782 R59 L48 flforttell Uniucraitg ffitbrarg THE GIFT OF UL.5. SoLpt. o|: Doca-manis, ^^JflAgJJ^-J^HV ■W &-J 1079F hi iUBfe illW ^na f Cornell University Library F 782R59 L48 olin 3 1924 028 879 082 Cornell University Library The original of this bool< is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924028879082 DEPARTMENT OF THE INTERIOR FRANKLIN K. lANE, Secretary NATIONAL PARK SERVICE STEPHEN T. MATHER, Director THE GEOLOGIC STORY OF THE ROCKY MOUNTAIN NATIONAL PARK COLORADO BY WILLIS T. LEE, Ph. D. Geologist, United States Geological SuiTey WASHINGTON GOVERNMENT PRINTING OFFICE 1917 n ^HnH- CONTENTS. Page. Introduction 7 Location and character 7 A brief historical sketch ^ 9 In the days of the aborigines 11 Accessibility 11 A general outlook 12 The making and shaping of the mountains 14 Geology and scenery 14 Before the Rockies were bom 15 The birth of the Rockies 19 How the mountains grew 21 How the mountains were shaped 22 Work of rain 23 Work of frost 24 Work of streams 25 Methods of work 25 Streams of park exceptional 27 Stripping of the mountains 27 An old plain of erosion'. 28 Many periods of uplift 28 Work of ice 29 When and why glaciers form. . . •. 29 ' Living glaciers • 29 Ancient glaciers 31 Fall River Glacier 32 Thompson Glacier 32 Bartholf Glacier 33 Mills Glacier 33 Wild Basin Glacier 34 Glaciers of North Fork and its tributaries 84 Glaciers in the northern part of the park 37 How the glaciers worked 37 Approaches to the park 38 Loveland to Estes Park 38 Lyons to Estes Park - 41 Ward to Estes Park 42 Grand Lake route 43 The park as seen from the trails 45 Black Canyon trail 45 Lawn Lake 47 Hagues Peak and Hallett Glacier 47 Roaring River 49 Horseshoe Falls 50 Fall River road 50 Trail ridge 54 3 4 CONTENTS. Page. The park as seen from the trails — Continued. Specimen Mountain 55 Mihier Pass 57 ffigh Drive 58 Moraine Park 59 Fern Lake and Odessa Gorge 59 Sprague Glacier 61 Flattop trail 62 Bierstadt Lake 63 Flattop Mountain 63 Glaciers and gorges south of Flattop 66 West of the Continental Divide •- 67 Bartholf Park 68 Bear Lake 69 Loch Vale 69 Lake Mills 71 Estes Park to Longs Peak 71 Routes 71 Longs Peak Inn 72 Twin Sisters 72 Longs Peak trail 74 Points of interest near timber line 75 Mills Moraine 75 The Chasm 76 Timber-Line trees 77 Ascent of Longs Peak 78 North St. Vrain River 81 Wild Basin ". 82 An appreciation 83 Index •. 85 nXUSTEATIONS. Page. Plate I. Map of the Rocky Mountam National Park In pocket II. Falls at the mouth of Glacier Gorge 7 III. A, Carboniferous landscape; B, Modem landscape in the Rocky Mountain National Park 14 IV. A, Brontoaaurus; B, Stegosaurus 15 V. A, Pterodactyl; B, Allosaurus '. 18 VI. A, Tylosaurus; B, Spoon-billed dinosaiir 19 VII. Panoramas of Estes Park 28 VIII. Map of ancient glaciers 30 IX. Flattop Peneplain 34 X. Narrows of Thompson Canyon: View near mouth of canyon; Tilted quartzites; Sedimentary rocks of the foothills 35 XI. Rapids in Thompson Canyon: A typical scene; A pinnacle in the canyon wall; Water versus rocks; A "pothole". . . 44 XII. Views in the canyon of the St. Vrain: A, Rapid and crag; B, Steamboat Rock 45 XIII. Scenes in the valley of the North Fork of Grand River: A, Cascade Falls; B, Lodge on the North Fork 46 XIV. Views near Estes Park: A, Estes Park and Longs Peak from Stanley Hotel; B, A remnant of erosion 47 XV. Black Canyon: A, The Needles; B, Twin Owls 48 XVI. A, Lawn Lake region; B, Hallett Glacier 49 XVII. A, A glacial cirque; B, View from Hallett Glacier 50 XVIII. Scenes on Hallett Glacier: Entering a crevasse; Interior of a crevasse; Icebergs 50 XIX. A, View from High Drive; B, Glacial moraine south of Horseshoe Park 50 XX. A, Horseshoe Falls; B, Rapids on Roaring River 51 XXI. Scenes on Pall River: A beaver dam; Fall River valley; Glacial cirque at head of Fall River 52 XXII. Scenes from the Continental Divide: A, The Never-Sum- mer Range; B, Crest of Front Range 54 XXIII. Specimen Mountain: A, Gulch on Specimen Mountain; B, Breccia and conglomerate 55 XXIV. A, Odessa Gorge; B, Bierstadt Lake 58 XXV. Winter sports: On Fern Lake; Snowshoeing on the Con- tinental Divide; Sprague Glacier 60 XXVI. TimberHne trees in Odessa Gorge: A, Dwarfed trees; B, A Limber pine 61 XXVII. Scenes on Milk Creek: Ruiaed beaver lodge; Glacial bowlder; Forests destroyed by fire 64 XXVIII. Scenes on Flattop Trail: Guide monument; Longs Peak and Glacier Gorge; Hallett Peak 66 XXIX How a glacier is fed; A hanging glacier; An arm of Tyndall Glacier 67 5 6 ILLUSTEATIONS. Page. Plate XXX. Bergschrund on Tyndall Glacier; Enos A. Mills; Beaver lodge; Bighorn sheep 68 XXXI. A, Andrews Glacier; B, Side of Andrews Glacier 68 XXXII. A, Bear Lake and Hallett Peak; B, Lilypad Lake 68 XXXIII. Loch Vale 69 XXXIV. Scenes near Longs Peak: Fire observer's station; Balanced rock; Timber-line trees on Twin Sisters; Trail makers; View from Cabin Rock 70 XXXV. A, Mills Moraine; B, The Chasm on Longs Peak 71 XXXVI. A, Wall of The Chasm; B, Chasm Lake 72 XXXVII. A, Timber Hne on Longs Peak; B, A pine tree at timber- line 73 XXXVIII. Timber-Hne trees on Longs Peak: Trees sheared by snow blasts; Where trees grow lying down; "The Winged Vic- tory" 74 XXXIX. Scenes on Longs Peak: A, Bowlder Meld; B, The Key- hole 75 XL. The Trough on Longs Peak 76 XLI. A pocket lake in Glacier Gorge 77 XLII. Views near the top of Longs Peak: The Notch; The Nar- rows; Home Stretch; An ice-smoothed rock 80 XLIII. A, Copeland Lake; B, Melting basin and lateral moraine of Wild Basin Glacier 81 XLIV. Views in Wild Basin: A, Longs Peak and Thimder Lake; B, Rapids on the St. Vrain 82 XLV. Thunder Lake and Mount Alice 83 FiGUEE 1. Map showing routes to the Rocky Mountain National Park 8 2. Profile section across the Rocky Mountains through Longs Peak and Grand Lake 16 3. Leg bones of a dinosaur 17 4. Map of North America showing distribution of land and sea in Upper Cretaceous time 18 5. Sketch map showing the glacial moraines in the valley of the North Fork of Grand River 36 6. A, Stream-cut valley; B, Same valley after glaciation 37 PLATE II mW'-iiv FALLS AT THE MOUTH OF GLACIER GORGE. Photograph by Willis T. Lee, United States Geological Survey. THE GEOLOGIC STORY OF THE ROCKY MOUNTAIN NATIONAL PARK, COLORADO. By Willis T. Lee, Ph. D. IHTEODTJCTIOIT. LOCATION AND CHARACTEB. On January 26, 1915, a particular section of the Rocky Mountains chosen as representative of the noblest qualities of the mountain region was set aside as the Eocky Mountain National Park. This park covers an area of approximately 398 square miles, situ- ated in the high mountains of the Front Range in north-central Colorado, about 50 miles in a straight hne northwest of Denver. Altitudes within it range from 8,000 to 14,255 feet above sea level. The moTintains are of such height that during the greater part of each year they are spangled or completely covered with snow. Hence the Front Range is often called the Snowy Range. Denver, the metropolis of the western plains, through which most of the visitors pass on their way to the Rocky Mountain National Park, is only 50 miles from Estes Park, the gateway. The park is within 30 hours of Chicago and St. Louis and is much closer to Kansas City and many other great centers of population in the cen- tral part of the United States. Probably no other national play- ground is more easily reached by a large munber of people. The appeal of this park to the tourist is varied, and few fail to find satisfaction here. In it are accommodations for visitors of every kind, from the man who wants the conveniences of the modern hotel to the one who wishes to throw off restraint and to Hve for a time the care-free life. Here he may bivouac by rock and stream in the primeval forest or obtain the comforts of modern Ufe in easy reach of perpetual ice, where cool breezes from the snow fields ren- der delightful the bright summer days and make welcome the warmth of the camp fire on the clear, cool evenings. The naturalist may find plant and animal hfe of all zones, from Temperate to Arctic. The artist has an inexhaustible supply of 7 8 ROCKY MOUNTAIN NATIONAL PARK. landscapes, ranging in character from mountain crag to flowery glade. The weary in mind or body find new vigor, while the vigorous have inexhaustible opportunities of testing their endurance. For glorious, sunny days and cool, restful nights the Eocky Moun- tain National Park can not be surpassed. The weather is depend- able. The crisp, sparkHng atmosphere, laden with the pungent breath of pine and spruce, is a never-failing dehght to the experienced and to the amateur ahke. Here the oppressive heat of lower alti- tudes and damper cUmates is unknown, and mosquitoes need not be thought of, for the nights are too cold for them. There is an abun- dance of dead and down firewood for the great, roaring campfires, around which the cool evenings may be spent spinning yarns and telhng stories of adventure which no one need beheve. Thunder- storms are of frequent occurrence, but little rain falls. The storm soon passes, and usually its most conspicuous result is the wonder- ful cloud effects which so delight the heart of the artist. The streams are fed by the melting snow of the high mountains, and their waters are clear, cool, and healthful. Like Bunyan's pilgrims, who in the course of their progress came to the "delectable mountains," the modern pilgrims are coming in increasing thousands to find their hearts' desire in the delectable mountains of the Snowy Range in the Rocky Mountain National Park. They come afoot and awheel, some with blankets and pro- visions on their backs, many on motorcycles; and great numbers in automobiles. Occasionally a horse-drawn vehicle is seen. But, however they come, it is with eyes fixed on the glowing peaks with feverish impatience to reach the wonderland of the dreams that have illmnined the weeks and months during which their vacation plans were forming. Whether they come in May or November, the general result is the same. The tourist of early summer is charmed by the great snow banks of the white-crested mountains and enthusiastically watches as they disappear and flowers spring into bloom in their place. Many of the plants push their tender stalks through the last rem- nants of the snow and burst into bloom while the ice actually covers their roots. The midsummer visitor is equally enthusiastic over the flowery glades, the spicy fragrance of the forest, the magnificence of the views obtained during the long excursions, and the exhilaration of venturesome climbing. The late visitor declares that the fall is supreme, when the air is crisp and the trout are hungry; when the frosts are painting the aspen-covered slopes, and the fleecy cover of the peaks is extended lower and lower with each recurring storm, until the whole range is covered for its winter sleep with a mantle of gUstening white. But, comes the toxuist early or late, the con- stantly increasing ntunber of visitors and the great number of those T»fO»reOUJNS MAP OF ROCKY MOUNTAIN NATIONAL PARK EOCKY MOUNTAIN NATIONAL PARK. 9 who retttm repeatedly speak eloquently of the fact that the white- crested monarchs of the Snowy Range are to them in truth "the delectable mountains." A BRIEF HISTOBICAL SKETCH." The development of Estes Park as a tourist resort was somewhat slow, but it is a matter of iaterest that tourists began to come as early as 1865, when two campers pitched their tent there. The num- ber entering it in 1916 is estimated as high as 86,000. It was not until 1874 that a stage line was established between the park .and Longmont. Three years later a toll road was completed between Estes and Lyons. Then followed a long period of slight activity toward development, • but with the new century a fresh start was taken. A long-distance telephone was run into the park in. 1900, and in September, 1906, the Estes Park Protective and Improvement Association was formed. One of the first accomplishments of this organization was the establishment of the fish hatchery, which has since been taken over by the State. Other results of its activity are the Highline Drive, the traU up Prospect Mountain, and the protec- tion of game and wild flowers. A year later, 1907, an automobile stage line was estabhshed between Estes Park and Loveland, and in 1909 Mr. Enos A. Mills began his work of urging the establishment of the national reservation. While the vast tumbled massing of mountains in Colorado became a notable landmark for the early explorers, that magnificently scenic groupmg which is now the Rocky Mountaia National Park became known only in later years. The reason was that, whUe it fronts immediately the great eastern plains, it lay apart from and between the natural passes across the Rockies. The first historical reference to this section is found in the records of the explorations of Lieut. Pike, for whom Pikes Peak was named. Scanning the snow-topped mountain barrier from the plains in November, 1806, Pike singled out its most commanding height and called it Great Peak; but he entered the mountains many mUes south. The second historical reference to this section is f oimd in the report of the exploring expedition under Col. S. H. Long, which President Madison sent out in 1819. While camping at the mouth of the Poudre River on July 3 of that year, the party was greatly im- pressed with the magnificence of a mountain which they identified as Lieut. Pike's Great Peak. This they formally named Longs Peak in honor of their leader. But neither Long nor any of his party approached the mountain, though some of the party were the first to climb Pikes Peak. Parkman records his first view of Longs Peak in 1845. 1 This sketch was prepared at my request by Mr. Eobert S. Yard, of the National Park Service. 10 EOCKY MOUNTAIN NATIONAL PARK. The early trappers knew the mountains, which then were fairly- alive with game, great and small. Enos Mills states that Kit Carson was probably the first white trapper to visit them. Carson camped m the valleys to the east probably in 1840. The first settler came in 1860. He was Joel Estes, from whom the broad valley was afterwards named Estes Park. He buUt a cabin on Willow Creek in the foothills. At that time there were numerous remains of former Indian residents in the valleys, but no Indians. For many years after that the region was visited by trappers, who followed the deer and elk and trapped the beaver in the valleys and shot the bear and mountain sheep in the rocky fastnesses of the great mountains. Settlers came slowly. In 1868 arrived James Nugent, afterwards widely celebrated as "Rocky Mountain Jim." The superb commanding height of Longs Peak naturally tempted the early comers. In 1864 WiUiam N. Byers, founder of the Rocky Mountain News, made the first attempt to climb it. This was unsuccessful, as were all other attempts until August 23, 1868, when Mr. Byers accompHshed the feat. With him were Maj. J. W. Powell, who, the following year, made his celebrated first exploration of the Grand Canyon, W. H. Powell, L. W. Keplinger, Samuel Gorman, Ned E. Farrell, and John C. Sumner. In 1871 the first regular guide on Longs Peak, the Rev. E. J. Lamb, made his first ascent. He descended by the east precipice, a dangerous feat which Enos MiUs repeated in 1903. The exceptionally fine hunting through this entire region caused Earl Dunraven in 1872 to attempt the acquisition of a great preserve. Men were hired to file claims which he afterwards acquired; but these claims proved invahd. But he maintained a ranch in the Estes Valley for some years. In 1874 Albert Bierstadt visited the region as Earl Dunraven's guest. Some of his most celebrated paintings are the fruit of this visit. This same year the first stage line was established between Estes Park and the village of Longmont, on the plains at the eastern edge of the foothills. Immediately thereafter many came to stay. The first formal hotel was built by Earl Dunraven upon a site chosen by Bierstadt. This was destroyed by fire. The Dunraven properties were acquired by Mr. F. O. Stanley, who by the erection in 1909 and 1910 of handsome modem hotels costing half a million dollars gave Estes Park its first big impetus as a summer resort. In recent years many hotels of many kinds have been buUt in the eastern valleys, and last year 86,000 persons found roofs to cover them. Meantime many miles of valley road were laid out, giving access to beauty spots in the glena and gorges between the rocky knees of the great range, and trails were built into the heart of the mountains and EOCKY MOUNTAIN NATIONAL PARK. H across the range to Grand Lake, which meantime had become a prosperous resort on the west side. In 1915 Congress set apart 358 square mUes of the front range, with Longs Peak for the cuhninating center, as the Rocky Mountain National Park. In 1917 Congress added more than 40 square mUes to this territory, briaging its boundary within a short distance of the village of Estes Park. IN THE DAYS OF THE ABORIGINES. The Arapahoe Indians once claimed the Rocky Mountain National Park as a part of their domain, and many of their place names are interesting and significant. An effort has been made, particularly by the Colorado Mountain Club, to preserve these names. Some of the Arapahoes, now old men who had visited the park in their youth, were brought back recently and questioned as to names of places and the legends connected with them. The story of their visit has been written by Oliver W. ToU. Unfortunately this story had not been published at the time the present account was written. However, the manuscript was kindly loaned by Miss Harriet Walcott VaUle, secretary of the Colorado Mountain Club, and from it were taken the notes explaining the Indian names scattered through the following description. ACCESSIBILITY. The value of a public park largely depends on the use that may be made of it. In accessibility the Rocky Mountain National Park is favorably situated. It contains momitain scenery of the highest order of beauty and grandeur and at the same time is the most easily reached by a large number of people of aU our national playgrounds. (See fig. 1.) Its gateway from the east is the village of Estes Park, situated within the mountains in a beautiful valley of the same name. Its gateway from the west is Grand Lake. There are several ways of reaching Estes Park (see PL I, in pocket) from the plains lying east of the mountains. Three routes are extensively used — the Thompson Canyon Road from Loveland to Estes Park, the Lyons-Longmont Road between Lyons and Estes Park, and the road from Ward northward by way of Aliens Park and Longs Peak. From Estes Park and the several hotels and lodges situated just outside the boimdary of the national park many of the points of interest may be reached by automobile, and the tops of the highest mountains may be reached by a day's travel on foot or on horseback. It is no uncommon thing for a traveler to breakfast at a hotel or lodge on one side of the range, walk or ride over the Continental Divide, and 12 ROCKY MOUNTAIN NATIONAL PARK. dine on the other side. For general accessibility it will be difficult to find a high mountain resort of the first order that will quite compare with the Rocky Mountain National Park. A GENERAL OUTLOOK. The Snowy Range lies in a north and south direction. The gentler^ slopes are to the west, and at altitudes below timber line they are so heavily forested that few good views can be obtained from the trails. On the east the descent from the Continental Divide is precipitous. Here barren slopes, craggy peaks, and precipices are so numerous that magnificent and unobstructed views are to be obtained everywhere. In many places east of the divide forests have been destroyed by fire, and only the dead trunks remain, some standing, others fallen, to indicate their departed glory; but although the wholesale destruc- tion of these splendid forests is regrettable it is not without its com- pensation, for many a wonderful landscape has been opened to view in this way which would be obscured by living forests. Also the weirdness of these spectral remains lends a melancholy charm to many a scene and adds variety to the galaxy of interesting spectacles. East of the mountain crest gorges with walls 1,000 or even 2,000 feet high are common, and between the gorges stand the bold sum- mits in infinite variety of form. As seen from the east, the range rises in daring relief, craggy in outline, snow spangled, and awe inspiring. In stalwart nobility, in calm dignity, and in the beauty and grandeur of varied scenery the mountain group that culmi- nates m Longs Peak (14,255 feet) is unsurpassed. The lover of moimtains who feels, the inspiration of its imposing stateliness may be pardoned if in his enthusiasm he calls this "the top of the world," as local enthusiasts are prone to do. Many a less imposing place has been so called. There are probably few other scenic regions which combine mountain outlines so bold with qualities of beauty so refined. The Longs Peak group of summits, loftiest and most imposing in the park, is not the only group worthy of special mention. There is in the northern part of the park an assemblage of mountains culmi- nating in Hagues Peak (13,562 feet), which is scarcely less imposing In this tumultuous mass are some of the most majestic peaks and one of the finest glaciers in the park. To the south of Longs Peak the coimtry grows even wilder. The range here is a succession of superb summits. The southern boundary of the park unfortunately cuts arbitrarily through a splendid massing of noble snow-covered mountains. The St. Vrain Glaciers, with their surrounding ramparts, a spectacle of grandeur, lie outside the park, and stiU farther south the Continental Divide increases in splendor to Arapahoe Peak and its weU-known glacier. It is to be EOCKY MOUNTAIN NATIONAL PARK. 13 hoped that the park will be extended southward to include Arapahoe Glacier, which is the southernmost living glacier in North America. The west side of the range, gentler in its slopes and less majestic in its moimtain grouping, is a region of lovehness and wildness diversified by innumerable streams and lakes of great charm. Grand Lake, which has railroad connections near by, is the largest and deepest lake in the park. It is the center of a growing cottage and hotel population and is destined to become a place of much impor- tance upon the completion of the Fall River Road, which will connect the east and west sides across the Continental Divide. The mountains of the Snowy Range are very rugged and are cut by deep canyons and steep-waUed gorges into an infinite variety of sharp peaks, pinnacled spurs, and crested or serrated ridges. Geologically they are "young mountains" and exhibit all the bold, daring, and attractive characteristics of youth. The Rocky Moimtain ISational Park is in the very heart of the Rockies, and the barren crags and granite cliffs seen in all parts of it make its name eminently appro- priate. The majestic monarchs in the center of the range are flanked by less commanding summits, arranged in order of prominence, down to the rank and file near the foothills, where mountains are so numerous that those which would be exploited in a less imposing presence as scenic wonders are not even named. These, like the more stalwart giants near the crest of the range, are separated by gorges whose walls rise almost vertically hundreds and in some cases thousands of feet. In many places precipices rise in daring reUef and craggy outhne 1,000 feet or more from relatively level floors. In the higher gorges many of these floors are covered during much of the year with snow or are occupied by frozen lakes. At lower altitudes they are forested or carpeted with grassy turf and beds of wild flowers. At the higher altitudes there are many rock-bound lakes, some occupying basins at the bottom of the gorges, others perched high in the craggy sides of precipices in most unexpected places. These high-altitude lakes range in color through many shades of green and blue. Because the shades vary from time to time these lakes have been called the "gems of the mountains," and their changing color is likened to the varying aspect of jewels. In the gorges and in many of the broader valleys are found con- spicuous evidences of ancient glaciation. Great moraines have been formed by glaciers carrying bowlders and smaller fragments of rock down the valleys and heaping them in great ridges at the sides and end of the ice. In many places the rocks were pohshed by the ice passing over them. Striated surfaces are found where the bottom 14 EOCKY MOUNTAIN NATIONAL PAEK. and sides of a gorge were scratched by rock fragments held frozen into the moving ice, like a graver's tool clamped in a lathe. Lake basins were gouged out of the soUd rock by the moving ice. For easily read records left by ancient glaciers the Rocky Mountain National Park is almost unique. In few other places do these evidences so intrude themselves upon the eye. The great moraines, such as the long ridge south of Moraine Park, which rises 800 feet or more above the floor of the valley, are so prominent and sharply outlined that even the untrained observer notices that they differ in character from the neighboring hiUs. The rounded bowlders, the pohshed and striated surfaces, and the perfectly outlined moraines make this region a primer of glacial geology, whose lessons may be read so easily that no one need miss them. Also in this park there are small living glaciers, samples of the great masses of ice which filled the gorges in past ages. These assist the observer in his effort to realize the grandeur of long ago. We may reconstruct in imagination the great streams of ice which existed here during the Great Ice Age by mag- nifying these living glaciers many thousands of times until they fill the hollows between the moimtains and extend many miles down the valleys. (See PL VIII, p. 30.) The lower slopes of the mountains are wooded wherever they are not too precipitous for trees to take root; in some places the forests have been destroyed by fire, but the higher slopes are barren, for trees do not grow here above an altitude of 11,500 feet. Near this elevation, known as timber line, the struggle for existence is severe and gives rise to many curious and intensely interesting forms of growth, commonly known as timber-Une trees. On the slopes above timber line may be found a flora sufficiently varied and unusual to delight the heart of the botanist as well as of the ordinary lover of flowers and plants. Here also may be found the descendants of the arctic plants which were driven southward during the Great Ice Age. Some followed the retreating glaciers northward as the cUmate moderated; others found a cUmate sufficiently cool for their needs on the high mountains. THE MAKIITG AND SHAPING OF THE MOUNTAINS. GEOLOGY AND SCENERY. The Rocky Mountain National Park is noted chiefly for variety of mountain landscape. The land forms result from the action of stream and frost and ice. A study of the park, therefore, is chiefly a study of geography. Furthermore, geographic development, or the shaping of the landscape is (E3dss',uon(-.'-^-;^;^ ^\ -o\\ O ■■^- v.. ,1 0/ t 1 1 (i o\ i\ ^^V o> .'S >. Ill fe S s M 03 te H Tj II i| fV a i H J -3 ;:^ 3« 'W Later, in the Age of Reptiles — that is, in the early part of the Cre- taceous period (see table, p. 20) — sand and mud were spread out over this region in the form of sheets rang- ing in total thickness from less than 100 to more than 400 feet. These hardened into the rocks which the geologists call the Morrison format tion, so called because it was first studied in detail at the town of Morrison, which is situated just west of Denver, Colo. In many respects these rocks are the most interesting of those exposed in the foothills of the Rockies. They are especially fascinating because of thefossilbones of huge reptiles found in them. It is worthy of note, in this connection, that the first fossils of the greatest of aU known reptihan faunas were found in these rocks at Morrison. During the hfe of these grotesque giants the country where now the hoary summits of the mountains hang among the clouds was a low- lying swampy plain somewhat similar in character to the delta of the Mis- sissippi. Over this plain the streams migrated, formingbroad flood plains, extensive swamps, and shallow mi- gratory lakes. In these swamps and lakes and on the surrounding plains lived the huge reptiles whose bulk seems almost incredible and whose form, as depicted by those most competent to judge their character, seems beyond the power of the imagi- nation (see PI. IV, B, p. 15). The lar- gest of these creatures were plant eaters, and some of them attained a length of 85 feet or more and a weight that has been estimated as high as 20 tons. These mon- EOCKY MOUNTAIN NATIONAL PARK. 17 sters were inhabitants of the swamps (see PI. IV, A), in which many of them perished by miring. Their bones were preserved in the mud and are now found petrified in a remarkably perfect state of preservation. The leg bone of one of these monsters, 6 feet 6 iuches long, is shown in figure 3. Probably the most grotesque of all the monsters of this period was the armored dinosaur (Stegosaurus) . It was a herbivorous or vege- table-eating creature, about 20 feet long and 10 feet high, with an extremely small lizard-hke head, long hind legs, and short forelegs. It had a double row of enormous bony plates along its back and four huge spines near the end of its tail. For repulsive ughness it seems Fig. 3.— Leg bones of a dinosaur, showing size in comparison with the size o£ a man. to be in a class of its own. Had it not been for the strong protective armor it could scarcely have survived the attacks of its carnivorous enemies, for its brain was so ludicrously small as to suggest a men- tality scarcely sufficient for conscious efforts at self-preservation. Scarcely less in bulk than these grotesque vegetarians and probably much more active and powerful were some of their carnivorous ene- mies, such as AUosaurus (PI. V, B, p. 18), a monster 20 feet long, whose toes were armed with long, sharp claws adapted to catching and rend- ing its prey, and whose jaws were well supphed with pointed fangs for tearing flesh. In the long ago monsters such as these lived where the Eocky Motmtain National Park now is — in the long ago before the moimtains 99305°— 17 2 18 EOCKY MOUNTAIN" NATIONAL PARK. were brought forth, and before erosion had succeeded in carving the upheaved mass into craggy peak and rocky gorge. In geologic history, as in huraan history, change is the order of progress. The swampy plains subsided, and over them the sea water Fio. 4.— Map of North America, showing distribution of land and sea in Upper Cretaceous (Benton) time. (Area not shaded indicates land; shaded area indicates sea.) made its way, connectiag the Gulf of Mexico with the Arctic Ocean, covering the interior of North America from Utah to the Mississippi Eiver. (See fig. 4.) In this sea sported such creatures as the great PLATE V A. RESTORATION OF A PTERODACTYL (ORNITHOSTOMA). A flying dragon measuring 18 feet from tip to tip of wings. Winged reptiles Uke this lived in central North America during the Cretaceous period. B. ALLOSAURUS. A carnivorous dinosaur preying on one of the herbivorous dinosaurs. ANCIENT INHABITANTS OF THE ROCKY MOUNTAIN NATIONAL PARK. PLATE VI ■M .^ A. RESTORATION OF TYLOSAURUS. A maxine lizard of Cretaceous age about 40 feet long — a "sea serpent" such as swam at one time where Longs Peak now stands. Drawn by J. Green. B. THE SPOON-BILL DINOSAUR. Hadrosaurus mirabilis, a reptile of Cretaceous age. CREATURES OF LONG AGO. EOCKY MOUNTAIN NATIONAL PAKK. 19 Mosasaur (Tylosaurus) (PI. VI, A, p. 19), and over its waters sailed carnivorous flying reptUes (pterodactyls), some of which had a stretch of wing of 18 feet (see PI. V, J., p. 18) ; they were animated engines of destruction, which somewhat forcibly suggest the modem war air- planes, of which they were in a sense the prototypes. On the shores of this sea grew luxuriant vegetation which foxmd lodgment in huge peat bogs. These deposits have been preserved for our use in the form of coal.^ On these boggy shores hved the reptiles of that age, some of which were scarcely less grotesque than their Morrison predecessors (see PI. IV, B, p. 15). With them lived birds, some of which still retained reptilian characteristics,^ such as jaws with teeth, a character possessed by few modem birds and by these only at an embryonic stage. The first sediments laid down in this sea were the sands and pebbles formed along the shore. As the water advanced farther and farther inland, the beach sands, washed clean by wave and tide, were buried, during a later stage when the shore had advanced and the water was deeper, by the mud which gathered over them at the bottom of the sea. This sand hardened into a very resistant layer of sandstone, which has been named Dakota. It is the rock which forms the crest of the prominent hogback or ridge just east of Lyons and a few mUes west of Loveland (see fig. 2, p. 16). The sand was buried in timi by other sand, mud, and Hmy ooze laid down in the sea during the Cretaceous period (see table, p. 20) to a depth of several thousand feet. These beds hardened into the shale and limestone of the plain which hes east of the foothills. The petrified shells of mollusks which lived in this sea during the Cre- taceous period may be seen west of Loveland in the shaly rocks at the side of the Estes Park Road. THE BIRTH OF THE ROCKIES. At the end of the Cretaceous period some great readjustment took place within the body of the earth which caused worldwide changes at its surface. The disturbance stirred into Ufe the dormant roots of the ancient mountains. The sea water sank back into the ocean basins,^ and the bed of the sea was arched into a great dome (see fig. 2) . 1 In the eastern and central paxts of the United States nearly all of the coal is of Carboniferous age— an age which took its name from the carboniferous or coal-bearing character of the rocks— but in the Eocky Mountain region nearly all of the coal is younger than Carboniferous. The coal beds in western America are mainly of Cretaceous and Tertiary age. (See table, p. 20.) 2 There are so many facts which indicate that birds were derived from reptiles that few paleontologists now question their ancestry. The strongest reptilian character is the jaws with teeth similar to those of the ancient reptiles. Other significant similarities are found in the skeletons. Added to these is the fact that certain modem birds during their early life have reptilian characteristics. ' Statements of this kind need not tax our credulity if we recall that a quantity of water equivalent to 1 per cent of the ocean would cover all the land areas of the globe to a depth of 290 feet. The water of the old Cretaceous sea would doubtless represent only a small fraction of 1 per cent of the oceanic water and when poured back into the ocean probably raised the general sea level very little. 20 BOCKY MOUNTAIN NATIONAL PARK. It should not be inferred that rock movements of this kind are rapid enough to be seen or that they were accompanied by cataclysmic disturbances. Doubtless there were earthquakes occasionally, as there are now.' But it is probable that the great rock movements which resdlted in the upheaval of the Eocky Mountains were not rapid enough to be perceptible. From a geologic point of view a change in level of 1 foot in a century for any large part of the earth's surface would be a rapid change. It is probable that had a man been hving during the time of even the most rapid mountain growth he woidd not have detected any change during his lifetime. We speak of the "everlasting hills" as types of stability and of imchangiag constancy, but they are everlasting only in a relative sense, as com- pared with the span of human life. Every geologist knows that the hUls are constantly changing, and it is possible that these changes are going on at the present time as rapidly as they ever did. Principal divisions of geologic time.'' Era. Period. Epoch. Characteristic life. Duration, accord- ing to various estimates. Cenozoic (re- Quaternary. Recent. Pleistoce n e (Great Ice Age). "Age of man." Animals and plants of modern types. MilUoTis of years. cent IKe). Tertiary. Pliocene. Miocene. Oligocene. Eocene. "Age of mammals." Possible first ap- pearance of man. Rise and develop- ment of highest orders of plants. Cretaceous. {') "Age of replUes. " Rise and culmination ofhuge land reptiles (dinosaurs), of shell- fish with complexly partitioned coiled shells (ammonites), and of great flying reptiles. First appearance (in Jurassic) of birds and mammals; of cycads, an order of pahullke plants (in Triassic); and of angiospermous plants, among which are palms and hardwood trees (in Cretaceous). Mesozoic (in- termediate lil?). Jurassic. (») i to 10. Triassic. (?) Carbonifer- ous. Permian. "Age of amphibians." Dominance of club mosses (lycopods) and plants of horsetail and fern types. Primitive flowering plants and earliest cone-bearing trees. Beginnings of backboned land animals (land vertebrates). Insects. Animals with nautilus-like coiled shells (ammon- ites) and sharks abundant. Pennsylva- nian. Paleozoic (old Uie). Miss i s s i p- pian. Devonian. ffl "Age of fishes." Shellfish (mollusks) also abundant. Rise of amphibians and land plants. 1 An earthquake shock was felt in Estes Park on Jan. 6, 1903. 2 The geologic record consists mainly of sedimentary beds— beds deposited in water. Over large areas long periods of uphft and erosion intervened between periods of deposition. Every such interruption in deposition in any area produces there what geologists term an unconformity. Many of the time divisions shown above are separated by such unconformities— that is, the dividing lines in the table represent local or widespread uplifts or depressions of the earth's surface. ' Epoch names omitted; in less common use than those given. EOCKY MOUNTAIN- NATIONAL PARK. Principal divisions of geologic time — Continued. 21 Era. Period. 'Epoch. Characteristic life. Duration, aocord- hig to various estimates. Silurian. 0) Shell-forming sea animals dominant, espe- cially those related to the nautilus (ceph- alopods). Rise and culmination of the marine animals sometimes known as sea lilies (crinoids) and of giant scorpion- like crustaceans (eurypterids). Rise of fishes and of reef-buildSng corals. 17 to 25. Paleozoic (old lile)— Continued. Ordovlcian. (') Shell-forming sea animals, especially ceph- alopods and moUusk-hke brachiopods, abundant. Culmination of the buglike marine crustaceans known as trilobites. First trace of insect life. Cambrian. (•) Trilobites and brachlopods most charac- teristic animals. Seaweeds (algse) abun- dant. No trace of land animals found. Proterozoic Algonkian. (') First life that has left distinct record. Crustaceans, brachiopods, and seaweeds. Archean. Crystall i n e rocks. No fossils found. SO-h 1 Epoch names omitted; in less common use than those given. HOW THE MOUNTAINS GREW. If uplift had occurred without erosion, a great dome, somewhat like that illustrated by the broken lines of the profile (fig. 2, p. 16), but more or less warped and broken, with surface cracked and uneven, would now stand in place of the highly varied complex of peaks, ridges, and gorges which characterize the mountain region. As a matter of fact, however, the agents of erosion began their work the moment that the rising land emerged from the sea. From that time to the present the height and the character of the moimtains have been dependent on the progress of the confhct between opposing forces. One group of forces strove to elevate the moxmtains; the other to tear them down. Sometimes one group gained the ascend- ' ancy and sometimes the other, so that the moimtains have had an eventful life. Sometimes they were high and rugged, as we now see them; at other times they were worn down to a state of low relief, in which some portions of them were nearly level and others were reduced to relatively low roUing hills having smooth, gently sloping sides. Little need be said here about the mountain-making forces. Their origin is obscure and their manner of operation is uncertain, because they originate in the unknown interior of the earth. There are several possible ways by which the Eocky Mountains may have been formed. They may represent wrinkles on the face of the earth, 22 BOCKY MOUNTAIN NATIONAL PAKK. caused by the shrinkage of the interior; they may have been forced up by the settling of some larger portion of the earth's mass, much as the surface of soft wax is raised near an object which is thrust into it; or they may have been raised by the intrusion of molten matter forced at great depths into the underlying rocks of the mountains. More is known of the processes by which the uplifted mass was sculptured, because these were recorded at the surface. Although erosion began as soon as the land arose above sea level, we may be permitted for the sake of clear understanding to think of the moim- tains as elevated before the agents of erosion began to operate; for it is difficult to carry in the mind the two concepts* with all the complex interrelations. The great dome may be thought of as the block of stone from which the sculptor is to carve a group of statuary. Chief among the graver's tools to be used are rain and stream, frost and ice. The driving forces for operating these tools are chiefly gravity and the heat of the sun. The latter may be said to work both positively and negatively. Its positive work consists largely in transforming water to vapor and raising it into the air. Its negative work, or the accomplishments due to partial withdrawal of heat, results in the fall of rain and snow, frost action, and accumulation of ice in snow fields and glaciers. Gravity works chiefly through the fall of rain and the flow of streams and of glaciers. The rocks are softened in preparation for the graver's tools by such chemical agents as carbon dioxide and other acids from decaying vegetation. The resulting statuary is the mountains. The chips formed in digging the valleys and gorges were swept away by the streams and the glaciers. Most of these have been carried out of the motmtains, but the chips most recently formed are now seen as the sand of the lakes, the pebbles of the streams, and the bowlders of the great glacial moraines. HOW THE MOUNTAINS WERE SHAPED. Many people have the erroneous notion that some titanic force pushed mountains up ia the form they now possess. On the con- trary, the forms so much admired result from centuries of action by raia, stream, frost, and ice. To uncivifized people rugged moun- tains and deep canyons are repellent, for the untutored mind peoples them with evil spirits and imaginative dangers. But the thousands of cultured tourists who visit them find a satisfying contentment, and this satisfaction reaches its climax when appreciation of the magnificent results is accompanied by an intelligent comprehension of the processes by which these results were obtained. Some moun- tain climbers are content only with the thrill of mastering a difficvdt peak; others are more advanced in their appreciation. The massive vigor of the mountains incites enthusiasm and lifts the mind to higher BOCKY MOUNTAIN NATIONAL PARK. 23 levels. But surely the acme of satisfaction, is reached when the thrill of attainment and the expansion of soul, so often experienced amid grand surroundings, is accompanied by an imderstanding of the forces which brought the objects of admiration into being. Although this is not the place for a textbook description, in which the various agents of erosion are enumerated and evaluated, mention may be made of some of the principal ones and a brief sketch given of the manner in which they operate. WORK OF RAIN. Great results may be accomplished by forces so insignificant that they escape the notice of unobservant persons. Some who have not given the subject special thought may read with incredulity the state- ment that the great mountains of this national park were carved out largely by rain. But those who study land forms and the processes by which a landscape is shaped have long recognized the fact that rain is one of the principal factors in erosion. Careful observation during a storm will convince the most skeptical. Every raindrop that strikes the earth picks up a tiny load of mud, and the myriad drops collect as the muddy water of the rivulets which join to form the river that carries the great loads of mud to the sea. But probably an equally important work accomplished by water falling as rain is done in connection with other chemical agents. Water has been called a universal solvent. In spite of the fact that we frequently refer to "pure water," there is no such thing as pure water on the face of the earth. It always contains other material in solution. If it contains certain kinds in sufficient quantity it may be called a mineral water, but in reahty every spring, every well, and every stream contains mineral water. The raindrop on its way from the cloud to the earth absorbs oxygen, carbon dioxide, and other gases, and, on penetrating the soil, it takes up vegetable acids and various other ingredients. It carries these with it into the minute crevices of the rock, where the acids produce chemical changes. The water is not so much the cause of the chem- ical action as it is the carrier of the chemical agents. Some of the newly formed compounds are easily soluble and are quickly taken into solution by the water; others are less soluble. Thus, by the chemical action of the rain water some parts of the rocks are dis- solved out and the less soluble parts are left, held together so loosely that the rock crumbles. The subject of the chemical action of water and its results might be expanded into volumes, for it embraces the production of soU, the construction of caves, the formation of minerals, and the deposition of metalliferous ores. However, the action which immediately concerns us in understanding how the rain helped to form the moimtains is 24 EOCKY MOUNTAIN NATIONAL PARK. that of moisture on the granite of which the mountains consist. The granite contains a variety of minerals But is composed mainly of crystals of quartz and feldspar. The quartz is only slightly af- fected by the penetrating solutions. These solutions act principally on the feldspars, composed chiefly of sodium, potassium, calcium, aluminum, and silica. Of these elements aluminum and silica are only slightly soluble and are left as clay and sand when the rock breaks down. The sodium, potassium, and calcium unite with the carbon dioxide brought to them in solution by the water and form soluble salts, such as calcium carbonate. These are removed by the percolating waters. This removal, however, takes place irregularly along crevices or wherever the solutions can penetrate the rock. Hence the rock crumbles when the honeycombing process has gone far enough. The decay of rocks seems more conspicuous in lowlands than in highlands, because the removal of waste products goes on less vigor- ously there than in highlands. Also from steep mountain surfaces a greater proportion of the rain water escapes as surface run-off. On such precipitous mountains as those of Rocky Mountain National Park chemical action is doubtless near the minimum, while the mechanical forces of disintegration, represented by stream, frost, and ice, are at their maximum. WOEK OF FEOST. Probably the most efficient of the mechanical agents of erosion, especially in the high mountains, is frost. It is well known that water expands on freezing, and it is equally well known that the expansive power of freezing water is almost irresistible. So potent is this force that it has no difficulty in splitting granite asimder and pushing great blocks of it from the cliffs. One of the dangers of chmbing in the high moimtains arises from falling rocks. Water fills a crack in the face of a precipice, freezes at night, and loosens a mass of rock from the face of the chff. The ice melts during the day, and the next night the expansion of the freezing water pushes the loosened mass farther from the parent cliff. The process is repeated again and again until there finally comes a time when the mass is pushed to a position from which it falls when released by the melting ice. Many a mountain climber has hastily sought shelter from such faUing rocks and counted himself fortunate when they went skirtling harmlessly to one side of him on their way down the mountain side. At altitudes where the ice melts slowly, this danger is minimized. Naturally it is increased on a warm day, when the ice holding the hanging masses melts rapidly. The loosening of these rocks illustrates the action in the less spec- tacular but far more important work of frost. All rocks are poroiia. BOCKY MOUNTAIN NATIONAL PARK. 25 some more so than others. Water makes its way into the pores — into the large ones under the force of gravity and into the smaller ones under the force of capiUaxy attraction. In some of the spaces thus filled the water is so confined that when it freezes and expands it breaks the rock asunder. When this process is repeated often enough the rock crumbles. The finer it is broken up the better opportunity have the chemical agents of operating upon it. Thus the frost and the chemical solutions cooperate in transforming the rocks to soU. ' Probably every tourist in the Eocky Mountain National Park has noticed the pink angular gravel which covers the surface and makes excellent roads but which makes walking difiicult where it is too deep. This material is due chiefly to the action of frost on the granite. The pink fragments are crystals of feldspar, a crystalline mineral in the granite which has the property of parting in two directions nearly at right angles to each other. For this reason when the rock breaks up under the action of frost the feldspars break into angular fragments having flat, glistening faces, which sparkle in the sunUght — the cleavage faces of the crystal. WORK OF STREAMS. Methods of work. — The chemical work of solutions in disintegrat- ing the rocl^ and the mechanical work of frost in breaking them up would have little effect in shaping the mountains if the products of their activity were not carried away. A relatively small amount of this work is done by wind, but the disposal of rock waste faUs mainly to the streams. It is their fimction to receive the solutions of mineral matter and the smaller fragments of rock and to transport them to the sea. If the particles are small enough they remain suspended for a time, rendering the water turbid, and may be trans- ported for long distances down a stream before finding temporary lodgment along its course. The larger pieces of broken rock, such as bowlders, pebbles, and sand, take shorter journeys. They are moved along the bed of the stream always farther and farther downstream until they are ground to powder. Also in the course of their passage they scour the rocks passed over. The streams do actual cutting by roUing pebbles along the bottom and by scouring their beds with the mud and sand held in suspension, but in ordinary cases the mechanical work of streams is subordinate to their work of transportation. In streams where muddy water passes through rock channels, such, for example, as the Colorado Eiver in its passage through Grand Canyon, the abrasive work is at a maximum, while in streams where the water is clear its abrasive work is reduced practically to nothing. A notable example of this is seen at Niagara Falls, where the clear water passes over the rocks without so much even as keeping them free from unicellular plants which grow on their surface and form a green coating. 26 KOCKY MOUNTAIN NATIONAL PARK. Ordinarily streams are inspected when the water is clear and doing little work, but the cutting is accomplished principally during times of flood when the water is muddy. Particles of mud and grains of sand are carried downstream in endless procession, each particle doing its minute part in cutting away the rock. Some, on gazing into a magnificent gorge in the rocks, are content with the enig- matical statement that it was "gnawed out by the tooth of time." Others are interested in knowing that the teeth which did the gnaw- ing were the grains of sand set in the jaws of every flood. Maj. Powell, who conducted the famous exploration of the Grand Canyon, had imphcit faith in the ability of these minute grains to accomplish great results. Many have marveled at the temerity shown by him and his daring associates in entering a canyon with walls a mile high, from which there was no exit except at the mouth, without knowing what falls were likely to be encountered. But Powell had observed that the water of Colorado Kiver is always muddy and his mental insight had convinced him that waterfalls are not to be expected in a muddy river. Such falls as may have existed there at one time had long ago been worn down by the myriads of sand grains which had passed over them. His faith in the efl&ciency of these minute agents of erosion was such that he staked his life on their accompHshment. But even in a stream which is perpetually muddy, like the Colo- rado River, the abrasive work is subordinate to the work of trans- portation. Water descends in the form of rain so quietly that we think httle of the work that it may accomphsh. Parts of the rain water gather m streamlets and pick up small particles of mud and sand that lie in its way and join other streamlets similarly laden to form a brook. The water of the stronger current of the brook gathers still more of the loose material and carries it along in its passage down the river on its way to the sea. Other parts of the rain enter the rock and dissolve portions of it, as already described, and these in time find their way downstream, together with the mud. Every year the streams of the United States carry to the sea about 270,000,000 tons of dissolved mineral matter and 513,000,000 tons of suspended matter, such as silt and mud. The rate at which streams work is influenced by many conditions, such as their rapidity of flow and the character of the country drained by them. On an average the surface of North America is lowered at the rate of 1 foot in about 9,000 years. It has been esti- mated that if this erosive action of the streams of the United States could have been concentrated on the Isthmus of Panama it would have dug in about 73 days the canal which has just been completed after 10 years' work with the most powerful appliances yet devised by man. EOCKY MOUNTAIN NATIONAL PAEK. 27 Streams of 'park exceptional. — Every visitor to the Eocky Mountain Rational Park has observed thatjthe^treams are remarkably clear. They carry little mud, for although the force of the descending water is great its grinding action on the rocks is slight because of the want of particles held in suspension. These energetic streams are ac- complishing relatively little at present toward tte shaping of the mountains. They constitute an exception to the general rule, and ihere is a special reason for this exception. Jlie, rocks along the streams are only slightly disintegrated. Most of them have a fresh, hard surface. The reason for this hes in the recent glaciation which is described in the following section under work of ice. The ice re- moved the soft weathered parts, and the time that has elapsed since the glaciers disappeared has not been long enough for the rocks to decay to such an extent that they furnish large quantities of mud and sand. However, it has not always been thus, nor wiU it always remain thus. In time the fresh faces of the glaciated rocks will weather and the normal conditions of an unglaciated region will be reestablished. Stripjying of the mountains. — Through the long ages during which the mountains have been struggling to rise vast quantities of rock waste have been carried from them by the streams. In the dim past, after the close of the Cretaceous period, as soon as they had lifted their heads from the sea, they were attacked by rain, streams, and chemical solutions, so that even though the vertical movement totaled many thousands of feet the mountaios may not have been greater at any time in the past than they are now. The first work of erosion was the removal of the relatively soft sedimentary rocks which at first extended over the site of the grow- ing motmtains. These rocks were thousands of feet thick, and their removal was no small task. Also the task was made difficult and the time of its accomplishment lengthened by floods of molten rock poured out on the surface. These were removed, together with the sedimentary rocks. During this early period of erosion not only were the thousands of feet of sedimentary rock and the sheets of hardened lava removed, but the underlying crystalline rocks were themselves deeply eroded. Some time early in the Tertiary period (see table of geologic time, p. 20) the forces of erosion seem to have prevailed over the mountain-making forces, and the young mountains were reduced to a rolling plain, known technically as a peneplain, or an "almost plain," and to relatively low hUls with gently inclined slopes and broad, shallow valleys. The highest hiQs of that day may have stood 2,000 feet or even more above the general level of the peneplain. Few definite statements can be made concerning this old plain until it is studied in detail. 28 EOCKY MOUNTAIN NATIONAL PARK. An old plain of erosion. — Later, when the mountains were raised still farther, the peneplain was hfted and the rising mass of rock was again deeply carved into mountains and valleys, but the raised surface has not been entirely destroyed. So many renanants of it remain that from a distance the tops of the mountains have the appearance of forming an even-crested ridge (see PI. VII) . Remnants of it remain on Flattop Mountain (PI. IX, p. 34) and in many other places near the top of the range. It shows conspicuously near the head of Forest Canyon (PI. XXII, B, p. 54) and above Hallett Glacier (PI. XVI, £, p. 49) . But the largest and most plainly recognizable rem- nant stretches out several mUes on either side of Flattop Mountain. This ancient plain will be referred to so often in the descriptions which follow that a name for it seems desirable, and I propose to call it the Flattop Peneplain. A characteristic view of it is given in Plate IX (p. 34). If this high-altitude plain were now restored from such remnants as remain, it would seem as if the surface was very uneven. Mountains of considerable height rise steeply from the general level (see Hallett Peak, PI. IX, p. 34), but it is not now known how many of the irregularities of the surface are due to incomplete erosion when the old plain was formed and how many of them are due to faulting and to warping of the surface during the process of elevation. About the time that this ancient plain was forming the volcanic forces again were busy, and floods of molten rocks similar to those previously mentioned were poured out on the sm^ace. These har- dened on coohng into resistant rocks, and nearly all were eroded away; but one large mass remains in Specimen Mountain, which consists of beds made up of lava flows, fragmental igneous rock, and bowlders of the older mountain rock. Many periods of uplift. — There were several stages of mountain uplift, altematiag with long periods of relative cessation of move- ment, during which the erosional forces gained ascendancy ovei' the elevating forces. During one of the long periods of erosion the mo\mtain region was reduced in many places to a nearly plane surface. This surface has been studied in the regions south of the Rocky Mountain National Park, where it has been called the Rocky Moun- tain Peneplain. The mountains of Estes Park rise to a general level (see PI. VII), which may be a part of this peneplaia.^^ StiU later streams cut deeply into this plain, forming the present broad valleys, such as Estes Park, and shaping the moimtains into something like their present form. Thus the mountains were shaped and the valleys dug mainly by water. The final shaping of the high peaks and the excavating of the gorges in the sides of them were done by ice. The glacial cirques, the rock-walled gorges, the pinnacled summits, the crested ridges, and many of the other greatly admired features of the landscape are the result of the intensive action of the ice during a relatively A. VIEW FROM PROSPECT MOUTsTAIN ^^T:STWARD OVER ESTES PARK. Showing the near-by mountains rising to a level which is essentially the same as that of the so-called Rocky Mountain peneplain of areas farther south. 1, Gianttrack Mountain; 2, Thomp Canyon; 8, The Needles; 9, Stanley Hotel; 10, Twin Owls. B. VIEW FROM THE HILL AT MORAINE PARK, WHICH APPEARS IN THE VIEW ABOVE, BETWEEN GIANTTRACK Showing the melting basin of Thompson Glacier (Moraine Park) with its lateral moraines in the foreground and the high range beyond, at whose relatively even crest are numerous remnants Mortune of Thompson Glacier; 4, Moraine of Bartholf Glacier; 5, Taylor Peak; 6, Otis Peak; 7, Hallett Peak; 8, Flattop Mountain; 9, Moraine Park; 10, Gorge of Thompson Gla Chapin; 15, Mount Chiquita; 16, Ypsilon Mountain; 17, Mount Fairchild; 18, Highline Drive. PANORAMAS OF ESTES PARK AND OF THE HIGH MOUNTAINS TO. THE Photographs by Frank W. Byerly. PLATE VTI lOSPECT MOUNTAIN ^^^:ST\VAIyD OVER ESTES PARK. eplain of areas farther south. 1, Gianttrack Mountain; 2, Thompson Canyon; 3, Oldman Mountain; 4, Deer Mountain; 5, FaU River; 6, Castle Mountain; 7, Black 8, The Needles; 9, Stanley Hotel; 10, Twin Owls. APPEARS IN THE VIEW ABOVE, BETW-EEN GIANTTRACK MOUNTAIN AND DEER MOUNTAIN. range beyond, at whose relatively even crest are numerous remnants of an old plain here called the Flattop peneplain. 1, Ix)ngs Peak; 2, Bartholf Park; 3, South Flattop Mountain; 9, Moraine Park; 10, Gorge of Thompson Glacier; 11, Stones Peak; 12, North Moraine of Thompson Glacier; 13, Trail Ridge; 14, Mount 'ARK AND OF THE HIGH MOUNTAINS TO .THE WEST. Photographs by Frank W. Byerly. EOCKY MOUNTAIN NATIONAL PARK. 29 short period. The work of the glaciers in shaping the mountains was accomplished in relatively recent time, hence the resiilts are conspicuous for the same reason that objects close to us intrude them- selves upon our attention. But in reahty these sink into insignifi- cance when compared to the stupendous results accompUshed by water in shaping the landscape. WOKK OF ICE. WHEN AND WHY GLACIEBS FORM. The most spectacular features of the landscape in the Eocky Moxintain National Park are due to ice. This is because the gla- ciation of this region was the last important event in its geologic history. The Great Ice Age dates back beyond the origin of human history, but in terms of geologic time it was very recent. The glacia- tion of the mountains was the last geologic event of the region, and the glacial epoch has in reahty not yet closed for the higher parts of the park, where small glaciers still exist. The popular notion that glaciers and fields of perpetual snow are due to excessively low temperature is not wholly correct. However, in order that the masses of snow and ice may endm-e, the average yearly temperature of the region must be low enough that the snow- fall of winter does not all melt in summer. The one condition neces- sary for a snow field is an excess of accumulation over waste. Those of the mountains are due chiefly to drifting. In a region where there is heavy snowfall dm-ing the winter the snow fields endure throughout the summer at much lower altitudes than where the snowfall is hght, for the obvious reason that the heat of smnmer, although it may be intense, can not melt all of the snow. On Mount Rainier, in the State of Washington, where the annual snowfall exceeds 20 feet, the glacial ice extends down within 3,960 feet of sea level, but in the Rocky Mountain National Park, where the annual snowfall is less than 10 feet, the glaciers extend little lower than 12,000 feet above sea level. LIVING GLACIERS. When the annual accumulation of snow is greater for any reason than the annual melting, snow fields are formed. The surface snow soon changes from the flaky form to a granular form, and these gran- ules consohdate into ice. When this granular ice accumulates to a sufficient depth it begins to move and becomes a glacier. The differ- ence between a glacier and other masses of ice seems to depend on motion. Profs. Chamberlin and SaUsbury' state that — 'TBrittle and resistant asiceseemSjit exhibits under proper conditions some of the out- ward characteristics of a plastic substance. Thus it may be made to change its form and may even be molded into almost any desired shape, if carefully subjected to suffi- cient pressure steadily applied through long intervals of time. These changes may be brought about without visible fracture and have been thought to point to a viscous » Chamberlin, T. C, and Salisbury, E. D., Geology, vol. 1, pp. 236, 237, 1004. 30 EOCKY MOUNTAIN NATIONAL PARK. condition of the ice. There is much reason, however, * * * to question this interpretation of the ultimate nature of the movement. Whatever tliis may be, the mass result of the movement in a field of ice is comparable, in a superficial way at least, to that which would be brought about if the ice were capable of moving like a viscous liquid, the motion taHng place with extreme slowness. This motion of the ice in an ice field is glacier motion and ice thus moving is glacier ice. When the moTing ice is confined to a ralley or gorge it is known as a valley glacier. These are often called alpine glaciers, because they were first studied in detail in the Alps. Probably the nearest ap- proach to a typical valley or alpine glacier in the Eocky Mountain National Park is found in Andrews Glacier. (PI. XXXI, p. 68.) In some places the snow accumulates in a sheltered nook on a cliff and forms a small and often steeply inclined mass of ice called a cliff glacier. (PI. XXIX, p. 67.) Such a mass of ice seems to be insecure and is sometimes called a hanging glacier. Although movement is the essential character of a glacier, there seems to be no Hmiting rate of movement. Hence, as a mass of ice once large and active gradually diminishes it is difficult, if not im- possible, to determine when it ceases to be a glacier. The question is especially pertinent in the Rocky Moimtain National Park, where several bodies of ice are now at the critical stage between glacier and snow field. A few of these bodies have perceptible movement and are genuine glaciers. Others move internaittently and are there- fore glaciers at certain times and not glaciers at other times,* but the greater number are not known to have measTirable motion — at least their rate of motion, if they have any, has not been determined and is so shght that it is not made apparent by any recognized external signs. The bodies of ice in this park now recognized as true glaciers are Hallett Glacier, Sprague Glacier, TyndaU Glacier, Andrews Glacier, and Taylor Glacier. A mile south of the park are two splendid masses known as the St. Vrain Glaciers, and about 10 miles farther south hes Arapahoe Glacier, the finest body of glacial ice in the southern Rocky Mountains. It was Hallett Glacier that gave rise several years ago to a con- troversy as to what constitutes a glacier. The definite question arose, "Is Hallett Glacier a glacier?" In 1884 Mr. W. L. Hallett, of Colorado Springs, for whom this body of ice was named, discovered a crevasse in it. Crevasses are common in glaciers and in^iicate motion of the ice. HaUett's discovery was used as proof ^ that a ' In a letter to the writer dated July 25, 1916, Enos A. Mills states: "I have made three measurements on the small ice field that lies on the eastern wall of Longs Peak above Chasm Lake. In 1909 1 made a 60-day test. The movement made was about 0.07 inch per day. In 1908 a 30-day test showed a movement of about 0.04 inch per day. A 10-day test in 1907 showed no perceptible movement. " This ice field was measured also by Chapin in 1888, 1 think, and he reported no perceptible movement. " A 15-day test on Sprague Glacier in 1906 showed a movement of 0.08 inch per day. In 1896 Hallett Glacier showed a movement of 1.01 inches per day, and in 1907 its movement was 0.06 inch per day. All these meas- urements were made in the autumn." 2 Stone, G. H., A live glacier on Hagues Peak, Colo.: Science, vol. 10, pp. 153, 154, 1887. PLATE VIII MAP OF THE ROCKY MOUNTAIN NATIONAL PARK AS IT MIGHT HAVE APPEARED DURING THE LAST STAGE 'of GLACIATION in THE GREAT ICE AGE Outlines of the glaciers approximate Scale 012345678 9 lOMHes EOCKY MOUNTAIN NATIONAL PARK. 31 true glacier had been discovered in Colorado. This raised the ques- tion of the hkenesses and differences between snow fields and glaciers. The question was discussed by S. F. Emmons,^ a well-known geologist, who pointed out that the present masses of ice in the Rocky Moun- tains are mere shadows of the former glaciers and argued that HaUett Glacier and similar masses of ice are not true glaciers. Nevertheless it has continued to be called a glacier, and, according to the definition previously given, several of the less well-known bodies of ice naturally fall with it into the class of true glaciers. ANCIENT GLACIERS. Whether or not the above conclusion is accepted as final there is no doubt of the existence of active glaciers in this territory in times past. Evidences of these are found in many places. Conspicuous among them are the lateral, terminal, and ground moraines, the smoothly rounded rock surfaces, polished and striated bowlders, steep-walled gorges, U-shaped valleys, and pocket lakes. _, In the moraines are bowlders, cobbles, pebbles, sand, and clay intermingled. This physical heterogeneity is one of the most dis- tinctive characteristics of morainal material and therefore one of the best evidences of the former existence of glaciers. AH the dis- tinctive marks of the ancient glaciers are found in great perfection, so that the park has been called a primer of glacial geology. The details of the several glaciated areas are enumerated in the descrip- tions that follow under the heading "The park as seen from the trails" (p. 45). ^ There appear to be two stages of glaciation represented in this park — an older one of which little is now known and a younger one called the Wisconsin stage, because it seems to correspond in time with the last stage of continental glaciation, which is typically developed in Wisconsia and was named for that State. Little need be said at this time of the older stage, for the proofs of its existence are not entirely conclusive. Apparently such broad open valleys as Estes Park and Tahosa VaUey were shaped by glacial ice. They have the broad floors, the precipitous walls (PI. XV, A, p. 48), aid the perched lakes which characterize glacial valleys, but they lie outside of the area affected by the glaciers of the Wisconsin stage. During the younger or Wisconsin stage of glaciation the ice accumulated in the valleys previously formed by the streams — and perhaps shaped to some extent by the older glaciers — and pushed its way from the high mountains down these valleys to altitudes of about 8,000 feet. The areas occupied by the ice are plainly marked and could be mapped accurately with little difficulty. But this mapping would require a large amount of detailed work and 1 Emmons, S. F., On glaciers in the Eocky Mountains: Colorado Sci. Soc, Proc. vol. 2, pp. 211, 227, 1888. 32 EOCKY MOUNTAIN NATIONAL PARK. hsis not yet been done. The accompanying illustration (PI. VIII) outlines the glaciated areas with sufficient accuracy for present purposes. The five named glaciers are outlined more accurately than those in the western and northern parts of the park. The areas occupied by the latter are not easily traversed at present for want of good trails. It is beyond question, however, that the high-altitude valleys and gorges were all occupied by glacial ice, although the out- lines as shown in the figure are only approximate. Fall River Glacier. — The body of ice which occupied the upper part of the Fall Kiver drainage area had a maximum length of nearly 10 miles and a width of more "than 7 miles. Its principal lobe orig- inated in the high mountains to the west and filled the main valley. Its principal tributary originated on Hagues Peak and filled the valleys between this peak and Mount Chapin. The Fall River lobe seems to have been much more powerfiil than the other lobes of ice and so modified its course that the valley of Roaring River was left "hanging" about 500 feet above Fall River. The ice of the united lobes was pushed through Horseshoe Park, where it built lateral moraines along its northern and southern margins about 900 feet above the present floor of the valley. Each of these conspicuous ridges of loose bowlders is separated from the solid mountain rock on either side of the park by a narrow trough. Horseshoe Park is the melting basin of Fall River Glacier. Here the supply of ice which moved down the steep gorges just equaled the waste due to melting. For this reason aU the fragments of rock borne by the glacier were dropped here as the ice melted from under them. The fragments which fell from the sides piled up in lateral moraines. Some of those in the central parts of the glacier were carried downstream to the end of the ice and deposited as the terminal moraine. Others lodged at the bottom of the glacier to form the ground moraine and were overridden by the ice, thus forming the relatively level floor of Horseshoe Park. Before the Great Ice Age Horseshoe Park was doubtless a part of an ordinary V-shaped valley like that between Deer Mountain and McGregor Mountain east of the terminal moraine^ but the narrow lower part of the " V " was filled with fragmental rock. This narrow part of the valley east of Horseshoe Park would appear now as wide as that park if it were filled to the same exteht. The quantity of morainal material in the floor and walls of Horseshoe Park indicates that the ice occupied it for a long time. Also the smoothness of the floor and the absence of large piles of bowlders indicate that the retreat of the glacier was relatively rapid when the ice finally melted. Thompson Glacier. — ^Two large glaciers formed on the headwaters of Thompson River. The largest one, heading in Forest Canyon EOOKY MOUNTAIN NATIONAL PABK. 33 and its tributary gorges, was about 15 miles long. It had several tributary lobes from the Continental Divide, among them one in Hayden Canyon, one ia Spruce Canyon, at the head of which now lies Sprague Glacier (PI. XXV, p. 60), and one in Odessa Gorge. The ice from the imited lobes crept down the valley of the Thompson, overriding such minor ridges as that north of Cub Lake, and halted in Moraine Park. This park is similar in nature and origin to Horse- shoe Park and is the melting basin of Thompson Glacier. To j udge from results, Thompson Glacier was a vigorous one . Forest Canyon and the tributary gorges just mentioned contain numerous and forceful reminders of its power. Many cirques and deep gorges were scooped out of the solid rock by it, and rounded bowlders were carried down to Moraine Park, where the valley floor was built up by ground moraine and the lateral moraines raised to a height of nearly 1,000 feet. It would be difficult to find a better or more conspicuous example of a lateral moraine than the even-crested ridge south of Moraine Park. Bariholf Glacier. — ^The glacier which descended through Bartholf Park was a relatively short one, never exceeding 8 mUes in length. However, it originated on the highest moimtain in the park and its gradient, or average slope of bed, was steep, hence its gouging action was vigorous. The principal lobe of ice occupied Glacier Gorge. Another scarcely less vigorous lobe occupied Loch Vale and headed in the cirques now occupied by Taylor Glacier and Andrews Glacier. Less extensive but scarcely less vigorous lobes occupied the gorges south of Flattop Moimtain, in one of which Tyndall Glacier reposes. These lobes of moving ice joined in a grand mM6e in Bartholf Park. The relatively small tongue of ice from the Flattop region tended to move eastward but was crowded toward the north by the more power- ful mass from Glacier Gorge and Loch Vale. Hence most of the ice-borne material was carried north of the park and piled up in the great moraine, on the top of which is Bierstadt Lake. This moraine occupies most of the space between Milk Creek and Glacier Creek and is more than a mUe wide. Its thickness is not definitely known, but it rises 900 feet or more above the floor of Bartholf Park, and this floor is itself built up to some unknown extent by ground moraine. Mills Glacier. — ^MiUs Glacier seems like a small one when compared with others (see PL VIII). It was not more than 4 miles long and a mUe wide, but the area occupied by it is one. of the most accessible and easily observed of those occupied by the ancient glaciers in the park. The entire site of this glacier can be seen from a single position. From Twin Sisters, east of Longs Peak, The Chasm, or cirque in which this glacier originated, and the glacial trough and moraines are spread out before the observer as on a map (PI. XXXV, A, p. 71). 99305°— 17 3 34 BOCKY MOUNTAIN NATIONAL PAKK. For some reason not now known, this glacier differed from the others described in not building at its lower end a melting basin or moraine-inclosed park. In the other four the parklike melting basins lie between the most conspicuous portions of the lateral moraines. In the case of Mills Glacier the most prominent portions of the laterals inclose only a narrow trough. There is some doubt as to the relation of the moraines of Mills Glacier to those of the possibly older glacier which is supposed to have filled Tahosa Valley. In this valley are basins now filled with boggy material and accumulations of glacial debris, which might be either old till or outwash material from Mills Glacier. Also outside of the conspicuous ridge called Mills Moraine is at least one less prominent morainal ridge, which denotes that this glacier covered a somewhat larger area during the early part of its existence than it did later. As the bowlders of this outer ridge are not notably more weathered than those of the higher inner ridge, the outer moraine seems to belong to the Wisconsin stage of glacia- tion rather than to the earlier stage. Wild Basin Glacier. — The body of ice which formed at the head of the St. Vrain drainage area was the most sjnmmetrical of the five named glaciers of the Wisconsin stage of glaciation. It filled Wild Basin to a width of about 6 miles, heading in the numerous gorges of the high range from Longs Peak to Ogalalla Peak. It extended nearly 9 miles down the valley of the North St. Vrain, forming a long melting basin between Copeland Moraine on the north and an equally prominent lateral on the south (PL XLIII, B, p. 81). Cope- land Lake lies within this basin, on a shelf of morainal material a few feet above the general level of the valley floor, and the stage road be- tween Ward and Estes Park crosses the basin near the eastern end. The terminal moraine lies east of the road near the junction of Horse Creek and the St. Vrain. Glaciers of North ForTc and its tributaries. — Little is known of the geology west of the Continental Divide. The evidences of former glaciers were seen in many places and the general outlines of the ancient ice are indicated by the topography, but the boundaries shown in Plate VIII (p. 30), are only approximate. The essential facts relating to the old glaciers of this region have long been known from the description of Archibald E. Marvine in the report of the United States Geological and Geograpliical Survey of the Territories for the year 1873, from which the following account is chiefly adapted: The floor of Grand Valley consists of terminal and ground moraine as far south as the southern extremity of the Rocky Moimtain National Park. Throughout most of its length the floor consists of ground moraine or material left at the bottom of the glacier and leveled off by the ice riding over it. Thus was formed the ' ' Meadows ' ' PLATE IX THE FLATTOP PENEPLAIN. View of a part of Flattop Mountcun, showing Hallett Peak in the middle ground and the square head of Longs Peak in the distange to the left. The gently rolling sur- face covering several square miles at altitudes near 1,200 feet is a remnant of a surface of erosion which once extended continuously over the site of the Rocky Mountain National Park when the mountains were much lower than they are now. During the elevation of these mountains this surface was raised and in most places was destroyed by later erosion. It suffered especially from the glaciers, which gnawed great holes in the sides of the mountains, but it is still recognizable in many places. Photograph by Frank W. Byerly. PLATE X NARROW PLACES IN THE NARROWS OF THOMPSON CANYON. On the road between Loveland and Estes Park there are many places where there is scarcely room for the road between the river and the precipitous walls. The rocks of these walls were originally formed of sand laid down in horizontal layers. The sand consolidated and the layers were upturned to their present steeply in- clined position when the mountains were elevated. Upper left, Looking down the canyon toward the foothills and plains; upper right, Upturned layers of pre- Cambrian quartzite; lower, Layers of red rocks in the foothills upturned against the mountains. Photographs by Willis T. Lee, United States Geological Survey. KOCKY MOUNTAIN NATIONAL PARK. 35 or flat floor over which the river now winds, in serpentine course, among the swamps, grassy meadows, and dense thickets of brush. From the southern extremity of the moraine northward for several nules the meadows are interrupted by ridges and irregularly shaped hiUs made up of rock debris deposited by the ancient glaciers. They are roughly semicircular in form and north of Grand Lake cross the valley somewhat regularly. These constitute the terminal moraines of the glacier which occupied the valley of the North Fork of Grand River. In its halting retreat the glacier built a succession of ter- minal moraines, reaching altitudes of 300 or 400 feet above the level of the meadows. Each semicircular ridge across the valley repre- sents a halt at the front of the retreating glacier. Their surface is uneven, there being in some places abrupt depressions down to 60 feet in depth, having no outlet. Some of these are occupied by undrained lakes. West of Grand Lake is a semicircular ridge situ- ated between the North Fork and the drainage from the lake. This is a medial moraine formed where the glacier of North Fork Valley joined the glacier from the gorges which converge in Grand Lake. The latter- seems to have extended down the Great Valley several mUes, but it is not possible, without more detailed field study, to say whether the southernmost ridges are moraines of the North Fork Glacier or the Grand Lake glaciers, or a combination of both. There are, however, three fairly weU defined ridges which seem to repre- sent stages in the retreat of the glacier that passed through Grand Lake. The western end of the lake is inclosed by a low morainal ridge. It is narrow and steep sided, ranging in height from a few feet to 100 feet or more, and offers choice sites for summer cottages. It represents a relatively short halt in the retreat of the glacier. The next older terminal moraine crosses the valley about 2 nules south of the outlet of the lake. The North Fork, which flows west of the medial moraine previously described, turns sharply to the north, cutting through the low but well-defined ridge of this moraine, and flows in an easterly direction north of the ridge for more than a mile to its junction with the Grand Lake drainage, where the com- bined stream breaks again through the moraine. Between this gap ajid the lake the ridge is a lateral moraine, attaining an altitude of 800 feet or more above the level of the lake. A still older and also more prominent terminal moraine lies nearly a mile farther south, the two separated from each other by a meadow. The river breaks through this ridge and enters a narrow canyon cut in the granitic rock. The river which had obviously occupied the main valley previous to the Great Ice Age apparently was crowded out of its former course by the accumulation of ice-borne material. When the glacier ice melted the river found the lowest 36 EOCKY MOXJKTAIN UrATrOlSrAL PAEK. course at the side of the moraine and, in place of reexcavating its old valley, cut a new one through the solid rock. Good exposures of the rocks in the moraines are not numerous. These rocks consist of schist and granite, which decompose readily on exposure. The morainal masses are covered with scanty soil, and 'iplu ■'•.■.;••; r'-'B.M-astr"' t:l MtEnentah \Gra '■hi Shadovv"Mf ■v '. Ranger Station - i y cf/^ MtBryar f^n I05"50' 4M1LES N;;^- Glacial moraine Meadow Fig. 5.— Sketcli map showing the glacial moraines in the valley of North Fork of Grand River near Grand Lake, Colo. on them is a thick growth of pines. In ma.ny places the lodgepole pines grow so close together that passage across the moraines is almost impossible. Traversing these thickets is particvilarly annoy- ing when they have been partly destroyed by wind or fire, the fallen trees making the thickets almost impenetrable. EOCKY MOUNTAIIT NATIONAL PAEK. 3V Glaciers in the nortJiern part of the parlc. — It is known that the valleys in the northern part of the Eocky Mountain National Park, such as those of the Cache la Poudre and its tributaries, are gla- ciated, but I have seen them only from a distance, and the outhnes of the glacial ice shown in Plate VIII (p. 30) have been drawn chiefly from topographic evidence. The boundaries may be mate- rially changed when these areas are examined in detail. HOW THE GLACIERS WORKED. The kind of work performed by the ice in shaping the mountains was much the same in each of the glaciers, and if we can see in imag- ination how a bowlder was formed, what work it did, and how it was carried to its present resting place, we wiU come close to an under- standing of glacial erosion. As we stand at the head of one of the gorges and gaze down its rock-walled trough we may easily picture the great river of ice that formerly cascaded over its cHffs, gnawing at the sides of the moimtains, plucking out their rock ribs, grinding and pohshing the rocks, and sweeping away the debris. ii^?C-s^^f:S' A. B. Fia. 6.— A, Sketch ot stream-cut valley; B, Sketch of same valley after modification by glaciation. Along the cliffs above the ice, and as far below its smface as water wiU freeze and thaw, fragments of rock large and small are loosened. Those frora the overhanging cliffs fall on the ice and are carried on it down the valley. Those from below the surface of the ice are plucked from the walls and held within the ice, where they serve as the cut- ting tools which wear down the floor of the gorge. _A thickness of 2,000 feet is a conservative estimate for the ice which filled many of the cirques and gorges of this park. A mass of ice of this thickness exerts a pressure of 56 tons on each square foot of its bed. The deeper the ice the stronger is its hold on the rocks and the greater is its ability to tear frs,gments of it from the walls and from the floor. The fragments of rock near the bottom and sides of the moving mass are held as in the grip of a vise. This rock-shod ice under pressure from above acts like a giant rasp, plucking away loosened fragments, scouring, grindiag, and polishing the rocks over which it moves. 38 ROCKY MOUNTAIN NATIONAL PARK. Such masses of ice do not adjust themselves readily to the irregu- larities of the valleys which they occupy. In consequence of this, more than ordinary force is exerted on the projecting mountain spurs and opposing ledges and these are worn away relatively fast. Hence a glacial trough has fewer irregularities than a stream-worn valley. Also, since the work of the ice increases with pressure, the bottom of the trough undergoes great modification. A glacial gorge has a characteristic U-shaped profile and is distinguishable by this feature from a stream-cut valley, which is characterized by a V-shaped profile (see fig. 6). In an alpine glacier the ice always moves down the valley. It never retreats. If the ice at the lower end melts faster than it is renewed from above the glacier may retreat, but the ice of the gla- cier moves always forward. Hence we may properly speak of a retreating glacier, but not of retreating ice. For this reason whether the glacier is advancing or retreating it is always bearing a load of rock debris forward. That borne to the end of the ice is dropped as the ice melts from \mder it and forms the terminal moraine; some lodges at the bottom behind the terminal, allowing the ice to ride over it, and is called ground moraine; and some accumulates at the sides asJLateral moraine. APPROACHES TO THE PARK. LOVELAND TO ESTES PARK. Loveland is the railroad station on the Colorado & Southern Rail- way near the mouth of Thompson Canyon, where the tourist destined for the Rocky Mountain National Park leaves the railroad and begins the stage journey. On leaving the railroad he travels for several miles between the orchards and through the meadows of the irri- gated plain. Just east of the foothOls the road traverses a short rock cut, in the sides of which may be found the petrified shells of extinct species of marine moUusks. These clamlike creatures flourished here during the Cretaceous period, when this region was under the sea. The foothills consist of a series of ridges separated by troughlike depressions lying in a general north and south direction along the mountain front. They were formed by erosion of the upturned strata. The sedimentary rocks of this region were formed in a nearly horizontal position, some of stream-laid deposits, others of sediments deposited in sea water. "When the mountains were elevated these horizontal layers were bent upward, so that near the line of flexure they are steeply inclined toward the plains. Much of the uplifted part has been worn away by rain, frost, and stream. The soft layers were worn down, more rapidly than the hard ones and valleys were formed where the softer strata outcrop. The harder layers were worn down more slowly, hence they outcrop in ridges. KOOKY MOUNTAIN NATIONAL PARK. 39 Thompson River has cut its way eastward through these ridges, thus forming an easy passage utilized by the road. The first promi- nent hogback or sharp ridge consists of -Dakota sandstone.^ It is prominent because the sand is cemented together firmly to form a quartzite which strongly resists erosion. The Morrison formation described (p. 16) as containing fossil bones of huge dinosam's out- crops in the brush-covered slope west of the Dakota hogback. Then , in order westward are the several layers of red rocks of Carboniferous age (see table, p. 20). The upper part of these red beds, kno\\Ti as the Lykins formation, contains a bed of gypsum. In traveling up the canyon we pass a miU where cement plaster, a product resembling plaster of Paris, is manufactured from this gyp- sum. In the middle part of the red beds is a thick layer of hard cross-bedded hght-red sandstone, known as the Lyons sandstone, which is described on page 41. A little farther to the west is a great series of still older red sedimentary rocks which lie on the crystal- hnes of the mountains proper (PI. X, p. 35). The geologist sees here in the contact of the red beds with the crystalline rocks the evidence of a long period of unrecorded time. The rocks at the base of the red beds are Carboniferous in age (see table, p. 20), while the crystallines on which they he are older than Cambrian. This line of contact therefore represents four geologic periods and a length of time as great as that represented by all the sediments of the foothiU region, or perhaps even greater. Soon after reaching the crystalline rocks the canyon proper of Thompson River is entered. The first deep, narrow part of this canyon west of the foothills is known as The Narrows. It has been cut by the stream in a complex consisting of hard metamorphosed sedimentary rocks, into which werejforced many dikes and irregular masses of igneous material which now appear as coarsely crystalline rocks of lighter color than the fine-grained sedimentaries. The strata are upturned steeply and in some places stand nearly vertical ^seeTl. X, p. 35). Their attitude and physical characteristics give rise to the interesting features for which this canyon is justly famous. In cutting its passage the river has naturally sought the line of least resistance. When it strikes a layer of unusually hard rock it turns abruptly to one side, passes around the obstruction, and doubles back upon itself, following in some places an intricately winding course. The canyon walls are here characterized by sharp projecting edges of rock, and the top by pinnacles (see PI. X), of varying form and height. In many places the walls rise sheer from the stream for himdreds of feet and are entirely wanting in • TWs sandstone was named for Dakota City, Nebr. It is exposed in many places throughout the Eocky Mountain region and extends from New Mexico northward for 1,000 miles or more. It underlies the Great Plains and comes to the surface again in the Mississippi Valley many hundreds of miles east of the moun- tains. The pores of the rock are filled with water, which is reached by artesian wells in 11 States. 40 EOCKY MOUNTAIN NATIONAL PAEK. vegetable growtli. In other places trees have gained a precarious foothold by sending their roots into rock crevices, and we wonder how they survive. The bottom of the canyon is little wider than the stream, and in many places the roadway has been bl'asted from the cliil or is held up on the streamward side by a retaining wall. At the mouth of the canyon is a beautiful waterfall at the spill- way of the reservoir of the Loveland waterworks. Farther upstream the granitic rock which was forced into the sedimentary rock during ages long past is more abundant, and because it weathers more readily than the quartzite, the walls of the canyon here change from sheer precipices to craggy, forested slopes, and finally the canyon widens into an open mountain valley. Near the forks of the Thompson the rock is a coarse crystalline granite, much of which Jbasthejorm known as pegmatite and consists chiefly of large crystals of pink feldspar, hght-colored quartz, and crystals of mica, popularly, though erroneously, called isinglass. Crystals of this mineral may be found as large as one's hand and several inches thick, which can be split into thousands of thia transparent sheets. In this part of the canyon are many picturesque rapids (PI. XI, where the water leaps and plunges from rock to rock and lashes itself into foam as if in impotent rage at the innumerable obstacles to its progress. Above the forks we enter the second narrow portion of Thompson Canyon, known as The Kapids and famous for unusual beauty. The canyon walls are steep and high, but the granite of which they are composed is variable in its resistance to erosion and weathers to an infinite variety of craggy forms that contrast strongly with the great barren faces which characterize The Narrows. Also the forest trees find more favorable conditions of growth here, and the pinnacled slopes (PL XI) are decorated in a variety of patterns in many shades of green on the somber background of the weathered granite. The bowlders along the stream are smooth and polished and are worn into a variety of forms by the never-ending friction in the bed of the stream. Where the channel is straight, grooves are cut into . the rock, but where there are eddies in the current, circular depres- sions or "potholes" may be formed. One of these may be seen from the road near Linger Longer Lodge (PL XI). Probably the greatest admiration for this part of the canyon is aroused by the rapids. The canyon contains great numbers of granite bowlders worn smooth and round by the never-tiring current. Over and among them the water dashes and foams. Out of some dark brushy obscurity (PL XI) it leaps, flashes for an instant in sunlight as it breaks in spray against some rocky ob- struction, gathers its shattered parts, and passes again into ob- scurity, only to repeat the ever-varying performance again and BOCKY MOUNTAIN NATIONAL PARK. 41 again on its eventful journey, until it emerges from the moimtains and finds rest for a time in some of the numerous irrigation reservoirs on the plain. Like the tourist who leaves the humdrum existence of everyday life and enjoys a summer of imusual experience in the mountains, this water in its eternal round of change through vapor, rain, snow, and stream, has visited the park, has spent its vacation on the Snowy Range, and is now on its way back to less spectacular but more useful vocations. For this water wiU find its way through the intricate maze of irrigation ditches to the orchards and to the fields of alfalfa and sugar beets on the plains. There it wiU linger for a time and make the desert beautiful in blossom and rich in fruit. LYONS TO ESTES PARK. Lyons is the terminal of a branch of the Chicago, Burlington & Quincy Railroad, where the traveler destined for Estes Park by way of the Lyons route takes stage. Lyons is located in the foothills, in the midst of the sharp-crested ridges or "hogbacks;" composed of upturned and eroded sediment- ary rocks. The eastenmiost prominent "hogback" consists of the hard sandstone called Dakota. East of this ridge the rocks are chiefly shale which accumulated as mud in the ancient sea. Because this shale is soft and easily eroded it has been worn down to a nearly level plain, which contrasts strongly with the uneven surface in the foothOls, where hard and soft layers of rock alternate. The troughlike depression just west of the Dakota "hogback" is due to erosion in the soft rocks of the Morrison formation, named for the town of Morrison, situated about 40 miles south of Lyons. This formation contains the fossil bones of some of the most remark- able extinct animals that ever hved (see p. 17). West of this trough the ridges consist of red sandstone and shale. In their midst is a series of thick cross-bedded flaggy layers, known as the Lyons sandstone, named for the town of Lyons. This rock has been quar- ried extensively for buUdings and has furnished many flagstones for the streets of Denver and other cities of Colorado. In the sand- stone are preserved the footprints of some of the animals that roamed over this country long ages ago. The strata were formed during the life of the earHest known land animals; hence in the streets paved with these stones we literally follow ia the footsteps of the first beings that walked on land. The parklike opening in which Lyons is situated was formed by St. Vrain River cutting a passage through the red rocks. After leaving the town we follow up the river between cliffs of the red strata. To the right may be seen quarries from which flagstones are obtained. At Steamboat Rock (PI. XII, 5, p. 45), which stands 42 EOCKY MOUNTAIN NATIONAL PARK. like a dominating headland overlooking the valley, we turn to the right through a trough cut by the river along the junction of the red beds and the underlying granite. The river cut along this junction because the rocks here are softer than those on either side. The granite near the contact with the overlying sedimentary rocks is coarsely crystalline and breaks down into coarse gravelly debris. Also the lower layers of the red rocks are soft and are easily worn away. After foUowing this trough for about 2 miles we tiirn westward and plunge into the narrow canyon between walls of gray and pink granite. Some of the pink varieties are dehcately colored and may some day be valuable* as ornamental stone. Attention is divided between the rushing waters of the river on the one hand and the pre- cipitous walls and wooded slopes on the other (PI. XII, A, p. 45). On leaving the canyon we take a winding course through forested bills, which assume huge proportions as we approach Estes Park. Mount Pisgah (8,500 feet) and Mount Olympus (8,808 feet) appear at the right and Kxuger Rock (9,342 feet) at the left. As we emerge from the hills which lie between these higher summits a splendid view is obtained of the group of commanding summits that culminate in Hagues Peak (13,562 feet). WABD TO ESTES PARK. One of the approaches to the Rocky Mountain National Park is by way of Ward, a small mining town situated at the terminus of the railroad commonly known as the Switzerland Trail. Ward Hes 9,269 feet above the sea and is near the top of the once nearly level surface called the Rocky Mountain peneplain (p. 16). Over this elevated surface, now trenched by the streams, the road winds north- ward to the canyon of the Middle St. Vrain. This canyon is cut to a depth of more than 500 feet below the general level of the ancient plain. The route leads eastward down this canyon, then northeast- ward up a branch canyon to Aliens Park and the North Fork of the St. Vrain. Here we descend the lateral moraine of Wild Basin Glacier (see p. 34), cross the floor of the melting basin of this glacier, and climb the low ridge at the end of Copeland moraine — the great elon- gated hill of bowlders and smaller fragments of rock deposited at the northern edge of the old glacier. Here we are fairly within the region of the Rocky Mountain National Park, and the route farther to the north is described elsewhere (pp. 71 et seq.). One of the interesting views obtained on this trip is that of Longs Peak and the mountains surrounding it. Here is seen one of those landscape curiosities which usually arouse interest. The crest of the ridge west of Longs Peak outlined against the sky resembles the EOCKY MOUNTAIlir NATIONAL PARK. 43 profile of a human face. At the sky line is seen forehead, nose, and chin in form suggestive of the upturned face of an Indian. The eye is represented by a bank of perpetual snow. Because of this hkeness the moxintain is called Chiefs Head. From this direction as well as from the north Longs Peak and Mount Meeker appear as a conspicuous double peak. For this reason the "Arapahoe Indians called them Two Guides (nesottayah), because they are the landmarks of the whole region." ^ GRAND LAKE ROUTE. Grand Lake is the western gateway to the Eocky Mountain Na- tional Park. It is situated in the valley of North Fork of Grand River and is the largest lake in the vicuiity of the park. The valley of North Fork lies along the western margin of the park. From the heights to the east of this great valley may be obtained magnificent views of the towering peaks of the rugged Medicine Bow Mountains to the west of it (PI. XXII, A, p. 54), which some prefer to call the Never-Simamer Range, foUowtng the' nomenclature of the Arapahoe Indians, who called them nicheebeeche-nokhu (Never-no sununer). The floor of the valley is nearly flat, is beautifully wooded in many places (PI. Ill, B, p. 14), and ranges in width from about 2 miles near Grand Lake to half a mile or less farther north. From the nearly level floor of the valley the surface rises abruptly on both sides in steep, rocky slopes which merge into the great cliffs and cirques in the sides of the mountains. East of the valley the mountain slopes are heavily forested in most places below timber line, but the Medicine Bow Mountains are less generally timbered and are more attractive to those interested in the land forms produced by erosion at these high altitudes. As seen from the sotith up the great valley the slopes appear regular, but in them are munerous great gorges extending from the main vaUey to the crest of the mountains. These so break up the seeming regiilarity that when the slope is viewed from the side it appears to consist of an intricate maze of rugged peaks, serrate ridges, sharp spurs, and deep canyons. The gorges in the Medicine Bow Mountains are relatively short and steep, for the moimtain crest is only 2 to 4 miles from the center of the valley and rises about 4,000 feet above its floor. Because of this steepness the rocks have been carved into a great variety of picturesque forms, and in the absence of continuous forests these forms may be seen to good advantage. They are especially conspicuous near the head of North Fork, where the top of the Medicine Bow Range consists of a short ragged crest which reaches a maximum altitude of nearly 13,000 feet. 1 This and following notes on Indian nomenclatiu-e arc taken from a manuscript by Oliver W. Toll (see p. 11). PLATE XI. SCENES IN THE RAPIDS OF THOMPSON CANYON ON THE ROAD BETWEEN LOVELAND AND ESTES PARK. Upper, A typical scene in the depths of the canyon, where the Thompson polishes the bowlders of granite and quartzite and grinds out the cobblestones. Middle left. One of the numerous pinnacles in the wall of Thompson Canyon. Middle right, Water versus rock. Where the river plunges and dashes itself into foam on its way to the plains. Lower, A "pothole" near Linger Longer Lodge, worn in a block of granite by sand and pebbles which are kept in motion by the eddying water. Photographs by Willis T. Lee, United States Geological Survey. 44 PLATE XI THE RAPIDS, THOMPSON CANYON. PLATE XII A. THROUGH WOODED LANE BETWEEN RAPID AND CRAG. ■IK.' x*.-^ 1 jmM ^RK -^ ii A ■UW3(Ufvaiir2MS T^WH^MMB?'^!S?BH!to>*>_ ^ 1 • '-'i-*^'' " W .^•^-■x-- '■^■^^^m ■■^^P^ l^f •'*' - ^rinHP^'^''- '^- ^•"^■-'^r'f^^^'^fj^BB HBffiHHBBI^* ^1^1 ^^I^H^HfflB^B^Vf^w^BuB^^^H^^^^^^H^^^^^^^^^^^I ^^H ^^^^:' ; ■■c*'^ ,.-e;V'.^ '-m B. STEAMBOAT ROCK. A promontory of red sandstone west of Lyons overlooking the St. Vrain. VIEWS IN THE CANYON OF THE ST. VRAIN ON THE ROAD BETWEEN LYONS AND ESTES PARK. Photographs by Willis T. Lee, United States Geological Survey. BOCKY MOUNTAIN NATIONAL PARK. 45 The gorges east of North Fork are longer and are eroded much deeper than those west of the valley. This is due to the greater dis- tance of the vaUey from the high mountains, the crest of the range lying 3 to 10 miles east of the great vaUey and reaching altitudes of more than 14,000 feet. Originally these gorges were ordinary can- yons or valleys formed by stream erosion. But dtu^ing the Great Ice Age they were filled with ice which crept from the heights down the canyons to the great valley. They modified the canyons, which were V-shaped in profile, to the broad-floored valleys of U-shaped profile characteristic of glacial erosion. Also they scoured the bottoms and sides of the valleys, removing the partly decomposed rock and the loose debris. They broke off and carried away the projecting pin- nacles and spurs of rock so that what may have been crooked, irreg- ularly shaped valleys now appear as relatively straight or gently curved gorges with steep walls. Like the better known glacial gorges of the eastern slope, which wUl be described in greater detail, these contain nimaerous ice-smoothed surfaces of rock, glacial lakes, and beautiful waterfalls (PI. XIII, A). ' THE PARK AS SEEN FROM THE TRAILS. Progress is being made toward opening the Rocky Mountain Na- tional Park by means of trails, but in so rugged a country it wiU be a long time before all points are made easily accessible. On the fol- lowing pages are described only such parts as were seen from trails in use during the summer of 1916. The vUlage of Estes Park is the center from which radiate many of the trails to the Eocky Mountain National Park. It takes its name from the basin-like opening among the hills which in turn was named for Joel Estes, the first white man to settle here. Prior to his arrival the Arapahoes visited the park frequently and knew it as "The Circle (ta kah ay non)." From this "circle" as a center I shall "personally conduct" the reader over the several trails and pioint out to him some of the glories of the mountains. We shall start with the Black Canyon Trail and make our way gradually southward to Wild Basin, which is situated near the southern boundary of the park. BLACK CANYON TBAIL. From Estes Park one may go on horseback or on foot up Black Canyon to Lawn Lake, where there is a lodge at which bed and board may be secured. From this point he,may go on foot to Hagues Peak, Hailett Glacier, and many other points of interest. On his return to Estes Park he may ride down the glacial gorge of Roaring River through Horseshoe Park and Fall River Valley, thus encircling a small but rather interesting group of moimtains. 46 EOCKY MOUNTAIN NATIONAL PAKK. The Black Canyon Trail passes for several miles tlirough a some- what open and easily traversed valley. But it grows steeper and more difficult farther up the canyon. On leaving the village we pass close to the Stanley Hotel, which was built at a cost of half a million dollars in 1907, at a time when toiu-ist travel was light and before suc- cess was assured by the estabhshment here of a national playground. From this place there is a superb view of the mountains (PI. XIV, A) , and many an attractive nook may be foiuid among the pines and the granitic rocks which the forces of erosion have shaped in cin-iously interesting forms (PI. XIV, B) . Still farther up the canyon we leave Castle Mountain (8,675 feet) on the left and pass The Needles, or "Little Lumps on Ridge (tha thay-ai ay tha)," as the Indians called these mountains, which reach a maximum altitude of 10,075 feet. The Needles take their name from the sharp pinnacles near the crest. Viewed from below these appear so sharp as to make the name seem singularly appropriate. The broad floor of the valley gives place abruptly to the precipitous side of The Needles (PI. XV, A, p. 48) in a manner which suggests that this valley was shaped by a glacier. It is not situated in the area occupied by the ice during the last stage of glaciation but may belong to the older stage described on page 31. Some of the needle- like pinnacles are so shaped as to resemble well-known forms when viewed from certaiu directions. One of the best known is called Twin Owls (PI. XV, 5). About 2^ miles from Estes Park the trail forks, the left-hand prong leading to a waterfall at the intake of the Estes Park water main. The right-hand prong leads up the mountain side toward Lawn Lake. Here we find ourselves on a typical mountain trail in the primeval forest, which winds in and out among the trees, sometimes with scarcely enough room to pass between them. It traverses rocky slopes and passes in "some places uncomfortably close to the brinks of dizzy precipices. Through the thick growth of trees we occasionally catch a glimpse of Bighorn Mountain (11,473 feet) and of McGregor Moimtain (10,482 feet), which perpetuates the name of R. O. McGregor, who settled in Black Canyon in 1874. The beautifully rounded summit of the former is caused by concentric shells of the granite peeling off, a process known as exfohation. Probably the best view of this moun- tain is obtained from a httle parklike opening where beavers have cut away the underbrush and small trees and bmlt a dam. Just north of Mount Tileston (11,244 feet) the trail reaches a maxi- mimi altitude of 11,000 feet. There are few trees to obstruct the view and there are numerous snow banks ; but we are shut in between walls of rock until the crest of the wind-swept ridge is reached, where there are no treies to interfere with the superb view (PI. XVI, A). From this ridge there bursts upon us one of those matchless high PLATE XIII A. CASCADE FALLS, ON NORTH INLET, ABOUT 4 MILES ABOVE GRAND LAKE. B. THE LODGE ON NORTH FORK OF GRAND RIVER, WEST OFMILNER PASS. Generally known as "Squeaky Bob's place." SCENES IN THE VALLEY OF NORTH FORK OF GRAND RIVER. Photographs by Willis T. Lee, United States Geological Survey. PLATE XIV A. ESTES PARK AKD LONGS PEAK FROM STANLEY HOTEL. B. A REMNANT OF EROSION IN THE GRANITE OF ESTES PARK. Showing character of weathering. VIEWS NEAR ESTES PARK. Photographs by WiUis T. Lee, United States Geological Survey. ROCKY MOUNTAIN NATIONAL PABK. 47 mountain scenes which it is quite impossible to describe. We gaze do"wn 400 feet into the bowlder-strewn gorge of a glacier which once occupied the valley of Roaring River. Directly in front lies Lawn Lake, in the center of a great cavity that was gouged out of the mountain side by the ice which gathered for the Roaring River Hmb of Fall River Glacier (p. 32). StiU higher may be seen, though imperfectly from this position, the subsidiary glacial cirque which holds Crystal Lake. To the left stands Mount Fairchild (13,502 feet) ; to the right Mummy Mountain (13,413 feet) ; and directly in front the dominating point of the region, Hagues Peak (13,562 feet). LAWN LAKE. Lawn Lake, which has an area of 65 acres, lies at the bottom of the main cirque at the head of Roaring River. It is one of the many glacial lakes of the park. The size and beauty of this one have been iacreased by the construction of a dam. In this way the water, which is abundant when the snow is melting early in summer, is held in storage until it is needed on the plains for irrigation later ia the summer. The lake lies just below timber line, at an altitude of 10,950 feet; hence tom-ists are here sheltered by trees while they have every advantage of the unobstructed views usually obtained from points above timber line. In a horizontal distance of little more than a mile from the lake the precipitous walls at the head of the cirque rise more than 2,600 feet above the surface of the water to Hagues Peak and nearly as high on either side. HAGITES PEAK AND HALLETT GLACIER. The trip to Hagues Peak and HaUett Glacier is a difficult one and must be made on foot, for the route is too steep and rough for a horse. The start from Lawn Lake should be made early in the morning. We foUow a trail for a short distance, then take a bearing to an objective point on the crest of the mountain and work toward it as best we may up the steep bowlder-strewn slope; for here no traU that can be followed has been laid out. Although this trip is as difficult as any other in the national park, we are not unmindful of the glorious panoramas that stretch out before us as far as the eye can reach. Almost at our feet lies Crystal Lake in its rock-walled basin high in the side of Moimt Fairchild, and we understand better than before seeing it why such lakes are called "pocket" lakes. A side trip to. the saddle between Hagues Peak and Mount Fairchild is worth aU the effort required to obtain the unusual views firom this point. Here may be seen the bighorns or wild, mountain sheep and flocks of ptarmigan. Slightly to the south of Comanche Peak, partly within and partly north of the Rocky Moimtain National Park, may be had an impressive view of a glacial cirque (PL XVII, A, p. 50). As the photograph was taken from a distance of about 5 48 EOCKY MOUNTAIN NATIONAL PAEK. miles, the cirque is shown in its true relation to its surroundirigs. This hollow, a mUe long and half a mile wide, was gouged out of the mountain side by the ice of an ancient glacier to a depth of about 1,000 feet. At the top of Hagues Peak are small remnants of the gently roHing plain (the peneplain of the geologist) which once occupied this region. A much larger remnant of this peneplain lies north of the peak. This surface seems nearly horizontal where its edge is seen above Hallett Glacier in the accompanying illustration (PI. XVI, B, p. 49), but much of the old plain has been destroyed by recent erosion.' In some places, as between the cirque occupied by HaUett Glacier and the one immediately north of it, the old surface is broken down. The wall separating these two cirques is only a few feet thick at the top and is sharply serrate. Through the notches in this wall may be obtained views into the glacial gorges of the Cache la Poudre drainage area, which are well worth the effort they cost and which some main- tain are the most charming to be found in the park (PI. XVII, B, p. 50). In order to reach HaUett Glacier we must cross the mountain ridge and descend into the cirque which lies at the head of the North Fork of Thompson Eiver. The climb to the crest of the ridge is exhausting, and a few moments may be spent resting and viewing the entrancing scenes. To the east lies Mount D'unraven, named for the Earl of Dunraven, who came to Estes Park in 1872 and later acquired property there with the intention of establishing a game preserve. Still farther south is Mount Dickinson, named in honor of Anna E. Dickinson, who is said to be the first woman to reach the top of Longs Peak. Toward the west is the sharp ridge of Mummy Mountain, whose face, nearly 2,500 feet high, is so precipitous that it seems to overhang Lawn Lake. Beyond this is the galaxy of peaks and gorges which we are to visit as we traverse the trails farther to the south. From this ridge there is a view of Hallett Glacier which is not surpassed from any other point (PI. XVT, B) . The glacier is a great crescent-shaped mass of snow and ice partly surrounding a lake about 300 feet in diameter. Its surface rises steeply from the water's edge to the mountain walls. As seen from below the glacier appears to slope steeply down from the south, west, and north, like tiers of seats in an amphitheater. As the ice aU moves toward the lake, it moves in a northerly direction from the south and in the opposite direction from the north, whUe in the center it moves eastward. As the length of a glacier is reckoned by the distance covered by the moving ice from source to melting point, HaUett Glacier is much wider than it is long. This anomaly is perhaps matched for curious 1 When the geologist speaks of recent erosion tie means erosion tliat has been accomplished within the last million years oi so. PLATE XV A. THE SOUTH FACE OF THE NEEDLES. Precipitous cliffs rising about 2,000 feet above the nearly level floor of Black Canyon. '^H WK^- i^«A >1 }ffTi ^<% M B^^^yT^Pyy^y V^^ '-'' mi::-. -% ^^B^M^B;' ''' ' i ■s.-K itffVi'J ■* ■n'* MtKUiVrm:' "-■' ■.jy-. j*f-1llBm^^f * . -r- ','3' xt .«,; .- \ f. M '■■ J' ■' '■■• ■.>---•';« ^mi^^ ^^F^ H"'- ''^ .J J y-^ WKm WP^^^^^^T^,^^^^*' ■ ,^^^-;:^r^#:- 0^ '"' ' '** m r Mr ■^S^BinRR. .."■l**^-- "■ ■' B. THE TWIN OWLS, AS SEEN FROM A POINT NEAR STANLEY HOTEL. These remnants of erosion indicate clearly why the Indians called The Needles "Lumpy Ridge." LANDSCAPES IN BLACK CANYON. Photographs by WiUis T. Lee, United States Geological Survey. BOCKY MOUNTAIN NATIONAL PARK. 49 interest by the question raised some years ago as to whether this body of ice should be called a glacier, a subject aheady discussed (see p. 30). Great interest has been shown in the crevasses of HaUett Glacier. They differ somewhat in their mode of origin from the crevasses of some other glaciers and seem to be caused, partly at least, by the rehef of pressure from below due to melting of the ice in the water of the lake. Some of the crevasses are concentric and conform essen- tially to the outline of the lake, as if large portions of the glacier were seeking to break off and float away with the surface ice which parts from the more massive body as small icebergs (PI. XVIII). But the crevasses of the higher slopes seem to be of different origin. Where the surface snow has melted away, the old ice is found deeply fractured. In exceptionally favorable seasons some crevasses open in late summer so wide that they may be entered and examiaed (PI. XVIII, upper). A crevasse several hundred feet long was explored in the faU of 1915, to a depth of about 50 feet. But for 15 years prior to that time, according to report, it had not opened wide enough to be accessible. BOABING RIVER. On leaving Lawn Lake we pass southward for nearly a mile across the wooded floor of the cirque to a small but unusually perfect termi- nal moraine. It is a crescent-shaped ridge extending across the valley and is composed of rounded bowlders carried by the ancient glacier out of the Lawn Lake cirque and deposited at the end of the melting ice. This moraine is relatively young and marks one of the last stands made by the vanishing glacier, whose retreat may be likened to the withdrawal of a defeated army. In this case the ene- mies were the warmth of the moderating climate, which forced retreat, and the decrease in snowfall, which cut off suppHes. This glacier once filled the valley of Roaring River (see PI. VIII, p. 30), but was forced back toward the emba,ttled strongholds of the high mountains. A mUe south of Lawn Lake it made a final stand, built up a breastwork of bowlders, and maintained its position for a brief period before final extinction. Farther south the trail angles down the steep slope of the glacial valley. Its east wall is precipitous and the cliffs show marks of ice action up to a height of several hundred feet. The western slopes are now densely forested but probably were once entirely covered with glacial ice which gathered east of the high range that extends from Mount Chapin to Mount Fairchild (see PI. XIX, J^, p. 50). These mountains have been carved by rain, stream, and ice into a group of picturesque gorges, cirques, and pinnacled ridges, but except for places near Ypsilon Lake these points of interest are not easily acces- 99305°— 17 4 50 BOCKY MOUNTAIN NATIONAL PARK. sible for want of trails. However, the great peaks of this range are so prominent that they are plainly recognizable from many parts of the park. YpsUon Momitain is especially attractive and is easily distinguished from aU others by the Y inscribed in perpetual snow in its eastern face. At the southern end of this group stands Mount Chapin, whose name perpetuates the memory of F. H. Chapin, the author of "Mountaineering in Colorado," who first visited this region in 1886. HORSESHOE FALLS. The main mass of Fall River Glacier (PL VIII, p. 30) occupied the valley of Fall River and eroded this vaUey much more extensively than the eastern lobe of this glacier eroded the valley of Roaring River. Hence Roaring River occupies what is called a "hanging valley" — that is, its floor lies at a higher level than that of the valley into which it empties. In its descent of 500 feet from this hanging valley Roaring River forms a succession of picturesque rapids and water- falls, known collectively as Horseshoe Falls (PI. XX). . There are great numbers of glacial bowlders along Roaring River, and as the water descends over these it is buffeted and torn and lashed into spray. The slopes on either side of the stream are densely wooded, and as we follow the winding trail through the woods and among the rocks the ever-changing scene holds many a pleasing sur- prise. FALL RIVER ROAD. One of the favorite outings in the Rocky Mountain National Park is a trip up Fall River. An excellent automobile road across the Continental Divide had, in 1916, been completed nearly to the head of Fall River. The altitude of the mountains at the crossing point and for 3 miles beyond is nearly 11,800 feet. The course is westward near Poudre Lakes, through Milner Pass, and down the western slope to the North Fork of Grand River. On or near this route there are numerous plainly recorded evidences of ancient glaciers; many interesting evidences of volcanic activity in past ages, especially on Specimen Mountain; and unsurpassed views of the high mountains. On leaving Estes Park for the Fall River drive we pass between Castle Mountain (8,675 feet) on the right and Oldman Mountain (8,306 feet) on the left. A short stop may be made at the fish hatchery, the yearly capacity of which is 1,000,000 rainbow, eastern brook, and black- spotted native trout. Farther upstream the course lies between two commanding summits of nearly equal height, McGregor Mountain (10,482 feet) on the north and Deer Mountain (10,028 feet) to the left, south of the river. Here we meet the first clear evidence of the ancient glacier which occupied Fall River valley. The hill on which we rise nearly 500 feet within a mile is the terminal moraine. The glacial material, consisting of striated bowlders, angular stones, and PLATE XVII A GLACIAL CIRQUE. Situated chiefly above timber line southwest of Comanche Peak, as it appears from Hagues Peak at a distance of about 5 miles. It is a depression more than a mile long in the line of vision, half a mile wide, and 1,000 feet deep. One of the lobes of the glacier that occupied Cache la Poudre Valley during the later part of the Great Ice Age gouged into the mountain side and produced this unusuaUy fine example of a cirque. B. VIEW THROUGH ONE OF THE NOTCHES IN THE ROCKY CREST ABOVE HALLETT GLACIER. Looking westward into the glacial cirques at the head of one of the tributaries of Cache la Poudre River. Photographs by WiUis T. Lee, United States Geological Survey. PLATE XVIII VIEWS AT HALLETT GLACIER. Upper left, Entrance to a crevasse in the ice. This crevasse was explored in 1915 for a distance of 400 feet. Photograph by Frank W. Byerly. Upper right, A view within the crevasse 50 feet below the surface of the ice. Photo- graph by Frank W. Byerly. Lower, Icebergs breaking away from the foot of Hallett Glacier. Photograph by PLATE XIX A. VIEW FROM HIGH DRIVE ACROSS HORSESHOE PARK TO THE MOUNTAIN RANGE NORTH OF FALL RIVER. Including Mount Chapin (12,458 feet), Mount Chiquita (13,052 feet), Ypsilon Moun- tain (13,507 feet), andMount Fairchild (13,502 feet). ^^ ,^._ ..^.^ t W^^ M S!5*5^ffl ....■2 W^m- . WM Sfy'M V* ■■■■>■■ ^9 .^■. ■ :.-■■■■.'■ fc A^Jf' : -:C ;/ \ , V:^ fJIJflkS^S^-'''^^-% t^-zip ■H^^^ ■ ^,::,:S:^ '>fsm^ ' - \ ■ L^S Vr:'rC - ■-.f'W-'^^ ^^^f' ■ ' i ■ ... ^ M" ■ ■ ■ :a ' :,«.;