked (Claypole). (Transactions of -the Edinburgh Geological Society.)] - -Perhaps it would have been best to give this list in the reverse order, -which would be more nearly chronological, since it is clear that the -highest outlets are the oldest. We should then have to mention, after the -Fort Wayne outlet, two others at lower levels which are pretty certainly -marked by distinct beach ridges upon the south side of Lake Erie. The -first was opened when the ice had melted back from the south peninsula of -Michigan to the water-shed across from the Shiawassee and Grand Rivers, -uncovering a pass which is now 729 feet above the sea. This continued to -be the outlet of Lake Erie-Ontario until the ice had further retreated -beyond the Strait of Mackinac, when the water would fall to the level of -the old outlet from Lake Michigan into the Illinois River, which is a -little less than 600 feet, where it would remain until the final opening -of the Mohawk River in New York attracted the water in that direction, -and lowered the level to that of the pass from Lake Ontario to the Mohawk -at Rome.[CM] - -[Footnote CM: Mr. Warren Upham, in the Bulletin of the Geological Society -of America, vol. ii, p. 259.] - -A study of these lines of temporary drainage during the Glacial period -sheds much light upon the long lines of gravel ridges running parallel -with the shores of Lake Erie and Lake Ontario. South of Lake Erie a -series of four ridges of different elevations can be traced. In Lorain -County, Ohio, the highest of these is 220 feet above the lake; the next -160 feet; the next 118 feet; and the lower one 100 feet, which would make -them respectively 795, 755, 715, and 700 feet above tide. - -These gravel ridges are evidently old beach lines, and indicate the -different levels up to which the water was held by ice-obstructions -across the various outlets of the drainage valley. The material in the -ridges is water-worn and well assorted, and in coarseness ranges from -fine sand up to pebbles several inches in diameter. The predominant -material in them is of local origin. Where the rocks over which they run -are sandstone, the material is chiefly sand, and where the outcropping -rock is shale, the ridges consist chiefly of the harder nodules of that -formation which have successfully resisted the attrition of the waves. -Ordinarily these ridges are steepest upon the side facing the lake. -According to Mr. Upham, who has driven over them with me, the Lake Erie -ridges correspond, both in general appearance and in all other important -respects, to those which he has so carefully surveyed around the shores -of the ancient Lake Agassiz in Minnesota and Manitoba, an account of -which will be given a little farther on in this chapter. - -[Illustration: Fig. 57.--Section of the lake ridges near Sandusky, Ohio.] - -We are not permitted, however, to assume that there have been no changes -of level since the deposition of these beaches surrounding the ancient -glacial Lake Erie-Ontario. On the contrary, there appears to have been -a considerable elevation towards the east and northeast in post-glacial -times. The highest ridge south of Lake Erie, which at Fort Wayne is about -780 feet high, is now about 795 feet in Lorain County. The second of the -ridges above-mentioned, which is about 740 feet above tide at Cleveland, -Ohio, rises to 870 feet where the last traces of it have been discovered -at Hamburg, N. Y. The third ridge, which is 673 feet at Cleveland, has -risen to the height of 860 feet at Crittenden, about one hundred miles to -the east of Buffalo, N. Y. - -A similar eastern increase of elevation is discoverable in the main ridge -surrounding Lake Ontario. What Professor Spencer calls the Iroquois -beach, which is 363 feet above tide at Hamilton, Ontario, has risen to a -height of 484 feet near Syracuse, N. Y.; while farther to the northeast, -in the vicinity of Watertown, it is upwards of 800 feet above tide. - -There is also a similar northward increase of elevation in the beaches -surrounding the higher lands of Ontario eastward of Lake Huron and -Georgian Bay. - -All this indicates that at the close of the Glacial period there -was a subsidence of several hundred feet in the area of greatest -ice-accumulation lying to the east and north of the Great Lake region. -The formation of these ridges occurred during that period of subsidence. -The re-elevation which followed the disappearance of the ice of course -carried with it these ridges, and brought them to their present -position.[CN] - -[Footnote CN: See Spencer, in Bulletin of the Geological Society of -America, vol. ii, pp. 465-476.] - -In returning to consider more particularly the remarkable gorge joining -the Minnesota with the Red River of the North, we are brought to the -largest of the glacial lakes of this class, and to the typical place in -America in which to study the temporary changes of drainage produced by -the ice itself daring the periods both of its advance and of its retreat. - -[Illustration: Fig. 58.--Map showing the stages of recession of the ice -in Minnesota as described in the text (Upham).] - -By turning to our general map of the glaciated region of the United -States,[CO] one can readily see the relation of the valley between -Lake Traverse and Big Stone Lake to an area marked as the bed of what -is called Lake Agassiz. During the Glacial period Brown's Valley, the -depression joining these two lakes, was the outlet of an immense body of -water to the north, whose natural drainage was towards Hudson Bay or the -Arctic Ocean, but which was cut off, by the advancing ice, from access to -the ocean-level in that direction, and was compelled to seek an exit to -the south. - -[Footnote CO: See page 66.] - -Thus for a long period the present Minnesota River Valley was occupied -by a stream of enormous dimensions, and this accounts for the great -size of the trough--the present Minnesota being but an insignificant -stream winding about in this deserted channel of the old "Father of -Waters," and having as much room as a child of tender age would have in -his parent's cast-off garments. This glacial stream has been fittingly -named River Warren, after General Warren, who first suggested and proved -its existence, and so we have designated it on the accompanying map of -Minnesota. - -Lake Traverse is fifteen miles long, and the water is nowhere more than -twenty feet deep. Big Stone Lake is twenty-six miles long, and of about -the same depth. Brown's Valley, which connects the two, is five miles -long, and the lakes are so nearly on a level that during floods the water -from Lake Traverse sometimes overflows and runs to the south as well as -to the north. - -[Illustration: Fig. 59.--Glacial terrace near the boundary of the -glaciated area, on Raccoon Creek, a tributary of the Licking River, in -Granville, Licking County, Ohio. Height about fifty feet.] - -The trough occupied by these lakes and valley is from one mile to one -mile and a half in width and about 120 feet in depth. If we had been -permitted to stand upon the bluffs overlooking it during the latter -part of the Glacial period, we should have seen the whole drainage of -the north passing by our feet on its way to the Gulf of Mexico. As lie -follows down the valley of the Minnesota River, the observant traveller, -even now, cannot fail to see in the numerous well-preserved gravel -terraces the high-water marks of that stream when flooded with the joint -product of the annual precipitation over the vast area to the north, and -of the still more enormous quantities set free by the melting of the -western part of the great Laurentide Glacier. - -Numerous other deserted water-ways in the northwestern part of the -valley of the Mississippi have been brought to light in the more -recent geological surveys, both in the United States and in Canada. -During a considerable portion of the Glacial period the Saskatchewan, -the Assiniboine, the Pembina, and the Cheyenne Rivers, whose present -drainage is into the Red River of the North, were all turned to the -south, and their temporary channels can be distinctly traced by deserted -water-courses marked by lines of gravel deposits.[CP] - -[Footnote CP: For further particulars, see Ice Age, pp. 293 _et seq._] - -In Dakota, Professor J. E. Todd has discovered large deserted channels -on the southwestern border of the glaciated region near the Missouri -River, where evidently streams must have flowed for a long distance in -ice-channels when the ice still continued to occupy the valley of the -James River. From these channels of ice in which the water was held up -to the level of the Missouri Coteau the water debouched directly into -channels with sides and bottom of earthy material, which still show every -mark of their former occupation by great streams.[CQ] - -[Footnote CQ: For particulars, see Ice Age, p. 292.] - -In Minnesota, also, there is abundant evidence that while the -northeastern part of the valley from Mankato to St. Paul was occupied by -ice, the drainage was temporarily turned directly southward across the -country through Union Slough and Blue Earth River into the head-waters of -the Des Moines River in Iowa. - - -_Ancient River Terraces._ - -The interest of the whole inquiry respecting the relation of man to -the Glacial period in America concentrates upon these temporary lines -of southern drainage. Wherever they existed, the swollen floods of the -Glacial period have left their permanent marks in the deposition of -extensive gravel terraces. The material thus distributed is derived -largely from the glacial deposits through which they run and out of which -they emerge. While the height of the terraces depended upon various -conditions which must be studied in detail, in general it may be said -that it corresponds pretty closely with the extent of the area whose -drainage was turned through the channel during the prevalence of the ice. -The height of the terraces and the coarseness of the material seem also -to have been somewhat dependent upon the proximity of their valleys to -the areas of most vigorous ice-action, and this, in turn, seems to lie in -the rear of the moraines which President Chamberlin has attributed to the -second Glacial epoch. Southward from this belt of moraines the terraces -uniformly and gradually diminish both in height and in the coarseness of -their gravel, until they finally disappear in the present flood-plain of -the Mississippi River. - -[Illustration: Fig. 60.--Ideal section across a river-bed in drift -region: _b b b_, old river-bed; _R_, the present river; _t t_, upper or -older terraces; _t' t'_, lower terraces.] - -An interesting illustration of this principle is to be observed in the -continuous valley of the Alleghany and Ohio Rivers. The trough of this -valley was reached by the continental glacier at only a few points, -the ice barely touching it at Salamanca, N. Y., Franklin, Pa., and -Cincinnati, Ohio. But throughout its whole length the ice-front was -approximately parallel to the valley, and occupied the head-waters of -nearly all its tributaries. Now, wherever tributaries which could be fed -by glacial floods, enter the trough of the main stream, they brought down -an excessive amount of gravel, and greatly increased the size of the -terrace in the trough itself, and from the mouth of each such tributary -to that of the next one below there is a gradual decrease in the height -of the terrace and in the coarseness of the material. - -This law is illustrated with special clearness in Pennsylvania between -Franklin and Beaver. Franklin is upon the Alleghany River, at the last -point where it was reached directly by the ice. Below this point no -tributary reaches it from the glaciated region, and none such reaches the -Ohio after its junction with the Alleghany until we come to the mouth of -Beaver Creek, about twenty-five miles below Pittsburg. - -But at this point the Ohio is joined by a line of drainage which emerges -from the glaciated area only ten or twelve miles to the north, and whose -branches occupy an exceptionally large glaciated area. Accordingly, there -is at Beaver a remarkable increase in the size of the glacial terrace -on the Ohio. In the angle down-stream between the Beaver and the Ohio -there is an enormous accumulation of granitic pebbles, many of them -almost large enough to be called boulders, forming the delta terrace, -upon which the city is built and rising to a height of 135 feet above -the low-water mark in the Ohio. In striking confirmation of our theory, -also, the terrace in the Ohio Valley upon the upper side of Beaver Creek -is composed of fine material, largely derived from local rocks and -containing but few granitic pebbles. - -From the mouth of Beaver Creek, down the Ohio, the terrace is constant -(sometimes upon one side of the river and sometimes upon the other), -but, according to rule, the material of which it is composed gradually -grows finer, and the elevation of the terrace decreases. According to -rule, also, there is a notable increase in the height of the terrace -below each affluent which enters the river from the glaciated region. -This is specially noticeable below Marietta, at the mouth of the -Muskingum, whose head-waters drain an extensive portion of the glaciated -area. From the mouth of the Little Beaver to this point the tributaries -of the Ohio are all small, and none of them rise within the glacial -limit. Hence they could contribute nothing of the granitic material which -enters so largely into the formation of the river terrace; but below the -mouth of the Muskingum the terrace suddenly ascends to a height of nearly -one hundred feet above low-water mark. - -Again, at the mouth of the Scioto at Portsmouth, there is a marked -increase in the size of the terrace, which is readily accounted for by -the floods which came down the Scioto Valley from the glaciated region. -The next marked increase is at Cincinnati, just below the mouth of the -Little Miami, whose whole course lay in the glaciated region, and whose -margin is lined by very pronounced terraces. At Cincinnati the upper -terrace upon which the city is built is 120 feet above the flood-plain. - -Twenty-five miles farther down the river, near Lawrenceburg, these -glacial terraces are even more extensive, the valley being there between -three and four miles wide, and being nearly filled with gravel deposits -to a height of 112 feet above the flood-plain. Below this point the -terraces gradually diminish in height, and the material becomes finer -and more water-worn, until it merges at last in the flood-plain of the -Mississippi. The course of the Wabash River is too long to permit it to -add materially to the size of the terraces which characterise the broader -valley of the Ohio below the Illinois line. - -It is in terraces such as these just described that we find the imbedded -relics of man which definitely connect him with the great Ice age. These -have now been found in the glacial terraces of the Delaware River at -Trenton, N. J.; in similar terraces in the valley of the Tuscarawas River -at New Comerstown, and in the valley of the Little Miami at Loveland and -Madisonville, in Ohio; on the East Fork of White River, at Medora, Ind.; -and still, again, at Little Falls, in the trough of the Mississippi, some -distance above Minneapolis, Minn. - -I append a list of the points at which various streams from the Atlantic -Ocean to the Mississippi River emerge from the glacial boundary, and -below which the terraces are specially prominent. Of course, with the -retreat of the ice, the formation of the terraces continued northward -in the glaciated area to a greater or less distance, according to the -extent of the valley or to the length of time during which the drainage -was temporarily turned into it. These points of emergence are: In the -Delaware Valley, at Belvidere, N. J.; in the Susquehanna, at Beach Haven, -Pa.; in the Conewango, at Ackley, Warren County; in Oil Creek, above -Titusville: in French Creek, a little above Franklin; in Beaver Creek, -at Chewtown, Lawrence County; on the Middle Fork of Little Beaver, near -New Lisbon, Ohio; on the east branch of Sandy Creek, at East Rochester, -Columbiana County; on the Nimishillin, at Canton, Stark County; on the -Tuscarawas, at Bolivar; on Sugar Creek, at Beech City; on the Killbuck, -at Millersburg, Holmes County; on the Mohican, near the northeast corner -of Knox County; on the Licking River, at Newark; on Jonathan Creek, Perry -County; on the Hocking, at Lancaster; on the Scioto, at Hopetown, just -above Chillicothe; on Paint Creek, and its various tributaries, between -Chillicothe and Bainbridge; and on the Wabash, above New Harmony, Ind.; -to which may be added the Ohio River itself, at its junction with the -Miami, near Lawrenceburg. - -Another class of terraces having most interesting connection with the -Glacial period is found in the arid basins west of the Rocky Mountains. -Over wide areas in Utah and Nevada the evaporation now just balances -the precipitation, and all the streams disappear in shallow bodies of -salt water of moderate dimensions, of which Great Salt Lake in Utah, and -Mono, Pyramid, and North Carson Lakes in Nevada, are the most familiar -examples. These occupy the lowest sinks of enclosed basins of great depth. - -But there is abundant evidence that in consequence of the increased -precipitation and diminished evaporation of the Glacial period one of -these basins was filled to the brim and the other to a depth of several -hundred feet. These former enlargements have been named after the first -explorers of the region, Captains Lahontan and Bonneville, and are shown -on the accompanying sketch map by the shading surrounding the existing -lakes. - -Lake Lahontan has been carefully studied by Mr. I. C. Russell, and has -been found to extend from the boundary of Oregon to latitude 38° 30' -south, a distance of two hundred and sixty miles. The Central Pacific -Railroad runs through its dried-up bed from Golconda to Wadsworth, a -distance of one hundred and sixty-five miles. The terraces of the former -lake are distinctly traceable at a height of 700 feet above the present -level of Lake Mono. - -Lake Bonneville, whose present representative is Great Salt Lake, is the -subject of a recent monograph by Mr. G. K. Gilbert, from which it appears -that this ancient body of water occupied 19,750 square miles--an area -about ten times that of the present lake. At the time of its maximum -extension its depth was 1,000 feet, while Great Salt Lake ranges only -from fifteen to fifty feet in depth. - -The pass through which the discharge finally took place is at Red Rock, -on the Utah and Northern Railroad, at the head of Cache Valley on the -south and the lower part of Marsh Creek Valley on the north. During -the long period preceding and accompanying the gradual rise of water in -the Utah basin to the level of the highest terrace, Marsh Creek (the -upper portion of which comes from the mountains on the east and turns -at right angles) had been at work depositing a delta of loose material -in the col which separates the two valleys. This deposit rested upon -a stratum of limestone at the bottom of the pass, and covered it with -sand, clay, and gravel to a depth of 375 feet. Thus, when the water was -approaching its upper level, the only barrier to prevent its escape was -this unstable accumulation of loose material upon top of the rock. It -would have required, therefore, no prophet's eye to predict that the way -was preparing for a tremendous _débâcle_. - -[Illustration: Fig. 61.--Map of the Quaternary Lakes. Bonneville and -Lahontan (after Gilbert and Russell).] - -The critical point at length was reached. After remaining nearly at -the elevation of the pass for a considerable period, during which the -1,000-foot shore-line was formed, the crisis came when the water began -to flow northward towards Snake River. Once begun in such loose material, -the channel rapidly enlarged until soon a stream equal to Niagara, and -at times probably much larger, was pouring northward through the valley -heretofore occupied by the insignificant rivulets of Marsh Creek and -the Port Neuf. It is impossible to tell how rapidly the loose barrier -wore away, but there is abundant evidence in the valley below that not -only the present channel of the lower part of Marsh Creek, but the whole -bottom of the valley for a mile or more in width, was for a considerable -time covered by a rapid stream from ten to twenty feet in depth, and -descending at the rate of thirteen feet to the mile. - -The continuance of this flood was dependent upon the amount of water to -be discharged, which, as we have seen, was that contained in an area of -20,000 square miles, with a depth of 375 feet. A stream of the size of -Niagara would occupy about twenty-five years in the discharge of such a -mass, and this may fairly be taken as a measure of the time through which -it lasted. When the loose material lying above the strata of limestone -in Red Rock Pass had been washed away, the lake then continued at that -level for an indefinite period, with an overflow regulated by the annual -precipitation of the drainage basin. This stage of the lake, during which -it occupied 13,000 square miles and was 625 feet above its present level, -is also marked by an extensive and persistent shore-line all around -the basin. But, finally, the balance again turned when the evaporation -exceeded the precipitation, and the vast body of water has since dwindled -to its present insignificant dimensions. - -My own interest in this discovery of Mr. Gilbert is enhanced by the -explanation it gives of a phenomenon in the Snake River Valley which I -was unable to solve when on the ground in 1890. The present railroad -town of Pocatello is situated just where this flood emerged from the -narrower valley of Marsh Creek and the Port Neuf, and spread itself out -upon the broad plain of the Snake River basin. The southern edge of the -plain upon which the city is built is a vast boulder-bed covered with a -thin stratum of sand and gravel. Everywhere, in sinking wells and digging -ditches on the vacant lots and in the streets of the city, water-worn -boulders of a great variety of material and sometimes three or four feet -in diameter are encountered. I was debarred from regarding this as a -terminal moraine, both by the water-worn character of the boulders and by -the absence of any sign of ice-action in the surrounding mountains, and I -was equally debarred from attributing it to any ordinary stream of water, -both by the size of the boulders and the fact that for a mile or more up -the Port Neuf Valley there is an intervale, forty or fifty feet below the -surface at Pocatello, and occupying the whole width of the valley, in -which there is only gravel and fine sand, through which the present Port -Neuf pursues a meandering course. The upper end of this short intervale -is bounded by the terminus of a basaltic stream which had flowed down the -valley and filled it to a considerable depth, but had subsequently been -much eroded by violent water-action. - -In the light of Mr. Gilbert's discoveries, however, everything is clear. -The tremendous _débâcle_ which he has brought within the range of -scientific vision would naturally produce just the condition of things -which is so puzzling at Pocatello. Coming down through the restricted -channel with sufficient force to roll along boulders of great size and -to clear them all out from the upper portion of the valley, the torrent -would naturally deposit them where the current was first checked, a mile -below the lava cliffs. The plunge of the water over these cliffs would -keep a short space below clear from boulders, and the more moderate -stream of subsequent times would fill in the depression with the sand -and gravel now occupying it. - -What other effects of this remarkable outburst may be traced farther down -in the Snake River Valley I cannot say, but it will be surprising if -they do not come to light and help to solve some of the many geological -problems yet awaiting us in this interesting region. - -It should have been said that during the formation of the 625-foot, or -so-called Provo shore-line, glaciers descended from the cañons on the -west flank of the Wahsatch Mountains, and left terminal moraines to mark -the coincidence of the Glacial period with that stage of the enlargement -of the lake. Evidences of a similar coincidence are to be found on the -high-level terraces surrounding Lake Mono, to which glaciers formerly -descended from the western flanks of the Sierra Nevada. - -The ancient shore-lines surrounding Lakes Bonneville and Lahontan bear -evidence also of various other episodes in the Glacial period. Evidently -there were two periods of marked increase in the size of the lakes, with -an arid period intervening. During the first rise the level of Bonneville -attained to within ninety feet of the second, and numerous beaches were -formed, and a large amount of yellow clay deposited. Then it seems -to have been wholly evaporated, while its soluble mineral matter was -precipitated, and so mingled with silt that it did not readily redissolve -during the second great rise of water. Partly on this account, and partly -through the influence of the outlet into the Snake River, the lake was -nearly fresh during its second enlargement. - - -_European Facts._ - -In Chapter VI it came in place to mention many of the facts connected -with the influence of the Glacial period upon the drainage systems -of Europe. We there discussed briefly the probable influence of the -ice-obstructions that extended across the mouths of the Dwina, the -Vistula, the Oder, the Elbe, the Weser, and the Rhine. The drainage of -the obstructed rivers in Russia was perhaps turned southward into the -Caspian and Black Seas, and then assisted in forming the fertile soil of -the plains in the southern part of that empire. - -The obstructed drainage of the German rivers was probably turned westward -in front of the ice through the Straits of Dover or across the southern -part of England. This was during the climax of the Glacial period; but -later, according to Dawkins, during a period in which the land of the -British Isles stood about 600 feet above its present level, the streams -of the eastern coast--namely, "the Thames, Medway, Humber, Tyne, and -others, joined the Rhine, the Weser, and the Elbe, to form a river -flowing through the valley of the ocean. In like manner, the rivers of -the south of England and of the north of France formed a great river -flowing past the Channel Islands due west into the Atlantic, and the -Severn united with the rivers of the south of Ireland; while those to the -east of Ireland joined the Dee, Mersey Ribble, and Lune, as well as those -of western Scotland, ultimately reaching the Atlantic to the west of the -Hebrides. The water-shed between the valleys of the British Channel and -the North Sea is represented by a ridge passing due south from Folkestone -to Dieppe, and that between the drainage area and the Severn and its -tributaries on the one hand, and of the Irish Channel on the other, by a -ridge from Holyhead westward to Dublin. - -"This tract of low, undulating land which surrounded Britain and Ireland -on every side consisted not merely of rich hill, valley, and plain, but -also of marsh-land studded with lakes, like the meres of Norfolk, now -indicated by the deeper soundings. These lakes were very numerous to the -south of the Isle of Wight and off the coast of Norfolk and Suffolk."[CR] - -[Footnote CR: Early Man in Britain, p. 151.] - -The evidence first regarded by scientific men to be demonstrative of the -formation of extensive lakes during the Glacial period by the direct -influence of ice-dams exists in the Parallel Roads of Glen Roy in -Scotland. - -[Illustration: Fig. 62.--Parallel roads of Glen Roy.] - -According to the description of Sir Charles Lyell, "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 nearly -its whole length, a distance of more than ten miles, three parallel -roads or shelves are traced along the steep sides of the mountains, 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 ten -to sixty feet broad, and merely differ from the side of the mountain by -being somewhat less steep. - -"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 immediately above the parallel -roads. The lowest of these roads is about 850 feet above the level of the -sea, and the next about 212 feet higher, and the third 82 feet above the -second. There is a fourth shelf, which occurs only in a contiguous valley -called Glen Gluoy, which is twelve feet above the highest of all the Glen -Roy roads, and consequently about 1,156 feet above the level of the sea. -One only, the lowest of the three roads of Glen Roy, is continued through -Glen Spean, a large valley with which Glen Roy unites. As the shelves, -having no slope towards the sea like ordinary river terraces, are always -at the same absolute height, 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, or any change either -in the shape of the ground or in the composition or hardness of the -rocks."[CS] - -[Footnote CS: Antiquity of Man, pp. 252, 253.] - -Early in his career Charles Darwin studied these ancient beaches, and -ascribed them to the action of the sea during a period of continental -subsidence. In this view he was supported by the majority of geologists -until the region was visited by Agassiz, who saw at once the true -explanation. If these were really sea-beaches, similar deposits should -be found at the same elevation on other mountains than those surrounding -Glen Roy. Their absence elsewhere points, therefore, to some local cause, -which was readily suggested to the trained eye of one like Agassiz, then -fresh from the study of Alpine glaciers, who saw that these beaches were -formed upon the margin of temporary lakes, held back during the Glacial -period (as the Merjelen See now is) by a glacier which came out of one -glen and projected itself directly across the course of another, and thus -obstructed its drainage. The glacier of Glen Spean had pushed itself -across Glen Roy, as the great Aletsch Glacier in Switzerland now pushes -itself across the little valley behind the Eggishorn. - - - - -CHAPTER VIII. - -RELICS OF MAN IN THE GLACIAL PERIOD. - - -_In Glacial Terraces of the United States._ - -Although the first clear evidence of glacial man was discovered in -Europe, the problem is so much simpler on the Western Continent that -we shall find it profitable to study the American facts first. We will -therefore present a summary of them at once, and then proceed to the more -obscure problems of European archæology. - -The first definite discovery of human relics clearly connected with, -glacial deposits in America, and of the same age with them, was made -by Dr. C. C. Abbott, at Trenton, N. J., in the year 1875. The city of -Trenton is built upon a delta terrace about three miles wide which -occurs at the head of tide-water on the Delaware River. This terrace -bears every mark of having been deposited by a torrential stream which -came down the valley during the closing period of the great Ice age. The -material of which the terrace consists is all water-worn. According to -the description of Professor N. S. Shaler: - -[Illustration: Fig. 63.--The glaciated portion is shaded. The shading -on the Lehigh and Delaware Rivers indicates glacial terraces, which are -absent from the Schuylkill.] - -"The general structure of the mass is neither that of ordinary -boulder-clay nor of stratified gravels, such as are formed by the -complete rearrangement by water of the elements of simple drift-deposits. -It is made up of boulders, pebbles, and sand, varying in size from masses -containing one hundred cubic feet or more to the finest sand of the -ordinary sea-beaches. There is little trace of true clay in the deposit; -there is rarely enough to give the least trace of cementation to the -masses. The various elements are rather confusedly arranged; the large -boulders not being grouped on any particular level, and their major -axes not always distinctly coinciding with the horizon. All the pebbles -and boulders, so far as observed, are smooth and water-worn, a careful -search having failed to show evidence of distinct glacial scratching -or polishing on their surfaces. The type of pebble is the subovate or -discoidal, and though many depart from this form, yet nearly all observed -by me had been worn so as to show that their shape had been determined by -running water. The materials comprising the deposit are very varied, but -all I observed could apparently with reason be supposed to have come from -the extensive valley of the river near which they lie, except perhaps the -fragments of some rather rare hypogene rocks." - -[Illustration: Fig. 64.--Palæolith found by Abbott in New Jersey, -slightly reduced.] - -A conclusive proof of the relation of this Trenton delta terrace to the -Glacial period is found in the fact that the gravel deposit is continuous -with terraces extending up the trough of the valley of the Delaware to -the glaciated area and beyond. As, however, the descent of the river-bed -is rapid (about four feet to the mile) from the glacial border down to -tide-water, the terrace is not remarkably high, being only about fifteen -or twenty feet above the present flood-plain. But it is continuous, -and similar in composition with the great enlargement in the delta at -Trenton. Without doubt, therefore, the deposit represents the overwash -gravel of the Glacial period. - -Fortunately for science, Dr. C. C. Abbott, whose tastes for archæological -investigations were early developed, had his residence upon the border -of this glacial delta terrace at Trenton, and as early as 1875 began -to find rough-stone implements of a peculiar type in the talus of -the bank where the river was undermining the terrace. In turning his -attention to the numerous fresh exposures of gravel made by railroad and -other excavations during the following year, he found several of the -implements in undisturbed strata, some of which were sixteen feet below -the surface. Since that time he has continued to make discoveries at -various intervals. In 1888 he had found four hundred implements of the -palæolithic type at Trenton, sixty of which had been taken from recorded -depths in the gravel, two hundred and fifty from the talus at the bluff -facing the river, and the remainder from the surface, or derived from -collectors who did not record the positions or circumstances under which -they were found. - -[Illustration: Fig. 65.--Section across the Delaware River at Trenton. -New Jersey: _a_, _a_, Philadelphia red gravel and brick-clay (McGee's -Columbia deposit); _b_. _b_, Trenton gravel, in which the implements are -found: _c_, present flood-plain of the Delaware River (after Lewis). -(From Abbott's Primitive Industry.)] - -The material from which the implements at Trenton are made is -argillite--that is, a clay slate which has been so metamorphosed as to -be susceptible of fracture, almost like flint. It is, however, by no -means capable of being worked into such delicate forms as flint is. But -as it is the only material in the vicinity capable of being chipped, -prehistoric men of that vicinity were compelled to make a virtue of -necessity and use the inferior material. Of all the implements found by -Dr. Abbott in the gravel, only one was flint; while upon the surface -innumerable arrow-heads of flint have been found. The transition, also, -in the type of implements is as sudden as that in the kind of material -of which they are made. Below the superficial deposit of black soil, -extending down to the depth of about one foot, the modern Indian flint -implements entirely disappear, and implements of palæolithic type only -are found. - -[Illustration: Fig. 66.--Section of the Trenton gravel in which the -implements described in the text are found. The shelf on which the man -stands is made in process of excavation. The gravel is the same above and -below (photograph by Abbott).] - -[Illustration: Fig. 67.--Face view of argillite implement, found by Dr. -C. C. Abbott, in 1876, at Trenton, New Jersey, in gravel, three feet -from face of bluff, and twenty-two feet from the surface (No. 10,985) -(Putnam).] - -In the year 1882, after I had traced the glacial boundary westward from -the Delaware River, across the States of Pennsylvania, Ohio, and Indiana, -I was struck with the similarity between the terrace at Trenton and -numerous terraces which I had attributed to the Glacial age in Ohio and -the other States. It adds much to the interest of subsequent discoveries -to note that in 1884, in my report to the Western Reserve Historical -Society upon the glacial boundary of Ohio, I wrote as follows: - -[Illustration: Fig. 68.--Argillite implement found by Dr. C. C Abbott, -March, 1879, at A. K. Rowan's farm, Trenton, New Jersey, in gravel -sixteen feet from surface: a, face view; b, side view (No. 11,286) -(Putnam).] - -"The gravel in which they [Dr. Abbott's implements] are found is glacial -gravel deposited upon the banks of the Delaware when, during the last -stages of the Glacial period, the river was swollen with vast floods of -water from the melting ice. Man was on this continent at that period -when the climate and ice of Greenland extended to the mouth of New York -Harbor. The probability is, that if he was in New Jersey at that time, he -was also upon the banks of the Ohio, and the extensive terrace and gravel -deposits in the southern part of our State should be closely scanned -by archæologists. When observers become familiar with the rude form of -these palæolithic implements, they will doubtless find them in abundance. -But whether we find them or not in this State [Ohio], if you admit, as -I am compelled to do, the genuineness of those found by Dr. Abbott, our -investigation into the glacial phenomena of Ohio must have an important -archæological significance, for they bear upon the question of the -chronology of the Glacial period, and so upon that of man's appearance in -New Jersey." - -[Illustration: Fig. 69.--Chipped pebble of black chert, found by Dr. C. -L. Metz. October, 1885, at Madisonville, Ohio, in gravel eight feet from -surface under clay: _a_, face view; _b_, side view.] - -The expectation of finding evidence of preglacial man in Ohio was -justified soon after this (in 1885), when Dr. C L. Metz, while -co-co-operating with Professor F. W. Putnam, of the Peabody Museum, -Cambridge, Mass., in field work, discovered a flint implement of -palæolithic type in undisturbed strata of the glacial terrace of the -Little Miami River, near his residence at Madisonville, Ohio. In 1887 -Dr. Metz found another implement in the terrace of the same river, at -Loveland, about twenty-five miles farther up the stream. The implement -at Madisonville occurred eight feet below the surface, and about a mile -back from the edge of the terrace; while that at Loveland was found in a -coarser deposit, about a quarter of a mile back from the present stream, -and thirty feet below the surface. Mastodon-bones also were discovered in -close proximity to the implement at Loveland. - -[Illustration: Fig. 70.] - -Interest in these investigations was still further increased by the -report of Mr. Hilborne T. Cresson, of Philadelphia, that in 1886, with -my map of the glaciated region in hand, he had found an implement of -palæolithic type in undisturbed strata of the glacial terrace bordering -the East Branch of White River, near the glacial boundary at Medora, -Jackson County, Ind. The terrace was about fifty feet above the -flood-plain of the river. - -Later still, in October, 1889, Mr. W. C. Mills, of Newcomerstown, -Tuscarawas County, Ohio, found in that town a finely shaped flint -implement sixteen feet below the surface of the terrace of glacial -gravel which lines the margin of the Tuscarawas Valley.[CT] Mr. Mills -was not aware of the importance of this discovery until meeting with -me some months later, when he described the situation to me, and soon -after sent the implement for examination. In company with Judge C. -C. Baldwin, President of the Western Reserve Historical Society, and -several others, a visit was made to Mr. Mills, and we carefully examined -the gravel-pit in which the implement occurred, and collected evidence -which was abundant to corroborate all his statements. The implement -in question is made from a peculiar flint which is found in the Lower -Mercer limestone, of which there are outcrops a few miles distant, and -it resembles in so many ways the typical implements found by Boucher de -Perthes, at Abbeville, that, except for the difference in the material -from which it is made, it would be impossible to distinguish it from -them. The similarity of pattern is too minute to have originated except -from imitation. - -[Footnote CT: For typical section of a glacial terrace in Ohio, see p. -227.] - -[Illustration: Fig. 71.--The smaller is the palæolith from Newcomerstown, -the larger from Amiens (face view), reduced one half in diameter.] - -In 1877, a year after the discoveries by Dr. Abbott in New Jersey, some -rude quartz implements were discovered by Professor N. H. Winchell in -the glacial terraces of the upper Mississippi, in the vicinity of Little -Falls, Morrison County, Minn. This locality was afterwards more fully -explored by Miss Franc E. Babbitt, who succeeded in finding so large a -number of the implements as to set at rest all question concerning their -human origin. According to Mr. Warren Upham, the glacial flood-plain -of the Mississippi is here about three miles wide, with an elevation -of from twenty-five to thirty feet above the river. It is in a stream -near the bottom of this glacial terrace that the most of Miss Babbitt's -discoveries were made, and Mr. Upham has pretty clearly shown that the -gravel of the terrace overlying them was mostly deposited while the -ice-front was still lingering about sixty miles farther north, in the -vicinity of Itasca Lake.[CU] - -[Footnote CU: For a general map, see p. 66; also p. 225.] - -[Illustration: Fig. 72.--Edge view of the preceding.] - -[Illustration: Fig. 73.--Section across the Mississippi Valley at Little -Falls, Minnesota, showing the stratum in which chipped quartz fragments -were found by Miss F. E. Babbitt, as described in the text (Upham).] - -Up to this time the above are all the instances in which the relics -of man are directly and indubitably connected with deposits of this -particular period east of the Rocky Mountains. Probably it is incorrect -to speak of these as preglacial, for the portion of the period at which -the deposits incorporating human relics were made is well on towards the -close of the great Ice age, since these terraces were, in some cases, and -may have been in all cases, deposited after the ice-front had withdrawn -nearly, if not quite, to the water-shed of the St Lawrence basin. It may -be difficult to demonstrate this with reference to the gravel deposits at -Trenton, Madisonville, and Medora, but it is evident at a glance in the -case of Newcomerstown and Little Falls. - -That the implement-bearing gravel of Trenton, N. J., belongs to the -later stages of the Glacial period is evident from its relation to what -Professor H. Carvill Lewis called "the Philadelphia red gravel and -brick-clay," but which, from its large development in the District of -Columbia at Washington, is called by Mr. McGee the "Columbia deposit." -The city of Philadelphia is built upon this formation in the Delaware -Valley, and the brick for its houses is obtained from it; the cellar -of each house ordinarily furnishing clay enough for its brick walls. -This clay is of course a deposit in comparatively still water, which -would imply deposition during a period of land subsidence. But that it -was ice-laden water which flooded the banks is shown by the frequent -occurrence of large blocks of stone in the deposits, such as could have -been transported only in connection with floating ice. The boulders in -the Columbia formation clearly belong to the individual river valleys in -which they are found, and doubtless are to be connected with the flooded -condition of those valleys when, by means of a northerly subsidence, the -gradient of the streams was considerably less than now. - -[Illustration: Fig. 74.--Quartz implement, found by Miss F. E. Babbitt, -1878, at Little Falls, Minnesota, in modified drift, fifteen feet below -surface: _a_, face view; _b_, profile view. The black represented on the -cut is the matrix of the quartz vein (No. 31,323) (Putnam).] - -There is some difference of opinion in respect to the extent of -this subsidence, and, indeed, respecting the height attained by the -Philadelphia brick-clay, or McGee's Columbia deposit. Professor Lewis -(whose residence was at Philadelphia, and who had devoted much time to -field observations) insisted that the deposit could not be found higher -than from 180 to 200 feet above the immediate flood-plain of the river -valleys where they occur. But, without entering upon this disputed -question, it is sufficient to consider the bearing of the facts that are -accepted by all--namely, that towards the close of the Glacial period -there was a marked subsidence of the land on the eastern coast of North -America, increasing towards the north. - -Fully to comprehend the situation, we need to bring before the mind some -of the indirect effects of the Glacial period in this region. The most -important of these was the necessary projection of subglacial conditions -over a considerable belt of territory to the south of that actually -reached by glacial ice; so that, while there are no clear indications of -the existence of local glaciers in the Appalachian Mountains south of the -central part of Pennsylvania, there are many indications of increased -snow-fall upon the mountains, connected with prolonged winters and with a -great increase of spring floods and ice-gorges upon the annual breaking -up of winter. - -These facts have been stated in detail by Mr. McGee,[CV] from whose -report it appears that, on the Potomac at Washington, the surface of -the Columbia deposit is 150 feet above tide, and that the deposit itself -contains many boulders, some of which are as much as two or three feet in -diameter. These are mingled with the gravel in such a way as to show that -they must have been brought down by floating ice from the head-waters of -the Potomac when the winters were much more severe than now. That this -deposit is properly the work of the river is shown by the entire absence -of marine shells. - -[Footnote CV: Seventh Annual Report of the United States Geological -Survey for 1885 and 1886, pp. 537-646.] - -According to Mr. McGee, also, there is a gradual decrease in the height -of these delta terraces of the Columbia period as they recede from the -glacial boundary--that at the mouth of the Susquehanna being 245 feet, -that of the Potomac 140 feet, that on the Rappahannock 125, that on the -James 100, and that on the Roanoke 75; while the size of the transported -boulders along the streams also gradually diminishes in the same order. -During the Columbia period the Susquehanna River transported boulders -fifty times the size now transported, while the Potomac transported them -only up to twenty times, the Rappahannock only ten times, the James -only five, and the Roanoke only two or three times the size of those -now transported. This progressive diminution, both in the extent of the -deposit and in the coarseness of the material deposited by these rivers -at about the time of the maximum portion of the Glacial period, is what -would naturally be expected under the conditions supposed to exist in -connection with the great Ice age, and is an important confirmation of -the glacial theory. - -That the period of subsidence and more intense glacial conditions during -which the Columbia deposits took place, preceded, by a long interval, the -deposition of the gravel terraces at Trenton, N. J., and the analogous -deposits in the Mississippi Valley where palæolithic implements have been -found, is evident enough. The Trenton gravel was deposited in a recess in -the Columbia deposit which had been previously worn out by the stream. -Indeed, in every place where opportunity offers for direct observation -the Trenton gravel is seen to be distinctly subsequent to the other. It -was not _buried by_ the Philadelphia red gravel and brick-clay, but to a -limited degree overlies and _buries_ it. - -The data for measuring the absolute length of time between these two -stages of the Glacial period are very indefinite. Mr. McGee, however, -supposes that since the Columbia period a sufficient time has elapsed -for the falls of the Susquehanna to recede more than twenty miles and -for those of the Potomac eighteen miles, and this through a rock which -is exceedingly obdurate. But, in channels opening, as these do, freely -outward, it is difficult to tell in what epochs the erosion has been -principally performed, since there are no buried channels, as in the -glaciated area, enabling us to determine whether or not much of the -eroding work of the river may have been accomplished in preglacial times. - -The lapse of time which, upon the least calculation, separates the -Columbia epoch from the Trenton, gives unusual importance to any -discovery of palæolithic implements which may be made in the earlier -deposits. We are bound, therefore, to consider with special caution -the reported discovery of an implement in these deposits at Claymont, -Delaware. The discovery was made by Dr. Hilborne T. Cresson, on July 13, -1887, during the progress of an extensive excavation in constructing the -Baltimore and Ohio Railroad, nineteen miles south of Philadelphia. The -implement was from eight to nine feet below the surface. As there is so -much chance for error of judgment respecting the undisturbed condition -of the strata, and as there was so little opportunity for Dr. Cresson to -verify his conclusion, we may well wait for the cumulative support of -other discoveries before building a theory upon it; still, it will be -profitable to consider the situation. - -[Illustration: Fig. 75.--Argillite implement, found by H. T. Cresson, -1887, in Baltimore and Ohio Railroad cut, one mile from Claymont, -Delaware, in Columbia gravel, eight to nine feet below the overlying clay -bed: _a_, face view; _b_, side view (No. 45,726) (Putnam).] - -Both Mr. McGee and myself have visited the locality with Dr. Cresson, and -there can be no doubt that the implement occurred underneath the Columbia -gravel. The line of demarcation is here very sharp between that gravel -and the decomposed strata of underlying gneiss rock, which appears in -our illustration as a light band in the middle of the section exposed. -Some large boulders which could have been moved only in connection with -floating ice are found in the overlying deposit near by. This excavation -is about one mile and a half west of the Delaware River, and about 150 -feet above it, being nearly at the uppermost limit of the Columbia -deposit in that vicinity. - -[Illustration: Fig. 76.--General section of Baltimore and Ohio cut, -near Claymont, Delaware, where Mr. Cresson found palæolithic implements -figured in the text (from photograph by Cresson).] - -The age of these deposits in which implements have been found at -Claymont and at Trenton will be referred to again when we come to the -specific discussion of the date of the Glacial period. It is sufficient -here to bring before our minds clearly, first, the fact that this at -Claymont is connected with the river floods accompanying the ice at its -time of maximum extension, and when there was a gradually increasing -or differential depression of the country to an unknown extent to the -northward. - -Two radically different theories are presented to account for the -deposits variously known as the Columbia gravel and the Philadelphia -brick-clay. Mr. McGee, in the monograph above referred to, supposes them -to have been deposited during a period of a general subsidence of the -coast-line; so that they took place at about tide-level. Mr. Upham, on -the other hand, supposes them to have been deposited during the period -of general elevation to whose influence he mainly attributes the Glacial -period itself. In his view much of the shallow sea-bottom adjoining -the present shore off from Delaware and Chesapeake Bays was then a -land-surface, and the Hudson, the Delaware, and the Susquehanna Rivers, -coming down from the still higher elevations of the north, flowed through -extensive plains so related to the northern areas of elevation that -deposition was occurring in their valleys, owing in part to the flooded -condition of the streams, in part to the differential elevation, and in -part to the superabundance of silt and other _débris_ furnished by the -melting ice-sheet in the head-waters of these streams. - -The deposits of Trenton gravel occurred much later, at a time when the -ice had melted far back towards the head-waters of the Delaware, and -after the land had nearly resumed its present relations of level, if -indeed it had not risen northward to a still greater relative height. - -As would be expected from the climatic conditions accompanying the -Glacial epoch, man's companions in the animal world were very different -during the period when the high-level river gravels of America were -forming from those with which he is now associated. From the remains -actually discovered, either in these gravels or in close proximity to -them, we infer that, while the mastodon was the most frequent of the -extinct quadrupeds with which man then had to contend in that region, he -must have been familiar also with the walrus, the Greenland reindeer, the -caribou, the bison, the moose, and the musk ox. - - -_In the Glacial Terraces of Europe._ - -The existence of glacial man in Europe was first determined in connection -with the high-level river gravels already described in the valley of the -Somme, situated in Picardy in the northern part of France. Here in 1841 -Boucher de Perthes began to discover rudely fashioned stone implements -in undisturbed strata of the gravel terraces, whose connection with -the Glacial period we have already made clear. But for nearly twenty -years his discoveries were ignored by scientific men, although he made -persistent efforts to get the facts before them, and published a full -account of them with illustrations as early as 1847. Some suggested fraud -on the part of the workmen; others without examination declared that the -gravel must have been disturbed; while others, still, denied altogether -the artificial character of the implements. - -[Illustration: Fig. 77.--Section across valley of the Somme: 1, peat, -twenty to thirty feet thick, resting on gravel, _a_; 2, lower-level -gravels, with elephant-bones and flint implements, covered with -river-loam twenty to forty feet thick; 3, upper-level gravels, with -similar fossils covered with loam, in all, thirty feet thick; 4, -upland-loam, five to six feet thick; 5, Eocene-Tertiary.] - -At length, Dr. Regillout, an eminent physician residing at Amiens, -about forty miles higher up the Somme than Abbeville, visited Boucher -de Perthes, and, upon seeing the similarity between the gravel terraces -at Abbeville and Amiens, returned home to look for similar implements -in the high-level gravel-pits at St. Acheul, a suburb of Amiens. Almost -immediately he discovered flint implements there of the same pattern with -those at Abbeville, and in undisturbed strata of the gravel terrace, -where it rested on the original chalk formation, at a height of 90 feet -above the river. In the course of four years, Dr. Regillout found several -hundred of these implements, and in 1854 published an illustrated report -upon the discoveries. - -Still the scientific world remained incredulous until the years 1858 and -1859, when Dr. Falconer, Mr. Prestwich, Mr. John Evans, Mr. Flower, Sir -Charles Lyell, of England, and MM. Pouchet and Gaudry, of France, visited -Abbeville and Amiens, and succeeded in making similar discoveries for -themselves. Additional discoveries at St. Acheul have continued up to -the present time whenever excavations have gone on at the gravel-pits. -Mr. Prestwich estimates that there is an implement to every cubic metre -of gravel, and says that he himself has brought away at different times -more than two hundred specimens, and that the total number found in this -one locality can hardly be under four thousand. "The gravel-beds are on -the brow of a hill 97 feet above the river Somme," and besides the relics -of man contain numerous fluviatile and land shells together with "teeth -and bones of the mammoth, rhinoceros, horse, reindeer, and red deer, but -not of the hippopotamus,"[CW] bones of the latter animal being found here -only in the gravels of the lower terraces, where they are less than -thirty feet above the river, and mark a considerably later stage in the -erosion of the valley. While many of the implements found at Amiens seem -to have been somewhat worn and rolled, "others are as sharp and fresh -as when first made.... The bedding of the gravel is extremely irregular -and contorted, as though it had been pushed about by a force acting from -above; and this, together with the occurrence of blocks of Tertiary -sandstone of considerable size, leads to the inference that both are due -to the action of river-ice. In the Seine Valley blocks of still larger -size, and transported from greater distances, are found in gravels of the -same age." - -[Footnote CW: Prestwich's Geology, vol. ii, p. 481.] - -"Flint implements are found under similar conditions in many of the -river-valleys of other parts of France, especially in the neighbourhood -of Paris; of Mons in Belgium; in Spain, in the neighbourhood of -Madrid, in Portugal, in Italy, and in Greece; but they have not been -discovered in the drift-beds of Denmark, Sweden, or Russia, nor is there -any well-authenticated instance of the occurrence of palæoliths in -Germany."[CX] - -[Footnote CX: Prestwich's Geology, vol. ii, pp. 481, 482.] - -When once the fact had been established that man was in northern France -at the time of the deposition of the high-level gravels of the Somme and -the Seine, renewed attention was directed to terraces of similar age in -southern England. One of these is that upon which the city of London is -built, and which, according to Lyell's description, "extends from above -Maidenhead through the metropolis to the sea, a distance from west to -east of fifty miles, having a width varying from two to nine miles. Its -thickness ranges commonly from five to fifteen feet."[CY] - -[Footnote CY: Antiquity of Man, pp. 154, 155.] - -For a long time geologists had been familiar with the fact that these -terraces of the Thames contain the remains of numerous extinct animals, -among which are included the mammoth and a species of rhinoceros. -Upon directing special attention to the subject, it was found that, at -various intervals, the remains of man, also, had been reported from the -same deposits. As long ago as 1715 Mr. Conyers discovered a palæolithic -implement, in connection with the skeleton of an elephant, at Black -Mary's, near Gray's Inn Lane, London. This implement is preserved in the -British Museum, and closely resembles typical specimens from the gravel -at Amiens. Other implements of similar character have been found in -the valley of the Wey near Guilford, also in the valley of the Darent, -near Whitstable in Kent, and between Heme Bay and the Reculvers. While -the exact position of these implements in the gravel had not been so -positively noted as in the case of those found at Amiens and Abbeville, -there can be little doubt that man, in company with the extinct animals -mentioned, inhabited the valley of the Thames at a period when its annual -floods spread over the whole terrace-plain upon which the main part of -London is built. - -In the valley of the Ouse, however, near Bedford, the discovery of -palæolithic implements in the gravel terraces connected with the -Glacial period and in intimate association with bones of the elephant, -rhinoceros, hippopotamus, and other extinct animals, has been as fully -established as in the valley of the Somme. The discoveries here were -first made in the year 1860, by Mr. James Wyatt, in a gravel-pit at -Biddenham, two miles northwest of Bedford. Two flint implements were -thrown out by workmen in one day from undisturbed strata thirteen feet -below the surface, and numerous other specimens have since been found in -a similar situation. - -The valley of the Ouse is bordered on either side by sections of a -superficial blanket of glacial drift containing many transported boulders -of considerable size. The valley is here about two miles wide, and ninety -feet deep. The gravel deposit, however, in which the implements were -found, is only about thirty feet above the present level of the river, -and hence represents the middle period of the work of the river in -erosion. - -Another locality in England in which similar discoveries have been made, -is at Hoxne, about five miles from Diss, in Suffolk County. Like that -in the valley of the Thames, however, the implements were found a long -time before the significance of the discovery was recognized. Mr. John -Frere reported the discovery to the Society of Antiquaries in 1801, -and gave some of the implements both to the society and to the British -Museum, in whose collections they are still preserved. The implements are -of the true palæolithic type, and existed in such abundance, and were -so free from signs of wear, that the conclusion seemed probable that a -manufactory of them had been uncovered. As many as five or six to the -square yard are said to have been found. Indeed, their numbers were so -great that the workmen "had emptied baskets of them into the ruts of the -adjoining road before becoming aware of their value." - -The deposit in which they are found is situated in the valley of Gold -Brook, a tributary of the Waveney. The implements occurred about twelve -feet below the surface, in fresh-water deposits, filling a hollow eroded -in the glacial deposit covering that part of England. This, therefore, is -clearly either of post-glacial or of late glacial age. - -Still another locality in which similar palæolithic implements were found -in undisturbed gravel of this same age in eastern England is Icklingham, -in the valley of the Lark, where the situation is quite similar to that -already described at Bedford, on the Ouse. - -The last place we will stop to mention in England which was visited -by palæolithic man, during or soon after the Glacial epoch, is to be -found in the vicinity of Southampton. At this time the Isle of Wight -was joined to the mainland, and not improbably England itself to the -Continent. The river, then flowing through the depression of the Solent -and the Southampton Water, occupied a much higher level than now, leaving -terraces along the shore at various places, in which the tools of -palæolithic man have been discovered. - -Though these are the best authenticated discoveries connecting man with -the Glacial period in England, they are by no means the only probable -cases. Almost every valley of southern England furnishes evidence of a -similar but less demonstrative character. - - -_In Cave Deposits._ - -The discovery of the remains of man in the high-level river-gravels -deposited near the close of the Glacial period led to a revision of the -evidence which had from time to time been reported connecting the remains -of man with those of various extinct animals in cave deposits both in -England and upon the Continent. - - -_The British Isles._ - -As early as 1826, Rev. J. MacEnery, a Roman Catholic priest residing -near Torquay, in Devonshire, England, had made some most remarkable -discoveries in a cavern at Kent's Hole, near his home; but, owing to his -early death, and to the incredulity of that generation of scientific -men, his story was neither credited nor published till 1859. About this -time, a new cave having been discovered not far away, at Brixham, the -best qualified members of the Royal Society (Lyell, Phillips, Lubbock, -Evans, Vivian, Pengelly, Busk, Dawkins, and Sanford) were deputed to see -that it was carefully explored. Mr. Pengelly, who had had twenty years' -experience in similar explorations, directed and superintended the work. -Every portion of the contents was examined with minutest care. Kent's -Hole is "180 to 190 feet above the level of mean tide, and about 70 feet -above the bottom of the valley immediately adjacent."[CZ] In one chamber -the excavation was about sixty feet square. The contents were arranged in -the following order: - -[Footnote CZ: Dawkins's Cave-Hunting, p. 325.] - -[Illustration: Fig. 78.--Mouth of Kent's Hole.] - -1. A surface of dark earth a few inches thick, containing Roman pottery, -iron and bronze spear-heads, together with polished stone weapons. There -were, too, in this stratum bones of cows, goats, and horses, mingled with -large quantities of charcoal. - -2. Below this was a stalagmite floor from one to three feet thick, formed -by the dripping of lime-water from the roof. - -3. Under this crust of stalagmite was a compact deposit of red earth, -from two to thirteen feet thick.[DA] Flint implements of various kinds -and charcoal were also found at different depths; also an awl, or -piercer; a needle with the eye large enough to admit small pack-thread; -and three harpoon-heads made out of bone and deer's horn. - -[Footnote DA: Dawkins's Cave-Hunting, p. 326; Lyell's Antiquity of Man, -p. 101.] - -4. Flint implements were also obtained in a conglomerate (breccia) still -below this. The fossil bones in this cave belonged to the same species of -animals as those discovered in a cave near Wells. - -The Brixham cave occurs near the small village of that name, not far from -Torquay. The entrance to it is about ninety-five feet above high water. -Its deposits, in descending order, are: 1. Stalagmitic floor from six to -twelve or fifteen inches in thickness. 2. A thin breccia of limestone -fragments cemented together by carbonate of lime. This had accumulated -about the mouth, so as to fill up the entrance. 3. A layer of blackish -earth about one foot in thickness 4. A deposit of from two to four feet -thick, consisting of clayey loam, mingled with fragments of limestone, -from small bits up to rocks weighing a ton. Bounded pebbles of other -material were also occasionally met with. 5. Shingle consisting of -rounded pebbles largely of foreign material. - -All these strata, except the third, contained fossils of some kind, but -the fourth was by far the richest repository. Among the bones found are -those of the mammoth, the woolly rhinoceros, the horse, the ox, the -reindeer, the cave-lion, the cave-hyena, and the cave-bear. Associated -with these remains a number of worked flints was found. In one place -the bones of an entire leg of a cave-bear occurred in such a position as -to show that they must have been bound together by the ligaments when -they were buried. Immediately below these bones a flint implement was -found.[DB] - -[Footnote DB: See Pengelly's Reports to the Devonshire Association, 1867.] - -The hyena's den, at Wookey Hole, near Wells, in Somerset, was carefully -explored by Professor Boyd Dawkins, who stood by and examined every -shovelful of material as it was thrown out. - -This cave alone yielded 35 specimens of palæolithic art, 467 jaws and -teeth of the cave-hyena, 15 of the cave lion, 27 of the cave-bear, 11 of -the grizzly bear, 11 of the brown bear, 7 of the wolf, 8 of the fox, 30 -of the mammoth, 233 of the woolly rhinoceros, 401 of the horse, 16 of the -wild ox, 30 of the bison, 35 of the Irish elk, and 30 of the reindeer -(jaws and teeth only). - -In Derbyshire numerous caves were explored by Professor Dawkins at Cress -well Crags, which, in addition to flint implements and the remains of -the animals occurring in the Brixham cave, yielded the bones of the -machairodus, an extinct species of tiger or lion which lived during the -Tertiary period. - -The Victoria cave, near Settle, in west Yorkshire, is the only other one -in England which we need to mention. In this there were no remains found -which could be positively identified as human, but the animal remains -in the lower strata of the cave deposit were so different from those in -the upper bed as to indicate the great lapse of time which separated the -two. This cave is 1,450 feet above the sea-level, and there were found in -the upper strata of the floor, down to a depth of from two to ten feet, -many remains of existing animals. Then, for a distance of twelve feet, -there occurred a clay deposit, containing no organic remains whatever, -but some well-scratched boulders. Below this was a third stratum of earth -mingled with limestone fragments, at the base of which were numerous -remains of the mammoth, rhinoceros, hippopotamus, bison, hyena, etc. -One bone occurred which was by some supposed to be human, but by others -to have belonged to a bear. This lower stratum is, without much doubt, -preglacial, and the thickness of the deposit intervening between it and -the upper fossiliferous bed is taken by some to indicate the great lapse -of time separating the period of the mammoth and rhinoceros in England -from the modern age. The scratched boulders in the middle stratum of -laminated clay, would indicate certainly that the material found its way -into the cave during the Glacial epoch, when ice filled the whole valley -of the Ribble, which flows past the foot of the hill, and whose bed is -900 feet below the mouth of the cave. - -In North Wales the Vale of Clwyd contains numerous caves which were -occupied by hyenas in preglacial times and with their bones are -associated those of the mammoth, the rhinoceros, the hippopotamus, the -cave-lion, the cave-bear, and various other animals. Flint implements -also were found in the cave at Cae Gwyn, near the village of Tremeirchon, -on the eastern side of the valley, opposite Cefn, and about four miles -distant. We have already given an illustration of the Cefn cave (see -page 148). It will be observed that this valley of the Clwyd opens to -the north, and has a pretty rapid descent to the sea from the Welsh -mountains, and was in position to be obstructed by the Irish Sea glacier, -so as to have been occupied at times by one of the characteristic -marginal lakes of the Glacial period. It is evident also that the -northern ice prevailed over the Welsh ice for a considerable portion -of the lower part of the valley; for northern drift is the superficial -deposit upon the hills on the sides of the valley up to a height of over -500 feet. From the investigations of Mr. C. E. De Rance, F. G. S.,[DC] -it is equally clear also that the northern drift, which until lately -sealed up the entrance of the cave, was subsequent to its occupation by -man, and this was the opinion formed by Sir Archibald Geikie, Director -General of the Geological Survey of the United Kingdom, as the result of -special investigations which he made of the matter.[DD] - -[Footnote DC: Proceedings of the Yorkshire Geological Society for 1888, -pp. 1-20.] - -[Footnote DD: See De Ranee, as above, p. 17; and article by H. Hicks, -in Quarterly Journal of Geological Society, vol. xlii, p. 3; Geological -Magazine, May, 1885, p. 510.] - -From the caves in the Vale of Clwyd as many as 400 teeth of rhinoceros, -500 of horse, 180 of hyena, and 15 of mammoth have been taken. A section -of the cave deposits in the cave at Cae Gwyn is as follows: - -"Below the soil for about eight feet a tolerably stiff boulder-clay, -containing many ice-scratched boulders and narrow bands and pockets of -sand. Below this about seven feet of gravel and sand, with here and -there bands of red clay, having also many ice-scratched boulders. The -next deposit was a laminated brown clay, and under this was found the -bone-earth, a brown, sandy clay with small pebbles and with angular -fragments of limestone, stalagmites, and stalactites. During the -excavations it became clear that the bones had been greatly disturbed by -water action; that the stalagmite floor, in parts more than a foot in -thickness, and massive stalactites, had also been broken and thrown about -in all positions; and that these had been covered afterwards by clays and -sand containing foreign pebbles. This seemed to prove that the caverns, -now 400 feet above ordnance datum, must have been submerged subsequently -to their occupation by the animals and by man. In Dr. Hicks's opinion, -the contents of the cavern must have been disturbed by marine action -during the great submergence in mid-glacial times, and afterwards -covered by marine sands and by an upper boulder-clay, identical in -character with that found at many points in the Vale of Clwyd. The -paleontological evidence suggests that the deposits in question are not -preglacial, but may be equivalent to the Pleistocene deposits of our -river-valleys."[DE] - -[Footnote DE: H. B. Woodward's Geology of England and Wales, pp. 543, 544] - -If the views of Professor Lewis and Mr. Kendall are correct concerning -the unity of the Glacial period in England, the shelly and sandy deposits -connected with these Clwydian caves at an elevation of 400 feet or more -would be explained in connection with the marginal lakes which must -have occupied the valley during both the advance and the retreat of -the ice-front; the shells having been carried up from the sea-bottom -by the ice-movement, after the manner supposed in the case of those at -Macclesfield and Moel Tryfaen. If, therefore, the statements concerning -the discovery of flint implements in this Cae Gwyn cave can be relied -upon, this is the most direct evidence yet obtained in Europe of man's -occupation of the island during the continuance of the Glacial period. - -In all these caves it is to be noted that there is a sharp line of -demarcation between the strata containing palæolithic implements and -those containing only the remains of modern animals. Palæolithic -implements are confined to the lower strata, which in some of the caves -are separated from the upper by a continuous bed of stalagmite, to which -reference will be made when discussing the chronology of the Glacial -period. The remains of extinct animals also are confined to the lower -beds. - -The caves which we have been considering in England are all in limestone -strata, and have been formed by streams of water which have enlarged some -natural fissures both by mechanical action in wearing away the rocks, and -by chemical action in dissolving them. Through the lowering of the main -line of drainage, caverns with a dry floor are at length left, offering -shelter and protection both to man and beast. Oftentimes, but not always, -some idea of the age of these caverns may be obtained by observing the -depth to which the main channel of drainage to which they were tributary -has been lowered since their formation. But to this subject also we will -return when we come specifically to discuss the chronological question. - - -_The Continent._ - -Systematic explorations in the caves of Belgium were begun in 1833 by -Dr. Schmerling, in the valley of the Meuse, near his residence in Liége. -The Meuse is here bordered by limestone precipices 200 or more feet in -height. Opening out from these rocky walls are the entrances to the -numerous caverns which have rendered the region so famous. To get access -to the most important of these, Dr. Schmerling had to let himself down -over a precipice by a rope tied to a tree, and then to creep along on -all-fours through intricate channels to reach the larger chambers which -it was his object to explore. In the cave at Engis, on the left bank of -the Meuse, about eight miles above Liége, he found a human skull deeply -buried in breccia in company with many bones of the extinct animals -previously stated to have been associated with man during the Glacial -period. This so-called "Engis skull" was by no means apelike in its -character, but closely resembled that of the average Caucasian man. But -this established the association upon the Continent of man with some of -the extinct animals of the Glacial period. - -[Illustration: Fig. 79.--Engis skull, reduced (after Lyell.)] - -The vicinity of Liége has also furnished us another cavern whose -contents are of the highest importance, ranking indeed as perhaps the -most significant single discovery yet made. The cave referred to is -on the property of the Count of Beauffort, in the commune of Spy, in -the province of Namur in Belgium. For the facts relating to it we are -indebted to Messrs: Lohest and Fraipont, the former Professor of Geology -and the latter of Anatomy in the University of Liége. The exploration -of the cave was made in 1886, and the full report with illustrations -published in the following year in Archives de Biologie.[DF] The -significance of this discovery is enhanced by the light it sheds upon and -the confirmation it brings to the famous Neanderthal skull and others of -similar character, which for a long time had been subjects of vigorous -discussion. Before describing it, therefore, we will give a brief account -of the previous discoveries. - -[Footnote DF: See pp. 587, 757.] - -The famous Neanderthal skull was brought to light in 1857 by workmen in a -limestone-quarry, near Düsseldorf, in the valley of the Neander, a small -tributary to the Rhine. By these workmen a cavern was opened upon the -southern side of the winding ravine, about sixty feet above the stream -and one hundred feet below the top of the cliff. The skull attracted much -attention from its supposed possession of many apelike characteristics; -indeed, it was represented by some to be a real intermediate link between -man and the anthropoid apes. The accompanying cut enables one to compare -the outline of the Neanderthal skull with that of a chimpanzee on the -one hand and of the highly developed European on the other. The apelike -peculiarities of this skull appear in its vertical depression, in the -enormous thickness of the bony ridges just above the eyes, and in the -gradual slope of the back part of the head, together with some other -characteristics which can only be described in technical language; so -that it was pronounced by the highest authorities the most apelike of -human crania which had yet been discovered. Unfortunately, the jaw was -not found. The capacity of the skull, however, was seventy-five cubic -inches, which is far above that of the highest of the apes, being indeed -equal to the average capacity of Polynesian and Hottentot skulls.[DG] -Huxley well remarks that "so large a mass of brain as this would alone -suggest that the pithecoid tendencies indicated by this skull did not -extend deep into the organization." - -[Footnote DG: Huxley's Man's Place in Nature, p. 181.] - -[Illustration: Fig. 80.--Comparison of forms of skulls: _a_, European; -_b_, the Neanderthal man; c, a chimpanzee (after Lyell).] - -[Illustration: Fig. 81.--Skull of the Man of Spy. (From photograph.)] - -Upon extending inquiries, it was found that the Neanderthal type of -skull is one which still has representatives in all nations; so that it -is unsafe to infer that the individual was a representative of all the -individuals living in his time. The skull of Bruce, the celebrated Scotch -hero, was a close reproduction of the Neanderthal type; while, according -to Quatrefages,[DH] the skull of the Bishop of Toul in the fourth century -"even exaggerates some of the most striking features of the Neanderthal -cranium. The forehead is still more receding, the vault more depressed, -and the head so long that the cephalic index is 69-41." The discovery of -Messrs. Fraipont and Lohest adds much to our definite knowledge of the -Neanderthal type of man, since the Belgic specimens are far more complete -than any others heretofore found, there being in their collection two -skulls, together with the jawbones and most of the other parts of the -frame. In this case also there is no suspicion that the deposits had been -disturbed, so as to admit any intrusion of human relics into the company -of relics of an earlier age. According to M, Lohest, there were three -distinct ossiferous beds, separated by layers of stalagmite. All the -ossiferous beds contained the remains of the mammoth, but in the upper -stratum they were few, and probably intrusive. The implements found in -this were also of a more modern type. In the second stratum from the top -numerous hearths were found with burnt wood and ashes, together with the -bones of the rhinoceros, the horse, the mammoth, the cave-bear, and the -cave-hyena, all of which were abundant, while there were also specimens -of the Irish elk, the reindeer, the bison, the cave-lion, and several -other species. In this layer also there were numerous implements of -ivory, together with ornaments and some faint indications of carving upon -the rib of a mammoth, besides a few fragments of pottery. - -[Footnote DH: Human Species, p. 310,] - -It was in the third, or lowest, of these beds that the skeletons -were found. Here they were associated with abundant remains of the -rhinoceros, the horse, the bison, the mastodon, the cave-hyena, and a -few other extinct species. Flint implements also, of the "Mousterien" -pattern (which, according to the opinion of the French archæologists, is -characteristic of middle palæolithic times), were abundant Neither of the -skeletons was complete, but they were sufficiently so to give an adequate -idea of the type to which they belong, and one of the skulls is nearly -perfect. According to M. Fraipont, "one of these skulls is apparently -that of an old woman, the other that of a middle-aged man. They are both -very thick; the former is clearly dolichocephalic (long-headed, index -70), the other less so. Both have very prominent eyebrows and large -orbits, with low, retreating foreheads, excessively so in the woman. The -lower jaws are heavy. The older has almost no projecting chin. The teeth -are large, and the last molar is as large as the others. These points -are characteristic of an inferior and the oldest-known race. The bones -indicate, like those of the Neanderthal and Naulette specimens, small, -square-shouldered individuals." They were "powerfully built, with strong, -curiously curved thigh-bones, the lower ends of which are so fashioned -that they must have walked with a bend at the knees."[DI] - -[Footnote DI: Huxley, Nineteenth Century, vol. xxviii (November, 1890), -p. 774.] - -Other crania from various Quaternary deposits in Europe seem to warrant -the inference that this type of man was the prevalent one during the -early part of the Palæolithic age. As long ago as 1700 a skull of -this type was exhumed in Canstadt, a village in the neighbourhood -of Stuttgart, in Würtemberg. This was found in coexistence with the -extinct animals whose bones we have described as so often appearing in -the high-level river-gravel of the Glacial age. But the importance of -the discovery at Canstadt was not appreciated until about the middle -of the present century. From the priority of the discovery, and of the -discussion among German anthropologists concerning it, it has been -thought proper, however, by some to give the name of this village to the -race and call it the "Canstadt race." But, whatever name prevails, it -is important in our reading to keep in mind that the man of Canstadt, -the man of Neanderthal, and the man of Spy are identical in type, and -probably in age. Similar discoveries have been made in various other -places. Among these are a lower jaw of the same type discovered in 1865 -by M. Dupont, at Naulette, in the valley of the Lesse, in Belgium, and -associated with the remains of extinct animals; a jawbone found in a -grotto at Arcy; a fragment of a skull found in 1865 by Faudel, in the -loess of Eguisheim, near Colmar; a skull at Olmo, discovered in 1863, in -a compact clayey deposit forty-five feet below the surface; and a skull -discovered in 1884 at Marcilly. - -M. Dupont has brought to light much additional testimony to glacial man -from other caves in different parts of Belgium. In all he has explored as -many as sixty. Three of these, in the valley of the Montaigle, situated -about one hundred feet above the river, contained both remains of man -and many bones of the mammoth and other associated animals, which had -evidently been brought in for food. - -In the hilly parts of Germany, also, and in Hungary, and even in the -Ural Mountains in Russia, and in one of the provinces of Siberia, the -remains of the rhinoceros, and most of the other animals associated with -man in glacial times, have been found in the cave deposits which have -been examined. Though it can not be directly proved that these animals -were associated with man in any of these places, still it is interesting -to see how wide-spread the animals were in northern Europe and Asia -during the Glacial period. - -Some northern animals, also, spread at this time into southern -Europe--remains of the reindeer having been discovered on the south slope -of the Pyrenees, but the remains of the mammoth, the woolly rhinoceros, -and the musk ox, have not been found so far south. - -African species of the elephant, however, seem at one time to have had -free range throughout Spain, and the hippopotamus roamed in vast herds -over the valleys of Sicily, while several species of pygmy elephants seem -to be peculiar to the island of Malta. - -In the case of all the cave deposits referred to (with possibly the -exception of those of Victoria, England, and Cae Gwyn, Wales), the -evidence of man's existence during the Glacial period is inferential, -and consists largely in the fact that he was associated with various -extinct animals which did not long survive that period, or with animals -that have since retired from Europe to their natural habitat in -mountain-heights or high latitudes. The men whose remains are found in -the high-level river-drift, and in the caverns described, were evidently -not in possession of domestic animals, as their bones are conspicuous for -their absence in all these places. The horse, which would seem to be an -exception, was doubtless used for food, and not for service. - -If we were writing upon the general subject of the antiquity and -development of the human race, we should speak here in detail of several -other caves and rock shelters in France and southern Europe, where -remains of man belonging to an earlier period have been found. We should -mention the rock shelter of Cro-Magnon in the valley of Vezère, as well -as that of Mentone, where entire human skeletons were found. But it is -doubtful if these and other remains from caves which might be mentioned -belong in any proper sense to the Glacial period. The same remarks should -be made also with reference to the lake-dwellings in Switzerland, of -which so much has been written in late years. All these belong to a much -later age than the river-drift man of whom we are speaking, and of whom -we have such abundant evidence both in Europe and in America. - -[Illustration: Fig. 82.--Tooth of Machairodus neogæus, × 1/6 (drawn from a -cast).] - -[Illustration: Fig. 83.--Perfect tooth of an Elephas, found in Stanislaus -County, California, 1/8 natural size.] - - -_Extinct Animals associated with Man during the Glacial Period._ - -This is the proper place in which to speak more fully of the extinct -animals which accompanied man in his earliest occupation of Europe and -America, and whose remains are so abundant in the river-drift gravel and -in the caves of England, in connection with the relics of man. Among -these animals are - -The Lion, which is now confined, to Africa and the warmer portions of -Asia. But in glacial times a large species of this genus ranged over -Europe from Sicily to central England. - -The saber-toothed Tiger, with tusks ten inches long: (Machairodus -latidens), is now extinct. This species was in existence during the -latter part of the Tertiary period, but continued on until after man's -appearance in the Glacial period. The presence of this animal would seem -to indicate a warm climate. - -The Leopard (_Felis pardus_) is now confined to Africa and southern Asia, -and the larger islands adjoining; but during man's occupation of Europe -in the Glacial epoch he was evidently haunted at every step by this -animal; for his bones are found as far north in England as palæolithic -man is known to have ranged. - -The Hyena. Two species of this animal are found in the bone-caves of -Europe. During the Glacial epoch they ranged as far up as northern -England, but they are now limited to Africa and southwestern Asia. - -[Illustration: Fig. 84.--Skull of _Hyena spelæa_, × 1/4.] - -The Elephant is represented in the Preglacial and Glacial epochs by -several species, some of which ranged as far north as Siberia. The -African elephant is not now found north of the Pyrenees and the Alps. -But a species of dwarf elephant, but four or five feet in height, -has already been referred to as having occupied Malta and Sicily; and -still another species has been found in Malta, whose average height -was less than three feet. An extinct species (Elephas antiquus), whose -remains are found in the river-drift and in the lower strata of sediment -in many caverns as far north as Yorkshire, England, was of unusual -size, and during the Glacial period was found on both sides of the -Mediterranean. But the species most frequently met with in palæolithic -times was the mammoth (_Elephas primigenius_). This animal, now extinct, -accompanied man in nearly every portion both of Europe and North America, -and lingered far down into post-glacial times before becoming extinct. -This animal was nearly twice the weight of the modern elephant, and one -third taller. Occasionally his tusks were more than twelve feet long, -and curved upward in a circle. It is the carcasses of this animal which -have been found in the frozen soil of Siberia and Alaska. It had a thick -covering of long, black hair, with a dense matting of reddish wool at the -roots. During the Glacial period these animals must have roamed in vast -herds over the plains of northern France and southern England, and the -northern half of North America. - -[Illustration: Fig. 85.--Celebrated skeleton of mammoth, in St. -Petersburg museum.] - -[Illustration: Fig. 86.--Molar tooth of mammoth (_Elephas primigenius_): -_a_, grinding surface; _b_, side view.] - -The Hippopotamus is at present a familiar animal in the larger rivers -of Africa, but is not now found in Europe. During the Glacial period, -however, he ranged as far north as Yorkshire, England, and his remains -were found in close association with those of man, both in Europe and on -the Pacific coast in America. Twenty tons of their bones have been taken -from a single cave in Sicily.[DJ] - -[Footnote DJ: Prestwich's Geology, vol. ii, p. 508.] - -[Illustration: Fig. 87.--Tooth of _Mastodon Americanus_.] - -The mammoth and the rhinoceros we know to have been adapted to cold -climates by the possession of long hair and thick fur, but the -hippopotamus by its love for water would seem to be precluded from the -possession of this protective covering. It is suggested, however, by -Sir William Dawson, that he may have been adapted to arctic climates by -a fatty covering, as the walrus is at the present time. A difficulty in -accounting for many of the remains of the hippopotamus in some of the -English caverns is that they are so far away from present or possible -water-courses. But it would seem that due credit has not been ordinarily -given to the migratory instincts of the animal. In southern Africa they -are known to "travel speedily for miles over land from one pool of a -dried-up river to another; but it is by water that their powers of -locomotion are surpassingly great, not only in rivers, but in the sea.... -The geologist, therefore, may freely speculate on the time when herds -of hippopotami issued from North African rivers, such as the Nile, and -swam northward in summer along the coasts of the Mediterranean, or even -occasionally visited islands near the shore. Here and there they may have -landed to graze or browse, tarrying awhile, and afterwards continuing -their course northward. Others may have swum in a few summer days from -rivers in the south of Spain or France to the Somme, Thames, or Severn, -making timely retreat to the south before the snow and ice set in."[DK] - -[Footnote DK: Lyell, Antiquity of Man, p. 180,] - -The Mastodon (_Mastodon Americanus_), (Fig. 88), "is probably the largest -land mammal known, unless we except the Dinotherium. It was twelve to -thirteen feet high, and, including the tusks, twenty-four to twenty-five -feet long. It differed from the elephant chiefly in the character of its -teeth. The difference is seen in Figs. 86 and 87. The elephant's tooth -given above (Fig. 86) is sixteen inches long, and the grinding surface -eight inches by four." - -[Illustration: Fig. 88.--_Mastodon Americanus_ (after Owen).] - -The mastodon, together with the mammoth, made their appearance about -the middle of the Miocene epoch. At the close of the Tertiary period -the mastodon became extinct on the Eastern Continent, but continued in -North America to be a companion of man well on toward the close of the -Glacial period. Many perfect skeletons have been found in the deposits -of this period in North America. "One magnificent specimen was found in -a marsh near Newburg, New York, with its legs bent under the body, and -the head thrown up, evidently in the very position in which it mired. The -teeth were still filled with the half-chewed remnants of its food, which -consisted of twigs of spruce, fir, and other trees; and within the ribs, -in the place where the stomach had been, a large quantity of similar -material was found."[DL] - -[Footnote DL: Le Conte's Geology (edition of 1891), p. 582.] - -The Rhinoceros is now confined to Africa and southern Asia; but the -remains of four species have been found in America, Europe, and northern -Asia, in deposits of the Glacial period. In company with that of the -mammoth, already spoken of, a carcass of the woolly rhinoceros was found -in 1771 in the frozen soil of northern Siberia. The bones of other -species have been found as far north as Yorkshire, England. In the valley -of the Somme there was found "the whole hind limb of a rhinoceros, the -bones of which were still in their true relative position. They must -have been joined together by ligaments and even surrounded by muscles -at the time of their interment." An entire skeleton was found near by. -The gravel terrace in which these occurred is about forty feet above the -floor of the valley, and must have been formed subsequent to some of the -strata which contained the remains of human art. In America the bones are -found in the gold-bearing gravels of California, in connection with human -remains. - -[Illustration: Fig. 89.--Skeleton of _Rhinoceros tichorhinus_.] - -[Illustration: Fig. 90.--Skull of cave-bear (_Ursus spelæus_),] - -The Bear was represented in Europe in palæolithic times by three species, -of which only one exists there at the present time. But during the -Glacial period the grizzly bear, now confined to the western part of -America, and the extinct cave-bear were companions, or enemies as the -case may be, of man throughout Europe. The cave-bear was of large size, -and his bones occur almost everywhere in the lower strata of sediment in -the caves of England. - -The Great Irish Elk, or deer, is now extinct, though it is supposed by -some to have lingered until historic times. Its remains are found widely -distributed over middle Europe in deposits of palæolithic age. - -[Illustration: Fig. 91.--Skeleton of the Irish elk (_Cervus megaceros_).] - -The Horse was also, as we have seen, a very constant associate of man -in middle Europe during the Palæolithic age, but probably not as a -domesticated animal. The evidence is pretty conclusive that he was -prized chiefly for food. About some of the caves in France such immense -quantities of their bones are found that they can be accounted for best -as refuse-heaps into which the useless bones had been thrown after their -feasts, after the manner of the disposal of shells of shell-fish. In -America the horses associated with man were probably of a species now -extinct. The skull of one (_Equus excelsus_) recently found in Texas, in -Pleistocene deposits, associated with human implements, is, according -to Cope, intermediate in character between the horse and quagga.[DM] -The frontal bone was crushed in in a manner to suggest that it had been -knocked in the head with a stone hammer, such as was found in the same -bed. Possibly, therefore, man's love of horse-flesh may have been an -important element in securing the extinction of the species in America. - -[Footnote DM: American Naturalist, vol. xxv (October, 1891), p. 912.] - -Besides these animals there were associated with man at this time the -Musk Sheep and the Reindeer, both now confined to the regions of the far -north, but during the Glacial period ranging into southern France, and -mingling their bones with those both of man and of the southern species -already enumerated. - -[Illustration: Fig. 92.--Musk-sheep (_Ovibos moschatius_).] - -The Wolverine, the Arctic Fox, the Marmot, the Lemming--all now confined -to colder regions--at that time mingled on the plains of central Europe -with the species mentioned as belonging now to Africa and southern Asia. -The Ibex, also, and the Snowy Vole and Chamois descended to the plains -from their mountain-heights, and joined in the strange companionship of -animals from the north and from the south. - -Besides these extremes there were associated with man during the Glacial -period numerous representatives of the temperate group of existing -animals, such as the bison, the horse, the stag, the beaver, the hare, -the rabbit, the otter, the weasel, the wild-cat, the fox, the wolf, the -wild boar, and the brown bear. - -[Illustration: Fig. 93.--Reindeer.] - -To account for this strange intermingling of arctic and torrid species -of animals, especially in Europe, during man's occupancy of the region -in glacial times, various theories have been resorted to, but none of -them can be said to be altogether satisfactory. One hypothesis is that -the bones of these diverse animals became mingled by reason of the great -range of the annual migration of the species. The reindeer, for example, -still performs extensive annual migrations. In summer it ventures far out -upon the _tundras_ of North America and Siberia to feed upon the abundant -vegetation that springs up like magic under the influence of the long -days of sunshine; while, as winter approaches, it returns to the forests -of the interior. Or in other places this animal and his associates, -like birds of passage, move northward in summer to escape the heat, and -southward in the winter to escape the extreme cold. Many of the other -animals also are more or less migratory in their habits. - -Thus it is thought that during the Glacial period, when man occupied -northern France and southern England, the reindeer, the musk sheep, the -arctic fox, and perhaps the hippopotamus and some other animals, annually -vibrated between northern England and southern France, a slight elevation -of the region furnishing a land passage from England to the continent; -while the chamois and other Alpine species vibrated as regularly between -the valleys in winter and the mountain-heights in summer. The habits of -these species are such that it is not difficult to see how in their case -this migration could have taken place. - -Professor Boyd Dawkins attempts to reduce the difficulty by supposing -that the Glacial epoch was marked by the occurrence of minor periods of -climatic variation, during which, in comparatively short periods, the -isothermal lines vibrated from north to south, and _vice versa_. In this -view the southern species gradually crowded upon the northern during -the periods of climatic amelioration, until they reached their limit in -central England, and then in turn, as the climate became more rigorous, -slowly retreated before the pressure of their northern competitors. -Meanwhile the hyena sallied forth from his various caves, over this -region, at one time of the year to feed upon the reindeer, and at another -time of the year upon the flesh of the hippopotamus, in both cases -dragging their bones with him to his sheltered retreat in the limestone -caverns[DN] which he shared at intervals with palæolithic man. - -[Footnote DN: Early Man in Britain, p. 114.] - -The theory of Mr. James Geikie is that the period, while one of great -precipitation, was characterised by a climate of comparatively even -temperature, in which there was not so great a difference as now between -the winters and the summers, the winters not being so cold and the -summers not so hot as at present. This is substantially the condition of -things in southern Alaska at the present time, where extensive glaciers -come down to the sea-level, even though the thermometer at Sitka rarely -goes below zero (Fahrenheit). It is, therefore, easy to conceive that if -there were extensive plains bordering the Alaskan archipelago, so as to -furnish ranging grounds for more southern species, the animals of the -north and the animals of the south might partially occupy the same belt -of territory, and their bones become mingled in the same river deposits. - -In order to clear the way for either of these hypotheses to account -for the mingling of arctic and torrid species characteristic of the -period under consideration in Europe, we must probably suppose such an -elevation of the region to the south as to afford land connection between -Europe and Africa. This would be furnished by only a moderate amount of -elevation across the Strait of Gibraltar and from the south of Italy to -the opposite shore in Africa; and there are many indications, in the -distribution of species, of the existence in late geological times of -such connection. - -It should also be observed that the present capacities and habits of -species are not a certain criterion of their past habits and capacities. -As already remarked, both the rhinoceros and the mammoth of glacial -times were probably furnished with a woolly protection, which enabled -them to endure more cold than their present descendants could do, while -the elephant is even now known to be able to endure the rigors of the -climate at great elevations upon the Himalaya Mountains. We can easily -imagine these species to have been adjusted to quite different climatic -conditions from those which now seem necessary to their existence. In -the case of the hippopotamus, also, it is quite possible, as already -suggested, that it is more inclined to migration than is generally -supposed. - -Geikie's theory of the prevalence of an equable climate during a portion -of the Glacial period in Europe is thought to be further sustained -by the character of the vegetation which then covered the region, as -well as by the remains of the mollusks which occupied the waters. Then -"temperate and southern species like the ash, the poplar, the sycamore, -the fig-tree, the Judas-tree, the laurel, etc., overspread all the low -ground of France, as far north at least as Paris.... It was under such -conditions," continues Geikie, "that the elephants, rhinoceroses, and -hippopotamuses, and the vast herds of temperate cervine and bovine -species ranged over Europe, from the shores of the Mediterranean up to -the latitude of Yorkshire, and probably even farther north still; and -from the borders of Asia to the Western Ocean. Despite the presence of -numerous fierce carnivora--lions, hyenas, tigers, and others--Europe at -that time, with its shady forests, its laurel-margined streams, its broad -and deep-flowing rivers, a country in every way suited to the needs of a -race of hunters and fishers--must have been no unpleasant habitation for -palæolithic man. - -"This, however, is only one side of the picture. There was a time when -the climate of Pleistocene Europe presented the strongest contrast to -those genial conditions--a time when the dwarf birch of the Scottish -Highlands, and the arctic willow, with their northern congeners, grew -upon the low grounds of middle Europe. Arctic animals, such as the musk -sheep and the reindeer, lived then, all the year round, in the south of -France; the mammoth ranged into Spain and Italy; the glutton descended to -the shores of the Mediterranean; the marmot came down to the low grounds -at the foot of the Apennines; and the lagomys inhabited the low-lying -maritime districts of Corsica and Sardinia. The land and fresh-water -shells of many Pleistocene deposits tell a similar tale; boreal, high -alpine, and hyperborean forms are characteristic of these accumulations -in central Europe; even in the southern regions of our continent the -shells testify to a former colder and wetter climate."[DO] - -[Footnote DO: Prehistoric Europe, p. 67.] - -In Mr. Geikie's view these facts indicate two Glacial periods, with an -intervening epoch of mild climate. In the opinion of others they are -readily explainable by the coming on and departure of a single Ice age, -with its various minor episodes. - - -_Earliest Remains of Man on the Pacific Coast of North America._ - -Most interesting evidence concerning the antiquity of man in America, -and his relation to the Glacial period, has come from the Pacific coast. -During the height of the mining activity in California, from 1850 to -1860, numerous reports were rife that human remains had been discovered -in the gold-bearing gravel upon the flanks of the Sierra Nevada -Mountains. These reports did not attract much scientific attention until -they came to relate to the gravel deposits found deeply buried beneath -a flow of lava locally known as the Sonora or Tuolumne Table Mountain. -This lava issued from a vent near the summit of the mountain-range, and -flowed down the valley of the Stanislaus River for a distance of fifty or -sixty miles, burying everything in the valley beneath it, and compelling -the river to seek another channel. The thickness of the lava averages -about one hundred feet, and so long a time has elapsed since the eruption -that the softer strata on either side of the valley down which it flowed -have been worn away to such an extent that the lava now rises nearly -everywhere above the general level, and has become a striking feature in -the landscape, stretching for many miles as a flat-topped ridge about -half a mile in width, and presenting upon the sides a perpendicular face -of solid basalt for a considerable distance near the lower end of the -flow. - -[Illustration: Fig. 94.--Section across Table Mountain, Tuolumne County, -California: _L_, lava; _G_, gravel; _S_, slate; _R_, old river-bed; _R'_, -present river-bed.] - -[Illustration: Fig. 95.--Calaveras Skull. (From Whitney.)] - -It was under this mountain of lava that the numerous implements and -remains of man occurred which were reported to Professor J. D. Whitney -when he was conducting the geological survey of California between 1860 -and 1870. The implements consisted of stone mortars and pestles, suitable -for use in grinding acorns and other coarse articles of food. There were, -however, some rude articles of ornament. In one of the mining shafts -penetrating the gravel underneath Table Mountain, near Sonora, there was -reported to have been discovered, in 1857, a human jawbone, one portion -of which was sent by responsible parties to the Boston Society of Natural -History, and another part to the Philadelphia Academy of Sciences, in -whose collections the fragments can now be seen. - -Interest reached a still higher pitch when, in 1860, an entire human -skull with some other human bones was reported to have been discovered -under this same lava deposit, a few miles from Sonora, at Altaville, in -Calaveras County, and hence known as the "Calaveras skull." Persistent -efforts were made soon after to discredit the genuineness of this -discovery. Bret Harte showered upon it the shafts of his ridicule, and -various other persons gave currency to the story that the whole report -originated in a joke played by the miners upon unsuspecting geologists. -These attacks were so successful that many conservative archæologists and -men of science have refused to accept the skull as genuine. - -Recent events, however, have brought such additional evidence[DP] to the -support of this discovery that it would seem unreasonable any longer to -refuse to credit the testimony. At the meeting of the Geological Society -of America, at Washington, in January, 1891, Mr. George P. Becker, of -the United States Geological Survey, who for some years has had charge -of investigations relating to the gold-bearing gravels of the Pacific -coast, presented the affidavit of Mr. J. H. Neale, a well-known mining -engineer of unquestionable character, stating that he had taken a stone -mortar and pestle, together with some spear-heads (which through Mr. -Becker he presented to the Society), from undisturbed strata of gravel -underneath the lava of Table Mountain, near Rawhide Gulch, a few miles -from Sonora. At the same meeting Mr. Becker presented a pestle which -Mr. Clarence King, the first director of the United States Geological -Survey, took with his own hands out of undisturbed gravel under this same -lava deposit, near Tuttletown, a mile or two from the preceding locality -mentioned. - -[Footnote DP: See Bulletin Geological Society of America, 1891, pp. -189-200.] - -I was so fortunate, also, as to be able to report to the Society at the -same meeting the discovery, in 1887, of a small stone mortar by Mr. C. -McTarnahan, the assistant surveyor of Tuolumne County. This mortar was -found by Mr. McTarnahan in the Empire mine, which penetrates the gravel -underneath Table Mountain, about three miles from Sonora, and not far -from the other localities above mentioned. The place where the mortar was -found is about one hundred and seventy-five feet in from the edge of the -superincumbent lava, which is here about one hundred feet in thickness. -At my request, this mortar was presented by its owner, Mrs. M. J. Darwin, -to the Western Reserve Historical Society of Cleveland, Ohio, in whose -collection it can now be seen. - -These three independent instances, each of them authenticated by the best -of evidence, have such cumulative force that probably few men of science -will longer stand out against it. - -Associated with these discoveries, there is to be mentioned another, -which was brought to my notice by Mr. Charles Francis Adams in October, -1889.[DQ] This was a miniature clay image of a female form, about one -inch and a half in length, and beautifully formed, which was found, in -August, 1889, by Mr. M. A. Kurtz, while boring an artesian well at Nampa, -Ada County, Idaho. The strata passed through included, near the surface, -fifteen feet of lava. Underneath this, alternating beds of clay and -quicksand occurred to a depth of three hundred and twenty feet, where -there appeared indications of a former surface soil lying just above the -bed-rock, from which the clay image was brought up in the sand-pump. - -[Footnote DQ: See Proceedings Boston Society Natural History, January, -1890, and February, 1891.] - -[Illustration: Fig. 96.--Three views of Nampa image drawn to scale. The -middle one is from a photograph.] - -I devoted the summer of 1890 to a careful study of the lava deposits both -in Idaho and in California, with a view to learning their significance -with reference to these discoveries. The main facts brought to light by -this investigation are that in the Snake River Valley, Idaho, there are -not far from twelve thousand square miles of territory covered with a -continuous stratum of basaltic lava, extending nearly across the entire -diameter of the State from east to west. Nampa, where the miniature -image was discovered, is within five miles of the western limit of this -lava-flow, and where it had greatly thinned out. The relative age of the -lava is shown by its relation to Tertiary beds of shale and sandstone, -containing numerous fossils of late Pliocene species. These are overlaid -in this vicinity by the lava, thus determining its post-Tertiary -character. Examination with reference to the more precise determination -of age reveals channels of erosion formed since the lava-flow took -place, which, when studied sufficiently, will probably lead to valuable -approximate results. At present I can only say that the amount of -erosion since the lava eruptions of western Idaho is not excessive, and -very likely may be brought within a period of from ten thousand to twenty -thousand years. The enormous erosion in the cañon of the Snake River, -near Shoshone Falls, in central Idaho, is doubtless of a much earlier -date than that in the Boise River, near Nampa. - -[Illustration: Fig. 97.--Map showing Pocatello, Nampa, and the valley of -Snake River.] - -The disturbances created in this part of the valley by the bursting of -the barriers between the glacial Lake Bonneville and the Snake River, -already described (see above, page 233), have not been worked out. There -can be no doubt, however, that interesting results will come to light -in connection with the problem; for Pocatello, the point at which the -_débâcle_ reached the Snake River plain, is about 2,000 feet higher than -Nampa, and 350 miles distant, and the water must have poured into the -valley faster than the river in its upper portion could have discharged -it. By just what channels the mighty current worked down to the lower -levels on the western borders of the State it would be most interesting -as well as instructive to know. - -A study of the situation in Tuolumne and Calaveras Counties, California, -reveals a state of things closely resembling, in important respects, -that in western Idaho. At first sight the impression is made that an -immense lapse of time must have occurred since the volcanic eruption -which furnished the lava of Table Mountain. The Stanislaus River flows -in a channel of erosion a thousand feet or more lower than the ancient -channel filled by lava, and in two or three places cuts directly across -it. An immense amount of time, also, would seem to be required to permit -the smaller local streams to have worn away so much of the sides of the -ancient valley as to allow the lava deposit now so continuously to rise -above the general surface. Still, the question of absolute time cannot -be considered separately without much further study. It is by no means -certain that, when the lava-stream poured down the mountain, it always -followed the lowest depressions; but at certain points it may have been -dammed up in its course by its own accumulations so as to be turned off -into what was then an ancient abandoned channel. - -[Illustration: Fig. 98.--Section along the line, north and south: -_r' r'_, old river-beds; _r r_, present river-beds; _L_, lava; -_sl_, slate.] - -The forms of animal and vegetable life with which the remains of man -under Table Mountain are associated, are, indeed, to a considerable -extent, species now extinct in California, and some of them no longer -exist anywhere in the world. But a suggestion of Professor Prestwich, -in England, made with reference to the extinct forms of life associated -with human remains in the glacial deposits in Europe, is revived by -Mr. Becker, of the Geological Survey, with reference to the California -discoveries; his inference being, not that man is so extremely ancient -in California, but that many of these plants and animals have continued -to a more recent date than has ordinarily been supposed. - -The connection of these lava-flows on the Pacific coast with the Glacial -period is unquestionably close. For some reason which we do not fully -understand, the vast accumulation of ice in North America during the -Glacial period is correlated with enormous eruptions of lava west of the -Rocky Mountains, and, in connection with these events, there took place -on the Pacific coast an almost entire change in the plants and animals -occupying the region. Mr. Warren Upham is of the opinion that on the -Pacific coast they lingered much later than in the region east of the -Rocky Mountains. Indeed, it is pretty certain that not many centuries -have elapsed since the glacial phenomena of the Sierra Nevada Mountains -were much more pronounced than they are at the present time, and it is -equally certain that there have been vast eruptions of lava in California -within three hundred years. - -From these data, therefore, Mr. Becker has real foundation for his -suggestion that perhaps in the Glacial period California was a kind of -health resort for Pliocene animals, as it is at the present time for man; -or, at any rate, that the later date of the accumulations permitted the -animals to survive there much longer than in the region east of the Rocky -Mountains. - -Further discussion of the preceding facts will profitably be deferred -until, in the next two chapters, the questions of the cause and date of -the Glacial period have been considered. - - - - -CHAPTER IX. - -THE CAUSE OF THE GLACIAL PERIOD. - - -In searching for the cause of the Glacial period, it is evident that we -must endeavor to find conditions which will secure over the centre of the -glaciated area either a great increase of snow-fall or a great decrease -in the mean annual temperature, or both of these conditions combined in -greater or less degree. As can be seen, both from the nature of the case -and from the unglaciated condition of Siberia and northern Alaska, a low -degree of temperature is not sufficient to produce permanent ice-fields. -If the snow-fall is excessively meagre, even the small amount of heat in -an arctic summer will be sufficient to melt it all away. - -From the condition of Greenland, however, it appears that a moderate -amount of precipitation where it is chiefly in the form of snow may -produce enormous glaciers if at the same time the average temperature -is low. In southeastern Alaska, on the other hand, the glaciers are of -enormous size, though the mean annual temperature is by no means low, -for there the great amount of snow-fall amply compensates for the higher -temperature. - -Snow stores the cold and keeps it in a definite place. If the air becomes -chilled, circulation at once sets in, and the cold air is transferred to -warmer regions; but if there is moisture in the air, so that snow forms, -the cold becomes locked up, as it were, and falls to the earth. - -The amount of cold thus locked up in snow is enormous. To melt one -cubic foot of ice requires as much heat as would raise the temperature -of a cubic foot of water 176° Fahrenheit. To melt a "layer of ice only -one inch and a half thick would require as much heat as would raise a -stratum of air eight hundred feet thick from the freezing-point to the -tropical heat of 88° Fahrenheit." It is the slowness with which ice melts -which enables it to accumulate as it does, both in winter and upon high -mountains and in arctic regions. Captain Scoresby relates that when near -the north pole the sun would sometimes be so hot as to melt the pitch on -the south side of his vessel, while water was freezing on the north side, -in the shade, owing to the cooling effect of the masses of ice with which -he was surrounded. - -Thus it will appear that a change in the direction of the moist winds -blowing from the equator towards the poles might produce a Glacial -epoch. If snow falls upon the ocean it cools the water, but through the -currents, everywhere visible in the sea, the temperature in the water in -the different parts soon becomes equalized. If, however, the snow falls -upon the land, it must be melted by the direct action of the sun and -wind upon the spot where it is. If the heat furnished by these agencies -is not sufficient to do it year by year, there will soon be such an -accumulation that glaciers will begin to form. It is clear, therefore, -that the conditions producing a Glacial period are likely to prove very -complicated, and we need not be surprised if the conclusions to which we -come are incapable of demonstration. - -Theories respecting the cause of the Glacial period may be roughly -classified as astronomical and geological. Among the astronomical -theories, one which has sometimes been adduced is that the solar system -in its movement through space is subjected to different degrees of heat -at different times. According to this theory, the temperate climate -which characterised the polar regions during the Tertiary period, and -continued up to the beginning of the Glacial epoch, was produced by the -influence of the warmer stretches of space through which the whole solar -system was moving at that time; while the Glacial period resulted from -the influence upon the earth of the colder spaces through which the -system subsequently moved. - -While it is impossible absolutely to disprove this hypothesis, it labors -under the difficulty of having little positive evidence in its favor, -and thus contravenes a fundamental law of scientific reasoning, that we -must have a real cause upon which to rest our theories. In endeavouring -to explain the unknown, we should have something known to start with. -But in this case we are not sure that there are any such variations in -the temperature of the space through which the solar system moves. This -theory, therefore, cannot come in for serious consideration until all -others have been absolutely disproved. As we shall also more fully see, -in the subsequent discussion, the distribution of the ice during the -Glacial period was not such as to indicate a gradual extension of it from -the north pole, but rather the accumulation upon centres many degrees to -the south. - -Closely allied with the preceding theory is the supposition broached -by some astronomers that the sun is a variable star, dependent to some -extent for its heat upon the impact of meteorites, or to the varying -rapidity with which the contraction of its volume is proceeding. - -It is well known that when two solid bodies clash together, heat is -produced proportionate to the momentum of the two bodies. In other -words, the motion which is arrested is transformed into heat. Mr. Croll, -in his last publication[DR] upon the subject, ingeniously attempted to -account for the gaseous condition of the nebulæ and the heat of the sun -and other fixed stars by supposing it to be simply transformed motion. -According to this theory, the original form of force imparted to the -universe was that exerted in setting in motion innumerable dark bodies, -which from time to time have collided with each other. The effects of -such collisions would be to transform a large amount of motion into -heat and its accompanying forms of molecular force. The violence of the -compact of two worlds would be so great as to break them up into the -original atoms of which they are composed, and the heat set free would -be sufficient to keep the masses in a gaseous condition and cause them -to swell out into enormous proportions. From that time on, as the heat -radiated into space, there would be the gradual contraction which we -suppose is going on in all the central suns, accompanied, of course, with -a gradual decline of the heat-energy in the system. - -[Footnote DR: Stellar Evolution and its Relation to Geological Time.] - -Now, it is well known that the earth and the solar system in their -onward progress pass through trains of meteorites. The tails of some of -the comets are indeed pretty clearly proved to be streams of ponderable -matter, through which, from time to time, the minor members of the solar -system plunge, and receive some accession to their bulk and weight. The -shooting-stars, which occasionally attract our attention in the sky, -mark the course of such meteorites as they pass through the earth's -atmosphere, and are heated to a glow by the friction with it. It has been -suggested, therefore, that the sun itself may at times have its amount -of heat sensibly affected by such showers of meteorites or asteroids. -Upon this theory the warm period of the Tertiary epoch, for instance, -may have been due to the heat temporarily added to the sun by impact -with minor astronomical bodies. When, afterwards, it gradually cooled -down, receiving through a long period no more accessions of heat from -that source, the way was prepared for the colder epoch of the Glacial -period, which, in turn, was dispelled by fresh showers of meteorites -upon the sun, sufficient to produce the amelioration of climate which we -experience at the present time. - -As intimated, this theory is closely allied to the preceding, the -principal difference being that it limits the effects of the supposed -cause to the solar system, and looks to our sun as the varying source of -heat-supply. It has the advantage over that, however, of possessing a -more tangible _vera causa_. Meteorites, asteroids, and comets are known -to be within this system, and have occasional collisions with other -members of it. But the principal objection urged against the preceding -theory applies here, also, with equal force. The accumulations of ice -during the Glacial period were not determined by latitude. In North -America the centre of accumulation was south of the Arctic Circle--a fact -which points clearly enough to some other cause than that of a general -lowering of the temperature exterior to the earth. - -The same objections would bear against the theory ably set forth by Mr. -Sereno E. Bishop, of Honolulu, which, in substance, is that there may -be considerable variability in the sun's emission of heat, owing to -fluctuations in the rate of the shrinkage of its diameter, brought about -by the unequal struggle between the diminishing amount of heat in the -interior and the increasing force of the gravitation of its particles, -and by the changes in the enveloping atmosphere of the sun, which, like -an enswathing blanket, arrests a large portion of the radiant heat from -the nucleus, and is itself evidently subject to violent movements, some -of which seem to carry it down to the sun's interior. Unknown electrical -forces, he thinks, may also combine to add an element of variability. -These supposed changes may be compared to those which take place upon -the surface of the earth when, at irregular intervals, immense sheets of -lava, like those upon the Pacific coast of North America, are exuded in a -comparatively brief time, to be succeeded by a long period of rest. The -heat thus brought to the surface of the earth would add perceptibly to -that radiated from it into space in ordinary times. Something similar to -this upon the sun, it is thought, might produce effects perceptible upon -the earth, and account for alternate periods of heat and cold. - -A fourth astronomical theory is that there has been a shifting of the -earth's axis; that at the time of the Glacial period the north pole, -instead of being where it now is, was somewhere in the region of central -Greenland. This attractive theory has been thought worthy of attention -by President T. C. Chamberlin and by Professor G. C. Comstock,[DS] but -it likewise labours under a twofold difficulty: First, the shifting of -the poles observed (450 feet per year) is too slight to have produced the -changes within any reasonable time, and it is not likely to have been -continuous for a long period. But still more fatal to the theory is the -fact that the warm climate preceding the Glacial period seems to have -extended towards the present north pole upon every side; a temperate -flora having been found in the fossil plants of the Tertiary beds in -Greenland and northern British America, as well as upon Nova Zembla and -Spitzbergen. - -[Footnote DS: See papers by these gentlemen read at the meeting of the -American Association for the Advancement of Science, in Washington, in -August, 1891. Professor Comstock's paper appeared in the American Journal -of Science for January, 1893.] - -A fifth astronomical theory, and one which has of late years been -received with great favour, is that so ably advocated by the late Dr. -James Croll and by Professor James Geikie. Following the suggestions -of the astronomer Adhémar, these writers have attempted to show that -not only one Glacial epoch, but a succession of such epochs, has been -produced in the world by the effect of the changes which are known to -have taken place in the eccentricity of the earth's orbit when combined -with the precession of the equinoxes--another calculable astronomical -cause. - -[Illustration: Fig. 99.--Diagram showing effect of precession: _A._ -condition of things now; _B._ as it will be 10,500 years hence. The -eccentricity is of course greatly exaggerated.] - -It is well known that the earth's orbit is elliptical; that is, it is -longer in one direction than in the other, so that the sun is one side -of the centre. During the winter of the northern hemisphere the earth -is now about three million miles nearer the sun than in the summer; but -the summer makes up for this distance by being about seven days longer -than the winter. Through the precession of the equinoxes this state of -things will be reversed in ten thousand five hundred years; at which time -we shall be nearer the sun during our northern summer, and farther away -in winter, our winter then being also longer than our summer. Besides, -through the unequal attraction of the planets the eccentricity of the -earth's orbit periodically increases and diminishes, so that there have -been periods when the earth was ten million five hundred thousand miles -farther from the sun in winter than in summer; at which times, also, -the winter was nearly twenty-eight days longer than the summer. Such an -extreme elongation of the earth's orbit occurred about two hundred and -fifty thousand years ago. - -It is easy to assume that such a change in astronomical conditions would -produce great effects upon the earth's climate; and equally easy to -connect with those effects the vast extension of ice during the Glacial -period. Since, also, this period of extreme eccentricity terminated -only eighty thousand years ago, the close of the Glacial period would, -perhaps, upon Mr. Croll's theory, be comparatively a recent event; for -if the secular summer of the earth's eccentricity lags relatively as -far behind the secular movements as the annual summer does behind the -vernal equinox, we should, as Professor Charles H. Hitchcock suggests, -have to place the complete breaking up of the Ice period as late as forty -thousand years ago.[DT] - -[Footnote DT: Geology of New Hampshire, vol. iii, p.327.] - -We have no space to indicate, as it deserves, the comparative merits -and demerits of this ingenious theory. It would, however, be a great -calamity to have geologists accept it without scrutiny. It is, indeed, -a part of the business of geologists to doubt such theories until they -are verified by a thorough examination of all accessible _terrestrial_ -evidence bearing upon the subject. There is no reason to question the -reality of the variations in the relative positions of the earth and the -sun assumed by Mr. Croll; though there may be serious doubt whether the -effects of those changes upon climate would be all that is surmised, -since equal amounts of heat would fall upon the earth during summer, -whether made longer or shorter by the cause referred to. During the short -summers the earth is so much nearer the sun that it receives each season -absolutely as much heat as it does during the longer summers, when it -is so much farther away from the sun. Thus the theory rests at last upon -the question what would become of the heat reaching the earth in these -differing conditions. It is plausibly urged by Mr. Croll that when a -hemisphere of the earth is passing through a period of long winters the -radiation of heat will be so excessive that the temperature would fall -much below what it would during the shorter winters; and so ice and snow -would accumulate far beyond the usual amount. It is also supposed that -the effect of the summer's sun in melting the ice during the short summer -would be diminished through natural increase of the amount of foggy and -cloudy weather. - -Adhémar's theory is supposed by Sir Robert Ball, Royal Astronomer of -Ireland, to be considerably re-enforced by a discovery which he has made -concerning the distribution of heat upon the earth during the seasons -culminating in the summer and winter solstices. Croll had assumed, -on the authority of Herschel, that a hemisphere of the earth during -the longer winter in aphelion would receive the same actual amount of -heat which would fall upon it during the shorter summer in perihelion; -whereas, according to Dr. Ball's discovery, "of the total amount of heat -received from the sun on a hemisphere of the earth in the course of a -year, sixty-three per cent is received during the summer and thirty-seven -per cent during the winter."[DU] When, therefore, the summers occur in -perihelion the heat is more intense than Croll had supposed, and, at -the same time, the winters occurring in aphelion are more deficient in -heat than he had assumed. This discovery of Dr. Ball will not, however, -materially affect the discussion of Croll's theory upon its inherent -merits, since it is simply an intensification of the causes invoked by -him. We will therefore let it stand or fall in the light of the general -considerations hereafter to be adduced. - -[Footnote DU: Cause of an Ice Age, p. 90.] - -The aid of theoretical consequent changes in the volume of the Gulf -Stream, and in the area of the trade-winds, has also to be invoked by -Mr. Croll. The theory likewise receives supposed confirmation from facts -alleged concerning the present climate of the southern hemisphere which -is passing through the astronomical conditions thought to be favourable -to its glaciation. The antarctic continent is completely enveloped in -ice, even down to the sixty-seventh degree of latitude. A few degrees -nearer the pole Sir J. C. Boss describes the ice as rising from the water -in a precipitous wall one hundred and eighty feet high. In front of such -a wall, and nearly twenty degrees from the south pole, this navigator -sailed four hundred and fifty miles! Voyagers, in general, are said to -agree that the summers of the antarctic zone are much more foggy and cold -than they are in corresponding latitudes in the northern hemisphere; and -this, even though the sun is 3,000,000 miles nearer the earth during the -southern summer than it is during the northern. - -Another direction from which evidence is invoked in confirmation of Mr. -Croll's theory is the geological indications of successive Glacial epochs -in times past. If there be a recurring astronomical cause sufficient of -itself to produce Glacial periods, such periods should recur as often as -the cause exists; but glaciation upon the scale of that which immediately -preceded the historic era could hardly have occurred in early geological -time without leaving marks which geologists would have discovered. Were -the "till" now covering the glaciated region to be converted into rock, -its character would be unmistakable, and the deposit is so extensive that -it could not escape notice. - -In his inaugural address before the British Association in 1880, -Professor Ramsey, Director-General of the Geological Survey of Great -Britain, presented a formidable list of glacial observations in -connection with rocks of a remote age.[DV] Beginning at the earliest -date, he cites Professor Archibald Geikie, one of the most competent -judges, as confident that the rounded knobs and knolls of Laurentian -rocks exposed over a large region in northwestern Scotland, together -with vast beds of coarse, angular, unstratified conglomerates, are -unquestionable evidences of glacial action at that early period. Masses -of similar conglomerates, resembling consolidated glacial boulder-beds, -occur also in the Lower Silurian formation at Corswall, England. In -Dunbar, Scotland, Professor Forbes also found, in formations of but -little later age than the Coal period, "brecciated conglomerates, -consisting of pebbles and large blocks of stone, generally angular, -embedded in a marly paste, in which some of the pebbles are as well -scratched as those found in medial moraines." In formations of -corresponding antiquity the geologists of India have found similar -boulder-beds, in which some of the blocks are polished and striated. - -[Footnote DV: Nature (August 26, 1880), vol. xxii, pp. 388, 389.] - -Still, this evidence is less abundant than we should expect, if there had -been the repeated Glacial epochs supposed by Mr. Croll's astronomical -theory; and it is by no means impossible that the conglomerates of -scratched stones described by Professor Ramsey in Great Britain, and -by Messrs. Blandford and Medlicott in India, may have resulted from -local glaciers coming down from mountain-chains which have been since -removed by erosion or subsidence. We are not aware that any incontestable -evidence has been presented in America of any glaciation previous to that -of _the_ Glacial period. - -Upon close consideration, also, it appears that Mr. Croll's theory has -not properly taken into account the anomalous distribution of heat which -we actually find to take place on the surface of the earth. He has done -good service in showing what an enormous transfer of heat there is -from the southern to the northern Atlantic by means of the Gulf Stream, -estimating that the heat conveyed by the Gulf Stream into the Atlantic -Ocean is equal to one fifth of all possessed by the waters of the North -Atlantic; or to the heat received from the sun upon a million and a half -square miles at the equator, or two million square miles in the temperate -zone. "The stoppage of the Gulf Stream would deprive the Atlantic of -77,479,650,000,000,000,000 foot-pounds of energy in the form of heat per -day." - -Among the objections which bear against this ingenious theory is one -which will appear with great force when we come to discuss the date of -the Glacial period, when we shall show that even Professor Hitchcock's -supposition that the lingering effects of the last great eccentricity of -the earth's orbit, continued down to forty thousand years ago, is not -sufficient to account for the recentness of the close of the period as -shown by abundant geological evidence. It is certainly not more than ten -or fifteen thousand years ago that the ice finally melted off from the -Laurentian highlands; while on the Pacific coast the period of glaciation -was still more recent. - -From inspection of the accompanying map the main point of Mr. Croll's -reasoning may be understood. It will be seen that the direction of the -currents in the central Atlantic is largely determined by the contour of -the northeastern coast of South America. From some cause the southeast -trade-winds are stronger than the northeast, and their force is felt in -pushing the superficial currents of warm water farther north than Cape -St. Roque, the eastern extremity of Brazil. As the direction of the South -American coast trends rapidly westward from this point to the Isthmus of -Panama, the resultant of the forces is a strong current northwestward -into the _cul-de-sac_ of the Gulf of Mexico, from which there is only the -one outlet between Cuba and the peninsula of Florida. Through this the -warm water is forced into the region where westerly winds prevail, and -spreads its genial influence far to the northward, modifying the climate -of the British Isles, and even of far-off Norway. - -[Illustration: Fig. 100.--Map showing course of currents in the Atlantic -Ocean: _b_ and _b'_ are currents set in motion by opposite trade-winds; -meeting, they produce the equatorial current, which divides into _c_ and -_c'_, continuing on as _a_ and _a'_ and _e_.] - -But why are the southeast trade-winds of the Atlantic stronger than -the northeast? The ultimate reason, of course, is to be found in the -fact that the northern hemisphere is warmer than the southern. The -atmosphere over the northern-central portion of the Atlantic region is -more thoroughly rarefied by the sun's heat than is that over the region -south of the equator. The strong southeast trades are simply the rush of -atmosphere from the South Atlantic to fill the vacuum caused by the heat -of the sun north of the equator. - -But, again, why is this? Because, says Mr. Croll, we are now in that -stage of astronomical development favourable to the increased warmth -of the northern hemisphere. In the northern hemisphere the summers are -longer than the winters. Perihelion occurs in winter and aphelion in -summer. This is the reason why the North Atlantic is warmer than the -South Atlantic, and why the trade-winds of the south are drawn to the -north of the equator. Ten thousand five hundred years ago, however, the -conditions were reversed, and the greater rarefaction of the atmosphere -would have taken place south of the equator, thus drawing the trade-winds -in that direction. - -By again inspecting the map, one will see how far-reaching the effect on -the climate of northern countries this change in the prevalences of the -trades would have been. Then, instead of having the northwest current -leading along the northeast coast of South America into the Gulf of -Mexico augmented by the warm currents circulating south of the equator, -the warm currents of the north would have been pushed down so far that -they would augment the current running to the southwest beyond Cape St. -Roque, along the southeast shore of South America; thus the northern -portion of the Atlantic, instead of robbing the southern portion of -heat, would itself be robbed of its warm currents to contribute to the -superfluous heat of the South Atlantic. - -This theory is certainly very ingenious. There is a weak point in -it, however. Mr. Croll assumes that when the winters of the northern -hemisphere occur in aphelion, they must necessarily be colder than now. -But, evidently, this assertion implies a fuller knowledge than we possess -of the laws by which the heat received from the sun is distributed over -the earth. - -For it appears from observation that the equator is by no means so -hot now as, theoretically, it ought to be, and that the arctic regions -are not so cold as, according to theory, they should be, and this in -places which could not be affected by oceanic currents. For example, -at Iquitos, on the Amazon, only three hundred feet above tide, three -degrees and a half south of the equator, and more than a thousand miles -from the Atlantic (so that ocean-currents cannot abstract the heat from -its vicinity), the mean yearly temperature is but 78° Fahr.; while at -Verkhojansk, in northeast Siberia, which is 67° north of the equator, and -is situated where it is out of the reach of ocean-currents, and where -the conditions for the radiation of heat are most favourable, and where, -indeed, the winter is the coldest on the globe (January averaging--56° -Fahr.), the mean yearly temperature is two degrees and a half above zero; -so that the difference between the temperature upon the equator and that -at the coldest point on the sixty-seventh parallel is only about 75° -Fahr.; whereas, if temperature were in proportion to heat received from -the sun, the difference ought to be 172°. Again, the difference between -the actual January temperature on the fiftieth parallel and that upon the -sixtieth is but 20° Fahr., whereas, the quantity of solar heat received -on the fiftieth parallel during the month of January is three times that -received upon the sixtieth, and the difference in temperature ought to be -about 170° Fahr. upon any known law in the case. - -Woeikoff, a Russian meteorologist, and one of the ablest critics of Mr. -Croll's theory, and to whom we are indebted for these facts, ascribes -the greater present warmth of the northern Atlantic basin, not to the -astronomical cause invoked by Mr. Croll, but to the relatively small -extent of sea in the middle latitudes of the northern hemisphere. The -extent and depth of the oceans of the southern hemisphere would of -themselves give greater steadiness and force to its trade-winds, and -lead to a general lowering of the temperature; so that it is doubtful -if the astronomical causes introduced by Mr. Croll, even with Dr. -Ball's re-enforcement, would produce any appreciable effect while the -distribution of land and water remains substantially what it is at the -present time. - -Still another variation in the astronomical theory has been set forth -and defended by Major-General A. W. Drayson, F. R. A. S., instructor -in the Royal Military School at Woolwich, England. He contends that -what has been called the precession of the equinoxes, and supposed to -be "a conical movement of the earth's axis in a circle around a point -as a centre, from which it continually decreases its distance,"[DW] is -really a second rotation of the earth about its centre. As a consequence -of this second rotation, he endeavours to show that the inclination of -the earth's axis varies as much as 12°; so that, whereas the Arctic and -Antarctic Circles and the tropics extend to only about 23° from the poles -and the equator, respectively, about thirteen thousand five hundred years -ago they extended more than 35°; thus bringing the frigid zones in both -cases 12° nearer the equator than now. This, he contends, would have -produced the Glacial period at the time now more generally assigned to it -by direct geological evidence. - -[Footnote DW: Untrodden Ground in Astronomy and Geology, p. 26.] - -The difficulty with this theory, even if the mathematical calculations -upon which it is based are correct, would be substantially the same as -those already urged against that of Mr. Croll. It is specially difficult -to see how General Drayson would account for the prolonged temperate -climate in high northern latitudes during the larger part of the Tertiary -epoch. - -It will be best to turn again to the map to observe the possible effect -upon the Gulf Stream of a geological event of which we have some definite -evidence, and which is adduced by Mr. Upham and others as one of the -important probable causes of the Glacial period, namely, the subsidence -of the Isthmus of Panama and the adjacent narrow neck of land connecting -North with South America. It will be seen at a glance that a subsidence -sufficient to allow the northwest current of warm water, pushed by the -trade-winds along the northeast shore of South America, to pass into -the Pacific Ocean, instead of into the Gulf of Mexico, would be a cause -sufficient to produce the most far-reaching results; it would rob the -North Atlantic of the immense amount of heat and moisture now distributed -over it by the Gulf Stream, and would add an equal amount to the northern -Pacific Ocean, and modify to an unknown extent the distribution of heat -and moisture over the lands of the northern hemisphere. - -The supposition that a subsidence of the Isthmus of Panama was among -the contributing causes of the Glacial period has been often made, but -without any positive proof of such subsidence. From evidence which -has recently come to light, however, it is certain that there has -actually been considerable subsidence there in late Tertiary if not in -post-Tertiary times. This evidence is furnished by Dr. G. A. Maack and -Mr. William M. Gabb in their report to the United States Government in -1874 upon the explorations for a ship-canal across the isthmus, and -consists of numerous fossils belonging to existing species which are -found at an elevation of 150 feet above tide. As the dividing ridge is -more than 700 feet above tide, this does not positively prove the point, -but so much demonstrated subsidence makes it easy to believe, in the -absence of contradictory evidence, that there was more, and that the -isthmus was sufficiently submerged to permit a considerable portion of -the warm equatorial current which now passes northward from the Caribbean -Sea and the Gulf of Mexico to pass into the Pacific Ocean. - -[Illustration: Fig. 101.--Map showing how the land clusters about the -north pole.] - -An obvious objection to the theory of a late Tertiary or post-Tertiary -subsidence of the Isthmus of Panama presents itself in the fact that -there is at present a complete diversity of species between the fish -inhabiting the waters upon the different sides of the isthmus. If -there had been such a subsidence, it seems natural to suppose that -Atlantic species would have migrated to the Pacific side and obtained -a permanent lodgment there, and that Pacific species would have found -a congenial home on the Atlantic side. It must be confessed that this -is a serious theoretical difficulty, but perhaps not insuperable. For -it is by no means certain that colonists from the heated waters of the -Caribbean Sea would become so permanently established upon the Pacific -side that they could maintain themselves there upon the re-establishment -of former conditions. On the contrary, it seems reasonable to suppose -that upon the re-elevation of the isthmus the northern currents, which -would then resume their course, would bring back with them conditions -unfavourable to the Atlantic species, and favourable to the competing -species which had only temporarily withdrawn from the field, and which -might now be better fitted than ever to renew the struggle with their -Atlantic competitors. It is by no means certain, therefore, that with -the re-establishment of the former conditions there would not also be a -re-establishment of the former equation of life upon the two sides of the -isthmus. - -Mr. Upham's theory involves also extensive elevations of land in the -northern part of America; in this respect agreeing with the opinions -early expressed by Professors J. D. Dana and J. S. Newberry. Of the -positive indications of such northward elevations of land we have already -spoken when treating in a previous chapter of the fiords and submerged -channels which characterise northern Europe and both the eastern and -the western coasts of North America. But in working out the problem the -solution is only half reached when we have got the Gulf Stream into -the Pacific Ocean, and the land in the northern part of the continents -elevated to some distance above its present level. There is still the -difficulty of getting the moisture-laden currents from the Pacific Ocean -to carry their burdens over the crest of the Sierra Nevada and Rocky -Mountains and to deposit them in snow upon the Laurentian highlands. -An ingenious supplement to the theory, therefore, has been brought -forward by Professor Carpenter, who suggests that the immense Tertiary -and post-Tertiary lava-flows which cover so much of the area west of -the Rocky Mountains were the cause of the accumulations of snow which -formed the Laurentide Glacier. This statement, which at first seems so -paradoxical as to be absurd, appears less so upon close examination. - - -The extent of the outflows of lava west of the Rocky Mountains is almost -beyond comprehension. Literally, hundreds of thousands of square miles -have been covered by them to a depth in many places of thousands of feet. -These volcanic eruptions are mostly of late date, beginning in the middle -of the Tertiary and culminating probably about the time of the maximum -extent of the Laurentide Glacier. Indeed, so nearly contemporaneous was -the growth of the Laurentide Glacier with these outflows that Professor -Alexander Winchell had, with a good deal of plausibility, suggested that -the outflows of the eruptions of lava were caused by the accumulation -of ice over eastern British America. His theory was that the three -million cubic miles of ice which is proved to have been abstracted from -the ocean and piled up over that area was so serious a disturbance of -the equilibrium of the earth's crust that it caused great fissures to -be opened along the lines of weakness west of the Rocky Mountains, and -pressed the liquid lava out, as the juice is pressed out of an orange in -one place by pressing upon the rind in another. - -Professor Carpenter's view is the exact reverse of Professor Winchell's. -Going back to those orographic changes which produced the lava-flows -and the elevation of the northern part of British America, he thinks -the problem of getting the moisture transferred from the Pacific Ocean -to the Canadian highlands is solved by the lava-flows west of the Rocky -Mountains. This immense exudation of molten matter was accompanied by an -enormous liberation of heat, which must have produced significant changes -in the meteorological conditions. - -The moisture of the atmosphere is precipitated by means of the -condensation connected with a lowering of its temperature. Ordinarily, -therefore, when moist winds from an oceanic area pass directly over a -lofty mountain-chain, the precipitation takes place immediately, and -the water finds its way back by a short course to the sea. This is what -now actually occurs on the Pacific coast. The Sierra Nevada condense -nearly all the moisture; so that very little falls on the vast area -extending from their summits eastward to the Rocky Mountains. All that -region is now practically a desert land, where the evaporation exceeds -the precipitation. In Professor Carpenter's view the heat radiated from -the freshly exuded lava is supposed to have prevented the precipitation -near the coast-line, and to have helped the winds in carrying it farther -onward to the northeast, where it would be condensed upon the elevated -highlands, upon which the snows of the great Laurentide Glacier were -collected. - -It is not necessary for us to attempt to measure the amount of truth in -this subsidiary hypothesis of Professor Carpenter, but it illustrates -how complicated are the conditions which have to be considered before we -rest securely upon any particular hypothesis. The unknown elements of the -problem are so numerous, and so far-reaching in their possible scope, -that a cautious attitude of agnosticism, with respect to the cause of -the Glacial period, is most scientific and becoming. Still, we are ready -to go so far as to say that Mr. Upham's theory comes nearest to giving -a satisfactory account of all the phenomena, and it is to this that -Professor Joseph Le Conte gives his cautious approval. - -Summarily stated, this theory is, that the passage from the Tertiary -to the Quaternary or Glacial period was characterised by remarkable -oscillations of land-level, and by corresponding changes of climate, and -of ice-accumulation in northern regions; that the northern elevation -was connected with subsidence in the equatorial regions; that these -changes of land-level were both initiated and, in the main, continued -by the interior geological forces of the globe; but that the very -continental elevation which mainly brought on the Glacial period added -at length, in the weight of the ice which accumulated over the elevated -region, a new force to hasten and increase the subsidence, which would -have taken place in due time in the natural progress of the orographic -oscillations already begun. Professor Le Conte illustrates the subject by -the following diagram, which, for simplicity's sake, treats the Glacial -epoch as one; the horizontal line, A B, represents time from the later -Pliocene until now; but it also represents the present condition of -things both as to land-level and as to ice-accumulation. The full line, c -d e, represents the oscillations of land (and presumably of temperature) -above and below the present condition. The broken line represents the -rise, culmination, and decline of ice-accumulation. The dotted line -represents the crust-movement as it would have been if there had been no -ice-accumulation. - -[Illustration: Fig. 102.] - -_Succession of Epochs, Glacial and Fluvial Deposits, and_ - - Eastern Provinces and Middle and Southern - Epochs. New England. Atlantic States. - - - Recent or Rise of the land to its Continued subsidence of - Terrace. present height, or coast at New York and - (Mostly within somewhat higher, soon southward, and rise of - the period of after the departure of the mountainous belt, by - traditional the ice. Rivers eroding displacement along the - and written their glacial fall line of the rivers. - history.) flood-plains, leaving Much erosion of the - remnants as terraces. Columbia formation since - Warmer climate than now, culmination of second - probably due to greater Glacial epoch; - Gulf Stream, formerly sedimentation in bays, - permitted southern sounds, and estuaries. - mollusks to extend to - Gulf of St. Lawrence, now - represented by isolated - colonies. - - Glacial Period of Ice Age. Pleistocene Period. - - Champlain. Land depressed under Less subsidence in - ice-weight; glacial latitude of New York and - (Close of the recession; continued southward than at north; - second Glacial deposition of upper till lower Hudson Valley, and - epoch.) and deep flood-plains of part of its present - gravel, sand and clay submarine continuation, - (modified drift). above sea-level. Gravel - Terminal moraines marking and sand deposits from - pauses or readvance englacial drift in - during general retreat of Delaware and Susquehanna - ice. Marine submergence. Valleys, inclosing - 150 to 230 feet on coast abundant human implements - of Maine, to 520 feet in at Trenton, N.J. - Gulf and valley of St. - Lawrence. - - Second Glacial. Second great uplift of Renewal of great - the land, 3.000 to 4,000 continental elevation - feet higher than now; (3.000 feet in latitude - snow-fall again all the of New York and - year; ice probably two Philadelphia), of - miles thick on Laurentide excessive snow-fall and - highlands, and extending rains, and of wide-spread - somewhat farther south fluvial deposits, the - here than in first Columbia formation, on - glaciation. Lower till the coastal plain, during - (ground moraine), and early part of this epoch. - upper till (englacial Implements of man at - drift). Terminal Claymont, Del. - moraines, kames, osars, - valley drift. - - Inter-glacial. Ice-sheet melted here; Depression, but generally - probably not more ice in not to the present level. - (Longest epoch arctic regions than now. Deep channels cut in the - of this era.) bed-rocks by the - Fluvial and lacustrine Delaware, Susquehanna, - deposits of this time, Potomac, and other - with those of the first rivers. The Appomattox - Glacial epoch, were deposits much eroded. - eroded by the second - glaciation. Relative length of this - epoch made known by McGee - from study of this - region. - - First Glacial. Begun by high continental Continental elevation; - uplift, cool climate and erosion of Delaware and - snow-fall throughout the Chesapeake Bays, and of - year, producing Albemarle and Pamlico - ice-sheet. Much glacial Sounds. Plentiful - erosion and snow-fall on the southern - transportation; till and Appalachian Mountains; - stratified deposits. snows melted in summer, - Ended by depression of and heavy rains, - land; return of warm producing broad - climate, with rain; final river-floods, with - melting of the ice. deposition of the - Isthmus of Panama Appomattox formation. - probably submerged (Gulf - Stream smaller), and - again in second Glacial - epoch. - - -_Changes in Altitude and Climate, during the Quaternary Era._ - - Mississippi Basin and Cordilleran Region. Europe and Asia. - northward. - - Terracing of river Including a stage of Erosion and terracing - valleys. Northward rise considerable uplift, of stratified drift in - of area of Lake Agassiz with return of humid river valleys. Land - nearly complete before conditions, Alpine passage of European - the ice was melted on glaciation (third flora to Greenland; - the country crossed by Glacial epoch), and succeeded by subsidence - Nelson River; but rise the second great rise there, admitting warm - about Hudson Bay is still of Lakes Bonneville currents to Arctic Sea. - going on; 7,000 to 8,000 and Lahontan. Very Minor climatic changes, - years since ice-melting recent subsidence including a warmer - uncovered Niagara and and change to present stage than now. Upper - falls of St. Anthony. aridity. and outer portions of - Indo-Gangetic alluvial - plain; extensive - deposits of Hwang Ho, - and destructive changes - of its course. - - Abundant deposition of Depression probably Final departure of the - englacial drift. Stone almost to the present ice-sheets; glacial - implements in river level. Restoration of rivers forming eskers - gravels of Ohio, Ind., arid climate; nearly or and kames. Loess - and Minn. Laurentian quite complete deposited while the - lakes held at higher evaporation of Lakes region of the Alps was - levels, and Lake Bonneville and Lahontan.depressed lower than - Agassiz formed in Red Formation of the "adobe"now. Upper (englacial) - River basin, by continuing through the till, and asar, of - barrier of retreating second Glacial, Sweden. Marine - ice, with outlets over Champlain, and Recent submergence 500 to 600 - lowest points of their epochs. feet in Scotland, - present southern Scandinavia, and - water-shed. Marine Spitzbergen. - submergence 300 to 500 - feet on southwest - side of Hudson Bay. - - - Ice-sheet here less Probable uplift 3,0 Second elevation and - extensive than in the feet, shown by general glaciation of - first Glacial epoch, and submerged valleys near northwestern Europe; - not generally bordered Cape Mendocino. Second the ice-sheets of Great - as then by lakes in ice-sheet on British Britain probably more - valleys which now drain Columbia and Vancouver extensive than in first - southward. Island; local Glacial epoch. - glaciation of Rocky Oscillations of - Terminal moraines at Mountains, Cascade and ice-front; British - extreme limit of the Sierra range, Nevada, Lower and Upper - ice-advance, and at ten south to latitude 37°. the Chalky, Purple, and - or more stages of halt or First great rise of bowlder-clays, Hessle - readvance in its retreat. Lakes Bonneville bowlder-clays. Terminal - and Lahontan. moraines in Germany. - - - Depression nearly to Continental depression. Recession, or probably - present level southward; Arid climate. Long- complete departure, of - more northward, but continued denudation of the ice-sheets. - followed there, by the mountains: - differential uplift of resulting very thick Land connection between - 800 or 1,000 feet. subaërial deposits of Europe and Africa, - Great erosion of loess the "adobe." permitting southern - and other modified animals to extend far - drift, and of "Orange Intermittent volcanic northward. - Sand." Valleys of this action in various parts - epoch, partly filled of this region, Erosion of the Somme - with later till, are throughout the Valley below its oldest - marked by chains of Quaternary era to very implement-bearing - lakes in southern recent times, and gravels. - Minnesota. liable to break forth - again. - - Pliocene elevation of Latest rise (3.000 Uplift and glaciation - continent brought to feet) of the Colorado of northwestern Europe: - culmination at Cañon district. Sierra maximum elevation. - beginning of Nevada and other Great 2,500 feet or more - Quaternary era; this Basin mountain-ranges (depth of the Skager - whole basin probably formed by immense Rack); France and - then uplifted 3.000 uplifts, with faulting. Britain united with the - feet; excessive California river- Färöe Islands, Iceland, - snow-fall and rain; courses changed; human and Greenland. Uplifts - deposition of the bones and implements in of the Himalayas and - "Orange Sand." Ice- the old river gravels, other mountain-ranges - sheet south to lava-covered. Ice-sheet attendant on both - Cincinnati and St. on British Columbia; Glacial epochs. - Louis, at length local glaciers - depressing the earth's southward. - crust beneath it; - slackened river floods - and shallow lakes, - forming the loess. - -It is seen from the diagram that the ice-accumulation culminated at a -time when the land, under the pressure of the ice-load, had already -commenced to subside; and that the subsidence was greatest at a time when -the pressure had already begun to diminish. But the fact that the land, -after the removal of the ice-load, did not return again to its former -height in the Pliocene, is proof positive that there were other and -more fundamental causes of crust-movement at work besides weighting and -lightening. The land did not again return to its former level because the -cycle of elevation, whatever its cause, which commenced in the Pliocene -and culminated in the early Quaternary, had exhausted itself. If it had -not been for the ice-load interfering with and modifying the natural -course of the crust-movement determined previously and primarily by other -and probably internal causes, the latter would probably have taken the -course represented by the dotted line. It would have risen higher and -culminated later, and its curve would have been of simpler form. - -We append a carefully prepared table by Mr. Warren Upham, showing the -probable changes in altitude and climate during the Quaternary era.[DX] - -[Footnote DX: On page 106 and sequel I have summarised the reasons which -lead me to discard the Inter-Glacial epoch, and to look upon the whole -Glacial period as constituting a grand unity with minor episodes. It -does not yet seem to me that the duality of the period is proved. On the -contrary, Mr. Kendall's chapter on the Glacial phenomena of Great Britain -strongly confirms my view.] - -On the part of many the theory here provisionally adopted will be -regarded with disfavour by reason of a disinclination to supposing -any great recent changes of level in the continental areas. So firmly -established do the continents appear to be, that it seems like invoking -an inordinate display of power to have them exalted for the sake of -producing a Glacial period. Due reflection, however, will make it -evident that within certain limits the continents are exceedingly -unstable, and that they have displayed this instability to as great an -extent in recent geological times as they have done in any previous -geological periods. When one reflects, also, upon the size of the earth, -a continental elevation of 3,000 or 4,000 feet upon a globe whose -diameter is more than 40,000,000 feet is an insignificant trifle. On a -globe one foot in diameter it would be represented by a protuberance of -barely one thousandth of an inch. A corresponding wrinkle upon a large -apple would require a magnifying-glass for its detection. Moreover, the -activity of existing volcanoes, the immense outflows of lava which have -taken place in the later geological periods, together with the uniform -increase of heat as we penetrate to deeper strata in the crust of the -earth--all point to a condition of the earth's interior that would -make the elevations of land which we have invoked for the production -of the Glacial period easily credible. Physicists do not, indeed, now -hold to the entire fluidity of the earth's interior, but rather to a -solid centre, where gravity overcomes the expansive power of heat, and -maintains solidity even when the heat is intense. But between the cooling -crust of the earth's exterior and a central solid core there is now -believed to be a film where the influences of heat and of the pressure -of gravity are approximately balanced, and the space is occupied by a -half-melted or viscous magma, capable of yielding to a slow pressure, and -of moving in response to it from one portion of the enclosed space to -another where the pressure is for any cause relieved. - -As a result of prolonged enquiries respecting the nature of the forces -at work both in the interior and upon the exterior of the earth, and -of a careful study of the successive changes marking the geological -period, we are led to believe that the continental elevations necessary -to produce the phenomena of the Glacial period are not only entirely -possible but easily credible, and in analogy with the natural progress -of geological history. In the first place, it is easy to see that -two causes are in operation to produce a contraction of the earth's -volume and a shortening of its diameter. Heat is constantly being -abstracted from the earth by conduction and radiation, but perhaps to -a greater extent through ceaseless volcanic eruptions which at times -are of enormous extent. It requires but a moment's thought to see that -contraction of the volume of the earth's interior means that the hardened -exterior crust must adjust itself by wrinkles and folds. For a long -period this adjustment might show itself principally in gentle swells, -lifting portions of the continents to a higher level, accompanied by -corresponding subsidence in other places. This gradually accumulating -strain would at length be relieved along some line of special weakness in -the crust by that folding process which has pushed up the great mountain -systems of the world. - -Careful study of the principal mountain systems shows that all the -highest of them are of late geological origin. Indeed, the latter part -of the Tertiary period has been the great mountain-building epoch in the -earth's history. The principal part of the elevation of the Andes and -the Rocky Mountains has taken place since the middle of the Tertiary -period. In Europe there is indubitable evidence that the Pyrenees have -been elevated eleven thousand feet during the same period, and that the -western Alps have been elevated thirteen thousand feet in the same time. -The Carpathians, the western Caucasus, and the Himalayas likewise bear -explicit evidence to the fact that a very considerable portion of their -elevation, amounting to many thousand feet, has been effected since the -middle of the Tertiary period, while a considerable portion of this -elevation of the chiefest mountain systems of the world has occurred in -what would be called post-Tertiary time--that is, has been coincident -with a portion of the Glacial period. - -The Glacial period, however, we suppose to have been brought about, not -by the specific plications in the earth's crust which have produced the -mountain-chains, but by the gentler swells of larger continental areas -whose strain was at last relieved by the folding and mashing together -of the strata along the lines of weakness now occupied by the mountain -systems. The formation of the mountains seems to have relieved the -accumulating strain connected with the continental elevations, and to -have brought about a subsequent subsidence. - -Doubtless, also, correlated subsidences and elevations of the earth's -crust have been aided by the transfer of the sediment from continental -to oceanic areas, and, as already suggested, during the Glacial period -by the transfer of water evaporated from the surface of the ocean to -the ice-fields of the glaciated area. For example, present erosive -agencies are lowering the level of the whole Mississippi basin from -the Alleghanies to the Rocky Mountains at the rate of a foot in five -thousand years. All this sediment removed is being transferred to the -ocean-bed. Present agencies, therefore, if not counteracted, would -remove the whole continent of America (whose average elevation above the -sea is only 748 feet) in less than four million years; while the great -rivers which descend in all directions from the central plateau of Asia -are transferring sediment to the ocean from two to four times as fast -as the Mississippi is, and the Po is transferring it from the Alps to -the Adriatic fully seven times as fast as the Mississippi is from its -basin to the Gulf of Mexico. This rapid transfer of sediment from the -continents to the ocean is producing effects in disturbing the present -equilibrium of the earth's crust, which are too complicated for us fully -to calculate; but it is by no means improbable that when accumulating for -a considerable length of time, the ultimate results may be very marked -and perhaps sudden in their appearance. - -The same may also be said of the accumulation of ice during the Glacial -period. The glaciated areas of North America and Europe combined -comprise about six million square miles. At a moderate estimate, -the ice was three-quarters of a mile deep. Here, therefore, there -would be between four and five million cubic miles of water, which -had first relieved the ocean-beds of the pressure of its weight, and -then concentrated its force over the elevated areas of the northern -hemisphere. This disturbance of the equilibrium, by the known transfer -of force from one part of the earth's crust to another, certainly gives -much plausibility to the theory of Jamieson, Winchell, Le Conte, and -Upham, that the Glacial period partly contained in itself its own cure, -and by the weight of its accumulated weight of ice helped to produce -that depression over the glaciated area which at length rendered the -accumulation of ice there impossible. - -This general view of the known causes in operation during the Glacial -period will go far towards answering an objection that has probably -before this presented itself to the reader's mind. It seems clear -that the Glacial period in the southern hemisphere has been nearly -contemporaneous with that of the northern. The Glacial period proper of -the southern hemisphere is long since passed. The existing glaciers of -New Zealand, of the southern portion of the Andes Mountains, and of the -Himalaya Mountains are but remnants of those of former days. In the light -of the considerations just presented, it would not seem improbable that -the same causes should produce these similar effects in the northern and -the southern hemisphere contemporaneously. At any rate, it would not -seem altogether unlikely that the pressure of ice during the climax of -the Glacial period upon the northern hemisphere (which, as we have seen, -there is reason to believe aided in the depression of the continent to -below its present level in the latter part of the Glacial period) should -have contributed towards the elevation of mountains in other parts of the -world, and so to the temporary enlargement of the glaciers about their -summits. - -Nor are we wholly without evidence that these readjustments of land-level -which have been carried on so Vigorously since the middle of the Tertiary -period are still going on with considerable though doubtless with -diminished rapidity. There has been a re-elevation of the land in North -America since the Glacial period amounting to 230 feet upon the coast of -Maine, 500 feet in the vicinity of Montreal, from 1,000 to 1,600 feet in -the extreme northern part of the continent, and in Scandinavia to the -extent of 600 feet. In portions of Scandinavia the land is now rising -at the rate of three feet in a century. Other indications of even the -present instability of the earth's surface occur in numbers too numerous -to mention.[DY] - -[Footnote DY: For a convincing presentation of the views here outlined, -together with abundant references to literature, see Mr. Warren Upham's -Appendix to the author's Ice Age in North America.] - -But, while we are increasingly confident that the main causes of the -Glacial period have been changes in the relative relation of land-levels -connected with diversion of oceanic currents, it is by no means -impossible, as Wallace[DZ] and others have suggested, that these were -combined with the astronomical causes urged by Drs. Croll and Geikie. -By some this combination is thought to be the more probable, because -of the extreme recentness of the close of the Glacial period, as shown -by the evidence which will be presented in the following chapter. The -continuance of glaciers in the highlands of Canada, down to within a few -thousand years of the present time, coincides in a remarkable manner with -the last occurrence of the conditions favourable to glaciation upon Mr. -Croll's theory, which took place about eleven thousand years ago. - -[Footnote DZ: See Island Life, chapters viii and ix.] - - - - -CHAPTER X. - -THE DATE OF THE GLACIAL PERIOD. - - -In approaching the subject of glacial chronology, we are compelled -to recognise at the outset the approximate character of all our -calculations. Still, we shall find that there are pretty well-defined -limits of time beyond which it is not reasonable to place the date of -the close of the Glacial period; and, where exact figures cannot be -determined, it may yet be of great interest and importance to know -something near the limits within which our speculations must range. - -For many years past Mr. Croll's astronomical theory as to the cause of -the Glacial period has been considered in certain circles as so nearly -established that it has been adopted by them as a chronological table in -which to insert a series of supposed successive Glacial epochs which are -thought to have characterised not merely the Quaternary epoch but all -preceding geological eras. What we have already said, however, respecting -the weakness of Mr. Croll's theory is probably sufficient to discredit it -as a chronological apparatus. We will therefore turn immediately to the -more tangible evidences bearing upon the subject. - -The data directly relating to the length of time which separates the -present from the Glacial period are mainly connected with two classes of -facts: - -1. The amount of erosion which has been accomplished by the river systems -since the Glacial period; and 2. The amount of sedimentation which -has taken place in lakes and kettle-holes. We will consider first the -evidence from erosion. - -[Illustration: Fig. 103.--Diagram of eccentricity and precession: -Abscissa represents time and ordinates, degrees of eccentricity and also -of cold. The dark and light shades show the warmer and colder winters, -and therefore indicate each 10,500 years, the whole representing a period -of 300,000 years.] - -The gorge below Niagara Falls affords an important chronometer for -measuring the time which has elapsed since a certain stage in the -recession of the great North American ice-sheet. As already shown, the -present Niagara River is purely a post-glacial line of drainage;[EA] the -preglacial outlet to Lake Erie having been filled up by glacial deposits, -so that, on the recession of the ice, the lowest level between Lake Erie -and Lake Ontario was in the line of the trough of the present outlet. -But, from what has already been said, it also appears that the Niagara -River did not begin to flow until considerably after the ice-front had -withdrawn from the escarpment at Queenston, where the river now emerges -from its cañon to the low shelf which borders Lake Ontario. For a -considerable period afterwards the ice continued to block up the easterly -and northerly outlets through the valleys of the Mohawk and of the St. -Lawrence, and held the water in front of the ice up to the level of the -passes leading into the Mississippi Valley. Niagara River, of course, was -not born until these ice-barriers on the east and northeast melted away -sufficiently to allow the drainage to take its natural course. - -[Footnote EA: See above, p. 200 _et seq._] - -[Illustration: Fig. 104.--Map of the Niagara River below the falls, -showing the buried channel from the whirlpool to St. Davids. Small -streams, _a_, _b_, _c_, fall into the main gorge over a rocky escarpment. -No rock appears in the channel at _d_, but the rocky escarpment reappears -at _e_.] - -Of these barriers, that across the Mohawk Valley doubtless gave way -first. This would allow the confluent waters of this great glacial lake -to fall down to the level of the old outlet from the basin of Lake -Ontario into the Mohawk Valley, in the vicinity of Home, N. Y. The -moment, however, that the water had fallen to this level, the plunging -torrents of Niagara would begin their work; and the gorge extending from -Queenston up to the present falls is the work done by this great river -since that point of time in the Glacial period when the ice-barrier -across the Mohawk Valley broke away. - -The problem is therefore a simple one. Considering the length of -this gorge as the dividend, the object is to find the rate of annual -recession; this will be the divisor. The quotient will be the number of -years which have elapsed since the ice first melted away from the Mohawk -Valley. We are favoured in our calculation by the simplicity of the -geologic arrangement. - -The strata at Niagara dip slightly to the south, but not enough to make -any serious disturbance in the problem. That at the surface, over which -the water now plunges, consists of hard limestone, seventy or eighty -feet in thickness, and this is continuous from the falls to the face of -the escarpment at Queenston, where the river emerges from the gorge. -Immediately underneath this hard superficial stratum there is a stratum -of soft rock, of about the same thickness, which disintegrates readily. -As a consequence, the plunging water continually undermines the hard -stratum at the surface, and prepares the way for it to fall down, from -time to time, in huge blocks, which are, in turn, ground to powder by -the constant commotion in which they are kept, and thus the channel is -cleared of _débris_. - -[Illustration: Fig. 105.--Section of strata along the Niagara gorge from -the falls to the lake: 1, 3, strata of hard rock; 2, 4, of soft rock.] - -Below these two main strata there is considerable variation in the -hardness of the rock, as shown in the accompanying diagram, where 3 and -5 are hard strata separated by a soft stratum. In view of this fact it -seems probable that, for a considerable period in the early part of the -recession, instead of there being simply one, there was a succession of -cataracts, as the water unequally wore back through the harder strata, -numbered 5, 3, and 1; but, after having receded half the distance, these -would cease to be disturbing influences, and the problem is thus really -the simple one of the recession through the strata numbered 1 and 2, -which are continuous. So uniform in consistency are these throughout the -whole distance, that the rate of recession could never have been less -than it is now. We come, therefore, to the question of the rapidity with -which the falls are now receding. - -In 1841 Sir Charles Lyell and Professor James Hall (the State Geologist -of New York) visited the falls together, and estimated that the rate of -recession could not be greater than one foot a year, which would make the -time required about thirty-five thousand years. But Lyell thought this -rate was probably three times too large; so that he favoured extending -the time to one hundred thousand years. Before this the eminent French -geologist Desor had estimated that the recession could not have been -more than a foot in a century, which would throw the beginning of the -gorge back more than three million years. But these were mere guesses -of eminent men, based on no well-ascertained facts; while Mr. Bakewell, -an eminent English geologist, trusting to the data furnished him by the -guides and the old residents of Niagara, had, even then, estimated that -the rate of recession was as much as three feet a year, which would -reduce the whole time required to about ten thousand years. - -But the visit of Lyell and Hall in 1841 led to the beginning of more -accurate calculations. Professor Hall soon after had a trigonometrical -survey of the falls made, from which a map was published in the State -geological report. From this and from the monuments erected, we have had -since that time a basis of comparison in which we could place absolute -confidence. - -In recent years three surveys have been made: the first by the New -York State Geologists, in 1875; and the third by Mr. R. S. Woodward, -the mathematician of the United States Geological Survey, in 1886. The -accompanying map shows the outlines of the falls at the time of these -three measurements, from 1842 to 1886. According to Mr. Woodward, "the -length of the front of the Horseshoe Fall is twenty-three hundred feet. -Between 1842 and 1875 four and a quarter acres of rock were worn away by -the recession of the falls. Between 1875 and 1886 a little over one acre -and a third disappeared in a similar manner, making in all, from 1842 to -1886, about five and a half acres removed, and giving an annual rate of -recession of about two feet and a half per year for the last forty-five -years. But in the central parts of the curve, where the water is deepest, -the Horseshoe Fall retreated between two hundred and two hundred and -seventy-five feet in the eleven years between 1875 and 1886." - -[Illustration: Fig. 106.--Map showing the recession of the Horseshoe -Falls since 1842, as by survey mentioned in the text (Pohlman). (by -courtesy of the American Institute of Mining Engineers.)] - -It will be perceived that the recession in the centre of the Horseshoe is -very much more rapid than that nearer the margin; yet this rate at the -centre is more nearly the standard of calculation than is that near the -margin, for the gorge constantly tends to enlarge itself below the falls, -and so gradually to bring itself into line with the full-formed channel. -Taking all things into account, Mr. Woodward and the other members of -the Geological Survey thought it not improbable that the average rate -of actual recession in the Horseshoe Fall was as great as five feet per -annum; and that, if we can rely upon the uniformity of the conditions in -the past, seven thousand years is as long a period as can be assigned to -its commencement. - -The only condition in the problem about which there can be much chance of -question relates to the constancy of the volume of water flowing in the -Niagara channel. Mr. Gilbert had suggested that, as a consequence of the -subsidence connected with the closing portions of the Glacial period, the -water of the Great Lakes may have been largely diverted from its present -outlet in Niagara River and turned northeastward, through Georgian Bay, -French River, and Lake Nipissing, into a tributary of the Ottawa River, -and so carried into the St. Lawrence below Lake Ontario. Of this theory -there is also much direct evidence. A well-defined shore line of rounded -pebbles extends, at an elevation of about fifty feet, across the col -from Lake Nipissing to the head-waters of the Mattawa, a tributary of -the Ottawa; while at the junction with the Ottawa there is an enormous -delta terrace of boulders, forming a bar across the main stream just such -as would result from Mr. Gilbert's supposed outlet. But this outlet was -doubtless limited to a comparatively few centuries, and Dr. Robert Bell -thinks the evidence still inconclusive.[EB] - -[Footnote EB: See Bul. Geol. Soc. Am., vol. iv, pp. 423-427, vol. v, pp. -620-626.] - -A second noteworthy glacial chronometer is found in the gorge of -the Mississippi River, extending from the Falls of St. Anthony, at -Minneapolis, to its junction with the preglacial trough of the old -Mississippi, at Fort Snelling, a distance likewise of about seven miles. - -Above Fort Snelling the preglacial gorge is occupied by the Minnesota -River, and, as we have before stated, extends to the very sources of -this river, and is continuous with the southern portion of the valley of -the trough of the Red River of the North. Before the Glacial period the -drainage of the present basin of the upper Mississippi joined this main -preglacial valley, not at Fort Snelling, but some little distance above, -as shown upon our map.[EC] This part of the preglacial gorge became -partially filled up with glacial deposits, but it can be still traced -by the lakelets occupying portions of the old depression, and by the -records of wells which have been sunk along the line. When the ice-front -had receded beyond the site of Minneapolis, the only line of drainage -left open for the water was along the course of the present gorge from -Minneapolis to Fort Snelling. - -[Footnote EC: See above, p. 209.] - -Here, as at Niagara, the problem is comparatively simple. The upper -strata of rock consist of hard limestone, which is underlaid by a soft -sandstone, which, like the underlying shale at Niagara, is eroded faster -than the upper strata, and so a perpendicular fall is maintained. The -strata are so uniform in texture and thickness that, with the present -amount of water in the river, the rate of recession of the falls must -have been, from the beginning, very constant. If, therefore, the rate can -be determined, the problem can be solved with a good degree of confidence. - - -Fortunately, the first discoverer of the cataract--the Catholic -missionary Hennepin--was an accurate observer, and was given to -recording his observations for the instruction of the outside world and -of future generations. From his description, printed in Amsterdam in -1704, Professor N. H. Winchell is able to determine the precise locality -of the cataract when discovered in 1680. - -Again, in 1766 the Catholic missionary Carver visited the falls, and not -only wrote a description, but made a sketch (found in an account of his -travels, published in London in 1788) which confirms the inferences drawn -from Hennepin's narrative. The actual period of recession, however (which -Professor Winchell duly takes into account), extends only to the year -1856, at which time such artificial changes were introduced as to modify -the rate of recession and disturb further calculations. But between 1680 -and 1766 the falls had evidently receded about 412 feet. Between 1766 and -1856 the recession had been 600 feet. The average rate is estimated by -Professor Winchell to be about five feet per year, and the total length -of time required for the formation of the gorge above Fort Snelling -is a little less than eight thousand years, or about the same as that -calculated by Messrs. Woodward and Gilbert for the Niagara gorge. - -To these calculations of Professor Winchell it does not seem possible -to urge any valid objection. It does not seem credible that the amount -of water in the Mississippi should ever have been less than now, while -during the continuance of the ice in the upper portion of the Mississippi -basin the flow of water was certainly far greater than now. - -If any one is inclined to challenge Professor Winchell's interpretation -of the facts, even a hasty visit to the locality will suffice to produce -conviction. The comparative youth of the gorge from Fort Snelling up to -Minneapolis is evident: 1. From its relative narrowness, when compared -with the main valley below. This is represented by the shading upon -the map. The gorge from Fort Snelling up is not old enough to have -permitted much enlargement by the gradual undermining of the superficial -strata on either side, which slowly but constantly goes on. 2. From -the abruptness with which it merges into the preglacial valley of the -Minnesota-Mississippi. The opening at Fort Snelling is not Y-shaped, -as in gorges where there has been indefinite time for the operation of -erosive agencies. 3. Furthermore, the precipices lining the post-glacial -gorge above Fort Snelling are far more abrupt than those in the -preglacial valley below, and they give far less evidence of weathering. -4. Still, again, the tributary streams, like the Minnehaha River, which -empty into the Mississippi between Fort Snelling and Minneapolis, -flow upon the surface, and have eroded gorges of very limited extent; -whereas, below Fort Snelling, the small streams have usually either found -underground access to the river or occupy gorges of indefinite extent. - -The above estimates, setting such narrow limits to post-glacial time -in America, will seem surprising only to those who have not carefully -considered the glacial phenomena of various kinds to be observed all -over the glaciated area. As already said, the glaciated portion of -North America is a region of waterfalls, caused by the filling up of -old channels with glacial _débris_, and the consequent diversion of the -water-courses. By this means the streams in countless places have been -forced to fall over precipices, and to begin anew their work of erosion. -Waterfalls abound in the glaciated region because post-glacial time is -so short. Give these streams time enough, and they will wear their way -back to their sources, as the preglacial streams had done over the same -area, and as similar streams have done outside the glaciated region. Upon -close observation, it will be found that the waterfalls in America are -nearly all post-glacial, and that their work of erosion has been confined -to a very limited time. A fair example is to be seen at Elyria, Ohio, -in the falls of Black River, one of the small streams which empty into -Lake Erie from the south. Its post-glacial gorge, worn in sandstone which -overlies soft shale, is only about two thousand feet in length, and it -has as yet made no approach toward a V-shaped outlet. - -The same impression of recent age is made by examining the outlets of -almost any of the lakes which dot the glaciated area. The very reason of -the continued existence of these lakes is that they have not had time -enough to lower their outlets sufficiently to drain the water off, as has -been done in all the unglaciated region. In many cases it is easy to see -that the time during which this process of lowering the outlets has been -going on cannot have been many thousand years. - -The same impression is made upon studying the evidences of post-glacial -valley erosion. Ordinary streams constantly enlarge their troughs by -impinging against the banks now upon one side and now upon the other, and -transporting the material towards the sea. It is estimated by Wallace -that nine-tenths of the sedimentary material borne along by rivers is -gathered from the immediate vicinity of its current, and goes to enlarge -the trough of the stream. Upon measuring the cubical contents of many -eroded troughs of streams in the glaciated region, and applying the -tables giving the average amount of annual transportation of sediment -by streams, we arrive at nearly the same results as by the study of the -recession of post-glacial waterfalls. - -Professor L. E. Hicks, of Granville, Ohio, has published the results -of careful calculations made by him, concerning the valley of Raccoon -Creek in Licking County, Ohio.[ED] These show that fifteen thousand -years would be more than abundant time for the erosion of the immediate -valley adjoining that small stream. I have made and published similar -calculations concerning Plum Creek, at Oberlin, in Lorain County, -Ohio.[EE] Like Raccoon Creek, this has its entire bed in glacial -deposits, and has had nothing else to do since its birth but to enlarge -its borders. The drainage basin of the creek covers an area of about -twenty-five square miles. Its main trough averages about twenty feet in -depth by five hundred in width, along a distance of about ten miles. From -the rate at which the stream is transporting sediment, it is incredible -that it could have been at work at this process more than ten thousand -years without producing greater results. - -[Footnote ED: See Baptist Quarterly for July. 1884.] - -[Footnote EE: See Ice Age in North America, p. 469.] - -Calculations based upon the amount of sediment deposited since the -retreat of the ice-sheet point to a like moderate conclusion. When one -looks upon the turbid water of a raging stream in time of flood, and -considers that all the sediment borne along will soon settle down upon -the bottom of the lake into which the stream empties, he can but feel -surprised that the "wash" of the hills has not already filled up the -depression of the lake. It certainly would have done so had the present -condition of things existed for an indefinite period of time. - -Naturally, while prosecuting the survey of the superficial geology of -Minnesota, Mr. Upham was greatly impressed by the continued existence -of the innumerable lakelets that give such a charm to the scenery of -that State. Every day's investigations added to the evidence that the -lapse of time since the Ice age must have been comparatively brief, -since, otherwise, the rains and streams would have filled these basins -with sediment, and cut outlets low enough to drain them dry, for in many -instances he could see such changes slowly going forward.[EF] - -[Footnote EF: Minnesota Geological Report for 1879, p. 73.] - -[Illustration: Fig. 107.--Section of kettle-hole near Pomp's Pond, -Andover, Massachusetts (see text). (For general view of the situation, -see Fig. 30, p. 78.)] - -Some years ago I myself made a careful estimate of the amount of -deposition and vegetable accumulation which had taken place in a -kettle-hole near Pomp's Pond, in Andover, Mass. The diameter of the -depression at the rim was 276 feet. The inclination of the sides was -such that the extreme depression of the apex of the inverted cone could -not have been more than seventy feet; yet the accumulation of peat and -sediment only amounted to a depth of seventeen feet. The total amount of -material which had accumulated would be represented by a cone ninety-six -feet in diameter at the base and seventeen feet at the apex, which would -equal only a deposit of about five feet over the present surface of the -bottom. It is easy to see that ten thousand years is a liberal allowance -of time for the accumulation of five feet of sediment in the bottom -of an enclosure like a kettle-hole, for upon examination it is clear -that whatever insoluble material gets into a kettle-hole must remain -there, since there is no possible way by which it can get out. Now five -feet is sixty inches, and if this amount has been six thousand years -in accumulating, that would represent a rate of an inch in one hundred -years, while, if it has been twelve thousand years in accumulation, the -rate will be only one two-hundredth of an inch per year, a film so small -as to be almost inappreciable. If we may judge from appearance, the -result would not be much different in the case of the tens of thousands -of kettle-holes and lakelets which dot the surface of the glaciated -region. - -In the year 1869 Dr. E. Andrews, of Chicago, made an important series of -calculations concerning the rate at which the waters of Lake Michigan are -eating into the shores and washing the sediment into deeper water or -towards the southern end of the lake. With reference to the erosion of -the shores, it appears from the work of the United States Coast Survey -that a shoulder, covered with sixty feet of water, representing the -depth at which wave-action is efficient in erosion, extends outward from -the west shore a distance of about three miles, where the sounding line -reveals the shore of the deeper original lake as it appeared upon the -first withdrawal of the ice. - -From a variety of observations the average rate at which the erosion of -the bluffs is proceeding is found to be such that the post-glacial time -cannot be more than ten thousand years, and probably not more than seven -thousand. - -An independent mode of calculating this period is afforded by the -accumulations of sand at the south end of the lake, to which it is -constantly drifting by the currents of water propelled against the shores -by the wind; for the body of water in the lake is moving southward -along the shores towards the closed end in that direction, there being -a returning current along the middle of the lake. All the railroads -approaching Chicago from the east pass through these sand deposits, and -few of the observant travellers passing over the routes can have failed -to notice the dunes into which the sand has been drifted by the wind. -Now, all the material of these dunes and sand-beaches has been washed out -of the bluffs to the northward by the process already mentioned, and has -been slowly transferred by wave-action to its present position. It is -estimated that south of Chicago and Grand Haven, this wave-transported -sand amounts to 3,407,451,000 cubic yards. This occupies a belt curving -around the south end about ten miles wide and one hundred miles long. - -The rate at which the sand is moving southward along the shore is found -by observing the amount annually arrested by the piers at Chicago, Grand -Haven, and Michigan City. This equals 129,000 cubic yards for a year, -which can scarcely be more than one quarter or one fifth of the total -amount in motion. At this rate, the sand accumulations at the southern -end of the lake would have been produced in a little less than seven -thousand years. - -"If," says Dr. Andrews, "we estimate the total annual sand-drift at -only twice the amount actually stopped by the very imperfect piers -built--which, in the opinion of the engineers, is setting it far too -low--and compare it with the capacity of the clay-basin of Lake Michigan, -we shall find that, had this process continued one hundred thousand years -the whole south end of Lake Michigan, up to the line connecting Chicago -and Michigan City, would have been full and converted into dry land -twenty-five thousand years ago, and the coast-line would now be found -many miles north of Chicago."[EG] - -[Footnote EG: Southall's Recent Origin of Man, p. 502.] - -It is proper to add a word in answer co an objection which may arise -in the reader's mind, for it will doubtless occur to some to ask why -this sand which is washed out by the waves from the bluffs is not -carried inward towards the deeper portion of the trough of the lake, -thus producing a waste which would partly counteract the forces of -accumulation at the south end. The answer is found in the fact that the -south end of Lake Michigan is closed, and that the currents set in motion -by the wind are such that there is no off-shore motion sufficient to move -sand, and, as a matter of fact, dredgings show that the sand is limited -to the vicinity of the shore. - -By comparing the eroded cliffs upon Michigan and the other Great Lakes -with what occurs in similar situations about the glacial Lake Agassiz, we -obtain an interesting means of estimating the comparative length of time -occupied by the ice-front in receding from the Canadian border to Hudson -Bay. - -As we have seen, Lake Agassiz occupied a position quite similar in most -respects to Lake Michigan. Its longest diameter was north and south, and -the same forces which have eroded the cliffs of Lake Michigan and piled -up sand-dunes at its southern end would have produced similar effects -upon the shores of Lake Agassiz, had its continuance been anywhere near -as long as that of the present Lake Michigan has been. But, according -to Mr. Upham, who has most carefully surveyed the whole region, there -are nowhere on the shores of the old Lake Agassiz any evidence of eroded -cliffs at all to be compared with those found upon the present Great -Lakes, while there is almost an entire lack of sand deposits about the -south end such as characterise the shore of Lake Michigan. "The great -tracts of dunes about the south end of Lake Michigan belong," as Upham -well observes, "wholly to beach accumulations, being sand derived from -erosion of the western and eastern shores of the lake.... But none of -the beaches of our glacial lakes are large enough to make dunes like -those on Lake Michigan, though the size and depth of Lake Agassiz, its -great extent from north to south, and the character of its shores, seem -equally favorable for their accumulation. It is thus again indicated that -the time occupied by the recession of the ice-sheet was comparatively -brief."[EH] - -[Footnote EH: Proceedings of the Boston Society of Natural History, -vol. xxiv, p. 454; Upham's Glacial Lakes in Canada, in Bulletin of the -Geological Society of America, vol. ii, p. 248.] - -From Mr. Upham's conclusions it would seem that if ten thousand years -be allowed for the post-glacial existence of Lake Michigan, one tenth -of that period would be more than sufficient to account for the cliffs, -deltas, beaches, and other analogous phenomena about Lake Agassiz. In -other words, the duration of Lake Agassiz could not have been more -than a thousand years, which gives us a measure of the rate at which -the recession of the ice-front went on after it had withdrawn to the -international boundary. The distance from there to the mouth of Nelson -River is about 600 miles. The recession of the ice-front over that area -proceeded, therefore, at the average rate of about half a mile per year. - -There are many evidences that the main period of glaciation west of the -Rocky Mountains was considerably later than that in the eastern part of -the continent. A portion of the facts pointing to this conclusion have -been well stated by Mr. George F. Becker, of the United States Geological -Survey. - -"No one," he says, "who has examined the glaciated regions of the -Sierra can doubt that the great mass of the ice disappeared at a very -recent period. The immense areas of polished surfaces fully exposed -to the severe climate of say from 7,000 to 12,000 feet altitude, the -insensible erosion of streams running over glaciated rocks, and the -freshness of erratic boulders are sufficient evidence of this. There -is also evidence that the glaciation began at no very distant geologic -date. As Professor Whitney pointed out, glaciation is the last important -geological phenomenon and succeeded the great lava flows. There is also -much evidence that erosion has been trifling since the commencement of -glaciation, excepting under peculiar circumstances. East of the range, -for example, at Virginia City, andesites which there is every reason to -suppose preglacial have scarcely suffered at all from erosion, so that -depressions down which water runs at every shower are not yet marked with -water-courses, while older rocks, even of Tertiary age and close by, -are deeply carved. The rainfall at Virginia City is, to be sure, only -about ten inches, so that rock would erode only say one third as fast -as on the California coast; but even when full allowance is made for -this difference, it is clear that these andesites must be much younger -than the commencement of glaciation in the northeastern portion of the -continent as usually estimated. So, too, the andesites near Clear Lake, -in California, though beyond a doubt preglacial, have suffered little -erosion, and one of the masses, Mount Konocti (or Uncle Sam), has nearly -as characteristic a volcanic form as Mount Vesuvius."[EI] - -[Footnote EI: Bulletin of the Geological Society of America, vol. ii, pp. -196, 197.] - -This view of Mr. Becker is amply sustained by many other obvious facts, -some of which may be easily observed by tourists who visit the Yosemite -Park. The freedom of the abutting walls of this cañon from talus, as well -as the freshness of the glacial scratches upon both the walls and the -floor of the tributary cañons, all indicate a lapse of centuries only, -rather than of thousands of years, since their occupation by glacial ice. - -The freshness of the high-level terraces surrounding the valleys of Great -Salt Lake, in Utah, and of Pyramid and North Carson Lakes, in Nevada, and -the small amount of erosion which has taken place since the formation of -these terraces, point in the same direction--namely, to a very recent -date for the glaciation of the Pacific coast. - -We have already detailed the facts concerning the formation of these -terraces and the evidence of their probable connection with the Glacial -period. It is sufficient, therefore, here to add that, according to Mr. -Russell and Mr. Gilbert (two of the most eminent members of the United -States Geological Survey, who have each published monographs minutely -embodying the results of their extensive observations in this region), -the erosion of present streams in the beds which were deposited during -the enlargement of the lakes is very slight, and the modification of the -shores since the formation of the high terraces has been insignificant. - -According to Mr. Gilbert: "The Bonneville shores are almost unmodified. -Intersecting streams, it is true, have scored them and interrupted their -continuity for brief spaces; but the beating of the rain has hardly -left a trace. The sea-cliffs still stand as they first stood, except -that frost has wrought upon their faces so as to crumble away a portion -and make a low talus at the base. The embankments and beaches and bars -are almost as perfect as though the lake had left them yesterday, and -many of them rival in the symmetry and perfection of their contours the -most elaborate work of the engineer. There are places where boulders of -quartzite or other enduring rock still retain the smooth, glistening -surfaces which the waves scoured upon them by clashing against them the -sands of the beach. - -"When this preservation is compared with that of the lowest Tertiary -rocks of the region--the Pliocene beds to which King has given the name -Humboldt--the difference is most impressive. The Pliocene shore-lines -have disappeared. - -"The deposits are so indurated as to serve for building-stone. They have -been upturned in many places by the uplifting of mountains. Elsewhere -they have been divided by faults, and the fragments, dissevered from -their continuation in the valley, have been carried high up on the -mountain-flanks, where erosion has carved them in typical mountain -forms.... The date of the Bonneville flood is the geologic yesterday, -and, calling it yesterday, we may without exaggeration refer the Pliocene -of Utah to the last decade; the Eocene of the Colorado basin to the last -century, and relegate the laying of the Potsdam sandstone to prehistoric -times."[EJ] - -[Footnote EJ: Second Annual Report of the United States Geological -Survey, p. 188.] - -Mr. Russell adds to this class of evidence that of the small extent to -which the glacial striæ have been effaced since the withdrawal of the -ice from the borders of these old lakes: "The smooth surfaces are still -scored with fine, hair-like lines, and the eye fails to detect more -than a trace of disintegration that has taken place since the surfaces -received their polish and striation.... It seems reasonable to conclude -that in a severe climate like that of the high Sierra it" (the polish) -"could not remain unimpaired for more than a few centuries at the -most."[EK] - -[Footnote EK: See also Mr. Upham in American Journal of Science, vol. -xli, pp. 41, 51.] - -Europe does not seem to furnish so favourable opportunities as America -for estimating the date of the Glacial period; still it is not altogether -wanting in data bearing upon the subject. - -Some of the caves in which palæolithic implements were found associated -with the bones of extinct animals in southern England contain floors -of stalagmite which have been thought by some to furnish a measure of -the time separating the deposits underneath from those above. This is -specially true in the case of Kent's Cavern, near Torquay, which contains -two floors of stalagmite, the upper one almost continuous and varying in -thickness from sixteen inches to five feet, the lower one being in places -twelve feet thick, underneath which human implements were found. - -But it is difficult to determine the rate at which stalagmite -accumulates. As is well known, this deposit is a form of carbonate of -lime, and accumulates when water holding the substance in solution drops -down upon the surface, where it is partially evaporated. It then leaves a -thin film of the substance upon the floor. The rate of the accumulation -will depend upon both the degree to which the water is saturated with the -carbonate and upon the quantity of the water which percolates through the -roof of the cavern. These factors are so variable, and so dependent upon -unknown conditions in the past, that it is very difficult to estimate the -result for any long period of time. Occasionally a quarter of an inch of -stalagmite accretion has been known to take place in a cavern in a single -year, while in Kent's Cavern, over a visitor's name inscribed in the -year 1688, a film of stalagmite only a twentieth of an inch in thickness -has accumulated. If, therefore, we could reckon upon a uniformity of -conditions stretching indefinitely back into the past, we could determine -the age of these oldest remains of man in Kent's Hole by a simple sum in -arithmetic, and should infer that the upper layer of stalagmite required -240,000 years, and the lower 576,000 years, for their growth, which would -carry us back more than 700,000 years, and some have not hesitated to -affix as early a date as this to these lowest implement-bearing gravels. - -But other portions of the cave show an actual rate of accretion very much -larger. Six inches of stalagmite is there found overlying some remains of -Romano-Saxon times which cannot be more than 2,000 years old. Assuming -this as the uniform rate, the total time required for the deposit of the -stalagmitic floors would still be about 70,000 years. But, as we have -seen, the present rates of deposition are probably considerably less than -those which took place during the moister climate of the Glacial epoch. -Still, even by supposing the rate to be increased fourfold, the age of -this lower stratum would be reduced to only 12,000 years. So that, as Mr. -James Geikie well maintains, "Even on the most extravagant assumption as -to the former rate of stalagmitic accretion, we shall yet be compelled -to admit a period of many thousands of years for the formation of the -stalagmitic pavements in Kent's Cavern."[EL] We should add, however, -that there is much well-founded doubt whether the implements found -in the lowest stratum were really in place, since, according to Dr. -Evans, "Owing to previous excavations and to the presence of burrowing -animals, the remains from above and below the stalagmite have become -intermingled."[EM] - -[Footnote EL: Prehistoric Europe, p. 83.] - -[Footnote EM: Stone and Flint Implements, p. 446.] - -An attempt was made by M. Morlot in Switzerland to obtain the chronology -of the Glacial period by studying the deltas of the streams descending -the glaciated valleys. He paid special attention to that of the Tinière, -a stream which flows into Lake Geneva near Villeneuve. The modern delta -of this stream consists of gravel and sand deposited in the shape of a -flattened cone, and investigations upon it were facilitated by a long -railroad cutting through it. "Three layers of vegetable soil, each of -which must at one time have formed the surface of the cone, have been -cut through at different depths."[EN] In the upper stratum Roman tiles -and a coin were found; in the second stratum, unvarnished pottery and -implements of bronze; while in the lower stratum, at a depth of nineteen -feet from the surface, a human skull was found, to which Morlot assigned -an age of from 5,000 to 7,000 years. - -[Footnote EN: Lyell's Antiquity of Man, p. 28.] - -But Dr. Andrews, after carefully revising the data, felt confident that -the time required for the whole deposit of this lower delta was not more -than 5,000 years, and that the oldest human remains in it, which were -about half way from between the base and the surface of the cone, were -probably not more than 3,000 years old. - -Still, the significance of this estimate principally arises from the -relation of the modern delta to older deltas connected with the Glacial -period. Above this modern delta, formed by the river in its present -proportions, there is another, more ancient, about ten times as large, -whose accumulation doubtless took place upon the final retreat of the -ice from Lake Geneva. No remains of man have been found in this, but it -doubtless corresponds in age with the high-level gravels in the valley -of the Somme, in which the remains of man and the mammoth, together with -other extinct animals, have been found. - -We do not see, however, that any very definite calculation can be made -concerning the time required for its deposition. Lyell was inclined to -consider it ten times as old as the modern delta, simply upon the ground -of its being ten times as large. On Morlot's estimate of the age of the -modern delta, therefore, the retreat of the ice whose melting torrents -deposited the upper delta would be fixed at 100,000 years ago, and upon -Dr. Andrews's calculation, at about 20,000. - -But it is evident that the problem is not one of simple multiplication. -The floods of water which accompanied the melting back of the ice from -the upper portions of this valley must have been immensely larger than -those of the present streams, and their transporting power immensely -greater still. Hence we do not see that any conclusions can be drawn from -the deltas of the Tinière to give countenance to extreme views concerning -the date of the close of the Glacial period.[EO] - -[Footnote EO: Lyell's Antiquity of Man, p. 321.] - -In the valley of the Somme the chronological data relating to the Glacial -period, and indicating a great antiquity for man, have been thought to -be more distinct than anywhere else in Europe. As already stated, it -is the prevalent opinion that since man first entered the valley, in -connection with the mammoth and the other extinct animals characteristic -of the Glacial period, the trough of the Somme, about a mile in width and -a hundred feet in depth, has been eroded by the drainage of its present -valley. An extensive accumulation of peat also has taken place along the -bottom of the trough of the river since it was originally eroded to its -present level. This substance occurs all along the bottom of the valley -from far above Amiens to the sea, and is in some places more than thirty -feet in depth. The animal and vegetable remains in it all belong to -species now inhabiting Europe. - -The depth of the peat indicates that when it was formed the land stood -at a slightly higher elevation than now, for the base of the stratum is -now below the sea-level, while the peat is of fresh-water origin, and, -according to Dr. Andrews,[EP] is formed from the vegetable accumulations -connected with forest growths. When, therefore, the country was covered -with forests, as it was in prehistoric times, the accumulation must have -proceeded with considerable rapidity. This inference is confirmed by the -occurrence in the peat of prostrate trunks of oak, four feet in diameter, -so sound that they were manufactured into furniture. The stumps of trees, -especially of the birch and alder, were also found in considerable -number, standing erect where they grew, sometimes to a height of three -feet. Now, as Dr. Andrews well remarks, it is evident that, in order -to prevent these stumps and prostrate trunks from complete decay, the -accumulation of peat must have been rapid. From certain Roman remains -found six feet and more beneath the surface, he estimates that the -accumulation since the Roman occupation has been as much as six inches a -century, at which rate the whole would take place in somewhat over 5,000 -years. - -[Footnote EP: American Journal of Science, October, 1868.] - -Still, if we accept this estimate, we have obtained but a starting-point -from which to estimate the age of the high-level gravels in which -palæolithic implements were found; for, if we accept the ordinary theory, -we must add to this the time required for the river to lower its bed from -eighty to a hundred feet, and to carry out to the sea the contents of -its wide trough. But, as already shown, the Glacial period was, even in -the north of France, a time of great precipitation and of a considerable -degree of cold, when ice formed to a much greater extent than now upon -the surface of the Somme. The direct evidence of this consists in the -boulders mingled with the high-level gravel which are of such size as to -require floating ice for their transportation. - -In addition to the natural increase in the eroding power of the Somme -brought about by the increase in its volume, on account of the greater -precipitation in the Glacial age, there would also be, as Prestwich has -well shown, a great increase in rate through the action of ground-ice, -which plays a very important part in the river erosion of arctic -countries, and in all probability did so during the Glacial period in the -valley of the Somme. - -"When the water is reduced to and below 32° Fahr., although the rapid -motion may prevent freezing on the surface for a time, any pointed -surfaces at the bottom of the river, such as stones and boulders, will -determine (as is the case with a saturated saline solution) a sort of -crystallisation, needles of ice being formed, which gradually extend from -stone to stone and envelop the bodies with which they are in contact. By -this means the whole surface of a gravelly river-bed may become coated -with ice, which, on a change of temperature, or of atmospheric pressure, -or on acquiring certain dimensions and buoyancy, rises to the surface, -bringing with it the loose materials to which it adhered. Colonel Jackson -remarks, in speaking of this bottom-ice, that 'it frequently happens that -these pieces, in rising from the bottom, bring up with them sand and -stones, which are thus transported by the current.... When the thaw sets -in the ice, becoming rotten, lets fall the gravel and stones in places -far distant from those whence they came.' - -"Again, Baron Wrangell remarks that, 'in all the more rapid and rocky -streams of this district [northern Siberia] the formation of ice takes -place in two different manners; a thin crust spreads itself along the -banks and over the smaller bays where the current is least rapid; but the -greater part is formed in the bed of the river, in the hollows among the -stones, where the weeds give it the appearance of a greenish mud. As soon -as a piece of ice of this kind attains a certain size, it is detached -from the ground and raised to the surface by the greater specific gravity -of the water; these masses, containing a quantity of gravel and weeds, -unite and consolidate, and in a few hours the river becomes passable -in sledges instead of in boats.' Similar observations have been made -in America; but instances need not be multiplied, as it is a common -phenomenon in all arctic countries, and is not uncommon on a small scale -even in our latitudes. - -"The two causes combined--torrential river-floods and rafts of -ground-ice, together with the rapid wear of the river cliffs by -frost--constituted elements of destruction and erosion of which our -present rivers can give a very inadequate conception; and the excavations -of the valleys must have proceeded with a rapidity with which the present -rate of erosion cannot be compared; and estimates of time founded on -this, like those before mentioned on surface denudation, are therefore -not to be relied upon."[EQ] - -[Footnote EQ: Prestwich's Geology, vol. ii, pp. 471, 472.] - -Speaking a little later of taking the present rates of river erosion as a -standard to estimate the chronology of the Glacial period, the same high -authority remarks: "It no more affords a true and sufficient guide than -it would be to take the tottering paces and weakened force of an old man -as the measure of what that individual was, and what he could do, in his -robust and active youth. It may be right to take the effects at present -produced by a given power as the known quantity, a, but it is equally -indispensable, in all calculations relative to the degree of those -forces in past times, to take notice of the unknown quantity, x, although -this, in the absence of actual experience, which cannot be had, can only -be estimated by the results and by a knowledge of the contemporaneous -physical conditions. It may be a complicated equation, but it is not to -be avoided.[ER] - -[Footnote ER: Prestwich's Geology, vol. ii, pp. 520, 521.] - -"In this country and in the north of France broad valleys have been -excavated to the depth of from about eighty to a hundred and fifty feet -in glacial and post-glacial times. Difficult as it is by our present -experience to conceive this to have been effected in a comparatively -short geological term, it is equally, and to my mind more, difficult to -suppose that man could have existed eighty thousand years or more, and -that existing forms of our fauna and flora should have survived during -two hundred and forty thousand years without modification or change."[ES] - -[Footnote ES: Ibid., p. 533.] - -The discussion of the age of the high-level river gravels of the Somme -and other streams in northwestern Europe is not complete, however, -without considering another possibility as to the mode of their -deposition. The conclusion to which Mr. Alfred Tylor arrived, after a -prolonged and careful study of the subject, was that the main valleys of -the Somme and other streams in northern France and southern England were -preglacial in their origin, and that the accumulations of gravel at high -levels along their margin were due to enormous floods which characterised -the closing portion of the great ice age, which he denominated the -pluvial period.[ET] The credibility of floods large enough to accomplish -the results manifest in the valley of the Somme is supported by reference -to a flood which occurred on the Mulleer River, in India, in 1856, when -a stream, which is usually insignificant, was so swollen by a rainfall -of a single day that it rose high enough to sweep away an iron bridge the -bottoms of whose girders were sixty-five feet above high-water mark. One -iron girder weighing eighty tons was carried two miles down the river, -and nearly buried in sand. The significance of these facts is enhanced -by observing also that for fifteen miles above the bridge the fall of -the river only averaged ten feet per mile. Floods to this extent are -not uncommon in India. During the Glacial period spring freshets, must -have been greatly increased by the melting of a large amount of snow and -ice which had accumulated during the winter, and also by the formation -of ice-gorges near the mouths of many of the streams. It is probable, -also, that the accumulation of ice across the northern part of the German -Ocean may have permanently flooded the streams entering that body of -water; for it is by no means improbable that there was a land connection -between England and France across the Straits of Dover until after the -climax of the Glacial period. In support of his theory, Mr. Tylor points -to the fact "that the gravel in the valley of the Somme at Amiens is -partly derived from _débris_ brought down by the river Somme and by the -two rivers the Celle and the Arve, and partly consists of material from -the adjoining higher grounds washed in by land floods," and that the -"Quaternary gravels of the Somme are not separated into two divisions by -an escarpment of chalk parallel to the river," but "thin out gradually as -they slope from the high land down to the Somme." - -Mr. Tylor's reasoning seems especially cogent to one who stands on the -ground where he can observe the size of the valley and the diminutive -proportions of the present stream. Even if we do not grant all that is -claimed by Mr. Tylor, it is difficult to resist the main force of his -argument, and to avoid the conclusion that the valley of the Somme is -largely the work of preglacial erosion, and has been, at any rate, only -in slight degree deepened and enlarged during post-Tertiary time. - -[Footnote ET: Proceedings of the Geological Society, London, November 8, -1867, pp. 103-126: Quarterly Journal of the Geological Society, February -1, 1869, pp. 57-100.] - - -Summary. - -In briefly summarising our conclusions concerning the question of man's -antiquity as affected by his known relations to the Glacial period, it is -important, first, to remark upon the changes of opinion which have taken -place with respect to geological time within the past generation. Under -the sway of Sir Charles Lyell's uniformitarian ideas, geologists felt -themselves at liberty to regard geological time as practically unlimited, -and did not hesitate to refer the origin of life upon the globe back to -a period of 500,000,000 years. In the first edition of his Origin of -Species Charles Darwin estimated that the time required for the erosion -of the Wealden deposits in England was 306,662,400 years, which he spoke -of as "a mere trifle" of that at command for establishing his theory of -the origin of species through natural selection. In his second edition, -however, he confesses that his original statement concerning the length -of geological time was rash; while in later editions he quietly omitted -it. - -Meanwhile astronomers and physicists have been gradually setting limits -to geological time until they have now reached conclusions strikingly -in contrast with those held by the mass of English geologists forty -years ago. Mr. George H. Darwin, Professor of Mathematics at Cambridge -University, has from a series of intricate calculations shown that -between fifty and one hundred million years ago the earth was revolving -from six to eight times faster than now, and that the moon then almost -touched the earth, and revolved about it once every three or four hours. -From this proximity of the moon to the earth, it would result that if the -oceans had been then in existence the tides would have been two hundred -times as great as now, creating a wave six hundred feet in height, -which would sweep around the world every four hours. Such a condition -of things would evidently be incompatible with geological life, and -geology must limit itself to a period which is inside of 100,000,000 -years. Sir William Thomson and Professor Tait, of Great Britain, and -Professor Newcomb, of the United States Naval Observatory, approaching -the question from another point of view, seem to demonstrate that the -radiation of heat from the sun is diminishing at a rate such that ten -or twelve million years ago it must have been so hot upon the earth's -surface as to vaporise all the water, and thus render impossible the -beginning of geological life until later than that period. Indeed, they -seem to prove by rigorous mathematical calculations that the total amount -of heat originally possessed by the nebula out of which the sun has been -condensed would only be sufficient to keep up the present amount of -radiation for 18,000,000 years. - -The late Dr. Croll, feeling the force of these astronomical conclusions, -thought it possible to add sufficiently to the sun's heat to extend its -rule backwards approximately 100,000,000 years by the supposition of a -collision with it of another moving body of near its own size. Professor -Young and others have thought that possibly the heat of the sun might -have been kept up by the aid of the impact of asteroids and meteorites -for a period of 30,000,000 years. Mr. Wallace obtains similar figures by -estimating the time required for the deposition of the stratified rocks -open to examination upon the land surface of the globe. As a result of -his estimates, it would appear that 28,000,000 years is all the time -required for the formation of the geological strata. From all this it is -evident that geologists are much more restricted in their speculations -involving time than they thought themselves to be a half-century ago. -Taking as our standard the medium results attained by Wallace, we shall -find it profitable to see how this time can be portioned out to the -geological periods, that we may ascertain how much approximately can be -left for the Glacial epoch. - -On all hands it is agreed that the geological periods decrease in length -as they approach the present time. According to Dana's estimates,[EU] -the "ratio for the Palæozoic, Mesozoic, and Cenozoic periods would be -12:3:1"--that is, Cenozoic time is but one sixteenth of the whole. -This embraces the whole of the Tertiary period, during which placental -mammals have been in existence, together with the post-Tertiary or -Glacial period, extending down to the present time; that is, the time -since the beginning of the Tertiary period and the existence of the -higher animals is considerably less than two million years, even upon Mr. -Wallace's basis of calculation. But if we should be compelled to accept -the calculations of Sir William Thomson, Professor Tait, and Professor -Newcomb, the Cenozoic period would be reduced to considerably less than -one million years. It is difficult to tell how much of Cenozoic time is -to be assigned to the Glacial period, since there is, in fact, no sharply -drawn line between the two periods. The climax of the Glacial period -represented a condition of things slowly attained by the changes of level -which took place during the latter part of the Tertiary epoch. - -[Footnote EU: See revised edition of his Geology, p. 586.] - -In order to estimate the degree of credibility with which we may at -the outset regard the theory of Mr. Prestwich and others, that all the -phenomena of the Glacial period can be brought within the limits of -thirty or forty thousand years, it is important to fix our minds upon -the significance of the large numbers with which we are accustomed to -multiply and divide geological quantities.[EV] - -[Footnote EV: See Croll's Climate and Time, chap. xx.] - -Few people realise either the rapidity with which geological changes -are now proceeding or the small amount of change which might produce a -Glacial period, and fewer still have an adequate conception of how long a -period a million years is, and how much present geological agencies would -accomplish in that time. At the present rate at which erosive agencies -are now acting upon the Alps, their dimensions would be reduced one half -in a million years. At the present rate of the recession of the Falls of -St. Anthony, the whole gorge from St. Louis to Minneapolis would have -been produced in a million years. A river lowering its bed a foot in a -thousand years would produce a cañon a thousand feet deep in a million -years. - -If we suppose the Glacial period to have been brought about by an -elevation of land in northern America and northern Europe, proceeding at -the rate of three feet a century, which is that now taking place in some -portions of Scandinavia, this would amount to three thousand feet in one -hundred thousand years, and that is probably all, and even more than all, -which is needed. One hundred thousand years, therefore, or even less, -might easily include both the slow coming on of the Glacial period and -its rapid close. Prestwich estimates that the ice now floating away from -Greenland as icebergs is sufficient if accumulating on a land-surface -to extend the borders of a continental glacier about four hundred and -fifty feet a year, or one mile in twelve years, one hundred miles in -twelve hundred years, and seven hundred miles (about the limit of glacial -transportation in America) in less than ten thousand years. - -After making all reasonable allowances, therefore, Prestwich's conclusion -that twenty-five thousand years is ample time to allow to the reign -of the ice of the Glacial period cannot be regarded as by any means -incredible or, on _a priori_ grounds, improbable. - - - - -APPENDIX. - - -THE TERTIARY MAN. - -By Professor Henry W. Haynes. - -"It must not be imagined that it is in any way proved that the -Palæolithic man was the first human being that existed. We must be -prepared to wait, however, for further and better authenticated -discoveries before carrying his existence back in time further than -the Pleistocene or post-Tertiary period."[EW] This was the position -assumed more than twelve years ago by the eminent English geologist -and archæologist, Dr. John Evans, and it was still maintained in his -address before the Anthropological Section of the British Association on -September 18, 1890. I believe that the study of all the evidence in favor -of the existence of the Tertiary man that has been brought forward down -to the present time will leave the question in precisely the same state -of uncertainty. - -[Footnote EW: _A Few Words on Tertiary Man_, Trans, of Hertfordshire Nat. -Hist. Soc, vol. i, p. 150.] - -"In order to establish the existence of man at such a remote period the -proofs must be convincing. It must be shown, first, that the objects -found are of human workmanship; secondly, that they are really found as -stated; and, thirdly, the age of the beds in which they are found must be -clearly ascertained and determined."[EX] These tests I propose to apply -to the evidence for the Tertiary man recently brought forward in Europe, -and then to consider the significance of certain discoveries on the -Pacific coast of our own continent. - -[Footnote EX: Ibid., p. 148.] - -Tertiary deposits in Europe are alleged to have supplied three sorts of -evidence of this fact: _First_, the bones of man himself; _second_, bones -of animals showing incisions or fractures supposed to have been produced -by human agency; _third_, chipped flints believed to exhibit marks of -design in their production. - -A very complete survey of the question of the antiquity of man was -published in 1883 by M. Gabriel de Mortillet, one of its most eminent -investigators, under the title of Le Préhistorique. In that work he -subjected to a most rigid examination all the evidence for Tertiary man, -coming under either of these three heads, that had been brought forward -up to that date. - -The instances of the discovery of human bones in Europe were two--at -Colle del Vento, in Savona, and Castenedolo, near Brescia, both in Italy. -At the former site, in a Pliocene marine deposit abounding in fossil -oysters and containing some _scattered_ bones of fossil mammals, a human -skeleton was found _with the bones lying in their natural connection_. -Mortillet, however, and many others regard this as an instance of a -subsequent interment rather than as proof that the man lived in Pliocene -times.[EY] At Castenedolo, in a similar marine Pliocene formation, on -three different occasions human skeletons have been discovered, but -in different strata. One investigator has accounted for these as the -result of a shipwreck in the Pliocene period. This bold hypothesis not -only requires that man should have been sufficiently advanced at that -very remote period to have navigated the sea, but it calls for two -shipwrecks, at different times, at the same point. It has, however, since -been abandoned by its author in favor of the presumption of subsequent -interments, as in the previous instance.[EZ] - -[Footnote EY: This is also the opinion of Hamy, _Précis de Paléontologie -Humaine_, p. 67. Professor Le Conte, _Elements of Geology_ (third -edition, 1891), p. 609, is wrong in attributing the opposite conclusion -to Hamy, on the evidence of "flint implements found in this locality."] - -[Footnote EZ: Bullettino di Paletnologia Italiana, tome xv, p. 109 -(August 18, 1889).] - -Animal bones showing cuts or breaks supposed to be the work of man have -been found in seventeen different localities in Europe. They can all, -however, be accounted for as the result of natural movements or pressure -of the soil acting in connection with sharp substances, like fractured -flints, or else as having been made by the teeth of sharks, whose fossil -remains are found in great abundance in the same formation. - -All the discoveries of flints supposed to show traces of intentional -chipping are pronounced to be unsatisfactory, with the exception of -those found in three localities--Thenay (near Tours) and Puy-Courny -(near Aurillac), in France, and Otta, in the valley of the Tagus, in -Portugal. As European archæologists at the present time are substantially -in accord with Mortillet in restricting the discussion to these three -places, I will follow their example. But although Mortillet believes -that flints found at all these localities exhibit marks of intelligent -action, he will not admit that they are the work of man. He attributes -them to an intelligent ancestor of man, whom he calls by the name -of anthropopithecus, or the precursor of man. Of this creature he -distinguishes three different species, named respectively after the -discoverers of the flints in the three localities just mentioned. The -precursor, however, has found up to this time only a very limited -acceptance among men of science, although a few believe in him on purely -theoretical grounds. The discussion generally turns upon the question -whether these flints were chipped intentionally or are the result of -natural causes; and also upon the determination of the geological age of -the formations in which they are found. - -[Illustration: Fig. 108.--Flint flakes collected by Abbé Bourgeois from -Miocene strata at Thenay (after Gaudry). Natural size.] - -I visited Thenay, the most celebrated of these three localities, in 1877, -and had the advantage of studying the question there under the guidance -of the late Abbé Bourgeois, the discoverer of the flints, and one of the -most prominent advocates of the Tertiary man. This was the year before -he died, and he showed me at the time his complete collection, and gave -me several of the objects he had discovered. Geologists are agreed in -assigning the deposits in which they occur to the lower Miocene or middle -Tertiary period, which restricts the discussion to the character of the -flints themselves. The accompanying woodcut[FA] gives some indication -of their appearance, although it is misleading, because the long figure -resembling a flint knife is intended to represent a solid nucleus. None -of these objects, however, ought to be called "flints flakes," as very -few, if any, flakes showing the "bulb of percussion," always seen upon -them, have been discovered in the Tertiary deposits at Thenay,[FB] -although I have found them there myself _upon the surface_. The three -other figures would be classed by archæologists as "piercers," as -Bourgeois has himself designated them, and are also solid objects. Many -of the Thenay flints exhibit a "crackled" appearance, due to the action -of heat. On this account Mortillet maintains that they were splintered -by fire, and not formed by percussion, the usual method by which flint -implements were fabricated in the stone age. The Thenay objects are -all of very small dimensions, and are so absolutely unlike the large, -rudely-chipped axes of the Chellean type, found in so many different -parts of the world, and generally accepted as the implement used by -Palæolithic man, that the question naturally suggests itself, What could -have been the purpose for which these little implements were employed? No -better answer has been suggested than the ludicrous one that they were -used by the hairy anthropopithecus to rid himself of the vermin with -which he was infested. - -[Footnote FA: From Le Conte, _op. cit._, p. 608. The figures are copied -from Gaudry, who borrowed them from the article by Bourgeois, _Congrès -Internat. de Bruxelles_, 1872, p. 89, pl. ii; and from his _La Question -de l'Homme Tertiare_. Revue des Questions Scientifiques, 1877, p. 15.] - -[Footnote FB: Le Préhistorique, p. 91.] - -But, leaving aside the question of their purpose, let us consider -the evidence presented by the flints themselves. Do they exhibit the -unmistakable traces of intentional chipping produced by a series of -slight blows or thrusts, delivered in regular succession and in the -same direction, with the result of forming a distinctly marked edge? -And does the appearance of the action of fire upon their surface imply -the intervention of intelligence? To both questions M. Adrien Arcelin, -the well-known geologist of Mâcon, has given very sufficient replies in -the negative. He has discovered numerous objects of precisely similar -appearance in Eocene deposits in the neighborhood of Mâcon.[FC] But, -instead of pushing man back on this account so much further into the -past, he accounts for the marks of chipping to be seen on many of these -objects as the result of the accidental shocks of one stone against -another in the countless overturnings and movements to which the -strata have been subjected during the long ages of geological time. He -gives photographs of some of these objects, which are to me entirely -convincing, and describes how he has surprised Nature in the very act of -fabricating them in an abandoned quarry worked in an Eocene deposit. He -thinks the "crackled" surfaces can be readily explained as the result -of atmospheric action, or of hot springs charged with silex. Numerous -examples of similar changes in the surface of flint, that have been -noticed by himself and others in different localities, are instanced. -Even if some have been caused by fire, this does not necessarily imply -the intervention of man to have produced it. Similar discoveries have -also been made by M. d'Ault de Mesnil, at Thenay, in Eocene deposits,[FD] -and by M. Paul Cabanne, in the Gironde.[FE] My own opinion, based -upon the experience of many years spent in the study of flints broken -naturally as well as artificially, and upon a careful examination of -Bourgeois's collections, is that the so-called Thenay flints are the -result of natural causes. - -[Footnote FC: Matériaux pour l'Histoire Prim, et Nat. de l'Homme, tome -xix, p. 193.] - -[Footnote FD: Matériaux, ibid., p. 246.] - -[Footnote FE: Id., tome xxii, p. 205.] - -The second locality where flints alleged to display marks of human action -have been found is the vicinity of Aurillac, in the Auvergne, especially -on the flanks of a hill called Puy-Courny. They occur in a conglomerate -of the upper Miocene period, and are consequently much later than the -Thenay flints. In this conglomerate, in 1869, M. Tardy discovered a -worked flint flake which has every appearance of being artificial.[FF] -Mortillet, however, says that it was found in the upper surface of the -deposit, where there may easily have been a mingling with the Quaternary -formation; and it certainly resembles worked flakes, which are not -uncommon in the Quaternary. The geological determination of the find may -consequently be regarded as uncertain. - -[Footnote FF: See Matériaux, tome vi, p. 94. S. Reinach, however, -_Description Raison. du Musée de Saint-Germain-en-Laye_, i, p. 107, n. 8, -calls it "gravure inexacte."] - -The flints discovered at Puy-Courny by M. Barnes are of small dimensions, -and have all been produced by percussion. Many of them are said to -bear some resemblance to pointed flakes of artificial origin, and -one has been figured, probably selected for its excellence.[FG] It is -by no means convincing to me, and I am not at all surprised that so -many archæologists question the artificial character of these objects, -which exhibit a great variety of forms. Upon this point Rames does -not profess to be qualified to pronounce judgment, limiting himself -solely to the geological questions. He argues, however, that the fact -that all the objects supposed to be artificial are made of the best -qualities of flint, of which implements are ordinarily made, although -fragments of inferior quality are abundant in the same formation, -implies the intervention of man's judgment in making the selection. -But M. Boule shows that this is merely the result of the erosion of an -ancient river, which operated only upon the upper beds, in which alone -the better qualities of flint are to be found; and Rames has accepted -this explanation.[FH] The flints of Puy-Courny seem to fall within the -same category as those of Thenay. They are the product of denudation, -have travelled long distances, and have been subjected to the action of -powerful agents. These causes are sufficient to account for the shocks of -which they show the traces, and to explain the production of splinters -arising therefrom. - -[Footnote FG: Matériaux, tome xviii, p. 400.] - -[Footnote FH: Revue d'Anthropologie (third series), tome iv, p. 217.] - -The last locality in which flints claimed to have been manufactured by -the Tertiary man are supposed to have been discovered is the so-called -desert of Otta, in the valley of the Tagus, not far from Lisbon. - -The formation there is a lacustrine deposit of great thickness, belonging -to the upper Miocene, and abounding in flint. Here, during the course of -twenty years, M. Ribeiro discovered, but mostly upon the surface, a large -number of flakes of flint and quartzite. After much debate in regard to -them, ninety-five of them were finally sent by him to Paris, in 1878, and -placed in the archæological department of the great exposition. There -they were to be submitted to the judgment of the assembled prehistoric -archæologists of all nationalities, many of whom, including the writer, -availed themselves of the opportunity of carefully studying them. The -judgment of Mortillet is that twenty-two specimens exhibited unmistakable -traces of intentional chipping, in which opinion I entirely concur. -Only nine, however, were represented as coming from the Miocene, some -of which showed on their surface an incrustation of grit, which was -claimed as proof of their origin. But the opinion was freely expressed -that, even if they really came from the Miocene deposits, they might -have penetrated into them from the surface, through cracks, and thus -have become so incrusted. It was accordingly resolved to hold the next -international congress of prehistoric archæologists at Lisbon, in 1880, -mainly for the purpose of settling this question, if possible, by an -investigation conducted upon the spot. In the course of a visit made at -that time to Otta, several artificial specimens were found on the surface -by different searchers, but Professor Bellucci, of Perugia, was fortunate -enough to discover a flint flake _in situ_, still so closely imbedded -in the deposit that it required to be detached by a hammer. There is no -question that this object was actually found in a Miocene deposit, but -unfortunately it belongs to the doubtful category of external flakes, -which, although they exhibit the "bulb of percussion," have no other -sure indication that they are the work of man.[FI] As such bulbs can -be produced by natural causes, some stronger proof than this of the -existence of Tertiary man is demanded. - -[Footnote FI: It has been figured by Bellucci, _Archivio per -l'Anthropologia e la Etnologia di Firenze_, tome xi, p. 12, tav. iv, fig. -2. To me it possesses no value as evidence.] - -These are all the localities in Europe claimed by Mortillet to have -furnished such evidence, but he thinks a strong confirmation of it -is afforded by certain discoveries made in the auriferous gravels of -California. I will not occupy space here in repeating arguments I have -brought forward elsewhere to show the utter insufficiency of this -evidence to prove the existence of man on the Pacific coast of our -continent during the Pliocene period,[FJ] They may all be summed up in -the words of Le Conte: "The doubts in regard to this extreme antiquity -of man are of three kinds, viz.: 1. Doubts as to the Pliocene age of the -gravels--they may be early Quaternary. 2. Doubts as to the authenticity -of the finds--no scientist having seen any of them in situ. 3. Doubts -as to the undisturbed conditions of the gravels, for auriferous gravels -are especially liable to disturbance. The character of the implements -said to have been found gives peculiar emphasis to this last doubt, _for -they are not Paleolithic_, but Neolithic."[FK] The question has been -raised whether this archæological objection is applicable to the stone -mortars, numerous examples of which have been found in the gravels, some -of them quite recently.[FL] If the evidence brought forward by Professor -Whitney and others were limited to these mortars, it might very well -be claimed that they are neither Palæolithic nor Neolithic; that the -smoothness of their surface is owing to their having been hollowed out of -pebbles that have been polished and worn by natural forces. But Professor -Whitney has cited numberless instances of "spear-heads," "arrow-heads," -"discoidal stones," "stone beads," and "a hatchet" that have been found -under precisely similar conditions as the mortars. So Mr. Becker has -recently produced an affidavit of a certain Mr. Neale that in a tunnel -run into the gravel in 1877 "between two hundred and three hundred feet -beyond the edge of the solid lava, he saw several spear-heads nearly -one foot in length."[FM] Now it cannot be questioned that such objects -as these clearly belong to the Neolithic period, which does not imply -that all the objects used at that time were polished, but that together -with chipped implements "polished stone implements were also used."[FN] -No archæologist will believe that, while Palæolithic man has not yet -been discovered in the Tertiary deposits of western Europe, the works of -Neolithic man have been found in similar deposits in western America. -Peculiar difficulties seem to surround the evidence brought forward -in support of such an assumption. We are told by Professor Whitney -that a stone mortar was "found standing upright, and the pestle was -in it, in its proper place, just as it had been left by the owner." -He fails, however, to explain how this was brought about in a gravel -deposit supposed to have been laid down by great floods of water. So, -when Mr. Neale swears that he saw fifteen years ago in the same gravels -spear-heads a great deal larger than those known to archæologists, may -we not ask whether reliance can be placed on the memory of witnesses who -testify to impossibilities to justify conclusions that rest upon such -testimony? I think we shall have to wait for further and better evidence -than this before we are called upon to admit that the existence of the -Tertiary man upon our Pacific coast has been established. - -[Footnote FJ: _The Prehistoric Archæology of North America_, Narrative -and Critical History of America, vol. i, pp. 850-356.] - -[Footnote FK: Le Conte, _op. cit._, p. 614.] - -[Footnote FL: Professor George Frederick Wright, _Prehistoric Man on the -Pacific Coast_, Atlantic Monthly, April, 1891, p. 512; _Table Mountain -Archæology_, Nation, May 21, 1891, p. 419.] - -[Footnote FM: _Antiquities from under Tuolome Table Mountain in -California_, Bulletin of the Geological Society of America, vol. ii, p. -192.] - -[Footnote FN: Le Conte, _op. cit._, p. 607.] - - - - -INDEX. - - - Aar Glacier, 11, 43, 132. - Abbeville, France, 251, 263. - Abbott, C. C, cited, 242, 245. - Adams, Charles Francis, cited, 297. - Adhémar, cited, 307, 310. - Africa, ancient glaciers of, 191. - Agassiz, Louis, cited, 9, 11, 43, 128, 241. - Ailsa Crag, 167, 168. - Akron. Ohio, 220, 221. - Alaska, 1, 22, 23 _et seq._, 47, 212, 283; - climate of, 291, 302. - Aletsch Glacier, 9, 211, 241. - Alleghany Valley, 206, 214; - terraces in, 229. - Alpine glaciers, existing, 9-11, 43 _et seq._; - size and number of, 9; - depth of, 11; - velocity of, 43 _et seq._; - ancient, 58-60, 131-136; - advance and retreat of, 116. - Alps, 1, 9-11, 43 _et seq._, 58 _et seq._, 91, 131 _et seq._, 211; - age of, 328. - Altaville, Cal, 296. - Amazon Valley, temperature of, 316. - Amherst, Ohio, glacial marks near, 52. - Amiens, France, implements from, 252, 263 _et seq._; - terraces at, 360. - Andes, 17, 330; - age of, 328. - Andover, Mass., 77 _et seq._, 345. - Andrews, cited, 345, 347, 354, 356. - Animals, extinct, associated with man in eastern America, 262; - in France, 263; - in England, 264 _et seq._; - in Wales, 272; - in Belgium, 277 _et seq._; - summary concerning, 281-293. - Animals, relics of, in loess, 188. - Antarctic Continent, existing glaciers of, 1, 18 _et seq._ - Arcy, Belgium, grotto at, 279. - Arenig Mawr, Wales, 150, 151, 172. - Argillite implement, face and side view of, 247, 259. - Arnhem, Holland, moraine at, 181. - Asia, existing glaciers in, 14 _et seq._; - ancient glaciers of, 190. - Assiniboine River, 228. - Astronomical theories of the Glacial period, 303 _et seq._ - Atlantic Ocean, 314. - Aurillac, supposed flint-chips near, 367, 370. - Australia, ancient glaciers of, 126, 192. - Austria, existing glaciers of, 9. - Auvergne, 136. - - Babbitt, Miss F. E., cited, 253, 254, 255. - Bakewell on age of Niagara gorge, 337. - Baldwin, C. C, 251. - Baldwin, P., 25. - Ball, cited, 310, 317. - Baltic Sea, 129. - Barnsley, England, 155. - Bates, cited, 204. - Bear, 270, 287, 290. - Bear, grizzly, 270, 288. - Beaver, 289. - Beaver Creek, Pa., 205, 230, 232. - Becker, cited, 296, 300, 349. - Bedford, England, 265. - Beech Flats, Ohio, terrace at, 217. - Belgium, human relics in glacial terraces in, 264; - caverns of, 274. - Bell, cited, 109, 117; - on unity of the Glacial period, 110. - Bellevue, Pa., glacial terrace on the Ohio at, 217. - Bellucci, cited, 372. - Ben Nevis, 240. - Bernese Oberland, 9, 59, 131, 132. - Big Stone Lake, 208, 226. - Birmingham. England, 150. - Bishop, cited. 306. - Bison, 262, 270, 271, 278, 289. - Black Forest, the, 136. - Black River, Ohio, 343. - Black Sea, 238. - Blanc, Mont, 1, 9-11, 132, 211. - Blandford, cited, 312. - Boone County, Ky., glacial deposits in, 212. - Boston, scratched stone from till of, 54; - drumlins in the vicinity of, 75. - Boston Society of Natural History, 296. - Boulder-clay. (See Till.) - Boulders, disintegrated, 57, 71. - Boulders, distribution of, in New-England, 57, 60, 61, 69 _et seq._; - in Switzerland, 58 _et seq._, 133. - Boulders, transportation of, in Pennsylvania, 57, 61, 85; - in New Hampshire, 60, 71; - in Kentucky, 63, 97; - in Ohio, 64, 72; - in Rhode Island, 67; - in Massachusetts, 69 _et seq._; - in Connecticut, 71, 72; - in New Jersey, 83; - in Illinois, 97. - Bourgeois, Abbé, cited, 367. - Bridgenorth, England, 150. - Bridlington, England, 156, 158. - Bristol Channel, 138, 178. - British Columbia, 1, 23, 121 _et seq._, 194, 198. - British Isles, ancient glaciers of, 136-181; - preglacial level of land in, 139-141; - preglacial climate in 141, 142; - great glacial centres-- - Wales, 143; - Ireland, 143; - Galloway, 144; - Lake District, 144; - Pennine Chain, 144; - confluent glaciers-- - Irish Sea Glacier, 145-153; - Solway Glacier, 153-158; - East Anglian Glacier, 158; - Isle of Man, 164-167; - the so-called Great Submergence, 167-180; - dispersion of erratics of Shap granite, 180, 181; - drainage of, 238; - caverns of, 267; - climate of, 314. - Brixham Cave, 267 _et seq._ - Bromsgrove, England, 150. - Brooklyn, N. Y., 66, 67. - Brown, on glaciers of Greenland, 40, 41. - Brown's Valley, 226. - Bruce, skull of, 276. - Buried forests in America, 107 _et seq._ - Buried outlets and channels, 199-210; - of Lake Erie, 201, 333; - of Lake Huron, 202; - of Lake Ontario, 202; - of Lake Superior, 203; - of Lake Michigan, 203; - in southwestern Ohio, 203; - near Cincinnati, 203; - near Louisville, Ky., 205; - in the Tuscarawas Valley, 205; - in the valley of the Beaver, 205; - of oil Creek, 205; - in the valley of the Alleghany, 206; - of Chautauqua Lake, 207; - near Minneapolis, 208. - Burton, England, 164. - Busk, cited, 267. - Buttermere, England, 153, 168. - - Cache Valley, Utah, 233. - Cae Gwyn Cave, 148, 271 _et seq._, 280. - Caithness, Scotland, 180. - Calaveras skull, 295, 300. - California, 21, 124, 281, 287, 294, 358, 372. - Cambridgeshire, England, 158. - Canada, 94, 95. - Canstadt, man of, 279. - Canton, Ohio, 232. - Cape St. Roque, 31 3. - Caribbean Sea, 318. - Caribou, 262. - Carll, cited, 205, 207. - Carpathian Mountains, 136, 328. - Carpenter, F. R., cited, 321, 322. - Cascade Range, 21. - Caspian Sea, 238. - Cattaraugus Creek, N. Y., 220. - Caucasus Mountains, 15; - age of, 328. - Cave-bear, 269-271, 278, 280; - hyena, 269, 270, 278; - lion, 269-271, 278. - Caverns, British, 267-274; - on the Continent, 274-281. - Cefn Cave, 148, 271. - Cenis, Mont, 135. - Centres of glacial dispersion, 304 _et seq._, 323 _et seq._, 328; - in America, 113, 121; - in Europe, 129 _et seq._; - in the British Isles, 142 _et seq._ - Cevennes, 136. - Chamberlin, T. C, terminal moraine of second Glacial epoch, 93, - 98 _et seq._; - on driftless area, 102, 103; - cited, 110, 218, 229, 307; - on Cincinnati ice-dam, 218. - Chamois, 289, 290. - Chamouni, 132. - Charpentier, 9, 59. - Chasseron, 58, 132. - Chautauqua Lake, buried outlet of, 207. - Chenango River, 220. - Cheshire, England, 149,153,178,180. - Cheyenne River, 228. - Chicago, Ill., 346. - Chimpanzee, skull of, 276. - Chur, 133. - Cincinnati, buried channels near, 203 _et seq._; - glacial dam at, 212 _et seq._; - terraces at, 231. - Clarksburg, W. Va., 216. - Claymont, Del., 258 _et seq._; - view of implement found near, 259. - Claypole, cited, 200, 219, 221. - Climate of Glacial period, 291. - Clwyd, vale of, 147 _et seq._. 271 _et seq._ - Clyde, the, 144. - Collett, cited, 107. - Colorado, 123, 124. - Columbia deposit, 245, 254 _et seq._ - Columbiana County, Ohio, 232. - Comstock, cited, 307. - Conewango Creek, 232; - ancient depth of, 206. - Connecticut, 71, 72, 74, 91. - Conyers, cited, 265. - Cook on subsidence in New Jersey, 196. - Cope, cited, 288. - Cordilleran Glacier, 121 _et seq._ - Corswall, England, 312. - Cows, 268. - Cresson, cited, 251, 258 _et seq._ - Crevasses. (See Fissures.) - Croll, cited, 304, 307 _et seq._, 332, 362. - Cro-Magnon, rock shelter of, 281. - Cromer, England, 160. - Crosby, on composition of till, 81 _et seq._ - Cross Fell escarpment, 153, 180. - Culoz, 132. - Cumberland, England, 146, 153, 168, 173. - Gumming, quoted, 166. - Gushing, H., 26 - Cuyahoga River, 220, 221; - buried channel of, 200. - - Dana, Professor J. D., on depth of ice, 91; - on driftless area, 102; - cited, 320, 363. - Danube, ancient glaciers of the, 129, 134, 188. - Darent, valley of, 265. - Darrtown, Ohio, 107. - Darwin, Charles, cited, 17, 126, 170, 241, 361. - Darwin, George G., cited, 361. - Darwin, Mrs. M. J., mortar owned by, 297. - Date of Glacial period, chapter on, 332-364. - Davidson Glacier, 23. - Davis on drumlins, 75. - Dawkins, cited, 238, 267, 269, 291. - Dawson, G. M., cited, 121; - on ice-movements, 97; - on oscillation of land-level, 125, 126. - Dawson, Sir William, on the fiord of the Saguenay, 197; - cited, 285. - Dee, the river, 149. - Deeley, quoted, 164. - Delaware River, 232, 242 _et seq._, 254, 258; - section across the, 245. - Delta terrace at Trenton, N. J., 242 _et seq._; - at Beaver, Pa., 230. - De Ranee, cited, 272. - Derbyshire, England, 270. - Desor on age of Niagara gorge, 337. - Diore, glaciers of the, 135. - Disintegration, amount of, near glacial margin, 117, 118. - Diss, England, 266. - Dnieper, the, 185, 188. - Don, the, 185, 188. - Dora Baltea, 134. - Dover, N. H., section of kame near, 77. - Dover, Straits of, 238. - Drave, glaciers in the, 134. - Drainage systems in the Glacial period, 335, 339, 340, 343, 344; - chapter on, 193-241. - Drayson, cited, 317. - Driftless area in the Mississippi Valley, 101, 102. - Drumlins, description of, 73 _et seq._; - view of, 73; - occurrence of, in Massachusetts, 73; - in New Hampshire, 74; - in Connecticut, 74; - in New York, 74, 94; - in the British Isles, 74, 137, 167. - Dunbar, Scotland, 312. - Dupont, cited, 279. - Du Quoin, Ill., 98, 119. - D'Urville, 20. - Düsseldorf, 275. - - Eagle, Wis., view of kettle-moraine near, 99. - East Anglian Glacier, 158-164. - Eccentricity of the earth's orbit, 308. - Eden Valley, 180. - Eggischorn, 211, 241. - Eguisheim, skull found at, 279. - Elephant, 265, 280, 282, 283, 292. - Elevation, preglacial, 112, 194, 198; - the cause of the Glacial period, 113, 320-331; - about the Great Lakes, 224; - in the latitude of New York, 261. - Elyria, Ohio, 342. - Engis skull, view of, 274. - England. (See British Isles.) - Enville, England, 150. - Erosion, preglacial, 193 _et seq._ - Erosion in river valleys, 198, 329, 332. - Erzgebirge, 136, 181. - Europe, existing glaciers in, 9, _et seq._, 43 _et seq._; - ancient glaciers of, 129-190; - former elevation of, 238; - ice-dams in, 360. - Evans, cited, 263, 267, 354, 365. - - Falconer, cited, 263. - Falls of St Anthony, 200. - Faudel, cited, 279. - Fiesch, Switzerland, 131, 211. - Filey Brigs;, Eng., 155. - Finchley, Eng., 158, 159. - Finger Lakes, 94. - Finsteraarhorn, 9. - Fiords, 194 _et seq._; - of Greenland, 212. - Fissures in glacial ice, 3, 48, 49. - Flamborough, 140, 156, 157, 176. - Florida, 314. - Flower, cited 263. - Forbes, 9, 38, 43, 44, 48. - Forel, M., cited, 116. - Fort Snelling, Mississippi gorge at, 208, 340 _et seq._ - Fort Wayne, Incl., 220, 224. - Foshay, cited, 119. - Fox, 270, 289, 290. - Fraipont, cited, 275 _et seq._ - France, existing glaciers of, 19; - ancient glaciers of, 136; - glacial gravels of, 262 _et seq._ - Frankley Hill, England, 150. - Franklin, Pa., 230, 232. - Franz-Josef Land, 14. - Frederickshaab Glacier, 91, 212. - Frere, cited, 266. - Frickthal, 133. - Frondeg, Wales, 149, 178. - - Gabb, cited, 318. - Galloway, ancient glaciers of, 144, 145, 154, 157, 167, 168, 173. - Garda, Lake, moraine in front of, 135. - Garonne, the, 136, 188. - Gaudry, cited, 263. - Geikie, Archibald, cited, 272, 312. - Geikie, James, on kames, 76; - on loess, 187, 188; - cited, 291 _et seq._, 307, 353. - Genesee River, 220. - Geological time, 361 _et seq._ - Georgian Bay, 339. - German Ocean, 129. - Germantown, Ohio, 107, 108. - Germany, North, moraine in, 181, 183; - glacial lakes in, 238; - Quaternary animals in, 279. - Gietroz Glacier, 211. - Gilbert, cited, 233 _et seq._, 350 _et seq._; - on age of Niagara gorge, 339. - Glacial dispersion. (See Centres of Glacial Dispersion.) - Glacial boundary in New England, 67; - in New Jersey, 83; - in Pennsylvania, 84 _et seq._; - in New York, 84; - in Ohio, 95, 100, 106; - in Kentucky, 96; - in Indiana, 96; - in Illinois, 96, 100; - in Kansas, Nebraska, Missouri, Montana, South Dakota, 96; - in Minnesota, 101; - in British Isles, 137, 148, 150, 151, 155, 167; - in Holland, 181; - in Germany, 181, 183; - in Russia, 181, 189. - Glacial erosion, 118, 119, 182. - Glacial ice, depth of, in Pennsylvania, 90 _et seq._; - in Connecticut, 91; - in New York. 91; - in Greenland, 91; - in the Alps, 91, 131, 133, 182; - in Germany, 182; - in Norway, 182; - amount of, 330. - Glacial lakes in Germany, 283. - Glacial motion, limit of, 2; - chapter on, 43-50; - plastic theory of, 48. - Glacial outlets of the Great Lakes, 220-222. - Glacial periods, cause of, 113; - chapter on, 302-331; - date of, chapter on, 332-364. - Glacial periods, supposed succession of, 106 _et seq._, 311, 324-326, - 332; - criticisms of the theory, 116 _et seq._ - Glacial striæ. (See Rock-Scoring.) - Glacial terraces, 229-238; - in Pennsylvania, 87 _et seq._, 215, 217, 229, 230; - in New York, 88; at Beech Flats, Ohio, 217; - at Granville, Ohio, 227; - on the Minnesota River, 228; - around Great Salt Lake, 233 _et seq._; - on Delaware River, 243 _et seq._; - in Europe, 238-241; - in Ohio, 249 _et seq._; - human relics in, 241-267; - on Delaware River, 245; - of the Mississippi River, 254; - in France, 263 _et seq._, 360; - in England, 264 _et seq._; - in Belgium, 264; - in Spain, 264; - in Portugal, 264; - in Italy, 264; - in Greece, 264. - Glacial theory, crucial tests of, 62, 65, 257, 302 _et seq._ - Glaciation, signs of past, chapter on, 51 _et seq._ - Glacier Bay, 24; - map of, 25. - Glacier, denned, 2; - formation of, 3; - characterised by veins and fissures, 3; - advance and retreat of, 116; - velocity of, in the Alps, 43 _et seq._; - in Greenland, 36, 46-48; - in Alaska, 47. - Glaciers, ancient, in North America, 66-128; - in Central and Northern Europe, 58-60, 131-136; - in the British Isles, 136-181; - in Northern Europe, 181-190; - in Australia, 126, 192; - in Asia, 190, 191; - in Africa. 191, 192. - Glaciers, existing, in the Alps, 9 _et seq._, 43 _et seq._; - in Scandinavia, 12; - in Spitzbergen, Nova Zembla, and Franz-Josef Land, 12; - in Iceland, 14; - in Asia, 14 _et seq._; - in Oceanica, 16; - in South America, 17; - in Antarctic Continent, 18 _et seq._; - in North America, 20 _et seq._; - in Greenland, 32 _et seq._, 46, 48, 364. - Glen Roy, parallel roads of, 239. - Glutton, 293. - Goat, 268. - Goffstown, N. H., 73. - Grafton, W. Va., 214. - Grand Haven, Mich., 346. - Granville, Ohio, terrace at, 227, 343. - Grape Creek, Col., view of moraines of, 123. - Great Bend, Pa., depth of river-channel at, 206. - Great Lakes, depth of, 115; formation of, 199 _et seq._; - glacial outlets of, 220-222; - elevation about, 224. - Great Salt Lake, Utah, 233 _et seq._, 350. - Greece, human relics in glacial terraces of, 264. - Greenland, existing glaciers of, 1, 32 _et seq._, 46, 48,364; - map of, 33; - climate of, 302. - Gross Glockner, 9, 134. - Ground ice, 357. - Gulf of Mexico, 313, 318. - Gulf Stream, 13, 311, 313, 317 _et seq._ - Guyot, 9, 58, 133. - - Haas, 16. - Hall, on the age of Niagara, 336. - Hare, 289. - Harrison, quoted, 167. - Harte, Bret, cited, 296. - Hartz Mountains, 136, 181. - Hayes, 36. - Haynes on Tertiary Man, 365-374. - Heald Moor, England, 147. - Hebrides, the, 136. - Heim, 9. - Helland, 14, 46-48. - Hennepin, cited, 340. - Heme Bay, England, 265. - Herschel, cited, 310. - Hertfordshire, England, 158. - Hicks, Dr. II., cited, 272. - Hicks, L. E., cited, 343. - Himalayas, 1,45, 292, 330; - age of, 328. - Hingham, Mass., section of kame near, 79. - Hippopotamus, 263, 265, 271, 280, 284, 285, 290, 292. - Hitchcock, C. II., discovery of boulders on Mount Washington, 60; - on drumlins, 73; - cited, 309, 313. - Hitchcock, E., on kames, 77. - Holland, terminal moraine in, 181. - Holderness, 157. - Hooker, cited, 191. - Horse, 188, 263, 268-270, 272, 278, 280, 288, 289. - Horseheads, N. Y., 220. - Horseshoe Fall, 337 _et seq._ - Hottentot skull, 276. - Hoxney, England, 266. - Hudson River, preglacial channel of, 194 _et seq._ - Hugi, 9, 43. - Hungary, Quaternary animals in, 279. - Huxley, cited, 276, 278. - Hyena, 271, 272, 282, 291, 292. - - Ibex, 289. - Icebergs, 18, 20; - formation of, 28. - Ice, characteristics of, 2, 48 _et seq._, 302 _et seq._; - transporting power of moving, 5. - Ice-dams, 211-228; - in the Alps, 211; - in the Himalayas, 211; - in Greenland, 212; - in Alaska, 212; - at Cincinnati, 213 _et seq._; - across the Mohawk, 92, 220, 334, 335; - in the Red River of the North, 225; - in Europe, 360. - Iceland, existing glaciers of, 1, 14. - Ice-pillars, 6, 27. - Ice-sheet, retreat of, 333 _et seq._ - Idaho, 122; lava-beds of, 297. - Illicilliwaet Glacier, 23. - Illinois, 96-98, 100, 119, 121, 345 _et seq._ - Indiana, 96, 98, 107, 119, 121. - Indian Ridge, 80. - Iowa, 98, 101. - Ireland, ancient glaciers of, 143. - Irish elk, 270, 278, 288. - Irish Sea Glacier, 137, 145-153, 164, 271. - Irthing, valley of the, 153. - Isère, glaciers of the, 132. - Isle of Man, 164-167. - Isle of Wight, 266. - Italy, existing glaciers of, 9; - ancient glaciers of, 185; - human relics in glacial terraces of, 264; - supposed Tertiary man in, 366. - Ivrea, 134. - - Jackson, cited, 357. - Jackson's Lake, 123. - Jakobshavn Glacier, velocity of, 46, 47; - depth of, 91; - ice-dams of, 212. - James, cited, 204. - James River, Dak., 228. - James River, Va., 257. - Jamieson, cited, 330. - Jensen, 91. - Judge's Cave, 72. - Jura Mountains, ancient glaciers of, 58-60, 132. - - Kames, formation of, 7, 76, 77; - of Muir Glacier, 29, 30; - in Massachusetts, 77 _et seq._; - in New Hampshire, 80; - map of, in Maine, 81; - in Pennsylvania, 87. - Kanawha River, 216. - Kane, 36-38. - Kansas, 96. - Kelly's Island, view of grooves on, 103, 105. - Kendall, chapter by. 137-181; - cited, 273. - Kent, England, 265. - Kent's Hole, 267 _et seq._, 352 _et seq._ - Kentucky, 63, 96, 97, 212; - view of boulder in, 63. - Kentucky River, 214. - Kettle-holes, formation of, 7, 68; - of Muir Glacier, 29, 30; - in New England, 66 _et seq._, 344, 345; - in Pennsylvania, 86; - sedimentation of, 333, 344 _et seq._ - Kettle-moraine in Wisconsin, 100. - King, 21, 351; - implement discovered by, 297. - Knox County, Ohio, 232. - Kurtz, Nam pa image discovered by, 297. - - Lake Agassiz, 126, 223, 225; - continuance of, 347 _et seq._ - Lake Bonneville, 233 _et seq._, 299, 350 _et seq._ - Lake Constance, 60, 133. - Lake Erie, origin of, 200 _et seq._; - ridges around, 222; - preglacial outlet of, 200, 333. - Lake Geneva during the Glacial period, 131, 132. - Lake Huron, preglacial outlet of, 202; - ridges around, 224. - Lake Itasca, 254. - Lake Lahontan, 233, 234. - Lake Michigan, age of, 345 _et seq._ - Lake Nipissing, 339. - Lake Ontario, origin of, 201 _et seq._ - Lake Traverse, 208, 226. - Lake District, England, the, 144. - Lake dwellings in Switzerland, 281. - Lake ridges, 222 _et seq._ - Lakes, sedimentation of, 333, 344 _et seq._ - Lamplugh, glacial observations of, 140, 196. - Lancashire, 153, 178, 180. - Lancaster, Ohio, 232. - Lang, cited, 116. - Lark, England, valley of the, 266. - Lateral moraines, 5. - Laurentide Glacier, 113 _et seq._, 121, 321. - Lava on the Pacific coast of North America, 294, 298, 300, 306, 321. - Lawrence, Mass., 80. - Lawrenceburg, Ind., 231, 232. - Le Conte, cited, 286, 322 _et seq._, 330, 372. - Leicestershire, England, 158. - Lehigh River, 243. - Lemming, 289. - Lenticular hills, 73. - Leopard, 282. - Lesley, cited, 215. - Lesse, Belgium, valley of the, 279. - Leverett, cited, 101, 218. - Lewis, on transported boulders, 57, 61; - work of, in Pennsylvania, 84, 119; - in Great Britain, 137; - cited, 254 _et seq._, 273. - Lickey Hills, 151. - Licking River, 214. - Liége, Belgium, 274. - Lincolnshire, England, 158. - Lindenkohl on old channel of the Hudson, 195 _et seq._ - Lion, 282, 293. - Little Beaver Creek, 231, 232. - Little Falls, Minn., 225, 232, 252, 254. - Little Falls, N. Y., buried channel near, 202. - Livingston, Mont., 122. - Llangollen, vale of, 151. - Loess in the Mississippi Valley, 98, 119, 120; - in Europe, 186 _et seq._ - Lohest, cited, 275 _et seq._ - Lombardy, 134. - London, 158, 159, 178; - glacial terrace in, 264. - Long Island, 66, 67. - Louisville, Ky., buried channel near, 205. - Loveland, Ohio, 232, 250. - Lubbock, cited, 267. - Lucerne, 133. - Lyell, on Richmond train of boulders, 70; - cited, 239, 263, 267, 274, 276, 285, 355, 361; - on the age of Niagara, 336. - Lyons, 132. - - Maack, cited, 318. - Macclesfield, England, 273. - MacEnery, cited, 267. - Machairodus, 270, 282. - Mackintosh, quoted, 149, 150, 173. - Mâcon, France, 369. - McTarnahan, mortar discovered, by 297. - Madison boulder, 71. - Madisonville, Ohio, 232, 250, 254. - Magdalena Bay, 13. - Mahoning River, 220. - Maine, 80; re-elevation of, 331. - Malaspina Glacier, map of, 31. - Mammoth, 188, 190, 263, 265, 269-272, 278, 280, 283-285, 287, 292, 293. - Man, relics of, in the Glacial period, chapter on, 242-301; - in glacial terraces of the United States, 242-262; - of Europe, 262-267; - in cave deposits of British Isles, 148, 267-274; - of the Continent, 274-281; - under lava-beds of the Pacific coast of North America, 294-301; - extinct animals associated with, 281-293. - Manitoba, 97. - Mankato, Minn., 229. - Marcilly, skull at, 279. - Marietta, Ohio, 231. - Marmot, 289, 293. - Marsh Creek Valley, Utah, 233. - Martigny, ancient glaciers near, 59, 60, 131, 211. - Massachusetts, 67 _et seq._, 73, 77 _et seq._, 81, 344, 345. - Mastodon, 262, 278, 285, 286. - Mattmark See, 211. - Maumee River, 220. - McGee, cited, 245, 254 _et seq._ - Medial moraines, formation of, 6; - of Muir Glacier, 27; - in Ohio, 100. - Medlicott, cited, 312. - Medora, Ind., 232, 251, 254. - Menai Straits, 145. - Mentone, skeleton of, 281. - Mer de Glace, 11, 44. - Merjelen See, 211, 241. - Mersey, the, 140. - Meteorites, 305. - Metz, cited, 250. - Meuse, valley of, 274 _et seq._ - Miami, the Great, 204, 220. - Miami, the Little, 231, 250. - Millersburg, Ohio, 232. - Mills, cited, 251. - Minneapolis, 232; buried outlet near, 208; - recession of falls at, 210, 340 _et seq._, 364. - Minnehaha, Falls of, 342. - Minnesota, 101, 107, 252 _et seq._; - lakes of, 344. - Minnesota River, a glacial outlet, 208, 225, 228, 342. - Miocene epoch, animals of the, 285. - Mississippi River, gorge of, at Fort Snelling, 208, 364; - terraces on, 229; - erosion by, 329; - glacial drainage of, 335, 340. - Missouri Coteau, 101, 126, 228. - Missouri, 96, 98, 119. - Moel Tryfaen, 145, 167 _et seq._, 178, 273. - Mohawk River, glacial drainage of, 92, 202, 335; - ice-dam across, 220, 334, 335. - Mohegan Bock, 71; view of, 72. - Monongahela River, 214 _et seq._ - Montaigle, valley of the, 279. - Montana, 96. - Montreal, re-elevation of, 331. - Moose, 262. - Moraines, formation of, 6; - in Wisconsin, 98-100; - in Italy, 134, 135; - between Speeton and Flamborough, 156; - in Germany, 183. - Morecambe Bay, 146, 180. - Morgantown, W. Va., 215. - Morlot, cited, 354. - Mortillet, cited, 366, 369, 372. - Morvan, the, 136. - Moulins, formation of, 7. - Mount Shasta, 21. - Mount Washington, 61. - Mueller Glacier, 17. - Muir Glacier, 24 _et seq._. 47, 68, 212; - view of front of, 26. - Muir, John, 24. - Muskingum River, 220, 231. - Musk ox, 262, 280. - Musk sheep, 289, 290, 293. - - Nampa image, 297 _et seq._ - Nansen, 39, 41. - Naulette, jaw found at, 278, 279. - Neale, implements discovered by, 296, 373. - Neanderthal skull, 275 _et seq._ - Nebraska, 96. - Nelson River, 349. - Neufchâtel, 133. - Nevada, 124; lakes of, 233. - Névé-field defined, 3. - Newark, Ohio, 232. - Newberry on the preglacial drainage of the Hudson, 195 _et seq._; - on the formation of the Great Lakes, 202 _et seq._; - cited, 320. - Newburg, N. Y., 286. - New Comerstown, implement from, 232, 250, 251 _et seq._, 254. - New England, 57, 60, 61, 91; - ancient glaciers in, 66-83. - New Hampshire, 69, 71, 74, 80. - New Harmony, Ind., 232. - New Jersey, 83. - New Lisbon, Ohio, 232. - New York, 74, 84, 88, 91, 92 _et seq._ - New York Bay, 184, 197, 249. - New Zealand, 1, 126, 192, 330. - Niagara gorge, age of, 333 _et seq._; - section of strata along the, 336. - Nile River, 285. - Nordenskiöld, 32, 34. - Norfolk, England, 161. - North America, existing glaciers in, 20 _et seq._ - North Sea, 238. - Norway, climate of, 314. - Nottingham, England, 164. - Nova Zembla, 14. - - Oberlin, Ohio, 64, 344. - Oceanica, existing glaciers of, 16, 17. - Ohio River, glacial terrace, 217, 229. - Ohio, 64,72, 95, 98, 100, 103, 106,107-117, 119, 217, 249 _et seq._, - 343, 344. - Oil Creek, 205, 232. - Olmo, skull at, 279. - Oregon, 21, 124. - Orme's Head, Little, 147. - Orton, cited, 72, 107. - Oscillations of land-level in America, 124 _et seq._ - Oswestry. England, 173. - Ottawa River, 339. - Otter, 290. - Ouse, valley of the, 265. - Ox, 269, 270. - - Pacific coast of America, 349. - Pacific Ocean, 318, 320. - Panama, Isthmus of, 113, 313, 314, 318. - Parsimony, law of, 117. - Pasterzen Glacier, 134. - Patagonia, 1. - Patton, 25. - Payer, 14, 39. - Peat-beds, 68, 125; - in Ohio, 107; - in Minnesota, 108; - in valley of the Somme, 355 _et seq._ - Pembina River, 228. - Pengelly, cited, 267, 270. - Pennine Chain, glaciation of, 137, 144, 146, 147, 154, 177. - Pennsylvania, 57, 61, 84 _et seq._, 119, 217. - Perry County, Ohio, 232. - Perthes, Boucher de, 262 _et seq._ - Philadelphia Academy of Sciences, 296. - Philadelphia, red gravel of, 254 _et seq._ - Phillips, cited, 267. - Picardy, glacial gravels of, 262. - Pittsburg, Pa., submergence of, 214, 217, 230. - Plum Creek, Ohio, 344. - Po, valley of the, 135; - erosion by, 328. - Pocatello, Idaho, 236, 299. - Pocono Mountain, 61. - Poland, 181. - Polynesian skull, 276. - Pomp's Pond, section of kettle-hole near, 345. - Portageville, N. Y., 220. - Port Neuf River, Idaho, 236. - Portsmouth, Ohio, 231. - Portugal, human relics in glacial terraces of, 264; - supposed Tertiary man in, 367, 371 _et seq._ - Post-glacial erosion, 332 _et seq._; - in Ohio, 343, 344; - in Illinois, 345 _et seq._ - Potomac River, 256 _et seq._ - Pot-holes in Lucerne, 133. - Pouchet, cited, 263. - Precession of equinoxes, 308. - Preglacial climate in England, 141, 142. - Preglacial levels in England, 139-142. - Prestwich, cited, 186, 189, 263 _et seq._, 284; - on date of Glacial period, 354, 357, 363, 364. - Provo shore-line, 237. - Putnam, cited, 250. - Puy-Courny, France, supposed Tertiary man at, 367, 370, 371. - Pyramid Lake, 350. - Pyrenees, glaciers of the, 11, 136; - Quaternary animals of, 280, 282; - age of, 328. - - Quaternary animals of California, 281, 287; - in Germany, 279; - in Hungary, 279. - Quatrefages, cited, 276. - Queenston, Canada, 333 _et seq._ - - Rabbit, 289. - Raccoon Creek, 343; - view of glacial terrace near, 227. - Rames, cited, 370, 371. - Ramsay, cited, 311. - Rappahannock River, 257. - Rawhide Gulch, Cal., 296. - Recession, rate of, of Falls of Niagara, 333 _et seq._; - of Falls of St. Anthony, 340 _et seq._, 364; - of Black River, 342, 343. - Red deer, 263. - Red River of the North, 209, 228, 340; - ice-dam in, 225. - Regillout, 263. - Reid, Clement, quoted, 162. - Reid, H. F., 26, 47. - Reindeer, 188, 262, 263, 269, 270, 278, 280, 287, 290, 293. - Rhine, ancient glaciers of the, 129, 133. - Rhinoceros, 188, 263, 265, 271, 277, 278, 280, 284, 286, 287, 292; - woolly, 269, 270, 272, 280, 287. - Rhode Island, 67. - Rhône, ancient glaciers of, 58-60, 131,132, 185, 188; - map of, 58. - Richmond, Mass., train of boulders in, 70, 71. - Rink, Dr., 35. - Roanoke River, 257. - Rocky Mountains, 320, 322; - age of the, 328. - Rock-scorings, cause of, 51 _et seq._; - in New England, 69; - on islands of Lake Erie, 103, 104; - in Pennsylvania, 119; - in Ohio, 103, 119; - in Indiana, 119; - in Illinois, 119; - in Missouri, 119. - Roman remains, 356. - Rome, N. Y., 335. - Rosa, Mount, 9, 134, 211. - Ross, Sir J. C, 18, 19, 311. - Royston, England, 155. - Runaway Pond, 207. - Russell, I. C, exploration of Mount St. Elias by, 30, 212; - cited, 233, 350 _et seq._ - Russia, glacial boundary in, 181, 189; - glacial drainage of, 238. - - Saguenay, fiord of the, 197. - Salamanca, N. Y., buried channels near, 206. - Salisbury, cited, 183, 184. - Salt Lake City, 123. - Sandusky, Ohio, section of the lake ridges near, 223. - Sandusky River, 220. - Sanford, cited, 267. - Saskatchewan River, 228. - Saxony, 181. - Scandinavia, existing glaciers of, 2, 12; - ancient glaciers of, 129, 136, 157, 181-190; - re-elevation of, 331. - Scioto River, 231. - Scotland. (See British Isles.) - Seattle, section of till in, 55. - Second Glacial period, 106 _et seq._ - Section, ideal, across river bed in drift region, 229. - Sedimentation of lakes, 333. - Seine, terraces of the, 186, 188, 264. - Seracs, 4, 5. - Settle, England, 270. - Severn, the, 149-151, 285. - Shaler, 67, 242. - Shap granite, 154, 157, 180. - Ship Rock, 71. - Shone, cited, 180. - Shoshone Falls, 299. - Shrewsbury, England, 150. - Shropshire, England, 149, 173. - Siberia, 190; - Quaternary animals in, 280, 282, 283, 290; - climate of, 302, 316. - Sierra Nevada Mountains, 21, 294, 301, 320, 322, 349, 352. - Skertchly, quoted, 159. - Skipton, 144, 146. - Skull, comparative study of, 276. - Slickenside, 53. - Smock on depth of glacial ice, 90. - Snake River Valley, 236 _et seq._, 298. - Snowdon, 145, 171. - Snowy vole, 289. - Soleure, 133. - Solferino, 135. - Solway Glacier, 153, 155, 180. - Somme, terraces of the, 186, 262 _et seq._, 285, 286, 355, 359 _et seq._ - Sonora, Cal., 294 _et seq._ - South America, existing glaciers of, 17; - ancient glaciers in, 126. - Southampton, England, 266. - South Dakota, 96, 98. - Spain, ancient glaciers of, 136; - human relics in glacial terraces of, 264; - Quaternary animals of, 280. - Speeton, 140, 155, 156. - Spencer, cited, 224. - Spencer, N. Y., 220. - Spitsbergen, 12. - Spy, man of, 275, 277. - St. Acheul, 263. - Stag, 289. - Stainmoor, England, 154, 157, 180. - Stalagmite, rate of accumulation of, 352 _et seq._ - Stanislaus River, Cal., 294. - St. Anthony, Falls of, 340 _et seq._, 364. - Steamburg, N. Y., buried channel at, 206. - St. Elias, 30 _et seq._, 212. - St. Lawrence River, glacial drainage of, 335, 339. - St. Louis, Mo., 119, 364. - St. Paul, Minn., 228. - Stone on kames in Maine, 80. - Straits of Dover, 360. - Straits of Gibraltar, 292. - Striæ, direction of, in New Hampshire, 69; - in Lake Erie, 104; - presence of, in Pennsylvania, 85, 119; - in Ohio, Indiana, Illinois, and Missouri, 119; - in Stuttgart, 279. - Subglacial streams, 23, 29, 120. - Submerged channels on the coasts of America, 194-198. - Submergence theory, 60-63, 70. - Subsidence of the Isthmus of Panama, 113, 318; - in Mississippi Valley, 93, 113, 120, 121; - on east coast of North America, 255 _et seq._; - about the Great Lakes, 224, 339; - in Great Britain, 167-181. - Susquehanna River, glacial drainage of, 93, 232, 257. - Svartisen Glacier, 13. - Svenonius, Dr., 12. - Sweden, 81. - Switzerland, existing glaciers of, 9-11; - ancient glaciers of, 131-136; - lake-dwellings in, 281. - - Table Mountain, Cal., 294 _et seq._, 300. - Table of changes during the Glacial epochs, 324, 325. - Tagus, valley of the, 367, 371 _et seq._ - Tait, cited, 362. - Tardy, cited, 370. - Tasman Glacier, 16. - Teesdale, England, 155, 157. - Terminal moraines, formation of, 6; - in Pennsylvania, 61, 62, 85 _et seq._; - on the southern coast of New England, 66 _et seq._; - in Ohio, 106; - in Puget Sound, 122; - in Tyghee Pass, 122; - in Italy, 135. - Terminal moraines of the second Glacial epoch, 93, 100, 101, 106. - Terraces. (See Glacial Terraces.) - Tertiary animals, 286. - Tertiary man, 365-374. - Tertiary period, climate of, 113, 117, 182, 305, 307. - Teton Mountains, 123. - Texas, Pleistocene animals of, 288. - Thames, England, 138, 264, 285. - Thenay, France, supposed Tertiary man in, 367, 371; - view of flint-flakes collected at, 368. - Thompson, 50. - Thomson, cited, 362. - Till, description of, 53; - composition of, in Massachusetts, 81 _et seq._; - section of, in Ohio, 108; - depth of, in Germany, Scandinavia, and Russia, 182. - Tinière River, 354. - Titusville, Pa., 232. - Todd, on forest beds and old soils,110 _et seq._; - cited, 228. - Torquay, England, 267. - Trade-winds of the Atlantic, 314, 318. - Tremeirchon, Wales, 271. - Trenton, N. J., 87, 232, 242 _et seq._, 254, 257; - view of implement found at, 247. - Trenton gravel, section of the, 246. - Trent, valley of the, 163, 164. - Trimmer, quoted, 148. - Trimingham, England, 162. - Trogen, Switzerland, 60. - Trons, Switzerland, 60. - Tuolumne County, Cal., 294, 299. - Turin, 135. - Tuscarawas Valley, 220, 221, 232, 251; - buried channel in, 205. - Tylor, cited, 359 _et seq._ - Tyndall, 44-46, 49. - Tynemouth, England, 155, 157. - Tyrol, 134, 135, 211. - Tyrrell, cited, 109. - - Ulm, 134. - Upham, on drumlins, 73; - on two ice-movements, 97; - cited, 222, 253 _et seq._, 301, 318, 320 _et seq._, 330, 348; - on the Columbia gravel, 261; - on date of the Glacial period, 344. - Ural Mountains, 15, 280. - Utah, 123; - lakes of, 233. - Utica, N. Y., 220. - Utrecht, moraine near, 181. - - Valais, the, 133. - Vegetable remains in glacial deposits, 117, 125; - in Ohio, 107, 117; - in Indiana, 107; - in Minnesota, 107, 109; - in Iowa, 108; - in British America, 109. - Veins in glacial ice, 3. - Vermont, Runaway Pond in, 207. - Vernagt Glacier, 211. - Vessel Rock, view of, 56. - Vezère, valley of, 281. - Victoria Cave, England, 270, 280. - Virginia City, 349. - Vivian, cited, 267. - Volga, the, 185. - Vosges Mountains, 136. - - Wabash River, 220, 231, 232. - Wahsatch Mountains, 237. - Wales, ancient glaciers of, 143, 150 _et seq._; - caverns of, 271. - Wallace, cited, 331, 343, 362. - Walrus, 262, 285. - Warren, Pa., buried channel near, 206. - Warren River, 226. - Washington, 1, 21, 122. - Washington, D. C., gravel deposit of, 254. - Water, transporting power of running, 5, 51-53. - Waveney, England, valley of the, 266. - Wealden formation, 361. - Weasel, 290. - Wells, England, 270. - Western Reserve Historical Society, 104. - Weston, W. Va., 216. - West Virginia, 214 _et seq._; - glacial terrace in, 216. - Wey, valley of the, 265. - Whitby, England, 155. - White, cited, 215 _et seq._ - White River, Ind., 232, 251. - White Sea, 181. - Whitney, 14, 21, 295, 349, 373. - Whittlesey, 100. - Wild-boar, 290. - Wild-cat, 290. - Winchell, Alexander, cited, 321, 330. - Winchell, N. H., cited, 107, 210, 252; - on the Falls of St. Anthony, 341 _et seq._ - Wisconsin, 98, 99, 100, 101. - Woeikoff, cited, 316. - Wolf, 270, 290. - Wolverine, 289. - Wood, cited, 179. - Woodward, quoted, 160; - on age of Niagara, 337 _et seq._ - Wookey Hole, England, 270. - Wrangell, cited, 357. - Wright, 373. - - Yankton, 120. - Yellowstone Park, 122. - Yorkshire, 140, 154, 155, 157, 176, 270, 283, 286. - Yosemite Park, 21, 350. - Young, Rev. Mr., 24. - Young, Professor, cited, 362. - Younglove, 104. - - Zermatt Glacier, view of, 2. - Zuyder Zee, 181. - - -THE END. - - - * * * * * - - -D. APPLETON & CO.'S PUBLICATIONS. - - -_THE ICE AGE IN NORTH AMERICA, and its Bearings upon the Antiquity of -Man._ By G. Frederick Wright, D. D., LL. D., F. G. S. A., Professor in -Oberlin Theological Seminary; Assistant on the United States Geological -Survey. With an appendix on "The Probable Cause of Glaciation," by Warren -Upham, F. G. S. 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Serviss's book, 'Astronomy with an Opera-Glass,' offers - us an admirable hand-book and guide in the cultivation of this noble - æsthetic discipline (the study of the stars)."--_New York Home Journal_. - - "The book should belong to every family library."--_Boston Home Journal_. - - "This book ought to make star-gazing popular."--_New York Herald_. - - "The author attributes much of the indifference of otherwise - well-informed persons regarding the wonders of the starry firmament to - the fact that telescopes are available to few, and that most people have - no idea of the possibilities of the more familiar instrument of almost - daily use whose powers he sets forth."--New Orleans Times-Democrat. - - - "By its aid thousands of people who have resigned themselves to the - ignorance in which they were left at school, by our wretched system of - teaching by the book only, will thank Mr. Serviss for the suggestions he - has so well carried out."--_New York Times_. - - "For amateur use this book is easily the best treatise on astronomy yet - published."--Chicago Herald. - - "'Astronomy with an Opera-Glass' fills a long-felt want."--_Albany - Journal_. - - "No intelligent reader of this book but will feel that if the author - fails to set his public star-gazing the fault is not his, for his style - is as winning, as graphic, and as clear as the delightful type in which - it is printed."--_Providence Journal_. - - "Mr. Serviss neither talks over the heads of his readers nor ignores - the sublime complexity and range of his themes, but unites simplicity - with scholarship, scientific precision with life-long enthusiasm, and a - genuine eloquence with rare touches of humor. Considered as a product - of the publishing industry, the book is elegance itself."--_The - Chautauquan_. - -New York: D. APPLETON & CO., 72 Fifth Avenue. - - - * * * * * - - -D. APPLETON & CO.'S PUBLICATIONS. - - -_OUTINGS AT ODD TIMES._ By Charles C. Abbott, author of "Days out of Doors" -and "A Naturalist's Rambles about Home." 16mo. Cloth, gilt top, $1.25. - - "A charming little volume, literally alone with Nature, for it discusses - seasons and the fields, birds, etc., with the loving freedom of a - naturalist born. Every page reads like a sylvan poem; and for the lovers - of the beautiful in quiet outdoor and out-of-town life, this beautifully - bound and attractively printed little volume will prove a companion and - friend."--_Rochester Union and Advertiser_. - - -_A NATURALIST'S RAMBLES ABOUT HOME._ By Charles C. Abbott. 12mo. Cloth, -$1.50. - - "The home about which Dr. Abbott rambles is clearly the haunt of fowl - and fish, of animal and insect life; and it is of the habits and nature - of these that he discourses pleasantly in this book. Summer and winter, - morning, and evening, he has been in the open air all the time on the - alert for some new revelation of instinct, or feeling, or character - on the part of his neighbor creatures. Most that he sees and hears he - reports agreeably to us, as it was no doubt delightful to himself. Books - like this, which are free from all the technicalities of science, but yet - lack little that has scientific value, are well suited to the reading of - the young. Their atmosphere is a healthy one for boys in particular to - breathe."--_Boston Transcript_. - - -_DAYS OUT OF DOORS._ By Charles C. Abbott. 12mo. Cloth, $1.50. - - "'Days out of Doors' is a series of sketches of animal life by Charles - C Abbott, a naturalist whose graceful writings have entertained and - instructed the public before now. The essays and narratives in this book - are grouped in twelve chapters, named after the months of the year. Under - 'January' the author talks of squirrels, muskrats, water-snakes, and the - predatory animals that withstand the rigor of winter; under 'February' - of frogs and herons, crows and blackbirds; under 'March' of gulls and - fishes and foxy sparrows; and so on appropriately, instructively, and - divertingly through the whole twelve."--_New York Sun_. - - -_THE PLAYTIME NATURALIST._ By Dr. J. E. Taylor, F. L. S., editor of -"Science Gossip." With 366 Illustrations. 12mo. Cloth, $1.50. - - "The work contains abundant evidence of the author's knowledge and - enthusiasm, and any boy who may read it carefully is sure to find - something to attract him. The style is clear and lively, and there are - many good illustrations."--_Nature_. - - -_THE ORIGIN OF FLORAL STRUCTURES_ through Insects and other Agencies. By -the Rev. George Henslow, Professor of Botany, Queen's College. With -numerous Illustrations. 12mo. Cloth, $1.75. - - "Much has been written on the structure of flowers, and it might seem - almost superfluous to attempt to say anything more on the subject, but it - is only within the last few years that a new literature has sprung up, - in which the authors have described their observations and given their - interpretations of the uses of floral mechanisms, more especially in - connection with the processes of fertilization."--_From Introduction_. - -New York: D. APPLETON & CO., 72 Fifth Avenue. - - - * * * * * - - -D. APPLETON & CO.'S PUBLICATIONS. - - -_THE GARDEN'S STORY;_ or, Pleasures and Trials of an Amateur Gardener. By -George H. Ellwanger. With Head and Tail Pieces by Rhead. 12mo. Cloth, -extra, $1.50. - - "Mr. Ellwanger's instinct rarely errs in matters of taste. He writes out - of the fullness of experimental knowledge, but his knowledge differs from - that of many a trained cultivator in that his skill in garden practice is - guided by a refined æsthetic sensibility, and his appreciation of what - is beautiful in nature is healthy, hearty, and catholic. His record of - the garden year, as we have said, begins with the earliest violet, and - it follows the season through until the witch-hazel is blossoming on the - border of the wintry woods.... This little book can not fail to give - pleasure 10 all who take a genuine interest in rural life."--_New York - Tribune_. - - -_THE ORIGIN OF CULTIVATED PLANTS._ By Alphonse de Candolle. 12mo. Cloth, -$2.00. - - "Though a fact familiar to botanists, it is not generally known hew - great is the uncertainty as to the origin of many of the most important - cultivated plants. ... In endeavoring to unravel the matter, a knowledge - of botany, of geography, of geology, of history, and of philosophy is - required. By a combination of testimony derived from these sources - M. de Candolle has been enabled to determine the botanical origin - aid geographical source of the large proportion of species he deals - with."--_The Athenæum_. - - -_THE FOLK-LORE OF PLANTS._ By T. F. Thiselton Dyer, M. A. 121110. Cloth, -$1.50. - - "A handsome and deeply interesting volume.... In all respects the book is - excellent. Its arrangement is simple and intelligible, its style bright - and alluring.... To all who seek an introduction to one of the most - attractive branches of folk-lore, this delightful volume may be warmly - commended."--_Notes and Queries_. - - -_FLOWERS AND THEIR PEDIGREES._ By Grant Allen, author of "Vignettes of -Nature," etc. Illustrated. 12mo. Cloth, $1.50. - - "No writer treats scientific subjects with so much ease and charm of - style as Mr. Grant Allen. The study is a delightful one, and the hook is - fascinating to any one who has either love for flowers or curiosity about - them."--_Hartford Courant_. - - "Any one with even a smattering of botanical knowledge, and with either a - heart or mind, must be charmed with this collection of essays."--_Chicago - Evening Journal_. - - -_THE GEOLOGICAL HISTORY OF PLANTS._ By Sir J. William Dawson, F. R. S. -Illustrated. 12mo. Cloth, $1.75. - - "The object of this work is to give, in a connected form, a summary of - the development of the vegetable kingdom in geological time. To the - geologist and botanist the subject is one of importance with reference to - their special pursuits, and one on which it has not been easy to find any - convenient manual of information. It is hoped that its treatment in the - present volume will also be found sufficiently simple and popular to be - attractive to the general reader."--_From the Preface_. - -New York: D. APPLETON & CO., 72 Fifth Avenue. - - - * * * * * - - -D. APPLETON & CO.'S PUBLICATIONS. - - -_IDLE DAYS IN PATAGONIA._ By W. H. Hudson, C. M. Z. S., author of "The -Naturalist in La Plata," etc. With 27 Illustrations. 8vo. Cloth, $4.00. - - "Of all modern books of travel it is certainly one of the most original, - and many, we are sure, will also find it one of the most interesting and - suggestive."--_New York Tribune_. - - "Mr. Hudson's remarks on color and expression of eyes in man and animals - are reserved for a second chapter, 'Concerning Eyes.' He is eloquent upon - the pleasures afforded by 'Bird Music in South America,' and relates - some romantic tales of white men in captivity to savages. But it makes - very little difference what is the topic when Mr. Hudson writes. He - calls up bright images of things unseen, and is a thoroughly agreeable - companion."--_Philadelphia Ledger_. - - -_THE NATURALIST IN LA PLATA._ By W. H. Hudson, C. M. Z. S., author of "Idle -Days in Patagonia," and joint author of "Argentine Ornithology." With 27 -Illustrations. 8vo. Cloth, $4.00. - - "Mr. Hudson is not only a clever naturalist, but he possesses the rare - gift of interesting his readers in whatever attracts him, and of being - dissatisfied with mere observation unless it enables him to philosophize - as well. With his lucid accounts of bird, beast, and insect, no one will - fail to be delighted."--_London Academy_. - - "A notably clear and interesting account of scientific observation and - research. Mr. Hudson has a keen eye for the phenomena with which the - naturalist is concerned, and a lucid and delightful way of writing - about them, so that any reader may be charmed by the narrative and the - reflections here set forth. It is easy to follow him, and we get our - information agreeably as he conducts us over the desert pampas, and makes - us acquainted with the results of his studies of animals, insects, and - birds."--_New York Sun_. - -_THE NATURALIST ON THE RIVER AMAZONS._ By Henry Walter Bates, F. R. S., -late Assistant Secretary of the Royal Geographical Society. With a Memoir -of the Author, by Edward Clodd. With Map and numerous Illustrations. 8vo. -Cloth, $5.00. - - "This famous work is a natural history classic."--_London Literary World_. - - "More than thirty years have passed since the first appearance of 'The - Naturalist on the River Amazons,' which Darwin unhesitatingly pronounced - the best book on natural history which ever appeared in England. The - work still retains its prime interest, and in rereading it one can not - but be impressed by the way in which the prophetic theories, disputed - and ridiculed at the time, have since been accepted. Such is the common - experience of those who keep a few paces in advance of their generation. - Bates was a 'born' naturalist."--_Philadelphia Ledger_. - - "No man was better prepared or gave himself up more thoroughly to - the task of studying an almost unknown fauna, or showed a zeal more - indefatigable in prosecuting his researches, than Bates. As a collector - alone his reputation would be second to none, but there is a great deal - more than sheer industry to be cited. The naturalist of the Amazons is, - par excellence, possessed of a happy literary style. He is always clear - and distinct. He tells of the wonders of tropical growth so that you can - understand them all."--_New York Times_. - -New York: D. APPLETON & CO., 72 Fifth Avenue. - - - * * * * * - - -D. APPLETON & CO.'S PUBLICATIONS. - - -WORKS BY ARABELLA B. BUCKLEY (MRS. FISHER). - - -_THE FAIRY-LAND OF SCIENCE._ With 74 Illustrations. 12mo. Cloth, gilt, -$1.50. "Deserves to take a permanent place in the literature of -youth."--_London Times_. - - "So interesting that, having once opened the book, we do not know how to - leave off reading. "--_Saturday Review_. - - -_THROUGH MAGIC GLASSES,_ and other Lectures. A Sequel to "The Fairy-Land of -Science." Illustrated. 12mo. Cloth, $1.50. - - _CONTENTS._ - - _The Magician's Chamber by Moonlight._ - _Magic Glasses and How to Use Them._ - _Fairy Rings and How They are Made._ - _The Life-History of Lichens and Mosses._ - _The History of a Lava-Stream._ - _An Hour with the Sun._ - _An Evening with the Stars._ - _Little Beings from a Miniature Ocean._ - _The Dartmoor Ponies._ - _The Magician's Dream of Ancient Days._ - -_LIFE AND HER CHILDREN:_ Glimpses of Animal Life from the Amoeba to the -Insects. With over 100 Illustrations. 121110. Cloth, gilt, $1.50. - - "The work forms a charming introduction to the study of zoology--the - science of living things--which, we trust, will find its way into many - hands."--_Nature_. - - -_WINNERS IN LIFE'S RACE;_ or, The Great Backboned Family. With numerous -Illustrations. 12mo. Cloth, gilt, $1.50. - - "We can conceive of no better gift-book than this volume. Miss Buckley - has spared no pains to incorporate in her book the latest results of - scientific research. The illustrations in the book deserve the highest - praise--they are numerous, accurate, and striking."--_Spectator_. - - -_SHORT HISTORY OF NATURAL SCIENCE;_ and of the Progress of Discovery from -the Time of the Greeks to the Present Time. New edition, revised and -rearranged. With 77 Illustrations. 12mo. Cloth, $2.00. - - "The work, though mainly intended for children and young persons, may be - most advantageously read by many persons of riper age, and may serve to - implant in their minds a fuller and clearer conception of 'the promises, - the achievements, and the claims of science.'"--_Journal of Science_. - - -_MORAL TEACHINGS OF SCIENCE._ 12mo. Cloth, 75 cents. - - "A little book that proves, with excellent clearness and force, how many - and striking are the moral lessons suggested by the study of the life - history of the plant or bird, beast or insect."--_London Saturday - Review_. - -New York: D. APPLETON & CO., 72 Fifth Avenue. - - - * * * * * - - -D. APPLETON & CO.'S PUBLICATIONS. - - -MODERN SCIENCE SERIES. - -Edited by Sir John Lubbock, Bart., F. R. S. - - -_THE CAUSE OF AN ICE AGE._ By Sir Robert Ball, LL. D., F. R. S., Royal -Astronomer of Ireland; author of "Star Land," "The Story of the Sun," etc. - - "Sir Robert Ball's book is, as a matter of course, admirably written. - Though but a small one, it is a most important contribution to - geology."--_London Saturday Review_. - - "A fascinating subject, cleverly related and almost colloquially - discussed."--_Philadelphia Public Ledger_. - - -_THE HORSE;_ A Study in Natural History. By William H. Flower, C. B., -Director in the British Natural History Museum. With 27 Illustrations. - - "The author admits that there are 3,800 separate treatises on the horse - already published, but he thinks that he can add something to the amount - of useful information now before the public, and that something not - heretofore written will be found in this book. The volume gives a large - amount of information, both scientific and practical, on the noble animal - of which it treats."--_New York Commercial Advertiser_. - - -_THE OAK:_ A Study in Botany. By H. Marshall Ward, F. R. S. With 53 -Illustrations. - - "From the acorn to the timber which has figured so gloriously in English - ships and houses, the tree is fully described, and all its living and - preserved beauties and virtues, in nature and in construction, are - recounted and pictured."--_Brooklyn Eagle_. - - -_ETHNOLOGY IN FOLK LORE._ By George L. Gomme, F. S. A., President of the -Folklore Society, etc. - - "The author puts forward no extravagant assumptions, and the method - he points out for the comparative study of folk-lore seems to - promise a considerable extension of knowledge as to prehistoric - times."--_Independent_. - - -_THE LAWS AND PROPERTIES OF MATTER._ By R. T. Glazebrook, F. R. S., Fellow -of Trinity College, Cambridge. - - "It is astonishing how interesting such a took can be made when the - author has a perfect mastery of his subject, as Mr. Glazebrook has. - One knows nothing of the world in which he lives until he has obtained - some insight of the properties of matter as explained in this excellent - work."--_Chicago Herald_. - - -_THE FAUNA OF THE DEEP SEA._ By Sydney J. J. Hickson, M. A., Fellow of -Downing College, Cambridge. With 23 Illustrations. - - "That realm of mystery and wonders at the bottom of the great waters is - gradually being mapped and explored and studied until its secrets seem no - longer secrets. . . . This excellent book has a score of illustrations - and a careful index to add to its value, and in every way is to be - commended for its interest and its scientific merit."--_Chicago Times_. - -Each, 12mo, cloth, $1.00. - -New York: D. APPLETON & CO., 72 Fifth Avenue. - - - * * * * * - - -Transcriber Note - -Figure captions were standardized. All figures were moved to avoid -splitting paragraphs. Any minor typos were corrected. - - - - - - - - -End of Project Gutenberg's Man and the Glacial Period, by G. Frederick Wright - -*** END OF THIS PROJECT GUTENBERG EBOOK MAN AND THE GLACIAL PERIOD *** - -***** This file should be named 50957-8.txt or 50957-8.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/0/9/5/50957/ - -Produced by Tom Cosmas from materials provided at The Internet Archive. -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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APPLETON & CO., 72 Filth Avenue.</p> - -<hr class="full" /> - -<div class="fig_center" style="width: 505px;"> -<a id="map_brit_glac" name="map_brit_glac"></a> -<a href="images/brit_glac_map_lg.png"> -<img src="images/brit_glac_map_sm.png" width="505" height="620" alt="CONTOUR AND GLACIAL MAP OF THE BRITISH ISLES" /></a> -<p class="smaller center">Click on map to view larger version.</p> -</div> - -<p class="pmt2"><span class="pagenum"><a name="Page_i" id="Page_i"></a> -<a name="Page_ii" id="Page_ii"></a> -<a name="Page_iii" id="Page_iii"></a></span></p> - - - - -<p class="center pmt4">THE INTERNATIONAL SCIENTIFIC SERIES</p> - -<hr class="r20" /> - - -<p id="title" class="title">MAN AND<br /> -THE GLACIAL PERIOD</p> - - -<p class="center pmt2">BY</p> - -<p id="author" class="author">G. FREDERICK WRIGHT</p> - -<p class="center">D. D., LL. D., F. G. S. A.</p> - - -<p class="center smaller"> -PROFESSOR IN OBERLIN THEOLOGICAL SEMINARY<br /> -<br /> -FORMERLY ASSISTANT ON THE UNITED STATES GEOLOGICAL SURVEY<br /> -<br /> -AUTHOR OF THE ICE AGE IN NORTH AMERICA.<br /> -<br /> -LOGIC OF CHRISTIAN EVIDENCES, ETC.<br /> -</p> - - -<p class="center pmt2"><i>WITH AN APPENDIX ON TERTIARY MAN</i></p> - -<p class="caption3"><span class="smcap">By PROF. HENRY W. HAYNES</span></p> - - -<p class="center pmt2">FULLY ILLUSTRATED</p> - - -<p class="center"><i>SECOND EDITION</i></p> - - -<p class="caption3nb pmt2">NEW YORK<br /> -D. APPLETON AND COMPANY<br /> -1895</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_iv" id="Page_iv"></a></span></p> - - -<p class="center smaller pmt4"><span class="smcap">Copyright, 1892,</span></p> - -<p class="center"><span class="smcap">By D. APPLETON AND COMPANY.</span></p> - - - -<p class="center pmt2 pmb4"><span class="smcap">Electrotyped and Printed<br /> -at the Appleton Press, U. S. A.</span><br /> -</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_v" id="Page_v"></a></span></p> - - -<p class="center pmt2">TO</p> - -<p class="caption3nb">JUDGE C. C. BALDWIN</p> - -<p class="center pmb2">PRESIDENT OF THE WESTERN RESERVE HISTORICAL SOCIETY<br /> -CLEVELAND<br /> -THIS VOLUME IS DEDICATED<br /> -IN RECOGNITION OF<br /> -HIS SAGACIOUS AND UNFAILING INTEREST IN<br /> -THE INVESTIGATIONS WHICH HAVE MADE IT POSSIBLE</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_vi" id="Page_vi"></a> -<a name="Page_vii" id="Page_vii"></a></span></p> - - - - -<p class="caption2"><a name="PREFACE_TO_THE_SECOND_EDITION" id="PREFACE_TO_THE_SECOND_EDITION">PREFACE TO THE SECOND EDITION.</a></p> - - -<p><span class="smcap">Since</span>, as stated in the Introduction (<a href="#Page_1">page 1</a>), the -plan of this volume permitted only “a concise presentation -of the facts,” it was impossible to introduce either -full references to the illimitable literature of the subject -or detailed discussion of all disputed points. The facts -selected, therefore, were for the most part those upon -which it was supposed there would be pretty general -agreement.</p> - -<p>The discussion upon the subject of the continuity of -the Glacial period was, however, somewhat elaborate (see -pages <a href="#Page_106">106-121</a>, <a href="#Page_311">311</a>, <a href="#Page_324">324</a>, <a href="#Page_332">332</a>), and was presented with -excessive respect for the authority of those who maintain -the opposite view; all that was claimed (<a href="#Page_110">page 110</a>) being -that one might maintain the <i>unity</i> or <i>continuity</i> of the -Glacial period “without forfeiting his right to the respect -of his fellow-geologists.” But it already appears that -there was no need of this extreme modesty of statement. -On the contrary, the vigorous discussion of the subject -which has characterized the last two years reveals a decided -reaction against the theory that there has been more -than one Glacial epoch in Quaternary times; while there -have been brought to light many most important if not -conclusive facts in favour of the theory supported in the -volume.</p> - -<p>In America the continuity of the Glacial period has -been maintained during the past two years with important -<span class="pagenum"><a name="Page_viii" id="Page_viii">« viii »</a></span> -new evidence, among others by authorities of no less -eminence and special experience in glacial investigations -than Professor Dana,<a name="FNanchor_1" id="FNanchor_1"></a><a href="#Footnote_1" class="fnanchor">[A]</a> Mr. Warren Upham,<a name="FNanchor_2" id="FNanchor_2"></a><a href="#Footnote_2" class="fnanchor">[B]</a> and Professor -Edward H. Williams, Jr.<a name="FNanchor_3" id="FNanchor_3"></a><a href="#Footnote_3" class="fnanchor">[C]</a> Professor Williams’s investigations -on the attenuated border of the glacial deposits -in the Lehigh, the most important upper tributary to the -Delaware Valley, Pa., are of important significance, since -the area which he so carefully studied lies wholly south of -the terminal moraine of Lewis and Wright, and belongs -to the portion of the older drift which Professors Chamberlin -and Salisbury have been most positive in assigning -to the first Glacial epoch, which they have maintained -was separated from the second epoch by a length -of time sufficient for the streams to erode rock gorges in -the Delaware and Lehigh Rivers from two hundred to -three hundred feet in depth.<a name="FNanchor_4" id="FNanchor_4"></a><a href="#Footnote_4" class="fnanchor">[D]</a> But Professor Williams has -found that the rock gorges of the Lehigh, and even of its -southern tributaries, had been worn down approximately -to the present depth of that of the Delaware before this -earliest period of glaciation, and that the gorges were -filled with the earliest glacial <i>débris</i>.</p> - -<div class="footnote"> - -<p><a name="Footnote_1" id="Footnote_1"></a><a href="#FNanchor_1"><span class="label">[A]</span></a> American Journal of Science, vol. xlvi, pp. 327, 330.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_2" id="Footnote_2"></a><a href="#FNanchor_2"><span class="label">[B]</span></a> American Journal of Science, vols, xlvi, pp. 114-121; xlvii, pp. -358-365; American Geologist, vols, x, pp. 339-362, especially pp. -361, 362; xiii, pp. 114, 278; Bulletin of the Geological Society of -America, vol. v, pp. 71-86, 87-100.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_3" id="Footnote_3"></a><a href="#FNanchor_3"><span class="label">[C]</span></a> Bulletin of the Geological Society of America, vol. v, pp. -13-16, 281-296; American Journal of Science, vol. xlvii, pp. 33-36.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_4" id="Footnote_4"></a><a href="#FNanchor_4"><span class="label">[D]</span></a> See especially Chamberlin, in the American Journal of Science, -vol. xlv, p. 192; Salisbury, in the American Geologist, vol. xi, -p. 18.</p></div> - -<p>A similar relation of the glacial deposits of the attenuated -border to the preglacial erosion of the rock gorges -of the Alleghany and upper Ohio Rivers has been brought -to light by the joint investigations of Mr. Frank Leverett -and myself in western Pennsylvania, in the vicinity of -<span class="pagenum"><a name="Page_ix" id="Page_ix">« ix »</a></span> -Warren, Pa., where, in an area which was affected by only -the earliest glaciation, glacial deposits are found filling -the rock channels of old tributaries to the Alleghany to a -depth of from one hundred and seventy to two hundred -and fifty feet, and carrying the preglacial erosion at that -point very closely, if not quite, down to the present rock -bottoms of all the streams. This removes from Professor -Chamberlin a most important part of the evidence of a -long interglacial period to which he had appealed; he -having maintained<a name="FNanchor_5" id="FNanchor_5"></a><a href="#Footnote_5" class="fnanchor">[E]</a> that “the higher glacial gravels -antedated those of the moraine-forming epoch by the -measure of the erosion of the channel through the old -drift and the rock, whose mean depth here is about three -hundred feet, of which perhaps two hundred and fifty -feet may be said to be rock,” adding that the “excavation -that intervened between the two epochs in other -portions of the Alleghany, Monongahela, and upper Ohio -valleys is closely comparable with this.”</p> - -<div class="footnote"> - -<p><a name="Footnote_5" id="Footnote_5"></a><a href="#FNanchor_5"><span class="label">[E]</span></a> Bulletin 58 of the United States Geological Survey, p. 35; -American Journal of Science, vol. xlv, p. 195.</p></div> - -<p>These observations of Mr. Leverett and myself seem -to demonstrate the position maintained in the volume -(<a href="#Page_218">page 218</a>), namely, that the inner precipitous rock -gorges of the upper Ohio and its tributaries are mainly -<i>pre</i>glacial, rather than <i>inter</i>glacial. The only way in -which Professor Chamberlin can in any degree break the -force of this discovery is by assuming that in preglacial -times the present narrow rock gorges of the Alleghany -and the Ohio were not continuous, but that (as indicated -in the present volume on <a href="#Page_206">page 206</a>) the drainage of various -portions of that region was by northern outlets to the -Lake Erie basin, leaving, on this supposition, the <i>cols</i> -between two or three drainage areas to be lowered in glacial -or interglacial time.</p> - -<p>On the theory of continuity the erosion of these -<span class="pagenum"><a name="Page_x" id="Page_x">« x »</a></span> <i>cols</i> -would have been rapidly effected by the reversed drainage -consequent upon the arrival of the ice-front at the southern -shore of the Lake Erie basin. During all the time elapsing -thereafter, until the ice had reached its southern limit, the -stream was also augmented by the annual partial melting -of the advancing glacier which was constantly bringing -into the valley the frozen precipitation of the far north. -The distance is from thirty to seventy miles, so that a -moderately slow advance of the ice at that stage would -afford time for a great amount of erosion before sufficient -northern gravel had reached the region to begin the filling -of the gorge.<a name="FNanchor_6" id="FNanchor_6"></a><a href="#Footnote_6" class="fnanchor">[F]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_6" id="Footnote_6"></a><a href="#FNanchor_6"><span class="label">[F]</span></a> See an elaborate discussion of the subject in its new phases by -Chamberlin and Leverett, in the American Journal of Science, vol. -xlvii, pp. 247-283.</p></div> - -<p>Mr. Leverett also presented an important paper before -the Geological Society of America at its meeting at Madison, -Wis., in August, 1893, adducing evidence which, he -thinks, goes to prove that the post-glacial erosion in the -earlier drift in the region of Rock River, Ill., was seven or -eight times as much as that in the later drift farther -north; while Mr. Oscar H. Hershey arrives at nearly the -same conclusions from a study of the buried channels in -northwestern Illinois.<a name="FNanchor_7" id="FNanchor_7"></a><a href="#Footnote_7" class="fnanchor">[G]</a> But even if these estimates are -approximately correct—which is by no means certain—they -only prove the length of the Glacial period, and not -necessarily its discontinuity.</p> - -<div class="footnote"> - -<p><a name="Footnote_7" id="Footnote_7"></a><a href="#FNanchor_7"><span class="label">[G]</span></a> American Geologist, vol. xii, p. 314f. Other important evidence -to a similar effect is given by Mr. Leverett, in an article on -The Glacial Succession in Ohio, Journal of Geology, vol. i, pp. 129-146.</p></div> - -<p>At the same time it should be said that these investigations -in western Pennsylvania somewhat modify a portion -of the discussion in the present volume concerning -the effects of the Cincinnati ice-dam. It now appears that -the full extent of the gravel terraces of glacial origin in -<span class="pagenum"><a name="Page_xi" id="Page_xi">« xi »</a></span> -the Alleghany River had not before been fully appreciated, -since they are nearly continuous on the two-hundred-foot -rock shelf, and are often as much as eighty feet thick. It -seems probable, therefore, that the Alleghany and upper -Ohio gorge was filled with glacial gravel to a depth of -about two hundred and fifty or three hundred feet, as far -down at least as Wheeling, W. Va. If this was the case, it -would obviate the necessity of bringing in the Cincinnati -ice-dam (as set forth in <a href="#Page_212">pages 212-216</a>) to account directly -for all the phenomena in that region, except as this obstruction -at Cincinnati would greatly facilitate the silting -up of the gorge. The simple accumulation of glacial -gravel in the Alleghany gorge would of itself dam up the -Monongahela at Pittsburg, so as to produce the results -detailed by Professor White on <a href="#Page_215">page 215</a>.<a name="FNanchor_8" id="FNanchor_8"></a><a href="#Footnote_8" class="fnanchor">[H]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_8" id="Footnote_8"></a><a href="#FNanchor_8"><span class="label">[H]</span></a> For a full discussion of these topics, see paper by Professor -B. C. Jillson, Transactions of the Academy of Science and Art of -Pittsburg, December 8, 1893; G. F. Wright, American Journal of -Science, vol. xlvii, pp. 161-187; especially pp. 177, 178; The Popular -Science Monthly, vol. xlv, pp. 184-198.</p></div> - -<p>Of European authorities who have recently favoured the -theory of the continuity of the Quaternary Glacial period, -as maintained in the volume, it is enough to mention the -names of Prestwich,<a name="FNanchor_9" id="FNanchor_9"></a><a href="#Footnote_9" class="fnanchor">[I]</a> Hughes,<a name="FNanchor_10" id="FNanchor_10"></a><a href="#Footnote_10" class="fnanchor">[J]</a> Kendall,<a name="FNanchor_11" id="FNanchor_11"></a><a href="#Footnote_11" class="fnanchor">[K]</a> Lamplugh,<a name="FNanchor_12" id="FNanchor_12"></a><a href="#Footnote_12" class="fnanchor">[L]</a> -and Wallace,<a name="FNanchor_13" id="FNanchor_13"></a><a href="#Footnote_13" class="fnanchor">[M]</a> of England; Falsan,<a name="FNanchor_14" id="FNanchor_14"></a><a href="#Footnote_14" class="fnanchor">[N]</a> of France; Holst,<a name="FNanchor_15" id="FNanchor_15"></a><a href="#Footnote_15" class="fnanchor">[O]</a> -of Sweden; Credner<a name="FNanchor_16" id="FNanchor_16"></a><a href="#Footnote_16" class="fnanchor">[P]</a> and Diener,<a name="FNanchor_17" id="FNanchor_17"></a><a href="#Footnote_17" class="fnanchor">[Q]</a> of Germany; and -Nikitin<a name="FNanchor_18" id="FNanchor_18"></a><a href="#Footnote_18" class="fnanchor">[R]</a> and Kropotkin,<a name="FNanchor_19" id="FNanchor_19"></a><a href="#Footnote_19" class="fnanchor">[S]</a> of Russia.<a name="FNanchor_20" id="FNanchor_20"></a><a href="#Footnote_20" class="fnanchor">[T]</a> Among leading -authorities still favouring a succession of Glacial epochs -are: Professor James Geikie,<a name="FNanchor_21" id="FNanchor_21"></a><a href="#Footnote_21" class="fnanchor">[U]</a> of Scotland; Baron de -Geer,<a name="FNanchor_22" id="FNanchor_22"></a><a href="#Footnote_22" class="fnanchor">[V]</a> of Sweden; and Professor Felix Wahnschaffe,<a name="FNanchor_23" id="FNanchor_23"></a><a href="#Footnote_23" class="fnanchor">[W]</a> -of Germany.</p> - -<div class="footnote"> - -<p><a name="Footnote_9" id="Footnote_9"></a><a href="#FNanchor_9"><span class="label">[I]</span></a> Quarterly Journal of the Geological Society for August, 1887.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_10" id="Footnote_10"></a><a href="#FNanchor_10"><span class="label">[J]</span></a> American Geologist, vol. viii, p. 241.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_11" id="Footnote_11"></a><a href="#FNanchor_11"><span class="label">[K]</span></a> Transactions of the Leeds Geological Association for February -10, 1893.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_12" id="Footnote_12"></a><a href="#FNanchor_12"><span class="label">[L]</span></a> Quarterly Journal of the Geological Society, August, 1891.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_13" id="Footnote_13"></a><a href="#FNanchor_13"><span class="label">[M]</span></a> Fortnightly Review, November, 1893, p. 633; reprinted in The -Popular Science Monthly, vol. xliv, p. 790.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_14" id="Footnote_14"></a><a href="#FNanchor_14"><span class="label">[N]</span></a> La Période glaciaire (Félix Alcan. Paris, 1889).</p></div> - -<div class="footnote"> - -<p><a name="Footnote_15" id="Footnote_15"></a><a href="#FNanchor_15"><span class="label">[O]</span></a> American Geologist, vol. viii, p. 242.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_16" id="Footnote_16"></a><a href="#FNanchor_16"><span class="label">[P]</span></a> Ibid., p. 241.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_17" id="Footnote_17"></a><a href="#FNanchor_17"><span class="label">[Q]</span></a> Ibid., p. 242.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_18" id="Footnote_18"></a><a href="#FNanchor_18"><span class="label">[R]</span></a> Congrès International d’Archéologie, Moscow, 1892.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_19" id="Footnote_19"></a><a href="#FNanchor_19"><span class="label">[S]</span></a> Nineteenth Century, January, 1894, p. 151, note.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_20" id="Footnote_20"></a><a href="#FNanchor_20"><span class="label">[T]</span></a> The volume The Glacial Geology of Great Britain and Ireland, -edited from the unpublished MSS. of the late Henry Carvill Lewis -(London, Longmans, Green & Co., 1894), adds much important evidence -in favour of the continuity of the Glacial epoch; see especially -pp. 187, 460, 461, 466.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_21" id="Footnote_21"></a><a href="#FNanchor_21"><span class="label">[U]</span></a> Transactions of the Royal Society of Edinburgh, vol. xxxvii, -Part I, pp. 127-150.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_22" id="Footnote_22"></a><a href="#FNanchor_22"><span class="label">[V]</span></a> American Geologist, vol. viii, p. 246.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_23" id="Footnote_23"></a><a href="#FNanchor_23"><span class="label">[W]</span></a> Forschungen zur deutschen Landes und Volkskunde von Dr. -A. Kirchhoff. Bd. vi, Heft i.</p> - -<p><span class="pagenum"><a name="Page_xii" id="Page_xii">« xii »</a></span></p></div> - -<p>When the first edition was issued, two years ago, there -seemed to be a general acceptance of all the facts detailed -in it which directly connected man with the Glacial period -both in America and in Europe; and, indeed, I had studiously -limited myself to such facts as had been so long -and so fully before the public that there would seem to be -no necessity for going again into the details of evidence -relating to them. It appears, however, that this confidence -was ill-founded; for the publication of the book -seems to have been the signal for a confident challenge, -by Mr. W. H. Holmes, of all the American evidence, with -intimations that the European also was very likely equally -defective.<a name="FNanchor_24" id="FNanchor_24"></a><a href="#Footnote_24" class="fnanchor">[X]</a> In particular Mr. Holmes denies the conclusiveness -of the evidence of glacial man adduced by Dr. -Abbott and others at Trenton, N. J.; Dr. Metz, at Madisonville, -Ohio; Mr. Mills, at Newcomerstown, Ohio; and -Miss Babbitt, at Little Falls, Minn.</p> - -<div class="footnote"> - -<p><a name="Footnote_24" id="Footnote_24"></a><a href="#FNanchor_24"><span class="label">[X]</span></a> Journal of Geology, vol. i, pp. 15-37, 147-163; American Geologist, -vol. xi, pp. 219-240.</p></div> - -<p>The sum of Mr. Holmes’s effort amounts, however, to -<span class="pagenum"><a name="Page_xiii" id="Page_xiii">« xiii »</a></span> -little more than the statement that, with a limited amount -of time and labour, neither he nor his assistants had been -able to find any implements in undisturbed gravel in any -of these places; and the suggestion of various ways in -which he thinks it possible that the observers mentioned -may have been deceived as to the original position of the -implements found. But, as had been amply and repeatedly -published,<a name="FNanchor_25" id="FNanchor_25"></a><a href="#Footnote_25" class="fnanchor">[Y]</a> Professor J. D. Whitney, Professor Lucien -Carr, Professor N. S. Shaler, Professor F. W. Putnam, of -Harvard University, besides Dr. C. C. Abbott, all expressly -and with minute detail describe finding implements in the -undisturbed gravel at Trenton, which no one denies to be -of glacial origin. In the face of such testimony, which -had been before the public and freely discussed for several -years, it is an arduous undertaking for Mr. Holmes to -claim that none of the implements have been found in -place, because he and his assistants (whose opportunities for -observation had scarcely been one twentieth part as great as -those of the others) failed to find any. To see how carefully -the original observations were made, one has but to -read the reports to Professor Putnam which have from -time to time appeared in the Proceedings of the Peabody -Museum and of the Boston Society of Natural History,, -and which are partially summed up in the thirty-second -chapter of Dr. Abbott’s volume on Primitive Industry.</p> - -<div class="footnote"> - -<p><a name="Footnote_25" id="Footnote_25"></a><a href="#FNanchor_25"><span class="label">[Y]</span></a> Proceedings of the Boston Society of Natural History, vol. xxi, -January 19, 1881; Report of the Peabody Museum, vol. ii, pp. 44-47; -chap, xxxii of Abbott’s Primitive Industry; American Geologist, -vol. xi, pp. 180-184.</p></div> - -<p>In the case of the discovery at Newcomerstown, Mr. -Holmes is peculiarly unfortunate in his efforts to present -the facts, since, in endeavouring to represent the conditions -under which the implement was found by Mr. Mills, he -has relied upon an imaginary drawing of his own, in which -an utterly impossible state of things is pictured. The -claim of Mr. Holmes in this case, as in the other, is that -<span class="pagenum"><a name="Page_xiv" id="Page_xiv">« xiv »</a></span> -possibly the gravel in which the implements were found -had been disturbed. In some cases, as in Little Falls -and at Madison ville, he thinks the implements may have -worked down to a depth of several feet by the overturning -of trees or by the decay of the tap-root of trees. A sufficient -answer to these suggestions is, that Mr. Holmes is -able to find no instance in which the overturning of trees -has disturbed the soil to a depth of more than three or -four feet, while some of the implements in these places -had been found buried from eight to sixteen feet. Even -if, as Mr. Chamberlin suggests,<a name="FNanchor_26" id="FNanchor_26"></a><a href="#Footnote_26" class="fnanchor">[Z]</a> fifty generations of trees -have decayed on the spot since the retreat of the ice, it is -difficult to see how that would help the matter, since the -effect could not be cumulative, and fifty upturnings of -three or four feet would not produce the results of one upturning -of eight feet. Moreover, at Trenton, where the -upturning of trees and the decaying of tap-roots would -have been as likely as anywhere to bury implements, -none of those of flint or jasper (which occur upon the surface -by tens of thousands) are buried more than a foot in -depth; while the argillite implements occur as low down -as fifteen or twenty feet. This limitation of flint and jasper -implements to the surface is conclusively shown not -only by Dr. Abbott’s discoveries, but also by the extensive -excavations at Trenton of Mr. Ernest Volk, whose collections -formed so prominent a part of Professor Putnam’s -Palæolithic exhibit at the Columbian Exposition at Chicago. -In the village sites explored by Mr. Volk, argillite -was the exclusive material of the implements found in the -lower strata of gravel. Similar results are indicated by -the excavations of Mr. H. C. Mercer at Point Pleasant, -Pa., about twenty miles above Trenton, where, in the -lower strata, the argillite specimens are sixty-one times -more numerous than the jasper are.</p> - -<div class="footnote"> - -<p><a name="Footnote_26" id="Footnote_26"></a><a href="#FNanchor_26"><span class="label">[Z]</span></a> American Geologist, vol. xi, p. 188.</p> - -<p><span class="pagenum"><a name="Page_xv" id="Page_xv">« xv »</a></span></p></div> - -<p>To discredit the discoveries at Trenton and Newcomerstown, -Mr. Holmes relies largely upon the theory -that portions of gravel from the surface had slid down to -the bottom of the terrace, carrying implements with them, -and forming a talus, which, he thinks, Mr. Mills, Dr. Abbott, -and the others have mistaken for undisturbed strata -of gravel. In his drawings Mr. Holmes has even represented -the gravel at Newcomerstown as caving down into -a talus without disturbing the strata to any great extent, -and at the same time he speaks slightingly of the promise -which I had made to publish a photograph of the bank as -it really was. In answer, it is sufficient to give, first, the -drawing made at the time by Mr. Mills, to show the general -situation of the gravel bank at Newcomerstown, in -which the implement figured on <a href="#Page_252">page 252</a> was found; and, -secondly, an engraving from a photograph of the bank, -taken by Mr. Mills after the discovery of the implement, -but before the talus had obscured its face. The implement -was found by Mr. Mills with its point projecting -from a fresh exposure of the terrace, just after a mass, -loosened by his own efforts, had fallen away. The gravel is -of such consistency that every sign of stratification disappears -when it falls down, and there could be no occasion -for a mistake even by an ordinary observer, while Mr. -Mills was a well-trained geologist and collector, making -his notes upon the spot.<a name="FNanchor_27" id="FNanchor_27"></a><a href="#Footnote_27" class="fnanchor">[AA]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_27" id="Footnote_27"></a><a href="#FNanchor_27"><span class="label">[AA]</span></a> The Popular Science Monthly, vol. xliii, pp. 29-39.</p></div> - -<div class="fig_center" style="width: 477px;"> -<img src="images/pg_xvi.png" width="477" height="297" alt="" /> -<div class="fig_caption">Height of Terrace exposed, 25 feet. Palæolith was found 14<span class="horsplit"><span class="top">3</span><span class="bottom trt">4</span></span> feet from surface.</div> -</div> - -<div class="fig_center" style="width: 511px;"> -<img src="images/pg_xvii.png" width="511" height="402" alt="" /> -<div class="fig_caption">Terrace in Newcomerstown, showing where W. C. Mills found the Palæolithic implement.</div> -</div> - -<p>I had thought at first that Mr. Holmes had made out -a better case against the late Miss Babbitt’s discoveries at -Little Falls (referred to on <a href="#Page_254">page 254</a>), but in the American -Geologist for May, 1894, page 363, Mr. Warren Upham, -after going over the evidence, expresses it as still his conviction -that Mr. Holmes’s criticism fails to shake the force -of the original evidence, so that I do not see any reason for -modifying any of the statements made in the body of the -<span class="pagenum"><a name="Page_xvi" id="Page_xvi">« xvi »</a></span> -book concerning the implements supposed to have been -found in glacial deposits. Yet if I had expected such an -avalanche of criticism of the evidence as has been loosened, -I should at the time have fortified my statements by fuller -references, and should possibly have somewhat enlarged -the discussion. But this seemed then the less necessary, -from the fact that Mr. McGee had, in most emphatic -manner, indorsed nearly every item of the evidence adduced -<span class="pagenum"><a name="Page_xvii" id="Page_xvii">« xvii »</a></span> -by me, and much more, in an article which appeared -in The Popular Science Monthly four years before the publication -of the volume (November, 1888). In this article -he had said:</p> - -<p>“But it is in the aqueo-glacial gravels of the Delaware -River at Trenton, which were laid down contemporaneously -<span class="pagenum"><a name="Page_xviii" id="Page_xviii">« xviii »</a></span> -with the terminal moraine one hundred miles farther -northward, and which have been so thoroughly studied by -Abbott, that the most conclusive proof of the existence of -glacial man is found" (<a href="#Page_23">p. 23</a>). “Excluding all doubtful -cases, there remains a fairly consistent body of testimony -indicating the existence of a widely distributed human -population upon the North. American continent during -the later Ice epoch” (<a href="#Page_24">p. 24</a>). “However the doubtful -cases may be neglected, the testimony is cumulative, parts -of it are unimpeachable, and the proof of the existence of -glacial man seems conclusive” (<a href="#Page_25">p. 25</a>).</p> - -<p>In view of the grossly erroneous statements made by Mr. -McGee concerning the Nampa image (described on <a href="#Page_298">pages -298, 299</a>), it is necessary for me to speak somewhat more -fully of this important discovery. The details concerning -the evidence were drawn out by me at length in two -communications to the Boston Society of Natural History -(referred to on <a href="#Page_297">page 297</a>), which fill more than thirty pages -of closely printed matter, while two or three years before -the appearance of the volume the facts had been widely -published in the New York Independent, the Scientific -American, The Nation, Scribner’s Magazine, and the Atlantic -Monthly, and in Washington at a meeting of the -Geological Society of America in 1890. In the second -communication to the Boston Society of Natural History -an account was given of a personal visit to the Snake River -Valley, largely for the purpose of further investigation of -the evidence brought to my notice by Mr. Charles Francis -Adams, and of the conditions under which the figurine -was found. Among the most important results of this investigation -was the discovery of numerous shells under the -lava deposits, which Mr. Dall, of the United States Geological -Survey, identified for me as either post-Tertiary or -late Pliocene; thus throwing the superficial lava deposits of -the region into the Quaternary period, and removing from -the evidence the antecedent improbability which would -<span class="pagenum"><a name="Page_xix" id="Page_xix">« xix »</a></span> -bear so heavily against it if we were compelled to suppose -that the lava of the Snake River region was all of Tertiary -or even of early Quaternary age. Furthermore, the evidence -of the occurrence of a great <i>débâcle</i> in the Snake -River Valley during the Glacial period, incident upon the -bursting of the banks of Lake Bonneville, goes far to remove -antecedent presumptions against the occurrence of -human implements in such conditions as those existing at -Nampa (see below, <a href="#Page_233">pp. 233-237</a>).</p> - -<p>Mr. McGee’s misunderstanding of the evidence on one -point is so gross, that I must make special reference to it. -He says<a name="FNanchor_28" id="FNanchor_28"></a><a href="#Footnote_28" class="fnanchor">[AB]</a> that this image “is alleged to have been pounded -out of volcanic tuff by a heavy drill, ... under a thick -Tertiary lava bed.” The statement of facts on <a href="#Page_298">page 298</a> -bears no resemblance to this representation. It is there -stated that there were but fifteen feet of lava, and that -near the surface; that below this there was nothing but -alternating beds of clay and quicksand, and that the lava -is post-Tertiary. The sand-pump I should perhaps have -described more fully in the book, as I had already done in -the communication to the Boston Society of Natural History. -It was a tube eight feet long, with a valve at the -bottom three and a half inches in diameter on the inside. -Through this it was the easiest thing in the world for the -object, which is only one inch and a half long, to be -brought up in the quicksand without injury.</p> - -<div class="footnote"> - -<p><a name="Footnote_28" id="Footnote_28"></a><a href="#FNanchor_28"><span class="label">[AB]</span></a> Literary Northwest, vol. ii, p. 275.</p></div> - -<p>The baseless assertions of Mr. McGee, involving the -honesty of Messrs. Kurtz and Duffes, are even less fortunate -and far more reprehensible. “It is a fact,” says Mr. -McGee, “hat one of the best-known geologists of the -world chanced to visit Nampa while the boring was in -progress, and the figurine and the pretty fiction were laid -before him. He recognized the figurine as a toy such as -the neighbouring Indians give their children, and laughed -<span class="pagenum"><a name="Page_xx" id="Page_xx">« xx »</a></span> -at the story; whereupon the owner of the object enjoined -secrecy, pleading: ‘Don’t give me away; I’ve fooled a lot -of fellows already, and I’d like to fool some more.’”<a name="FNanchor_29" id="FNanchor_29"></a><a href="#Footnote_29" class="fnanchor">[AC]</a> -This well-known geologist, on being challenged by Professor -Claypole<a name="FNanchor_30" id="FNanchor_30"></a><a href="#Footnote_30" class="fnanchor">[AD]</a> to give “a full, exact, and certified statement -of the conversation” above referred to, proved to be Major -Powell, who responded with the following statement: “In -the fall of 1889 the writer visited Boise City, in Idaho -[twenty miles from Nampa]. While stopping at a hotel, -some gentlemen called on him to show him a figurine -which they said they had found in sinking an artesian -well in the neighbourhood, at a depth, if I remember -rightly, of more than three hundred feet.... When this -story was told the writer, he simply jested with those who -claimed to have found it. He had known the Indians -that live in the neighbourhood, had seen their children play -with just such figurines, and had no doubt that the little -image had lately belonged to some Indian child, and said -the same. While stopping at the hotel different persons -spoke about it, and it was always passed off as a jest; and -various comments were made about it by various people, -some of them claiming that it had given them much -sport, and that a good many tenderfeet had looked at it, -and believed it to be genuine; and they seemed rather -pleased that I had detected the hoax.”<a name="FNanchor_31" id="FNanchor_31"></a><a href="#Footnote_31" class="fnanchor">[AE]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_29" id="Footnote_29"></a><a href="#FNanchor_29"><span class="label">[AC]</span></a> American Anthropologist, vol. vi, p. 94: repeated by Mr. McGee -in the Literary Northwest, vol. ii, p. 276.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_30" id="Footnote_30"></a><a href="#FNanchor_30"><span class="label">[AD]</span></a> The Popular Science Monthly, vol. xlii, p. 773.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_31" id="Footnote_31"></a><a href="#FNanchor_31"><span class="label">[AE]</span></a> Ibid., vol. xliii, pp. 322, 323.</p></div> - -<p>Thus it appears that Major Powell has made no such -statement, at least in public, as Mr. McGee attributes to -him. It should be said, also, that Major Powell’s memory -is very much at fault when he affirms that there is a close -resemblance between this figurine and some of the children’s -playthings among the Pocatello Indians. On the -<span class="pagenum"><a name="Page_xxi" id="Page_xxi">« xxi »</a></span> -contrary, it would have been even more of a surprise to -find it in the hands of these children than to find it among -the prehistoric deposits on the Pacific coast.</p> - -<p>To most well-informed people it is sufficient to know -that no less high authorities than Mr. Charles Francis -Adams and Mr. G. M. Gumming, General Manager for -the Union Pacific line for that district, carefully investigated -the evidence at the time of the discovery, and, -knowing the parties, were entirely satisfied with its sufficiency. -It was also subjected to careful examination by -Professor F. W. Putnam, who discerned, in a deposit of an -oxide of iron on various parts of the image, indubitable -evidence that it was a relic which had lain for a long time -in some such condition as was assigned to it in the bottom -of the well—all of which is detailed in the papers referred -to below, on <a href="#Page_297">page 297</a>.</p> - -<p>Finally, the discovery, both in its character and conditions, -is in so many respects analogous to those made -under Table Mountain, near Sonora, Cal. (described on -pages <a href="#Page_294">294-297</a>), that the evidence of one locality adds -cumulative force to that of the other. The strata underneath -the lava in which these objects were found are all -indirectly, but pretty certainly, connected with the Glacial -period.<a name="FNanchor_32" id="FNanchor_32"></a><a href="#Footnote_32" class="fnanchor">[AF]</a> No student of glacial archæology, therefore, can -hereafter afford to disregard these facts from the Pacific -coast.</p> - -<div class="footnote"> - -<p><a name="Footnote_32" id="Footnote_32"></a><a href="#FNanchor_32"><span class="label">[AF]</span></a> See below, <a href="#Page_349">p. 349</a>.</p></div> - -<p> -Oberlin, Ohio, <i>June 2, 1894</i>.</p> - -<p><span class="pagenum"><a name="Page_xxii" id="Page_xxii"></a> -<a name="Page_xxiii" id="Page_xxiii"></a></span></p> - - -<p class="caption2"><a name="PREFACE_TO_THE_FIRST_EDITION" id="PREFACE_TO_THE_FIRST_EDITION">PREFACE TO THE FIRST EDITION.</a></p> - - -<p><span class="smcap">The</span> wide interest manifested in my treatise upon The -Ice Age in North America and its Bearing upon the Antiquity -of Man (of which a third edition was issued a year -ago), seemed to indicate the desirability of providing for -the public a smaller volume discussing the broader question -of man’s entire relation to the Glacial period in Europe -as well as in America. When the demand for such -a volume became evident, I set about preparing for the -task by spending, first, a season in special study of the -lava-beds of the Pacific coast, whose relations to the Glacial -period and to man’s antiquity are of such great interest; -and, secondly, a summer in Europe, to enable me -to compare the facts bearing upon the subject on both -continents.</p> - -<p>Of course, the chapters of the present volume relating -to America cover much of the same ground gone over in -the previous treatise; but the matter has been entirely rewritten -and very much condensed, so as to give due proportions -to all parts of the subject. It will interest some -to know that most of the new material in this volume was -first wrought over in my second course of Lowell Institute -Lectures, given in Boston during the month of March -last.</p> - -<p>I am under great obligations to Mr. Charles Francis -Adams for his aid in prosecuting investigations upon the -Pacific coast of America; and also to Dr. H. W. Crosskey, -<span class="pagenum"><a name="Page_xxiv" id="Page_xxiv">« xxiv »</a></span> -of Birmingham, England, and to Mr. G. W. Lamplugh, of -Bridlington, as well as to Mr. C. E. De Rance and Mr. -Clement Reid, of the British Geological Survey, besides -many others in England who have facilitated my investigations; -but pre-eminently to Prof. Percy F. Kendall, of -Stockport, who consented to prepare for me the portion -of <a href="#CHAPTER_VI">Chapter VI</a> which relates to the glacial phenomena -of the British Isles. I have no doubt of the general correctness -of the views maintained by him, and little doubt, -also, that his clear and forcible presentation of the facts -will bring about what is scarcely less than a revolution in -the views generally prevalent relating to the subject of -which he treats.</p> - -<p>For the glacial facts relating to France and Switzerland -I am indebted largely to M. Falsan’s valuable compendium, -La Période Glaciaire.</p> - -<p>It goes without saying, also, that I am under the deepest -obligation to the works of Prof. James Geikie upon -The Great Ice Age and upon Prehistoric Europe, and to -the remarkable volume of the late Mr. James Croll upon -Climate and Time, as well as to the recent comprehensive -geological treatises of Sir Archibald Geikie and Prof. -Prestwich. Finally, I would express my gratitude for the -great courtesy of Prof. Fraipont, of Liége, in assisting me -to an appreciation of the facts relating to the late remarkable -discovery of two entire skeletons of Paleolithic man -in the grotto of Spy.</p> - -<p>Comparative completeness is also given to the volume -by the appendix on the question of man’s existence during -the Tertiary period, prepared by the competent hand of -Prof. Henry W. Haynes, of Boston.</p> - -<p>I trust this brief treatise will be useful not only in -<i>interesting</i> the general public, but in giving a clear view -of the present state of progress in one department of the -inquiries concerning man’s antiquity. If the conclusions -reached are not as positive as could be wished, still it is -<span class="pagenum"><a name="Page_xxv" id="Page_xxv">« xxv »</a></span> -both desirable and important to see what degree of indefiniteness -rests upon the subject, in order that rash speculations -may be avoided and future investigations directed -in profitable lines.</p> - -<p> -<span class="smcap">G. Frederick Wright.</span><br /> -<br /> -Oberlin, Ohio, <i>May 1, 1892</i>.</p> - -<p><span class="pagenum"><a name="Page_xxvi" id="Page_xxvi"></a> -<a name="Page_xxvii" id="Page_xxvii"></a></span></p> - - - - -<p class="caption2">CONTENTS.</p> - - -<table summary="ToC"> -<tr> - <td></td> - <td class="smaller tdr">PAGES</td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER I.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Introductory</span></td> - <td class="tdr"><a href="#CHAPTER_I">1-8</a></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER II.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Existing Glaciers</span></td> - <td class="tdr"><a href="#CHAPTER_II">9-42</a></td> -</tr> -<tr> - <td class="tdl2">In Europe; in Asia; in Oceanica; in South America; - on the Antarctic Continent; in North America.</td> - <td></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER III.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Glacial Motion</span></td> - <td class="tdr"><a href="#CHAPTER_III">43-50</a></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER IV.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Signs of Past Glaciation</span></td> - <td class="tdr"><a href="#CHAPTER_IV">51-65</a></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER V.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Ancient Glaciers in the Western Hemisphere</span></td> - <td class="tdr"><a href="#CHAPTER_V">66-128</a></td> -</tr> -<tr> - <td class="tdl2">New England; New York, New Jersey, and Pennsylvania; - the Mississippi Basin; west of the Rocky Mountains.</td> - <td></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER VI.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Ancient Glaciers in the Eastern Hemisphere</span></td> - <td class="tdr"><a href="#CHAPTER_VI">129-192</a></td> -</tr> -<tr> - <td class="tdl2">Central and Southern Europe; the British Isles—the - Preglacial Level of the Land, the Great Glacial Centres, - the Confluent Glaciers, the East Anglian Glacier, - the so-called Great Submergence; Northern Europe; - Asia; Africa.</td> - <td></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER VII.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Drainage Systems in the Glacial Period </span></td> - <td class="tdr"><a href="#CHAPTER_VII">193-241</a></td> -</tr> -<tr> - <td class="tdl2">In America—Preglacial Erosion, Buried Outlets and - Channels, Ice-dams, Ancient River Terraces; in Europe.</td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER VIII. - <span class="pagenum"><a name="Page_xxviii" id="Page_xxviii">« xxviii »</a></span></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Relics of Man in the Glacial Period</span></td> - <td class="tdr"><a href="#CHAPTER_VIII">242-301</a></td> -</tr> -<tr> - <td class="tdl2">In Glacial Terraces of the United States; in Glacial - Terraces of Europe; in Cave Deposits in the British - Isles; in Cave Deposits on the Continent; Extinct - Animals associated with Man; Earliest Man on the - Pacific Coast of North America.</td> - <td></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER IX.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">The Cause of the Glacial Period</span></td> - <td class="tdr"><a href="#CHAPTER_IX">302-331</a></td> -</tr> -<tr> - <td class="caption3" colspan="2">CHAPTER X.</td> -</tr> -<tr> - <td class="tdl"><span class="smcap">The Date of the Glacial Period</span></td> - <td class="tdr"><a href="#CHAPTER_X">332-364</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Appendix on the Tertiary Man</span></td> - <td class="tdr"><a href="#APPENDIX">365-374</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Index</span></td> - <td class="tdr"><a href="#INDEX">375-385</a></td> -</tr> -</table> - -<p><span class="pagenum"><a name="Page_xxix" id="Page_xxix">« xxix »</a></span></p> - - - -<hr class="chap" /> - -<p class="caption2">LIST OF ILLUSTRATIONS.</p> - - -<table summary="Illos"> -<tr> - <td class="smaller">FIG.</td> - <td></td> - <td class="tdr smaller">PAGE</td> -</tr> -<tr> - <td class="tdr">1.</td> - <td class="tdl">Zermatt Glacier</td> - <td class="tdr"><a href="#fig1">2</a></td> -</tr> -<tr> - <td class="tdr">2.</td> - <td class="tdl">Formation of veined structure</td> - <td class="tdr"><a href="#fig2">3</a></td> -</tr> -<tr> - <td class="tdr">3,</td> - <td class="tdl">4. Formation of marginal fissures and veins</td> - <td class="tdr"><a href="#fig3">4</a></td> -</tr> -<tr> - <td class="tdr">5.</td> - <td class="tdl">Fissures and seracs</td> - <td class="tdr"><a href="#fig5">4</a></td> -</tr> -<tr> - <td class="tdr">6.</td> - <td class="tdl">Section across glacial valley, showing old lateral moraines</td> - <td class="tdr"><a href="#fig6">5</a></td> -</tr> -<tr> - <td class="tdr">7.</td> - <td class="tdl">Mont Blanc glacier region</td> - <td class="tdr"><a href="#fig7">10</a></td> -</tr> -<tr> - <td class="tdr">8.</td> - <td class="tdl">Svartisen Glacier</td> - <td class="tdr"><a href="#fig8">13</a></td> -</tr> -<tr> - <td class="tdr">9.</td> - <td class="tdl">Floating berg</td> - <td class="tdr"><a href="#fig9">18</a></td> -</tr> -<tr> - <td class="tdr">10.</td> - <td class="tdl">Iceberg in the Antarctic Ocean</td> - <td class="tdr"><a href="#fig10">20</a></td> -</tr> -<tr> - <td class="tdr">11.</td> - <td class="tdl">Map of southeastern Alaska</td> - <td class="tdr"><a href="#fig11">22</a></td> -</tr> -<tr> - <td class="tdr">12.</td> - <td class="tdl">Map of Glacier Bay, Alaska</td> - <td class="tdr"><a href="#fig12">25</a></td> -</tr> -<tr> - <td class="tdr">13.</td> - <td class="tdl">Front of Muir Glacier</td> - <td class="tdr"><a href="#fig13">26</a></td> -</tr> -<tr> - <td class="tdr">14.</td> - <td class="tdl">Map of glaciers in the St. Elias Alps</td> - <td class="tdr"><a href="#fig14">31</a></td> -</tr> -<tr> - <td class="tdr">15.</td> - <td class="tdl">Map of Greenland</td> - <td class="tdr"><a href="#fig15">33</a></td> -</tr> -<tr> - <td class="tdr">16.</td> - <td class="tdl">Diagram showing the character of glacial motion</td> - <td class="tdr"><a href="#fig16">43</a></td> -</tr> -<tr> - <td class="tdr">17.</td> - <td class="tdl">Line of most rapid glacial motion</td> - <td class="tdr"><a href="#fig17">45</a></td> -</tr> -<tr> - <td class="tdr">18.</td> - <td class="tdl">Diagram showing retardation of the bottom of a glacier</td> - <td class="tdr"><a href="#fig18">46</a></td> -</tr> -<tr> - <td class="tdr">19.</td> - <td class="tdl">Bed-rock scored with glacial marks</td> - <td class="tdr"><a href="#fig19">52</a></td> -</tr> -<tr> - <td class="tdr">20.</td> - <td class="tdl">Scratched stone from the till of Boston</td> - <td class="tdr"><a href="#fig20">54</a></td> -</tr> -<tr> - <td class="tdr">21.</td> - <td class="tdl">Typical section of till in Seattle, Wash.</td> - <td class="tdr"><a href="#fig21">55</a></td> -</tr> -<tr> - <td class="tdr">22.</td> - <td class="tdl">Ideal section showing how the till overlies the stratified - rocks</td> - <td class="tdr"><a href="#fig22">56</a></td> -</tr> -<tr> - <td class="tdr">23.</td> - <td class="tdl">Vessel Rock, a glacial boulder</td> - <td class="tdr"><a href="#fig23">56</a></td> -</tr> -<tr> - <td class="tdr">24.</td> - <td class="tdl">Map of Rhône Glacier</td> - <td class="tdr"><a href="#fig24">58</a></td> -</tr> -<tr> - <td class="tdr">25.</td> - <td class="tdl">Conglomerate boulder found in Boone County, Ky.</td> - <td class="tdr"><a href="#fig25">63</a></td> -</tr> -<tr> - <td class="tdr">26.</td> - <td class="tdl">Mohegan Rock</td> - <td class="tdr"><a href="#fig26">72</a></td> -</tr> -<tr> - <td class="tdr">27.</td> - <td class="tdl">Drumlins in Goffstown, N. H.</td> - <td class="tdr"><a href="#fig27">73</a></td> -</tr> -<tr> - <td class="tdr">28.</td> - <td class="tdl">Map of drumlins in the vicinity of Boston</td> - <td class="tdr"><a href="#fig28">75</a></td> -</tr> -<tr> - <td class="tdr">29.</td> - <td class="tdl">Section of kame</td> - <td class="tdr"><a href="#fig29">77</a></td> -</tr> -<tr> - <td class="tdr">30.</td> - <td class="tdl">Map of kames in Andover, Mass.</td> - <td class="tdr"><a href="#fig30">78</a></td> -</tr> -<tr> - <td class="tdr">31.</td> - <td class="tdl">Longitudinal kames near Hingham, Mass.</td> - <td class="tdr"><a href="#fig31">79</a> - <span class="pagenum"><a name="Page_xxx" id="Page_xxx">« xxx »</a></span></td> -</tr> -<tr> - <td class="tdr">32.</td> - <td class="tdl">Map showing the kames of Maine and southeastern New Hampshire</td> - <td class="tdr"><a href="#fig32">81</a></td> -</tr> -<tr> - <td class="tdr">33.</td> - <td class="tdl">Western face of the Kettle Moraine near Eagle, Wis.</td> - <td class="tdr"><a href="#fig33">99</a></td> -</tr> -<tr> - <td class="tdr">34.</td> - <td class="tdl">Section of the east-and-west glacial furrows on Kelly’s - Island</td> - <td class="tdr"><a href="#fig34">103</a></td> -</tr> -<tr> - <td class="tdr">35.</td> - <td class="tdl">Same as the preceding</td> - <td class="tdr"><a href="#fig35">105</a></td> -</tr> -<tr> - <td class="tdr">36.</td> - <td class="tdl">Section of till near Germantown, Ohio</td> - <td class="tdr"><a href="#fig36">108</a></td> -</tr> -<tr> - <td class="tdr">37.</td> - <td class="tdl">Moraines of Grape Creek, Col.</td> - <td class="tdr"><a href="#fig37">123</a></td> -</tr> -<tr> - <td class="tdr">38.</td> - <td class="tdl">Map of North America in the Ice period</td> - <td class="tdr"><a href="#fig38">127</a></td> -</tr> -<tr> - <td class="tdr">39.</td> - <td class="tdl">Quartzite boulder on Mont Lachat</td> - <td class="tdr"><a href="#fig39">128</a></td> -</tr> -<tr> - <td class="tdr">40.</td> - <td class="tdl">Map showing glaciated areas in North America and Europe</td> - <td class="tdr"><a href="#fig40">130</a></td> -</tr> -<tr> - <td class="tdr">41.</td> - <td class="tdl">Maps showing lines of <i>débris</i> extending from the Alps into - the plains of the Po</td> - <td class="tdr"><a href="#fig41">134</a></td> -</tr> -<tr> - <td class="tdr">42.</td> - <td class="tdl">Section of the Cefn Cave</td> - <td class="tdr"><a href="#fig42">148</a></td> -</tr> -<tr> - <td class="tdr">43.</td> - <td class="tdl">Map showing moraine between Speeton and Flamborough</td> - <td class="tdr"><a href="#fig43">156</a></td> -</tr> -<tr> - <td class="tdr">44.</td> - <td class="tdl">Diagram-section near Cromer</td> - <td class="tdr"><a href="#fig44">166</a></td> -</tr> -<tr> - <td class="tdr">45.</td> - <td class="tdl">Section through the westerly chalk bluff at Trimingham, - Norfolk</td> - <td class="tdr"><a href="#fig45">162</a></td> -</tr> -<tr> - <td class="tdr">46.</td> - <td class="tdl">Section across Wales</td> - <td class="tdr"><a href="#fig46">172</a></td> -</tr> -<tr> - <td class="tdr">47.</td> - <td class="tdl">Section of cliff at Flamborough Head</td> - <td class="tdr"><a href="#fig47">176</a></td> -</tr> -<tr> - <td class="tdr">48.</td> - <td class="tdl">Enlarged section of the shelly sand and surrounding clay - at <i>B</i> in preceding figure</td> - <td class="tdr"><a href="#fig48">177</a></td> -</tr> -<tr> - <td class="tdr">49.</td> - <td class="tdl">Map showing the glaciated area of Europe</td> - <td class="tdr"><a href="#fig49">184</a></td> -</tr> -<tr> - <td class="tdr">50.</td> - <td class="tdl">Map showing old channel and mouth of the Hudson</td> - <td class="tdr"><a href="#fig50">195</a></td> -</tr> -<tr> - <td class="tdr">51.</td> - <td class="tdl">New York Harbor in preglacial times</td> - <td class="tdr"><a href="#fig51">197</a></td> -</tr> -<tr> - <td class="tdr">52.</td> - <td class="tdl">Section across the valley of the Cuyahoga River</td> - <td class="tdr"><a href="#fig52">200</a></td> -</tr> -<tr> - <td class="tdr">53.</td> - <td class="tdl">Map of Mississippi River from Fort Snelling to Minneapolis</td> - <td class="tdr"><a href="#fig53">209</a></td> -</tr> -<tr> - <td class="tdr">54.</td> - <td class="tdl">Map showing the effect of the glacial dam at Cincinnati</td> - <td class="tdr"><a href="#fig54">213</a></td> -</tr> -<tr> - <td class="tdr">55.</td> - <td class="tdl">Map of Lake Erie-Ontario</td> - <td class="tdr"><a href="#fig55">219</a></td> -</tr> -<tr> - <td class="tdr">56.</td> - <td class="tdl">Map of Cuyahoga Lake</td> - <td class="tdr"><a href="#fig56">221</a></td> -</tr> -<tr> - <td class="tdr">57.</td> - <td class="tdl">Section of the lake ridges near Sandusky, Ohio</td> - <td class="tdr"><a href="#fig57">223</a></td> -</tr> -<tr> - <td class="tdr">58.</td> - <td class="tdl">Map showing stages of recession of the ice in Minnesota</td> - <td class="tdr"><a href="#fig58">225</a></td> -</tr> -<tr> - <td class="tdr">59.</td> - <td class="tdl">Glacial terrace on Raccoon Creek, in Ohio</td> - <td class="tdr"><a href="#fig59">227</a></td> -</tr> -<tr> - <td class="tdr">60.</td> - <td class="tdl">Ideal section across a river-bed in drift region</td> - <td class="tdr"><a href="#fig60">229</a></td> -</tr> -<tr> - <td class="tdr">61.</td> - <td class="tdl">Map of Lakes Bonneville and Lahontan</td> - <td class="tdr"><a href="#fig61">234</a></td> -</tr> -<tr> - <td class="tdr">62.</td> - <td class="tdl">Parallel roads of Glen Roy</td> - <td class="tdr"><a href="#fig62">239</a></td> -</tr> -<tr> - <td class="tdr">63.</td> - <td class="tdl">Map showing glacial terraces on the Delaware and - Schuylkill Rivers</td> - <td class="tdr"><a href="#fig63">243</a></td> -</tr> -<tr> - <td class="tdr">64.</td> - <td class="tdl">Palæolith found by Abbott in New Jersey</td> - <td class="tdr"><a href="#fig64">244</a> - <span class="pagenum"><a name="Page_xxxi" id="Page_xxxi">« xxxi »</a></span></td> -</tr> -<tr> - <td class="tdr">65.</td> - <td class="tdl">Section across the Delaware River at Trenton, N. J.</td> - <td class="tdr"><a href="#fig65">245</a></td> -</tr> -<tr> - <td class="tdr">66.</td> - <td class="tdl">Section of the Trenton gravel</td> - <td class="tdr"><a href="#fig66">246</a></td> -</tr> -<tr> - <td class="tdr">67.</td> - <td class="tdl">Face view of argillite implement found by Dr. C. C. Abbott - in 1876.</td> - <td class="tdr"><a href="#fig67">247</a></td> -</tr> -<tr> - <td class="tdr">68.</td> - <td class="tdl">Argillite implement found by Dr. C. C. Abbott, March, 1879</td> - <td class="tdr"><a href="#fig68">248</a></td> -</tr> -<tr> - <td class="tdr">69.</td> - <td class="tdl">Chipped pebble of black chert found by Dr. C. L. Metz, - October, 1885</td> - <td class="tdr"><a href="#fig69">249</a></td> -</tr> -<tr> - <td class="tdr">70.</td> - <td class="tdl">Map showing glaciated area in Ohio</td> - <td class="tdr"><a href="#fig70">250</a></td> -</tr> -<tr> - <td class="tdr">71.</td> - <td class="tdl">Palæoliths from Newcomerstown and Amiens (face view)</td> - <td class="tdr"><a href="#fig71">252</a></td> -</tr> -<tr> - <td class="tdr">72.</td> - <td class="tdl">Edge view of the preceding</td> - <td class="tdr"><a href="#fig72">253</a></td> -</tr> -<tr> - <td class="tdr">73.</td> - <td class="tdl">Section across the Mississippi Valley at Little Falls, Minn.</td> - <td class="tdr"><a href="#fig73">254</a></td> -</tr> -<tr> - <td class="tdr">74.</td> - <td class="tdl">Quartz implement found by Miss F. E. Babbitt, 1878, at Little - Falls, Minn</td> - <td class="tdr"><a href="#fig74">255</a></td> -</tr> -<tr> - <td class="tdr">75.</td> - <td class="tdl">Argillite implement found by H. T. Cresson, 1887</td> - <td class="tdr"><a href="#fig75">259</a></td> -</tr> -<tr> - <td class="tdr">76.</td> - <td class="tdl">General view of Baltimore and Ohio Railroad cut, - Claymont, Del.</td> - <td class="tdr"><a href="#fig76">260</a></td> -</tr> -<tr> - <td class="tdr">77.</td> - <td class="tdl">Section across valley of the Somme</td> - <td class="tdr"><a href="#fig77">262</a></td> -</tr> -<tr> - <td class="tdr">78.</td> - <td class="tdl">Mouth of Kent’s Hole</td> - <td class="tdr"><a href="#fig78">268</a></td> -</tr> -<tr> - <td class="tdr">79.</td> - <td class="tdl">Engis skull (reduced)</td> - <td class="tdr"><a href="#fig79">274</a></td> -</tr> -<tr> - <td class="tdr">80.</td> - <td class="tdl">Comparison of forms of skulls</td> - <td class="tdr"><a href="#fig80">276</a></td> -</tr> -<tr> - <td class="tdr">81.</td> - <td class="tdl">Skull of the Man of Spy</td> - <td class="tdr"><a href="#fig81">277</a></td> -</tr> -<tr> - <td class="tdr">82.</td> - <td class="tdl">Tooth of Machairodus neogæus</td> - <td class="tdr"><a href="#fig82">281</a></td> -</tr> -<tr> - <td class="tdr">83.</td> - <td class="tdl">Perfect tooth of an Elephas</td> - <td class="tdr"><a href="#fig83">281</a></td> -</tr> -<tr> - <td class="tdr">84.</td> - <td class="tdl">Skull of Hyena spelæa</td> - <td class="tdr"><a href="#fig84">282</a></td> -</tr> -<tr> - <td class="tdr">85.</td> - <td class="tdl">Celebrated skeleton of mammoth in St. Petersburg Museum</td> - <td class="tdr"><a href="#fig85">283</a></td> -</tr> -<tr> - <td class="tdr">86.</td> - <td class="tdl">Molar tooth of mammoth</td> - <td class="tdr"><a href="#fig86">284</a></td> -</tr> -<tr> - <td class="tdr">87.</td> - <td class="tdl">Tooth of Mastodon Americanus</td> - <td class="tdr"><a href="#fig87">284</a></td> -</tr> -<tr> - <td class="tdr">88.</td> - <td class="tdl">Skeleton of Mastodon Americanus</td> - <td class="tdr"><a href="#fig88">286</a></td> -</tr> -<tr> - <td class="tdr">89.</td> - <td class="tdl">Skeleton of Rhinoceros tichorhinus</td> - <td class="tdr"><a href="#fig89">287</a></td> -</tr> -<tr> - <td class="tdr">90.</td> - <td class="tdl">Skull of cave-bear</td> - <td class="tdr"><a href="#fig90">287</a></td> -</tr> -<tr> - <td class="tdr">91.</td> - <td class="tdl">Skeleton of the Irish elk</td> - <td class="tdr"><a href="#fig91">288</a></td> -</tr> -<tr> - <td class="tdr">92.</td> - <td class="tdl">Musk-sheep</td> - <td class="tdr"><a href="#fig92">289</a></td> -</tr> -<tr> - <td class="tdr">93.</td> - <td class="tdl">Reindeer</td> - <td class="tdr"><a href="#fig93">290</a></td> -</tr> -<tr> - <td class="tdr">94.</td> - <td class="tdl">Section across Table Mountain, Tuolumne County, Cal.</td> - <td class="tdr"><a href="#fig94">294</a></td> -</tr> -<tr> - <td class="tdr">95.</td> - <td class="tdl">Calaveras skull</td> - <td class="tdr"><a href="#fig95">295</a></td> -</tr> -<tr> - <td class="tdr">96.</td> - <td class="tdl">Three views of Nampa image, drawn to scale</td> - <td class="tdr"><a href="#fig96">298</a></td> -</tr> -<tr> - <td class="tdr">97.</td> - <td class="tdl">Map showing Pocatello, Nampa, and the valley of Snake River</td> - <td class="tdr"><a href="#fig97">299</a></td> -</tr> -<tr> - <td class="tdr">98.</td> - <td class="tdl">Section across the channel of the Stanislaus River</td> - <td class="tdr"><a href="#fig98">300</a></td> -</tr> -<tr> - <td class="tdr">99.</td> - <td class="tdl">Diagram showing effect of precession</td> - <td class="tdr"><a href="#fig99">308</a></td> -</tr> -<tr> - <td class="tdr">100.</td> - <td class="tdl">Map showing course of currents in the Atlantic Ocean</td> - <td class="tdr"><a href="#fig100">314</a></td> -</tr> -<tr> - <td class="tdr">101.</td> - <td class="tdl">Map showing how the land clusters about the north pole</td> - <td class="tdr"><a href="#fig101">319</a></td> -</tr> -<tr> - <td class="tdr">102.</td> - <td class="tdl">Diagram showing oscillations of land-surface and ice-surface - during the Glacial epoch</td> - <td class="tdr"><a href="#fig102">323</a></td> -</tr> -<tr> - <td class="tdr">103.</td> - <td class="tdl">Diagram of eccentricity and precession</td> - <td class="tdr"><a href="#fig103">333</a></td> -</tr> -<tr> - <td class="tdr">104.</td> - <td class="tdl">Map of the Niagara River below the Falls</td> - <td class="tdr"><a href="#fig104">334</a></td> -</tr> -<tr> - <td class="tdr">105.</td> - <td class="tdl">Section of strata along the Niagara Gorge</td> - <td class="tdr"><a href="#fig105">336</a></td> -</tr> -<tr> - <td class="tdr">106.</td> - <td class="tdl">Map showing the recession of the Horseshoe Falls since 1842</td> - <td class="tdr"><a href="#fig106">338</a></td> -</tr> -<tr> - <td class="tdr">107.</td> - <td class="tdl">Section of kettle-hole near Pomp’s Pond, Andover, Mass.</td> - <td class="tdr"><a href="#fig107">345</a></td> -</tr> -<tr> - <td class="tdr">108.</td> - <td class="tdl">Flint-flakes collected by Abbé Bourgeois</td> - <td class="tdr"><a href="#fig108">368</a></td> -</tr> -</table> - - -<p class="caption2">MAPS.</p> - -<table summary="Maps"> -<tr> - <td></td> - <td class="tdr smaller">TO FACE PAGE</td> -</tr> -<tr> - <td class="tdl">Contour and glacial map of the British Isles <a href="#map_brit_glac"><i>Frontispiece.</i></a></td> - <td></td> -</tr> -<tr> - <td class="tdl">Map showing the glacial geology of the United States</td> - <td class="tdr"><a href="#map_usa_glac">66</a></td> -</tr> -<tr> - <td class="tdl">Map of glacial movements in France and Switzerland</td> - <td class="tdr"><a href="#map_glac_mv">132</a></td> -</tr> -</table> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_1" id="Page_1">« 1 »</a></span></p> - - -<p class="caption1 pmt4 pmb4"><a name="MAN_AND_THE_GLACIAL_PERIOD" id="MAN_AND_THE_GLACIAL_PERIOD">MAN AND THE GLACIAL PERIOD.</a></p> - - -<hr class="chap" /> - -<p class="caption2"><a name="CHAPTER_I" id="CHAPTER_I">CHAPTER I.</a></p> - -<p class="caption2">INTRODUCTORY.</p> - - -<p><span class="smcap">That</span> glaciers now exist in the Alps, in the Scandinavian -range, in Iceland, in the Himalayas, in New Zealand, -in Patagonia, and in the mountains of Washington, -British Columbia, and southeastern Alaska, and that a -vast ice-sheet envelops Greenland and the Antarctic Continent, -are statements which can be verified by any one -who will take the trouble to visit those regions. That, at -a comparatively recent date, these glaciers extended far -beyond their present limits, and that others existed upon -the highlands of Scotland and British America, and at -one time covered a large part of the British Isles, the -whole of British America, and a considerable area in the -northern part of the United States, are inferences drawn -from phenomena which are open to every one’s observations. -That man was in existence and occupied both Europe -and America during this great expansion of the -northern glaciers is proved by evidence which is now beyond -dispute. It is the object of the present volume to -make a concise presentation of the facts which have been -rapidly accumulating during the past few years relating -to the Glacial period and to its connection with human -history.</p> - -<p>Before speaking of the number and present extent of -existing glaciers, it will be profitable, however, to devote a -little attention to the definition of terms.</p> - -<p><span class="pagenum"><a name="Page_2" id="Page_2">« 2 »</a></span></p> - -<div class="fig_center" style="width: 377px;"> -<a id="fig1" name="fig1"></a> -<img src="images/fig_1.png" width="377" height="352" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 1.</span>—Zermatt Glacier (Agassiz).</div> -</div> - -<p>A <i>glacier</i> is a mass of ice so situated and of such size as -to have motion in itself. The conditions determining the -character and rate of this motion will come up for statement -and discussion later. It is sufficient here to say that -ice has a capacity of movement similar to that possessed -by such plastic substances as cold molasses, wax, tar, or -cooling lava.</p> - -<p>The limit of a glacier’s <i>motion</i> is determined by the -forces which fix the point at which its final melting takes -place. This will therefore depend upon both the warmth -of the weather and upon the amount of ice. If the ice -is abundant, it will move farther into the region of warm -temperature than it will if it is limited in supply.</p> - -<p>Upon ascending a glacier far enough, one reaches a -<span class="pagenum"><a name="Page_3" id="Page_3">« 3 »</a></span> -comparatively motionless part corresponding to the lake -out of which a river often flows. Technically this is -called the <i>névé</i>.</p> - -<p><i>Glacial ice</i> is formed from snow where the annual fall -is in excess of the melting power of the sun at that point. -Through the influence of pressure, such as a boy applies -to a snow-ball (but which in the <i>névé</i>-field arises from the -weight of the accumulating mass), the lower strata of the -<i>névé</i> are gradually transformed into ice. This process, is -also assisted by the moisture which percolates through the -snowy mass, and which is furnished both by the melting -of the surface snow and by occasional rains.</p> - -<p>The division between the <i>névé</i> and the glacier proper is -not always easily determined. The beginnings of the glacial -movement—that is, of the movement of the ice-stream -flowing out of the <i>névé</i>-field—are somewhat like the beginnings -of the movement of the water from a great lake -into its outlet. The <i>névé</i> is the reservoir from which the -glacier gets both its supply of ice and the impulse which -gives it its first movement. There can not be a glacier -without a <i>névé</i>-field, as there can not be a river without a -drainage basin. But there may -be a <i>névé</i>-field without a glacier—that -is, a basin may be partially -filled with snow which never melts -completely away, while the equilibrium -of forces is such that the -ice barely reaches to the outlet -from which the tongue-like projection -(to which the name glacier -would be applied) fails to emerge -only because of the lack of material.</p> - -<div class="fig_left" style="width: 147px;"> -<a id="fig2" name="fig2"></a> -<img src="images/fig_2.png" width="147" height="147" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 2.</span>—Illustrates the formation -of veined structure by pressure at the junction of two branches.</div> -</div> - -<p>A glacier is characterised by both <i>veins</i> and <i>fissures</i>. -The veins give it a banded or stratified appearance, blue -alternating with lighter-coloured portions of ice. As these -<span class="pagenum"><a name="Page_4" id="Page_4">« 4 »</a></span> -bands are not arranged with any apparent uniformity in -the glacier, their explanation has given rise to much discussion. -Sometimes the veins are horizontal, sometimes -vertical, and at other times at an angle with the line of -motion. On close investigation, however, it is found that -the veins are always at right angles to the line of greatest -pressure. This leads to the conclusion that pressure is -the cause of the banded structure. The blue strata in the -ice are those from which the particles of air have been -expelled by pressure; -the lighter portions are -those in which the particles -are less thoroughly -compacted. Snow is -but pulverized ice, and -differs in colour from -the compact mass for -the same reason that almost -all rocks and minerals -change their colour when ground into a powder.</p> - -<div class="fig_left" style="width: 225px;"> -<a id="fig3" name="fig3"></a> -<a id="fig4" name="fig4"></a> -<img src="images/fig_3-4.png" width="225" height="131" alt="" /> -<div class="fig_caption"><span class="smcap">Figs. 3, 4.</span>—Illustrate the formation of marginal -fissures and veins.</div> -</div> - -<div class="fig_left" style="width: 282px;"> -<a id="fig5" name="fig5"></a> -<img src="images/fig_5.png" width="282" height="125" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 5.</span>—<i>c</i>, <i>c</i>, show fissures and seracs where the glacier -moves down the steeper portion of its incline; <i>s</i>, <i>s</i>, -show the vertical structure produced by pressure on -the gentler slopes.</div> -</div> - -<p>The <i>fissures</i>, which, when of large size, are called -<i>crevasses</i>, are formed in those portions of a glacier where, -from some cause, the ice is subjected to slight tension. This -occurs especially where, through irregularities in the bottom, -the slope of the descent is increased. The -ice, then, instead of moving in a continuous -stream at the top, cracks open -along the line of tension, and -wedge-shaped -fissures are -formed extending from -the top down -to a greater -or less distance, according to the degree of tension. Usually, -however, the ice remains continuous in the lower -<span class="pagenum"><a name="Page_5" id="Page_5">« 5 »</a></span> -strata, and when the slope is diminished the pressure reunites -the faces of the fissure, and the surface becomes -again comparatively smooth. Where there are extensive -areas of tension, the surface of the ice sometimes becomes -exceedingly broken, presenting a tangled mass of towers, -domes, and pinnacles of ice called <i>seracs</i>.</p> - -<div class="fig_right" style="width: 244px;"> -<a id="fig6" name="fig6"></a> -<img src="images/fig_6.png" width="244" height="118" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 6.</span>—Section across Glacial Valley, showing old -Lateral Moraines.</div> -</div> - -<p>Like running water, moving ice is a powerful agent in -<i>transporting</i> rocks and earthy <i>débris</i> of all grades of -fineness; but, owing to the different consistencies of ice -and water, there are great differences in the mode and -result of transportation by them. While water can hold -in suspension only the very finest material, ice can bear -upon its surface -rocks of the greatest -magnitude, and -can roll or shove -along under it -boulders and pebbles -which would -be Unaffected except by torrential -currents of water. We find, therefore, a great amount of -earthy material of all sizes upon the top of a glacier, which -has reached it very much as <i>débris</i> reaches the bed of a -river, namely, by falling down upon it from overhanging -cliffs, or by land-slides of greater or less extent. Such -material coming into a river would either disappear beneath -its surface, or would form a line of <i>débris</i> along the -banks; in both cases awaiting the gradual erosion and -transportation which running water is able to effect. But, -in case of a glacier, the material rests upon the surface of -the ice, and at once begins to partake of its motion, while -successive accessions of material keep up the supply at any -one point, so as to form a train of boulders and other -<i>débris</i>, extending below the point as far as the glacial -motion continues.</p> - -<p><span class="pagenum"><a name="Page_6" id="Page_6">« 6 »</a></span></p> - -<p>Such a line of <i>débris</i> is called a <i>moraine</i>. When it -forms along the edge of the ice, it is called a <i>lateral</i> -moraine. It is easy to see that, where glaciers come out -from two valleys which are tributary to a larger valley, -their inner sides must coalesce below the separating promontory, -and the two lateral moraines will become united -and will move onward in the middle of the surface of the -glacier. Such lines of <i>débris</i> are called <i>medial</i> moraines. -These are characteristic of all extensive glaciers formed by -the union of tributaries. There is no limit to the number -of medial moraines, except in the number of tributaries.</p> - -<p>A medial moraine, when of sufficient thickness, protects -the ice underneath it from melting; so that the -moraine will often appear to be much larger than it really -is: what seems to be a ridge of earthy material being in -reality a long ridge of ice, thinly covered with earthy <i>débris</i>, -sliding down the slanting sides as the ice slowly wastes -away Large blocks of stone in the same manner protect -the ice from melting underneath, and are found standing -on pedestals of ice, often several feet in height. An interesting -feature of these blocks is that, when the pedestal -fails, the block uniformly falls towards the sun, since that -is the side on which the melting has proceeded most -rapidly.</p> - -<p>If the meteorological forces are so balanced that the -foot of a glacier remains at the same place for any great -length of time, there must be a great accumulation of -earthy <i>débris</i> at the stationary point, since the motion of -the ice is constantly bearing its lines of lateral and medial -moraine downwards to be deposited, year by year, at the -melting line along the front.</p> - -<p>Such accumulations are called <i>terminal</i> moraines, and -the process of their formation may be seen at the foot of -almost any large glacier. The pile of material thus confusedly -heaped up in front of some of the larger glaciers -of the world is enormous.</p> - -<p><span class="pagenum"><a name="Page_7" id="Page_7">« 7 »</a></span></p> - -<p>The melting away of the lower part of a glacier gives -rise also to several other characteristic phenomena. Where -the foot of a glacier chances to be on comparatively level -land, the terminal moraine often covers a great extent of -ice, and protects it from melting for an indefinite period -of time. When the ice finally melts away and removes the -support from the overlying morainic <i>débris</i>, this settles -down in a very irregular manner, leaving enclosed depressions -to which there is no natural outlet. These depressions, -from their resemblance to a familiar domestic utensil, -are technically known as <i>kettle-holes</i>. The terminal -moraines of ancient glaciers may often be traced by the -relative abundance of these kettle-holes.</p> - -<p>The streams of water arising both from the rainfall -and from the melting of the ice also produce a peculiar -effect about the foot of an extensive glacier. Sometimes -these streams cut long, open channels near the end of the -glacier, and sweep into it vast quantities of morainic material, -which is pushed along by the torrential current, and, -after being abraded, rolled, and sorted, is deposited in a -delta about its mouth, or left stranded in long lines between -the ice-walls which have determined its course. At -other times the stream has disappeared far back in the -glacier, and plunged into a crevasse (technically called a -<i>moulin</i>), whence it flows onwards as a subglacial stream. -But in this case the deposits might closely resemble those -of the previous description. In both cases, when the ice -has finally melted away, peculiar ridge-like deposits of -sorted material remain, to mark the temporary line of -drainage. These exist abundantly in most regions which -have been covered with glacial ice, and are referred to in -Scotland as <i>kames</i>, in Ireland as <i>eskers</i>, and in Sweden as -<i>osars</i>. In this volume we shall call them <i>kames</i>, and the -deltas spread out in front of them will be referred to as -<i>kame-plains</i>.</p> - -<p>With this preliminary description of glacial phenomena, -<span class="pagenum"><a name="Page_8" id="Page_8">« 8 »</a></span> -we will proceed to give, first, a brief enumeration and -description of the ice-fields which are still existing in the -world; second, the evidences of the former existence of -far more extensive ice-fields; and, third, the relation of -the Glacial period to some of the vicissitudes which have -attended the life of man in the world.</p> - -<p>The geological period of which we shall treat is variously -designated by different writers. By some it is simply -called the “post-Tertiary,” or “Quaternary”; by others -the term “post-Pliocene” is used, to indicate more sharply -its distinction from the latter portion of the Tertiary -period; by others this nicety of distinction is expressed -by the term “Pleistocene.” But, since the whole epoch -was peculiarly characterised by the presence of glaciers, -which have not even yet wholly disappeared, we may -properly refer to it altogether under the descriptive name -of “Glacial” period.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_9" id="Page_9">« 9 »</a></span></p> - - - - -<p class="caption2"><a name="CHAPTER_II" id="CHAPTER_II">CHAPTER II.</a></p> - -<p class="caption2">EXISTING GLACIERS.</p> - - -<p><i>In Europe.</i>—Our specific account of existing glaciers -naturally begins with those of the Alps, where Hugi, -Charpentier, Agassiz, Forbes, and Guyot, before the middle -of this century, first brought clearly to light the reality -and nature of glacial motion.</p> - -<p>According to Professor Heim, of Zürich, the total area -covered by the glaciers and ice-fields of the Alps is upwards -of three thousand square kilometres (about eleven -hundred square miles). The Swiss Alps alone contain -nearly two-thirds of this area. Professor Heim enumerates -1,155 distinct glaciers in the region. Of these, 144 -are in France, 78 in Italy, 471 in Switzerland, and 462 in -Austria.</p> - -<p>Desor describes fourteen principal glacial districts in -the Alps, the westernmost of which is that of Mont Pelvoux, -in Dauphiny, and the easternmost that in the vicinity -of the Gross Glockner, in Carinthia. The most important -of the Alpine systems are those which are grouped -around Mont Blanc, Monte Rosa, and the Finsteraarhorn, -the two former peaks being upwards of fifteen thousand -feet in height, and the latter upwards of fourteen thousand. -The area covered by glaciers and snow-fields in the -Bernese Oberland, of which Finsteraarhorn is the culminating -point, is about three hundred and fifty square kilometres -(a hundred square miles), and contains the Aletsch -Glacier, which is the longest in Europe, extending twenty-one -kilometres (about fourteen miles) from the <i>névé</i>-field -to its foot. The Mer de Glace, which descends from Mont -Blanc to the valley of Chamounix, has a length of about -eight miles below the <i>névé</i>-field. In all, there are estimated -to be twenty-four glaciers in the Alps which are -upwards of four miles long, and six which are upwards of -eight miles in length. The principal of these are the Mer -de Glace, of Chamounix, on Mont Blanc; the Gorner -Glacier, near Zermatt, on Monte Rosa; the lower glacier -of the Aar, in the Bernese Oberland; and the Aletsch -Glacier and Glacier of the Rhône, in Vallais; and the -Pasterzen, in Carinthia.</p> - -<p><span class="pagenum"><a name="Page_10" id="Page_10">« 10 »</a></span></p> - -<div class="fig_center" style="width: 616px;"> -<a id="fig7" name="fig7"></a> -<img src="images/fig_7.png" width="616" height="384" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 7.</span>—Mount Blanc Glacier Region: <i>m</i>, Mer de Glace; <i>g</i>, Du Géant; <i>l</i>, Leschaux; <i>t</i>, Taléfre; <i>B</i>, Bionassay; <i>b</i>, Bosson.</div> -</div> - -<p><span class="pagenum"><a name="Page_11" id="Page_11">« 11 »</a></span></p> - -<p>These glaciers adjust themselves to the width of the -valleys down which they flow, in some places being a mile -or more in width, and at others contracting into much -narrower compass. The greatest depth which Agassiz -was able directly to measure in the Aar Glacier was two -hundred and sixty metres (five hundred and twenty-eight -feet), but at another point the depth was estimated by -him to be four hundred and sixty metres (or fifteen hundred -and eighty-four feet).</p> - -<p>The glaciers of the Alps are mostly confined to the -northern side and to the higher portions of the mountain-chain, -none of them descending below the level of four -thousand feet, and all of them varying slightly in extent, -from year to year, according as there are changes in the -temperature and in the amount of snow-fall.</p> - -<p>The Pyrenees, also, still maintain a glacial system, but -it is of insignificant importance. This is partly because -the altitude is much less than that of the Alps, the culminating -point being scarcely more than eleven thousand -feet in height. Doubtless, also, it is partly due to the -narrowness of the range, which does not provide gathering-places -for the snow sufficiently extensive to produce large -glaciers. The snow-fall also is less upon the Pyrenees -than upon the Alps. As a consequence of all these conditions, -the glaciers of the Pyrenees are scarcely more -<span class="pagenum"><a name="Page_12" id="Page_12">« 12 »</a></span> -than stationary <i>névé</i>-fields lingering upon the north side -of the range. The largest of these is near Bagnères de -Luchon, and sends down a short, river-like glacier.</p> - -<p>In Scandinavia the height of the mountains is also -much less than that of the Alps, but the moister climate -and the more northern latitude favours the growth of -glaciers at a much lower level North of the sixty-second -degree of latitude, the plateaus over five thousand feet -above the sea pretty generally are gathering-places for -glaciers. From the Justedal a snow-field, covering five -hundred and eighty square miles, in latitude 62°, twenty-four -glaciers push outwards towards the German Sea, the -largest of which is five miles long and three-quarters of a -mile wide. The Fondalen snow-field, between latitudes -66° and 67°, covers an area about equal to that of the -Justedal; but, on account of its more northern position, -its glaciers descend through the valleys quite to the ocean-level. -The Folgofon snow-field is still farther south, but, -though occupying an area of only one hundred square -miles, it sends down as many as three glaciers to the sea-level. -The total area of the Scandinavian snow-fields is -about five thousand square miles.</p> - -<p>In Sweden Dr. Svenonius estimates that there are, -between latitudes 67° and 68<span class="horsplit"><span class="top">1</span><span class="bottom trt">2</span></span>°, twenty distinct groups of -glaciers, covering an area of four hundred square kilometres -(one hundred and forty-four square miles), and he -numbers upwards of one hundred distinct glaciers of small -size.</p> - -<p>As is to be expected, the large islands in the Polar -Sea north of Europe and Asia are, to a great extent, -covered with <i>névé</i>-fields, and numerous glaciers push out -from them to the sea in all directions, discharging their -surplus ice as bergs, which float away and cumber the -waters with their presence in many distant places.</p> - -<p><span class="pagenum"><a name="Page_13" id="Page_13">« 13 »</a></span></p> - -<div class="fig_center" style="width: 386px;"> -<a id="fig8" name="fig8"></a> -<img src="images/fig_8.png" width="386" height="316" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 8.</span>—The Svartisen Glacier on the west coast of Norway, just within the Arctic -circle, at the head of a fiord ten miles from the ocean. The foot of the -Glacier is one mile wide, and a quarter of a mile back from the water. Terminal -moraine in front. (Photographed by Dr. L. C. Warner.)</div> -</div> - -<p>The island of Spitzbergen, in latitude 76° to 81°, is -favourably situated for the production of glaciers, by -reason both of its high northern latitude, and of its relation -to the Gulf Stream, which conveys around to it an -excessive amount of moisture, thus ensuring an exceptionally -large snow-fall over the island. The mountainous -character of the island also favours the concentration of -the ice-movement into glaciers of vast size and power. -Still, even here, much of the land is free from snow and -ice in summer. But upon the northern portion of the -island there is an extensive table-land, upwards of two -thousand feet above the sea, over which the ice-field is -continuous. Four great glaciers here descend to tide-water -in Magdalena Bay. The largest of these presents at the -front a wall of ice seven thousand feet across and three -hundred feet high; but, as the depth of the water is not -<span class="pagenum"><a name="Page_14" id="Page_14">« 14 »</a></span> -great, few icebergs of large size break off and float away -from it.</p> - -<p>Nova Zembla, though not in quite so high latitude, -has a lower mean temperature upon the coasts than Spitzbergen. -Owing to the absence of high lands and mountains, -however, it is not covered with perpetual snow, -much less with glacial ice, but its level portions are -“carpeted with grasses and flowers,” and sustain extensive -forests of stunted trees.</p> - -<p>Franz-Josef Land, to the north of Nova Zembla, both -contains high mountains and supports glaciers of great -size. Mr. Payer conducted a sledge party into this land -in 1874, and reported that a precipitous wall of glacial -ice, “of more than a hundred feet in height, formed the -usual edge of the coast.” But the motion of the ice is -very slow, and the ice coarse-grained in structure, and it -bears a small amount only of morainic material. So low -is here the line of perpetual snow, that the smaller islands -“are covered with caps of ice, so that a cross-section -would exhibit a regular flat segment of ice.” It is interesting -to note, also, that “many ice-streams, descending -from the high <i>névé</i> plateau, spread themselves out -over the mountain-slopes,” and are not, as in the Alps, -confined to definite valleys.</p> - -<p>Iceland seems to have been properly named, since a -single one of the snow-fields—that of Vatnajoküll, with -an extreme elevation of only six thousand feet—is estimated -by Helland to cover one hundred and fifty Norwegian -square miles (about seven thousand English square -miles), while five other ice-fields (the Langjoküll, the -Hofsjoküll, the Myrdalsjoküll, the Drangajoküll, and the -Glamujoküll) have a combined area of ninety-two Norwegian -or about four thousand five hundred English -square miles. The glaciers are supposed by Whitney to -have been rapidly advancing for some time past.</p> - -<p><i>In Asia.</i>—Notwithstanding its lofty mountains and its -<span class="pagenum"><a name="Page_15" id="Page_15">« 15 »</a></span> -great extent of territory lying in high latitudes, glaciers -are for two reasons relatively infrequent: 1. The land in -the more northern latitudes is low. 2. The dryness of the -atmosphere in the interior of the continent is such that it -unduly limits the snow-fall. Long before they reach the -central plateau of Asia, the currents of air which sweep -over the continent from the Indian Ocean have parted -with their burdens of moisture, having left them in a -snowy mantle upon the southern flanks of the Himalayas. -As a result, we have the extensive deserts of the interior, -where, on account of the clear atmosphere, there is not -snow enough to resist continuously the intense activity of -the unobstructed rays of the sun.</p> - -<p>In spite of their high latitude and considerable elevation -above the sea-level, glaciers are absent from the Ural -Mountains, for the range is too narrow to afford <i>névé</i>-fields -of sufficient size to produce glaciers of large extent.</p> - -<p>The Caucasus Mountains present more favourable conditions, -and for a distance of one hundred and twenty -miles near their central portion have an average height of -12,000 feet, with individual peaks rising to a height of -16,000 feet or more; but, owing to their low latitude, the -line of perpetual snow scarcely reaches down to the 11,000-foot -level. So great are the snow-fields, however, -above this height that many glaciers push their way down -through the narrow mountain-gorges as far as the 6,000-foot -level.</p> - -<p>The Himalaya Mountains present many favourable conditions -for the development of glaciers of large size. The -range is of great extent and height, thus affording ample -gathering-places for the snows, while the relation of the -mountains to the moisture-laden winds from the Indian -Ocean is such that they enjoy the first harvest of the clouds -where the interior of Asia gets only the gleanings. As is -to be expected, therefore, all the great rivers which course -<span class="pagenum"><a name="Page_16" id="Page_16">« 16 »</a></span> -through the plains of Hindustan have their rise in large -glaciers far up towards the summits of the northern -mountains. The Indus and the Ganges are both glacial -streams in their origin, as are their larger tributary -branches—the Basha, the Shigar, and the Sutlej. Many -of the glaciers in the higher levels of the Himalaya -Mountains where these streams rise have a length of -from twenty-five to forty miles, and some of them are -as much as a mile and a half in width and extend for -a long distance, with an inclination as small as one degree -and a half or one hundred and thirty-eight feet to a -mile.</p> - -<p>In the Mustagh range of the western Himalayas there -are two adjoining glaciers whose united length is sixty-five -miles, and another not far away which is twenty-one -miles long and from one to two miles wide in its upper -portion. Its lower portion terminates at an altitude of -16,000 feet above tide, where it is three miles wide and -two hundred and fifty feet thick.</p> - -<p><i>Oceanica.</i>—-Passing eastward to the islands of the Pacific -Ocean, New Zealand is the only one capable of supporting -glaciers. Their existence on this island seems -the more remarkable because of its low latitude (42° to -45°); but a grand range of mountains rises abruptly from -the water on the western coast of the southern island, -culminating in Mount Cook, 13,000 feet above the sea, -and extending for a distance of about one hundred miles. -The extent and height of this chain, coupled with the -moisture of the winds, which sweep without obstruction -over so many leagues of the tropical Pacific, are specially -favourable to the production of ice-fields of great extent. -Consequently we find glaciers in abundance, some of -which are not inferior in extent to the larger ones of -the Alps. The Tasman Glacier, described by Haas, is ten -miles long and nearly two miles broad at its termination, -“the lower portion for a distance of three miles being -<span class="pagenum"><a name="Page_17" id="Page_17">« 17 »</a></span> -covered with morainic <i>detritus</i>.” The Mueller Glacier is -about seven miles long and one mile broad in its lower -portion.</p> - -<p><i>South America.</i>—In America, existing glaciers are -chiefly confined to three principal centres, namely, to -the Andes, south of the equator; to the Cordilleras, north -of central California; and to Greenland.</p> - -<p>In South America, however, the high mountains of -Ecuador sustain a few glaciers above the twelve-thousand-foot -level. The largest of these are upon the eastern slope -of the mountains, giving rise to some of the branches of -the Amazon—indeed, on the flanks of Cotopaxi, Chimborazo, -and Illinissa there are some glaciers in close proximity -to the equator which are fairly comparable in size to those -of the Alps.</p> - -<p>In Chili, at about latitude 35°, glaciers begin to appear -at lower levels, descending beyond the six-thousand-foot -line, while south of this both the increasing -moisture of the winds and the decreasing average temperature -favour the increase of ice-fields and glaciers. Consequently, -as Darwin long ago observed, the line of perpetual -snow here descends to an increasingly lower level, -and glaciers extend down farther and farther towards the -sea, until, in Tierra del Fuego, at about latitude 45°, they -begin to discharge their frozen contents directly into the -tidal inlets. Darwin’s party surveyed a glacier entering -the Gulf of Penas in latitude 46° 50’, which was fifteen -miles long, and, in one part, seven broad. At Eyre’s -Sound, also, in about latitude 48°, they found immense -glaciers coming clown to the sea and discharging icebergs -of great size, one of which, as they encountered it floating -outwards, was estimated to be “<i>at least</i> one hundred and -sixty-eight feet in total height.”</p> - -<p>In Tierra del Fuego, where the mountains are only -from three thousand to four thousand feet in height and -in latitude less than 55°, Darwin reports that "every valley -<span class="pagenum"><a name="Page_18" id="Page_18">« 18 »</a></span> -is filled with streams of ice descending to the sea-coast," -and that the inlets penetrated by his party presented -miniature likenesses of the polar sea.</p> - -<div class="fig_center" style="width: 281px;"> -<a id="fig9" name="fig9"></a> -<img src="images/fig_9.png" width="281" height="316" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 9.</span>—Floating berg, showing the proportions above and under the water. -About seven feet under water to one above.</div> -</div> - -<p><i>Antarctic Continent.</i>—Of the so-called Antarctic Continent -little is known; but icebergs of great size are frequently -encountered up to 58° south latitude, in the direction -of Cape Horn, and as far as latitude 33° in the direction -of Cape of Good Hope. Nearly all that is known -about this continent was discovered by Sir J. C. Ross -during the period extending from 1839 to 1843, when, -between the parallels of 70° and 78° south latitude, he -encountered in his explorations a precipitous mountain -coast, rising from seven thousand to ten thousand feet -above tide. Through the valleys intervening between the -mountain-ranges huge glaciers descended, and “projected -in many places several miles into the sea and terminated -<span class="pagenum"><a name="Page_19" id="Page_19">« 19 »</a></span> -in lofty, perpendicular cliffs. In a few places the rocks -broke through their icy covering, by which alone we could -be assured that land formed the nucleus of this, to appearance, -enormous iceberg.”<a name="FNanchor_33" id="FNanchor_33"></a><a href="#Footnote_33" class="fnanchor">[AG]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_33" id="Footnote_33"></a><a href="#FNanchor_33"><span class="label">[AG]</span></a> Quoted by Whitney in Climatic Changes, p. 314.</p></div> - -<p>Again, speaking of the region in the vicinity of the -lofty volcanoes Terror and Erebus, between ten thousand -and twelve thousand feet high, the same navigator says:</p> - -<p>“We perceived a low, white line extending from its -extreme eastern point, as far as the eye could discern, -to the eastward. It presented an extraordinary appearance, -gradually increasing in height as we got nearer to -it, and proving at length to be a perpendicular cliff of -ice, between one hundred and fifty and two hundred feet -above the level of the sea, perfectly flat and level at the -top, and without any fissures or promontories on its even, -seaward face. What was beyond it we could not imagine; -for, being much higher than our mast-head, we could not -see anything except the summit of a lofty range of mountains -extending to the southward as far as the seventy-ninth -degree of latitude. These mountains, being the -southernmost land hitherto discovered, I felt great satisfaction -in naming after Sir Edward Parry.... Whether -Parry Mountains again take an easterly trending and -form the base to which this extraordinary mass of ice is -attached, must be left for future navigators to determine. -If there be land to the southward it must be very remote, -or of much less elevation than any other part of the coast -we have seen, or it would have appeared above the barrier.”</p> - -<p>This ice-cliff or barrier was followed by Captain Ross -as far as 198° west longitude, and found to preserve very -much the same character during the whole of that distance. -On the lithographic view of this great ice-sheet -given in Ross’s work it is described as “part of the South -Polar Barrier, one hundred and eighty feet above the sea-level, -<span class="pagenum"><a name="Page_20" id="Page_20">« 20 »</a></span> -one thousand feet thick, and four hundred and fifty -miles in length.”</p> - -<p>A similar vertical wall of ice was seen by D’Urville, off -the coast of Adelie Land. He thus describes it: “Its appearance -was astonishing. We perceived a cliff having a -uniform elevation of from one hundred to one hundred -and fifty feet, forming a long line extending off to the -west.... Thus for more than twelve hours we had followed -this wall of ice, and found its sides everywhere perfectly -vertical and its summit horizontal. Not the smallest -irregularity, not the most inconsiderable elevation, -broke its uniformity for the twenty leagues of distance -which we followed it during the day, although we passed -it occasionally at a distance of only two or three miles, so -that we could make out with ease its smallest irregularities. -Some large pieces of ice were lying along the side -of this frozen coast; but, on the whole, there was open -sea in the offing.” <a name="FNanchor_34" id="FNanchor_34"></a><a href="#Footnote_34" class="fnanchor">[AH]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_34" id="Footnote_34"></a><a href="#FNanchor_34"><span class="label">[AH]</span></a> Whitney’s Climatic Changes, pp. 315, 316.</p></div> - -<div class="fig_center" style="width: 382px;"> -<a id="fig10" name="fig10"></a> -<img src="images/fig_10.png" width="382" height="231" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 10.</span>—Iceberg in the Antarctic Ocean.</div> -</div> - -<p><i>North America.</i>—In North America living glaciers -<span class="pagenum"><a name="Page_21" id="Page_21">« 21 »</a></span> -begin to appear in the Sierra Nevada Mountains, in the -vicinity of the Yosemite Park, in central California. Here -the conditions necessary for the production of glaciers are -favourable, namely, a high altitude, snow-fields of considerable -extent, and unobstructed exposure to the moisture-laden -currents of air from the Pacific Ocean. Sixteen -glaciers of small size have been noted among the summits -to the east of the Yosemite; but none of them descend -much below the eleven-thousand-foot line, and none of -them are over a mile in length. Indeed, they are so small, -and their motion is so slight, that it is a question whether -or not they are to be classed with true glaciers.</p> - -<p>Owing to the comparatively low elevation of the Sierra -Nevada north of Tuolumne County, California, no other -living glaciers are found until reaching Mount Shasta, in -the extreme northern part of the State. This is a volcanic -peak, rising fourteen thousand five hundred feet above -the sea, and having no peaks within forty miles of it as -high as ten thousand feet; yet so abundant is the snow-fall -that as many as five glaciers are found upon its northern -side, some of them being as much as three miles long -and extending as low down as the eight-thousand-foot -level. Upon the southern side glaciers are so completely -absent that Professor Whitney ascended the mountain -and remained in perfect ignorance of its glacial system. -In 1870 Mr. Clarence King first discovered and described -them on the northern side.</p> - -<p>North of California glaciers characterise the Cascade -Range in increasing numbers all the way to the Alaskan -Peninsula. They are to be found upon Diamond Peak, -the Three Sisters, Mount Jefferson, and Mount Hood, in -Oregon, and appear in still larger proportions upon the -flanks of Mount Rainier (or Tacoma) and Mount Baker, -in the State of Washington. The glacier at the head of -the White River Valley is upon the north side of Rainier, -and is the largest one upon that mountain, reaching -down to within five thousand feet of the sea-level, and -being ten miles or more in length. All the streams which -descend the valleys upon this mountain are charged with -the milky-coloured water which betrays their glacial origin.</p> - -<p><span class="pagenum"><a name="Page_22" id="Page_22">« 22 »</a></span></p> - -<div class="fig_center" style="width: 419px;"> -<a id="fig11" name="fig11"></a> -<img src="images/fig_11.png" width="419" height="702" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 11.</span>—Map of Southeastern Alaska. The arrow-points mark glaciers.</div> -</div> - -<p><span class="pagenum"><a name="Page_23" id="Page_23">« 23 »</a></span></p> - -<p>In British Columbia, Glacier Station, upon the Canadian -Pacific Railroad, in the Selkirk Mountains, is within -half a mile of the handsome Illicilliwaet Glacier, while -others of larger size are found at no great distance. The -interior farther north is unexplored to so great an extent -that little can be definitely said concerning its glacial phenomena. -The coast of British Columbia is penetrated by -numerous fiords, each of which receives the drainage of -a decaying glacier; but none are in sight of the tourist-steamers -which thread their way through the intricate -network of channels characterising this coast, until the -Alaskan boundary is crossed and the mouth of the Stickeen -River is passed.</p> - -<p>A few miles up from the mouth of the Stickeen, however, -glaciers of large size come down to the vicinity of -the river, both from the north and from the south, and -the attention of tourists is always attracted by the abundant -glacial sediment borne into the tide-water by the river -itself and discolouring the surface for a long distance beyond -the outlet. Northward from this point the tourist -is rarely out of sight of ice-fields. The Auk and Patterson -Glaciers are the first to come into view, but they do -not descend to the water-level. On nearing Holcomb -Bay, however, small icebergs begin to appear, heralding -the first of the glaciers which descend beyond the water’s -edge. Taku Inlet, a little farther north, presents glaciers -of great size coming down to the sea-level, while the whole -length of Lynn Canal, from Juneau to Chilkat, a distance -of eighty miles, is dotted on both sides by conspicuous -glaciers and ice-fields.</p> - -<p>The Davidson Glacier, near the head of the canal, is -one of the most interesting for purposes of study. It -<span class="pagenum"><a name="Page_24" id="Page_24">« 24 »</a></span> -comes down from an unknown distance in the western interior, -bearing two marked medial moraines upon its surface. -On nearing tide-level, the valley through which -it flows is about three-quarters of a mile in width; but, -after emerging from the confinement of the valley, the -ice spreads out over a fan-shaped area until the width of -its front is nearly three miles. The supply of ice not being -sufficient to push the front of the glacier into deep -water, equilibrium between the forces of heat and cold is -established near the water’s edge. Here, as from year to -year the ice melts and deposits its burdens of earthy <i>débris</i>, -it has piled up a terminal moraine which rises from two -hundred to three hundred feet in height, and is now covered -with evergreen trees of considerable size. From -Chilkat, at the head of Lynn Canal, to the sources of the -Yukon River, the distance is only thirty-five miles, but -the intervening mountain-chain is several thousand feet in -height and bears numerous glaciers upon its seaward -side.</p> - -<p>About forty miles west of Lynn Canal, and separated -from it by a range of mountains of moderate height, is -Glacier Bay, at the head of one of whose inlets is the -Muir Glacier, which forms the chief attraction for the -great number of tourists that now visit the coast of southeastern -Alaska during the summer season. This glacier -meets tide-water in latitude 58° 50’, and longitude 136° 40’ -west of Greenwich. It received its name from Mr. John -Muir, who, in company with Rev. Mr. Young, made a -tour of the bay and discovered the glacier in 1879. It -was soon found that the bay could be safely navigated by -vessels of large size, and from that time on tourists in -increasing number have been attracted to the region. -Commodious steamers now regularly run close up to the -ice-front, and lie-to for several hours, so that the passengers -may witness the “calving” of icebergs, and may -climb upon the sides of the icy stream and look into its -<span class="pagenum"><a name="Page_25" id="Page_25">« 25 »</a></span> -deep crevasses and out upon its corrugated and broken -surface.</p> - -<div class="fig_center" style="width: 419px;"> -<a id="fig12" name="fig12"></a> -<img src="images/fig_12.png" width="419" height="485" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 12.</span>—Map of Glacier Bay. Alaska, and its surroundings. -Arrow-points indicate glaciated area.</div> -</div> - -<p>The first persons who found it in their way to pay -more than a tourist’s visit to this interesting object were -Rev. J. L. Patton, Mr. Prentiss Baldwin, and myself, who -spent the entire month of August, 1886, encamped at the -<span class="pagenum"><a name="Page_26" id="Page_26">« 26 »</a></span> -foot of the glacier, conducting such observations upon it -as weather and equipment permitted. From that time -till the summer of 1890 no one else stopped off from the -tourist steamers to bestow any special study upon it. -But during this latter season Mr. Muir returned to the -scene of his discovered wonder, and spent some weeks in -exploring the interior of the great ice-field. During the -same season, also, Professors H. F. Reid and H. Cushing, -with a well-equipped party of young men, spent two -months or more in the same field, conducting observations -and experiments, of various kinds, relating to the -extent, the motion, and the general behaviour of the vast -mass of moving ice.</p> - -<div class="fig_center" style="width: 378px;"> -<a id="fig13" name="fig13"></a> -<img src="images/fig_13.png" width="378" height="322" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 13.</span>—Shows central part of the front of Muir Glacier one half mile distant. -Near the lower left hand corner the ice is seen one mile distant resting for -about one half mile on gravel which it had overrun. The ice is now retreating -in the channel. (From photograph.)</div> -</div> - -<p>The main body of the Muir Glacier occupies a vast -<span class="pagenum"><a name="Page_27" id="Page_27">« 27 »</a></span> -amphitheatre, with diameters ranging from thirty to forty -miles, and covers an area of about one thousand square -miles. From one of the low mountains near its mouth I -could count twenty-six tributary glaciers which came together -and became confluent in the main stream of ice. -Nine medial moraines marked the continued course of as -many main branches, which becoming united formed the -grand trunk of the glacier. Numerous rocky eminences -also projected above the surface of the ice, like islands in -the sea, corresponding to what are called “<i>nunataks</i>” in -Greenland. The force of the ice against the upper side -of these rocky prominences is such as to push it in great -masses above the surrounding level, after the analogy of -waves which dash themselves into foam against similar -obstructions. In front of the <i>nunataks</i> there is uniformly -a depression, like the eddies which appear in the -current below obstacles in running water.</p> - -<p>Over some portions of the surface of the glacier there -is a miniature river system, consisting of a main stream, -with numerous tributaries, but all flowing in channels of -deep blue ice. Before reaching the front of the glacier, -however, each one of these plunges down into a crevasse, -or <i>moulin</i>, to swell the larger current, which may be -heard rushing along in an impetuous course hundreds of -feet beneath, and far out of sight. The portion of the -glacier in which there is the most rapid motion is characterised -by innumerable crags and domes and pinnacles -of ice, projecting above the general level, whose bases are -separated by fissures, extending in many cases more than -a hundred feet below the general level. These irregularities -result from the combined effect of the differential -motion (as illustrated in the diagram on <a href="#Page_4">page 4</a>), and -the influence of sunshine and warm air in irregularly -melting the unprotected masses. The description given -in our introductory chapter of medial moraines and ice-pillars -is amply illustrated everywhere upon the surface -<span class="pagenum"><a name="Page_28" id="Page_28">« 28 »</a></span> -of the Muir Glacier. I measured one block of stone -which was twenty feet square and about the same height, -standing on a pedestal of ice three or four feet high.</p> - -<p>The mountains forming the periphery of this amphitheatre -rise to a height of several thousand feet; Mount -Fairweather, upon the northwest, from whose flanks probably -a portion of the ice comes, being, in fact, more than -fifteen thousand feet high. The mouth of the amphitheatre -is three miles wide, in a line extending from -shoulder to shoulder of the low mountains which guard -it. The actual water-front where the ice meets tide-water -is one mile and a half.<a name="FNanchor_35" id="FNanchor_35"></a><a href="#Footnote_35" class="fnanchor">[AI]</a> Here the depth of the inlet is -so great that the front of the ice breaks off in icebergs of -large size, which float away to be dissolved at their leisure. -At the water’s edge the ice presents a perpendicular front -of from two hundred and fifty to four hundred feet in -height, and the depth of the water in the middle of the -inlet immediately in front of the ice is upwards of seven -hundred feet; thus giving a total height to the precipitous -front of a thousand feet.</p> - -<div class="footnote"> - -<p><a name="Footnote_35" id="Footnote_35"></a><a href="#FNanchor_35"><span class="label">[AI]</span></a> These are the measurements of Professor Reid. In my former -volume I have given the dimensions as somewhat smaller.</p></div> - -<p>The formation of icebergs can here be studied to -admirable advantage. During the month in which we -encamped in the vicinity the process was going on continuously. -There was scarcely an interval of fifteen -minutes during the whole time in which the air was not -rent with the significant boom connected with the “calving” -of a berg. Sometimes this was occasioned by the -separation of a comparatively small mass of ice from near -the top of the precipitous wall, which would fall into the -water below with a loud splash. At other times I have -seen a column of ice from top to bottom of the precipice -split off and fall over into the water, giving rise to great -waves, which would lash the shore with foam two miles -below.</p> - -<p><span class="pagenum"><a name="Page_29" id="Page_29">« 29 »</a></span></p> - -<p>This manner of the production of icebergs differs -from that which has been ordinarily represented in the -text-books, but it conforms to the law of glacial motion, -which we will describe a little later, namely, that the -upper strata of ice move faster than the lower. Hence -the tendency is constantly to push the upper strata forwards, -so as to produce a perpendicular or even projecting -front, after the analogy of the formation of breakers on -the shelving shore of a large body of water.</p> - -<p>Evidently, however, these masses of ice which break -off from above the water do not reach the whole distance -to the bottom of the glacier below the water; so that a -projecting foot of ice remains extending to an indefinite -distance underneath the surface. But at occasional intervals, -as the superincumbent masses of ice above the -surface fall off and relieve the strata below of their weight, -these submerged masses suddenly rise, often shooting up -considerably higher than they ultimately remain when -coming to rest. The bergs formed by this latter process -often bear much earthy material upon them, which is -carried away with the floating ice, to be deposited finally -wherever the melting chances to take place.</p> - -<p>Numerous opportunities are furnished about the front -and foot of this vast glacier to observe the manner of the -formation of <i>kames</i>, kettle-holes, and various other irregular -forms into which glacial <i>débris</i> is accustomed to accumulate. -Over portions of the decaying foot of the -glacier, which was deeply covered with morainic <i>débris</i>, -the supporting ice is being gradually removed through the -influence of subglacial streams or of abandoned tunnels, -which permit the air to exert its melting power underneath. -In some places where old <i>moulins</i> had existed, the -supporting ice is melting away, so that the superincumbent -mass of sand, gravel, and boulders is slowly sliding into a -common centre, like grain in a hopper. This must produce -a conical hill, to remain, after the ice has all melted -<span class="pagenum"><a name="Page_30" id="Page_30">« 30 »</a></span> -away, a mute witness of the impressive and complicated -forces which have been so long in operation for its production.</p> - -<p>In other places I have witnessed the formation of a -long ridge of gravel by the gradual falling in of the roof -of a tunnel which had been occupied by a subglacial -stream, and over which there was deposited a great amount -of morainic material. As the roof gave way, this was -constantly falling to the bottom, where, being exempt -from further erosive agencies, it must remain as a gravel -ridge or kame.</p> - -<p>In other places, still, there were vast masses of ice -covering many acres, and buried beneath a great depth of -morainic material which had been swept down upon it -while joined to the main glacier. In the retreat of the -ice, however, these masses had become isolated, and the -sand, gravel, and boulders were sliding down the wasting -sides and forming long ridges of <i>débris</i> along the bottom, -which, upon the final melting of the ice, will be left as a -complicated network of ridges and knolls of gravel, enclosing -an equally complicated nest of kettle-holes.</p> - -<p>Beyond Cross Sound the Pacific coast is bounded for -several hundred miles by the magnificent semicircle of -mountains known as the St. Elias Alps, with Mount Crillon -at the south, having an elevation of nearly sixteen -thousand feet, and St. Elias in the centre, rising to a -greater height. Everywhere along this coast, as far as the -Alaskan Peninsula, vast glaciers come down from the -mountain-sides, and in many cases their precipitous fronts -form the shore-line for many miles at a time. Icy Bay, -just to the south of Mount St, Elias, is fitly named, on -account of the extent of the glaciers emptying into it and -the number of icebergs cumbering its waters.</p> - -<p>In the summer of 1890 a party, under the lead of Mr. -I. C. Russell, of the United States Geological Survey, -made an unsuccessful attempt to scale the heights of -<span class="pagenum"><a name="Page_31" id="Page_31">« 31 »</a></span> -Mount St. Elias; but the information brought back by -them concerning the glaciers of the region amply repaid -them for their toil and expense, and consoled them for -the failure of their immediate object.</p> - -<div class="fig_center" style="width: 358px;"> -<a id="fig14" name="fig14"></a> -<img src="images/fig_14.png" width="358" height="360" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 14.</span>—By the courtesy of the National Geographical Society.</div> -</div> - -<p>Leaving Yakutat Bay, and following the route indicated -upon the accompanying map, they travelled on glacial -ice almost the entire distance to the foot of Mount -St. Elias. The numerous glaciers coming down from the -summit of the mountain-ridge become confluent nearer -the shore, and spread out over an area of about a thousand -square miles. This is fitly named the Malaspina Glacier, -after the Spanish explorer who discovered it in 1792.</p> - -<p>It is not necessary to add further particulars concerning -<span class="pagenum"><a name="Page_32" id="Page_32">« 32 »</a></span> -the results of this expedition, since they are so similar -to those already detailed in connection with the Muir -Glacier. A feature, however, of special interest, pertains -to the glacial lakes which are held in place by the glacial -ice at an elevation of thousands of feet above the sea. One -of considerable size is indicated upon the map just south -of what was called Blossom Island, which, however, is not -an island, but simply a <i>nunatak</i>, the ice here surrounding -a considerable area of fertile land, which is covered with -dense forests and beautified by a brilliant assemblage of -flowering plants. In other places considerable vegetation -was found upon the surface of moraines, which were probably -still in motion with the underlying ice.</p> - -<p><i>Greenland.</i>—The continental proportions of Greenland, -and the extent to which its area is covered by glacial -ice, make it by far the most important accessible field for -glacial observations. The total area of Greenland can not -be less than five hundred thousand square miles—equal in -extent to the portion of the United States east of the Mississippi -and north of the Ohio. It is now pretty evident -that the whole of this area, except a narrow border about -the southern end, is covered by one continuous sheet of -moving ice, pressing outward on every side towards the -open water of the surrounding seas.</p> - -<p>For a long time it was the belief of many that a large -region in the interior of Greenland was free from ice, and -was perhaps inhabited. It was in part to solve this problem -that Baron Nordenskiöld set out upon his expedition -of 1883. Ascending the ice-sheet from Disco Bay, in -latitude 69°, he proceeded eastward for eighteen days -across a continuous ice-field. Rivers were flowing in -channels upon the surface like those cut on land in horizontal -strata of shale or sandstone, only that the pure deep -blue of the ice-walls was, by comparison, infinitely more -beautiful. These rivers were not, however, perfectly continuous. -After flowing for a distance in channels on the -surface, they, one and all, plunged with deafening roar -into some yawning crevasse, to find their way to the sea -through subglacial channels. Numerous lakes with shores -of ice were also encountered.</p> - -<p><span class="pagenum"><a name="Page_33" id="Page_33">« 33 »</a></span></p> - -<div class="fig_center" style="width: 578px;"> -<a id="fig15" name="fig15"></a> -<img src="images/fig_15.png" width="578" height="394" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 15.</span>—Map of Greenland. The arrow-points mark the margin of the ice-field.</div> -</div> - -<p><span class="pagenum"><a name="Page_34" id="Page_34">« 34 »</a></span></p> - -<p>“On bending down the ear to the ice,” says this explorer, -“we could hear on every side a peculiar subterranean -hum, proceeding from rivers flowing within the -ice; and occasionally a loud, single report, like that of a -cannon, gave notice of the formation of a new glacier-cleft.... -In the afternoon we saw at some distance from -us a well-defined pillar of mist, which, when we approached -it, appeared to rise from a bottomless abyss, into which a -mighty glacier-river fell. The vast, roaring water-mass -had bored for itself a vertical hole, probably down to the -rock, certainly more than two thousand feet beneath, on -which the glacier rested.”<a name="FNanchor_36" id="FNanchor_36"></a><a href="#Footnote_36" class="fnanchor">[AJ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_36" id="Footnote_36"></a><a href="#FNanchor_36"><span class="label">[AJ]</span></a> Geological Magazine, vol. ix, pp. 393, 399.</p></div> - -<p>At the end of the eighteen days Nordenskiöld found -himself about a hundred and fifty miles from his starting-point, -and about five thousand feet above the sea. Here -the party rested, and sent two Eskimos forward on <i>skidor</i>—a -kind of long wooden skate, with which they could -move rapidly over the ice, notwithstanding the numerous -small, circular holes which everywhere pitted the surface. -These Eskimos were gone fifty-seven hours, having slept -only four hours of the period. It is estimated that they -made about a hundred and fifty miles, and attained an -altitude of six thousand feet. The ice is reported as rising -in distinct terraces, and as seemingly boundless beyond. -If this is the case, two hundred miles from Disco Bay, -there would seem little hope of finding in Greenland an -interior freed from ice. So we may pretty confidently -speak of that continental body of land as still enveloped -in an ice-sheet. Up to about latitude 75°, however, the -continent is fringed by a border of islands, over which -<span class="pagenum"><a name="Page_35" id="Page_35">« 35 »</a></span> -there is no continuous covering of ice. In south Greenland -the continuous ice-sheet is reached about thirty miles -back from the shore.</p> - -<p>A summary of the results of Greenland exploration -was given by Dr. Kink in 1886, from which it appears -that since 1876 one thousand miles of the coast-line have -been carefully explored by entering every fiord and attempting -to reach the inland ice. According to this authority—</p> - -<p>We are now able to demonstrate that a movement of -ice from the central regions of Greenland to the coast -continually goes on, and must be supposed to act upon -the ground over which it is pushed so as to detach and -transport fragments of it for such a distance.... The -plainest idea of the ice-formation here in question is given -by comparing it with an inundation.... Only the marginal -parts show irregularity; towards the interior the surface -grows more and more level and passes into a plain -very slightly rising in the same direction. It has been -proved that, ascending its extreme verge, where it has -spread like a lava-stream over the lower ground in front -of it, the irregularities are chiefly met with up to a height -of 2,000 feet, but the distance from the margin in which -the height is reached varies much. While under 68<span class="horsplit"><span class="top">1</span><span class="bottom trt">2</span></span>° -north latitude it took twenty-four miles before this elevation -was attained, in 72<span class="horsplit"><span class="top">1</span><span class="bottom trt">2</span></span>° the same height was arrived -at in half the distance....</p> - -<p>A general movement of the whole mass from the central -regions towards the sea is still continued, but it concentrates -its force to comparatively few points in the most -extraordinary degree. These points are represented by -the ice-fiords, through which the annual surplus ice is -carried off in the shape of bergs.... In Danish Greenland -are found five of the first, four of the second, and -eight of the third (or least productive) class, besides a -number of inlets which only receive insignificant fragments. -<span class="pagenum"><a name="Page_36" id="Page_36">« 36 »</a></span> -Direct measurements of the velocity have now -been applied on three first-rate and one second-rate fiords, -all situated between 69° and 71° north latitude. The -measurements have been repeated during the coldest and -the warmest season, and connected with surveying and -other investigations of the inlets and their environs. It -is now proved that the glacier branches which produce -the bergs proceed incessantly at a rate of thirty to fifty -feet per diem, this movement being not at all influenced -by the seasons. . . .</p> - -<p>In the ice-fiord of Jakobshavn, which spreads its enormous -bergs over Disco Bay and probably far into the Atlantic, -the productive part of the glacier is 4,500 metres -(about 2<span class="horsplit"><span class="top">1</span><span class="bottom trt">2</span></span> miles) broad. The movement along its middle -line, which is quicker than on the sides nearer the shores, -can be rated at fifty feet per diem. The bulk of ice here -annually forced into the sea would, if taken on the shore, -make a mountain two miles long, two miles broad, and -1,000 feet high. The ice-fiord of Torsukatak receives -four or five branches of the glacier; the most productive -of them is about 9,000 metres broad (five miles), and -moves between sixteen and thirty-two feet per diem. The -large Karajak Glacier, about 7,000 metres (four miles) -broad, proceeds at a rate of from twenty-two to thirty-eight -feet per diem. Finally, a glacier branch dipping -into the fiord of Jtivdliarsuk, 5,800 metres broad (three -miles), moved between twenty-four and forty-six feet per -diem.<a name="FNanchor_37" id="FNanchor_37"></a><a href="#Footnote_37" class="fnanchor">[AK]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_37" id="Footnote_37"></a><a href="#FNanchor_37"><span class="label">[AK]</span></a> See Transactions of the Edinburgh Geological Society for February -18, 1886, vol. v, part ii, pp. 286-293.</p></div> - -<p>The principal part of our information concerning the -glaciers of Greenland north of Melville Bay was obtained -by Drs. Kane and Hayes, in 1853 and 1854, while conducting -an expedition in search of Sir John Franklin and -his unfortunate crew. Dr. Hayes conducted another expedition -<span class="pagenum"><a name="Page_37" id="Page_37">« 37 »</a></span> -to the same desolate region in 1860, while other -explorers have to some extent supplemented their observations. -The largest glacier which they saw enters the -sea between latitude 79° and 80°, where it presents a precipitous -discharging front more than sixty miles in width -and hundreds of feet in perpendicular height.</p> - -<p>Dr. Kane gives his first impressions of this grand glacier -in the following vivid description:</p> - -<p>“I will not attempt to do better by florid description. -Men only rhapsodize about Niagara and the ocean. My -notes speak simply of the ‘long, ever-shining line of cliff -diminished to a well-pointed wedge in the perspective’; -and, again, of ‘the face of glistening ice, sweeping in a -long curve from the low interior, the facets in front intensely -illuminated by the sun.’ But this line of cliff -rose in a solid, glassy wall three hundred feet above the -water-level, with an unknown, unfathomable depth below -it; and its curved face, sixty miles in length from Cape -Agassiz to Cape Forbes, vanished into unknown space at -not more than a single day’s railroad-travel from the pole. -The interior, with which it communicated and from -which it issued, was an unsurveyed <i>mer de glace</i>—an ice-ocean -to the eye, of boundless dimensions.</p> - -<p>“It was in full sight—the mighty crystal bridge which -connects the two continents of America and Greenland. -I say continents, for Greenland, however insulated it may -ultimately prove to be, is in mass strictly continental. Its -least possible axis, measured from Cape Farewell to the -line of this glacier, in the neighbourhood of the eightieth -parallel, gives a length of more than 1,200 miles, not materially -less than that of Australia from its northern to its -southern cape.</p> - -<p>“Imagine, now, the centre of such a continent, occupied -through nearly its whole extent by a deep, unbroken -sea of ice that gathers perennial increase from the water-shed -of vast snow-covered mountains and all the precipitations -<span class="pagenum"><a name="Page_38" id="Page_38">« 38 »</a></span> -of its atmosphere upon its own surface. Imagine -this, moving onwards like a great glacial river, seeking -outlets at every fiord and valley, rolling icy cataracts into -the Atlantic and Greenland seas; and, having at last -reached the northern limit of the land that has borne it -up, pouring out a mighty frozen torrent into unknown -arctic space!</p> - -<p>“It is thus, and only thus, that we must form a just -conception of a phenomenon like this great glacier. I -had looked in my own mind for such an appearance, -should I ever be fortunate enough to reach the northern -coast of Greenland; but, now that it was before me, I -could hardly realize it. I had recognized, in my quiet -library at home, the beautiful analogies which Forbes and -Studer have developed between the glacier and the river. -But I could not comprehend at first this complete substitution -of ice for water.</p> - -<p>“It was slowly that the conviction dawned on me that -I was looking upon the counterpart of the great river-system -of Arctic Asia and America. Yet here were no -water-feeders from the south. Every particle of moisture -had its origin within the polar circle and had been converted -into ice. There were no vast alluvions, no forest -or animal traces borne down by liquid torrents. Here -was a plastic, moving, semi-solid mass, obliterating life, -swallowing rocks and islands, and ploughing its way with -irresistible march through the crust of an investing sea.”<a name="FNanchor_38" id="FNanchor_38"></a><a href="#Footnote_38" class="fnanchor">[AL]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_38" id="Footnote_38"></a><a href="#FNanchor_38"><span class="label">[AL]</span></a> Arctic Explorations in the Years 1853, 1854, and 1855, vol. i, -pp. 225-228.</p></div> - -<p>Much less is known concerning the eastern coast of -Greenland than about the western coast. For a long time -it was supposed that there might be a considerable population -in the lower latitudes along the eastern side. But -that is now proved to be a mistake. The whole coast is -very inhospitable and difficult of approach. From latitude -<span class="pagenum"><a name="Page_39" id="Page_39">« 39 »</a></span> -65° to latitude 69° little or nothing is known of it. -In 1822-’23 Scoresby, Cleavering, and Sabine hastily explored -the coast from latitude 69° to 76°, and reported -numerous glaciers descending to the sea-level through -extensive fiords, from which immense icebergs float out -and render navigation dangerous. In 1869 and 1870 the -second North-German Expedition partly explored the -coast between latitude 73° and 77°. Mr. Payer, an experienced -Alpine explorer, who accompanied the expedition, -reports the country as much broken, and the glaciers -as “subordinated in position to the higher peaks, and having -their moraines, both lateral and terminal, like those -of the Alpine ranges, and on a still grander scale.” Petermann -Peak, in latitude 73°, is reported as 13,000 feet -high. Captain Koldewey, chief of the expedition, found -extensive plateaus on the mainland, in latitude 75°, to be -“entirely clear of snow, although only sparsely covered with -vegetation.” The mountains in this vicinity, also, rising -to a height of more than 2,000 feet, were free from snow -in the summer. Some of the fiords in this vicinity penetrate -the continent through several degrees of longitude.</p> - -<p>An interesting episode of this expedition was the experience -of the crew of the ship Hansa, which was caught -in the ice and destroyed. The crew, however, escaped by -encamping on the ice-floe which had crushed the ship. -From this, as it slowly floated towards the south through -several degrees of latitude, they had opportunity to make -many important observations upon the continent itself. -As viewed from this unique position the coast had the appearance -everywhere of being precipitous, with mountains -of considerable height rising in the background, from -which numerous small glaciers descended to the sea-level.</p> - -<p>In 1888 Dr. F. Nansen, with Lieutenant Sverdrup and -four others, was left by a whaler on the ice-pack bordering -the east of Greenland about latitude 65°, and in sight -of the coast. For twelve days the party was on the ice-pack -<span class="pagenum"><a name="Page_40" id="Page_40">« 40 »</a></span> -floating south, and so actually reached the coast only -about latitude 64°. From this point they attempted to -cross the inland ice in a northwesterly direction towards -Christianshaab. They soon reached a height of 7,000 -feet, and were compelled by severe northerly storms to -diverge from their course, taking a direction more to the -west. The greatest height attained was 9,500 feet, and -the party arrived on the western coast at Ameralik Fiord, -a little south of Godhaab, about the same latitude at which -they entered.</p> - -<p>It thus appears that subsequent investigations have -confirmed in a remarkable manner the sagacious conclusions -made by the eminent Scotch geologist and glacialist -Robert Brown in 1875, soon after his own expedition to -the country. “I look upon Greenland and its interior -ice-field,” he writes, "in the light of a broad-lipped, -shallow vessel, but with chinks in the lips here and -there, and the glacier like viscous matter in it. As -more is poured in, the viscous matter will run over the -edges, naturally taking the line of the chinks as its line -of outflow. The broad lips of the vessel are the outlying -islands or ‘outskirts’; the viscous matter in the vessel -the inland ice, the additional matter continually being -poured in in the form of the enormous snow covering, -which, winter after winter, for seven or eight months in -the year, falls almost continuously on it; the chinks are -the fiords or valleys down which the glaciers, representing -the outflowing viscous matter, empty the surplus of -the vessel—in other words, the ice floats out in glaciers, -overflows the land in fact, down the valleys and fiords of -Greenland by force of the superincumbent weight of snow, -just as does the grain on the floor of a barn (as admirably -described by Mr. Jamieson) when another sackful is emptied -on the top of the mound already on the floor. ‘The -floor is flat, and therefore does not conduct the grain in -any direction; the outward motion is due to the pressure -<span class="pagenum"><a name="Page_41" id="Page_41">« 41 »</a></span> -of the particles of grain on one another; and, given a -floor of infinite extension and a pile of sufficient amount, -the mass would move outward to any distance, and with a -very slight pitch or slope it would slide forward along the -incline.’ To this let me add that if the floor on the margin -of the heap of grain was undulating the stream of -grain would take the course of such undulations. The -want, therefore, of much slope in a country and the absence -of any great mountain-range are of very little moment -to the movement of land-ice, <i>provided we have snow -enough</i>" On another page Dr. Brown had well said that -“the country seems only a circlet of islands separated -from one another by deep fiords or straits, and bound together -on the landward side by the great ice covering -which overlies the whole interior.... No doubt under -this ice there lies land, just as it lies under the sea; but -nowadays none can be seen, and as an insulating medium -it might as well be water.”</p> - -<p>In his recently published volumes descriptive of the -journey across the Greenland ice-sheet, alluded to on <a href="#Page_39">page 39</a>, -Dr. Nansen sums up his inferences in very much the -same way: “The ice-sheet rises comparatively abruptly -from the sea on both sides, but more especially on the -east coast, while its central portion is tolerably flat. On -the whole, the gradient decreases the farther one gets into -the interior, and the mass thus presents the form of a -shield with a surface corrugated by gentle, almost imperceptible, -undulations lying more or less north and south, -and with its highest point not placed symmetrically, but -very decidedly nearer the east coast than the west.”</p> - -<p>From this rapid glance at the existing glaciers of the -world we see that a great ice age is not altogether a -strange thing in the world. The lands about the south -pole and Greenland are each continental in dimensions, -and present at the present time accumulations of land-ice -so extensive, so deep, and so alive with motion as to prepare -<span class="pagenum"><a name="Page_42" id="Page_42">« 42 »</a></span> -our minds for almost anything that may be suggested -concerning the glaciated condition of other portions of -the earth’s surface. The <i>vera causa</i> is sufficient to accomplish -anything of which glacialists have ever dreamed. It -only remains to enquire what the facts really are and over -how great an extent of territory the actual results of glacial -action may be found. But we will first direct more -particular attention to some of the facts and theories concerning -glacial motion.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_43" id="Page_43">« 43 »</a></span></p> - - - - -<p class="caption2"><a name="CHAPTER_III" id="CHAPTER_III">CHAPTER III.</a></p> - -<p class="caption2">GLACIAL MOTION.</p> - - -<p>That glacial ice actually moves after the analogy of a -semi-fluid has been abundantly demonstrated by observation. -In the year 1827 Professor Hugi, of Soleure, built -a hut far up upon the Aar Glacier in Switzerland, in -order to determine the rate of its motion. After three -years he found that it had moved 330 feet; after nine -years, 2,354 feet; and after fourteen -years Louis Agassiz found that its -motion had been 4,712 feet. In 1841 -Agassiz began a more accurate series -of observation upon the same glacier. -Boring holes in the ice, he set across -it a row of stakes which, on visiting -in 1842, he found to be no longer in -a straight line. All had moved downwards -with varying velocity, those -near the centre having moved farther than the others. -The displacements of the stakes were in order, from side -to side, as follows: 160 feet, 225 feet, 269 feet, 245 feet, -210 feet, and 125 feet. Agassiz followed up his observations -for six years, and in 1847 published the results in -his celebrated work System Glacière.</p> - -<div class="fig_right" style="width: 126px;"> -<a id="fig16" name="fig16"></a> -<img src="images/fig_16.png" width="126" height="147" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 16.</span></div> -</div> - -<p>But in August, 1841, the distinguished Swiss investigator -had invited Professor J. D. Forbes, of Edinburgh, to -interest himself in solving the problem of glacial motion. -In response to this request, Professor Forbes spent three -weeks with Agassiz upon the Aar Glacier. Stimulated -<span class="pagenum"><a name="Page_44" id="Page_44">« 44 »</a></span> -by the interest of this visit, Forbes returned to Switzerland -in 1842 and began a series of independent investigations -upon the Mer de Glace. After a week’s observations -with accurate instruments, Forbes wrote to Professor -Jameson, editor of the Edinburgh New Philosophical -Journal, that he had already made it certain that “the -central part of the glacier moves faster than the edges in -a very considerable proportion, quite contrary to the -opinion generally maintained.” This letter was dated -July 4, 1842, but was not published until the October following, -Agassiz’s results, so far as then determined, were, -however, published in Comptes Rendus of the 29th of -August, 1842, two months before the publication of -Forbes’s letter. But Agassiz’s letter was dated twenty-seven -days later than that of Forbes. It becomes certain, -therefore, that both Agassiz and Forbes, independently -and about the same time, discovered the fact that the -central portion of a glacier moves more rapidly than the -sides.</p> - -<p>In 1857 Professor Tyndall began his systematic and -fruitful observations upon the Mer de Glace and other -Alpine glaciers. Professor Forbes had already demonstrated -that, with an accurate instrument of observation, -the motion of a line of stakes might be observed after -the lapse of a single clay, or even of a few hours. As -a result of Tyndall’s observations, it was found that -the most rapid daily motion in the Mer de Glace in 1857 -was about thirty-seven inches. This amount of motion -was near the lower end of the glacier On ascending the -glacier, the rate was found in general to be diminished; -but the diminution was not uniform throughout the -whole distance, being affected both by the size and by the -contour of the valley. The motion in the tributary glaciers -was also much less than that of the main glacier.</p> - -<p>This diminution of movement in the tributary glaciers -was somewhat proportionate to their increase in width. -<span class="pagenum"><a name="Page_45" id="Page_45">« 45 »</a></span> -For example, the combined width of the three tributaries -uniting to form the Mer de Glace is 2,597 yards; but a -short distance below the junction of these tributaries the -total width of the Mer de Glace itself is only 893 yards, -or one-third that of the tributaries combined. Yet, though -the depth of the ice is probably here much greater than in -the tributaries, the rapidity of movement is between two -and three times as great as that of any one of the branches.<a name="FNanchor_39" id="FNanchor_39"></a><a href="#Footnote_39" class="fnanchor">[AM]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_39" id="Footnote_39"></a><a href="#FNanchor_39"><span class="label">[AM]</span></a> See Tyndall’s Forms of Water, pp. 78-82.</p></div> - -<p>From Tyndall’s observations it appears also that the -line of most rapid motion is not exactly in the middle of -the channel, but is pushed by its own momentum from -one side to the other of the middle, so -as always to be nearer the concave side; -in this respect conforming, as far as its -nature will permit, to the motion of -water in a tortuous channel.</p> - -<div class="fig_right" style="width: 108px;"> -<a id="fig17" name="fig17"></a> -<img src="images/fig_17.png" width="108" height="256" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 17.</span></div> -</div> - -<p>It is easy to account for this differential -motion upon the surface of a glacier, -since it is clear that the friction of the -sides of the channel must retard the motion -of ice as it does that of water. It -is clear also that the friction of the bottom -must retard the motion of ice even -more than it is known to do in the case -of water. In the formation of breakers, -when the waves roll in upon a shallowing -beach, every one is familiar with the -effect of the bottom upon the moving mass. Here friction -retards the lower strata of water, and the upper strata -slide over the lower, and, where the water is of sufficient -depth and the motion is sufficiently great, the crest breaks -down in foam before the ever-advancing tide. A similar -phenomenon occurs when dams give way and reservoirs -suddenly pour their contents into the restricted channels -<span class="pagenum"><a name="Page_46" id="Page_46">« 46 »</a></span> -below. At such times the advancing water rolls onwards -like the surf with a perpendicular front, varying in height -according to the extent of the flood.</p> - -<p>Seasoning from these phenomena connected with moving -water, it was naturally suggested to Professor Tyndall -that an analogous movement must take place in a glacier. -Choosing, therefore, a favourable place for observation on -the Mer de Glace where the ice emerged from a gorge, he -found a perpendicular side about one hundred and fifty -feet in height from bottom to top. In this face he drove -stakes in a perpendicular line from top to bottom. Upon -subsequently observing -them, Tyndall found, -as he expected, that -there was a differential -motion among them as -in the stakes upon the -surface. The retarding -effect of friction upon -the bottom was evident. The stake near the top moved -forwards about three times as fast as the one which was -only four feet from the bottom.</p> - -<div class="fig_left" style="width: 223px;"> -<a id="fig18" name="fig18"></a> -<img src="images/fig_18.png" width="223" height="104" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 18.</span></div> -</div> - -<p>The most rapid motion (thirty-seven inches per day) -observed by Professor Tyndall upon the Alpine glaciers -occurred in midsummer. In winter the rate was only -about one-half as great; but in the year 1875 the Norwegian -geologist, Helland, reported a movement of twenty -metres (about sixty-five feet) per day in the Jakobshavn -Glacier which enters Disco Bay, Greenland, about latitude -70°. For some time there was a disposition on the part -of many scientific men to doubt the correctness of Holland’s -calculations. Subsequent observations have shown, -however, that from the comparatively insignificant glaciers -of the Alps they were not justified in drawing inferences -with respect to the motion of the vastly larger masses -which come down to the sea through the fiords of Greenland. -<span class="pagenum"><a name="Page_47" id="Page_47">« 47 »</a></span> -The Jakobshavn Glacier was about two and a half -miles in width and its depth very likely more than a thousand -feet, making a cross-section of more than 1,400,000 -square yards, whereas the cross-section of the Mer de -Glace at Montanvert is estimated to be but 190,000 square -yards or only about one-seventh the above estimate for -the Greenland glacier. As the friction of the sides -would be no greater upon a large stream than upon a -small one, while upon the bottom it would be only in proportion -to the area, it is evident that we cannot tell beforehand -how rapidly an increase in the volume of the -ice might augment the velocity of the glacier.</p> - -<p>At any rate, all reasonable grounds for distrusting the -accuracy of Helland’s estimates seem to have been removed -by later investigations. According to my own observations -in the summer of 1886 upon the Muir Glacier, -Alaska, the central portions, a mile back from the front -of that vast ice-current, were moving from sixty-five to -seventy feet per day. These observations were taken with -a sextant upon pinnacles of ice recognizable from a baseline -established upon the shore. It is fair to add, however, -that during the summer of 1890 Professor H. F. -Reid attempted to measure the motion of the same glacier -by methods promising greater accuracy than could be obtained -by mine. He endeavoured to plant, after the method -of Tyndall, a line of stakes across the ice-current. But -with his utmost efforts, working inwards from both sides, -he was unable to accomplish his purpose, and so left unmeasured -a quarter of a mile or more of the most rapidly-moving -portion of the glacier. His results, therefore, of -ten feet per day in the most rapidly-moving portion observed -cannot discredit my own observations on a portion -of the stream inaccessible by his method. A quarter of a -mile in width near the centre of so vast a glacier gives -ample opportunity for a much greater rate of motion than -that observed by Professor Reid. Especially may this be -<span class="pagenum"><a name="Page_48" id="Page_48">« 48 »</a></span> -true in view of Tyndall’s suggestion that the contour of -the bottom over which the ice flows may greatly affect the -rate in certain places. A sudden deepening of the channel -may affect the motion of ice in a glacier as much as it -does that of water in a river.</p> - -<p>Other observations also amply sustain the conclusions -of Helland. As already stated, the Danish surveying party -under Steenstrup, after several years’ work upon the southwestern -coast of Greenland, have ascertained that the numerous -glaciers coming down to the sea in that region and -furnishing the icebergs incessantly floating down Baffin’s -Bay, move at a rate of from thirty to fifty feet per day, -while Lieutenants Ryder and Bloch, of the Danish Navy, -who spent the year 1887 in exploring the coast in the -vicinity of Upernavik, about latitude 73°, found that the -great glacier entering the fiord east of the village had a -velocity of ninety-nine feet per day during the month of -August.<a name="FNanchor_40" id="FNanchor_40"></a><a href="#Footnote_40" class="fnanchor">[AN]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_40" id="Footnote_40"></a><a href="#FNanchor_40"><span class="label">[AN]</span></a> Nature, December 29, 1887.</p></div> - -<p>It is easier to establish the fact of glacial motion than -to explain how the motion takes place, for ice seems to be -as brittle as glass. This, however, is true of it only when -compelled suddenly to change its form. When subjected -to slow and long-continued pressure it gradually yet readily -yields, and takes on new forms. From this capacity of -ice, it has come to be regarded by some as a really viscous -substance, like tar or cooling lava, and upon that theory -Professor Forbes endeavours to explain all glacial movement.</p> - -<p>The theory, however, seems to be contradicted by familiar -facts; for the iceman, after sawing a shallow groove -across a piece of ice, can then split it as easily as he would -a piece of sandstone or wood. On the glaciers themselves, -likewise, the existence of innumerable crevasses would -seem to contradict the plastic theory of glacier motion;<span class="pagenum"><a name="Page_49" id="Page_49">« 49 »</a></span> -for, wherever the slope of the glacier’s bed increases, crevasses -are formed by the increased strain to which the ice -is subjected. Crevasses are also formed in rapidly-moving -glaciers by the slight strain occasioned by the more rapid -motion of the middle portion. Still, in the words of Tyndall, -“it is undoubted that the glacier moves like a viscous -body. The centre flows past the sides, the top flows over -the bottom, and the motion through a curved valley corresponds -to fluid motion.”<a name="FNanchor_41" id="FNanchor_41"></a><a href="#Footnote_41" class="fnanchor">[AO]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_41" id="Footnote_41"></a><a href="#FNanchor_41"><span class="label">[AO]</span></a> Forms of Water, p. 163.</p></div> - -<p>To explain this combination of the seemingly contradictory -qualities of brittleness and viscosity in ice, physicists -have directed attention to the remarkable transformations -which take place in water at the freezing-point. -Faraday discovered in 1850 that "when two pieces of -thawing ice are placed together they freeze together at the -point of contact.<a name="FNanchor_42" id="FNanchor_42"></a><a href="#Footnote_42" class="fnanchor">[AP]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_42" id="Footnote_42"></a><a href="#FNanchor_42"><span class="label">[AP]</span></a> Ibid., p. 164.</p></div> - -<p>“Place a number of fragments of ice in a basin of -water and cause them to touch each other; they freeze -together where they touch. You can form a chain of -such fragments; and then, by taking hold of one end of -the chain, you can draw the whole series after it. Chains -of icebergs are sometimes formed in this way in the arctic -seas.”<a name="FNanchor_43" id="FNanchor_43"></a><a href="#Footnote_43" class="fnanchor">[AQ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_43" id="Footnote_43"></a><a href="#FNanchor_43"><span class="label">[AQ]</span></a> Ibid., pp. 164, 165.</p></div> - -<p>This is really what takes place when a hard snow-ball -is made by pressure in the hand. So, by subjecting fragments -of ice to pressure it is first crumbled to powder, -and then, as the particles are pressed together in close -contact, it resumes the nature of ice again, though in a -different form, taking now the shape of the mould in -which it has been pressed.</p> - -<p>Thus it is supposed that, when the temperature of ice -is near the melting-point, the pressure of the superincumbent -mass may produce at certain points insensible disintegration, -while, upon the removal of the pressure by -<span class="pagenum"><a name="Page_50" id="Page_50">« 50 »</a></span> -change of position, regulation instantly takes place, and -thus the phenomena which simulate plasticity are produced. -As the freezing-point of water is, within a narrow -range, determined by the amount of pressure to which it -is subjected, it is not difficult to see how these changes -may occur. Pressure slightly lowers the freezing-point, -and so would liquefy the portions of ice subjected to greatest -pressure, wherever that might be in the mass of the -glacier, and thus permit a momentary movement of the -particles, until they should recongeal in adjusting themselves -to spaces of less pressure.<a name="FNanchor_44" id="FNanchor_44"></a><a href="#Footnote_44" class="fnanchor">[AR]</a> This is the theory by -which Professor James Thompson would account for the -apparent plasticity of glacial ice.</p> - -<div class="footnote"> - -<p><a name="Footnote_44" id="Footnote_44"></a><a href="#FNanchor_44"><span class="label">[AR]</span></a> Forms of Water, p. 168.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_51" id="Page_51">« 51 »</a></span></p></div> - - - - -<p class="caption2"><a name="CHAPTER_IV" id="CHAPTER_IV">CHAPTER IV.</a></p> - -<p class="caption2">SIGNS OF PAST GLACIATION.</p> - - -<p>The facts from which we draw the inference that vast -areas of the earth’s surface which are now free from glaciers -were, at a comparatively recent time, covered with -them, are fourfold, and are everywhere open to inspection. -These facts are: 1. Scratches upon the rocks. 2. Extensive -unstratified deposits of clay and sand intermingled -with scratched stones and loose fragments of rock. 3. -Transported boulders left in such positions and of such -size as to preclude the sufficiency of water-carriage to -account for them. 4. Extensive gravel terraces bordering -the valleys which emerge from the glaciated areas. We -will consider these in their order:</p> - -<p>1. The scratches upon the rocks.</p> - -<p>Almost anywhere in the region designated as having -been covered with ice during the Glacial period, the surface -of the rocks when freshly uncovered will be found to -be peculiarly marked by grooves and scratches more or -less fine, and such as could not be produced by the action -of water. But, when we consider the nature of a glacier, -these marks seem to be just what would be produced -by the pushing or dragging along of boulders, pebbles, -gravel, and particles of sand underneath a moving mass -of ice.</p> - -<p>Running water does indeed move gravel, pebbles, and -boulders along with the current, but these objects are not -held by it in a firm grasp, such as is required to make a -groove or scratch in the rock. If, also, there are inequalities -<span class="pagenum"><a name="Page_52" id="Page_52">« 52 »</a></span> -in the compactness or hardness of the rock, the -natural action of running water is to hollow out the soft -parts, and leave the harder parts projecting. But, in the -phenomena which we are attributing to glacial action, -there has been a movement which has steadily planed -down the surface of the underlying rock; polishing it, -indeed, but also grooving it and scratching it in a manner -which could be accomplished only by firmly held -graving-tools.</p> - -<div class="fig_center" style="width: 389px;"> -<a id="fig19" name="fig19"></a> -<img src="images/fig_19.png" width="389" height="420" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 19.</span>—Bed-rock scored with glacial marks, near Amherst, Ohio. (From a photograph -by Chamberlin.)</div> -</div> - -<p>This polishing and scratching can indeed be produced -<span class="pagenum"><a name="Page_53" id="Page_53">« 53 »</a></span> -by various agencies; as, for example, by the forces which -fracture the earth’s crust, and shove one portion past -another, producing what is called a <i>slicken-side</i>. Or, -again, avalanches or land-slides might be competent to -produce the results over limited and peculiarly situated -areas. Icebergs, also, and shore ice which is moved backwards -and forwards by the waves, would produce a certain -amount of such grooving and scratching. But the -phenomena to which we refer are so extensive, and occur -in such a variety of situations, that the movement of -glacial ice is alone sufficient to afford a satisfactory explanation. -Moreover, in Alaska, Greenland, Norway, -and Switzerland, and wherever else there are living -glaciers, it is possible to follow up these grooved and -striated surfaces till they disappear underneath the existing -glaciers which are now producing the phenomena. -Thus by its tracks we can, as it were, follow -this monster to its lair with as great certainty as we -could any animal with whose footprints we had become -familiar.</p> - -<p>2. The till, or boulder-clay.</p> - -<p>A second sign of the former existence of glaciers over -any area consists of an unstratified deposit of earthy -material, of greater or less depth, in which scratched -pebbles and fragments of rock occur without any definite -arrangement.</p> - -<p>Moving water is a most perfect sieve. During floods, -a river shoves along over its bed gravel and pebbles of -considerable size, whereas in time of low-water the current -may be so gentle as to transport nothing but fine -sand, and the clay will be carried still farther onwards, to -settle in the still water and form a delta about the river’s -mouth. The transporting capacity of running water is -in direct ratio to the sixth power of its velocity. Other -things being equal, if the velocity be doubled, the size of -the grains of sand or gravel which it transports is increased -<span class="pagenum"><a name="Page_54" id="Page_54">« 54 »</a></span> -sixty-four fold.<a name="FNanchor_45" id="FNanchor_45"></a><a href="#Footnote_45" class="fnanchor">[AS]</a> So frequent are the changes in -the velocity of running water, that the stratification of -its deposits is almost necessary and universal. If large -fragments of rocks or boulders are found embedded in -stratified clay, it is pretty surely a sign that they have -been carried to their position by floating ice. A small -mountain stream with great velocity may move a good-sized -boulder, while the Amazon, with its mighty but -slow-moving current, would pass by it forever without -<span class="pagenum"><a name="Page_55" id="Page_55">« 55 »</a></span> -stirring it from its position. But the vast area which is -marked in our map as having been covered with ice during -the Glacial period is characterised by deep and extensive -<span class="pagenum"><a name="Page_56" id="Page_56">« 56 »</a></span> -deposits of loose material devoid of stratification, and -composed of soil and rock gathered in considerable part -from other localities, and mixed in an indiscriminate -mass with material which has originated in the disintegration -of the underlying local strata.</p> - -<div class="footnote"> - -<p><a name="Footnote_45" id="Footnote_45"></a><a href="#FNanchor_45"><span class="label">[AS]</span></a> Le Conte’s Geology, p. 19.</p></div> - -<div class="fig_center" style="width: 408px;"> -<a id="fig20" name="fig20"></a> -<img src="images/fig_20.png" width="408" height="387" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 20.</span>—Scratched stone from the till of Boston. Natural size about one foot -and a half long by ten inches wide. (From photograph.)</div> -</div> - -<div class="fig_center" style="width: 333px;"> -<a id="fig21" name="fig21"></a> -<img src="images/fig_21.png" width="333" height="552" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 21.</span>—Typical section of till in Seattle. Washington State, about two hundred -feet above Puget Sound. This is on the height between the sound and Lake -Washington.</div> -</div> - -<div class="fig_center" style="width: 383px;"> -<a id="fig22" name="fig22"></a> -<img src="images/fig_22.png" width="383" height="72" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 22.</span>—Ideal section, showing how the till overlies the stratified rocks.</div> -</div> - -<div class="fig_center" style="width: 382px;"> -<a id="fig23" name="fig23"></a> -<img src="images/fig_23.png" width="382" height="243" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 23.</span>—Vessel Rock, a glacial boulder in Gilsum. N. H. (C. H. Hitchcock.)</div> -</div> - -<p>3. Transported boulders.</p> - -<p>Where there is a current of water deep enough to float -large masses of ice, there is scarcely any limit to the size -of boulders which may be transported upon them, or to -the distance to which the boulders may be carried and -dropped upon the bottom. The icebergs which break off -from the glaciers of Greenland may bear their burdens of -rock far down into the Atlantic, depositing them finally -amidst the calcareous ooze and the fine sediment from the -<span class="pagenum"><a name="Page_57" id="Page_57">« 57 »</a></span> -Gulf Stream which is slowly covering the area between -Northern America and Europe. Northern streams like -the St. Lawrence, which are deeply frozen over with ice -in the winter, and are heavily flooded as the ice breaks up -in the spring, afford opportunity for much transportation -of boulders in the direction of their current. In attributing -the transportation of a boulder to glacial ice, it is -necessary, therefore, to examine the contour of the country, -so as to eliminate from the problem the possibility of -the effects having been produced by floating ice.</p> - -<p>Another source of error against which one has to be -on his guard arises from the close resemblance of boulders -resulting from disintegration to those which have been -transported by ice from distant places. Owing to the -fact that large masses of rocks, especially those which are -crystalline, are seldom homogeneous in their structure, it -results that, under the slow action of disintegrating and -erosive agencies, the softer parts often are completely removed -before the harder nodules are sensibly affected, -and these may remain as a collection of boulders dotting -the surface. Such boulders are frequent in the granitic -regions of North Carolina and vicinity, where there has -been no glacial transportation. Several localities in Pennsylvania, -also, south of the line of glacial action as delineated -by Professor Lewis and myself, had previously -been supposed to contain transported boulders of large -size, but on examination they proved in all cases to be -resting upon undisturbed strata of the parent rock, and -were evidently the harder portions of the rock left in loco -by the processes of erosion spoken of. In New England, -also, it is possible that some boulders heretofore attributed -to ice-action may be simply the results of these processes -of disintegration and erosion. Whether they are or not -can usually be determined by their likeness or unlikeness -to the rocks on which they rest; but oftentimes, where a -particular variety of rock is exposed over a broad area, it -<span class="pagenum"><a name="Page_58" id="Page_58">« 58 »</a></span> -is difficult to tell whether a boulder has suffered any extensive -transportation or not.</p> - -<div class="fig_right" style="width: 238px;"> -<a id="fig24" name="fig24"></a> -<a href="images/fig_24_lrg.png"><img src="images/fig_24.png" width="238" height="235" alt="" /></a> -<div class="fig_caption"><span class="smcap">Fig. 24.</span>—Map showing the outline and course of -flow of the great Rhône Glacier (after Lyell).<br /> -Click on image to view larger sized.</div> -</div> - -<p>One of the most interesting and satisfactory demonstrations -of the distribution of boulders by glacial ice was -furnished by Guyot in Switzerland in 1845. His observations -and argument -will be most readily -understood by reference -to the accompanying -map, taken -from Lyell’s clear description.<a name="FNanchor_46" id="FNanchor_46"></a><a href="#Footnote_46" class="fnanchor">[AT]</a> -The Jura -Mountains are separated -from the Alps -by a valley, about -eighty miles in width, -which constitutes the -main habitable portion -of Switzerland, -and they rise upwards -of two thousand feet above it. But large Alpine boulders -are found as high as two thousand feet above the Lake -Neufchâtel upon the flanks of the Jura Mountains beyond -Chasseron (at the point marked G on the map), and the -whole valley is dotted with Alpine boulders. Upon comparing -these with the native rocks in the Alps, Guyot in -many cases was able to determine the exact centres from -which they were distributed, and the distribution is such -as to demonstrate that glacial ice was the medium of distribution.</p> - -<div class="footnote"> - -<p><a name="Footnote_46" id="Footnote_46"></a><a href="#FNanchor_46"><span class="label">[AT]</span></a> Antiquity of Man, p. 299.</p></div> - -<p>For example, the dotted lines upon the map indicate -the motion of the transporting medium. On ascending -the valley of the Rhône to A, the diminutive representative -of the ancient glacier is still found in existence, and -<span class="pagenum"><a name="Page_59" id="Page_59">« 59 »</a></span> -is at work transporting boulders and moraines according -to the law of ice-movement. Following down the valley -from A, boulders from the head of the Rhône Valley are -found distributed as far as B at Martigny, where the valley -turns at right angles towards the north. It is evident -that floating ice in a stream of water would by its momentum -be carried to the left bank, so that if icebergs were -the medium of transportation we should expect to find -the boulders from the right-hand side of the Rhône Valley -distributed towards the left end of the great valley of -Switzerland—that is, in the direction of Geneva. But, -instead, the boulders derived from C, D, and E, on the -Bernese Oberland side, instead of crossing the valley at -B, continue to keep on the right-hand side and are distributed -over the main valley in the direction of the river -Aar.</p> - -<p>As is to be expected also, the direct northward motion -of the ice from B is stronger than the lateral movement to -the right and left after it emerges from the mouth of the -Rhône Valley, at F, and consequently it has pushed forwards -in a straight line, so as to raise the Alpine boulders -to a greater height upon the Jura Mountains at G than -anywhere else, the upper limit of boulders at G being -1,500 feet higher than the limits at I or K on the left and -right, points distant about one hundred miles from each -other. All the boulders to the right of the line from B to -G have been derived from the right side of the Rhône, -while all the boulders to the left of that line have been -derived from its left side.</p> - -<p>A boulder of talcose granite containing 61,000 French -cubic feet, measuring about forty feet in one direction, -came, according to Charpentier, from the point <i>n</i>, near -the head of the Rhône Valley, and must have travelled -one hundred and fifty miles to reach its present position.</p> - -<p>It scarcely needs to be added that the grooves and -scratches upon the rocks over the floor of this great valley -<span class="pagenum"><a name="Page_60" id="Page_60">« 60 »</a></span> -of Switzerland indicate a direction of the ice-movement -corresponding to that implied in the distribution of boulders. -Thus, at K upon the map referred to, Lyell reports -that the abundant grooves and striæ upon the polished -marble all trend down the valley of the Aar.<a name="FNanchor_47" id="FNanchor_47"></a><a href="#Footnote_47" class="fnanchor">[AU]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_47" id="Footnote_47"></a><a href="#FNanchor_47"><span class="label">[AU]</span></a> Antiquity of Man, p. 305.</p></div> - -<p>Similar facts concerning the transportation of boulders -have been observed at Trogen, in Appenzel, where -boulders derived from Trons, one hundred miles distant, -are found to keep upon the left bank of the Rhine, however -much the valley may wind about; and in some places, -as at Mayenfeld, it turns almost at right angles, as did the -Rhône at Martigny. Upon reaching the lower country at -Lake Constance, these granite blocks from the left side of -the valley deploy out upon the same side and do not cross -over, as they would inevitably have done had they been -borne along by currents of water.</p> - -<p>In America Ave do not have quite so easy a field as is -presented in Switzerland for the discovery of crucial instances -showing that boulders have been transported by -glacial ice rather than by floating ice, for in Switzerland -the glaciated area is comparatively small and the diminutive -remnants of former glaciers are still in existence, furnishing -a comprehensive object-lesson of great interest -and convincing power. Still, it is not difficult to find -decisive instances of glacial transportation even in the -broad fields of America which now retain no living remnants -of the great continental ice-sheet.</p> - -<p>As every one who resides in or who visits New England -knows, boulders are scattered freely over all parts of that -region, but for a long time the theory suggested to account -for their distribution was that of floating ice during -a period of submergence. One of the most convincing -evidences that the boulders were distributed by glacial ice -rather than by icebergs is found in Professor C. H. Hitchcock’s -<span class="pagenum"><a name="Page_61" id="Page_61">« 61 »</a></span> -discovery of boulders on the summit of Mount -Washington (over 6,000 feet above the sea), which he was -able to identify as derived from the ledges of light grey -Bethlehem gneiss, whose nearest outcrop is in Jefferson, -several miles to the northwest, and 3,000 or 4,000 feet -lower than Mount Washington. However difficult it may -be to explain the movement of these boulders by glacial -ice, it is not impossible to do so, but the attempt to account -for their transportation by floating ice is utterly -preposterous. No iceberg could pick up boulders so far -beneath the surface of the water, and even if it could advance -thus far in its work it could not by any possibility -land them afterwards upon the summit of Mount Washington.</p> - -<p>Among the most impressive instances of boulders evidently -transported by glacial ice, rather than by icebergs, -were some which came to my notice when, in company -with the late Professor H. Carvill Lewis, I was tracing the -glacial boundary across the State of Pennsylvania. We -had reached the elevated plateau (two thousand feet above -the sea) which extends westwards and southwards from -the peak of Pocono Mountain, in Monroe County. This -plateau consists of level strata of sandstone, the southern -part of which is characterised by a thin sandy soil, such -as is naturally formed by the disintegration of the underlying -rock, and there is no foreign material to be found -in it. But, on going northwards to the boundary of Tobyhanna -township, we at once struck a large line of accumulations, -stretching from east to west, and rising to a height -of seventy or eighty feet. This was chiefly an accumulation -of transported boulders, resembling in its structure -the terminal moraines which are found at the front of -glaciers in the Alps and in Alaska, and indeed wherever -active glaciers still remain. But here we were upon the -summit of the mountain, where there are no higher levels -to the north of us, down which the ice could flow. Besides, -<span class="pagenum"><a name="Page_62" id="Page_62">« 62 »</a></span> -among these boulders we readily recognised many of -granite, which must have come either from the Adirondack -Mountains, two hundred miles to the north, or from -the Canadian highlands, still farther away.</p> - -<p>Limiting our observations simply to the boulders, we -should indeed have been at liberty to suppose that they -had been transported across the valley of the Mohawk or -of the Great Lakes by floating ice during a period of submergence. -But we were forbidden to resort to this hypothesis -by the abrupt marginal line, running east and -west, upon Pocono plateau, along which these northern -boulders ceased. South of this evident terminal moraine -there was no barrier, and there were no northern boulders. -On the theory of submergence, there was no reason for -the boundary-line so clearly manifested. Ice which had -floated so far would have floated farther.</p> - -<p>Still further, on going a few miles east of the Pocono -plateau, one descends into a parallel valley, lying between -Pocono Mountain and Blue Mountain, and one thousand -feet below their level. But our marginal southern boundary -of transported granite rocks did not extend much -farther south in the valley than it did on the plateau, -except where we could trace the action of a running -stream, evidently corresponding to the subglacial rivers -which pour forth from the front of every extensive glacier. -In these facts, therefore, we had a crucial test of the -glacial hypothesis, and, in view of them, could maintain, -against all objectors, the theory of the distant glacial -transportation of boulders, even over vast areas of the -North American continent.</p> - -<p>Since that experience, I have traced this limit of -southern boulders for thousands of miles across the continent, -according to the delineation which may be seen in -the <a href="#map_usa_glac">map in a later chapter</a>. If necessary, I could indicate -hundreds of places where the proof of glacial transportation -is almost as clear as that on the Pocono plateau -<span class="pagenum"><a name="Page_63" id="Page_63">« 63 »</a></span> -in Pennsylvania. One of the most interesting of these is -on the hills in Kentucky, about twelve miles south of the -Ohio River, at Cincinnati, where I discovered boulders of -a conglomerate containing many pebbles of red jasper, -which can be identified as from a limited formation cropping -out in Canada, to the north of Lake Huron, six -hundred or seven hundred miles distant. That this was -transported by glacial ice, and not by floating ice, is evident -from the fact that here, too, there was no barrier to -the south, requiring deposits to cease at that point, and -from the further fact that boulders of this material are -found in increasing frequency all the way from Kentucky -to the parent ledges in Canada. With reference to these -boulders, as with reference to those found on the summit -of Mount Washington, we can reason, also, that any -northerly subsidence permitting a body of water to occupy -the space between Kentucky and Lake Superior, and deep -<span class="pagenum"><a name="Page_64" id="Page_64">« 64 »</a></span> -enough to facilitate the movement across it of floating -ice, would render it impossible for the ice to have loaded -itself with them.</p> - -<div class="fig_center" style="width: 407px;"> -<a id="fig25" name="fig25"></a> -<img src="images/fig_25.png" width="407" height="296" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 25.</span>—Conglomerate boulder found in Boone County, Kentucky. (See text.)</div> -</div> - -<p>The same line of reasoning is conclusive respecting the -innumerable boulders which cover the northern portion -of Ohio, where I have my residence. The whole State of -Ohio, and indeed almost the entire Mississippi basin between -the Appalachian and the Rocky Mountains, is completely -covered, and to a great depth, with stratified rocks -which have been but slightly disturbed in the elevation of -the continent; yet, down to an irregular border-line running -east and west, granitic boulders everywhere occur in -great numbers. In the locality spoken of in northern -Ohio the elevation of the country is from two hundred to -five hundred feet above the level of Lake Erie. The nearest -outcrops of granitic rock occur about four hundred miles -to the north, in Canada. After the meeting of the American -Association for the Advancement of Science in Toronto -in the summer of 1889, I had the privilege of joining -a company of geologists in an excursion, conducted -by members of the Canadian Survey, to visit the region -beyond Lake Nipissing, north of Lake Huron, where the -ancient Laurentian and Huronian rocks are most typically -developed. I took advantage of the trip to collect specimens -of a great variety of the granites and gneisses and -metamorphic schists and trap-rock of the region. On -bringing them home I turned them over to the professor -of geology, who at once set his class at work to see if they -could match my fragments from Canada with corresponding -fragments from the boulders of the vicinity. To the -great gratification, both of the pupils and myself, they -were able to do so in almost every case; and so they might -have done in any county or township to the south until -reaching the limit of glacier action which I had previously -mapped. Here, at Oberlin, on the north side of the water-shed, -it is possible to imagine that we are on the southern -<span class="pagenum"><a name="Page_65" id="Page_65">« 65 »</a></span> -border of an ancient lake upon whose bosom floating ice -had brought these objects from their distant home in -Canada. But this theory would not apply to the portion -of the State which is south of the water-shed and which -slopes rapidly towards the Gulf of Mexico. Yet the distribution -of boulders is practically uniform over the glaciated -area on both sides of the water-shed, constituting -thus an indisputable proof of the glacial theory.</p> - -<p>4th. As the significance of the gravel terraces which -mark the lines of outward drainage from the glaciated -area cannot well be indicated in a single paragraph, the -reader is referred for further information upon this point -to the general statements respecting them throughout the -next chapter.</p> - -<hr class="chap" /> - -<div class="fig_center" style="width: 657px;"> -<a id="map_usa_glac" name="map_usa_glac"></a> -<a href="images/usa_glac_map_lrg.png"><img src="images/usa_glac_map_sm.png" width="657" height="487" alt="MAP SHOWING THE GLACIAL GEOLOGY OF THE UNITED STATES" /></a> -<div class="fig_caption smaller">Click on map to view larger sized.</div> -</div> - - -<p><span class="pagenum"><a name="Page_66" id="Page_66">« 66 »</a></span></p> - - -<p class="caption2"><a name="CHAPTER_V" id="CHAPTER_V">CHAPTER V.</a></p> - -<p class="caption2">ANCIENT GLACIERS IN THE WESTERN HEMISPHERE.</p> - - -<p class="caption3nb"><i>New England.</i></p> - -<p>In North America all the indubitable signs of glacial -action are found over the entire area of New England, the -southern coast being bordered by a double line of terminal -moraines. The outermost of these appears in Nantucket, -Martha’s Vineyard, No Man’s Land, Block Island, and -through the entire length of Long Island—from Montauk -Point, through the centre of the island, to Brooklyn, -N. Y., and thence across Staten Island to Perth Amboy in -New Jersey. The interior line is nearly parallel with the -outer, and, beginning at the east end of Cape Cod, runs -in a westerly direction to Falmouth, and thence southwesterly -through Wood’s Holl, and the Elizabeth Islands—these -being, indeed, but the unsubmerged portions of -the moraine. On the mainland this interior line reappears -near Point Judith, on the south shore of Rhode -Island, and, running slightly south of west, serves to give -character to the scenery at Watch Hill, and thence crops -out in the Sound as Fisher and Plum Islands, and farther -west forms the northern shore of Long Island to Port Jefferson.</p> - -<p><span class="pagenum"><a name="Page_67" id="Page_67">« 67 »</a></span></p> - -<p>In these accumulations bordering the southern shore -of New England, the characteristic marks of glacial action -can readily be detected even by the casual observer, and -prolonged examination will amply confirm the first impression. -The material of which they are composed is, -for the most part, foreign to the localities, and can be -traced to outcrops of rock at the north. The boulders -scattered over the surface of Long Island, for example, -consist largely of granite, gneiss, hornblende, mica slate, -and red sandstone, which are easily recognised as fragments -from well-known quarries in Connecticut, Rhode -Island, and Massachusetts; yet they have been transported -bodily across Long Island Sound, and deposited in a heterogeneous -mass through the entire length of the island. -Not only do they lie upon the surface, but, in digging into -the lines of hills which constitute the backbone of Long -Island, these transported boulders are found often to make -up a large part of the accumulation. Almost any of the -railroad excavations in the city of Brooklyn present an -interesting object-lesson respecting the composition of a -terminal moraine.</p> - -<p>All these things are true also of the lines of moraine -farther east, as just described. Professor Shaler has traced -to its source a belt of boulders occurring extensively over -southern Rhode Island, and found that they have spread -out pretty evenly over a triangular area to the southward, -in accordance with the natural course to be pursued by an -ice-movement. Nearly all of Plymouth County, in southeastern -Massachusetts, is composed of foreign material, -much of which can be traced to the hills and mountains -to the north. Even Plymouth Rock is a boulder from the -direction of Boston, and the “rock-bound” shores upon -which the Pilgrims are poetically conceived to have landed -are known, in scientific prose, as piles of glacial rubbish -dumped into the edge of the sea by the great continental -ice-sheet.</p> - -<p>The whole area of southeastern Massachusetts is dotted -with conical knolls of sand, gravel, and boulders, separated -by circular masses of peat or ponds of water, whose -origin and arrangement can be accounted for only by the -peculiar agency of a decaying ice-front. Indeed, this -<span class="pagenum"><a name="Page_68" id="Page_68">« 68 »</a></span> -whole line of moraines, from the end of Cape Cod to -Brooklyn, N. Y., consists of a reticulated network of -ridges and knolls, so deposited by the ice as to form innumerable -kettle-holes which are filled with water where -other conditions are favourable. Those which are dry are -so because of their elevation above the general level, and -of the looseness of the surrounding soil; while many have -been filled with a growth of peat, so that their original -character as lakelets is disguised.</p> - -<p>As already described, these depressions, so characteristic -of the glaciated region, are, in the majority of cases, -supposed to have originated by the deposition of a great -quantity of earthy material around and upon the masses -of ice belonging to the receding front of the glacier, so -that, when at length the ice melted away, a permanent depression -in the soil was left, without any outlet.</p> - -<p>To some extent, however, the kettle-holes may have -been formed by the irregular deposition of streams of water -whose courses have crossed each other, or where eddies -of considerable force have been produced in any way. The -ordinary formation of kettle-holes can be observed in progress -on the foot of almost any glacier, or, indeed, on a small -scale, during the melting away of almost any winter’s snow. -Where, from any cause, a stratum of dirt has accumulated -upon a mass of compact snow or ice, it will be found to -settle down in an irregular manner; furrows will be formed -in various directions by currents of water, so that the melting -will proceed irregularly, and produce upon a miniature -scale exactly what I have seen on a large scale over whole -square miles of the decaying foot of the great Muir Glacier -in Alaska. The effects of similar causes and conditions -we can see on a most enormous scale in the ten thousand -lakes and ponds and peat-bogs of the whole glaciated -area both in North America and in Europe.</p> - -<p>In addition to these two lines of evidence of glacial -action in New England, we should mention also the innumerable -<span class="pagenum"><a name="Page_69" id="Page_69">« 69 »</a></span> -glacial grooves and scratches upon the rocks -which can be found on almost any freshly uncovered surface. -In New England the direction of these grooves is -ordinarily a little east of south. Upon the east coast of -Massachusetts and New Hampshire the scratches trend -much more to the east than they do over most of the interior. -This is as it should be on the glacial theory, since -the ice would naturally move outwards in the line of least -resistance, which would, of course, be towards the open sea -wherever that is near. In the interior of New England -the scratches upon the rocks indicate a more southerly -movement in the Connecticut Valley than upon the -mountains in the western part of Massachusetts. This -also is as it should be upon the glacial theory. The -scratches upon the mountains were made when the ice -was at its greatest depth and when it moved over the -country in comparative disregard of minor irregularities -of surface, while in the valleys, at least in the later portion -of the Ice age, the movement would be obstructed -except in one direction. In the interpretation of the -glacial grooves and scratches it should be borne in mind -that they often represent the work done during the closing -stages of the period. Just as the last shove of the -carpenter’s plane removes the marks of the previous -work, so the last rasping of a glacial movement wears -away the surfaces which have been previously polished -and striated.</p> - -<p>In various places of New England it is interesting as -well as instructive to trace the direction of the ice-movement -by the distribution of boulders. My own attention -was early attracted to numerous fragments of gneiss -in eastern Massachusetts containing beautiful crystals of -feldspar, which proved to be peculiar to the region of -Lake Winnepesaukee, a hundred miles to the north, and -to a narrow belt stretching thence to the southwestward. -In ascending almost any of the lower summits of the -<span class="pagenum"><a name="Page_70" id="Page_70">« 70 »</a></span> -White Mountains one’s attention can scarcely fail of being -directed to the difference between the material of -which the mountains are composed and that of the numerous -boulders which lie scattered over the surface. -The local geologist readily recognises these boulders as -pilgrims that have wandered far from their homes to the -northward.</p> - -<p>Trains of boulders, such as those already described in -Rhode Island, can frequently be traced to some prominent -outcrop of the rock in a hill or mountain-peak from which -they have been derived. One of the earliest of these to -attract attention occurs in the towns of Richmond, Lenox, -and Stockbridge, in the western part of Massachusetts. -Here a belt of peculiar boulders about four hundred feet -wide is found to originate in the town of Lebanon, N. Y., -and to run continuously to the southeast for a distance of -nine miles. West of Fry’s Hill, where the outcrop occurs, -no boulders of this variety of rock are to be found, while -to the southeast the boulders gradually diminish in size as -their distance from the outcrop increases. Near the outcrop -boulders of thirty feet in diameter occur, while nine -miles away two feet is the largest diameter observed.</p> - -<p>Sir Charles Lyell endeavoured to explain this train of -boulders by the action of icebergs during a period of submergence—supposing -that, as icebergs floated past or -away from this hill in Lebanon, N. Y., they were the -means of the regular distribution described. It is needless -to repeat the difficulties arising in connection with -such a theory, since now both by observation and experiment -we have become more familiar with the movement of -glacial ice. What we have already said about the transportation -of boulders over Switzerland by the Alpine -glaciers, and what is open to observation at the present -time upon the large glaciers of Alaska, closely agree with -the facts concerning this Richmond train of boulders, and -we have no occasion to look further for a cause.</p> - -<p><span class="pagenum"><a name="Page_71" id="Page_71">« 71 »</a></span></p> - -<p>Indeed, trains of boulders ought to appear almost -everywhere over the glaciated area; and so they do where -all the circumstances are favourable. But, readily to identify -the train, requires that to furnish the boulders there -should be in the line of the ice-movement a projecting -mass of rock hard enough to offer considerable resistance -to the abrading agency of the ice and characteristic enough -in its composition to be readily recognised. Ship Rock, -in Peabody, Mass., weighing about eleven hundred tons, -and Mohegan Rock, in Montville, Conn., weighing about -ten thousand tons, have ordinarily been pointed to as -boulders illustrating the power of ice-action. Their glacial -character, however, has been challenged from the fact that -the variety of granite to which they belong occurs in the -neighbourhood, and indeed constitutes the bed-rock upon -which they rest.<a name="FNanchor_48" id="FNanchor_48"></a><a href="#Footnote_48" class="fnanchor">[AV]</a> Some would therefore consider them, -like some of which we have already spoken, to be boulders -which have originated through the disintegration of great -masses of rock, of which these were harder nuclei that -have longer resisted the ravages of the tooth of time. It -must be admitted that possibly this explanation is correct; -but it is scarcely probable that, in a region where there -are so many other evidences of glacial action, these boulders -could have remained immovable in presence of the -onward progress of the ice-current that certainly passed -over them.</p> - -<div class="footnote"> - -<p><a name="Footnote_48" id="Footnote_48"></a><a href="#FNanchor_48"><span class="label">[AV]</span></a> Popular Science Monthly, vol. xxxvii, pp. 196-201.</p></div> - -<p>However, as already seen, we are not left to doubt as -to the movement of some boulders of great size. That -which now claims the reputation of being the largest in -New England is in Madison, N. H., and measures thirty -by forty by seventy-five feet. This can be traced to -ledges of Conway granite, about two miles away.<a name="FNanchor_49" id="FNanchor_49"></a><a href="#Footnote_49" class="fnanchor">[AW]</a> Many -boulders in the vicinity of New Haven, Conn., can be -<span class="pagenum"><a name="Page_72" id="Page_72">« 72 »</a></span> -identified, as from well-known trap-dykes, sixteen miles -or more to the north. The so-called Judge’s Cave, on -West Rock, 365 feet above the adjoining valley and -weighing a thousand tons, is one of these. Professor Edward -Orton<a name="FNanchor_50" id="FNanchor_50"></a><a href="#Footnote_50" class="fnanchor">[AX]</a> describes a mass of Clinton limestone near -Freeport, Warren County, Ohio, as covering an area of -three-fourths of an acre, and as sixteen feet in thickness. -It overlies glacial clays and gravels, and must have been -transported bodily from the elevations containing this -rock several miles to the northwest.</p> - -<div class="footnote"> - -<p><a name="Footnote_49" id="Footnote_49"></a><a href="#FNanchor_49"><span class="label">[AW]</span></a> See W. 0. Crosby’s paper in Appalachia, vol. vi, pp. 59-70.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_50" id="Footnote_50"></a><a href="#FNanchor_50"><span class="label">[AX]</span></a> Geological Survey of Ohio, vol. iii, p. 385,</p></div> - -<div class="fig_center" style="width: 387px;"> -<a id="fig26" name="fig26"></a> -<img src="images/fig_26.png" width="387" height="396" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 26.</span>—Mohegan Rock.</div> -</div> - -<p><span class="pagenum"><a name="Page_73" id="Page_73">« 73 »</a></span></p> - -<p>Portions of New England present the best illustrations -anywhere afforded in America of what are called -“drumlins.” These are “lenticular-shaped” hills, composed -of till, and containing, interspersed through their -mass, numerous scratched stones of all sizes. They vary -in length from a few hundred feet to a mile, and are usually -from half to two-thirds as wide as they are long. In -height they vary from twenty-five to two hundred feet.</p> - -<p>But, according to the description of Mr. Upham, whatever -may be their size and height, they are singularly -alike in outline and form, usually having steep sides, with -gently sloping, rounded tops, and presenting a very -smooth and regular contour. From this resemblance in -shape to an elliptical convex lens, Professor Hitchcock -has called them lenticular hills to distinguish these deposits -of till from the broadly flattened or undulating -sheets which are common throughout New England.</p> - -<div class="fig_center" style="width: 401px;"> -<a id="fig27" name="fig27"></a> -<img src="images/fig_27.png" width="401" height="207" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 27.</span>—Drumlins in Goffstown, N. H. (Hitchcock).</div> -</div> - -<p>The trend, or direction of the longer axis, of these -lenticular hills is nearly the same for all of them comprised -within any limited area, and is approximately like -the course of the striæ or glacial furrows marked upon -the neighbouring ledges. In eastern Massachusetts and -<span class="pagenum"><a name="Page_74" id="Page_74">« 74 »</a></span> -New Hampshire, within twenty-five miles of the coast, it -is quite uniformly to the southeast, or east-southeast. -Farther inland, in both of these States, it is generally -from north to south, or a few degrees east of south; while -in the valley of the Connecticut River it is frequently a -little to the west of south. In New Hampshire, besides -its accumulation in these hills, the till is frequently -amassed in slopes of similar lenticular form. These have -their position almost invariably upon either the south or -north side of the ledgy hills against which they rest, showing -a considerable deflection towards the southeast and -northwest in the east part of the State. It cannot be -doubted that the trend of the lenticular hills, and the -direction taken by these slopes, have been determined by -the glacial current, which produced the striæ with which -they are parallel.<a name="FNanchor_51" id="FNanchor_51"></a><a href="#Footnote_51" class="fnanchor">[AY]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_51" id="Footnote_51"></a><a href="#FNanchor_51"><span class="label">[AY]</span></a> Proceedings of the Boston Society of Natural History, vol. xx, -pp. 224, 225.</p></div> - -<p>Drumlins are abundant in the vicinity of Boston, and -constitute nearly all the islands in Boston Harbour. On -the mainland, Beacon Hill, Bunker Hill, Green Hill, Powderhorn -Hill, Tufts College Hill, Winter Hill, Mount Ida, -Corey Hill, Parker Hill, Wollaston Heights, Prospect Hill, -and Telegraph Hill are specimens.</p> - -<p>The northeastern corner of Massachusetts and the -southeastern corner of New Hampshire are largely covered -with these peculiar-shaped glacial deposits, while -they are numerous as far west as Fitchburg, in Massachusetts, -and Ware, N. H., and in the northeastern part of -Connecticut. A little later, also, we shall refer to an interesting -line of them in central New York. Elsewhere -in America, except in a portion of Wisconsin, they rarely -occur in such fine development as in New England. In -Europe they are best developed in portions of Ireland.</p> - -<p>One’s first impression in examining an exposed section -<span class="pagenum"><a name="Page_75" id="Page_75">« 75 »</a></span> -of a drumlin would lead him to think that the mass was -entirely unstratified; but closer examination shows that -there is a coarse stratification, but evidently not produced -by water-action. The accumulation has probably taken -place gradually by successive deposits underneath the -glacier itself. Professor William M. Davis has suggested -a plausible explanation which we will briefly state.</p> - -<div class="fig_center" style="width: 268px;"> -<a id="fig28" name="fig28"></a> -<img src="images/fig_28.png" width="268" height="326" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 28.</span>—Drumlins in the vicinity of Boston (Davis).</div> -</div> - -<p>The frequency with which drumlins are found to rest -upon a mass of projecting rock, the general co-ordination -of the direction of their axes with the direction of the -scratches upon the underlying rock, and the abundance -of scratched stones in them, all support the theory that -drumlins are formed underneath the ice-sheet, somewhat -in the way that islands and bars of silt are formed in the -delta of a great river. The movement of ice seems to -<span class="pagenum"><a name="Page_76" id="Page_76">« 76 »</a></span> -have been concentrated in pretty definite lines, often determined -by the contour of the bottom, leaving a slacker -movement in intervening areas, which were evidently protected -in some cases by projecting masses of rock. In -these areas of slower movement there was naturally an -accumulation at the same time that there was vigorous -erosion in the lines of more rapid movement.</p> - -<p>There was doubtless a continual transfer of material -from the end of the drumlin which abutted against the -moving mass of ice to the lower end, as there is in the -formation of an island in a river. If time enough had -elapsed, the whole accumulation would have been levelled -by the glacier and spread over the broader area where the -more rapid lines of movement became confluent, and -where the differential motion was less marked. Drumlins -are thus characteristic of areas in the glaciated region -whose floor was originally only moderately irregular, and -where there was an excessive amount of ground-moraine -to be transported, and where the movement did not continue -indefinitely. It has been suggested, also, that some -of the long belts of territory in New England and central -New York covered by drumlins may represent old terminal -moraines which were subsequently surmounted by a readvance -of the ice, and partially wrought over into their -present shape.</p> - -<p>It is in New England, also, that kames are to be found -in better development than anywhere else in America. -These interesting remnants of the Glacial age are clearly -described by Mr. James Geikie. His account will serve -as well for New England as for Scotland.</p> - -<p>The sands and gravels have a tendency to shape themselves -into mounds and winding ridges, which give a -hummocky and rapidly undulating outline to the ground. -Indeed, so characteristic is this appearance, that by it -alone we are often able to mark out the boundaries of the -deposits with as much precision as we could were all the -<span class="pagenum"><a name="Page_77" id="Page_77">« 77 »</a></span> -vegetation and soil stripped away and the various subsoils -laid bare. Occasionally, ridges may be tracked continuously -for several miles, running like great artificial ramparts -across the country. These vary in breadth and -height, some of the more conspicuous ones being upward -of four or five hundred feet broad at the base, and sloping -upward at an angle of twenty-five or even thirty-five degrees, -to a height of sixty feet and more above the general -surface of the ground. It is most common, however, to -find mounds and ridges confusedly intermingled, crossing -and recrossing each other at all angles, so as to enclose -deep hollows and pits between. Seen from some dominant -point, such an assemblage of kames, as they are called, -looks like a tumbled sea—the ground now swelling into -long undulations, now rising suddenly into beautiful peaks -and cones, and anon curving up in sharp ridges that often -wheel suddenly round so as to enclose a lakelet of bright -clear water.<a name="FNanchor_52" id="FNanchor_52"></a><a href="#Footnote_52" class="fnanchor">[AZ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_52" id="Footnote_52"></a><a href="#FNanchor_52"><span class="label">[AZ]</span></a> The Great Ice Age, pp. 210, 211.</p></div> - -<div class="fig_center" style="width: 413px;"> -<a id="fig29" name="fig29"></a> -<img src="images/fig_29.png" width="413" height="86" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 29.</span>—Section of kame near Dover, New Hampshire. Length, three hundred -feet; height, forty feet; base, about forty feet above the Cocheco River, or -seventy-five feet above the sea. <i>a</i>, <i>a</i>, gray clay; <i>b</i>, fine sand; <i>c</i>, <i>c</i>, coarse -gravel containing pebbles from six inches to one foot and a half in diameter; -<i>d</i>, <i>d</i>, fine gravel (Upham).</div> -</div> - -<div class="fig_center" style="width: 359px;"> -<a id="fig30" name="fig30"></a> -<img src="images/fig_30.png" width="359" height="558" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 30.</span>—Kames in Andover Mass.</div> -</div> - -<p>In New England attention was first directed to kames -in 1842, by President Edward Hitchcock, in a paper before -the American Association of Geologists and Naturalists, -describing the gravel ridges in Andover, Mass. In -the accompanying plate is shown a portion of this kame -system, which has a double interest to me from the fact -that it was while living upon the banks of the Shawshin -<span class="pagenum"><a name="Page_78" id="Page_78">« 78 »</a></span> -River, near where the kames and the river intersect, that I -began, in 1874, my special study of glacial deposits. The -Andover ridges are composed of imperfectly stratified -water-worn material, and are very sharply defined, from -the town of Chelsea, back from the coast into New Hampshire, -for a distance of twenty-five miles. The base of the -ridges does not maintain a uniform level, but the system -descends into shallow valleys, and rises over elevations of -one hundred to two hundred feet, without interruption. -This indifference to slight changes of level is specially -noticeable where the system crosses the Merrimac River, -just above the city of Lawrence. It is also represented in -the accompanying plate, where the base of the ridges in -the immediate valley of the Shawshin is fifty feet lower -than the base of those a short distance to the north, at -the points marked <i>a</i>, <i>b</i>, and <i>c</i>. The ridges here terminate -at the surface in a sharp angle, and are above their base -forty-one feet at <i>a</i>, forty-nine feet at <i>b</i>, and ninety-one feet -at <i>c</i>. Between <i>c</i> and <i>b</i> there is an extensive peat-swamp, -filling the depression up to the level of an outlet through -which the surplus water has found a passage.</p> - -<p><span class="pagenum"><a name="Page_79" id="Page_79">« 79 »</a></span></p> - -<div class="fig_center" style="width: 685px;"> -<a id="fig31" name="fig31"></a> -<img src="images/fig_31.png" width="685" height="276" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 31.</span>—Longitudinal kames near Hingham, Massachusetts. The parallel ridges of gravel in the foreground run nearly east and west, and coalesce -at each end, near the edges of the picture, to form an elongated kettle-hole. The ridges from fifty to sixty feet in height. The kame-stream -was here evidently emptying into the ocean a few miles to the east (Bouvé).</div> -</div> - -<p><span class="pagenum"><a name="Page_80" id="Page_80">« 80 »</a></span></p> - -<p>Several systems of kames approximately parallel to -this have been traced out in Massachusetts and New -Hampshire, while the remnants of a very extensive system -are found in the Connecticut Valley above the Massachusetts -line. But they abound in greatest profusion -in the State of Maine, where Professor George H. Stone -has plotted them with much care. The accompanying -map gives only an imperfect representation of the ramifying -systems which he has traced out, and of the extent to -which they are independent of the present river-channels. -One of the longest of these extends more than one hundred -miles, crossing the Penobscot River nearly opposite -Grand Lake, and terminating in an extensive delta of -gravel and sand in Cherryfield, nearly north of Mount -Desert. This is represented on our map by the shaded -portion west of the Machias River. Locally these ridges -are variously designated as “horsebacks,” “hogbacks,” or -“whalebacks,” but that in Andover, Mass., was for some -reason called “Indian Ridge.” Nowhere else in the world -<span class="pagenum"><a name="Page_81" id="Page_81">« 81 »</a></span> -are these ridges better developed than in New England, -except it be in southern Sweden, where they have long -been known and carefully mapped.</p> - -<div class="fig_center" style="width: 422px;"> -<a id="fig32" name="fig32"></a> -<img src="images/fig_32.png" width="422" height="509" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 32.</span>—The kames of Maine and southeastern New Hampshire. (Stone.)</div> -</div> - -<p>The investigations of Mr. W. 0. Crosby upon the composition -of till in eastern Massachusetts is sufficiently important -<span class="pagenum"><a name="Page_82" id="Page_82">« 82 »</a></span> -in its bearings upon the question of glacial erosion -to merit notice at this point.<a name="FNanchor_53" id="FNanchor_53"></a><a href="#Footnote_53" class="fnanchor">[BA]</a> The object of his investigations -was to determine how much of the so-called -ground moraine, or till, consisted of material disintegrated -by mechanical action, and how much by chemical action. -The “residuary clay,” which has arisen from chemical decomposition, -would properly be attributed to the disintegrating -agencies of preglacial times, while the clay, which -is strictly mechanical in its origin, remains to represent -the true “grist” or “rock flour” of the Glacial period.</p> - -<div class="footnote"> - -<p><a name="Footnote_53" id="Footnote_53"></a><a href="#FNanchor_53"><span class="label">[BA]</span></a> Proceedings of the Boston Society of Natural History, vol. -xxv (1890), pp. 115-140.</p></div> - -<p>The results of Mr. Crosby’s investigations show that -“not more than one-third of the <i>detritus</i> composing the -till of the Boston Basin was in existence before the Ice -age, and that the remaining two-thirds must be attributed -to the mechanical action of the ice-sheet and its accompanying -torrents of water. In other words, if we assume -the average thickness of the drift as thirty feet, the -amount of glacial erosion can scarcely fall below twenty -feet. After scraping away the residuary clays and half-decomposed -material, the ice-sheet has cut more than an -equal depth into the solid rocks.”</p> - -<p>Mr. Crosby’s investigations also convinced him that the -movement of the till, or ground moraine, underneath the ice -was not <i>en masse</i>, but that “it must have experienced differential -horizontal movements or flowing, in which, normally, -every particle or fragment slipped or was squeezed -forward with reference to those immediately below it, the -velocity diminishing downward through the friction of -the underlying ledges.... The glaciation was not limited -to masses which were firmly caught between the ice and -the solid ledges, and it was in every case essentially a slipping -and not a rolling movement.... These differential -horizontal movements mean that the till acted as a lubricant -<span class="pagenum"><a name="Page_83" id="Page_83">« 83 »</a></span> -for the ice-sheet; and the clayey element, especially, -co-operating in many cases with the pent-up subglacial -waters, must have greatly facilitated the onward progress -of the ice.” He concludes, therefore, that the onward -movement of the vast ice-sheet greatly exceeded that of -the main part of the ground moraine, the ice-sheet slipping -over the till, the whole being in some degree analogous to -that of a great land-slip. “In both cases the progress of -a somewhat yielding and mobile mass is facilitated by an -underlying clayey layer saturated with water.”</p> - - -<p class="caption3nb"><i>New York, New Jersey, and Pennsylvania.</i></p> - -<p>West of New England the glacial phenomena over the -northern part of the United States are equally marked all -the way to the Missouri River, and the boundary-line of -the glaciated region can be traced with little difficulty. -It emerges from New York Bay on Staten Island and -enters New Jersey at Perth Amboy. A well-formed -moraine covers the northern part of Staten Island, and -upon the mainland marks the boundary from Perth -Amboy, around through Raritan, Plainfield, Chatham, -Morris, and Hanover, to Rockaway, and thence in a -southwesterly direction to Belvidere, on the Delaware -River. That portion of New Jersey lying north of this -serpentine line of moraine hills is characterised by the -presence of transported boulders, by numerous lakes of -evident glacial origin, and by every other sign of glacial -action, while south of it all these peculiar characteristics -are absent. The observant passenger upon the railroad -trains between New York and Philadelphia can easily -recognise the moraine as it is passed through on the -Pennsylvania Railroad at Metuchen and on the Bound -Brook Railroad at Plainfield. Near Drakestown, in Morris -County, there is a mass of blue limestone measuring, -as exposed, thirty-six by thirty feet, and which was quarried -for years before discovering that it was a boulder -<span class="pagenum"><a name="Page_84" id="Page_84">« 84 »</a></span> -brought with other drift material from many miles to the -northwest and lodged here a thousand feet above the sea.</p> - -<p>Across Pennsylvania the glacial boundary passes -through Northampton, Monroe, Luzerne, Columbia, Sullivan, -Lycoming, Tioga, and Potter Counties, where it enters -the State of New York, running still in a northwest -direction through Allegany and Cattaraugus Counties to -the vicinity of Salamanca. Here it turns to the south -nearly at a right angle, running southwestward to Chautauqua -County and re-entering Pennsylvania in Warren -County, and thence passing onward in the same general -direction through Crawford, Venango, Mercer, Butler, -and Lawrence Counties to the Ohio line in Columbiana -County, about ten miles north of the Ohio River.</p> - -<p>The occurrence of a well-defined terminal moraine to -mark the glacial boundary eastward from Pennsylvania -led Professor Lewis and myself, who made the survey of -that State in 1880, to be rather too sanguine in our expectations -of finding an equally well-marked moraine -everywhere along the southern margin of the glaciated -area; still, the results are even more interesting than -would have been the exact fulfilment of our expectations, -since they more fully revealed to us the great complexity -of effect which is capable of being brought about by ice-action. -Before proceeding farther with the details, therefore, -it will be profitable at this point to pause in the -narrative and briefly record a few generalisations that have -forced themselves into prominence during the years in -which field-work has been in progress.</p> - -<p>Previous to our explorations in Pennsylvania it had -been thought that the indications of ice-action would -extend much farther south in the valleys than on the -mountains, and this indeed would have been the case if -the glaciers in northern Pennsylvania had been of local -origin; but our experience very soon demonstrated that -the great gathering-place of the snows which produced -<span class="pagenum"><a name="Page_85" id="Page_85">« 85 »</a></span> -the glacial movement in northern Pennsylvania could not -have been local, but that over the northern part of that -State there was distinct evidence of a continental movement -of ice whose centre was far beyond the Alleghanies.</p> - -<p>For example, we found that the evidences of direct -glacial action extended farther south upon the hills and -plateaus than they did in the narrow valleys, while everywhere -on the very southern border of glacial indications -we found boulders that had been brought from the granitic -region of northern New York or central Canada. -In eastern Pennsylvania we found indeed a terminal moraine -more or less distinctly marking the southern border -over the highlands. This was more specially true in -Northampton and Monroe Counties.</p> - -<p>In Northampton County it was very interesting to see -long lines of hills, a hundred or more feet in height and -lying several hundred feet above the Delaware River, composed -entirely of glacial <i>débris</i>, much of which had been -brought bodily over the sharp summit of the Blue Ridge, -or Kittatinny Mountain, which rises as a continuous wall -to the northwest and is everywhere several hundred feet -higher than the moraine in Northampton County. The -summit of Blue Ridge, also, as far south as the glacial -movement extended, shows evident signs of glacial abrasion, -some hundreds of feet evidently having been removed -by that means, leaving a well-defined shoulder, marking -the limits of its southwestern border. Resting upon the -summit of the glaciated portion of the Blue Ridge, there -are also numerous boulders of Helderberg limestone, which -must have been brought from ledges at least five hundred -feet lower than the places upon which they now lie.</p> - -<p>In Monroe County the terminal moraine marking there -the extreme limit of the ice-movement is upon an extensive -plateau of Pocono sandstone, about eighteen hundred -feet above sea-level, and five or six hundred feet lower than -<span class="pagenum"><a name="Page_86" id="Page_86">« 86 »</a></span> -the crest of the Alleghany Mountains, a short distance to -the north. The moraine hills are here well marked by -the occurrence of circular lakelets and kettle-holes (such -as have been described as characteristic of the shores and -islands bordering the south of New England); by the -occurrence of granitic boulders, which must have been -brought from the Adirondacks or Canada; and by the -various other indications referred to on a previous page.</p> - -<p>As already intimated, the instructive point in our observations -is the fact that, between Kittatinny Mountain, -in Northampton County, and Pocono plateau, in Monroe -County, there is a longitudinal depression, running northeast -by southwest, parallel with the ranges of the mountain -system, which is here about a thousand feet below the -respective ridges on either side. This, therefore, is one of -the places where we should have expected a considerable -southern extension of the ice, if it had been largely due to -local causes. Now, while there is indeed a gradual southern -trend down the flanks of the mountain, yet, upon reaching -the axis of the valley, there appears at once a very -marked change in the character of the deposit, and the -influence of powerful streams of water becomes manifest, -and it is evident, upon a slight inspection, that we have -come upon a line of drainage which sustained a peculiar -relation to the continental ice-sheet.</p> - -<p>From Stroudsburg, near the Delaware Water-Gap, to -Weissport, on the Lehigh River, a distance of about thirty -miles, the valley between the mountains is continuous, and -the elevation at each end very nearly the same. But about -half-way between the two places, near Saylorsburg, there -is a river-parting from which the water now runs on the -one hand north to Stroudsburg, and thence to the Delaware -River, and on the other hand south, through Big and -Aquonchichola Creeks, to the Lehigh River. The river-parting -is formed by a great accumulation of gravel, whose -summit is about two hundred feet above the level of the -<span class="pagenum"><a name="Page_87" id="Page_87">« 87 »</a></span> -valleys into which the creeks empty at either end; and -there are numerous kettle-holes and lakelets in the vicinity, -such as characterize the glacial region in general.</p> - -<p>In short, we are, without doubt, here on a well-marked -terminal moraine much modified by strong water-action -in a valley of glacial drainage. The gravel and boulders -are all well water-worn, and the material is of various kinds, -including granite boulders from the far north, such as characterise -the terminal moraine on the highlands; but the -pebbles are not scratched, and the gravel is more or less -stratified. It is evident that we are here where a violent -stream of water poured forth from that portion of the ice-front -which filled this valley, and which found its only outlet -in the direction of the Lehigh River. The gravel can -be traced in diminishing quantities to the southward, in -accordance with this theory, while to the northward there -extends a series of gravel ridges, or kames, such as we have -shown naturally to owe their origin to the accumulations -taking place in ice-channels formed near the front of a -glacier as it slowly melts away.</p> - -<p>From similar occurrences of vast gravel accumulations -in other valleys stretching southward from the glacial -margin, we came to expect that, wherever there was an -open, line of drainage from the glaciated region southward, -the point of intersection between the glacial margin -and the drainage valley would be marked by an excessive -accumulation of water-worn gravel, diminishing in coarseness -and abundance down the valleys in proportion to the -distance from the glacial margin.</p> - -<p>For example, the Delaware River emerges from the -glaciated region at Belvidere, and there are there vast accumulations -of gravel rising a hundred or more feet above -the present level of the river, while gravel terraces, diminishing -in height, mark the river below to tide-water at -Trenton. The Lehigh River leaves the glaciated region -at Hickory Run, a few miles above Mauch Chunk, but -<span class="pagenum"><a name="Page_88" id="Page_88">« 88 »</a></span> -the gorge is so steep that there was little opportunity -either for the accumulation of gravel there or for its preservation. -Still, the transported gravel and boulders characteristic -of the melting floods pouring forth from a glacier, -are found lining the banks of the Lehigh all along the -lower portion of its course. In the Susquehanna River -we have a better example at Beach Haven, in Luzerne -County, where there are very extensive accumulations of -gravel resting on the true glacial deposits of the valley, -and extending down the river in terraces of regularly -diminishing height for many miles, and merging into terraces -of moderate elevation which line the Susquehanna -Valley throughout the rest of its course. Above Beach -Haven the gravel deposits in the trough of the river valley -are more irregular, and betray the modifying influence of -the slowly decaying masses of ice which belonged to the -enveloping continental glacier.</p> - -<p>Westward from the north fork of the Susquehanna, -similar extensive accumulations of gravel occur at the intersection -of Fishing Creek in Columbia County, Muncy, -Loyalsock, Lycoming, and Pine Creeks in Lycoming -County, all tributary to the Susquehanna River, and all -evidently being channels through which the melting floods -of the ice-sheet brought vast quantities of gravel down to -the main stream. Williamsport, on the West Branch of -the Susquehanna, is built upon an extensive terrace containing -much granitic material, brought down from the -glaciated region by Lycoming Creek, when it was flooded -with the waters melted from the continental ice-sheet -which had here surmounted the Alleghanies and invaded -the valley of the Susquehanna.</p> - -<p>Analogous deposits of unusual amounts of gravel, occurring -in streams flowing southward from the glaciated -region, occur at Great Valley, Little Valley, and Steamburg -in Cattaraugus County, New York, and at Russelburg -and Garland in Warren County, Pennsylvania, also -<span class="pagenum"><a name="Page_89" id="Page_89">« 89 »</a></span> -at Titusville and Franklin in Venango County, and at -Wampum in Lawrence County, of the same State.</p> - -<p>As a rule, Professor Lewis and myself found it more -difficult to determine with accuracy the exact point to -which the ice extended in the axis of these south-flowing -valleys than we did upon the highlands upon either side; -and, in looking for the positive indications of direct ice-action -in these lines of drainage, we were almost always -led up the valley to a considerable distance inside of the -line. This arose from our inexperience in interpreting -the phenomena, or rather from our inattention to the -well-known determining facts in the problem. On further -reflection it readily appeared that this was as it should -be. The ice-front, instead of extending farther down in -a narrow valley than on the adjoining highlands (where -they are of only moderate elevation) ought not to extend -so far, for the subglacial streams would not only wear -away the ice of themselves, but would admit the air into -the tunnels formed by them so as to melt the masses both -from below and from above, and thus cause a recession of -the front. If we had understood this principle at the beginning -of our survey, it would have saved us much perplexity -and trouble.</p> - -<p>A single further illustration of this point will help to -an understanding of many references which will hereafter -be made to the water deposits which accumulated in the -lines of drainage running southward from the glaciated -area. At Warren, Pa., Conewango Creek, which is the -outlet from Chautauqua Lake, enters the Alleghany River -after flowing for a number of miles in a deep valley with -moderate slopes. In ascending the creek from Warren, -the gravel terraces, which rise twenty-five or thirty feet -above high-water mark, rapidly increase in breadth and -height, and the pebbles become more and more coarse. -After a certain distance the regular terraces begin to give -place to irregular accumulations of gravel in ridges and -<span class="pagenum"><a name="Page_90" id="Page_90">« 90 »</a></span> -knobs. In the lower portion of the valley no pebbles -could be found which were scratched. Up the valley -a few miles pebbles were occasionally discovered which -showed some slight indications of having been scratched, -but which had been subjected to such an amount of abrasion -by water-action as almost to erase the scratches. On -reaching Ackley’s Station, the stream is found to be cutting -through a regular terminal moraine, extending across -the valley and full of clearly marked glaciated stones. -Above this terminal moraine the terraces and gravel -ridges which had characterised the valley below disappear, -giving place to long stretches of level and swampy land, -which had been subject to overflow.</p> - -<p>Something similar to this so often appears, that there -can be no question as to its meaning, which is, that during -the farthest extent of the ice the front rested for a -considerable period of time along the line marked by the -terminal moraine. During this period there occurred both -the accumulation of the moraine and of the gravel terraces -in the valley below, due to the vast flow of water emerging -from the ice-front, especially during the period when -it was most rapidly melting away. Upon the retreat of -the ice, the moraine constituted a dam which has not yet -been wholly worn away. For a while the water was so effectually -ponded back by this as to form a lake, which has -since become filled up with sediment and accumulations -of peat. From this it is evident, also, that when the ice -began to retreat, the retreat was so continuous and rapid -that no parallel terminal moraines were formed for many -miles.</p> - -<p>Before leaving this section we will summarise the -leading facts concerning the glacial phenomena north of -Pennsylvania and New Jersey. From the observations of -Professor Smock, it appears that, from the southern margin -the ascent to the summit of the ice-sheet was pretty -rapid; the depth one mile back from the margin being -<span class="pagenum"><a name="Page_91" id="Page_91">« 91 »</a></span> -not much less than a thousand feet. “Northward the -angle of the slope diminished, and the glacier surface approximated -to a great level plain. The distance between -the high southwestern peaks of the Catskills and Pocono -Knob in Pennsylvania is sixty miles. The difference in -the elevation of the glacier could not have exceeded a -thousand feet,” <a name="FNanchor_54" id="FNanchor_54"></a><a href="#Footnote_54" class="fnanchor">[BB]</a> that is, the slope of the surface was -about seventeen feet to the mile.</p> - -<div class="footnote"> - -<p><a name="Footnote_54" id="Footnote_54"></a><a href="#FNanchor_54"><span class="label">[BB]</span></a> American Journal of Science, vol. cxxv, 1883, p. 339 <i>et seq.</i></p></div> - -<p>Professor Dana estimates the thickness of the ice in -southern Connecticut to have been between fifteen hundred -and two thousand feet. Attempts to calculate the -thickness of the ice farther north, except from actual discovery -of glacial action on the summits of the mountains, -are based upon uncertain data with reference to the slope -necessary to secure glacial movement. In the Alps the -lowest mean slopes down which glaciers move are about -two hundred and fifty feet to a mile; but in Greenland, -Jensen found the slope of the Frederickshaab Glacier to -be only seventy-five feet to the mile, while Helland found -that of the Jakobshavn Glacier to be only forty-five feet.</p> - -<p>It is doubtful if even that amount is necessary to secure -a continental movement of ice, since, as already remarked, -it is unsafe to draw inferences concerning the -movements of large masses of ice from those of smaller -masses in more constricted areas. We have seen, from -the glacial deposits on the top of Mount Washington, -that over the northern part of New England the ice was -more than a mile in depth. We have no direct evidence -of the depth of the stream which surrounded the Adirondack -Mountains. Nor, on the other hand, are we certain -that the Catskills were not completely enveloped in ice, -though most observers, reasoning from negative evidence, -have supposed that to be the case. But from the facts -stated concerning the boulders along the glacial boundary -<span class="pagenum"><a name="Page_92" id="Page_92">« 92 »</a></span> -in Pennsylvania, it is certain that the ice was deep enough -to surmount the ridge of the Alleghanies where they are -two thousand and more feet in height. At the least calculation -the ice must have been five hundred feet thick, -in order to secure the movement of which there is evidence -across the Appalachian range. Supposing this to -be the height of the ice above the sea on the crest of the -Alleghanies, and that the slope of the surface of the ice-sheet -was as moderate as Professor Smock has estimated -it (namely seventeen feet to the mile), the ice would be -upwards of six thousand feet in thickness in the latitude -of the Adirondacks, which corresponds closely with the -positive evidence Ave have from the mountains in New -England.</p> - -<p>A study of the map of New York will make it easy to -understand the distribution of some interesting glacial -marks over the State. The distance along the Hudson -from the glacial boundary in the vicinity of New York to -the valley of the Mohawk is about one hundred and sixty -miles. Prom the glacial boundary at Salamanca, N. Y., -to the same valley, is not over eighty miles. It is easy to -see, therefore, that when, in advancing, the ice moved -southward past the Adirondacks, the east end of the valley -of the Mohawk was reached and closed by the ice, while -at the west end of Lake Ontario the ice-front was still in -Canada. Thus the drainage, which naturally followed -the course of the St. Lawrence, would first be turned -through the Mohawk. Afterwards, when the Mohawk -had been closed by ice, the vast amount of ponded water -was compelled to seek a temporary outlet over the lower -passages leading into the Susquehanna or into the Alleghany.</p> - -<p>A number of such passages exist. One can be traced -along the line of the old canal from Utica to Binghamton, -whose highest level is not far from eleven hundred -feet. Another lies in a valley leading south of Cayuga -<span class="pagenum"><a name="Page_93" id="Page_93">« 93 »</a></span> -Lake, whose highest point, at Wilseyville, is nine hundred -and forty feet above tide. Another leads south to the -Chemung River from Seneca Lake, whose highest point, -at Horseheads, is less than nine hundred feet above tide. -The cols farther west are somewhat more elevated; the -one at Portage, leading from the Genesee River into the -Canisteo, being upwards of thirteen hundred feet, and -that of Dayton, leading from Cattaraugus Creek into the -Conewango, being about the same. Of other southern -outlets farther west we will speak later on.</p> - -<p>Fixing our minds now upon the region under consideration, -in the southern part of the State of New York, -we can readily see that a glacial lake must have existed in -front of the ice while it was advancing, until it had reached -the river-partings between the Mohawk and the St. Lawrence -Rivers on the north and the Susquehanna and Alleghany -Rivers on the south. After the ice had attained its -maximum extension, and was in process of retreat, there -would be a repetition of the phenomena, only they would -occur in the reverse order. The glacial markings which -we see are, of course, mainly those produced during the -general retreat of the ice.</p> - -<p>The Susquehanna River stretching out its arms—the -Chenango and Chemung Rivers—to the east and the west, -evidently serves as a line of drainage for the vast glacial -floods. These floods have left, along their courses, extensive -elevated gravel terraces, with much material in them which -is not local, but which has been washed out of the direct -glacial deposits from the far north. The east-and-west -line of the water-parting throughout the State is characterised -by excessive accumulations of glaciated material, -forming something like a terminal moraine, and is designated -by President Chamberlin as “the terminal moraine -of the second Glacial epoch,” corresponding, as he thinks, -to the interior line already described as characterising the -south shore of New England.</p> - -<p><span class="pagenum"><a name="Page_94" id="Page_94">« 94 »</a></span></p> - -<p>In the central part of New York the remarkable series -of “Finger Lakes,” tributary to Lake Ontario and -emptying into it through the Oswego and Genesee Rivers, -all have a glacial origin. Probably, however, they are not -due in any great degree to glacial erosion, but they seem -to occupy north-and-south valleys which had been largely -formed by streams running towards the St. Lawrence -when there was, by some means (probably through the -Mohawk River), a much deeper outlet than now exists, -but which has been filled up and obliterated by glacial -<i>débris</i>. The ice-movement naturally centred itself more -or less in these north-and-south valleys, and hence somewhat -enlarged them, but probably did not deepen them. -The ice, however, did prevent them from becoming filled -with sediment, and on its final retreat gave place to -water.</p> - -<p>Between these lakes and Lake Ontario, also, and extending -east and west nearly all the way from Syracuse to -Rochester, there is a remarkable series of hills, from one -hundred to two or three hundred feet in height, composed -of glacial <i>débris</i>. But while the range extends east and -west, the axis of the individual hills lies nearly north and -south. These are probably remnants of a morainic accumulation -which were made during a pause in the first -advance of the ice, and were finally sculptured into their -present shape by the onward movement of the ice. These -are really “drumlins,” similar to those already described -in northeastern Massachusetts and southeastern New -Hampshire. In the valley of central New York these -have determined the lines of drainage of the “Finger -Lakes,” and formed dams across the natural outlets of -nearly all of them.</p> - -<p>North of the State of New York the innumerable -lakes in Canada are all of glacial origin, being mostly due -to depressions of the nature of kettle-holes, or to the damming -up of old outlets by glacial deposits. A pretty well-marked -<span class="pagenum"><a name="Page_95" id="Page_95">« 95 »</a></span> -line of moraine hills, formed probably as terminal -deposits in the later stages of the Ice age, runs from -near the eastern end of Lake Ontario to the Georgian -Bay, passing south of Lake Simcoe.</p> - - -<p class="caption3nb"><i>The Mississippi Basin.</i></p> - -<p>The physical geography of the glaciated region north -of the Ohio River is so much simpler than that of New -England and the Middle States, that its characteristics -can be briefly stated. Ohio, Indiana, and Illinois are covered -with nearly parallel strata of rock mostly of the Carboniferous -age. In general, the surface slopes gently to -the west; the average elevation of Ohio being about a -thousand feet above tide, while that of the Great Lakes to -the north and of the middle portion of the Mississippi -Valley is less than six hundred feet. The glacial deposits -are spread in a pretty even sheet over the area which was -reached by the ice in these States, and the lines of moraine, -of which a dozen or more have been partially traced -in receding order, are much less clearly marked than they -are in New England, or in Michigan, and the States farther -to the northwest.</p> - -<p>The line marking the southern limit attained by the -ice of the Glacial period in these three States is as follows: -Entering Ohio in Columbiana County, about ten miles -north of the Ohio River, the glacial boundary runs westward -through New Lisbon to Canton in Stark County, -and thence to Millersburg in Holmes County. A few -miles west of this place it turns abruptly south, passing -through Danville in Knox County, Newark in Licking -County, Lancaster in Fairfield County, to Adelphi in Ross -County. Thence bearing more westward it passes through -Chillicothe to southeastern Highland County and northwestern -Adams, reaching the Ohio River near Ripley, in -Clermont County. Thence, following the north bank of -the Ohio River to Cincinnati, it crosses the river, and after -<span class="pagenum"><a name="Page_96" id="Page_96">« 96 »</a></span> -extending through the northern part of Boone County, -Kentucky, and recrossing the river to Indiana, not far -from Rising Sun, it again follows approximately the north -bank of the river to within about ten miles of Louisville, -Ky., where it bends northward running through Clarke, -Scott, Jackson, Bartholomew, and Brown Counties to Martinsville, -in Morgan County, where it turns again west and -south and follows approximately the West Branch of the -White River through Owen, Greene, and Knox Counties, -where it crosses the main stream of White River, and, continuing -through Gibson and Posey Counties, crosses the -Wabash River near New Harmony.</p> - -<p>In Illinois the line still continues southwesterly through -White, Gallatin, Saline, and Williamson Counties, where -it reaches its southern limit near Carbondale, in latitude -37° 40’, and from this point trends northwestward, approximately -following the northeastern bluff of the Mississippi -River, to the vicinity of Carondelet, Mo., a short -distance south of St. Louis.</p> - -<p>Beyond the Mississippi the line follows approximately -the course of the Missouri River across Missouri, and continues -westward to the vicinity of Manhattan, in Kansas, -where it turns northward, keeping about a hundred miles -west of the Missouri River, through eastern Kansas and -Nebraska, and striking the river near the mouth of the -Niobrara, in South Dakota. From there the line follows -approximately the course of the Missouri River to the vicinity -of Fort Benton, in northwestern Montana, where the line -again bears more northward, running into British America.</p> - -<p>It is still in dispute whether the ice extended from the -eastern centre far enough west to join the ice-movement -from the Rocky Mountain plateau. Dr. George M. Dawson<a name="FNanchor_55" id="FNanchor_55"></a><a href="#Footnote_55" class="fnanchor">[BC]</a> -is of the opinion that it did not, but that there was -<span class="pagenum"><a name="Page_97" id="Page_97">« 97 »</a></span> -a belt of a hundred miles or more, east of the Rocky Mountains, -which was never covered by true glacial ice. Mr. -Upham<a name="FNanchor_56" id="FNanchor_56"></a><a href="#Footnote_56" class="fnanchor">[BD]</a> is equally confident that the two ice-movements -became confluent, and united upon the western plateau of -Manitoba. The opportunity for such a difference of opinion -arises in the difficulty sometimes encountered of distinguishing -between a direct glacial deposit and a deposit -taking place in water containing boulder-laden icebergs. -Where Mr. Upham supposes the ice-fields of the east and -of the west to have been confluent in western Manitoba, -Dr. Dawson supposes there was an extensive subsidence of -the land sufficient to admit the waters of the ocean. Leaving -this question for the present undetermined, we will -now rapidly summarise the glacial phenomena west of the -third meridian from Washington (which corresponds nearly -with the western boundary of Pennsylvania), and east of -the Rocky Mountains.</p> - -<div class="footnote"> - -<p><a name="Footnote_55" id="Footnote_55"></a><a href="#FNanchor_55"><span class="label">[BC]</span></a> Transactions of the Royal Society of Canada, vol. viii, sec. iv, -pp. 54-74.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_56" id="Footnote_56"></a><a href="#FNanchor_56"><span class="label">[BD]</span></a> American Geologist, vol. vi, September, 1890; Bulletin of the -Geological Society of America, vol. ii, pp. 243-276.</p></div> - -<p>That the glacial movement extended to the southern -boundary just delineated is established by the presence -down to that line of all the signs of glacial action, and -their absence beyond. Glacial groovings are found upon -the freshly uncovered rock surfaces at frequent intervals -in close proximity to the line all along its course, while -granitic boulders from the far north are scattered, with -more or less regularity, over the whole intervening space -between this line and the Canadian highlands. I have -already referred to a boulder of jasper conglomerate found -in Boone County, Kentucky, which must have come from -unique outcroppings of this rock north of Lake Huron. -Granitic boulders from the Lake Superior region are also -found in great abundance at the extreme margin mentioned -in southern Illinois. West of the Missouri River -it is somewhat more difficult to delineate the boundary -<span class="pagenum"><a name="Page_98" id="Page_98">« 98 »</a></span> -with accuracy, on account of an enveloping deposit of fine -loam, technically called “loess.” Loess is very abundant -in the whole valley of the Missouri River below Yankton, -South Dakota, being for a long distance in the vicinity of -the river a hundred feet or more in depth. Over northern -Missouri and southern Illinois the deposit is nearly -continuous, but less in depth, and everywhere in that region -tends to hide from view the unstratified glacial deposit -continuously underlying it.</p> - -<p>A single instance of personal experience will illustrate -the condition of things. While going south from Chicago, -in search of the southern limit of glacial action, I stopped -off from the train at Du Quoin, about forty miles north -of where I subsequently found the boundary. Here the -whole surface was covered with loess, two or three feet in -depth. Below this was a gravelly soil, three or four feet -in thickness, which contained many scratched pebbles of -granite. A well which had recently been dug, reached -the rock at a depth of twenty feet, and revealed a beautifully -polished and scratched surface, betraying, beyond -question, the action of glacial ice. As we shall show a -little later, it is probable that, about the time the ice of -the Glacial period had reached its maximum development, -this area, which is covered with loess, was depressed in -level, and remained under water during a considerable -portion of the period when the ice-front was retreating.</p> - -<p><span class="pagenum"><a name="Page_99" id="Page_99">« 99 »</a></span></p> - -<div class="fig_center" style="width: 694px;"> -<a id="fig33" name="fig33"></a> -<img src="images/fig_33.png" width="694" height="358" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 33.</span>—Western face of the kettle-moraine, near Eagle, Waukesha County, Wisconsin. -(From a photograph by President T. C. Chamberlain, United States Geological Survey.)</div> -</div> - -<p><span class="pagenum"><a name="Page_100" id="Page_100">« 100 »</a></span></p> - -<p>To such an extent is this portion of the area included -in southern Iowa, northern Missouri, southern Illinois, -and the extreme southern portions of Indiana and Ohio -covered with loess, that it has been difficult to determine -the relation of its underlying glacial deposits to the more -irregular deposits found farther north. At an early period -of recent investigations, while making a geological survey -of the State of Wisconsin, President T. C. Chamberlin -fixed upon the line of moraine hills, which can be seen -upon <a href="#map_usa_glac">our map</a>, running southward between Green Bay -and Lake Michigan, and sweeping around in a curve to the -right, passing south of Madison and northward along the -line of Wisconsin River, and in another curve to the left, -around the southern end of Lake Michigan, as the “terminal -moraine of the second Glacial epoch.” In Wisconsin -the character of this line of moraine hills had been -discovered and described by Colonel Charles Whittlesey, in -1866. It was first named the “kettle-moraine,” because -of the frequent occurrence in it of “kettle-holes.” This -line of moraine hills has been traced with a great degree -of confidence across the entire glaciated area, as shown -upon our map, but it is not everywhere equally distinct, -and, as will be observed, follows a very irregular course.</p> - -<p>Beginning in Ohio we find it coinciding nearly with -the extreme glacial boundary until it reaches the valley of -the Scioto River, on the sixth meridian west from Washington, -where it begins to bear northward and continues -in that direction for a distance of sixty or seventy miles, -and then turns southward again in the valley of the -Miami, having formed between these two valleys a sort of -medial moraine.<a name="FNanchor_57" id="FNanchor_57"></a><a href="#Footnote_57" class="fnanchor">[BE]</a> A similar medial moraine had also been -noted by President Chamberlin between the valleys of the -Grand and Cuyahoga Rivers, in the eastern part of Ohio. -Indeed, for the whole distance across Ohio and Indiana, -this moraine occurs in a series of loops pointing to the -south, corresponding in general to the five gentle valleys -which mark the territory, namely, those of the Grand and -Mahoning Rivers; the Sandusky and Scioto Rivers; the -Great Miami River; the White River; and the Maumee -and Wabash Rivers. Everywhere, however, over this area -these morainic accumulations approximate pretty closely -to the extreme boundary of the glaciated region.</p> - -<div class="footnote"> - -<p><a name="Footnote_57" id="Footnote_57"></a><a href="#FNanchor_57"><span class="label">[BE]</span></a> See <a href="#map_usa_glac">map</a> at the beginning of the chapter.</p> -</div> - -<p>In Illinois President Chamberlin’s original determination -of the moraine fixed it near the southern end of Lake -<span class="pagenum"><a name="Page_101" id="Page_101">« 101 »</a></span> -Michigan, as shown upon our map, but Mr. Frank Leverett -has subsequently demonstrated that there is a concentric -series of moraines south of this, reaching across the State, -(but somewhat obscured by superficial accumulations of -loess referred to) and extending nearly to the latitude of -St. Louis.</p> - -<p>West of Wisconsin President Chamberlin’s “terminal -moraine of the second Glacial epoch” bends southward -through eastern Minnesota, and, sweeping down through -central Iowa, forms, near the middle of the northern part -of that State, a loop, having its southern extremity in the -vicinity of Des Moines. The western arm of this loop runs -through Minnesota in a northwesterly direction nearly -parallel with the upper portion of the valley of the Minnesota, -until reaching the latitude of the head-waters of that -river, where, in the vicinity of the Sisseton Agency, in -Dakota, it turns to the south by an acute angle, and makes -a loop in that State, extending to the vicinity of Yankton, -and with the valley of the James River as its axis. The -western arm of this loop follows pretty closely the line of -the eastern edge of the trough of the Missouri River, constituting -what is called the “Missouri Coteau,” which -continues on as a well-marked line of hills running in -a northwesterly direction far up into the Dominion of -Canada.</p> - -<p>One of the most puzzling glacial phenomena in the -Mississippi Valley is the driftless area which occupies the -southeastern portion of Minnesota, the southwestern part -of Wisconsin, and the northwestern corner of Iowa, as delineated -upon our map. This is an area which, while being -surrounded on every side by all the characteristic marks of -glaciation, is itself conspicuous for their entire absence. -Its rocks preserve no glacial scratches and are covered by -no deposits of till, while northern boulders avoided it in -their journey to more southern latitudes.</p> - -<p>The reason for all this is not evident in the topography -<span class="pagenum"><a name="Page_102" id="Page_102">« 102 »</a></span> -of the region. The land is not higher than that to the -north of it, nor is there any manifest protection to it by -the highlands south of Lake Superior. Nor yet is there -any reason to suppose that any extensive changes of level -in former times seriously affected its relations to the surrounding -country. Professor Dana, however, has called -attention to the fact that even now it is in a region of -comparatively light precipitation, suggesting that the -snow-fall over it may always have been insignificant in -amount. But this could scarcely account for the failure -of the great ice-wave of the north to overrun it. We are -indebted again to the sagacity of President Chamberlin in -suggesting the true explanation.</p> - -<p>By referring to the map it will be noticed that this -area sustains a peculiar relation to the troughs of Lake -Michigan and Lake Superior, while from the arrangements -of the moraines in front of these lakes it will be seen -that these lake basins were prominent factors in determining -the direction of the movement of the surplus ice from -the north. It is the more natural that they should do so -because of their great depth, their bottoms being in both -cases several hundred feet below the present water-level, -reaching even below the level of the sea.</p> - -<p>These broad, deep channels seem to have furnished the -readiest outlet for the surplus ice of the North, and so to -have carried both currents of ice beyond this driftless area -before they became again confluent. The slight elevation -south of Lake Superior served to protect the area on account -of the feebleness of direct movement made possible -by the strength of these diverging lateral ice-currents. -The phenomenon is almost exactly what occurs where a -slight obstruction in a river causes an eddy and preserves -a low portion of land below it from submergence. A -glance at the map will make it easily credible that an ice-movement -south of Manitoba, becoming confluent with -one from Lake Superior, pushed far down into the Missouri -<span class="pagenum"><a name="Page_103" id="Page_103">« 103 »</a></span> -Valley and spread eastward to the Mississippi River, -south of the unglaciated driftless area, and there became -confluent with a similar movement which had been directed -by the valleys of Lake Michigan and Lake Erie. -There can be little doubt that President Chamberlin’s explanation -is in the main correct, and we have in this another -illustration of the analogy between the behaviour of -moving ice and that of moving water.</p> - -<div class="fig_center" style="width: 376px;"> -<a id="fig34" name="fig34"></a> -<img src="images/fig_34.png" width="376" height="378" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 34.</span>—Section of the east-and-west glacial furrows, on Kelly’s Island, preserved -by Mr. Younglove. Fine sediment rests immediately on the rock, -with washed pebbles at the surface.</div> -</div> - -<p>The accompanying illustrations will give a better idea -than words can do of the celebrated glacial grooves on the -hard limestone islands near Sandusky, in the western part -<span class="pagenum"><a name="Page_104" id="Page_104">« 104 »</a></span> -of Lake Erie. Through the interest aroused in them by -an excursion of the American Association for the Advancement -of Science, while meeting in Cleveland, Ohio, -in 1888, the Kelly Island Lime and Transport Company, -of which Mr. M. C. Younglove is the president, has been -induced to deed to the Western Reserve Historical Society -for preservation a portion of one of the most remarkable -of the grooves still remaining.</p> - -<p>The portion of the groove preserved is thirty-three -feet across, and the depth of the cut in the rock is seventeen -feet below the line, extending from rim to rim. -Originally there was probably here a small depression -formed by preglacial water erosion, into which the ice -crowded the material, which became its graving-tool, and -so the rasping and polishing went on in increasing degree -until this enormous furrow is the result. The groove, -however, is by no means simple, but presents a series of -corrugations merging into each other by beautiful curves. -When exposed for a considerable length it will resemble -nothing else so much as a collection of prostrate Corinthian -columns lying side by side on a concave surface.</p> - -<p>The direction of these grooves is a little south of west, -corresponding to that of the axis of the lake. This is -nearly at right angles to the course of the ice-scratches on -the summit of the water-shed south of this, between the -lake and the Ohio River. The reason for this change of -direction can readily be seen by a little attention to the -physical geography. The highlands to the south of the -lake rise about seven hundred feet above it. When the -Ice period was at its climax and overran these highlands, -the ice took its natural course at right angles to the terminal -moraine and flowed southeast according to the direction -indicated by the scratches on the summit; but when -the supply of ice was not sufficient to overrun the highlands, -the obstruction in front turned the course and the -resultant was a motion towards Toledo and the Maumee -Valley, where in the vicinity of Fort Wayne an extensive -terminal moraine was formed.</p> - -<p><span class="pagenum"><a name="Page_105" id="Page_105">« 105 »</a></span></p> - -<div class="fig_center" style="width: 694px;"> -<a id="fig35" name="fig35"></a> -<img src="images/fig_35.png" width="694" height="391" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 35.</span>—Same as the preceding. (Courtesy of M. C. Younglove.)</div> -</div> - -<p><span class="pagenum"><a name="Page_106" id="Page_106">« 106 »</a></span></p> - -<p>The much-mooted question of a succession of glacial -epochs finds the most of its supporting facts in the portion -of the glaciated area lying west of Pennsylvania. -That there have been frequent oscillations of the glacial -front over this area is certain. But it is a question -whether the glacial deposits south of this distinct line of -moraine hills are so different from those to the north of -it as to necessitate the supposition of two entirely distinct -glacial epochs. This can be considered most profitably -here.</p> - -<p>The following are among the points with reference to -which the phenomena south of the moraine just delineated -differ from those north of the line:</p> - -<p>1. The glacial deposits to the south appear to be distributed -more uniformly than those to the north. To the -north the drift is often accumulated in hills, and is dotted -over with kettle-holes, while to the south these are pretty -generally absent. Any one travelling upon a line of railroad -which traverses these two portions of the glaciated -area as indicated upon our map can easily verify these -statements.</p> - -<p>2. The amount of glacial erosion seems to be much -less south of the line of moraine hills delineated than -north of them. Still, glacial striæ are found, almost everywhere, -close down to the extreme margin of the glaciated -area.</p> - -<p>3. The gravel deposits connected with the drainage of -the Glacial period are much less abundant south of the -so-called “terminal moraine of the second Glacial period” -than they are north of it. South of this moraine the -water deposits attributed to the Glacial period are of such -fine silt as to indicate slow-moving currents over a gentle -low slope of the surface.</p> - -<p>4. The glacial deposits to the south are more deeply -<span class="pagenum"><a name="Page_107" id="Page_107">« 107 »</a></span> -coloured than those to the north, showing that they have -been longer exposed to oxidising agencies. Even the -granitic boulders show the marks of greater age south of -this line, being disintegrated to a greater extent than -those to the north.</p> - -<p>5. And, finally, there occur, over a wide belt bordering -the so-called moraine hills of the second Glacial epoch, -extensive intercalated beds of vegetal deposits. Among -the earliest of these to be discovered were those of Montgomery -County, Ohio, where, in 1870, Professor Orton, of -the Ohio Survey, found at Germantown a deposit of peat -fourteen feet thick underneath ninety-five feet of till, and -there seem also to be glacial deposits underneath the peat -as well as over it. The upper portion of the peat contains -“much undecomposed sphagnous mosses, grasses, and -sedges, and both the peat and the clayey till above it” -contain many fragments of coniferous wood which can be -identified as red cedar (<i>Juniperus Virginianus</i>). In numerous -other places in that portion of Ohio fresh-appearing -logs, branches, and twigs of wood are found underneath -the till, or mingled with it, much as boulders are. -Near Darrtown, in Butler County, Ohio, red cedar logs -were found under a covering of sixty-five feet of till, and -so fresh that the perfume of the wood is apparently as -strong as ever. Similar facts occur in several other counties -in the glaciated area of southern Ohio and southern -Indiana. Professor Collett reports that all over southwestern -Indiana peat, muck, rotted stumps, branches, and -leaves of trees are found from sixty to one hundred and -twenty feet below the surface, and that these accumulations -sometimes occur to a thickness of from two to -twenty feet.</p> - -<p><span class="pagenum"><a name="Page_108" id="Page_108">« 108 »</a></span></p> - -<div class="fig_center" style="width: 387px;"> -<a id="fig36" name="fig36"></a> -<img src="images/fig_36.png" width="387" height="508" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 36.</span>—Section of till near Germantown, Ohio, overlying thick bed of peat. -The man in the picture stands upon a shelf of peat from which the till has -been eroded by the stream. The dark spot at the right hand of the picture, -just above the water, is an exposure of the peat. The thickness of the till is -ninety-five feet. The partial stratification spoken of in the text can be seen -about the middle of the picture. The furrows up and down had been made -by recent rains. (United States Geological Survey.) (Wright.)</div> -</div> - -<p>Farther to the northwest similar phenomena occur. -Professor N. H. Winchell has described them most particularly -in Fillmore and Mower Counties, Minnesota, -from which they extend through a considerable portion of -Iowa. In the above counties of Minnesota a stratum of -peat from eighteen inches to six or eight feet in thickness, -with much wood, is pretty uniformly encountered in digging -<span class="pagenum"><a name="Page_109" id="Page_109">« 109 »</a></span> -wells, the depth varying from twenty to fifty feet. -This county is near the highest divide in the State of Minnesota, -and from it “flow the sources of the streams to the -north, south, and east.” The wood encountered in this -stratum indicates the prevalence f coniferous trees, and -the peat mosses indicate a cool and moist climate.</p> - -<p>Nor are intercalated vegetable deposits absent from the -vast region farther north over the area that drains into -Hudson Bay. At Barnesville, in Clay County, Minnesota, -which lies in the valley of the Red River of the North, and -also in Wilkin County in the same valley, tamarack wood -and sandy black mud containing many snail-shells have -been found from eight to twelve feet below a surface of -till; and Dr. Robert Bell reports the occurrence of limited -deposits of lignite between layers of till, far to the northwest, -in Canada, and even upon the southern part of Hudson -Bay; while Mr. J. B. Tyrrell reports<a name="FNanchor_58" id="FNanchor_58"></a><a href="#Footnote_58" class="fnanchor">[BF]</a> many indications -of successive periods of glaciation near the northern -end of the Duck Mountain. The most characteristic indications -which he had witnessed consisted of stratified -beds of silt, containing fresh-water shells, with fragments -of plants and fish similar to those living in the lakes of -the region at the present time.</p> - -<div class="footnote"> - -<p><a name="Footnote_58" id="Footnote_58"></a><a href="#FNanchor_58"><span class="label">[BF]</span></a> Bulletin of the Geological Society of America, vol. i, pp. 395-410.</p></div> - -<p>Reviewing these facts with reference to their bearing -upon the point under consideration, we grant, at the outset, -that they do indicate a successive retreat and readvance -of the ice over extensive areas. This is specially -clear with respect to the vegetal deposits interstratified -with beds of glacial origin. But the question at issue -concerning the interpretation of these phenomena is, Do -they necessarily indicate absolutely distinct glacial epochs -separated by a period in which the ice had wholly disappeared -from the glaciated area to the north? That they -<span class="pagenum"><a name="Page_110" id="Page_110">« 110 »</a></span> -do, is maintained by President Chamberlin and many others -who have wide acquaintance with the facts. That -they do not certainly indicate a complete disappearance -of the ice during an extensive interglacial epoch, is capable, -however, of being maintained, without forfeiting one’s -rights to the respect of his fellow-geologists. The opposite -theory is thus stated by Dr. Robert Bell: “It appears -as if all the phenomena might be referred to one general -Glacial period, which was long continued, and consequently -accompanied by varying conditions of temperature, -regional oscillations of the surface, and changes in -the distributions of sea and land, and in the currents in -the ocean. These changes would necessarily give rise to -local variations in the climate, and might permit of vegetation -for a time in regions which need not have been far -removed from extensive glaciers.”<a name="FNanchor_59" id="FNanchor_59"></a><a href="#Footnote_59" class="fnanchor">[BG]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_59" id="Footnote_59"></a><a href="#FNanchor_59"><span class="label">[BG]</span></a> Bulletin of the Geological Society of America, vol. i, pp. 287-310.</p></div> - -<p>At my request, Professor J. E. Todd, of Iowa, whose -acquaintance with the region is extensive, has kindly written -out for me his conclusions upon this subject, which I -am permitted to give in his own words:</p> - -<p>“I am not prepared to write as I would like concerning -the forest-beds and old soils. I will, however, offer -the following as a partial report. I have come to think -that there is considerable confusion on the subject. I believe -there are five or six different things classed under -one head.</p> - -<p>“1. <i>Recent Much and Soils.</i>—The finest example I have -found in the whole Missouri Valley was twenty feet below -silt and clay, in a basin inside the outer moraine, near -Grand View, South Dakota. From my examination of -the reported old soil near Albia, Iowa, I think the most -rational way of reconciling the conflicting statements concerning -it is that it also belongs to this class.</p> - -<p><span class="pagenum"><a name="Page_111" id="Page_111">« 111 »</a></span></p> - -<p>“2. <i>Peat or Soil under Loess.</i>—This does not signify -much if the loess was formed in a lake subject to orographic -oscillations, or if, as I am coming to believe, -it is a fluviatile deposit of an oscillating river like the -Hoang-Ho on the great Chinese plain. It at least does -not mean an interglacial epoch.</p> - -<p>“3. <i>Wood and Dirt rearranged, not in situ.</i>—This -occurs either in subaqueous or in subglacial deposits. I -have found drift-wood in the lower layers of the loess -here, but not <i>in situ</i>. I have frequently found traces of -wood in till in Dakota, but always in an isolated way. I -think, from reading statements about the deposits in eastern -Iowa, that most if not all of the cases are of this -sort. Two things have conspired to lead to this error: -one, the influence of Croll’s speculation; and the other, -the easy inference of many well-diggers, and especially -well-borers, that what they pass through are always in -layers. In this way a log becomes a forest-bed. Scattered -logs and muck fragments occurring frequently in a -region, though at different levels, are readily imagined by -an amateur geologist to be one continuous stratum antedating -the glacier or floods (as the case may be in that -particular region), when, in fact, it has been washed down -from the margin of the transporting agent and is contemporaneous -with it. I suspect the prevalence of wood -in eastern Iowa may be traced to a depression of the -driftless region during the advance of the glacier, so as to -bring the western side of that area more into the grasp -of glacial agencies.</p> - -<p>“4. <i>Peat between Subglacial Tills.</i>—If cases of this sort -are found, they are in Illinois, Indiana, and Ohio. Professor -Worthen insisted that there were no interglacial -soils or forest-beds in Illinois; and in the cases mentioned -in the State reports he repeatedly explains the sections -given by his assistants, so as to harmonize them with that -statement. I think he usually makes his explanations -<span class="pagenum"><a name="Page_112" id="Page_112">« 112 »</a></span> -plausible. He was very confident in referring most of -them, to preglacial times. His views, I suppose, will be published -in the long-delayed volume, now about to be issued.</p> - -<p>“5. <i>Vegetable Matter between Glacial Till and Underlying -Berg Till or other Drift Deposits.</i>—When one remembers -that the front of the great ice-sheet may have been as -long in reaching its southern boundary as in receding -from it, and with as many advance and retrograde movements, -we can easily believe that much drift material -would have outrun the ice and have formed deposits so far -ahead of it that vegetation would have grown before the -ice arrived to bury it.</p> - -<p>“6. <i>Preglacial Soils, etc.</i>—I believe that this will be -found to include most in southern Ohio, if not in Illinois, -as Worthen claimed.”</p> - -<p>The phenomena of the Glacial period are too vast -either to have appeared or to have disappeared suddenly. -By whatever cause the great accumulation of ice was produced, -the advance to the southward must have been slow -and its disappearance must have been gradual, though, as -we shall show a little later, the final retreat of the ice-front -occupied but a short time relatively to the whole -period which has elapsed since. As we shall show also, -the advent of the Ice period was probably preceded and -accompanied by a considerable elevation of the northern -part of the continent Whether this elevation was contemporaneous -upon both sides of the continent is perhaps -an open question; but with reference to the area east of the -Rocky Mountains, which is now under consideration, the -centre of elevation was somewhere south of Hudson Bay. -Putting together what we know, from the nature of the -case, concerning the accumulation and movement of glacial -ice, and what we know from the relics of the great -glacial invasion, which have enabled us to determine its -extent and the vigour of its action, the course of events -seems to have been about as follows:</p> - -<p><span class="pagenum"><a name="Page_113" id="Page_113">« 113 »</a></span></p> - -<p>Throughout the Tertiary period a warm climate had -prevailed over British America, Greenland, and indeed -over all the lands in proximity to the north pole, so far as -explorers have been able to penetrate them. The vegetation -characterizing these regions during the Tertiary -period indicates a temperature about like that which now -prevails in North Carolina and Virginia. Whatever may -be said in support of the theory that the Glacial period -was produced by astronomical causes, in view of present -facts those causes cannot be regarded as predominant; at -most they were only co-operative. The predominant -cause of the Glacial period was probably a late Tertiary -or post-Tertiary elevation of the northern part of the -continents, accompanied with a subsidence in the central -portion. Of such a subsidence in the Isthmus of -Panama indications are thought to be afforded by the -occurrence of late Tertiary or, more probably, post-Tertiary -sea-shells at a considerable elevation on the divide -along the Isthmus of Panama, between the Atlantic and -Pacific Oceans. Of this we shall speak more fully in a -later chapter.</p> - -<p>Fixing our thoughts upon what is known as the Laurentian -plateau, which, though now in the neighbourhood -of but two thousand feet above the sea, was then much -higher, we can easily depict in imagination the beginnings -of the great “Laurentide Glacier,” which eventually -extended to the margin already delineated on the south -and southwest in the United States, and spread northward -and eastward over an undetermined area. Year -after year and century after century the accumulating -snows over this elevated region consolidated into glacial -ice and slowly pushed outward the surplus reservoirs of -cold. For a long time this process of ice-accumulation -may have been accompanied by the continued elevation -of the land, which, together with the natural effect of the -enlarging area of ice and snow, would tend to lower the -<span class="pagenum"><a name="Page_114" id="Page_114">« 114 »</a></span> -temperature around the margin and to increase still more -the central area of accumulation.</p> - -<p>The vigour of movement in any direction was determined -partly by the shape of the valleys opening southward -in which the ice-streams would naturally concentrate, -and partly by those meteorological conditions which -determine the extent of snow-fall over the local centres -of glacial dispersion. For example, the general map of -North America in the Ice period indicates that there -were two marked subcentres of dispersion for the great -Laurentide Glacier, the eastern one being in Labrador -and the western one north of Lake Superior. In a -general way the southern boundary of the glaciated region -in the United States presents the appearance of portions -of two circumferences of circles intersecting each -other near the eastern end of Lake Erie. These circles, I -am inclined to believe, represent the areas over which a -semi-fluid (or a substance like ice, which flows like a semi-fluid) -would disperse itself from the subcentres above -mentioned.</p> - -<p>A study of the contour of the country shows that that -also, in a general way, probably had something to do with -the lines of dispersion. The western lobe of this glaciated -area corresponds in its boundary pretty closely with the -Mississippi Valley, having the Ohio River approximately -as its eastern arm and the Missouri as its western, with -the Mississippi River nearly in its north and south axis. -The eastern lobe has its farthest extension in the axis of -the Champlain and Hudson River Valleys, its western -boundary being thrown more and more northward as the -line proceeds to the west over the Alleghany Mountains -until reaching the longitude of the eastern end of Lake -Erie; but this southern boundary is by no means a water-level, -nor is the contour of the country such that it could -ever have been a water-level. But it conforms in nearly -every particular to what would be the resultant arising -<span class="pagenum"><a name="Page_115" id="Page_115">« 115 »</a></span> -from a pretty general southward flow of a semi-fluid from -the two subcentres mentioned, meeting with the obstructions -of the Adirondacks in northern New York and of -the broader Appalachian uplift in northern Pennsylvania.</p> - -<p>How far south the area of glacial accumulation may -have extended cannot be definitely ascertained, but doubtless -at an early period of the great Ice age the northern -portions of the Appalachian range in New York, New -England, New Brunswick, and Nova Scotia became themselves -centres of dispersion, while only at the height of -the period did all their glaciers become confluent, so that -there was one continuous ice-sheet.</p> - -<p>In the western portion of the area covered by the Laurentide -Glacier, the depression occupied by the Great -Lakes, especially Lakes Michigan and Superior, evidently -had a marked influence in directing the flow of ice during -the stages which were midway between the culmination -of the Ice period and both its beginning and its end. -This would follow from the great depth of these lakes, -the bottom of Lake Michigan being 286 feet below sea-level, -and that of Lake Superior 375 feet, making a total -depth of water of about 900 and 1,000 feet respectively. -Into these oblong depressions the ice would naturally -gravitate until they were filled, and they would become -the natural channels of subsequent movement in the direction -of their longest diameters, while the great thickness -of ice in them would make them the conservative -centres of glacial accumulation and action after the ice -had begun to retreat.</p> - -<p>These deductions from the known nature of ice and -the known topography of the region are amply sustained -by a study of the detailed map showing the glacial geology -in the United States. But on this we can represent -indeed only the marks left by the ice at various stages of -its retreat, since, as already remarked, the marks of each -stage of earlier advance would be obliterated by later forward -<span class="pagenum"><a name="Page_116" id="Page_116">« 116 »</a></span> -movements. We may presume, however, that in -general the marks left by the retreating ice correspond -closely with those actually made and obliterated by the -advancing movement.</p> - -<p>From observations upon the glaciers of Switzerland -and of Alaska, it is found that neither the advance nor -the retreat of these glaciers is constant, but that, in obedience -to meteorologic agencies not fully understood, -they advance and retreat in alternate periods, at one time -receding for a considerable distance, and at other times -regaining the lost ground and advancing over the area -which has been uncovered by their retreat.</p> - -<p>“M. Forel reports, from the data which he has collected -with much care, that there have been in this century -five periods in the Alpine glaciers: of enlargement, -from 1800 (?) to 1815; of diminution, from 1815 to -1830; of enlargement, from 1830 to 1845; of diminution, -from 1845 to 1875; and of enlargement again, from 1875 -onward. He remarks further that these periods correspond -with those deduced by Mr. C. Lang for the variations -for the precipitations and temperature of the air; -and, consequently, that the enlargement of the glaciers -has gone forward in the cold and rainy period, and the -diminution in the warm and the dry.”<a name="FNanchor_60" id="FNanchor_60"></a><a href="#Footnote_60" class="fnanchor">[BH]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_60" id="Footnote_60"></a><a href="#FNanchor_60"><span class="label">[BH]</span></a> American Journal of Science, vol. cxxxii, 1886, p. 77.</p></div> - -<p>When, now, we attentively consider the combination -of causes necessary to produce the climatic conditions of -the great Ice age of North America, we shall be prepared -to find far more extensive variations in the progress of -the continental glacier, both during its advance and during -its retreat, than are to be observed in any existing -local glaciers.</p> - -<p>With respect to the arguments adduced in favor of a -succession of glacial epochs in America the following -criticisms are pertinent:</p> - -<p><span class="pagenum"><a name="Page_117" id="Page_117">« 117 »</a></span></p> - -<p>1. So far as we can estimate, a temporary retreat of -the front, lasting a few centuries, would be sufficient to -account for the vegetable accumulations that are found -buried beneath the glacial deposits in southern Ohio, Indiana, -central Illinois, and Iowa, while a temporary readvance -of the ice would be sufficient to bury the vegetable -remains beneath a freshly accumulated mass of till. -Thus, as Dr. Bell suggested, the interglacial vegetal deposits -do not necessarily indicate anything more than a -temporary oscillation of the ice-front, and do not carry -with them the necessity of supposing a disappearance of -the ice from the whole glaciated area. Thus the introduction -of a whole Glacial period to account for such limited -phenomena is a violation of the well-known law of parsimony, -which requires us in our explanations of phenomena -to be content with the least cause which is sufficient to -produce them. In the present instance a series of comparatively -slight oscillations of the ice-front during a -single glacial period would seem to be sufficient to account -for all the buried forests and masses of vegetal -<i>débris</i> that occur either in the United States or in the -Dominion of Canada.</p> - -<p>2. Another argument for the existence of two absolutely -distinct glacial periods in North America has been -drawn from the greater oxidation of the clays and the -more extensive disintegration of certain classes of the boulders -found over the southern part of the glaciated area of -the Mississippi Valley, than has taken place in the more -northerly regions. Without questioning this statement -of fact (which, however, I believe to be somewhat exaggerated), -it is not difficult to see that the effects probably -are just what would result from a single long glacial period -brought about by such causes as we have seen to be -probably in operation in America. For if one reflects -upon the conditions existing when the Glacial period began, -he will see that, during the long ages of warm climate -<span class="pagenum"><a name="Page_118" id="Page_118">« 118 »</a></span> -which characterised the preceding period, the rocks -must have been extensively disintegrated through the -action of subaërial agencies. The extent to which this -disintegration takes place can be appreciated now only -by those who reside outside of the glaciated area, where -these agencies have been in uninterrupted action. In the -Appalachian range south of the glaciated region the granitic -masses and strata of gneiss are sometimes found to be -completely disintegrated to a depth of fifty or sixty feet; -and what seem to be beds of gravel often prove in fact to -be horizontal strata of gneiss from which the cementing -material has been removed by the slow action of acids -brought down by the percolating water.</p> - -<p>Now, there can be no question that this process of -disintegration had proceeded to a vast extent before the -Glacial period, so that, when the ice began to advance, -there was an enormous amount of partially oxidised and -disintegrated material ready to be scraped off with the -first advance of ice, and this is the material which would -naturally be transported farthest to the south; and thus, -on the theory of a single glacial period, we can readily account -for the greater apparent age of the glacial <i>débris</i> -near the margin. This <i>débris</i> was old when the Glacial -period began.</p> - -<p>3. With reference to the argument for two distinct -glacial periods drawn from the smaller apparent amount -of glacial erosion over the southern part of the glaciated -area, we have to remark that that would occur in case of -a single ice-invasion as well as in case of two distinct ice-invasions, -in which the later did not extend so far as -the former.</p> - -<p>From the very necessity of the case, glacial erosion -diminishes as the limit of the extent of the glaciation is -approached. At the very margin of the glacier, motion -has ceased altogether. Back one mile from the margin -only one mile of ice-motion has been active in erosion, -<span class="pagenum"><a name="Page_119" id="Page_119">« 119 »</a></span> -while ten miles back from its front there has been ten -times as much moving ice actually engaged in erosion, -and in the extreme north several hundred times as much -ice, Thus it is evident that we do not need to resort to -two glacial periods to account for the relatively small -amount of erosion exhibited over the southern portion of -our glaciated area.</p> - -<p>At the same time, it should be said that the indications -of active glacial erosion near the margin are by no -means few or small. In Lawrence County, Pennsylvania, -on the very margin of the glaciated area, Mr. Max Foshay<a name="FNanchor_61" id="FNanchor_61"></a><a href="#Footnote_61" class="fnanchor">[BI]</a> -has discovered very extensive glacial grooves, indicating -much vigour of ice-action even beyond the more extensive -glacial deposits which Professor Lewis and myself had -fixed upon as the terminal moraine. In Highland and -Butler Counties, Ohio, and in southwestern Indiana and -southern Illinois, near the glacial margin, glacial grooves -and striæ are as clear and distinct in many cases as can -anywhere be found; while upon the surface of the limestone -rocks within the limits of the city of St. Louis, -where the glacial covering is thin, and where disintegrating -agencies had had special opportunities to work, I -found very clear evidences of a powerful ice-movement, -which had planed and scratched the rock surface; and -at Du Quoin, Illinois, as already related, the fragments -thrown up from the surface of the rock, fifty or sixty feet -below the top of the soil, were most beautifully planed -and striated. It should be observed, also, that this whole -area is so deeply covered with <i>débris</i> that the extent of -glacial erosion underneath is pretty generally hid from -view.</p> - -<div class="footnote"> - -<p><a name="Footnote_61" id="Footnote_61"></a><a href="#FNanchor_61"><span class="label">[BI]</span></a> Bulletin of the Geological Society, vol. ii, pp. 457-464.</p></div> - -<p>4. The uniformity of the distribution of the glacial -deposits over the southern portion of the glaciated area in -the Mississippi Valley is partly an illusion, due to the -<span class="pagenum"><a name="Page_120" id="Page_120">« 120 »</a></span> -fact that there was a vast amount of deposition by water -over that area during the earlier stages of the ice-retreat. -This has been due partly to the gentler slope which would -naturally characterise the borders of an area of elevation, -and partly to an extensive subsidence which seems to have -begun soon after the ice had reached its farthest extent of -motion.</p> - -<p>It should be borne in mind that at all times a glacier -is accompanied by the issue of vast streams of water from -its front, and that these of course increase in volume when -the climax has been reached and the ameliorating influences -begin to melt away the accumulated mass of ice -and to add the volume of its water to that produced by -ordinary agencies. As these subglacial streams of water -poured out upon the more gentle slopes of the area in -front of the ice, they would distribute a vast amount of -fine material, which would settle into the hollow places -and tend to obscure the irregularities of the previous direct -glacial deposit.</p> - -<p>Such an instance came clearly under my own observation -in the vicinity of Yankton, in South Dakota, where, -upon visiting a locality some miles from any river, and to -which workmen were resorting for sand, I found that the -deposit occupied a kettle-hole, filling it to its brim, and -had evidently been superimposed by a temporary stream of -water flowing over the region while the ice was still in -partial occupation of it. Thus, no doubt, in many cases, -the original irregularities of the direct glacial deposits -have been obliterated, even where there has been no general -subsidence.</p> - -<p>But, in the area under consideration, the loess, or -loam, is so extensive that it is perhaps necessary to suppose -that the central portions of the Mississippi Valley -were subjected to a subsidence amounting to about five -hundred feet; so that the glacial streams from the retreating -ice-front met the waters of the ocean in southern -<span class="pagenum"><a name="Page_121" id="Page_121">« 121 »</a></span> -Illinois and Indiana; thus accounting for the extensive -fine silt which has done so much over that region to -obscure the glacial phenomena.</p> - - -<p class="caption3nb"><i>West of the Rocky Mountains.</i></p> - -<p>The glacial phenomena in the United States west of -the Rocky Mountains must be treated separately, since -American geologists have ceased to speak of an all-pervading -ice-cap extending from the north pole. But, as -already said, the glaciation of North America has proceeded -from two definite centres of ice-accumulation, one of -which we have been considering in the pages immediately -preceding. The great centre of glacial dispersion east of -the Rocky Mountains is the region south of Hudson Bay, -and the vast ice-field spreading out from that centre is -appropriately named the Laurentide Glacier. The movement -of ice in this glacial system was outward in all -directions from the Laurentian hills, and extended west -several hundred miles, well on towards the eastern foot of -the Rocky Mountains.</p> - -<p>The second great centre of glacial dispersion occupies -the vast Cordilleran region of British Columbia, reaching -from the Rocky Mountains on the northeast to the Coast -Range of the Pacific on the southwest, a width of four -hundred miles. The length is estimated by Dr. Dawson -to be twelve hundred miles. The principal centre of ice-accumulation -lies between the fifty-fifth and the fifty-ninth -parallel. From this centre the movement was in -all directions, but chiefly to the northwest and to the -south. The movement of the Cordilleran glaciers extended -northwest to a distance of three hundred and -fifty miles, leaving their moraines far down in the Yukon -Valley on the Lewes and Pelly Rivers.<a name="FNanchor_62" id="FNanchor_62"></a><a href="#Footnote_62" class="fnanchor">[BJ]</a> Southward the -<span class="pagenum"><a name="Page_122" id="Page_122">« 122 »</a></span> -Cordilleran Glacier moved to a distance of six hundred -miles, extending to the Columbia River, in the eastern -part of the State of Washington.</p> - -<div class="footnote"> - -<p><a name="Footnote_62" id="Footnote_62"></a><a href="#FNanchor_62"><span class="label">[BJ]</span></a> See George M. Dawson, in Science, vol. xi, 1888, p. 186, and -American Geologist, September, 1890, pp. 153-162.</p></div> - -<p>From this centre, also, the ice descended to the sea-level -upon the west, and filled all the channels between -Vancouver’s Island and the mainland, as well as those in -the Alexander Archipelago of Alaska. South of Vancouver’s -Island a glacier pushed out through the straits of -Juan de Fuca to an unknown distance. All the islands -in Puget Sound are composed of glacial <i>débris</i>, resembling -in every respect the terminal moraines which have -been described as constituting many of the islands south -of the New England coast. The ice-movement in Puget -Sound, however, was probably northward, resulting from -glaciers which are now represented by their diminutive -descendants on the flanks of Mount Rainier.</p> - -<p>South of the Columbia River the country was never -completely enveloped by the ice, but glaciers extended far -down in the valleys from all the lofty mountain-peaks. In -Idaho there are glacial signs from the summit of the Rocky -Mountains down to the westward of Lake Pend d’Oreille. -In the Yellowstone Park there are clear indications that -the whole area was enveloped in glacial ice. An immense -boulder of granite, resting upon volcanic deposits, may be -found a little west of Inspiration Point, on the Yellowstone -Cañon. Abundant evidences of glacial action are -also visible down the Yellowstone River to the vicinity of -Livingston, showing that that valley must have been -filled with glacial ice to a depth of sixteen hundred feet. -To the west the glaciers from the Yellowstone Park extended -to the border of Idaho, where a clearly marked -terminal moraine is to be found in the Tyghee Pass, leading -over from the western fork of the Madison River into -Lewis Fork of the Snake River. South of Yellowstone -Park the Teton Mountains were an important centre for -the dispersion of local glaciers, but they did not descend -<span class="pagenum"><a name="Page_123" id="Page_123">« 123 »</a></span> -upon the western side much below the 6,000-foot level, -and only barely came to the edge of the great Snake -River lava plains. To the east the movement from the -Teton Mountains joined that from various other lofty -mountains, where altogether they have left a most intricate -system of glacial deposits, in whose reticulations Jackson’s -Lake is held in place.</p> - -<div class="fig_center" style="width: 378px;"> -<a id="fig37" name="fig37"></a> -<img src="images/fig_37.png" width="378" height="339" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 37.</span>—Moraines of Grape Creek, Sangre del Cristo Mountains, Colorado (after -Stevenson).</div> -</div> - -<p>In Utah extensive glaciers filled all the northern valleys -of the Uintah Mountains, and extended westward in -the Wahsatch range to the vicinity of Salt Lake City. -The mountain region of Colorado, also, had its glaciers, -occupying the head-waters of the Arkansas, the Platte, the -Gunnison, and the Grand Rivers. The most southern -point in the Rocky Mountains at which signs of local -glaciers have been noted is near the summits of the San -<span class="pagenum"><a name="Page_124" id="Page_124">« 124 »</a></span> -Juan range, in southwestern Colorado. Here a surface of -about twenty-five square miles, extending from an elevation -of 12,000 feet down to 8,000 feet, shows every sign of -the former presence of moving ice. The greater part of -the glaciation in Colorado is confined to elevations above -10,000 feet.</p> - -<p>The whole range of the Sierra Nevada through Oregon, -and as far south as the Yosemite Valley in California, -formerly sustained glaciers of far greater size than -any which are now found in those mountains. In general -these glaciers were much longer on the western side of the -Sierra Nevada than on the eastern. On the eastern side -glaciers barely came down to Lake Tahoe and Lake Mono -in California. The State of Nevada seems to have been -entirely free from glaciers, although it contains numerous -mountain-peaks more than ten thousand feet high. -In the Yosemite Cañon glaciers extended down the Merced -River to the mouth of the cañon; while in the Tuolumne -River, a few miles to the north, the glaciers which -still linger about the peaks of Mount Dana filled the valley -for a distance of forty miles.</p> - -<p>It is a question among geologists whether or not the -glaciation west of the Rocky Mountains was contemporaneous -with that of the eastern part of the continent. -The more prevalent opinion among those who have made -special study of the phenomena is that the development of -the Cordilleran glaciers was independent of that of the -Laurentide system. At any rate, the intense glaciation of -the Pacific coast seems to have been considerably later than -that of the Atlantic region. Of this we will speak more -particularly in discussing the questions of the date and -the cause of the Glacial period. It is sufficient for us -here simply to say that, from his extensive field observations -throughout the Cordilleran region, Dr. George M. -Dawson infers that there have been several successive alternations -of level on the Pacific coast corresponding to -<span class="pagenum"><a name="Page_125" id="Page_125">« 125 »</a></span> -successive glacial and interglacial epochs, and that when -there was a period of elevation west of the Rocky Mountains -there was a period of subsidence to the east, and <i>vice -versa</i>. In short, he supposes that the east and west for a -long time played a game of seesaw, with the Rocky -Mountains as the fulcrum. We give his scheme in tabulated -form.</p> - -<p><span class="pagenum"><a name="Page_126" id="Page_126">« 126 »</a></span></p> - - -<p class="center pmt2 pmb2"><i>Scheme of Correlation of the Phenomena of the Glacial -Period in the Cordilleran Region and in the Region of the Great Plains.</i></p> - -<div class="regions"> -<table summary="regions"> -<tr> - <td class="center" style="width: 45%">CORDILLERAN REGION.</td> - <td class="center" style="width: 45%">REGION OF THE GREAT PLAINS.</td> -</tr> -<tr> - <td><p>Cordilleran zone at a high elevation. Period of most severe - glaciation and maximum development of the great Cordilleran Glacier.</p></td> - <td><p>Correlative subsidence and submergence of the great plains, - with possible contemporaneous increased elevation of the - Laurentian axis and maximum development of ice upon it. - Deposition of the lower boulder-clay of the plains.</p></td> -</tr> -<tr> - <td><p>Gradual subsidence of the Cordilleran region and decay of the - great glacier, with deposition of the boulder-clay of the interior - plateau and the Yukon basin, of the lower boulder-clay of the littoral - and probably also, at a later stage (and with greater submergence), of - the interglacial silts of the same region.</p></td> - <td><p>Correlative elevation of the western part, at least, of the - great plains, which was probably more or less irregular and led to - the production of extensive lakes in which interglacial deposits, - including peat, were formed.</p></td> -</tr> -<tr> - <td><p>Re-elevation of the Cordilleran region to a level probably as high - as or somewhat higher than the present. Maximum of second period - of glaciation.</p></td> - <td><p>Correlative subsidence of the plains, which (at least in the - western part of the region) exceeded the first subsidence and - extended submergence to the base of the Rocky Mountains near the - forty-ninth parallel. Formation of second boulder-clay, and (at a - later stage) dispersion of large erratics.</p></td> -</tr> -<tr> - <td><p>Partial subsidence of the Cordilleran region, to a level - about 2,500 feet lower than the present. Long stage of stability. - Glaciers of the second period considerably reduced. Upper - boulder-clay of the coast probably formed at this time, though perhaps - in part during the second maximum of glaciation.</p></td> - <td><p>Correlative elevation of the plains, or at least of their - western portion, resulting in a condition of equilibrium as between - the plains and the Cordillera, their <i>relative</i> levels - becoming nearly as at present. Probable formation of the Missouri - coteau along a shore-line during this period of rest.</p></td> -</tr> -<tr> - <td><p>Renewed elevation of the Cordilleran region, with one - well-marked pause, during which the littoral stood about 200 feet lower - than at present. Glaciers much reduced, and diminishing in - consequence of general amelioration of climate towards the close of the - Glacial period.</p></td> - <td><p>Simultaneous elevation of the great plains to about their present - level, with final exclusion of waters in connection with the sea. - Lake Agassiz formed and eventually drained towards the close of this - period. This simultaneous movement in elevation of both great areas - may probably have been connected with a more general northern - elevation of land at the close of the Glacial period.</p></td> -</tr> -</table> -</div> - -<p>In New Zealand the marks of the Glacial period are -unequivocal The glaciers which now come down from -the lofty mountains upon the South Island of New Zealand -to within a few hundred feet of the sea then descended -to the sea-level. The longest existing glacier in -New Zealand is sixteen miles, but formerly one of them -had a length of seventy-eight miles. One of the ancient -moraines contains a boulder from thirty to forty feet in -diameter, and the amount of glacial <i>débris</i> covering the -mountain-sides is said to be enormous. Reports have also -been recently brought of signs of ancient glaciers in Australia.</p> - -<p><span class="pagenum"><a name="Page_127" id="Page_127">« 127 »</a></span></p> - -<div class="fig_center" style="width: 423px;"> -<a id="fig38" name="fig38"></a> -<img src="images/fig_38.png" width="423" height="552" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 38.</span>—Generalised view of the whole glaciated region of North America. -The area of motionless ground-ice is shown by the white lines in northern -part of Alaska.</div> -</div> - -<p>According to Darwin, there are distinct signs of glaciation -upon the plains of Patagonia sixty or seventy miles -east of the foot of the mountains, and in the Straits of Magellan -he found great masses of unstratified glacial material -containing boulders which were at least one hundred and -thirty miles away from their parent rock; while upon the -<span class="pagenum"><a name="Page_128" id="Page_128">« 128 »</a></span> -island of Chiloe he found embedded in “hardened mud” -boulders which must have come from the mountain-chains -of the continent. Agassiz also observed unquestionable -glacial phenomena on various parts of the Fuegian coast, -and indeed everywhere on the continent south of latitude -37°. Between Concepcion and Arauco, in latitude 37°, -Agassiz observed, near the sea-level, a glacial surface well -marked with furrows and scratches, and as well preserved, -he says, “as any he had seen under the glaciers of the -present day.”</p> - -<div class="fig_center" style="width: 386px;"> -<a id="fig39" name="fig39"></a> -<img src="images/fig_39.png" width="386" height="204" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 39.</span>—Quartzite boulder of 45 cubic metres, on Mont Lachat, 800 metres above -the valley of the Belley, in Ain, France (Falsan).</div> -</div> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_129" id="Page_129">« 129 »</a></span></p> - - - - -<p class="caption2"><a name="CHAPTER_VI" id="CHAPTER_VI">CHAPTER VI.</a></p> - -<p class="caption2">ANCIENT GLACIERS IN THE EASTERN HEMISPHERE.</p> - - -<p>About two million square miles of northern Europe -were covered with perennial ice during the Glacial period. -From the scratches upon the rocks, and from the direction -in which material has been transported, it is evident that -the main centre of radiation is to be found in the mountains -of Scandinavia, and that the glaciers still existing in -Norway are the lineal descendants of those of the great -Ice age.</p> - -<p>So shallow are the Baltic Sea and the German Ocean, -that their basins were easily filled with ice, upon which -Scandinavian boulders could be transported westward to -the east shore of England, southward into the plains of -Germany, and eastward far out upon the steppes of Russia. -The islands north of Scotland bear marks also of an ice-movement -from the direction of Norway. If Scotland -itself was not overrun with Scandinavian glaciers, the -reason was that it had ice enough of its own, and from -its highlands set up a counter-movement, which successfully -resisted the invasion from the Scandinavian Peninsula. -But, elsewhere in Europe, Scandinavian ice moved -freely outward to the extent of its capacity. Then, as -now also, the Alps furnished centres for ice-movement, -but the glaciers were limited to the upper portions of the -valleys of the Rhône, the Rhine, and the Danube upon -the west and north, and to a still smaller area upon the -southern side.</p> - -<p><span class="pagenum"><a name="Page_130" id="Page_130">« 130 »</a></span></p> - -<div class="fig_center" style="width: 700px;"> -<a id="fig40" name="fig40"></a> -<img src="images/fig_40.png" width="700" height="420" alt="MAP showing GLACIATED AREAS in North America and Europe." /> -<div class="fig_caption"><span class="smcap">Fig. 40.</span></div> -</div> - -<p><span class="pagenum"><a name="Page_131" id="Page_131">« 131 »</a></span></p> - - -<p class="caption3nb"><i>Central and Southern Europe.</i></p> - -<p>The main centres of ice-movement in the Alps during -the Glacial period are the same as those which furnish -the lingering glaciers of the present time. From the -water-shed between the Rhine, the Rhône, and the Aar, -glaciers of immense size descended all the valleys now -occupied by those streams. The valley of the Rhône between -the Bernese and the Pennine Alps was filled with a -glacier of immense depth, which was maintained by fresh -supplies from tributaries upon either side as far down as -Martigny. Glacial markings at the head of the Rhône -Valley are found upon the Schneestock,<a name="FNanchor_63" id="FNanchor_63"></a><a href="#Footnote_63" class="fnanchor">[BK]</a> at an elevation -above the sea of about 11,500 feet (3,550 metres), or -about 1,500 feet above the present surface of the Rhône -Glacier. At Fiesch, about twenty miles below, where -tributaries from the Bernese Oberland snow-fields were -received, the thickness of the glacier was upwards of 5,000 -feet (1,680 metres). Near Martigny, about fifty miles -farther down the valley, where the glacier was abruptly deflected -to the north, the depth of the ice was still upwards -of 1,600 metres. From Martigny northward the thickness -of the ice decreased rapidly for a few miles, where, -at the enlargement of the valley above the head of Lake -Geneva, it was less than 1,200 metres in thickness, and -spread out over the intervening plain as far as Chasseron, -with a nearly level surface, transporting, as we have before -said, Alpine boulders to the flanks of the Juras, and landing -them about 3,000 feet (1,275 metres) above the level -of Lake Geneva. The width of the main valley is here -about fifty miles, making the slope of the surface of the -ice about twenty feet to the mile.</p> - -<div class="footnote"> - -<p><a name="Footnote_63" id="Footnote_63"></a><a href="#FNanchor_63"><span class="label">[BK]</span></a> A. Falsan’s La Période Grlaciaire étudiée principalement en -France et en Suisse, chapitre xv.</p></div> - -<p>From its “vomitory,” at the head of Lake Geneva, the -<span class="pagenum"><a name="Page_132" id="Page_132">« 132 »</a></span> -ice of the ancient Rhône Glacier spread to the right and -to the left, while its northern boundary was abruptly terminated -by the line of the Jura Mountains. The law of -glacial motion was, however, admirably illustrated in the -height to which the ice rose upon the flanks of the Jura. -At Chasseron, in the direct line of its onward motion, it -rose to its highest point, while both to the southwest and -to the northeast, along the line of the Juras, the ice-action -was limited to constantly decreasing levels.</p> - -<p>Down the valley of the Rhône the direction of motion -was determined by the depression of Lake Geneva, at the -lower end of which it received its main tributary from -Mont Blanc, which had come down from Chamouni -through the valley of the river Arve. From this point it -was deflected by a spur of the Jura Mountains more and -more southward to the vicinity of Culoz, near the mouth -of Lake Bourget. Here the glacier coming down from -the western flanks of the Alps, through the upper valley -of the Isère, past Chambéry, became predominant, and -deflected the motion to the west and north, whither the -ice extended to a line passing through Bourg, Lyons, and -Vienne, leaving upon one of the eminences on which -Lyons is built a boulder several feet in diameter, which is -duly preserved and labelled in the public park in that -portion of the city. Farther south, glaciers of less extent -marked the Alps most of the way to the Mediterranean, -but they were not at all comparable in size to those from -the central region.</p> - -<p>To the right of Lake Geneva the movement started by -the Rhône Glacier spread eastward, being joined in the -vicinity of Berne by the confluent ice-stream which descended -from the north flank of the Bernese Oberland, -through the valley of the Aar. These united streams -filled the whole valley with ice as far down as Soleure.<a name="FNanchor_64" id="FNanchor_64"></a><a href="#Footnote_64" class="fnanchor">[BL]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_64" id="Footnote_64"></a><a href="#FNanchor_64"><span class="label">[BL]</span></a> <a href="#fig30">See map</a> of Rhône Glacier, on <a href="#Page_58">p. 58</a>.</p> -</div> - - -<div class="fig_center" style="width: 661px;"> -<a id="map_glac_mv" name="map_glac_mv"></a> -<a href="images/glac_mv_map_lrg.png"><img src="images/glac_mv_map_sm.png" width="661" height="543" alt="MAP OF GLACIAL MOVEMENTS IN FRANCE AND SWITZERLAND." /></a> -<span class="center smaller">Click on map to view larger sized.</span> -</div> - -<p><span class="pagenum"><a name="Page_133" id="Page_133">« 133 »</a></span></p> - -<p>Farther eastward, other ice-streams from the Alps became -predominant, one of which, moving down the Reuss, -deployed out upon the country lying north of Lucerne -and Zug. Still farther down, the ancient glacier which -descended the Limmatt spread itself out over the hills -and lowlands about Zürich, one of its moraines of retrocession -nearly dividing the lake into two portions.</p> - -<p>Guyot and others have shown that the superficial deposits -of this portion of Switzerland are just such as would -be distributed by glaciers coming down from the above-mentioned -Alpine valleys. Uniting together north of -Zürich, these glaciers pushed onward as far as the Rhine -below Schaffhausen. In Frickthal the glacial ice was still -1,200 feet thick, and at Kaisterberg between 400 and 500 -feet.</p> - -<p>At Lucerne there is a remarkable exposure of pot-holes, -and a glaciated surface such as could be produced -only by the combined action of moving ice and running -water; thus furnishing to tourists an instructive object-lesson. -Among the remarkable instances of boulders -transported a long distance in Switzerland, is that of a -block of granite carried from the Valais to the vicinity of -Soleure, a distance of one hundred and fifteen miles, which -weighs about 4,100 tons. “The celebrated Pierre-à-Bot, -above Neufchâtel, measures 50’ × 20’ × 40’, and contains -about 40,000 cubic feet of stone; while the Pierre-des-Marmettes, -near Monthey, contains no less than 60,840 -cubic feet.”</p> - -<p>The ancient glacier of the Rhine, receiving its initial -impulse in the same centre as that of the Rhône, fully -equalled it in all its dimensions. Descending eastward -from its source near the Schneestock to Chur, a distance -of fifty miles, it turned northward and continued forty-five -miles farther to the head of Lake Constance, where it -spread out in fan-shape, extending northwest to Thiengen, -below Schaffhausen, and covering a considerable area north -<span class="pagenum"><a name="Page_134" id="Page_134">« 134 »</a></span> -and northeastward of the lake, reaching in the latter direction -Ulm, upon the Danube—the whole distance of the -movement being more than one hundred and fifty miles. -Through other valleys tributary to the Danube, glaciers -descended upon the upper plains of Bavaria, from the -Tyrolese Alps to the vicinity of Munich. From Gross -Glockner as a centre in the Noric Alps, vast rivers of ice, -of which the Pasterzen Glacier is the remnant, poured -far down into the valleys of the Inn and the Enns on -the north and into that of the Drave on the southeast. -Farther eastward in this part of Europe the mountains -seem to have been too low to have furnished centres for -any general dispersion of glacial ice.</p> - -<div class="fig_right" style="width: 232px;"> -<a id="fig41" name="fig41"></a> -<a href="images/fig_41_lrg.png"><img src="images/fig_41.png" width="232" height="265" alt="" /></a> -<div class="fig_caption"><span class="smcap">Fig. 41.</span>—Map showing the Lines of <i>Débris</i> extending -from the Alps into the Plains of the -Po (after Lyell). <i>A.</i> Crest of the Alpine water-shed; -<i>B.</i> Névé-fields of the ancient glaciers; -<i>C.</i> Moraines of ancient glaciers.<br /> -Click on image to view larger sized.</div> -</div> - -<p>Upon the south side of the Alps the ancient glaciers -spread far out upon the plains of Lombardy, where moraines -of vast extent -and of every description -enable the student -to determine the -exact limits of the -ancient ice-action. -From the southern -flanks of Mont Blanc -and Monte Rosa, and -from the snow-fields -of the western Alps, -glaciers of great volume -descended into -the valley of Dora -Baltea (vale of Aosta), -and on emerging -from the mountain -valley Spread Out over -the plains around -Ivrea, leaving moraine hills in some instances 1,500 feet in -height. The total length of this glacier was as much as -<span class="pagenum"><a name="Page_135" id="Page_135">« 135 »</a></span> -one hundred and twenty miles. From the snow-fields in -the vicinity of Mont Cenis, also, glaciers extended down -the Dora Ripera to the vicinity of Turin, and down other -valleys to a less extent. The lateral moraines of the Diore, -on the south side of Mont Blanc, at the head of the Dora -Baltea, are 2,000 feet above the present river, and extend -upon the left bank for a distance of twenty miles.</p> - -<p>From the eastern Alps, glaciers descended through all -the valleys of the Italian lakes and deposited vast terminal -moraines, which still obstruct the drainage, and produce -the charming lakes of that region. A special historic -interest pertains to the series of concentric moraines south -of Lake Garda, since it was in the reticulations of this -glacial deposit that the last great battle for Italian liberty -was fought on June 24, 1859. Defeated in the engagements -farther up the valley of the Po, the Austrian -general Benedek took his final stand to resist the united -forces of France and Italy behind an outer semicircle of -the moraine hills south of this lake (some of which are -500 or 600 feet above the surrounding country), with his -centre at Solferino, about ten miles from Peschera. Here, -behind this natural fortification, he awaited the enemy, -who was compelled to perform his manœuvres on the open -plain which spread out on every side. But the natural -fortifications furnished by the moraine hills were too extensive -to be defended by an army of moderate size. The -troops of Napoleon and Victor Immanuel concentrated at -Solferino and broke through the line. Thus the day was -lost to the Austrians, and they retired from Lombardy, -leaving to Italy both the artificial and the natural fortifications -that guard the southern end of this important -entrance to the Tyrolese Alps. When once his attention -is called to the subject, the traveller upon the railroad -cannot fail to notice this series of moraines, as he enters -it through a tunnel at Lonato on the west, and emerges -from it at Soma Campagna, eighteen or twenty miles distant -<span class="pagenum"><a name="Page_136" id="Page_136">« 136 »</a></span> -to the east. A monument celebrating the victory -stands upon a moraine hill about half-way between, at -Martino della Battaglie.</p> - -<p>In other portions of central and southern Europe the -mountains were too low to furnish important centres for -glacial movements. Still, to a limited extent, the signs -of ancient glaciers are seen in the mountains of the Black -Forest, in the Harz and Erzgebirge, and in the Carpathians -on the east and among the Apennines on the south. In -Spain, also, there were limited ice-fields on the higher portions -of the Sierra Nevada and in the mountains of Estremadura, -and perhaps in some other places. In France, -small glaciers were to be found in the higher portions of -the Auvergne, of the Morvan, of the Vosges, and of the -Cevennes; while, from the Pyrenees, glaciers extended -northward throughout nearly their whole extent. The -ice-stream descending from the central mass of Maladetta -through the upper valley of the Garonne, was joined by -several tributaries, and attained a length of about forty-five -miles.</p> - - -<p class="caption3nb"><i>The British Isles.</i></p> - -<p>During the climax of the Glacial period the Hebrides -to the north of Scotland were covered with ice to a depth -of 1,600 feet. How far westward of this it moved out -to the sea, it is of course impossible to tell. But in the -channels between the Hebrides and Scotland it is evident -that the water was completely expelled by the ice, and -that, from a height of 1,600 feet above the Hebrides to the -northern shores of Scotland, there was a continuous ice-field -sloping southward at the rate of about twenty-five -feet a mile.</p> - -<p>Scotland itself was completely enveloped in glacial ice. -Prevented by the Scandinavian Glacier from moving eastward, -the Scotch movement was compelled to be westward -and southward. On the southwest the ice-stream reached -<span class="pagenum"><a name="Page_137" id="Page_137">« 137 »</a></span> -the shores of Ireland, and became confluent with the -glaciers that enveloped that island, completely filling the -Irish Sea.</p> - -<p>There are so many controverted points respecting the -glacial geology of England, and they have such an important -bearing upon the main question of this volume, that -a pretty full discussion of them will be necessary. I have -recently been over enough of the ground myself to become -satisfied of the general correctness of the views entertained -by my late colleague, the lamented Professor Henry Carvill -Lewis, whose death in 1888 took place before the publication -of his most mature conclusions. But the lines of -investigation to which he gave so powerful an impulse -have since been followed out by an active body of scientific -observers. To give the statement of facts greater -precision and authority, I have committed the preparation -of it to the Secretary of the Northwest of England Boulder -Committee, Percy F. Kendall, F. G. S., Lecturer on -Geology at the Yorkshire College, Leeds, and at the -Stockport Technical School, England.<a name="FNanchor_65" id="FNanchor_65"></a><a href="#Footnote_65" class="fnanchor">[BM]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_65" id="Footnote_65"></a><a href="#FNanchor_65"><span class="label">[BM]</span></a> Mr. Kendall’s contribution extends to <a href="#Page_181">page 181</a>.</p></div> - -<p>“All the characteristic evidences of the action of land-ice -can be found in the greatest perfection in many parts -of England and Wales. Drumlins, kames, <i>roches moutonnées</i>, -far-travelled erratics, terminal moraines, and perched -blocks, all occur. There are, besides, in the wide-spread -deposits of boulder-clay which cover so many thousands -of square miles on the low grounds lying on either side of -the Pennine chain, evidences of the operation of ice-masses -of a size far exceeding that of the grandest of existing -European glaciers. But, while the proofs of protracted -and severe glaciation are thus patent, there are, -nevertheless, many apparently anomalous circumstances -which arrest the attention when the whole country is surveyed. -The glacial phenomena appear to be strictly limited -to the country lying to the northward of a line extending -<span class="pagenum"><a name="Page_138" id="Page_138">« 138 »</a></span> -from the Bristol Channel to the mouth of the -Thames; and within the glaciated area there are many -extensive tracts of land devoid of ‘drift’ or other indications -of ice-action.</p> - -<p>“By comparison with the phenomena displayed in the -North American continent, English glacial geology must -seem puny and insignificant; but, just as with the features -of the ‘Solid Geology,’ we have compressed within -the narrow limits of our isles an epitome of the features -which across the Atlantic require a continent for their -exposition. It has resulted from this concentration that -English geology requires a much closer and more minute -investigation. And the difficulty which has been experienced -by glacial geologists of dealing with an involved -series of facts has, in the absence of any clue leading to the -co-ordination of a vast series of more or less disconnected -observations, resulted in the adoption, to meet certain local -anomalies, of explanations which were very difficult if not -impossible of reconciliation with facts observed in adjacent -areas. Thus, to account for shell-bearing drift extending -up to the water-shed on one side of a lofty range of hills, a -submergence of the land to a depth of 1,400 feet has been -postulated; leaving for independent explanation the fact, -that the opposite slopes of the hills and the low ground -beyond were absolutely destitute of drift or of any evidence -of marine action.</p> - -<p>“In the following pages I must adopt a somewhat dogmatic -tone, in order to confine myself within the limits of -space which are imposed; and trust rather to the cohesion -and consistency of the explanations offered and to a few -pregnant facts than to the weighing and contrasting of -rival theories.</p> - -<p>“The facts point conclusively to the action in the British -Isles of a series of glaciers radiating outward from the -great hill chains or clusters, and, as the refrigeration progressed, -becoming confluent and moving though in the -<span class="pagenum"><a name="Page_139" id="Page_139">« 139 »</a></span> -same general direction, yet with less regard to the minor -inequalities of the ground. During these two stages many -glaciers must have debouched upon the sea-coast, with the -consequent production of icebergs, which floated off with -loads of boulders and dispersed them in the random fashion -which is a necessary characteristic of transport by -floating ice.</p> - -<p>“With a further accentuation of the cold conditions -the discharge of bergs from terminal fronts which advanced -into the extremely shallow seas surrounding the British -shores would be quite inadequate to relieve the great press -of ice, and a further coalescence of separate elements must -have resulted. In the case of enclosed seas—as, for example, -the Irish Sea—the continued inthrust of glacier-ice -would expel the water completely; and the conjoined ice-masses -would take a direction of flow the resultant of the -momentum and direction of the constituent elements. In -other cases—as, for example, in the North Sea—extraneous -ice approaching the shores might cause a deflection of the -flow of the native glaciers, even though the foreign ice -might never actually reach the shore.</p> - -<p>“To such a system of confluent glaciers, and to the -separate elements out of which they grew, and into which, -after the culmination, they were resolved, I attribute the -whole of the phenomena of the English and Welsh drift. -And only at one or two points upon the coast, and raised -but little above the sea-level, can I recognise any signs -of marine action.</p> - -<p>“<i>The Preglacial Level of the Land.</i>—There is very little -direct evidence bearing upon this point. In Norfolk -the famous forest bed, with its associated deposits, stands at -almost precisely the level which it occupied in preglacial -times. At Sewerby, near Flamborough Head, there is an -ancient beach and ‘buried cliff’ which the sea is now denuding -of its swathing of drift-deposits, and its level can -be seen to be almost absolutely coincident with the present -<span class="pagenum"><a name="Page_140" id="Page_140">« 140 »</a></span> -beach. Mr. Lamplugh, whose description of the ‘Drifts -of Flamborough Head,’<a name="FNanchor_66" id="FNanchor_66"></a><a href="#Footnote_66" class="fnanchor">[BN]</a> constitutes one of the gems of -glacial literature, considers that there is clear evidence -that the land stood at this level for a long period. The -beach is covered by a rain-wash of small extent, and that -in turn by an ancient deposit of blown sand, while the -lowest member of the drift series of Yorkshire covers the -whole. Mr. Lamplugh thinks that the blown sand may -indicate a slight elevation of the land; but the beach appears -to me to be the storm beach, and the reduction in -the force of the waves such as would result from the approach -of an ice-front a few miles to the seaward would -probably produce the necessary conditions.</p> - -<div class="footnote"> - -<p><a name="Footnote_66" id="Footnote_66"></a><a href="#FNanchor_66"><span class="label">[BN]</span></a> Quarterly Journal of the Geological Society, vol. xlvii.</p></div> - -<p>“Six miles to the northward of Flamborough, at Speeton, -a bed of estuarine silt containing the remains of mollusca -in the position of life occurs at an altitude of ninety -feet above high-water mark. Mr. Lamplugh inclines to -the opinion that this bed is of earlier date than the ‘buried -cliff’; he also admits the possibility that its superior altitude -may be due to a purely local upward bulging of the -soft Lower Cretaceous clays upon which the estuarine bed -rests by the weight of the adjacent lofty chalk escarpment.</p> - -<p>“The evidence obtained from inland sections and borings -in different parts of England has been taken to indicate -a greater altitude in preglacial times. Thus, in -Essex, deep-borings have revealed the existence of deep -drift-filled valleys, having their floors below sea-level. -The valley of the Mersey is a still better example. Numerous -borings have been made in the neighbourhood of -Widnes and at other places in the lower reaches of the -river, making it clear that there is a channel filled with -drift and extending to 146 feet below mean sea-level. -This, with several other instances, has been taken to indicate -<span class="pagenum"><a name="Page_141" id="Page_141">« 141 »</a></span> -a greater altitude for the land in preglacial times, -since a river could not erode its channel to such a depth -below sea-level. The argument appears inconclusive for -one principal reason: no mention is made of any river -gravels or other alluvium in the borings. Indeed, there -is an explicit statement that the deposits are all glacial, -showing that the channel must have been cleared out by -ice. This, therefore, leaves open the vital question, -whether the deposits removed were marine or fluviatile. -It may be remarked that the great estuary of the Mersey -has undoubtedly been produced by a post-glacial (and -probably post-Roman) movement of depression.</p> - -<p>“<i>The Preglacial Climate.</i>—In all speculations regarding -the cause of the Glacial epoch, due account must be -taken of the undoubted fact that it came on with extreme -slowness and departed with comparative suddenness. In -the east of England an almost perfect and uninterrupted -sequence of deposits is preserved, extending from the early -part of the Pliocene period down to the present day.</p> - -<p>“These in descending order are:</p> - -<p>“1. Post-glacial sands, gravels, etc.</p> - -<p>“2. Glacial series.</p> - -<p>“3. The ‘Forest Bed’ and associated marine deposits.</p> - -<p>“4. Chillesford clay and sand.</p> - -<p>“5. The many successive stages of the Red Crag. (The -Norwich Crag is a local variation of the upper part of the -Red Crag.)</p> - -<p>“6. The Coralline Crag.</p> - -<p>“The fossils preserved in these deposits, apart from the -physical indications, exhibit the climatal changes which -accompanied their deposition. The Coralline Crag contains -a fauna consisting mainly of species which now -range to the Mediterranean, many of them being restricted -to the warm southern waters. Associated with these are -a few boreal forms, but they are represented in general -by few individuals. Here and there in the deposits of -<span class="pagenum"><a name="Page_142" id="Page_142">« 142 »</a></span> -this age far-travelled stones are to be found, but they are -always accounted great rarities.</p> - -<p>“The Red Crag consists of an irregular assemblage of -beaches and sand-banks of widely different ages, but their -sequence can be made out with ease by a study of the -fauna. In the oldest deposits, Mediterranean species are -very numerous, while the boreal forms are comparatively -rare; but in successive later deposits the proportions are -very gradually reversed, and from the overlying Chillesford -series the Mediterranean species are practically absent. -The physical indications run <i>pari passu</i> with the -paleontological, and in the newer beds of the Red Crag -far-travelled stones are common.</p> - -<p>“In the Forest Bed series there is a marine band—the -<i>Leda myalis</i> bed—which contains an almost arctic assemblage -of shells; while at about the same horizon plant -remains have been found, including such high northern -species as <i>Salix polaris</i> and <i>Betula nana</i>.</p> - -<p>“The glacial deposits do not, in my opinion, contain -anywhere in England or Wales a genuine intrinsic fauna, -such shells as occur in the East Anglian glacial deposits -having been derived in part from a contemporary sea-bed, -and, for the rest, from the older formations, down perhaps -to the Coralline Crag. In the post-glacial deposits we -have hardly any trace of a survival of the boreal forms, -and I consider that the whole marine fauna of the North -Sea was entirely obliterated at the culmination of the -Glacial epoch, and that the repeopling in post-glacial -times proceeded mainly from the English Channel, into -which the northern forms never penetrated.</p> - - -<p class="center larger">"<i>The Great Glacial Centres.</i></p> - -<p>“Where such complex interactions have to be described -as were produced by the conflicting glaciers of the British -Isles it is difficult to deal consecutively with the phenomena -of any one area, but with short digressions in explanation -<span class="pagenum"><a name="Page_143" id="Page_143">« 143 »</a></span> -of special points it may be possible to accomplish -a clear presentation of the facts.</p> - -<p>“<i>Wales.</i>—The phenomena of South Wales are comparatively -simple. Great glaciers travelled due southward -from the lofty Brecknock Beacons, and left the characteristic -<i>moutonnée</i> appearance upon the rocky bed over -which they moved. The boulder-transport is in entire -agreement with the other indications, and there are no -shells in the drift. The facts awaiting explanation are -the occurrence in the boulder-clays of Glamorganshire, at -altitudes up to four hundred feet, of flints, and of igneous -rocks somewhat resembling those of the Archæan series -of the Wrekin. At Clun, in Shropshire, a train of erratics -(<a href="#map_brit_glac">see map</a>) has been traced back to its source to the westward. -On the west coast, in Cardigan Bay, the boulders -are all such as might have been derived from the interior -of Wales. At St. David’s Peninsula, Pembrokeshire, striæ -occur coming in from the northwest, and, taken with the -discovery of boulders of northern rocks, may point to a -southward extension of a great glacier produced by confluent -sheets that choked the Irish Sea. Information is very -scanty regarding large areas in mid-Wales, but such as -can be gathered seems to point to ice-shedding having -taken place from a north and south parting line. In -North Wales, much admirable work has been done which -clearly indicates the neighbourhood of Great Arenig -(Arenig Mawr) as the radiant point for a great dispersal -of blocks of volcanic rock of a characteristic Welsh type.</p> - -<p>“<i>Ireland.</i>—A brief reference must be made to Ireland, -as the ice which took origin there played an important -part in bringing about some strange effects in English -glaciation, which would be inexplicable without a recognition -of the causes in operation across the Irish Sea. -Ireland is a great basin, surrounded by an almost continuous -girdle of hills. The rainfall is excessive, and the -snow-fall was probably more than proportionately great; -<span class="pagenum"><a name="Page_144" id="Page_144">« 144 »</a></span> -therefore we might expect that an ice-sheet of very large -dimensions would result from this combination of favouring -conditions. The Irish ice-sheet appears to have -moved outward from about the centre of the island, but -the main flow was probably concentrated through the -gaps in the encircling mountains.</p> - -<p>“<i>Galloway.</i>—The great range of granite mountains in -the southwestern corner of Scotland seems to have given -origin to an immense mass of ice which moved in the main -to the southward, and there are good grounds for the -belief that the whole ice-drainage of the area, even that -which gathered on the northern side of the water-shed, -ultimately found its way into the Irish Sea basin and -came down coastwise and across the low grounds of the -Rinns of Galloway, being pushed down by the press of -Highland ice which entered the Firth of Clyde. It is a -noteworthy fact that marine shells occur in the drift in -the course taken by the ice coming on to the extremity of -Galloway from the Clyde.</p> - -<p>“<i>The Lake District.</i>—A radial flow of ice took place -down the valleys from about the centre of the Cumbrian -hill-plexus, but movement to the eastward was at first forbidden -by the great rampart of the Cross Fell escarpment, -which stretches like a wall along the eastern side of the -Vale of Eden.</p> - -<p>“During the time when the Cumbrian glaciers had -unobstructed access to the Solway Frith, to the Irish Sea, -and to Morecambe Bay, the dispersal of boulders of characteristic -local rocks would follow the ordinary drainage-lines; -but, as will be shown later, a state of affairs supervened -in the Irish Sea which resulted, in many cases, in a -complete reversal of the ice-flow.</p> - -<p>“<i>The Pennine Chain</i> was the source of glaciers of majestic -dimensions upon both its flanks in the region north -of Skipton, but to the southward of that breach in the chain -(<a href="#map_brit_glac">see map</a>) no evidence is obtainable of any local glaciers.</p> - -<p><span class="pagenum"><a name="Page_145" id="Page_145">« 145 »</a></span></p> - - -<p class="center">"<i>The Confluent Glaciers.</i></p> - -<p>“With the growth of ice-caps upon the great centres -a condition of affairs was brought about in the Irish Sea -productive of results which will readily be foreseen. The -enormous volumes of ice poured into the shallow sea -from north, south, east, and west, resulted in such a congestion -as to necessitate the initiation of some new systems -of drainage.</p> - -<p>“<i>The Irish Sea Glacier.</i>—The ice from Galloway, Cumbria, -and Ireland became confluent, forming what the late -Professor Carvill Lewis termed ‘the Irish Sea Glacier,’ -and took a direction to the southward. Here it came in -diametrical conflict with the northward-flowing element -of the Welsh sheet, which it arrested and mastered; and -the Irish Sea Glacier bifurcated, probably close upon the -precipitous Welsh coast to the eastward of the Little -Orme’s Head, and the two branches flowed coastwise to -eastward and westward, keeping near the shore-line.</p> - -<p>“The westerly branch swept round close to the coast in a -southwesterly direction, and completely overrode Anglesea; -striating the rock-surfaces from northeast to southwest -(<a href="#map_brit_glac">see map</a>), and strewing the country with its bottom-moraine, -containing characteristic northern rocks, such as the -Galloway granites, the lavas and granites of the central and -western portions of the Lake District, and fragments of -shells derived from shell-banks in the Irish Sea. One episode -of this phase of the ice-movement was the invasion -of the first line of hills between the Menai Straits and -Snowdon. The gravels and sands of Fridd-bryn-mawr, -Moel Tryfaen, and Moel-y-Cilgwyn, are the coarser washings -of the bottom-moraine, and consequently contain such -rock-fragments and shells as characterise it. From Moel-y-Cilgwyn -southward, evidence is lacking regarding the -course taken by the glacier, but it probably passed over -or between the Rivals Mountains (Yr Eifl), and down -<span class="pagenum"><a name="Page_146" id="Page_146">« 146 »</a></span> -Cardigan Bay at some distance from the coast in confluence -with the ice from mid-Wales; and, as I have suggested, -may have passed over St. David’s Head.</p> - -<p>“Returning now towards the head of the glacier we may -follow with advantage its left bank downward. The ice-flow -on the Cumberland coast appears to have resembled -very much that in North Wales. A great press of ice -from the northward (Galloway) seems to have had a powerful -‘easting’ imparted to it by the conjoint influences -of the thrust of the Irish ice and the inflow of ice from -the Clyde. Whatever may have been the cause, the effect -is clear: about Ravenglass cleavage took place, and a flow -to northward and to southward, each bending easterly. -By far the larger mass took a southerly course and bent -round Black Combe, over Walney, and a strip of the mainland -about Barrow in Furness, and out into and across -Morecambe Bay. Its limits are marked in the field by -the occurrence of the same rocks which characterise it in -Anglesea, viz., the granites of Galloway and of west and -central Cumbria.</p> - -<p>“The continued thrust shouldered in the glacier upon -the mainland of Lancashire, but the precise point of -emergence has not yet been traced, though it cannot be -more than a few miles from the position indicated on the -map. I should here remark, that all along the boundaries -the Irish Sea Glacier was confluent with local ice, -except, probably, in that part of the Pennine chain to the -southward of Skipton. Down to Skipton there was a -great mass of Pennine ice which was compelled to take -an almost due southerly course, and thus to run directly -athwart the direction of the main hills and valleys. A -sharp easterly inflection of the Irish Sea Glacier carried it -up the valley of the Ribble, and thence, under the shoulder -of Pendle, to Burnley, where Scottish granites are -found in the boulder-clay.</p> - -<p>“On the summit of the Pennine water-shed, at Heald -<span class="pagenum"><a name="Page_147" id="Page_147">« 147 »</a></span> -Moor, near Todmorden (1,419 feet), boulder-clay has been -found containing erratics belonging to this dispersion; -while in the gorge of the Yorkshire Calder, which flows -along the eastern side of the same hill, not a vestige of -such a deposit is to be found, saving a few erratic pebbles -at a distance of eight or ten miles, which were probably -carried down by flood-wash from the edge of the ice.</p> - -<p>“From this point the limits of the ice may be traced -along the flanks of the Pennine chain at an average altitude -of about 1,100 feet.</p> - -<p>“At one place the erratics can be traced to a position -which would indicate the formation of an extra-morainic -lake having its head at a col about 1,000 feet above sea-level, -separating it from the valley of an eastward-flowing -stream, the Wye, about twelve miles down which a -few granite blocks have been found. Other extra-morainic -lakes must have been formed, but very little information -has been collected regarding them. The Irish Sea Glacier -can be shown to have spread across the whole country -to the westward of the line I have traced, and beyond the -estuary of the Dee.</p> - -<p>“I may now follow its boundaries on the Welsh coast, -and pursue the line to the final melting-place of the glacier. -From the Little Orme’s Head the line of confluence with -the native ice is pretty clearly defined. It runs in, perhaps, -half a mile from the shore, until the broad low tract -of the Vale of Clwyd is reached. Here the northern ice -obtained a more complete mastery, and pushed in even -as far as Denbigh. This extreme limit was probably attained -as a mere temporary episode. Horizontal striæ on -a vertical face of limestone on the crags dominating the -mouth of the vale on the eastern side attest beyond dispute -the action of a mass of land-ice moving in from the -north.</p> - -<p>“I may here remark, that in this district the deposits -furnish a very complete record of the events of the Glacial -<span class="pagenum"><a name="Page_148" id="Page_148">« 148 »</a></span> -period. In the cliffs on the eastern side of the Little -Orme’s Head, and at several other points along the coast -towards the east, a sequence may be observed as follows:</p> - -<p>“4. Boulder-clay with northern erratics and shells.</p> - -<p>“3. Sands and gravels with northern erratics and shells.</p> - -<p>“2. Boulder-clay with northern erratics and shells.</p> - -<p>“1. Boulder-clay with Welsh erratics and no shells.</p> - -<p>“A similar succession is to be seen in the Vale of -Clwyd. The interpretation is clear: In the early stages -of glaciation the Welsh ice spread without hindrance to, -and laid down, bed No. 1; then the northern ice came -down, bringing its typical erratics and the scourings of -the sea-bottom, and laid down the variable series of clays, -sands, and gravels which constitute Nos. 2, 3, and 4 of -the section.</p> - -<div class="fig_left" style="width: 374px;"> -<a id="fig42" name="fig42"></a> -<img src="images/fig_42.png" width="374" height="193" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 42.</span>—The Cefn Cave, in Vale of Clwyd. (Trimmer.) <i>a</i>, Entrance; <i>b</i>, mud -with pebbles and wood covered with stalagmite; <i>c</i>, mud, bones, and angular -fragments of limestone; <i>d</i>, sand and silt, with fragments of marine shells; -<i>e</i>, fissure; <i>f</i>, northern drift; <i>g</i>, cave cleared of mud; <i>h</i>, river Elwy, 100 feet -below; <i>i</i>, limestone rock.</div> -</div> - -<p>“In the Vale of Clwyd an additional interest is imparted -to the study of the drift from the circumstance that the -remains of man have been found in deposits in caves sealed -with drift-beds. The best example is the Cae Gwyn caves, -in which flint implements and the bones and teeth of various -extinct animals were found embedded in ‘cave-earth’<span class="pagenum"><a name="Page_149" id="Page_149">« 149 »</a></span> -which was overlaid by bedded deposits of shell-bearing -drift, with erratics of the northern type.</p> - -<p>“It has been supposed that the drift-deposits were marine -accumulations; but it is inconceivable that the cave -could ever have been subjected to wave-action without the -complete scouring out of its contents.</p> - -<p>“To resume the delineation of the limits of the great -Irish Sea Glacier: From the Vale of Clwyd the boundary -runs along the range of hills parallel to the estuary of the -Dee at an altitude of about nine hundred feet. As it is -traced to the southeast it gradually rises, until at Frondeg, -a few miles to the northward of the embouchure of the -Yale of Llangollen, it is at a height of 1,450 feet above -sea-level. Thence it falls to 1,150 feet at Gloppa, three -miles to the westward of Oswestry, and this is the most -southerly point to which it has been definitely traced on -the Welsh border, though scattered boulders of northern -rocks are known to occur at Church Stretton.</p> - -<p>“Along the line from the Vale of Clwyd to Oswestry the -boundary is marked by a very striking series of moraine-mounds. -They occur on the extreme summits of lofty -hills in a country generally almost driftless, and their appearance -is so unusual that one—Moel-y-crio—at least has -been mistaken for an artificial tumulus. The limitation -of the dispersal of northern erratics by these mounds is -very clear and sharp; and Mackintosh, in describing those -at Frondeg, remarked that, while no northern rocks extended -to the westward of them, so no Welsh erratics could -be found to cross the line to the eastward. There are -Welsh erratics in the low grounds of Cheshire and Shropshire, -but their distribution is sporadic, and will be explained -in a subsequent section.</p> - -<p>“Having thus followed around the edges of this glacier, -it remains to describe its termination. It is clear that the -ice must have forced its way over the low water-shed -between the respective basins of the Dee and the Severn. -<span class="pagenum"><a name="Page_150" id="Page_150">« 150 »</a></span> -So soon as this ridge (less than 500 feet above the sea) is -crossed, we find the deposits laid down by the glacier -change their character, and sands and gravels attain a -great predominance.<a name="FNanchor_67" id="FNanchor_67"></a><a href="#Footnote_67" class="fnanchor">[BO]</a> Near Bridgenorth, and, at other -places, hills composed of such materials attain an altitude -of 200 feet. From Shrewsbury <i>via</i> Burton, and thence, -in a semicircular sweep, through Bridgenorth and Enville, -there is an immense concentration of boulders and pebbles, -such as to justify the designation of a terminal moraine. -To the southward, down the valley of the Severn, -existing information points to the occurrence merely of -such scattered pebbles as might have been carried down -by floods. In the district lying outside this moraine there -is a most interesting series of glacial deposits and of boulders -of an entirely different character. (<a href="#map_brit_glac">See map</a>.)</p> - -<div class="footnote"> - -<p><a name="Footnote_67" id="Footnote_67"></a><a href="#FNanchor_67"><span class="label">[BO]</span></a> Mackintosh, Q. J. G. S.</p></div> - -<p>“From the neighbourhood of Lichfield, through some -of the suburbs of Birmingham, and over Frankley Hill and -the Lickey Hills to Bromsgrove, there is a great accumulation -of Welsh erratics, from the neighbourhood, probably, -of Arenig Mawr.</p> - -<p>“The late Professor Carvill Lewis suggested that these -Arenig rocks might have been derived from some adjacent -outcrop of Palæozoic rocks—a suggestion having its justification -in the discoveries that had been made of Cumbrian -rocks in the Midlands. To test the matter, an excavation -was made at a point selected on Frankley Hill, -and a genuine boulder-clay was found, containing erratics -of the same type as those found upon the surface.</p> - -<p>“The explanation has since been offered that this boulder-clay -was a marine deposit laid down during a period -of submerge nee.<a name="FNanchor_68" id="FNanchor_68"></a><a href="#Footnote_68" class="fnanchor">[BP]</a> Apart from the difficulty that the -boulder-clay displays none of the ordinary characteristics -of a marine deposition, but possesses a structure, or rather -<span class="pagenum"><a name="Page_151" id="Page_151">« 151 »</a></span> -absence of structure, in many respects quite inconsistent -with such an origin, and contains no shells or other remains -of marine creatures, it must be pointed out that no theory -of marine notation will explain the distribution of the -erratics, and especially their concentration in such numbers -at a station sixty or seventy miles from their source.</p> - -<div class="footnote"> - -<p><a name="Footnote_68" id="Footnote_68"></a><a href="#FNanchor_68"><span class="label">[BP]</span></a> Proceedings of the Birmingham Philosophical Society, vol. vi, -Part I, p. 181.</p></div> - -<p>“Upon the land-ice hypothesis this difficulty disappears. -During the early stages of the Glacial period the Welsh -ice had the whole of the Severn Valley at its mercy, and a -great glacier was thrust down from Arenig, or some other -point in central Wales, having an <i>initial direction</i>, broadly -speaking, from west to east. This glacier extended across -the valley of the Severn, sweeping past the Wrekin, whence -it carried blocks of the very characteristic rocks to be -lodged as boulders near Lichfield; and it probably formed -its terminal moraine along the line indicated. (See lozenge-shaped -marks on the map.) As the ice in the north gathered -volume it produced the great Irish Sea Glacier, which -pressed inland and down the Vale of Severn in the manner -I have described, and brushed the relatively small Welsh -stream out of its path, and laid down its own terminal -moraine in the space between the Welsh border and the -Lickey Hills. It seems probable that the Welsh stream -came mainly down the Vale of Llangollen, and thence to -the Lickey Hills. Boulders of Welsh rocks occur in the -intervening tract by ones and twos, with occasional large -clusters, the preservation of any more connected trail -being rendered impossible by the great discharge of water -from the front of the Irish Sea Glacier, and the distributing -action of the glacier itself.</p> - -<p>“Within the area in England and Wales covered by the -Irish Sea Glacier all the phenomena point to the action of -land-ice, with the inevitable concomitants of subglacial -streams, extra-morainic lakes, etc. There is nothing to -suggest marine conditions in any form except the occurrence -of shells or shell fragments; and these present so -<span class="pagenum"><a name="Page_152" id="Page_152">« 152 »</a></span> -many features of association, condition, and position inconsistent -with, what we should be led to expect from a -study of recent marine life, that conchologists are unanimous -in declaring that not one single group of them is on -the site whereon the shells lived. It is a most significant -fact—one out of a hundred which could be cited did space -permit—that in the ten thousand square miles of, as it is -supposed, recently elevated sea-bottom, not a single example -of a bivalve shell with its valves in apposition has -ever been found! Nor has a boulder or other stone been -found encrusted with those ubiquitous marine parasites, -the barnacles.</p> - -<p>“The evidences of the action of land-ice within the area -are everywhere apparent in the constancy of direction of— -(1.) Striæ upon rock surfaces. (2.) The terminal curvature -of rocks. (3.) The ‘pull-over’ of soft rocks. (4.) -The transportal of local boulders. (5.) The orientation of -the long axes of large boulders. (6.) The false bedding -of sands and gravels. (7.) The elongation of drift-hills. -(8.) The relations of ‘crag and tail.’ There is a similar -general constancy, too, in the directions of the striæ upon -large boulders. Upon the under side they run longitudinally -from southeast (or thereabouts) to northwest, while -upon the upper surface they originate at the opposite -end, showing that the scratches on the under side were -produced by the stone being dragged from northwest to -southeast, while those on the top were the product of -the passage of stone-laden ice over it in the same direction.</p> - -<p>“Such an agreement cannot be fortuitous, but must be -attributed to the operation of some agent acting in close -parallelism over the whole area. To attribute such regularity -to the action of marine currents is to ignore the -most elementary principles of marine hydrology. Icebergs -must, in the nature of things, be the most erratic -of all agents, for the direction of drift is determined—among -<span class="pagenum"><a name="Page_153" id="Page_153">« 153 »</a></span> -other varying factors—by the draught of the berg. -A mass of small draught will be carried by surface currents, -while one of greater depth will be brought within -the influence of under-currents; and hence it not infrequently -happens that while floe-ice is drifting, say, to the -southeast, giant bergs will go crashing through it to the -northwest. There are tidal influences also to be reckoned -with, and it is matter of common knowledge that flotsam -and jetsam travel back and forth, as they are alternately -affected by ebb and flood tide.</p> - -<p>“Bearing these facts in mind, it is surely too much to -expect that marine ice should transport boulders (how it -picked up many of them also requires explanation) with -such unfailing regularity that it can be said without challenge,<a name="FNanchor_69" id="FNanchor_69"></a><a href="#Footnote_69" class="fnanchor">[BQ]</a> -‘boulders in this district [South Lancashire and -Cheshire] never occur to the north or west of the parent -rock.’ The same rule applies without a single authentic -exception to the whole area covered by the eastern branch -of the Irish Sea Glacier; and hence it comes about that -not a single boulder of Welsh rock has ever been recorded -from Lancashire.</p> - -<div class="footnote"> - -<p><a name="Footnote_69" id="Footnote_69"></a><a href="#FNanchor_69"><span class="label">[BQ]</span></a> Brit. Assoc. Report, 1890, p. 343.</p></div> - -<p>“<i>The Solway Glacier.</i>—The pressure which forced -much of the Irish Sea ice against the Cumbrian coast-line -caused, as has been described, a cleavage of the flow near -Ravenglass, and, having followed the southerly branch to -its termination in the midlands, the remaining moiety demands -attention.</p> - -<p>“The ‘easting’ motion carried it up the Solway Frith, -its right flank spreading over the low plain of northern -Cumberland, which it strewed with boulders of the well-known -‘syenite’ (granophyre) of Buttermere. When this -ice reached the foot of the Cross Fell escarpment, it suffered -a second bifurcation, one branch pushing to the -eastward up the valley of the Irthing and over into Tyneside, -<span class="pagenum"><a name="Page_154" id="Page_154">« 154 »</a></span> -and the other turning nearly due southward and -forcing its way up the broad Vale of Eden.</p> - -<p>“Under the pressure of an enormous head of ice, this -stream rose from sea-level, turned back or incorporated -the native Cumbrian Glacier which stood in its path, and, -having arrived almost at the water-shed between the -northern and the southern drainage, it swept round to -the eastward and crossed over the Pennine water-shed; -not, however, by the lowest pass, which is only some 1,400 -feet above sea-level, but by the higher pass of Stainmoor, -at altitudes ranging from 1,800 to 2,000 feet. The lower -part of the course of this ice-flow is sufficiently well characterised -by boulders of the granite of the neighbourhood -of Dalbeattie in Galloway; but on its way up the Vale of -Eden it gathered several very remarkable rocks and posted -them as way-stones to mark its course. One of these -rocks, the Permian Brockram, occurs nowhere <i>in situ</i> -at altitudes exceeding 700 feet, yet in the course of its -short transit it was lifted about a thousand feet above its -source. The Shap granite (see radiant point on map) -is on the northern side of the east and west water-sheds -of the Lake District, and reaches its extreme elevation, -(1,656 feet) on Wasdale Pike; yet boulders of it were -carried over Stainmoor, at an altitude of 1,800 feet literally -by tens of thousands.</p> - -<p>“This Stainmoor Glacier passed directly over the Pennine -chain, past the mouths of several valleys, and into -Teesdale, which it descended and spread out in the low -grounds beyond. Pursuing its easterly course, it abutted -upon the lofty Cleveland Hills and separated into two -streams, one of which went straight out to sea at Hartlepool, -while the other turned to the southward and flowed -down the Vale of York, being augmented on its way by -tributary glaciers coming down Wensleydale. The final -melting seems to have taken place somewhere a little to -the southward of York; but boulders of Shap granite by -<span class="pagenum"><a name="Page_155" id="Page_155">« 155 »</a></span> -which its extension is characterised have been found as -far to the southward as Royston, near Barnsley.</p> - -<p>“The other branch of the Solway Glacier—that which -travelled due eastward—passed up the valley of the Irthing, -and over into that of the Tyne, and out to sea at -Tynemouth. It carried the Scottish granites with it, and -tributary masses joined on either hand, bringing characteristic -boulders with them.</p> - -<p>“The fate of those elements of the Solway Frith Glacier -which reached the sea is not left entirely to conjecture. -The striated surfaces near the coast of Northumberland -indicate a coastwise flow of ice from the northward—probably -from the Frith of Forth—and the glaciers -coming out from the Tyne and Tees were deflected -to the southward.</p> - -<p>“There is conclusive evidence that this ice rasped the -cliffs of the Yorkshire coast and pressed up into some of -the valleys. Where it passed the mouth of the Tees near -Whitby it must have had a height of at least 800 feet, but -farther down the coast it diminished in thickness. It -nowhere extended inland more than a mile or two, and -for the most part kept strictly to the coast-line. Along -the whole coast are scattered erratics derived from Galloway -and the places lying in the paths of the glaciers. -In many places the cliffs exhibit signs of rough usage, -the rocks being crumpled and distorted by the violent -impact of the ice. At Filey Brigg a well-scratched surface -has been discovered, the striation being from a few -degrees east of north.</p> - -<p>“At Speeton the evidence of ice-sheet or glacier-work is -of the most striking character. On the top of the cliffs of -Cretaceous strata a line of moraine-hills has been laid down, -extending in wonderful perfection for a distance of six -miles. They consist of a mixture of sand, gravel, and a -species of clay-rubble, with occasional masses of true boulder-clay, -the whole showing the arched bedding so characteristic -<span class="pagenum"><a name="Page_156" id="Page_156">« 156 »</a></span> -of such accumulations. At the northerly end -the moraine keeps close to the edge of the chalk cliffs, -which are there 400 feet high, and the hills are frequently -displayed in section; but as the elevation of the cliffs declines -they fall back from the edge of the cliffs and run -quite across the headland of Flamborough, and are again -exposed in section in Bridlington Bay. One remarkable -and significant fact is pointed out, namely, that behind -this moraine, within half a mile and at a lower level, the -country is almost absolutely devoid of any drift whatever.</p> - -<div class="fig_left" style="width: 460px;"> -<a id="fig43" name="fig43"></a> -<img src="images/fig_43.png" width="460" height="427" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 43.</span>—Moraine between Speeton and Flamborough (Lamplugh).</div> -</div> - -<p><span class="pagenum"><a name="Page_157" id="Page_157">« 157 »</a></span></p> - -<p>“The interpretation of these phenomena is as follows: -When the valley-glaciers reached the sea they suffered the -deflection which has been mentioned, partly as the result -of the interference of ice from the east of Scotland, but -also influenced directly by the cause which operated upon -the Scottish ice and gave direction to it—that is, the impact -of a great glacier from Scandinavia, which almost -filled the North Sea, and turned in the eastward-flowing -ice upon the British coast.</p> - -<p>“It is easy to see how this pressure must have forced the -glacier-ice against the Yorkshire coast, but vertical chalk -cliffs 400 feet in height are not readily surmounted by ice -of any thickness, however great, and so it coasted along -and discharged its lateral moraine upon the cliff-tops. As -the cliffs diminished in height we find the moraine farther -inland, and, as I have pointed out, the ice completely overrode -Flamborough Head. Amongst the boulders at Flamborough -are many of Shap granite, a few Galloway granites, -a profusion of Carboniferous rocks, brought by the -Tyne branch of the Sol way Glacier as well as by that of -Stainmoor, and, besides many torn from the cliffs of Yorkshire, -a few examples of unquestionable Scandinavian rocks, -such as the well-known <i>Rhomben-porphyr</i>. It is important -to note that about ten to twenty miles from the Yorkshire -coast there is a tract of sea-bottom called by trawlers -‘the rough ground,’ in allusion to the fact that it -is strewn with large boulders, amongst which are many of -Shap granite. This probably represents a moraine of the -Teesdale Glacier, laid down at a time when the Scandinavian -Glacier was not at its greatest development.</p> - -<p>“On the south side of Flamborough Head the ‘buried -cliff’ previously alluded to occurs. The configuration of -the country shows—and the conclusion is established by -numerous deep-borings—that the preglacial coast-line -takes a great sweep inland from here, and that the plain -of Holderness is the result of the banking-up of an immense -thickness of glacial <i>débris</i>. In the whole country -<span class="pagenum"><a name="Page_158" id="Page_158">« 158 »</a></span> -reviewed, from Tynemouth to Bridlington, wherever the -ice came on to the land from the seaward, it brought in -shells and fragmentary patches of the sea-bottom involved -in its ground moraine. Space does not permit of -a detailed description of the several members of the Yorkshire -Drift, and I pass on to deal in a general way with -the glacial phenomena of the eastern side of England.</p> - -<p>“<i>The East Anglian Glacier.</i>—The influence of the -Scandinavian ice is clearly seen in the fact that the entire -ice-movement down the east coast south of Bridlington -was all from the <i>seaward</i>. Clays, sands, and gravels, the -products of a continuous mass of land-ice coming from -the northeast are spread over the whole country, from the -Trent to the high grounds on the north of London overlooking -the Thames.</p> - -<p>“The line of extreme extension of these drift-deposits -runs from Finchley (near London), in the south across -Hertfordshire, through Cambridgeshire, with outlying -patches at Gogmagog and near Buckingham, and northwestward -over a large portion of Leicestershire into the -upper waters of the Trent, embracing the elevated region -of Palæozoic rocks at Charnwood Forest, near Leicester.</p> - -<p>“Reserving the consideration of the very involved questions -connected with the drifts of the upper part of the -Trent Valley, I may pass on to join the phenomena of the -southeastern counties with those at Flamborough Head. -From Nottinghamshire the limits of the drift of the East -Anglian Glacier seem to run in a direction nearly due -west to east, for the great oolitic escarpment upon which -Lincoln Cathedral is built is absolutely driftless to the -northward of the breach about Sleaford. However, along -the western flank of the oolitic range true boulder-clay -occurs, bordering and doubtless underlying the great fen-tract -of mid-Lincolnshire; and the great Lincolnshire -<span class="pagenum"><a name="Page_159" id="Page_159">« 159 »</a></span> -Wolds appear to have been completely whelmed beneath -the ice.</p> - -<p>“The most remarkable of the deposits in this area is -the Great Chalky Boulder-Clay, which consists of clay containing -much ground-up chalk, and literally packed with -well-striated boulders of chalk of all sizes, from minute -pebbles up to blocks a foot or more in diameter. Associated -with them are boulders of various foreign rocks, and -many flints in a remarkably fresh condition, and still retaining -the characteristic white coat, except where partially -removed by glacial attrition.</p> - -<p>“One of the perplexing features of the glacial phenomena -in the eastern counties of England is the extension -of true chalky boulder-clay to the north London heights -at Finchley and elsewhere; for only the faintest traces are -to be found in the gravel deposits of the Thames Valley -of any wash from such a deposit, or from a glacier carrying -such materials.</p> - -<p>“It has been suggested that the deposit may have been -laid down in an extra-morainic lake, or in an extension of -the North. Sea, but these suggestions leave the difficulty -just where it was. If a lake or sea could exist without -shores, a glacier-stream might equally dispense with banks. -Within the area of glaciation, defined above, abundant -evidence of the action of land-ice is obtainable, though -striated surfaces are extremely rare—a fact attributable to -the softness of the chalk and clays which occupy almost -the whole area. Well-striated surfaces are found on the -harder rocks, as, for example, on the oolitic limestone at -Dunston, near Lincoln.</p> - -<p>“Mr. Skertchly has remarked that the proofs of the -action of land-ice are irrefragable. The Great Chalky -Boulder-Clay covers an area of 3,000 square miles, and attains -an altitude of 500 feet above the sea-level, thus bespeaking, -if the product of icebergs, ‘an extensive gathering-ground -of chalk, having an elevation of more than -500 feet. But where is it? Certainly not in Western -Europe, for the chalk does not attain so great an elevation -except in a few isolated spots.’<a name="FNanchor_70" id="FNanchor_70"></a><a href="#Footnote_70" class="fnanchor">[BR]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_70" id="Footnote_70"></a><a href="#FNanchor_70"><span class="label">[BR]</span></a> Geikie’s Great Ice Age, p. 360.</p> - -<p><span class="pagenum"><a name="Page_160" id="Page_160">« 160 »</a></span></p></div> - -<div class="fig_right" style="width: 679px;"> -<a id="fig44" name="fig44"></a> -<img src="images/fig_44.png" width="679" height="261" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 44.</span>—Diagram-section near Cromer (Woodward). 6. Gravel and sand (Middle Glacial) resting on contorted drift (loam, sand, and marl, -with large included boulders of chalk); 5. Cromer till: 4. Laminated clay and sands (Leda myalis bed); 3. Fresh-water loams and -sands: <i>3a</i>. Black fresh-water bed of Runton (upper fresh-water bed); 2. Forest bed—laminated clays and sands, with roots and <i>débris</i> -of wood, bones of mammalia, estuarine mollusca, etc., the upper part in places penetrated by rootlets (rootlet bed); <i>2a</i>. Weybourn -crag; 1. Chalk with flints; * Large included boulder of chalk.</div> -</div> - -<p><span class="pagenum"><a name="Page_161" id="Page_161">« 161 »</a></span></p> - -<p>“It has been further pointed out by Mr. Skertchly, that -the condition of the flints in this deposit furnishes strong -evidence that they could not have been carried by floating -ice nor upon a glacier, for, in either of the latter events, -there must have been some exposure to the weather, which, -as he remarks, would have rendered them worthless to the -makers of gun-flints, whereas they are now regularly collected -for their use.</p> - -<p>“The way in which the boulder-clay is related to the -rocks upon which it rests is a conclusive condemnation of -any theory of floating ice; for example, where it rests upon -Oxford Clay, it contains the fossils characteristic of -that formation, as it is largely made up of the clay itself. -The exceptions to this rule are as suggestive as those cases -which conform to it. Each outcrop yields material to the -boulder-clay to the south westward, showing a pull-over -from the northeast.</p> - -<p>“One of the most remarkable features of the drift of -this part of England is the inclusion of gigantic masses of -rock transported for a short distance from their native -outcrop, very often with so small a disturbance that they -have been mapped as <i>in situ</i>. Examples of chalk-masses -800 feet in length, and of considerable breadth and thickness, -have been observed in the cliffs near Cromer, in Norfolk, -but they are by no means restricted to situations -near the coast. One example is mentioned in which -quarrying operations had been carried on for some years -before any suspicion was aroused that it was merely an -erratic. The huge boulders were probably dislodged from -the parent rock by the thrust of a great glacier, which first -crumbled the beds, then sheared off a prominent fold and -carried it along. This explanation we owe to Mr. Clement -Reid.<a name="FNanchor_71" id="FNanchor_71"></a><a href="#Footnote_71" class="fnanchor">[BS]</a> The drift-deposits of this region frequently contain -shells, but they rarely constitute what may be termed -a consistent fauna, usually showing such an association as -could only be found where some agent had been at work -gathering together shells of different habitats and geological -age.</p> - -<div class="footnote"> - -<p><a name="Footnote_71" id="Footnote_71"></a><a href="#FNanchor_71"><span class="label">[BS]</span></a> See Geology of the Country around Cromer, and Geology of -Holderness, Memoirs of Geological Survey of England and Wales.</p> - -<p><span class="pagenum"><a name="Page_162" id="Page_162">« 162 »</a></span></p></div> - -<div class="fig_center" style="width: 665px;"> -<a id="fig45" name="fig45"></a> -<img src="images/fig_45.png" width="665" height="189" alt="" /> -<div class="fig_caption"><p><span class="smcap">Fig. 45.</span>—Section at right angles to the cliff through the westerly chalk bluff at Trimingham, Norfolk, showing the manner in which chalk -masses are incorporated into the till (Clement Reid). Scale, 250 fret to an inch. A. Level of low-water spring-tides; B. Chalk, with -sandy bed at *; C. Forest-bed series, etc., seen in the cliffs a few yards north and south of this point; D. Cromer till, stiff lead-colored -boulder-clay; E. Fine, chalky sands, much false-bedded; F. Contorted drift, brown bouldery-clay with marked bedding- or fluxion-structure; -G. The bed, above the white line were seen and measured by more snow and measured by Mr. Reid; * Chalk seen <i>in situ</i> on beach.</p> - -<p>“If the ice-sheet, instead of flowing over the beds, happens to plough into them or abut against them, it would bend up a boss of chalk, -as at Beeston. A more extensive disturbance, like that at Trimingham drives before it a long ridge of the bads, and nips up the chalk, till, -like a cloth creased by the sliding of a heavy book, it is folded into an inverted anticlinal. A slight increase of pressure, and the third -stage is reached—the top of the anticlinal being entirely sheared off, the chalk boulder driven up an incline, and forced into the overlying -boulder-clays.” (Clement Reid.)</p></div> -</div> - -<p><span class="pagenum"><a name="Page_163" id="Page_163">« 163 »</a></span></p> - -<p>“Attempts have been made to correlate the deposits -over the whole area, but with very indifferent success. A -consideration of the consequences of the invasion of the -country by an ice-stream from the northeast will prepare -us for any conceivable complication of the deposits.</p> - -<p>“The main movement was against the drainage of the -country, so that the ice-front must have been frequently -in water. There would be aqueous deposition and erosion; -the kneading up of morainic matter into ground-moraine; -irregularities of distribution and deposition due -to ice floating in an extra-morainic lake; flood-washes at -different points of overflow; and other confusing causes, -which make it rather matter for surprise that any order -whatever is traceable.</p> - -<p>“I now turn to the valley of the Trent. We find that -it occupies such a position that it would be exposed, successively -or simultaneously, to the action of ice-streams -of most diverse origin. I have shown that the area to the -westward of Lichfield was invaded at one period by a -Welsh glacier, and at a subsequent one by the Irish Sea -Glacier, and both of these streams entered the valley of -the Trent or some of its affluents. From the eastward, -again, the great North Sea Glacier encroached in like manner, -carrying the Great Chalky Boulder-Clay even into the -drainage area of the westward-flowing rivers near Coventry.</p> - -<p><span class="pagenum"><a name="Page_164" id="Page_164">« 164 »</a></span></p> - -<p>“The glacial geology of the Trent Valley from Burton -to Nottingham has been ably dealt with by Mr. R. M. -Deeley,<a name="FNanchor_72" id="FNanchor_72"></a><a href="#Footnote_72" class="fnanchor">[BT]</a> who recognises a succession which may be generalised -as follows: (1.) A lower series containing rocks derived -from the Pennine chain; (2.) A middle series containing -rocks from the eastward (chalky boulder-clay, -etc.); and (3.) An upper series with Pennine rocks. Mr. -Deeley thinks the Pennine <i>débris</i> may have been brought -by glaciers flowing down the valleys of the Dove, the Wye, -and the Derwent; but, while recognising the importance -of the testimony adduced, especially that of the boulders, -I am compelled to reserve judgment upon this point until -something like moraines or other evidences of local glaciers -can be shown in those valleys. In their upper parts there -is not a sign of glaciation. Some of the deposits described -must have been laid down by land-ice; while the -conformation of the country shows that during some stages -of glaciation a lake must have existed into which the different -elements of the converging glaciers must have projected. -This condition will account for the remarkable -commingling of boulders observed in some of the deposits. -Welsh, Cumbrian, and Scottish rocks occur in the western -portion of the Trent Valley. The overflow of the extra-morainic -lake would find its way into the valleys of the -Avon and Severn, and may be taken to account for the -abundance of flints in some of the gravels.</p> - -<div class="footnote"> - -<p><a name="Footnote_72" id="Footnote_72"></a><a href="#FNanchor_72"><span class="label">[BT]</span></a> Quarterly Journal Geological Society, vol. xlii, p. 437.</p></div> - -<p>“<i>The Isle of Man.</i>—This little island in mid-seas constituted -in the early stages of the Glacial epoch an independent -centre of glaciation, and from some of its valleys -ice-streams undoubtedly descended to the sea; but with -the growth of the great Irish Sea Glacier the native ice -was merged in the invading mass, and at the climax of the -period the whole island was completely buried, even to its -highest peak (Snae Fell, 2,054 feet), beneath the ice. The -<span class="pagenum"><a name="Page_165" id="Page_165">« 165 »</a></span> -effects of this general glaciation are clearly seen in the -mantle of unstratified drift material which overspread the -hills; in the <i>moutonnée</i> appearance of the entire island; -and in the transport of boulders of local rocks. The -striations upon rock surfaces show a constancy of direction -in agreement with the boulder-transport which can -be ascribed to no other agency than a great continuous -sheet of such dimensions as to ignore minor hills and -valleys.</p> - -<p>“The disposition of the striæ is equally conclusive, for -we find that on a stepped escarpment of limestone both -the horizontal and the vertical faces are striated continuously -and obliquely from the one on to the other, showing -that the ice had a power of accommodating itself to the -surface over which it passed that could not be displayed -by floating ice. There is a remarkable fact concerning -the distribution of boulders on this island which would -strike the most superficial observers, namely, that foreign -rocks are confined to the low grounds. It might be -argued that the local ice always retained its individuality, -and so kept the foreign ice with its characteristic boulders -at bay. But, apart from the <i>a priori</i> improbability of so -small a hill-cluster achieving what the Lake District -could not accomplish, the fact that Snae Fell, an isolated -<i>conical</i> hill, is swathed in drift from top to bottom, is -quite conclusive that the foreign ice must have got in. -Why, then, did it carry no stones with it? The following -suggestion I make not without misgivings, though there -are many facts to which I might appeal that seem strongly -corroborative:</p> - -<p>“The hilly axis of the island runs in a general northeast -and southwest direction, and it rises from a great -expanse of drift in the north with singular abruptness, -some of the hills being almost inaccessible to a direct approach -without actual climbing. I imagine that the ice -which bore down upon the northern end of the island -<span class="pagenum"><a name="Page_166" id="Page_166">« 166 »</a></span> -was, so far as its lower strata were concerned, unable to -ascend so steep an acclivity, and was cleft, and flowed to -right and left. The upper ice, being of ice-sheet origin, -would be relatively clean, and this flowing straight over -the top of the obstruction would glaciate the country -with such material as was lying loose upon the ground or -could be dislodged by mere pressure. It would appear -from published descriptions that the Isle of Arran offers -the same problem, and I would suggest the application of -the same solution to it.</p> - -<p>“Marine shells occur in the Manx drift, but only in -such situations as were reached by the ice-laden with -foreign stones. They present similar features of association -of shells of different habitat, and perhaps of geological -age, to those already referred to as being common -characteristics of the shell-faunas of the drift of the -mainland. Four extinct species of mollusca have been -recognised by me in the Manx drift.</p> - -<p>“The Manx drift is of great interest as showing, perhaps -better than any locality yet studied, those features -of the distribution of boulders of native rocks which attest -so clearly the exclusive action of land-ice. There -are in the island many highly characteristic igneous -rocks, and I have found that boulders of these rocks -never occur to the northward of the parent mass, and -very rarely in any direction except to the southwest.</p> - -<p>“Cumming observed in regard to one rock, the Foxdale -granite, that whereas the highest point at which it occurs -<i>in situ</i> was 657 feet above sea-level, boulders of it occurred -in profusion within 200 feet of the summit of South Barrule -(1,585 feet), a hill two miles only, in a southwesterly -direction, from the granite outcrop.</p> - -<p>“They also occur on the summit of Cronk-na-Irrey-Lhaa, -1,449 feet above sea-level. The vertical uplift has -been 728 and 792 feet respectively.</p> - -<p>“In the low grounds of the north of the island a finely -<span class="pagenum"><a name="Page_167" id="Page_167">« 167 »</a></span> -developed terminal moraine extends in a great sweep -so as to obstruct the drainage and convert thousands -of acres of land into lake and morass, which is only now -yielding to artificial drainage. Many fine examples of -drumlin and esker mounds occur at low levels in different -parts of the island; and it was remarked nearly fifty -years ago by Cumming, that their long axes were parallel -to the direction of ice-movement indicated by the striated -surfaces and the transport of boulders.</p> - -<p>“The foreign boulders are mainly from the granite -mountains of Galloway, but there are many flints, presumably -from Antrim, a very small number of Lake District -rocks, and a remarkable rock containing the excessively -rare variety of hornblende, Riebeckite. This has -now been identified with a rock on Ailsa Crag, a tiny -islet in the Frith of Clyde; and a Manx geologist, the -Rev. S. N. Harrison, has discovered a single boulder of -the highly characteristic pitchstone of Corriegills, in the -Isle of Arran.</p> - - -<p>“<i>The So-called Great Submergence.</i></p> - -<p>“It may be convenient to adduce some additional facts -which render the theory of a great submergence of the -country south of the Cheviots untenable.</p> - -<p>“The sole evidence upon which it rests is the occurrence -of shells, mostly in an extremely fragmentary condition, -in deposits occurring at various levels up to about -1,400 feet above sea-level: A little space may profitably -be devoted to a criticism of this evidence.</p> - -<p>“<i>Moel Tryfaen</i> (‘The Hill of the Three Rocks’).—This -celebrated locality is on the first rise of the ground between -the Menai Straits and the congeries of hills constituting -‘Snowdonia’; and when we look to the northward from -the top of the hill (1,350 feet) we see the ground rising -from the straits in a series of gentle undulations whose -smooth contours would be found from a walk across the -<span class="pagenum"><a name="Page_168" id="Page_168">« 168 »</a></span> -country to be due to the thick mask of glacial deposits -which obliterates the harsher features of the solid rocks.</p> - -<p>“The deposits on Moel Tryfaen are exposed in a slate-quarry -on the northern aspect of the hill near the summit, -and consist of two wedges of structureless boulder-clay, -each thinning towards the top of the hill. The lower mass -of clay, wherever it rests upon the rock, contains streaks -and irregular patches of eccentric form, of sharp, perfectly -angular fragments of slate; and the underlying rock may -be seen to be crushed and broken, its cleavage-laminæ -being thrust over from northwest to southeast—that is, -<i>up-hill</i>. The famous ‘shell-bed’ is a thick series of -sands and gravels interosculated with the clays on the -slope of the hill, but occupying the entire section above the -slate towards the top. The bedding shows unmistakable -signs of the action of water, both regular stratification and -false bedding being well displayed. The stones occurring -in the clays are mainly if not entirely Welsh, including -some from the interior of the country, and they are not infrequently -of large size—two or three tons’ weight—and -well scratched.</p> - -<p>“The stones found in the sands and gravels include a -great majority of local rocks, but besides these there have -been recorded the following:</p> - -<table summary="rocks"> -<tr> - <td class="center bdt bdb">Rock.</td> - <td class="center bdt bdb bdl">Source.</td> - <td class="center bdt bdb bdl">Highest<br />point<br /><i>in situ</i>.</td> - <td class="center bdt bdb bdl">Minimum<br />uplift<br />in feet.</td> -</tr> -<tr> - <td class="tdl">Granite</td> - <td class="tdl bdl">Eskdale, Cumberland</td> - <td class="tdr bdl">1,286</td> - <td class="tdr bdl">64</td> -</tr> -<tr> - <td class="tdl">Granite</td> - <td class="tdl bdl">Criffel, Galloway</td> - <td class="tdr bdl">.....</td> - <td class="tdr bdl">...</td> -</tr> -<tr> - <td class="tdl">Flint</td> - <td class="tdl bdl">Antrim (?)</td> - <td class="tdr bdl">1,000</td> - <td class="tdr bdl">350</td> -</tr> -<tr> - <td class="tdl"> To these I can add:</td> - <td class="tdr bdl"></td> - <td class="tdr bdl"></td> - <td class="tdr bdl"></td> -</tr> -<tr> - <td class="tdl">Granophyre</td> - <td class="tdl bdl">Buttermere, Cumberland</td> - <td class="tdr bdl">.....</td> - <td class="tdr bdl">...</td> -</tr> -<tr> - <td class="tdl bdb">Eurite <a name="FNanchor_73" id="FNanchor_73"></a><a href="#Footnote_73" class="fnanchor">[BU]</a></td> - <td class="tdl bdb bdl">Ailsa Craig, Frith of Clyde</td> - <td class="tdr bdb bdl">1,097</td> - <td class="tdr bdb bdl">253</td> -</tr> -</table> - -<div class="footnote"> - -<p><a name="Footnote_73" id="Footnote_73"></a><a href="#FNanchor_73"><span class="label">[BU]</span></a> The altitude at which this rock occurs on Ailsa Craig has not -been announced, so 1 have put it as the extreme height of the island.</p> - -<p><span class="pagenum"><a name="Page_169" id="Page_169">« 169 »</a></span></p></div> - -<p>“The shells in the Moel Tryfaen deposit have been fully -described, so far as the enumeration of species and relative -frequency are concerned, but little has been said as to -their absolute abundance and their condition. The shells -are extremely rare, and daring a recent visit a party of -five persons, in an assiduous search of about two hours, succeeded -in finding <i>five whole shells</i> and about two ounces of -fragments. The opportunities for collecting are as good -as could be desired. The sections exposed have an aggregate -length of about a quarter of a mile, with a height -varying from ten to twenty feet of the shelly portion; and -besides this there are immense spoil-banks, upon whose -rain-washed slopes fossil-collecting can be carried on under -the most favorable conditions.</p> - -<p>“I would here remark, that the occurrence of small -seams of shelly material of exceptional richness has impressed -collectors with the idea that they were dealing with -a veritable shell-bed, when the facts would bear a very different -interpretation. A fictitious abundance is brought -about by a process of what may be termed ‘concentration,’ -by the action of a gently flowing current of water upon -materials of different sizes and different specific gravities. -Shells when but recently vacated consist of materials of -rather high specific gravity, penetrated by pores containing -animal matter, so that the density of the whole mass -is far below that of rocks in general, and hence a current -too feeble to move pebbles would yet carry shells. Illustrations -of this process may be observed upon any shore -in the concentration of fragments of coal, corks, or other -light material.</p> - -<p>“Regarding the interpretation of these facts: The commonly -received idea is, that the beds were laid down in the -sea during a period of submergence, and that the shells -lived, not perhaps on the spot, but somewhere near, and -that the terminal curvature of the slate was produced by -the grounding of icebergs which also brought the boulders. -<span class="pagenum"><a name="Page_170" id="Page_170">« 170 »</a></span> -But if this hypothesis were accepted, it would be -necessary to invest the flotation of ice with a constancy of -direction entirely at variance with observed facts, for the -phenomena of terminal curvature is shown" with perfect -persistence of direction wherever the boulder-clay rests -upon the rock; and, further, there is the highly significant -fact, that neither the sands and gravels nor the rock -upon which they rest show any signs of disturbance or -contortion, such as must have been produced if floating -ice had been an operative agent.</p> - -<p>“The uplift of foreign rocks is equally significant; and -when we take into account the great distances from which -they have been borne and the frequency with which such -an operation must have been repeated, the inadequacy becomes -apparent of Darwin’s ingenious suggestion, that it -might have been effected by a succession of uplifts by -shore-ice during a period of slow subsidence; while the -character and abundance of the molluscan remains invest -with a species of irony the application of the term ‘shell-bed’ -to the deposit.</p> - -<p>“I now turn to the alternative explanation (see <i>ante</i>, -<a href="#Page_145">p. 145</a>), viz., that the whole of the phenomena were produced -by a mass of land-ice which was forced in upon Moel Tryfaen -from the north or northwest, overpowering any Welsh -ice which obstructed its course. This view is in harmony -with the observations regarding the ‘terminal curvature’ -of the slates, the occurrence of sharp angular chips of slate -in the boulder-clay, and the coincidence of direction of -these indications of movement with the carry of foreign -stones. The few shells and shell-crumbs in the sands and -gravels would, upon this hypothesis, be the infinitesimal -relics of huge shell-banks in the Irish Sea which were -destroyed by the glacier and in part incorporated in its -ground-moraine or involved in the ice itself. The sands -and gravels would represent the wash which would take -place wherever, by the occurrence of a ‘nunatak’ or by -<span class="pagenum"><a name="Page_171" id="Page_171">« 171 »</a></span> -approach to the edge of the ice, water could have a free -escape.</p> - -<p>“Two principal objections have been urged to the land-ice -explanation of the Moel Tryfaen deposits. An able -critic asks, ‘Can, then, ice walk up-hill?’ To this we -answer, Given a sufficient ‘head’ behind it, and ice can -certainly achieve that feat, as every <i>roche moutonnée</i> -proves. If it be granted that ice on the small scale can -move up-hill, there is no logical halting-place between the -uplift of ten or twenty feet to surmount a <i>roche moutonnée</i>, -and an equally gradual elevation to the height of Moel -Tryfaen. Furthermore, the inland ice of Greenland is -known to extrude its ground-moraine on the ‘weather-side’ -of the nunataks, and the same action would account -for the material uplifted on Moel Tryfaen.</p> - -<p>“The second objection brought forward was couched in -somewhat these terms: ‘If the Lake District had its ice-sheet, -surely Wales had one also. Could not Snowdonia -protect the heart of its own domain?’ Of course, Wales -had its ice-sheet, and the question so pointedly raised by -the objector needs an answer; and though it is merely a -question of how much force is requisite to overcome a certain -resistance (both factors being unknown), still there -are features in the case which render it specially interesting -and at the same time comparatively easy of explanation. -It seems rather like stating a paradox, yet the fact -is, that it was the proximity of Snowdon which, in my -opinion, enabled the foreign ice to invade Wales at that -point.</p> - -<p>“A glance at the map will show that the ‘radiant point’ -of the Welsh ice was situated on or near Arenig Mawr, and -that the great mass of Snowdon stands quite on the periphery -of the mountainous regions of North Wales, so -that it would oppose its bulk to fend off the native ice-sheet -and prevent it from extending seaward in that direction.</p> - -<p><span class="pagenum"><a name="Page_172" id="Page_172">« 172 »</a></span></p> - -<div class="fig_center" style="width: 651px;"> -<a id="fig46" name="fig46"></a> -<img src="images/fig_46.png" width="651" height="96" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 46.</span>—Section across Wales to show the relationship of native to foreign ice.</div> -</div> - -<p>“As a consequence, the only Welsh -ice in position to obstruct the onward -march of the invader would be such -trifling valley-glaciers as could form -on the western slopes of Snowdon itself.</p> - -<p>“The peak of Snowdon is 3,570 -feet above sea-level, and Arenig Mawr, -2,817 feet high, is eighteen miles to -the eastward, and a broad, deep valley -with unobstructed access to Cardigan -Bay intervenes; so, if any ice from -the central mass made its way over -the Snowdonian range, it performed -a much more surprising feat than that -involved in the ascent of Moel Tryfaen -from the westward.</p> - -<p>“The profile shows in diagrammatic -form the probable relations of the -foreign to the native ice at the time -when the Moel Tryfaen deposits were -laid down.</p> - -<p>“From what has been said regarding -the great glaciers, it would seem -that ice advanced upon the land from -the seaward in several parts of the -coast of England, Wales, and the Isle -of Man. Now, it is in precisely those -parts of the country, and those alone, -that the remains of marine animals -occur in the glacial deposits. If the -dispersal of the shells found in the -drift had been effected by the means -I have suggested, it would follow, as -an inevitable consequence, that wherever -shells occur there should also -<span class="pagenum"><a name="Page_173" id="Page_173">« 173 »</a></span> -be boulders which have been brought from beyond the -sea. This I find to be the case, and in two instances the -discovery of shells was preliminary to the extension of the -boundaries of the known distribution of boulders of trans-marine -origin.</p> - -<p>“The officers of the Geological Survey some years ago -observed the occurrence of ‘obscure fragments of marine -shells’ in a deposit at Whalley, Lancashire, in which they -could find only local rocks. One case such as this would -be fatal to the theory of the <i>remanié</i> origin of the shells, -but on visiting the section with Mr. W. A. Downham, I -found, amongst the very few stones which occurred in the -shell-bearing sand at the spot indicated, two well-marked -examples of Cumbrian volcanic rocks, and, at a little distance, -large boulders of Scottish granites.</p> - -<p>“The second case is more striking. The announcement -was made that shells had been found on a hill called Gloppa -near Oswestry, in Shropshire, and, as it lay about five miles -to the westward of Mackintosh’s boundary of the Irish Sea -Glacier, and therefore well within the area of exclusively -Welsh boulders, it furnished an excellent opportunity of -putting the theory to the test. An examination of the -boulders associated with the shells showed that the whole -suite of Galloway and Cumbrian erratics such as belong to -the Irish Sea Glacier were present in great abundance. -Not only this, but in the midst of the series of shell-bearing -gravels I observed a thin lenticular bed of greenish -clay, which upon examination was found to be crowded -with well-scratched specimens of Welsh rocks; but neither -a morsel of shell nor a single pebble of a foreign rock -could be found, either by a careful examination in the -field or by washing the clay at home, and examining with -a lens the sand and stones separated out.</p> - -<p>“The fact that predictions such as these have been verified -affords a very striking corroboration of the theory put -forward; and, though shells cannot be found in every -<span class="pagenum"><a name="Page_174" id="Page_174">« 174 »</a></span> -deposit in which they might, <i>ex hypothesi</i>, be found, yet -the strict limitation of them to situations which conform -to those assigned upon theoretical grounds cannot be ascribed -to mere coincidence. If the land had ever been -submerged during any part of the Glacial epoch to a depth -of 1,400 feet, it is inconceivable that clear and indisputable -evidence should not be found in abundance in the sheltered -valleys of the Lake District and Wales, which would -have been deep, quiet fiords, in which vast colonies of marine -creatures would have found harbour, as they do in the -deep lochs of Scotland to-day.</p> - -<p>“It has been urged, in explanation of this absence of -marine remains in the great hill-centres, that the ‘second -glaciation’ might have destroyed them; but to do this -would require that the ice should make a clean and complete -sweep of all the loose deposits both in the hollows of -the valleys and on the hill-sides, and further that it should -destroy all the shells and all the foreign stones which -floated in during the submergence. At the same time we -should have to suppose that the drift which lay in the -paths of the great glaciers was not subjected to any interference -whatever. But, assuming that these difficulties -were explained, there would still remain the fact that the -valleys which have never been glaciated—as, for example, -those of Derbyshire—show no signs whatever of any marine -deposits, nor of marine action in any form whatever.</p> - -<p>“The sea leaves other traces also, besides shells, of its -presence in districts that have really been submerged, yet -there are no signs whatever to be found of them in all England, -except the <i>post</i>-glacial raised beaches. Furthermore, -in all the area occupied by glacial deposits there are no true -sea-beaches, no cliffs nor sea-worn caves, no barnacle-encrusted -rocks, nor rocks bored by Pholas or Saxicava. -Are we to believe that these never existed; or that, having -existed, they have been obliterated by subsequent denudations? -To make good the former proposition, it would be -<span class="pagenum"><a name="Page_175" id="Page_175">« 175 »</a></span> -necessary as a preliminary to show that the movement of -subsidence and re-elevation was so rapid, and the interval -between so brief, that no time was allowed for any marine -erosion to take place. If this were so, it would be the most -stupendous catastrophe of which we have any geological -record; but we are not left in doubt regarding the duration -of the submerged condition, for the occurrence of forty feet -of gravel upon the summits of the hills indicates plainly -that, if they were accumulated by the sea, the land must -have stood at that level for a very long period, amply sufficient -for the formation of a well-marked coast-line.</p> - -<p>“The alternative proposition, that post-glacial denudation -had removed the traces of subsidence, is equally at -variance with the evidence. Post-glacial denudation has -left kames and drumlins, and all the other forms of glacial -deposits, in almost perfect integrity; the small kettle-holes -are not yet filled up; and it is therefore quite out of the -question that the far more enduring features, such as sea-cliffs, -shore platforms, and beaches, should have been destroyed.</p> - -<p>“The only reasonable conclusion is, that these evidences -of marine action never existed, because the land in glacial -times was never depressed below its present level. If the -level were different at all (as I think may have been the -case on the western side of England), it was higher, and -not lower.</p> - -<p>“The details of the submergence hypothesis have, so far -as I am aware, never been dealt with by its advocates, otherwise -I cannot but think that it would have been abandoned -long since. It has been stated in general terms that -the subsidence was greatest in the north and diminished -to zero in the south, but no attempt was made to trace the -evidence of extreme subsidence across country and along -the principal hill-ranges—in fact, to see how it varied in -every direction.</p> - -<p>“If we take a traverse of England, say from Flamborough -<span class="pagenum"><a name="Page_176" id="Page_176">« 176 »</a></span> -Head upon -the east to Moel -Tryfaen on the west, -and accept as evidence -of submergence -any true glacial -deposits (except, -as in the case of the -interior of Wales, -the deposits are obviously -the effects of -purely local glaciers -and contain, therefore, -no shells), we -shall find that the -subsidence, if any, -must have been not -simply differential -but sporadic.</p> - -<div class="fig_center" style="width: 655px;"> -<a id="fig47" name="fig47"></a> -<img src="images/fig_47.png" width="655" height="176" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 47.</span>—Section of the cliff on the east side of South Sea Landing, Flamborough Head. Scale, 120 feet to 1 inch; length of section 290 -yards; average height, 125 feet. (See above map of moraine between Speeton and Flamborough.)<br /> -<br /> -Explanation.—<i>4.</i> Brownish boulder-clay, a band of pebbles; <i>4a</i>, in places about seven feet from top. <i>3.</i> Washed gravel, with thin -sand-seams, well-bedded, pebbles chiefly erratics. <i>2.</i> “Basement” boulder-clay, with many included patches of sand, gravel, and -silt; <i>2a</i>, at <i>B</i>, one of these <i>2b</i> contain shells. <i>1b</i>. Sand and silt, overlying and in places interbedded with <i>1</i>. <i>1.</i> Rubble of angular and -subangular chalk-blocks and gravel, with occasional erratic, passes partly into chalky boulder-clay, <i>1a</i>. <i>x</i>. White chalk, without -flints, surface much shaken.</div> -</div> - -<p>“At Flamborough -Head shelly drift attains -an altitude of -400 feet, but half a -mile from the coast -the country is practically -driftless even -at lower levels. The -Yorkshire Wolds -were not submerged. -On the western flanks -of the wolds drift -comes in at about -100 to 150 feet, and -persists, probably, -under the post-glacial -warp, from -<span class="pagenum"><a name="Page_177" id="Page_177">« 177 »</a></span> -which it again protrudes -on the western side of -the valley of the Ouse, -and however the drift -between there and the -Pennine water-shed -may be interpreted, it -shows not a sign of marine -origin; but, even -granting that it did, we -find that it does not -reach within a thousand -feet of the water-shed. -When the water-shed is -crossed, however, abundant -glacial deposits are -met with which are not -to be differentiated from -others at slightly lower -levels which contain -shells.</p> - -<div class="fig_center" style="width: 664px;"> -<a id="fig48" name="fig48"></a> -<img src="images/fig_48.png" width="664" height="179" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 48.</span>—Enlarged section of the shelly sand and surrounding clay at <i>B</i> in preceding figure. Scale, 4 feet to 1 inch.<br /> -<br /> -Explanation.—<i>2.</i> “Basement” boulder-clay. <i>2a</i>. Pure compact blue and brown clay of aqueous origin, bedding contorted and nearly -obliterated, but the mass is cut up by shearing planes. <i>2b</i>. Irregular seam, and scattered streaks, of greenish-yellow sand with many -marine shells. <i>2c</i>. Patch of pale-yellow sand, different from <i>2b</i>, without trace of fossils.</div> -</div> - -<p>“If we suppose that -the line of our traverse -crosses the Pennine -Chain at Heald Moor, -we shall find that on -the eastern side no -traces of drift occur -above about 300 feet; -while the very summit -of the water-shed is occupied -by boulder-clay, -and thence downward -the trace is practically -continuous, and at about -1,000 feet and downward -<span class="pagenum"><a name="Page_178" id="Page_178">« 178 »</a></span> -the drift contains marine shells. Across the great -plain of Lancashire and Cheshire the ‘marine’ drift is -fully developed—though it may be remarked in parentheses -that it contains a shallow-water fauna, albeit <i>ex hypothesi</i> -deposited, in part at least, in a depth of 200 fathoms -of water—and to the Welsh border at Frondeg, where -it again reaches a water-shed at an altitude of 1,450 feet; -but at 100 yards to the westward of the summit all traces -of subsidence disappear, and through the centre of Wales -no sign is visible; then we emerge on the western slopes -at Moel Tryfaen, and they assume their fullest dimensions, -though only to finish abruptly on the hill-top, and put in -no appearance in the lower grounds which extend from -there to the sea.</p> - -<p>“The conclusions pointed to by the evidence (and, as I -have endeavoured to show, all the evidence which existed -at the close of the Glacial period is there still) are, that -a subsidence of the Yorkshire Wolds took place on the -east, but not in the centre or west; that the Pennine Chain -was submerged on the western side to a depth of 1,400 -feet, and on the east to not more than 300 feet, even on opposite -sides of the same individual hill; that all the lowlands -between, say, Bacup and the Welsh border, were submerged, -and that the hills near Frondeg partook of this -movement, but only on their eastern sides; that the centre -of Wales was exempt, but that the summit of Moel -Tryfaen forms an isolated spot submerged, while the surrounding -country escaped. These absurdities might be -indefinitely multiplied, and they must follow unless it be -admitted that the phenomena are the results of glacial ice, -and that ice can move ‘up-hill.’</p> - -<p>“The south of England certainly has partaken of no -movement of subsidence. A line drawn from Bristol to -London will leave all the true glacial deposits to the northward, -except a bed of very questionable boulder-clay at -Watchet, and a peculiar deposit of clayey rubble which -<span class="pagenum"><a name="Page_179" id="Page_179">« 179 »</a></span> -has been produced on the flanks of the Cornish hills probably, -as the late S. V. Wood, Jr, suggested, by the slipping -of material over a permanently frozen subsoil.</p> - -<p>“For the remainder of the southern area the evidence is -plain that there has been no considerable subsidence during -glacial times. The presence over large areas of chalk -country of the ‘clay with flints’—a deposit produced by -the gradual solution of the chalk and the accumulation -in situ of its insoluble residue—is absolute demonstration -that for immense periods of time the country has been exempt -from any considerable aqueous action. The enormous -accumulations of china clay upon the granite bosses -of Cornwall and Devon tell the same tale. A few erratics -have been found at low levels at various points on the -southern coasts, usually not above the reach of the waves. -These consist of rocks which may have been floated by -shore-ice from the Channel Islands or the French coast.</p> - -<p>“This imperfect survey of the evidence against the supposed -submergence has been rendered the more difficult by -the fact that it is not considered necessary to produce the -evidence of marine shells in all cases. Indeed, it has been -argued that post-Tertiary beds covering thousands of square -miles might be absolutely destitute of shells without prejudice -to the theory of their formation in the sea.</p> - -<p>“But such a suggestion, one would think, could hardly -come from anyone familiar with marine Tertiary deposits, -or even with the appearance of modern sea-beaches. Admitting, -however, for the purposes of argument, that the -beaches along a great extent of coast might be devoid of -shells, it cannot be argued that the deep waters were destitute -of life; and hence the boulder-clays, if of marine origin, -should contain a great abundance of shells and other remains, -and, once entombed, it is beyond belief that they -could all be removed from such a deposit in the short lapse -of post-glacial time.</p> - -<p>“Now, some of the boulder-clays—as, for example, those -<span class="pagenum"><a name="Page_180" id="Page_180">« 180 »</a></span> -of Lancashire and Cheshire—are held to be of marine origin, -and this is indeed a vital necessity to the submergence -theory; for, if these are not marine deposits, neither are the -other shelly deposits; but these boulder-clays are absolutely -indistinguishable from those lying within the hill-centres, -and, as it passes belief that such deposits could be -of diverse origin and yet possess an identical structure and -arrangement, then we should have a right to demand that -these clays should have enclosed shells and should still contain -them, but they do not.</p> - -<p>“I may here mention that I am informed by Mr. W. -Shone, F. G. S.—and he was good enough to permit me to -quote the statement—that the boulder-clay of Cheshire and -the shelly boulder-clay of Caithness are ‘as like as two -peas.’ The importance of this comparison lies in the fact -that, since Croll’s classical description, all observers have -agreed that it was the product of land-ice which moved in -upon the land out of the Dornoch Firth. It was pointed -out then, as since has been done for England, that it was -only where the direction of ice-movement was from the -seaward that any shells occur in the boulder-clay.</p> - -<p>“<i>The Dispersion of Erratics of Shap Granite.</i>—So -great a significance attaches to the peculiar distribution -of this remarkable rock, that I may add a few details here -which could not be conveniently introduced elsewhere.</p> - -<p>“This granite occupies an area which lies just to the -northward of the water-shed between the basins of the -Lime and the Eden, and its extreme elevation is 1,656 feet. -Boulders occur in large numbers as far to the northward -as Cross Fells, while, as already described, they pass over -Stainmoor and are dispersed in great numbers along the -route taken by the great Stainmoor branch of the Solway -Glacier. But a considerable number of the boulders -also found their way to the southward, and a well-marked -trail can be followed down into Morecambe Bay; and at -Hest Bank, to the north of Lancaster, the boulder-clay -<span class="pagenum"><a name="Page_181" id="Page_181">« 181 »</a></span> -contains many examples, together with the ‘mica-trap’ -of the Kendal and Sedbergh dykes and other local rocks, -but no shells or erratics from other sources than the -country draining into Morecambe Bay. To the southward -the ice which bore these rocks was deflected by the -great Irish Sea Glacier, and, so far as present information -enables me to state, the Shap granite blocks mark the -course of the medial moraine between these two ice-streams. -It has been found near Garstang, at Longridge, and at -Whalley, this being the exact line of junction of the Irish -Sea Glacier with the ice from Morecambe Bay and the -Pennine Chain.</p> - -<p>“It is a very remarkable and significant fact, that not -a single authentic occurrence of the rock across the boundary -indicated has yet been recorded.”</p> - - -<p class="caption3nb"><i>Northern Europe.</i></p> - -<p>On passing over the shallow German Sea from England -to the Continent, the southern border of the Scandinavian -ice-field is found south of the Zuyder Zee, between -Utrecht and Arnhem—the moraine hills in the vicinity of -Arnhem being quite marked, and a barren, sandy plain -dotted with boulders and irregular moraine hills extending -most of the way to the Zuyder Zee. From Arnhem the -southern boundary of the great ice-field runs “eastward -across the Rhine Valley, along the base of the Westphalian -Hills, around the projecting promontory of the Hartz, and -then southward through Saxony to the roots of the Erzgebirge. -Passing next southeastward along the flanks of the -Riesen and Sudeten chain, it sweeps across Poland into -Russia, circling round by Kiev, and northward by Nijni-Novgorod -towards the Urals.”<a name="FNanchor_74" id="FNanchor_74"></a><a href="#Footnote_74" class="fnanchor">[BV]</a> Thence the boundary -passes northward to the Arctic Ocean, a little east of the -White Sea.</p> - -<div class="footnote"> - -<p><a name="Footnote_74" id="Footnote_74"></a><a href="#FNanchor_74"><span class="label">[BV]</span></a> A. Geikie’s Text-Book of Geology, p. 885.</p> - -<p><span class="pagenum"><a name="Page_182" id="Page_182">« 182 »</a></span></p></div> - -<p>The depth of this northern ice-sheet is proved to have -been upwards of 1,400 feet where it met the Hartz Mountains, -for it has deposited northern <i>débris</i> upon them to -that height; while, as already shown, it must have been -over 2,000 feet in the main valley of Switzerland. In -Norway it is estimated that the ice was between 6,000 -and 7,000 feet thick.</p> - -<p>The amount of work done by the continental glaciers -of Europe in the erosion, transportation, and deposition of -rock and earthy material is immense. According to Helland, -the average depth of the glacial deposits over North -Germany and northwestern Russia is 150 German feet, -i. e., about 135 English feet. As the deposition towards -the margin of a glacier must be commensurate with its -erosion near the centre of movement, this vast amount -implies a still greater proportionate waste in the mountains -of Scandinavia, where the area diminishes with every -contraction of the circle. Two hundred and fifty feet is -therefore not an extravagant calculation for the amount -of glacial erosion in the Scandinavian Peninsula.</p> - -<p>It is not difficult to see how the Scandinavian mountains -were able to contribute so much soil to the plains of -northern Germany and northwestern Russia. Previous to -the Glacial period, a warm climate extended so far north as -to permit the growth of semi-tropical vegetation in Spitsbergen, -Greenland, and the northern shores of British -America. Such a climate, with its abundant moisture -and vegetation, afforded most favourable conditions for the -superficial disintegration of the rocks. When, therefore, -the cold of the Glacial period came on, the moving currents -of ice would have a comparatively easy task in stripping -the mantle of soil from the hills of Norway and -Sweden, and transporting it towards the periphery of its -movement. Of course, erosion in Scandinavia meant -subglacial deposition beyond the Baltic. Doubtless, therefore, -the plains of northern Germany, with their great -<span class="pagenum"><a name="Page_183" id="Page_183">« 183 »</a></span> -depth of soil, are true glacial deposits, whose inequalities -of surface have since been much obliterated, through the -general influences of the lapse of time, and by the ceaseless -activity of man.</p> - -<p>An interesting series of moraines in the north of Germany, -bordering the Baltic Sea, was discovered in 1888 by -Professor Salisbury, of the United States Geological Survey. -Its course lies through Schleswig-Holstein, Mecklenburg, -Potsdam (about forty miles north of Berlin), -thence swinging more to the north, and following nearly -the line between Pomerania and West Prussia, crossing -the Vistula about twenty miles south of Dantzic, thence -easterly to the Spirding See, near the boundary of Poland.</p> - -<p>Among the places where this moraine can be best seen -are—“1. In Province Holstein, the region about (especially -north of) Eutin; 2. Province Mecklenburg, north of -Crivitz, and between Bütow and Kröpelin; 3. Province -Brandenburg, south of Reckatel, between Strassen and -Bärenbusch, south of Fürstenberg and north of Everswalde, -and between Pyritz and Solden; 4. Province Posen, -east of Locknitz, and at numerous points to the south, and -especially about Falkenburg, and between Lompelburg and -Bärwalde. This is one of the best localities. 5. Province -West Preussen, east of Bütow; 6. Province Ost Preussen, -between Horn and Widikin.”</p> - -<p>Comparing these with the moraines of America, Professor -Salisbury remarks:</p> - -<p>“In its composition from several members, in its variety -of development, in its topographic relations, in its topography, -in its constitution, in its associated deposits, and -in its wide separation from the outermost drift limit, this -morainic belt corresponds to the extensive morainic belt -of America, which extends from Dakota to the Atlantic -Ocean. That the one formation corresponds to the other -does not admit of doubt. In all essential characteristics -they are identical in character. What may be their relations -in time remains to be determined.”</p> - -<p><span class="pagenum"><a name="Page_184" id="Page_184">« 184 »</a></span></p> - -<div class="fig_center" style="width: 715px;"> -<a id="fig49" name="fig49"></a> -<img src="images/fig_49.png" width="715" height="436" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 49.</span>—Map showing the glaciated area of Europe according to J. Geikie, and -the moraines in Britain and Germany according to Lewis and Salisbury.</div> -</div> - -<p><span class="pagenum"><a name="Page_185" id="Page_185">« 185 »</a></span></p> - -<p>The physical geography of Europe is so different from -that of America, that there was a marked difference in -the secondary or incidental effects of the Glacial period -upon the two regions. In America the continental area -over which the glaciers spread is comparatively simple in -its outlines. East of the Rocky Mountains, as we have -seen, the drainage of the Glacial period was, for a time, -nearly all concentrated in the Mississippi basin, and the -streams had a free course southward.</p> - -<p>But in Europe there was no free drainage to the south, -except over a small portion of the glaciated area in central -Russia, about the head-waters of the Dnieper, the Don, -and the Volga; though the Danube and the Rhône afforded -free course for the waters of a portion of the great -Alpine glaciers. But all the great rivers of northern -Europe flow to the northward, and, with the exception of -the Seine, they all for a time encountered the front of the -continental ice-sheet. This circumstance makes it difficult -to distinguish closely between the direct glacial -deposits in Europe and those which are more or less -modified by water-action. At first sight it would seem -also somewhat hazardous to attempt to correlate with any -portion of the Glacial period the deposition of the gravelly -and loamy deposits in valleys, which, like those of the -Seine and Somme, lie entirely outside of the glaciated -area.</p> - -<p>Upon close examination, however, the elements of -doubt more and more disappear. The Glacial period was -one of great precipitation, and it is natural to suppose -that the area of excessive snow-fall extended considerably -beyond the limit of the ice-front. During that period -therefore, the rivers of central France must have been annually -flooded to an extent far beyond anything which is -known at the present time. Since these rivers flowed to -<span class="pagenum"><a name="Page_186" id="Page_186">« 186 »</a></span> -the northward, at a period when, during the long and -severe winters, the annual accumulation of ice near their -mouths was excessive, ice-gorges of immense extent, such -as now form about the mouths of the Siberian rivers, -would regularly occur. We are not surprised, therefore, -to find, even in these streams, abundant indications of the -indirect influence of the great northern ice-sheet.</p> - -<p>The indications referred to consist of high-level gravel -terraces occasionally containing boulders, of from four to -five tons weight, which have been transported for a considerable -distance. The elevation of the terraces above -the present flood-plains of the Seine and Somme reaches -from 100 to 150 feet. We are not to suppose, however, -that even in glacial times the floods of the river Seine -could have filled its present valley to that height. The -highest flood in this river known in historic times rose -only to a height of twenty-nine feet. Mr. Prestwich estimates -that, without taking into consideration the more -rapid discharge, a flood of sixty times this magnitude -would be required to fill the present valley to the level of -the ancient gravels, while at Amiens the shape of the valley -of the Somme is such that five hundred times the -mean average of the stream would be required to reach -the high-level gravels. The conclusion, therefore, is that -the troughs of these streams have been largely formed by -erosion since the deposition of the high-level gravels.</p> - -<p>Connected with these terrace gravels in northern -France is a loamy deposit, corresponding to the loess in -other parts of Europe, and to a similar deposit to which -we have referred in describing the southwestern part of -the glaciated area in North America. In northern France -this fine silt overlies the high-level gravel deposits, and, -as Mr. Prestwich has pretty clearly shown, was deposited -contemporaneously with them during the early inundations -and before the stream had eroded its channel to its -present level.</p> - -<p><span class="pagenum"><a name="Page_187" id="Page_187">« 187 »</a></span></p> - -<p>The distribution of loess in Europe was doubtless connected -with the peculiar glacial conditions of the continent. -Its typical development is in the valley of the -Rhine, where it is described by Professor James Geikie -“as a yellow or pale greyish-brown, fine-grained, and -more or less homogeneous, consistent, non-plastic loam, -consisting of an intimate admixture of clay and carbonate -of lime. It is frequently minutely perforated by long, vertical, -root-like tubes which are lined with carbonate of -lime—a structure which imparts to the loess a strong -tendency to cleave or divide in vertical planes. Thus it -usually presents upright bluffs or cliffs upon the margins -of streams and rivers which intersect it. Very often it -contains concretions or nodules of irregular form.... -Land-shells and the remains of land animals are the most -common fossils of the loess, but occasionally fresh-water -shells and the bones of fresh-water fish occur.”</p> - -<p>“From the margins of the modern alluvial flats which -form the bottoms of the valleys it rises to a height of 200 -or 300 feet above the streams—sweeping up the slopes of -the valleys, and imparting a rich productiveness to many -districts which would otherwise be comparatively unfruitful. -From the Rhienthal itself it extends into all the -tributary valleys—those of the Neckar, the Main, the -Lahn, the Moselle, and the Meuse, being more or less -abundantly charged with it. It spreads, in short, like a -great winding-sheet over the country—lying thickly in -the valleys and dying off upon the higher slopes and -plateaux. Wide and deep accumulations appear likewise -in the Rhône Valley, as also in several other river-valleys -of France, as in those of the Seine, the Saône, and the Garonne, -and the same is the case with many of the valleys -of middle Germany, such as those of the Fulda, the Werra, -the Weser, and the upper reaches of the great basin of -the Elbe. It must not be supposed that the loess is restricted -to valleys and depressions in the surface of the ground.</p> - -<p><span class="pagenum"><a name="Page_188" id="Page_188">« 188 »</a></span></p> - -<p>“It is true that it attains in these its greatest thickness, -but extensive accumulations may often be followed -far into the intermediate hilly districts and over the -neighbouring plateaux. Thus the Odenwald, the Taunus, -the Vogelgebirge, and other upland tracts, are cloaked -with loess up to a considerable height. Crossing into the -drainage system of the Danube, we find that this large -river and many of its tributaries flow through vast tracts -of loess. Lower Bavaria is thickly coated with it, and it -attains a great development in Bohemia, Upper and Lower -Austria, and Moravia—in the latter country rising to an -elevation of 1,300 feet. It is equally abundant in Hungary, -Galicia, Bukowina, and Transylvania. From the -Danubian flat lands and the low grounds of Galicia it -stretches into the valleys of the Carpathians, up to -heights of 800 and 2,000 feet. In some cases it goes -even higher—namely, to 3,000 feet, according to Zeuschner, -and to 4,000 or 5,000 feet, according to Korzistka. -These last great elevations, it will be understood, are -in the upper valleys of the northern Carpathians. In -Roumania loess is likewise plentiful, but it has not been -observed south of the Balkans. East of the Carpathians—that -is to say, in the regions watered by the -Dniester, the Dnieper, and the Don—loess appears also -to be wanting, and to be represented by those great -steppe-deposits which are known as <i>Tchernozen</i>, or black -earth.”<a name="FNanchor_75" id="FNanchor_75"></a><a href="#Footnote_75" class="fnanchor">[BW]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_75" id="Footnote_75"></a><a href="#FNanchor_75"><span class="label">[BW]</span></a> Prehistoric Europe, pp. 144-146.</p></div> - -<p>The shells found in the loess indicate both a colder and -a wetter climate during its deposition than that which now -exists. The relics of land animals are infrequently found -in the deposit, yet they do occur, but mostly in fragmentary -condition—the principal animals represented being -the mammoth, the rhinoceros, the reindeer, and the horse; -which is about the same variety as is found in the gravel -<span class="pagenum"><a name="Page_189" id="Page_189">« 189 »</a></span> -deposits of the Glacial period, both in western Europe and -in America.</p> - -<p>A species of loess—differing, however, somewhat in -color from that on the Rhine—covers the plains of northeastern -France up to an elevation of 700 feet above the -the sea, where, as we have already said, it overlies the high-level -gravels of the Seine and the Somme. Above this -height the superficial soil in France is evidently merely -the decomposed upper surface of the native rock.</p> - -<p>The probable explanation of all these deposits, included -under the term “loess,” is the same as that already given -by Prestwich of the loamy deposits of northern France. -But in case of rivers, which, like the Rhine, encountered -the ice-front in their northward flow, a flooded condition -favouring the accumulation of loess was doubtless promoted -by the continental ice-barrier. In the case of the Danube -and the Rhône, however, where there was a free outlet -away from the glaciated region, the loess in the upper part -of the valleys must have accumulated in connection with -glacial floods quite similar to those which we have described -as spreading over the imperfectly formed water-courses -of the Mississippi basin during the close of the Ice -age. That the typical loess is of glacial origin is pretty -certainly shown, both by its distribution in front of glaciers -and by its evident mechanical origin when studied -under the microscope. It is, in short, the fine sediment -which gives the milky whiteness to glacial rivers.</p> - -<p>In central Russia there is a considerable area in which -the glacial conditions were, in one respect, similar to those -in the northern part of the Mississippi Valley in the United -States. In both regions the continental ice-sheet surmounted -the river partings, and spread over the upper -portion of an extensive plain whose drainage was to the -south. The Dnieper, the Don, and the western branch of -the Volga, like the Ohio and the Mississippi, have their -head-waters in the glaciated region. In some other respects, -<span class="pagenum"><a name="Page_190" id="Page_190">« 190 »</a></span> -also, there is a resemblance between the plains bordering -the glaciated region in central Russia and those which in -America border it in the Mississippi Valley. Mr. James -Geikie is of the opinion that the extensive belt of black -earth adjoining the glaciated area in Russia, and constituting -the most productive agricultural portion of the country, -derives its fertility, as does much of the Mississippi Valley, -from the blanket of glacial silt spread pretty evenly over it. -Thus it would appear that in Europe, as in America, the -ice of the Glacial period was a most beneficent agent, preparing -the face of the earth for the permanent occupation -of man. On both continents the seat of empire is in the -area once occupied by the advance of the great ice-movements -of that desolate epoch.</p> - - -<p class="caption3nb"><i>Asia.</i></p> - -<p>East of the Urals, in northern Asia, there is no evidence -of moving ice upon the land during the Glacial period; -but at Yakutsk, in latitude 62° north, the soil is frozen at -the present time to an unknown depth, and many of the -Siberian rivers, as they approach and empty into the Arctic -Sea, flow between cliffs of perpetual ice or frozen ground. -The changes that came over this region during the Glacial -period are impressively indicated by the animal remains -which have been preserved in these motionless icy cliffs. -In the early part of the period herds of mammoth and -woolly rhinoceros roamed over the plains of Siberia, and -waged an unequal warfare with the slowly converging and -destructive forces. The heads and tusks of these animals -were so abundant in Siberia that they long supplied all -Russia with ivory, besides contributing no small amount -for export to other countries. “In 1872 and 1873 as -many as 2,770 mammoth-tusks, weighing from 140 to 160 -pounds each, were entered at the London clocks.”<a name="FNanchor_76" id="FNanchor_76"></a><a href="#Footnote_76" class="fnanchor">[BX]</a> So -<span class="pagenum"><a name="Page_191" id="Page_191">« 191 »</a></span> -perfectly have the carcasses of these extinct animals been -preserved in the frozen soil of northern Siberia that when, -after the lapse of thousands of years, floods have washed -them out from the frozen cliffs, dogs and wolves and bears -have fed upon their flesh with avidity. In some instances -even “portions of the food of these animals were found in -the cavities of the teeth. Microscopic examination showed -that they fed upon the leaves and shoots of the coniferous -trees which then clothed the plains of Siberia.” A skeleton -and parts of the skin, and some of the softer portions -of the body of a mammoth, discovered in 1799 in the -frozen cliff near the mouth of the Lena, was carried to -St. Petersburg in 1806, from which it was ascertained that -this huge animal was “covered with alight-coloured, curly, -very thick-set hair one to two inches in length, interspersed -with darker-colored hair and bristles from four to -eighteen inches long.”<a name="FNanchor_77" id="FNanchor_77"></a><a href="#Footnote_77" class="fnanchor">[BY]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_76" id="Footnote_76"></a><a href="#FNanchor_76"><span class="label">[BX]</span></a> Prestwich’s Geology, vol. ii, p. 460.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_77" id="Footnote_77"></a><a href="#FNanchor_77"><span class="label">[BY]</span></a> Prestwich’s Geology, vol. ii, p. 460.</p></div> - -<p>In the valleys of Sikkim and eastern Nepaul, in -northern India, glaciers formerly extended 6,000 feet -lower than now, or to about the 5,000-foot level, and in -the western Himalayas to a still lower level. The higher -ranges of mountains in other portions of Asia also show -many signs of former glaciation. This is specially true -of the Caucasus, where the ancient glaciers were of vast -extent. According, also, to Sir Joseph Hooker, the cedars -of Lebanon flourish upon an ancient moraine. Of the -glacial phenomena in other portions of Asia little is known.</p> - - -<p class="caption3nb"><i>Africa.</i></p> - -<p>Northern and even central Africa must likewise come -in for their share of attention. The Atlas Mountains, rising -to a height of 13,000 feet, though supporting none at -the present time, formerly sustained glaciers of considerable -size. Moraines are found in several places as low as -<span class="pagenum"><a name="Page_192" id="Page_192">« 192 »</a></span> -the 4,000-foot level, and one at an altitude of 4,000 feet -is from 800 to 900 feet high, and completely crosses -and dams up the ravine down which the glacier formerly -came.</p> - -<p>Some have supposed that there are indubitable evidences -of former glaciation in the mountain-ranges of -southwestern Africa between latitude 30° and 33°, but -the evidence is not as unequivocal as we could wish, and -we will not pause upon it.</p> - -<p>The mountains of <i>Australia</i>, also, some of which rise -to a height of more than 7,000 feet, are supposed to have -been once covered with glacial ice down to the level of -5,800 feet, but the evidence is at present too scanty to -build upon. But in <i>New Zealand</i> the glaciers now clustering -about the peaks in the middle of the South Island, -culminating in Mount Cook, are but diminutive representatives -of their predecessors. This is indicated by extensive -moraines in the lower part of the valleys and by -the existence of numerous lakes, attributable, like so many -in Europe and North America, to the irregular deposition -of morainic material by the ancient ice-sheet.<a name="FNanchor_78" id="FNanchor_78"></a><a href="#Footnote_78" class="fnanchor">[BZ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_78" id="Footnote_78"></a><a href="#FNanchor_78"><span class="label">[BZ]</span></a> See With Axe and Rope in the New Zealand Alps, by G. E. -Mannering, 1891.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_193" id="Page_193">« 193 »</a></span></p></div> - - - - -<p class="caption2"><a name="CHAPTER_VII" id="CHAPTER_VII">CHAPTER VII.</a></p> - -<p class="caption2">DRAINAGE SYSTEMS AND THE GLACIAL PERIOD.</p> - - -<p>We will begin the consideration of this part of our -subject, also, with the presentation of the salient facts in -North America, since that field is simpler than any field -in the Old World.</p> - -<p>The natural drainage basins of North America east of -the Rocky Mountains are readily described. The Mississippi -River and its branches drain nearly all the region -lying between the Appalachian chain and the Rocky -Mountains and south of the Dominion of Canada and of -the Great Lakes. All the southern tributaries to the Great -Lakes are insignificant, the river partings on the south -being reached in a very short distance. The drainage of -the rather limited basin of the Great Lakes is northeastward -through the St. Lawrence River, leaving nearly all -of the Dominion of Canada east of the Rocky Mountains -to pour its surplus waters northward into Hudson Bay -and the Arctic Ocean. With the exception of the St. -Lawrence River, these are essentially permanent systems -of drainage. To understand the extent to which the ice -of the Glacial period modified these systems, we must first -get before our minds a picture of the country before the -accumulation of ice began.</p> - - -<p class="caption3nb"><i>Preglacial Erosion.</i></p> - -<p>Reference has already been made to the elevated condition -of the northern and central parts of North America -<span class="pagenum"><a name="Page_194" id="Page_194">« 194 »</a></span> -at the beginning of the Glacial period. The direct -proof of this preglacial elevation is largely derived from -the fiords and great lake basins of the continent. The -word “fiord” is descriptive of the deep and narrow inlets -of the sea specially characteristic of the coasts of Norway, -Denmark. Iceland, and British Columbia. Usually also -fiords are connected with valleys extending still farther -inland, and occupied by streams.</p> - -<p>Fiords are probably due in great part to river erosion -when the shores stood at considerably higher level than -now. Slowly, during the course of ages, the streams wore -out for themselves immense gorges, and were assisted, perhaps, -to some extent by the glaciers which naturally -came into existence during the higher continental elevation. -The present condition of fiords, occupied as they -usually are by great depths of sea-water, would be accounted -for by recent subsidence of the land. In short, -fiords seem essentially to be submerged river gorges, partially -silted up near their mouths, or perhaps partially -closed by terminal moraines.</p> - -<p>It is not alone in northwestern Europe and British -Columbia that fiords are found, but they characterize as -well the eastern coast of America north of Maine, while -even farther south, both on the Atlantic and on the Pacific -coast, some extensive examples exist, whose course -has been revealed only to the sounding-line of the Government -survey.</p> - -<p>The most remarkable of the submerged fiords in the -middle Atlantic region of the United States is the continuation -of the trough of Hudson River beyond New -York Bay. As long ago as 1844 the work of the United -States Coast Survey showed that there was a submarine -continuation of this valley, extending through the comparatively -shallow waters eighty miles or more seaward -from Sandy Hook.</p> - -<p><span class="pagenum"><a name="Page_195" id="Page_195">« 195 »</a></span></p> - -<div class="fig_center" style="width: 473px;"> -<a id="fig50" name="fig50"></a> -<img src="images/fig_50.png" width="473" height="291" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 50.</span>—Map showing old channel and mouth of the Hudson (dewberry).</div> -</div> - -<p>The more accurate surveys conducted from 1880 to -1884 have brought to our knowledge the facts about this -submarine valley almost as clearly as those relating to the -inland portion of it above New York city. According to -Mr. A. Lindenkohl,<a name="FNanchor_79" id="FNanchor_79"></a><a href="#Footnote_79" class="fnanchor">[CA]</a> this submarine valley began to be -noticeable in the soundings ten miles southeast of Sandy -Hook. The depth of the water where the channel begins -is nineteen fathoms (114 feet). Ten miles out the channel -<span class="pagenum"><a name="Page_196" id="Page_196">« 196 »</a></span> -has sunk ninety feet below the general depth of the -water on the bank, and continues at this depth for twenty -miles farther. This narrow channel continues with more -or less variation for a distance of seventy-five miles, where -it suddenly enlarges to a width of three miles and to a -depth of 200 fathoms, or 1,200 feet, and extends for a distance -of twenty-five miles, reaching near that point a -depth of 474 fathoms, or 2,844 feet. According to Mr. -Lindenkohl, this ravine maintains for half its length "a -vertical depth of more than 2,000 feet, measuring from -the top of its banks, and the banks have a nearly uniform -slope of about 14°.” The mouth of the ravine opens -out into the deep basin of the central Atlantic.</p> - -<div class="footnote"> - -<p><a name="Footnote_79" id="Footnote_79"></a><a href="#FNanchor_79"><span class="label">[CA]</span></a> Bulletin of the Geological Society of America, vol. i, p. 564; -American Journal of Science, June, 1891.</p></div> - -<p>With little question there is brought to light in these -remarkable investigations a channel eroded by the extension -of the Hudson River, into the bordering shelf of the -Atlantic basin at a time when the elevation of the continent -was much greater than now. This is shown to have -occurred in late Tertiary or post-Tertiary times by the -fact that the strata through which it is worn are the continuation -of the Tertiary deposits of New Jersey. The -subsidence to its present level has probably been gradual, -and, according to Professor Cook, is still continuing at -the rate of two feet a century.</p> - -<p>Similar submarine channels are found extending out -from the present shore-line to the margin of the narrow -shelf bordering the deep water of the central Atlantic -running from the mouth of the St. Lawrence River, -through St. Lawrence Bay, and through Delaware and -Chesapeake Bays.<a name="FNanchor_80" id="FNanchor_80"></a><a href="#Footnote_80" class="fnanchor">[CB]</a> All these submerged fiords on the -Atlantic coast were probably formed during a continental -elevation which commenced late in the Tertiary period, -and reached the amount of from 2,000 to 3,000 feet in -the northern part of the continent.</p> - -<div class="footnote"> - -<p><a name="Footnote_80" id="Footnote_80"></a><a href="#FNanchor_80"><span class="label">[CB]</span></a> See Lindenkohl in American Journal of Science, for June, 1891.</p> - -<p><span class="pagenum"><a name="Page_197" id="Page_197">« 197 »</a></span></p></div> - -<div class="fig_center" style="width: 474px;"> -<a id="fig51" name="fig51"></a> -<img src="images/fig_51.png" width="474" height="321" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 51.</span>—New York harbor in preglacial times looking south, from south end of New York -Island (Newberry).</div> -</div> - -<p>To this period must probably be referred also the -formation of the gorge, or more properly fiord, of the -Saguenay, which joins the St. Lawrence below Quebec. -The great depth of this fiord is certainly surprising, since, -according to Sir William Dawson, its bottom, for fifty -miles above the St. Lawrence, is 840 feet below the sea-level, -while the bordering cliffs are in some places 1,500 -feet above the water. The average width is something -over a mile.</p> - -<p><span class="pagenum"><a name="Page_198" id="Page_198">« 198 »</a></span></p> - -<p>It seems impossible to account for such a deep gorge -extending so far below the sea-level, except upon the supposition -of a long-continued continental elevation, which -should allow the stream to form a cañon to an extent -somewhat comparable with that of the cañons of the -Colorado and other rivers in the far West. Then, upon -the subsidence of the continent to the present level, it -would remain partially or wholly submerged, as we find it -at the present time. During the Glacial period it was so -filled with ice as to prevent silting up. The rivers entering -the Pacific Ocean, both in the United States and in -British Columbia, are also lost in submerged channels extending -out to the deeper waters of the Pacific basin in a -manner closely similar to the Atlantic streams which have -been mentioned.</p> - -<p>During this continental elevation which preceded, -accompanied, and perhaps brought on the Glacial period, -erosion must have proceeded with great intensity along -all the lines of drainage, and throughout the whole region -which is now covered, and to a considerable extent -smoothed over, by glacial deposits, and the whole country -must have presented a very different appearance from -what it does now.</p> - -<p>A pretty definite idea of its preglacial condition can -probably be formed by studying the appearance of the -regions outside of and adjoining that which was covered -by the continental glacier. The contrast between the -glaciated and the unglaciated region is striking in several -respects aside from the presence and absence of transported -rocks and other <i>débris</i>, but in nothing is it greater -than in the extent of river erosion which is apparent upon -the surface. For example, upon the western flanks of the -Alleghanies the regions south of the glacial limit is everywhere -deeply channeled by streams. Indeed, so long have -they evidently been permitted to work in their present -channels that, wherever there have been waterfalls, they -<span class="pagenum"><a name="Page_199" id="Page_199">« 199 »</a></span> -have receded to the very head-waters, and no cataracts -exist in them at the present time. Nor are there in the -unglaciated region any lakes of importance, such as characterize -the glaciated region. If there have been lakes, -the lapse of time has been sufficient for their outlets to -lower their beds sufficiently to drain the basins dry.</p> - -<p>On entering the glaciated area all this is changed. -The ice-movement has everywhere done much to wear -down the hills and fill the valleys, and, where there was -<i>débris</i> enough at command, it has obliterated the narrow -gorges originally occupied by the preglacial streams. -Thus it has completely changed the minor lines of superficial -drainage, and in many instances has produced most -extensive and radical changes in the whole drainage system -of the region. In the glaciated area, channels buried -beneath glaciated <i>débris</i> are of frequent occurrence, while -many of the streams which occupy their preglacial channels -are flowing at a very much higher level than formerly, -the lower part of the channel having been silted up by the -superabundant <i>débris</i> accessible since the glacial movement -began.</p> - - -<p class="caption3nb"><i>Buried Outlets and Channels.</i></p> - -<p>It is easy to see how the great number of shallow lakes -which frequent the glaciated region were formed by the -irregular deposition of glacial <i>débris</i>, but it is somewhat -more difficult to trace out the connection between the -Glacial period and the Great Lakes of North America, -several of which are of such depth that their bottoms are -some hundreds of feet below the sea-level, Lake Erie -furnishing the only exception. This lake is so shallow -that it is easy to see how its basin may have been principally -formed by river erosion, while it is evident that -such must have been the mode of its formation, since it is -surrounded by sedimentary strata lying nearly in a horizontal -position.</p> - -<p><span class="pagenum"><a name="Page_200" id="Page_200">« 200 »</a></span></p> - -<div class="fig_center" style="width: 415px;"> -<a id="fig52" name="fig52"></a> -<img src="images/fig_52.png" width="415" height="119" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 52.</span>—Section across the valley of the Cuyahoga River, twenty miles above -its mouth (Claypole).</div> -</div> - -<p>That Lake Erie is really nothing but a “glacial mill-pond” -is proved also by much direct evidence, especially -that derived from the depth of the buried channels of the -streams flowing into it from the south. Of these, the -Cuyahoga River, which enters the lake at Cleveland, has -been most fully investigated. In searching for oil, some -years ago, borings were made at many places for twenty-five -miles above the mouth of the river. As a result, it -appeared that for the whole distance the rocky bottom of -the gorge was about two hundred feet below the present -bottom of the river, while the river itself is two or three -hundred feet below the general level of the country, occupying -a trough about half a mile in width, with steep, -rocky sides. These facts indicate that at one time the -river must have found opportunity to discharge its contents -at a level two hundred feet below that of the present -lake, while an examination of the material filling up the -bottom of the gorge to its present level shows it to be -glacial <i>débris</i>, thus proving that the silting up was accomplished -during the Glacial period.</p> - -<p>As the water of Lake Erie is for the most part less -than one hundred feet in depth, and is nowhere much -more than two hundred feet deep, it is clear that the preglacial -outlet which drained it down to the level of the -rocky bottom of the Cuyahoga River must have destroyed -the lake altogether. Hence Ave may be certain that, before -the Glacial period, the area now covered by the lake was -<span class="pagenum"><a name="Page_201" id="Page_201">« 201 »</a></span> -simply a broad, shallow valley through which there coursed -a single river of great magnitude, with tributary branches -occupying deep gorges. Professor J. W. Spencer has -shown with great probability that the old line of drainage -from Lake Erie passed through the lower part of the valley -of Grand River, in Canada, and entered Lake Ontario -at its western extremity, and that during the great Ice -age this became so completely obstructed with glacial <i>débris</i> -as to form an impenetrable dam, and to cause the -pent-up water to flow through the Niagara Valley, which -chanced to furnish the lowest opening.</p> - -<p>In speaking of the present area of Lake Erie, however, -as being then occupied by a river valley, we do not mean -to imply that it was not afterwards greatly modified by -glacial erosion; for undoubtedly this was the case, whatever -views we may have as to the relative efficiency of ice -and water in scooping out lake basins.</p> - -<p>In the case of Lake Erie, we need suppose no change -of level to account for the erosion of its basin, but only -that, since the strata in which it is situated were deposited, -time enough had elapsed for a great river to cut a gorge -extending from the western end of Lake Ontario through -to the present bed of Lake Erie, and that here a great enlargement -of the valley was occasioned by the existence -of deep beds of soft shale which could easily be worn away -by a ramifying system of tributary streams. Rivers acting -at present relative levels would be amply sufficient to -produce the results which are here manifest.</p> - -<p>But in the case of Lakes Ontario, Huron, Michigan, -and Superior, whose depths descend considerably below -the sea-level, we must suppose that they were, in the -main, eroded when the continent was so much elevated -that their bottoms were brought above tide-level. The -depth of Lake Ontario implies the existence of an outlet -more than four hundred feet lower than at present, -which, of course, could exist only when the general elevation -<span class="pagenum"><a name="Page_202" id="Page_202">« 202 »</a></span> -was more than four hundred feet greater than -now.</p> - -<p>The existence of an outlet at that depth seems to be -proved also by the fact that at Syracuse, where numerous -wells have been sunk to obtain brine for the manufacture -of salt, deposits of sand, gravel, and rolled stones, four hundred -and fifty feet thick, are penetrated without reaching -rock. Since this lies in the basin of Lake Ontario, it follows -that if the basin itself has been produced by river -erosion, the land must have been of sufficient height to -permit an outlet through a valley, or cañon, of the required -depth, and this outlet must now be buried beneath the -abundant glacial <i>débris</i> that covers the region.</p> - -<p>Professor Newberry, who has studied the vicinity carefully, -is of the opinion that there is ample opportunity -for such a line of drainage to have extended through the -Mohawk Valley to the Hudson River. But, at Little Falls, -a spur of the Adirondack Mountains projects into the -valley, and the Archæan rocks over which the river runs -are so prominent and continuous that some have thought it -impossible for the requisite channel to have ever existed -there. Extensive deposits of glacial <i>débris</i>, however, are -found in the vicinity, especially in places some distance to -the north, and in Professor Newberry’s opinion the existence -of a buried channel around the obstruction upon the -north side is by no means improbable.</p> - -<p>The preglacial drainage of Lake Huron has not been -determined with any great degree of probability. Professor -Spencer formerly supposed that it passed from the -southern end of the lake through London, in the western -part of Ontario, and reached the Erie basin near Port -Stanley, and so augmented the volume of the ancient -river which eroded the buried cañon from Lake Erie to -Lake Ontario. But he now supposes, though the evidence -is by no means demonstrative, that the waters of Lake -Huron passed into Lake Ontario by means of a channel -<span class="pagenum"><a name="Page_203" id="Page_203">« 203 »</a></span> -extending from Georgian Bay to the vicinity of Toronto.</p> - -<p>With a fair degree of probability, the basin of Lake -Superior is supposed by Professor Newberry to have been -joined to that of Lake Michigan by some passage, now -buried, considerably to the west of the Strait of Mackinac, -and thence to have had an outlet southward from the -vicinity of Chicago directly into the Mississippi River. -Of this there is considerable evidence furnished by deeply -buried channels which have been penetrated by borings -in various places in Kankakee, Livingston, and McLean -Counties, Illinois; but the whole area extending from -Lake Michigan to the Mississippi is so deeply covered -with glacial <i>débris</i> that the surface of the country gives -no satisfactory indication of the exact lines of preglacial -drainage.</p> - -<p>Some of the most remarkable instances of ancient -river channels buried by the glacial deposits have been -brought to light in southwestern Ohio, where there has -been great activity in boring for gas and oil. At St. -Paris, Champaign County, for example, in a locality where -the surface of the rock near by was known to be not far -below the general level, a boring was begun and continued -to a depth of more than five hundred feet without reaching -rock, or passing out of glacial <i>débris</i>.</p> - -<p>Many years ago Professor Newberry collected sufficient -facts to show that pretty generally the ancient bed -of the Ohio River was as much as 150 feet below that -over which it now flows. During a continental elevation -the erosion had proceeded to that extent, and then the -channel had been silted up during the Glacial period with -the abundant material carried down by the streams from -the glaciated area. One of the evidences of the preglacial -depth of the channel of the Ohio was brought to -light at Cincinnati, where “gravel and sand have been -found to extend to a depth of over one hundred feet below -<span class="pagenum"><a name="Page_204" id="Page_204">« 204 »</a></span> -low-water mark, and the bottom of the trough has not -been reached.” In the valley of Mill Creek, also, “in the -suburbs of Cincinnati, gravel and sand were penetrated -to the depth of 120 feet below the stream before reaching -rock.” But from the general appearance of the channel, -Professor J. F. James was led to surmise that a rock -bottom extended all the way across the present channel -of the Ohio, between Price Hill and Ludlow, Ky., a short -distance below Cincinnati, which would preclude the -possibility of a preglacial outlet at the depth disclosed in -that direction. Mr. Charles J. Bates (who was inspector -of the masonry for the Cincinnati Southern Railroad while -building the bridge across the Ohio at this point) informs -me that Mr. James’s surmise is certainly correct, and that -his “in all probability” may be displaced by “certainly,” -since the bedded rocks supposed by Professor James to -extend across the river a few feet below its present bottom -were found by the engineers to be in actual existence.</p> - -<p>In looking for an outlet for the waters of the upper -Ohio which should permit them to flow off at the low -level reached in the channel at Cincinnati, Professor -James was led to inspect the valley extending up Mill -Creek to the north towards Hamilton, where it joins the -Great Miami. The importance of Mill Creek Valley is -readily seen in the fact that the canal and the railroads -have been able to avoid heavy grades by following it from -Cincinnati to Hamilton. As a glance at a map will show, -it is also practically but a continuation of the northerly -course pursued by the Ohio for twenty miles before reaching -Cincinnati. This, therefore, was a natural place in -which to look beneath the extensive glacial <i>débris</i> for the -buried channel of the ancient Ohio, and here in all probability -it has been found. The borings which have been -made in Milk Creek Valley north of Cincinnati, show that -the bedded rock lies certainly thirty-four feet below the -low-water mark of the Ohio just below Cincinnati, while -<span class="pagenum"><a name="Page_205" id="Page_205">« 205 »</a></span> -at Hamilton, twenty-five miles north of Cincinnati, where -the valley of the Great Miami is reached, the bedded rock -of the valley lies as much as ninety feet below present -low-water mark in the Ohio.</p> - -<p>Other indications of the greater depth of the preglacial -gorge of the Ohio are abundant. “At the junction -of the Anderson with the Ohio, in Indiana, a well was -sunk ninety-four feet below the level of the Ohio before -rock was found.” At Louisville, Ky., the occurrence of -falls in the Ohio seemed at first to discredit the theory in -question, but Professor Newberry was able to show that -the falls at Louisville are produced by the water’s being -now compelled to flow over a rocky point projecting from -the north side into the old valley, while to the south there -is ample opportunity for an old channel to have passed -around this point underneath the city on the south side. -The lowlands upon which the city stands are made lands, -where glacial <i>débris</i> has filled up the old channel of the -Ohio.</p> - -<p>Above Cincinnati the tributaries of the Ohio exhibit -the same phenomena. At New Philadelphia, Tuscarawas -County, the borings for salt-wells show that the Tuscarawas -is running 175 feet above its ancient bed. The -Beaver, at the junction of the Mahoning and Shenango, -is flowing 150 feet above the bottom of its old trough, as -is demonstrated by a large number of oil-wells bored in -the vicinity. Oil Creek is shown by the same proofs to -run from 75 to 100 feet above its old channel, and that -channel had sometimes vertical and even overhanging -walls.<a name="FNanchor_81" id="FNanchor_81"></a><a href="#Footnote_81" class="fnanchor">[CC]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_81" id="Footnote_81"></a><a href="#FNanchor_81"><span class="label">[CC]</span></a> Geological Survey of Ohio, vol. ii, pp. 13, 14.</p></div> - -<p>The course of preglacial drainage in the upper basin -of the Alleghany River is worthy of more particular mention. -Mr. Carll, of the Pennsylvania Geological Survey, -has adduced plausible reasons for believing that previous -<span class="pagenum"><a name="Page_206" id="Page_206">« 206 »</a></span> -to the Glacial period the drainage of the valley of the -upper Alleghany north of the neighbourhood of Tidioute, -in Warren County, instead of passing southward as now, -was collected into one great stream flowing northward -through the region of Cassadaga Lake to enter the Lake -Erie basin at Dunkirk, N. Y. The evidence is that between -Tidioute and Warren the present Alleghany is shallow, -and flows over a rocky basin; but from Warren northward -along the valley of the Conewango, the bottom of -the old trough lies at a considerably lower level, and slopes -to the north. Borings show that in thirteen miles the -slope of the preglacial floor of Conewango Creek to the -north is 136 feet. The actual height above tide of the -old valley floor at Fentonville, where the Conewango -crosses the New York line, is only 964 feet; while that of -the ancient rocky floor of the Alleghany at Great Bend, -a few miles south of Warren, was 1,170 feet. Again, -going nearer the head-waters of the Alleghany, in the -neighbourhood of Salamanca, it is found that the ancient -floor of the Alleghany is, at Carrollton, 70 feet lower than -the ancient bed of the present stream at Great Bend, -about sixty miles to the south; while at Cole’s Spring, in -the neighbourhood of Steamburg, Cattaraugus County, -N. Y., there has been an accumulation of 315 feet of drift -in a preglacial valley whose rocky floor is 155 feet below -the ancient rocky floor at Great Bend. Unless there has -been a great change in levels, there must, therefore, have -been some other outlet than the present for the waters -collecting in the drainage basin to the north of Great -Bend.<a name="FNanchor_82" id="FNanchor_82"></a><a href="#Footnote_82" class="fnanchor">[CD]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_82" id="Footnote_82"></a><a href="#FNanchor_82"><span class="label">[CD]</span></a> For a criticism of Mr. Carll’s views, see an article on Pleistocene -Fluvial Planes of Western Pennsylvania, by Mr. Frank Leverett, -in American Journal of Science, vol. xlii, pp. 200-212.</p></div> - -<p>While there are numerous superficial indications of -buried channels running towards Lake Erie in this region, -<span class="pagenum"><a name="Page_207" id="Page_207">« 207 »</a></span> -direct exploration has not been made to confirm these -theoretical conclusions. In the opinion of Mr. Carll, -Chautauqua Lake did not flow directly to the north, but, -passing through a channel nearly coincident with that -now occupied by it, joined the northerly flowing stream -a few miles northeast from Jamestown.<a name="FNanchor_83" id="FNanchor_83"></a><a href="#Footnote_83" class="fnanchor">[CE]</a> It is probable, -however, that Chautauqua did not then exist as a lake, -since the length of preglacial time would have permitted -its outlet to wear a continuous channel of great depth corresponding -to that known to have existed in the Conewango -and upper Alleghany.</p> - -<div class="footnote"> - -<p><a name="Footnote_83" id="Footnote_83"></a><a href="#FNanchor_83"><span class="label">[CE]</span></a> Second Geological Survey of Pennsylvania, vol. iii.</p></div> - -<p>The foregoing are but a few of the innumerable instances -where the local lines of drainage have been disturbed, -and even permanently changed, by the glacial deposits. -Almost every lake in the glaciated region is a -witness to this disturbance of the established lines of -drainage by glacial action, while in numerous places where -lakes do not now exist they have been so recently drained -that their shore-lines are readily discernible.</p> - -<p>An interesting instance of the recent disappearance of -one of these glacial lakes is that of Runaway Pond, in -northern Vermont. In the early part of the century the -Lamoille River had its source in a small lake in Craftsbury, -Orleans County. The sources of the Missisquoi -River were upon the same level just to the north, and the -owner of a mill privilege upon this latter stream, desiring -to increase his power by obtaining access to the water of -the lake, began digging a ditch to turn it into the Missisquoi, -but no sooner had he loosened the thin rim of -compact material which formed the bottom and the sides -of the inclosure, than the water began to rush out through -the underlying and adjacent quicksands. This almost instantly -enlarged the channel, and drained the whole body -of water oft 3 in an incredibly short time. As a consequence, -<span class="pagenum"><a name="Page_208" id="Page_208">« 208 »</a></span> -the torrent went rushing down through the narrow valley, -sweeping everything before it; and nothing but the -unsettled condition of the country prevented a disaster -like that which occurred in 1889 at Johnstown, Pa. -Doubtless there are many other lakes held in position -by equally slender natural embankments. Artificial reservoirs -are by no means the only sources of such danger.</p> - -<p>The buried channel of the old Mississippi River in -the vicinity of Minneapolis is another instructive example -of the instability of many of the present lines of drainage. -The gorge of the Mississippi River extending from Fort -Snelling to the Falls of St. Anthony at Minneapolis is of -post-glacial origin. One evidence of this is its narrowness -when contrasted with the breadth of the valley below -Fort Snelling. Below this point the main trough of the -Mississippi has a width of from two to eight miles, and -the faces of the bluffs on either side show the marks of -extreme age. The tributary streams also have had time -to wear gorges proportionate to that of the main stream, -and the agencies which oxidise and discolor the rocks -have had time to produce their full effects. But from -Fort Snelling up to Minneapolis, a distance of about -seven miles, the gorge is scarcely a quarter of a mile in -width, and the faces of the high, steep bluffs on either side -are remarkably fresh looking by comparison with those -below; while the tributary gorges, of which that of the -Minnehaha River is a fair specimen, are very limited in -their extent.</p> - -<p>Upon looking for the cause of this condition of things -we observe that the broad trough of the Mississippi River, -which had characterised it all the way below Fort Snelling, -continues westward, without interruption, up the valley -of the present Minnesota River, and, what seems at -first most singular, it does not cease at the sources of the -Minnesota, but, through Lake Traverse and Big Stone -<span class="pagenum"><a name="Page_209" id="Page_209">« 209 »</a></span> -Lake, is continuous with the trough of the Red River of -the North.</p> - -<div class="fig_center" style="width: 358px;"> -<a id="fig53" name="fig53"></a> -<img src="images/fig_53.png" width="358" height="555" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 53.</span>—Map of Mississippi River from Fort Snelling to Minneapolis and the -vicinity, showing the extent of the recession of the Falls of St. Anthony since -the great Ice age. Notice the greater breadth of the valley of the Minnesota -River as described in the text (Winchell).</div> -</div> - -<p>Deferring, however, for a little the explanation of this, -<span class="pagenum"><a name="Page_210" id="Page_210">« 210 »</a></span> -we will go back to finish the history of the preglacial -channel around the Falls of St. Anthony. As early as -the year 1876 Professor N. H. Winchell had collected sufficient -evidence from wells, one of which had been sunk -to a depth of one hundred and seventy-five feet, to show -that the preglacial course of the stream corresponding to -the present Mississippi River ran to the west of Minneapolis -and of the Falls of Minnehaha, and joined the main -valley some distance above Fort Snelling, as shown in the -accompanying map.</p> - -<p>This condition of things was at one time very painfully -brought to the notice of the citizens of Minneapolis. -A large part of the wealth of the city at that time consisted -of the commercial value of the water-power furnished -by the Falls of St. Anthony. To facilitate the -discharge of the waste water from their wheels, some mill-owners -dug a tunnel through the soft sandstone underlying -the limestone strata over which the river falls; but it very -soon became apparent that the erosion was proceeding -with such rapidity that in a few years the recession of -the falls would be carried back to the preglacial channel, -when the river would soon scour out the channel and destroy -their present source of wealth. The citizens rallied -to protect their property, and spent altogether as much -as half a million dollars in filling up the holes that had -been thoughtlessly made; but so serious was the task that -they were finally compelled to appeal for aid to the United -States Government. Permanent protection was provided -by running a tunnel, some ways back from the falls, completely -across the channel, through the soft sandstone underlying -the limestone, and filling this up with cement -hard enough and compact enough to prevent the further -percolation of the water from above.</p> - -<p><span class="pagenum"><a name="Page_211" id="Page_211">« 211 »</a></span></p> - - -<p class="caption3nb"><i>Ice-Dams.</i></p> - -<p>The foregoing changes in lines of drainage due to the -Glacial period were produced by deposits of earthy material -in preglacial channels. Another class of temporary -but equally interesting changes were produced by the ice -itself acting directly as a barrier.</p> - -<p>Many such lakes on a small scale are still in existence -in various parts of the world. The Merjelen See in Switzerland -is a well-known instance. This is a small body of -water held back by the great Aletsch Glacier, in a little -valley leading to that of the Fiesch Glacier, behind the -Eggischorn. At irregular intervals the ice-barrier gives -way, and allows the water to rush out in a torrent and -flood the valley below. Afterwards the ice closes up again, -and the water reaccumulates in preparation for another -flood.</p> - -<p>Other instances in the Alps are found in the Mattmark -See, which fills the portion of the Saas Valley between -Monte Rosa and the Rhône. This body of water is held -in place by the Allalin Glacier, which here crosses the -main valley. The Lac du Combal is held back by the -Glacier de Miage at the southern base of Mont Blanc. -“A more famous case is that of the Gietroz Glacier in the -valley of Bagnes, south of Martigny. In 1818 this lake -had grown to be a mile long, and was 700 feet wide and -200 feet deep. An attempt was made to drain it by cutting -through the ice, and about half the water was slowly -drawn off in this way; but then the barrier broke, and -the rest of the lake was emptied in half an hour, causing -a dreadful flood in the valley below. In the Tyrol, the -Vernagt Glacier has many times caused disastrous floods -by its inability to hold up the lake formed behind it. In -the northwestern Himalaya, the upper branches of the -Indus are sometimes held back in this way. A noted -flood occurred in 1835; it advanced twenty-five miles in -<span class="pagenum"><a name="Page_212" id="Page_212">« 212 »</a></span> -an hour, and was felt three hundred miles down-stream, -destroying all the villages on the lower plain, and strewing -the fields with stones, sand, and mud.”<a name="FNanchor_84" id="FNanchor_84"></a><a href="#Footnote_84" class="fnanchor">[CF]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_84" id="Footnote_84"></a><a href="#FNanchor_84"><span class="label">[CF]</span></a> Professor William M. Davis in. Proceedings of the Boston -Society of Natural History, vol. xxi, pp. 350, 351.</p></div> - -<p>In Greenland such temporary obstructions are frequent, -forming lakes of considerable size. Instances occur, -in connection with the Jakobshavn and the Frederickshaab -Glaciers, and in the North Isortok and Alangordlia -Fiords.</p> - -<p>Frequently, also, bodies of water of considerable size -are found in depressions of the ice itself, even at high -levels. I have myself seen them covering more than an -acre, and as much as a thousand feet above the sea-level, -upon the surface of the Muir Glacier, Alaska. They are -reported by Mr. I. C. Russell<a name="FNanchor_85" id="FNanchor_85"></a><a href="#Footnote_85" class="fnanchor">[CG]</a> of larger size and at still -higher elevations upon the glaciers radiating from Mount -St. Elias; while the explorers of Greenland mention them -of impressive size upon the surface of its continental ice-sheet.</p> - -<div class="footnote"> - -<p><a name="Footnote_85" id="Footnote_85"></a><a href="#FNanchor_85"><span class="label">[CG]</span></a> See National Geographic Magazine, vol. iii, pp. 116-120.</p></div> - -<p>With these facts in mind we can the more readily -enter into the description which will now be given of -some temporary lakes of vast size which were formed by -direct ice-obstructions during portions of the period.</p> - -<p>One of the most interesting of these is illustrated upon -the accompanying map, which will need little description.</p> - -<p><span class="pagenum"><a name="Page_213" id="Page_213">« 213 »</a></span></p> - -<div class="fig_center" style="width: 714px;"> -<a id="fig54" name="fig54"></a> -<img src="images/fig_54.png" width="714" height="428" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 54.</span>—Map showing the effect of the glacial dam at Cincinnati (Claypole). (From Transactions of the Edinburgh Geological Society.)</div> -</div> - -<p><span class="pagenum"><a name="Page_214" id="Page_214">« 214 »</a></span></p> - -<p>While tracing the boundary-line of the glaciated area -in the Mississippi Valley during the summer of 1882, I -discovered the existence of unmistakable glacial deposits -in Boone County, Kentucky, across the Ohio River, from -Cincinnati.<a name="FNanchor_86" id="FNanchor_86"></a><a href="#Footnote_86" class="fnanchor">[CH]</a>; These deposits were upon the height of land -550 feet above the Ohio River, or nearly 1,000 feet above -the sea, which is about the height of the water-shed between -the Licking and Kentucky Rivers. As the Ohio -River occupies a trough of erosion some hundreds of feet -in depth, and extending all the way from this point to the -mountains of western Pennsylvania, it would follow that -the ice which conveyed boulders across the Ohio River at -Cincinnati, and deposited them upon the highlands between -the Licking and Kentucky Rivers, would so obstruct -the channel of the Ohio as to pond the water back, -and hold it up to the level of the lowest pass into the -Ohio River farther down. Direct evidences of obstruction -by glacial ice appear also for a distance of fifty or -sixty miles, extending both ways, from Cincinnati.</p> - -<div class="footnote"> - -<p><a name="Footnote_86" id="Footnote_86"></a><a href="#FNanchor_86"><span class="label">[CH]</span></a> The existence of portions of this evidence had previously been -pointed out by Mr. Robert B. Warder and Dr. George Sutton (see -Geological Reports of Indiana, 1872 and 1878).</p></div> - -<p>The consequences connected with this state of things -are of the most interesting character.</p> - -<p>The bottom of the Ohio River at Cincinnati is 432 -feet above the sea-level. A dam of 550 feet would raise -the water in its rear to a height of 982 feet above tide. -This would produce a long, narrow lake, of the width of -the eroded trough of the Ohio, submerging the site of -Pittsburg to a depth of 281 feet, and creating slack water -up the Monongahela nearly to Grafton, West Virginia, -and up the Alleghany as far as Oil City. All the tributaries -of the Ohio would likewise be filled to this level. -The length of this slack-water lake in the main valley, to -its termination up either the Alleghany or the Monongahela, -was not far from one thousand miles. The conditions -were also peculiar in this, that all the northern -tributaries rose within the southern margin of the ice-front, -which lay at varying distances to the north. Down -these there must have poured during the summer months -immense torrents of water to strand boulder-laden icebergs -on the summits of such high hills as were lower -than the level of the dam.</p> - -<p>Naturally enough, this hypothesis of a glacial dam at -Cincinnati aroused considerable discussion, and led to -<span class="pagenum"><a name="Page_215" id="Page_215">« 215 »</a></span> -some differences of opinion. Professors I. C. White and -J. P. Lesley, whose field work has made them perfectly -familiar with the upper Ohio and its tributaries, at once -supported the theory, with a great number of facts concerning -certain high-level terraces along the Alleghany -and Monongahela Rivers; while additional facts of the -same character have been brought to light by myself and -others. In general, it may be said that in numerous -places terraces occur at a height so closely corresponding -to that of the supposed dam at Cincinnati, that they certainly -strongly suggest direct dependence upon it. The -upward limit of these terraces in the Monongahela River -is 1,065 feet, and they are found in various places in situations -which indicate that they were formed in still water -of such long standing as would require an obstruction below -of considerable permanence.</p> - -<p>One of the most decisive cases adduced by Professor -White occurs near Morgantown, in West Virginia, of which -he gives the following description:</p> - -<p>“Owing to the considerable elevation—275 feet—of -the fifth terrace above the present river-bed in the vicinity -of Morgantown, its deposits are frequently found far inland -from the Monongahela, on tributary streams. A -very extensive deposit of this kind occurs on a tributary -one mile and a half northeast of Morgantown; and the region, -which includes three or four square miles, is significantly -known as the ‘Flats.’ The elevation of the ‘Flats’ -is 275 feet above the river, or 1,065 feet above tide. The -deposits on this area consist almost entirely of clays and -fine, sandy material, there being very few boulders intermingled. -The depth of the deposit is unknown, since a -well sunk on the land of Mr. Baker passed through alternate -beds of clay, fine sand, and muddy trash, to a depth of sixty-five -feet without reaching bed-rock. In some portions -of the clays which make up this deposit, the leaves of our -common forest-trees are found most beautifully preserved.</p> - -<p><span class="pagenum"><a name="Page_216" id="Page_216">« 216 »</a></span></p> - -<p>“At Clarksburg, where the river unites with Elk Creek, -there is a wide stretch of terrace deposits, and the upper -limit is there about 1,050 feet above tide, or only 130 feet -above low-water (920 feet); while at Weston, forty miles -above (by the river), these deposits cease at seventy feet -above low water, which is there 985 feet above tide. It -will thus be observed that the upper limit of the deposits -retains a practical horizontality from Morgantown to Weston, -a distance of one hundred miles, since the upper limit -has the same elevation above tide (1,045 to 1,065 feet) at -every locality.</p> - -<p>“These deposits consist of rounded boulders of sandstone, -with a large amount of clay, quicksand, and other -detrital matter. The country rock in this region consists -of the soft shales and limestones of the upper coal-measures, -and hence there are many ‘low gaps’ from the head -of one little stream to that of another, especially along the -immediate region of the river; and in every case the summits -of these divides, where they do not exceed an elevation -of 1,050 feet above tide, are covered with transported -or terrace material; but where the summits go more than -a few feet above that level we find no transported material -upon them, but simply the decomposed country -rock.”</p> - -<p>Other noteworthy terraces naturally attributable to the -Cincinnati ice-dam are to be found in the valley of the Kanawha, -in West Virginia, and one of special significance -on the pass between the valleys of the Ohio and Monongahela, -west of Clarksburg, West Virginia. According to -Professor White, there is at this latter place “a broad, -level summit, having an elevation of 1,100 feet, in a gap -about 300 feet below the enclosing hills. This gap, or -valley, is covered by a deposit of fine clay. The cut -through it is about thirty feet, and one can observe the -succession of clays of all kinds and of different colours, -from yellow on the surface down to the finest white potter’s -<span class="pagenum"><a name="Page_217" id="Page_217">« 217 »</a></span> -clay at the level of the railway, where the cut reaches -bed-rock, thus proving that the region has been submerged.”<a name="FNanchor_87" id="FNanchor_87"></a><a href="#Footnote_87" class="fnanchor">[CI]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_87" id="Footnote_87"></a><a href="#FNanchor_87"><span class="label">[CI]</span></a> Bulletin of the Geological Society of America, vol. i, p. 478.</p></div> - -<p>Another crucial case I have myself described at Bellevue, -in the angle of the Ohio and Alleghany Rivers, about -five miles below Pittsburg, where the gravel terrace is -nearly 300 feet above the river, making it about 1,000 -feet above the sea. A significant circumstance connected -with this terrace is that not only does its height correspond -with that of the supposed obstruction at Cincinnati, -but it contains many pebbles of Canadian origin, -which could not have got into the valley of the Alleghany -before the Glacial period, and could only have reached -their present position by being brought down the Alleghany -River upon floating ice, or by the ordinary movement -of gravel along the margin of a river. Thus this -terrace, while corresponding closely with the elevation of -those on the Monongahela River, is directly connected -with the Glacial period, and furnishes a twofold argument -for our theory.</p> - -<p>A still stronger case occurs at Beech Flats, at the head -of Ohio Brush Creek, in the northwest corner of Pike -County, Ohio, where, at an elevation of about 950 feet -above the sea, there is an extensive flat-topped terrace just -in front of the terminal moraine. This terrace consists of -fine loam, such as is derived from the glacial streams, but -which must have been deposited in still water. The occurrence -of still water at that elevation just in front of the -continental ice-sheet is best accounted for by the supposed -dam at Cincinnati. Indeed, it is extremely difficult to account -for it in any other way.</p> - -<p>There are, however, two other methods of attempting -to account for the class of facts above cited in support of -the ice-dam theory, of which the most plausible is, that in -<span class="pagenum"><a name="Page_218" id="Page_218">« 218 »</a></span> -connection with the Glacial period there was a subsidence -of the whole region to an extent of 1,100 feet.</p> - -<p>The principal objection heretofore alleged against this -supposition is that there are not corresponding signs of -still-water action at the same level on the other side of the -Alleghany Mountains. This will certainly be fatal to the -subsidence theory, if it proves true. But it is possible that -sufficient search for such marks has not yet been made on -the eastern side of the mountains.</p> - -<p>The other theory to account for the facts is, that the -terraces adduced in proof of the Cincinnati ice-dam were -left by the streams in the slow process of lowering their -beds from their former high levels. This is the view -advocated by President T. C. Chamberlin. But the freshness -of the leaves and fragments of wood, such as were -noted by Professor White at Morgantown, and the great -extent of fine silt occasionally resting upon the summits -of the water-sheds, as described above, near Clarksburg, -bear strongly against it. Furthermore, to account for the -terrace described at Bellevue, which contains Canadian -pebbles, President Chamberlin is compelled to connect -the deposit with his hypothetical first Glacial epoch, and -to assume that all the erosion of the Alleghany and -Monongahela Rivers, and indeed of the whole trough of -the Ohio River, took place in the interval between the -“first” and the “second” Glacial periods (for he would -connect the glacial deposits upon the south side of the -river at Cincinnati with the first Glacial epoch)—all of -which, it would seem, is an unnecessary demand upon the -forces of Nature, when the facts are so easily accounted for -by the simple supposition of the dam at Cincinnati.<a name="FNanchor_88" id="FNanchor_88"></a><a href="#Footnote_88" class="fnanchor">[CJ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_88" id="Footnote_88"></a><a href="#FNanchor_88"><span class="label">[CJ]</span></a> See matter discussed more at length in the lee Age, pp. 326-350, -480-500; Bulletin of the United States Geological Survey, No. -58, pp. 76-100; Popular Science Monthly, vol. xlv, pp. 184-199. <i>Per -contra</i>, Mr. Frank Leverett, in American Geologist, vol. x, pp. 18-24.</p> - -<p><span class="pagenum"><a name="Page_219" id="Page_219">« 219 »</a></span></p></div> - -<div class="fig_center" style="width: 642px;"> -<a id="fig55" name="fig55"></a> -<img src="images/fig_55.png" width="642" height="374" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 55.</span>—Map showing the condition of things when the ice-front had withdrawn about on hundred and twenty miles, and while it -still filled the valley of the Mohawk. The outlet was then through the Wabash. Niagara was not yet born (Claypole). (Transactions -of the Edinburgh Geological Society.)</div> -</div> - -<p><span class="pagenum"><a name="Page_220" id="Page_220">« 220 »</a></span></p> - -<p>We have already described<a name="FNanchor_89" id="FNanchor_89"></a><a href="#Footnote_89" class="fnanchor">[CK]</a> the various temporary lakes -and lines of drainage caused by the direct obstruction of -the northward outlets to the basin of the Great Lakes. -In connection with the map, it will be unnecessary to do -anything more here than add a list of such temporary -southern outlets from the Erie-Ontario basin.<a name="FNanchor_90" id="FNanchor_90"></a><a href="#Footnote_90" class="fnanchor">[CL]</a> The first -is at Fort Wayne, Indiana, through a valley connecting -the Maumee River basin with that of the Wabash. The -channel here is well defined, and the high-level gravel -terraces down the Wabash River are a marked characteristic -of the valley. The elevation of this col above the sea -is 740 feet. Similar temporary lines of drainage existed -from the St. Mary’s River to the Great Miami, at an elevation -of 942 feet; from the Sandusky River to the Scioto, -through the Tymochtee Gap, at an elevation of 912 feet; -from Black River to the Killbuck (a tributary of the -Muskingum) through the Harrisville Gap, at 911 feet; -from the Cuyahoga into the Tuscarawas Valley, through -the Akron Gap, at 971 feet; from Grand River into the -Mahoning, through the Orwell Gap, 938 feet; from Cattaraugus -Creek, N. Y., into the Alleghany Valley through -the Dayton Gap, about 1,300 feet; between Conneaut -Creek and Shenango River, at Summit Station, 1,141 feet; -from the Genesee River, N. Y., into the head-waters of the -Canisteo, a branch of the Susquehanna, at Portageville, -1,314 feet; from Seneca Lake to Chemung River, at -Horseheads, 879 feet; from Cayuga Lake to the valley of -Cayuga Creek, at Spencer, N. Y., 1,000 feet; from Utica, -N. Y., into the Chenango Valley at Hamilton, about 900 -feet.</p> - -<div class="footnote"> - -<p><a name="Footnote_89" id="Footnote_89"></a><a href="#FNanchor_89"><span class="label">[CK]</span></a> See pp. <a href="#Page_92">92</a> <i>seq.</i>, <a href="#Page_199">199</a> <i>seq.</i></p></div> - -<div class="footnote"> - -<p><a name="Footnote_90" id="Footnote_90"></a><a href="#FNanchor_90"><span class="label">[CL]</span></a> See also accompanying map.</p> - -<p><span class="pagenum"><a name="Page_221" id="Page_221">« 221 »</a></span></p></div> - -<div class="fig_center" style="width: 434px;"> -<a id="fig56" name="fig56"></a> -<img src="images/fig_56.png" width="434" height="642" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 56.</span>—Map illustrating a stage in the recession of the ice in Ohio. For a section of -the deposit in the bed of this lakelet, see <a href="#Page_200">page 200</a>. The gravel deposits formed at -this stage along the outlet into the Tuscarawas River are very clearly marked (Claypole). -(Transactions of the Edinburgh Geological Society.)</div> -</div> - -<p><span class="pagenum"><a name="Page_222" id="Page_222">« 222 »</a></span></p> - -<p>Perhaps it would have been best to give this list -in the reverse order, which would be more nearly chronological, -since it is clear that the highest outlets are the -oldest. We should then have to mention, after the Fort -Wayne outlet, two others at lower levels which are pretty -certainly marked by distinct beach ridges upon the south -side of Lake Erie. The first was opened when the ice had -melted back from the south peninsula of Michigan to the -water-shed across from the Shiawassee and Grand Rivers, -uncovering a pass which is now 729 feet above the sea. -This continued to be the outlet of Lake Erie-Ontario until -the ice had further retreated beyond the Strait of Mackinac, -when the water would fall to the level of the old outlet -from Lake Michigan into the Illinois River, which is a -little less than 600 feet, where it would remain until the -final opening of the Mohawk River in New York attracted -the water in that direction, and lowered the level to that -of the pass from Lake Ontario to the Mohawk at Rome.<a name="FNanchor_91" id="FNanchor_91"></a><a href="#Footnote_91" class="fnanchor">[CM]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_91" id="Footnote_91"></a><a href="#FNanchor_91"><span class="label">[CM]</span></a> Mr. Warren Upham, in the Bulletin of the Geological Society -of America, vol. ii, p. 259.</p></div> - -<p>A study of these lines of temporary drainage during -the Glacial period sheds much light upon the long lines -of gravel ridges running parallel with the shores of Lake -Erie and Lake Ontario. South of Lake Erie a series of -four ridges of different elevations can be traced. In Lorain -County, Ohio, the highest of these is 220 feet above -the lake; the next 160 feet; the next 118 feet; and the -lower one 100 feet, which would make them respectively -795, 755, 715, and 700 feet above tide.</p> - -<p>These gravel ridges are evidently old beach lines, and -indicate the different levels up to which the water was -held by ice-obstructions across the various outlets of the -drainage valley. The material in the ridges is water-worn -and well assorted, and in coarseness ranges from fine sand -up to pebbles several inches in diameter. The predominant -material in them is of local origin. Where the rocks -over which they run are sandstone, the material is chiefly -sand, and where the outcropping rock is shale, the ridges -consist chiefly of the harder nodules of that formation -<span class="pagenum"><a name="Page_223" id="Page_223">« 223 »</a></span> -which have successfully resisted the attrition of the waves. -Ordinarily these ridges are steepest upon the side facing -the lake. According to Mr. Upham, who has driven over -them with me, the Lake Erie ridges correspond, both in -general appearance and in all other important respects, -to those which he has so carefully surveyed around the -shores of the ancient Lake Agassiz in Minnesota and -Manitoba, an account of which will be given a little farther -on in this chapter.</p> - -<div class="fig_center" style="width: 410px;"> -<a id="fig57" name="fig57"></a> -<img src="images/fig_57.png" width="410" height="454" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 57.</span>—Section of the lake ridges near Sandusky, Ohio.</div> -</div> - -<p><span class="pagenum"><a name="Page_224" id="Page_224">« 224 »</a></span></p> - -<p>We are not permitted, however, to assume that there -have been no changes of level since the deposition of these -beaches surrounding the ancient glacial Lake Erie-Ontario. -On the contrary, there appears to have been a considerable -elevation towards the east and northeast in post-glacial -times. The highest ridge south of Lake Erie, which at -Fort Wayne is about 780 feet high, is now about 795 feet -in Lorain County. The second of the ridges above-mentioned, -which is about 740 feet above tide at Cleveland, -Ohio, rises to 870 feet where the last traces of it have been -discovered at Hamburg, N. Y. The third ridge, which is -673 feet at Cleveland, has risen to the height of 860 feet -at Crittenden, about one hundred miles to the east of -Buffalo, N. Y.</p> - -<p>A similar eastern increase of elevation is discoverable -in the main ridge surrounding Lake Ontario. What Professor -Spencer calls the Iroquois beach, which is 363 feet -above tide at Hamilton, Ontario, has risen to a height of -484 feet near Syracuse, N. Y.; while farther to the northeast, -in the vicinity of Watertown, it is upwards of 800 -feet above tide.</p> - -<p>There is also a similar northward increase of elevation -in the beaches surrounding the higher lands of Ontario -eastward of Lake Huron and Georgian Bay.</p> - -<p>All this indicates that at the close of the Glacial period -there was a subsidence of several hundred feet in the area -of greatest ice-accumulation lying to the east and north of -the Great Lake region. The formation of these ridges -occurred during that period of subsidence. The re-elevation -which followed the disappearance of the ice of course -carried with it these ridges, and brought them to their -present position.<a name="FNanchor_92" id="FNanchor_92"></a><a href="#Footnote_92" class="fnanchor">[CN]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_92" id="Footnote_92"></a><a href="#FNanchor_92"><span class="label">[CN]</span></a> See Spencer, in Bulletin of the Geological Society of America, -vol. ii, pp. 465-476.</p></div> - -<p>In returning to consider more particularly the remarkable -<span class="pagenum"><a name="Page_225" id="Page_225">« 225 »</a></span> -gorge joining the Minnesota with the Red River of -the North, we are brought to the largest of the glacial -lakes of this class, and to the typical place in America in -which to study the temporary changes of drainage produced -by the ice itself daring the periods both of its advance -and of its retreat.</p> - -<div class="fig_center" style="width: 419px;"> -<a id="fig58" name="fig58"></a> -<a href="images/fig_58_lrg.png"><img src="images/fig_58.png" width="419" height="468" alt="" /></a> -<div class="fig_caption"><span class="smcap">Fig. 58.</span>—Map showing the stages of recession of the ice in Minnesota as<br /> -described in the text (Upham).<br /> -Click on image to view larger sized.</div> -</div> - -<p>By turning to our general map of the glaciated region -<span class="pagenum"><a name="Page_226" id="Page_226">« 226 »</a></span> -of the United States,<a name="FNanchor_93" id="FNanchor_93"></a><a href="#Footnote_93" class="fnanchor">[CO]</a> one can readily see the relation of -the valley between Lake Traverse and Big Stone Lake to -an area marked as the bed of what is called Lake Agassiz. -During the Glacial period Brown’s Valley, the depression -joining these two lakes, was the outlet of an immense body -of water to the north, whose natural drainage was towards -Hudson Bay or the Arctic Ocean, but which was cut off, -by the advancing ice, from access to the ocean-level in -that direction, and was compelled to seek an exit to the -south.</p> - -<div class="footnote"> - -<p><a name="Footnote_93" id="Footnote_93"></a><a href="#FNanchor_93"><span class="label">[CO]</span></a> See <a href="#Page_66">page 66</a>.</p></div> - -<p>Thus for a long period the present Minnesota River -Valley was occupied by a stream of enormous dimensions, -and this accounts for the great size of the trough—the -present Minnesota being but an insignificant stream winding -about in this deserted channel of the old “Father of -Waters,” and having as much room as a child of tender -age would have in his parent’s cast-off garments. This -glacial stream has been fittingly named River Warren, -after General Warren, who first suggested and proved its -existence, and so we have designated it on the accompanying -map of Minnesota.</p> - -<p>Lake Traverse is fifteen miles long, and the water is -nowhere more than twenty feet deep. Big Stone Lake is -twenty-six miles long, and of about the same depth. -Brown’s Valley, which connects the two, is five miles long, -and the lakes are so nearly on a level that during floods -the water from Lake Traverse sometimes overflows and -runs to the south as well as to the north.</p> - -<p><span class="pagenum"><a name="Page_227" id="Page_227">« 227 »</a></span></p> - -<div class="fig_center" style="width: 708px;"> -<a id="fig59" name="fig59"></a> -<img src="images/fig_59.png" width="708" height="397" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 59.</span>—Glacial terrace near the boundary of the glaciated area, on Raccoon Creek, a tributary of the Licking River, in Granville, Licking -County, Ohio. Height about fifty feet.</div> -</div> - -<p><span class="pagenum"><a name="Page_228" id="Page_228">« 228 »</a></span></p> - -<p>The trough occupied by these lakes and valley is from -one mile to one mile and a half in width and about 120 -feet in depth. If we had been permitted to stand upon -the bluffs overlooking it during the latter part of the -Glacial period, we should have seen the whole drainage of -the north passing by our feet on its way to the Gulf of -Mexico. As lie follows down the valley of the Minnesota -River, the observant traveller, even now, cannot fail to see in -the numerous well-preserved gravel terraces the high-water -marks of that stream when flooded with the joint product -of the annual precipitation over the vast area to the north, -and of the still more enormous quantities set free by the -melting of the western part of the great Laurentide Glacier.</p> - -<p>Numerous other deserted water-ways in the northwestern -part of the valley of the Mississippi have been -brought to light in the more recent geological surveys, -both in the United States and in Canada. During a considerable -portion of the Glacial period the Saskatchewan, -the Assiniboine, the Pembina, and the Cheyenne Rivers, -whose present drainage is into the Red River of the North, -were all turned to the south, and their temporary channels -can be distinctly traced by deserted water-courses marked -by lines of gravel deposits.<a name="FNanchor_94" id="FNanchor_94"></a><a href="#Footnote_94" class="fnanchor">[CP]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_94" id="Footnote_94"></a><a href="#FNanchor_94"><span class="label">[CP]</span></a> For further particulars, see Ice Age, pp. 293 <i>et seq.</i></p></div> - -<p>In Dakota, Professor J. E. Todd has discovered large -deserted channels on the southwestern border of the glaciated -region near the Missouri River, where evidently -streams must have flowed for a long distance in ice-channels -when the ice still continued to occupy the valley of -the James River. From these channels of ice in which -the water was held up to the level of the Missouri Coteau -the water debouched directly into channels with sides and -bottom of earthy material, which still show every mark of -their former occupation by great streams.<a name="FNanchor_95" id="FNanchor_95"></a><a href="#Footnote_95" class="fnanchor">[CQ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_95" id="Footnote_95"></a><a href="#FNanchor_95"><span class="label">[CQ]</span></a> For particulars, see Ice Age, p. 292.</p></div> - -<p>In Minnesota, also, there is abundant evidence that -while the northeastern part of the valley from Mankato -to St. Paul was occupied by ice, the drainage was temporarily -turned directly southward across the country through -Union Slough and Blue Earth River into the head-waters -of the Des Moines River in Iowa.</p> - -<p><span class="pagenum"><a name="Page_229" id="Page_229">« 229 »</a></span></p> - - -<p class="caption3nb"><i>Ancient River Terraces.</i></p> - -<p>The interest of the whole inquiry respecting the relation -of man to the Glacial period in America concentrates -upon these temporary lines of southern drainage. Wherever -they existed, the swollen floods of the Glacial period -have left their permanent marks in the deposition of extensive -gravel terraces. The material thus distributed is -derived largely from the glacial deposits through which -they run and out of which they emerge. While the height -of the terraces depended upon various conditions which -must be studied in detail, in general it may be said that it -corresponds pretty closely with the extent of the area -whose drainage was turned through the channel during -the prevalence of the ice. The height of the terraces -and the coarseness of the material seem also to have been -somewhat dependent upon the proximity of their valleys -to the areas of most vigorous ice-action, and this, in -turn, seems to lie in the rear of the moraines which President -Chamberlin has attributed to the second Glacial -epoch. Southward from this belt of moraines the terraces -uniformly and gradually diminish both in height -and in the coarseness of their gravel, until they finally -disappear in the present flood-plain of the Mississippi -River.</p> - -<div class="fig_center" style="width: 454px;"> -<a id="fig60" name="fig60"></a> -<img src="images/fig_60.png" width="454" height="92" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 60.</span>—Ideal section across a river-bed in drift region: <i>b b b</i>, old river-bed; -<i>R</i>, the present river; <i>t t</i>, upper or older terraces; <i>t′ t′</i>, lower terraces.</div> -</div> - -<p>An interesting illustration of this principle is to be -observed in the continuous valley of the Alleghany and -Ohio Rivers. The trough of this valley was reached by -the continental glacier at only a few points, the ice barely -<span class="pagenum"><a name="Page_230" id="Page_230">« 230 »</a></span> -touching it at Salamanca, N. Y., Franklin, Pa., and Cincinnati, -Ohio. But throughout its whole length the ice-front -was approximately parallel to the valley, and occupied -the head-waters of nearly all its tributaries. Now, -wherever tributaries which could be fed by glacial floods, -enter the trough of the main stream, they brought down -an excessive amount of gravel, and greatly increased the -size of the terrace in the trough itself, and from the mouth -of each such tributary to that of the next one below there -is a gradual decrease in the height of the terrace and in -the coarseness of the material.</p> - -<p>This law is illustrated with special clearness in Pennsylvania -between Franklin and Beaver. Franklin is upon -the Alleghany River, at the last point where it was reached -directly by the ice. Below this point no tributary reaches -it from the glaciated region, and none such reaches the -Ohio after its junction with the Alleghany until we come -to the mouth of Beaver Creek, about twenty-five miles below -Pittsburg.</p> - -<p>But at this point the Ohio is joined by a line of drainage -which emerges from the glaciated area only ten or -twelve miles to the north, and whose branches occupy an -exceptionally large glaciated area. Accordingly, there is at -Beaver a remarkable increase in the size of the glacial terrace -on the Ohio. In the angle down-stream between the -Beaver and the Ohio there is an enormous accumulation of -granitic pebbles, many of them almost large enough to be -called boulders, forming the delta terrace, upon which the -city is built and rising to a height of 135 feet above the -low-water mark in the Ohio. In striking confirmation of -our theory, also, the terrace in the Ohio Valley upon the -upper side of Beaver Creek is composed of fine material, -largely derived from local rocks and containing but few -granitic pebbles.</p> - -<p>From the mouth of Beaver Creek, down the Ohio, the -terrace is constant (sometimes upon one side of the river -<span class="pagenum"><a name="Page_231" id="Page_231">« 231 »</a></span> -and sometimes upon the other), but, according to rule, -the material of which it is composed gradually grows finer, -and the elevation of the terrace decreases. According to -rule, also, there is a notable increase in the height of the -terrace below each affluent which enters the river from the -glaciated region. This is specially noticeable below Marietta, -at the mouth of the Muskingum, whose head-waters -drain an extensive portion of the glaciated area. From the -mouth of the Little Beaver to this point the tributaries of -the Ohio are all small, and none of them rise within the glacial -limit. Hence they could contribute nothing of the granitic -material which enters so largely into the formation -of the river terrace; but below the mouth of the Muskingum -the terrace suddenly ascends to a height of nearly -one hundred feet above low-water mark.</p> - -<p>Again, at the mouth of the Scioto at Portsmouth, there -is a marked increase in the size of the terrace, which is -readily accounted for by the floods which came down the -Scioto Valley from the glaciated region. The next marked -increase is at Cincinnati, just below the mouth of the -Little Miami, whose whole course lay in the glaciated region, -and whose margin is lined by very pronounced terraces. -At Cincinnati the upper terrace upon which the -city is built is 120 feet above the flood-plain.</p> - -<p>Twenty-five miles farther down the river, near Lawrenceburg, -these glacial terraces are even more extensive, -the valley being there between three and four miles wide, -and being nearly filled with gravel deposits to a height of -112 feet above the flood-plain. Below this point the terraces -gradually diminish in height, and the material becomes -finer and more water-worn, until it merges at last -in the flood-plain of the Mississippi. The course of the -Wabash River is too long to permit it to add materially to -the size of the terraces which characterise the broader valley -of the Ohio below the Illinois line.</p> - -<p>It is in terraces such as these just described that we find -<span class="pagenum"><a name="Page_232" id="Page_232">« 232 »</a></span> -the imbedded relics of man which definitely connect him -with the great Ice age. These have now been found in -the glacial terraces of the Delaware River at Trenton, -N. J.; in similar terraces in the valley of the Tuscarawas -River at New Comerstown, and in the valley of the Little -Miami at Loveland and Madisonville, in Ohio; on the -East Fork of White River, at Medora, Ind.; and still, -again, at Little Falls, in the trough of the Mississippi, some -distance above Minneapolis, Minn.</p> - -<p>I append a list of the points at which various streams -from the Atlantic Ocean to the Mississippi River emerge -from the glacial boundary, and below which the terraces -are specially prominent. Of course, with the retreat of the -ice, the formation of the terraces continued northward in -the glaciated area to a greater or less distance, according -to the extent of the valley or to the length of time during -which the drainage was temporarily turned into it. -These points of emergence are: In the Delaware Valley, -at Belvidere, N. J.; in the Susquehanna, at Beach Haven, -Pa.; in the Conewango, at Ackley, Warren County; in -Oil Creek, above Titusville: in French Creek, a little -above Franklin; in Beaver Creek, at Chewtown, Lawrence -County; on the Middle Fork of Little Beaver, near New -Lisbon, Ohio; on the east branch of Sandy Creek, at East -Rochester, Columbiana County; on the Nimishillin, at -Canton, Stark County; on the Tuscarawas, at Bolivar; on -Sugar Creek, at Beech City; on the Killbuck, at Millersburg, -Holmes County; on the Mohican, near the northeast -corner of Knox County; on the Licking River, at Newark; -on Jonathan Creek, Perry County; on the Hocking, at -Lancaster; on the Scioto, at Hopetown, just above Chillicothe; -on Paint Creek, and its various tributaries, between -Chillicothe and Bainbridge; and on the Wabash, above -New Harmony, Ind.; to which may be added the Ohio -River itself, at its junction with the Miami, near Lawrenceburg.</p> - -<p><span class="pagenum"><a name="Page_233" id="Page_233">« 233 »</a></span></p> - -<p>Another class of terraces having most interesting connection -with the Glacial period is found in the arid basins -west of the Rocky Mountains. Over wide areas in Utah -and Nevada the evaporation now just balances the precipitation, -and all the streams disappear in shallow bodies -of salt water of moderate dimensions, of which Great -Salt Lake in Utah, and Mono, Pyramid, and North -Carson Lakes in Nevada, are the most familiar examples. -These occupy the lowest sinks of enclosed basins of great -depth.</p> - -<p>But there is abundant evidence that in consequence of -the increased precipitation and diminished evaporation of -the Glacial period one of these basins was filled to the brim -and the other to a depth of several hundred feet. These -former enlargements have been named after the first explorers -of the region, Captains Lahontan and Bonneville, -and are shown on the accompanying sketch map by the -shading surrounding the existing lakes.</p> - -<p>Lake Lahontan has been carefully studied by Mr. I. C. -Russell, and has been found to extend from the boundary -of Oregon to latitude 38° 30’ south, a distance of two hundred -and sixty miles. The Central Pacific Railroad runs -through its dried-up bed from Golconda to Wadsworth, -a distance of one hundred and sixty-five miles. The terraces -of the former lake are distinctly traceable at a height -of 700 feet above the present level of Lake Mono.</p> - -<p>Lake Bonneville, whose present representative is Great -Salt Lake, is the subject of a recent monograph by Mr. G. -K. Gilbert, from which it appears that this ancient body -of water occupied 19,750 square miles—an area about ten -times that of the present lake. At the time of its maximum -extension its depth was 1,000 feet, while Great Salt -Lake ranges only from fifteen to fifty feet in depth.</p> - -<p>The pass through which the discharge finally took -place is at Red Rock, on the Utah and Northern Railroad, -at the head of Cache Valley on the south and the lower -<span class="pagenum"><a name="Page_234" id="Page_234">« 234 »</a></span> -part of Marsh Creek Valley on the north. During the -long period preceding and accompanying the gradual rise -of water in the Utah basin to the level of the highest terrace, -Marsh Creek (the upper portion of which comes from -the mountains on the east and turns at right angles) had -been at work depositing a delta of loose material in the -col which separates the two valleys. This deposit rested -upon a stratum of limestone at the bottom of the pass, -and covered it with sand, clay, and gravel to a depth of -375 feet. Thus, when the water was approaching its upper -level, the only barrier to prevent its escape was this -unstable accumulation of loose material upon top of the -rock. It would have required, therefore, no prophet’s -eye to predict that the way was preparing for a tremendous -<i>débâcle</i>.</p> - -<div class="fig_center" style="width: 412px;"> -<a id="fig61" name="fig61"></a> -<img src="images/fig_61.png" width="412" height="285" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 61.</span>—Map of the Quaternary Lakes. Bonneville and Lahontan (after Gilbert -and Russell).</div> -</div> - -<p>The critical point at length was reached. After remaining -nearly at the elevation of the pass for a considerable -period, during which the 1,000-foot shore-line was formed, -<span class="pagenum"><a name="Page_235" id="Page_235">« 235 »</a></span> -the crisis came when the water began to flow northward -towards Snake River. Once begun in such loose material, -the channel rapidly enlarged until soon a stream equal to -Niagara, and at times probably much larger, was pouring -northward through the valley heretofore occupied by -the insignificant rivulets of Marsh Creek and the Port -Neuf. It is impossible to tell how rapidly the loose barrier -wore away, but there is abundant evidence in the -valley below that not only the present channel of the -lower part of Marsh Creek, but the whole bottom of the -valley for a mile or more in width, was for a considerable -time covered by a rapid stream from ten to twenty feet -in depth, and descending at the rate of thirteen feet to the -mile.</p> - -<p>The continuance of this flood was dependent upon the -amount of water to be discharged, which, as we have seen, -was that contained in an area of 20,000 square miles, with -a depth of 375 feet. A stream of the size of Niagara -would occupy about twenty-five years in the discharge of -such a mass, and this may fairly be taken as a measure of -the time through which it lasted. When the loose material -lying above the strata of limestone in Red Rock Pass -had been washed away, the lake then continued at that -level for an indefinite period, with an overflow regulated -by the annual precipitation of the drainage basin. This -stage of the lake, during which it occupied 13,000 square -miles and was 625 feet above its present level, is also -marked by an extensive and persistent shore-line all -around the basin. But, finally, the balance again turned -when the evaporation exceeded the precipitation, and the -vast body of water has since dwindled to its present insignificant -dimensions.</p> - -<p>My own interest in this discovery of Mr. Gilbert is enhanced -by the explanation it gives of a phenomenon in -the Snake River Valley which I was unable to solve when -on the ground in 1890. The present railroad town of -<span class="pagenum"><a name="Page_236" id="Page_236">« 236 »</a></span> -Pocatello is situated just where this flood emerged from -the narrower valley of Marsh Creek and the Port Neuf, -and spread itself out upon the broad plain of the Snake -River basin. The southern edge of the plain upon which -the city is built is a vast boulder-bed covered with a thin -stratum of sand and gravel. Everywhere, in sinking wells -and digging ditches on the vacant lots and in the streets -of the city, water-worn boulders of a great variety of material -and sometimes three or four feet in diameter are encountered. -I was debarred from regarding this as a terminal -moraine, both by the water-worn character of the -boulders and by the absence of any sign of ice-action in the -surrounding mountains, and I was equally debarred from -attributing it to any ordinary stream of water, both by the -size of the boulders and the fact that for a mile or more -up the Port Neuf Valley there is an intervale, forty or fifty -feet below the surface at Pocatello, and occupying the -whole width of the valley, in which there is only gravel -and fine sand, through which the present Port Neuf pursues -a meandering course. The upper end of this short -intervale is bounded by the terminus of a basaltic stream -which had flowed down the valley and filled it to a considerable -depth, but had subsequently been much eroded by -violent water-action.</p> - -<p>In the light of Mr. Gilbert’s discoveries, however, everything -is clear. The tremendous <i>débâcle</i> which he has -brought within the range of scientific vision would naturally -produce just the condition of things which is so -puzzling at Pocatello. Coming down through the restricted -channel with sufficient force to roll along boulders of -great size and to clear them all out from the upper portion -of the valley, the torrent would naturally deposit them -where the current was first checked, a mile below the -lava cliffs. The plunge of the water over these cliffs -would keep a short space below clear from boulders, and -the more moderate stream of subsequent times would fill -<span class="pagenum"><a name="Page_237" id="Page_237">« 237 »</a></span> -in the depression with the sand and gravel now occupying -it.</p> - -<p>What other effects of this remarkable outburst may be -traced farther down in the Snake River Valley I cannot -say, but it will be surprising if they do not come to light -and help to solve some of the many geological problems -yet awaiting us in this interesting region.</p> - -<p>It should have been said that during the formation of -the 625-foot, or so-called Provo shore-line, glaciers descended -from the cañons on the west flank of the Wahsatch -Mountains, and left terminal moraines to mark -the coincidence of the Glacial period with that stage -of the enlargement of the lake. Evidences of a similar -coincidence are to be found on the high-level terraces -surrounding Lake Mono, to which glaciers formerly descended -from the western flanks of the Sierra Nevada.</p> - -<p>The ancient shore-lines surrounding Lakes Bonneville -and Lahontan bear evidence also of various other episodes -in the Glacial period. Evidently there were two periods -of marked increase in the size of the lakes, with an arid -period intervening. During the first rise the level of -Bonneville attained to within ninety feet of the second, and -numerous beaches were formed, and a large amount of -yellow clay deposited. Then it seems to have been wholly -evaporated, while its soluble mineral matter was precipitated, -and so mingled with silt that it did not readily redissolve -during the second great rise of water. Partly on -this account, and partly through the influence of the outlet -into the Snake River, the lake was nearly fresh during -its second enlargement.</p> - - -<p class="caption3nb"><i>European Facts.</i></p> - -<p>In <a href="#CHAPTER_VI">Chapter VI</a> it came in place to mention many of -the facts connected with the influence of the Glacial period -upon the drainage systems of Europe. We there discussed -briefly the probable influence of the ice-obstructions -<span class="pagenum"><a name="Page_238" id="Page_238">« 238 »</a></span> -that extended across the mouths of the Dwina, the Vistula, -the Oder, the Elbe, the Weser, and the Rhine. The -drainage of the obstructed rivers in Russia was perhaps -turned southward into the Caspian and Black Seas, and -then assisted in forming the fertile soil of the plains in the -southern part of that empire.</p> - -<p>The obstructed drainage of the German rivers was -probably turned westward in front of the ice through the -Straits of Dover or across the southern part of England. -This was during the climax of the Glacial period; but later, -according to Dawkins, during a period in which the land -of the British Isles stood about 600 feet above its present -level, the streams of the eastern coast—namely, "the -Thames, Medway, Humber, Tyne, and others, joined the -Rhine, the Weser, and the Elbe, to form a river flowing -through the valley of the ocean. In like manner, the -rivers of the south of England and of the north of France -formed a great river flowing past the Channel Islands due -west into the Atlantic, and the Severn united with the rivers -of the south of Ireland; while those to the east of Ireland -joined the Dee, Mersey Ribble, and Lune, as well as those of -western Scotland, ultimately reaching the Atlantic to the -west of the Hebrides. The water-shed between the valleys -of the British Channel and the North Sea is represented by -a ridge passing due south from Folkestone to Dieppe, and -that between the drainage area and the Severn and its -tributaries on the one hand, and of the Irish Channel on -the other, by a ridge from Holyhead westward to Dublin.</p> - -<p>“This tract of low, undulating land which surrounded -Britain and Ireland on every side consisted not merely of -rich hill, valley, and plain, but also of marsh-land studded -with lakes, like the meres of Norfolk, now indicated by -the deeper soundings. These lakes were very numerous -to the south of the Isle of Wight and off the coast of Norfolk -and Suffolk.”<a name="FNanchor_96" id="FNanchor_96"></a><a href="#Footnote_96" class="fnanchor">[CR]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_96" id="Footnote_96"></a><a href="#FNanchor_96"><span class="label">[CR]</span></a> Early Man in Britain, p. 151.</p> - -<p><span class="pagenum"><a name="Page_239" id="Page_239">« 239 »</a></span></p></div> - -<p>The evidence first regarded by scientific men to be -demonstrative of the formation of extensive lakes during -the Glacial period by the direct influence of ice-dams -exists in the Parallel Roads of Glen Roy in Scotland.</p> - -<div class="fig_center" style="width: 429px;"> -<a id="fig62" name="fig62"></a> -<img src="images/fig_62.png" width="429" height="315" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 62.</span>—Parallel roads of Glen Roy.</div> -</div> - -<p>According to the description of Sir Charles Lyell, -"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 nearly its whole length, a distance of more -than ten miles, three parallel roads or shelves are traced -along the steep sides of the mountains, 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 -<span class="pagenum"><a name="Page_240" id="Page_240">« 240 »</a></span> -and so covered with boulders. They are from ten to -sixty 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 immediately above the parallel roads. The -lowest of these roads is about 850 feet above the level of -the sea, and the next about 212 feet higher, and the third -82 feet above the second. There is a fourth shelf, which -occurs only in a contiguous valley called Glen Gluoy, which -is twelve feet above the highest of all the Glen Roy roads, -and consequently about 1,156 feet above the level of the -sea. One only, the lowest of the three roads of Glen Roy, -is continued through Glen Spean, a large valley with which -Glen Roy unites. As the shelves, having no slope towards -the sea like ordinary river terraces, are always at the same -absolute height, 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, or any change either in the shape of the -ground or in the composition or hardness of the rocks.” <a name="FNanchor_97" id="FNanchor_97"></a><a href="#Footnote_97" class="fnanchor">[CS]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_97" id="Footnote_97"></a><a href="#FNanchor_97"><span class="label">[CS]</span></a> Antiquity of Man, pp. 252, 253.</p></div> - -<p>Early in his career Charles Darwin studied these ancient -beaches, and ascribed them to the action of the sea -during a period of continental subsidence. In this view -he was supported by the majority of geologists until the -region was visited by Agassiz, who saw at once the true -explanation. If these were really sea-beaches, similar deposits -<span class="pagenum"><a name="Page_241" id="Page_241">« 241 »</a></span> -should be found at the same elevation on other -mountains than those surrounding Glen Roy. Their -absence elsewhere points, therefore, to some local cause, -which was readily suggested to the trained eye of one like -Agassiz, then fresh from the study of Alpine glaciers, -who saw that these beaches were formed upon the margin -of temporary lakes, held back during the Glacial period -(as the Merjelen See now is) by a glacier which came out -of one glen and projected itself directly across the course -of another, and thus obstructed its drainage. The glacier -of Glen Spean had pushed itself across Glen Roy, as the -great Aletsch Glacier in Switzerland now pushes itself -across the little valley behind the Eggishorn.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_242" id="Page_242">« 242 »</a></span></p> - - - - -<p class="caption2"><a name="CHAPTER_VIII" id="CHAPTER_VIII">CHAPTER VIII.</a></p> - -<p class="caption2">RELICS OF MAN IN THE GLACIAL PERIOD.</p> - - -<p class="caption3nb"><i>In Glacial Terraces of the United States.</i></p> - -<p>Although the first clear evidence of glacial man was -discovered in Europe, the problem is so much simpler on -the Western Continent that we shall find it profitable to -study the American facts first. We will therefore present -a summary of them at once, and then proceed to the more -obscure problems of European archæology.</p> - -<p>The first definite discovery of human relics clearly connected -with, glacial deposits in America, and of the same -age with them, was made by Dr. C. C. Abbott, at Trenton, -N. J., in the year 1875. The city of Trenton is built upon -a delta terrace about three miles wide which occurs at the -head of tide-water on the Delaware River. This terrace -bears every mark of having been deposited by a torrential -stream which came down the valley during the closing period -of the great Ice age. The material of which the terrace -consists is all water-worn. According to the description -of Professor N. S. Shaler:</p> - -<p><span class="pagenum"><a name="Page_243" id="Page_243">« 243 »</a></span></p> - -<div class="fig_center" style="width: 439px;"> -<a id="fig63" name="fig63"></a> -<img src="images/fig_63.png" width="439" height="665" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 63.</span>—The glaciated portion is shaded. The shading on the Lehigh and Delaware -Rivers indicates glacial terraces, which are absent from the Schuylkill.</div> -</div> - -<p><span class="pagenum"><a name="Page_244" id="Page_244">« 244 »</a></span></p> - -<p>“The general structure of the mass is neither that of -ordinary boulder-clay nor of stratified gravels, such as are -formed by the complete rearrangement by water of the -elements of simple drift-deposits. It is made up of boulders, -pebbles, and sand, varying in size from masses containing -one hundred cubic feet or more to the finest sand -of the ordinary sea-beaches. There is little trace of true -clay in the deposit; there is rarely enough to give the -least trace of cementation to the masses. The various elements -are rather confusedly arranged; the large boulders -not being grouped on any particular level, and their major -axes not always distinctly coinciding with the horizon. -All the pebbles and boulders, so far as observed, are smooth -and water-worn, a careful search having failed to show -evidence of distinct glacial scratching or polishing on -their surfaces. The type of pebble is the subovate or discoidal, -and though many depart from this form, yet nearly -all observed by me had been worn so as to show that their -shape had been determined by running water. The materials -comprising the deposit are very varied, but all I observed -could apparently with reason be supposed to have -come from the extensive valley of the river near which -they lie, except perhaps the fragments of some rather rare -hypogene rocks.”</p> - -<div class="fig_right" style="width: 360px;"> -<a id="fig64" name="fig64"></a> -<img src="images/fig_64.png" width="360" height="220" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 64.</span>—Palæolith found by Abbott in New Jersey, slightly reduced.</div> -</div> - -<p>A conclusive proof of the relation of this Trenton -delta terrace to the Glacial period is found in the fact that -the gravel deposit is continuous with terraces extending -up the trough of the valley of the Delaware to the glaciated -area and beyond. As, however, the descent of the river-bed -is rapid (about four feet to the mile) from the glacial -<span class="pagenum"><a name="Page_245" id="Page_245">« 245 »</a></span> -border down to tide-water, the terrace is not remarkably -high, being only about fifteen or twenty feet above the present -flood-plain. But it is continuous, and similar in composition -with the great enlargement in the delta at Trenton. -Without doubt, therefore, the deposit represents the -overwash gravel of the Glacial period.</p> - -<p>Fortunately for science, Dr. C. C. Abbott, whose tastes -for archæological investigations were early developed, had -his residence upon the border of this glacial delta terrace -at Trenton, and as early as 1875 began to find rough-stone -implements of a peculiar type in the talus of the bank -where the river was undermining the terrace. In turning -his attention to the numerous fresh exposures of gravel -made by railroad and other excavations during the following -year, he found several of the implements in undisturbed -strata, some of which were sixteen feet below the surface. -Since that time he has continued to make discoveries at -various intervals. In 1888 he had found four hundred -implements of the palæolithic type at Trenton, sixty of -which had been taken from recorded depths in the gravel, -two hundred and fifty from the talus at the bluff facing -the river, and the remainder from the surface, or derived -from collectors who did not record the positions or circumstances -under which they were found.</p> - -<div class="fig_center" style="width: 438px;"> -<a id="fig65" name="fig65"></a> -<img src="images/fig_65.png" width="438" height="57" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 65.</span>—Section across the Delaware River at Trenton. New Jersey: <i>a</i>, <i>a</i>, -Philadelphia red gravel and brick-clay (McGee’s Columbia deposit); <i>b</i>. <i>b</i>, -Trenton gravel, in which the implements are found: <i>c</i>, present flood-plain of -the Delaware River (after Lewis). (From Abbott’s Primitive Industry.)</div> -</div> - -<p>The material from which the implements at Trenton -are made is argillite—that is, a clay slate which has been -so metamorphosed as to be susceptible of fracture, almost -like flint. It is, however, by no means capable of being -worked into such delicate forms as flint is. But as it is -<span class="pagenum"><a name="Page_246" id="Page_246">« 246 »</a></span> -the only material in the vicinity capable of being chipped, -prehistoric men of that vicinity were compelled to make a -virtue of necessity and use the inferior material. Of all -the implements found by Dr. Abbott in the gravel, only -one was flint; while upon the surface innumerable arrow-heads -of flint have been found. The transition, also, in -the type of implements is as sudden as that in the kind of -material of which they are made. Below the superficial -deposit of black soil, extending down to the depth of about -one foot, the modern Indian flint implements entirely -disappear, and implements of palæolithic type only are -found.</p> - -<div class="fig_center" style="width: 394px;"> -<a id="fig66" name="fig66"></a> -<img src="images/fig_66.png" width="394" height="415" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 66.</span>—Section of the Trenton gravel in which the implements described in -the text are found. The shelf on which the man stands is made in process -of excavation. The gravel is the same above and below (photograph by -Abbott).</div> -</div> - -<p><span class="pagenum"><a name="Page_247" id="Page_247">« 247 »</a></span></p> - -<div class="fig_center" style="width: 302px;"> -<a id="fig67" name="fig67"></a> -<img src="images/fig_67.png" width="302" height="537" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 67.</span>—Face view of argillite implement, found by Dr. C. C. Abbott, in 1876, -at Trenton, New Jersey, in gravel, three feet from face of bluff, and twenty-two -feet from the surface (No. 10,985) (Putnam).</div> -</div> - -<p>In the year 1882, after I had traced the glacial boundary -westward from the Delaware River, across the States -of Pennsylvania, Ohio, and Indiana, I was struck with -<span class="pagenum"><a name="Page_248" id="Page_248">« 248 »</a></span> -the similarity between the terrace at Trenton and numerous -terraces which I had attributed to the Glacial age in -Ohio and the other States. It adds much to the interest -of subsequent discoveries to note that in 1884, in my report -to the Western Reserve Historical Society upon the -glacial boundary of Ohio, I wrote as follows:</p> - -<p>“The gravel in which they [Dr. Abbott’s implements] -are found is glacial gravel deposited upon the banks of the -Delaware when, during the last stages of the Glacial period, -the river was swollen with vast floods of water from -the melting ice. Man was on this continent at that period -<span class="pagenum"><a name="Page_249" id="Page_249">« 249 »</a></span> -when the climate and ice of Greenland extended to the -mouth of New York Harbor. The probability is, that if -he was in New Jersey at that time, he was also upon the -banks of the Ohio, and the extensive terrace and gravel -deposits in the southern part of our State should be closely -scanned by archæologists. When observers become familiar -with the rude form of these palæolithic implements, -they will doubtless find them in abundance. But whether -we find them or not in this State [Ohio], if you admit, as -I am compelled to do, the genuineness of those found by -Dr. Abbott, our investigation into the glacial phenomena -of Ohio must have an important archæological significance, -for they bear upon the question of the chronology of the -Glacial period, and so upon that of man’s appearance in -New Jersey.”</p> - -<table summary="figs"> -<tr> - <td><a id="fig68" name="fig68"></a> - <img src="images/fig_68.png" width="283" height="409" alt="" /></td> - <td><a id="fig69" name="fig69"></a> - <img src="images/fig_69.png" width="262" height="301" alt="" /></td> -</tr> -<tr> - <td class="vtop" style="width: 300px"><div class="fig_caption"><span class="smcap">Fig. 68.</span>—Argillite implement found by Dr. C. C Abbott, March, 1879, at A. K. - Rowan’s farm, Trenton, New Jersey, in gravel sixteen feet from surface: a, - face view; b, side view (No. 11,286) (Putnam).</div></td> - <td class="vtop" style="width: 300px"><div class="fig_caption"><span class="smcap">Fig. 69.</span>—Chipped pebble of black chert, found by Dr. C. L. Metz. October, 1885, at Madisonville, Ohio, in gravel eight feet from surface under clay: <i>a</i>, face - view; <i>b</i>, side view.</div></td> -</tr> -</table> - -<p>The expectation of finding evidence of preglacial man -in Ohio was justified soon after this (in 1885), when Dr. C -<span class="pagenum"><a name="Page_250" id="Page_250">« 250 »</a></span> -L. Metz, while co-co-operating with Professor F. W. Putnam, -of the Peabody Museum, Cambridge, Mass., in field work, -discovered a flint implement of palæolithic type in undisturbed -strata of the glacial terrace of the Little Miami -River, near his residence at Madisonville, Ohio. In 1887 -Dr. Metz found another implement in the terrace of the -same river, at Loveland, about twenty-five miles farther -up the stream. The implement at Madisonville occurred -eight feet below the surface, and about a mile back from -the edge of the terrace; while that at Loveland was -found in a coarser deposit, about a quarter of a mile back -from the present stream, and thirty feet below the surface. -Mastodon-bones also were discovered in close proximity to -the implement at Loveland.</p> - -<div class="fig_center" style="width: 416px;"> -<a id="fig70" name="fig70"></a> -<img src="images/fig_70.png" width="416" height="465" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 70.</span></div> -</div> - -<p><span class="pagenum"><a name="Page_251" id="Page_251">« 251 »</a></span></p> - -<p>Interest in these investigations was still further increased -by the report of Mr. Hilborne T. Cresson, of -Philadelphia, that in 1886, with my map of the glaciated -region in hand, he had found an implement of -palæolithic type in undisturbed strata of the glacial terrace -bordering the East Branch of White River, near -the glacial boundary at Medora, Jackson County, Ind. -The terrace was about fifty feet above the flood-plain of -the river.</p> - -<p>Later still, in October, 1889, Mr. W. C. Mills, of Newcomerstown, -Tuscarawas County, Ohio, found in that town -a finely shaped flint implement sixteen feet below the surface -of the terrace of glacial gravel which lines the margin -of the Tuscarawas Valley.<a name="FNanchor_98" id="FNanchor_98"></a><a href="#Footnote_98" class="fnanchor">[CT]</a> Mr. Mills was not aware of the -importance of this discovery until meeting with me some -months later, when he described the situation to me, -and soon after sent the implement for examination. In -company with Judge C. C. Baldwin, President of the -Western Reserve Historical Society, and several others, a -visit was made to Mr. Mills, and we carefully examined -the gravel-pit in which the implement occurred, and collected -evidence which was abundant to corroborate all -his statements. The implement in question is made from -a peculiar flint which is found in the Lower Mercer limestone, -of which there are outcrops a few miles distant, and -it resembles in so many ways the typical implements found -by Boucher de Perthes, at Abbeville, that, except for the -difference in the material from which it is made, it would -be impossible to distinguish it from them. The similarity -of pattern is too minute to have originated except from -imitation.</p> - -<div class="footnote"> - -<p><a name="Footnote_98" id="Footnote_98"></a><a href="#FNanchor_98"><span class="label">[CT]</span></a> For typical section of a glacial terrace in Ohio, see <a href="#Page_227">p. 227</a>.</p> - -<p><span class="pagenum"><a name="Page_252" id="Page_252">« 252 »</a></span></p></div> - -<div class="fig_center" style="width: 374px;"> -<a id="fig71" name="fig71"></a> -<img src="images/fig_71.png" width="374" height="473" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 71.</span>—The smaller is the palæolith from Newcomerstown, the larger from -Amiens (face view), reduced one half in diameter.</div> -</div> - -<p>In 1877, a year after the discoveries by Dr. Abbott in -New Jersey, some rude quartz implements were discovered -by Professor N. H. Winchell in the glacial terraces of the -upper Mississippi, in the vicinity of Little Falls, Morrison -County, Minn. This locality was afterwards more fully -<span class="pagenum"><a name="Page_253" id="Page_253">« 253 »</a></span> -explored by Miss Franc E. Babbitt, who succeeded in finding -so large a number of the implements as to set at rest -all question concerning their human origin. According -to Mr. Warren Upham, the glacial flood-plain of the Mississippi -is here about three miles wide, with an elevation of -from twenty-five to thirty feet above the river. It is in -a stream near the bottom of this glacial terrace that the -most of Miss Babbitt’s discoveries were made, and Mr. -<span class="pagenum"><a name="Page_254" id="Page_254">« 254 »</a></span> -Upham has pretty clearly shown that the gravel of the -terrace overlying them was mostly deposited while the ice-front -was still lingering about sixty miles farther north, -in the vicinity of Itasca Lake.<a name="FNanchor_99" id="FNanchor_99"></a><a href="#Footnote_99" class="fnanchor">[CU]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_99" id="Footnote_99"></a><a href="#FNanchor_99"><span class="label">[CU]</span></a> For a general map, see <a href="#Page_66">p. 66</a>; also <a href="#Page_225">p. 225</a>.</p></div> - -<div class="fig_center" style="width: 372px;"> -<a id="fig72" name="fig72"></a> -<img src="images/fig_72.png" width="372" height="471" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 72.</span>—Edge view of the preceding.</div> -</div> - -<div class="fig_center" style="width: 432px;"> -<a id="fig73" name="fig73"></a> -<img src="images/fig_73.png" width="432" height="57" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 73.</span>—Section across the Mississippi Valley at Little Falls, Minnesota, showing -the stratum in which chipped quartz fragments were found by Miss F. E. -Babbitt, as described in the text (Upham).</div> -</div> - -<p>Up to this time the above are all the instances in which -the relics of man are directly and indubitably connected -with deposits of this particular period east of the Rocky -Mountains. Probably it is incorrect to speak of these as -preglacial, for the portion of the period at which the deposits -incorporating human relics were made is well on -towards the close of the great Ice age, since these terraces -were, in some cases, and may have been in all cases, deposited -after the ice-front had withdrawn nearly, if not quite, -to the water-shed of the St Lawrence basin. It may be -difficult to demonstrate this with reference to the gravel -deposits at Trenton, Madisonville, and Medora, but it is -evident at a glance in the case of Newcomerstown and -Little Falls.</p> - -<p>That the implement-bearing gravel of Trenton, N. J., -belongs to the later stages of the Glacial period is evident -from its relation to what Professor H. Carvill Lewis called -“the Philadelphia red gravel and brick-clay,” but which, -from its large development in the District of Columbia at -Washington, is called by Mr. McGee the “Columbia deposit.” -The city of Philadelphia is built upon this formation -in the Delaware Valley, and the brick for its houses -is obtained from it; the cellar of each house ordinarily -furnishing clay enough for its brick walls. This clay is -<span class="pagenum"><a name="Page_255" id="Page_255">« 255 »</a></span> -of course a deposit in comparatively still water, which -would imply deposition during a period of land subsidence. -But that it was ice-laden water which flooded the banks is -shown by the frequent occurrence of large blocks of stone -in the deposits, such as could have been transported only -in connection with floating ice. The boulders in the -Columbia formation clearly belong to the individual river -valleys in which they are found, and doubtless are to be -connected with the flooded condition of those valleys -when, by means of a northerly subsidence, the gradient of -the streams was considerably less than now.</p> - -<div class="fig_center" style="width: 375px;"> -<a id="fig74" name="fig74"></a> -<img src="images/fig_74.png" width="375" height="508" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 74.</span>—Quartz implement, found by Miss F. E. Babbitt, 1878, at Little Falls, -Minnesota, in modified drift, fifteen feet below surface: <i>a</i>, face view; <i>b</i>, -profile view. The black represented on the cut is the matrix of the quartz -vein (No. 31,323) (Putnam).</div> -</div> - -<p><span class="pagenum"><a name="Page_256" id="Page_256">« 256 »</a></span></p> - -<p>There is some difference of opinion in respect to the -extent of this subsidence, and, indeed, respecting the -height attained by the Philadelphia brick-clay, or McGee’s -Columbia deposit. Professor Lewis (whose residence was -at Philadelphia, and who had devoted much time to field -observations) insisted that the deposit could not be found -higher than from 180 to 200 feet above the immediate -flood-plain of the river valleys where they occur. But, -without entering upon this disputed question, it is sufficient -to consider the bearing of the facts that are accepted -by all—namely, that towards the close of the Glacial period -there was a marked subsidence of the land on the eastern -coast of North America, increasing towards the north.</p> - -<p>Fully to comprehend the situation, we need to bring -before the mind some of the indirect effects of the Glacial -period in this region. The most important of these was -the necessary projection of subglacial conditions over a -considerable belt of territory to the south of that actually -reached by glacial ice; so that, while there are no clear -indications of the existence of local glaciers in the Appalachian -Mountains south of the central part of Pennsylvania, -there are many indications of increased snow-fall -upon the mountains, connected with prolonged winters and -with a great increase of spring floods and ice-gorges upon -the annual breaking up of winter.</p> - -<p>These facts have been stated in detail by Mr. McGee,<a name="FNanchor_100" id="FNanchor_100"></a><a href="#Footnote_100" class="fnanchor">[CV]</a> -from whose report it appears that, on the Potomac at -<span class="pagenum"><a name="Page_257" id="Page_257">« 257 »</a></span> -Washington, the surface of the Columbia deposit is 150 -feet above tide, and that the deposit itself contains many -boulders, some of which are as much as two or three feet in -diameter. These are mingled with the gravel in such a -way as to show that they must have been brought down by -floating ice from the head-waters of the Potomac when the -winters were much more severe than now. That this deposit -is properly the work of the river is shown by the entire -absence of marine shells.</p> - -<div class="footnote"> - -<p><a name="Footnote_100" id="Footnote_100"></a><a href="#FNanchor_100"><span class="label">[CV]</span></a> Seventh Annual Report of the United States Geological Survey -for 1885 and 1886, pp. 537-646.</p></div> - -<p>According to Mr. McGee, also, there is a gradual decrease -in the height of these delta terraces of the Columbia -period as they recede from the glacial boundary—that at -the mouth of the Susquehanna being 245 feet, that of the -Potomac 140 feet, that on the Rappahannock 125, that on -the James 100, and that on the Roanoke 75; while the -size of the transported boulders along the streams also -gradually diminishes in the same order. During the -Columbia period the Susquehanna River transported -boulders fifty times the size now transported, while the -Potomac transported them only up to twenty times, the -Rappahannock only ten times, the James only five, and -the Roanoke only two or three times the size of those now -transported. This progressive diminution, both in the -extent of the deposit and in the coarseness of the material -deposited by these rivers at about the time of the maximum -portion of the Glacial period, is what would naturally -be expected under the conditions supposed to exist in connection -with the great Ice age, and is an important confirmation -of the glacial theory.</p> - -<p>That the period of subsidence and more intense glacial -conditions during which the Columbia deposits took place, -preceded, by a long interval, the deposition of the gravel -terraces at Trenton, N. J., and the analogous deposits in -the Mississippi Valley where palæolithic implements have -been found, is evident enough. The Trenton gravel was -deposited in a recess in the Columbia deposit which had -<span class="pagenum"><a name="Page_258" id="Page_258">« 258 »</a></span> -been previously worn out by the stream. Indeed, in every -place where opportunity offers for direct observation the -Trenton gravel is seen to be distinctly subsequent to the -other. It was not <i>buried by</i> the Philadelphia red gravel and -brick-clay, but to a limited degree overlies and <i>buries</i> it.</p> - -<p>The data for measuring the absolute length of time -between these two stages of the Glacial period are very -indefinite. Mr. McGee, however, supposes that since the -Columbia period a sufficient time has elapsed for the falls -of the Susquehanna to recede more than twenty miles -and for those of the Potomac eighteen miles, and this -through a rock which is exceedingly obdurate. But, in -channels opening, as these do, freely outward, it is difficult -to tell in what epochs the erosion has been principally -performed, since there are no buried channels, as in the -glaciated area, enabling us to determine whether or not -much of the eroding work of the river may have been accomplished -in preglacial times.</p> - -<p>The lapse of time which, upon the least calculation, -separates the Columbia epoch from the Trenton, gives -unusual importance to any discovery of palæolithic implements -which may be made in the earlier deposits. We -are bound, therefore, to consider with special caution the -reported discovery of an implement in these deposits at -Claymont, Delaware. The discovery was made by Dr. -Hilborne T. Cresson, on July 13, 1887, during the progress -of an extensive excavation in constructing the Baltimore -and Ohio Railroad, nineteen miles south of Philadelphia. -The implement was from eight to nine feet -below the surface. As there is so much chance for error -of judgment respecting the undisturbed condition of the -strata, and as there was so little opportunity for Dr. Cresson -to verify his conclusion, we may well wait for the cumulative -support of other discoveries before building a theory -upon it; still, it will be profitable to consider the situation.</p> - -<p><span class="pagenum"><a name="Page_259" id="Page_259">« 259 »</a></span></p> - -<div class="fig_center" style="width: 387px;"> -<a id="fig75" name="fig75"></a> -<img src="images/fig_75.png" width="387" height="457" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 75.</span>—Argillite implement, found by H. T. Cresson, 1887, in Baltimore and -Ohio Railroad cut, one mile from Claymont, Delaware, in Columbia gravel, -eight to nine feet below the overlying clay bed: <i>a</i>, face view; <i>b</i>, side view -(No. 45,726) (Putnam).</div> -</div> - -<p>Both Mr. McGee and myself have visited the locality -with Dr. Cresson, and there can be no doubt that the -implement occurred underneath the Columbia gravel. -The line of demarcation is here very sharp between that -gravel and the decomposed strata of underlying gneiss -rock, which appears in our illustration as a light band in -the middle of the section exposed. Some large boulders -which could have been moved only in connection with -floating ice are found in the overlying deposit near by. -This excavation is about one mile and a half west of the -Delaware River, and about 150 feet above it, being nearly -at the uppermost limit of the Columbia deposit in that -vicinity.</p> - -<p><span class="pagenum"><a name="Page_260" id="Page_260">« 260 »</a></span></p> - -<div class="fig_center" style="width: 707px;"> -<a id="fig76" name="fig76"></a> -<img src="images/fig_76.png" width="707" height="405" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 76.</span>—General section of Baltimore and Ohio cut, near Claymont, Delaware, where Mr. Cresson found palæolithic implements figured -in the text (from photograph by Cresson).</div> -</div> - -<p><span class="pagenum"><a name="Page_261" id="Page_261">« 261 »</a></span></p> - -<p>The age of these deposits in which implements have -been found at Claymont and at Trenton will be referred -to again when we come to the specific discussion of the -date of the Glacial period. It is sufficient here to bring -before our minds clearly, first, the fact that this at Claymont -is connected with the river floods accompanying the -ice at its time of maximum extension, and when there was -a gradually increasing or differential depression of the -country to an unknown extent to the northward.</p> - -<p>Two radically different theories are presented to account -for the deposits variously known as the Columbia gravel -and the Philadelphia brick-clay. Mr. McGee, in the -monograph above referred to, supposes them to have been -deposited during a period of a general subsidence of the -coast-line; so that they took place at about tide-level. Mr. -Upham, on the other hand, supposes them to have been -deposited during the period of general elevation to whose -influence he mainly attributes the Glacial period itself. -In his view much of the shallow sea-bottom adjoining the -present shore off from Delaware and Chesapeake Bays -was then a land-surface, and the Hudson, the Delaware, -and the Susquehanna Rivers, coming down from the still -higher elevations of the north, flowed through extensive -plains so related to the northern areas of elevation that -deposition was occurring in their valleys, owing in part to -the flooded condition of the streams, in part to the differential -elevation, and in part to the superabundance of silt -and other <i>débris</i> furnished by the melting ice-sheet in the -head-waters of these streams.</p> - -<p>The deposits of Trenton gravel occurred much later, -at a time when the ice had melted far back towards the -head-waters of the Delaware, and after the land had -nearly resumed its present relations of level, if indeed -<span class="pagenum"><a name="Page_262" id="Page_262">« 262 »</a></span> -it had not risen northward to a still greater relative -height.</p> - -<p>As would be expected from the climatic conditions -accompanying the Glacial epoch, man’s companions in the -animal world were very different during the period when -the high-level river gravels of America were forming from -those with which he is now associated. From the remains -actually discovered, either in these gravels or in close proximity -to them, we infer that, while the mastodon was the -most frequent of the extinct quadrupeds with which man -then had to contend in that region, he must have been -familiar also with the walrus, the Greenland reindeer, the -caribou, the bison, the moose, and the musk ox.</p> - - -<p class="caption3nb"><i>In the Glacial Terraces of Europe.</i></p> - -<p>The existence of glacial man in Europe was first determined -in connection with the high-level river gravels -already described in the valley of the Somme, situated in -Picardy in the northern part of France. Here in 1841 -Boucher de Perthes began to discover rudely fashioned -stone implements in undisturbed strata of the gravel terraces, -whose connection with the Glacial period we have -already made clear. But for nearly twenty years his discoveries -were ignored by scientific men, although he made -persistent efforts to get the facts before them, and published -a full account of them with illustrations as early as -1847. Some suggested fraud on the part of the workmen; -others without examination declared that the gravel must -have been disturbed; while others, still, denied altogether -the artificial character of the implements.</p> - -<div class="fig_center" style="width: 398px;"> -<a id="fig77" name="fig77"></a> -<img src="images/fig_77.png" width="398" height="59" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 77.</span>—Section across valley of the Somme: 1, peat, twenty to thirty feet -thick, resting on gravel, <i>a</i>; 2, lower-level gravels, with elephant-bones and -flint implements, covered with river-loam twenty to forty feet thick; 3, -upper-level gravels, with similar fossils covered with loam, in all, thirty feet -thick; 4, upland-loam, five to six feet thick; 5, Eocene-Tertiary.</div> -</div> - -<p><span class="pagenum"><a name="Page_263" id="Page_263">« 263 »</a></span></p> - -<p>At length, Dr. Regillout, an eminent physician residing -at Amiens, about forty miles higher up the Somme -than Abbeville, visited Boucher de Perthes, and, upon seeing -the similarity between the gravel terraces at Abbeville -and Amiens, returned home to look for similar implements -in the high-level gravel-pits at St. Acheul, a suburb of -Amiens. Almost immediately he discovered flint implements -there of the same pattern with those at Abbeville, -and in undisturbed strata of the gravel terrace, where it -rested on the original chalk formation, at a height of 90 -feet above the river. In the course of four years, Dr. Regillout -found several hundred of these implements, and in -1854 published an illustrated report upon the discoveries.</p> - -<p>Still the scientific world remained incredulous until -the years 1858 and 1859, when Dr. Falconer, Mr. Prestwich, -Mr. John Evans, Mr. Flower, Sir Charles Lyell, of -England, and MM. Pouchet and Gaudry, of France, visited -Abbeville and Amiens, and succeeded in making similar -discoveries for themselves. Additional discoveries at St. -Acheul have continued up to the present time whenever -excavations have gone on at the gravel-pits. Mr. Prestwich -estimates that there is an implement to every cubic -metre of gravel, and says that he himself has brought away -at different times more than two hundred specimens, and -that the total number found in this one locality can hardly -be under four thousand. “The gravel-beds are on the -brow of a hill 97 feet above the river Somme,” and besides -the relics of man contain numerous fluviatile and land -shells together with “teeth and bones of the mammoth, -rhinoceros, horse, reindeer, and red deer, but not of the -hippopotamus,”<a name="FNanchor_101" id="FNanchor_101"></a><a href="#Footnote_101" class="fnanchor">[CW]</a> bones of the latter animal being found -here only in the gravels of the lower terraces, where they -<span class="pagenum"><a name="Page_264" id="Page_264">« 264 »</a></span> -are less than thirty feet above the river, and mark a considerably -later stage in the erosion of the valley. While -many of the implements found at Amiens seem to have -been somewhat worn and rolled, “others are as sharp and -fresh as when first made.... The bedding of the gravel is -extremely irregular and contorted, as though it had been -pushed about by a force acting from above; and this, together -with the occurrence of blocks of Tertiary sandstone -of considerable size, leads to the inference that both are -due to the action of river-ice. In the Seine Valley blocks -of still larger size, and transported from greater distances, -are found in gravels of the same age.”</p> - -<div class="footnote"> - -<p><a name="Footnote_101" id="Footnote_101"></a><a href="#FNanchor_101"><span class="label">[CW]</span></a> Prestwich’s Geology, vol. ii, p. 481.</p></div> - -<p>“Flint implements are found under similar conditions -in many of the river-valleys of other parts of France, especially -in the neighbourhood of Paris; of Mons in Belgium; -in Spain, in the neighbourhood of Madrid, in Portugal, -in Italy, and in Greece; but they have not been discovered -in the drift-beds of Denmark, Sweden, or Russia, -nor is there any well-authenticated instance of the occurrence -of palæoliths in Germany.”<a name="FNanchor_102" id="FNanchor_102"></a><a href="#Footnote_102" class="fnanchor">[CX]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_102" id="Footnote_102"></a><a href="#FNanchor_102"><span class="label">[CX]</span></a> Prestwich’s Geology, vol. ii, pp. 481, 482.</p></div> - -<p>When once the fact had been established that man was -in northern France at the time of the deposition of the -high-level gravels of the Somme and the Seine, renewed -attention was directed to terraces of similar age in southern -England. One of these is that upon which the city -of London is built, and which, according to Lyell’s description, -“extends from above Maidenhead through the metropolis -to the sea, a distance from west to east of fifty -miles, having a width varying from two to nine miles. Its -thickness ranges commonly from five to fifteen feet.”<a name="FNanchor_103" id="FNanchor_103"></a><a href="#Footnote_103" class="fnanchor">[CY]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_103" id="Footnote_103"></a><a href="#FNanchor_103"><span class="label">[CY]</span></a> Antiquity of Man, pp. 154, 155.</p></div> - -<p>For a long time geologists had been familiar with the -fact that these terraces of the Thames contain the remains -of numerous extinct animals, among which are included -<span class="pagenum"><a name="Page_265" id="Page_265">« 265 »</a></span> -the mammoth and a species of rhinoceros. Upon directing -special attention to the subject, it was found that, at -various intervals, the remains of man, also, had been reported -from the same deposits. As long ago as 1715 Mr. -Conyers discovered a palæolithic implement, in connection -with the skeleton of an elephant, at Black Mary’s, near -Gray’s Inn Lane, London. This implement is preserved -in the British Museum, and closely resembles typical specimens -from the gravel at Amiens. Other implements of -similar character have been found in the valley of the -Wey near Guilford, also in the valley of the Darent, near -Whitstable in Kent, and between Heme Bay and the Reculvers. -While the exact position of these implements in -the gravel had not been so positively noted as in the case -of those found at Amiens and Abbeville, there can be little -doubt that man, in company with the extinct animals -mentioned, inhabited the valley of the Thames at a period -when its annual floods spread over the whole terrace-plain -upon which the main part of London is built.</p> - -<p>In the valley of the Ouse, however, near Bedford, the -discovery of palæolithic implements in the gravel terraces -connected with the Glacial period and in intimate association -with bones of the elephant, rhinoceros, hippopotamus, -and other extinct animals, has been as fully established as -in the valley of the Somme. The discoveries here were -first made in the year 1860, by Mr. James Wyatt, in a -gravel-pit at Biddenham, two miles northwest of Bedford. -Two flint implements were thrown out by workmen in one -day from undisturbed strata thirteen feet below the surface, -and numerous other specimens have since been found -in a similar situation.</p> - -<p>The valley of the Ouse is bordered on either side by -sections of a superficial blanket of glacial drift containing -many transported boulders of considerable size. The valley -is here about two miles wide, and ninety feet deep. -The gravel deposit, however, in which the implements -<span class="pagenum"><a name="Page_266" id="Page_266">« 266 »</a></span> -were found, is only about thirty feet above the present -level of the river, and hence represents the middle period -of the work of the river in erosion.</p> - -<p>Another locality in England in which similar discoveries -have been made, is at Hoxne, about five miles from -Diss, in Suffolk County. Like that in the valley of the -Thames, however, the implements were found a long time -before the significance of the discovery was recognized. -Mr. John Frere reported the discovery to the Society of -Antiquaries in 1801, and gave some of the implements -both to the society and to the British Museum, in whose -collections they are still preserved. The implements are of -the true palæolithic type, and existed in such abundance, -and were so free from signs of wear, that the conclusion -seemed probable that a manufactory of them had been -uncovered. As many as five or six to the square yard are -said to have been found. Indeed, their numbers were so -great that the workmen “had emptied baskets of them -into the ruts of the adjoining road before becoming aware -of their value.”</p> - -<p>The deposit in which they are found is situated in the -valley of Gold Brook, a tributary of the Waveney. The -implements occurred about twelve feet below the surface, -in fresh-water deposits, filling a hollow eroded in the -glacial deposit covering that part of England. This, -therefore, is clearly either of post-glacial or of late glacial -age.</p> - -<p>Still another locality in which similar palæolithic implements -were found in undisturbed gravel of this same -age in eastern England is Icklingham, in the valley of the -Lark, where the situation is quite similar to that already -described at Bedford, on the Ouse.</p> - -<p>The last place we will stop to mention in England -which was visited by palæolithic man, during or soon after -the Glacial epoch, is to be found in the vicinity of Southampton. -At this time the Isle of Wight was joined to the -<span class="pagenum"><a name="Page_267" id="Page_267">« 267 »</a></span> -mainland, and not improbably England itself to the Continent. -The river, then flowing through the depression of -the Solent and the Southampton Water, occupied a much -higher level than now, leaving terraces along the shore at -various places, in which the tools of palæolithic man have -been discovered.</p> - -<p>Though these are the best authenticated discoveries -connecting man with the Glacial period in England, they -are by no means the only probable cases. Almost every -valley of southern England furnishes evidence of a similar -but less demonstrative character.</p> - - -<p class="caption3nb"><i>In Cave Deposits.</i></p> - -<p>The discovery of the remains of man in the high-level -river-gravels deposited near the close of the Glacial period -led to a revision of the evidence which had from time to -time been reported connecting the remains of man with -those of various extinct animals in cave deposits both in -England and upon the Continent.</p> - - -<p class="caption3nb"><i>The British Isles.</i></p> - -<p>As early as 1826, Rev. J. MacEnery, a Roman Catholic -priest residing near Torquay, in Devonshire, England, had -made some most remarkable discoveries in a cavern at -Kent’s Hole, near his home; but, owing to his early death, -and to the incredulity of that generation of scientific men, -his story was neither credited nor published till 1859. -About this time, a new cave having been discovered not -far away, at Brixham, the best qualified members of the -Royal Society (Lyell, Phillips, Lubbock, Evans, Vivian, -Pengelly, Busk, Dawkins, and Sanford) were deputed to -see that it was carefully explored. Mr. Pengelly, who had -had twenty years’ experience in similar explorations, directed -and superintended the work. Every portion of the -contents was examined with minutest care. Kent’s Hole -<span class="pagenum"><a name="Page_268" id="Page_268">« 268 »</a></span> -is “180 to 190 feet above the level of mean tide, and -about 70 feet above the bottom of the valley immediately -adjacent.”<a name="FNanchor_104" id="FNanchor_104"></a><a href="#Footnote_104" class="fnanchor">[CZ]</a> In one chamber the excavation was about -sixty feet square. The contents were arranged in the following -order:</p> - -<div class="footnote"> - -<p><a name="Footnote_104" id="Footnote_104"></a><a href="#FNanchor_104"><span class="label">[CZ]</span></a> Dawkins’s Cave-Hunting, p. 325.</p></div> - -<div class="fig_center" style="width: 385px;"> -<a id="fig78" name="fig78"></a> -<img src="images/fig_78.png" width="385" height="398" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 78.</span>—Mouth of Kent’s Hole.</div> -</div> - -<p>1. A surface of dark earth a few inches thick, containing -Roman pottery, iron and bronze spear-heads, together -with polished stone weapons. There were, too, in this -stratum bones of cows, goats, and horses, mingled with -large quantities of charcoal.</p> - -<p><span class="pagenum"><a name="Page_269" id="Page_269">« 269 »</a></span></p> - -<p>2. Below this was a stalagmite floor from one to three -feet thick, formed by the dripping of lime-water from the -roof.</p> - -<p>3. Under this crust of stalagmite was a compact deposit -of red earth, from two to thirteen feet thick.<a name="FNanchor_105" id="FNanchor_105"></a><a href="#Footnote_105" class="fnanchor">[DA]</a> Flint implements -of various kinds and charcoal were also found at -different depths; also an awl, or piercer; a needle with -the eye large enough to admit small pack-thread; and -three harpoon-heads made out of bone and deer’s -horn.</p> - -<div class="footnote"> - -<p><a name="Footnote_105" id="Footnote_105"></a><a href="#FNanchor_105"><span class="label">[DA]</span></a> Dawkins’s Cave-Hunting, p. 326; Lyell’s Antiquity of Man, -p. 101.</p></div> - -<p>4. Flint implements were also obtained in a conglomerate -(breccia) still below this. The fossil bones in this -cave belonged to the same species of animals as those discovered -in a cave near Wells.</p> - -<p>The Brixham cave occurs near the small village of -that name, not far from Torquay. The entrance to it is -about ninety-five feet above high water. Its deposits, in -descending order, are: 1. Stalagmitic floor from six to -twelve or fifteen inches in thickness. 2. A thin breccia -of limestone fragments cemented together by carbonate of -lime. This had accumulated about the mouth, so as to -fill up the entrance. 3. A layer of blackish earth about -one foot in thickness 4. A deposit of from two to four -feet thick, consisting of clayey loam, mingled with fragments -of limestone, from small bits up to rocks weighing -a ton. Bounded pebbles of other material were also occasionally -met with. 5. Shingle consisting of rounded pebbles -largely of foreign material.</p> - -<p>All these strata, except the third, contained fossils of -some kind, but the fourth was by far the richest repository. -Among the bones found are those of the mammoth, the -woolly rhinoceros, the horse, the ox, the reindeer, the cave-lion, -the cave-hyena, and the cave-bear. Associated with -<span class="pagenum"><a name="Page_270" id="Page_270">« 270 »</a></span> -these remains a number of worked flints was found. In -one place the bones of an entire leg of a cave-bear occurred -in such a position as to show that they must have been -bound together by the ligaments when they were buried. -Immediately below these bones a flint implement was -found.<a name="FNanchor_106" id="FNanchor_106"></a><a href="#Footnote_106" class="fnanchor">[DB]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_106" id="Footnote_106"></a><a href="#FNanchor_106"><span class="label">[DB]</span></a> See Pengelly’s Reports to the Devonshire Association, 1867.</p></div> - -<p>The hyena’s den, at Wookey Hole, near Wells, in Somerset, -was carefully explored by Professor Boyd Dawkins, -who stood by and examined every shovelful of material as -it was thrown out.</p> - -<p>This cave alone yielded 35 specimens of palæolithic -art, 467 jaws and teeth of the cave-hyena, 15 of the cave -lion, 27 of the cave-bear, 11 of the grizzly bear, 11 of the -brown bear, 7 of the wolf, 8 of the fox, 30 of the mammoth, -233 of the woolly rhinoceros, 401 of the horse, 16 of -the wild ox, 30 of the bison, 35 of the Irish elk, and 30 of -the reindeer (jaws and teeth only).</p> - -<p>In Derbyshire numerous caves were explored by Professor -Dawkins at Cress well Crags, which, in addition to -flint implements and the remains of the animals occurring -in the Brixham cave, yielded the bones of the machairodus, -an extinct species of tiger or lion which lived during the -Tertiary period.</p> - -<p>The Victoria cave, near Settle, in west Yorkshire, is -the only other one in England which we need to mention. -In this there were no remains found which could be positively -identified as human, but the animal remains in the -lower strata of the cave deposit were so different from those -in the upper bed as to indicate the great lapse of time -which separated the two. This cave is 1,450 feet above the -sea-level, and there were found in the upper strata of the -floor, down to a depth of from two to ten feet, many remains -of existing animals. Then, for a distance of twelve -feet, there occurred a clay deposit, containing no organic remains -<span class="pagenum"><a name="Page_271" id="Page_271">« 271 »</a></span> -whatever, but some well-scratched boulders. Below -this was a third stratum of earth mingled with limestone -fragments, at the base of which were numerous remains -of the mammoth, rhinoceros, hippopotamus, bison, hyena, -etc. One bone occurred which was by some supposed to -be human, but by others to have belonged to a bear. This -lower stratum is, without much doubt, preglacial, and the -thickness of the deposit intervening between it and the -upper fossiliferous bed is taken by some to indicate the -great lapse of time separating the period of the mammoth -and rhinoceros in England from the modern age. The -scratched boulders in the middle stratum of laminated -clay, would indicate certainly that the material found its -way into the cave during the Glacial epoch, when ice filled -the whole valley of the Ribble, which flows past the foot -of the hill, and whose bed is 900 feet below the mouth of -the cave.</p> - -<p>In North Wales the Vale of Clwyd contains numerous -caves which were occupied by hyenas in preglacial times -and with their bones are associated those of the mammoth, -the rhinoceros, the hippopotamus, the cave-lion, the cave-bear, -and various other animals. Flint implements also -were found in the cave at Cae Gwyn, near the village of -Tremeirchon, on the eastern side of the valley, opposite -Cefn, and about four miles distant. We have already -given an illustration of the Cefn cave (see <a href="#Page_148">page 148</a>). It -will be observed that this valley of the Clwyd opens to the -north, and has a pretty rapid descent to the sea from the -Welsh mountains, and was in position to be obstructed by -the Irish Sea glacier, so as to have been occupied at times -by one of the characteristic marginal lakes of the Glacial -period. It is evident also that the northern ice prevailed -over the Welsh ice for a considerable portion of the lower -part of the valley; for northern drift is the superficial deposit -upon the hills on the sides of the valley up to a -height of over 500 feet. From the investigations of Mr. -<span class="pagenum"><a name="Page_272" id="Page_272">« 272 »</a></span> -C. E. De Rance, F. G. S.,<a name="FNanchor_107" id="FNanchor_107"></a><a href="#Footnote_107" class="fnanchor">[DC]</a> it is equally clear also that the -northern drift, which until lately sealed up the entrance of -the cave, was subsequent to its occupation by man, and -this was the opinion formed by Sir Archibald Geikie, Director -General of the Geological Survey of the United -Kingdom, as the result of special investigations which he -made of the matter.<a name="FNanchor_108" id="FNanchor_108"></a><a href="#Footnote_108" class="fnanchor">[DD]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_107" id="Footnote_107"></a><a href="#FNanchor_107"><span class="label">[DC]</span></a> Proceedings of the Yorkshire Geological Society for 1888, pp. -1-20.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_108" id="Footnote_108"></a><a href="#FNanchor_108"><span class="label">[DD]</span></a> See De Ranee, as above, p. 17; and article by H. Hicks, in Quarterly -Journal of Geological Society, vol. xlii, p. 3; Geological Magazine, -May, 1885, p. 510.</p></div> - -<p>From the caves in the Vale of Clwyd as many as 400 -teeth of rhinoceros, 500 of horse, 180 of hyena, and 15 of -mammoth have been taken. A section of the cave deposits -in the cave at Cae Gwyn is as follows:</p> - -<p>“Below the soil for about eight feet a tolerably stiff -boulder-clay, containing many ice-scratched boulders and -narrow bands and pockets of sand. Below this about -seven feet of gravel and sand, with here and there bands -of red clay, having also many ice-scratched boulders. The -next deposit was a laminated brown clay, and under this -was found the bone-earth, a brown, sandy clay with small -pebbles and with angular fragments of limestone, stalagmites, -and stalactites. During the excavations it became -clear that the bones had been greatly disturbed by water -action; that the stalagmite floor, in parts more than a foot -in thickness, and massive stalactites, had also been broken -and thrown about in all positions; and that these had been -covered afterwards by clays and sand containing foreign -pebbles. This seemed to prove that the caverns, now 400 -feet above ordnance datum, must have been submerged -subsequently to their occupation by the animals and by -man. In Dr. Hicks’s opinion, the contents of the cavern -must have been disturbed by marine action during the -great submergence in mid-glacial times, and afterwards -<span class="pagenum"><a name="Page_273" id="Page_273">« 273 »</a></span> -covered by marine sands and by an upper boulder-clay, -identical in character with that found at many points in -the Vale of Clwyd. The paleontological evidence suggests -that the deposits in question are not preglacial, but -may be equivalent to the Pleistocene deposits of our river-valleys.”<a name="FNanchor_109" id="FNanchor_109"></a><a href="#Footnote_109" class="fnanchor">[DE]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_109" id="Footnote_109"></a><a href="#FNanchor_109"><span class="label">[DE]</span></a> H. B. Woodward’s Geology of England and Wales, pp. 543, 544</p></div> - -<p>If the views of Professor Lewis and Mr. Kendall are -correct concerning the unity of the Glacial period in England, -the shelly and sandy deposits connected with these -Clwydian caves at an elevation of 400 feet or more would -be explained in connection with the marginal lakes which -must have occupied the valley during both the advance -and the retreat of the ice-front; the shells having been -carried up from the sea-bottom by the ice-movement, after -the manner supposed in the case of those at Macclesfield -and Moel Tryfaen. If, therefore, the statements concerning -the discovery of flint implements in this Cae Gwyn -cave can be relied upon, this is the most direct evidence -yet obtained in Europe of man’s occupation of the island -during the continuance of the Glacial period.</p> - -<p>In all these caves it is to be noted that there is a sharp -line of demarcation between the strata containing palæolithic -implements and those containing only the remains -of modern animals. Palæolithic implements are confined -to the lower strata, which in some of the caves are separated -from the upper by a continuous bed of stalagmite, -to which reference will be made when discussing the -chronology of the Glacial period. The remains of extinct -animals also are confined to the lower beds.</p> - -<p>The caves which we have been considering in England -are all in limestone strata, and have been formed by -streams of water which have enlarged some natural fissures -both by mechanical action in wearing away the -rocks, and by chemical action in dissolving them. -<span class="pagenum"><a name="Page_274" id="Page_274">« 274 »</a></span> -Through the lowering of the main line of drainage, caverns -with a dry floor are at length left, offering shelter -and protection both to man and beast. Oftentimes, but -not always, some idea of the age of these caverns may be -obtained by observing the depth to which the main channel -of drainage to which they were tributary has been -lowered since their formation. But to this subject also -we will return when we come specifically to discuss the -chronological question.</p> - - -<p class="caption3nb"><i>The Continent.</i></p> - -<p>Systematic explorations in the caves of Belgium were -begun in 1833 by Dr. Schmerling, in the valley of the -Meuse, near his residence in Liége. The Meuse is here -bordered by limestone precipices 200 or more feet in -height. Opening out -from these rocky walls -are the entrances to -the numerous caverns -which have rendered -the region so famous. -To get access to the -most important of -these, Dr. Schmerling -had to let himself -down over a precipice -by a rope tied to a -tree, and then to creep -along on all-fours through intricate channels to reach the -larger chambers which it was his object to explore. In the -cave at Engis, on the left bank of the Meuse, about eight -miles above Liége, he found a human skull deeply buried -in breccia in company with many bones of the extinct animals -previously stated to have been associated with man -during the Glacial period. This so-called “Engis skull” -was by no means apelike in its character, but closely resembled -that of the average Caucasian man. But this -established the association upon the Continent of man -with some of the extinct animals of the Glacial period.</p> - -<div class="fig_right" style="width: 236px;"> -<a id="fig79" name="fig79"></a> -<img src="images/fig_79.png" width="236" height="208" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 79.</span>—Engis skull, reduced (after Lyell.)</div> -</div> - -<div class="fig_right" style="width: 250px;"> -<a id="fig80" name="fig80"></a> -<img src="images/fig_80.png" width="250" height="144" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 80.</span>—Comparison of forms of skulls: <i>a</i>, European; -<i>b</i>, the Neanderthal man; c, a chimpanzee -(after Lyell).</div> -</div> - -<p><span class="pagenum"><a name="Page_275" id="Page_275">« 275 »</a></span></p> - -<p>The vicinity of Liége has also furnished us another -cavern whose contents are of the highest importance, ranking -indeed as perhaps the most significant single discovery -yet made. The cave referred to is on the property of the -Count of Beauffort, in the commune of Spy, in the province -of Namur in Belgium. For the facts relating to it -we are indebted to Messrs: Lohest and Fraipont, the former -Professor of Geology and the latter of Anatomy in -the University of Liége. The exploration of the cave was -made in 1886, and the full report with illustrations published -in the following year in Archives de Biologie.<a name="FNanchor_110" id="FNanchor_110"></a><a href="#Footnote_110" class="fnanchor">[DF]</a> -The significance of this discovery is enhanced by the -light it sheds upon and the confirmation it brings to the -famous Neanderthal skull and others of similar character, -which for a long time had been subjects of vigorous discussion. -Before describing it, therefore, we will give a -brief account of the previous discoveries.</p> - -<div class="footnote"> - -<p><a name="Footnote_110" id="Footnote_110"></a><a href="#FNanchor_110"><span class="label">[DF]</span></a> See pp. 587, 757.</p></div> - -<p>The famous Neanderthal skull was brought to light in -1857 by workmen in a limestone-quarry, near Düsseldorf, -in the valley of the Neander, a small tributary to the -Rhine. By these workmen a cavern was opened upon the -southern side of the winding ravine, about sixty feet above -the stream and one hundred feet below the top of the cliff. -The skull attracted much attention from its supposed possession -of many apelike characteristics; indeed, it was -represented by some to be a real intermediate link between -man and the anthropoid apes. The accompanying cut -enables one to compare the outline of the Neanderthal -skull with that of a chimpanzee on the one hand and of -the highly developed European on the other. The apelike -peculiarities of this skull appear in its vertical depression, -<span class="pagenum"><a name="Page_276" id="Page_276">« 276 »</a></span> -in the enormous thickness of the bony ridges just -above the eyes, and in the gradual slope of the back part -of the head, together with some other characteristics which -can only be described in technical language; so that it was -pronounced by the -highest authorities -the most apelike of -human crania which -had yet been discovered. -Unfortunately, -the jaw was not -found. The capacity -of the skull, however, -was seventy-five -cubic inches, -which is far above that of the highest of the apes, being -indeed equal to the average capacity of Polynesian and -Hottentot skulls.<a name="FNanchor_111" id="FNanchor_111"></a><a href="#Footnote_111" class="fnanchor">[DG]</a> Huxley well remarks that “so large a -mass of brain as this would alone suggest that the pithecoid -tendencies indicated by this skull did not extend deep into -the organization.”</p> - -<div class="footnote"> - -<p><a name="Footnote_111" id="Footnote_111"></a><a href="#FNanchor_111"><span class="label">[DG]</span></a> Huxley’s Man’s Place in Nature, p. 181.</p></div> - -<div class="fig_right" style="width: 307px;"> -<a id="fig81" name="fig81"></a> -<img src="images/fig_81.png" width="307" height="336" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 81.</span>—Skull of the Man of Spy. (From photograph.)</div> -</div> - -<p>Upon extending inquiries, it was found that the Neanderthal -type of skull is one which still has representatives -in all nations; so that it is unsafe to infer that the individual -was a representative of all the individuals living in his -time. The skull of Bruce, the celebrated Scotch hero, -was a close reproduction of the Neanderthal type; while, -according to Quatrefages,<a name="FNanchor_112" id="FNanchor_112"></a><a href="#Footnote_112" class="fnanchor">[DH]</a> the skull of the Bishop of -Toul in the fourth century “even exaggerates some of the -most striking features of the Neanderthal cranium. The -forehead is still more receding, the vault more depressed, -and the head so long that the cephalic index is 69-41.” -The discovery of Messrs. Fraipont and Lohest adds -<span class="pagenum"><a name="Page_277" id="Page_277">« 277 »</a></span> -much to our definite knowledge of the Neanderthal type of -man, since the Belgic specimens are far more complete than -any others heretofore found, there being in their collection -two skulls, together with the jawbones and most of the -other parts of the frame. In this case also there is no suspicion -that the deposits had been disturbed, so as to admit -any intrusion of human relics into the company of relics of -an earlier age. According to M, Lohest, there were three -distinct ossiferous beds, separated by layers of stalagmite. -All the ossiferous beds contained the remains of the -mammoth, but in the upper stratum they were few, and -probably intrusive. The implements found in this were -also of a more modern type. In the second stratum from -the top numerous hearths were found with burnt wood -and ashes, together with the bones of the rhinoceros, the -<span class="pagenum"><a name="Page_278" id="Page_278">« 278 »</a></span> -horse, the mammoth, the cave-bear, and the cave-hyena, -all of which were abundant, while there were also specimens -of the Irish elk, the reindeer, the bison, the cave-lion, -and several other species. In this layer also there were -numerous implements of ivory, together with ornaments -and some faint indications of carving upon the rib of a -mammoth, besides a few fragments of pottery.</p> - -<div class="footnote"> - -<p><a name="Footnote_112" id="Footnote_112"></a><a href="#FNanchor_112"><span class="label">[DH]</span></a> Human Species, p. 310,</p></div> - -<p>It was in the third, or lowest, of these beds that the -skeletons were found. Here they were associated with -abundant remains of the rhinoceros, the horse, the bison, -the mastodon, the cave-hyena, and a few other extinct -species. Flint implements also, of the “Mousterien” -pattern (which, according to the opinion of the French -archæologists, is characteristic of middle palæolithic times), -were abundant Neither of the skeletons was complete, -but they were sufficiently so to give an adequate -idea of the type to which they belong, and one of the -skulls is nearly perfect. According to M. Fraipont, “one -of these skulls is apparently that of an old woman, the -other that of a middle-aged man. They are both very -thick; the former is clearly dolichocephalic (long-headed, -index 70), the other less so. Both have very prominent -eyebrows and large orbits, with low, retreating foreheads, -excessively so in the woman. The lower jaws are heavy. -The older has almost no projecting chin. The teeth are -large, and the last molar is as large as the others. These -points are characteristic of an inferior and the oldest-known -race. The bones indicate, like those of the Neanderthal -and Naulette specimens, small, square-shouldered -individuals.” They were “powerfully built, with -strong, curiously curved thigh-bones, the lower ends of -which are so fashioned that they must have walked with -a bend at the knees.” <a name="FNanchor_113" id="FNanchor_113"></a><a href="#Footnote_113" class="fnanchor">[DI]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_113" id="Footnote_113"></a><a href="#FNanchor_113"><span class="label">[DI]</span></a> Huxley, Nineteenth Century, vol. xxviii (November, 1890), -p. 774.</p> - -<p><span class="pagenum"><a name="Page_279" id="Page_279">« 279 »</a></span></p></div> - -<p>Other crania from various Quaternary deposits in Europe -seem to warrant the inference that this type of man -was the prevalent one during the early part of the Palæolithic -age. As long ago as 1700 a skull of this type was -exhumed in Canstadt, a village in the neighbourhood of -Stuttgart, in Würtemberg. This was found in coexistence -with the extinct animals whose bones we have described -as so often appearing in the high-level river-gravel -of the Glacial age. But the importance of the discovery -at Canstadt was not appreciated until about the middle of -the present century. From the priority of the discovery, -and of the discussion among German anthropologists concerning -it, it has been thought proper, however, by some -to give the name of this village to the race and call it the -“Canstadt race.” But, whatever name prevails, it is important -in our reading to keep in mind that the man of -Canstadt, the man of Neanderthal, and the man of Spy -are identical in type, and probably in age. Similar discoveries -have been made in various other places. Among -these are a lower jaw of the same type discovered in -1865 by M. Dupont, at Naulette, in the valley of the Lesse, -in Belgium, and associated with the remains of extinct -animals; a jawbone found in a grotto at Arcy; a fragment -of a skull found in 1865 by Faudel, in the loess of -Eguisheim, near Colmar; a skull at Olmo, discovered in -1863, in a compact clayey deposit forty-five feet below -the surface; and a skull discovered in 1884 at Marcilly.</p> - -<p>M. Dupont has brought to light much additional testimony -to glacial man from other caves in different parts of -Belgium. In all he has explored as many as sixty. Three -of these, in the valley of the Montaigle, situated about -one hundred feet above the river, contained both remains -of man and many bones of the mammoth and other -associated animals, which had evidently been brought in -for food.</p> - -<p>In the hilly parts of Germany, also, and in Hungary, -<span class="pagenum"><a name="Page_280" id="Page_280">« 280 »</a></span> -and even in the Ural Mountains in Russia, and in one of -the provinces of Siberia, the remains of the rhinoceros, -and most of the other animals associated with man in -glacial times, have been found in the cave deposits which -have been examined. Though it can not be directly -proved that these animals were associated with man in -any of these places, still it is interesting to see how wide-spread -the animals were in northern Europe and Asia -during the Glacial period.</p> - -<p>Some northern animals, also, spread at this time into -southern Europe—remains of the reindeer having been -discovered on the south slope of the Pyrenees, but the -remains of the mammoth, the woolly rhinoceros, and the -musk ox, have not been found so far south.</p> - -<p>African species of the elephant, however, seem at one -time to have had free range throughout Spain, and the -hippopotamus roamed in vast herds over the valleys of -Sicily, while several species of pygmy elephants seem to be -peculiar to the island of Malta.</p> - -<p>In the case of all the cave deposits referred to (with -possibly the exception of those of Victoria, England, and -Cae Gwyn, Wales), the evidence of man’s existence during -the Glacial period is inferential, and consists largely -in the fact that he was associated with various extinct -animals which did not long survive that period, or with -animals that have since retired from Europe to their -natural habitat in mountain-heights or high latitudes. -The men whose remains are found in the high-level river-drift, -and in the caverns described, were evidently not in -possession of domestic animals, as their bones are conspicuous -for their absence in all these places. The horse, -which would seem to be an exception, was doubtless used -for food, and not for service.</p> - -<p>If we were writing upon the general subject of the -antiquity and development of the human race, we should -speak here in detail of several other caves and rock shelters -<span class="pagenum"><a name="Page_281" id="Page_281">« 281 »</a></span> -in France and southern Europe, where remains of -man belonging to an earlier period have been found. We -should mention the rock shelter of Cro-Magnon in the -valley of Vezère, as well as that of Mentone, where entire -human skeletons were found. But it is doubtful if these -and other remains from caves which might be mentioned -belong in any proper sense to the Glacial period. The -same remarks should be made also with reference to the -lake-dwellings in Switzerland, of which so much has been -written in late years. All these belong to a much later -age than the river-drift man of whom we are speaking, -and of whom we have such abundant evidence both in -Europe and in America.</p> - -<div class="fig_center" style="width: 450px;"> - <a id="fig82" name="fig82"></a> - <a id="fig83" name="fig83"></a> - <img src="images/fig_82-83.png" width="354" height="212" alt="" /> - <div class="fig_caption"><span class="smcap">Fig. 82.</span>—Tooth of Machairodus neogæus, - × <span class="horsplit"><span class="top">1</span><span class="bottom trt">6</span></span> (drawn from a cast).<br /> - <span class="smcap">Fig. 83.</span>—Perfect tooth of an Elephas, - found in Stanislaus County, California, - <span class="horsplit"><span class="top">1</span><span class="bottom trt">8</span></span> natural size.</div> -</div> - -<p class="caption3nb pmt2"><i>Extinct Animals associated with Man during the Glacial -Period.</i></p> - -<p>This is the proper place in which to speak more fully -of the extinct animals which accompanied man in his -earliest occupation of Europe and America, and whose -remains are so abundant in the river-drift gravel and in -the caves of England, in connection with the relics of -man. Among these animals are</p> - -<p><span class="pagenum"><a name="Page_282" id="Page_282">« 282 »</a></span></p> - -<p>The Lion, which is now confined, to Africa and the -warmer portions of Asia. But in glacial times a large -species of this genus ranged over Europe from Sicily to -central England.</p> - -<p>The saber-toothed Tiger, with tusks ten inches long: -(Machairodus latidens), is now extinct. This species was -in existence during the latter part of the Tertiary period, -but continued on until after man’s appearance in the -Glacial period. The presence of this animal would seem -to indicate a warm climate.</p> - -<p>The Leopard (<i>Felis pardus</i>) is now confined to Africa -and southern Asia, and the larger islands adjoining; but -during man’s occupation of Europe in the Glacial epoch -he was evidently haunted at every step by this animal; -for his bones are found as far north in England as -palæolithic man is known to have ranged.</p> - -<p>The Hyena. Two species of this animal are found -in the bone-caves of Europe. During the Glacial epoch -they ranged as far up as northern England, but they are -now limited to Africa and southwestern Asia.</p> - -<div class="fig_center" style="width: 339px;"> -<a id="fig84" name="fig84"></a> -<img src="images/fig_84.png" width="339" height="183" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 84.</span>—Skull of <i>Hyena spelæa</i>, × <span class="horsplit"><span class="top">1</span><span class="bottom trt">4</span></span>.</div> -</div> - -<p>The Elephant is represented in the Preglacial and -Glacial epochs by several species, some of which ranged -as far north as Siberia. The African elephant is not now -found north of the Pyrenees and the Alps. But a species of -<span class="pagenum"><a name="Page_283" id="Page_283">« 283 »</a></span> -dwarf elephant, but four or five feet in height, has already -been referred to as having occupied Malta and Sicily; and -still another species has been found in Malta, whose average -height was less than three feet. An extinct species -(Elephas antiquus), whose remains are found in the river-drift -and in the lower strata of sediment in many caverns -as far north as Yorkshire, England, was of unusual size, -and during the Glacial period was found on both sides -of the Mediterranean. But the species most frequently -met with in palæolithic times was the mammoth (<i>Elephas -primigenius</i>). This animal, now extinct, accompanied -man in nearly every portion both of Europe and -North America, and lingered far down into post-glacial -times before becoming extinct. This animal was nearly -twice the weight of the modern elephant, and one third -taller. Occasionally his tusks were more than twelve -feet long, and curved upward in a circle. It is the carcasses -of this animal which have been found in the frozen -soil of Siberia and Alaska. It had a thick covering of -long, black hair, with a dense matting of reddish wool at -the roots. During the Glacial period these animals must -have roamed in vast herds over the plains of northern -France and southern England, and the northern half of -North America.</p> - -<div class="fig_center" style="width: 319px;"> -<a id="fig85" name="fig85"></a> -<img src="images/fig_85.png" width="319" height="204" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 85.</span>—Celebrated skeleton of mammoth, in St. Petersburg museum.</div> -</div> - -<p><span class="pagenum"><a name="Page_284" id="Page_284">« 284 »</a></span></p> - -<div class="fig_center" style="width: 347px;"> -<a id="fig86" name="fig86"></a> -<img src="images/fig_86.png" width="347" height="253" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 86.</span>—Molar tooth of mammoth (<i>Elephas primigenius</i>): <i>a</i>, grinding surface; -<i>b</i>, side view.</div> -</div> - -<p>The Hippopotamus is at present a familiar animal -in the larger rivers of Africa, but is not now found in -Europe. During the Glacial period, however, he ranged -as far north as Yorkshire, England, and his remains were -found in close association with those of man, both in -Europe and on the Pacific -coast in America. Twenty -tons of their bones have been -taken from a single cave in -Sicily.<a name="FNanchor_114" id="FNanchor_114"></a><a href="#Footnote_114" class="fnanchor">[DJ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_114" id="Footnote_114"></a><a href="#FNanchor_114"><span class="label">[DJ]</span></a> Prestwich’s Geology, vol. ii, p. 508.</p></div> - -<div class="fig_left" style="width: 192px;"> -<a id="fig87" name="fig87"></a> -<img src="images/fig_87.png" width="192" height="137" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 87.</span>—Tooth of <i>Mastodon -Americanus</i>.</div> -</div> - -<p>The mammoth and the -rhinoceros we know to have -been adapted to cold climates -by the possession of -long hair and thick fur, but -the hippopotamus by its love for water would seem to -be precluded from the possession of this protective covering. -<span class="pagenum"><a name="Page_285" id="Page_285">« 285 »</a></span> -It is suggested, however, by Sir William Dawson, -that he may have been adapted to arctic climates -by a fatty covering, as the walrus is at the present time. -A difficulty in accounting for many of the remains of -the hippopotamus in some of the English caverns is -that they are so far away from present or possible -water-courses. But it would seem that due credit has -not been ordinarily given to the migratory instincts -of the animal. In southern Africa they are known to -“travel speedily for miles over land from one pool of a -dried-up river to another; but it is by water that their -powers of locomotion are surpassingly great, not only in -rivers, but in the sea.... The geologist, therefore, may -freely speculate on the time when herds of hippopotami -issued from North African rivers, such as the Nile, and -swam northward in summer along the coasts of the Mediterranean, -or even occasionally visited islands near the -shore. Here and there they may have landed to graze -or browse, tarrying awhile, and afterwards continuing their -course northward. Others may have swum in a few summer -days from rivers in the south of Spain or France to -the Somme, Thames, or Severn, making timely retreat to -the south before the snow and ice set in.” <a name="FNanchor_115" id="FNanchor_115"></a><a href="#Footnote_115" class="fnanchor">[DK]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_115" id="Footnote_115"></a><a href="#FNanchor_115"><span class="label">[DK]</span></a> Lyell, Antiquity of Man, p. 180,</p></div> - -<p>The Mastodon (<i>Mastodon Americanus</i>), (<a href="#fig88">Fig. 88</a>), -“is probably the largest land mammal known, unless we -except the Dinotherium. It was twelve to thirteen feet -high, and, including the tusks, twenty-four to twenty-five -feet long. It differed from the elephant chiefly in the -character of its teeth. The difference is seen in Figs. 86 -and 87. The elephant’s tooth given above (<a href="#fig86">Fig. 86</a>) is -sixteen inches long, and the grinding surface eight inches -by four.”</p> - -<p><span class="pagenum"><a name="Page_286" id="Page_286">« 286 »</a></span></p> - -<div class="fig_center" style="width: 396px;"> -<a id="fig88" name="fig88"></a> -<img src="images/fig_88.png" width="396" height="334" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 88.</span>—<i>Mastodon Americanus</i> (after Owen).</div> -</div> - -<p>The mastodon, together with the mammoth, made -their appearance about the middle of the Miocene epoch. -At the close of the Tertiary period the mastodon became -extinct on the Eastern Continent, but continued in North -America to be a companion of man well on toward the -close of the Glacial period. Many perfect skeletons have -been found in the deposits of this period in North America. -“One magnificent specimen was found in a marsh -near Newburg, New York, with its legs bent under the -body, and the head thrown up, evidently in the very position -in which it mired. The teeth were still filled with -the half-chewed remnants of its food, which consisted of -twigs of spruce, fir, and other trees; and within the ribs, -in the place where the stomach had been, a large quantity -of similar material was found.”<a name="FNanchor_116" id="FNanchor_116"></a><a href="#Footnote_116" class="fnanchor">[DL]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_116" id="Footnote_116"></a><a href="#FNanchor_116"><span class="label">[DL]</span></a> Le Conte’s Geology (edition of 1891), p. 582.</p></div> - -<div class="fig_right" style="width: 179px;"> -<a id="fig89" name="fig89"></a> -<img src="images/fig_89.png" width="179" height="108" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 89.</span>—Skeleton of <i>Rhinoceros -tichorhinus</i>.</div> -</div> - -<p>The Rhinoceros is now confined to Africa and southern -<span class="pagenum"><a name="Page_287" id="Page_287">« 287 »</a></span> -Asia; but the remains of four species have been found -in America, Europe, and northern Asia, in deposits of -the Glacial period. In company with that of the mammoth, -already spoken of, a carcass of the woolly rhinoceros -was found in 1771 in the -frozen soil of northern Siberia. -The bones of other -species have been found as -far north as Yorkshire, England. -In the valley of the -Somme there was found “the -whole hind limb of a rhinoceros, -the bones of which were still in their true relative position. -They must have been joined together by ligaments -and even surrounded by muscles at the time of their interment.” -An entire skeleton was found near by. The gravel -terrace in which these occurred is about forty feet above -the floor of the valley, and must have been formed subsequent -to some of the strata which contained the remains -of human art. In America the bones are found in the -gold-bearing gravels of California, in connection with human -remains.</p> - -<div class="fig_right" style="width: 372px;"> -<a id="fig90" name="fig90"></a> -<img src="images/fig_90.png" width="372" height="200" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 90.</span>—Skull of cave-bear (<i>Ursus spelæus</i>),</div> -</div> - -<p>The Bear was represented in Europe in palæolithic -times by three species, of which only one exists there at -<span class="pagenum"><a name="Page_288" id="Page_288">« 288 »</a></span> -the present time. But during the Glacial period the -grizzly bear, now confined to the western part of America, -and the extinct cave-bear were companions, or enemies as -the case may be, of man throughout Europe. The cave-bear -was of large size, and his bones occur almost everywhere -in the lower strata of sediment in the caves of England.</p> - -<p>The Great Irish Elk, or deer, is now extinct, though -it is supposed by some to -have lingered until historic -times. Its remains -are found widely distributed -over middle Europe -in deposits of palæolithic -age.</p> - -<div class="fig_left" style="width: 205px;"> -<a id="fig91" name="fig91"></a> -<img src="images/fig_91.png" width="205" height="218" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 91.</span>—Skeleton of the Irish elk (<i>Cervus megaceros</i>).</div> -</div> - -<p>The Horse was also, -as we have seen, a very -constant associate of man -in middle Europe during -the Palæolithic age, but -probably not as a domesticated -animal. The evidence -is pretty conclusive -that he was prized chiefly for food. About some of the -caves in France such immense quantities of their bones -are found that they can be accounted for best as refuse-heaps -into which the useless bones had been thrown -after their feasts, after the manner of the disposal of -shells of shell-fish. In America the horses associated -with man were probably of a species now extinct. The -skull of one (<i>Equus excelsus</i>) recently found in Texas, -in Pleistocene deposits, associated with human implements, -is, according to Cope, intermediate in character -between the horse and quagga.<a name="FNanchor_117" id="FNanchor_117"></a><a href="#Footnote_117" class="fnanchor">[DM]</a> The frontal bone was -crushed in in a manner to suggest that it had been knocked -<span class="pagenum"><a name="Page_289" id="Page_289">« 289 »</a></span> -in the head with a stone hammer, such as was found in -the same bed. Possibly, therefore, man’s love of horse-flesh -may have been an important element in securing the -extinction of the species in America.</p> - -<div class="footnote"> - -<p><a name="Footnote_117" id="Footnote_117"></a><a href="#FNanchor_117"><span class="label">[DM]</span></a> American Naturalist, vol. xxv (October, 1891), p. 912.</p></div> - -<p>Besides these animals there were associated with man -at this time the Musk Sheep and the Reindeer, both -now confined to the regions of the far north, but during -the Glacial period ranging into southern France, and -mingling their bones with those both of man and of the -southern species already enumerated.</p> - -<div class="fig_center" style="width: 375px;"> -<a id="fig92" name="fig92"></a> -<img src="images/fig_92.png" width="375" height="226" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 92.</span>—Musk-sheep (<i>Ovibos moschatius</i>).</div> -</div> - -<p>The Wolverine, the Arctic Fox, the Marmot, the -Lemming—all now confined to colder regions—at that -time mingled on the plains of central Europe with the -species mentioned as belonging now to Africa and southern -Asia. The Ibex, also, and the Snowy Vole and Chamois -descended to the plains from their mountain-heights, -and joined in the strange companionship of animals from -the north and from the south.</p> - -<p>Besides these extremes there were associated with man -during the Glacial period numerous representatives of the -temperate group of existing animals, such as the bison, -the horse, the stag, the beaver, the hare, the rabbit, the -<span class="pagenum"><a name="Page_290" id="Page_290">« 290 »</a></span> -otter, the weasel, the wild-cat, the fox, the wolf, the wild -boar, and the brown bear.</p> - -<div class="fig_left" style="width: 194px;"> -<a id="fig93" name="fig93"></a> -<img src="images/fig_93.png" width="194" height="149" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 93.</span>—Reindeer.</div> -</div> - -<p>To account for this strange intermingling of arctic and -torrid species of animals, especially in Europe, during man’s -occupancy of the region in glacial times, various theories -have been resorted to, but none of them can be said to be -altogether satisfactory. One hypothesis is that the bones -of these diverse animals -became mingled by reason -of the great range of the -annual migration of the -species. The reindeer, for -example, still performs extensive -annual migrations. -In summer it ventures far -out upon the <i>tundras</i> of -North America and Siberia -to feed upon the abundant vegetation that springs up like -magic under the influence of the long days of sunshine; -while, as winter approaches, it returns to the forests of the -interior. Or in other places this animal and his associates, -like birds of passage, move northward in summer to escape -the heat, and southward in the winter to escape the extreme -cold. Many of the other animals also are more or -less migratory in their habits.</p> - -<p>Thus it is thought that during the Glacial period, when -man occupied northern France and southern England, -the reindeer, the musk sheep, the arctic fox, and perhaps -the hippopotamus and some other animals, annually -vibrated between northern England and southern France, -a slight elevation of the region furnishing a land passage -from England to the continent; while the chamois and -other Alpine species vibrated as regularly between the valleys -in winter and the mountain-heights in summer. The -habits of these species are such that it is not difficult to see -how in their case this migration could have taken place.</p> - -<p><span class="pagenum"><a name="Page_291" id="Page_291">« 291 »</a></span></p> - -<p>Professor Boyd Dawkins attempts to reduce the difficulty -by supposing that the Glacial epoch was marked by -the occurrence of minor periods of climatic variation, during -which, in comparatively short periods, the isothermal -lines vibrated from north to south, and <i>vice versa</i>. In this -view the southern species gradually crowded upon the -northern during the periods of climatic amelioration, -until they reached their limit in central England, and -then in turn, as the climate became more rigorous, slowly -retreated before the pressure of their northern competitors. -Meanwhile the hyena sallied forth from his various caves, -over this region, at one time of the year to feed upon the -reindeer, and at another time of the year upon the flesh -of the hippopotamus, in both cases dragging their bones -with him to his sheltered retreat in the limestone caverns<a name="FNanchor_118" id="FNanchor_118"></a><a href="#Footnote_118" class="fnanchor">[DN]</a> -which he shared at intervals with palæolithic man.</p> - -<div class="footnote"> - -<p><a name="Footnote_118" id="Footnote_118"></a><a href="#FNanchor_118"><span class="label">[DN]</span></a> Early Man in Britain, p. 114.</p></div> - -<p>The theory of Mr. James Geikie is that the period, -while one of great precipitation, was characterised by a -climate of comparatively even temperature, in which there -was not so great a difference as now between the winters -and the summers, the winters not being so cold and the -summers not so hot as at present. This is substantially -the condition of things in southern Alaska at the present -time, where extensive glaciers come down to the sea-level, -even though the thermometer at Sitka rarely goes below -zero (Fahrenheit). It is, therefore, easy to conceive that -if there were extensive plains bordering the Alaskan archipelago, -so as to furnish ranging grounds for more southern -species, the animals of the north and the animals of -the south might partially occupy the same belt of territory, -and their bones become mingled in the same river -deposits.</p> - -<p>In order to clear the way for either of these hypotheses -to account for the mingling of arctic and torrid species -<span class="pagenum"><a name="Page_292" id="Page_292">« 292 »</a></span> -characteristic of the period under consideration in Europe, -we must probably suppose such an elevation of the region -to the south as to afford land connection between Europe -and Africa. This would be furnished by only a moderate -amount of elevation across the Strait of Gibraltar and -from the south of Italy to the opposite shore in Africa; -and there are many indications, in the distribution of -species, of the existence in late geological times of such -connection.</p> - -<p>It should also be observed that the present capacities -and habits of species are not a certain criterion of their -past habits and capacities. As already remarked, both the -rhinoceros and the mammoth of glacial times were probably -furnished with a woolly protection, which enabled -them to endure more cold than their present descendants -could do, while the elephant is even now known to be able -to endure the rigors of the climate at great elevations upon -the Himalaya Mountains. We can easily imagine these -species to have been adjusted to quite different climatic -conditions from those which now seem necessary to their -existence. In the case of the hippopotamus, also, it is -quite possible, as already suggested, that it is more inclined -to migration than is generally supposed.</p> - -<p>Geikie’s theory of the prevalence of an equable climate -during a portion of the Glacial period in Europe is -thought to be further sustained by the character of the -vegetation which then covered the region, as well as by -the remains of the mollusks which occupied the waters. -Then “temperate and southern species like the ash, the -poplar, the sycamore, the fig-tree, the Judas-tree, the -laurel, etc., overspread all the low ground of France, as -far north at least as Paris.... It was under such conditions,” -continues Geikie, "that the elephants, rhinoceroses, -and hippopotamuses, and the vast herds of temperate -cervine and bovine species ranged over Europe, from the -shores of the Mediterranean up to the latitude of Yorkshire, -<span class="pagenum"><a name="Page_293" id="Page_293">« 293 »</a></span> -and probably even farther north still; and from the -borders of Asia to the Western Ocean. Despite the presence -of numerous fierce carnivora—lions, hyenas, tigers, -and others—Europe at that time, with its shady forests, -its laurel-margined streams, its broad and deep-flowing -rivers, a country in every way suited to the needs of a -race of hunters and fishers—must have been no unpleasant -habitation for palæolithic man.</p> - -<p>“This, however, is only one side of the picture. There -was a time when the climate of Pleistocene Europe presented -the strongest contrast to those genial conditions—a -time when the dwarf birch of the Scottish Highlands, -and the arctic willow, with their northern congeners, grew -upon the low grounds of middle Europe. Arctic animals, -such as the musk sheep and the reindeer, lived then, all -the year round, in the south of France; the mammoth -ranged into Spain and Italy; the glutton descended to -the shores of the Mediterranean; the marmot came down -to the low grounds at the foot of the Apennines; and the -lagomys inhabited the low-lying maritime districts of -Corsica and Sardinia. The land and fresh-water shells of -many Pleistocene deposits tell a similar tale; boreal, high -alpine, and hyperborean forms are characteristic of these -accumulations in central Europe; even in the southern -regions of our continent the shells testify to a former -colder and wetter climate.”<a name="FNanchor_119" id="FNanchor_119"></a><a href="#Footnote_119" class="fnanchor">[DO]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_119" id="Footnote_119"></a><a href="#FNanchor_119"><span class="label">[DO]</span></a> Prehistoric Europe, p. 67.</p></div> - -<p>In Mr. Geikie’s view these facts indicate two Glacial -periods, with an intervening epoch of mild climate. In -the opinion of others they are readily explainable by the -coming on and departure of a single Ice age, with its various -minor episodes.</p> - -<p><span class="pagenum"><a name="Page_294" id="Page_294">« 294 »</a></span></p> - - -<p class="caption3nb"><i>Earliest Remains of Man on the Pacific Coast of North -America.</i></p> - -<p>Most interesting evidence concerning the antiquity of -man in America, and his relation to the Glacial period, -has come from the Pacific coast. During the height of -the mining activity in California, from 1850 to 1860, -numerous reports were rife that human remains had been -discovered in the gold-bearing gravel upon the flanks of -the Sierra Nevada Mountains. These reports did not -attract much scientific attention until they came to relate -to the gravel deposits found deeply buried beneath a flow -of lava locally known as the Sonora or Tuolumne Table -Mountain. This lava issued from a vent near the summit -of the mountain-range, and flowed down the valley of the -Stanislaus River for a distance of fifty or sixty miles, -burying everything in the valley beneath it, and compelling -the river to seek another channel. The thickness of -the lava averages about one hundred feet, and so long a -time has elapsed since the eruption that the softer strata -on either side of the valley down which it flowed have -been worn away to such an extent that the lava now rises -nearly everywhere above the general level, and has become -a striking feature in the landscape, stretching for many -miles as a flat-topped ridge about half a mile in width, -and presenting upon the sides a perpendicular face of -solid basalt for a considerable distance near the lower end -of the flow.</p> - -<div class="fig_center" style="width: 440px;"> -<a id="fig94" name="fig94"></a> -<img src="images/fig_94.png" width="440" height="107" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 94.</span>—Section across Table Mountain, Tuolumne County, California: <i>L</i>, -lava; <i>G</i>, gravel; <i>S</i>, slate; <i>R</i>, old river-bed; <i>R′</i>, present river-bed.</div> -</div> - -<p><span class="pagenum"><a name="Page_295" id="Page_295">« 295 »</a></span></p> - -<div class="fig_center" style="width: 513px;"> -<a id="fig95" name="fig95"></a> -<img src="images/fig_95.png" width="513" height="271" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 95.</span>—Calaveras Skull. (From Whitney.)</div> -</div> - -<p>It was under this mountain of lava that the numerous -implements and remains of man occurred which were -reported to Professor J. D. Whitney when he was conducting -the geological survey of California between 1860 -and 1870. The implements consisted of stone mortars -and pestles, suitable for use in grinding acorns and other -coarse articles of food. There were, however, some rude -articles of ornament. In one of the mining shafts penetrating -<span class="pagenum"><a name="Page_296" id="Page_296">« 296 »</a></span> -the gravel underneath Table Mountain, near -Sonora, there was reported to have been discovered, in -1857, a human jawbone, one portion of which was sent by -responsible parties to the Boston Society of Natural History, -and another part to the Philadelphia Academy of -Sciences, in whose collections the fragments can now be -seen.</p> - -<p>Interest reached a still higher pitch when, in 1860, an -entire human skull with some other human bones was -reported to have been discovered under this same lava -deposit, a few miles from Sonora, at Altaville, in Calaveras -County, and hence known as the “Calaveras skull.” Persistent -efforts were made soon after to discredit the -genuineness of this discovery. Bret Harte showered upon -it the shafts of his ridicule, and various other persons gave -currency to the story that the whole report originated in -a joke played by the miners upon unsuspecting geologists. -These attacks were so successful that many conservative -archæologists and men of science have refused to accept -the skull as genuine.</p> - -<p>Recent events, however, have brought such additional -evidence<a name="FNanchor_120" id="FNanchor_120"></a><a href="#Footnote_120" class="fnanchor">[DP]</a> to the support of this discovery that it would -seem unreasonable any longer to refuse to credit the testimony. -At the meeting of the Geological Society of -America, at Washington, in January, 1891, Mr. George P. -Becker, of the United States Geological Survey, who for -some years has had charge of investigations relating to -the gold-bearing gravels of the Pacific coast, presented -the affidavit of Mr. J. H. Neale, a well-known mining -engineer of unquestionable character, stating that he had -taken a stone mortar and pestle, together with some spear-heads -(which through Mr. Becker he presented to the -Society), from undisturbed strata of gravel underneath -the lava of Table Mountain, near Rawhide Gulch, a few -<span class="pagenum"><a name="Page_297" id="Page_297">« 297 »</a></span> -miles from Sonora. At the same meeting Mr. Becker -presented a pestle which Mr. Clarence King, the first -director of the United States Geological Survey, took with -his own hands out of undisturbed gravel under this same -lava deposit, near Tuttletown, a mile or two from the preceding -locality mentioned.</p> - -<div class="footnote"> - -<p><a name="Footnote_120" id="Footnote_120"></a><a href="#FNanchor_120"><span class="label">[DP]</span></a> See Bulletin Geological Society of America, 1891, pp. 189-200.</p></div> - -<p>I was so fortunate, also, as to be able to report to -the Society at the same meeting the discovery, in 1887, -of a small stone mortar by Mr. C. McTarnahan, the assistant -surveyor of Tuolumne County. This mortar was -found by Mr. McTarnahan in the Empire mine, which -penetrates the gravel underneath Table Mountain, about -three miles from Sonora, and not far from the other localities -above mentioned. The place where the mortar was -found is about one hundred and seventy-five feet in from -the edge of the superincumbent lava, which is here about -one hundred feet in thickness. At my request, this mortar -was presented by its owner, Mrs. M. J. Darwin, to the -Western Reserve Historical Society of Cleveland, Ohio, -in whose collection it can now be seen.</p> - -<p>These three independent instances, each of them authenticated -by the best of evidence, have such cumulative -force that probably few men of science will longer stand -out against it.</p> - -<p>Associated with these discoveries, there is to be mentioned -another, which was brought to my notice by Mr. -Charles Francis Adams in October, 1889.<a name="FNanchor_121" id="FNanchor_121"></a><a href="#Footnote_121" class="fnanchor">[DQ]</a> This was a -miniature clay image of a female form, about one inch -and a half in length, and beautifully formed, which was -found, in August, 1889, by Mr. M. A. Kurtz, while boring -an artesian well at Nampa, Ada County, Idaho. The -strata passed through included, near the surface, fifteen -feet of lava. Underneath this, alternating beds of clay and -<span class="pagenum"><a name="Page_298" id="Page_298">« 298 »</a></span> -quicksand occurred to a depth of three hundred and -twenty feet, where there appeared indications of a former -surface soil lying just above the bed-rock, from which -the clay image was brought up in the sand-pump.</p> - -<div class="footnote"> - -<p><a name="Footnote_121" id="Footnote_121"></a><a href="#FNanchor_121"><span class="label">[DQ]</span></a> See Proceedings Boston Society Natural History, January, 1890, -and February, 1891.</p></div> - -<div class="fig_center" style="width: 337px;"> -<a id="fig96" name="fig96"></a> -<img src="images/fig_96.png" width="337" height="184" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 96.</span>—Three views of Nampa image drawn to scale. The middle one is from -a photograph.</div> -</div> - -<p>I devoted the summer of 1890 to a careful study of -the lava deposits both in Idaho and in California, with a -view to learning their significance with reference to these -discoveries. The main facts brought to light by this -investigation are that in the Snake River Valley, Idaho, -there are not far from twelve thousand square miles of -territory covered with a continuous stratum of basaltic -lava, extending nearly across the entire diameter of the -State from east to west. Nampa, where the miniature -image was discovered, is within five miles of the western -limit of this lava-flow, and where it had greatly thinned -out. The relative age of the lava is shown by its relation -to Tertiary beds of shale and sandstone, containing numerous -fossils of late Pliocene species. These are overlaid in -this vicinity by the lava, thus determining its post-Tertiary -character. Examination with reference to the more -precise determination of age reveals channels of erosion -formed since the lava-flow took place, which, when studied -sufficiently, will probably lead to valuable approximate -<span class="pagenum"><a name="Page_299" id="Page_299">« 299 »</a></span> -results. At present I can only say that the amount of -erosion since the lava eruptions of western Idaho is not -excessive, and very likely may be brought within a period -of from ten thousand to twenty thousand years. The -enormous erosion in the cañon of the Snake River, near -Shoshone Falls, in central Idaho, is doubtless of a much -earlier date than that in the Boise River, near Nampa.</p> - -<div class="fig_center" style="width: 271px;"> -<a id="fig97" name="fig97"></a> -<img src="images/fig_97.png" width="271" height="212" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 97.</span>—Map showing Pocatello, Nampa, and the valley of Snake River.</div> -</div> - -<p>The disturbances created in this part of the valley by -the bursting of the barriers between the glacial Lake -Bonneville and the Snake River, already described (see -above, <a href="#Page_233">page 233</a>), have not been worked out. There can -be no doubt, however, that interesting results will come -to light in connection with the problem; for Pocatello, -the point at which the <i>débâcle</i> reached the Snake River -plain, is about 2,000 feet higher than Nampa, and 350 -miles distant, and the water must have poured into the -valley faster than the river in its upper portion could have -discharged it. By just what channels the mighty current -worked down to the lower levels on the western borders -of the State it would be most interesting as well as instructive -to know.</p> - -<p>A study of the situation in Tuolumne and Calaveras -<span class="pagenum"><a name="Page_300" id="Page_300">« 300 »</a></span> -Counties, California, reveals a state of things closely resembling, -in important respects, that in western Idaho. -At first sight the impression is made that an immense -lapse of time must have occurred since the volcanic eruption -which furnished the lava of Table Mountain. The -Stanislaus River flows in a channel of erosion a thousand -feet or more lower than the ancient channel filled by lava, -and in two or three places cuts directly across it. An -immense amount of time, also, would seem to be required -to permit the smaller local streams to have worn away so -much of the sides of the ancient valley as to allow the -lava deposit now so continuously to rise above the general -surface. Still, the question of absolute time cannot be -considered separately without much further study. It is -by no means certain that, when the lava-stream poured -down the mountain, it always followed the lowest depressions; -but at certain points it may have been dammed -up in its course by its own accumulations so as to be turned -off into what was then an ancient abandoned channel.</p> - -<div class="fig_center" style="width: 377px;"> -<a id="fig98" name="fig98"></a> -<img src="images/fig_98.png" width="377" height="95" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 98.</span>—Section along the line, north and south: <i>r′ r′</i>, old river-beds; <i>r r</i>, -present river-beds; <i>L</i>, lava; <i>sl</i>, slate.</div> -</div> - -<p>The forms of animal and vegetable life with which -the remains of man under Table Mountain are associated, -are, indeed, to a considerable extent, species now extinct -in California, and some of them no longer exist anywhere -in the world. But a suggestion of Professor Prestwich, -in England, made with reference to the extinct forms of -life associated with human remains in the glacial deposits -in Europe, is revived by Mr. Becker, of the Geological -Survey, with reference to the California discoveries; his -<span class="pagenum"><a name="Page_301" id="Page_301">« 301 »</a></span> -inference being, not that man is so extremely ancient in -California, but that many of these plants and animals -have continued to a more recent date than has ordinarily -been supposed.</p> - -<p>The connection of these lava-flows on the Pacific coast -with the Glacial period is unquestionably close. For -some reason which we do not fully understand, the vast -accumulation of ice in North America during the Glacial -period is correlated with enormous eruptions of lava west -of the Rocky Mountains, and, in connection with these -events, there took place on the Pacific coast an almost -entire change in the plants and animals occupying the -region. Mr. Warren Upham is of the opinion that on -the Pacific coast they lingered much later than in the -region east of the Rocky Mountains. Indeed, it is pretty -certain that not many centuries have elapsed since the -glacial phenomena of the Sierra Nevada Mountains were -much more pronounced than they are at the present time, -and it is equally certain that there have been vast eruptions -of lava in California within three hundred years.</p> - -<p>From these data, therefore, Mr. Becker has real foundation -for his suggestion that perhaps in the Glacial -period California was a kind of health resort for Pliocene -animals, as it is at the present time for man; or, at any -rate, that the later date of the accumulations permitted -the animals to survive there much longer than in the region -east of the Rocky Mountains.</p> - -<p>Further discussion of the preceding facts will profitably -be deferred until, in the next two chapters, the questions -of the cause and date of the Glacial period have -been considered.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_302" id="Page_302">« 302 »</a></span></p> - - - - -<p class="caption2"><a name="CHAPTER_IX" id="CHAPTER_IX">CHAPTER IX.</a></p> - -<p class="caption2">THE CAUSE OF THE GLACIAL PERIOD.</p> - - -<p>In searching for the cause of the Glacial period, it is -evident that we must endeavor to find conditions which -will secure over the centre of the glaciated area either a -great increase of snow-fall or a great decrease in the mean -annual temperature, or both of these conditions combined -in greater or less degree. As can be seen, both from the -nature of the case and from the unglaciated condition of -Siberia and northern Alaska, a low degree of temperature -is not sufficient to produce permanent ice-fields. If the -snow-fall is excessively meagre, even the small amount of -heat in an arctic summer will be sufficient to melt it all -away.</p> - -<p>From the condition of Greenland, however, it appears -that a moderate amount of precipitation where it is chiefly -in the form of snow may produce enormous glaciers if at -the same time the average temperature is low. In southeastern -Alaska, on the other hand, the glaciers are of enormous -size, though the mean annual temperature is by no -means low, for there the great amount of snow-fall amply -compensates for the higher temperature.</p> - -<p>Snow stores the cold and keeps it in a definite place. -If the air becomes chilled, circulation at once sets in, and -the cold air is transferred to warmer regions; but if there -is moisture in the air, so that snow forms, the cold becomes -locked up, as it were, and falls to the earth.</p> - -<p>The amount of cold thus locked up in snow is enormous. -<span class="pagenum"><a name="Page_303" id="Page_303">« 303 »</a></span> -To melt one cubic foot of ice requires as much heat -as would raise the temperature of a cubic foot of water -176° Fahrenheit. To melt a “layer of ice only one inch -and a half thick would require as much heat as would raise -a stratum of air eight hundred feet thick from the freezing-point -to the tropical heat of 88° Fahrenheit.” It is -the slowness with which ice melts which enables it to -accumulate as it does, both in winter and upon high -mountains and in arctic regions. Captain Scoresby relates -that when near the north pole the sun would sometimes -be so hot as to melt the pitch on the south side of -his vessel, while water was freezing on the north side, in -the shade, owing to the cooling effect of the masses of ice -with which he was surrounded.</p> - -<p>Thus it will appear that a change in the direction of -the moist winds blowing from the equator towards the -poles might produce a Glacial epoch. If snow falls upon -the ocean it cools the water, but through the currents, -everywhere visible in the sea, the temperature in the water -in the different parts soon becomes equalized. If, however, -the snow falls upon the land, it must be melted by -the direct action of the sun and wind upon the spot where -it is. If the heat furnished by these agencies is not sufficient -to do it year by year, there will soon be such an -accumulation that glaciers will begin to form. It is clear, -therefore, that the conditions producing a Glacial period -are likely to prove very complicated, and we need not be -surprised if the conclusions to which we come are incapable -of demonstration.</p> - -<p>Theories respecting the cause of the Glacial period -may be roughly classified as astronomical and geological. -Among the astronomical theories, one which has sometimes -been adduced is that the solar system in its movement -through space is subjected to different degrees of -heat at different times. According to this theory, the -temperate climate which characterised the polar regions -<span class="pagenum"><a name="Page_304" id="Page_304">« 304 »</a></span> -during the Tertiary period, and continued up to the beginning -of the Glacial epoch, was produced by the influence -of the warmer stretches of space through which the -whole solar system was moving at that time; while the -Glacial period resulted from the influence upon the earth -of the colder spaces through which the system subsequently -moved.</p> - -<p>While it is impossible absolutely to disprove this -hypothesis, it labors under the difficulty of having little -positive evidence in its favor, and thus contravenes a -fundamental law of scientific reasoning, that we must have -a real cause upon which to rest our theories. In endeavouring -to explain the unknown, we should have something -known to start with. But in this case we are not sure -that there are any such variations in the temperature of -the space through which the solar system moves. This -theory, therefore, cannot come in for serious consideration -until all others have been absolutely disproved. As -we shall also more fully see, in the subsequent discussion, -the distribution of the ice during the Glacial period was -not such as to indicate a gradual extension of it from the -north pole, but rather the accumulation upon centres many -degrees to the south.</p> - -<p>Closely allied with the preceding theory is the supposition -broached by some astronomers that the sun is a -variable star, dependent to some extent for its heat upon -the impact of meteorites, or to the varying rapidity with -which the contraction of its volume is proceeding.</p> - -<p>It is well known that when two solid bodies clash together, -heat is produced proportionate to the momentum -of the two bodies. In other words, the motion which is -arrested is transformed into heat. Mr. Croll, in his last -publication<a name="FNanchor_122" id="FNanchor_122"></a><a href="#Footnote_122" class="fnanchor">[DR]</a> upon the subject, ingeniously attempted to -account for the gaseous condition of the nebulæ and the -<span class="pagenum"><a name="Page_305" id="Page_305">« 305 »</a></span> -heat of the sun and other fixed stars by supposing it to be -simply transformed motion. According to this theory, -the original form of force imparted to the universe was -that exerted in setting in motion innumerable dark bodies, -which from time to time have collided with each other. -The effects of such collisions would be to transform a large -amount of motion into heat and its accompanying forms -of molecular force. The violence of the compact of two -worlds would be so great as to break them up into the -original atoms of which they are composed, and the heat set -free would be sufficient to keep the masses in a gaseous condition -and cause them to swell out into enormous proportions. -From that time on, as the heat radiated into space, -there would be the gradual contraction which we suppose -is going on in all the central suns, accompanied, of -course, with a gradual decline of the heat-energy in the -system.</p> - -<div class="footnote"> - -<p><a name="Footnote_122" id="Footnote_122"></a><a href="#FNanchor_122"><span class="label">[DR]</span></a> Stellar Evolution and its Relation to Geological Time.</p></div> - -<p>Now, it is well known that the earth and the solar -system in their onward progress pass through trains of -meteorites. The tails of some of the comets are indeed -pretty clearly proved to be streams of ponderable matter, -through which, from time to time, the minor members of -the solar system plunge, and receive some accession to -their bulk and weight. The shooting-stars, which occasionally -attract our attention in the sky, mark the course -of such meteorites as they pass through the earth’s atmosphere, -and are heated to a glow by the friction with it. -It has been suggested, therefore, that the sun itself may at -times have its amount of heat sensibly affected by such -showers of meteorites or asteroids. Upon this theory the -warm period of the Tertiary epoch, for instance, may -have been due to the heat temporarily added to the sun -by impact with minor astronomical bodies. When, afterwards, -it gradually cooled down, receiving through a long -period no more accessions of heat from that source, the -way was prepared for the colder epoch of the Glacial -<span class="pagenum"><a name="Page_306" id="Page_306">« 306 »</a></span> -period, which, in turn, was dispelled by fresh showers of -meteorites upon the sun, sufficient to produce the amelioration -of climate which we experience at the present time.</p> - -<p>As intimated, this theory is closely allied to the preceding, -the principal difference being that it limits the -effects of the supposed cause to the solar system, and looks -to our sun as the varying source of heat-supply. It has -the advantage over that, however, of possessing a more -tangible <i>vera causa</i>. Meteorites, asteroids, and comets -are known to be within this system, and have occasional -collisions with other members of it. But the principal -objection urged against the preceding theory applies here, -also, with equal force. The accumulations of ice during -the Glacial period were not determined by latitude. In -North America the centre of accumulation was south of -the Arctic Circle—a fact which points clearly enough to -some other cause than that of a general lowering of the -temperature exterior to the earth.</p> - -<p>The same objections would bear against the theory -ably set forth by Mr. Sereno E. Bishop, of Honolulu, -which, in substance, is that there may be considerable -variability in the sun’s emission of heat, owing to fluctuations -in the rate of the shrinkage of its diameter, brought -about by the unequal struggle between the diminishing -amount of heat in the interior and the increasing force of -the gravitation of its particles, and by the changes in the -enveloping atmosphere of the sun, which, like an enswathing -blanket, arrests a large portion of the radiant heat -from the nucleus, and is itself evidently subject to violent -movements, some of which seem to carry it down to -the sun’s interior. Unknown electrical forces, he thinks, -may also combine to add an element of variability. These -supposed changes may be compared to those which take -place upon the surface of the earth when, at irregular -intervals, immense sheets of lava, like those upon the -Pacific coast of North America, are exuded in a comparatively -<span class="pagenum"><a name="Page_307" id="Page_307">« 307 »</a></span> -brief time, to be succeeded by a long period of rest. -The heat thus brought to the surface of the earth would -add perceptibly to that radiated from it into space in ordinary -times. Something similar to this upon the sun, it -is thought, might produce effects perceptible upon the -earth, and account for alternate periods of heat and -cold.</p> - -<p>A fourth astronomical theory is that there has been a -shifting of the earth’s axis; that at the time of the Glacial -period the north pole, instead of being where it now -is, was somewhere in the region of central Greenland. -This attractive theory has been thought worthy of attention -by President T. C. Chamberlin and by Professor G. -C. Comstock,<a name="FNanchor_123" id="FNanchor_123"></a><a href="#Footnote_123" class="fnanchor">[DS]</a> but it likewise labours under a twofold -difficulty: First, the shifting of the poles observed (450 -feet per year) is too slight to have produced the changes -within any reasonable time, and it is not likely to have -been continuous for a long period. But still more fatal -to the theory is the fact that the warm climate preceding -the Glacial period seems to have extended towards the -present north pole upon every side; a temperate flora -having been found in the fossil plants of the Tertiary beds -in Greenland and northern British America, as well as -upon Nova Zembla and Spitzbergen.</p> - -<div class="footnote"> - -<p><a name="Footnote_123" id="Footnote_123"></a><a href="#FNanchor_123"><span class="label">[DS]</span></a> See papers by these gentlemen read at the meeting of the American -Association for the Advancement of Science, in Washington, in -August, 1891. Professor Comstock’s paper appeared in the American -Journal of Science for January, 1893.</p></div> - -<p>A fifth astronomical theory, and one which has of late -years been received with great favour, is that so ably advocated -by the late Dr. James Croll and by Professor James -Geikie. Following the suggestions of the astronomer -Adhémar, these writers have attempted to show that not -only one Glacial epoch, but a succession of such epochs, -has been produced in the world by the effect of the -changes which are known to have taken place in the -<span class="pagenum"><a name="Page_308" id="Page_308">« 308 »</a></span> -eccentricity of the earth’s orbit when combined with the -precession of the equinoxes—another calculable astronomical -cause.</p> - -<div class="fig_center" style="width: 468px;"> -<a id="fig99" name="fig99"></a> -<img src="images/fig_99.png" width="468" height="272" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 99.</span>—Diagram showing effect of precession: <i>A.</i> condition of things now; -<i>B.</i> as it will be 10,500 years hence. The eccentricity is of course greatly exaggerated.</div> -</div> - -<p>It is well known that the earth’s orbit is elliptical; that -is, it is longer in one direction than in the other, so that -the sun is one side of the centre. During the winter of -the northern hemisphere the earth is now about three -million miles nearer the sun than in the summer; but -the summer makes up for this distance by being about -seven days longer than the winter. Through the precession -of the equinoxes this state of things will be reversed -in ten thousand five hundred years; at which time we -shall be nearer the sun during our northern summer, and -farther away in winter, our winter then being also longer -than our summer. Besides, through the unequal attraction -of the planets the eccentricity of the earth’s -orbit periodically increases and diminishes, so that there -have been periods when the earth was ten million five -<span class="pagenum"><a name="Page_309" id="Page_309">« 309 »</a></span> -hundred thousand miles farther from the sun in winter -than in summer; at which times, also, the winter was -nearly twenty-eight days longer than the summer. Such -an extreme elongation of the earth’s orbit occurred about -two hundred and fifty thousand years ago.</p> - -<p>It is easy to assume that such a change in astronomical -conditions would produce great effects upon the earth’s -climate; and equally easy to connect with those effects the -vast extension of ice during the Glacial period. Since, -also, this period of extreme eccentricity terminated only -eighty thousand years ago, the close of the Glacial period -would, perhaps, upon Mr. Croll’s theory, be comparatively -a recent event; for if the secular summer of the earth’s -eccentricity lags relatively as far behind the secular movements -as the annual summer does behind the vernal -equinox, we should, as Professor Charles H. Hitchcock -suggests, have to place the complete breaking up of the -Ice period as late as forty thousand years ago.<a name="FNanchor_124" id="FNanchor_124"></a><a href="#Footnote_124" class="fnanchor">[DT]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_124" id="Footnote_124"></a><a href="#FNanchor_124"><span class="label">[DT]</span></a> Geology of New Hampshire, vol. iii, p.327.</p></div> - -<p>We have no space to indicate, as it deserves, the comparative -merits and demerits of this ingenious theory. It -would, however, be a great calamity to have geologists -accept it without scrutiny. It is, indeed, a part of the -business of geologists to doubt such theories until they -are verified by a thorough examination of all accessible -<i>terrestrial</i> evidence bearing upon the subject. There is no -reason to question the reality of the variations in the relative -positions of the earth and the sun assumed by Mr. -Croll; though there may be serious doubt whether the -effects of those changes upon climate would be all that is -surmised, since equal amounts of heat would fall upon -the earth during summer, whether made longer or shorter -by the cause referred to. During the short summers -the earth is so much nearer the sun that it receives -each season absolutely as much heat as it does during the -<span class="pagenum"><a name="Page_310" id="Page_310">« 310 »</a></span> -longer summers, when it is so much farther away from -the sun. Thus the theory rests at last upon the question -what would become of the heat reaching the earth in -these differing conditions. It is plausibly urged by Mr. -Croll that when a hemisphere of the earth is passing -through a period of long winters the radiation of heat will -be so excessive that the temperature would fall much -below what it would during the shorter winters; and -so ice and snow would accumulate far beyond the usual -amount. It is also supposed that the effect of the summer’s -sun in melting the ice during the short summer -would be diminished through natural increase of the -amount of foggy and cloudy weather.</p> - -<p>Adhémar’s theory is supposed by Sir Robert Ball, -Royal Astronomer of Ireland, to be considerably re-enforced -by a discovery which he has made concerning the distribution -of heat upon the earth during the seasons culminating -in the summer and winter solstices. Croll had -assumed, on the authority of Herschel, that a hemisphere -of the earth during the longer winter in aphelion would -receive the same actual amount of heat which would fall -upon it during the shorter summer in perihelion; whereas, -according to Dr. Ball’s discovery, “of the total amount of -heat received from the sun on a hemisphere of the earth -in the course of a year, sixty-three per cent is received during -the summer and thirty-seven per cent during the winter.”<a name="FNanchor_125" id="FNanchor_125"></a><a href="#Footnote_125" class="fnanchor">[DU]</a> -When, therefore, the summers occur in perihelion -the heat is more intense than Croll had supposed, and, -at the same time, the winters occurring in aphelion -are more deficient in heat than he had assumed. This -discovery of Dr. Ball will not, however, materially affect -the discussion of Croll’s theory upon its inherent merits, -since it is simply an intensification of the causes -invoked by him. We will therefore let it stand or fall -<span class="pagenum"><a name="Page_311" id="Page_311">« 311 »</a></span> -in the light of the general considerations hereafter to be -adduced.</p> - -<div class="footnote"> - -<p><a name="Footnote_125" id="Footnote_125"></a><a href="#FNanchor_125"><span class="label">[DU]</span></a> Cause of an Ice Age, p. 90.</p></div> - -<p>The aid of theoretical consequent changes in the volume -of the Gulf Stream, and in the area of the trade-winds, -has also to be invoked by Mr. Croll. The theory -likewise receives supposed confirmation from facts alleged -concerning the present climate of the southern hemisphere -which is passing through the astronomical conditions -thought to be favourable to its glaciation. The antarctic -continent is completely enveloped in ice, even down to -the sixty-seventh degree of latitude. A few degrees nearer -the pole Sir J. C. Boss describes the ice as rising from -the water in a precipitous wall one hundred and eighty -feet high. In front of such a wall, and nearly twenty -degrees from the south pole, this navigator sailed four -hundred and fifty miles! Voyagers, in general, are said -to agree that the summers of the antarctic zone are -much more foggy and cold than they are in corresponding -latitudes in the northern hemisphere; and this, even -though the sun is 3,000,000 miles nearer the earth during -the southern summer than it is during the northern.</p> - -<p>Another direction from which evidence is invoked in -confirmation of Mr. Croll’s theory is the geological indications -of successive Glacial epochs in times past. If -there be a recurring astronomical cause sufficient of itself -to produce Glacial periods, such periods should recur as -often as the cause exists; but glaciation upon the scale of -that which immediately preceded the historic era could -hardly have occurred in early geological time without leaving -marks which geologists would have discovered. Were -the “till” now covering the glaciated region to be converted -into rock, its character would be unmistakable, and -the deposit is so extensive that it could not escape notice.</p> - -<p>In his inaugural address before the British Association -in 1880, Professor Ramsey, Director-General of the Geological -Survey of Great Britain, presented a formidable -<span class="pagenum"><a name="Page_312" id="Page_312">« 312 »</a></span> -list of glacial observations in connection with rocks of a -remote age.<a name="FNanchor_126" id="FNanchor_126"></a><a href="#Footnote_126" class="fnanchor">[DV]</a> Beginning at the earliest date, he cites Professor -Archibald Geikie, one of the most competent judges, -as confident that the rounded knobs and knolls of Laurentian -rocks exposed over a large region in northwestern -Scotland, together with vast beds of coarse, angular, unstratified -conglomerates, are unquestionable evidences of -glacial action at that early period. Masses of similar conglomerates, -resembling consolidated glacial boulder-beds, -occur also in the Lower Silurian formation at Corswall, -England. In Dunbar, Scotland, Professor Forbes also -found, in formations of but little later age than the Coal -period, “brecciated conglomerates, consisting of pebbles -and large blocks of stone, generally angular, embedded in -a marly paste, in which some of the pebbles are as well -scratched as those found in medial moraines.” In formations -of corresponding antiquity the geologists of India -have found similar boulder-beds, in which some of the -blocks are polished and striated.</p> - -<div class="footnote"> - -<p><a name="Footnote_126" id="Footnote_126"></a><a href="#FNanchor_126"><span class="label">[DV]</span></a> Nature (August 26, 1880), vol. xxii, pp. 388, 389.</p></div> - -<p>Still, this evidence is less abundant than we should expect, -if there had been the repeated Glacial epochs supposed -by Mr. Croll’s astronomical theory; and it is by no means -impossible that the conglomerates of scratched stones -described by Professor Ramsey in Great Britain, and by -Messrs. Blandford and Medlicott in India, may have resulted -from local glaciers coming down from mountain-chains -which have been since removed by erosion or subsidence. -We are not aware that any incontestable evidence -has been presented in America of any glaciation previous -to that of <i>the</i> Glacial period.</p> - -<p>Upon close consideration, also, it appears that Mr. -Croll’s theory has not properly taken into account the -anomalous distribution of heat which we actually find to -take place on the surface of the earth. He has done good -<span class="pagenum"><a name="Page_313" id="Page_313">« 313 »</a></span> -service in showing what an enormous transfer of heat -there is from the southern to the northern Atlantic by -means of the Gulf Stream, estimating that the heat conveyed -by the Gulf Stream into the Atlantic Ocean is equal -to one fifth of all possessed by the waters of the North Atlantic; -or to the heat received from the sun upon a million -and a half square miles at the equator, or two million -square miles in the temperate zone. “The stoppage of -the Gulf Stream would deprive the Atlantic of -77,479,650,000,000,000,000 foot-pounds of energy in the form of -heat per day.”</p> - -<p>Among the objections which bear against this ingenious -theory is one which will appear with great force when -we come to discuss the date of the Glacial period, when -we shall show that even Professor Hitchcock’s supposition -that the lingering effects of the last great eccentricity of -the earth’s orbit, continued down to forty thousand years -ago, is not sufficient to account for the recentness of the -close of the period as shown by abundant geological evidence. -It is certainly not more than ten or fifteen thousand -years ago that the ice finally melted off from the Laurentian -highlands; while on the Pacific coast the period -of glaciation was still more recent.</p> - -<p>From inspection of the accompanying map the main -point of Mr. Croll’s reasoning may be understood. It -will be seen that the direction of the currents in the central -Atlantic is largely determined by the contour of the -northeastern coast of South America. From some cause -the southeast trade-winds are stronger than the northeast, -and their force is felt in pushing the superficial currents -of warm water farther north than Cape St. Roque, the -eastern extremity of Brazil. As the direction of the -South American coast trends rapidly westward from this -point to the Isthmus of Panama, the resultant of the forces -is a strong current northwestward into the <i>cul-de-sac</i> of -the Gulf of Mexico, from which there is only the one -<span class="pagenum"><a name="Page_314" id="Page_314">« 314 »</a></span> -outlet between Cuba and the peninsula of Florida. -Through this the warm water is forced into the region -where westerly winds prevail, and spreads its genial influence -far to the northward, modifying the climate of -the British Isles, and even of far-off Norway.</p> - -<div class="fig_center" style="width: 446px;"> -<a id="fig100" name="fig100"></a> -<img src="images/fig_100.png" width="446" height="370" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 100.</span>—Map showing course of currents in the Atlantic Ocean: <i>b</i> and <i>b′</i> are -currents set in motion by opposite trade-winds; meeting, they produce the -equatorial current, which divides into <i>c</i> and <i>c′</i>, continuing on as <i>a</i> and <i>a′</i> and <i>e</i>.</div> -</div> - -<p>But why are the southeast trade-winds of the Atlantic -stronger than the northeast? The ultimate reason, of -course, is to be found in the fact that the northern hemisphere -is warmer than the southern. The atmosphere -over the northern-central portion of the Atlantic region -is more thoroughly rarefied by the sun’s heat than is that -over the region south of the equator. The strong southeast -trades are simply the rush of atmosphere from the -<span class="pagenum"><a name="Page_315" id="Page_315">« 315 »</a></span> -South Atlantic to fill the vacuum caused by the heat of -the sun north of the equator.</p> - -<p>But, again, why is this? Because, says Mr. Croll, we -are now in that stage of astronomical development favourable -to the increased warmth of the northern hemisphere. -In the northern hemisphere the summers are longer than -the winters. Perihelion occurs in winter and aphelion in -summer. This is the reason why the North Atlantic is -warmer than the South Atlantic, and why the trade-winds -of the south are drawn to the north of the equator. Ten -thousand five hundred years ago, however, the conditions -were reversed, and the greater rarefaction of the atmosphere -would have taken place south of the equator, thus -drawing the trade-winds in that direction.</p> - -<p>By again inspecting the map, one will see how far-reaching -the effect on the climate of northern countries -this change in the prevalences of the trades would have -been. Then, instead of having the northwest current -leading along the northeast coast of South America into -the Gulf of Mexico augmented by the warm currents circulating -south of the equator, the warm currents of the -north would have been pushed down so far that they -would augment the current running to the southwest beyond -Cape St. Roque, along the southeast shore of South -America; thus the northern portion of the Atlantic, -instead of robbing the southern portion of heat, would -itself be robbed of its warm currents to contribute to the -superfluous heat of the South Atlantic.</p> - -<p>This theory is certainly very ingenious. There is a -weak point in it, however. Mr. Croll assumes that when -the winters of the northern hemisphere occur in aphelion, -they must necessarily be colder than now. But, evidently, -this assertion implies a fuller knowledge than we possess -of the laws by which the heat received from the sun is -distributed over the earth.</p> - -<p>For it appears from observation that the equator is by -<span class="pagenum"><a name="Page_316" id="Page_316">« 316 »</a></span> -no means so hot now as, theoretically, it ought to be, and -that the arctic regions are not so cold as, according to -theory, they should be, and this in places which could not -be affected by oceanic currents. For example, at Iquitos, -on the Amazon, only three hundred feet above tide, three -degrees and a half south of the equator, and more than a -thousand miles from the Atlantic (so that ocean-currents -cannot abstract the heat from its vicinity), the mean -yearly temperature is but 78° Fahr.; while at Verkhojansk, -in northeast Siberia, which is 67° north of the equator, -and is situated where it is out of the reach of ocean-currents, -and where the conditions for the radiation of heat -are most favourable, and where, indeed, the winter is the -coldest on the globe (January averaging—56° Fahr.), the -mean yearly temperature is two degrees and a half above -zero; so that the difference between the temperature upon -the equator and that at the coldest point on the sixty-seventh -parallel is only about 75° Fahr.; whereas, if temperature -were in proportion to heat received from the sun, -the difference ought to be 172°. Again, the difference -between the actual January temperature on the fiftieth -parallel and that upon the sixtieth is but 20° Fahr., -whereas, the quantity of solar heat received on the fiftieth -parallel during the month of January is three times that -received upon the sixtieth, and the difference in temperature -ought to be about 170° Fahr. upon any known law -in the case.</p> - -<p>Woeikoff, a Russian meteorologist, and one of the -ablest critics of Mr. Croll’s theory, and to whom we are -indebted for these facts, ascribes the greater present -warmth of the northern Atlantic basin, not to the astronomical -cause invoked by Mr. Croll, but to the relatively -small extent of sea in the middle latitudes of the northern -hemisphere. The extent and depth of the oceans of the -southern hemisphere would of themselves give greater -steadiness and force to its trade-winds, and lead to a general -<span class="pagenum"><a name="Page_317" id="Page_317">« 317 »</a></span> -lowering of the temperature; so that it is doubtful -if the astronomical causes introduced by Mr. Croll, even -with Dr. Ball’s re-enforcement, would produce any appreciable -effect while the distribution of land and water remains -substantially what it is at the present time.</p> - -<p>Still another variation in the astronomical theory has -been set forth and defended by Major-General A. W. -Drayson, F. R. A. S., instructor in the Royal Military -School at Woolwich, England. He contends that what -has been called the precession of the equinoxes, and supposed -to be “a conical movement of the earth’s axis in a -circle around a point as a centre, from which it continually -decreases its distance,”<a name="FNanchor_127" id="FNanchor_127"></a><a href="#Footnote_127" class="fnanchor">[DW]</a> is really a second rotation of -the earth about its centre. As a consequence of this -second rotation, he endeavours to show that the inclination -of the earth’s axis varies as much as 12°; so that, -whereas the Arctic and Antarctic Circles and the tropics -extend to only about 23° from the poles and the equator, -respectively, about thirteen thousand five hundred years -ago they extended more than 35°; thus bringing the -frigid zones in both cases 12° nearer the equator than -now. This, he contends, would have produced the Glacial -period at the time now more generally assigned to it -by direct geological evidence.</p> - -<div class="footnote"> - -<p><a name="Footnote_127" id="Footnote_127"></a><a href="#FNanchor_127"><span class="label">[DW]</span></a> Untrodden Ground in Astronomy and Geology, p. 26.</p></div> - -<p>The difficulty with this theory, even if the mathematical -calculations upon which it is based are correct, would -be substantially the same as those already urged against -that of Mr. Croll. It is specially difficult to see how -General Drayson would account for the prolonged temperate -climate in high northern latitudes during the -larger part of the Tertiary epoch.</p> - -<p>It will be best to turn again to the map to observe the -possible effect upon the Gulf Stream of a geological event -of which we have some definite evidence, and which -<span class="pagenum"><a name="Page_318" id="Page_318">« 318 »</a></span> -is adduced by Mr. Upham and others as one of the -important probable causes of the Glacial period, namely, -the subsidence of the Isthmus of Panama and the adjacent -narrow neck of land connecting North with South -America. It will be seen at a glance that a subsidence -sufficient to allow the northwest current of warm water, -pushed by the trade-winds along the northeast shore of -South America, to pass into the Pacific Ocean, instead of -into the Gulf of Mexico, would be a cause sufficient to -produce the most far-reaching results; it would rob the -North Atlantic of the immense amount of heat and moisture -now distributed over it by the Gulf Stream, and would -add an equal amount to the northern Pacific Ocean, and -modify to an unknown extent the distribution of heat and -moisture over the lands of the northern hemisphere.</p> - -<p>The supposition that a subsidence of the Isthmus of -Panama was among the contributing causes of the Glacial -period has been often made, but without any positive -proof of such subsidence. From evidence which has recently -come to light, however, it is certain that there has -actually been considerable subsidence there in late Tertiary -if not in post-Tertiary times. This evidence is furnished -by Dr. G. A. Maack and Mr. William M. Gabb in -their report to the United States Government in 1874 -upon the explorations for a ship-canal across the isthmus, -and consists of numerous fossils belonging to existing -species which are found at an elevation of 150 feet above -tide. As the dividing ridge is more than 700 feet above -tide, this does not positively prove the point, but so much -demonstrated subsidence makes it easy to believe, in the -absence of contradictory evidence, that there was more, -and that the isthmus was sufficiently submerged to permit -a considerable portion of the warm equatorial current -which now passes northward from the Caribbean Sea and -the Gulf of Mexico to pass into the Pacific Ocean.</p> - -<p><span class="pagenum"><a name="Page_319" id="Page_319">« 319 »</a></span></p> - -<div class="fig_center" style="width: 550px;"> -<a id="fig101" name="fig101"></a> -<img src="images/fig_101.png" width="550" height="306" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 101.</span>—Map showing how the land clusters about the north pole.</div> -</div> - -<p>An obvious objection to the theory of a late Tertiary -or post-Tertiary subsidence of the Isthmus of Panama -presents itself in the fact that there is at present a complete -diversity of species between the fish inhabiting the -waters upon the different sides of the isthmus. If there -had been such a subsidence, it seems natural to suppose -<span class="pagenum"><a name="Page_320" id="Page_320">« 320 »</a></span> -that Atlantic species would have migrated to the Pacific -side and obtained a permanent lodgment there, and that -Pacific species would have found a congenial home on the -Atlantic side. It must be confessed that this is a serious -theoretical difficulty, but perhaps not insuperable. For -it is by no means certain that colonists from the heated -waters of the Caribbean Sea would become so permanently -established upon the Pacific side that they could maintain -themselves there upon the re-establishment of former -conditions. On the contrary, it seems reasonable to suppose -that upon the re-elevation of the isthmus the northern -currents, which would then resume their course, would -bring back with them conditions unfavourable to the Atlantic -species, and favourable to the competing species -which had only temporarily withdrawn from the field, and -which might now be better fitted than ever to renew the -struggle with their Atlantic competitors. It is by no -means certain, therefore, that with the re-establishment -of the former conditions there would not also be a re-establishment -of the former equation of life upon the two -sides of the isthmus.</p> - -<p>Mr. Upham’s theory involves also extensive elevations -of land in the northern part of America; in this respect -agreeing with the opinions early expressed by Professors -J. D. Dana and J. S. Newberry. Of the positive indications -of such northward elevations of land we have already -spoken when treating in a previous chapter of the fiords -and submerged channels which characterise northern -Europe and both the eastern and the western coasts of -North America. But in working out the problem the -solution is only half reached when we have got the Gulf -Stream into the Pacific Ocean, and the land in the northern -part of the continents elevated to some distance above -its present level. There is still the difficulty of getting -the moisture-laden currents from the Pacific Ocean to -carry their burdens over the crest of the Sierra Nevada -<span class="pagenum"><a name="Page_321" id="Page_321">« 321 »</a></span> -and Rocky Mountains and to deposit them in snow upon -the Laurentian highlands. An ingenious supplement to -the theory, therefore, has been brought forward by Professor -Carpenter, who suggests that the immense Tertiary -and post-Tertiary lava-flows which cover so much of the -area west of the Rocky Mountains were the cause of the -accumulations of snow which formed the Laurentide -Glacier. This statement, which at first seems so paradoxical -as to be absurd, appears less so upon close examination.</p> - - -<p>The extent of the outflows of lava west of the Rocky -Mountains is almost beyond comprehension. Literally, -hundreds of thousands of square miles have been covered -by them to a depth in many places of thousands of -feet. These volcanic eruptions are mostly of late date, -beginning in the middle of the Tertiary and culminating -probably about the time of the maximum extent of the -Laurentide Glacier. Indeed, so nearly contemporaneous -was the growth of the Laurentide Glacier with these outflows -that Professor Alexander Winchell had, with a -good deal of plausibility, suggested that the outflows of -the eruptions of lava were caused by the accumulation of -ice over eastern British America. His theory was that -the three million cubic miles of ice which is proved to -have been abstracted from the ocean and piled up over that -area was so serious a disturbance of the equilibrium of -the earth’s crust that it caused great fissures to be opened -along the lines of weakness west of the Rocky Mountains, -and pressed the liquid lava out, as the juice is pressed -out of an orange in one place by pressing upon the rind -in another.</p> - -<p>Professor Carpenter’s view is the exact reverse of Professor -Winchell’s. Going back to those orographic changes -which produced the lava-flows and the elevation of the -northern part of British America, he thinks the problem -of getting the moisture transferred from the Pacific -<span class="pagenum"><a name="Page_322" id="Page_322">« 322 »</a></span> -Ocean to the Canadian highlands is solved by the lava-flows -west of the Rocky Mountains. This immense exudation -of molten matter was accompanied by an enormous -liberation of heat, which must have produced significant -changes in the meteorological conditions.</p> - -<p>The moisture of the atmosphere is precipitated by -means of the condensation connected with a lowering of -its temperature. Ordinarily, therefore, when moist winds -from an oceanic area pass directly over a lofty mountain-chain, -the precipitation takes place immediately, and the -water finds its way back by a short course to the sea. -This is what now actually occurs on the Pacific coast. -The Sierra Nevada condense nearly all the moisture; so -that very little falls on the vast area extending from their -summits eastward to the Rocky Mountains. All that region -is now practically a desert land, where the evaporation -exceeds the precipitation. In Professor Carpenter’s -view the heat radiated from the freshly exuded lava is -supposed to have prevented the precipitation near the -coast-line, and to have helped the winds in carrying it -farther onward to the northeast, where it would be condensed -upon the elevated highlands, upon which the -snows of the great Laurentide Glacier were collected.</p> - -<p>It is not necessary for us to attempt to measure the -amount of truth in this subsidiary hypothesis of Professor -Carpenter, but it illustrates how complicated are the conditions -which have to be considered before we rest securely -upon any particular hypothesis. The unknown elements -of the problem are so numerous, and so far-reaching in -their possible scope, that a cautious attitude of agnosticism, -with respect to the cause of the Glacial period, is -most scientific and becoming. Still, we are ready to go so -far as to say that Mr. Upham’s theory comes nearest to -giving a satisfactory account of all the phenomena, and it -is to this that Professor Joseph Le Conte gives his cautious -approval.</p> - -<p><span class="pagenum"><a name="Page_323" id="Page_323">« 323 »</a></span></p> - -<p>Summarily stated, this theory is, that the passage from -the Tertiary to the Quaternary or Glacial period was characterised -by remarkable oscillations of land-level, and by -corresponding changes of climate, and of ice-accumulation -in northern regions; that the northern elevation was -connected with subsidence in the equatorial regions; that -these changes of land-level were both initiated and, in the -main, continued by the interior geological forces of the -globe; but that the very continental elevation which -mainly brought on the Glacial period added at length, in -the weight of the ice which accumulated over the elevated -region, a new force to hasten and increase the subsidence, -which would have taken place in due time in the natural -progress of the orographic oscillations already begun. -Professor Le Conte illustrates the subject by the following -diagram, which, for simplicity’s sake, treats the Glacial -epoch as one; the horizontal line, A B, represents time -from the later Pliocene until now; but it also represents -the present condition of things both as to land-level and -as to ice-accumulation. The full line, c d e, represents -the oscillations of land (and presumably of temperature) -above and below the present condition. The broken line -represents the rise, culmination, and decline of ice-accumulation. -The dotted line represents the crust-movement -as it would have been if there had been no ice-accumulation.</p> - -<div class="fig_center" style="width: 432px;"> -<a id="fig102" name="fig102"></a> -<img src="images/fig_102.png" width="432" height="99" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 102.</span></div> -</div> - - -<p><span class="pagenum"><a name="Page_324" id="Page_324">« 324 »</a></span></p> - -<p class="center larger pmt2 pmb2"><i>Succession of Epochs, Glacial and Fluvial Deposits, and<br /> -Changes in Altitude and Climate, during the Quaternary Era.</i></p> - -<table class="epochs" summary="Epochs"> -<tr> - <td class="center"><span class="center smcap">Epochs.</span></td> - <td class="center"><span class="center smcap">Eastern Provinces and - New England.</span></td> - <td class="center"><span class="center smcap">Middle and Southern - Atlantic States.</span></td> -</tr> -<tr> - <td class="center"><span class="smcap">Recent</span> or<br /> - <span class="smcap">Terrace</span>.<br /><br /> - (Mostly within the period of traditional and written - history.)</td> - <td class="vtop1">Rise of the land to its present - height, or somewhat higher, soon - after the departure of the ice. - Rivers eroding their glacial flood-plains, - leaving remnants as terraces. - Warmer climate than now, - probably due to greater Gulf - Stream, formerly permitted southern - mollusks to extend to Gulf of - St. Lawrence, now represented by - isolated colonies.</td> - <td class="vtop1">Continued subsidence of coast - at New York and southward, and - rise of the mountainous belt, by - displacement along the fall line - of the rivers. Much erosion of - the Columbia formation since culmination - of second Glacial epoch; - sedimentation in bays, sounds, - and estuaries.</td> -</tr> -<tr> - <td class="center" colspan="3"><span class="smcap">Glacial Period or Ice Age. Pleistocene Period.</span></td> -</tr> -<tr> - <td class="center"><span class="smcap">Champlain.</span><br /><br /> - (Close of the second Glacial epoch.)</td> - <td class="vtop1">Land depressed under ice-weight; - glacial recession; continued - deposition of upper till - and deep flood-plains of gravel, - sand and clay (modified drift). - Terminal moraines marking pauses - or readvance during general retreat - of ice. Marine submergence. - 150 to 230 feet on coast of Maine, - to 520 feet in Gulf and valley of - St. Lawrence.</td> - <td class="vtop1">Less subsidence in latitude of - New York and southward than at - north; lower Hudson Valley, and - part of its present submarine continuation, - above sea-level. Gravel - and sand deposits from englacial - drift in Delaware and Susquehanna - Valleys, inclosing abundant - human implements at Trenton, N.J.</td> -</tr> -<tr> - <td class="center"><span class="smcap">Second Glacial.</span></td> - <td class="vtop1">Second great uplift of the land, - 3,000 to 4,000 feet higher than - now; snow-fall again all the year; - ice probably two miles thick on - Laurentide highlands, and extending - somewhat farther south here - than in first glaciation. Lower - till (ground moraine), and upper - till (englacial drift). Terminal - moraines, kames, osars, valley - drift.</td> - <td class="vtop1">Renewal of great continental - elevation (3,000 feet in latitude of - New York and Philadelphia), of - excessive snow-fall and rains, and - of wide-spread fluvial deposits, the - Columbia formation, on the coastal - plain, during early part of this - epoch. Implements of man at - Claymont, Del.</td> -</tr> -<tr> - <td class="center"><span class="center smcap">Inter-glacial.</span><br /><br /> - (Longest epoch of this era.)</td> - <td class="vtop1">Ice-sheet melted here; probably - not more ice in arctic regions - than now.<br /> - Fluvial and lacustrine deposits - of this time, with those of the - first Glacial epoch, were eroded - by the second glaciation.</td> - <td class="vtop1">Depression, but generally not to - the present level. Deep channels - cut in the bed-rocks by the Delaware, - Susquehanna, Potomac, and - other rivers. The Appomattox - deposits much eroded.<br /> - Relative length of this epoch - made known by McGee from - study of this region.</td> -</tr> -<tr> - <td class="center"><span class="smcap">First Glacial.</span></td> - <td class="vtop1">Begun by high continental uplift, - cool climate and snow-fall - throughout the year, producing - ice-sheet. Much glacial erosion - and transportation; till and stratified - deposits. Ended by depression - of land; return of warm climate, - with rain; final melting of - the ice. Isthmus of Panama - probably submerged (Gulf Stream - smaller), and again in second - Glacial epoch.</td> - <td class="vtop1">Continental elevation; erosion - of Delaware and Chesapeake Bays, - and of Albemarle and Pamlico - Sounds. Plentiful snow-fall on - the southern Appalachian Mountains; - snows melted in summer, - and heavy rains, producing broad - river-floods, with deposition of the - Appomattox formation.</td> -</tr> -<tr> - <td class="center larger" style="border-left: 0; border-right: 0;" colspan="3"><br /><i>Succession of Epochs</i> (cont.)<br /> - <span class="pagenum"><a name="Page_325" id="Page_325">« 325 »</a></span><br /></td> -</tr> -<tr> - <td class="center smcap vmid">Mississippi Basin and - northward.</td> - <td class="center smcap vmid">Cordilleran Region.</td> - <td class="center vmid"><span class="smcap">Europe and Asia.</span></td> -</tr> -<tr> - <td class="vtop1">Terracing of river valleys. - Northward rise of area of Lake Agassiz nearly complete - before the ice was melted on the country crossed - by Nelson River; but rise about Hudson Bay is still - going on; 7,000 to 8,000 years since ice-melting uncovered - Niagara and falls of St. Anthony.</td> - <td class="vtop1">Including a stage of considerable - uplift, with return of humid conditions, Alpine - glaciation (third Glacial epoch), and the second great - rise of Lakes Bonneville and Lahontan. Very recent subsidence - and change to present aridity.</td> - <td class="vtop1">Erosion and terracing of - stratified drift in river valleys. Land passage of European - flora to Greenland; succeeded by subsidence there, admitting - warm currents to Arctic Sea. Minor climatic - changes, including a warmer stage than now. Upper and - outer portions of Indo-Gangetic alluvial plain; extensive - deposits of Hwang Ho, and destructive changes of its - course.</td> -</tr> -<tr> - <td class="center" colspan="3"><p class="smcap">Glacial Period or Ice Age. Pleistocene Period.</p></td> -</tr> -<tr> - <td class="vtop1">Abundant deposition of englacial - drift. Stone implements in river gravels of - Ohio, Ind., and Minn. Laurentian lakes held at higher - levels, and Lake Agassiz formed in Red River basin, by - barrier of retreating ice, with outlets over lowest points of - their present southern water-shed. Marine submergence - 300 to 500 feet on southwest side of Hudson Bay.</td> - <td class="vtop1">Depression probably almost - to the present level. Restoration of arid climate; - nearly or quite complete evaporation of Lakes Bonneville - and Lahontan. Formation of the “adobe” continuing - through the second Glacial, Champlain, and Recent - epochs.</td> - <td class="vtop1">Final departure of the ice-sheets; - glacial rivers forming eskers and kames. Loess - deposited while the region of the Alps was depressed lower - than now. Upper (englacial) till, and asar, of Sweden. - Marine submergence 500 to 600 feet in Scotland, Scandinavia, - and Spitzbergen.</td> -</tr> -<tr> - <td class="vtop1">Ice-sheet here less extensive - than in the first Glacial epoch, and not generally bordered - as then by lakes in valleys which now drain southward.<br /> - Terminal moraines at extreme limit of the ice-advance, - and at ten or more stages of halt or readvance - in its retreat.</td> - <td class="vtop1">Probable uplift 3,000 feet, - shown by submerged valleys near Cape Mendocino. Second - ice-sheet on British Columbia and Vancouver Island; - local glaciation of Rocky Mountains, Cascade range, - and Sierra Nevada, south to latitude 37°. First great rise - of Lakes Bonneville and Lahontan.</td> - <td class="vtop1">Second elevation and general - glaciation of northwestern Europe; the ice-sheets of - Great Britain probably more extensive than in first Glacial - epoch. Oscillations of ice-front; British Lower and - Upper bowlder-clays, the Chalky, Purple, and Hessle - bowlder-clays. Terminal moraines in Germany.</td> -</tr> -<tr> - <td class="vtop1">Depression nearly to present - level southward; more northward, but followed there, - by differential uplift of 800 or 1,000 feet. Great erosion of - loess and other modified drift, and of “Orange Sand.” Valleys - of this epoch, partly filled with later till, are - marked by chains of lakes in southern Minnesota.</td> - <td class="vtop1">Continental depression. Arid - climate. Long-continued denudation of the mountains: - resulting very thick subaërial deposits of the “adobe.”<br /> - Intermittent volcanic action in various parts of this - region, throughout the Quaternary era to very recent - times, and liable to break forth again.</td> - <td class="vtop1">Recession, or probably complete - departure, of the ice-sheets.<br /> - Land connection between Europe and Africa, permitting - southern animals to extend far northward.<br /> - Erosion of the Somme Valley - below its oldest implement-bearing - gravels.</td> -</tr> -<tr> - <td class="vtop1">Pliocene elevation of continent brought to culmination - at beginning of Quaternary era; this whole basin probably - then uplifted 3,000 feet; excessive snow-fall and rain; - deposition of the “Orange Sand.” Ice-sheet south to - Cincinnati and St. Louis, at length depressing the earth’s - crust beneath it; slackened river floods and shallow lakes, - forming the loess.</td> - <td class="vtop1">Latest rise (3,000 feet) of the Colorado Cañon district. - Sierra Nevada and other Great Basin mountain-ranges - formed by immense uplifts, with faulting. California river-courses - changed; human bones and implements in the - old river gravels, lava-covered. Ice-sheet on British Columbia; - local glaciers southward.</td> - <td class="vtop1">Uplift and glaciation of northwestern Europe: maximum - elevation. 2,500 feet or more (depth of the Skager - Rack); France and Britain united with the Färöe Islands, - Iceland, and Greenland. Uplifts of the Himalayas - and other mountain-ranges attendant on both - Glacial epochs.</td> -</tr> -</table> - - -<p><span class="pagenum"><a name="Page_326" id="Page_326">« 326 »</a></span></p> - -<p>It is seen from the diagram that the ice-accumulation -culminated at a time when the land, under the pressure -of the ice-load, had already commenced to subside; and -that the subsidence was greatest at a time when the pressure -had already begun to diminish. But the fact that -the land, after the removal of the ice-load, did not return -again to its former height in the Pliocene, is proof positive -that there were other and more fundamental causes -of crust-movement at work besides weighting and lightening. -The land did not again return to its former level -because the cycle of elevation, whatever its cause, which -commenced in the Pliocene and culminated in the early -Quaternary, had exhausted itself. If it had not been for -the ice-load interfering with and modifying the natural -course of the crust-movement determined previously and -primarily by other and probably internal causes, the latter -would probably have taken the course represented by -the dotted line. It would have risen higher and culminated -later, and its curve would have been of simpler -form.</p> - -<p>We append a carefully prepared table by Mr. Warren -Upham, showing the probable changes in altitude and -climate during the Quaternary era.<a name="FNanchor_128" id="FNanchor_128"></a><a href="#Footnote_128" class="fnanchor">[DX]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_128" id="Footnote_128"></a><a href="#FNanchor_128"><span class="label">[DX]</span></a> On <a href="#Page_106">page 106</a> and sequel I have summarised the reasons which -lead me to discard the Inter-Glacial epoch, and to look upon the -whole Glacial period as constituting a grand unity with minor -episodes. It does not yet seem to me that the duality of the period -is proved. On the contrary, Mr. Kendall’s chapter on the Glacial -phenomena of Great Britain strongly confirms my view.</p></div> - -<p>On the part of many the theory here provisionally -adopted will be regarded with disfavour by reason of a disinclination -to supposing any great recent changes of level -in the continental areas. So firmly established do the -continents appear to be, that it seems like invoking an -inordinate display of power to have them exalted for the -sake of producing a Glacial period. Due reflection, however, -will make it evident that within certain limits the -continents are exceedingly unstable, and that they have -displayed this instability to as great an extent in recent -<span class="pagenum"><a name="Page_327" id="Page_327">« 327 »</a></span> -geological times as they have done in any previous geological -periods. When one reflects, also, upon the size -of the earth, a continental elevation of 3,000 or 4,000 feet -upon a globe whose diameter is more than 40,000,000 feet -is an insignificant trifle. On a globe one foot in diameter -it would be represented by a protuberance of barely one -thousandth of an inch. A corresponding wrinkle upon a -large apple would require a magnifying-glass for its detection. -Moreover, the activity of existing volcanoes, the -immense outflows of lava which have taken place in the -later geological periods, together with the uniform increase -of heat as we penetrate to deeper strata in the crust of -the earth—all point to a condition of the earth’s interior -that would make the elevations of land which we have -invoked for the production of the Glacial period easily -credible. Physicists do not, indeed, now hold to the entire -fluidity of the earth’s interior, but rather to a solid centre, -where gravity overcomes the expansive power of heat, and -maintains solidity even when the heat is intense. But -between the cooling crust of the earth’s exterior and a -central solid core there is now believed to be a film where -the influences of heat and of the pressure of gravity are -approximately balanced, and the space is occupied by a -half-melted or viscous magma, capable of yielding to a -slow pressure, and of moving in response to it from one -portion of the enclosed space to another where the pressure -is for any cause relieved.</p> - -<p>As a result of prolonged enquiries respecting the nature -of the forces at work both in the interior and upon -the exterior of the earth, and of a careful study of the -successive changes marking the geological period, we are -led to believe that the continental elevations necessary to -produce the phenomena of the Glacial period are not -only entirely possible but easily credible, and in analogy -with the natural progress of geological history. In the -first place, it is easy to see that two causes are in operation -<span class="pagenum"><a name="Page_328" id="Page_328">« 328 »</a></span> -to produce a contraction of the earth’s volume and a -shortening of its diameter. Heat is constantly being abstracted -from the earth by conduction and radiation, but -perhaps to a greater extent through ceaseless volcanic -eruptions which at times are of enormous extent. It requires -but a moment’s thought to see that contraction of -the volume of the earth’s interior means that the hardened -exterior crust must adjust itself by wrinkles and -folds. For a long period this adjustment might show -itself principally in gentle swells, lifting portions of the -continents to a higher level, accompanied by corresponding -subsidence in other places. This gradually accumulating -strain would at length be relieved along some line of -special weakness in the crust by that folding process which -has pushed up the great mountain systems of the world.</p> - -<p>Careful study of the principal mountain systems shows -that all the highest of them are of late geological origin. -Indeed, the latter part of the Tertiary period has been -the great mountain-building epoch in the earth’s history. -The principal part of the elevation of the Andes and the -Rocky Mountains has taken place since the middle of the -Tertiary period. In Europe there is indubitable evidence -that the Pyrenees have been elevated eleven thousand feet -during the same period, and that the western Alps have -been elevated thirteen thousand feet in the same time. -The Carpathians, the western Caucasus, and the Himalayas -likewise bear explicit evidence to the fact that a -very considerable portion of their elevation, amounting to -many thousand feet, has been effected since the middle of -the Tertiary period, while a considerable portion of this -elevation of the chiefest mountain systems of the world -has occurred in what would be called post-Tertiary time—that -is, has been coincident with a portion of the Glacial -period.</p> - -<p>The Glacial period, however, we suppose to have been -brought about, not by the specific plications in the earth’s -<span class="pagenum"><a name="Page_329" id="Page_329">« 329 »</a></span> -crust which have produced the mountain-chains, but by -the gentler swells of larger continental areas whose strain -was at last relieved by the folding and mashing together -of the strata along the lines of weakness now occupied by -the mountain systems. The formation of the mountains -seems to have relieved the accumulating strain connected -with the continental elevations, and to have brought about -a subsequent subsidence.</p> - -<p>Doubtless, also, correlated subsidences and elevations -of the earth’s crust have been aided by the transfer of the -sediment from continental to oceanic areas, and, as already -suggested, during the Glacial period by the transfer of -water evaporated from the surface of the ocean to the ice-fields -of the glaciated area. For example, present erosive -agencies are lowering the level of the whole Mississippi -basin from the Alleghanies to the Rocky Mountains at the -rate of a foot in five thousand years. All this sediment -removed is being transferred to the ocean-bed. Present -agencies, therefore, if not counteracted, would remove the -whole continent of America (whose average elevation -above the sea is only 748 feet) in less than four million -years; while the great rivers which descend in all directions -from the central plateau of Asia are transferring -sediment to the ocean from two to four times as fast as -the Mississippi is, and the Po is transferring it from the -Alps to the Adriatic fully seven times as fast as the Mississippi -is from its basin to the Gulf of Mexico. This -rapid transfer of sediment from the continents to the -ocean is producing effects in disturbing the present equilibrium -of the earth’s crust, which are too complicated -for us fully to calculate; but it is by no means improbable -that when accumulating for a considerable length of -time, the ultimate results may be very marked and perhaps -sudden in their appearance.</p> - -<p>The same may also be said of the accumulation of ice -during the Glacial period. The glaciated areas of North -<span class="pagenum"><a name="Page_330" id="Page_330">« 330 »</a></span> -America and Europe combined comprise about six million -square miles. At a moderate estimate, the ice was -three-quarters of a mile deep. Here, therefore, there -would be between four and five million cubic miles of -water, which had first relieved the ocean-beds of the pressure -of its weight, and then concentrated its force over -the elevated areas of the northern hemisphere. This disturbance -of the equilibrium, by the known transfer of -force from one part of the earth’s crust to another, certainly -gives much plausibility to the theory of Jamieson, -Winchell, Le Conte, and Upham, that the Glacial period -partly contained in itself its own cure, and by the weight -of its accumulated weight of ice helped to produce that -depression over the glaciated area which at length rendered -the accumulation of ice there impossible.</p> - -<p>This general view of the known causes in operation -during the Glacial period will go far towards answering -an objection that has probably before this presented itself -to the reader’s mind. It seems clear that the Glacial -period in the southern hemisphere has been nearly contemporaneous -with that of the northern. The Glacial -period proper of the southern hemisphere is long since -passed. The existing glaciers of New Zealand, of the -southern portion of the Andes Mountains, and of the -Himalaya Mountains are but remnants of those of former -days. In the light of the considerations just presented, -it would not seem improbable that the same causes should -produce these similar effects in the northern and the -southern hemisphere contemporaneously. At any rate, it -would not seem altogether unlikely that the pressure of -ice during the climax of the Glacial period upon the -northern hemisphere (which, as we have seen, there is -reason to believe aided in the depression of the continent -to below its present level in the latter part of the Glacial -period) should have contributed towards the elevation of -mountains in other parts of the world, and so to the -<span class="pagenum"><a name="Page_331" id="Page_331">« 331 »</a></span> -temporary enlargement of the glaciers about their summits.</p> - -<p>Nor are we wholly without evidence that these readjustments -of land-level which have been carried on so -Vigorously since the middle of the Tertiary period are -still going on with considerable though doubtless with -diminished rapidity. There has been a re-elevation of -the land in North America since the Glacial period -amounting to 230 feet upon the coast of Maine, 500 feet -in the vicinity of Montreal, from 1,000 to 1,600 feet in -the extreme northern part of the continent, and in Scandinavia -to the extent of 600 feet. In portions of Scandinavia -the land is now rising at the rate of three feet in a -century. Other indications of even the present instability -of the earth’s surface occur in numbers too numerous to -mention.<a name="FNanchor_129" id="FNanchor_129"></a><a href="#Footnote_129" class="fnanchor">[DY]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_129" id="Footnote_129"></a><a href="#FNanchor_129"><span class="label">[DY]</span></a> For a convincing presentation of the views here outlined, together -with abundant references to literature, see Mr. Warren Upham’s -Appendix to the author’s Ice Age in North America.</p></div> - -<p>But, while we are increasingly confident that the main -causes of the Glacial period have been changes in the relative -relation of land-levels connected with diversion of oceanic -currents, it is by no means impossible, as Wallace<a name="FNanchor_130" id="FNanchor_130"></a><a href="#Footnote_130" class="fnanchor">[DZ]</a> -and others have suggested, that these were combined with -the astronomical causes urged by Drs. Croll and Geikie. -By some this combination is thought to be the more probable, -because of the extreme recentness of the close of the -Glacial period, as shown by the evidence which will be -presented in the following chapter. The continuance of -glaciers in the highlands of Canada, down to within a few -thousand years of the present time, coincides in a remarkable -manner with the last occurrence of the conditions -favourable to glaciation upon Mr. Croll’s theory, which -took place about eleven thousand years ago.</p> - -<div class="footnote"> - -<p><a name="Footnote_130" id="Footnote_130"></a><a href="#FNanchor_130"><span class="label">[DZ]</span></a> See Island Life, chapters viii and ix.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_332" id="Page_332">« 332 »</a></span></p></div> - - - - -<p class="caption2"><a name="CHAPTER_X" id="CHAPTER_X">CHAPTER X.</a></p> - -<p class="caption2">THE DATE OF THE GLACIAL PERIOD.</p> - - -<p>In approaching the subject of glacial chronology, we -are compelled to recognise at the outset the approximate -character of all our calculations. Still, we shall find that -there are pretty well-defined limits of time beyond which -it is not reasonable to place the date of the close of the -Glacial period; and, where exact figures cannot be determined, -it may yet be of great interest and importance -to know something near the limits within which our speculations -must range.</p> - -<p>For many years past Mr. Croll’s astronomical theory -as to the cause of the Glacial period has been considered -in certain circles as so nearly established that it has been -adopted by them as a chronological table in which to insert -a series of supposed successive Glacial epochs which are -thought to have characterised not merely the Quaternary -epoch but all preceding geological eras. What we have -already said, however, respecting the weakness of Mr. -Croll’s theory is probably sufficient to discredit it as a -chronological apparatus. We will therefore turn immediately -to the more tangible evidences bearing upon the -subject.</p> - -<p>The data directly relating to the length of time which -separates the present from the Glacial period are mainly -connected with two classes of facts:</p> - -<p>1. The amount of erosion which has been accomplished -by the river systems since the Glacial period; and 2. The -<span class="pagenum"><a name="Page_333" id="Page_333">« 333 »</a></span> -amount of sedimentation which has taken place in lakes -and kettle-holes. We will consider first the evidence -from erosion.</p> - -<div class="fig_center" style="width: 455px;"> -<a id="fig103" name="fig103"></a> -<img src="images/fig_103.png" width="455" height="225" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 103.</span>—Diagram of eccentricity and precession: Abscissa represents time and -ordinates, degrees of eccentricity and also of cold. The dark and light -shades show the warmer and colder winters, and therefore indicate each -10,500 years, the whole representing a period of 300,000 years.</div> -</div> - -<p>The gorge below Niagara Falls affords an important -chronometer for measuring the time which has elapsed -since a certain stage in the recession of the great North -American ice-sheet. As already shown, the present Niagara -River is purely a post-glacial line of drainage;<a name="FNanchor_131" id="FNanchor_131"></a><a href="#Footnote_131" class="fnanchor">[EA]</a> the -preglacial outlet to Lake Erie having been filled up by -glacial deposits, so that, on the recession of the ice, the -lowest level between Lake Erie and Lake Ontario was in -the line of the trough of the present outlet. But, from -what has already been said, it also appears that the Niagara -River did not begin to flow until considerably after the -ice-front had withdrawn from the escarpment at Queenston, -where the river now emerges from its cañon to the -low shelf which borders Lake Ontario. For a considerable -period afterwards the ice continued to block up the easterly -and northerly outlets through the valleys of the -Mohawk and of the St. Lawrence, and held the water in -front of the ice up to the level of the passes leading into -the Mississippi Valley. Niagara River, of course, was not -born until these ice-barriers on the east and northeast -melted away sufficiently to allow the drainage to take its -natural course.</p> - -<div class="footnote"> - -<p><a name="Footnote_131" id="Footnote_131"></a><a href="#FNanchor_131"><span class="label">[EA]</span></a> See above, <a href="#Page_200">p. 200</a> <i>et seq.</i></p> - -<p><span class="pagenum"><a name="Page_334" id="Page_334">« 334 »</a></span></p></div> - -<div class="fig_center" style="width: 409px;"> -<a id="fig104" name="fig104"></a> -<img src="images/fig_104.png" width="409" height="692" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 104.</span>—Map of the Niagara River below the falls, showing the buried channel -from the whirlpool to St. Davids. Small streams, <i>a</i>, <i>b</i>, <i>c</i>, fall into the main -gorge over a rocky escarpment. No rock appears in the channel at <i>d</i>, but the -rocky escarpment reappears at <i>e</i>.</div> -</div> - -<p><span class="pagenum"><a name="Page_335" id="Page_335">« 335 »</a></span></p> - -<p>Of these barriers, that across the Mohawk Valley doubtless -gave way first. This would allow the confluent waters -of this great glacial lake to fall down to the level of the old -outlet from the basin of Lake Ontario into the Mohawk -Valley, in the vicinity of Home, N. Y. The moment, however, -that the water had fallen to this level, the plunging -torrents of Niagara would begin their work; and the -gorge extending from Queenston up to the present falls is -the work done by this great river since that point of time -in the Glacial period when the ice-barrier across the Mohawk -Valley broke away.</p> - -<p>The problem is therefore a simple one. Considering -the length of this gorge as the dividend, the object is to -find the rate of annual recession; this will be the divisor. -The quotient will be the number of years which have -elapsed since the ice first melted away from the Mohawk -Valley. We are favoured in our calculation by the simplicity -of the geologic arrangement.</p> - -<p>The strata at Niagara dip slightly to the south, but -not enough to make any serious disturbance in the problem. -That at the surface, over which the water now -plunges, consists of hard limestone, seventy or eighty feet -in thickness, and this is continuous from the falls to -the face of the escarpment at Queenston, where the river -emerges from the gorge. Immediately underneath this -hard superficial stratum there is a stratum of soft rock, -of about the same thickness, which disintegrates readily. -As a consequence, the plunging water continually undermines -the hard stratum at the surface, and prepares the -way for it to fall down, from time to time, in huge blocks, -<span class="pagenum"><a name="Page_336" id="Page_336">« 336 »</a></span> -which are, in turn, ground to powder by the constant commotion -in which they are kept, and thus the channel is -cleared of <i>débris</i>.</p> - -<div class="fig_center" style="width: 353px;"> -<a id="fig105" name="fig105"></a> -<img src="images/fig_105.png" width="353" height="166" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 105.</span>—Section of strata along the Niagara gorge from the falls to the lake: -1, 3, strata of hard rock; 2, 4, of soft rock.</div> -</div> - -<p>Below these two main strata there is considerable -variation in the hardness of the rock, as shown in the -accompanying diagram, where 3 and 5 are hard strata -separated by a soft stratum. In view of this fact it seems -probable that, for a considerable period in the early part -of the recession, instead of there being simply one, there -was a succession of cataracts, as the water unequally wore -back through the harder strata, numbered 5, 3, and 1; -but, after having receded half the distance, these would -cease to be disturbing influences, and the problem is thus -really the simple one of the recession through the strata -numbered 1 and 2, which are continuous. So uniform in -consistency are these throughout the whole distance, that -the rate of recession could never have been less than it is -now. We come, therefore, to the question of the rapidity -with which the falls are now receding.</p> - -<p>In 1841 Sir Charles Lyell and Professor James Hall -(the State Geologist of New York) visited the falls together, -and estimated that the rate of recession could not be -greater than one foot a year, which would make the time -required about thirty-five thousand years. But Lyell -thought this rate was probably three times too large; so -<span class="pagenum"><a name="Page_337" id="Page_337">« 337 »</a></span> -that he favoured extending the time to one hundred thousand -years. Before this the eminent French geologist -Desor had estimated that the recession could not have -been more than a foot in a century, which would throw -the beginning of the gorge back more than three million -years. But these were mere guesses of eminent men, -based on no well-ascertained facts; while Mr. Bakewell, -an eminent English geologist, trusting to the data furnished -him by the guides and the old residents of -Niagara, had, even then, estimated that the rate of recession -was as much as three feet a year, which would -reduce the whole time required to about ten thousand -years.</p> - -<p>But the visit of Lyell and Hall in 1841 led to the beginning -of more accurate calculations. Professor Hall -soon after had a trigonometrical survey of the falls made, -from which a map was published in the State geological -report. From this and from the monuments erected, we -have had since that time a basis of comparison in which -we could place absolute confidence.</p> - -<p>In recent years three surveys have been made: the -first by the New York State Geologists, in 1875; and the -third by Mr. R. S. Woodward, the mathematician of the -United States Geological Survey, in 1886. The accompanying -map shows the outlines of the falls at the time of -these three measurements, from 1842 to 1886. According -to Mr. Woodward, “the length of the front of the Horseshoe -Fall is twenty-three hundred feet. Between 1842 -and 1875 four and a quarter acres of rock were worn away -by the recession of the falls. Between 1875 and 1886 a -little over one acre and a third disappeared in a similar -manner, making in all, from 1842 to 1886, about five and -a half acres removed, and giving an annual rate of recession -of about two feet and a half per year for the last -forty-five years. But in the central parts of the curve, -where the water is deepest, the Horseshoe Fall retreated -between two hundred and two hundred and seventy-five -feet in the eleven years between 1875 and 1886.”</p> - -<p><span class="pagenum"><a name="Page_338" id="Page_338">« 338 »</a></span></p> - -<div class="fig_center" style="width: 703px;"> -<a id="fig106" name="fig106"></a> -<img src="images/fig_106.png" width="703" height="392" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 106.</span>—Map showing the recession of the Horseshoe Falls since 1842, as by survey mentioned in the text (Pohlman). (by courtesy of -the American Institute of Mining Engineers.)</div> -</div> - -<p><span class="pagenum"><a name="Page_339" id="Page_339">« 339 »</a></span></p> - -<p>It will be perceived that the recession in the centre of -the Horseshoe is very much more rapid than that nearer -the margin; yet this rate at the centre is more nearly the -standard of calculation than is that near the margin, for -the gorge constantly tends to enlarge itself below the falls, -and so gradually to bring itself into line with the full-formed -channel. Taking all things into account, Mr. -Woodward and the other members of the Geological Survey -thought it not improbable that the average rate of -actual recession in the Horseshoe Fall was as great as five -feet per annum; and that, if we can rely upon the uniformity -of the conditions in the past, seven thousand years is -as long a period as can be assigned to its commencement.</p> - -<p>The only condition in the problem about which there -can be much chance of question relates to the constancy -of the volume of water flowing in the Niagara channel. -Mr. Gilbert had suggested that, as a consequence of the -subsidence connected with the closing portions of the Glacial -period, the water of the Great Lakes may have been -largely diverted from its present outlet in Niagara River -and turned northeastward, through Georgian Bay, French -River, and Lake Nipissing, into a tributary of the Ottawa -River, and so carried into the St. Lawrence below Lake -Ontario. Of this theory there is also much direct evidence. -A well-defined shore line of rounded pebbles extends, -at an elevation of about fifty feet, across the col -from Lake Nipissing to the head-waters of the Mattawa, a -tributary of the Ottawa; while at the junction with the -Ottawa there is an enormous delta terrace of boulders, -forming a bar across the main stream just such as would -result from Mr. Gilbert’s supposed outlet. But this outlet -was doubtless limited to a comparatively few centuries, and -Dr. Robert Bell thinks the evidence still inconclusive.<a name="FNanchor_132" id="FNanchor_132"></a><a href="#Footnote_132" class="fnanchor">[EB]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_132" id="Footnote_132"></a><a href="#FNanchor_132"><span class="label">[EB]</span></a> See Bul. Geol. Soc. Am., vol. iv, pp. 423-427, vol. v, pp. 620-626.</p> - -<p><span class="pagenum"><a name="Page_340" id="Page_340">« 340 »</a></span></p></div> - -<p>A second noteworthy glacial chronometer is found in -the gorge of the Mississippi River, extending from the -Falls of St. Anthony, at Minneapolis, to its junction with -the preglacial trough of the old Mississippi, at Fort Snelling, -a distance likewise of about seven miles.</p> - -<p>Above Fort Snelling the preglacial gorge is occupied -by the Minnesota River, and, as we have before stated, -extends to the very sources of this river, and is continuous -with the southern portion of the valley of the trough of -the Red River of the North. Before the Glacial period -the drainage of the present basin of the upper Mississippi -joined this main preglacial valley, not at Fort Snelling, -but some little distance above, as shown upon our map.<a name="FNanchor_133" id="FNanchor_133"></a><a href="#Footnote_133" class="fnanchor">[EC]</a> -This part of the preglacial gorge became partially filled -up with glacial deposits, but it can be still traced by the -lakelets occupying portions of the old depression, and by -the records of wells which have been sunk along the line. -When the ice-front had receded beyond the site of Minneapolis, -the only line of drainage left open for the water -was along the course of the present gorge from Minneapolis -to Fort Snelling.</p> - -<div class="footnote"> - -<p><a name="Footnote_133" id="Footnote_133"></a><a href="#FNanchor_133"><span class="label">[EC]</span></a> See above, <a href="#Page_209">p. 209</a>.</p></div> - -<p>Here, as at Niagara, the problem is comparatively -simple. The upper strata of rock consist of hard limestone, -which is underlaid by a soft sandstone, which, like -the underlying shale at Niagara, is eroded faster than the -upper strata, and so a perpendicular fall is maintained. -The strata are so uniform in texture and thickness that, -with the present amount of water in the river, the rate of -recession of the falls must have been, from the beginning, -very constant. If, therefore, the rate can be determined, -the problem can be solved with a good degree of confidence.</p> - - -<p>Fortunately, the first discoverer of the cataract—the -Catholic missionary Hennepin—was an accurate observer, -<span class="pagenum"><a name="Page_341" id="Page_341">« 341 »</a></span> -and was given to recording his observations for the instruction -of the outside world and of future generations. -From his description, printed in Amsterdam in 1704, -Professor N. H. Winchell is able to determine the precise -locality of the cataract when discovered in 1680.</p> - -<p>Again, in 1766 the Catholic missionary Carver visited -the falls, and not only wrote a description, but made a -sketch (found in an account of his travels, published in -London in 1788) which confirms the inferences drawn -from Hennepin’s narrative. The actual period of recession, -however (which Professor Winchell duly takes into -account), extends only to the year 1856, at which time -such artificial changes were introduced as to modify the -rate of recession and disturb further calculations. But -between 1680 and 1766 the falls had evidently receded -about 412 feet. Between 1766 and 1856 the recession -had been 600 feet. The average rate is estimated by -Professor Winchell to be about five feet per year, and the -total length of time required for the formation of the -gorge above Fort Snelling is a little less than eight thousand -years, or about the same as that calculated by Messrs. -Woodward and Gilbert for the Niagara gorge.</p> - -<p>To these calculations of Professor Winchell it does -not seem possible to urge any valid objection. It does -not seem credible that the amount of water in the Mississippi -should ever have been less than now, while during -the continuance of the ice in the upper portion of the -Mississippi basin the flow of water was certainly far greater -than now.</p> - -<p>If any one is inclined to challenge Professor Winchell’s -interpretation of the facts, even a hasty visit to -the locality will suffice to produce conviction. The comparative -youth of the gorge from Fort Snelling up to -Minneapolis is evident: 1. From its relative narrowness, -when compared with the main valley below. This is represented -by the shading upon the map. The gorge from -<span class="pagenum"><a name="Page_342" id="Page_342">« 342 »</a></span> -Fort Snelling up is not old enough to have permitted -much enlargement by the gradual undermining of the -superficial strata on either side, which slowly but constantly -goes on. 2. From the abruptness with which it merges -into the preglacial valley of the Minnesota-Mississippi. -The opening at Fort Snelling is not Y-shaped, as in gorges -where there has been indefinite time for the operation of -erosive agencies. 3. Furthermore, the precipices lining -the post-glacial gorge above Fort Snelling are far more -abrupt than those in the preglacial valley below, and they -give far less evidence of weathering. 4. Still, again, the -tributary streams, like the Minnehaha River, which empty -into the Mississippi between Fort Snelling and Minneapolis, -flow upon the surface, and have eroded gorges of -very limited extent; whereas, below Fort Snelling, the -small streams have usually either found underground -access to the river or occupy gorges of indefinite extent.</p> - -<p>The above estimates, setting such narrow limits to -post-glacial time in America, will seem surprising only to -those who have not carefully considered the glacial phenomena -of various kinds to be observed all over the glaciated -area. As already said, the glaciated portion of North -America is a region of waterfalls, caused by the filling up -of old channels with glacial <i>débris</i>, and the consequent -diversion of the water-courses. By this means the streams -in countless places have been forced to fall over precipices, -and to begin anew their work of erosion. Waterfalls -abound in the glaciated region because post-glacial -time is so short. Give these streams time enough, and -they will wear their way back to their sources, as the preglacial -streams had done over the same area, and as similar -streams have done outside the glaciated region. Upon -close observation, it will be found that the waterfalls in -America are nearly all post-glacial, and that their work of -erosion has been confined to a very limited time. A fair -example is to be seen at Elyria, Ohio, in the falls of Black -<span class="pagenum"><a name="Page_343" id="Page_343">« 343 »</a></span> -River, one of the small streams which empty into Lake -Erie from the south. Its post-glacial gorge, worn in -sandstone which overlies soft shale, is only about two -thousand feet in length, and it has as yet made no approach -toward a V-shaped outlet.</p> - -<p>The same impression of recent age is made by examining -the outlets of almost any of the lakes which dot the -glaciated area. The very reason of the continued existence -of these lakes is that they have not had time enough -to lower their outlets sufficiently to drain the water off, as -has been done in all the unglaciated region. In many -cases it is easy to see that the time during which this -process of lowering the outlets has been going on cannot -have been many thousand years.</p> - -<p>The same impression is made upon studying the evidences -of post-glacial valley erosion. Ordinary streams -constantly enlarge their troughs by impinging against the -banks now upon one side and now upon the other, and -transporting the material towards the sea. It is estimated -by Wallace that nine-tenths of the sedimentary material -borne along by rivers is gathered from the immediate -vicinity of its current, and goes to enlarge the trough of -the stream. Upon measuring the cubical contents of -many eroded troughs of streams in the glaciated region, -and applying the tables giving the average amount of -annual transportation of sediment by streams, we arrive -at nearly the same results as by the study of the recession -of post-glacial waterfalls.</p> - -<p>Professor L. E. Hicks, of Granville, Ohio, has published -the results of careful calculations made by him, concerning -the valley of Raccoon Creek in Licking County, Ohio.<a name="FNanchor_134" id="FNanchor_134"></a><a href="#Footnote_134" class="fnanchor">[ED]</a> -These show that fifteen thousand years would be more -than abundant time for the erosion of the immediate valley -adjoining that small stream. I have made and published -<span class="pagenum"><a name="Page_344" id="Page_344">« 344 »</a></span> -similar calculations concerning Plum Creek, at -Oberlin, in Lorain County, Ohio.<a name="FNanchor_135" id="FNanchor_135"></a><a href="#Footnote_135" class="fnanchor">[EE]</a> Like Raccoon Creek, -this has its entire bed in glacial deposits, and has had -nothing else to do since its birth but to enlarge its borders. -The drainage basin of the creek covers an area of -about twenty-five square miles. Its main trough averages -about twenty feet in depth by five hundred in width, along -a distance of about ten miles. From the rate at which -the stream is transporting sediment, it is incredible that -it could have been at work at this process more than ten -thousand years without producing greater results.</p> - -<div class="footnote"> - -<p><a name="Footnote_134" id="Footnote_134"></a><a href="#FNanchor_134"><span class="label">[ED]</span></a> See Baptist Quarterly for July. 1884.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_135" id="Footnote_135"></a><a href="#FNanchor_135"><span class="label">[EE]</span></a> See Ice Age in North America, p. 469.</p></div> - -<p>Calculations based upon the amount of sediment deposited -since the retreat of the ice-sheet point to a like -moderate conclusion. When one looks upon the turbid -water of a raging stream in time of flood, and considers -that all the sediment borne along will soon settle down -upon the bottom of the lake into which the stream -empties, he can but feel surprised that the “wash” of -the hills has not already filled up the depression of the -lake. It certainly would have done so had the present -condition of things existed for an indefinite period of -time.</p> - -<p>Naturally, while prosecuting the survey of the superficial -geology of Minnesota, Mr. Upham was greatly impressed -by the continued existence of the innumerable -lakelets that give such a charm to the scenery of that -State. Every day’s investigations added to the evidence -that the lapse of time since the Ice age must have been -comparatively brief, since, otherwise, the rains and streams -would have filled these basins with sediment, and cut outlets -low enough to drain them dry, for in many instances -he could see such changes slowly going forward.<a name="FNanchor_136" id="FNanchor_136"></a><a href="#Footnote_136" class="fnanchor">[EF]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_136" id="Footnote_136"></a><a href="#FNanchor_136"><span class="label">[EF]</span></a> Minnesota Geological Report for 1879, p. 73.</p> - -<p><span class="pagenum"><a name="Page_345" id="Page_345">« 345 »</a></span></p></div> - -<div class="fig_center" style="width: 467px;"> -<a id="fig107" name="fig107"></a> -<img src="images/fig_107.png" width="467" height="77" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 107.</span>—Section of kettle-hole near Pomp’s Pond, Andover, Massachusetts (see -text). (For general view of the situation, see <a href="#fig30">Fig. 30, p. 78</a>.)</div> -</div> - -<p>Some years ago I myself made a careful estimate of the -amount of deposition and vegetable accumulation which -had taken place in a kettle-hole near Pomp’s Pond, in -Andover, Mass. The diameter of the depression at the rim -was 276 feet. The inclination of the sides was such that -the extreme depression of the apex of the inverted cone -could not have been more than seventy feet; yet the -accumulation of peat and sediment only amounted to a -depth of seventeen feet. The total amount of material -which had accumulated would be represented by a cone -ninety-six feet in diameter at the base and seventeen feet -at the apex, which would equal only a deposit of about -five feet over the present surface of the bottom. It is -easy to see that ten thousand years is a liberal allowance -of time for the accumulation of five feet of sediment in -the bottom of an enclosure like a kettle-hole, for upon -examination it is clear that whatever insoluble material -gets into a kettle-hole must remain there, since there is -no possible way by which it can get out. Now five feet is -sixty inches, and if this amount has been six thousand -years in accumulating, that would represent a rate of an -inch in one hundred years, while, if it has been twelve -thousand years in accumulation, the rate will be only one -two-hundredth of an inch per year, a film so small as to be -almost inappreciable. If we may judge from appearance, -the result would not be much different in the case of the -tens of thousands of kettle-holes and lakelets which dot -the surface of the glaciated region.</p> - -<p>In the year 1869 Dr. E. Andrews, of Chicago, made -an important series of calculations concerning the rate -at which the waters of Lake Michigan are eating into the -<span class="pagenum"><a name="Page_346" id="Page_346">« 346 »</a></span> -shores and washing the sediment into deeper water or -towards the southern end of the lake. With reference to -the erosion of the shores, it appears from the work of the -United States Coast Survey that a shoulder, covered with -sixty feet of water, representing the depth at which wave-action -is efficient in erosion, extends outward from the -west shore a distance of about three miles, where the -sounding line reveals the shore of the deeper original -lake as it appeared upon the first withdrawal of the ice.</p> - -<p>From a variety of observations the average rate at -which the erosion of the bluffs is proceeding is found to -be such that the post-glacial time cannot be more than -ten thousand years, and probably not more than seven -thousand.</p> - -<p>An independent mode of calculating this period is -afforded by the accumulations of sand at the south end of -the lake, to which it is constantly drifting by the currents -of water propelled against the shores by the wind; for the -body of water in the lake is moving southward along the -shores towards the closed end in that direction, there being -a returning current along the middle of the lake. All -the railroads approaching Chicago from the east pass -through these sand deposits, and few of the observant -travellers passing over the routes can have failed to notice -the dunes into which the sand has been drifted by -the wind. Now, all the material of these dunes and sand-beaches -has been washed out of the bluffs to the northward -by the process already mentioned, and has been -slowly transferred by wave-action to its present position. -It is estimated that south of Chicago and Grand Haven, -this wave-transported sand amounts to 3,407,451,000 cubic -yards. This occupies a belt curving around the south end -about ten miles wide and one hundred miles long.</p> - -<p>The rate at which the sand is moving southward -along the shore is found by observing the amount annually -arrested by the piers at Chicago, Grand Haven, and -<span class="pagenum"><a name="Page_347" id="Page_347">« 347 »</a></span> -Michigan City. This equals 129,000 cubic yards for a year, -which can scarcely be more than one quarter or one fifth of -the total amount in motion. At this rate, the sand accumulations -at the southern end of the lake would have been -produced in a little less than seven thousand years.</p> - -<p>“If,” says Dr. Andrews, “we estimate the total annual -sand-drift at only twice the amount actually stopped by -the very imperfect piers built—which, in the opinion of -the engineers, is setting it far too low—and compare it -with the capacity of the clay-basin of Lake Michigan, we -shall find that, had this process continued one hundred -thousand years the whole south end of Lake Michigan, -up to the line connecting Chicago and Michigan City, -would have been full and converted into dry land twenty-five -thousand years ago, and the coast-line would now be -found many miles north of Chicago.”<a name="FNanchor_137" id="FNanchor_137"></a><a href="#Footnote_137" class="fnanchor">[EG]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_137" id="Footnote_137"></a><a href="#FNanchor_137"><span class="label">[EG]</span></a> Southall’s Recent Origin of Man, p. 502.</p></div> - -<p>It is proper to add a word in answer co an objection -which may arise in the reader’s mind, for it will doubtless -occur to some to ask why this sand which is washed out -by the waves from the bluffs is not carried inward towards -the deeper portion of the trough of the lake, thus producing -a waste which would partly counteract the forces of -accumulation at the south end. The answer is found in -the fact that the south end of Lake Michigan is closed, -and that the currents set in motion by the wind are such -that there is no off-shore motion sufficient to move sand, -and, as a matter of fact, dredgings show that the sand is -limited to the vicinity of the shore.</p> - -<p>By comparing the eroded cliffs upon Michigan and the -other Great Lakes with what occurs in similar situations -about the glacial Lake Agassiz, we obtain an interesting -means of estimating the comparative length of time occupied -by the ice-front in receding from the Canadian border -to Hudson Bay.</p> - -<p><span class="pagenum"><a name="Page_348" id="Page_348">« 348 »</a></span></p> - -<p>As we have seen, Lake Agassiz occupied a position -quite similar in most respects to Lake Michigan. Its -longest diameter was north and south, and the same forces -which have eroded the cliffs of Lake Michigan and piled -up sand-dunes at its southern end would have produced -similar effects upon the shores of Lake Agassiz, had its -continuance been anywhere near as long as that of the -present Lake Michigan has been. But, according to Mr. -Upham, who has most carefully surveyed the whole region, -there are nowhere on the shores of the old Lake Agassiz -any evidence of eroded cliffs at all to be compared with -those found upon the present Great Lakes, while there is -almost an entire lack of sand deposits about the south end -such as characterise the shore of Lake Michigan. “The -great tracts of dunes about the south end of Lake Michigan -belong,” as Upham well observes, “wholly to beach accumulations, -being sand derived from erosion of the western -and eastern shores of the lake.... But none of the -beaches of our glacial lakes are large enough to make -dunes like those on Lake Michigan, though the size and -depth of Lake Agassiz, its great extent from north to -south, and the character of its shores, seem equally favorable -for their accumulation. It is thus again indicated -that the time occupied by the recession of the ice-sheet -was comparatively brief.”<a name="FNanchor_138" id="FNanchor_138"></a><a href="#Footnote_138" class="fnanchor">[EH]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_138" id="Footnote_138"></a><a href="#FNanchor_138"><span class="label">[EH]</span></a> Proceedings of the Boston Society of Natural History, vol. -xxiv, p. 454; Upham’s Glacial Lakes in Canada, in Bulletin of the -Geological Society of America, vol. ii, p. 248.</p></div> - -<p>From Mr. Upham’s conclusions it would seem that if -ten thousand years be allowed for the post-glacial existence -of Lake Michigan, one tenth of that period would be more -than sufficient to account for the cliffs, deltas, beaches, -and other analogous phenomena about Lake Agassiz. In -other words, the duration of Lake Agassiz could not have -been more than a thousand years, which gives us a measure -<span class="pagenum"><a name="Page_349" id="Page_349">« 349 »</a></span> -of the rate at which the recession of the ice-front went -on after it had withdrawn to the international boundary. -The distance from there to the mouth of Nelson River is -about 600 miles. The recession of the ice-front over that -area proceeded, therefore, at the average rate of about -half a mile per year.</p> - -<p>There are many evidences that the main period of -glaciation west of the Rocky Mountains was considerably -later than that in the eastern part of the continent. A -portion of the facts pointing to this conclusion have been -well stated by Mr. George F. Becker, of the United States -Geological Survey.</p> - -<p>“No one,” he says, “who has examined the glaciated -regions of the Sierra can doubt that the great mass of the -ice disappeared at a very recent period. The immense areas -of polished surfaces fully exposed to the severe climate of -say from 7,000 to 12,000 feet altitude, the insensible erosion -of streams running over glaciated rocks, and the freshness -of erratic boulders are sufficient evidence of this. -There is also evidence that the glaciation began at no very -distant geologic date. As Professor Whitney pointed out, -glaciation is the last important geological phenomenon -and succeeded the great lava flows. There is also much -evidence that erosion has been trifling since the commencement -of glaciation, excepting under peculiar circumstances. -East of the range, for example, at Virginia City, -andesites which there is every reason to suppose preglacial -have scarcely suffered at all from erosion, so that depressions -down which water runs at every shower are not -yet marked with water-courses, while older rocks, even of -Tertiary age and close by, are deeply carved. The rainfall -at Virginia City is, to be sure, only about ten inches, so -that rock would erode only say one third as fast as on the -California coast; but even when full allowance is made -for this difference, it is clear that these andesites must be -much younger than the commencement of glaciation in -<span class="pagenum"><a name="Page_350" id="Page_350">« 350 »</a></span> -the northeastern portion of the continent as usually estimated. -So, too, the andesites near Clear Lake, in California, -though beyond a doubt preglacial, have suffered -little erosion, and one of the masses, Mount Konocti (or -Uncle Sam), has nearly as characteristic a volcanic form -as Mount Vesuvius.”<a name="FNanchor_139" id="FNanchor_139"></a><a href="#Footnote_139" class="fnanchor">[EI]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_139" id="Footnote_139"></a><a href="#FNanchor_139"><span class="label">[EI]</span></a> Bulletin of the Geological Society of America, vol. ii, pp. 196, -197.</p></div> - -<p>This view of Mr. Becker is amply sustained by many -other obvious facts, some of which may be easily observed -by tourists who visit the Yosemite Park. The freedom of -the abutting walls of this cañon from talus, as well as the -freshness of the glacial scratches upon both the walls and -the floor of the tributary cañons, all indicate a lapse of -centuries only, rather than of thousands of years, since -their occupation by glacial ice.</p> - -<p>The freshness of the high-level terraces surrounding the -valleys of Great Salt Lake, in Utah, and of Pyramid and -North Carson Lakes, in Nevada, and the small amount of -erosion which has taken place since the formation of -these terraces, point in the same direction—namely, to a -very recent date for the glaciation of the Pacific coast.</p> - -<p>We have already detailed the facts concerning the formation -of these terraces and the evidence of their probable -connection with the Glacial period. It is sufficient, therefore, -here to add that, according to Mr. Russell and Mr. -Gilbert (two of the most eminent members of the United -States Geological Survey, who have each published monographs -minutely embodying the results of their extensive -observations in this region), the erosion of present streams -in the beds which were deposited during the enlargement of -the lakes is very slight, and the modification of the shores -since the formation of the high terraces has been insignificant.</p> - -<p>According to Mr. Gilbert: "The Bonneville shores -<span class="pagenum"><a name="Page_351" id="Page_351">« 351 »</a></span> -are almost unmodified. Intersecting streams, it is true, -have scored them and interrupted their continuity for -brief spaces; but the beating of the rain has hardly left a -trace. The sea-cliffs still stand as they first stood, except -that frost has wrought upon their faces so as to crumble -away a portion and make a low talus at the base. The -embankments and beaches and bars are almost as perfect -as though the lake had left them yesterday, and many of -them rival in the symmetry and perfection of their contours -the most elaborate work of the engineer. There -are places where boulders of quartzite or other enduring -rock still retain the smooth, glistening surfaces which the -waves scoured upon them by clashing against them the -sands of the beach.</p> - -<p>“When this preservation is compared with that of the -lowest Tertiary rocks of the region—the Pliocene beds to -which King has given the name Humboldt—the difference -is most impressive. The Pliocene shore-lines have -disappeared.</p> - -<p>“The deposits are so indurated as to serve for building-stone. -They have been upturned in many places by the -uplifting of mountains. Elsewhere they have been divided -by faults, and the fragments, dissevered from their continuation -in the valley, have been carried high up on the -mountain-flanks, where erosion has carved them in typical -mountain forms.... The date of the Bonneville -flood is the geologic yesterday, and, calling it yesterday, we -may without exaggeration refer the Pliocene of Utah to -the last decade; the Eocene of the Colorado basin to the -last century, and relegate the laying of the Potsdam sandstone -to prehistoric times.”<a name="FNanchor_140" id="FNanchor_140"></a><a href="#Footnote_140" class="fnanchor">[EJ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_140" id="Footnote_140"></a><a href="#FNanchor_140"><span class="label">[EJ]</span></a> Second Annual Report of the United States Geological Survey, -p. 188.</p></div> - -<p>Mr. Russell adds to this class of evidence that of the -small extent to which the glacial striæ have been effaced -<span class="pagenum"><a name="Page_352" id="Page_352">« 352 »</a></span> -since the withdrawal of the ice from the borders of these -old lakes: “The smooth surfaces are still scored with fine, -hair-like lines, and the eye fails to detect more than a -trace of disintegration that has taken place since the surfaces -received their polish and striation.... It seems -reasonable to conclude that in a severe climate like that -of the high Sierra it” (the polish) “could not remain unimpaired -for more than a few centuries at the most.”<a name="FNanchor_141" id="FNanchor_141"></a><a href="#Footnote_141" class="fnanchor">[EK]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_141" id="Footnote_141"></a><a href="#FNanchor_141"><span class="label">[EK]</span></a> See also Mr. Upham in American Journal of Science, vol. xli, -pp. 41, 51.</p></div> - -<p>Europe does not seem to furnish so favourable opportunities -as America for estimating the date of the Glacial -period; still it is not altogether wanting in data bearing -upon the subject.</p> - -<p>Some of the caves in which palæolithic implements -were found associated with the bones of extinct animals -in southern England contain floors of stalagmite which -have been thought by some to furnish a measure of the -time separating the deposits underneath from those above. -This is specially true in the case of Kent’s Cavern, near -Torquay, which contains two floors of stalagmite, the -upper one almost continuous and varying in thickness -from sixteen inches to five feet, the lower one being in -places twelve feet thick, underneath which human implements -were found.</p> - -<p>But it is difficult to determine the rate at which stalagmite -accumulates. As is well known, this deposit is a -form of carbonate of lime, and accumulates when water -holding the substance in solution drops down upon the -surface, where it is partially evaporated. It then leaves a -thin film of the substance upon the floor. The rate of the -accumulation will depend upon both the degree to which -the water is saturated with the carbonate and upon the -quantity of the water which percolates through the roof -of the cavern. These factors are so variable, and so dependent -<span class="pagenum"><a name="Page_353" id="Page_353">« 353 »</a></span> -upon unknown conditions in the past, that it is -very difficult to estimate the result for any long period of -time. Occasionally a quarter of an inch of stalagmite -accretion has been known to take place in a cavern in a -single year, while in Kent’s Cavern, over a visitor’s name -inscribed in the year 1688, a film of stalagmite only a -twentieth of an inch in thickness has accumulated. If, -therefore, we could reckon upon a uniformity of conditions -stretching indefinitely back into the past, we could determine -the age of these oldest remains of man in Kent’s -Hole by a simple sum in arithmetic, and should infer that -the upper layer of stalagmite required 240,000 years, and -the lower 576,000 years, for their growth, which would -carry us back more than 700,000 years, and some have not -hesitated to affix as early a date as this to these lowest -implement-bearing gravels.</p> - -<p>But other portions of the cave show an actual rate of -accretion very much larger. Six inches of stalagmite is -there found overlying some remains of Romano-Saxon -times which cannot be more than 2,000 years old. Assuming -this as the uniform rate, the total time required -for the deposit of the stalagmitic floors would still be about -70,000 years. But, as we have seen, the present rates of -deposition are probably considerably less than those which -took place during the moister climate of the Glacial epoch. -Still, even by supposing the rate to be increased fourfold, -the age of this lower stratum would be reduced to only -12,000 years. So that, as Mr. James Geikie well maintains, -“Even on the most extravagant assumption as to -the former rate of stalagmitic accretion, we shall yet be -compelled to admit a period of many thousands of years -for the formation of the stalagmitic pavements in Kent’s -Cavern.”<a name="FNanchor_142" id="FNanchor_142"></a><a href="#Footnote_142" class="fnanchor">[EL]</a> We should add, however, that there is much -well-founded doubt whether the implements found in the -<span class="pagenum"><a name="Page_354" id="Page_354">« 354 »</a></span> -lowest stratum were really in place, since, according to -Dr. Evans, “Owing to previous excavations and to the -presence of burrowing animals, the remains from above -and below the stalagmite have become intermingled.”<a name="FNanchor_143" id="FNanchor_143"></a><a href="#Footnote_143" class="fnanchor">[EM]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_142" id="Footnote_142"></a><a href="#FNanchor_142"><span class="label">[EL]</span></a> Prehistoric Europe, p. 83.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_143" id="Footnote_143"></a><a href="#FNanchor_143"><span class="label">[EM]</span></a> Stone and Flint Implements, p. 446.</p></div> - -<p>An attempt was made by M. Morlot in Switzerland to -obtain the chronology of the Glacial period by studying -the deltas of the streams descending the glaciated valleys. -He paid special attention to that of the Tinière, a stream -which flows into Lake Geneva near Villeneuve. The -modern delta of this stream consists of gravel and sand -deposited in the shape of a flattened cone, and investigations -upon it were facilitated by a long railroad cutting -through it. “Three layers of vegetable soil, each of which -must at one time have formed the surface of the cone, -have been cut through at different depths.”<a name="FNanchor_144" id="FNanchor_144"></a><a href="#Footnote_144" class="fnanchor">[EN]</a> In the -upper stratum Roman tiles and a coin were found; in the -second stratum, unvarnished pottery and implements of -bronze; while in the lower stratum, at a depth of nineteen -feet from the surface, a human skull was found, to which -Morlot assigned an age of from 5,000 to 7,000 years.</p> - -<div class="footnote"> - -<p><a name="Footnote_144" id="Footnote_144"></a><a href="#FNanchor_144"><span class="label">[EN]</span></a> Lyell’s Antiquity of Man, p. 28.</p></div> - -<p>But Dr. Andrews, after carefully revising the data, felt -confident that the time required for the whole deposit of -this lower delta was not more than 5,000 years, and that -the oldest human remains in it, which were about half -way from between the base and the surface of the cone, -were probably not more than 3,000 years old.</p> - -<p>Still, the significance of this estimate principally arises -from the relation of the modern delta to older deltas connected -with the Glacial period. Above this modern delta, -formed by the river in its present proportions, there is -another, more ancient, about ten times as large, whose accumulation -doubtless took place upon the final retreat of -the ice from Lake Geneva. No remains of man have been -<span class="pagenum"><a name="Page_355" id="Page_355">« 355 »</a></span> -found in this, but it doubtless corresponds in age with the -high-level gravels in the valley of the Somme, in which -the remains of man and the mammoth, together with -other extinct animals, have been found.</p> - -<p>We do not see, however, that any very definite calculation -can be made concerning the time required for its -deposition. Lyell was inclined to consider it ten times as -old as the modern delta, simply upon the ground of its -being ten times as large. On Morlot’s estimate of the age -of the modern delta, therefore, the retreat of the ice whose -melting torrents deposited the upper delta would be fixed -at 100,000 years ago, and upon Dr. Andrews’s calculation, -at about 20,000.</p> - -<p>But it is evident that the problem is not one of simple -multiplication. The floods of water which accompanied -the melting back of the ice from the upper portions of -this valley must have been immensely larger than those -of the present streams, and their transporting power immensely -greater still. Hence we do not see that any conclusions -can be drawn from the deltas of the Tinière to -give countenance to extreme views concerning the date of -the close of the Glacial period.<a name="FNanchor_145" id="FNanchor_145"></a><a href="#Footnote_145" class="fnanchor">[EO]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_145" id="Footnote_145"></a><a href="#FNanchor_145"><span class="label">[EO]</span></a> Lyell’s Antiquity of Man, p. 321.</p></div> - -<p>In the valley of the Somme the chronological data -relating to the Glacial period, and indicating a great antiquity -for man, have been thought to be more distinct -than anywhere else in Europe. As already stated, it is -the prevalent opinion that since man first entered the -valley, in connection with the mammoth and the other -extinct animals characteristic of the Glacial period, the -trough of the Somme, about a mile in width and a hundred -feet in depth, has been eroded by the drainage of its -present valley. An extensive accumulation of peat also -has taken place along the bottom of the trough of the -river since it was originally eroded to its present level. -<span class="pagenum"><a name="Page_356" id="Page_356">« 356 »</a></span> -This substance occurs all along the bottom of the valley -from far above Amiens to the sea, and is in some places -more than thirty feet in depth. The animal and vegetable -remains in it all belong to species now inhabiting -Europe.</p> - -<p>The depth of the peat indicates that when it was -formed the land stood at a slightly higher elevation than -now, for the base of the stratum is now below the sea-level, -while the peat is of fresh-water origin, and, according -to Dr. Andrews,<a name="FNanchor_146" id="FNanchor_146"></a><a href="#Footnote_146" class="fnanchor">[EP]</a> is formed from the vegetable accumulations -connected with forest growths. When, therefore, -the country was covered with forests, as it was in -prehistoric times, the accumulation must have proceeded -with considerable rapidity. This inference is confirmed -by the occurrence in the peat of prostrate trunks of oak, -four feet in diameter, so sound that they were manufactured -into furniture. The stumps of trees, especially of -the birch and alder, were also found in considerable number, -standing erect where they grew, sometimes to a height -of three feet. Now, as Dr. Andrews well remarks, it is -evident that, in order to prevent these stumps and prostrate -trunks from complete decay, the accumulation of -peat must have been rapid. From certain Roman remains -found six feet and more beneath the surface, he estimates -that the accumulation since the Roman occupation has -been as much as six inches a century, at which rate the -whole would take place in somewhat over 5,000 years.</p> - -<div class="footnote"> - -<p><a name="Footnote_146" id="Footnote_146"></a><a href="#FNanchor_146"><span class="label">[EP]</span></a> American Journal of Science, October, 1868.</p></div> - -<p>Still, if we accept this estimate, we have obtained but -a starting-point from which to estimate the age of the -high-level gravels in which palæolithic implements were -found; for, if we accept the ordinary theory, we must add -to this the time required for the river to lower its bed -from eighty to a hundred feet, and to carry out to the sea -the contents of its wide trough. But, as already shown, -<span class="pagenum"><a name="Page_357" id="Page_357">« 357 »</a></span> -the Glacial period was, even in the north of France, a -time of great precipitation and of a considerable degree of -cold, when ice formed to a much greater extent than now -upon the surface of the Somme. The direct evidence of -this consists in the boulders mingled with the high-level -gravel which are of such size as to require floating ice for -their transportation.</p> - -<p>In addition to the natural increase in the eroding -power of the Somme brought about by the increase in its -volume, on account of the greater precipitation in the -Glacial age, there would also be, as Prestwich has well -shown, a great increase in rate through the action of -ground-ice, which plays a very important part in the river -erosion of arctic countries, and in all probability did so -during the Glacial period in the valley of the Somme.</p> - -<p>“When the water is reduced to and below 32° Fahr., -although the rapid motion may prevent freezing on the -surface for a time, any pointed surfaces at the bottom of -the river, such as stones and boulders, will determine (as -is the case with a saturated saline solution) a sort of crystallisation, -needles of ice being formed, which gradually -extend from stone to stone and envelop the bodies with -which they are in contact. By this means the whole surface -of a gravelly river-bed may become coated with ice, -which, on a change of temperature, or of atmospheric -pressure, or on acquiring certain dimensions and buoyancy, -rises to the surface, bringing with it the loose materials to -which it adhered. Colonel Jackson remarks, in speaking -of this bottom-ice, that ‘it frequently happens that these -pieces, in rising from the bottom, bring up with them -sand and stones, which are thus transported by the current.... -When the thaw sets in the ice, becoming rotten, -lets fall the gravel and stones in places far distant -from those whence they came.’</p> - -<p>“Again, Baron Wrangell remarks that, ‘in all the more -rapid and rocky streams of this district [northern Siberia]<span class="pagenum"><a name="Page_358" id="Page_358">« 358 »</a></span> -the formation of ice takes place in two different manners; -a thin crust spreads itself along the banks and over the -smaller bays where the current is least rapid; but the -greater part is formed in the bed of the river, in the hollows -among the stones, where the weeds give it the appearance -of a greenish mud. As soon as a piece of ice of this -kind attains a certain size, it is detached from the ground -and raised to the surface by the greater specific gravity of -the water; these masses, containing a quantity of gravel -and weeds, unite and consolidate, and in a few hours the -river becomes passable in sledges instead of in boats.’ -Similar observations have been made in America; but -instances need not be multiplied, as it is a common phenomenon -in all arctic countries, and is not uncommon on -a small scale even in our latitudes.</p> - -<p>“The two causes combined—torrential river-floods and -rafts of ground-ice, together with the rapid wear of the -river cliffs by frost—constituted elements of destruction -and erosion of which our present rivers can give a very -inadequate conception; and the excavations of the valleys -must have proceeded with a rapidity with which the present -rate of erosion cannot be compared; and estimates of -time founded on this, like those before mentioned on surface -denudation, are therefore not to be relied upon.”<a name="FNanchor_147" id="FNanchor_147"></a><a href="#Footnote_147" class="fnanchor">[EQ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_147" id="Footnote_147"></a><a href="#FNanchor_147"><span class="label">[EQ]</span></a> Prestwich’s Geology, vol. ii, pp. 471, 472.</p></div> - -<p>Speaking a little later of taking the present rates of -river erosion as a standard to estimate the chronology of -the Glacial period, the same high authority remarks: "It -no more affords a true and sufficient guide than it would -be to take the tottering paces and weakened force of an -old man as the measure of what that individual was, and -what he could do, in his robust and active youth. It may -be right to take the effects at present produced by a given -power as the known quantity, a, but it is equally indispensable, -in all calculations relative to the degree of those -<span class="pagenum"><a name="Page_359" id="Page_359">« 359 »</a></span> -forces in past times, to take notice of the unknown quantity, -x, although this, in the absence of actual experience, -which cannot be had, can only be estimated by the results -and by a knowledge of the contemporaneous physical conditions. -It may be a complicated equation, but it is not -to be avoided.<a name="FNanchor_148" id="FNanchor_148"></a><a href="#Footnote_148" class="fnanchor">[ER]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_148" id="Footnote_148"></a><a href="#FNanchor_148"><span class="label">[ER]</span></a> Prestwich’s Geology, vol. ii, pp. 520, 521.</p></div> - -<p>“In this country and in the north of France broad valleys -have been excavated to the depth of from about eighty -to a hundred and fifty feet in glacial and post-glacial times. -Difficult as it is by our present experience to conceive this -to have been effected in a comparatively short geological -term, it is equally, and to my mind more, difficult to suppose -that man could have existed eighty thousand years -or more, and that existing forms of our fauna and flora -should have survived during two hundred and forty thousand -years without modification or change.”<a name="FNanchor_149" id="FNanchor_149"></a><a href="#Footnote_149" class="fnanchor">[ES]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_149" id="Footnote_149"></a><a href="#FNanchor_149"><span class="label">[ES]</span></a> Ibid., p. 533.</p></div> - -<p>The discussion of the age of the high-level river gravels -of the Somme and other streams in northwestern Europe -is not complete, however, without considering another -possibility as to the mode of their deposition. The conclusion -to which Mr. Alfred Tylor arrived, after a prolonged -and careful study of the subject, was that the main -valleys of the Somme and other streams in northern France -and southern England were preglacial in their origin, and -that the accumulations of gravel at high levels along their -margin were due to enormous floods which characterised -the closing portion of the great ice age, which he denominated -the pluvial period.<a name="FNanchor_150" id="FNanchor_150"></a><a href="#Footnote_150" class="fnanchor">[ET]</a> The credibility of floods large -enough to accomplish the results manifest in the valley -of the Somme is supported by reference to a flood which -occurred on the Mulleer River, in India, in 1856, when a -<span class="pagenum"><a name="Page_360" id="Page_360">« 360 »</a></span> -stream, which is usually insignificant, was so swollen by a -rainfall of a single day that it rose high enough to sweep -away an iron bridge the bottoms of whose girders were -sixty-five feet above high-water mark. One iron girder -weighing eighty tons was carried two miles down the -river, and nearly buried in sand. The significance of -these facts is enhanced by observing also that for fifteen -miles above the bridge the fall of the river only averaged -ten feet per mile. Floods to this extent are not uncommon -in India. During the Glacial period spring freshets, -must have been greatly increased by the melting of a large -amount of snow and ice which had accumulated during -the winter, and also by the formation of ice-gorges near -the mouths of many of the streams. It is probable, also, -that the accumulation of ice across the northern part of -the German Ocean may have permanently flooded the -streams entering that body of water; for it is by no means -improbable that there was a land connection between -England and France across the Straits of Dover until -after the climax of the Glacial period. In support of his -theory, Mr. Tylor points to the fact “that the gravel in -the valley of the Somme at Amiens is partly derived from -<i>débris</i> brought down by the river Somme and by the two -rivers the Celle and the Arve, and partly consists of material -from the adjoining higher grounds washed in by -land floods,” and that the “Quaternary gravels of the -Somme are not separated into two divisions by an escarpment -of chalk parallel to the river,” but “thin out gradually -as they slope from the high land down to the Somme.”</p> - -<p>Mr. Tylor’s reasoning seems especially cogent to one -who stands on the ground where he can observe the size -of the valley and the diminutive proportions of the present -stream. Even if we do not grant all that is claimed by -Mr. Tylor, it is difficult to resist the main force of his -argument, and to avoid the conclusion that the valley of -the Somme is largely the work of preglacial erosion, and -has been, at any rate, only in slight degree deepened and -enlarged during post-Tertiary time.</p> - -<div class="footnote"> - -<p><a name="Footnote_150" id="Footnote_150"></a><a href="#FNanchor_150"><span class="label">[ET]</span></a> Proceedings of the Geological Society, London, November 8, -1867, pp. 103-126: Quarterly Journal of the Geological Society, -February 1, 1869, pp. 57-100.</p> - -<p><span class="pagenum"><a name="Page_361" id="Page_361">« 361 »</a></span></p></div> - - -<p>Summary.</p> - -<p>In briefly summarising our conclusions concerning the -question of man’s antiquity as affected by his known relations -to the Glacial period, it is important, first, to remark -upon the changes of opinion which have taken place -with respect to geological time within the past generation. -Under the sway of Sir Charles Lyell’s uniformitarian -ideas, geologists felt themselves at liberty to regard geological -time as practically unlimited, and did not hesitate -to refer the origin of life upon the globe back to a -period of 500,000,000 years. In the first edition of his -Origin of Species Charles Darwin estimated that the time -required for the erosion of the Wealden deposits in England -was 306,662,400 years, which he spoke of as “a mere -trifle” of that at command for establishing his theory of -the origin of species through natural selection. In his -second edition, however, he confesses that his original -statement concerning the length of geological time was -rash; while in later editions he quietly omitted it.</p> - -<p>Meanwhile astronomers and physicists have been gradually -setting limits to geological time until they have now -reached conclusions strikingly in contrast with those held -by the mass of English geologists forty years ago. Mr. -George H. Darwin, Professor of Mathematics at Cambridge -University, has from a series of intricate calculations -shown that between fifty and one hundred million -years ago the earth was revolving from six to eight times -faster than now, and that the moon then almost touched -the earth, and revolved about it once every three or four -hours. From this proximity of the moon to the earth, it -would result that if the oceans had been then in existence -the tides would have been two hundred times as great as -now, creating a wave six hundred feet in height, which -<span class="pagenum"><a name="Page_362" id="Page_362">« 362 »</a></span> -would sweep around the world every four hours. Such a -condition of things would evidently be incompatible with -geological life, and geology must limit itself to a period -which is inside of 100,000,000 years. Sir William Thomson -and Professor Tait, of Great Britain, and Professor -Newcomb, of the United States Naval Observatory, approaching -the question from another point of view, seem -to demonstrate that the radiation of heat from the sun -is diminishing at a rate such that ten or twelve million -years ago it must have been so hot upon the earth’s surface -as to vaporise all the water, and thus render impossible -the beginning of geological life until later than that -period. Indeed, they seem to prove by rigorous mathematical -calculations that the total amount of heat originally -possessed by the nebula out of which the sun has -been condensed would only be sufficient to keep up the -present amount of radiation for 18,000,000 years.</p> - -<p>The late Dr. Croll, feeling the force of these astronomical -conclusions, thought it possible to add sufficiently -to the sun’s heat to extend its rule backwards approximately -100,000,000 years by the supposition of a collision -with it of another moving body of near its own -size. Professor Young and others have thought that possibly -the heat of the sun might have been kept up by the -aid of the impact of asteroids and meteorites for a period -of 30,000,000 years. Mr. Wallace obtains similar figures -by estimating the time required for the deposition of -the stratified rocks open to examination upon the land -surface of the globe. As a result of his estimates, it -would appear that 28,000,000 years is all the time required -for the formation of the geological strata. From -all this it is evident that geologists are much more restricted -in their speculations involving time than they -thought themselves to be a half-century ago. Taking as -our standard the medium results attained by Wallace, we -shall find it profitable to see how this time can be portioned -<span class="pagenum"><a name="Page_363" id="Page_363">« 363 »</a></span> -out to the geological periods, that we may ascertain -how much approximately can be left for the Glacial -epoch.</p> - -<p>On all hands it is agreed that the geological periods -decrease in length as they approach the present time. -According to Dana’s estimates,<a name="FNanchor_151" id="FNanchor_151"></a><a href="#Footnote_151" class="fnanchor">[EU]</a> the “ratio for the Palæozoic, -Mesozoic, and Cenozoic periods would be 12:3:1”—that -is, Cenozoic time is but one sixteenth of the whole. -This embraces the whole of the Tertiary period, during -which placental mammals have been in existence, together -with the post-Tertiary or Glacial period, extending -down to the present time; that is, the time since the -beginning of the Tertiary period and the existence of the -higher animals is considerably less than two million years, -even upon Mr. Wallace’s basis of calculation. But if we -should be compelled to accept the calculations of Sir -William Thomson, Professor Tait, and Professor Newcomb, -the Cenozoic period would be reduced to considerably -less than one million years. It is difficult to tell how -much of Cenozoic time is to be assigned to the Glacial -period, since there is, in fact, no sharply drawn line between -the two periods. The climax of the Glacial period -represented a condition of things slowly attained by the -changes of level which took place during the latter part -of the Tertiary epoch.</p> - -<div class="footnote"> - -<p><a name="Footnote_151" id="Footnote_151"></a><a href="#FNanchor_151"><span class="label">[EU]</span></a> See revised edition of his Geology, p. 586.</p></div> - -<p>In order to estimate the degree of credibility with -which we may at the outset regard the theory of Mr. -Prestwich and others, that all the phenomena of the Glacial -period can be brought within the limits of thirty or -forty thousand years, it is important to fix our minds -upon the significance of the large numbers with which we -are accustomed to multiply and divide geological quantities.<a name="FNanchor_152" id="FNanchor_152"></a><a href="#Footnote_152" class="fnanchor">[EV]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_152" id="Footnote_152"></a><a href="#FNanchor_152"><span class="label">[EV]</span></a> See Croll’s Climate and Time, chap. xx.</p> - -<p><span class="pagenum"><a name="Page_364" id="Page_364">« 364 »</a></span></p></div> - -<p>Few people realise either the rapidity with which geological -changes are now proceeding or the small amount -of change which might produce a Glacial period, and -fewer still have an adequate conception of how long a -period a million years is, and how much present geological -agencies would accomplish in that time. At the present -rate at which erosive agencies are now acting upon the -Alps, their dimensions would be reduced one half in a -million years. At the present rate of the recession of -the Falls of St. Anthony, the whole gorge from St. Louis -to Minneapolis would have been produced in a million -years. A river lowering its bed a foot in a thousand -years would produce a cañon a thousand feet deep in a -million years.</p> - -<p>If we suppose the Glacial period to have been brought -about by an elevation of land in northern America and -northern Europe, proceeding at the rate of three feet a -century, which is that now taking place in some portions -of Scandinavia, this would amount to three thousand feet -in one hundred thousand years, and that is probably all, -and even more than all, which is needed. One hundred -thousand years, therefore, or even less, might easily include -both the slow coming on of the Glacial period and its -rapid close. Prestwich estimates that the ice now floating -away from Greenland as icebergs is sufficient if accumulating -on a land-surface to extend the borders of a -continental glacier about four hundred and fifty feet a -year, or one mile in twelve years, one hundred miles in -twelve hundred years, and seven hundred miles (about the -limit of glacial transportation in America) in less than ten -thousand years.</p> - -<p>After making all reasonable allowances, therefore, -Prestwich’s conclusion that twenty-five thousand years is -ample time to allow to the reign of the ice of the Glacial -period cannot be regarded as by any means incredible or, -on <i>a priori</i> grounds, improbable.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_365" id="Page_365">« 365 »</a></span></p> - - - - -<p class="caption2"><a name="APPENDIX" id="APPENDIX">APPENDIX.</a></p> - -<p class="caption2">THE TERTIARY MAN.</p> - -<p class="caption3">By Professor Henry W. Haynes.</p> - -<p>“It must not be imagined that it is in any way proved -that the Palæolithic man was the first human being that existed. -We must be prepared to wait, however, for further -and better authenticated discoveries before carrying his existence -back in time further than the Pleistocene or post-Tertiary -period.”<a name="FNanchor_153" id="FNanchor_153"></a><a href="#Footnote_153" class="fnanchor">[EW]</a> This was the position assumed more than -twelve years ago by the eminent English geologist and -archæologist, Dr. John Evans, and it was still maintained in -his address before the Anthropological Section of the British -Association on September 18, 1890. I believe that the study -of all the evidence in favor of the existence of the Tertiary -man that has been brought forward down to the present -time will leave the question in precisely the same state of -uncertainty.</p> - -<div class="footnote"> - -<p><a name="Footnote_153" id="Footnote_153"></a><a href="#FNanchor_153"><span class="label">[EW]</span></a> <i>A Few Words on Tertiary Man</i>, Trans, of Hertfordshire Nat. -Hist. Soc, vol. i, p. 150.</p></div> - -<p>“In order to establish the existence of man at such a remote -period the proofs must be convincing. It must be -shown, first, that the objects found are of human workmanship; -secondly, that they are really found as stated; and, -thirdly, the age of the beds in which they are found must be -clearly ascertained and determined.”<a name="FNanchor_154" id="FNanchor_154"></a><a href="#Footnote_154" class="fnanchor">[EX]</a> These tests I propose -to apply to the evidence for the Tertiary man recently brought -<span class="pagenum"><a name="Page_366" id="Page_366">« 366 »</a></span> -forward in Europe, and then to consider the significance of -certain discoveries on the Pacific coast of our own continent.</p> - -<div class="footnote"> - -<p><a name="Footnote_154" id="Footnote_154"></a><a href="#FNanchor_154"><span class="label">[EX]</span></a> Ibid., p. 148.</p></div> - -<p>Tertiary deposits in Europe are alleged to have supplied -three sorts of evidence of this fact: <i>First</i>, the bones of man -himself; <i>second</i>, bones of animals showing incisions or -fractures supposed to have been produced by human -agency; <i>third</i>, chipped flints believed to exhibit marks of -design in their production.</p> - -<p>A very complete survey of the question of the antiquity -of man was published in 1883 by M. Gabriel de Mortillet, -one of its most eminent investigators, under the title of Le -Préhistorique. In that work he subjected to a most rigid -examination all the evidence for Tertiary man, coming under -either of these three heads, that had been brought forward -up to that date.</p> - -<p>The instances of the discovery of human bones in Europe -were two—at Colle del Vento, in Savona, and Castenedolo, -near Brescia, both in Italy. At the former site, in a Pliocene -marine deposit abounding in fossil oysters and containing -some <i>scattered</i> bones of fossil mammals, a human skeleton -was found <i>with the bones lying in their natural connection</i>. -Mortillet, however, and many others regard this as an instance -of a subsequent interment rather than as proof that -the man lived in Pliocene times.<a name="FNanchor_155" id="FNanchor_155"></a><a href="#Footnote_155" class="fnanchor">[EY]</a> At Castenedolo, in a -similar marine Pliocene formation, on three different occasions -human skeletons have been discovered, but in different -strata. One investigator has accounted for these as the result -of a shipwreck in the Pliocene period. This bold -hypothesis not only requires that man should have been -sufficiently advanced at that very remote period to have -navigated the sea, but it calls for two shipwrecks, at different -times, at the same point. It has, however, since been abandoned -by its author in favor of the presumption of subsequent -interments, as in the previous instance.<a name="FNanchor_156" id="FNanchor_156"></a><a href="#Footnote_156" class="fnanchor">[EZ]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_155" id="Footnote_155"></a><a href="#FNanchor_155"><span class="label">[EY]</span></a> This is also the opinion of Hamy, <i>Précis de Paléontologie Humaine</i>, -p. 67. Professor Le Conte, <i>Elements of Geology</i> (third edition, -1891), p. 609, is wrong in attributing the opposite conclusion to -Hamy, on the evidence of “flint implements found in this locality.”</p></div> - -<div class="footnote"> - -<p><a name="Footnote_156" id="Footnote_156"></a><a href="#FNanchor_156"><span class="label">[EZ]</span></a> Bullettino di Paletnologia Italiana, tome xv, p. 109 (August -18, 1889).</p> - -<p><span class="pagenum"><a name="Page_367" id="Page_367">« 367 »</a></span></p></div> - -<p>Animal bones showing cuts or breaks supposed to be the -work of man have been found in seventeen different localities -in Europe. They can all, however, be accounted for as -the result of natural movements or pressure of the soil acting -in connection with sharp substances, like fractured -flints, or else as having been made by the teeth of sharks, -whose fossil remains are found in great abundance in the -same formation.</p> - -<p>All the discoveries of flints supposed to show traces of -intentional chipping are pronounced to be unsatisfactory, -with the exception of those found in three localities—Thenay -(near Tours) and Puy-Courny (near Aurillac), in -France, and Otta, in the valley of the Tagus, in Portugal. -As European archæologists at the present time are substantially -in accord with Mortillet in restricting the discussion -to these three places, I will follow their example. But although -Mortillet believes that flints found at all these localities -exhibit marks of intelligent action, he will not admit -that they are the work of man. He attributes them to an -intelligent ancestor of man, whom he calls by the name of -anthropopithecus, or the precursor of man. Of this creature -he distinguishes three different species, named respectively -after the discoverers of the flints in the three localities -just mentioned. The precursor, however, has found up to -this time only a very limited acceptance among men of -science, although a few believe in him on purely theoretical -grounds. The discussion generally turns upon the question -whether these flints were chipped intentionally or are the -result of natural causes; and also upon the determination of -the geological age of the formations in which they are found.</p> - -<div class="fig_center" style="width: 280px;"> -<a id="fig108" name="fig108"></a> -<img src="images/fig_108.png" width="280" height="449" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 108.</span>—Flint flakes collected by Abbé Bourgeois from Miocene strata -at Thenay (after Gaudry). Natural size.</div> -</div> - -<p>I visited Thenay, the most celebrated of these three localities, -in 1877, and had the advantage of studying the question -there under the guidance of the late Abbé Bourgeois, the discoverer -of the flints, and one of the most prominent advocates -of the Tertiary man. This was the year before he died, -and he showed me at the time his complete collection, and -gave me several of the objects he had discovered. Geologists -are agreed in assigning the deposits in which they -occur to the lower Miocene or middle Tertiary period, -which restricts the discussion to the character of the flints -<span class="pagenum"><a name="Page_368" id="Page_368">« 368 »</a></span> -themselves. The accompanying woodcut<a name="FNanchor_157" id="FNanchor_157"></a><a href="#Footnote_157" class="fnanchor">[FA]</a> gives some indication -of their appearance, although it is misleading, because -the long figure resembling a flint knife is intended to represent -a solid nucleus. None of these objects, however, ought -to be called “flints flakes,” as very few, if any, flakes showing -<span class="pagenum"><a name="Page_369" id="Page_369">« 369 »</a></span> -the “bulb of percussion,” always seen upon them, have -been discovered in the Tertiary deposits at Thenay,<a name="FNanchor_158" id="FNanchor_158"></a><a href="#Footnote_158" class="fnanchor">[FB]</a> although -I have found them there myself <i>upon the surface</i>. -The three other figures would be classed by archæologists as -“piercers,” as Bourgeois has himself designated them, and -are also solid objects. Many of the Thenay flints exhibit a -“crackled” appearance, due to the action of heat. On -this account Mortillet maintains that they were splintered -by fire, and not formed by percussion, the usual method by -which flint implements were fabricated in the stone age. -The Thenay objects are all of very small dimensions, and -are so absolutely unlike the large, rudely-chipped axes of -the Chellean type, found in so many different parts of the -world, and generally accepted as the implement used by -Palæolithic man, that the question naturally suggests itself, -What could have been the purpose for which these little -implements were employed? No better answer has been -suggested than the ludicrous one that they were used by the -hairy anthropopithecus to rid himself of the vermin with -which he was infested.</p> - -<div class="footnote"> - -<p><a name="Footnote_157" id="Footnote_157"></a><a href="#FNanchor_157"><span class="label">[FA]</span></a> From Le Conte, <i>op. cit.</i>, p. 608. The figures are copied from -Gaudry, who borrowed them from the article by Bourgeois, <i>Congrès -Internat. de Bruxelles</i>, 1872, p. 89, pl. ii; and from his <i>La Question -de l’Homme Tertiare</i>. Revue des Questions Scientifiques, 1877, p. 15.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_158" id="Footnote_158"></a><a href="#FNanchor_158"><span class="label">[FB]</span></a> Le Préhistorique, p. 91.</p></div> - -<p>But, leaving aside the question of their purpose, let us -consider the evidence presented by the flints themselves. -Do they exhibit the unmistakable traces of intentional chipping -produced by a series of slight blows or thrusts, delivered -in regular succession and in the same direction, with -the result of forming a distinctly marked edge? And does -the appearance of the action of fire upon their surface imply -the intervention of intelligence? To both questions M. -Adrien Arcelin, the well-known geologist of Mâcon, has -given very sufficient replies in the negative. He has discovered -numerous objects of precisely similar appearance in -Eocene deposits in the neighborhood of Mâcon.<a name="FNanchor_159" id="FNanchor_159"></a><a href="#Footnote_159" class="fnanchor">[FC]</a> But, instead -of pushing man back on this account so much further -into the past, he accounts for the marks of chipping to -be seen on many of these objects as the result of the accidental -shocks of one stone against another in the countless -<span class="pagenum"><a name="Page_370" id="Page_370">« 370 »</a></span> -overturnings and movements to which the strata have been -subjected during the long ages of geological time. He gives -photographs of some of these objects, which are to me entirely -convincing, and describes how he has surprised Nature -in the very act of fabricating them in an abandoned quarry -worked in an Eocene deposit. He thinks the “crackled” -surfaces can be readily explained as the result of atmospheric -action, or of hot springs charged with silex. Numerous -examples of similar changes in the surface of flint, that -have been noticed by himself and others in different localities, -are instanced. Even if some have been caused by fire, -this does not necessarily imply the intervention of man to -have produced it. Similar discoveries have also been made -by M. d’Ault de Mesnil, at Thenay, in Eocene deposits,<a name="FNanchor_160" id="FNanchor_160"></a><a href="#Footnote_160" class="fnanchor">[FD]</a> and -by M. Paul Cabanne, in the Gironde.<a name="FNanchor_161" id="FNanchor_161"></a><a href="#Footnote_161" class="fnanchor">[FE]</a> My own opinion, -based upon the experience of many years spent in the study -of flints broken naturally as well as artificially, and upon a -careful examination of Bourgeois’s collections, is that the so-called -Thenay flints are the result of natural causes.</p> - -<div class="footnote"> - -<p><a name="Footnote_159" id="Footnote_159"></a><a href="#FNanchor_159"><span class="label">[FC]</span></a> Matériaux pour l’Histoire Prim, et Nat. de l’Homme, tome xix, -p. 193.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_160" id="Footnote_160"></a><a href="#FNanchor_160"><span class="label">[FD]</span></a> Matériaux, ibid., p. 246.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_161" id="Footnote_161"></a><a href="#FNanchor_161"><span class="label">[FE]</span></a> Id., tome xxii, p. 205.</p></div> - -<p>The second locality where flints alleged to display marks -of human action have been found is the vicinity of Aurillac, -in the Auvergne, especially on the flanks of a hill called -Puy-Courny. They occur in a conglomerate of the upper -Miocene period, and are consequently much later than the -Thenay flints. In this conglomerate, in 1869, M. Tardy discovered -a worked flint flake which has every appearance of -being artificial.<a name="FNanchor_162" id="FNanchor_162"></a><a href="#Footnote_162" class="fnanchor">[FF]</a> Mortillet, however, says that it was found -in the upper surface of the deposit, where there may easily -have been a mingling with the Quaternary formation; and it -certainly resembles worked flakes, which are not uncommon -in the Quaternary. The geological determination of the -find may consequently be regarded as uncertain.</p> - -<div class="footnote"> - -<p><a name="Footnote_162" id="Footnote_162"></a><a href="#FNanchor_162"><span class="label">[FF]</span></a> See Matériaux, tome vi, p. 94. S. Reinach, however, <i>Description -Raison. du Musée de Saint-Germain-en-Laye</i>, i, p. 107, n. 8, -calls it “gravure inexacte.”</p></div> - -<p>The flints discovered at Puy-Courny by M. Barnes are of -small dimensions, and have all been produced by percussion. -Many of them are said to bear some resemblance to pointed -<span class="pagenum"><a name="Page_371" id="Page_371">« 371 »</a></span> -flakes of artificial origin, and one has been figured, probably -selected for its excellence.<a name="FNanchor_163" id="FNanchor_163"></a><a href="#Footnote_163" class="fnanchor">[FG]</a> It is by no means convincing to -me, and I am not at all surprised that so many archæologists -question the artificial character of these objects, which exhibit -a great variety of forms. Upon this point Rames does -not profess to be qualified to pronounce judgment, limiting -himself solely to the geological questions. He argues, however, -that the fact that all the objects supposed to be artificial -are made of the best qualities of flint, of which implements -are ordinarily made, although fragments of inferior -quality are abundant in the same formation, implies the intervention -of man’s judgment in making the selection. But -M. Boule shows that this is merely the result of the erosion -of an ancient river, which operated only upon the upper -beds, in which alone the better qualities of flint are to be -found; and Rames has accepted this explanation.<a name="FNanchor_164" id="FNanchor_164"></a><a href="#Footnote_164" class="fnanchor">[FH]</a> The -flints of Puy-Courny seem to fall within the same category -as those of Thenay. They are the product of denudation, -have travelled long distances, and have been subjected to -the action of powerful agents. These causes are sufficient -to account for the shocks of which they show the traces, and -to explain the production of splinters arising therefrom.</p> - -<div class="footnote"> - -<p><a name="Footnote_163" id="Footnote_163"></a><a href="#FNanchor_163"><span class="label">[FG]</span></a> Matériaux, tome xviii, p. 400.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_164" id="Footnote_164"></a><a href="#FNanchor_164"><span class="label">[FH]</span></a> Revue d’Anthropologie (third series), tome iv, p. 217.</p></div> - -<p>The last locality in which flints claimed to have been -manufactured by the Tertiary man are supposed to have -been discovered is the so-called desert of Otta, in the valley -of the Tagus, not far from Lisbon.</p> - -<p>The formation there is a lacustrine deposit of great -thickness, belonging to the upper Miocene, and abounding -in flint. Here, during the course of twenty years, M. Ribeiro -discovered, but mostly upon the surface, a large number -of flakes of flint and quartzite. After much debate in -regard to them, ninety-five of them were finally sent by -him to Paris, in 1878, and placed in the archæological department -of the great exposition. There they were to be -submitted to the judgment of the assembled prehistoric -archæologists of all nationalities, many of whom, including -the writer, availed themselves of the opportunity of carefully -<span class="pagenum"><a name="Page_372" id="Page_372">« 372 »</a></span> -studying them. The judgment of Mortillet is that twenty-two -specimens exhibited unmistakable traces of intentional -chipping, in which opinion I entirely concur. Only nine, -however, were represented as coming from the Miocene, -some of which showed on their surface an incrustation of -grit, which was claimed as proof of their origin. But the -opinion was freely expressed that, even if they really came -from the Miocene deposits, they might have penetrated into -them from the surface, through cracks, and thus have become -so incrusted. It was accordingly resolved to hold the -next international congress of prehistoric archæologists at -Lisbon, in 1880, mainly for the purpose of settling this question, -if possible, by an investigation conducted upon the spot. -In the course of a visit made at that time to Otta, several -artificial specimens were found on the surface by different -searchers, but Professor Bellucci, of Perugia, was fortunate -enough to discover a flint flake <i>in situ</i>, still so closely imbedded -in the deposit that it required to be detached by a -hammer. There is no question that this object was actually -found in a Miocene deposit, but unfortunately it belongs to -the doubtful category of external flakes, which, although -they exhibit the “bulb of percussion,” have no other sure -indication that they are the work of man.<a name="FNanchor_165" id="FNanchor_165"></a><a href="#Footnote_165" class="fnanchor">[FI]</a> As such bulbs -can be produced by natural causes, some stronger proof than -this of the existence of Tertiary man is demanded.</p> - -<div class="footnote"> - -<p><a name="Footnote_165" id="Footnote_165"></a><a href="#FNanchor_165"><span class="label">[FI]</span></a> It has been figured by Bellucci, <i>Archivio per l’Anthropologia -e la Etnologia di Firenze</i>, tome xi, p. 12, tav. iv, fig. 2. To me it -possesses no value as evidence.</p></div> - -<p>These are all the localities in Europe claimed by Mortillet -to have furnished such evidence, but he thinks a strong confirmation -of it is afforded by certain discoveries made in the -auriferous gravels of California. I will not occupy space -here in repeating arguments I have brought forward elsewhere -to show the utter insufficiency of this evidence to -prove the existence of man on the Pacific coast of our continent -during the Pliocene period,<a name="FNanchor_166" id="FNanchor_166"></a><a href="#Footnote_166" class="fnanchor">[FJ]</a> They may all be summed -up in the words of Le Conte: “The doubts in regard to this -<span class="pagenum"><a name="Page_373" id="Page_373">« 373 »</a></span> -extreme antiquity of man are of three kinds, viz.: 1. Doubts -as to the Pliocene age of the gravels—they may be early -Quaternary. 2. Doubts as to the authenticity of the finds—no -scientist having seen any of them in situ. 3. Doubts as -to the undisturbed conditions of the gravels, for auriferous -gravels are especially liable to disturbance. The character -of the implements said to have been found gives peculiar -emphasis to this last doubt, <i>for they are not Paleolithic</i>, -but Neolithic.”<a name="FNanchor_167" id="FNanchor_167"></a><a href="#Footnote_167" class="fnanchor">[FK]</a> The question has been raised whether this -archæological objection is applicable to the stone mortars, -numerous examples of which have been found in the gravels, -some of them quite recently.<a name="FNanchor_168" id="FNanchor_168"></a><a href="#Footnote_168" class="fnanchor">[FL]</a> If the evidence brought forward -by Professor Whitney and others were limited to -these mortars, it might very well be claimed that they are -neither Palæolithic nor Neolithic; that the smoothness of -their surface is owing to their having been hollowed out of -pebbles that have been polished and worn by natural forces. -But Professor Whitney has cited numberless instances of -“spear-heads,” "arrow-heads," “discoidal stones,” "stone -beads," and “a hatchet” that have been found under precisely -similar conditions as the mortars. So Mr. Becker has -recently produced an affidavit of a certain Mr. Neale that -in a tunnel run into the gravel in 1877 “between two hundred -and three hundred feet beyond the edge of the solid -lava, he saw several spear-heads nearly one foot in length.”<a name="FNanchor_169" id="FNanchor_169"></a><a href="#Footnote_169" class="fnanchor">[FM]</a> -Now it cannot be questioned that such objects as these clearly -belong to the Neolithic period, which does not imply that all -the objects used at that time were polished, but that together -with chipped implements “polished stone implements were -also used.”<a name="FNanchor_170" id="FNanchor_170"></a><a href="#Footnote_170" class="fnanchor">[FN]</a> No archæologist will believe that, while Palæolithic -man has not yet been discovered in the Tertiary -deposits of western Europe, the works of Neolithic man have -<span class="pagenum"><a name="Page_374" id="Page_374">« 374 »</a></span> -been found in similar deposits in western America. Peculiar -difficulties seem to surround the evidence brought forward -in support of such an assumption. We are told by Professor -Whitney that a stone mortar was “found standing upright, -and the pestle was in it, in its proper place, just as it had -been left by the owner.” He fails, however, to explain how -this was brought about in a gravel deposit supposed to have -been laid down by great floods of water. So, when Mr. -Neale swears that he saw fifteen years ago in the same -gravels spear-heads a great deal larger than those known -to archæologists, may we not ask whether reliance can be -placed on the memory of witnesses who testify to impossibilities -to justify conclusions that rest upon such testimony? -I think we shall have to wait for further and better evidence -than this before we are called upon to admit that the -existence of the Tertiary man upon our Pacific coast has been -established.</p> - -<div class="footnote"> - -<p><a name="Footnote_166" id="Footnote_166"></a><a href="#FNanchor_166"><span class="label">[FJ]</span></a> <i>The Prehistoric Archæology of North America</i>, Narrative and -Critical History of America, vol. i, pp. 850-356.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_167" id="Footnote_167"></a><a href="#FNanchor_167"><span class="label">[FK]</span></a> Le Conte, <i>op. cit.</i>, p. 614.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_168" id="Footnote_168"></a><a href="#FNanchor_168"><span class="label">[FL]</span></a> Professor George Frederick Wright, <i>Prehistoric Man on the -Pacific Coast</i>, Atlantic Monthly, April, 1891, p. 512; <i>Table Mountain -Archæology</i>, Nation, May 21, 1891, p. 419.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_169" id="Footnote_169"></a><a href="#FNanchor_169"><span class="label">[FM]</span></a> <i>Antiquities from under Tuolome Table Mountain in California</i>, -Bulletin of the Geological Society of America, vol. ii, p. 192.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_170" id="Footnote_170"></a><a href="#FNanchor_170"><span class="label">[FN]</span></a> Le Conte, <i>op. cit.</i>, p. 607.</p> -</div> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_375" id="Page_375">« 375 »</a></span></p> - - - - -<p class="caption2"><a name="INDEX" id="INDEX">INDEX.</a></p> - - -<p class="p0"> -Aar Glacier <a href="#Page_11">11</a>, <a href="#Page_43">43</a>, <a href="#Page_132">132</a>.<br /> -Abbeville, France, <a href="#Page_251">251</a>, <a href="#Page_263">263</a>.<br /> -Abbott, C. C, cited, <a href="#Page_242">242</a>, <a href="#Page_245">245</a>.<br /> -Adams, Charles Francis, cited, <a href="#Page_297">297</a>.<br /> -Adhémar, cited, <a href="#Page_307">307</a>, <a href="#Page_310">310</a>.<br /> -Africa, ancient glaciers of, <a href="#Page_191">191</a>.<br /> -Agassiz, Louis, cited, <a href="#Page_9">9</a>, <a href="#Page_11">11</a>, <a href="#Page_43">43</a>, <a href="#Page_128">128</a>, <a href="#Page_241">241</a>.<br /> -Ailsa Crag, <a href="#Page_167">167</a>, <a href="#Page_168">168</a>.<br /> -Akron. Ohio, <a href="#Page_220">220</a>, <a href="#Page_221">221</a>.<br /> -Alaska, <a href="#Page_1">1</a>, <a href="#Page_22">22</a>, <a href="#Page_23">23</a> <i>et seq.</i>, <a href="#Page_47">47</a>, <a href="#Page_212">212</a>, <a href="#Page_283">283</a>;<br /> - climate of, <a href="#Page_291">291</a>, <a href="#Page_302">302</a>.<br /> -Aletsch Glacier, <a href="#Page_9">9</a>, <a href="#Page_211">211</a>, <a href="#Page_241">241</a>.<br /> -Alleghany Valley, <a href="#Page_206">206</a>, <a href="#Page_214">214</a>;<br /> - terraces in, <a href="#Page_229">229</a>.<br /> -Alpine glaciers, existing, <a href="#Page_9">9-11</a>, <a href="#Page_43">43</a> <i>et seq.</i>;<br /> - size and number of, <a href="#Page_9">9</a>;<br /> - depth of, <a href="#Page_11">11</a>;<br /> - velocity of, <a href="#Page_43">43</a> <i>et seq.</i>;<br /> - ancient, <a href="#Page_58">58-60</a>, <a href="#Page_131">131-136</a>;<br /> - advance and retreat of, <a href="#Page_116">116</a>.<br /> -Alps, <a href="#Page_1">1</a>, <a href="#Page_9">9-11</a>, <a href="#Page_43">43</a> <i>et seq.</i>, <a href="#Page_58">58</a> <i>et seq.</i>, <a href="#Page_91">91</a>, <a href="#Page_131">131</a> <i>et seq.</i>, <a href="#Page_211">211</a>;<br /> - age of, <a href="#Page_328">328</a>.<br /> -Altaville, Cal, <a href="#Page_296">296</a>.<br /> -Amazon Valley, temperature of, <a href="#Page_316">316</a>.<br /> -Amherst, Ohio, glacial marks near, <a href="#Page_52">52</a>.<br /> -Amiens, France, implements from, <a href="#Page_252">252</a>, <a href="#Page_263">263</a> <i>et seq.</i>;<br /> - terraces at, <a href="#Page_360">360</a>.<br /> -Andes, <a href="#Page_17">17</a>, <a href="#Page_330">330</a>;<br /> - age of, <a href="#Page_328">328</a>.<br /> -Andover, Mass., <a href="#Page_77">77</a> <i>et seq.</i>, <a href="#Page_345">345</a>.<br /> -Andrews, cited, <a href="#Page_345">345</a>, <a href="#Page_347">347</a>, <a href="#Page_354">354</a>, <a href="#Page_356">356</a>.<br /> -Animals, extinct, associated with man in eastern America, <a href="#Page_262">262</a>;<br /> - in France, <a href="#Page_263">263</a>;<br /> - in England, <a href="#Page_264">264</a> <i>et seq.</i>;<br /> - in Wales, <a href="#Page_272">272</a>;<br /> - in Belgium, <a href="#Page_277">277</a> <i>et seq.</i>;<br /> - summary concerning, <a href="#Page_281">281-293</a>.<br /> -Animals, relics of, in loess, <a href="#Page_188">188</a>.<br /> -Antarctic Continent, existing glaciers of, <a href="#Page_1">1</a>, <a href="#Page_18">18</a> <i>et seq.</i><br /> -Arcy, Belgium, grotto at, <a href="#Page_279">279</a>.<br /> -Arenig Mawr, Wales, <a href="#Page_150">150</a>, <a href="#Page_151">151</a>, <a href="#Page_172">172</a>.<br /> -Argillite implement, face and side view of, <a href="#Page_247">247</a>, <a href="#Page_259">259</a>.<br /> -Arnhem, Holland, moraine at, <a href="#Page_181">181</a>.<br /> -Asia, existing glaciers in, <a href="#Page_14">14</a> <i>et seq.</i>;<br /> - ancient glaciers of, <a href="#Page_190">190</a>.<br /> -Assiniboine River, <a href="#Page_228">228</a>.<br /> -Astronomical theories of the Glacial period, <a href="#Page_303">303</a> <i>et seq.</i><br /> -Atlantic Ocean, <a href="#Page_314">314</a>.<br /> -Aurillac, supposed flint-chips near, <a href="#Page_367">367</a>, <a href="#Page_370">370</a>.<br /> -Australia, ancient glaciers of, <a href="#Page_126">126</a>, <a href="#Page_192">192</a>.<br /> -Austria, existing glaciers of, <a href="#Page_9">9</a>.<br /> -Auvergne, <a href="#Page_136">136</a>.<br /> -<br /> -Babbitt, Miss F. E., cited, <a href="#Page_253">253</a>, <a href="#Page_254">254</a>, <a href="#Page_255">255</a>.<br /> -Bakewell on age of Niagara gorge, <a href="#Page_337">337</a>.<br /> -Baldwin, C. C, <a href="#Page_251">251</a>.<br /> -Baldwin, P., <a href="#Page_25">25</a>.<br /> -Ball, cited, <a href="#Page_310">310</a>, <a href="#Page_317">317</a>.<br /> -Baltic Sea, <a href="#Page_129">129</a>.<br /> -Barnsley, England, <a href="#Page_155">155</a>.<br /> -Bates, cited, <a href="#Page_204">204</a>.<br /> -Bear, <a href="#Page_270">270</a>, <a href="#Page_287">287</a>, <a href="#Page_290">290</a>.<br /> -Bear, grizzly, <a href="#Page_270">270</a>, <a href="#Page_288">288</a>.<br /> -Beaver, <a href="#Page_289">289</a>.<br /> -Beaver Creek, Pa., <a href="#Page_205">205</a>, <a href="#Page_230">230</a>, <a href="#Page_232">232</a>.<br /> -Becker, cited, <a href="#Page_296">296</a>, <a href="#Page_300">300</a>, <a href="#Page_349">349</a>.<br /> -Bedford, England, <a href="#Page_265">265</a>.<br /> -Beech Flats, Ohio, terrace at, <a href="#Page_217">217</a>.<br /> -Belgium, human relics in glacial terraces in, <a href="#Page_264">264</a>;<br /> - caverns of, <a href="#Page_274">274</a>.<br /> -Bell, cited, <a href="#Page_109">109</a>, <a href="#Page_117">117</a>;<br /> - on unity of the Glacial period, <a href="#Page_110">110</a>.<br /> -Bellevue, Pa., glacial terrace on the Ohio at, <a href="#Page_217">217</a>.<br /> -Bellucci, cited, <a href="#Page_372">372</a>.<br /> -Ben Nevis, <a href="#Page_240">240</a>.<br /> -Bernese Oberland, <a href="#Page_9">9</a>, <a href="#Page_59">59</a>, <a href="#Page_131">131</a>, <a href="#Page_132">132</a>.<br /> -Big Stone Lake, <a href="#Page_208">208</a>, <a href="#Page_226">226</a>.<br /> -Birmingham. England, <a href="#Page_150">150</a>.<br /> -Bishop, cited, <a href="#Page_306">306</a>.<br /> -Bison, <a href="#Page_262">262</a>, <a href="#Page_270">270</a>, <a href="#Page_271">271</a>, <a href="#Page_278">278</a>, <a href="#Page_289">289</a>.<br /> -Black Forest, the, <a href="#Page_136">136</a>. -<span class="pagenum"><a name="Page_376" id="Page_376">« 376 »</a></span><br /> -Black River, Ohio, <a href="#Page_343">343</a>.<br /> -Black Sea, <a href="#Page_238">238</a>.<br /> -Blanc, Mont, <a href="#Page_1">1</a>, <a href="#Page_9">9-11</a>, <a href="#Page_132">132</a>, <a href="#Page_211">211</a>.<br /> -Blandford, cited, <a href="#Page_312">312</a>.<br /> -Boone County, Ky., glacial deposits in, <a href="#Page_212">212</a>.<br /> -Boston, scratched stone from till of, <a href="#Page_54">54</a>;<br /> - drumlins in the vicinity of, <a href="#Page_75">75</a>.<br /> -Boston Society of Natural History, <a href="#Page_296">296</a>.<br /> -Boulder-clay. (<a href="#Till">See Till.</a>)<br /> -Boulders, disintegrated, <a href="#Page_57">57</a>, <a href="#Page_71">71</a>.<br /> -Boulders, distribution of, in New-England, <a href="#Page_57">57</a>, <a href="#Page_60">60</a>, <a href="#Page_61">61</a>, <a href="#Page_69">69</a> <i>et seq.</i>;<br /> - in Switzerland, <a href="#Page_58">58</a> <i>et seq.</i>, <a href="#Page_133">133</a>.<br /> -Boulders, transportation of, in Pennsylvania, <a href="#Page_57">57</a>, <a href="#Page_61">61</a>, <a href="#Page_85">85</a>;<br /> - in New Hampshire, <a href="#Page_60">60</a>, <a href="#Page_71">71</a>;<br /> - in Kentucky, <a href="#Page_63">63</a>, <a href="#Page_97">97</a>;<br /> - in Ohio, <a href="#Page_64">64</a>, <a href="#Page_72">72</a>;<br /> - in Rhode Island, <a href="#Page_67">67</a>;<br /> - in Massachusetts, <a href="#Page_69">69</a> <i>et seq.</i>;<br /> - in Connecticut, <a href="#Page_71">71</a>, <a href="#Page_72">72</a>;<br /> - in New Jersey, <a href="#Page_83">83</a>;<br /> - in Illinois, <a href="#Page_97">97</a>.<br /> -Bourgeois, Abbé, cited, <a href="#Page_367">367</a>.<br /> -Bridgenorth, England, <a href="#Page_150">150</a>.<br /> -Bridlington, England, <a href="#Page_156">156</a>, <a href="#Page_158">158</a>.<br /> -Bristol Channel, <a href="#Page_138">138</a>, <a href="#Page_178">178</a>.<br /> -British Columbia, <a href="#Page_1">1</a>, <a href="#Page_23">23</a>, <a href="#Page_121">121</a> <i>et seq.</i>, <a href="#Page_194">194</a>, <a href="#Page_198">198</a>.<br /> -<a id="British_Isles" name="British_Isles"></a>British Isles, ancient glaciers of, <a href="#Page_136">136-181</a>;<br /> - preglacial level of land in, <a href="#Page_139">139-141</a>;<br /> - preglacial climate in 141, <a href="#Page_142">142</a>;<br /> - great glacial centres—<br /> - Wales, <a href="#Page_143">143</a>;<br /> - Ireland, <a href="#Page_143">143</a>;<br /> - Galloway, <a href="#Page_144">144</a>;<br /> - Lake District, <a href="#Page_144">144</a>;<br /> - Pennine Chain, <a href="#Page_144">144</a>;<br /> - confluent glaciers—<br /> - Irish Sea Glacier, <a href="#Page_145">145-153</a>;<br /> - Solway Glacier, <a href="#Page_153">153-158</a>;<br /> - East Anglian Glacier, <a href="#Page_158">158</a>;<br /> - Isle of Man, <a href="#Page_164">164-167</a>;<br /> - the so-called Great Submergence, <a href="#Page_167">167-180</a>;<br /> - dispersion of erratics of Shap granite, <a href="#Page_180">180</a>, <a href="#Page_181">181</a>;<br /> - drainage of, <a href="#Page_238">238</a>;<br /> - caverns of, <a href="#Page_267">267</a>;<br /> - climate of, <a href="#Page_314">314</a>.<br /> -Brixham Cave, <a href="#Page_267">267</a> <i>et seq.</i><br /> -Bromsgrove, England, <a href="#Page_150">150</a>.<br /> -Brooklyn, N. Y., <a href="#Page_66">66</a>, <a href="#Page_67">67</a>.<br /> -Brown, on glaciers of Greenland, <a href="#Page_40">40</a>, <a href="#Page_41">41</a>.<br /> -Brown’s Valley, <a href="#Page_226">226</a>.<br /> -Bruce, skull of, <a href="#Page_276">276</a>.<br /> -Buried forests in America, <a href="#Page_107">107</a> <i>et seq.</i><br /> -Buried outlets and channels, <a href="#Page_199">199-210</a>;<br /> - of Lake Erie, <a href="#Page_201">201</a>, <a href="#Page_333">333</a>;<br /> - of Lake Huron, <a href="#Page_202">202</a>;<br /> - of Lake Ontario, <a href="#Page_202">202</a>;<br /> - of Lake Superior, <a href="#Page_203">203</a>;<br /> - of Lake Michigan, <a href="#Page_203">203</a>;<br /> - in southwestern Ohio, <a href="#Page_203">203</a>;<br /> - near Cincinnati, <a href="#Page_203">203</a>;<br /> - near Louisville, Ky., <a href="#Page_205">205</a>;<br /> - in the Tuscarawas Valley, <a href="#Page_205">205</a>;<br /> - in the valley of the Beaver, <a href="#Page_205">205</a>;<br /> - of oil Creek, <a href="#Page_205">205</a>;<br /> - in the valley of the Alleghany, <a href="#Page_206">206</a>;<br /> - of Chautauqua Lake, <a href="#Page_207">207</a>;<br /> - near Minneapolis, <a href="#Page_208">208</a>.<br /> -Burton, England, <a href="#Page_164">164</a>.<br /> -Busk, cited, <a href="#Page_267">267</a>.<br /> -Buttermere, England, <a href="#Page_153">153</a>, <a href="#Page_168">168</a>.<br /> -<br /> -Cache Valley, Utah, <a href="#Page_233">233</a>.<br /> -Cae Gwyn Cave, <a href="#Page_148">148</a>, <a href="#Page_271">271</a> <i>et seq.</i>, <a href="#Page_280">280</a>.<br /> -Caithness, Scotland, <a href="#Page_180">180</a>.<br /> -Calaveras skull, <a href="#Page_295">295</a>, <a href="#Page_300">300</a>.<br /> -California, <a href="#Page_21">21</a>, <a href="#Page_124">124</a>, <a href="#Page_281">281</a>, <a href="#Page_287">287</a>, <a href="#Page_294">294</a>, <a href="#Page_358">358</a>, <a href="#Page_372">372</a>.<br /> -Cambridgeshire, England, <a href="#Page_158">158</a>.<br /> -Canada, <a href="#Page_94">94</a>, <a href="#Page_95">95</a>.<br /> -Canstadt, man of, <a href="#Page_279">279</a>.<br /> -Canton, Ohio, <a href="#Page_232">232</a>.<br /> -Cape St. Roque, <a href="#Page_31">31</a> 3.<br /> -Caribbean Sea, <a href="#Page_318">318</a>.<br /> -Caribou, <a href="#Page_262">262</a>.<br /> -Carll, cited, <a href="#Page_205">205</a>, <a href="#Page_207">207</a>.<br /> -Carpathian Mountains, <a href="#Page_136">136</a>, <a href="#Page_328">328</a>.<br /> -Carpenter, F. R., cited, <a href="#Page_321">321</a>, <a href="#Page_322">322</a>.<br /> -Cascade Range, <a href="#Page_21">21</a>.<br /> -Caspian Sea, <a href="#Page_238">238</a>.<br /> -Cattaraugus Creek, N. Y., <a href="#Page_220">220</a>.<br /> -Caucasus Mountains, <a href="#Page_15">15</a>;<br /> - age of, <a href="#Page_328">328</a>.<br /> -Cave-bear, <a href="#Page_269">269-271</a>, <a href="#Page_278">278</a>, <a href="#Page_280">280</a>;<br /> - hyena, <a href="#Page_269">269</a>, <a href="#Page_270">270</a>, <a href="#Page_278">278</a>;<br /> - lion, <a href="#Page_269">269-271</a>, <a href="#Page_278">278</a>.<br /> -Caverns, British, <a href="#Page_267">267-274</a>;<br /> - on the Continent, <a href="#Page_274">274-281</a>.<br /> -Cefn Cave, <a href="#Page_148">148</a>, <a href="#Page_271">271</a>.<br /> -Cenis, Mont, <a href="#Page_135">135</a>.<br /> -<a id="Centres" name="Centres"></a>Centres of glacial dispersion, <a href="#Page_304">304</a> <i>et seq.</i>, <a href="#Page_323">323</a> <i>et seq.</i>, <a href="#Page_328">328</a>;<br /> - in America, <a href="#Page_113">113</a>, <a href="#Page_121">121</a>;<br /> - in Europe, <a href="#Page_129">129</a> <i>et seq.</i>;<br /> - in the British Isles, <a href="#Page_142">142</a> <i>et seq.</i><br /> -Cevennes, <a href="#Page_136">136</a>.<br /> -Chamberlin, T. C, terminal moraine of second Glacial epoch, <a href="#Page_93">93</a>,<br /> -<span style="margin-left: 3em;">98 <i>et seq.</i>;<br /> - on driftless area, <a href="#Page_102">102</a>, <a href="#Page_103">103</a>;<br /> - cited, <a href="#Page_110">110</a>, <a href="#Page_218">218</a>, <a href="#Page_229">229</a>, <a href="#Page_307">307</a>;<br /> - on Cincinnati ice-dam, <a href="#Page_218">218</a>.<br /> -Chamois, <a href="#Page_289">289</a>, <a href="#Page_290">290</a>.<br /> -Chamouni, <a href="#Page_132">132</a>.<br /> -Charpentier, <a href="#Page_9">9</a>, <a href="#Page_59">59</a>.<br /> -Chasseron, <a href="#Page_58">58</a>, <a href="#Page_132">132</a>.<br /> -Chautauqua Lake, buried outlet of, <a href="#Page_207">207</a>.<br /> -Chenango River, <a href="#Page_220">220</a>.<br /> -Cheshire, England, <a href="#Page_149">149</a>,153,178,180.</span><br /> -Cheyenne River, <a href="#Page_228">228</a>.<br /> -Chicago, Ill., <a href="#Page_346">346</a>.<br /> -Chimpanzee, skull of, <a href="#Page_276">276</a>.<br /> -Chur, <a href="#Page_133">133</a>.<br /> -Cincinnati, buried channels near, <a href="#Page_203">203</a> <i>et seq.</i>;<br /> - glacial dam at, <a href="#Page_212">212</a> <i>et seq.</i>;<br /> - terraces at, <a href="#Page_231">231</a>.<br /> -Clarksburg, W. Va., <a href="#Page_216">216</a>.<br /> -Claymont, Del., <a href="#Page_258">258</a> <i>et seq.</i>;<br /> - view of implement found near, <a href="#Page_259">259</a>. -<span class="pagenum"><a name="Page_377" id="Page_377">« 377 »</a></span><br /> -Claypole, cited, <a href="#Page_200">200</a>, <a href="#Page_219">219</a>, <a href="#Page_221">221</a>.<br /> -Climate of Glacial period, <a href="#Page_291">291</a>.<br /> -Clwyd, vale of, <a href="#Page_147">147</a> <i>et seq.</i>. 271 <i>et seq.</i><br /> -Clyde, the, <a href="#Page_144">144</a>.<br /> -Collett, cited, <a href="#Page_107">107</a>.<br /> -Colorado, <a href="#Page_123">123</a>, <a href="#Page_124">124</a>.<br /> -Columbia deposit, <a href="#Page_245">245</a>, <a href="#Page_254">254</a> <i>et seq.</i><br /> -Columbiana County, Ohio, <a href="#Page_232">232</a>.<br /> -Comstock, cited, <a href="#Page_307">307</a>.<br /> -Conewango Creek, <a href="#Page_232">232</a>;<br /> - ancient depth of, <a href="#Page_206">206</a>.<br /> -Connecticut, <a href="#Page_71">71</a>, <a href="#Page_72">72</a>, <a href="#Page_74">74</a>, <a href="#Page_91">91</a>.<br /> -Conyers, cited, <a href="#Page_265">265</a>.<br /> -Cook on subsidence in New Jersey, <a href="#Page_196">196</a>.<br /> -Cope, cited, <a href="#Page_288">288</a>.<br /> -Cordilleran Glacier, <a href="#Page_121">121</a> <i>et seq.</i><br /> -Corswall, England, <a href="#Page_312">312</a>.<br /> -Cows, <a href="#Page_268">268</a>.<br /> -Cresson, cited, <a href="#Page_251">251</a>, <a href="#Page_258">258</a> <i>et seq.</i><br /> -Crevasses. (<a href="#Fissures">See Fissures.</a>)<br /> -Croll, cited, <a href="#Page_304">304</a>, <a href="#Page_307">307</a> <i>et seq.</i>, <a href="#Page_332">332</a>, <a href="#Page_362">362</a>.<br /> -Cro-Magnon, rock shelter of, <a href="#Page_281">281</a>.<br /> -Cromer, England, <a href="#Page_160">160</a>.<br /> -Crosby, on composition of till, <a href="#Page_81">81</a> <i>et seq.</i><br /> -Cross Fell escarpment, <a href="#Page_153">153</a>, <a href="#Page_180">180</a>.<br /> -Culoz, <a href="#Page_132">132</a>.<br /> -Cumberland, England, <a href="#Page_146">146</a>, <a href="#Page_153">153</a>, <a href="#Page_168">168</a>, <a href="#Page_173">173</a>.<br /> -Gumming, quoted, <a href="#Page_166">166</a>.<br /> -Gushing, H., <a href="#Page_26">26</a><br /> -Cuyahoga River, <a href="#Page_220">220</a>, <a href="#Page_221">221</a>;<br /> - buried channel of, <a href="#Page_200">200</a>.<br /> -<br /> -Dana, Professor J. D., on depth of ice, <a href="#Page_91">91</a>;<br /> - on driftless area, <a href="#Page_102">102</a>;<br /> - cited, <a href="#Page_320">320</a>, <a href="#Page_363">363</a>.<br /> -Danube, ancient glaciers of the, <a href="#Page_129">129</a>, <a href="#Page_134">134</a>, <a href="#Page_188">188</a>.<br /> -Darent, valley of, <a href="#Page_265">265</a>.<br /> -Darrtown, Ohio, <a href="#Page_107">107</a>.<br /> -Darwin, Charles, cited, <a href="#Page_17">17</a>, <a href="#Page_126">126</a>, <a href="#Page_170">170</a>, <a href="#Page_241">241</a>, <a href="#Page_361">361</a>.<br /> -Darwin, George G., cited, <a href="#Page_361">361</a>.<br /> -Darwin, Mrs. M. J., mortar owned by, <a href="#Page_297">297</a>.<br /> -Date of Glacial period, chapter on, <a href="#Page_332">332-364</a>.<br /> -Davidson Glacier, <a href="#Page_23">23</a>.<br /> -Davis on drumlins, <a href="#Page_75">75</a>.<br /> -Dawkins, cited, <a href="#Page_238">238</a>, <a href="#Page_267">267</a>, <a href="#Page_269">269</a>, <a href="#Page_291">291</a>.<br /> -Dawson, G. M., cited, <a href="#Page_121">121</a>;<br /> - on ice-movements, <a href="#Page_97">97</a>;<br /> - on oscillation of land-level, <a href="#Page_125">125</a>, <a href="#Page_126">126</a>.<br /> -Dawson, Sir William, on the fiord of the Saguenay, <a href="#Page_197">197</a>;<br /> - cited, <a href="#Page_285">285</a>.<br /> -Dee, the river, <a href="#Page_149">149</a>.<br /> -Deeley, quoted, <a href="#Page_164">164</a>.<br /> -Delaware River, <a href="#Page_232">232</a>, <a href="#Page_242">242</a> <i>et seq.</i>, <a href="#Page_254">254</a>, <a href="#Page_258">258</a>;<br /> - section across the, <a href="#Page_245">245</a>.<br /> -Delta terrace at Trenton, N. J., <a href="#Page_242">242</a> <i>et seq.</i>;<br /> - at Beaver, Pa., <a href="#Page_230">230</a>.<br /> -De Ranee, cited, <a href="#Page_272">272</a>.<br /> -Derbyshire, England, <a href="#Page_270">270</a>.<br /> -Desor on age of Niagara gorge, <a href="#Page_337">337</a>.<br /> -Diore, glaciers of the, <a href="#Page_135">135</a>.<br /> -Disintegration, amount of, near glacial margin, <a href="#Page_117">117</a>, <a href="#Page_118">118</a>.<br /> -Diss, England, <a href="#Page_266">266</a>.<br /> -Dnieper, the, <a href="#Page_185">185</a>, <a href="#Page_188">188</a>.<br /> -Don, the, <a href="#Page_185">185</a>, <a href="#Page_188">188</a>.<br /> -Dora Baltea, <a href="#Page_134">134</a>.<br /> -Dover, N. H., section of kame near, <a href="#Page_77">77</a>.<br /> -Dover, Straits of, <a href="#Page_238">238</a>.<br /> -Drave, glaciers in the, <a href="#Page_134">134</a>.<br /> -Drainage systems in the Glacial period, <a href="#Page_335">335</a>, <a href="#Page_339">339</a>, <a href="#Page_340">340</a>, <a href="#Page_343">343</a>, <a href="#Page_344">344</a>;<br /> - chapter on, <a href="#Page_193">193-241</a>.<br /> -Drayson, cited, <a href="#Page_317">317</a>.<br /> -Driftless area in the Mississippi Valley, <a href="#Page_101">101</a>, <a href="#Page_102">102</a>.<br /> -Drumlins, description of, <a href="#Page_73">73</a> <i>et seq.</i>;<br /> - view of, <a href="#Page_73">73</a>;<br /> - occurrence of, in Massachusetts, <a href="#Page_73">73</a>;<br /> - in New Hampshire, <a href="#Page_74">74</a>;<br /> - in Connecticut, <a href="#Page_74">74</a>;<br /> - in New York, <a href="#Page_74">74</a>, <a href="#Page_94">94</a>;<br /> - in the British Isles, <a href="#Page_74">74</a>, <a href="#Page_137">137</a>, <a href="#Page_167">167</a>.<br /> -Dunbar, Scotland, <a href="#Page_312">312</a>.<br /> -Dupont, cited, <a href="#Page_279">279</a>.<br /> -Du Quoin, Ill., <a href="#Page_98">98</a>, <a href="#Page_119">119</a>.<br /> -D’Urville, <a href="#Page_20">20</a>.<br /> -Düsseldorf, <a href="#Page_275">275</a>.<br /> -<br /> -Eagle, Wis., view of kettle-moraine near, <a href="#Page_99">99</a>.<br /> -East Anglian Glacier, <a href="#Page_158">158-164</a>.<br /> -Eccentricity of the earth’s orbit, <a href="#Page_308">308</a>.<br /> -Eden Valley, <a href="#Page_180">180</a>.<br /> -Eggischorn, <a href="#Page_211">211</a>, <a href="#Page_241">241</a>.<br /> -Eguisheim, skull found at, <a href="#Page_279">279</a>.<br /> -Elephant, <a href="#Page_265">265</a>, <a href="#Page_280">280</a>, <a href="#Page_282">282</a>, <a href="#Page_283">283</a>, <a href="#Page_292">292</a>.<br /> -Elevation, preglacial, <a href="#Page_112">112</a>, <a href="#Page_194">194</a>, <a href="#Page_198">198</a>;<br /> - the cause of the Glacial period, <a href="#Page_113">113</a>, <a href="#Page_320">320-331</a>;<br /> - about the Great Lakes, <a href="#Page_224">224</a>;<br /> - in the latitude of New York, <a href="#Page_261">261</a>.<br /> -Elyria, Ohio, <a href="#Page_342">342</a>.<br /> -Engis skull, view of, <a href="#Page_274">274</a>.<br /> -England. (<a href="#British_Isles">See British Isles.</a>)<br /> -Enville, England, <a href="#Page_150">150</a>.<br /> -Erosion, preglacial, <a href="#Page_193">193</a> <i>et seq.</i><br /> -Erosion in river valleys, <a href="#Page_198">198</a>, <a href="#Page_329">329</a>, <a href="#Page_332">332</a>.<br /> -Erzgebirge, <a href="#Page_136">136</a>, <a href="#Page_181">181</a>.<br /> -Europe, existing glaciers in, <a href="#Page_9">9</a>, <i>et seq.</i>, 43 <i>et seq.</i>;<br /> - ancient glaciers of, <a href="#Page_129">129-190</a>;<br /> - former elevation of, <a href="#Page_238">238</a>;<br /> - ice-dams in, <a href="#Page_360">360</a>.<br /> -Evans, cited, <a href="#Page_263">263</a>, <a href="#Page_267">267</a>, <a href="#Page_354">354</a>, <a href="#Page_365">365</a>. -<span class="pagenum"><a name="Page_378" id="Page_378">« 378 »</a></span><br /> -<br /> -Falconer, cited, <a href="#Page_263">263</a>.<br /> -Falls of St Anthony, <a href="#Page_200">200</a>.<br /> -Faudel, cited, <a href="#Page_279">279</a>.<br /> -Fiesch, Switzerland, <a href="#Page_131">131</a>, <a href="#Page_211">211</a>.<br /> -Filey Brigs;, Eng., <a href="#Page_155">155</a>.<br /> -Finchley, Eng., <a href="#Page_158">158</a>, <a href="#Page_159">159</a>.<br /> -Finger Lakes, <a href="#Page_94">94</a>.<br /> -Finsteraarhorn, <a href="#Page_9">9</a>.<br /> -Fiords, <a href="#Page_194">194</a> <i>et seq.</i>;<br /> - of Greenland, <a href="#Page_212">212</a>.<br /> -<a id="Fissures" name="Fissures"></a>Fissures in glacial ice, <a href="#Page_3">3</a>, <a href="#Page_48">48</a>, <a href="#Page_49">49</a>.<br /> -Flamborough, <a href="#Page_140">140</a>, <a href="#Page_156">156</a>, <a href="#Page_157">157</a>, <a href="#Page_176">176</a>.<br /> -Florida, <a href="#Page_314">314</a>.<br /> -Flower, cited, <a href="#Page_263">263</a>.<br /> -Forbes, <a href="#Page_9">9</a>, <a href="#Page_38">38</a>, <a href="#Page_43">43</a>, <a href="#Page_44">44</a>, <a href="#Page_48">48</a>.<br /> -Forel, M., cited, <a href="#Page_116">116</a>.<br /> -Fort Snelling, Mississippi gorge at, <a href="#Page_208">208</a>, <a href="#Page_340">340</a> <i>et seq.</i><br /> -Fort Wayne, Incl., <a href="#Page_220">220</a>, <a href="#Page_224">224</a>.<br /> -Foshay, cited, <a href="#Page_119">119</a>.<br /> -Fox, <a href="#Page_270">270</a>, <a href="#Page_289">289</a>, <a href="#Page_290">290</a>.<br /> -Fraipont, cited, <a href="#Page_275">275</a> <i>et seq.</i><br /> -France, existing glaciers of, <a href="#Page_19">19</a>;<br /> - ancient glaciers of, <a href="#Page_136">136</a>;<br /> - glacial gravels of, <a href="#Page_262">262</a> <i>et seq.</i><br /> -Frankley Hill, England, <a href="#Page_150">150</a>.<br /> -Franklin, Pa., <a href="#Page_230">230</a>, <a href="#Page_232">232</a>.<br /> -Franz-Josef Land, <a href="#Page_14">14</a>.<br /> -Frederickshaab Glacier, <a href="#Page_91">91</a>, <a href="#Page_212">212</a>.<br /> -Frere, cited, <a href="#Page_266">266</a>.<br /> -Frickthal, <a href="#Page_133">133</a>.<br /> -Frondeg, Wales, <a href="#Page_149">149</a>, <a href="#Page_178">178</a>.<br /> -<br /> -Gabb, cited, <a href="#Page_318">318</a>.<br /> -Galloway, ancient glaciers of, <a href="#Page_144">144</a>, <a href="#Page_145">145</a>, <a href="#Page_154">154</a>, <a href="#Page_157">157</a>, <a href="#Page_167">167</a>, <a href="#Page_168">168</a>, <a href="#Page_173">173</a>.<br /> -Garda, Lake, moraine in front of, <a href="#Page_135">135</a>.<br /> -Garonne, the, <a href="#Page_136">136</a>, <a href="#Page_188">188</a>.<br /> -Gaudry, cited, <a href="#Page_263">263</a>.<br /> -Geikie, Archibald, cited, <a href="#Page_272">272</a>, <a href="#Page_312">312</a>.<br /> -Geikie, James, on kames, <a href="#Page_76">76</a>;<br /> - on loess, <a href="#Page_187">187</a>, <a href="#Page_188">188</a>;<br /> - cited, <a href="#Page_291">291</a> <i>et seq.</i>, <a href="#Page_307">307</a>, <a href="#Page_353">353</a>.<br /> -Genesee River, <a href="#Page_220">220</a>.<br /> -Geological time, <a href="#Page_361">361</a> <i>et seq.</i><br /> -Georgian Bay, <a href="#Page_339">339</a>.<br /> -German Ocean, <a href="#Page_129">129</a>.<br /> -Germantown, Ohio, <a href="#Page_107">107</a>, <a href="#Page_108">108</a>.<br /> -Germany, North, moraine in, <a href="#Page_181">181</a>, <a href="#Page_183">183</a>;<br /> - glacial lakes in, <a href="#Page_238">238</a>;<br /> - Quaternary animals in, <a href="#Page_279">279</a>.<br /> -Gietroz Glacier, <a href="#Page_211">211</a>.<br /> -Gilbert, cited, <a href="#Page_233">233</a> <i>et seq.</i>, <a href="#Page_350">350</a> <i>et seq.</i>;<br /> - on age of Niagara gorge, <a href="#Page_339">339</a>.<br /> -Glacial dispersion. (<a href="#Centres">See Centres of Glacial Dispersion.</a>)<br /> -Glacial boundary in New England, <a href="#Page_67">67</a>;<br /> - in New Jersey, <a href="#Page_83">83</a>;<br /> - in Pennsylvania, <a href="#Page_84">84</a> <i>et seq.</i>;<br /> - in New York, <a href="#Page_84">84</a>;<br /> - in Ohio, <a href="#Page_95">95</a>, <a href="#Page_100">100</a>, <a href="#Page_106">106</a>;<br /> - in Kentucky, <a href="#Page_96">96</a>;<br /> - in Indiana, <a href="#Page_96">96</a>;<br /> - in Illinois, <a href="#Page_96">96</a>, <a href="#Page_100">100</a>;<br /> - in Kansas, Nebraska, Missouri, Montana, South Dakota, <a href="#Page_96">96</a>;<br /> - in Minnesota, <a href="#Page_101">101</a>;<br /> - in British Isles, <a href="#Page_137">137</a>, <a href="#Page_148">148</a>, <a href="#Page_150">150</a>, <a href="#Page_151">151</a>, <a href="#Page_155">155</a>, <a href="#Page_167">167</a>;<br /> - in Holland, <a href="#Page_181">181</a>; in Germany, <a href="#Page_181">181</a>, <a href="#Page_183">183</a>;<br /> - in Russia, <a href="#Page_181">181</a>, <a href="#Page_189">189</a>.<br /> -Glacial erosion, <a href="#Page_118">118</a>, <a href="#Page_119">119</a>, <a href="#Page_182">182</a>.<br /> -Glacial ice, depth of, in Pennsylvania, <a href="#Page_90">90</a> <i>et seq.</i>;<br /> - in Connecticut, <a href="#Page_91">91</a>;<br /> - in New York, <a href="#Page_91">91</a>;<br /> - in Greenland, <a href="#Page_91">91</a>;<br /> - in the Alps, <a href="#Page_91">91</a>, <a href="#Page_131">131</a>, <a href="#Page_133">133</a>, <a href="#Page_182">182</a>;<br /> - in Germany, <a href="#Page_182">182</a>;<br /> - in Norway, <a href="#Page_182">182</a>;<br /> - amount of, <a href="#Page_330">330</a>.<br /> -Glacial lakes in Germany, <a href="#Page_283">283</a>.<br /> -Glacial motion, limit of, <a href="#Page_2">2</a>;<br /> - chapter on, <a href="#Page_43">43-50</a>;<br /> - plastic theory of, <a href="#Page_48">48</a>.<br /> -Glacial outlets of the Great Lakes, <a href="#Page_220">220-222</a>.<br /> -Glacial periods, cause of, <a href="#Page_113">113</a>;<br /> - chapter on, <a href="#Page_302">302-331</a>;<br /> - date of, chapter on, <a href="#Page_332">332-364</a>.<br /> -Glacial periods, supposed succession of, <a href="#Page_106">106</a> <i>et seq.</i>, <a href="#Page_311">311</a>, <a href="#Page_324">324-326</a>, <a href="#Page_332">332</a>;<br /> - criticisms of the theory, <a href="#Page_116">116</a> <i>et seq.</i><br /> -Glacial striæ. (<a href="#Rock-Scoring">See Rock-Scoring.</a>)<br /> -<a id="Glacial_Terraces" name="Glacial_Terraces"></a>Glacial terraces, <a href="#Page_229">229-238</a>;<br /> - in Pennsylvania, <a href="#Page_87">87</a> <i>et seq.</i>, <a href="#Page_215">215</a>, <a href="#Page_217">217</a>, <a href="#Page_229">229</a>, <a href="#Page_230">230</a>;<br /> - in New York, <a href="#Page_88">88</a>; at Beech Flats, Ohio, <a href="#Page_217">217</a>;<br /> - at Granville, Ohio, <a href="#Page_227">227</a>;<br /> - on the Minnesota River, <a href="#Page_228">228</a>;<br /> - around Great Salt Lake, <a href="#Page_233">233</a> <i>et seq.</i>;<br /> - on Delaware River, <a href="#Page_243">243</a> <i>et seq.</i>;<br /> - in Europe, <a href="#Page_238">238-241</a>;<br /> - in Ohio, <a href="#Page_249">249</a> <i>et seq.</i>;<br /> - human relics in, <a href="#Page_241">241-267</a>;<br /> - on Delaware River, <a href="#Page_245">245</a>;<br /> - of the Mississippi River, <a href="#Page_254">254</a>;<br /> - in France, <a href="#Page_263">263</a> <i>et seq.</i>, <a href="#Page_360">360</a>;<br /> - in England, <a href="#Page_264">264</a> <i>et seq.</i>;<br /> - in Belgium, <a href="#Page_264">264</a>;<br /> - in Spain, <a href="#Page_264">264</a>;<br /> - in Portugal, <a href="#Page_264">264</a>;<br /> - in Italy, <a href="#Page_264">264</a>;<br /> - in Greece, <a href="#Page_264">264</a>.<br /> -Glacial theory, crucial tests of, <a href="#Page_62">62</a>, <a href="#Page_65">65</a>, <a href="#Page_257">257</a>, <a href="#Page_302">302</a> <i>et seq.</i><br /> -Glaciation, signs of past, chapter on, <a href="#Page_51">51</a> <i>et seq.</i><br /> -Glacier Bay, <a href="#Page_24">24</a>;<br /> - map of, <a href="#Page_25">25</a>.<br /> -Glacier, denned, <a href="#Page_2">2</a>;<br /> - formation of, <a href="#Page_3">3</a>;<br /> - characterised by veins and fissures, <a href="#Page_3">3</a>;<br /> - advance and retreat of, <a href="#Page_116">116</a>;<br /> - velocity of, in the Alps, <a href="#Page_43">43</a> <i>et seq.</i>;<br /> - in Greenland, <a href="#Page_36">36</a>, <a href="#Page_46">46-48</a>;<br /> - in Alaska, <a href="#Page_47">47</a>.<br /> -Glaciers, ancient, in North America, <a href="#Page_66">66-128</a>;<br /> - in Central and Northern Europe, <a href="#Page_58">58-60</a>, <a href="#Page_131">131-136</a>;<br /> - in the British Isles, <a href="#Page_136">136-181</a>;<br /> - in Northern Europe, <a href="#Page_181">181-190</a>;<br /> - in Australia, <a href="#Page_126">126</a>, <a href="#Page_192">192</a>; -<span class="pagenum"><a name="Page_379" id="Page_379">« 379 »</a></span><br /> - in Asia, <a href="#Page_190">190</a>, <a href="#Page_191">191</a>;<br /> - in Africa. 191, <a href="#Page_192">192</a>.<br /> -Glaciers, existing, in the Alps, <a href="#Page_9">9</a> <i>et seq.</i>, <a href="#Page_43">43</a> <i>et seq.</i>;<br /> - in Scandinavia, <a href="#Page_12">12</a>;<br /> - in Spitzbergen, Nova Zembla, and Franz-Josef Land, <a href="#Page_12">12</a>;<br /> - in Iceland, <a href="#Page_14">14</a>;<br /> - in Asia, <a href="#Page_14">14</a> <i>et seq.</i>;<br /> - in Oceanica, <a href="#Page_16">16</a>;<br /> - in South America, <a href="#Page_17">17</a>;<br /> - in Antarctic Continent, <a href="#Page_18">18</a> <i>et seq.</i>;<br /> - in North America, <a href="#Page_20">20</a> <i>et seq.</i>;<br /> - in Greenland, <a href="#Page_32">32</a> <i>et seq.</i>, <a href="#Page_46">46</a>, <a href="#Page_48">48</a>, <a href="#Page_364">364</a>.<br /> -Glen Roy, parallel roads of, <a href="#Page_239">239</a>.<br /> -Glutton, <a href="#Page_293">293</a>.<br /> -Goat, <a href="#Page_268">268</a>.<br /> -Goffstown, N. H., <a href="#Page_73">73</a>.<br /> -Grafton, W. Va., <a href="#Page_214">214</a>.<br /> -Grand Haven, Mich., <a href="#Page_346">346</a>.<br /> -Granville, Ohio, terrace at, <a href="#Page_227">227</a>, <a href="#Page_343">343</a>.<br /> -Grape Creek, Col., view of moraines of, <a href="#Page_123">123</a>.<br /> -Great Bend, Pa., depth of river-channel at, <a href="#Page_206">206</a>.<br /> -Great Lakes, depth of, <a href="#Page_115">115</a>; formation of, <a href="#Page_199">199</a> <i>et seq.</i>;<br /> - glacial outlets of, <a href="#Page_220">220-222</a>;<br /> - elevation about, <a href="#Page_224">224</a>.<br /> -Great Salt Lake, Utah, <a href="#Page_233">233</a> <i>et seq.</i>, <a href="#Page_350">350</a>.<br /> -Greece, human relics in glacial terraces of, <a href="#Page_264">264</a>.<br /> -Greenland, existing glaciers of, <a href="#Page_1">1</a>, <a href="#Page_32">32</a> <i>et seq.</i>, <a href="#Page_46">46</a>, <a href="#Page_48">48</a>,364;<br /> - map of, <a href="#Page_33">33</a>;<br /> - climate of, <a href="#Page_302">302</a>.<br /> -Gross Glockner, <a href="#Page_9">9</a>, <a href="#Page_134">134</a>.<br /> -Ground ice, <a href="#Page_357">357</a>.<br /> -Gulf of Mexico, <a href="#Page_313">313</a>, <a href="#Page_318">318</a>.<br /> -Gulf Stream, <a href="#Page_13">13</a>, <a href="#Page_311">311</a>, <a href="#Page_313">313</a>, <a href="#Page_317">317</a> <i>et seq.</i><br /> -Guyot, <a href="#Page_9">9</a>, <a href="#Page_58">58</a>, <a href="#Page_133">133</a>.<br /> -<br /> -Haas, <a href="#Page_16">16</a>.<br /> -Hall, on the age of Niagara, <a href="#Page_336">336</a>.<br /> -Hare, <a href="#Page_289">289</a>.<br /> -Harrison, quoted, <a href="#Page_167">167</a>.<br /> -Harte, Bret, cited, <a href="#Page_296">296</a>.<br /> -Hartz Mountains, <a href="#Page_136">136</a>, <a href="#Page_181">181</a>.<br /> -Hayes, <a href="#Page_36">36</a>.<br /> -Haynes on Tertiary Man, <a href="#Page_365">365-374</a>.<br /> -Heald Moor, England, <a href="#Page_147">147</a>.<br /> -Hebrides, the, <a href="#Page_136">136</a>.<br /> -Heim, <a href="#Page_9">9</a>.<br /> -Helland, <a href="#Page_14">14</a>, <a href="#Page_46">46-48</a>.<br /> -Hennepin, cited, <a href="#Page_340">340</a>.<br /> -Heme Bay, England, <a href="#Page_265">265</a>.<br /> -Herschel, cited, <a href="#Page_310">310</a>.<br /> -Hertfordshire, England, <a href="#Page_158">158</a>.<br /> -Hicks, Dr. II., cited, <a href="#Page_272">272</a>.<br /> -Hicks, L. E., cited, <a href="#Page_343">343</a>.<br /> -Himalayas, <a href="#Page_1">1</a>,45, <a href="#Page_292">292</a>, <a href="#Page_330">330</a>;<br /> - age of, <a href="#Page_328">328</a>.<br /> -Hingham, Mass., section of kame near, <a href="#Page_79">79</a>.<br /> -Hippopotamus, <a href="#Page_263">263</a>, <a href="#Page_265">265</a>, <a href="#Page_271">271</a>, <a href="#Page_280">280</a>, <a href="#Page_284">284</a>, <a href="#Page_285">285</a>, <a href="#Page_290">290</a>, <a href="#Page_292">292</a>.<br /> -Hitchcock, C. II., discovery of boulders on Mount Washington, <a href="#Page_60">60</a>;<br /> - on drumlins, <a href="#Page_73">73</a>;<br /> - cited, <a href="#Page_309">309</a>, <a href="#Page_313">313</a>.<br /> -Hitchcock, E., on kames, <a href="#Page_77">77</a>.<br /> -Holland, terminal moraine in, <a href="#Page_181">181</a>.<br /> -Holderness, <a href="#Page_157">157</a>.<br /> -Hooker, cited, <a href="#Page_191">191</a>.<br /> -Horse, <a href="#Page_188">188</a>, <a href="#Page_263">263</a>, <a href="#Page_268">268-270</a>, <a href="#Page_272">272</a>, <a href="#Page_278">278</a>, <a href="#Page_280">280</a>, <a href="#Page_288">288</a>, <a href="#Page_289">289</a>.<br /> -Horseheads, N. Y., <a href="#Page_220">220</a>.<br /> -Horseshoe Fall, <a href="#Page_337">337</a> <i>et seq.</i><br /> -Hottentot skull, <a href="#Page_276">276</a>.<br /> -Hoxney, England, <a href="#Page_266">266</a>.<br /> -Hudson River, preglacial channel of, <a href="#Page_194">194</a> <i>et seq.</i><br /> -Hugi, <a href="#Page_9">9</a>, <a href="#Page_43">43</a>.<br /> -Hungary, Quaternary animals in, <a href="#Page_279">279</a>.<br /> -Huxley, cited, <a href="#Page_276">276</a>, <a href="#Page_278">278</a>.<br /> -Hyena, <a href="#Page_271">271</a>, <a href="#Page_272">272</a>, <a href="#Page_282">282</a>, <a href="#Page_291">291</a>, <a href="#Page_292">292</a>.<br /> -<br /> -Ibex, <a href="#Page_289">289</a>.<br /> -Icebergs, <a href="#Page_18">18</a>, <a href="#Page_20">20</a>;<br /> - formation of, <a href="#Page_28">28</a>.<br /> -Ice, characteristics of, <a href="#Page_2">2</a>, <a href="#Page_48">48</a> <i>et seq.</i>, <a href="#Page_302">302</a> <i>et seq.</i>;<br /> - transporting power of moving, <a href="#Page_5">5</a>.<br /> -Ice-dams, <a href="#Page_211">211-228</a>;<br /> - in the Alps, <a href="#Page_211">211</a>;<br /> - in the Himalayas, <a href="#Page_211">211</a>;<br /> - in Greenland, <a href="#Page_212">212</a>;<br /> - in Alaska, <a href="#Page_212">212</a>;<br /> - at Cincinnati, <a href="#Page_213">213</a> <i>et seq.</i>;<br /> - across the Mohawk, <a href="#Page_92">92</a>, <a href="#Page_220">220</a>, <a href="#Page_334">334</a>, <a href="#Page_335">335</a>;<br /> - in the Red River of the North, <a href="#Page_225">225</a>;<br /> - in Europe, <a href="#Page_360">360</a>.<br /> -Iceland, existing glaciers of, <a href="#Page_1">1</a>, <a href="#Page_14">14</a>.<br /> -Ice-pillars, <a href="#Page_6">6</a>, <a href="#Page_27">27</a>.<br /> -Ice-sheet, retreat of, <a href="#Page_333">333</a> <i>et seq.</i><br /> -Idaho, <a href="#Page_122">122</a>; lava-beds of, <a href="#Page_297">297</a>.<br /> -Illicilliwaet Glacier, <a href="#Page_23">23</a>.<br /> -Illinois, <a href="#Page_96">96-98</a>, <a href="#Page_100">100</a>, <a href="#Page_119">119</a>, <a href="#Page_121">121</a>, <a href="#Page_345">345</a> <i>et seq.</i><br /> -Indiana, <a href="#Page_96">96</a>, <a href="#Page_98">98</a>, <a href="#Page_107">107</a>, <a href="#Page_119">119</a>, <a href="#Page_121">121</a>.<br /> -Indian Ridge, <a href="#Page_80">80</a>.<br /> -Iowa, <a href="#Page_98">98</a>, <a href="#Page_101">101</a>.<br /> -Ireland, ancient glaciers of, <a href="#Page_143">143</a>.<br /> -Irish elk, <a href="#Page_270">270</a>, <a href="#Page_278">278</a>, <a href="#Page_288">288</a>.<br /> -Irish Sea Glacier, <a href="#Page_137">137</a>, <a href="#Page_145">145-153</a>, <a href="#Page_164">164</a>, <a href="#Page_271">271</a>.<br /> -Irthing, valley of the, <a href="#Page_153">153</a>.<br /> -Isère, glaciers of the, <a href="#Page_132">132</a>.<br /> -Isle of Man, <a href="#Page_164">164-167</a>.<br /> -Isle of Wight, <a href="#Page_266">266</a>.<br /> -Italy, existing glaciers of, <a href="#Page_9">9</a>;<br /> - ancient glaciers of, <a href="#Page_185">185</a>;<br /> - human relics in glacial terraces of, <a href="#Page_264">264</a>;<br /> - supposed Tertiary man in, <a href="#Page_366">366</a>.<br /> -Ivrea, <a href="#Page_134">134</a>.<br /> -<br /> -Jackson, cited, <a href="#Page_357">357</a>. -<span class="pagenum"><a name="Page_380" id="Page_380">« 380 »</a></span><br /> -Jackson’s Lake, <a href="#Page_123">123</a>.<br /> -Jakobshavn Glacier, velocity of, <a href="#Page_46">46</a>, <a href="#Page_47">47</a>;<br /> - depth of, <a href="#Page_91">91</a>;<br /> - ice-dams of, <a href="#Page_212">212</a>.<br /> -James, cited, <a href="#Page_204">204</a>.<br /> -James River, Dak., <a href="#Page_228">228</a>.<br /> -James River, Va., <a href="#Page_257">257</a>.<br /> -Jamieson, cited, <a href="#Page_330">330</a>.<br /> -Jensen, <a href="#Page_91">91</a>.<br /> -Judge’s Cave, <a href="#Page_72">72</a>.<br /> -Jura Mountains, ancient glaciers of, <a href="#Page_58">58-60</a>, <a href="#Page_132">132</a>.<br /> -<br /> -Kames, formation of, <a href="#Page_7">7</a>, <a href="#Page_76">76</a>, <a href="#Page_77">77</a>;<br /> - of Muir Glacier, <a href="#Page_29">29</a>, <a href="#Page_30">30</a>;<br /> - in Massachusetts, <a href="#Page_77">77</a> <i>et seq.</i>;<br /> - in New Hampshire, <a href="#Page_80">80</a>;<br /> - map of, in Maine, <a href="#Page_81">81</a>;<br /> - in Pennsylvania, <a href="#Page_87">87</a>.<br /> -Kanawha River, <a href="#Page_216">216</a>.<br /> -Kane, <a href="#Page_36">36-38</a>.<br /> -Kansas, <a href="#Page_96">96</a>.<br /> -Kelly’s Island, view of grooves on, <a href="#Page_103">103</a>, <a href="#Page_105">105</a>.<br /> -Kendall, chapter by, <a href="#Page_137">137-181</a>;<br /> - cited, <a href="#Page_273">273</a>.<br /> -Kent, England, <a href="#Page_265">265</a>.<br /> -Kent’s Hole, <a href="#Page_267">267</a> <i>et seq.</i>, <a href="#Page_352">352</a> <i>et seq.</i><br /> -Kentucky, <a href="#Page_63">63</a>, <a href="#Page_96">96</a>, <a href="#Page_97">97</a>, <a href="#Page_212">212</a>;<br /> - view of boulder in, <a href="#Page_63">63</a>.<br /> -Kentucky River, <a href="#Page_214">214</a>.<br /> -Kettle-holes, formation of, <a href="#Page_7">7</a>, <a href="#Page_68">68</a>;<br /> - of Muir Glacier, <a href="#Page_29">29</a>, <a href="#Page_30">30</a>;<br /> - in New England, <a href="#Page_66">66</a> <i>et seq.</i>, <a href="#Page_344">344</a>, <a href="#Page_345">345</a>;<br /> - in Pennsylvania, <a href="#Page_86">86</a>;<br /> - sedimentation of, <a href="#Page_333">333</a>, <a href="#Page_344">344</a> <i>et seq.</i><br /> -Kettle-moraine in Wisconsin, <a href="#Page_100">100</a>.<br /> -King, <a href="#Page_21">21</a>, <a href="#Page_351">351</a>;<br /> - implement discovered by, <a href="#Page_297">297</a>.<br /> -Knox County, Ohio, <a href="#Page_232">232</a>.<br /> -Kurtz, Nam pa image discovered by, <a href="#Page_297">297</a>.<br /> -<br /> -Lake Agassiz, <a href="#Page_126">126</a>, <a href="#Page_223">223</a>, <a href="#Page_225">225</a>;<br /> - continuance of, <a href="#Page_347">347</a> <i>et seq.</i><br /> -Lake Bonneville, <a href="#Page_233">233</a> <i>et seq.</i>, <a href="#Page_299">299</a>, <a href="#Page_350">350</a> <i>et seq.</i><br /> -Lake Constance, <a href="#Page_60">60</a>, <a href="#Page_133">133</a>.<br /> -Lake Erie, origin of, <a href="#Page_200">200</a> <i>et seq.</i>;<br /> - ridges around, <a href="#Page_222">222</a>;<br /> - preglacial outlet of, <a href="#Page_200">200</a>, <a href="#Page_333">333</a>.<br /> -Lake Geneva during the Glacial period, <a href="#Page_131">131</a>, <a href="#Page_132">132</a>.<br /> -Lake Huron, preglacial outlet of, <a href="#Page_202">202</a>;<br /> - ridges around, <a href="#Page_224">224</a>.<br /> -Lake Itasca, <a href="#Page_254">254</a>.<br /> -Lake Lahontan, <a href="#Page_233">233</a>, <a href="#Page_234">234</a>.<br /> -Lake Michigan, age of, <a href="#Page_345">345</a> <i>et seq.</i><br /> -Lake Nipissing, <a href="#Page_339">339</a>.<br /> -Lake Ontario, origin of, <a href="#Page_201">201</a> <i>et seq.</i><br /> -Lake Traverse, <a href="#Page_208">208</a>, <a href="#Page_226">226</a>.<br /> -Lake District, England, the, <a href="#Page_144">144</a>.<br /> -Lake dwellings in Switzerland, <a href="#Page_281">281</a>.<br /> -Lake ridges, <a href="#Page_222">222</a> <i>et seq.</i><br /> -Lakes, sedimentation of, <a href="#Page_333">333</a>, <a href="#Page_344">344</a> <i>et seq.</i><br /> -Lamplugh, glacial observations of, <a href="#Page_140">140</a>, <a href="#Page_196">196</a>.<br /> -Lancashire, <a href="#Page_153">153</a>, <a href="#Page_178">178</a>, <a href="#Page_180">180</a>.<br /> -Lancaster, Ohio, <a href="#Page_232">232</a>.<br /> -Lang, cited, <a href="#Page_116">116</a>.<br /> -Lark, England, valley of the, <a href="#Page_266">266</a>.<br /> -Lateral moraines, <a href="#Page_5">5</a>.<br /> -Laurentide Glacier, <a href="#Page_113">113</a> <i>et seq.</i>, <a href="#Page_121">121</a>, <a href="#Page_321">321</a>.<br /> -Lava on the Pacific coast of North America, <a href="#Page_294">294</a>, <a href="#Page_298">298</a>, <a href="#Page_300">300</a>, <a href="#Page_306">306</a>, <a href="#Page_321">321</a>.<br /> -Lawrence, Mass., <a href="#Page_80">80</a>.<br /> -Lawrenceburg, Ind., <a href="#Page_231">231</a>, <a href="#Page_232">232</a>.<br /> -Le Conte, cited, <a href="#Page_286">286</a>, <a href="#Page_322">322</a> <i>et seq.</i>, <a href="#Page_330">330</a>, <a href="#Page_372">372</a>.<br /> -Leicestershire, England, <a href="#Page_158">158</a>.<br /> -Lehigh River, <a href="#Page_243">243</a>.<br /> -Lemming, <a href="#Page_289">289</a>.<br /> -Lenticular hills, <a href="#Page_73">73</a>.<br /> -Leopard, <a href="#Page_282">282</a>.<br /> -Lesley, cited, <a href="#Page_215">215</a>.<br /> -Lesse, Belgium, valley of the, <a href="#Page_279">279</a>.<br /> -Leverett, cited, <a href="#Page_101">101</a>, <a href="#Page_218">218</a>.<br /> -Lewis, on transported boulders, <a href="#Page_57">57</a>, <a href="#Page_61">61</a>;<br /> - work of, in Pennsylvania, <a href="#Page_84">84</a>, <a href="#Page_119">119</a>;<br /> - in Great Britain, <a href="#Page_137">137</a>;<br /> - cited, <a href="#Page_254">254</a> <i>et seq.</i>, <a href="#Page_273">273</a>.<br /> -Lickey Hills, <a href="#Page_151">151</a>.<br /> -Licking River, <a href="#Page_214">214</a>.<br /> -Liége, Belgium, <a href="#Page_274">274</a>.<br /> -Lincolnshire, England, <a href="#Page_158">158</a>.<br /> -Lindenkohl on old channel of the Hudson, <a href="#Page_195">195</a> <i>et seq.</i><br /> -Lion, <a href="#Page_282">282</a>, <a href="#Page_293">293</a>.<br /> -Little Beaver Creek, <a href="#Page_231">231</a>, <a href="#Page_232">232</a>.<br /> -Little Falls, Minn., <a href="#Page_225">225</a>, <a href="#Page_232">232</a>, <a href="#Page_252">252</a>, <a href="#Page_254">254</a>.<br /> -Little Falls, N. Y., buried channel near, <a href="#Page_202">202</a>.<br /> -Livingston, Mont., <a href="#Page_122">122</a>.<br /> -Llangollen, vale of, <a href="#Page_151">151</a>.<br /> -Loess in the Mississippi Valley, <a href="#Page_98">98</a>, <a href="#Page_119">119</a>, <a href="#Page_120">120</a>;<br /> - in Europe, <a href="#Page_186">186</a> <i>et seq.</i><br /> -Lohest, cited, <a href="#Page_275">275</a> <i>et seq.</i><br /> -Lombardy, <a href="#Page_134">134</a>.<br /> -London, <a href="#Page_158">158</a>, <a href="#Page_159">159</a>, <a href="#Page_178">178</a>;<br /> - glacial terrace in, <a href="#Page_264">264</a>.<br /> -Long Island, <a href="#Page_66">66</a>, <a href="#Page_67">67</a>.<br /> -Louisville, Ky., buried channel near, <a href="#Page_205">205</a>.<br /> -Loveland, Ohio, <a href="#Page_232">232</a>, <a href="#Page_250">250</a>.<br /> -Lubbock, cited, <a href="#Page_267">267</a>.<br /> -Lucerne, <a href="#Page_133">133</a>.<br /> -Lyell, on Richmond train of boulders, <a href="#Page_70">70</a>;<br /> - cited, <a href="#Page_239">239</a>, <a href="#Page_263">263</a>, <a href="#Page_267">267</a>, <a href="#Page_274">274</a>, <a href="#Page_276">276</a>, <a href="#Page_285">285</a>, <a href="#Page_355">355</a>, <a href="#Page_361">361</a>;<br /> - on the age of Niagara, <a href="#Page_336">336</a>. -<span class="pagenum"><a name="Page_381" id="Page_381">« 381 »</a></span><br /> -Lyons, <a href="#Page_132">132</a>.<br /> -<br /> -Maack, cited, <a href="#Page_318">318</a>.<br /> -Macclesfield, England, <a href="#Page_273">273</a>.<br /> -MacEnery, cited, <a href="#Page_267">267</a>.<br /> -Machairodus, <a href="#Page_270">270</a>, <a href="#Page_282">282</a>.<br /> -Mackintosh, quoted, <a href="#Page_149">149</a>, <a href="#Page_150">150</a>, <a href="#Page_173">173</a>.<br /> -Mâcon, France, <a href="#Page_369">369</a>.<br /> -McTarnahan, mortar discovered by, <a href="#Page_297">297</a>.<br /> -Madison boulder, <a href="#Page_71">71</a>.<br /> -Madisonville, Ohio, <a href="#Page_232">232</a>, <a href="#Page_250">250</a>, <a href="#Page_254">254</a>.<br /> -Magdalena Bay, <a href="#Page_13">13</a>.<br /> -Mahoning River, <a href="#Page_220">220</a>.<br /> -Maine, <a href="#Page_80">80</a>; re-elevation of, <a href="#Page_331">331</a>.<br /> -Malaspina Glacier, map of, <a href="#Page_31">31</a>.<br /> -Mammoth, <a href="#Page_188">188</a>, <a href="#Page_190">190</a>, <a href="#Page_263">263</a>, <a href="#Page_265">265</a>, <a href="#Page_269">269-272</a>, <a href="#Page_278">278</a>, <a href="#Page_280">280</a>, <a href="#Page_283">283-285</a>, <a href="#Page_287">287</a>, <a href="#Page_292">292</a>, <a href="#Page_293">293</a>.<br /> -Man, relics of, in the Glacial period, chapter on, <a href="#Page_242">242-301</a>;<br /> - in glacial terraces of the United States, <a href="#Page_242">242-262</a>;<br /> - of Europe, <a href="#Page_262">262-267</a>;<br /> - in cave deposits of British Isles, <a href="#Page_148">148</a>, <a href="#Page_267">267-274</a>;<br /> - of the Continent, <a href="#Page_274">274-281</a>;<br /> - under lava-beds of the Pacific coast of North America, <a href="#Page_294">294-301</a>;<br /> - extinct animals associated with, <a href="#Page_281">281-293</a>.<br /> -Manitoba, <a href="#Page_97">97</a>.<br /> -Mankato, Minn., <a href="#Page_229">229</a>.<br /> -Marcilly, skull at, <a href="#Page_279">279</a>.<br /> -Marietta, Ohio, <a href="#Page_231">231</a>.<br /> -Marmot, <a href="#Page_289">289</a>, <a href="#Page_293">293</a>.<br /> -Marsh Creek Valley, Utah, <a href="#Page_233">233</a>.<br /> -Martigny, ancient glaciers near, <a href="#Page_59">59</a>, <a href="#Page_60">60</a>, <a href="#Page_131">131</a>, <a href="#Page_211">211</a>.<br /> -Massachusetts, <a href="#Page_67">67</a> <i>et seq.</i>, <a href="#Page_73">73</a>, <a href="#Page_77">77</a> <i>et seq.</i>, <a href="#Page_81">81</a>, <a href="#Page_344">344</a>, <a href="#Page_345">345</a>.<br /> -Mastodon, <a href="#Page_262">262</a>, <a href="#Page_278">278</a>, <a href="#Page_285">285</a>, <a href="#Page_286">286</a>.<br /> -Mattmark See, <a href="#Page_211">211</a>.<br /> -Maumee River, <a href="#Page_220">220</a>.<br /> -McGee, cited, <a href="#Page_245">245</a>, <a href="#Page_254">254</a> <i>et seq.</i><br /> -Medial moraines, formation of, <a href="#Page_6">6</a>;<br /> - of Muir Glacier, <a href="#Page_27">27</a>;<br /> - in Ohio, <a href="#Page_100">100</a>.<br /> -Medlicott, cited, <a href="#Page_312">312</a>.<br /> -Medora, Ind., <a href="#Page_232">232</a>, <a href="#Page_251">251</a>, <a href="#Page_254">254</a>.<br /> -Menai Straits, <a href="#Page_145">145</a>.<br /> -Mentone, skeleton of, <a href="#Page_281">281</a>.<br /> -Mer de Glace, <a href="#Page_11">11</a>, <a href="#Page_44">44</a>.<br /> -Merjelen See, <a href="#Page_211">211</a>, <a href="#Page_241">241</a>.<br /> -Mersey, the, <a href="#Page_140">140</a>.<br /> -Meteorites, <a href="#Page_305">305</a>.<br /> -Metz, cited, <a href="#Page_250">250</a>.<br /> -Meuse, valley of, <a href="#Page_274">274</a> <i>et seq.</i><br /> -Miami, the Great, <a href="#Page_204">204</a>, <a href="#Page_220">220</a>.<br /> -Miami, the Little, <a href="#Page_231">231</a>, <a href="#Page_250">250</a>.<br /> -Millersburg, Ohio, <a href="#Page_232">232</a>.<br /> -Mills, cited, <a href="#Page_251">251</a>.<br /> -Minneapolis, <a href="#Page_232">232</a>; buried outlet near, <a href="#Page_208">208</a>;<br /> - recession of falls at, <a href="#Page_210">210</a>, <a href="#Page_340">340</a> <i>et seq.</i>, <a href="#Page_364">364</a>.<br /> -Minnehaha, Falls of, <a href="#Page_342">342</a>.<br /> -Minnesota, <a href="#Page_101">101</a>, <a href="#Page_107">107</a>, <a href="#Page_252">252</a> <i>et seq.</i>;<br /> - lakes of, <a href="#Page_344">344</a>.<br /> -Minnesota River, a glacial outlet, <a href="#Page_208">208</a>, <a href="#Page_225">225</a>, <a href="#Page_228">228</a>, <a href="#Page_342">342</a>.<br /> -Miocene epoch, animals of the, <a href="#Page_285">285</a>.<br /> -Mississippi River, gorge of, at Fort Snelling, <a href="#Page_208">208</a>, <a href="#Page_364">364</a>;<br /> - terraces on, <a href="#Page_229">229</a>;<br /> - erosion by, <a href="#Page_329">329</a>;<br /> - glacial drainage of, <a href="#Page_335">335</a>, <a href="#Page_340">340</a>.<br /> -Missouri Coteau, <a href="#Page_101">101</a>, <a href="#Page_126">126</a>, <a href="#Page_228">228</a>.<br /> -Missouri, <a href="#Page_96">96</a>, <a href="#Page_98">98</a>, <a href="#Page_119">119</a>.<br /> -Moel Tryfaen, <a href="#Page_145">145</a>, <a href="#Page_167">167</a> <i>et seq.</i>, <a href="#Page_178">178</a>, <a href="#Page_273">273</a>.<br /> -Mohawk River, glacial drainage of, <a href="#Page_92">92</a>, <a href="#Page_202">202</a>, <a href="#Page_335">335</a>;<br /> - ice-dam across, <a href="#Page_220">220</a>, <a href="#Page_334">334</a>, <a href="#Page_335">335</a>.<br /> -Mohegan Bock, <a href="#Page_71">71</a>; view of, <a href="#Page_72">72</a>.<br /> -Monongahela River, <a href="#Page_214">214</a> <i>et seq.</i><br /> -Montaigle, valley of the, <a href="#Page_279">279</a>.<br /> -Montana, <a href="#Page_96">96</a>.<br /> -Montreal, re-elevation of, <a href="#Page_331">331</a>.<br /> -Moose, <a href="#Page_262">262</a>.<br /> -Moraines, formation of, <a href="#Page_6">6</a>;<br /> - in Wisconsin, <a href="#Page_98">98-100</a>;<br /> - in Italy, <a href="#Page_134">134</a>, <a href="#Page_135">135</a>;<br /> - between Speeton and Flamborough, <a href="#Page_156">156</a>;<br /> - in Germany, <a href="#Page_183">183</a>.<br /> -Morecambe Bay, <a href="#Page_146">146</a>, <a href="#Page_180">180</a>.<br /> -Morgantown, W. Va., <a href="#Page_215">215</a>.<br /> -Morlot, cited, <a href="#Page_354">354</a>.<br /> -Mortillet, cited, <a href="#Page_366">366</a>, <a href="#Page_369">369</a>, <a href="#Page_372">372</a>.<br /> -Morvan, the, <a href="#Page_136">136</a>.<br /> -Moulins, formation of, <a href="#Page_7">7</a>.<br /> -Mount Shasta, <a href="#Page_21">21</a>.<br /> -Mount Washington, <a href="#Page_61">61</a>.<br /> -Mueller Glacier, <a href="#Page_17">17</a>.<br /> -Muir Glacier, <a href="#Page_24">24</a> <i>et seq.</i>. 47, <a href="#Page_68">68</a>, <a href="#Page_212">212</a>;<br /> - view of front of, <a href="#Page_26">26</a>.<br /> -Muir, John, <a href="#Page_24">24</a>.<br /> -Muskingum River, <a href="#Page_220">220</a>, <a href="#Page_231">231</a>.<br /> -Musk ox, <a href="#Page_262">262</a>, <a href="#Page_280">280</a>.<br /> -Musk sheep, <a href="#Page_289">289</a>, <a href="#Page_290">290</a>, <a href="#Page_293">293</a>.<br /> -<br /> -Nampa image, <a href="#Page_297">297</a> <i>et seq.</i><br /> -Nansen, <a href="#Page_39">39</a>, <a href="#Page_41">41</a>.<br /> -Naulette, jaw found at, <a href="#Page_278">278</a>, <a href="#Page_279">279</a>.<br /> -Neale, implements discovered by, <a href="#Page_296">296</a>, <a href="#Page_373">373</a>.<br /> -Neanderthal skull, <a href="#Page_275">275</a> <i>et seq.</i><br /> -Nebraska, <a href="#Page_96">96</a>.<br /> -Nelson River, <a href="#Page_349">349</a>.<br /> -Neufchâtel, <a href="#Page_133">133</a>.<br /> -Nevada, <a href="#Page_124">124</a>; lakes of, <a href="#Page_233">233</a>.<br /> -Névé-field defined, <a href="#Page_3">3</a>.<br /> -Newark, Ohio, <a href="#Page_232">232</a>.<br /> -Newberry on the preglacial drainage of the Hudson, <a href="#Page_195">195</a> <i>et seq.</i>;<br /> - on the formation of the Great Lakes, <a href="#Page_202">202</a> <i>et seq.</i>; -<span class="pagenum"><a name="Page_382" id="Page_382">« 382 »</a></span><br /> - cited, <a href="#Page_320">320</a>.<br /> -Newburg, N. Y., <a href="#Page_286">286</a>.<br /> -New Comerstown, implement from, <a href="#Page_232">232</a>, <a href="#Page_250">250</a>, <a href="#Page_251">251</a> <i>et seq.</i>, <a href="#Page_254">254</a>.<br /> -New England, <a href="#Page_57">57</a>, <a href="#Page_60">60</a>, <a href="#Page_61">61</a>, <a href="#Page_91">91</a>;<br /> - ancient glaciers in, <a href="#Page_66">66-83</a>.<br /> -New Hampshire, <a href="#Page_69">69</a>, <a href="#Page_71">71</a>, <a href="#Page_74">74</a>, <a href="#Page_80">80</a>.<br /> -New Harmony, Ind., <a href="#Page_232">232</a>.<br /> -New Jersey, <a href="#Page_83">83</a>.<br /> -New Lisbon, Ohio, <a href="#Page_232">232</a>.<br /> -New York, <a href="#Page_74">74</a>, <a href="#Page_84">84</a>, <a href="#Page_88">88</a>, <a href="#Page_91">91</a>, <a href="#Page_92">92</a> <i>et seq.</i><br /> -New York Bay, <a href="#Page_184">184</a>, <a href="#Page_197">197</a>, <a href="#Page_249">249</a>.<br /> -New Zealand, <a href="#Page_1">1</a>, <a href="#Page_126">126</a>, <a href="#Page_192">192</a>, <a href="#Page_330">330</a>.<br /> -Niagara gorge, age of, <a href="#Page_333">333</a> <i>et seq.</i>;<br /> - section of strata along the, <a href="#Page_336">336</a>.<br /> -Nile River, <a href="#Page_285">285</a>.<br /> -Nordenskiöld, <a href="#Page_32">32</a>, <a href="#Page_34">34</a>.<br /> -Norfolk, England, <a href="#Page_161">161</a>.<br /> -North America, existing glaciers in, <a href="#Page_20">20</a> <i>et seq.</i><br /> -North Sea, <a href="#Page_238">238</a>.<br /> -Norway, climate of, <a href="#Page_314">314</a>.<br /> -Nottingham, England, <a href="#Page_164">164</a>.<br /> -Nova Zembla, <a href="#Page_14">14</a>.<br /> -<br /> -Oberlin, Ohio, <a href="#Page_64">64</a>, <a href="#Page_344">344</a>.<br /> -Oceanica, existing glaciers of, <a href="#Page_16">16</a>, <a href="#Page_17">17</a>.<br /> -Ohio River, glacial terrace, <a href="#Page_217">217</a>, <a href="#Page_229">229</a>.<br /> -Ohio, <a href="#Page_64">64</a>,72, <a href="#Page_95">95</a>, <a href="#Page_98">98</a>, <a href="#Page_100">100</a>, <a href="#Page_103">103</a>, <a href="#Page_106">106</a>,107-117, <a href="#Page_119">119</a>, <a href="#Page_217">217</a>, <a href="#Page_249">249</a> <i>et seq.</i>, <a href="#Page_343">343</a>, <a href="#Page_344">344</a>.<br /> -Oil Creek, <a href="#Page_205">205</a>, <a href="#Page_232">232</a>.<br /> -Olmo, skull at, <a href="#Page_279">279</a>.<br /> -Oregon, <a href="#Page_21">21</a>, <a href="#Page_124">124</a>.<br /> -Orme’s Head, Little, <a href="#Page_147">147</a>.<br /> -Orton, cited, <a href="#Page_72">72</a>, <a href="#Page_107">107</a>.<br /> -Oscillations of land-level in America, <a href="#Page_124">124</a> <i>et seq.</i><br /> -Oswestry. England, <a href="#Page_173">173</a>.<br /> -Ottawa River, <a href="#Page_339">339</a>.<br /> -Otter, <a href="#Page_290">290</a>.<br /> -Ouse, valley of the, <a href="#Page_265">265</a>.<br /> -Ox, <a href="#Page_269">269</a>, <a href="#Page_270">270</a>.<br /> -<br /> -Pacific coast of America, <a href="#Page_349">349</a>.<br /> -Pacific Ocean, <a href="#Page_318">318</a>, <a href="#Page_320">320</a>.<br /> -Panama, Isthmus of, <a href="#Page_113">113</a>, <a href="#Page_313">313</a>, <a href="#Page_314">314</a>, <a href="#Page_318">318</a>.<br /> -Parsimony, law of, <a href="#Page_117">117</a>.<br /> -Pasterzen Glacier, <a href="#Page_134">134</a>.<br /> -Patagonia, <a href="#Page_1">1</a>.<br /> -Patton, <a href="#Page_25">25</a>.<br /> -Payer, <a href="#Page_14">14</a>, <a href="#Page_39">39</a>.<br /> -Peat-beds, <a href="#Page_68">68</a>, <a href="#Page_125">125</a>;<br /> - in Ohio, <a href="#Page_107">107</a>;<br /> - in Minnesota, <a href="#Page_108">108</a>;<br /> - in valley of the Somme, <a href="#Page_355">355</a> <i>et seq.</i><br /> -Pembina River, <a href="#Page_228">228</a>.<br /> -Pengelly, cited, <a href="#Page_267">267</a>, <a href="#Page_270">270</a>.<br /> -Pennine Chain, glaciation of, <a href="#Page_137">137</a>, <a href="#Page_144">144</a>, <a href="#Page_146">146</a>, <a href="#Page_147">147</a>, <a href="#Page_154">154</a>, <a href="#Page_177">177</a>.<br /> -Pennsylvania, <a href="#Page_57">57</a>, <a href="#Page_61">61</a>, <a href="#Page_84">84</a> <i>et seq.</i>, <a href="#Page_119">119</a>, <a href="#Page_217">217</a>.<br /> -Perry County, Ohio, <a href="#Page_232">232</a>.<br /> -Perthes, Boucher de, <a href="#Page_262">262</a> <i>et seq.</i><br /> -Philadelphia Academy of Sciences, <a href="#Page_296">296</a>.<br /> -Philadelphia, red gravel of, <a href="#Page_254">254</a> <i>et seq.</i><br /> -Phillips, cited, <a href="#Page_267">267</a>.<br /> -Picardy, glacial gravels of, <a href="#Page_262">262</a>.<br /> -Pittsburg, Pa., submergence of, <a href="#Page_214">214</a>, <a href="#Page_217">217</a>, <a href="#Page_230">230</a>.<br /> -Plum Creek, Ohio, <a href="#Page_344">344</a>.<br /> -Po, valley of the, <a href="#Page_135">135</a>;<br /> - erosion by, <a href="#Page_328">328</a>.<br /> -Pocatello, Idaho, <a href="#Page_236">236</a>, <a href="#Page_299">299</a>.<br /> -Pocono Mountain, <a href="#Page_61">61</a>.<br /> -Poland, <a href="#Page_181">181</a>.<br /> -Polynesian skull, <a href="#Page_276">276</a>.<br /> -Pomp’s Pond, section of kettle-hole near, <a href="#Page_345">345</a>.<br /> -Portageville, N. Y., <a href="#Page_220">220</a>.<br /> -Port Neuf River, Idaho, <a href="#Page_236">236</a>.<br /> -Portsmouth, Ohio, <a href="#Page_231">231</a>.<br /> -Portugal, human relics in glacial terraces of, <a href="#Page_264">264</a>;<br /> - supposed Tertiary man in, <a href="#Page_367">367</a>, <a href="#Page_371">371</a> <i>et seq.</i><br /> -Post-glacial erosion, <a href="#Page_332">332</a> <i>et seq.</i>;<br /> - in Ohio, <a href="#Page_343">343</a>, <a href="#Page_344">344</a>;<br /> - in Illinois, <a href="#Page_345">345</a> <i>et seq.</i><br /> -Potomac River, <a href="#Page_256">256</a> <i>et seq.</i><br /> -Pot-holes in Lucerne, <a href="#Page_133">133</a>.<br /> -Pouchet, cited, <a href="#Page_263">263</a>.<br /> -Precession of equinoxes, <a href="#Page_308">308</a>.<br /> -Preglacial climate in England, <a href="#Page_141">141</a>, <a href="#Page_142">142</a>.<br /> -Preglacial levels in England, <a href="#Page_139">139-142</a>.<br /> -Prestwich, cited, <a href="#Page_186">186</a>, <a href="#Page_189">189</a>, <a href="#Page_263">263</a> <i>et seq.</i>, <a href="#Page_284">284</a>;<br /> - on date of Glacial period, <a href="#Page_354">354</a>, <a href="#Page_357">357</a>, <a href="#Page_363">363</a>, <a href="#Page_364">364</a>.<br /> -Provo shore-line, <a href="#Page_237">237</a>.<br /> -Putnam, cited, <a href="#Page_250">250</a>.<br /> -Puy-Courny, France, supposed Tertiary man at, <a href="#Page_367">367</a>, <a href="#Page_370">370</a>, <a href="#Page_371">371</a>.<br /> -Pyramid Lake, <a href="#Page_350">350</a>.<br /> -Pyrenees, glaciers of the, <a href="#Page_11">11</a>, <a href="#Page_136">136</a>;<br /> - Quaternary animals of, <a href="#Page_280">280</a>, <a href="#Page_282">282</a>;<br /> - age of, <a href="#Page_328">328</a>.<br /> -<br /> -Quaternary animals of California, <a href="#Page_281">281</a>, <a href="#Page_287">287</a>;<br /> - in Germany, <a href="#Page_279">279</a>;<br /> - in Hungary, <a href="#Page_279">279</a>.<br /> -Quatrefages, cited, <a href="#Page_276">276</a>.<br /> -Queenston, Canada, <a href="#Page_333">333</a> <i>et seq.</i><br /> -<br /> -Rabbit, <a href="#Page_289">289</a>.<br /> -Raccoon Creek, <a href="#Page_343">343</a>;<br /> - view of glacial terrace near, <a href="#Page_227">227</a>.<br /> -Rames, cited, <a href="#Page_370">370</a>, <a href="#Page_371">371</a>.<br /> -Ramsay, cited, <a href="#Page_311">311</a>. -<span class="pagenum"><a name="Page_383" id="Page_383">« 383 »</a></span><br /> -Rappahannock River, <a href="#Page_257">257</a>.<br /> -Rawhide Gulch, Cal., <a href="#Page_296">296</a>.<br /> -Recession, rate of, of Falls of Niagara, <a href="#Page_333">333</a> <i>et seq.</i>;<br /> - of Falls of St. Anthony, <a href="#Page_340">340</a> <i>et seq.</i>, <a href="#Page_364">364</a>;<br /> - of Black River, <a href="#Page_342">342</a>, <a href="#Page_343">343</a>.<br /> -Red deer, <a href="#Page_263">263</a>.<br /> -Red River of the North, <a href="#Page_209">209</a>, <a href="#Page_228">228</a>, <a href="#Page_340">340</a>;<br /> - ice-dam in, <a href="#Page_225">225</a>.<br /> -Regillout, <a href="#Page_263">263</a>.<br /> -Reid, Clement, quoted, <a href="#Page_162">162</a>.<br /> -Reid, H. F., <a href="#Page_26">26</a>, <a href="#Page_47">47</a>.<br /> -Reindeer, <a href="#Page_188">188</a>, <a href="#Page_262">262</a>, <a href="#Page_263">263</a>, <a href="#Page_269">269</a>, <a href="#Page_270">270</a>, <a href="#Page_278">278</a>, <a href="#Page_280">280</a>, <a href="#Page_287">287</a>, <a href="#Page_290">290</a>, <a href="#Page_293">293</a>.<br /> -Rhine, ancient glaciers of the, <a href="#Page_129">129</a>, <a href="#Page_133">133</a>.<br /> -Rhinoceros, <a href="#Page_188">188</a>, <a href="#Page_263">263</a>, <a href="#Page_265">265</a>, <a href="#Page_271">271</a>, <a href="#Page_277">277</a>, <a href="#Page_278">278</a>, <a href="#Page_280">280</a>, <a href="#Page_284">284</a>, <a href="#Page_286">286</a>, <a href="#Page_287">287</a>, <a href="#Page_292">292</a>;<br /> - woolly, <a href="#Page_269">269</a>, <a href="#Page_270">270</a>, <a href="#Page_272">272</a>, <a href="#Page_280">280</a>, <a href="#Page_287">287</a>.<br /> -Rhode Island, <a href="#Page_67">67</a>.<br /> -Rhône, ancient glaciers of, <a href="#Page_58">58-60</a>, <a href="#Page_131">131</a>,132, <a href="#Page_185">185</a>, <a href="#Page_188">188</a>;<br /> - map of, <a href="#Page_58">58</a>.<br /> -Richmond, Mass., train of boulders in, <a href="#Page_70">70</a>, <a href="#Page_71">71</a>.<br /> -Rink, Dr., <a href="#Page_35">35</a>.<br /> -Roanoke River, <a href="#Page_257">257</a>.<br /> -Rocky Mountains, <a href="#Page_320">320</a>, <a href="#Page_322">322</a>;<br /> - age of the, <a href="#Page_328">328</a>.<br /> -<a id="Rock-Scoring" name="Rock-Scoring"></a>Rock-scorings, cause of, <a href="#Page_51">51</a> <i>et seq.</i>;<br /> - in New England, <a href="#Page_69">69</a>;<br /> - on islands of Lake Erie, <a href="#Page_103">103</a>, <a href="#Page_104">104</a>;<br /> - in Pennsylvania, <a href="#Page_119">119</a>;<br /> - in Ohio, <a href="#Page_103">103</a>, <a href="#Page_119">119</a>;<br /> - in Indiana, <a href="#Page_119">119</a>;<br /> - in Illinois, <a href="#Page_119">119</a>;<br /> - in Missouri, <a href="#Page_119">119</a>.<br /> -Roman remains, <a href="#Page_356">356</a>.<br /> -Rome, N. Y., <a href="#Page_335">335</a>.<br /> -Rosa, Mount, <a href="#Page_9">9</a>, <a href="#Page_134">134</a>, <a href="#Page_211">211</a>.<br /> -Ross, Sir J. C, <a href="#Page_18">18</a>, <a href="#Page_19">19</a>, <a href="#Page_311">311</a>.<br /> -Royston, England, <a href="#Page_155">155</a>.<br /> -Runaway Pond, <a href="#Page_207">207</a>.<br /> -Russell, I. C, exploration of Mount St. Elias by, <a href="#Page_30">30</a>, <a href="#Page_212">212</a>;<br /> - cited, <a href="#Page_233">233</a>, <a href="#Page_350">350</a> <i>et seq.</i><br /> -Russia, glacial boundary in, <a href="#Page_181">181</a>, <a href="#Page_189">189</a>;<br /> - glacial drainage of, <a href="#Page_238">238</a>.<br /> -<br /> -Saguenay, fiord of the, <a href="#Page_197">197</a>.<br /> -Salamanca, N. Y., buried channels near, <a href="#Page_206">206</a>.<br /> -Salisbury, cited, <a href="#Page_183">183</a>, <a href="#Page_184">184</a>.<br /> -Salt Lake City, <a href="#Page_123">123</a>.<br /> -Sandusky, Ohio, section of the lake ridges near, <a href="#Page_223">223</a>.<br /> -Sandusky River, <a href="#Page_220">220</a>.<br /> -Sanford, cited, <a href="#Page_267">267</a>.<br /> -Saskatchewan River, <a href="#Page_228">228</a>.<br /> -Saxony, <a href="#Page_181">181</a>.<br /> -Scandinavia, existing glaciers of, <a href="#Page_2">2</a>, <a href="#Page_12">12</a>;<br /> - ancient glaciers of, <a href="#Page_129">129</a>, <a href="#Page_136">136</a>, <a href="#Page_157">157</a>, <a href="#Page_181">181-190</a>;<br /> - re-elevation of, <a href="#Page_331">331</a>.<br /> -Scioto River, <a href="#Page_231">231</a>.<br /> -Scotland. (<a href="#British_Isles">See British Isles.</a>)<br /> -Seattle, section of till in, <a href="#Page_55">55</a>.<br /> -Second Glacial period, <a href="#Page_106">106</a> <i>et seq.</i><br /> -Section, ideal, across river bed in drift region, <a href="#Page_229">229</a>.<br /> -Sedimentation of lakes, <a href="#Page_333">333</a>.<br /> -Seine, terraces of the, <a href="#Page_186">186</a>, <a href="#Page_188">188</a>, <a href="#Page_264">264</a>.<br /> -Seracs, <a href="#Page_4">4</a>, <a href="#Page_5">5</a>.<br /> -Settle, England, <a href="#Page_270">270</a>.<br /> -Severn, the, <a href="#Page_149">149-151</a>, <a href="#Page_285">285</a>.<br /> -Shaler, <a href="#Page_67">67</a>, <a href="#Page_242">242</a>.<br /> -Shap granite, <a href="#Page_154">154</a>, <a href="#Page_157">157</a>, <a href="#Page_180">180</a>.<br /> -Ship Rock, <a href="#Page_71">71</a>.<br /> -Shone, cited, <a href="#Page_180">180</a>.<br /> -Shoshone Falls, <a href="#Page_299">299</a>.<br /> -Shrewsbury, England, <a href="#Page_150">150</a>.<br /> -Shropshire, England, <a href="#Page_149">149</a>, <a href="#Page_173">173</a>.<br /> -Siberia, <a href="#Page_190">190</a>;<br /> - Quaternary animals in, <a href="#Page_280">280</a>, <a href="#Page_282">282</a>, <a href="#Page_283">283</a>, <a href="#Page_290">290</a>;<br /> - climate of, <a href="#Page_302">302</a>, <a href="#Page_316">316</a>.<br /> -Sierra Nevada Mountains, <a href="#Page_21">21</a>, <a href="#Page_294">294</a>, <a href="#Page_301">301</a>, <a href="#Page_320">320</a>, <a href="#Page_322">322</a>, <a href="#Page_349">349</a>, <a href="#Page_352">352</a>.<br /> -Skertchly, quoted, <a href="#Page_159">159</a>.<br /> -Skipton, <a href="#Page_144">144</a>, <a href="#Page_146">146</a>.<br /> -Skull, comparative study of, <a href="#Page_276">276</a>.<br /> -Slickenside, <a href="#Page_53">53</a>.<br /> -Smock on depth of glacial ice, <a href="#Page_90">90</a>.<br /> -Snake River Valley, <a href="#Page_236">236</a> <i>et seq.</i>, <a href="#Page_298">298</a>.<br /> -Snowdon, <a href="#Page_145">145</a>, <a href="#Page_171">171</a>.<br /> -Snowy vole, <a href="#Page_289">289</a>.<br /> -Soleure, <a href="#Page_133">133</a>.<br /> -Solferino, <a href="#Page_135">135</a>.<br /> -Solway Glacier, <a href="#Page_153">153</a>, <a href="#Page_155">155</a>, <a href="#Page_180">180</a>.<br /> -Somme, terraces of the, <a href="#Page_186">186</a>, <a href="#Page_262">262</a> <i>et seq.</i>, <a href="#Page_285">285</a>, <a href="#Page_286">286</a>, <a href="#Page_355">355</a>, <a href="#Page_359">359</a> <i>et seq.</i><br /> -Sonora, Cal., <a href="#Page_294">294</a> <i>et seq.</i><br /> -South America, existing glaciers of, <a href="#Page_17">17</a>;<br /> - ancient glaciers in, <a href="#Page_126">126</a>.<br /> -Southampton, England, <a href="#Page_266">266</a>.<br /> -South Dakota, <a href="#Page_96">96</a>, <a href="#Page_98">98</a>.<br /> -Spain, ancient glaciers of, <a href="#Page_136">136</a>;<br /> - human relics in glacial terraces of, <a href="#Page_264">264</a>;<br /> - Quaternary animals of, <a href="#Page_280">280</a>.<br /> -Speeton, <a href="#Page_140">140</a>, <a href="#Page_155">155</a>, <a href="#Page_156">156</a>.<br /> -Spencer, cited, <a href="#Page_224">224</a>.<br /> -Spencer, N. Y., <a href="#Page_220">220</a>.<br /> -Spitsbergen, <a href="#Page_12">12</a>.<br /> -Spy, man of, <a href="#Page_275">275</a>, <a href="#Page_277">277</a>.<br /> -St. Acheul, <a href="#Page_263">263</a>.<br /> -Stag, <a href="#Page_289">289</a>.<br /> -Stainmoor, England, <a href="#Page_154">154</a>, <a href="#Page_157">157</a>, <a href="#Page_180">180</a>.<br /> -Stalagmite, rate of accumulation of, <a href="#Page_352">352</a> <i>et seq.</i><br /> -Stanislaus River, Cal., <a href="#Page_294">294</a>.<br /> -St. Anthony, Falls of, <a href="#Page_340">340</a> <i>et seq.</i>, <a href="#Page_364">364</a>.<br /> -Steamburg, N. Y., buried channel at, <a href="#Page_206">206</a>.<br /> -St. Elias, <a href="#Page_30">30</a> <i>et seq.</i>, <a href="#Page_212">212</a>.<br /> -St. Lawrence River, glacial drainage of, <a href="#Page_335">335</a>, <a href="#Page_339">339</a>. -<span class="pagenum"><a name="Page_384" id="Page_384">« 384 »</a></span><br /> -St. Louis, Mo., <a href="#Page_119">119</a>, <a href="#Page_364">364</a>.<br /> -St. Paul, Minn., <a href="#Page_228">228</a>.<br /> -Stone on kames in Maine, <a href="#Page_80">80</a>.<br /> -Straits of Dover, <a href="#Page_360">360</a>.<br /> -Straits of Gibraltar, <a href="#Page_292">292</a>.<br /> -Striæ, direction of, in New Hampshire, <a href="#Page_69">69</a>;<br /> - in Lake Erie, <a href="#Page_104">104</a>;<br /> - presence of, in Pennsylvania, <a href="#Page_85">85</a>, <a href="#Page_119">119</a>;<br /> - in Ohio, Indiana, Illinois, and Missouri, <a href="#Page_119">119</a>;<br /> - in Stuttgart, <a href="#Page_279">279</a>.<br /> -Subglacial streams, <a href="#Page_23">23</a>, <a href="#Page_29">29</a>, <a href="#Page_120">120</a>.<br /> -Submerged channels on the coasts of America, <a href="#Page_194">194-198</a>.<br /> -Submergence theory, <a href="#Page_60">60-63</a>, <a href="#Page_70">70</a>.<br /> -Subsidence of the Isthmus of Panama, <a href="#Page_113">113</a>, <a href="#Page_318">318</a>;<br /> - in Mississippi Valley, <a href="#Page_93">93</a>, <a href="#Page_113">113</a>, <a href="#Page_120">120</a>, <a href="#Page_121">121</a>;<br /> - on east coast of North America, <a href="#Page_255">255</a> <i>et seq.</i>;<br /> - about the Great Lakes, <a href="#Page_224">224</a>, <a href="#Page_339">339</a>;<br /> - in Great Britain, <a href="#Page_167">167-181</a>.<br /> -Susquehanna River, glacial drainage of, <a href="#Page_93">93</a>, <a href="#Page_232">232</a>, <a href="#Page_257">257</a>.<br /> -Svartisen Glacier, <a href="#Page_13">13</a>.<br /> -Svenonius, Dr., <a href="#Page_12">12</a>.<br /> -Sweden, <a href="#Page_81">81</a>.<br /> -Switzerland, existing glaciers of, <a href="#Page_9">9-11</a>;<br /> - ancient glaciers of, <a href="#Page_131">131-136</a>;<br /> - lake-dwellings in, <a href="#Page_281">281</a>.<br /> -<br /> -Table Mountain, Cal., <a href="#Page_294">294</a> <i>et seq.</i>, <a href="#Page_300">300</a>.<br /> -Table of changes during the Glacial epochs, <a href="#Page_324">324</a>, <a href="#Page_325">325</a>.<br /> -Tagus, valley of the, <a href="#Page_367">367</a>, <a href="#Page_371">371</a> <i>et seq.</i><br /> -Tait, cited, <a href="#Page_362">362</a>.<br /> -Tardy, cited, <a href="#Page_370">370</a>.<br /> -Tasman Glacier, <a href="#Page_16">16</a>.<br /> -Teesdale, England, <a href="#Page_155">155</a>, <a href="#Page_157">157</a>.<br /> -Terminal moraines, formation of, <a href="#Page_6">6</a>;<br /> - in Pennsylvania, <a href="#Page_61">61</a>, <a href="#Page_62">62</a>, <a href="#Page_85">85</a> <i>et seq.</i>;<br /> - on the southern coast of New England, <a href="#Page_66">66</a> <i>et seq.</i>;<br /> - in Ohio, <a href="#Page_106">106</a>;<br /> - in Puget Sound, <a href="#Page_122">122</a>;<br /> - in Tyghee Pass, <a href="#Page_122">122</a>;<br /> - in Italy, <a href="#Page_135">135</a>.<br /> -Terminal moraines of the second Glacial epoch, <a href="#Page_93">93</a>, <a href="#Page_100">100</a>, <a href="#Page_101">101</a>, <a href="#Page_106">106</a>.<br /> -Terraces. (<a href="#Glacial_Terraces">See Glacial Terraces.</a>)<br /> -Tertiary animals, <a href="#Page_286">286</a>.<br /> -Tertiary man, <a href="#Page_365">365-374</a>.<br /> -Tertiary period, climate of, <a href="#Page_113">113</a>, <a href="#Page_117">117</a>, <a href="#Page_182">182</a>, <a href="#Page_305">305</a>, <a href="#Page_307">307</a>.<br /> -Teton Mountains, <a href="#Page_123">123</a>.<br /> -Texas, Pleistocene animals of, <a href="#Page_288">288</a>.<br /> -Thames, England, <a href="#Page_138">138</a>, <a href="#Page_264">264</a>, <a href="#Page_285">285</a>.<br /> -Thenay, France, supposed Tertiary man in, <a href="#Page_367">367</a>, <a href="#Page_371">371</a>;<br /> - view of flint-flakes collected at, <a href="#Page_368">368</a>.<br /> -Thompson, <a href="#Page_50">50</a>.<br /> -Thomson, cited, <a href="#Page_362">362</a>.<br /> -<a id="Till" name="Till"></a>Till, description of, <a href="#Page_53">53</a>;<br /> - composition of, in Massachusetts, <a href="#Page_81">81</a> <i>et seq.</i>;<br /> - section of, in Ohio, <a href="#Page_108">108</a>;<br /> - depth of, in Germany, Scandinavia, and Russia, <a href="#Page_182">182</a>.<br /> -Tinière River, <a href="#Page_354">354</a>.<br /> -Titusville, Pa., <a href="#Page_232">232</a>.<br /> -Todd, on forest beds and old soils,110 <i>et seq.</i>;<br /> - cited, <a href="#Page_228">228</a>.<br /> -Torquay, England, <a href="#Page_267">267</a>.<br /> -Trade-winds of the Atlantic, <a href="#Page_314">314</a>, <a href="#Page_318">318</a>.<br /> -Tremeirchon, Wales, <a href="#Page_271">271</a>.<br /> -Trenton, N. J., <a href="#Page_87">87</a>, <a href="#Page_232">232</a>, <a href="#Page_242">242</a> <i>et seq.</i>, <a href="#Page_254">254</a>, <a href="#Page_257">257</a>;<br /> - view of implement found at, <a href="#Page_247">247</a>.<br /> -Trenton gravel, section of the, <a href="#Page_246">246</a>.<br /> -Trent, valley of the, <a href="#Page_163">163</a>, <a href="#Page_164">164</a>.<br /> -Trimmer, quoted, <a href="#Page_148">148</a>.<br /> -Trimingham, England, <a href="#Page_162">162</a>.<br /> -Trogen, Switzerland, <a href="#Page_60">60</a>.<br /> -Trons, Switzerland, <a href="#Page_60">60</a>.<br /> -Tuolumne County, Cal., <a href="#Page_294">294</a>, <a href="#Page_299">299</a>.<br /> -Turin, <a href="#Page_135">135</a>.<br /> -Tuscarawas Valley, <a href="#Page_220">220</a>, <a href="#Page_221">221</a>, <a href="#Page_232">232</a>, <a href="#Page_251">251</a>;<br /> - buried channel in, <a href="#Page_205">205</a>.<br /> -Tylor, cited, <a href="#Page_359">359</a> <i>et seq.</i><br /> -Tyndall, <a href="#Page_44">44-46</a>, <a href="#Page_49">49</a>.<br /> -Tynemouth, England, <a href="#Page_155">155</a>, <a href="#Page_157">157</a>.<br /> -Tyrol, <a href="#Page_134">134</a>, <a href="#Page_135">135</a>, <a href="#Page_211">211</a>.<br /> -Tyrrell, cited, <a href="#Page_109">109</a>.<br /> -<br /> -Ulm, <a href="#Page_134">134</a>.<br /> -Upham, on drumlins, <a href="#Page_73">73</a>;<br /> - on two ice-movements, <a href="#Page_97">97</a>;<br /> - cited, <a href="#Page_222">222</a>, <a href="#Page_253">253</a> <i>et seq.</i>, <a href="#Page_301">301</a>, <a href="#Page_318">318</a>, <a href="#Page_320">320</a> <i>et seq.</i>, <a href="#Page_330">330</a>, <a href="#Page_348">348</a>;<br /> - on the Columbia gravel, <a href="#Page_261">261</a>;<br /> - on date of the Glacial period, <a href="#Page_344">344</a>.<br /> -Ural Mountains, <a href="#Page_15">15</a>, <a href="#Page_280">280</a>.<br /> -Utah, <a href="#Page_123">123</a>;<br /> - lakes of, <a href="#Page_233">233</a>.<br /> -Utica, N. Y., <a href="#Page_220">220</a>.<br /> -Utrecht, moraine near, <a href="#Page_181">181</a>.<br /> -<br /> -Valais, the, <a href="#Page_133">133</a>.<br /> -Vegetable remains in glacial deposits, <a href="#Page_117">117</a>, <a href="#Page_125">125</a>;<br /> - in Ohio, <a href="#Page_107">107</a>, <a href="#Page_117">117</a>;<br /> - in Indiana, <a href="#Page_107">107</a>;<br /> - in Minnesota, <a href="#Page_107">107</a>, <a href="#Page_109">109</a>;<br /> - in Iowa, <a href="#Page_108">108</a>;<br /> - in British America, <a href="#Page_109">109</a>.<br /> -Veins in glacial ice, <a href="#Page_3">3</a>.<br /> -Vermont, Runaway Pond in, <a href="#Page_207">207</a>.<br /> -Vernagt Glacier, <a href="#Page_211">211</a>.<br /> -Vessel Rock, view of, <a href="#Page_56">56</a>.<br /> -Vezère, valley of, <a href="#Page_281">281</a>.<br /> -Victoria Cave, England, <a href="#Page_270">270</a>, <a href="#Page_280">280</a>.<br /> -Virginia City, <a href="#Page_349">349</a><br /> -Vivian, cited, <a href="#Page_267">267</a>.<br /> -Volga, the, <a href="#Page_185">185</a>.<br /> -Vosges Mountains, <a href="#Page_136">136</a>.<br /> -<br /> -Wabash River, <a href="#Page_220">220</a>, <a href="#Page_231">231</a>, <a href="#Page_232">232</a>. -<span class="pagenum"><a name="Page_385" id="Page_385">« 385 »</a></span><br /> -Wahsatch Mountains, <a href="#Page_237">237</a>.<br /> -Wales, ancient glaciers of, <a href="#Page_143">143</a>, <a href="#Page_150">150</a> <i>et seq.</i>;<br /> - caverns of, <a href="#Page_271">271</a>.<br /> -Wallace, cited, <a href="#Page_331">331</a>, <a href="#Page_343">343</a>, <a href="#Page_362">362</a>.<br /> -Walrus, <a href="#Page_262">262</a>, <a href="#Page_285">285</a>.<br /> -Warren, Pa., buried channel near, <a href="#Page_206">206</a>.<br /> -Warren River, <a href="#Page_226">226</a>.<br /> -Washington, <a href="#Page_1">1</a>, <a href="#Page_21">21</a>, <a href="#Page_122">122</a>.<br /> -Washington, D. C., gravel deposit of, <a href="#Page_254">254</a>.<br /> -Water, transporting power of running, <a href="#Page_5">5</a>, <a href="#Page_51">51-53</a>.<br /> -Waveney, England, valley of the, <a href="#Page_266">266</a>.<br /> -Wealden formation, <a href="#Page_361">361</a>.<br /> -Weasel, <a href="#Page_290">290</a>.<br /> -Wells, England, <a href="#Page_270">270</a>.<br /> -Western Reserve Historical Society, <a href="#Page_104">104</a>.<br /> -Weston, W. Va., <a href="#Page_216">216</a>.<br /> -West Virginia, <a href="#Page_214">214</a> <i>et seq.</i>;<br /> - glacial terrace in, <a href="#Page_216">216</a>.<br /> -Wey, valley of the, <a href="#Page_265">265</a>.<br /> -Whitby, England, <a href="#Page_155">155</a>.<br /> -White, cited, <a href="#Page_215">215</a> <i>et seq.</i><br /> -White River, Ind., <a href="#Page_232">232</a>, <a href="#Page_251">251</a>.<br /> -White Sea, <a href="#Page_181">181</a>.<br /> -Whitney, <a href="#Page_14">14</a>, <a href="#Page_21">21</a>, <a href="#Page_295">295</a>, <a href="#Page_349">349</a>, <a href="#Page_373">373</a>.<br /> -Whittlesey, <a href="#Page_100">100</a>.<br /> -Wild-boar, <a href="#Page_290">290</a>.<br /> -Wild-cat, <a href="#Page_290">290</a>.<br /> -Winchell, Alexander, cited, <a href="#Page_321">321</a>, <a href="#Page_330">330</a>.<br /> -Winchell, N. H., cited, <a href="#Page_107">107</a>, <a href="#Page_210">210</a>, <a href="#Page_252">252</a>;<br /> - on the Falls of St. Anthony, <a href="#Page_341">341</a> <i>et seq.</i><br /> -Wisconsin, <a href="#Page_98">98</a>, <a href="#Page_99">99</a>, <a href="#Page_100">100</a>, <a href="#Page_101">101</a>.<br /> -Woeikoff, cited, <a href="#Page_316">316</a>.<br /> -Wolf, <a href="#Page_270">270</a>, <a href="#Page_290">290</a>.<br /> -Wolverine, <a href="#Page_289">289</a>.<br /> -Wood, cited, <a href="#Page_179">179</a>.<br /> -Woodward, quoted, <a href="#Page_160">160</a>;<br /> - on age of Niagara, <a href="#Page_337">337</a> <i>et seq.</i><br /> -Wookey Hole, England, <a href="#Page_270">270</a>.<br /> -Wrangell, cited, <a href="#Page_357">357</a>.<br /> -Wright, <a href="#Page_373">373</a>.<br /> -<br /> -Yankton, <a href="#Page_120">120</a>.<br /> -Yellowstone Park, <a href="#Page_122">122</a>.<br /> -Yorkshire, <a href="#Page_140">140</a>, <a href="#Page_154">154</a>, <a href="#Page_155">155</a>, <a href="#Page_157">157</a>, <a href="#Page_176">176</a>, <a href="#Page_270">270</a>, <a href="#Page_283">283</a>, <a href="#Page_286">286</a>.<br /> -Yosemite Park, <a href="#Page_21">21</a>, <a href="#Page_350">350</a>.<br /> -Young, Rev. Mr., <a href="#Page_24">24</a>.<br /> -Young, Professor, cited, <a href="#Page_362">362</a>.<br /> -Younglove, <a href="#Page_104">104</a>.<br /> -<br /> -Zermatt Glacier, view of, <a href="#Page_2">2</a>.<br /> -Zuyder Zee, <a href="#Page_181">181</a>.<br /> -</p> - - -<p class="center">THE END.</p> - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_ia" id="Page_ia">« ia »</a></span></p> - - -<p class="caption2ad">D. APPLETON & CO.’S PUBLICATIONS.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE ICE AGE IN NORTH AMERICA, and its -Bearings upon the Antiquity of Man.</i> By G. Frederick -Wright, D. D., LL. D., F. G. S. A., Professor in Oberlin -Theological Seminary; Assistant on the United States Geological -Survey. With an appendix on “The Probable Cause -of Glaciation,” by Warren Upham, F. G. S. A., Assistant on -the Geological Surveys of New Hampshire, Minnesota, and -the United States. New and enlarged edition. 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Growing in -fullness and accuracy with the growth of experience and observation in every region of -the world, the work has incorporated with itself each established discovery, and has -been modified by every hypothesis of value which has been brought to bear upon, or -been evolved from, the most recent body of facts.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE AUTOBIOGRAPHY OF THE EARTH: -A Popular Account of Geological history.</i> By Rev. H. N. -Hutchinson, B. A., F. G. S. With 27 Illustrations. Crown -8vo. Cloth, $1.50.</p> - -<p class="smaller">“A scientific work, divested of technicalities, and put into a bright, narrative form -which can not but attract even the most general reader.”—<i>Boston Transcript</i>.</p> - -<p class="smaller">“It is hardly conceivable that the rich results of the science of geology can be so -treated as to prove uninteresting to thinking people, be they young or old. When, -therefore, we say that Mr. Hutchinson’s book is extremely interesting, no more might -be implied than that the author has skillfully used the vast materials at his hand. But -Mr. Hutchinson has successfully carried out a difficult design on an admirable plan, -and has adhered to that plan throughout. His sketch of historical geology has a -genuine continuity.”—<i>Saturday Review</i>.</p> - - -<div class="dropcap">A</div> -<p class="p0"><i><span class="hidden">A </span>REPRINT OF ANNUAL REPORTS AND -OTHER PAPERS OF THE GEOLOGY OF THE VIRGINIAS.</i> -By the late William Barton Rogers, LL. D., -etc., Director of the Geological Survey of Virginia from 1835 -to 1841. With numerous Maps, Colored Charts, etc. 12mo. -Cloth, $5.00.</p> - - -<p><i>NATURAL RESOURCES OF THE UNITED -STATES.</i> By Jacob Harris Patton, M. A., Ph. D. 8vo. -523 pages. 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It is sure to make a reputation aboard -as well as at home for its distinguished author, as one of the most active and intelligent -of the living students of natural science and the special department of glacial action.”—<i>Philadelphia -Bulletin</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE GREAT ICE AGE, and Us Relation to the -Antiquity of Man.</i> By James Geikie, F. R. S. E., of H. M. -Geological Survey of Scotland. With Maps and Illustrations. -12mo. Cloth, $2.50.</p> - -<p class="smaller">A systematic account of the Glacial epoch in England and Scotland, with special -reference to its changes of climate.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE CAUSE OF AN ICE AGE.</i> By Sir Robert -J. Ball, LL. D., F. R. S., Royal Astronomer of Ireland, author of -“Starland.” The first volume in the Modern Science Series, -edited by Sir John Lubbock. 12mo. 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Mr. Macfarlane has produced a very convenient -and serviceable hand-book, available alike to the practical geologist, to the student of -that science, and to the intelligent traveler who would like to know the country through -which he is passing.”—<i>Boston Evening Transcript</i>.</p> - -<hr class="r50" /> - -<p class="caption3">New York: D. APPLETON & CO., 72 Fifth Avenue.</p> - -<p><span class="pagenum"><a name="Page_iva" id="Page_iva">« iva »</a></span></p> - - -<p class="caption2ad">D. APPLETON & CO.’S PUBLICATIONS.</p> - - -<p class="caption2">RICHARD A. PROCTOR’S WORKS.</p> - -<div class="dropcap">O</div> -<p class="p0"><i><span class="hidden">O</span>THER WORLDS THAN OURS: The Plurality -of Worlds, Studied under the Light of Recent Scientific Researches.</i> -By Richard Anthony Proctor. With Illustrations, -some colored. 12mo. Cloth, $1.75.</p> - -<p class="smaller">Contents.—Introduction.—What the Earth teaches us.—What we learn from -the Sun.—The Inferior Planets.—Mars, the Miniature of our Earth.—Jupiter, the -Giant of the Solar System.—Saturn, the Ringed World.—Uranus and Neptune, the -Arctic Planets.—The Moon and other Satellites.—Meteors and Comets: their Office -in the Solar System.—Other Suns than Ours.—Of Minor Stars, and of the Distribution -of Stars in Space.—The Nebulæ: are they External Galaxies?—Supervision -and Control.</p> - - -<div class="dropcap">O</div> -<p class="p0"><i><span class="hidden">O</span>UR PLACE AMONG INFINITIES.</i> A Series -of Essays contrasting our Little Abode in Space and Time with -the Infinities around us. To which are added Essays on the -Jewish Sabbath and Astrology. 12mo. Cloth, $1.75.</p> - -<p class="smaller">Contents.—Past and Future of the Earth.—Seeming Wastes in Nature.—New -Theory of Life in other Worlds.—A Missing Comet.—The Lost Comet and its Meteor -Train.—Jupiter.—Saturn and its System.—A Giant Sun.—The Star Depths.—Star -Gauging.—Saturn and the Sabbath of the Jews.—Thoughts on Astrology.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE EXPANSE OF HEAVEN.</i> A Series of -Essays on the Wonders of the Firmament. 121110. Cloth -$2.00.</p> - -<p class="smaller">Contents.—A Dream that was not all a Dream.—The Sun.—The Queen of -Night.—The Evening Star.—The Ruddy Planet.—Life in the Ruddy Planet.—The -Prince of Planets.—Jupiter’s Family of Moons.—The Ring-Girdled Planet.—Newton -and the Law of the Universe.—The Discovery of Two Giant Planets.—The -Lost Comet.—Visitants from the Star Depths.—Whence come the Comets?—The -Comet Families of the Giant Planets.—The Earth’s Journey through Showers.—How -the Planets Grew.—Our Daily Light.—The Flight of Light.—A Cluster of -Suns.—Worlds ruled by Colored Suns.—The King of Suns.—Four Orders of Suns. -—The Depths of Space.—Charting the Star Depths.—The Star Depths Astir with -Life.—The Drifting Stars.—The Milky Way.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE MOON: Her Motions, Aspect, Scenery, and Physical -Conditions.</i> With Three Lunar Photographs, Map, and -many Plates, Charts, etc. 12mo. 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Cloth, $1.50.</p> - -<p class="smaller">This is a unique book, quite alone in the field that it occupies. The call for a -fourth edition within two years after its first publication attests its popularity. As one -of its reviewers has said, “It is the most human book on the subject of the stars.” -It would have supplied Thomas Carlyle’s want when he wrote, “Why did not somebody -teach me the stars and make me at home in the starry heavens?” Interest in -the geography of the heavens is increasing every year, as the discoveries of astronomers -with the giant telescopes of our day push back the limits of the known universe, -and this book is to those who read of such discoveries like an atlas to the student of -history.</p> - -<p>Some of the compliments that the book has received are these:</p> - -<p class="smaller">“A most interesting and even fascinating book.”—<i>Christian Union.</i></p> - -<p class="smaller">“The glimpses he allows to be seen of far-stretching vistas opening out on every -side of his modest course of observation help to fix the attention of the negligent, and -lighten the toil of the painstaking student.... Mr. Serviss writes with freshness and -vivacity.”—<i>London Saturday Review.</i></p> - -<p class="smaller">“We are glad to welcome this, the second edition, of a popular introduction to the -study of the heavens.... There could hardly be a more pleasant road to astronomical -knowledge than it affords.... A child may understand the text, which reads -more like a collection of anecdotes than anything else, but this does not mar its scientific -value.”—<i>Nature.</i></p> - -<p class="smaller">“Mr. Garrett P. Serviss’s book, ‘Astronomy with an Opera-Glass,’ offers us an -admirable hand-book and guide in the cultivation of this noble æsthetic discipline (the -study of the stars).”—<i>New York Home Journal.</i></p> - -<p class="smaller">“The book should belong to every family library.”—<i>Boston Home Journal.</i></p> - -<p class="smaller">“This book ought to make star-gazing popular.”—<i>New York Herald.</i></p> - -<p class="smaller">“The author attributes much of the indifference of otherwise well-informed persons -regarding the wonders of the starry firmament to the fact that telescopes are available -to few, and that most people have no idea of the possibilities of the more familiar -instrument of almost daily use whose powers he sets forth.”—<i>New Orleans Times-Democrat.</i></p> - -<p class="smaller">“By its aid thousands of people who have resigned themselves to the ignorance in -which they were left at school, by our wretched system of teaching by the book only, -will thank Mr. Serviss for the suggestions he has so well carried out.”—<i>New York -Times.</i></p> - -<p class="smaller">“For amateur use this book is easily the best treatise on astronomy yet published.”—<i>Chicago Herald.</i></p> - -<p class="smaller">“‘Astronomy with an Opera-Glass’ fills a long-felt want.”—<i>Albany Journal.</i></p> - -<p class="smaller">“No intelligent reader of this book but will feel that if the author fails to set his -public star-gazing the fault is not his, for his style is as winning, as graphic, and as -clear as the delightful type in which it is printed.”—<i>Providence Journal.</i></p> - -<p class="smaller">“Mr. Serviss neither talks over the heads of his readers nor ignores the sublime -complexity and range of his themes, but unites simplicity with scholarship, scientific -precision with life-long enthusiasm, and a genuine eloquence with rare touches of humor. -Considered as a product of the publishing industry, the book is elegance itself.”—<i>The -Chautauquan.</i></p> - -<hr class="r50" /> - -<p class="caption3">New York: D. APPLETON & CO., 72 Fifth Avenue.</p> - -<p><span class="pagenum"><a name="Page_via" id="Page_via">« via »</a></span></p> - - -<p class="caption2ad">D. APPLETON & CO.’S PUBLICATIONS.</p> - - -<div class="dropcap">O</div> -<p class="p0"><i><span class="hidden">O</span>UTINGS AT ODD TIMES.</i> By Charles C. -Abbott, author of “Days out of Doors” and “A Naturalist’s -Rambles about Home.” 16mo. Cloth, gilt top, $1.25.</p> - -<p class="smaller">“A charming little volume, literally alone with Nature, for it discusses seasons and -the fields, birds, etc., with the loving freedom of a naturalist born. Every page reads -like a sylvan poem; and for the lovers of the beautiful in quiet outdoor and out-of-town -life, this beautifully bound and attractively printed little volume will prove a -companion and friend.”—<i>Rochester Union and Advertiser.</i></p> - -<div class="dropcap">A</div> -<p class="p0"><i><span class="hidden">A </span>NATURALIST’S RAMBLES ABOUT HOME.</i> -By Charles C. Abbott. 12mo. Cloth, $1.50.</p> - -<p class="smaller">“The home about which Dr. Abbott rambles is clearly the haunt of fowl and fish, -of animal and insect life; and it is of the habits and nature of these that he discourses -pleasantly in this book. Summer and winter, morning, and evening, he has been in -the open air all the time on the alert for some new revelation of instinct, or feeling, -or character on the part of his neighbor creatures. Most that he sees and hears he -reports agreeably to us, as it was no doubt delightful to himself. Books like this, -which are free from all the technicalities of science, but yet lack little that has scientific -value, are well suited to the reading of the young. Their atmosphere is a healthy -one for boys in particular to breathe.”—<i>Boston Transcript.</i></p> - - -<div class="dropcap">D</div> -<p class="p0"><i><span class="hidden">D</span>AYS OUT OF DOORS.</i> By Charles C. Abbott. -12mo. Cloth, $1.50.</p> - -<p class="smaller">“‘Days out of Doors’ is a series of sketches of animal life by Charles C Abbott, -a naturalist whose graceful writings have entertained and instructed the public before -now. The essays and narratives in this book are grouped in twelve chapters, named -after the months of the year. Under ‘January’ the author talks of squirrels, muskrats, -water-snakes, and the predatory animals that withstand the rigor of winter; -under ‘February’ of frogs and herons, crows and blackbirds; under ‘March’ of gulls -and fishes and foxy sparrows; and so on appropriately, instructively, and divertingly -through the whole twelve.”—<i>New York Sun.</i></p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE PLAYTIME NATURALIST.</i> By Dr. J. E. -Taylor, F. L. S., editor of “Science Gossip.” With 366 Illustrations. -12mo. 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Cloth, $1.75.</p> - -<p class="smaller">“Much has been written on the structure of flowers, and it might seem almost -superfluous to attempt to say anything more on the subject, but it is only within the -last few years that a new literature has sprung up, in which the authors have described -their observations and given their interpretations of the uses of floral mechanisms, more -especially in connection with the processes of fertilization.”—<i>From Introduction.</i></p> - -<hr class="r50" /> - -<p class="caption3">New York: D. APPLETON & CO., 72 Fifth Avenue.</p> - -<p><span class="pagenum"><a name="Page_viia" id="Page_viia">« viia »</a></span></p> - - -<p class="caption2ad">D. APPLETON & CO.’S PUBLICATIONS.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE GARDEN’S STORY;</i> or, Pleasures and -Trials of an Amateur Gardener. By George H. Ellwanger. -With Head and Tail Pieces by Rhead. 12mo. Cloth, extra, -$1.50.</p> - -<p class="smaller">“Mr. Ellwanger’s instinct rarely errs in matters of taste. He writes out of the -fullness of experimental knowledge, but his knowledge differs from that of many a -trained cultivator in that his skill in garden practice is guided by a refined æsthetic -sensibility, and his appreciation of what is beautiful in nature is healthy, hearty, and -catholic. His record of the garden year, as we have said, begins with the earliest -violet, and it follows the season through until the witch-hazel is blossoming on the -border of the wintry woods.... This little book can not fail to give pleasure 10 all -who take a genuine interest in rural life.”—<i>New York Tribune</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE ORIGIN OF CULTIVATED PLANTS.</i> -By Alphonse de Candolle. 12mo. 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In all respects the book is excellent. -Its arrangement is simple and intelligible, its style bright and alluring.... -To all who seek an introduction to one of the most attractive branches of folk-lore, -this delightful volume may be warmly commended.”—<i>Notes and Queries</i>.</p> - - -<div class="dropcap">F</div> -<p class="p0"><i><span class="hidden">F</span>LOWERS AND THEIR PEDIGREES.</i> By -Grant Allen, author of “Vignettes of Nature,” etc. Illustrated. -12mo. Cloth, $1.50.</p> - -<p class="smaller">“No writer treats scientific subjects with so much ease and charm of style as Mr. -Grant Allen. The study is a delightful one, and the hook is fascinating to any one -who has either love for flowers or curiosity about them.”—<i>Hartford Courant</i>.</p> - -<p class="smaller">“Any one with even a smattering of botanical knowledge, and with either a heart -or mind, must be charmed with this collection of essays.”—<i>Chicago Evening Journal</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE GEOLOGICAL HISTORY OF PLANTS.</i> -By Sir J. William Dawson, F. R. S. Illustrated. 12mo. -Cloth, $1.75.</p> - -<p class="smaller">“The object of this work is to give, in a connected form, a summary of the development -of the vegetable kingdom in geological time. To the geologist and botanist the -subject is one of importance with reference to their special pursuits, and one on which -it has not been easy to find any convenient manual of information. It is hoped that its -treatment in the present volume will also be found sufficiently simple and popular to be -attractive to the general reader.”—<i>From the Preface</i>.</p> - -<hr class="r50" /> - -<p class="caption3">New York: D. APPLETON & CO., 72 Fifth Avenue.</p> - -<p><span class="pagenum"><a name="Page_viiia" id="Page_viiia">« viiia »</a></span></p> - - -<p class="caption2ad">D. APPLETON & CO.’S PUBLICATIONS.</p> - - -<div class="dropcap">I</div> -<p class="p0"><i><span class="hidden">I</span>DLE DAYS IN PATAGONIA.</i> By W. H. Hudson, -C. M. Z. S., author of “The Naturalist in La Plata,” etc. -With 27 Illustrations. 8vo. Cloth, $4.00.</p> - -<p class="smaller">“Of all modern books of travel it is certainly one of the most original, and many, -we are sure, will also find it one of the most interesting and suggestive.”—<i>New York -Tribune.</i></p> - -<p class="smaller">“Mr. Hudson’s remarks on color and expression of eyes in man and animals are reserved -for a second chapter, ‘Concerning Eyes.’ He is eloquent upon the pleasures -afforded by ‘Bird Music in South America,’ and relates some romantic tales of white -men in captivity to savages. But it makes very little difference what is the topic when -Mr. Hudson writes. He calls up bright images of things unseen, and is a thoroughly -agreeable companion.”—<i>Philadelphia Ledger.</i></p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE NATURALIST IN LA PLATA.</i> By W. H. -Hudson, C. M. Z. S., author of “Idle Days in Patagonia,” and -joint author of “Argentine Ornithology.” With 27 Illustrations. -8vo. Cloth, $4.00.</p> - -<p class="smaller">“Mr. Hudson is not only a clever naturalist, but he possesses the rare gift of interesting -his readers in whatever attracts him, and of being dissatisfied with mere observation -unless it enables him to philosophize as well. With his lucid accounts of -bird, beast, and insect, no one will fail to be delighted.”—<i>London Academy.</i></p> - -<p class="smaller">“A notably clear and interesting account of scientific observation and research. -Mr. Hudson has a keen eye for the phenomena with which the naturalist is concerned, -and a lucid and delightful way of writing about them, so that any reader may be -charmed by the narrative and the reflections here set forth. It is easy to follow him, -and we get our information agreeably as he conducts us over the desert pampas, and -makes us acquainted with the results of his studies of animals, insects, and birds.”—<i>New -York Sun.</i></p> - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE NATURALIST ON THE RIVER -AMAZONS.</i> By Henry Walter Bates, F. R. S., late Assistant -Secretary of the Royal Geographical Society. With a -Memoir of the Author, by Edward Clodd. With Map and -numerous Illustrations. 8vo. Cloth, $5.00.</p> - -<p class="smaller">“This famous work is a natural history classic.”—<i>London Literary World.</i></p> - -<p class="smaller">“More than thirty years have passed since the first appearance of ‘The Naturalist -on the River Amazons,’ which Darwin unhesitatingly pronounced the best book on -natural history which ever appeared in England. The work still retains its prime interest, -and in rereading it one can not but be impressed by the way in which the prophetic -theories, disputed and ridiculed at the time, have since been accepted. Such is -the common experience of those who keep a few paces in advance of their generation. -Bates was a ‘born’ naturalist.”—<i>Philadelphia Ledger.</i></p> - -<p class="smaller">“No man was better prepared or gave himself up more thoroughly to the task of -studying an almost unknown fauna, or showed a zeal more indefatigable in prosecuting -his researches, than Bates. As a collector alone his reputation would be second to -none, but there is a great deal more than sheer industry to be cited. The naturalist of -the Amazons is, par excellence, possessed of a happy literary style. He is always clear -and distinct. He tells of the wonders of tropical growth so that you can understand -them all.”—<i>New York Times.</i></p> - -<hr class="r50" /> - -<p class="caption3">New York: D. APPLETON & CO., 72 Fifth Avenue.</p> - -<p><span class="pagenum"><a name="Page_ixa" id="Page_ixa">« ixa »</a></span></p> - - -<p class="caption2ad">D. APPLETON & CO.’S PUBLICATIONS.</p> - - -<p class="caption3">WORKS BY ARABELLA B. BUCKLEY (MRS. FISHER).</p> - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE FAIRY-LAND OF SCIENCE.</i> With 74 -Illustrations. 12mo. Cloth, gilt, $1.50.</p> - -<p class="smaller">“Deserves to take a permanent place in the literature of youth.”—<i>London Times.</i></p> - -<p class="smaller">“So interesting that, having once opened the book, we do not know how to leave -off reading.”—<i>Saturday Review</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HROUGH MAGIC GLASSES,</i> and other Lectures. -A Sequel to “The Fairy-Land of Science.” Illustrated. -12mo. Cloth, $1.50.</p> - -<p class="center"><i>CONTENTS.</i></p> - -<table summary="list"> -<tr> - <td class="tdl"><i>The Magician’s Chamber by Moonlight.</i></td> - <td class="tdl1"><i>An Hour with the Sun.</i></td> -</tr> -<tr> - <td class="tdl"><i>Magic Glasses and How to Use Them.</i></td> - <td class="tdl1"><i>An Evening with the Stars.</i></td> -</tr> -<tr> - <td class="tdl"><i>Fairy Rings and How They are Made.</i></td> - <td class="tdl1"><i>Little Beings from a Miniature Ocean.</i></td> -</tr> -<tr> - <td class="tdl"><i>The Life-History of Lichens and Mosses.</i></td> - <td class="tdl1"><i>The Dartmoor Ponies.</i></td> -</tr> -<tr> - <td class="tdl"><i>The History of a Lava-Stream.</i></td> - <td class="tdl1"><i>The Magician’s Dream of Ancient Days.</i></td> -</tr> -</table> - - -<div class="dropcap">L</div> -<p class="p0"><i><span class="hidden">L</span>IFE AND HER CHILDREN:</i> Glimpses of Animal -Life from the Amœba to the Insects. With over 100 Illustrations. -121110. Cloth, gilt, $1.50.</p> - -<p class="smaller">“The work forms a charming introduction to the study of zoology—the science of -living things—which, we trust, will find its way into many hands.”—<i>Nature</i>.</p> - - -<div class="dropcap">W</div> -<p class="p0"><i><span class="hidden">W</span>INNERS IN LIFE’S RACE;</i> or, The Great -Backboned Family. With numerous Illustrations. 12mo. -Cloth, gilt, $1.50.</p> - -<p class="smaller">“We can conceive of no better gift-book than this volume. Miss Buckley has spared -no pains to incorporate in her book the latest results of scientific research. The illustrations -in the book deserve the highest praise—they are numerous, accurate, and -striking.”—<i>Spectator</i>.</p> - - -<div class="dropcap">S</div> -<p class="p0"><i><span class="hidden">S</span>HORT HISTORY OF NATURAL SCIENCE;</i> -and of the Progress of Discovery from the Time of -the Greeks to the Present Time. New edition, revised and rearranged. -With 77 Illustrations. 12mo. Cloth, $2.00.</p> - -<p class="smaller">“The work, though mainly intended for children and young persons, may be most -advantageously read by many persons of riper age, and may serve to implant in their -minds a fuller and clearer conception of ‘the promises, the achievements, and the claims -of science.’”—<i>Journal of Science</i>.</p> - - -<div class="dropcap">M</div> -<p class="p0"><i><span class="hidden">M</span>ORAL TEACHINGS OF SCIENCE.</i> 12mo. -Cloth, 75 cents.</p> - -<p class="smaller">“A little book that proves, with excellent clearness and force, how many and striking -are the moral lessons suggested by the study of the life history of the plant or bird, -beast or insect.”—<i>London Saturday Review</i>.</p> - - -<p class="caption3">New York: D. APPLETON & CO., 72 Fifth Avenue.</p> - -<p><span class="pagenum"><a name="Page_xa" id="Page_xa">« x »</a></span></p> - - -<p class="caption2ad">D. APPLETON & CO.’S PUBLICATIONS.</p> - - -<p class="caption2">MODERN SCIENCE SERIES.</p> - -<p class="caption3">Edited by Sir John Lubbock, Bart., F. R. S.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE CAUSE OF AN ICE AGE.</i> By Sir Robert -Ball, LL. D., F. R. S., Royal Astronomer of Ireland; author -of “Star Land,” “The Story of the Sun,” etc.</p> - -<p class="smaller">“Sir Robert Ball’s book is, as a matter of course, admirably written. Though but a -small one, it is a most important contribution to geology.”—<i>London Saturday Review.</i></p> - -<p class="smaller">“A fascinating subject, cleverly related and almost colloquially discussed.”—<i>Philadelphia -Public Ledger</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE HORSE;</i> A Study in Natural History. By -William H. Flower, C. B., Director in the British Natural -History Museum. With 27 Illustrations.</p> - -<p class="smaller">“The author admits that there are 3,800 separate treatises on the horse already published, -but he thinks that he can add something to the amount of useful information -now before the public, and that something not heretofore written will be found in this -book. The volume gives a large amount of information, both scientific and practical, -on the noble animal of which it treats.”—<i>New York Commercial Advertiser</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE OAK:</i> A Study in Botany. By H. Marshall -Ward, F. R. S. With 53 Illustrations.</p> - -<p class="smaller">“From the acorn to the timber which has figured so gloriously in English ships -and houses, the tree is fully described, and all its living and preserved beauties and -virtues, in nature and in construction, are recounted and pictured.”—<i>Brooklyn Eagle</i>.</p> - - -<div class="dropcap">E</div> -<p class="p0"><i><span class="hidden">E</span>THNOLOGY IN FOLK LORE.</i> By George L. -Gomme, F. S. A., President of the Folklore Society, etc.</p> - -<p class="smaller">“The author puts forward no extravagant assumptions, and the method he points -out for the comparative study of folk-lore seems to promise a considerable extension of -knowledge as to prehistoric times.”—<i>Independent</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE LAWS AND PROPERTIES OF MATTER.</i> By R. T. Glazebrook, F. R. S., Fellow of Trinity -College, Cambridge.</p> - -<p class="smaller">“It is astonishing how interesting such a took can be made when the author has a -perfect mastery of his subject, as Mr. Glazebrook has. One knows nothing of the -world in which he lives until he has obtained some insight of the properties of matter -as explained in this excellent work.”—<i>Chicago Herald</i>.</p> - - -<div class="dropcap">T</div> -<p class="p0"><i><span class="hidden">T</span>HE FAUNA OF THE DEEP SEA.</i> By Sydney -J. J. Hickson, M. A., Fellow of Downing College, Cambridge. -With 23 Illustrations.</p> - -<p class="smaller">“That realm of mystery and wonders at the bottom of the great waters is gradually -being mapped and explored and studied until its secrets seem no longer secrets. . . . -This excellent book has a score of illustrations and a careful index to add to its value, -and in every way is to be commended for its interest and its scientific merit.”—<i>Chicago -Times</i>.</p> - - -<p>Each, 12mo, cloth, $1.00.</p> - - -<p class="caption3">New York: D. APPLETON & CO., 72 Fifth Avenue.</p> - -<hr class="full" /> - - -<div class="trans_notes"> -<p class="caption2">Transcriber Note</p> - -<p>Figure captions were standardized. All figures were moved to avoid -splitting paragraphs. Any minor typos were corrected.</p> - -</div> - - - - - - - - - - - - -<pre> - - - - - -End of Project Gutenberg's Man and the Glacial Period, by G. 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