Geological Survey Bulletin 707 Guidebook of the Western United States: Part E. The Denver & Rio Grande Western Route

Soda Springs and Evergreen Lake, two resorts of local interest, are 2-1/2 miles west of Malta. Evergreen Lake is said to be very attractive, and Soda Springs is much visited by those who hope to be benefited by the use of the waters.

A little north of Malta, at the crossing of a strong stream from the east known as the East Fork of the Arkansas, the north end of the Leadville loop connects with the main line. The East Fork heads in the Mosquito Range, on the Continental Divide, northeast of Leadville. The pass between the head of this stream and Tenmile Creek, the head stream of Blue River, has been named Fremont Pass, on the supposition that Fremont crossed the range at this place in his expedition of 1845, but the "Pathfinder" probably crossed at Tennessee Pass.

Long ago, in the Wisconsin stage of the glacial epoch, a great glacier came down East Fork to a point within a mile and a quarter of the Denver & Rio Grande Western Railroad. This great river of ice scoured the valley clean and left it with a broad, flat bottom and a gentle grade. Most of the loose material scoured from the rocky sides of the valley by the moving mass was carried away by Arkansas River, but some was dumped near the lower limit of the ice. Another glacier came down Lake Fork from the high mountains on the west, and this one was so strong that it pushed out across the broad, flat valley of the Arkansas, crowding the stream against the bluffs on the east side. This glacier dumped a great mass of loose material in semicircular form (called a terminal moraine), which the traveler may see on the west (left), but he is so far below its summit that he can not realize its shape. A glance at the map (sheet 4) will show its semicircular shape, which conforms to the curved margin of the tongue of ice that laid it down.

About halfway between mileposts 274 and 275, a mile beyond the crossing of East Fork, the railroad is crossed by a high-tension electric transmission line, which is carried on steel towers. This line carries the power generated in a hydroelectric plant on Colorado River,^33a which the traveler will see at Shoshone, 10 miles east of Glenwood Springs. As the transmission line for such a plant is very expensive, it follows as straight a course as possible without regard to mountains or canyons. For this reason it does not follow the Denver & Rio Grande Western Railroad eastward from Shoshone but turns to the south and passes up Roaring Fork and Fryingpan Creek to Hagermann Pass. From this point it descends Lake Fork and crosses the Denver & Rio Grande Western, as noted above, and thence goes to Leadville, where much of the power is utilized in the mines and mills. The line then turns northeastward toward Denver and crosses Fremont Pass to Tenmile Creek, which it follows to Dillon. From Dillon it runs due east and crosses the Continental Divide for the third time at Argentine Pass. It then descends Clear Creek, serving Idaho Springs, Central City, Blackhawk, and finally Denver. The traveler who visited Mount McClellan while at Denver probably noted the steel towers and the wide swath cleared of timber for this line along the mountain slopes.

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^33aThe name of Grand River, in Colorado and Utah, has recently been changed to Colorado River by act of Congress.

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Near milepost 275 Arkansas Valley regains its normal width of about 2 miles. The constrictions lower down are due entirely to the moraines of the glaciers that flowed down from the mountain valleys on the west. Another glacier from the west filled the valley above milepost 278 with a great moraine, which also crowded the stream against the east bank. As the roadbed is cut in the hillside it exposes some quartzites and limestones, the beds of which are parallel with the railroad and dip to the east. These beds probably rest on the granite that forms the foundation of the earth's crust in this part of the country, and they are visible for some distance along the railroad track. On the south side of Tennessee Pass, however, the beds are so poorly exposed that the traveler on a passing train can get only momentary glimpses of them.

At milepost 281 the slopes of the valley are gentle, and it seems but a little way to the Continental Divide. When the narrow-gage railroad was first built it climbed over the summit of Tennessee Pass, but now it saves about 250 vertical feet of this climb by a tunnel 2,572 feet long. The station of Tennessee Pass is at the south end of this tunnel. After running a short distance into the tunnel the engine ceases to labor and finishes the long steady climb from Pueblo. So far as the railroad can carry him toward it the traveler has now attained the crest of the continent.

The heaviest grade on the main line on the east side of the Continental Divide is 1.42 per cent, or 75 feet to the mile. This grade extends with few interruptions from Buena Vista to Tennessee Pass, a distance of 41 miles. The heaviest grade on the west side is 3.3 per cent on the westbound track. This grade is maintained for a short distance above Minturn, but throughout most of the distance from Minturn to the summit the maximum grade is 3 per cent, or 158 feet to the mile.

After emerging from the tunnel the traveler may look back and see the apparently low summit of Tennessee Pass. If it were not at the backbone of the continent and the parting of the waters of the Atlantic and Pacific it would not attract attention, for it is only a low, flat cross ridge against which the streams head that flow in opposite directions to the two oceans. The Arkansas drainage has become familiar to the traveler, and now the drainage of Eagle River and Colorado River will become equally familiar as the train descends these streams on its way to the western border of the State. Some travelers may find the Continental Divide disappointing, for they may have pictured it as the sharp summit of a single mountain ridge; but the Rocky Mountains form a great system of interlocking and parallel ranges, only a few of which have sharp, narrow crests, most of them having rounded summits that are not particularly imposing.

North of the tunnel the railroad is at the headwaters of Piney Creek, down which it winds and twists to maintain an easy grade to the main stream, which heads on the flanks of Homestake Peak, on the west. This valley is generally covered with forest except near the railroad, where the trees have been cut for use in building the railroad and in working the mines. It is now a part of the Holy Cross National Forest, which is described by Smith Riley in the footnote.³⁴

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³⁴After passing through the tunnel at Tennessee Pass the traveler enters the Holy Cross National Forest. This forest, which covers 577,634 acres and includes part of the drainage basin of Eagle River, takes its name from the famous Mount of the Holy Cross, which lies within sight of the railroad but some distance to the west.

West of Minturn the boundary of the forest follows the lower line of timber growth back some distance from Eagle River valley. The mining camps of Redcliff and Gilman are furnished with timber from the dead trees on the large tracts that were swept by fires before the national forest was created. Some dimension lumber is cut from the green Englemann spruce in the vicinity of Redcliff, but most of it is shipped to the mines at Leadville and in the surrounding country, and some is shipped westward and made into crates for the fruit that is raised in the vicinity of Grand Junction.

The trout fishing in the waters of the Holy Cross Forest is excellent, and the Bureau of Fisheries and the Forest Service keep the streams and lakes well stocked by yearly "plants" of young fish. (See Pl. LI, B.) Game animals and birds of all kinds are considered a big asset to the national forest, and efforts are made to protect and develop them, but predatory animals are eagerly hunted and destroyed. During the winter, when the weather is severe and food is scarce, the wild animals are closely watched by the forest officers, and if found suffering for want of food the State game authorities are informed and steps are taken to feed them. Wild deer and mountain sheep (see Pl. LVII, A, p. 132) feed each winter in Glenwood Canyon, and it is no uncommon sight to see large herds of these animals near the railroad.

PLATE LI. A (top). WILD ANIMALS IN A NATIONAL FOREST. The United States Forest Service is making vigorous efforts to restock the national forests with wild animals. This picture shows a herd of elk recently shipped from Wyoming and turned loose in the Holy Cross National Forest. Photograph by the U. S. Forest Service. B (bottom). STOCKING A STREAM WITH FISH IN A NATIONAL FOREST. The streams in the Holy Cross National Forest are stocked with trout fry so that anglers who visit this region will be rewarded for casting a fly. Photograph by the U. S. Forest Service.

Before the white man came to the mountains of the West game animals of every kind were abundant in them. Now, even in the national forests, which are their natural habitat, there are many areas in which they can not be found. In many of these areas, however, wild animals of many kinds could no doubt be propagated and made a source of revenue. The Forest Service is restocking such areas by shipping game animals to Colorado. In shipping these animals care is taken to send them to areas that afford both summer and winter pasturage. The settlement of the valley lands of the State has cut off wild animals from the valleys, where there is only a light fall of snow during the winter, and has limited their range to the higher country. The larger game animals of this country, however, must have winter feeding grounds where the snow is comparatively light. Even the mountain sheep, which during the summer inhabit exposed regions near timber line, migrate in winter to areas that have exposures to the south and west, where the sun and wind keep the grass free from snow.

Plate LI, A, shows a number of elk, part of a herd of several hundred that were shipped to Colorado by the Forest Service and turned loose in the mountain region. Recent reports show that these animals are contented and are increasing rapidly.

When the State law was passed prohibiting the killing of elk several herds of native elk still remained in the mountains. There are 2,000 or more in the White River National Forest north of Glenwood Springs, 50 on Williams River in the Leadville National Forest, 250 on the south fork of the Rio Grande in the Rio Grande National Forest, 200 in the Gunnison National Forest, and 80 in the Durango National Forest. Mountain sheep are plentiful near timber line and black-tailed deer throughout the mountains. Having so large a stock of wild animals to start with, Colorado can again become one of the foremost "big game" States of the West.

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Like most mountain valleys that stand at a high altitude the valley of Piney Creek is broad and has gentle slopes. The old roadbed of the narrow-gage line, which crossed the summit of the pass, may be seen on the left of the present road, several hundred feet above it. The old line made a great detour to the west into the main valley, and its bed joins that of the present line at the station of Mitchell. Few rocks can be seen in place, but the tunnel at the pass was driven in granite, which is exposed also from place to place in cuts on the railroad. Just below Mitchell the stream has cut a rugged trench in the granite on the east side of its valley, upon which it had been crowded by a great mass of boulders and clay pushed out by a glacier that came down from the west. This glacier came at least as far as the creek, and at times the ice probably turned northward and followed the creek for several hundred yards. The conditions here resembled those that prevailed in Wildhorse Canyon, already described.

Below this point the stream has cut a deep gorge in its rocky floor, and its descent is so rapid that the railroad can not follow it, but climbs down more gradually along the west wall of the canyon. The old narrow-gage track swung to the east, making a broad loop up the East Fork of Eagle River, and then went northward to Pando, on the level floor of the old lake basin, now called Eagle Park. This grade is now utilized by the automobile road that in a general way parallels the Denver & Rio Grande Western Railroad from Leadville to Grand Junction.

In the vicinity of Eagle Park the granite is overlain by sedimentary bedded rocks that were laid down countless ages ago as sand on the shore of a sea. Since that time they have been crushed in the movements in the crust of the earth that have raised up the mountains. They have been permeated by waters bearing silica in solution until all the pores of the sandstone have been filled with silica or quartz (quartz is a form of silica) and the rock has become a glassy white quartzite. This rock crops out nearly parallel with the railroad and dips from 10° to 20° E. It may be seen in the mountain side on the left nearly 400 feet above the railroad, and its nearly horizontal beds are on the opposite side of the valley about 150 feet above the creek. This mountain side is really the eastern slope of the great Sawatch uplift, or, as it is frequently called, the Holy Cross Mountains, which lie west of the railroad. The mountain slope on the other side of the valley is composed mainly of rocks that overlie the quartzite, and if a trench were cut from the top to the bottom of the slope the rocks would appear as shown in figure 28.

FIGURE 28.—Section across Eagle Park, showing the thin cap of quartzite on the west (left) and the same bed dipping into the base of the slope on the opposite side. The beds dip eastward, away from the Sawatch or Holy Cross anticline.

Near milepost 286 the traveler has an unobstructed view to the east (right) up the valley of the East Fork of Eagle River almost into Fremont Pass. The width of this valley suggests that it has been occupied by a great river of ice that originated in the high summits of the Mosquito Range north of Leadville and flowed down Eagle River valley to a point where the melting exceeded the supply of ice from above, but the region has not been examined carefully enough to determine this point.

FIGURE 29.—Meanders of Eagle River in Eagle Park near Deen.

In descending the west wall of the valley the traveler may look down upon the level surface of Eagle Park, and one of the features that may attract his attention is the crooked course of Eagle River, which wends its way down the valley in many bends or meanders. These bends, as seen from a point midway between mileposts 286 and 287, are shown in the accompanying sketch (fig. 29). Courses so crooked are not limited to streams in mountain regions but are characteristic of streams that flow on flat surfaces with a grade insufficient to enable them to straighten their channels. The cause of the flat surface here was a dam formed by a glacier in the valley at Pando. In the pond above this dam mud accumulated, and when the ice disappeared the valley was left with a flat mud bottom, which has since been covered with a thick layer of turf.

A little below this point, at the signal tower of Deen, is the beginning of the double track that extends from that place through Eagle Canyon to Minturn.

The railroad follows the outcrop of the bedded rocks, which maintains, at least as far as Pando, about the same relative position as when first seen—that is, about 500 feet above the valley floor on the west and 100 to 150 feet on the east. Just after passing milepost 288, half a mile above Pando, the traveler may see on the east (right) a low ridge of gravel, which extends across the valley and which is thought by some geologists to have constituted the terminal moraine of a very old glacier that once came down Homestake Valley from the southwest, though the writer thinks that it was more probably the terminal moraine of a great glacier that came down to this point from Fremont Pass; but, as already stated, the region has not been examined with sufficient care to justify a definite statement on this subject. The trench that the stream has cut in the moraine has been filled by an artificial dam, and the pond above the dam is utilized for making ice.

At Pando the railroad turns abruptly to the right and follows the river across the broad valley to its eastern wall. The reason for this abrupt change in the course of the railroad from one side of the valley to the other is that half a mile below Pando the valley, although broad, is almost completely blocked by a great mass of gravel and boulders, which was brought down by a glacier that once descended Homestake Creek, on the west, but pushed a tongue of ice into this valley. (See Pl. LII.) The material brought in by this glacier obstructed the drainage of the valley so much that the river was forced against the east side, and the railroad has followed the pathway kept open by the stream. The course of Eagle River has been greatly affected by this glacier and by the morainic material which it deposited.³⁵

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³⁵A critical observer will see clearly that Eagle River did not originally find its outlet down its present canyon below Pando, which is too narrow for a stream of its volume, but that it once flowed westward across the low divide to Homestake Creek. (See Pl. LII.) In other words, Eagle River here once turned to the west (left) and flowed northward down what is now the lower course of Homestake Creek. The interesting question then arises, What could have happened to cause a stream like Eagle River, firmly intrenched in a deep valley, to change its course and carve for itself a new valley? Manifestly a stream can not make such a change unless it is compelled to do so by some obstruction. What could have been the obstruction? As there is conclusive evidence that the valley of Homestake Creek was once occupied by a great glacier, it seems obvious that ice was the barrier which prevented Eagle River from pursuing its original course and forced it to seek a new outlet toward the north. The conditions as they were at that time are shown on the accompanying map (Pl. LII).

PLATE LII. MAP OF HOMESTAKE GLACIER, COLORADO. Showing how it dammed Eagle River and forced that stream to follow a new course below Pando. (click on image for an enlargement in a new window)

The contrast of the broad valley above Pando and the narrow rocky gorge into which the stream plunges near milepost 290 is striking. To add to the ruggedness of the scene the quartzite, which up to this point has been high up on the slopes, especially on the west side of the valley, is here at creek level on the right; and at milepost 290 the base of the quartzite crosses the stream and makes cliffs on both sides of the gorge. The gorge is so narrow that it can accommodate only the stream and the railroad, but even in order to build the railroad much rock cutting was necessary.

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As the railroad curves about the terminal moraine that marks the lower limit of the glacier the traveler may catch, far to the west (left), a fleeting glimpse of the Mount of the Holy Cross (13,986 feet), so named because the snow on its east slope clings throughout the summer in a great vertical cleft that extends nearly the whole height of the mountain and in a horizontal cleft that crosses the vertical cleft, the two together having the form of a cross. The Mount of the Holy Cross is familiar to many persons through Moran's painting, which has been reproduced extensively in colored prints and postcards. It is doubtful whether from Pando the traveler can see, even in the best weather, more than the crest of the peak, but farther along the road, near Minturn, he may obtain a somewhat better view of this well-known mountain. The cross and the mountain that bears it are well shown in Plate LIII.

PLATE LIII. MOUNT OF THE HOLY CROSS. This wonderful peak, hidden away in the mountain fastnesses, far from the ordinary routes of travel, bears a shining symbol of the Christian religion. The snowy cross is so protected by clefts in the rock that is never disappears, no matter how long and how hot the summer may be. Photograph by W. H. Jackson.

In some places the rock beds are bent upward and the underlying granite appears in great irregular masses, but beyond such bosses, which continue only for short distances, the quartzite takes its accustomed place at railroad level.

The course of the river is nearly due north to the junction with Weary Man's Creek, which comes in from the east. The combined stream turns abruptly and flows west until it joins Homestake Creek and is again in its rightful valley. At the sharp turn from north to west is situated the mining camp of Redcliff, which is also the county seat of Eagle County. This valley was the route of an exploring party under the command of Capt. (afterward Gen.) John C. Fremont, and a flag on a rocky eminence on the right of the railroad in Redcliff is said to mark the site of an engagement with the Ute Indians in one of his expeditions between 1842 and 1845.

Several mines are in operation in the vicinity of Redcliff, and others may be seen in the canyon between Redcliff and Minturn. (See Pls. L, B, and LIV.) Some of these mines have found gold in the granite near the railroad track, but most of them are operating in the Leadville limestone at the top of the canyon wall and the products are silver, lead, and zinc. At the station at Redcliff the granite may be seen on the right, and above the granite towers a great cliff of quartzite, making an imposing entrance to Eagle River canyon, which begins at this point and extends down the stream for a distance of 4 miles. Overlying the quartzite, but hardly visible from the station, is the outcrop of Leadville limestone, marked everywhere by mines and prospect pits. Above the limestone may be seen here and there ledges of red rock belonging to the upper part of the Carboniferous—the same formation that is so conspicuous about Howard and Salida.

PLATE LIV. MINES IN EAGLE RIVER CANYON. The walls of Eagle River canyon are pitted with mines and prospects—gold in the granite near the river and silver, lead, and zinc in the limestones at the top of the cliffs. The mining town of Gilman, on the rim of the canyon, shows in the distance. The ledges in the canyon wall are quartzite. Photograph furnished by the Denver & Rio Grande Western Railroad.

After leaving the station at Redcliff the traveler has just about time to turn in his seat and see the mouth of Homestake Creek on the south (left). Eagle River once occupied this valley, as already explained, but was turned out of its course by the glacier that came down the creek valley from the high mountains on the south. The glacier did not quite reach the site of the railway below Redcliff, but at the time of its greatest extension its front was only a few hundred yards away. Below the mouth of this creek the railroad follows the river through Eagle River canyon, which is not so deep as many gorges cut by Arkansas River on the other side of the Continental Divide, though for narrowness and picturesqueness it is excelled by few.

The stream, which has here become a river, tumbles down through the narrow gorge, dashing its spray over the great boulders that obstruct its pathway. The walls of the canyon rise in jagged pinnacles to a height of 400 or 500 feet and on the east are capped by banded quartzite, the projecting points of which look like ruined castles perched on the rocky walls. Mining has been carried on in this canyon and on the surrounding mountain slopes for many years, and the walls are honeycombed with old prospects and tunnels driven in search of gold. The ores obtained in the limestone above the canyon were lowered to the railroad on inclined tramways or aerial cable lines, the remains of which may be seen along the east wall at points where an unobstructed passageway could be obtained from the head-house, which seems to have a precarious footing on the rocky slope, down to the railroad. For some distance all the mines seem to have been abandoned, but near milepost 296 the river swings to the east and the sedimentary rocks, which dip in that direction, are much lower than they are farther up the stream. Here there are several large mines (see Pl. L, B, p. 105), and the mining town of Gilman has been built on a rocky point that projects into the canyon from the east at a height of several hundred feet above railroad level. The mines are in the Leadville limestone, which lies above the precipitous walls of quartzite and granite, and the traveler may be able to see some of the ore being lowered to a mill in the bottom of the canyon.³⁶ The ore is crushed in this mill and partly separated from the rock with which it is associated and is then shipped to some smelter for reduction to the metallic state. At Belden the quartzite is about 100 feet above the railroad and has a thickness of 250 to 300 feet. It is overlain by the Leadville limestone, which shows at the top of the canyon wall.

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³⁶A. H. Means in Economic Geology, vol. 10, p. 4, 1915, gives the following section of the rocks in the Eagle River canyon:

Section of rocks exposed in Eagle River canyon, Colo.

Age.	Character.	Formation.	Thickness.
Carboniferous:			Feet.
Pennsylvanian	Sandstone	Maroon formation	1,900
	Sandstone	Weber sandstone	3,950
	Shale	Weber shale	50
	Porphyry (intrusive)	--	100
Mississippian	Limestone, gray and white	Leadville limestone	150
Cambrian	Quartzite	Sawatch quartzite	270
	Granite	--	--

Regarding the ores and the mines Mr. Means says:

"The ore deposits of the district are confined to a relatively small area, the largest part of which lies in the canyon of Eagle River between Redcliff and Gilman, a distance of about 3-1/2 miles. The deposits may be divided as follows:

"(1) Fissure veins in the granite, carrying principally gold and silver with some copper, lead, and zinc.

"(2) Replacements in the quartzite, consisting of bodies of zinc blende and galena, also narrow veins carrying gold and silver.

"(3) Replacements in the limestone, comprising large bodies of zinc blende and considerable deposits of chalcopyrite and pyrite."

According to Henderson the value of all the metals produced in Eagle County from 1880 to the end of 1920 is $23,834,838. The ores mined here are the same as those produced in the Leadville district, and the field has had a somewhat similar experience, on a much smaller scale. The camp started as a silver-lead camp, but a little gold also has been mined. The mines produced about $1,500,000 a year in 1883 to 1886. In 1896 copper began to be mined, and in 1905 the zinc mined became of sufficient value to be noted in the reports of production. In this camp, as at Leadville, zinc sprang into prominence in 1914, and in 1915 it led all other metals in the value of its output, which amounted to $l,381,577.

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PLATE LV. A (top). ROCHES MOUTONNÉES. The great glacier that originated near the Mount of the Holy Cross flowed down Cross Creek, rounding and polishing every projecting point of the granite rock. Such rock forms, owing to their fancied resemblance to the backs of sheep, are called by the French "roches moutonnées." Photograph by W. H. Jackson. B (bottom). EAGLE RIVER CANYON. An eastbound train passing through Eagle River canyon. View from a point near Belden, looking upstream. The remains of old mines are visible just below the top of the canyon wall in the distance. Photograph furnished by the Denver & Rio Grande Western Railroad.

Eagle River canyon is so narrow that in building the second track the Denver & Rio Grande was forced to use both sides of the river and even there had to tunnel through many of the projecting points of rock. (See Pls. L, B, and LV, B.) The westbound track follows the east side of the canyon and the eastbound track the opposite side.

For a short distance below Belden the canyon continues narrow and rugged, but its course is more and more toward the east, and the result is that the quartzite steadily approaches railroad level down stream. About half a mile below milepost 297 the quartzite reaches railroad grade, and a short distance below it passes beneath the stream and is lost to view.

PLATE LVI. A (top). EAGLE VALLEY NEAR EDWARDS. Although most of the valley of Eagle River between Minturn and Walcott is more than 7,000 feet above sea level, good crops of alfalfa, the more hardy grains, and potatoes are raised. The ranch buildings are usually substantial and the ranches well kept. In the soft light of the evening the fields of waving grain make a very pretty picture. Photograph by M. O. Leighton. B (middle). RECENT VOLCANO IN EAGLE VALLEY. From the dark hill in the middle background came the last volcanic outburst in this part of the country. Fragments of dark lava still cling to the slopes, showing that the lava flowed down to the bottom of the valley. Photograph by Macins R. Campbell. C (bottom). EDGE OF RECENT LAVA FLOW. The lava flowed out from the volcano shown in B until it reached the river; there it stopped. This is a view of the edge of the flow where it is washed by Eagle River. Photograph by M. O. Leighton.

Just before reaching Rex siding the traveler may see on the west (left) a ridge of loose boulders, which seems almost like a dam thrown across the valley of Eagle River. Doubtless he has already learned to recognize such an accumulation of boulders as a moraine that was pushed out by a glacier from some side valley. This moraine was built by a large body of ice which descended Cross Creek from the high peaks of the Holy Cross group of mountains. The boulders were carried entirely across the valley of Eagle River, showing that the ice filled the valley to the foot of the slope on the east side. The glacier expanded when it reached Eagle River, so that its extremity must have resembled a fan, and it covered the area on which the railroad has been built for a distance of 2-1/2 miles. One of the great blocks of gneiss which it carried to the foot of the slope on the farther side may be seen on the east (right) of the track near Elk Creek. It is 40 feet long and 25 or 30 feet wide, and its top stands 12 feet above the ground.

Cross Creek is noted for the peculiar forms that were produced along it by the passage of the glacier over its granite bed. As the glacier found the floor of the granite canyon somewhat irregular its principal work was to round off and polish the projecting knobs. The rounded masses of granite in this canyon, called "roches moutonnées" (rosh moo-ton-nay'), are shown in Plate LV, A. This name has been applied by French geologists to such rounded rocks on account of their fancied resemblance, when seen at a distance, to the backs of sheep.

At Rex siding the top of the quartzite is at railroad level, and the Leadville limestone may be seen on the left, where it forms several knobs. Its color is light blue, and it is easily distinguishable from the quartzite, which has a yellowish tone. As the railroad swings to the east and the rocks dip in the same direction the Leadville limestone soon disappears below the bottom of the valley, and the only hard rocks in sight are the Carboniferous sandstones and shales, which give to the slopes on the east (right) their banded appearance.

One of the most noteworthy features of this part of the Denver & Rio Grande Western Railroad is the Mount of the Holy Cross (Pl. LIII). This peak stands near the head of Cross Creek, but unfortunately no good view of it can be obtained from the train. Near the mouth of Elk Creek, however, a fleeting glimpse of the mountain may be had, if the traveler is on the alert and looks in the right direction. As the train swings eastward and approaches the mouth of Elk Creek the traveler, by looking back on the west (left) may see high rugged peaks coming one by one into view. Mount Jackson may be seen by looking up Cross Creek, but the one peak which he desires to see more than all others is hidden for a long time by the high plateau on the south side of the canyon. Finally, however, after crossing Elk Creek, which comes in from the east, when the train is near milepost 300 and just before it passes behind a ridge on the left, the traveler may catch a glimpse up the creek valley of the Mount of the Holy Cross (see Pl. LIII), but even here the cross itself is not well shown. Very few persons who have passed over this road have been able to identify this famous peak, but if the traveler will look as directed he can certainly see it unless the atmospheric conditions prevent a view of any of the high mountains.

FIGURE 30.—Sketch map showing old and new moraines above Minturn.

Just after milepost 300 is passed the moraine that marks the other limit of the Cross Creek glacier appears across the river as a sharp and distinct ridge which curves parallel with the railroad, and a good view of its tree-covered slopes may be had from the train. This moraine is composed of sand, clay, gravel, and boulders brought down by the ice from the high mountains on the west, and the glacier that brought this great mass of material marked the last stage of glaciation (Wisconsin) that affected North America; but half a mile beyond milepost 300 there is on the west (left) another ridge or moraine that is rudely parallel to the other ridge just described, but sharply distinct from it. This outer moraine was evidently formed long before the last glacier occupied the valley, for its slopes are more affected by the weather, and as it is outside of the other moraine it must have been formed earlier or else the ice would have demolished the inner ridge, which now is the more conspicuous of the two. The relative position of the two moraines is shown in figure 30. The existence of this older moraine shows clearly that glaciers were formed in these mountains in at least two distinct epochs of time, one of which was much earlier than the other.

The rocks that are so well shown in the mountain slope on the east (right) are supposed to belong to the lower part of the upper Carboniferous or, in other words, to have been formed at the same time as the earliest of the great coal beds in the Appalachian region and the Mississippi Valley. In the Rocky Mountains some coal beds have been found in these rocks, but most of them are too small or too impure to be worked profitably. The lowermost of these formations is the Weber shale, which lies directly above the Leadville limestone but which is so soft that it makes no showing at the surface. Above the Weber shale lies 200 or 300 feet of sandstone and shale that have a strong reddish tint, and above this for 1,000 feet or more the rocks consist mainly of light-colored sandstone separated by layers of shale. On account of this alternation of rocks the hillside appears to be ribbed horizontally by beds of white rock.

As the railroad curves back toward the west the river cuts into the Leadville limestone. The rock is first seen near milepost 301, but it rises steeply and at the milepost is 30 feet above the track. Here the direction in which the beds of rock trend or strike begins to be affected by the northward plunge of the Holy Cross anticline,³⁷ so that the Leadville limestone, instead of becoming higher and higher as the train descends the valley, dips down the stream, and before the train reaches Minturn the beds are below water level.

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³⁷An upward bulge or fold of the rocks is termed an anticline; if it is long and narrow it is frequently called an arch, but if it is short and nearly circular in outline it is called a dome. The corresponding downfold is called a syncline. These folks are represented in figure 31.

FIGURE 31.—Anticline (at left) and syncline (at right). Perspective views and vertical sections showing the half-cigar-shaped mountains of hard rocks on the anticline and the canoe-shaped point of the syncline. After Willis.

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The town of Minturn is built on a broad, flat valley bottom in which no hard rocks are exposed, but a mile below the station the same beds of rock which before were seen only in the cliffs on the east form the mountain side on the west, showing that the beds of rock are swinging more toward the west than they do farther up the river. The red sandstone that was so conspicuous above disappears on the right about the mouth of Gores Creek. This creek is a clear mountain stream that heads in the high peaks of the Gore Range on the east, some of which may be seen by looking directly up its valley. The stream is noted for the fine fishing that it affords and that tempts many anglers to come here to try their luck. The double track which begins above Red cliff ends just below the bridge over Gores Creek.

At the point where the red sandstone and shale pass below railroad level near Gores Creek the cliff on the right is composed of the overlying light-colored sandstone and interbedded darker shale. At the mouth of the creek these beds dip about 30° NE. A short distance below the mouth of the creek the river bends sharply toward the east, and in so doing it cuts more directly across the hard ledges of sandstone which compose the bulk of the formation. As these rocks are harder than those either above or below, the canyon cut by the river is narrower and more rugged than it is in the vicinity of Minturn or below that place, where the beds are much softer. After making a great curve to the right the sandstones (Weber formation) abruptly come to an end. As the train passes this point the traveler may not fully realize why they terminate at this place, but the map will show him that their disappearance from the east side of the river is due to the fact that they swing across the stream, although they do not show in the hillside on the west. If the traveler looks back after passing down the valley a mile or so he will see these beds on the east side of the valley dipping about 45° NE. and reappearing on the west side, as described above. The beds that overlie the sandstone are very soft and consist mostly of clay or shale with here and there a more sandy layer that makes a ledge along the hillside. The beds are so soft that they have been worn down into comparatively low hills, at least near the river, and the slopes are everywhere round and gentle. These rocks are the same as the variegated sandstone and shale at Leadville, which have been called the Maroon formation.

Immediately below the mouth of the canyon the river bottom, which expands to a width of about half a mile and holds it for a distance of several miles, is strewn with boulders brought down by the stream. These boulders extend for about half a mile, and below that point the valley, although narrow, is well irrigated and farmed. The hills on the west side of the valley bear no resemblance in form or color to those on the east. They are dark and their surfaces are hummocky, as if composed of soft material that has slid down the hillside until it resembles a gigantic moraine. The reason for the peculiar appearance of this hillside is not apparent until the traveler has passed the little village of Avon and has looked back on the other side of the hill. The rocks here are well exposed by the cutting of the stream that comes down out of the high mountains on the west. At the base they consist of the ordinary country rocks with which the traveler is already familiar. Above these rocks lie some darker ones, composed of volcanic material that was long ago washed down to this position from a lava flow. This material, which is soft and easily washed by the rains, has slumped down the hillsides until it has given the surface a general hummocky appearance.

The valley at Avon is nearly a mile wide, and in summer it presents a beautiful appearance, with field after field of grain rippling in the wind and here and there a well-kept farmhouse peeping from a grove of cottonwood trees. The farms extend about a mile below the village to a point where the bluff on the east side swings in against the river, cutting off the farming land and rendering the valley rough and broken. The railroad, which has been forced to follow the river along the west (left) side of the valley, swings to the right in a broad curve at Edwards siding, just beyond milepost 312, and continues on that side for some distance. As the railroad is high above the river and skirts the bluffs along the east side, the traveler has an unobstructed view of the full sweep of the valley. (See Pl. LVI, A.) A large valley comes in from the southwest (left), and soon the high peaks of the Holy Cross Range burst into view. The view near milepost 313 is one of the most attractive on the road, especially in early summer, when the summits are still covered with the snow of the previous winter, or in early autumn, when they are white with the first snow of the season. One can look across the grassy bottom of Eagle River, dotted with herds of cattle, to the ranches on the opposite side, where field after field of grain or hay stretches up the side valley as far as the eye can see and even climbs the opposite slope to the highest terrace. Here and there ranch houses are embowered in groves of trees, and the white schoolhouse, with its bright-red roof, gives a touch of color to the pastoral scene. The green fields, especially when the afternoon shadows begin to lengthen, look like velvet, and one would have to travel far to find a landscape more beautiful.

In the movements that have raised the mountains the soft rocks have been crumpled and folded or crushed and broken in a very complex manner. Just beyond Allenton siding, beyond milepost 314, the beds of rock are magnificently exposed on the east (right), for here an old bend in the river threw it against the foot of the bluff, where it washed away all loose material. Here the beds of rock stand nearly vertical, but within a short distance they show a tendency to flatten and pass with slight dips under the river, which here swings sharply to the right. The traveler can see that the rocks here are prevailingly soft and that only here and there thin beds of sandstone stand out like giant ribs on the face of the cliff. The colors of the rocks are variegated, but there is enough red and deep brown in them to give the hills a warm tint.

Half a mile beyond milepost 315, at the crossing of a small creek which enters the river from the right, the base of brilliant light-red sandstone is exposed. This sandstone is Triassic in age and is much more showy in color than any other rock which the traveler has seen since he left Canon City. On account of its striking color attempts have been made to utilize it as building stone, but generally it is so easily affected by the weather that in a few years the corners are rounded off and even great holes are etched in the solid blocks. Where first seen these beds dip about 45° W., but the dip flattens in a short distance to about 25°.³⁸ Beyond milepost 316 the top of the bright-red beds may be seen on both sides of the river. On the right they extend down the hillside in a great curve, but on the left they run along the face of the bluff with only a slight dip downstream.

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³⁸The peculiarities and irregularities of the dips in this part of the valley can be best understood by reference to the map on page 134. This map shows that the river here cuts diagonally across the rim of a sag or basin in the rocks (not a surface basin), the lowest part or axis of which is crossed by the railroad a mile or so farther north toward Wolcott. On the eastern rim of this basin the rocks stand on edge, as shown by the accompanying diagram, but they flatten rapidly as they pass below water level, and as seen farther on they lie nearly flat along its axis.

The meaning of the dips is well illustrated in the accompanying sketch (fig. 32), which shows the rocks as they would appear in a deep trench cut vertically from east to west through the fold.

FIGURE 32.—Sketch section across the syncline at Wolcott on a line from east to west.

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The rocks that overlie the bright-red sandstone are variegated in color but are predominantly green and maroon. They make up sandstones what is called the Gunnison formation, so named from its outcrop in the valley of Gunnison River. The upper part of this formation, is without doubt the same as the Morrison formation on the east side of the mountains, but its lower part probably includes rocks that are not found on that side. The Gunnison formation here contains much soft shale and clay but includes also some beds of resistant sandstone. At this place the formation has been so much crushed that its thickness can not be estimated, but at other outcrops in this vicinity, where it is undisturbed, it is about 220 feet thick. The discovery of the remains of some very wonderful animals in the upper part of this formation north of Canon City is described briefly on page 70.

Above the Gunnison formation lies the Dakota sandstone, which crosses the track near milepost 317. This sandstone marks the base of the Upper Cretaceous and is one of the most persistent and widespread formations of the Rocky Mountain region. It extends from northern Wyoming to central New Mexico and from Omaha to central Utah. In the valley of Eagle River it consists of a single layer of brownish-yellow sandstone 30 to 40 feet thick. It slopes up the hillside on the right and forms the crest of a ridge that runs nearly parallel with the railroad for a mile or more. Across the river it forms the northeastern slope of the hill in what geologists call a "dip slope."³⁹

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³⁹A dip slope is formed by a bed of hard rock from which overlying soft material has been removed by rains and streams, and as the slope of the surface is the same as the dip of the bed that controls the surface it is known as a dip slope.

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The formations so far described are fairly hard, and consequently they form the walls of a rather narrow canyon, but immediately over the Dakota sandstone lies the Mancos shale, which is one of the softest rocks in this region. It is so soft that it readily wears away under the action of the weather and the streams, and consequently it seldom or never forms high or large hills. Where Eagle River crosses the outcrop of the Dakota sandstone and cuts into the shale the valley immediately expands to a width of nearly a mile and contains several ranches. In fact, nearly all the shale on the left side of the river has been removed and the valley takes the form of a rock rimmed basin. The beds of rock on the east side of the basin are steeply upturned, but those on the west side dip toward the middle of the basin at a very low angle, which can hardly be detected but which may be seen in the cliffs of shale almost directly ahead. This little basin or downfold of Cretaceous rocks forms the extreme southern tip of the great syncline or basin of Cretaceous rocks which carries the valuable coal beds of Routt and Moffat counties, in the northwestern part of the State, and which underlies most of southwestern Wyoming.

As the train passes milepost 317 the traveler, by looking back the way he came, may obtain another glimpse of the high peaks of the Holy Cross Range, which, if they are covered with snow, are still conspicuous objects above the horizon. After the traveler passes the axis of the syncline, between mileposts 317 and 318, he can see the gentle rise of the rocks on the west (left) of the railroad in a great cliff of shale, which is nearly ahead but which may be seen on the left from milepost 318. Some bands of white, impure limestone can be followed by the eye, and these indicate clearly the rise of the beds toward the west, but a still better marker of their rise is the Dakota sandstone, which lies below the surface in the central part of the basin but which rises from stream level just below the station at Wolcott and from that place westward forms a battlemented wall along the canyon.

The north side of the valley is marked by a high cliff of the Mancos shale, but the other side is nearly flat and can be cultivated, so that if makes an agreeable break in the line of canyons and narrow valleys through which the traveler has been passing. Until the building of the "Moffat road," in 1906, Wolcott, although but a small village, was one of the principal distributing points for the region to the north as far as the Wyoming line, and a stage was run daily between Wolcott and Steamboat Springs. At that time the region now included in Routt and Moffat counties was noted chiefly as a stock-raising country and thousands of cattle were annually shipped east over the Denver & Rio Grande Railroad from Wolcott and Rifle. Since the completion of the "Moffat road" Steamboat Springs and the region round about receive their supplies directly from Denver, but a stage line is still maintained from Wolcott to State Bridge, 14 miles distant, the nearest point on the "Moffat road."

On leaving Wolcott the train plunges into another canyon, which extends for a distance of about 5 miles. The Dakota sandstone forms the cap rock of the walls of this canyon, especially on the north side, but the surface back of the rugged cliffs rises gradually to much greater heights. The sandstone appears above railroad level just below the station at Wolcott, where it consists of a brownish-yellow sandstone, about 80 feet thick. It abounds in impressions of stems and leaves of plants, which show that at the time it was deposited the country was covered with trees, many of them similar to those living to-day in the more humid regions of the United States. At that time there were no Rocky Mountains, and the deposition of this sand, which has since been hardened into sandstone, was followed by a great invasion of salt water, which formed a sea that stretched from Iowa to Utah and entirely across the United States from north to south. In that sea lived animals that produced shells much like the shellfish of the present day, and on the death of the animals the shells dropped to the bottom and there became embedded in fine mud. To-day that sea bottom has been elevated thousands of feet above its former position, the sea water has drained away, and the limy muds have been hardened into shale in which the shells are preserved with all their beautiful ornamentation. The traveler can verify this statement for himself by finding well-preserved fossil sea shells in the railroad cut just east of the station at Wolcott.

FIGURE 33.—Canyon cut by Eagle River through the west rim of the syncline, as seen from Wolcott.

The station at Wolcott is built on the Dakota sandstone, which in a short distance to the west rises above track level, so that the underlying variegated shale and sandstone (Gunnison formation) and the rocks still lower in the geologic column come into view as the traveler pursues his way down the river bank. As the train rounds the first sharp curve below the station the variegated beds of the Gunnison formation may be seen on the north (right), where they have been exposed by the cutting for the railroad track. About a mile below the village the Dakota lies about 300 feet above the level of the track and the light-red sandstone of the Triassic makes its appearance at that level, but it is so poorly shown that the traveler may not be able to identify it. A view down the river valley from this point, however, shows that the bright-red sandstone is very conspicuous in the cliffs—it is, in fact, the most prominent rock to be seen. The profile of the cliff on the north side of the canyon is represented in figure 33. In this part of the canyon the red sandstone is so brilliant that the outcrop looks like a flame or a mass of red-hot iron on the hillside. At Kent siding, just beyond milepost 321, the valley is somewhat wider than it is farther upstream, and the traveler may obtain, on the north, an excellent view of the canyon wall, which is about 175 feet high and is capped by Dakota sandstone and the brownish-red sandstone that marks the top of the Triassic system of rocks.

Although the canyon is in general very narrow there are at some places along the river level lands and small farms. The stream, like all others in this region, is fringed with cottonwood trees and willows, but among these are interspersed dark spruce trees, which give a pleasing contrast. In summer there is a decided difference between the dark-bluish tint of the spruce trees and the soft green of the cottonwoods and the willows, but the color effects are at their best in early autumn, when the leaves of the cottonwoods and the willows are a brilliant yellow.

Owing to the westward rise of the rocks the canyon walls grow higher and higher, but near Ortega siding (mileposts 323-324) the Triassic red sandstone rises above track level and the canyon ends, because as soon as the hard beds rise above drainage level they are undermined by the cutting away of the soft shale of the lower (Maroon) formation. The canyon is in places rugged and picturesque, but generally it will be remembered for its brilliant coloring rather than for the configuration of its rocky walls.

The valley below the canyon resembles the valley cut in the same rocks near Avon, but the hills here are lower than those about Avon and are cut more deeply by the tributary streams. The main valley, however, contains few striking scenic features, but it is interesting for its many fine farms and comfortable residences.

Near milepost 327 the band of bright-red rock on the higher hills across the river is very conspicuous. As shown on the map, it does not extend far to the west, for it loops around and connects with the exposure that was crossed a few miles above Wolcott. Toward the north the Triassic rocks extend for a long distance, but they are not visible from the train. The traveler may be able to trace the Dakota for some distance, but it eventually fades from sight, and then the most prominent rock is a dark basalt that caps the highest hill 6 or 8 miles to the north. This rock is a remnant of what was once probably a continuous sheet of lava that was poured out on a nearly level surface before the present canyons were cut, when the general surface of the country coincided with the tops of the present highest hills and plateaus. It should not be supposed, however, that the surface at that time was higher above sea level than it is to-day; indeed, it may have been not nearly so high, for it may have been raised to its present level since the lava was poured out. Other remnants of this sheet of lava may be seen farther down Eagle River.

The thriving village of Eagle stands at the junction of the valleys of Brush Creek and Eagle River, in the midst of a rich agricultural district, which presents a pleasing contrast to the bare rocks of the canyon walls and to the badlands that the streams have produced in the bluffs bordering the main valley. Although the general altitude of the valley is rather high, good crops of hay, grain, and potatoes are raised, and much live stock finds pasturage on the surrounding uplands. The railroad crosses Eagle River just before reaching Eagle and remains on the south side of that stream as far as its junction with Colorado River.

After leaving Eagle the traveler may obtain another glimpse of the Holy Cross Mountains on the left, up the broad valley of Brush Creek. For some distance below this point the bluffs of the river are so high that they shut out from view the country on the south (left), but farther west the bluffs recede from the river and grow lower and lower until the upland on the south is clearly visible. This upland now takes on the aspect of a broad, sloping plateau that culminates in the Holy Cross Mountains, which form a most striking feature, especially when they are covered with snow and the intermediate country is still clothed in its summer verdure.

The Holy Cross Mountains are usually regarded as the western most range of the Rocky Mountains. The traveler who is pursuing his way along the bottoms of these canyons may not be aware that he has passed out of the Rocky Mountains and has entered a province marked by very different surface features, but if he could obtain a comprehensive view of the country from some high point he would see at once that the great ranges of the Rocky Mountains lie entirely to the east, and that although mountain ranges are visible to the west they are neither extensive nor continuous. The region into which he is now entering is a land of plateaus, some low and some high—nearly as high as the peaks of the Rockies. It is also called a land of canyons, for it includes most of the canyons of the Colorado River system. Country of this type extends westward from the Holy Cross Mountains to the west side of the Wasatch Plateau in the vicinity of Provo, Utah.

For about 6 miles below the town of Eagle the valley of the river continues much the same as it is about the town. The railroad is built on a terrace that stands 60 to 80 feet above the river, and in places this terrace is surmounted by another about 50 feet higher. The bluffs on the north side of the valley become conspicuous because of their barrenness and because they are being rapidly dissected by rivulets produced by every shower. Gypsum Creek, another large stream, enters the main valley from the south at the village of Gypsum. The creek and the town are so named because of the occurrence in abundance of the mineral gypsum in the neighborhood. The village of Gypsum is a supply point for large districts both to the north and to the south. The region near the village is devoted largely to farming, but beyond the farms there is a large area of open range, upon which a great number of cattle are fattened each year.

The red sandstone of the Triassic comes into the tops of the hills below Gypsum and as it is the hardest rock in the series exposed here it tends to form a canyon that has high and apparently precipitous walls. Near milepost 337 the railroad enters the canyon, which is not so narrow as it at first appears. This canyon is not so picturesque as the canyon in similar beds below Wolcott, for in the canyon below Gypsum the hard red sandstone lies high in the hills and is underlain by soft clay and shale, which wear away rapidly, so that the harder sandstone above breaks down, forming a long, gradual slope back from the stream, whereas in the canyon below Wolcott there are no soft beds exposed below to be eroded and to undermine the harder rocks above, so that the red sandstone cliffs rise almost directly from the water.

As the traveler enters the canyon below Gypsum he may see that the bright-red beds lie in the form of a downfold (syncline)—that is, they are higher at the ends of the canyon than in the middle. This structure may not be apparent to him at first, but at a point between mileposts 338 and 339 he may easily see that the red beds directly opposite the train are lower than the same beds are either to the right or to the left. This lowest point is called the axis of the syncline; it is the line toward which the beds dip from both sides. The layer of rock at the extreme top of the hill on the right is dark brown and not red like the underlying beds, and it does not lie parallel with the other beds but caps the hills without conforming to the dip of the beds beneath. The dark rock is so far away that the traveler can not distinguish its character, but if it were nearer he would see that it is basalt, similar to the sheet of basalt that caps the canyon walls below Wolcott.

In passing down the canyon, before he arrives at the junction of Eagle River and Colorado (Grand) River, the traveler has spread before him one of the finest examples of a recent lava flow that can be found in this country. He can first see this lava flow in the distance on the right soon after he passes milepost 340, in a low, dark hill in the bottom of the valley. The rock of this hill may not at first attract his attention, but on approaching it nearer he can see that it is nearly black and presents a striking contrast to the light-colored rock of the sides of the valley. This rock can be seen at close range at a point about half a mile farther along, where it forms a terrace across the river bottom which suggests that the valley was at one time filled up to a certain level with this black rock. On closer inspection this black rock is seen to be very rough and broken (see Pl. LVI, B), and those who are familiar with lava flows will at once recognize its character, though others may have difficulty in realizing that this mass of rock was once molten matter that was forced up from the interior of the earth through some vent in the solid crust and that flowed down into this valley much as thick molasses flows in cold weather. This fiery mass could not flow rapidly, for its outer part was continually cooling and being "frozen" into solid rock. The crust thus formed would hold the lava for a time, but it would finally burst and the fiery flood would once more roll along until it was again held up by the cooling of the surface. This drawing off of the liquid lava produced caverns beneath the solid crust, which in time broke and fell in, so that the surface is now very rough. The edge of the flow, shown in Plate LVI, C, can be seen from the train as it follows the bank of Eagle River on the opposite side.

The traveler has now seen the lava flow, though he has probably not seen the vent or volcano from which it must have come, but if he scans closely the hills across the valley he will see that some of them are littered with fragments of the same dark rock that composes the flow and that others consist wholly of that rock. The volcano must have been near the top of the first series of hills, as shown in Plate LVI, B, but its crater is now obscured by the lava that consolidated in its throat. The vent was small, but it has all the essential features of a true volcano. The ravine down which the fiery flood rolled into the valley, leaving some of the melted rock adhering to its sides as it passed, may be seen from the train. (See Pl. LVI, B.)

This eruption seems to have been the last expiring gasp of forces that long before poured out immense floods of molten material in this region. The material erupted at this place was only enough to fill the valley to a depth of 50 or 60 feet but not enough to turn the river from its course. The lava extends down the valley half a mile beyond milepost 341.

As the train rounds the bend, just below the limit of the lava flow, the valley of Colorado River is visible on the north (right), and Eagle River unites with this stream a few hundred yards farther on, but the junction is not near enough to be seen from the train. Colorado River has its source on the east slope of Mount Richthofen, in the northern part of Middle Park, and those who went to the summit of the mountains (Corona) on the "Moffat road" could look down on this west side into some of the head tributaries of this river. After flowing westward across Middle Park the river escapes from that natural basin in the mountains by Gore Canyon, a rugged gorge which it has cut through the Park Range—the same range which the traveler saw on the east (right) at Tennessee Pass. Gore Canyon is cut in granite, but below the Park Range the valley is much like that of Eagle River, consisting of a succession of narrow canyons with stretches of broad valley between. This alternation is repeated many times along the river before it is joined by Eagle River at the siding of Dotsero. At the point of junction there is visible far to the north a high plateau, which is locally called The Flattops or the White River Plateau, from the stream that drains its western slope. It has an altitude of 11,000 to 12,000 feet and is noted as the greatest hunting ground of western Colorado. It was here that Theodore Roosevelt made one of his famous hunting trips while he was President of the United States. The preservation of the plateau at this high altitude is largely due to the fact that soon after its even surface was formed it was covered from some vent in this region with lava, which afterward cooled and consolidated into a basalt that has successfully withstood the action of the elements and still preserves its nearly level surface. The lava sheet that caps the high hill on the north side of the canyon below Wolcott was probably once a part of this same flow or flows but has been separated from it by the canyon cut by Colorado River.

After passing milepost 342 and a small cut a few hundred yards beyond the railroad track reaches the bank of Colorado River, which it follows to the western border of Colorado. This part of the country is noted for its cattle and horses, and the siding of Dotsero is maintained largely for their shipment. There are no red rocks in the valley of Colorado River just below the mouth of Eagle River, but the rocks there exposed are about as hard as the soft red and green shale and sandstone above. At first the traveler may not be able to identify any of the dull-gray and slate-colored rocks below Eagle River with those he has seen farther upstream, but a comparison of the section and of the order of the formations may show him that these beds are the same as the heavy cliff-making sandstone and shale which he saw just below Minturn. It might be supposed that the same formation should show the same composition and hardness wherever it is exposed, but as these formations consisted originally of sand, clay, and limy materials that were deposited in some body of standing water, either a lake or the sea, it is apparent that the character of the formation at any place must depend largely upon the kind of material there swept into the body of water by the streams, and as the land near by was probably composed of various kinds of rocks, which furnished various kinds of material, it does not seem strange that at one locality a formation may consist largely of sandstone and at another of shale. Changes from sandstone or shale to limestone are more rare, but such changes are observed in many parts of the country. The soft materials, including some coal beds that are exposed below Eagle River, belong to the Weber formation, which is in the lower part of the upper Carboniferous rocks.

The rocks rise gently westward, and at milepost 345 the massive layers of the Leadville limestone rise from river level. This point marks the beginning of one of the most noted canyons on the line of the Denver & Rio Grande Western Railroad, the canyon of Colorado River that stretches in unbroken beauty and grandeur from this point to Glenwood Springs, a distance of 15 miles. (See Pls. LVII, B, LVIII, and LIX.) This great canyon was trenched by the river in an immense upfold of hard beds, which include all the sedimentary rocks that the railroad has crossed in the canyons above, and into the underlying granite, to a total depth of 800 to 1,000 feet. The first appearance of the Leadville limestone, noted above, near milepost 345, is marked by a warm sulphur spring, very similar to the warm springs which gush from the same formation at Glenwood Springs and give that place its reputation. Why the water should be warm at both these places is a question that can not yet be answered, for neither spring has any apparent connection with a fault that would permit the hot waters to rise from great depths, or with old volcanic flows or vents in which circulating water would come into contact with rocks that still retain some of the heat they had when they were ejected from the earth's interior. However, there may be some underground connection with one or the other of these features which is not apparent at the surface but which would account for the temperature of the waters carried in this limestone.

PLATE LVII. A (top). MOUNTAIN SHEEP. Occasionally during the winter mountain sheep may be seen on the cliffs in the Colorado River canyon. The deep snow drives them down from the higher tops, and they find pasture on the narrow ledges along the canyon wall, from which they may gaze on the passing trains. B (bottom). UPPER END OF CANYON OF COLORADO RIVER. The regular masonry-like walls are the striking feature of the upper end of this beautiful and picturesque canyon. The beds of quartzite are so even and continuous that they seem to have been dressed and laid by man. The walls rise abruptly from the river, so in building the automobile highway it was necessary to tunnel through these beds at some points. Photograph by the Detroit Publishing Co.; furnished by Denver & Rio Grande Western Railroad.

PLATE LVIII. CANYON OF COLORADO RIVER. In the part of the canyon a short distance above Shoshone there are many beautiful vistas of quiet stretches of river between the rugged walls of quartzite towering on either side. The rocks rise steadily downstream, and the granite makes its first appearance in the railroad tunnel through the projecting point on the left. Photograph copyrighted by the Detroit Publishing Co.; furnished by the Denver & Rio Grande Western Railroad.

The limestone rises toward the west at an angle of about 15°, and within a distance of half a mile the underlying quartzite appears at the level of the track. As the river cuts deeper and deeper into the rising rocks the canyon becomes more and more rugged, and the short bends give rise to many towers and pinnacles upon the projecting points. As the rocks continue to rise in the direction in which the train is going, lower and lower rocks come into view. Next below the upper quartzite, which is about 100 feet thick, lie shale and thin-bedded sandstone, about 40 feet thick, and upon these lies white quartzite, about 270 feet thick. So far the section in this canyon is almost identical with that seen in the deeper canyons up Eagle River, but here there is still another member, which seems not to be present farther east. This member is a coarse quartzite whose chief characteristics are its rich pink or maroon color and the remarkable regularity in the thickness of its various beds, as well as the evenness of the bedding planes which separate them. These characteristics are well shown in Plate LVII, B. The full thickness of this quartzite can not be seen here, for within a short distance the beds dip sharply in the other direction and the quartzite disappears below water level. Farther down the river, however, where the quartzite rests on the granite, its thickness is about 80 feet. The highest point on this arch in the rocks is reached about half a mile beyond milepost 346. Beyond this point the beds dip rather steeply downstream until the Leadville limestone is at track level on the left, and then the whole series is broken by a great fault, which, as shown on the map, crosses the railroad at milepost 347.

Beyond the fault the land on both sides of the river is comparatively low and smooth, and then the Leadville limestone rises again from track level. Where it is seen by the roadside it is much broken, having evidently been greatly disturbed and crushed. The rise of the formations downstream is gradual but steady, so that near milepost 349 all the sedimentary rocks are again above water level and the granite makes its appearance. Plate LVIII is reproduced from a photograph taken at this point, looking downstream. The first tunnel near milepost 350 is cut in the massive granite, which continues to rise higher and higher in the canyon as the train proceeds.

The part of the canyon in which the base of the quartzite is only a few score or few hundred feet above water level is its most interesting and picturesque part, which is all too soon passed by the trains. The canyon walls are nearly vertical, and the cliffs formed of the quartzite stand up like immense architectural structures and present great variety of form and color. The joints, which cut the rocks in at least two directions, give rise to smooth vertical faces of rock and to buttresses and minarets almost without number. The canyon here is narrow and tortuous, and many magnificent vistas can be had of the swiftly flowing river and the dark walls, which even at midday seem to envelop the deeper parts with a somber haze.