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<div>*** START OF THE PROJECT GUTENBERG EBOOK 51116 ***</div>
<div id="cover" class="img">
<img id="coverpage" src="images/cover.jpg" alt="The Geologic Story of Arches National Park" width="500" height="786" />
</div>
<div class="img">
<img src="images/pmg000.jpg" alt="Geology of Arches National Park" width="600" height="292" />
</div>
<div class="img" id="pic1">
<img src="images/pmg001.jpg" alt="" width="800" height="730" />
<p class="pcap">BALANCED ROCK, guarding The
Windows section of Arches National
Park. Rock is Slick Rock Member of
Entrada Sandstone resting upon crinkly
bedded Dewey Bridge Member of
the Entrada. White rock in foreground
is Navajo Sandstone. La Sal Mountains
on right skyline. (Frontispiece)</p>
</div>
<div class="img">
<img src="images/pmg002.jpg" alt="Graphic Title Page" width="496" height="791" />
</div>
<div class="box">
<h1><span class="smaller"><i>The Geologic Story of</i></span>
<br /><span class="large"><span class="sc"><b>Arches</b></span></span>
<br /><span class="small">NATIONAL PARK</span></h1>
<p class="center">By S. W. Lohman
<br />Graphics by
<br />John R. Stacy</p>
<p class="center">GEOLOGICAL SURVEY BULLETIN 1393</p>
</div>
<p class="tbcenter">UNITED STATES DEPARTMENT OF THE INTERIOR
<br />ROGERS C. B. MORTON, <i>Secretary</i></p>
<p class="center">GEOLOGICAL SURVEY
<br />V. E. McKelvey, <i>Director</i></p>
<div class="img">
<img src="images/pmg003.jpg" alt="Department of the Interior · March 3, 1949" width="414" height="415" />
</div>
<p class="center">U.S. GOVERNMENT PRINTING OFFICE: 1975</p>
<hr />
<dl class="undent"><dt>Library of Congress Cataloging in Publication Data</dt>
<dt>Lohman, Stanley William, 1907-</dt>
<dt>The geologic story of Arches National Park.</dt>
<dt>(Geological Survey Bulletin 1393)</dt>
<dt>Bibliography: p.</dt>
<dt>Includes index.</dt>
<dt>Supt. of Docs. no.: I 19.3:1393</dt>
<dt>1. Geology—Utah—Arches National Park—Guide-books.</dt>
<dt>2. Arches National Park, Utah—Guide-books.</dt>
<dt>I. Title. II. Series: United States Geological Survey</dt>
<dt>Bulletin 1393.</dt>
<dt>QE75.B9 No. 1393 [QE170.A7] 557.3′08s [557.92′58]</dt>
<dt>74-23324</dt></dl>
<hr />
<p class="center">For sale by the Superintendent of Documents, U. S. Government Printing Office
<br />Washington, D. C. 20402
<br />Stock Number 024-001-02598-1</p>
<div class="pb" id="Page_VII">VII</div>
<h2 class="center">Contents</h2>
<dl class="toc">
<dt class="small">Page</dt>
<dt><a href="#c1">Beginning of a monument</a> 1</dt>
<dt><a href="#c2">Graduation to a park</a> 5</dt>
<dt><a href="#c3">Early history</a> 9</dt>
<dd><a href="#c4">Prehistoric people</a> 9</dd>
<dd><a href="#c5">Late arrivals</a> 12</dd>
<dt><a href="#c6">Geographic setting</a> 18</dt>
<dt><a href="#c7">Deposition of the rock materials</a> 20</dt>
<dt><a href="#c8">Bending and breaking of the rocks</a> 24</dt>
<dt><a href="#c9">Uplift and erosion of the Plateau</a> 33</dt>
<dt><a href="#c10">Origin and development of the arches</a> 37</dt>
<dd><a href="#c11">Examples of arches</a> 46</dd>
<dt><a href="#c12">How to see the park</a> 50</dt>
<dt><a href="#c13">A trip through the park</a> 52</dt>
<dd><a href="#c14">Colorado River canyon</a> 52</dd>
<dd><a href="#c15">Headquarters area</a> 57</dd>
<dd><a href="#c16">Courthouse Towers area</a> 63</dd>
<dd><a href="#c17">The Windows section</a> 68</dd>
<dd><a href="#c18">Delicate Arch area</a> 74</dd>
<dd><a href="#c19">Fiery Furnace</a> 79</dd>
<dd><a href="#c20">Salt Valley and Klondike Bluffs</a> 82</dd>
<dd><a href="#c21">Devils Garden</a> 83</dd>
<dt><a href="#c22">Summary of geologic history</a> 98</dt>
<dt><a href="#c23">Additional reading</a> 104</dt>
<dt><a href="#c24">Acknowledgments</a> 105</dt>
<dt><a href="#c25">Selected references</a> 105</dt>
<dt><a href="#c26">Index</a> 109</dt>
</dl>
<div class="pb" id="Page_VIII">VIII</div>
<h2><br /><span class="small">Figures</span></h2>
<dl class="toc">
<dt class="small">Page</dt>
<dt><a href="#pic1">Frontispiece. Balanced Rock.</a></dt>
<dt><a href="#fig1">1. Arches National Park</a> 6</dt>
<dt><a href="#fig2">2. Rock art in Arches National Park</a> 11</dt>
<dt><a href="#fig3">3. Wolfe’s Bar-DX Ranch</a> 14</dt>
<dt><a href="#fig4">4. Rock column of Arches National Park</a> 21</dt>
<dt><a href="#fig5">5. Common types of rock folds</a> 25</dt>
<dt><a href="#fig6">6. Common types of rock faults</a> 26</dt>
<dt><a href="#fig7">7. Paradox basin</a> 27</dt>
<dt><a href="#fig8">8. Geologic section across northwest end of Arches National Park</a> 28</dt>
<dt><a href="#fig9">9. Index map of northwestern part of Arches National Park</a> 28</dt>
<dt><a href="#fig10">10. Gravity anomalies over Salt Valley</a> 31</dt>
<dt><a href="#fig11">11. Tilted block of rocks in Cache Valley graben</a> 34</dt>
<dt><a href="#fig12">12. Jointed northeast flank of Salt Valley anticline</a> 36</dt>
<dt><a href="#fig13">13. Index map</a> 38</dt>
<dt><a href="#fig14">14. Tunnel Arch</a> 43</dt>
<dt><a href="#fig15">15. “Baby Arch”</a> 44</dt>
<dt><a href="#fig16">16. Broken Arch</a> 45</dt>
<dt><a href="#fig17">17. Double Arch</a> 47</dt>
<dt><a href="#fig18">18. Pothole Arch</a> 48</dt>
<dt><a href="#fig19">19. Glen Canyon Group</a> 53</dt>
<dt><a href="#fig20">20. Navajo Sandstone cliffs</a> 54</dt>
<dt><a href="#fig21">21. Mouth of Salt Wash</a> 55</dt>
<dt><a href="#fig22">22. Southeast end of faulted Cache Valley anticline</a> 56</dt>
<dt><a href="#fig23">23. Faulted Seven Mile-Moab Valley anticline</a> 58</dt>
<dt><a href="#fig24">24. Three Penguins</a> 59</dt>
<dt><a href="#fig25">25. Moab Valley</a> 60</dt>
<dt><a href="#fig26">26. Faulted wall of Entrada Sandstone</a> 61</dt>
<dt><a href="#fig27">27. Park Avenue</a> 62</dt>
<dt><a href="#fig28">28. Balanced rocks on south wall of Park Avenue</a> 64</dt>
<dt><a href="#fig29">29. Courthouse Towers</a> 65</dt>
<dt><a href="#fig30">30. The Three Gossips</a> 66</dt>
<dt><a href="#fig31">31. Sheep Rock</a> 66</dt>
<dt><a href="#fig32">32. Petrified sand dunes</a> 67</dt>
<dt><a href="#fig33">33. “Hoodoos and goblins”</a> 68</dt>
<dt><a href="#fig34">34. Eye of The Whale</a> 69</dt>
<dt><a href="#fig35">35. Intricate crossbeds in Navajo Sandstone</a> 70</dt>
<dt><a href="#fig36">36. Cove Arch and Cove of Caves</a> 71</dt>
<dt><a href="#fig37">37. North Window</a> 72</dt>
<dt><a href="#fig38">38. Looking southwestward through North Window</a> 73</dt>
<dt><a href="#fig39">39. South Window</a> 74</dt>
<dt><a href="#fig40">40. Turret Arch</a> 75</dt>
<dt><a href="#fig41">41. Parade of Elephants</a> 76</dt>
<dt><a href="#fig42">42. Suspension foot bridge across Salt Wash</a> 78</dt>
<dt><a href="#fig43">43. Delicate Arch</a> 78</dt>
<dt><a href="#fig44">44. Fiery Furnace</a> 80</dt>
<dt><a href="#fig45">45. Trail to Sand Dune Arch</a> 81</dt>
<dt><a href="#fig46">46. Sand Dune Arch</a> 82</dt>
<dt><a href="#fig47">47. Tower Arch</a> 84</dt>
<dt><a href="#fig48">48. Skyline Arch</a> 85</dt>
<dt><a href="#fig49">49. Campground in Devils Garden</a> 86</dt>
<dt><a href="#fig50">50. View north from campground</a> 87</dt>
<dt><a href="#fig51">51. Southeastern part of Devils Garden trail</a> 88</dt>
<dt><a href="#fig52">52. Pine Tree Arch</a> 89</dt>
<dt><a href="#fig53">53. Landscape Arch</a> 91</dt>
<dt><a href="#fig54">54. Navajo Arch</a> 92</dt>
<dt><a href="#fig55">55. Partition Arch</a> 93</dt>
<dt><a href="#fig56">56. Double O Arch</a> 93</dt>
<dt><a href="#fig57">57. Dark Angel</a> 94</dt>
<dt><a href="#fig58">58. “Indian-Head Arch”</a> 95</dt>
<dt><a href="#fig59">59. Geologic time spiral</a> 96</dt>
</dl>
<div class="img">
<img src="images/pmg004.jpg" alt="Petroglyph figure" width="500" height="413" />
</div>
<div class="pb" id="Page_1">1</div>
<h2 class="pcap" id="c1">Beginning of a Monument</h2>
<div class="img">
<img src="images/pmg005.jpg" alt="" width="500" height="363" />
</div>
<p>According to former Superintendent Bates Wilson
(1956), Prof. Lawrence M. Gould, of the University of
Michigan, was the first to recognize the geologic and scenic
values of the Arches area in eastern Utah and to urge its
creation as a national monument. Mrs. Faun McConkie
Tanner<a class="fn" id="fr_1" href="#fn_1">[1]</a>
told me that Professor Gould, who had done a
thesis problem in the nearby La Sal Mountains, was first
taken through the area by Marv Turnbow, third owner of
Wolfe cabin. (See <a href="#Page_12">p. 12</a>.) When Professor Gould went into
ecstasy over the beautiful scenery, Turnbow replied, “I
didn’t know there was anything unusual about it.”</p>
<p>Dr. J. W. Williams, generally regarded as father of the
monument, and L. L. (Bish) Taylor, of the Moab Times-Independent,
were the local leaders in following up on
Gould’s suggestion and, with the help of the Moab Lions
Club, their efforts finally succeeded on April 12, 1929, when
President Herbert Hoover proclaimed Arches National
<span class="pb" id="Page_2">2</span>
Monument, then comprising only 7 square miles.<a class="fn" id="fr_2" href="#fn_2">[2]</a> It was
enlarged to about 53 square miles by President Franklin
D. Roosevelt’s Proclamation of November 25, 1938, and remained
at nearly that size, with some boundary adjustments
on July 22, 1960, until it was enlarged to about 130
square miles by President Lyndon B. Johnson’s Proclamation
of January 20, 1969.</p>
<p>According to Breed (1947), Harry Goulding, of Monument
Valley, in a specially equipped car, traversed the
rugged sand and rocks of the Arches region in the fall of
1936 and, thus, became the first person to drive a car into
The Windows section of Arches National Monument. Soon
after, a bulldozer followed Harry’s tracks and made a passable
trail.</p>
<p>When my family and I visited the monument in 1946,
the entrance was about 12 miles northwest of Moab on
U.S. Highway 163 (then U.S. 160), where Goulding’s old
tire tracks led eastward past a small sign reading “Arches
National Monument 8 miles.” This primitive road crossed
the sandy, normally dry Courthouse Wash and ended in
what is now called The Windows section. At that time
there was no water or ranger station, nor were there any
picnic tables or other improvements within the monument
proper, and the custodian was housed in an old barracks
of the Civilian Conservation Corps near what is now the
entrance, 5 miles northwest of Moab.</p>
<p>Former Custodian Russell L. Mahan reported (oral
commun., May 1973) that soon after our initial visit in 1946
a 500-gallon tank was installed near Double Arch in The
Windows section and connected to a drinking fountain and
that two picnic tables and a pit toilet were added. At that
time the only access to Salt Valley and what is now called
Devils Garden was a primitive dirt road which, according
to Breed (1947, p. 175), left old U.S. Highway 160 (now
U.S. 163) 24 miles northwest of Moab, went 22 miles east,
<span class="pb" id="Page_3">3</span>
then followed Salt Valley Wash down to Wolfe cabin
(<a href="#fig1">fig. 1</a>).</p>
<p>According to Abbey (1971), who served as a seasonal
ranger beginning about 1958, a sign had by then been
erected at the crossing of Courthouse Wash which read:</p>
<p class="center">WARNING: QUICKSAND
<br />DO NOT CROSS WASH
<br />WHEN WATER IS RUNNING</p>
<p>The ranger station, his home for 6 months of the year, was
what Abbey described as “a little tin housetrailer.” Nearby
was an information display under a “lean-to shelter.” He
had propane fuel for heat, cooking, and refrigeration, and a
small gasoline-engine-driven generator for lights at night.
His water came from the 500-gallon tank, which was filled
at intervals from a tank truck. At that time there were
three small dry campgrounds, each with tables, fireplaces,
garbage cans, and pit toilets. By that time an extension of
the dirt road led northward to Devils Garden, and some
trails had been built and marked.</p>
<p>Bates Wilson became Custodian of the monument in
1949 and later became Superintendent not only of Arches
but also of the nearby new Canyonlands National Park
(<a href="../../51048/51048-h/51048-h.htm">Lohman, 1974</a>) and the more distant Natural Bridges
National Monument. In the fall of 1969, Bates told me of
some of his early experiences in the undeveloped monument,
including the evening when 22 cars were marooned
on the wrong (northeast) side of Courthouse Wash after
a flash flood. Bates and his “lone” ranger brought ropes,
coffee, and what food they could obtain in town after closing
time, threw a line across the swollen stream, had a
tourist pull a rope across, then took turns wading the
stream with one hand on the rope and the other balancing
supplies on his shoulder. After a fire had been built and hot
coffee and food passed around, the spirits of the stranded
group rose considerably, except for one irate woman
from the East, who refused to budge from her car. Bates
and his helper finally got the last car out about 1 a.m.,
after the flood had subsided, and Mrs. Wilson then supplied
lodging and more food and coffee for those who
needed it.</p>
<div class="pb" id="Page_4">4</div>
<p>During and for sometime after World War II and the
Korean War, lack of maintenance funds and personnel had
prevented improvement of the facilities in many of our national
parks and monuments, particularly in undeveloped
ones like Arches. The day was saved through the wisdom
and foresight of former Park Service Director Conrad L.
Wirth, who saw the need and desirability of putting the
whole “want” list into one attractive, marketable package.
In the words of Everhart (1972, p. 36):</p>
<blockquote>
<p>Selection of a name is of course recognized as the most important
decision in any large-scale enterprise, and here Wirth struck
pure gold. In 1966 the Park Service would be celebrating its
fiftieth anniversary. What a God-given target to shoot for! Why
not produce a ten-year program, which would begin in 1956, aimed
to bring every park up to standard by 1966—and call it Mission 66?</p>
</blockquote>
<p>The ensuing well-documented and cost-estimated plan
for Mission 66 was enthusiastically backed by President
Dwight D. Eisenhower and approved and well supported
by Congress to the tune of more than $1 billion during
the 10-year period. For Arches, this included a new entrance,
Park Headquarters, Visitor Center, a museum
boasting a bust of founder Dr. Williams, and modern
housing for park personnel, all 5 miles northwest of Moab.
By 1958 (Pierson, 1960) a fine new paved road between
Park Headquarters and Balanced Rock (frontispiece) was
completed. These badly needed improvements were followed
by the completion of the paved road all the way to
Devils Garden, the building of the modern campground,
picnic facilities, and amphitheater in the Devils Garden,
and the construction of turnouts and marked trails.</p>
<div class="img">
<img src="images/pmg006.jpg" alt="Petroglyph figure" width="500" height="161" />
</div>
<div class="pb" id="Page_5">5</div>
<h2 class="pcap" id="c2">Graduation to a Park</h2>
<div class="img">
<img src="images/pmg007.jpg" alt="" width="500" height="304" />
</div>
<p>Arches graduated to a full-fledged national
park when President Richard M. Nixon signed a Congressional
Bill on November 16, 1971. The change in status
was accompanied by boundary changes that reduced the
area to about 114 square miles. The loss of most of Dry
Mesa, just east of the present boundary (<a href="#fig1">fig. 1</a>), was
offset in part by gains of new land northwest of Devils
Garden. The present (1974) boundaries, roads, trails, and
named features of the park are shown in <a href="#fig1">figure 1</a>.</p>
<p>The park was virtually completed at graduation time,
and so far this change in status has shown up mainly in
new entrance signs, a new 1972 brochure and map, and a
very informative “Guide to an Auto Tour of Arches National
Park,” keyed to numbered signs at parking spaces.
About all that remain to be added are new wayside exhibits,
some boundary fences, and spur roads and trails.</p>
<div class="pb" id="Page_6">6</div>
<div class="img" id="fig1">
<img src="images/map1_lr.jpg" alt="" width="600" height="766" />
<p class="pcap">ARCHES NATIONAL PARK, showing location in Utah,
boundaries, streams, highways and roads, trails, landforms, principal
named features, and the city of Moab. The reader is referred
to <a href="#fig7">figure 7</a> and to road maps issued by the State or by oil
companies for the locations of other nearby towns and features.
Visitors also may obtain pamphlets, from the entrance station
or from the National Park Service office in Moab, which contain
up-to-date maps of the park and the latest available information
on roads, trails, campsites, and picnic sites. (Fig. 1)<br /><span class="center"><a class="abl" href="images/map1_hr.jpg">High-resolution Map</a></span></p>
</div>
<div class="pb" id="Page_8">8</div>
<p>Although Arches had officially become a park in November
1971, it was not formally dedicated until May 15, 1972.
The ceremony began by having the Federal, State, and
local dignitaries and other guests totaling 140 persons
board the <i>Canyon King</i>, a 93-foot replica of a Mississippi
River sternwheeler (Lansford, 1972; <a href="../../51048/51048-h/51048-h.htm#fig69">Lohman, 1974, fig. 69</a>),
for its maiden voyage down the Colorado River. After
about half an hour, the heavily laden boat became stuck
on a sandbar, and after a 90-minute wait the passengers
were rescued by jet boats. This delayed a luncheon at the
Visitor Center put on by the Moab Lions Club. Following
the luncheon, Park Superintendent Bates Wilson made a
brief welcoming address, then introduced J. Leonard Volz,
Director of the Midwest Region of the National Park Service,
who served as master of ceremonies. Speakers included
Utah Governor Calvin L. Rampton, Senator Frank
E. Moss, a representative of Senator Wallace F. Bennett,
Representatives Sherman P. Lloyd of Utah and Wayne
Aspinall of Colorado, and Mitchell Melich, Solicitor General
of the Department of Interior, representing Secretary
Rogers C. B. Morton. After the speeches, a commemorative
plaque, donated by the Canyonlands Natural History Association,
was unveiled by Senator Moss and Mr. Melich.</p>
<p>Most of the color photographs were taken by me on
4- × 5-inch film in a tripod-mounted press camera, using
lenses of several focal lengths, but a few were taken on
35-mm film, using lenses of various focal lengths. I am
grateful to several friends for the color photographs credited
to them in the figure captions. The black and white
photographs were kindly loaned from the Moab and
Arches files of the National Park Service. The points from
which most of the photographs were taken are shown in
<a href="#fig13">figure 13</a>.</p>
<div class="img">
<img src="images/pmg010.jpg" alt="Petroglyph figure" width="500" height="129" />
</div>
<div class="pb" id="Page_9">9</div>
<h2 class="pcap" id="c3">Early History</h2>
<div class="img">
<img src="images/pmg011.jpg" alt="" width="500" height="228" />
</div>
<h3 id="c4">Prehistoric People</h3>
<p>The Canyon lands in and south of Arches were
inhabited by cliff dwellers centuries before the first visits
of the Spaniards and fur trappers. Projectile points and
other artifacts found in the nearby La Sal and Abajo
Mountains indicate occupation by aborigines during the
period from about 3000-2000 <span class="sc">B.C.</span> to about <span class="sc">A.D.</span> 1 (Hunt,
Alice, 1956). The Fremont people occupied the area around
<span class="sc">A.D.</span> 850 or 900, and the Pueblo or Anasazi people from
about <span class="sc">A.D.</span> 1075 to their departure in the late 12th century
(Jennings, 1970). Most of the evidence for these early
occupations has been found in and south of Canyonlands
National Park (<a href="../../51048/51048-h/51048-h.htm">Lohman, 1974</a>), but some traces of these
and possibly earlier cultures have been found also within
Arches National Park.</p>
<p>Ross A. Maxwell (National Park Service, written
commun., 1941) investigated two caves in the Entrada
Sandstone in the upper reaches of Salt Wash that contain
Anasazi ruins. He mentioned that perhaps a dozen or more
other caves should be checked for evidence of former occupation
and, also, that he found several ancient campsites
littered with flint chips and broken tools.</p>
<p>One cave Maxwell explored some 5 miles north of Wolfe
Ranch and north of the park is about 300 feet long and
100 to 150 feet deep. It contains the remains of one or
more ruins of a structure he thought may have covered
much of the floor. The remaining parts of walls now are
only two to four tiers of stones in height, although originally
they may have been more than one story high.
<span class="pb" id="Page_10">10</span>
Maxwell explored a second cave on the east side of Salt
Wash, about 2 miles north of Wolfe Ranch, which contains
16 storage cists of adobe.</p>
<p>The faces of many older sandstone cliffs or ledges are
darkened by desert varnish—a natural pigment of iron
and manganese oxides. The prehistoric inhabitants of the
Plateau learned that effective and enduring designs, called
petroglyphs, could be created simply by chiseling or pecking
through the thin dark layer to reveal the buff or tan
sandstone beneath. Most petroglyphs were created by the
Anasazi, but those showing men mounted on horses were
done by Ute tribesmen after the Spaniards brought in
horses in the 1500’s. The Fremont people and some earlier
people painted figures on rock faces, called pictographs,
and some of these had pecked outlines.</p>
<p>The so-called “Moab panel” was described by Beckwith
(1934, p. 177) as a petroglyph, but, as pointed out by
Schaafsma (1971, p. 72, 73), it comprises figures having
pecked outlines and painted bodies, which actually are
combinations of petroglyphs and pictographs. This beautifully
preserved group of paintings is shown in the upper
photograph of <a href="#fig2">figure 2</a>. Mrs. Schaafsma goes on to say,
concerning the “Moab panel”:</p>
<blockquote>
<p>The long tapered body, the antenna like headdresses, and the
staring eyes are characteristic features of Barrier Canyon style
figures elsewhere * * *. Of special interest here are the large
shields held by certain figures. A visit to this site indicated that
the shields, although apparently of some antiquity, have been
superimposed over some of the Barrier Canyon figures. Whether
or not this was done by the Barrier Canyon style artists themselves
or later comers to the site is impossible to tell.</p>
</blockquote>
<p>Although definite proof seems lacking, she suggested
(written commun., Nov. 3, 1973) that the “‘Barrier Canyon
style’<a class="fn" id="fr_3" href="#fn_3">[3]</a> * * * is earlier than the work in the same
region clearly attributable to the Fremont.” Note the
three bullet holes in and near the right-hand shield. A
ledge above the panel that contained petroglyphs during
her earlier visit had fallen to the base of the cliff by the
time my wife and I inspected the panel in September 1973.</p>
<div class="pb" id="Page_11">11</div>
<div class="img" id="fig2">
<img src="images/pmg012.jpg" alt="" width="800" height="526" />
<p class="pcap">ROCK ART IN ARCHES NATIONAL PARK. A (above), “Moab panel,”
on cliff of Wingate Sandstone above U.S. Highway 163 between
Courthouse Wash and Colorado River, believed to be the work
of “Barrier Canyon” style people. B (below), Petroglyphs on ledge
of sandstone in Morrison Formation on east side of Salt Wash
just north of Wolfe Ranch, believed to have been cut by Ute
tribesmen. (Fig. 2)</p>
</div>
<div class="img">
<img src="images/pmg013.jpg" alt="Fig. 2 B" width="800" height="568" />
</div>
<div class="pb" id="Page_12">12</div>
<p>Mrs. Schaafsma believes the petroglyphs in the lower
photograph of <a href="#fig2">figure 2</a> to be the work of Ute tribesmen,
not only because of the horses, but also because of the
stiff-legged appearance of the mountain sheep. Note the
bullet hole above the panel.</p>
<h3 id="c5">Late Arrivals</h3>
<p>Later arrivals in and near Arches National Park included
first Spanish explorers, then trappers, cattlemen,
cattle rustlers and horse thieves, followed in the present
century by oil drillers, uranium hunters, jeepsters, and
tourists. Butch Cassidy, the Sundance Kid, and other
members of The Wild Bunch are known to have frequented
parts of what is now Canyonlands National Park (Baker,
Pearl, 1971), but it is not certain whether or not any of
them traversed what is now Arches National Park.</p>
<p>The first settler in what is now Arches National Park
was a Civil War veteran named John Wesley Wolfe, who
was discharged from the Union Army about 3 weeks
before the Battle of Bull Run because he suffered from
varicose veins. In 1888 his doctor told him he had to leave
Ohio for a dryer climate or he would not live 6 months, so
he took his son Fred west and settled on a tract of 150
acres along the west bank of Salt Wash, where his “Wolfe
cabin” still stands (figs. <a href="#fig1">1</a>, <a href="#fig3">3</a>). From family letters and
newspaper clippings compiled by Mrs. Maxine Newell and
other members of the National Park Service (Maxine
Newell, written commun., 1971), we learn what life in the
area was like:</p>
<blockquote>
<p>We have started a cattle spread on a desert homestead. We call
it the Bar-DX Ranch. Fred and I live in a little log
house on the bank of a creek that is sometimes dry, sometimes
flooded from bank to bank with roaring muddy water. We are
surrounded with rocks—gigantic red rock formations, massive
arches and weird figures, the like of which youve [sic] never
seen. The desert is a hostile, demanding country, hot in summer,
cold in winter. The Bar-DX Ranch is a day’s ride from the nearest
store, out of the range of schools.</p>
</blockquote>
<div class="pb" id="Page_13">13</div>
<p>Although John Wolfe had promised his wife and his
other children that he would return home the first fall
that his cattle sales netted enough money, he and Fred
stayed on and on, and his wife refused to go west and
join her husband and son. Eighteen years later he sent
money from his pension check to his daughter, Mrs. Flora
Stanley, his son-in-law, Ed Stanley, and his two grandchildren,
Esther and Ferol, to join him and Fred at the
ranch. Their train was met at Thompson Springs (now
Thompson), Utah (<a href="#fig7">fig. 7</a>), by John Wolfe for the 30-mile
ride to the ranch by horse and wagon. Sight of the tiny
log cabin with only a dirt floor brought tears to his daughter’s
eyes, but her spirits rose considerably after John
Wolfe promised to build a new log cabin with a wooden
floor. But the children were enchanted with this strange
country, with the building of the new cabin, and, especially,
with getting to go rabbit hunting with Grandpa Wolfe.
The Stanleys stayed at the ranch until Esther was 10,
then moved to Moab to await the arrival of their third
child, Volna.</p>
<p>In 1910 John Wolfe sold the Bar-DX Ranch, and the
entire family moved to Kansas. John Wolfe later moved
back to Ohio, and died at Etna, Licking County, on
October 22, 1913, at the age of 84, 25 years after his doctor
had warned him to move to a dryer climate or face an
early death.</p>
<p>Wolfe had sold his spread to Tommy Larson, who later
sold it to J. Marv Turnbow and his partners, Lester Walker
and Stib Beeson. The old log cabin gradually came to
be known as the “Turnbow cabin,” and this name appeared
on early maps of the area by the U.S. Geological Survey
and on early pamphlets by the National Park Service,
partly because Marv Turnbow served as a camphand in
1927 assisting in the first detailed geologic mapping of the
area (Dane, 1935, p. 4). In 1947 the ranch was sold to
Emmett Elizondo, who later sold it to the Government
for inclusion in what was then the monument.</p>
<p>From information supplied by Wolfe’s granddaughter,
Mrs. Esther Stanley Rison, and his great-granddaughter,
Mrs. Hazel Wolfe Hastler, who visited the cabin in July
<span class="pb" id="Page_14">14</span>
1970, the original name Wolfe cabin, or Wolfe Ranch, has
been restored, and appears on the newer maps and pamphlets.
(See <a href="#fig1">fig. 1</a>.) What remains of Wolfe’s Bar-DX
Ranch is shown in <a href="#fig3">figure 3</a>.</p>
<div class="img" id="fig3">
<img src="images/pmg014.jpg" alt="" width="800" height="479" />
<p class="pcap">WOLFE’S BAR-DX RANCH, on west bank of Salt Wash at start of
trail to Delicate Arch. Left to right: Corral, wagon, “new” cabin,
and root cellar. “Old” cabin, which formerly was to right of photograph,
was washed away by a flood in 1906. (Fig. 3)</p>
</div>
<p>Arches National Park is surrounded by active uranium
and vanadium mines and by many test wells for oil, gas,
and potash; it is underlain by extensive salt and potash
deposits. Oil and gas are produced a few miles to the north
and east, and potash is being produced about 12 miles to
the south (<a href="../../51048/51048-h/51048-h.htm">Lohman, 1974</a>).</p>
<p>Uranium and vanadium have been mined on the Colorado
Plateau since 1898 (Dane, 1935, p. 176) and in the
Yellow Cat area (also called Thompson’s area), just north
of the park (<a href="#fig1">fig. 1</a>), since about 1911 (Stokes, 1952, p. 7).
The deposits in the Yellow Cat area occur in the Salt
Wash Sandstone Member of the Morrison Formation (<a href="#fig4">fig. 4</a>).
According to Pete Beroni (U.S. Atomic Energy Commission,
oral commun., August 6, 1973), some ore is still
being produced in the Yellow Cat area, and the production
of vanadium ore will increase as soon as the uranium mill
at Moab is converted to also handle vanadium ore. The
<span class="pb" id="Page_15">15</span>
Corral and so-called Shinarump mines along the southwest
side of Moab Canyon just north of Sevenmile Canyon (<a href="#fig1">fig. 1</a>)
are still actively producing uranium ore from the Moss
Back Member of the Chinle Formation, according to
Mr. Beroni.</p>
<p>The occurrences of salt and potash in and near the park
and the attempts to find oil and gas nearby are discussed
in a recent report (Hite and Lohman, 1973), and the
deposits beneath Moab, Salt, and Cache Valleys are discussed
in later chapters.</p>
<p>In 1955 and 1956 the Pacific Northwest Pipeline, known
also as the “Scenic Inch,” was constructed by the Pacific
Northwest Pipeline Corp. to transmit natural gas from
wells in the San Juan Basin of northwestern New Mexico
for a total of 1,487 miles to the Pacific Northwest, with
additional pickups from gas fields in northeastern Utah,
northwestern Colorado, and southwestern Wyoming (Walters,
1956). This 26-inch pipeline follows the general route
of U.S. Highway 163 from Cortez, Colo., past Moab to
Sevenmile Canyon 10 miles northwest of Moab, where it
turns abruptly to the northeast and crosses about the middle
of Arches National Park. It crosses the park road and
the flat area between the Fiery Furnace and the southeast
end of Devils Garden, but the scars are so well healed that
most visitors are unaware of its existence unless they
happen to look southwestward across Salt Valley, where
the filled excavation is still visible. The filled trench also
appears in the lower middle of <a href="#fig23">figure 23</a>.</p>
<p>Unlike Canyonlands National Park a few miles to the
south, Arches was not on the route of the famous early-day
river expeditions of John Wesley Powell or of most of
those that followed; however, the southeastern boundary
of the park is the Colorado River, formerly the Grand,
which was traversed by the first leg of the ill-fated Brown-Stanton
expedition (Dellenbaugh, 1902, p. 343-369; <a href="../../51048/51048-h/51048-h.htm">Lohman, 1974</a>).</p>
<p>The canyon of the Colorado River along the southeastern
park boundary is deep and beautiful and is a favorite
stretch of quiet water for boaters and floaters. Partly
paved State Highway 128 on the east bank is a part of a
<span class="pb" id="Page_16">16</span>
most scenic drive from Moab to Cisco—a small railroad
town about 32 miles northeast of the eastern border of
<a href="#fig1">figure 1</a> (<a href="#fig7">fig. 7</a>). This road has been variously called the
“Moab Mail Road,” the “Cisco Cutoff,” the “Dewey
Road,” or the “Dewey Bridge Road” after an old suspension
bridge (<a href="#fig7">fig. 7</a>) across the Colorado River at the old
townsite of Dewey about 12 miles south of Cisco. During
the summer this deep colorful canyon may be viewed at
night by artificial illumination. Each evening one-half hour
after sundown, an 80-passenger jet boat leaves a dock north
of the highway bridge, carries passengers several miles upstream,
then floats slowly downstream followed by a truck
on the highway carrying 40,000 watts of searchlights
which play back and forth on the colorful red canyon
walls, while the passengers listen to a taped discourse. The
entire trip requires about 2 hours.</p>
<p>The spectacular arches and red rocks of Arches and
vicinity have been used to advantage in making color movies
and color TV shows. Parts of the recent Walt Disney
film “Run, Cougar, Run” were filmed beneath Delicate
Arch (<a href="#fig43">fig. 43</a>), in Professor Valley of the Colorado River
just east of the park (<a href="#fig7">fig. 7</a>), and in other sections of the
canyon country.</p>
<p>Ever since military jet aircraft broke the sound barrier,
there has been a growing number of protests from concerned
citizens, organizations, and National Park Service
officials concerning the dangers sonic booms have posed to
Indian ruins and delicate erosional forms in our national
parks and monuments, such as natural bridges, arches and
windows, balanced rocks, and natural spires or towers.
Many instances of damaged ruins, roads, erosional forms,
and broken windows were reported. My wife and I can
vouch for the destructive power of such booms, for in
October 1969, while we were having breakfast at Squaw
Flat Campground in The Needles section of Canyonlands
National Park, a particularly severe blast from a low-flying
jet not only violently rocked our jack-supported trailer
but broke the windshield of our car.</p>
<p>At Arches National Park, particular fear was felt for
Landscape Arch (<a href="#fig53">fig. 53</a>), thought to be the longest natural
<span class="pb" id="Page_17">17</span>
stone arch in the world, and many a special round
trip from headquarters involving 47 road miles and 2
trail miles was made to check on the condition of this arch
after especially loud sonic booms were heard. Finally, in
April 1972, following a rash of newspaper and magazine
articles that spread across the nation, the Secretary of the
Air Force put a virtual stop to this danger by ruling
that, except in an emergency (Moab Times-Independent,
April 12, 1972):</p>
<blockquote>
<p>Supersonic flights must not only avoid passing over national
parks, they also may not fly near them, according to the new
regulation. For each 1,000 feet of altitude, the pilot must allow
one-half mile between the flight path and the park boundary. The
regulation also prohibits supersonic flights below 30,000 feet
(over land) so the high speed planes must allow 15 miles between
the nearest park boundary and the flight path.</p>
</blockquote>
<p>Let us hope that with the aid of this long-needed regulation
and cooperation from visitors, the arches will remain
intact for many more generations to see.</p>
<div class="img">
<img src="images/pmg015.jpg" alt="Petroglyph figure" width="300" height="356" />
</div>
<div class="pb" id="Page_18">18</div>
<h2 class="pcap" id="c6">Geographic Setting</h2>
<div class="img">
<img src="images/pmg016.jpg" alt="" width="500" height="255" />
</div>
<p>Geologists have divided the United States into
many provinces, each of which has distinctive geologic and
topographic characteristics that set it apart from the
others. One of the most intriguing and scenic of these is
the Colorado Plateaus province, referred to in this report
simply as the Colorado Plateau, or the Plateau (Hunt, C.
B., 1956, <a href="#fig1">fig. 1</a>). This province, which covers some 150,000
square miles and is not all plateaus, as we shall see, extends
from Rifle, Colo., at the northeast to a little beyond
Flagstaff, Ariz., at the southwest, and from Cedar City,
Utah, at the west nearly to Albuquerque, N. Mex., at the
southeast. Arches National Park occupies part of the Canyon
Lands Section, one of the six subdivisions of the
Plateau. As the names imply, the Canyon Lands Section
of the Plateau comprises a high plateau generally ranging
in altitude from 5,000 to 7,000 feet, which has been intricately
dissected by literally thousands of canyons.</p>
<p>Arches National Park is drained entirely by the Colorado
River, whose deep canyon borders the park on the
southeast (<a href="#fig1">fig. 1</a>). Most of the park is drained by Salt
Wash, which enters the Colorado River just southeast of
The Windows section, but the southwestern part is drained
by Courthouse Wash and Moab Canyon, whose flows
join the Colorado just west of the bridge on which U.S.
Highway 163 crosses the river.</p>
<p>When viewed at a distance of 1 foot, the shaded relief
map (<a href="#fig1">fig. 1</a>) shows the general shape of the land surface
in and near Arches National Park to the same horizontal
scale as it would appear to a person in a spacecraft flying
at a height of 250,000 feet, or about 47.5 miles. This map
<span class="pb" id="Page_19">19</span>
was prepared from part of the reverse side of a plastic-relief
map<a class="fn" id="fr_4" href="#fn_4">[4]</a> at a scale of 1:250,000 by the U.S. Army Map
Service of the Moab quadrangle, using a simple time- and
money-saving method (Stacy, 1962).</p>
<div class="img">
<img src="images/pmg017.jpg" alt="Petroglyph figure" width="500" height="535" />
</div>
<div class="pb" id="Page_20">20</div>
<h2 class="pcap" id="c7">Deposition of The Rock Materials</h2>
<div class="img">
<img src="images/pmg018.jpg" alt="" width="500" height="273" />
</div>
<p>The vivid and varied colors of the bare rocks and
the fantastic buttes, spires, columns, alcoves, caves, arches,
and other erosional forms of Arches National Park result
from a fortuitous combination of geologic and climatic
circumstances and events unequalled in most other parts
of the world.</p>
<p>First among these events was the piling up, layer upon
layer, of thousands of feet of sedimentary rocks under a
wide variety of environments. Sedimentary rocks of the
region are composed of clay, silt, sand, and gravel carried
and deposited by moving water; silt and sand transported
by wind; and some materials precipitated from water solutions,
such as limestone (calcium carbonate), dolomite
(calcium and magnesium carbonate), gypsum (calcium
sulfate with some water), anhydrite (calcium sulfate
alone), common salt (sodium chloride), potash minerals,
such as potassium chloride, and a few other less common
types. Some of the beds were laid down in shallow seas
that once covered the area or in lagoons and estuaries
near the sea. Other beds were deposited by streams in inland
basins or plains, a few were deposited in lakes, and
the constituents of deposits like the Navajo Sandstone,
were carried in by the wind. The character and thickness
of the exposed sedimentary rocks and the names and ages
assigned to them by geologists are shown in the rock
column (<a href="#fig4">fig. 4</a>) and in the cross section (<a href="#fig8">fig. 8</a>). The history
of their deposition is summarized on pages <a href="#Page_98">98</a>-<a href="#Page_102">102</a>.
<a href="#fig4">Figure 4</a> was compiled mainly from generalized sections
given by A. A. Baker (1933), Dane (1935), McKnight
(1940), and Wright, Shawe, and Lohman (1962), and, in
part, from Hite and Lohman (1973).</p>
<div class="pb" id="Page_21">21</div>
<div class="img" id="fig4">
<img src="images/pmg019.jpg" alt="" width="1000" height="622" />
<p class="pcap">ROCK COLUMN OF ARCHES NATIONAL PARK. Average thickness
of units 250-1,000 feet is exaggerated two times; those less than
250 feet, four times. 1 foot = 0.305 meter. (Fig. 4)</p>
</div>
<div class="ss">
<dl class="undent"><dt>AGE (millions of yrs ago)</dt>
<dd>GEOLOGIC AGE</dd>
<dd class="t">NAME OF ROCK UNIT</dd>
<dd class="t4">KIND OF ROCK AND HOW IT IS SCULPTURED BY EROSION</dd>
<dd class="t5">THICKNESS (feet)</dd>
<dd class="t6">NAMED FOR OCCURRENCE AT OR NEAR</dd></dl>
<dl class="undent"><dt>100</dt>
<dd>Late Cretaceous</dd>
<dd class="t">Mancos Shale</dd>
<dd class="t4">Lead-gray fossiliferous marine shale. Forms slopes.</dd>
<dd class="t5">?</dd>
<dd class="t6">Mancos, Colo.</dd>
<dd class="t">Dakota Sandstone</dd>
<dd class="t4">Conglomeratic sandstone, gray shale, carbonaceous shale, and coal. Forms ledge.</dd>
<dd class="t5">100</dd>
<dd class="t6">Dakota, Nebr.</dd>
<dd class="t">Unconformity</dd>
<dd>Late Jurassic</dd>
<dd class="t">Morrison Fm.</dd>
<dd class="t5">700</dd>
<dd class="t6">Morrison, Colo.</dd>
<dd class="t2">Brushy Basin Member</dd>
<dd class="t4">Variegated shale, some sandstone and conglomerate, petrified wood, chert, and dinosaur bones. May contain some beds of Burro Canyon (Early Cretaceous) age.</dd>
<dd class="t2">Salt Wash Member</dd>
<dd class="t4">Crossbedded white and gray conglomeratic sandstone beds and lenses, locally carnotite bearing, and red and gray sandy mudstone. Forms slopes.</dd>
<dd class="t">Unconformity</dd>
<dt>160</dt>
<dd class="t">San Rafael Group</dd>
<dd class="t6">(San Rafael Swell, Utah)</dd>
<dd class="t2">Summerville Fm.</dd>
<dd class="t4">Thin bedded red sandstone and shale. Some cherty limestone concretions. Forms slopes.</dd>
<dd class="t5">0-40</dd>
<dd class="t6">Summerville Point, Utah</dd>
<dd class="t2">Entrada Ss.</dd>
<dd class="t6">(Entrada Point, Utah)</dd>
<dd class="t3">Moab Member</dd>
<dd class="t4">White, crossbedded fine-grained sandstone. Caps Slick Rock Member north of Devils Garden and Fiery Furnace and on Klondike Bluffs.</dd>
<dd class="t5">0-100</dd>
<dd class="t6">Moab, Utah</dd>
<dd class="t3">Slick Rock Member</dd>
<dd class="t4">Salmon-colored to pink and white fine-grained generally crossbedded sandstone, containing some medium- to coarse-grained sand. Generally forms cliffs or narrow fins many of which contain arches or windows.</dd>
<dd class="t5">0-240</dd>
<dd class="t6">Slick Rock, Colo.</dd>
<dd class="t3">Dewey Bridge Member</dd>
<dd class="t4">Red muddy sandstone and sandy mudstone, with contorted bedding. Forms easily eroded bases to arches in Windows Section, hence aided in their development.</dd>
<dd class="t5">0-175</dd>
<dd class="t6">Dewey Bridge, Utah</dd>
<dd class="t">Unconformity</dd>
<dt>190</dt>
<dd>Jurassic and Triassic(?);</dd>
<dd class="t">Glen Canyon Group</dd>
<dd class="t2">Navajo Sandstone</dd>
<dd class="t4">Massive crossbedded buff, gray, and white fine-grained sandstone, and local beds of gray limestone. Forms cliffs along Colorado River, floors Windows Section.</dd>
<dd class="t5">0-350</dd>
<dd class="t6">Navajo Country, Four Corners (Glen Canyon, U.)</dd>
<dd>Late Triassic(?)</dd>
<dd class="t2">Kayenta Formation</dd>
<dd class="t4">Lavender, gray, and white lenses of sandstone, red sandy shale, and conglomerate. Contains some freshwater shells. Caps and protects cliffs of Wingate Sandstone.</dd>
<dd class="t5">0-250</dd>
<dd class="t6">Kayenta, Ariz.</dd>
<dd>Late Triassic</dd>
<dd class="t2">Wingate Sandstone</dd>
<dd class="t4">Massive, horizontally bedded and crossbedded reddish buff fine-grained sandstone. Forms vertical cliffs along Colorado River, Cache Valley, Salt Wash, and Courthouse Wash.</dd>
<dd class="t5">0-350</dd>
<dd class="t6">Fort Wingate, N. Mex.</dd>
<dt>200</dt>
<dd class="t">Chinle Formation</dd>
<dd class="t4">Irregularly bedded buff to red sandstone, red mudstone, limestone, and conglomerate. Lenticular sandstone and conglomerate (Moss Back Member) locally at base. Freshwater shells, petrified wood, reptile bones. Forms slopes.</dd>
<dd class="t5">0-700</dd>
<dd class="t6">Chinle Valley, Ariz.</dd>
<dd class="t6">Moss Back Ridge, Utah Unconformity</dd>
<dd>Middle(?) and Early Triassic</dd>
<dd class="t">Moenkopi Formation</dd>
<dd class="t4">Thin-bedded brown shale, gray and brown sandstone, arkosic grit, and conglomerate. Crops out on southwest side of Moab Valley and in several places in Salt and Cache Valleys. Forms slopes.</dd>
<dd class="t5">0-1,300</dd>
<dd class="t6">Moenkopi Wash, Ariz.</dd>
<dd class="t">Unconformity</dd>
<dt>250</dt>
<dd>Permian</dd>
<dd class="t">Cutler Formation</dd>
<dd class="t4">Chocolate brown and red sandy shale, maroon and pinkish-gray arkose and conglomerate. Lower part probably equivalent in age to Rico Formation in areas to south and east. Crops out in Moab Canyon west of Moab fault. Forms slopes.</dd>
<dd class="t5">0-2,500</dd>
<dd class="t6">Cutler Creek, Colo.</dd>
<dd>Pennsylvanian</dd>
<dd class="t">Hermosa Formation</dd>
<dd class="t2">Unnamed upper member</dd>
<dd class="t4">Gray marine fossiliferous sandy limestone, gray and greenish-gray sandstone and sandy shale, and red sandy shale. Exposed in ledges southwest of Moab fault in highway cut west of park entrance.</dd>
<dd class="t5">0-1,500</dd>
<dd class="t6">Hermosa Creek, Animas River Valley, Colo.</dd>
<dt>300</dt>
<dd class="t2">Paradox Member</dd>
<dd class="t4">Salt, gypsum, and anhydrite, with black and gray shale and limestone. Few exposures in Salt and Cache Valleys. Forms slopes.</dd>
<dd class="t5">0-11,000</dd>
<dd class="t6">Paradox Valley, Colo.</dd>
<dd class="t">Unconformity</dd>
<dd>Pennsylvanian(?)</dd>
<dd class="t">Unnamed conglomerate</dd>
<dd class="t4">Yellow sandstone with boulders of limestone and chert containing Mississippian fossils. Exposed at two places in Salt Valley.</dd>
<dd class="t5">?</dd></dl>
</div>
<div class="pb" id="Page_22">22</div>
<p>Not exposed in the area but present far beneath the
sedimentary cover and exposed in several places a few
miles to the northeast are examples of the other two
principal types of rocks—(1) igneous rocks, solidified
from molten rock forced into or above preexisting rocks
along cracks, joints, and faults, and (2) much older metamorphic
rocks, formed from other preexisting rock types
by great heat and pressure at extreme depths. Igneous
rocks of Tertiary age (<a href="#fig59">fig. 59</a>) form the nearby La Sal
Mountains. The particles comprising the sedimentary
rocks in the area were derived by weathering and erosion
of all three types of rocks in various source areas.</p>
<p>Arches National Park and nearby Canyonlands National
Park are both in the heart of the Canyon Lands
Section of the Plateau; therefore, it is only reasonable to
wonder why the differences in their general character seemingly
outweigh their similarities. First, let us consider the
similarities. Both parks are underlain by dominantly red
sedimentary rocks, both parks feature unusual erosional
forms of sandstone, and both contain beautiful natural
arches, although the arches in Canyonlands are restricted
almost entirely to the southeastern part of The Needles
section and are in much older rocks than those in Arches.</p>
<p>To be sure, differences in the rocks themselves play a
part in the dissimilarity of the two parks, and these differences
are of two types. First, there are lateral changes in
the character of the strata, known to geologists as facies
changes, brought about by differences in the environment,
in the type of materials, and in the mode of deposition
even within relatively short distances. Thus, during parts
of the Permian Period while sand, later to be known as
the Cedar Mesa and White Rim Sandstone Members of
<span class="pb" id="Page_23">23</span>
the Cutler Formation, was being deposited in the southern
part of Canyonlands, red mud, silt, and sand of the Cutler
were laid down farther north in Canyonlands
(<a href="../../51048/51048-h/51048-h.htm#fig9">Lohman, 1974, fig. 9</a>), and similar, though somewhat coarser, beds
of the Cutler were laid down at Arches (<a href="#fig4">fig. 4</a>). Further
comparisons of the rock columns in the two parks show
that while limestones of the Rico Formation were being
deposited in a shallow sea in the southern part of Canyonlands,
additional red mud, silt, and sand of the Cutler
were being laid down above sea level in areas to the northeast.
The source of the coarser materials was the ancient
Uncompahgre Highland, which stood above sea level from
Late Pennsylvanian time to Late Triassic time (figs. <a href="#fig7">7</a>,
<a href="#fig59">59</a>). Although wider and longer, it occupied about the
same position as the present Uncompahgre Plateau between
Grand Junction and Gateway, Colo. Streams eroded
the hard igneous and metamorphic rocks from this ancient
landmass and dumped the material into basins to the
northeast and southwest. The basin to the southwest, now
called the Paradox basin (after Paradox Valley, Colo.), at
intervals contained shallow seas and lagoons, which I will
discuss later.</p>
<p>Comparison of the rock columns for the two parks also
reveals other differences. Both parks contain exposures of
rocks as old as the Pennsylvanian Paradox Member of the
Hermosa Formation. However, only in the Horseshoe Canyon
Detached Unit of Canyonlands are rocks as young as
the Jurassic Entrada Sandstone, whereas all the spectacular
natural arches that make Arches famous were formed
in the Entrada Sandstone, and Arches also contains several
younger formations of Jurassic and Cretaceous age
(<a href="#fig4">fig. 4</a>).</p>
<p>A commonly asked question is “Why are most of the
rocks so red, particularly those in which the arches were
formed?” This can be answered with one word—iron, the
same pigment used in rouge and in paint for barns and
boxcars. Various oxides of iron, some including water,
produce not only brick red but also pink, salmon, brown,
buff, yellow, and even green or bluish green. This does not
imply that the rocks could be considered as sources of
<span class="pb" id="Page_24">24</span>
iron ore, for the merest trace, generally only 1 to 3 percent,
is enough to produce even the darkest shades of red. The
white or nearly white Navajo Sandstone and the Moab
Member of the Entrada Sandstone contain little or no iron.</p>
<p>As pointed out by Stokes (1970, p. 3), microscopic
examination of the colored grains of quartz or other
minerals shows the pigment to be merely a thin coating on
and between white or colorless particles. Sand or silt
weathered from such rocks soon loses its color by the
scouring action of wind or water, so that most of the sand
dunes and sand bars are white or nearly so.</p>
<h2 class="pcap" id="c8">Bending And Breaking of The Rocks</h2>
<div class="img">
<img src="images/pmg020.jpg" alt="" width="500" height="186" />
</div>
<p>Perhaps the greatest geologic contrast between
these two closely adjacent parks lies in their different geologic
structure—the kind and amount of bending and
breaking of the once nearly flat lying strata. Consolidated
rocks, particularly brittle types, are subject to two types
of fracturing by Earth forces. Joints are fractures along
which no movement has taken place. Faults are fractures
along which there has been displacement of the two sides
relative to one another (<a href="#fig6">fig. 6</a>). As noted in the report on
Canyonlands National Park (<a href="../../51048/51048-h/51048-h.htm">Lohman, 1974</a>), the strata
there, particularly along the valley of the Green River, are
virtually flat lying or have only very gentle dips. Along the
Colorado River above the confluence with the Green, however,
the slightly dipping strata are interrupted by several
gentle anticlinal and synclinal folds (<a href="#fig5">fig. 5</a>) and by at
least one fault (<a href="#fig6">fig. 6</a>). The largest of these folds—the
Cane Creek anticline, which crosses the Colorado River
north of Canyonlands—has yielded oil in the past and is
<span class="pb" id="Page_25">25</span>
now yielding potash by solution mining of salt beds in
the Paradox Member of the Hermosa Formation.</p>
<div class="img" id="fig5">
<img src="images/pmg021.jpg" alt="" width="500" height="733" />
<p class="pcap">COMMON TYPES OF ROCK FOLDS. Top, Anticline, or upfold;
closed anticlines are called domes. Bottom, Syncline, or downfold;
closed synclines are called basins. From Hansen (1969, p. 31,
108). (Fig. 5)</p>
</div>
<p>In strong contrast to Canyonlands, Arches National
Park contains three northwesterly trending major folds
and is bordered on the southwest by a fourth. The largest
and most important are the collapsed Salt Valley and
Cache Valley anticlines, which separate the two most
scenic groups of arches and other erosional forms—Eagle
Park, Devils Garden, Fiery Furnace, and Delicate Arch
on the northeast, and Klondike Bluffs, Herdina Park, and
The Windows section on the southwest. Farther southwest
is the Courthouse syncline, containing the attractive
group of erosional forms called Courthouse Towers (<a href="#fig1">fig. 1</a>).
<span class="pb" id="Page_26">26</span>
Finally, near the southwest edge of the park, is the
Seven Mile-Moab Valley anticline (also known as the
Moab-Spanish Valley anticline), whose southwest limb is
cut off by the Moab fault (figs. <a href="#fig7">7</a>, <a href="#fig23">23</a>). The folds just
named and the sharply contrasting geologic structures of
the two parks are well shown on sheet 2 of the geologic
map of the Moab quadrangle (Williams, 1964), and the
geologic formations are shown in color on sheet 1.</p>
<div class="img" id="fig6">
<img src="images/pmg022.jpg" alt="" width="500" height="770" />
<p class="pcap">COMMON TYPES OF FAULTS. Top, Normal, or gravity fault, resulting
from tension in and lengthening of the Earth’s crust. Bottom,
reverse fault, resulting from compression in and shortening
of the Earth’s crust. Low-angle reverse faults generally are called
overthrusts or overthrust faults. In both types, note amount of
displacement and repetition of strata. Displacements may range
from a few inches or feet to many thousands of feet. From Hansen
(1969, p. 116). (Fig. 6)</p>
</div>
<div class="pb" id="Page_27">27</div>
<div class="img" id="fig7">
<img src="images/pmg023.jpg" alt="" width="600" height="756" />
<p class="pcap">PARADOX BASIN, in southeastern Utah and southwestern Colorado,
showing the extent of common salt and major potash deposits
in the Paradox Member of the Hermosa Formation, and the salt
anticlines. Adapted from Hite (1972, fig. 1B). (Fig. 7)</p>
</div>
<div class="pb" id="Page_28">28</div>
<div class="img" id="fig8">
<img src="images/pmg024.jpg" alt="" width="1000" height="376" />
<p class="pcap">GEOLOGIC SECTION ACROSS NORTHWEST END OF ARCHES
NATIONAL PARK, showing strata beneath Courthouse syncline and
Salt Valley anticline. For line of section, see <a href="#fig9">figure 9</a>. Caprock
consists of gypsum and shale, from which common salt has been
leached by ground water, covered by alluvium. Heavy slanted lines
near crest of anticline are faults. Adapted from Hite and Lohman
(1973, fig. 13). (Fig. 8)</p>
</div>
<div class="img" id="fig9">
<img src="images/pmg025.jpg" alt="" width="600" height="553" />
<p class="pcap">INDEX MAP OF NORTHWESTERN PART OF ARCHES NATIONAL
PARK, showing axes of Courthouse syncline and Salt Valley anticline,
line of section <i>A</i>-<i>A</i>′ in <a href="#fig8">figure 8</a> and line of section <i>B</i>-<i>B</i>′ in
<a href="#fig10">figure 10</a>. Open circles along line of section are sites of test wells
for oil, gas, or potash. Adapted from Hite and Lohman (1973, fig. 12). (Fig. 9)</p>
</div>
<div class="pb" id="Page_29">29</div>
<p>Arches National Park and most of nearby Canyonlands
National Park lie within what geologists have termed the
“Paradox basin,” which contains a remarkable assemblage
of sediments called the Paradox Member of the Hermosa
Formation. These deposits were laid down in shallow seas
and lagoons during Middle Pennsylvanian time, roughly
300 million years ago (<a href="#fig59">fig. 59</a>). As indicated in <a href="#fig4">figure 4</a>,
the Paradox Member contains, in addition to shale and
limestone, minerals deposited by the evaporation and concentration
of sea water—common salt, gypsum, anhydrite,
and potash salts. For this reason such deposits are
<span class="pb" id="Page_30">30</span>
collectively called evaporites. <a href="#fig7">Figure 7</a> also shows that the
northeastern part of the Paradox basin, which is the
deepest part, contains a series of partly alined anticlines
which have cores of salt and, hence, are called salt anticlines.
As might be expected, roughly alined synclines
intervene between the anticlines, but are not shown because
of space limitations. According to Cater (1970, p. 50):
“The salt anticlines of Utah and Colorado are unique
in North America both in structure and in mode of development.”
To this may be added that they also are
relatively rare in the world.</p>
<p>A section across the Salt Valley anticline and the Courthouse
syncline in the northwestern part of the park is
shown in <a href="#fig8">figure 8</a>, and the axes of these structures are
shown in <a href="#fig9">figure 9</a>.</p>
<p>Normally, a series of roughly parallel northwestward-trending
folds would result from shortening of a segment
of the Earth’s crust by compressive forces from the northeast
and the southwest, but such does not seem to be
the origin of these folds. The folds occur in a relatively
narrow belt along the northeastern part of the Paradox
basin, the deepest part, which was broken by a series of
northwesterly trending normal faults (<a href="#fig6">fig. 6</a>) that cut the
deep-lying Precambrian and older Paleozoic rocks (<a href="#fig8">fig. 8</a>)
prior to the deposition of the salt-bearing Paradox Member
of the Hermosa Formation. Movement along these
faults continued intermittently during and after deposition
of the Paradox, however, and resulted in the formation
of a series of northwesterly trending ridges and
troughs. Following Paradox time, normal sediments derived
from a rising landmass to the northeast began to fill
the basin. These sediments accumulated most rapidly and
to greater thicknesses in the fault-derived troughs. Salt
differs from normal sediments in two properties critical
to the development of salt anticlines: first, salt is considerably
lighter (<a href="#fig10">fig. 10</a>), and, second, salt under pressure
will flow slowly by plastic deformation, much like ice in a
glacier flows slowly downstream. Thus, salt in the troughs
underlying the thicker and heavier masses of sediments
was squeezed into the adjoining ridges, causing them to
<span class="pb" id="Page_31">31</span>
rise. Once started, this process tended to be self-perpetuating,
as the flow of salt from beneath the thick masses
of sediments in the troughs made room for the accumulation
of still greater thicknesses of normal sediments. Consequently,
the troughs receiving most of the sediments
began to form downfolds, or synclines, and the ridges
receiving little or no normal sediments began to form huge
salt rolls that later were to become the cores of the salt
anticlines when finally the ridges too were buried by sediments.
Thus, the cross section (<a href="#fig8">fig. 8</a>) shows about 12,000
feet of the Paradox Member beneath the crest of the Salt
Valley anticline and only about 2,000 feet beneath the
Courthouse syncline. Near the middle of these structures
farther to the southeast, all the Paradox Member has been
squeezed out from beneath the bordering synclines.</p>
<div class="img" id="fig10">
<img src="images/pmg026.jpg" alt="" width="600" height="415" />
<p class="pcap">GRAVITY ANOMALIES OVER SALT VALLEY, along line <i>B-B′</i> shown
in <a href="#fig9">figure 9</a>, and relative densities and shapes of rock bodies beneath.
Densities are in grams per cubic centimeter. Gravity values
are in milligals, as shown. The standard acceleration of gravity is
980.665 centimeters per second per second; 1 gal is equal to 1
centimeter per second per second, and 1 milligal is one thousandth
of a gal. Modified from Case and Joesting (1972, fig. 2). (Fig. 10)</p>
</div>
<p>The general shape of the Salt Valley anticline is shown
also by cross-section <i>B-B′</i> (<a href="#fig10">fig. 10</a>), taken along the northeast-southwest
<span class="pb" id="Page_32">32</span>
line <i>B-B′</i> in <a href="#fig9">figure 9</a>, which is based upon
so-called gravity anomalies over Salt Valley. The lighter
Paradox Member, having an average density of 2.20, has a
lower gravitational attraction than the heavier rocks on
each side, which have an average density of 2.55.</p>
<p>By this time you are doubtless wondering why prominent
upfolds of the rocks, such as the Salt Valley anticline
and associated Cache Valley anticline and the Seven
Mile-Moab Valley anticline, now underlie relatively deep
valleys bordered by prominent ridges. The formation of
these valleys was not simple and involved many steps
extending over a considerable amount of geologic time, as
portrayed by Cater (1970, fig. 13; 1972, fig. 4). For a part
of the story, let us reexamine the cross section (<a href="#fig8">fig. 8</a>);
the rest of the story will be told in the section on “Uplift
and Erosion.”</p>
<p><a href="#fig8">Figure 8</a> shows that the unnamed upper member of the
Hermosa Formation and the overlying Cutler and Moenkopi
Formations are thickest beneath the Courthouse
syncline but wedge out against the flanks of the anticline.
Although the Chinle Formation and younger rocks appear
to extend across the fold, and may have extended across
this part of the fold, in Colorado all rocks older than the
Jurassic Morrison wedge out against the flanks of the
salt anticlines (Cater, 1970, p. 35) and also in the widest
part of the Salt Valley anticline southwest of the section
in <a href="#fig8">figure 8</a>. The salt anticlines were uplifted in a series of
pulses so that some formations either were not deposited
over the rising structures or were removed by erosion before
deposition of the next younger unit. By Morrison
time the supply of salt beneath the synclines seems to
have become used up; hence, the anticline stopped rising,
and the Morrison and younger formations were deposited
across the structures. Thus, in <a href="#fig4">figure 4</a>, the minimum
thickness of all units older than the Morrison is given
as zero. <a href="#fig4">Figure 4</a> shows the marine Mancos Shale to be
the youngest rock unit exposed in the park, but the Mesaverde
Group of Late Cretaceous age and possibly the
early Tertiary (<a href="#fig59">fig. 59</a>) Wasatch Formation may have
been deposited and later removed by erosion.</p>
<div class="pb" id="Page_33">33</div>
<h2 class="pcap" id="c9">Uplift And Erosion of The Plateau</h2>
<div class="img">
<img src="images/pmg027.jpg" alt="" width="500" height="205" />
</div>
<p>Next among the main events leading to the formation
of landforms in the park was the raising and additional
buckling and breaking of the Plateau by Earth
forces partly during the Late Cretaceous but mainly during
the early Tertiary. After uplift and deformation, the
Plateau was vigorously attacked by various forces of
erosion, and the rock materials pried loose or dissolved
were eventually carted away to the Gulf of California by
the ancestral Colorado River. Some idea of the enormous
volume of rock thus removed is apparent when one looks
down some 2,000 feet to the river from any of the high
overlooks farther south, such as Dead Horse Point (<a href="../../51048/51048-h/51048-h.htm#fig15">Lohman, 1974, fig. 15</a>).
Not so apparent, however, is the fact
that younger Mesozoic and Tertiary rocks more than 1
mile thick once overlaid this high plateau but have been
swept away by erosion. In all, the river has carried
thousands of cubic miles of sediment to the sea and is
still actively at work on this gigantic earth-moving project.
In an earlier report (Lohman, 1965, p. 42) I estimated
that the rate of removal may have been as great as about
3 cubic miles each century. For a few years the bulk of
the sediment was dumped into Lake Mead, but now Lake
Powell is getting much of it. When these and other reservoirs
ultimately become filled with sediment—for reservoirs
and lakes are but temporary things—the Gulf of
California will again become the burial ground.</p>
<p>According to Cater (1970, p. 65-67), who made an intensive
study of the salt anticlines, collapse of their crests
seemingly occurred in two stages—the first stage following
Late Cretaceous folding; the second following uplift
<span class="pb" id="Page_34">34</span>
of the Plateau later in the Tertiary. Solution and removal
of salt by ground water played the leading role in the
ultimate collapse.</p>
<div class="img" id="fig11">
<img src="images/pmg028.jpg" alt="" width="800" height="472" />
<p class="pcap">TILTED BLOCK OF ROCKS IN CACHE VALLEY GRABEN, viewed to
the east toward Cache Valley from point on gravelled side road to
Wolfe’s cabin, about half a mile east of paved road. Steep slope on
left composed of Jurassic Morrison Formation, hogback on top
formed by Dakota Sandstone of Late Cretaceous age, and gentle
slopes to right composed of the Mancos Shale of Late Cretaceous
age. (Fig. 11)</p>
</div>
<p>As shown by Dane (1935, pl. 1, p. 121-126), collapse
of the Salt Valley and Cache Valley anticlines was accompanied
by considerable faulting and jointing, particularly
along their northeast sides; by the upward intrusion
of two large areas of the Paradox Member of the Hermosa
Formation, one just northwest of the park and one in the
middle of Salt Valley south of the campground; and by
two downdropped masses of rock known to geologists as
grabens (pronounced gräbǝns)—one just northwest of
the park and one called the Cache Valley graben, which
extends both east and west from Salt Wash. The Cache
Valley graben has preserved from erosion the youngest
rock formations in the park, as shown in <a href="#fig11">figure 11</a>.</p>
<p>The remarkable jointing of the rocks on the northeast
limb of the Salt Valley anticline is shown in <a href="#fig12">figure 12</a>.
All the arches in this section of the park were eroded
through thin fins of the Slick Rock Member of the Entrada
<span class="pb" id="Page_35">35</span>
Sandstone, and some, like Broken Arch, <a href="#fig16">figure 16</a>,
are capped by the Moab Member.</p>
<p>Differences in the composition, hardness, arrangement,
and thickness of the rock layers determine their ability to
withstand the forces of fracturing and erosion and, hence,
whether they tend to form cliffs, ledges, fins, or slopes.
Most of the cliff- or ledge-forming rocks are sandstones
consisting of sand deposited by wind or water and later
cemented together by silica (SiO₂), calcium carbonate
(CaCO₃), or one of the iron oxides (such as Fe₂O₃), but
some hard, resistant ledges are made of limestone (calcium
carbonate). The rock column (<a href="#fig4">fig. 4</a>) shows in general
how these rock formations are sculptured by erosion and
how they protect underlying layers from more rapid erosion.
The nearly vertical cliffs along the lower reaches of
Salt and Courthouse Washes and the Colorado River
canyon upstream from Moab consist of the well-cemented
Wingate Sandstone protected above by the even harder
sandstones of the Kayenta Formation. (See figs. <a href="#fig21">21</a>, <a href="#fig22">22</a>.)
To borrow from an earlier report of mine (Lohman, 1965, p. 17),
“Vertical cliffs and shafts of the Wingate Sandstone
endure only where the top of the formation is capped
by beds of the next younger rock unit—the Kayenta
Formation. The Kayenta is much more resistant than the
Wingate, so even a few feet of the Kayenta * * * protect
the rock beneath.” In some places, as shown in figures <a href="#fig19">19</a>
and <a href="#fig20">20</a>, the overlying Navajo Sandstone makes up the
topmost unit of the cliff.</p>
<div class="pb" id="Page_36">36</div>
<div class="img" id="fig12">
<img src="images/pmg029.jpg" alt="" width="800" height="485" />
<p class="pcap">JOINTED NORTHEAST FLANK OF SALT VALLEY ANTICLINE, viewed
westward from an airplane. Light-colored wedge in middle background
is Salt Valley bordered on extreme left by Klondike Bluffs.
Dark-colored fins and pinnacles on left, of Slick Rock Member of
the Entrada Sandstone, form Devils Garden. Sharp pinnacle above
valley is the Dark Angel. (See <a href="#fig57">fig. 57</a>.) White bands of sandstone
extending to foreground are composed of Moab Member of the
Entrada. Note vegetation in the joints. Photograph by National Park
Service. (Fig. 12)</p>
</div>
<div class="pb" id="Page_37">37</div>
<p>Last but far from least among the factors responsible
for the grandeur of Arches National Park and the Plateau
in general is the desert climate, which allows one to see
virtually every foot of the vividly colored naked rocks,
and which has made possible the creation and preservation
of such a wide variety of fantastic sculptures. A wetter
climate would have produced a far different, smoother
landscape in which most of the rocks and land forms
would have been hidden by vegetation. On the Plateau
the vegetation grows mainly on the high mesas and the
narrow flood plains bordering the rivers, but scanty vegetation
also occurs on the gentle slopes or flats.</p>
<p>The combination of layers of sediments of different composition,
hardness and thickness, the bending and breaking
of the rocks, and the desert climate, has produced steep
slopes having many cliffs, ledges, and fins with generally
sharp to angular edges, rather than the subdued rounded
forms of more humid regions.</p>
<h2 class="pcap" id="c10">Origin And Development of The Arches</h2>
<div class="img">
<img src="images/pmg030.jpg" alt="" width="500" height="242" />
</div>
<p>Among the questions commonly asked by visitors
are, “How do arches form?”, “Why are some openings
called windows, others arches?”, “What is the difference,
if any, between arches or windows and natural bridges,
such as those at Natural Bridges National Monument?”,
and “How many arches are there in Arches National
Park?” Before taking up the origin and development of
arches, I shall attempt to explain the differences between
the three types of natural rock openings named above and
comment upon the number of arches.</p>
<div class="pb" id="Page_38">38</div>
<div class="img" id="fig13">
<img src="images/map2_lr.jpg" alt="" width="600" height="743" />
<p class="pcap">INDEX MAP, showing localities where
most of the photographs were taken.
Arrows point to distant views. Numbers
refer to figure numbers. (Fig. 13)<br /><span class="center"><a class="abl" href="images/map2_hr.jpg">High-resolution Map</a></span></p>
</div>
<div class="pb" id="Page_40">40</div>
<p>I believe most geologists and geographers are in general
agreement with Cleland (1910, p. 314) that “a ‘natural
bridge’ is a natural stone arch that spans a valley of
erosion. A ‘natural arch’ is a similar structure which, however,
does not span an erosion valley.” According to this
definition, Natural Bridges National Monument includes
three true bridges, whereas all the larger rock openings in
Arches National Park with which I am familiar are properly
termed “arches,” but some are called windows. If we
were to distinguish between arches and windows, we might
say that arches occur at or near the base of a rock wall,
as do the doors of a house or building, whereas windows
are found well above ground level. This distinction was
not followed in naming the rock openings in the park,
however; for example, Tunnel Arch (<a href="#fig14">fig. 14</a>) is considerably
higher above the ground than North Window (figs.
<a href="#fig37">37</a>, <a href="#fig38">38</a>) or South Window (<a href="#fig39">fig. 39</a>).</p>
<p>As to the number of arches in the park, I might begin
by saying that there is no universal agreement as to how
large a rock opening must be to qualify as an arch. The
pamphlet formerly handed to visitors entering the park
proclaimed that “Nearly 90 arches have been discovered,
and others are probably hidden away in remote and rugged
parts of the area,” but the average visitor probably
sees less than a third of this number.</p>
<p>David May, Assistant Chief of Interpretation and Resource
Management, Moab office of National Park Service
(oral commun., Oct. 1973), believes that if only those in
the park having a minimum dimension of 10 feet in any
one direction were considered to be arches, the number
would boil down to about 56 or 57. The most complete
count of arches and other openings in all of southeastern
Utah was made by Dale J. Stevens, Professor of Geography
at Brigham Young University, during the period
February through April 1973. He considered those with
openings of 3 feet or larger and found more than 300 in
southeastern Utah, of which 124 are in Arches National
Park, although he stated that several areas of the park
were not intensively searched because of time limitations
(written commun., July and Sept. 1973). The 124 arches
<span class="pb" id="Page_41">41</span>
and openings are distributed among the several named
areas of the park, as follows: Courthouse Towers, 13;
Herdina Park, 11; The Windows section, 25; Delicate Arch
area, 3; Fiery Furnace, 19; Devils Garden, 25; upper Devils
Garden (northwest of Devils Garden), 14; Eagle Park, 2;
and Klondike Bluffs, 12.</p>
<p>Professor Stevens generally used a range finder or a
steel tape to measure the width and height of the openings
and the width and thickness of the spans, but estimated
a few of the dimensions. In the text descriptions of
arches or captions of figures that follow, I am including
all or part of these measurements, without further acknowledgment.</p>
<p>All the arches in the park were formed in the Entrada
Sandstone, mainly in the Slick Rock Member but partly
in the Slick Rock and Dewey Bridge Members, and a few
in the Slick Rock Member occur not far beneath the base
of the overlying Moab Member. The sandstone of the
three members is composed mainly of quartz sand cemented
together by calcium carbonate (CaCO₃), which also
forms the mineral calcite and the rock known as limestone,
but the Dewey Bridge Member also contains beds
of sandy mudstone. Limestone and calcite are soluble in
acid, even in weak acid such as carbonic acid, HHCO₃,
also written H₂CO₃, formed by the solution of carbon dioxide
(CO₂) in water. Ground water, found everywhere in
rock openings at different depths beneath the land surface,
contains dissolved carbon dioxide derived from decaying
organic matter in soil, from the atmosphere, and
from other sources. Even rainwater and snow contain a
little carbon dioxide absorbed from the atmosphere—enough
to dissolve small amounts of limestone or of calcite
cement from sandstone. The calcite cement in the Entrada
and in many other sandstones is unevenly distributed,
however, so that all the cement is removed first
from places that contain the least amounts, and, once the
cement is dissolved away, the loose sand is carried away
by gravity, wind, or water.</p>
<p>Both nearly flat but slightly irregular beds of sandstone
and relatively thin walls or fins of sandstone are prime
<span class="pb" id="Page_42">42</span>
targets for this differential erosion. Potholes, as shown
in <a href="#fig18">figure 18</a><i>A</i>, may be formed in relatively flat beds by the
dissolving action of repeated accumulations of rainwater
or snowmelt, even in arid regions like the Plateau.</p>
<p>Relatively thin walls, or fins as they are called in parts
of the Plateau including Arches, are targets for the formation
of alcoves and caves by solution of cement and removal
of sand by gravity, wind, and water, aided by the
prying action of frost in joints, bedding planes, or other
openings. Once a breakthrough of a wall or fin occurs,
weakened chunks from the ceiling tend to fall, and natural
arches of various shapes and sizes are produced. Arches
form the strongest shapes for supporting overlying rock
loads, as the rock in the arch is compressed toward each
abutment by the heavy loads. Blocks of compressed rock
beneath a relatively flat ceiling tend to be dislodged also
by expansion due to release of pent-up pressure, until a
strong self-supporting arch is formed. Release of pent-up
pressure in rock walls may help also in initiating the
formation of alcoves or caves in cliff faces. Man, including
the ancient Greeks, Romans, Egyptians, and others, has
long made use of arches in building bridges, aqueducts,
temples, cathedrals, and other enduring edifices.</p>
<p>As vividly shown in <a href="#fig12">figure 12</a>, the Entrada Sandstone
on the northeast flank of the Salt Valley anticline has
been broken by Earth forces into thin slabs mostly 10 to
20 feet thick between nearly parallel joints, but, as will
be noted in the descriptions of individual arches, some
rock walls are only 1 or 2 feet thick, whereas others are
50 feet thick or more. Some weak or thin slabs have
weathered away, leaving the stronger or thicker ones as
towering fins, particularly in the Fiery Furnace and Devils
Garden areas. Jointing on a less spectacular scale also has
broken the Entrada in areas south of Salt Valley, leaving
walls or fins of rock.</p>
<div class="pb" id="Page_43">43</div>
<div class="img" id="fig14">
<img src="images/pmg033.jpg" alt="" width="600" height="833" />
<p class="pcap">TUNNEL ARCH, reached by short trail north of main trail through
Devils Garden. Opening is 26½ feet wide and 22 feet high; span
is about 14 feet thick. (Fig. 14)</p>
</div>
<div class="pb" id="Page_44">44</div>
<p>Although all the arches in the park were carved from
the Entrada Sandstone, slight differences in their mode of
origin or placement within the Entrada allow them to be
grouped into three classes: (1) vertical arches formed in
the Slick Rock Member alone or in the Slick Rock and
Moab Members, (2) vertical arches formed mainly in the
Slick Rock Member but partly in, and with the aid of,
the incompetent underlying Dewey Bridge Member, and
(3) horizontal arches, or so-called pothole arches, formed
from the union of a vertical pothole and a horizontal cave.
Hereinafter, the three members will be referred to alone,
without reference to the Entrada.</p>
<div class="img" id="fig15">
<img src="images/pmg034.jpg" alt="" width="721" height="600" />
<p class="pcap">“BABY ARCH,” just southwest of Sheep Rock in Courthouse Towers
area. For details, see text. (Fig. 15)</p>
</div>
<p>Before giving examples of arches in each of the three
classes, it is appropriate to remark that the arches and
other erosion forms in the park represent but a fleeting instant
in geologic time. Many of the pinnacles or piles of
rock may be the broken remains of former arches, and
many of the arches we see may be gone tomorrow, next
year, or a few hundreds of years and, certainly, before
many thousands of years. On the other hand, many new
arches will form by the processes described above as the
geologic clock ticks on.</p>
<div class="pb" id="Page_45">45</div>
<div class="img" id="fig16">
<img src="images/pmg035.jpg" alt="" width="800" height="484" />
<p class="pcap">BROKEN ARCH, reached by a ½-mile trail leading northward across
field that separates Fiery Furnace from Devils Garden. White thin-bedded
unit at top is the Moab Member, which rests upon the
massive salmon-colored Slick Rock Member. Opening is 59 feet
wide and 43 feet high. (Fig. 16)</p>
</div>
<div class="pb" id="Page_46">46</div>
<h3 id="c11">Examples of Arches</h3>
<p>Tunnel Arch (<a href="#fig14">fig. 14</a>) is a good example of an arch
eroded entirely within the massive Slick Rock Member.
Just southwest of Sheep Rock (<a href="#fig31">fig. 31</a>) is an unnamed
opening in the lower part of the Slick Rock Member
which I call “Baby Arch,” because it is one of the newest
ones visible from the park road (<a href="#fig15">fig. 15</a>). It is only 25½
feet wide and 14 feet high and penetrates a wall 14 feet
thick. Note that the breakthrough probably began along
the prominent recessed bedding plane at the base of the
arch. Its youthfulness is also indicated by the sharp,
angular breaks in the ceiling and by the pile of freshly
fallen rocks. Some visitors have asked park personnel why
they have not cleared away such debris! Despite its youthfulness,
the ceiling has already taken on the shape of
an arch.</p>
<p>Broken Arch (<a href="#fig16">fig. 16</a>) was formed near the top of the
Slick Rock Member and is strengthened and protected
by the more resistant overlying Moab Member, which
forms the upper half of the span. The crest is only 6 feet
thick at the thinnest point and is not broken as the name
seems to imply.</p>
<p>Double Arch (<a href="#fig17">fig. 17</a>), “one” of the most beautiful in
the park, is in The Windows section near the east end of
the road. The southeast arch, which is 160 feet wide and
105 feet high, is the second largest in the park, but the
west arch measures only 60 feet wide and 61 feet high. In
common with most arches in The Windows section, these
two arches of the Slick Rock Member rest upon bases of
the weak, easily eroded Dewey Bridge Member. More
rapid erosion of the Dewey Bridge undercut the arches
and hastened their development.</p>
<div class="pb" id="Page_47">47</div>
<div class="img" id="fig17">
<img src="images/pmg036.jpg" alt="" width="600" height="852" />
<p class="pcap">DOUBLE ARCH, in The Windows section. (Fig. 17)</p>
</div>
<div class="pb" id="Page_48">48</div>
<div class="img" id="fig18">
<img src="images/pmg037.jpg" alt="" width="800" height="571" />
<p class="pcap">PROBABLE STEPS IN FORMATION OF POTHOLE ARCH. <i>A</i>, Original
pothole probably formed in relatively level bed of sandstone, such
as this one, which is in an older rock unit—the White Rim Sandstone
Member of the Cutler Formation, a unit not present in Arches.
This pothole, which contains 4 feet of water, is in nearby Canyonlands
National Park (<a href="../../51048/51048-h/51048-h.htm#fig17">Lohman, 1974, fig. 17</a>), just north of the edge
of the White Rim, about 4½ miles north of the confluence of the
Green and Colorado Rivers. Photograph by E. N. Hinrichs. <i>B</i>, Pothole
is being deepened by solution while cliff is receding toward
pothole by weathering. <i>C</i>, As erosion continues, pothole and cave
in cliff face are growing deeper. <i>D</i>, Pothole Arch formed by union
of vertical pothole and horizontal cave. <i>E</i>, Telephoto view of Pothole
Arch from park road near stop 14. Visible span is 90 feet
across and 30 feet high. (Fig. 18)</p>
</div>
<div class="img">
<img src="images/pmg038.jpg" alt="Fig. 18 B" width="500" height="210" />
</div>
<div class="img">
<img src="images/pmg039.jpg" alt="Fig. 18 C" width="500" height="200" />
</div>
<div class="pb" id="Page_49">49</div>
<div class="img">
<img src="images/pmg040.jpg" alt="Fig. 18 D" width="500" height="201" />
</div>
<div class="img">
<img src="images/pmg041.jpg" alt="Fig. 18 E" width="800" height="568" />
</div>
<div class="pb" id="Page_50">50</div>
<p>The cause of the wavy bedding in the Dewey Bridge
Member, as shown in <a href="#fig17">figure 17</a> but as better shown in the
frontispiece, is not known for sure but generally is regarded
to be the result of irregular slumping during or
just after deposition of the sediments in a body of water,
caused by the weight of overlying sediments.</p>
<p>The last example I shall take up is Pothole Arch (<a href="#fig18">fig. 18</a>),
which differs from all the other examples in that this
arch is roughly horizontal rather than vertical. Most park
visitors, including me, were not aware of this interesting
feature until after publication of the pamphlet “The Guide
to an Auto Tour of Arches National Park,” which, as
previously noted, may be purchased at the Visitor Center.
Pothole Arch caps a ridge high above the road half a mile
northwest of Garden of Eden, so only those who happened
to look up at the right place were aware of its existence.</p>
<p>A different mode of origin than that given in the caption
for <a href="#fig18">figure 18</a> is depicted on a poster in the Visitor
Center, which shows the pothole being formed by a waterfall
having an apparent flow rate of several cubic feet per
second. Potholes can be formed in this manner in places
where sufficient streamflow is available, either continuously
or following rainstorms, but I believe the process
depicted in <a href="#fig18">figure 18</a> is a more likely mode of origin for
Pothole Arch.</p>
<h2 class="pcap" id="c12">How to See the Park</h2>
<div class="img">
<img src="images/pmg042.jpg" alt="" width="500" height="223" />
</div>
<p>As aptly stated on a poster in the Visitor Center,
how to see the park depends in part upon the question
“How long can you stay?” Inasmuch as the park entrance
and Visitor Center are beside a through U.S. Highway
(163), many motorists first become aware of the park’s
<span class="pb" id="Page_51">51</span>
existence from the entrance sign, and some take time for
at least a quick visit, such as a round trip to The Windows
section, which can be made in an hour or so.</p>
<p>For those who have or take more time and are able to
walk at least short distances, a visit of 1 or 2 days is a
very rewarding experience. Others, particularly avid
shutterbugs and those with camping gear, profitably
spend from several days to a week or more and hike all
or most of the trails.</p>
<p>Regardless of how long you plan to spend, I urge at
least a brief stop at the Visitor Center, where excellent
displays and a narrated slide show help materially in conveying
just what the park has to offer. At the counter you
can purchase a copy of “The Guide to an Auto Tour of
Arches National Park,” which explains the views from
each of 25 numbered stops along the park road, as well
as other reports describing arches or other parks and
monuments.</p>
<p>The park is open the year round, but, like most high
deserts, it gets rather hot in the summer and cold enough
in the winter for occasional snows and is sometimes closed
temporarily because of heavy snowfall. The weather generally
is ideal during the spring and fall. Even though
summer daytime temperatures may exceed 100°F (37.8°C)
and slow down hikers, the nights are cool enough for comfortable
sleeping beneath ample covers.</p>
<p>Before beginning our trip through the park proper, let
us consider a beautiful part many people fail to realize
actually belongs to the park—the Colorado River canyon
forming the southeastern boundary.</p>
<div class="img">
<img src="images/pmg043.jpg" alt="Petroglyph figure" width="500" height="212" />
</div>
<div class="pb" id="Page_52">52</div>
<h2 class="pcap" id="c13">A Trip Through The Park</h2>
<div class="img">
<img src="images/pmg044.jpg" alt="" width="500" height="257" />
</div>
<h3 id="c14">Colorado River Canyon</h3>
<p>The southeastern boundary of the park for
about 11 miles is the Colorado River, from the bridge on
which U.S. Highway 163 crosses the river to a point upstream
about half a mile below the mouth of Salt Wash.
Illuminated night float trips down part of this reach are
run during the summer, as noted on <a href="#Page_16">p. 16</a>. Partly paved
State Highway 128 follows the southeast side of the river
for about 30 miles to Dewey Bridge, then goes northward
about 15 miles to Cisco, where it connects with Highway
I-70.</p>
<p>The rocks of the Glen Canyon Group form the southernmost
corner of the park, as shown in <a href="#fig19">figure 19</a>. About 2
miles northeast of the bridge, we cross the axis of the
Courthouse syncline (<a href="#fig9">fig. 9</a>), which brings the Navajo
Sandstone down nearly to river level, as shown in <a href="#fig20">figure 20</a>.
The underlying Kayenta Formation is largely hidden
by vegetation and alluvial deposits in this view.</p>
<div class="pb" id="Page_53">53</div>
<div class="img" id="fig19">
<img src="images/pmg045.jpg" alt="" width="825" height="500" />
<p class="pcap">GLEN CANYON GROUP, forming southernmost point of park, as
viewed across the Colorado River from State Highway 128 half a
mile above Moab bridge carrying U.S. Highway 163. Massive sandstone
forming about the lower third of cliff is the Wingate Sandstone,
darker thin-bedded sandstones and mudstones forming
middle section of cliff comprise the Kayenta Formation, upper cliff is
the lower part of the Navajo Sandstone. Note that the saltcedar (tamarisk),
which lines both banks of the river, is in full bloom. (Fig. 19)</p>
</div>
<div class="pb" id="Page_54">54</div>
<div class="img" id="fig20">
<img src="images/pmg046.jpg" alt="" width="882" height="450" />
<p class="pcap">NAVAJO SANDSTONE CLIFFS, bordering west bank of Colorado River in Courthouse syncline, from State Highway 128
about 2 miles above the Moab bridge. Note rounded domes at top of cliff. (Fig. 20)</p>
</div>
<div class="pb" id="Page_55">55</div>
<div class="img" id="fig21">
<img src="images/pmg047.jpg" alt="" width="600" height="713" />
<p class="pcap">MOUTH OF SALT WASH, viewed across Colorado River from point
on State Highway 128, 11 miles above Moab bridge. Dark cliffs on
upper right and left are of Wingate Sandstone capped by thin protective
cover of resistant sandstone beds of the Kayenta Formation.
In background Wingate is overlain by entire Kayenta Formation and
lower part of the Navajo Sandstone. Wingate is underlain to river
level by weathered slope of the Chinle Formation. Water in Salt
Wash is largely backwater from the bankfull river; actual flow in
wash generally is much less but at times reaches flood proportions.
(Fig. 21)</p>
</div>
<p>About 11 miles above the Moab bridge is the mouth of
Salt Wash (<a href="#fig1">fig. 1</a>), as viewed from State Highway 128.
(See <a href="#fig21">fig. 21</a>.) Seventeen miles above the bridge (east of
area shown in <a href="#fig1">fig. 1</a>), we get an excellent view of the
southeast end of the highly faulted Cache Valley anticline,
as shown in <a href="#fig22">figure 22</a>. The background shown in the
<span class="pb" id="Page_56">56</span>
photograph formerly was the easternmost part of the
former monument, but when the monument graduated to
a park on November 16, 1971, this part of Cache Valley
along with most of Dry Mesa was withdrawn from the
park and put under the supervision of the Bureau of Land
Management, also a part of the Department of the
Interior.</p>
<div class="img" id="fig22">
<img src="images/pmg048.jpg" alt="" width="800" height="592" />
<p class="pcap">SOUTHEAST END OF FAULTED CACHE VALLEY ANTICLINE, viewed
northwestward across Colorado River from a point on State Highway
128, 17 miles above Moab bridge. High cliff of Wingate Sandstone
on left is capped by thin protective layer of the Kayenta
Formation. About upper third of slope below base of cliff is the
Chinle Formation, below which is the Moenkopi Formation extending
to high-water level. Note bent and broken beds on right.
(Fig. 22)</p>
</div>
<p>As noted on <a href="#Page_16">page 16</a>, part of “Run, Cougar, Run” was
filmed just upstream from the irrigated field in the foreground
of <a href="#fig22">figure 22</a>, in a wide part of the valley called
Professor Valley (<a href="#fig7">fig. 7</a>). This valley and the Richardson
Amphitheater on the southeast side of the river were
named after a Professor Richardson who settled in the
area in the 1880’s. The long abandoned townsite of
Richardson was 1¼ miles due east from the point from
which <a href="#fig22">figure 22</a> was taken.</p>
<div class="pb" id="Page_57">57</div>
<h3 id="c15">Headquarters Area</h3>
<p>The junction of the park road with U.S. Highway 163
is shown at the lower left of <a href="#fig23">figure 23</a>, and the entrance
station, Visitor Center, parking lot, and several buildings
are seen at the lower right. Several residences for park
personnel and other buildings are shown in <a href="#fig25">figure 25</a>. As
shown in the lower part of <a href="#fig23">figure 23</a>, the geology at the
park entrance is rather complex, as the park boundary
here is partly along the Moab fault and partly along a
branch fault—both in the Seven Mile-Moab Valley
anticline (<a href="#fig7">fig. 7</a>). The Moab fault extends northwestward
from Moab for more than 30 miles (McKnight, 1940,
p. 120, 121, pl. 1).</p>
<p>As shown in <a href="#fig23">figure 23</a>, soon after leaving the checking
station the park road begins to ascend the first of several
switchbacks, and cuts first into the Slick Rock Member,
then the Dewey Bridge Member, and finally the Navajo
Sandstone the rest of the way to and beyond the top of
the hill.</p>
<p>From points a mile or so up the hill may be seen interesting
features in several directions.<a class="fn" id="fr_5" href="#fn_5">[5]</a> The view to the
southwest is shown in <a href="#fig23">figure 23</a>, to the west are the Three
Penguins (<a href="#fig24">fig. 24</a>). A good view of the Moab Valley is
had by looking southeastward (<a href="#fig25">fig. 25</a>). A well in the
Navajo Sandstone at the base of the hill supplies water
to all the residences and to the Visitor Center, where a
drinking fountain and modern restrooms are available to
the public. Storage is provided by a steel tank hidden in a
ravine above the buildings shown in <a href="#fig25">figure 25</a>.</p>
<p>To the north the wall of Entrada Sandstone is cut by
a normal fault (<a href="#fig6">fig. 6</a>), as shown in <a href="#fig26">figure 26</a>.</p>
<div class="pb" id="Page_58">58</div>
<div class="img" id="fig23">
<img src="images/pmg049.jpg" alt="" width="800" height="552" />
<p class="pcap">FAULTED SEVEN MILE-MOAB VALLEY ANTICLINE. Top, View
toward the southwest from park road about 1 mile above entrance
station. Bottom, Geologic interpretation of photograph in part after
McKnight (1940, pl. 1). Moab fault and branch fault (both normal
faults, <a href="#fig6">fig. 6</a>) unite just beyond ridge of Slick Rock Member. Total
vertical displacement along both faults is about 2,500 feet. H.F.,
unnamed upper member of Hermosa Formation; M.F., Moenkopi
Formation; D, downthrown side of faults; U, upthrown side. Valley
fill and slope wash of recent (Holocene) age obscure faults and
underlying rocks. The original sequence of the rocks may be visualized
by placing the Navajo Sandstone, the upper part of which
is exposed at the lower right, on top of the Kayenta Formation, the
lower few feet of which cap and protect the cliffs of Wingate Sandstone
in the background. The Pacific Northwest (gas) Pipeline
mentioned on <a href="#Page_15">page 15</a> is buried beneath the slice of the Moenkopi
Formation between the two faults, which accounts for the disturbed
appearance of the rock. (Fig. 23)</p>
</div>
<div class="img">
<img src="images/pmg050.jpg" alt="Geologic interpretation of photograph" width="883" height="600" />
</div>
<div class="pb" id="Page_59">59</div>
<div class="img" id="fig24">
<img src="images/pmg051.jpg" alt="" width="616" height="600" />
<p class="pcap">THREE PENGUINS, viewed westward from park road about 1 mile
above entrance station. Penguins are carved in massive Slick Rock
Member seen resting upon thin-bedded Dewey Bridge Member.
(Fig. 24)</p>
</div>
<div class="pb" id="Page_60">60</div>
<div class="img" id="fig25">
<img src="images/pmg052.jpg" alt="" width="900" height="531" />
<p class="pcap">MOAB VALLEY, viewed southeastward from park road about 1 mile
above entrance station. Moab fault in about middle of valley, hidden
beneath recent (Holocene) valley fill and slope wash, separates
unnamed upper member of Hermosa Formation just above U.S.
Highway 163 on right from Navajo Sandstone forming hills on left
and ledges in foreground. Park Service residences at base of hill.
White patch bordering Colorado River on northwest is tailings pile
of Atlas Corporation’s uranium mill. Moab and Spanish Valley are
beyond river, and south end of La Sal Mountains forms distant
skyline. (Fig. 25)</p>
</div>
<div class="pb" id="Page_61">61</div>
<div class="img" id="fig26">
<img src="images/pmg053.jpg" alt="" width="800" height="583" />
<p class="pcap">FAULTED WALL OF ENTRADA SANDSTONE, north of park road
about 1 mile above entrance station. Fault is nearly vertical and
normal (<a href="#fig6">fig. 6</a>), but fault trace slopes steeply downward to right,
separating upthrown Slick Rock and Dewey Bridge Members on
left from downthrown Slick Rock Member on right. Light-colored
rock in foreground is Navajo Sandstone. Displacement probably
does not exceed 50 feet. (Fig. 26)</p>
</div>
<div class="pb" id="Page_62">62</div>
<div class="img" id="fig27">
<img src="images/pmg054.jpg" alt="" width="500" height="850" />
<p class="pcap">PARK AVENUE, viewed to the north along trail. (Fig. 27)</p>
</div>
<div class="pb" id="Page_63">63</div>
<h3 id="c16">Courthouse Towers Area</h3>
<p>About 2.3 miles from the entrance station is a turnoff
and parking area at the south end of the Park Avenue
trail (stop 2), which is about 1 mile long and ends at
another parking area 1.7 miles farther north. An interesting
hike is best made from south to north in a downhill
direction, and hikers generally meet the cars of relatives
or friends awaiting them at the northern parking area. The
trail begins in a canyon cut in the soft Dewey Bridge
Member and walled by high fins of the Slick Rock Member
(<a href="#fig27">fig. 27</a>), but farther north the canyon is floored by the
bare Navajo Sandstone. The avenue was named from the
resemblance of the east wall to a row of tall buildings.
Atop the west wall, just to the left of the view in
<a href="#fig27">figure 27</a>, are two balanced rocks (<a href="#fig28">fig. 28</a>). The one on the left,
which resembles somewhat the head of an Egyptian queen,
is offset to the right along a bedding plane, and this offset
may have been caused by an earthquake.</p>
<p>As we progress toward Courthouse Towers proper, lofty
fins and monoliths lie mostly on our left, and to the right
are fine distant views of the La Sal Mountains (stop 4).
A general view of the Courthouse Towers is shown in
<a href="#fig29">figure 29</a>, and closeups of two of the named rock sculptures—the
Three Gossips and Sheep Rock—are shown in
figures <a href="#fig30">30</a> and <a href="#fig31">31</a>. Just beyond Sheep Rock, which some
think resembles the Sphinx, we see “Baby Arch,” shown
in <a href="#fig15">figure 15</a>.</p>
<p>Five miles from the entrance station, the road crosses
Courthouse Wash on a modern bridge (stop 6)—a
distinct improvement over the two tracks in the sand we
used in 1946. The Courthouse syncline, named after the
wash, extends northwestward through here. (See figs. <a href="#fig8">8</a>,
<a href="#fig9">9</a>, <a href="#fig20">20</a>.) About a mile west of the bridge, Professor Stevens
found another pothole arch. A mile and a half north of the
bridge is stop 7, where attention is called in the booklet
to the vast area of “petrified dunes” east of the road,
which are simply dunelike exposures of the crossbedded
Navajo Sandstone formed originally by the cementation
of a vast area of sand dunes. My view of these was taken
about 1 mile beyond the stop (<a href="#fig32">fig. 32</a>).</p>
<div class="pb" id="Page_64">64</div>
<div class="img" id="fig28">
<img src="images/pmg055.jpg" alt="" width="600" height="845" />
<p class="pcap">BALANCED ROCKS ON SOUTH WALL OF PARK AVENUE, at south end of trail. (Fig. 28)</p>
</div>
<div class="pb" id="Page_65">65</div>
<div class="img" id="fig29">
<img src="images/pmg056.jpg" alt="" width="600" height="679" />
<p class="pcap">COURTHOUSE TOWERS, viewed to the northwest from point on
park road about three-fourths of a mile northeast of the south end
of Park Avenue trail. Sandstone towers are Slick Rock Member
resting on Dewey Bridge Member, which also forms foreground.
Three Gossips at upper left, Sheep Rock just beyond. The Organ
and Tower of Babel are on right. (Fig. 29)</p>
</div>
<div class="pb" id="Page_66">66</div>
<div class="img" id="fig30">
<img src="images/pmg057.jpg" alt="" width="547" height="801" />
<p class="pcap">THE THREE GOSSIPS, shown at upper left of <a href="#fig29">figure 29</a>. (Fig. 30)</p>
</div>
<div class="img" id="fig31">
<img src="images/pmg058.jpg" alt="" width="480" height="800" />
<p class="pcap">SHEEP ROCK, shown on center-left skyline in <a href="#fig29">figure 29</a>. (Fig. 31)</p>
</div>
<p>West of the road between the petrified dunes and The
Windows section, the Entrada Sandstone, particularly the
Dewey Bridge Member, has been weathered into grotesque
spires and pinnacles resembling the so-called “hoodoos and
goblins” in Goblin Valley State Park, just north of Hanksville,
Utah. Typical examples of “hoodoos and goblins” are
shown in <a href="#fig33">figure 33</a> (near stop 8). It seems reasonable to
assume that some of these spires are the skeletal remains
of former arch abutments. From here may be seen North
and South Windows and Turret Arch on the skyline to
the northeast (figs. <a href="#fig37">37</a>-<a href="#fig40">40</a>).</p>
<div class="pb" id="Page_67">67</div>
<div class="img" id="fig32">
<img src="images/pmg059.jpg" alt="" width="908" height="550" />
<p class="pcap">PETRIFIED SAND DUNES, looking northeast from park road 2.7
miles north of Courthouse Wash. The Navajo Sandstone was once
a huge sandpile of dunes laid down by winds during an arid interval,
so it is interesting to note that the irregularly weathered sandstone
once again resembles a pile of crossbedded dunes. See also
<a href="#fig35">figure 35</a>. (Fig. 32)</p>
</div>
<div class="pb" id="Page_68">68</div>
<div class="img" id="fig33">
<img src="images/pmg060.jpg" alt="" width="800" height="595" />
<p class="pcap">“HOODOOS AND GOBLINS,” weathered from Dewey Bridge Member,
viewed northwest from park road about 2½ miles north of Courthouse
Wash. (Fig. 33)</p>
</div>
<h3 id="c17">The Windows Section</h3>
<p>The Windows section, one of the most beautiful parts
of the park, once was the only readily accessible part of
the former monument and is still the only collection of
arches seen by many visitors who either do not have or do
not take time to travel farther north. All the arches and
erosion forms are on or near a high crest called Elephant
Butte (Dane, 1935, p. 126, 127), which separates Salt
Valley from the Courthouse syncline. The ridge also marks
the south edge of several minor anticlines and synclines
termed by Dane the “Elephant Butte folds.”</p>
<div class="pb" id="Page_69">69</div>
<div class="img" id="fig34">
<img src="images/pmg061.jpg" alt="" width="800" height="524" />
<p class="pcap">EYE OF THE WHALE, one of several arches in Herdina Park, just
south of jeep trail about 2 miles northwest of Balanced Rock. Cut
in Slick Rock Member. Front opening is 60 feet wide and 27 feet
high, but back opening is only 35 feet wide and 11 feet high. Photograph
by Professor Dale J. Stevens, Brigham Young University.
(Fig. 34)</p>
</div>
<p>Guarding the approach to The Windows section is
Balanced Rock (stop 9). As shown in the frontispiece, it
is accompanied on the right by another balanced rock and
a third one may be seen in the distance. The original route
to The Windows section, pioneered by Goulding, passed
just north of Balanced Rock. Traces of the old road between
here and the Garden of Eden parking area are still
visible but no longer used. To the west, however, a part
of the old road is the starting point of a jeep trail leading
northwestward through Herdina Park to a point near
Klondike Bluffs, where it joins the dirt road in Salt Valley
(<a href="#fig1">fig. 1</a>). Visitors having four-wheel-drive vehicles may
wish to drive at least as far as Eye of The Whale (<a href="#fig34">fig. 34</a>),
<span class="pb" id="Page_70">70</span>
which is about 2 miles northwest of Balanced Rock. There
are several picnic tables at the beginning of this jeep trail,
but no water.</p>
<div class="img" id="fig35">
<img src="images/pmg062.jpg" alt="" width="734" height="600" />
<p class="pcap">INTRICATE CROSSBEDS IN NAVAJO SANDSTONE, on north side
of road between Garden of Eden and Cove of Caves. Red crest is
basal part of Dewey Bridge Member. (Fig. 35)</p>
</div>
<p>Just beyond Balanced Rock, a branch paved road turns
eastward 2½ miles to the main parking lots in The
Windows section. Between the Garden of Eden (stop 13)
and Cove of Caves are spectacular exposures of the
Navajo Sandstone showing the crossbedding typical of the
original dunes (<a href="#fig35">fig. 35</a>). Just east of the crossbedded
Navajo Sandstone, shown in <a href="#fig35">figure 35</a>, we pass Cove Arch
and Cove of Caves (stop 10) on the north side of the
road (<a href="#fig36">fig. 36</a>).</p>
<p>Just around the curve east of Cove of Caves is the first
of two parking lots (stop 11) forming a one-way loop at
the end of this branch of the road. From the loop may be
seen the greatest concentration of readily accessible arches
<span class="pb" id="Page_71">71</span>
in the park, all of which are roofed by the Slick Rock
Member and floored by the Dewey Bridge Member. Let
us take the short paved trail from the upper lot to the
southeast, where we come first to North Window (<a href="#fig37">fig. 37</a>).
If we walk through this arch and climb the rock beyond
(<a href="#fig37">fig. 37</a> caption), we see one of the best views in the park
(<a href="#fig38">fig. 38</a>). A short walk south of North Window brings us
to South Window (<a href="#fig39">fig. 39</a>). The other side of this arch
may be reached either by walking around the nearby
southeast end of the fin or by walking through North
Window. A short walk to the southwest brings us to
Turret Arch—the one seen through North Window in
<a href="#fig38">figure 38</a>. <a href="#fig40">Figure 40</a> was taken from the southwest side
of Turret Arch, viewed northeastward toward South
Window, one corner of which appears at the left. Both
North and South Windows may be seen in one photograph
taken from points near Turret Arch.</p>
<div class="img" id="fig36">
<img src="images/pmg063.jpg" alt="" width="836" height="600" />
<p class="pcap">COVE ARCH AND COVE OF CAVES, on north side of road just west
of Double Arch and Parade of Elephants. Arch at left and three of
the caves on right are roofed by Slick Rock Member and floored by
Dewey Bridge Member. Arch is 48½ feet wide and 34 feet high.
In time the caves will eat through the 30-foot-thick fin and become
arches. Note sharp contact between Dewey Bridge Member and
Navajo Sandstone. (Fig. 36)</p>
</div>
<div class="pb" id="Page_72">72</div>
<div class="img" id="fig37">
<img src="images/pmg064.jpg" alt="" width="762" height="600" />
<p class="pcap">NORTH WINDOW, viewed to the northeast. Large rock seemingly
partly blocking left end of arch actually is the southeast end of a
fin some 50 feet or more beyond the arch, from
which <a href="#fig38">figure 38</a> was taken. Arch is 93 feet wide and 51 feet high. (Fig. 37)</p>
</div>
<p>From the lower parking lot (stop 12), a short walk by
paved trail takes us to spectacular Double Arch, shown in
<a href="#fig17">figure 17</a>. This arch is visible from the parking lot but is
best seen and photographed from at or near the end of the
trail. Looking westward from near the trail’s end, we see
the Parade of Elephants, shown in <a href="#fig41">figure 41</a>. This feature
is described on pages 16 and 17 of “The Guide to an Auto
Tour of Arches National Park” as “whimsical stone
statuary resembling a circus pachyderm parade. With tail
in trunk, the elephants rumble toward you along a sandstone
roadway.”</p>
<p>Ribbon Arch, on the north side of Elephant Butte, is one
of the most delicate ones in the park (<a href="#fig1">fig. 1</a>). Although it
is 50 feet wide and 55 feet high, the rock span is only
1½ feet wide and 1 foot thick.</p>
<div class="pb" id="Page_73">73</div>
<p>On the way back to the intersection with the main park
road, we pass stop 14, from which may be seen Pothole
Arch (<a href="#fig18">fig. 18</a>). One and one-half miles north of the intersection
with the main road is the Panorama Point parking
area (stop 15), which affords fine distant views of Salt
and Cache Valleys and points beyond. A roadside exhibit
portrays the gradual development of the Salt Valley anticline,
which supplements my description on pages <a href="#Page_27">27</a>-<a href="#Page_32">32</a>.
A parking space a short distance farther down the hill
(stop 16) provides good distant views of the Fiery Furnace.
I tried several telephoto shots from this viewpoint,
but preferred my closeup views, such as the one shown in
<a href="#fig44">figure 44</a>.</p>
<div class="img" id="fig38">
<img src="images/pmg065.jpg" alt="" width="710" height="600" />
<p class="pcap">LOOKING SOUTHWESTWARD THROUGH NORTH WINDOW, from
fin shown beyond left side of North Window in <a href="#fig37">figure 37</a>. Turret
Arch (<a href="#fig40">fig. 40</a>) is seen at right middle ground, south rim of Moab
Valley to left of arch, Colorado River canyon forms left skyline.
(Fig. 38)</p>
</div>
<div class="pb" id="Page_74">74</div>
<div class="img" id="fig39">
<img src="images/pmg066.jpg" alt="" width="600" height="612" />
<p class="pcap">SOUTH WINDOW, viewed toward northeast. Arch is 105 feet wide
and 66 feet high. See text. (Fig. 39)</p>
</div>
<h3 id="c18">Delicate Arch Area</h3>
<p>Two and a half miles northeast of the road intersection
near Balanced Rock, a gravelled side road leads northeastward
to several points of considerable interest. The
photograph in <a href="#fig11">figure 11</a> was taken from this side road
about half a mile northeast of the intersection. About 2
miles to the northeast, just beyond Salt Valley Wash, is
a parking area (stop 17) at the beginning of the trail past
Wolfe’s Bar-DX Ranch (<a href="#fig3">fig. 3</a>) to famed Delicate Arch,
which is featured on the front cover. Although the trail
to the arch is only 1½ miles long, it crosses several hills
at the outset, then climbs 500 feet, mostly on bare Entrada
Sandstone, so is considered quite strenuous, particularly
<span class="pb" id="Page_75">75</span>
in hot weather. The Park Service advises hikers to carry
water. The Walt Disney crew, cameras, gear, cougars, and
all climbed this trail in the hottest part of the summer of
1971 (see <a href="#Page_16">p. 16</a>), while my wife and I were working in
the vicinity. Visitors who do not wish to make the hike
may get a distant view of Delicate Arch by driving to a
parking area (stop 18) 1.3 miles farther east.</p>
<div class="img" id="fig40">
<img src="images/pmg067.jpg" alt="" width="600" height="612" />
<p class="pcap">TURRET ARCH, viewed northeast toward South Window, part of
which is visible on left. Small opening on right is visible also in
<a href="#fig38">figure 38</a>. Largest arch is 39 feet wide and 64 feet high; smaller
one is 12 feet wide and 13 feet high. A still smaller one, not visible
in the photograph, is 8 feet wide and only 4½ feet high. (Fig. 40)</p>
</div>
<div class="pb" id="Page_76">76</div>
<div class="img" id="fig41">
<img src="images/pmg068.jpg" alt="" width="900" height="522" />
<p class="pcap">PARADE OF ELEPHANTS, viewed west from end of trail to Double
Arch. Two elephants are on right, one on left. (Fig. 41)</p>
</div>
<div class="pb" id="Page_77">77</div>
<p>After leaving Wolfe’s Ranch, the trail to Delicate Arch
crosses Salt Wash on a suspension foot bridge (<a href="#fig42">fig. 42</a>).
Just beyond the bridge, a short walk to the left (north)
leads to the Ute petroglyphs shown in the lower photograph
of <a href="#fig2">figure 2</a>. The most difficult part of the trail, on
bare sandstone, is marked by cairns of stones placed at
sufficient intervals to keep hikers from losing the barely
visible trail. When the summit finally is reached and the
last corner rounded, one suddenly sees perhaps the most
sublime view in the park—famed Delicate Arch, framing
part of the La Sal Mountains beyond (<a href="#fig43">fig. 43</a>). This
graceful arch and mighty Landscape Arch (<a href="#fig53">fig. 53</a>) were
considered to be in serious jeopardy during the era of
sonic booms, but hopefully this danger now is past. (See
p. <a href="#Page_16">16</a>-<a href="#Page_17">17</a>.)</p>
<p>It may be of interest to shutterbugs that professional
photographer Hal Rumel lugged an 8- × 10-inch camera
plus a heavy tripod and accessories up the steep trail to
get the excellent photograph of Delicate Arch shown in
<a href="#fig43">figure 43</a>. The late afternoon sun intensified the red somewhat,
but my shots made earlier in the day using both
4- × 5-inch and 35-mm equipment resulted in unwanted
shadows, even though the salmon color of the Slick Rock
Member was more nearly normal.</p>
<p>After leaving the junction with the side road, the main
park road traverses slices of vertical strata squeezed between
faults along the north side of Salt Valley, then
gradually climbs out of the valley for about 2 miles to a
parking area (stop 19), from which good views are had of
the southeast end of Salt Valley and of the grabens in the
west end of Cache Valley. (See <a href="#fig11">fig. 11</a>.)</p>
<div class="img">
<img src="images/pmg069.jpg" alt="Petroglyph figure" width="400" height="140" />
</div>
<div class="pb" id="Page_78">78</div>
<div class="img" id="fig42">
<img src="images/pmg070.jpg" alt="" width="693" height="600" />
<p class="pcap">SUSPENSION FOOT BRIDGE ACROSS SALT WASH, in front of
Wolfe’s cabin at beginning of Delicate Arch trail. (Fig. 42)</p>
</div>
<div class="img" id="fig43">
<img src="images/pmg071.jpg" alt="" width="655" height="600" />
<p class="pcap">DELICATE ARCH, from end of trail 1½ miles above Wolfe’s Ranch.
The opening is 33 feet wide and 45 feet high. The left abutment
is only 5 feet wide at the narrowest point. The arch is carved near
the top of the Slick Rock Member, and the top of the span, 19
feet thick, is capped by a few feet of the more resistant Moab
Member, as is Broken Arch (<a href="#fig16">fig. 16</a>). Photograph by Hal Rumel,
Salt Lake City. (Fig. 43)</p>
</div>
<div class="pb" id="Page_79">79</div>
<h3 id="c19">Fiery Furnace</h3>
<p>About half a mile farther uphill is a parking area for
viewing the southeastern part of the Fiery Furnace (stop
20), a vast array of towering fins and pinnacles of the
reddish Slick Rock Member separated by narrow slots,
vaguely resembling flames shooting skyward. The view of
the Fiery Furnace in <a href="#fig44">figure 44</a> was taken about 1 mile
farther up the hill. It is not difficult to get lost among this
myriad of fins and narrow slots, so ranger-guided tours
are conducted during the summer.</p>
<p>About 1 mile farther northwest is a parking area (stop
23) from which a short walk to the north end of Fiery
Furnace leads to a narrow slot between high fins (<a href="#fig45">fig. 45</a>),
along which a short sandy trail leads to a recess along the
southwest wall containing Sand Dune Arch (<a href="#fig46">fig. 46</a>). This
hidden arch receives sunshine only near the middle of the
day and is a delightful, shady place to rest.</p>
<p>From the entrance to the slot leading to Sand Dune
Arch, a trail goes half a mile north across an open field to
Broken Arch, shown in <a href="#fig16">figure 16</a>. This field, which separates
the Fiery Furnace and Devils Garden areas, is seen
from the air in <a href="#fig12">figure 12</a>.</p>
<div class="img">
<img src="images/pmg072.jpg" alt="Petroglyph figure" width="300" height="281" />
</div>
<div class="pb" id="Page_80">80</div>
<div class="img" id="fig44">
<img src="images/pmg073.jpg" alt="" width="937" height="500" />
<p class="pcap">FIERY FURNACE, viewed northwest along park road about 1 mile northwest from stop 20. Fins and spires are of the jointed
Slick Rock Member (<a href="#fig12">fig. 12</a>), but the top of the Dewey Bridge Member is seen to the right of the curve in the road. (Fig. 44)</p>
</div>
<div class="pb" id="Page_81">81</div>
<div class="img" id="fig45">
<img src="images/pmg074.jpg" alt="" width="600" height="849" />
<p class="pcap">TRAIL TO SAND DUNE ARCH, looking northwest away from arch,
between towering fins of Slick Rock Member, at northwest end
of Fiery Furnace. Southeast end of Devils Garden in distance.
(Fig. 45)</p>
</div>
<div class="pb" id="Page_82">82</div>
<div class="img" id="fig46">
<img src="images/pmg075.jpg" alt="" width="760" height="600" />
<p class="pcap">SAND DUNE ARCH, in recess along southwest wall of narrow slot
shown in <a href="#fig45">figure 45</a>. Slick Rock Member. (Fig. 46)</p>
</div>
<h3 id="c20">Salt Valley and Klondike Bluffs</h3>
<p>Before proceeding to the end of the paved road, let us
take an unimproved side road, which turns south about a
third of a mile beyond the last stop, in order to see more
of Salt Valley and to visit Klondike Bluffs in the northwestern
part of the park. After descending 2.3 miles of
winding road we reach the normally dry bed of Salt Valley
Wash, and turn abruptly to the northwest. For the next
three-fourths of a mile the “road” is simply two tracks in
the loose, sandy bed of the wash, which obviously should
not be travelled when flooded or when there is even a
hint of rain. In dry weather, however, this road may be
travelled by ordinary passenger car. This stretch of the
wash cuts through an intruded block of the Paradox
Member of the Hermosa Formation consisting mainly of
gray and brown gypsum, the common salt having been
<span class="pb" id="Page_83">83</span>
dissolved out by ground water. Such an intrusive block of
salt-bearing rock is known to geologists as a diapir—not
to be confused with the garment (diaper) worn by
infants.</p>
<p>From here on the road traverses a rather uninteresting
stretch of valley north of Salt Valley Wash. Eleven miles
from the starting point, the road reaches an intersection
from which a side road leads southwestward three-fourths
of a mile to a parking area at the foot of Klondike Bluffs,
which form the south side of Salt Valley. From here, one
may make a strenuous hike over a primitive trail about
1½ miles long to beautiful Tower Arch (<a href="#fig47">fig. 47</a>).</p>
<p>The valley road continues northwestward from the intersection
to and beyond the northwest end of the park and
connects with roads to Crescent Junction, Thompson, and
the Yellow Cat mining district, north of the park (<a href="#Page_14">p. 14</a>).</p>
<p>Let us return to the paved road and continue our tour
of the park.</p>
<h3 id="c21">Devils Garden</h3>
<p>Turning left (northwest) at the intersection with the
paved park road, we enter Devils Garden—another large
maze of towering red fins separated by narrow slots, which
resembles the Fiery Furnace. After a third of a mile, we
reach stop 24 and walk 100 feet or more to the north for a
good view of Skyline Arch (<a href="#fig48">fig. 48</a>). This arch is very
appropriately named, as it forms the skyline viewed either
from the road on the south or from the campground on
the north, from points south of the amphitheater. Less
well known is the fact that Skyline Arch is clearly visible
to the naked eye or through binoculars from stretches
of Highway I-70 (or old U.S. Highways 6 and 50) about
11 miles to the north. Most arches and other erosion forms
do not change appearance much from day to day or year
to year, but some, like “Baby Arch” (<a href="#fig15">fig. 15</a>), show evidence
of relatively recent origin. In November 1940
(Abbey, 1971, p. 42) Skyline Arch suddenly doubled in size
by the fall of a large rock that occupied what is now the
northwest half of the arch. Photographs taken before and
after this event appear on pages 24 and 25 of the road
guide and also in the museum at the Visitor Center.</p>
<div class="pb" id="Page_84">84</div>
<div class="img" id="fig47">
<img src="images/pmg076.jpg" alt="" width="600" height="732" />
<p class="pcap">TOWER ARCH, on Klondike Bluffs, viewed eastward. Arch is in
Slick Rock Member but tower on left, after which arch was named,
is capped by a protective layer of the resistant Moab Member.
Opening is 88 feet wide and 43 feet high. Photograph by Robert D.
Miller. (Fig. 47)</p>
</div>
<div class="pb" id="Page_85">85</div>
<div class="img" id="fig48">
<img src="images/pmg077.jpg" alt="" width="897" height="550" />
<p class="pcap">SKYLINE ARCH, viewed north from point about 100 feet north of
stop 24, in Slick Rock Member. Although fins are vertical, note
that the strata seem to dip about 15° to the right, although the
actual dip is to the northeast. (See <a href="#fig50">fig. 50</a>.) (Fig. 48)</p>
</div>
<div class="pb" id="Page_86">86</div>
<p>Another half mile brings us to a one-way (to right) loop
at the end of the park road. Just beyond the beginning
of the loop is a parking lot and very attractive picnic
area containing several picnic tables shaded by piñon
pines at the foot of a towering red fin of the Slick Rock
Member. Just north of this picnic ground, a paved side
road leads eastward into a truly beautiful, well-equipped
campground comprising both back-in and drive-through
campsites for trailers, campers, or tents; three pairs of
modern restrooms, hydrants, and drinking fountains; and
an amphitheater, where illustrated campfire talks are
given nightly during the summer. The east end of the
campground is shown in <a href="#fig49">figure 49</a>.</p>
<div class="img" id="fig49">
<img src="images/pmg078.jpg" alt="" width="807" height="600" />
<p class="pcap">CAMPGROUND IN DEVILS GARDEN, viewed northwestward across
turn-around at southeastern end. (Fig. 49)</p>
</div>
<p>Devils Garden in general and the campground in particular
are on the crest of a ridge separating Salt Valley to
the southwest from the Sagers Wash syncline to the northeast,
which lies north of Yellow Cat Flat and north of the
<span class="pb" id="Page_87">87</span>
area shown in <a href="#fig1">figure 1</a>. From the higher parts of the campground
striking views are to be had toward the north and
northeast, particularly late in the afternoon, as shown in
<a href="#fig50">figure 50</a>.</p>
<div class="img" id="fig50">
<img src="images/pmg079.jpg" alt="" width="768" height="600" />
<p class="pcap">VIEW NORTH FROM CAMPGROUND, in late afternoon. Reddish
Slick Rock Member capped by light-colored Moab Member are
seen dipping northeastward toward Sagers Wash syncline. Book
Cliffs, north of Thompson, are 16 miles north on left skyline.
(Fig. 50)</p>
</div>
<p>In about the middle of the one-way loop at the end of
the park road is a well that supplies water to the campground
from early in the spring until the return of freezing
weather late in the fall. The well, which was drilled in
1962 to a depth of 900 feet, obtains a small amount of
water from the Wingate Sandstone. No water was found in
the overlying Navajo and Entrada Sandstones because of
the pronounced dip of the rocks toward the northeast,
which allows any water in these rocks to drain northeastward
(Ted Arnow, written commun., 1963). Water from
this well is pumped to a steel tank in a high part of the
<span class="pb" id="Page_88">88</span>
campground, whence it flows by gravity to the three sets
of restrooms.</p>
<div class="img" id="fig51">
<img src="images/pmg080.jpg" alt="" width="600" height="738" />
<p class="pcap">SOUTHEASTERN PART OF DEVILS GARDEN TRAIL, viewed northwestward.
Narrow slot between fins of Slick Rock Member indicates
local spacing of joints. (Fig. 51)</p>
</div>
<p>At the northwest end of the one-way loop is a large
parking area for use by people hiking the Devils Garden
trail. This trail leads to seven of the most interesting
arches in the park, all of which are in the Slick Rock
Member, and there are many more farther to the northwest.
The approximate distances to the seven arches are
given in the paragraphs that follow. The trail is paved
for about 1 mile as far as Landscape Arch (<a href="#fig53">fig. 53</a>), but
from there to Double O Arch (<a href="#fig56">fig. 56</a>) the trail is primitive,
and the Park Service recommends rubber soles as
part of the trail is on bare sandstone. For these reasons,
many visitors hike only as far as Landscape Arch.</p>
<div class="pb" id="Page_89">89</div>
<div class="img" id="fig52">
<img src="images/pmg081.jpg" alt="" width="600" height="825" />
<p class="pcap">PINE TREE ARCH, viewed northeastward. Opening is 46 feet wide
and 48 feet high. Fin is 30 feet thick. (Fig. 52)</p>
</div>
<div class="pb" id="Page_90">90</div>
<p>Much of the trail, particularly the first part, lies in a
narrow slot between fins of the Slick Rock Member, as
shown in <a href="#fig51">figure 51</a>. After about half a mile, a side trail
to the north leads to a <span class="ss">Y</span>, the right-hand fork of which
goes to Tunnel Arch (<a href="#fig14">fig. 14</a>). The left-hand fork leads to
Pine Tree Arch, obviously named for the piñon pine
framed by this arch (<a href="#fig52">fig. 52</a>).</p>
<p>At the end of the improved part of the trail, we reach
Landscape Arch (<a href="#fig53">fig. 53</a>), claimed by the Park Service to
be the longest known natural arch in the world. According
to Ouellette (1958) it is 291 feet long and 118 feet high,
but Professor Stevens’ measurements indicate it to be 287
feet long and 106 feet high. At its thinnest point on the
right, the span is only 11 feet wide and 11 feet thick. In
1958 three young men made what was claimed to be the
second known ascent of Landscape Arch, using ropes and
other climbing gear, after which they walked across (Ouellette,
1958). This crossing was made with the permission
of a park ranger, but such permission is no longer given,
for the safety of both the arch and of would-be climbers.</p>
<p>Wall Arch is about a quarter of a mile beyond the end
of the improved part of the trail, and another three-fourths
mile brings us to Navajo Arch (<a href="#fig54">fig. 54</a>) and Partition Arch
(<a href="#fig55">fig. 55</a>). A distant view of Partition Arch may be had
just before reaching Landscape Arch. Part of the remaining
trail to Double O Arch (<a href="#fig56">fig. 56</a>) is on the top of a low
sandstone fin, in part between somewhat higher fins and
in part above lower slots.</p>
<div class="pb" id="Page_91">91</div>
<div class="img" id="fig53">
<img src="images/pmg082.jpg" alt="" width="800" height="493" />
<p class="pcap">LANDSCAPE ARCH, viewed southwestward from near end of improved
part of Devils Garden trail. Note that ground beneath arch
is covered by slope wash and near the middle with what appears
to be a small landslide. Slick Rock Member here is more nearly
buff than salmon colored, because of a smaller content of iron
oxide. Fresh breaks and angular blocks of stone at right abutment
indicate relatively recent rock falls. See text for size. (Fig. 53)</p>
</div>
<div class="pb" id="Page_92">92</div>
<div class="img" id="fig54">
<img src="images/pmg083.jpg" alt="" width="742" height="600" />
<p class="pcap">NAVAJO ARCH, viewed northeastward from a branch of Devils Garden
trail. One of few arches having a flat soil-covered floor. Opening
is 40½ feet wide. Photograph by National Park Service. (Fig. 54)</p>
</div>
<p>Beautiful Double O Arch (<a href="#fig56">fig. 56</a>) is at the end of the
Devils Garden trail about 2½ miles northwest of the trailhead.
About half a mile northwest of the trail’s end is a
prominent landmark called Dark Angel (<a href="#fig57">fig. 57</a>), which is
visible in <a href="#fig12">figure 12</a> and from the unimproved road in Salt
Valley.</p>
<div class="pb" id="Page_93">93</div>
<div class="img" id="fig55">
<img src="images/pmg084.jpg" alt="" width="600" height="615" />
<p class="pcap">PARTITION ARCH, viewed southwestward from near Devils Garden
trail. Arch frames part of south wall of Salt Valley and, on skyline,
mesas south of Moab Valley. Opening is 27½ feet wide and 26 feet
high. A smaller opening to the right measures 8½ feet wide and
8 feet high. Photograph by Dawn E. Reed. (Fig. 55)</p>
</div>
<div class="img" id="fig56">
<img src="images/pmg085.jpg" alt="" width="853" height="600" />
<p class="pcap">DOUBLE O ARCH, viewed about north from northwest end of Devils
Garden trail. Large opening is 71 feet wide and 45 feet high; small
one at lower left is 21 feet wide and 11 feet high. Span of large
opening is 11 feet wide and 6 feet thick. Arch frames a part of the
Book Cliffs about 14 miles to the north. Photograph by Hildegard
Hamilton, Flagstaff, Ariz. (Fig. 56)</p>
</div>
<div class="pb" id="Page_94">94</div>
<div class="img" id="fig57">
<img src="images/pmg086.jpg" alt="" width="594" height="999" />
<p class="pcap">DARK ANGEL, a shaft of the Slick Rock Member that is an erosional
remnant of a once high, narrow fin. About one-half mile
northwest of Double O Arch. Photograph by National Park Service.
(Fig. 57)</p>
</div>
<div class="pb" id="Page_95">95</div>
<div class="img" id="fig58">
<img src="images/pmg087.jpg" alt="" width="692" height="600" />
<p class="pcap">“INDIAN-HEAD ARCH,” in upper Devils Garden. Arch and most of
head are in Slick Rock Member, top of head is basal part of Moab
Member. Opening is 4 feet wide and 4½ feet high. Photograph by
Professor Dale J. Stevens, Brigham Young University. (Fig. 58)</p>
</div>
<div class="pb" id="Page_96">96</div>
<div class="img" id="fig59">
<img src="images/pmg088.jpg" alt="" width="1000" height="816" />
<p class="pcap">GEOLOGIC TIME SPIRAL, showing the sequence, names,
and ages of the geologic eras, periods, and epochs, and the evolution
of plant and animal life on land and in the sea. The primitive
animals that evolved in the sea during the vast Precambrian Era
left few traces in the rocks because they had not developed hard
parts, such as shells, but hard shell or skeletal parts became
abundant during and after the Paleozoic Era. (Fig. 59)</p>
</div>
<div class="box">
<p class="center ccap">GEOLOGIC TIME
<br />The Age of the Earth</p>
<p class="pcap">The Earth is very old—4.5 billion years or more according to
recent estimates. Most of the evidence for an ancient Earth is contained
in the rocks that form the Earth’s crust. The rock layers
themselves—like pages in a long and complicated history—record
the surface-shaping events of the past, and buried within them are
traces of life—the plants and animals that evolved from organic
structures that existed perhaps 3 billion years ago.</p>
<p class="pcap">Also contained in rocks once molten are radioactive elements
whose isotopes provide Earth scientists with an atomic clock. Within
these rocks, “parent” isotopes decay at a predictable rate to form
“daughter” isotopes. By determining the relative amounts of parent
and daughter isotopes, the age of these rocks can be calculated.</p>
<p class="pcap">Thus, the results of studies of rock layers (stratigraphy), and of
fossils (paleontology), coupled with the ages of certain rocks as measured
by atomic clocks (geochronology), attest to a very old Earth!</p>
</div>
<div class="pb" id="Page_98">98</div>
<p>Professor Stevens found 14 arches in what he called
upper Devils Garden, northwest of Double O Arch, and
two arches in the northwesternmost extension of the park
known as Eagle Park (<a href="#fig1">fig. 1</a>). One of the unnamed arches
in upper Devils Garden is shown in <a href="#fig58">figure 58</a>. I am tentatively
calling it “Indian-Head Arch,” because of the rather
obvious resemblance.</p>
<p>This ends our journey through Arches National Park,
but there remains for consideration a summary of the
principal geologic events leading to the formation of this
beautiful part of the Colorado Plateau and a brief comparison
with the geology of other national parks and
monuments on the Plateau.</p>
<h2 class="pcap" id="c22">Summary of Geologic History</h2>
<div class="img">
<img src="images/pmg089.jpg" alt="" width="500" height="234" />
</div>
<p>Having finished our geologic trip through Arches
National Park, let us see how the arches and other features
fit into the bigger scheme of things—the geologic age
and events of the Earth as a whole, as depicted in
<a href="#fig59">figure 59</a>. As shown in <a href="#fig4">figure 4</a>, the rock strata still preserved
in the park range in age from Pennsylvanian to Cretaceous,
or from about 300 million to 100 million years old—a
span of about 200 million years. This seems an incredibly
long time, until one notes that the earth is some 4.5 billion
years old, and that our rock pile is but 1/23 or 4½ percent
of the age of the Earth as a whole. Thus, in <a href="#fig59">figure 59</a>, the
rocks exposed in the park occupy only about the left half
of the top whorl of the spiral.</p>
<p>But this is not the whole story. As indicated earlier,
younger Mesozoic and Tertiary rocks more than 1 mile
thick that once covered the area have been carried away
<span class="pb" id="Page_99">99</span>
by erosion, and if we include these the span is increased
to about 250 million years, or nearly a full whorl of
the spiral.</p>
<p>Deep tests for oil and gas tell us that much older rocks
underlie the area, and we have seen that some of these
played a part in shaping the park we see today. In addition
to the Precambrian igneous and metamorphic rocks,
there is about 2,000 feet of Paleozoic sedimentary rocks
older than the Pennsylvanian Paradox Member of the
Hermosa Formation, most of which was laid down in ancient
seas. This includes strata of Cambrian, Ordovician,
Devonian, Mississippian, and Pennsylvanian ages (<a href="#fig59">fig. 59</a>).
There are some gaps in the rock record caused by
temporary emergence of the land above sea level and
erosion of the land surface before the land again subsided
below sea level so that deposition could resume. Silurian
rocks are absent, presumably because, here, the Silurian
Period was dominated by erosion rather than deposition.</p>
<p>While Pennsylvanian and Permian rocks were being
laid down in and southwest of the park, a large area to
the northeast, called by geologists the Uncompahgre Highland
(because it occupied the same general area as part
of the present Uncompahgre Plateau), rose slowly above
sea level. Whatever Paleozoic rocks were on this rising
land plus part of the underlying Precambrian rocks were
eroded and carried by streams into deep basins to the
northeast and southwest. Thus, while some marine or near-shore
deposits were being laid down in and south of the
park, thousands of feet of red beds were being laid down
by streams between the park and what is now the Uncompahgre
Plateau. During part of Middle Pennsylvanian
time, a large area, including the park, known as the Paradox
basin, was alternately connected to or cut off from the
sea, so that the water was evaporated during cutoff periods
and replenished during periods when connection with
the sea resumed. In these huge evaporation basins were
deposited the salt and gypsum plus some potash salts and
shale that now make up the Paradox Member of the
Hermosa Formation.</p>
<p>Arches National Park contains four northwesterly trending
<span class="pb" id="Page_100">100</span>
major folds—the Salt Valley and Cache Valley salt
anticlines, the Courthouse syncline, and the faulted Moab-Seven
Mile anticline, which forms the southwestern border.
How these folds were formed was explained on pages <a href="#Page_27">27</a>-<a href="#Page_32">32</a>.
The history of their growth, however, was a long one
that began about 300 million years ago in the Pennsylvanian
and ended about 50 million years ago in the early
Tertiary. The growth of these folds occurred in two stages.
The first stage, which involved the development of the salt
cores of the anticlines, ended in the Jurassic with the
beginning of Morrison time; the second stage, which involved
additional folding that intensified the magnitude
and shape of existing folds, occurred in the early Tertiary
and was followed later by collapse of the salt anticlines.
The formation and collapse of the Salt Valley and Cache
Valley anticlines was accompanied by pronounced jointing
(<a href="#fig12">fig. 12</a>), which allowed differential erosion to produce the
tall fins in which the arches were formed.</p>
<p>The old Uncompahgre Highland continued to shed
debris into the bordering basins until Triassic time, when
it began to be covered by a veneer of red sandstone and
siltstone of the Chinle Formation (Lohman, 1965). The
area remained above sea level during the Triassic Period
and most, if not all, of the Jurassic Period, although the
Jurassic Carmel Formation was laid down in a sea that
lay just to the west.</p>
<p>Late in the Cretaceous Period a large part of Central
and Southeastern United States, including the eastern
half of Utah, sank beneath the sea and received thousands
of feet of mud, silt, and some sand that later compacted
into the Mancos Shale. This formation, as well as all
younger and some older strata, has long since been eroded
from most of the park area, but a little of the Mancos is
preserved in the Cache Valley graben (<a href="#fig11">fig. 11</a>), and the
entire Mancos Shale and younger rocks are present in
adjacent areas, such as the Book Cliffs north of Green
River, Crescent Junction, and Cisco (figs. <a href="#fig7">7</a>, <a href="#fig50">50</a>, <a href="#fig56">56</a>).</p>
<p>The land rose above the sea at about the close of the
Cretaceous and has remained above ever since, although
inland basins and lakes received sediment during parts
<span class="pb" id="Page_101">101</span>
of the Tertiary Period. Compressive forces in the Earth’s
crust produced some gentle folding of the strata at the
close of the Cretaceous, but more pronounced folding and
some faulting occurred during the Eocene Epoch, when
most of the Rocky Mountains took form. During the Miocene
Epoch igneous rock welled up into older rocks to
form the cores of the nearby La Sal, Abajo, and Henry
Mountains. Additional uplift and some folding occurred
in the Pliocene and Pleistocene Epochs.</p>
<p>Much of the course of the Colorado River was established
during the Miocene Epoch, with some additional
adjustments in the late Pliocene and early Pleistocene
Epochs (Hunt, C. B., 1969, p. 67). Erosion during much
of the Tertiary Period and all of the Quaternary Period
plus some sagging and breaking of the crest of the anticlines,
brought on by solution and lateral squeezing of salt
beds beneath the Moab-Seven Mile, Salt Valley, and
Cache Valley anticlines, combined to produce the landscape
as we now see it.</p>
<p>The Precambrian rocks beneath the area are about 1.5
billion years old; so an enormous span of time is represented
by the rocks and events in and beneath Canyonlands
National Park.</p>
<p>If we consider the geologic formations that make up the
national parks (N.P.), national monuments (N.M.) (excluding
small historical or archaeological ones), Monument
Valley, San Rafael Swell, and Glen Canyon National
Recreation Area, all in the Colorado Plateau, it becomes
apparent that certain formations or groups of formations
play starring roles in some parks or monuments, some play
supporting roles, and in a few places the entire cast of
rocks gets about equal billing. Let us compare them and
see how and where they fit into the “Geologic Time
Spiral” (<a href="#fig59">fig. 59</a>).</p>
<p>Dinosaur N.M., with exposed rocks ranging in age from
Precambrian to Cretaceous, covers the greatest time span
(nearly 2 billion years), but has one unit—the Jurassic
Morrison Formation—in the starring role, for this unit
contains the many dinosaur fossils that give the monument
its name and fame, although there are several older
<span class="pb" id="Page_102">102</span>
units in supporting roles. Grand Canyon N.P. and N.M.
are next, with rocks ranging in age from Precambrian
through Permian (excluding the Quaternary lava flows
in the N.M.), but here there is truly a team effort, for
the entire cast gets about equal billing. Canyonlands N.P.
stands third in this category, with rocks ranging from
Pennsylvanian to Jurassic, but we would have to give
top billing to the Permian Cedar Mesa Sandstone Member
of the Cutler Formation, from which The Needles, The
Grabens, and most of the arches were sculptured; the Triassic
Wingate Sandstone and the Triassic(?) Kayenta
Formation get second billing for their roles in forming and
preserving Island in the Sky and other high mesas.</p>
<p>Now let us consider other areas with only one or few
players in the cast, beginning at the bottom of the time
spiral. Black Canyon of the Gunnison N.M., cut entirely
in rocks of early Precambrian age with only a veneer of
much younger rocks, obviously has but one star in its
cast. Colorado N.M. contains rocks ranging from Precambrian
to Cretaceous—equal to Dinosaur in this respect,
but Colorado is unique in that all the rocks of the
long Paleozoic Era and some others are missing from the
cast; of those that remain, the Triassic Wingate and the
Triassic(?) Kayenta are the stars, with strong support
from the Jurassic Entrada Sandstone.</p>
<p>All the bridges in Natural Bridges N.M. were carved
from the Permian Cedar Mesa Sandstone Member of the
Cutler Formation, also one of the stars in Canyonlands
N.P. In Canyon de Chelly (pronounced dee shay) N.M.
and Monument Valley (neither a national park nor a
national monument, as it is owned and administered by
the Navajo Tribe), the De Chelly Sandstone Member of
the Cutler Formation—a Permian member younger than
the Cedar Mesa—plays the starring role.</p>
<p>Wupatki N.M. near Flagstaff, Ariz., stars the Triassic
Moenkopi Formation. Petrified Forest N.P. (which now
includes part of the Painted Desert) has but one star—the
Triassic Chinle Formation, in which are found many
petrified logs and stumps of ancient trees. The Triassic-Jurassic
Glen Canyon Group (<a href="#fig19">fig. 19</a>), which includes the
<span class="pb" id="Page_103">103</span>
Triassic Wingate Sandstone, the Triassic(?) Kayenta
Formation, and the Triassic(?)-Jurassic Navajo Sandstone,
receives top billing in recently enlarged Capitol Reef
N.P., but the Triassic Moenkopi and Chinle Formations
enjoy supporting roles.</p>
<p>The Triassic(?)-Jurassic Navajo Sandstone, which has
a supporting role in Arches N.P., is the undisputed star
of Zion N.P., Rainbow Bridge N.M., and Glen Canyon
National Recreation Area, despite the fact that the latter
is the type locality of the entire Glen Canyon Group. The
Navajo also forms the impressive reef at the east edge of
the beautiful San Rafael Swell, a dome, or closed anticline,
now crossed by Highway I-70 between Green River and
Fremont Junction, Utah.</p>
<p>As we journey upward in the time spiral (<a href="#fig59">fig. 59</a>), we
come to the Jurassic Entrada Sandstone, which stars in
Arches N.P., with help from the underlying Navajo Sandstone,
and a supporting cast of both older and younger
rocks. The Entrada also forms the grotesque erosion forms
called “hoodoos and goblins” in Goblin Valley State Park,
north of Hanksville, Utah.</p>
<p>Moving ever upward in the spiral, we come to the Cretaceous—the
age of the starring Mesaverde Group, in
which the caves of Mesaverde N.P. were formed, and
which now house beautifully preserved ruins once occupied
by the Anasazi, the same ancient people who once dwelt
in Arches N.P. and nearby areas.</p>
<p>This brings us up to the Tertiary Period, during the
early part of which the pink limestones and shales of the
Paleocene and Eocene Wasatch Formation were laid down
in inland basins. Beautifully sculptured cliffs, pinnacles,
and caves of the Wasatch star in Bryce Canyon N.P. and
in nearby Cedar Breaks N.M. This concludes our climb
up the time spiral, except for Quaternary volcanoes and
some older volcanic features at Sunset Crater N.M., near
Flagstaff, Ariz.</p>
<p>Thus, one way or another, many rock units formed
during the last couple of billion years have performed on
the stage of the Colorado Plateau and, hamlike, still lurk
in the wings eagerly awaiting your applause to recall them
<span class="pb" id="Page_104">104</span>
to the footlights. Don’t let them down—visit and enjoy
the national parks and monuments of the Plateau, for
they probably are the greatest collection of scenic wonderlands
in the world.</p>
<h2 class="pcap" id="c23">Additional Reading</h2>
<div class="img">
<img src="images/pmg090.jpg" alt="" width="500" height="192" />
</div>
<p>Many reports covering various aspects of the
area have been cited in the text by author and year, and
these plus a few additional ones are listed in “Selected
References.” A few works of general or special interest
should be mentioned, however.</p>
<p>Between 1926 and 1929 the entire area now included
in the park was mapped geologically in classic reports by
Dane (1935) and by McKnight (1940). These men and
their field assistants mapped the area by use of the plane-table
and telescopic alidade without benefit of modern
topographic maps or aerial photographs, except for topographic
maps of the narrow stretch along the Colorado
River mapped under the direction of Herron (1917). Only
small sections could be reached by automobile, so nearly
all the area was traversed using horses and mules or by
hiking. This work plus mapping done in nearby areas to
the south and to the north (Stokes, 1952) during the
uranium boom of the mid-fifties was used by Williams
(1964) in compiling a geologic map of the Moab quadrangle
at a scale of 1:250,000.</p>
<p>Several early reports on the Colorado River and its
potential utilization contain a wealth of information and
many fine photographs, including two by La Rue (1916,
1925) and one by Follansbee (1929).</p>
<p>You may be interested in brief accounts of the geology
of other national parks and monuments, or other areas of
special interest, such as the reports on the Uinta Mountains
by Hansen (1969), Mount Rainier by Crandell
<span class="pb" id="Page_105">105</span>
(1969), Yellowstone National Park by Keefer (1971),
and ones by me on
Colorado National Monument (Lohman, 1965) and Canyonlands National Park (<a href="../../51048/51048-h/51048-h.htm">1974</a>).</p>
<p>For those who wish to learn more about the science
of geology, I suggest the textbook by Gilluly, Waters, and
Woodford (1968).</p>
<h2 id="c24"><br /><span class="small">Acknowledgments</span></h2>
<p>I am greatly indebted to Bates Wilson, former
Superintendent, and to former Assistant Superintendent
Joe Carithers, for their splendid cooperation in supplying
data and information; to Chuck Budge, former Chief
Ranger; Dave May, Assistant Chief of Interpretation and
Resource Management; Joe Miller, former Maintenance
Engineer; Bob Kerr, new Superintendent; Maxine Newell,
Park Historian and member of the staff at Arches National
Park; Jerry Banta, former Park Ranger at Arches;
and Carl Mikesell, Park Ranger at Arches, for their many
favors.</p>
<p>I am grateful to several colleagues and friends for the
loan of photographs, for geologic help and data, and for
reviewing this report. I am also deeply grateful to my
wife, Ruth, for accompanying me on all the fieldwork
and for her help and encouragement.</p>
<h2 id="c25"><br /><span class="small">Selected References</span></h2>
<dl class="undent"><dt>Abbey, Edward, 1971, Desert solitaire, a season in the wilderness: New York, Ballantine Books, 303 p.</dt>
<dt>Baker, A. A., 1933, Geology and oil possibilities of the Moab district, Grand and San Juan Counties, Utah: U.S. Geol. Survey Bull. 841, 95 p.</dt>
<dt>Baker, Pearl, 1971, The Wild Bunch at Robbers Roost: New York, Aberlard-Schuman, 224 p.</dt>
<dt>Beckwith, Frank, 1934, A group of petroglyphs near Moab, Utah: Santa Fe, N. Mex., El Palacio, v. 36, p. 177-178.</dt>
<dt>Breed, Jack, 1947, Utah’s arches of stone: Natl. Geog. Mag., p. 173-192, August.</dt>
<dt>Case, J. E., and Joesting, H. R., 1972, Regional geophysical investigations in the central Colorado Plateau: U.S. Geol. Survey Prof. Paper 736, 34 p.</dt>
<dt class="pb" id="Page_106">106</dt>
<dt>Cater, F. W., 1970, Geology of the salt anticline region in southwestern Colorado: U.S. Geol. Survey Prof. Paper 637, 80 p.</dt>
<dt>—— 1972, Salt anticlines within the Paradox Basin, <i>in</i> Geologic atlas of the Rocky Mountain region, United States of America: Denver, Colo., Rocky Mtn. Assoc. of Geologists, p. 137, 138, fig. 4.</dt>
<dt>Cleland, H. F., 1910, North American natural bridges, with a discussion of their origins: Geol. Soc. America Bull., v. 21, p. 313-338.</dt>
<dt>Crandell, D. R., 1969, The geologic story of Mt. Rainier: U.S. Geol. Survey Bull. 1292, 43 p.</dt>
<dt>Dane, C. H., 1935, Geology of the Salt Valley anticline and adjacent areas, Grand County, Utah: U.S. Geol. Survey Bull. 863, 184 p.</dt>
<dt>Dellenbaugh, F. S., 1902, The romance of the Colorado River: New York, G. P. Putnam’s Sons, 399 p. [reprinted 1962 by Rio Grande Press, Chicago, Ill.]</dt>
<dt>Everhart, W. C., 1972, The National Park Service, Praeger Library of U.S. Government Departments and Agencies No. 13: New York, Praeger Publishers, p. i-xii, 1-276.</dt>
<dt>Follansbee, Robert, 1929, Upper Colorado River and its utilization: U.S. Geol. Survey Water-Supply Paper 617, 394 p.</dt>
<dt>Gilluly, James, Waters, A. C., and Woodford, A. O., 1968, Principles of geology [3d ed.]: San Francisco, W. R. Freeman & Co., 685 p.</dt>
<dt>Hansen, W. R., 1969, The geologic story of the Uinta Mountains [with graphics by John R. Stacy]: U.S. Geol. Survey Bull. 1291, 144 p.</dt>
<dt>Herron, W. R., 1917, Profile surveys in the Colorado River Basin in Wyoming, Utah, Colorado, and New Mexico: U.S. Geol. Survey Water-Supply Paper 396, 6 p., 43 pls.</dt>
<dt>Hite, R. J., 1972, Pennsylvanian rocks, <i>in</i> Geologic atlas of the Rocky Mountain region, United States of America: Denver, Colo., Rocky Mtn. Assoc. of Geologists, p. 133-137.</dt>
<dt>Hite, R. J., and Lohman, S. W., 1973, Geologic appraisal of Paradox basin salt deposits for waste emplacement: U.S. Geol. Survey open-file report, 75 p.</dt>
<dt>Hunt, Alice, 1956, Archeology of southeastern Utah, <i>in</i> Geology and economic deposits of east-central Utah: Salt Lake City, Intermountain Assoc. of Petroleum Geologists, 7th Ann. Field Conf., p. 13-18.</dt>
<dt>Hunt, C. B., 1956, Cenozoic geology of the Colorado Plateau: U.S. Geol. Survey Prof. Paper 279, 99 p.</dt>
<dt>—— 1969, Geologic history of the Colorado River, <i>in</i> The Colorado River region and John Wesley Powell: U.S. Geol. Survey Prof. Paper 669, p. I-IV, 59-130.</dt>
<dt class="pb" id="Page_107">107</dt>
<dt>Jennings, J. D., 1970, Canyonlands-Aborigines: Naturalist, v. 21, Summer, Special Issue no. 2, p. 10-15.</dt>
<dt>Joesting, H. R., Case, J. E., and Plouff, Donald, 1966, Regional geophysical investigations of the Moab-Needles area, Utah: U.S. Geol. Survey Prof. Paper 516-C, 21 p.</dt>
<dt>Keefer, W. R., 1971, The geologic story of Yellowstone National Park, illustrated by John R. Stacy: U.S. Geol. Survey Bull. 1347, 92 p. [1972].</dt>
<dt>Lansford, Henry, 1972, Boatman in the desert, a passenger-carrying sternwheeler in canyon country: “Empire” [magazine of the Denver Post], Nov. 5, p. 18, 19.</dt>
<dt>La Rue, E. C., 1916, Colorado River and its utilization: U.S. Geol. Survey Water-Supply Paper 395, 231 p.</dt>
<dt>—— 1925, Water power and flood control of Colorado River below Green River, Utah, with a foreword by Hubert Work, Secretary of the Interior, p. 1-100. [Appendix A, A report on water supply, by E. C. La Rue and G. F. Holbrook, p. 101-123; and Appendix B, A geologic report on the inner gorge of the Grand Canyon of Colorado River, by R. C. Moore, p. 125-171]: U.S. Geol. Survey Water-Supply Paper 556, 176 p.</dt>
<dt>Lohman, S. W., 1965, The geologic story of Colorado National Monument [with graphics by John R. Stacy]: Fruita, Colo., Colorado and Black Canyon Natural History Assoc., 56 p.</dt>
<dt>—— 1974, <a href="../../51048/51048-h/51048-h.htm">The geologic story of Canyonlands National Park</a>, with graphics by John R. Stacy: U.S. Geol. Survey Bull. 1327, 126 p.</dt>
<dt>McKnight, E. T., 1940, Geology of area between Green and Colorado Rivers, Grand and San Juan Counties, Utah: U.S. Geol. Survey Bull. 908, 147 p.</dt>
<dt>Ouellette, C. M., 1958, Over the top of Landscape Arch: Desert Mag., p. 13-16, March.</dt>
<dt>Pierson, Lloyd, 1960, Arches National Monument, <i>in</i> Geology of the Paradox basin fold and fault belt: Durango, Colo., Four Corners Geol. Soc. Guidebook, 3d Ann. Field Conf., p. 17-21.</dt>
<dt>Schaafsma, Polly, 1971, Rock art of Utah: Cambridge, Mass., Harvard Univ., Papers of the Peabody Museum of Archaeology and Ethnology, v. 65, 169 p.</dt>
<dt>Stacy, J. R., 1962, Shortcut method for the preparation of shaded-relief illustrations, <i>in</i> Short papers in geology, hydrology, and topography 1962: U.S. Geol. Survey Prof. Paper 450-D, p. D164-D165.</dt>
<dt>Stokes, W. L., 1952, Uranium-vanadium deposits of the Thompsons area, Grand County, Utah, with emphasis on the origin of carnotite ores: Utah Geol. and Mineralogical Survey Bull. 46, 51 p., December.</dt>
<dt class="pb" id="Page_108">108</dt>
<dt>—— 1970, Canyonlands—Geology: Naturalist, v. 21, Summer, Special Issue no. 2, p. 3-9.</dt>
<dt>Walters, H. H., 1956, Pacific Northwest Pipeline—The scenic inch, <i>in</i> Geology and economic deposits of east-central Utah: Salt Lake City, Intermountain Assoc. of Petroleum Geologists, p. 169-170.</dt>
<dt>Williams, P. L., 1964, Geology, structure, and uranium deposits of the Moab quadrangle, Colorado and Utah: U.S. Geol. Survey Misc. Geol. Inv. Map I-360.</dt>
<dt>Wilson, B. E., 1956, Arches National Monument, <i>in</i> Geology and economic deposits of east-central Utah: Salt Lake City, Intermountain Assoc. of Petroleum Geologists, 7th Ann. Field Conf., p. 50-51.</dt>
<dt>Wright, J. C., Shawe, D. R., and Lohman, S. W., 1962, Definition of members of the Jurassic Entrada Sandstone in east-central Utah and west-central Colorado: Bull. Am. Assoc. Petroleum Geologists, v. 46, no. 11, p. 2057-2070.</dt></dl>
<div class="img">
<img src="images/pmg091.jpg" alt="Petroglyph figure" width="500" height="429" />
</div>
<h2><br /><span class="small">Footnotes</span></h2>
<div class="fnblock"><div class="fndef"><a class="fn" id="fn_1" href="#fr_1">[1]</a>Mrs. Tanner, of Phoenix, Ariz., is the author of an earlier history of Moab
(her hometown). She has completed a revision entitled, “The Far Country—A
Regional History of Moab and La Sal, Utah,” which will be serialized in
the Moab Times-Independent, after which it will be published.
</div><div class="fndef"><a class="fn" id="fn_2" href="#fr_2">[2]</a>For the benefit of visitors from countries in which the metric system is
used, the following conversion factors may be helpful: 1 inch = 2.54 centimeters,
1 foot = 0.305 meter, 1 mile = 1.609 kilometers, 1 U.S. gallon = 0.00379
cubic meter.
</div><div class="fndef"><a class="fn" id="fn_3" href="#fr_3">[3]</a>Barrier Creek flows through Horseshoe Canyon in the detached unit of
Canyonlands National Park. The canyon walls are adorned by striking pictographs
(<a href="../../51048/51048-h/51048-h.htm#fig2">Lohman, 1974, fig. 2</a>). “Barrier Canyon style” is named after the
pictographs found in Horseshoe Canyon.
</div><div class="fndef"><a class="fn" id="fn_4" href="#fr_4">[4]</a>Plastic-relief maps are no longer available from the U.S. Army Map Service
but may be obtained from the T. N. Hubbard Scientific Co., Box 105,
Northbrook, Ill. 60062. A topographic map at a scale of 1:250,000 of the
Moab quadrangle and similar maps at a scale of 1:62,500 for the Thompson,
Cisco, Moab, and Castle Valley quadrangles are available from the U.S. Geological
Survey, Denver Distribution Section, Federal Center, Denver, Colo.
80225, from the Canyonlands Natural History Association at Moab, and from
privately owned shops where maps are sold. Most of the park is covered by the
Thompson and Moab quadrangles. The southern part of the park is shown also
on the Moab 4 NW, Moab 4 NE, and Mt. Waas 3 NW quadrangles at a scale
of 1:24,000. A special topographic map of Arches National Park at a scale of
1:50,000 is in preparation by the U.S. Geological Survey. These maps also
may be obtained from the above-listed sources.
</div><div class="fndef"><a class="fn" id="fn_5" href="#fr_5">[5]</a>This is numbered stop 1 in the booklet referred to earlier “The Guide to
an Auto Tour of Arches National Park,” and corresponds to the numeral one
on a small sign at the roadside parking place. Some of the other numbers are
given in the pages that follow.
</div>
</div>
<div class="pb" id="Page_109">109</div>
<h2 id="c26"><br /><span class="small">Index</span></h2>
<p class="center"><a href="#index_A" class="ab">A</a> <a href="#index_B" class="ab">B</a> <a href="#index_C" class="ab">C</a> <a href="#index_D" class="ab">D</a> <a href="#index_E" class="ab">E</a> <a href="#index_F" class="ab">F</a> <a href="#index_G" class="ab">G</a> <a href="#index_H" class="ab">H</a> <a href="#index_I" class="ab">I</a> <a href="#index_J" class="ab">J</a> <a href="#index_K" class="ab">K</a> <a href="#index_L" class="ab">L</a> <a href="#index_M" class="ab">M</a> <a href="#index_N" class="ab">N</a> <a href="#index_O" class="ab">O</a> <a href="#index_P" class="ab">P</a> <span class="ab">Q</span> <a href="#index_R" class="ab">R</a> <a href="#index_S" class="ab">S</a> <a href="#index_T" class="ab">T</a> <a href="#index_U" class="ab">U</a> <a href="#index_V" class="ab">V</a> <a href="#index_W" class="ab">W</a> <span class="ab">X</span> <a href="#index_Y" class="ab">Y</a> <a href="#index_Z" class="ab">Z</a></p>
<p class="center small">[Italic page numbers indicate major references]</p>
<dl class="index">
<dt class="center" id="index_A"><b>A</b></dt>
<dt class="jr">Page</dt>
<dt>Abajo Mountains<span class="jr"> <a href="#Page_101">101</a></span></dt>
<dd>artifacts<span class="jr"> <a href="#Page_9">9</a></span></dd>
<dt>Abbey, Edward<span class="jr"> <a href="#Page_3">3</a></span></dt>
<dt>Aborigines, occupation of area<span class="jr"> <a href="#Page_9">9</a></span></dt>
<dt>Acknowledgments<span class="jr"> <i><a href="#Page_105">105</a></i></span></dt>
<dt>Anasazi people, petroglyphs<span class="jr"> <a href="#Page_10">10</a></span></dt>
<dt>Anasazi ruins<span class="jr"> <a href="#Page_9">9</a>, <a href="#Page_103">103</a></span></dt>
<dt>Ancestral Colorado River<span class="jr"> <a href="#Page_33">33</a></span></dt>
<dt>Anomalies, gravity, Salt Valley<span class="jr"> <a href="#Page_32">32</a></span></dt>
<dt>Anticlines, salt<span class="jr"> <a href="#Page_31">31</a></span></dt>
<dt>Arches, broken remains<span class="jr"> <a href="#Page_44">44</a></span></dt>
<dd>examples<span class="jr"> <i><a href="#Page_46">46</a></i></span></dd>
<dd>former abutments<span class="jr"> <a href="#Page_68">68</a></span></dd>
<dd>horizontal<span class="jr"> <a href="#Page_44">44</a></span></dd>
<dd>how they are formed<span class="jr"> <a href="#Page_42">42</a></span></dd>
<dd>natural, defined<span class="jr"> <i><a href="#Page_40">40</a></i></span></dd>
<dd>number in the park<span class="jr"> <a href="#Page_40">40</a>, <i><a href="#Page_41">41</a></i></span></dd>
<dd>origin and development<span class="jr"> <a href="#Page_37">37</a></span></dd>
<dd>pothole<span class="jr"> <a href="#Page_44">44</a></span></dd>
<dd>vertical<span class="jr"> <a href="#Page_42">42</a>, <a href="#Page_44">44</a></span></dd>
<dt>Artifacts, La Sal and Abajo Mountains<span class="jr"> <a href="#Page_9">9</a></span></dt>
<dt>Aspinall, Wayne, Representative<span class="jr"> <a href="#Page_8">8</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_B"><b>B</b></dt>
<dt>“Baby Arch”<span class="jr"> <a href="#Page_46">46</a>, <a href="#Page_63">63</a>, <a href="#Page_83">83</a></span></dt>
<dt>Balanced Rock<span class="jr"> <a href="#Page_69">69</a>, <a href="#Page_70">70</a>, <a href="#Page_74">74</a></span></dt>
<dt>Banta, Jerry<span class="jr"> <a href="#Page_105">105</a></span></dt>
<dt>Bar-DX Ranch<span class="jr"> <a href="#Page_12">12</a>, <a href="#Page_13">13</a>, <a href="#Page_14">14</a></span></dt>
<dt>“Barrier Canyon style”<span class="jr"> <a href="#Page_10">10</a></span></dt>
<dt>Bedding, wavy, Dewey Bridge Member<span class="jr"> <a href="#Page_46">46</a></span></dt>
<dt>Beeson, Stib<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dt>Beginning of a monument<span class="jr"> <i><a href="#Page_1">1</a></i></span></dt>
<dt>Bending of rocks<span class="jr"> <i><a href="#Page_24">24</a></i></span></dt>
<dt>Bennett, Wallace F., Senator<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Beroni, Pete<span class="jr"> <a href="#Page_14">14</a>, <a href="#Page_15">15</a></span></dt>
<dt>Black Canyon of the Gunnison National Monument<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt>Book Cliffs<span class="jr"> <a href="#Page_100">100</a></span></dt>
<dt>Breaking of rocks<span class="jr"> <i><a href="#Page_24">24</a></i></span></dt>
<dt>Bridge, natural, defined<span class="jr"> <i><a href="#Page_40">40</a></i></span></dt>
<dt>Broken Arch<span class="jr"> <a href="#Page_46">46</a>, <a href="#Page_79">79</a></span></dt>
<dt>Brown-Stanton expedition, exploration<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Bryce Canyon National Park<span class="jr"> <a href="#Page_103">103</a></span></dt>
<dt>Budge, Chuck<span class="jr"> <a href="#Page_105">105</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_C"><b>C</b></dt>
<dt>Cache Valley<span class="jr"> <a href="#Page_56">56</a>, <a href="#Page_73">73</a>, <a href="#Page_77">77</a></span></dt>
<dt>Cache Valley anticline<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_32">32</a>, <a href="#Page_34">34</a>, <a href="#Page_55">55</a>, <a href="#Page_100">100</a>, <a href="#Page_101">101</a></span></dt>
<dt>Cache Valley graben<span class="jr"> <a href="#Page_34">34</a>, <a href="#Page_100">100</a></span></dt>
<dt>Campground<span class="jr"> <a href="#Page_86">86</a></span></dt>
<dd>water supply<span class="jr"> <a href="#Page_87">87</a></span></dd>
<dt>Cane Creek anticline<span class="jr"> <a href="#Page_24">24</a></span></dt>
<dt>Canyon de Chelly National Monument<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt><i>Canyon King</i><span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Canyon Lands Section, Colorado Plateau<span class="jr"> <a href="#Page_9">9</a>, <a href="#Page_22">22</a></span></dt>
<dt>Canyonlands National Park<span class="jr"> <a href="#Page_3">3</a>, <a href="#Page_9">9</a>, <a href="#Page_15">15</a>, <a href="#Page_102">102</a></span></dt>
<dt>Canyonlands Natural History Association<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Capitol Reef National Park<span class="jr"> <a href="#Page_103">103</a></span></dt>
<dt>Carithers, Joe<span class="jr"> <a href="#Page_105">105</a></span></dt>
<dt>Carmel Formation<span class="jr"> <a href="#Page_100">100</a></span></dt>
<dt>Cassidy, Butch<span class="jr"> <a href="#Page_12">12</a></span></dt>
<dt>Caves, Entrada Sandstone<span class="jr"> <a href="#Page_9">9</a></span></dt>
<dt>Cedar Breaks National Monument<span class="jr"> <a href="#Page_103">103</a></span></dt>
<dt>Cedar Mesa Sandstone Member, Cutler Formation<span class="jr"> <a href="#Page_22">22</a>, <a href="#Page_102">102</a></span></dt>
<dt>Chinle Formation<span class="jr"> <a href="#Page_32">32</a>, <a href="#Page_100">100</a>, <a href="#Page_102">102</a>, <a href="#Page_103">103</a></span></dt>
<dt>“Cisco Cutoff”<span class="jr"> <a href="#Page_16">16</a></span></dt>
<dt>Civilian Conservation Corps<span class="jr"> <a href="#Page_2">2</a></span></dt>
<dt>Cliff dwellers<span class="jr"> <a href="#Page_9">9</a></span></dt>
<dt>Climate, desert<span class="jr"> <a href="#Page_35">35</a>, <a href="#Page_51">51</a></span></dt>
<dd>wetter, different landscape produced<span class="jr"> <a href="#Page_37">37</a></span></dd>
<dt>Collapse, salt anticlines<span class="jr"> <a href="#Page_33">33</a>, <a href="#Page_34">34</a></span></dt>
<dt>Color photographs, equipment used<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Colorado National Monument<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt>Colorado Plateau, geologic formations included<span class="jr"> <a href="#Page_101">101</a></span></dt>
<dd>rock formations<span class="jr"> <a href="#Page_103">103</a>, <a href="#Page_104">104</a></span></dd>
<dd>subdivisions<span class="jr"> <a href="#Page_18">18</a></span></dd>
<dd>uranium-vanadium mining<span class="jr"> <a href="#Page_14">14</a></span></dd>
<dt>Colorado Plateaus Province<span class="jr"> <a href="#Page_18">18</a></span></dt>
<dt>Colorado River, course established<span class="jr"> <a href="#Page_101">101</a></span></dt>
<dd>nighttime illuminated float trip<span class="jr"> <a href="#Page_16">16</a>, <a href="#Page_52">52</a></span></dd>
<dt>Colorado River canyon<span class="jr"> <a href="#Page_35">35</a>, <a href="#Page_51">51</a>, <i><a href="#Page_52">52</a></i></span></dt>
<dt>Cores, salt<span class="jr"> <a href="#Page_100">100</a></span></dt>
<dt>Corral mine<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Courthouse syncline<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_30">30</a>, <a href="#Page_31">31</a>, <a href="#Page_32">32</a>, <a href="#Page_52">52</a>, <a href="#Page_63">63</a>, <a href="#Page_68">68</a>, <a href="#Page_100">100</a></span></dt>
<dt>Courthouse Towers area<span class="jr"> <a href="#Page_25">25</a>, <i><a href="#Page_63">63</a></i></span></dt>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dt>Courthouse Wash<span class="jr"> <a href="#Page_2">2</a>, <a href="#Page_3">3</a>, <a href="#Page_18">18</a>, <a href="#Page_35">35</a>, <a href="#Page_63">63</a></span></dt>
<dt>Cove Arch<span class="jr"> <a href="#Page_70">70</a></span></dt>
<dt>Cove of Caves<span class="jr"> <a href="#Page_70">70</a></span></dt>
<dt>Crossbedding, Navajo Sandstone<span class="jr"> <a href="#Page_63">63</a>, <a href="#Page_66">66</a>, <a href="#Page_70">70</a></span></dt>
<dt>Cutler Formation<span class="jr"> <a href="#Page_32">32</a>, <a href="#Page_102">102</a></span></dt>
<dd>Cedar Mesa Sandstone Member<span class="jr"> <a href="#Page_22">22</a></span></dd>
<dd>White Rim Sandstone Member<span class="jr"> <a href="#Page_22">22</a></span></dd>
</dl>
<div class="pb" id="Page_110">110</div>
<dl class="index">
<dt class="center" id="index_D"><b>D</b></dt>
<dt>Dark Angel<span class="jr"> <a href="#Page_92">92</a></span></dt>
<dt>De Chelly Sandstone Member, Cutler Formation<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt>Dead Horse Point<span class="jr"> <a href="#Page_33">33</a></span></dt>
<dt>Dedication of the park<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Delicate Arch<span class="jr"> <a href="#Page_16">16</a>, <a href="#Page_25">25</a>, <a href="#Page_74">74</a>, <a href="#Page_75">75</a>, <a href="#Page_77">77</a></span></dt>
<dt>Delicate Arch area, number of arches<span class="jr"> <a href="#Page_41">41</a></span></dt>
<dt>Density, average, Paradox Member<span class="jr"> <a href="#Page_32">32</a></span></dt>
<dt>Deposition of rock materials, environments<span class="jr"> <i><a href="#Page_20">20</a></i></span></dt>
<dt>Desert varnish<span class="jr"> <a href="#Page_10">10</a></span></dt>
<dt>Development of the arches<span class="jr"> <i><a href="#Page_37">37</a></i></span></dt>
<dt>Devils Garden<span class="jr"> <a href="#Page_2">2</a>, <a href="#Page_5">5</a>, <a href="#Page_25">25</a>, <a href="#Page_79">79</a>, <i><a href="#Page_83">83</a></i>, <a href="#Page_86">86</a></span></dt>
<dd>fins<span class="jr"> <a href="#Page_42">42</a></span></dd>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dd>trail<span class="jr"> <a href="#Page_88">88</a>, <a href="#Page_92">92</a></span></dd>
<dt>Dewey Bridge<span class="jr"> <a href="#Page_52">52</a></span></dt>
<dt>Dewey Bridge Member<span class="jr"> <a href="#Page_46">46</a>, <a href="#Page_63">63</a></span></dt>
<dd>Entrada Sandstone, composition<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dd class="ddt">“hoodoos and goblins”<span class="jr"> <a href="#Page_66">66</a></span></dd>
<dd class="ddt">park road cutting<span class="jr"> <a href="#Page_57">57</a></span></dd>
<dd class="ddt">The Windows section<span class="jr"> <a href="#Page_71">71</a></span></dd>
<dd class="ddt">vertical arches<span class="jr"> <a href="#Page_44">44</a></span></dd>
<dt>“Dewey Road”<span class="jr"> <a href="#Page_16">16</a></span></dt>
<dt>Diapir<span class="jr"> <a href="#Page_83">83</a></span></dt>
<dt>Differential erosion<span class="jr"> <a href="#Page_42">42</a></span></dt>
<dt>Dinosaur National Monument<span class="jr"> <a href="#Page_101">101</a>, <a href="#Page_102">102</a></span></dt>
<dt>Dissimilarity of Arches vs. Canyonlands<span class="jr"> <a href="#Page_23">23</a>, <a href="#Page_24">24</a></span></dt>
<dt>Double Arch<span class="jr"> <a href="#Page_2">2</a>, <a href="#Page_46">46</a>, <a href="#Page_72">72</a></span></dt>
<dt>Double O Arch<span class="jr"> <a href="#Page_90">90</a>, <a href="#Page_92">92</a>, <a href="#Page_98">98</a></span></dt>
<dt>Drainage, Arches National Park<span class="jr"> <a href="#Page_18">18</a></span></dt>
<dt>Dry Mesa<span class="jr"> <a href="#Page_5">5</a>, <a href="#Page_56">56</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_E"><b>E</b></dt>
<dt>Eagle Park<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_98">98</a></span></dt>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dt>Early dwellers<span class="jr"> <i><a href="#Page_9">9</a></i></span></dt>
<dt>Earthquake, rock offset along bedding plane<span class="jr"> <a href="#Page_63">63</a></span></dt>
<dt>Egyptian queen, arch resembling<span class="jr"> <a href="#Page_63">63</a></span></dt>
<dt>Eisenhower, Dwight D., Mission 66<span class="jr"> <a href="#Page_4">4</a></span></dt>
<dt>Elephant Butte<span class="jr"> <a href="#Page_72">72</a></span></dt>
<dt>Elephant Butte folds<span class="jr"> <a href="#Page_68">68</a></span></dt>
<dt>Elizondo, Emmett<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dt>Entrada Sandstone<span class="jr"> <a href="#Page_23">23</a>, <a href="#Page_74">74</a>, <a href="#Page_102">102</a>, <a href="#Page_103">103</a></span></dt>
<dd>arches, modes of origin<span class="jr"> <a href="#Page_42">42</a></span></dd>
<dd>caves<span class="jr"> <a href="#Page_9">9</a></span></dd>
<dd>cut by normal fault<span class="jr"> <a href="#Page_57">57</a></span></dd>
<dd>Moab Member<span class="jr"> <a href="#Page_24">24</a></span></dd>
<dd>no water found<span class="jr"> <a href="#Page_87">87</a></span></dd>
<dt>Environments of deposition<span class="jr"> <i><a href="#Page_20">20</a></i></span></dt>
<dt>Erosion<span class="jr"> <a href="#Page_99">99</a></span></dt>
<dd>Colorado Plateau<span class="jr"> <i><a href="#Page_33">33</a></i></span></dd>
<dt>Evaporation basins<span class="jr"> <a href="#Page_99">99</a></span></dt>
<dt>Evaporites<span class="jr"> <a href="#Page_30">30</a></span></dt>
<dt>Eye of The Whale<span class="jr"> <a href="#Page_69">69</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_F"><b>F</b></dt>
<dt>Facies changes<span class="jr"> <a href="#Page_22">22</a></span></dt>
<dt>“Father of the monument,” J. W. Williams<span class="jr"> <a href="#Page_1">1</a>, <a href="#Page_4">4</a></span></dt>
<dt>Faults, Cache Valley anticline<span class="jr"> <a href="#Page_34">34</a></span></dt>
<dd>Salt Valley anticline<span class="jr"> <a href="#Page_34">34</a></span></dd>
<dt>Fiery Furnace<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_42">42</a>, <a href="#Page_73">73</a>, <i><a href="#Page_79">79</a></i>, <a href="#Page_83">83</a></span></dt>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dt>Fins<span class="jr"> <a href="#Page_63">63</a>, <a href="#Page_79">79</a></span></dt>
<dt>Float trip, nighttime illuminated, down Colorado River<span class="jr"> <a href="#Page_52">52</a></span></dt>
<dt>Folds<span class="jr"> <i><a href="#Page_24">24</a></i>, <a href="#Page_30">30</a>, <a href="#Page_100">100</a></span></dt>
<dt>Four-wheel-drive vehicles<span class="jr"> <a href="#Page_69">69</a></span></dt>
<dt>Fractures<span class="jr"> <i><a href="#Page_24">24</a></i></span></dt>
<dt>Fremont people, occupation of area<span class="jr"> <a href="#Page_9">9</a></span></dt>
<dd>pictographs<span class="jr"> <a href="#Page_10">10</a></span></dd>
<dt>Frost, prying action<span class="jr"> <a href="#Page_42">42</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_G"><b>G</b></dt>
<dt>Garden of Eden<span class="jr"> <a href="#Page_50">50</a>, <a href="#Page_69">69</a>, <a href="#Page_70">70</a></span></dt>
<dt>Gas exploration, deep tests<span class="jr"> <a href="#Page_15">15</a>, <a href="#Page_99">99</a></span></dt>
<dt>Geographic setting<span class="jr"> <i><a href="#Page_18">18</a></i></span></dt>
<dt>Geologic age of rocks in park<span class="jr"> <i><a href="#Page_98">98</a></i></span></dt>
<dt>Geologic events forming the Colorado Plateau<span class="jr"> <i><a href="#Page_98">98</a></i></span></dt>
<dt>Geologic history, summary<span class="jr"> <i><a href="#Page_98">98</a></i></span></dt>
<dt>Geologic Time Spiral<span class="jr"> <a href="#Page_101">101</a>, <a href="#Page_103">103</a></span></dt>
<dt>Geology, at the park entrance<span class="jr"> <a href="#Page_57">57</a></span></dt>
<dt>Glen Canyon Group<span class="jr"> <a href="#Page_52">52</a>, <a href="#Page_102">102</a>, <a href="#Page_103">103</a></span></dt>
<dt>Glen Canyon National Recreation Area<span class="jr"> <a href="#Page_101">101</a>, <a href="#Page_103">103</a></span></dt>
<dt>Goblin Valley State Park<span class="jr"> <a href="#Page_66">66</a>, <a href="#Page_103">103</a></span></dt>
<dt>Gould, Lawrence M.<span class="jr"> <a href="#Page_1">1</a></span></dt>
<dt>Goulding, Harry, first person to drive into The Windows section<span class="jr"> <a href="#Page_2">2</a>, <a href="#Page_69">69</a></span></dt>
<dt>Grabens<span class="jr"> <a href="#Page_34">34</a></span></dt>
<dt>Grand Canyon National Park and National Monument<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt>Gravity anomalies, Salt Valley<span class="jr"> <a href="#Page_32">32</a></span></dt>
<dt>Green River<span class="jr"> <a href="#Page_103">103</a></span></dt>
<dt>Ground water<span class="jr"> <a href="#Page_41">41</a></span></dt>
<dt>“Guide to an Auto Tour of Arches National Park,” (The)<span class="jr"> <a href="#Page_5">5</a>, <a href="#Page_50">50</a>, <a href="#Page_51">51</a>, <a href="#Page_72">72</a></span></dt>
<dt>Gulf of California<span class="jr"> <a href="#Page_33">33</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_H"><b>H</b></dt>
<dt>Hastier, (Mrs.) Hazel Wolfe<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dt>Headquarters area<span class="jr"> <i><a href="#Page_57">57</a></i></span></dt>
<dt>Henry Mountains<span class="jr"> <a href="#Page_101">101</a></span></dt>
<dt>Herdina Park<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_69">69</a></span></dt>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dt>Hermosa Formation, Paradox Member<span class="jr"> <a href="#Page_23">23</a>, <a href="#Page_25">25</a>, <a href="#Page_29">29</a>, <a href="#Page_30">30</a>, <a href="#Page_32">32</a></span></dt>
<dt>History, early<span class="jr"> <i><a href="#Page_9">9</a></i></span></dt>
<dd>geologic, summary<span class="jr"> <i><a href="#Page_98">98</a></i></span></dd>
<dt>“Hoodoos and goblins”<span class="jr"> <a href="#Page_66">66</a>, <a href="#Page_103">103</a></span></dt>
<dt>Hoover, Herbert, proclamation<span class="jr"> <a href="#Page_1">1</a></span></dt>
<dt>Horizontal arches<span class="jr"> <a href="#Page_44">44</a></span></dt>
<dt>Horseshoe Canyon, pictographs<span class="jr"> <a href="#Page_10">10</a></span></dt>
<dt>Horseshoe Canyon Detached Unit of Canyonlands<span class="jr"> <a href="#Page_23">23</a></span></dt>
<dt>Humid regions, subdued rounded landforms<span class="jr"> <a href="#Page_37">37</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_I"><b>I</b></dt>
<dt>Igneous rocks<span class="jr"> <a href="#Page_22">22</a>, <a href="#Page_99">99</a></span></dt>
<dt>“Indian-Head Arch”<span class="jr"> <a href="#Page_98">98</a></span></dt>
<dt>Iron in the rocks<span class="jr"> <a href="#Page_23">23</a></span></dt>
<dt>Island in the Sky<span class="jr"> <a href="#Page_102">102</a></span></dt>
</dl>
<div class="pb" id="Page_111">111</div>
<dl class="index">
<dt class="center" id="index_J"><b>J</b></dt>
<dt>Jeep trail<span class="jr"> <a href="#Page_69">69</a>, <a href="#Page_70">70</a></span></dt>
<dt>Johnson, Lyndon B., proclamation<span class="jr"> <a href="#Page_2">2</a></span></dt>
<dt>Joints<span class="jr"> <i><a href="#Page_24">24</a></i>, <a href="#Page_34">34</a>, <a href="#Page_100">100</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_K"><b>K</b></dt>
<dt>Kayenta Formation<span class="jr"> <a href="#Page_35">35</a>, <a href="#Page_52">52</a>, <a href="#Page_102">102</a>, <a href="#Page_103">103</a></span></dt>
<dt>Kerr, Bob<span class="jr"> <a href="#Page_105">105</a></span></dt>
<dt>Klondike Bluffs<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_69">69</a>, <i><a href="#Page_82">82</a></i>, <a href="#Page_83">83</a></span></dt>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
</dl>
<dl class="index">
<dt class="center" id="index_L"><b>L</b></dt>
<dt>La Sal Mountains<span class="jr"> <a href="#Page_22">22</a>, <a href="#Page_63">63</a>, <a href="#Page_77">77</a>, <a href="#Page_101">101</a></span></dt>
<dd>artifacts<span class="jr"> <a href="#Page_9">9</a></span></dd>
<dt>Lake Mead<span class="jr"> <a href="#Page_33">33</a></span></dt>
<dt>Lake Powell<span class="jr"> <a href="#Page_33">33</a></span></dt>
<dt>Land forms, formation in the park<span class="jr"> <a href="#Page_33">33</a></span></dt>
<dt>Landscape Arch<span class="jr"> <a href="#Page_16">16</a>, <a href="#Page_77">77</a>, <a href="#Page_88">88</a></span></dt>
<dd>second known ascent<span class="jr"> <a href="#Page_90">90</a></span></dd>
<dt>Larson, Tommy<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dt>Lloyd, Sherman P., Representative<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Lohman, (Mrs.) Ruth<span class="jr"> <a href="#Page_105">105</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_M"><b>M</b></dt>
<dt>Mahan, Russel L.<span class="jr"> <a href="#Page_2">2</a></span></dt>
<dt>Mancos Shale<span class="jr"> <a href="#Page_32">32</a>, <a href="#Page_100">100</a></span></dt>
<dt>Maxwell, Ross A., investigation of caves<span class="jr"> <a href="#Page_9">9</a>, <a href="#Page_10">10</a></span></dt>
<dt>May, David<span class="jr"> <a href="#Page_40">40</a>, <a href="#Page_105">105</a></span></dt>
<dt>Melich, Mitchell, Solicitor General<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Mesaverde Group<span class="jr"> <a href="#Page_32">32</a>, <a href="#Page_103">103</a></span></dt>
<dt>Mesaverde National Park<span class="jr"> <a href="#Page_103">103</a></span></dt>
<dt>Metamorphic rocks<span class="jr"> <a href="#Page_22">22</a>, <a href="#Page_99">99</a></span></dt>
<dt>Metric unit conversion factors<span class="jr"> <i><a href="#Page_2">2</a></i></span></dt>
<dt>Mikesell, Carl<span class="jr"> <a href="#Page_105">105</a></span></dt>
<dt>Miller, Joe<span class="jr"> <a href="#Page_105">105</a></span></dt>
<dt>Mission 66, presidential and congressional support<span class="jr"> <a href="#Page_4">4</a></span></dt>
<dt>Mississippi River sternwheeler replica<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Moab, uranium-vanadium mill<span class="jr"> <a href="#Page_14">14</a></span></dt>
<dt>Moab bridge<span class="jr"> <a href="#Page_52">52</a></span></dt>
<dt>Moab Canyon<span class="jr"> <a href="#Page_15">15</a>, <a href="#Page_18">18</a></span></dt>
<dt>Moab fault<span class="jr"> <a href="#Page_26">26</a>, <a href="#Page_57">57</a></span></dt>
<dt>Moab Lions Club<span class="jr"> <a href="#Page_1">1</a>, <a href="#Page_8">8</a></span></dt>
<dt>“Moab Mail Road”<span class="jr"> <a href="#Page_16">16</a></span></dt>
<dt>Moab Member, Entrada Sandstone<span class="jr"> <a href="#Page_24">24</a>, <a href="#Page_35">35</a></span></dt>
<dd>Entrada Sandstone, Broken Arch<span class="jr"> <a href="#Page_46">46</a></span></dd>
<dd>composition<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dt>“Moab panel”<span class="jr"> <a href="#Page_10">10</a></span></dt>
<dt>Moab-Spanish Valley anticline<span class="jr"> <a href="#Page_26">26</a></span></dt>
<dt>Moab Valley<span class="jr"> <a href="#Page_57">57</a></span></dt>
<dt>Moab Valley-Seven Mile anticline<span class="jr"> <a href="#Page_100">100</a>, <a href="#Page_101">101</a></span></dt>
<dt>Moenkopi Formation<span class="jr"> <a href="#Page_32">32</a>, <a href="#Page_102">102</a>, <a href="#Page_103">103</a></span></dt>
<dt>Monoliths<span class="jr"> <a href="#Page_63">63</a></span></dt>
<dt>Monument, beginning<span class="jr"> <i><a href="#Page_1">1</a></i></span></dt>
<dt>Monument Valley<span class="jr"> <a href="#Page_101">101</a>, <a href="#Page_102">102</a></span></dt>
<dt>Morrison Formation<span class="jr"> <a href="#Page_32">32</a>, <a href="#Page_101">101</a></span></dt>
<dt>Morton, Rogers C. B., Secretary of the Interior<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Moss, Frank E., Senator<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Moss Back Member, Chinle Formation<span class="jr"> <a href="#Page_15">15</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_N"><b>N</b></dt>
<dt><a id="xnps">National Park Service</a><span class="jr"> <a href="#Page_8">8</a>, <a href="#Page_12">12</a>, <a href="#Page_40">40</a>, <a href="#Page_75">75</a>, <a href="#Page_90">90</a></span></dt>
<dt>Natural Bridges National Monument<span class="jr"> <a href="#Page_3">3</a>, <a href="#Page_37">37</a>, <a href="#Page_40">40</a>, <a href="#Page_102">102</a></span></dt>
<dt>Navajo Arch<span class="jr"> <a href="#Page_90">90</a></span></dt>
<dt>Navajo Sandstone<span class="jr"> <a href="#Page_24">24</a>, <a href="#Page_35">35</a>, <a href="#Page_52">52</a>, <a href="#Page_103">103</a></span></dt>
<dd>canyon floor<span class="jr"> <a href="#Page_63">63</a></span></dd>
<dd>crossbedding<span class="jr"> <a href="#Page_63">63</a>, <a href="#Page_66">66</a>, <a href="#Page_70">70</a></span></dd>
<dd>park road cutting<span class="jr"> <a href="#Page_57">57</a></span></dd>
<dd>water supply<span class="jr"> <a href="#Page_57">57</a>, <a href="#Page_87">87</a></span></dd>
<dt>Navajo Tribe<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt>Needles section, The, Canyonlands National Park<span class="jr"> <a href="#Page_16">16</a>, <a href="#Page_102">102</a></span></dt>
<dt>Newell, (Mrs.) Maxine<span class="jr"> <a href="#Page_12">12</a>, <a href="#Page_105">105</a></span></dt>
<dt>Nixon, Richard M., Congressional Bill<span class="jr"> <a href="#Page_5">5</a></span></dt>
<dt>North Window<span class="jr"> <a href="#Page_40">40</a>, <a href="#Page_68">68</a>, <a href="#Page_71">71</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_O"><b>O</b></dt>
<dt>Oil exploration<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dd>Cane Creek anticline<span class="jr"> <a href="#Page_24">24</a></span></dd>
<dd>deep tests<span class="jr"> <a href="#Page_99">99</a></span></dd>
<dt>Origin of the arches<span class="jr"> <i><a href="#Page_37">37</a></i></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_P"><b>P</b></dt>
<dt>Pacific Northwest Pipeline<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Painted Desert<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt>Panorama Point<span class="jr"> <a href="#Page_73">73</a></span></dt>
<dt>Parade of Elephants<span class="jr"> <a href="#Page_72">72</a></span></dt>
<dt>Paradox basin<span class="jr"> <a href="#Page_23">23</a></span></dt>
<dt>Paradox Member, Hermosa Formation<span class="jr"> <a href="#Page_23">23</a>, <a href="#Page_25">25</a>, <a href="#Page_29">29</a>, <a href="#Page_30">30</a>, <a href="#Page_82">82</a>, <a href="#Page_99">99</a></span></dt>
<dd>Hermosa Formation, average density<span class="jr"> <a href="#Page_32">32</a></span></dd>
<dd class="ddt">upward intrusion<span class="jr"> <a href="#Page_34">34</a></span></dd>
<dt>Park, a trip through<span class="jr"> <i><a href="#Page_52">52</a></i></span></dt>
<dd>dedication<span class="jr"> <a href="#Page_8">8</a></span></dd>
<dd>how to see<span class="jr"> <i><a href="#Page_50">50</a></i></span></dd>
<dd>improvements<span class="jr"> <a href="#Page_4">4</a></span></dd>
<dt>Park Avenue, trail<span class="jr"> <a href="#Page_63">63</a></span></dt>
<dt>Park Service. <i>See</i> <a href="#xnps">National Park Service</a>.</dt>
<dt>Partition Arch<span class="jr"> <a href="#Page_90">90</a></span></dt>
<dt>Petrified dunes<span class="jr"> <a href="#Page_63">63</a>, <a href="#Page_66">66</a></span></dt>
<dt>Petrified Forest National Park<span class="jr"> <a href="#Page_102">102</a></span></dt>
<dt>Petroglyphs, Ute<span class="jr"> <a href="#Page_10">10</a>, <a href="#Page_75">75</a></span></dt>
<dt>Pictographs, Fremont people<span class="jr"> <a href="#Page_10">10</a></span></dt>
<dt>Pine Tree Arch<span class="jr"> <a href="#Page_90">90</a></span></dt>
<dt>Piñon pines<span class="jr"> <a href="#Page_86">86</a></span></dt>
<dt>Pipeline scars, Pacific Northwest Pipeline<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Plateau, uplift and erosion<span class="jr"> <i><a href="#Page_33">33</a></i></span></dt>
<dt>Potash occurrence<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Pothole Arch<span class="jr"> <a href="#Page_50">50</a>, <a href="#Page_73">73</a></span></dt>
<dt>Pothole arches<span class="jr"> <a href="#Page_44">44</a></span></dt>
<dt>Powell, John Wesley, Canyonlands National Park<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Professor Valley<span class="jr"> <a href="#Page_56">56</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_R"><b>R</b></dt>
<dt>Rainbow Bridge National Monument<span class="jr"> <a href="#Page_103">103</a></span></dt>
<dt>Rainwater<span class="jr"> <a href="#Page_41">41</a>, <a href="#Page_42">42</a></span></dt>
<dt>Rampton, Calvin L., Utah Governor<span class="jr"> <a href="#Page_8">8</a></span></dt>
<dt>Reading, additional<span class="jr"> <i><a href="#Page_104">104</a></i></span></dt>
<dt>References, selected<span class="jr"> <i><a href="#Page_105">105</a></i></span></dt>
<dt class="pb" id="Page_112">112</dt>
<dt>Relief map, shaded, Arches National Park, described<span class="jr"> <a href="#Page_18">18</a>, <a href="#Page_19">19</a></span></dt>
<dt>Ribbon Arch<span class="jr"> <a href="#Page_72">72</a></span></dt>
<dt>Richardson Amphitheater<span class="jr"> <a href="#Page_56">56</a></span></dt>
<dt>Richardson, Professor<span class="jr"> <a href="#Page_56">56</a></span></dt>
<dt>Rico Formation<span class="jr"> <a href="#Page_23">23</a></span></dt>
<dt>Rison, (Mrs.) Esther Stanley<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dt>Rock formations, sculptured by erosion<span class="jr"> <a href="#Page_35">35</a></span></dt>
<dt>Rock openings, natural, types<span class="jr"> <a href="#Page_37">37</a></span></dt>
<dt>Rock types in the park<span class="jr"> <a href="#Page_35">35</a></span></dt>
<dt>Roosevelt, Franklin D., proclamation<span class="jr"> <a href="#Page_2">2</a></span></dt>
<dt>Rumel, Hal, photographer<span class="jr"> <a href="#Page_77">77</a></span></dt>
<dt>“Run, Cougar, Run”<span class="jr"> <a href="#Page_16">16</a>, <a href="#Page_56">56</a>, <a href="#Page_75">75</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_S"><b>S</b></dt>
<dt>Sagers Wash syncline<span class="jr"> <a href="#Page_86">86</a></span></dt>
<dt>Salt, occurrence<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dd>properties critical to formation of salt anticlines<span class="jr"> <a href="#Page_30">30</a></span></dd>
<dt>Salt anticlines<span class="jr"> <a href="#Page_30">30</a>, <a href="#Page_31">31</a>, <a href="#Page_100">100</a></span></dt>
<dd>collapse<span class="jr"> <a href="#Page_33">33</a>, <a href="#Page_34">34</a></span></dd>
<dt>Salt-bearing rock<span class="jr"> <a href="#Page_83">83</a></span></dt>
<dt>Salt rolls<span class="jr"> <a href="#Page_31">31</a></span></dt>
<dt>Salt Valley<span class="jr"> <a href="#Page_2">2</a>, <a href="#Page_68">68</a>, <a href="#Page_73">73</a>, <a href="#Page_77">77</a>, <i><a href="#Page_82">82</a></i>, <a href="#Page_83">83</a>, <a href="#Page_92">92</a></span></dt>
<dd>gravity anomalies<span class="jr"> <a href="#Page_32">32</a></span></dd>
<dt>Salt Valley anticline<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_30">30</a>, <a href="#Page_31">31</a>, <a href="#Page_32">32</a>, <a href="#Page_73">73</a>, <a href="#Page_100">100</a>, <a href="#Page_101">101</a></span></dt>
<dd>collapse<span class="jr"> <a href="#Page_34">34</a></span></dd>
<dd>fins<span class="jr"> <a href="#Page_42">42</a></span></dd>
<dt>Salt Valley Wash<span class="jr"> <a href="#Page_3">3</a>, <a href="#Page_74">74</a>, <a href="#Page_82">82</a>, <a href="#Page_83">83</a></span></dt>
<dt>Salt Wash<span class="jr"> <a href="#Page_35">35</a>, <a href="#Page_55">55</a></span></dt>
<dd>Anasazi ruins<span class="jr"> <a href="#Page_9">9</a></span></dd>
<dd>drainage<span class="jr"> <a href="#Page_18">18</a></span></dd>
<dd>grabens<span class="jr"> <a href="#Page_34">34</a></span></dd>
<dd>sandstone caves near<span class="jr"> <a href="#Page_10">10</a></span></dd>
<dt>Salt Wash Sandstone Member, Morrison Formation<span class="jr"> <a href="#Page_14">14</a></span></dt>
<dt>San Juan Basin, natural gas<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>San Rafael Swell<span class="jr"> <a href="#Page_101">101</a>, <a href="#Page_103">103</a></span></dt>
<dt>Sand Dune Arch<span class="jr"> <a href="#Page_79">79</a></span></dt>
<dt>Sandstone fins<span class="jr"> <a href="#Page_41">41</a>, <a href="#Page_42">42</a></span></dt>
<dt>Schaafsma, Polly, quoted<span class="jr"> <a href="#Page_10">10</a>, <a href="#Page_12">12</a></span></dt>
<dt>Scenic drive, Moab to Cisco<span class="jr"> <a href="#Page_16">16</a></span></dt>
<dt>“Scenic Inch,” Pacific Northwest Pipeline<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Sedimentary rocks<span class="jr"> <a href="#Page_20">20</a></span></dt>
<dd>modes of deposition<span class="jr"> <a href="#Page_99">99</a></span></dd>
<dt>Seven Mile-Moab Valley anticline<span class="jr"> <a href="#Page_26">26</a>, <a href="#Page_32">32</a>, <a href="#Page_57">57</a></span></dt>
<dt>Sevenmile Canyon<span class="jr"> <a href="#Page_15">15</a></span></dt>
<dt>Sheep Rock<span class="jr"> <a href="#Page_63">63</a></span></dt>
<dt>Skyline Arch<span class="jr"> <a href="#Page_83">83</a></span></dt>
<dt>Slick Rock Member, Entrada Sandstone<span class="jr"> <a href="#Page_34">34</a></span></dt>
<dd>Entrada Sandstone, composition<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dd class="ddt">high fins and pinnacles<span class="jr"> <a href="#Page_63">63</a>, <a href="#Page_79">79</a>, <a href="#Page_86">86</a></span></dd>
<dd class="ddt">hiking trail between fins<span class="jr"> <a href="#Page_90">90</a></span></dd>
<dd class="ddt">park road cutting<span class="jr"> <a href="#Page_57">57</a></span></dd>
<dd class="ddt">salmon<span class="jr"> <a href="#Page_77">77</a></span></dd>
<dd class="ddt">The Windows section<span class="jr"> <a href="#Page_71">71</a></span></dd>
<dd class="ddt">Tunnel Arch<span class="jr"> <a href="#Page_46">46</a></span></dd>
<dd class="ddt">vertical arches<span class="jr"> <a href="#Page_42">42</a>, <a href="#Page_44">44</a></span></dd>
<dt>Slumping of sediments, irregular<span class="jr"> <a href="#Page_50">50</a></span></dt>
<dt>Snow<span class="jr"> <a href="#Page_41">41</a>, <a href="#Page_51">51</a></span></dt>
<dt>Sonic booms, dangers posed to arches<span class="jr"> <a href="#Page_16">16</a>, <a href="#Page_17">17</a></span></dt>
<dt>South Window<span class="jr"> <a href="#Page_40">40</a>, <a href="#Page_68">68</a>, <a href="#Page_71">71</a></span></dt>
<dt>Spanish explorers<span class="jr"> <a href="#Page_12">12</a></span></dt>
<dd>introduction of horses to this country<span class="jr"> <a href="#Page_10">10</a></span></dd>
<dt>Squaw Flat Campground<span class="jr"> <a href="#Page_16">16</a></span></dt>
<dt>Stanley, Esther<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dd>(Mrs.) Flora<span class="jr"> <a href="#Page_13">13</a></span></dd>
<dd>Volna<span class="jr"> <a href="#Page_13">13</a></span></dd>
<dt>Stevens, Dale J.<span class="jr"> <a href="#Page_40">40</a>, <a href="#Page_41">41</a>, <a href="#Page_63">63</a>, <a href="#Page_90">90</a>, <a href="#Page_98">98</a></span></dt>
<dt>Strata, lateral changes across the park<span class="jr"> <a href="#Page_22">22</a></span></dt>
<dt>Sundance Kid<span class="jr"> <a href="#Page_12">12</a></span></dt>
<dt>Sunset Crater National Monument<span class="jr"> <a href="#Page_103">103</a></span></dt>
<dt>Supersonic flights banned, Moab-Times Independent<span class="jr"> <a href="#Page_17">17</a></span></dt>
<dt>Suspension bridge, Colorado River<span class="jr"> <a href="#Page_16">16</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_T"><b>T</b></dt>
<dt>Tanner, (Mrs.) Faun McConkie<span class="jr"> <a href="#Page_1">1</a></span></dt>
<dt>Taylor, L. L. (Bish)<span class="jr"> <a href="#Page_1">1</a></span></dt>
<dt>Temperatures<span class="jr"> <a href="#Page_51">51</a></span></dt>
<dt>“The Guide to an Auto Tour of Arches National Park”<span class="jr"> <a href="#Page_5">5</a>, <a href="#Page_50">50</a>, <a href="#Page_51">51</a>, <a href="#Page_72">72</a></span></dt>
<dt>The Needles section, Canyonlands National Park<span class="jr"> <a href="#Page_16">16</a>, <a href="#Page_102">102</a></span></dt>
<dt>The Windows section<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_41">41</a>, <a href="#Page_46">46</a>, <a href="#Page_51">51</a>, <a href="#Page_66">66</a>, <i><a href="#Page_68">68</a></i>, <a href="#Page_69">69</a>, <a href="#Page_70">70</a></span></dt>
<dt>Three Gossips<span class="jr"> <a href="#Page_63">63</a></span></dt>
<dt>Three Penguins<span class="jr"> <a href="#Page_57">57</a></span></dt>
<dt>Tower Arch<span class="jr"> <a href="#Page_83">83</a></span></dt>
<dt>Tunnel Arch<span class="jr"> <a href="#Page_40">40</a>, <a href="#Page_46">46</a>, <a href="#Page_90">90</a></span></dt>
<dt>Turnbow, Mary<span class="jr"> <a href="#Page_1">1</a></span></dt>
<dt>Turnbow cabin<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dt>Turret Arch<span class="jr"> <a href="#Page_68">68</a>, <a href="#Page_71">71</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_U"><b>U</b></dt>
<dt>Uncompahgre Highland<span class="jr"> <a href="#Page_23">23</a>, <a href="#Page_99">99</a>, <a href="#Page_100">100</a></span></dt>
<dt>Uncompahgre Plateau<span class="jr"> <a href="#Page_23">23</a>, <a href="#Page_99">99</a></span></dt>
<dt>Uplift, Colorado Plateau<span class="jr"> <i><a href="#Page_33">33</a></i></span></dt>
<dt>Upper Devils Garden<span class="jr"> <a href="#Page_98">98</a></span></dt>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dt>Uranium mines<span class="jr"> <a href="#Page_14">14</a></span></dt>
<dt>Ute petroglyphs<span class="jr"> <a href="#Page_10">10</a>, <a href="#Page_75">75</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_V"><b>V</b></dt>
<dt>Vanadium mines<span class="jr"> <a href="#Page_14">14</a></span></dt>
<dt>Vegetation<span class="jr"> <a href="#Page_37">37</a></span></dt>
<dt>Vertical arches<span class="jr"> <a href="#Page_42">42</a>, <a href="#Page_44">44</a></span></dt>
<dt>Visitor Center<span class="jr"> <a href="#Page_50">50</a>, <a href="#Page_51">51</a>, <a href="#Page_57">57</a>, <a href="#Page_86">86</a></span></dt>
<dt>Volz, J. Leonard<span class="jr"> <a href="#Page_8">8</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_W"><b>W</b></dt>
<dt>Walker, Lester<span class="jr"> <a href="#Page_13">13</a></span></dt>
<dt>Wall Arch<span class="jr"> <a href="#Page_90">90</a></span></dt>
<dt>Walt Disney crew, “Run, Cougar, Run”<span class="jr"> <a href="#Page_75">75</a></span></dt>
<dt>Wasatch Formation<span class="jr"> <a href="#Page_32">32</a></span></dt>
<dt>Water supply, Navajo Sandstone<span class="jr"> <a href="#Page_57">57</a></span></dt>
<dd>to the campground<span class="jr"> <a href="#Page_87">87</a></span></dd>
<dt class="pb" id="Page_113">113</dt>
<dt>White Rim Sandstone Member, Cutler Formation<span class="jr"> <a href="#Page_22">22</a></span></dt>
<dt>Wild Bunch, The<span class="jr"> <a href="#Page_12">12</a></span></dt>
<dt>Williams, J. W.<span class="jr"> <a href="#Page_1">1</a>, <a href="#Page_4">4</a></span></dt>
<dt>Wilson, Bates<span class="jr"> <a href="#Page_1">1</a>, <a href="#Page_3">3</a>, <a href="#Page_105">105</a></span></dt>
<dt>Wilson, (Mrs.) Bates<span class="jr"> <a href="#Page_3">3</a></span></dt>
<dt>Windows, distinguished from arches<span class="jr"> <i><a href="#Page_40">40</a></i></span></dt>
<dt>Windows section, The<span class="jr"> <a href="#Page_25">25</a>, <a href="#Page_46">46</a>, <a href="#Page_51">51</a>, <a href="#Page_66">66</a>, <i><a href="#Page_68">68</a></i>, <a href="#Page_69">69</a>, <a href="#Page_70">70</a></span></dt>
<dd>number of arches<span class="jr"> <a href="#Page_41">41</a></span></dd>
<dt>Wingate Sandstone<span class="jr"> <a href="#Page_35">35</a>, <a href="#Page_87">87</a>, <a href="#Page_102">102</a>, <a href="#Page_103">103</a></span></dt>
<dt>Wirth, Conrad L.<span class="jr"> <a href="#Page_4">4</a></span></dt>
<dt>Wolfe cabin<span class="jr"> <a href="#Page_1">1</a>, <a href="#Page_3">3</a>, <a href="#Page_12">12</a>, <a href="#Page_13">13</a>, <a href="#Page_14">14</a></span></dt>
<dt>Wolfe, Fred<span class="jr"> <a href="#Page_12">12</a>, <a href="#Page_13">13</a></span></dt>
<dt>Wolfe, John Wesley<span class="jr"> <a href="#Page_12">12</a>, <a href="#Page_13">13</a></span></dt>
<dt>Wolfe’s Bar-DX Ranch<span class="jr"> <a href="#Page_9">9</a>, <a href="#Page_10">10</a>, <a href="#Page_14">14</a>, <a href="#Page_74">74</a>, <a href="#Page_75">75</a></span></dt>
<dt>Wupatki National Monument<span class="jr"> <a href="#Page_102">102</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_Y"><b>Y</b></dt>
<dt>Yellow Cat area (Thompson’s area)<span class="jr"> <a href="#Page_14">14</a></span></dt>
<dt>Yellow Cat Flat<span class="jr"> <a href="#Page_86">86</a></span></dt>
<dt>Yellow Cat mining district<span class="jr"> <a href="#Page_83">83</a></span></dt>
</dl>
<dl class="index">
<dt class="center" id="index_Z"><b>Z</b></dt>
<dt>Zion National Park<span class="jr"> <a href="#Page_103">103</a></span></dt>
</dl>
<p><span class="lr"><span class="smaller">★U.S. GOVERNMENT PRINTING OFFICE: 1975—679-138</span></span></p>
<div class="img">
<img src="images/pmg092.jpg" alt="U. S. Department of the Interior, March 3, 1849" width="400" height="401" />
</div>
<h2 id="c27"><br /><span class="small">Transcriber’s Notes</span></h2>
<ul><li>Retained publication information from the printed edition: this eBook is public-domain in the country of publication.</li>
<li>Corrected a few palpable typos.</li>
<li>Included a transcription of the text within some images.</li>
<li>In the text versions only, text in italics is delimited by _underscores_.</li>
<li>The HTML version contains relative hyperlinks to a companion volume on Canyonlands National Park, Gutenberg eBook #51048.</li>
<li>A third book in the series, on Colorado National Monument, was revised after this book was printed.</li></ul>
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