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

SHEET No. 8 (click on image for an enlargement in a new window)

Beyond Cisco the railroad curves here and there over the shale upland, steadily approaching the foot of the Book Cliffs. (See sheet 8, p. 210.) As it nears the cliffs it seems to be lost in a maze of small shale hills, as shown in Plate LXXXII, B, but in places one may catch glimpses through them of the ragged front of the cliffs. Viewed from a distance the Book Cliffs look like a regular mountain front, but viewed near by they are seen to be made up of a series of terraces or benches, each bench being formed by some hard bed of sandstone more resistant to erosion than the beds above or below. Each bench is cut by streams into a number of salients, or teeth, which project far beyond the main mass of the cliffs. Behind and above the lowest row of salients there may be a second row, formed by a similar hard bed, and in places there is a still higher row of salients, formed by a third hard bed. The resulting cliffs present a front that is very irregular in detail but very regular when viewed from a distance. A view along the front, showing the lower tier of salients, is given in figure 54. The lowest bench of the cliffs is formed by the lowest sandstone in the coal-bearing Mesaverde formation, and the slope below is composed of Mancos shale. This shale is very homogeneous in composition, and therefore on steep slopes it has been cut by many minute ravines, with a wealth of detail that is amazing to one unaccustomed to the effects of the erosion of rocks in a semiarid region. What infinite pains Nature apparently takes even in carving one of these commonplace hill slopes! This carving is, indeed, a work of art comparable to that of the most skillful sculptor.

FIGURE 54—Projecting point of the lower salients of the Book Cliffs. view looking east from Thompson, Utah.

As the traveler goes westward he finds many shale ridges, which form the divides between parallel stream valleys that head in the Book Cliffs. These ridges have either flat tops or tops that slope regularly away from the front of the cliffs. The tops of the ridges stand from 80 to 100 feet above the general level of the plain and doubtless represent the surface of a former plain that stood that distance above the present surface. When that plain existed the streams could not cut deeper into it, and so the land was reduced to a gentle slope, but later the streams acquired greater cutting power and they have succeeded in eroding away most of the old plain except where it is best protected on the divides. What caused the increased cutting power of the streams is a difficult question to answer. It may have been an uplift of the country, or it may have been a change in climate by which the volume of water carried by the streams was greatly increased.

After the train has passed through cuts made in two or three of these shale ridges it reaches the village of Thompson, or, as it was formerly called, Thompson's Springs, a name applied to it because 5 miles up the canyon that opens at this place there are several springs which have been of great value. In a dry country all settlement except on the railroad depends on the presence of water, and in the early days Thompson's Springs were the chief source of supply for those who were forced to make the trip across this inhospitable country. When the railroad was built the springs were equally valuable as a source of supply for the locomotives, and water was piped from them to the line of the road. For a long time Thompson owed its prosperity to the water from these springs and to the business which it obtained as a supply and shipping point for the sheep owners in the region about Moab, an old Mormon town on Colorado River, 32 miles to the southeast.⁶⁴

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⁶⁴It was the settled determination of the early Mormon leaders to make their followers an agricultural people, for they knew that those who till the soil can much more easily be held in an organization like that of the Mormon Church and are less likely to wander away after "strange gods" than those who are engaged in other pursuits. A great empire was to be built, and its most secure foundation was a large and prosperous agricultural population.

The region in which they had settled and which they regarded as the "promised land" was much like that of Judea, in which the ancient Hebrews flourished, a land consisting in large part of deserts whose oases here and there afforded fine opportunities for a pastoral people. Soon after the first settlement of the valley of Great Salt Lake, in 1847, immigrants began pouring into Utah at the rate of several thousand a year, and the leaders had to find these oases and see that the newcomers were settled therein. In this work they were autocratic. Brigham Young directed the settlement of the valleys and even picked the families and the leaders who were to settle them. Nothing was left to chance. The proceeding was high-handed, but the results, as seen to-day, show that it was probably the best that could have followed. Moab was one of these distant colonies, and others were established in southern Utah, Arizona, and California, as well as in more northern States.

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Coal mines have recently been opened 5 miles up the canyon, and the coal is brought to the railroad by a branch line. The coal is of good quality but not quite so valuable as that which is mined in the same formation farther west.

The many salients of the Book Cliffs show well from Thompson. By looking east or west along the front one can see point after point projecting from the plateau, as shown in figure 54. The intricate sculpture of the shale that composes the lower slopes of the cliffs is well shown about a mile west of Thompson. By contrast with the curves in the sculpture of the shale the angularity of the forms of the land impresses the traveler more and more as he gazes off to the southwest while he is passing over the plain just west of Thompson. Seen from this plain the profiles of the distant plateaus appear extremely angular and show no flowing curves. The landscape looks as if it had been formed by the hand of a giant who carved it with an axe, cutting here and there great angular chunks out of the flat-lying rocks. (See fig. 52, p. 198.)

A short distance west of a siding called Crescent the railroad cuts through a low ridge of shale, which is one of the remnants of the higher surface, and then begins the long descent to Green River. Immediately after cutting through the ridge the road turns to the north, and for about 10 miles it skirts the front of the Book Cliffs, running most of the way through badlands of soft shale that have been cut by rain and running water. It passes so near the cliffs that the traveler may see all the delicate fluting and also the sharp points of the salients which are protected by caps of heavy sandstone. Although the variety of details is infinite, the general similarity of the forms produced grows wearisome, and the traveler finally welcomes the emergence of the train from the badlands into the open plain, which leads down to Green River. This change occurs at a siding called Solitude, which indeed is rightly named. Here nothing is in sight but the endless expanse of plain covered with the stunted vegetation of the desert on the one side and the equally endless badlands on the other. To the eye of the sheep herder, however, this region is not desolate, for it affords fine feeding ground for his sheep. The impression of it, then, depends on the point of view; what the stranger sees as desolation no words can describe one familiar with the scene views without aversion and accepts at its real worth.

Immediately after the train rounds the curve beyond Solitude the town of Greenriver comes in sight, although it is almost 12 miles distant. At least the green trees in and surrounding the town can be seen, but they are nearly straight ahead and the traveler may have difficulty in locating them.

As the train passes down this even slope much of the surrounding landscape is spread out before the traveler. The Book Cliffs on the right swing far to the north in a great reentrant which Green River has cut in their generally even front. Across the river there is a strong salient, which is known as the Beckwith Plateau, named for Lieut. Beckwith, who was associated with Capt. Gunnison in his survey of this route for a Pacific railroad and who crossed Green River September 30, 1853. Capt. Gunnison lost his life in an encounter with a band of Indians after he had crossed the Wasatch Plateau, and Lieut. Beckwith prepared the report of the exploration. The most attractive features in the landscape are the wonderful tablelands and the peaks resembling ruined cities, which can be seen far across the river in the north end of what is known as the San Rafael Swell. This region is described in greater detail on pages 207-208.

As the traveler descends the smooth shale slope he can make out the point where Green River emerges from the mountainous country to the north by the deep reentrant in the line of the Book Cliffs. By close examination he may be able to see a butte on the west side of the river, which is marked by a series of pinnacles and which is known as Gunnison Butte, in commemoration of the survey of this region by Capt. Gunnison. (See Pl. LXXXII, C.) This butte towers 2,700 feet above the river, but as seen from the train it seems to be not more than 300 or 400 feet high. Very few published reports regarding the early exploration of this part of the country are available. Gannett⁶⁵ refers to the early history as follows:

From a very early time this region was traversed by Spanish caravans, traveling from Santa Fe, N. Mex., to Los Angeles, Calif. The old Spanish trail, which these caravans followed, entered Utah on the east near Dolores River, crossed the Grand [Colorado] near the Sierra La Sal and the Green at the present crossing of the Rio Grande Western Railway. It reached the valley of Sevier River near its bend and, turning south, followed its valley to the head and down the Virgin to a point near its mouth, whence it turned westward, running out of the State near its southwest corner. This traffic, which at one time was great, left, however, no trace behind in the form of a settlement. * * *

The earliest recorded exploration of any part of Utah was a journey by two Franciscan fathers, Escalante and Dominguez, from Santa Fe, N. Mex., to the shores of Great Salt Lake in 1776-77. So far as can be learned, their route followed in the main that of the old Spanish trail, and it is not at all improbable that they were the pioneers in laying out the western part of this route to southern California. So far as known, they were the first white men to visit the eastern part of the Great Basin of Utah. This journey was not, however, fruitful in geographic discovery, except in the fact that it may have determined the route of travel between the Spanish settlements of New Mexico and those of California.

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⁶⁵Gannett, Henry, A gazetteer of Utah: U. S. Geol. Survey Bull. 166, pp. 10-11, 1900.

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PLATE LXXXIII. GREEN RIVER. Here the river is quiet and sluggish, seemingly gathering its strength for the wild plunge through the great canyons that lie below. Photograph furnished by the Denver & Rio Grande Western Railroad.

Thus it seems probable that while the original colonies on the Atlantic seaboard were waging their war for independence, Fathers Escalante and Dominguez were marking out the old Spanish trail and even crossing Colorado River at or near the same point where the travelers of to-day cross it on the trains of the Denver & Rio Grande Western Railroad. The next notable journey of exploration in this part of the country, at least by English-speaking people, was that of Capt. Gunnison in 1853. He likewise crossed the river at this point, but after reaching the west bank he veered off to the south and followed the Spanish trail instead of the route now followed by the railroad.

In its descent from the east the railroad runs into a shallow valley, which conceals the view of the surrounding country, and finally comes out on the east bank of Green River at a little village called Elgin. The change from the barren slopes of shale to the beautiful green of the cottonwood trees and the brilliant fields of alfalfa is very grateful to the traveler, and he welcomes the sight of running water. It is true that Green River is generally muddy, but even if it is he looks upon it with pleasure and almost with reverence, because a stream of this size that can persist through so many miles of semiarid land excites curiosity and admiration. The river is spanned by a fine steel bridge (see Pl. LXXXIII), and a mile farther west is the station of Greenriver, an oasis in this inhospitable desert, at the lowest point on the Denver & Rio Grande Western Railroad. In this region the summer temperature is almost torrid and the precipitation is slight, probably about 6 or 7 inches annually. Water has here been taken from Green River for the irrigation of a small area that has been made to produce almost all kinds of crops and fruit. Fruit trees flourish here, as shown in Plate LXXXIV. A much larger area could be irrigated, though at much greater expense, by damming Green River in the canyon far above the town and constructing expensive canals to carry the water high up on the surrounding slopes. Sooner or later this work will be done, and then Green River valley will rival Grand Junction in the acreage under cultivation and in the abundance of its products.

PLATE LXXXIV. APPLE TREES IN BLOOM. Green River is the center of a considerable fruit-growing district. When in full bloom the orchards present an exceedingly beautiful aspect, excelled only by their appearance when the fruit is full grown. Photograph furnished by the Denver & Rio Grande Western Railroad.

Where it is crossed by the Denver & Rio Grande Western Railroad, Green River is a quiet, peaceful stream, as shown in Plate LXXXIII, flowing in a broad valley with low banks. It is hard to realize, therefore, that above this place it is a roaring torrent, confined in narrow walls hundreds if not thousands of feet high, and that 50 miles downstream it joins the Colorado, which there enters the grandest canyon in the world.⁶⁶

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⁶⁶It is impossible here, in describing Green River, to avoid mentioning the exploration of this wonderful stream and its southward continuation, the Colorado, in 1869 by Maj. John W. Powell, who afterward became the Director of the United States Geological Survey. Although Maj. Powell had lost his right arm on the battle field of Shiloh, this loss did not deter him from attempting the descent of the canyon of the Colorado, an exploit that few men physically perfect have been able to accomplish.

For a number of years prior to 1869 Powell had been doing geologic and geographic work in the Uinta Mountains and the adjacent plateaus, and he had many times looked down into the swirling waters in the bottoms of the unexplored canyons and longed to embark upon them and learn the secret of the canyon land. He thus fell under the spell of the Grand Canyon, and for many years he dreamed of exploring it, although up to that time no one who had been brave or foolhardy enough to attempt to ride the current of the mighty Colorado had lived to tell the tale. Powell was warned by the Indians that no one who entered the secret and sacred precincts of the gods, as the Indians conceived the canyon to be, could expect to come out alive. But such tales only whetted his curiosity and spurred him on to increased activity. In his narrative (Exploration of the Colorado River of the West and its tributaries, p. 7, Washington, 1875) Powell says:

"The Indians, too, have woven the mysteries of the canyon into the myths of their religion. Long ago there was a great and wise chief who mourned the death of his wife and would not be comforted until Ta-vwoats, one of the Indian gods, came to him and told him she was in a happier land and offered to take him there that he might see for himself if upon his return he would cease to mourn. The great chief promised. Then Ta-vwoats made a trail through the mountains that intervene between that beautiful land, the balmy region in the great west, and this, the desert home of the poor Nu-ma.

"This trail was the canyon gorge of the Colorado. Through it he led him, and when they had returned the deity exacted from the chief a promise that he would tell no one of the joys of that land lest, through discontent with the circumstances of this world, they should desire to go to heaven. Then he rolled a river into the gorge, a mad, raging stream that should engulf anyone that might attempt to enter thereby.

"More than once have I been warned by the Indians not to enter this canyon. They considered it disobedience to the gods and contempt for their authority and believed that it would surely bring upon me their wrath."

One of the Indians described to Powell the fate of some members of his tribe who attempted to run one of the canyons of Green River in the following graphic manner:

"'The rocks,' he said, holding his hands above his head, his arms vertical, and looking between them to the heavens, 'the rocks h-e-a-p, h-e-a-p high; the water go h-oo-woogh, h-oo wough; water pony [boat] h-e-a-p buck; water catch 'em; no see 'em Injun any more! no see 'em squaw any more! no see 'em papoose any more!'"

Despite these admonitions Powell made preparations to undertake the descent of the canyons, and on May 24, 1869, he floated away from the frontier settlement of Green River, Wyo, with a party of ten men in four boats. One of the boats was wrecked in the canyon of Lodore, where the river cuts through the great mass of the Uinta Mountains, but none of the party was lost. The expedition passed what was then called Gunnison's Crossing, now Greenriver, Utah, on July 13, and thence went into the Grand Canyon of the Colorado. Here they met many mishaps but found no falls over which they could not take their boats, and in time they reached the deepest part of the canyon; but they had lost their instruments and had no means of estimating the distance yet to be traveled to the Mormon settlements at the mouth of the Grand Wash. Their progress was slow, too, and provisions began to run short, and several of the party became discouraged and dissatisfied. Powell did all he could to induce the men to remain with the expedition, but three of them decided to abandon the river and attempt to climb out of the canyon. These men succeeded in reaching the plateau only to be killed by the Indians, who did not believe their story about coming down through the canyon but thought they were white men from across the river who had killed a squaw in a drunken brawl. What made their fate more tragic was the success of Powell and his remaining men, who continued down the river and on the next day reached the mouth of the canyon, and on the day following arrived safely at the mouth of Virgin River.

No romance is more entertaining and exciting than the account of this expedition, told in the plain, simple language of Maj. Powell, or than the account by Dellenbaugh of Powell's second trip, made in 1871 and 1872, to verify and extend the fragmental scientific observations recorded during some parts of his first trip. To-day a fitting monument to Maj. Powell stands on the brink of that titan of chasms at Grand Canyon to commemorate his exploration.

The pioneer trips thus made by Maj. Powell in hardship and peril prepared the way for the topographic engineers and geologists of the Geological Survey, who to-day, more than 50 years later, guide their motor boats with confidence, though even yet not without danger, over stretches of the river traversed by the Powell party. These engineers are doing pioneer work of another sort, for they are making plans by which the river can be used for irrigation and for generating power, so that men can make homes in this still wild country.

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A few hundred feet west of the station at Greenriver the railroad has cut through the dark shale at the base of the Mancos formation. If the traveler could have the opportunity of leaving the railroad coach and of walking through this small cut he would find that almost every fragment of shale is covered with impressions of shells. Experts who have studied these shells say that at one time each was inhabited by an animal that lived in the sea and that when the animal died the shell was filled with the dark mud that has since been consolidated into shale. The form and all the delicate markings of these shells have been well preserved. The general distribution of this shale in New Mexico, northeastern Arizona, eastern Utah, Colorado, Wyoming, Montana, North Dakota, and South Dakota shows that the sea in which it was deposited must have been of great extent and that the Rocky Mountains of to-day could not then have been in existence. Geologic evidence over all the world shows that its surface has been continually changing. At one time a region may be covered with water; at another time it may have been a plain much like that which the traveler crossed east of Denver; and at still another time it may have been high land, with mountains. Such a succession of changes has been repeated many times, with infinite variations, through all the ages, and the present age is no exception but is also a scene of general change or transformation. Such a transformation is going on to-day as in the past, but we are scarcely aware of it, for it is so slow that even during the entire period of human history it has made but little progress.

After the train surmounts the slight rise out of the valley of Green River the traveler will see spread wide before him one of the most desolate landscapes that he has thus far passed in his western trip. For miles the surface of the plain consists of bare clay or shale without so much as a clump of sagebrush or greasewood to break its monotony. The soil is the same as that about Green River and at Grand Junction and Montrose, in Colorado, and all that it needs to transform it from a scene of desolation to one of peace and plenty is water. To-day it is desolate and waterless, far from the homes of men, inhabited only by beasts and birds of prey. Even these are not always seen, and the traveler who is unfamiliar with the country may imagine that it is totally without animal life; but should he camp here in the desert for a time he would find that at morning and evening it is alive with birds and animals eagerly seeking food and ready to fight for it.

West of the crossing of Green River, at what is now the town of Greenriver, the old Spanish trail divided. The main trail, which led to southern California, turned to the south and crossed the Wasatch Plateau at Emery Canyon; the other branch of the trail turned to the north and followed practically the present line of the Denver & Rio Grande Western Railroad. By crossing southern Utah over the old Spanish trail the early travelers gained a general knowledge of that country. It was soon settled by bands of Mormons sent out by Brigham Young, and its settlement led to the location of the first capital of the Territory of Utah in its southern part.⁶⁷

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⁶⁷It was originally planned to locate the capital of Utah at Salt Lake City, but when the Territory was created in 1850 it was decided that the capital should be more nearly in the center of the Territory. The County of Millard was therefore created, and on October 29, 1851, the city of Fillmore was laid out as the capital, both the city and the county being named for Millard Fillmore, then President of the United States. A State house was begun but never finished. The legislature held but one full session at Fillmore—that of 1855-56. Several succeeding legislatures met there in order to comply with the law but did no business except to adjourn to Salt Lake City, which was finally made the capital.

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The train pursues a westerly course through the barren wilderness of clay flats, low shale hills, and dry beds of the desert watercourses. Water is so scarce in this region that at each siding the railroad company has built cisterns to which it hauls water in tank cars for long distances. The rainstorms here are generally violent; the water falls in torrents, the desert becomes a sea of mud, and the rushing streams cut deep channels and dissolve their banks as if they were made of sugar. At times even the railroad trains have been engulfed by streams which during more than eleven months of the year carry not a drop of water.

The great south face of Beckwith Plateau, a point that runs off southward from the main mass of the Book Cliffs, looms up prominently on the north (right), as shown in Plate LXXXV, but in the other direction there is no prominent feature to attract attention; one can look southwestward across the adobe plain as far as the eye can see and distinguish nothing but the dim outline of the Henry Mountains, far away in the hazy distance.

PLATE LXXXV. BECKWITH PLATEAU. Beckwith Plateau is one of the landmarks west of Green River. The coal-bearing sandstone on the top is broken into fantastic forms, and the shale slopes below are marvelously sculptured by the rain. It stands in the midst of one of the most desolate flats that the traveler will see east of Salt Lake City. Scarcely a shrub or plant of any kind breaks the monotony of this expanse of barren clay. Photograph furnished by the Denver & Rio Grande Western Railroad.

Six miles west of Greenriver, at milepost 561, the railroad curves to the north and follows the shale valley on the west side of the Beckwith Plateau. As the train goes around the curve the traveler may get on the left an excellent view of the east side of the San Rafael Swell, a great uplift of the rocks that involves all the geologic formations he has seen on his journey and even the underlying granite in a large area in the middle of the uplift. The sedimentary rocks on the east side of this elongated dome have been sharply upturned, and the heavy beds of sandstone between the notches cut by the streams have been left standing as great tables tilted to the east at an angle of 30° or 40°, which as seen from the train resemble the teeth of a gigantic saw. This line of tilted sandstone can be followed by the eye for many miles, but in the distance it fades into the misty blue of the desert. The beds nearer the traveler are upturned less steeply and have not been removed by erosion, so they form a great swell, but even where the rocks lie nearly flat the streams have cut into them deep canyons, having nearly or quite vertical sides, which measure hundreds or perhaps a thousand feet in height. The profiles are all angular; they are composed of straight lines; and when viewed from a distance these immense pinnacles of rock resemble the ruins of some ancient city, and in imagination one can see in them the remains of temples, pyramids, columns, and arches standing in grandeur amid the wreck of the structures of which they once formed a part. Here one can not resist the temptation to let the imagination have free rein—to rebuild these ruins as wonderful habitations of ancient giants and to picture the dramas that may have been enacted in them. If the traveler is fortunate enough to see these ruins when the sun is just setting behind their massive piles and suffusing their domes and pinnacles with great golden halos he can readily understand how a savage race might have here received the inspiration to build a magnificent temple to the sun, which to our minds might rival the most wonderful temples of the Egyptian kings.

At the point where the railroad makes the turn around the Beckwith Plateau it is at a considerable distance from the front of the plateau, but farther north it approaches the front more and more closely, until near the siding called Desert it is so close that the traveler may see, if the light is just right, all the delicate lines of erosion that the rain has cut in the shale slope.

The great anticline called the San Rafael Swell extends far to the north, and the rocks of the Book Cliffs bear the same relation to those in the anticline as the rocks of the Book Cliffs at Grand Junction bear to those of the Uncompahgre Plateau. The Book Cliffs west of Green River look different from those with which the traveler is familiar east of it. East of Green River the rocks weather into many projecting points or salients of hard rock, and between these points there are deep notches or reentrant angles. In addition, the upper beds of sandstone have weathered back much farther than the lower beds, but each layer is characterized by the same kind of salients and reentrant angles. The result of this form of weathering is a front that is extremely irregular and jagged. West of Green River the front of the Book Cliffs is very regular; it shows no tendency to weather into long points. This difference is probably due to the absence of streams and to the presence of a greater number of beds of sandstone in the west than in the east, as well as to the more massive character of these beds and to the greater dips which prevail in this part of the plateau, for all these characteristics would give a very different result in the forms produced by erosion. The Book Cliffs west of Green River are characterized by many bands of sandstone, which may be followed by the eye for long distances and which produce slight benches on the slope. A profile of a part of the front of the Beckwith Plateau is shown in figure 55.

FIGURE 55.—Profile of front of Beckwith Plateau

A geologist accustomed to interpret the meaning of land forms sees almost everywhere in these shale areas fragments of older surfaces of the land, preserved in terraces and benches. Some of these remnants of an older surface were pointed out west of Grand Junction and again near Thompson. West of Green River they grow more and more prominent as the traveler approaches the head of the stream. They stand at different heights above the present general surface, but commonly some particular terrace—one that ranges in height from 50 to 200 feet above the present surface is more prominent than the rest. The old surface in this region was probably more nearly smooth and regular than the surface of to-day, and its slope was doubtless not so great as that of the present surface. After this old surface had been well developed, the lower country, though it showed considerable differences in elevation between the higher and the lower parts of its slopes, must have formed one general plain. Then came a change, either an uplift of the land or an increase in the rainfall. At any rate, the streams were able to cut deep trenches in this old surface, and their work has been continued so long that it has left, here and there, only remnants of the once continuous surface, and these remnants are the terraces and benches that we see to-day. Terraces are very prominent in places west of Woodside, and the traveler may be interested in studying them, not as terraces but as remnants of that old surface. Indeed, he may be able in imagination to reconstruct from them the old surface as it existed before the streams had cut into it and carved the valleys of to-day.

The railroad rises steadily until it reaches a local summit at Cliff siding, between mileposts 574 and 575, and then begins a rapid descent to Price River, the master stream in the north end of Castle Valley. This stream heads on the Wasatch Plateau, far to the northwest, and flows across the north end of the San Rafael Swell, beyond which it joins Green River through a deep canyon cut in the Book Cliffs just north of the Beckwith Plateau. The traveler may see the entrance to this canyon by looking ahead on the east (right) after passing Cliff siding.

The line of cottonwood trees that marks the course of Price River may be seen long before the train has reached the bottom of the valley, and their soft green color is very refreshing to the eye that has been gazing on the barren expanse of desert just crossed. At Woodside the railroad crosses Price River, which the traveler unaccustomed to this region may not be willing to call a river unless he remembers that most of the water it normally carries is withdrawn for irrigation farther upstream, and then he may wonder that any water at all is left in it at Woodside.

For a distance of about 3 miles the railroad follows the east bank of the river through groves of cottonwood trees and small irrigated farms. Its course here lies near the west margin of the belt of shale, and the underlying sandstone (Dakota) and the red and green rocks of the McElmo may be seen at many places across the river on the left. Near milepost 583 the river ceases to follow the shale and swings in from the west, where it has cut a deep and narrow canyon in the hard rocks across the north end of the San Rafael Swell. The railroad engineers sought to avoid this canyon by following the broad valley that Grassy Creek has cut in the shale. This valley is the extension of the one that the train has followed ever since it left Green River.

The valley was not formed by a downfold in the rocks but simply by the erosion of the soft Mancos shale. The traveler may understand this easily by looking at the higher rocks in the face of the Book Cliffs on the east and the lower rocks in the San Rafael Swell on the west and noticing that they dip in the same direction—toward the northeast. From time to time as the traveler may be able to look ahead he can see that apparently the valley is filled and cut off by terraces that rise 100 feet or more above the level of the track, as shown in figure 56. These terraces appear to bar the further passage of the railroad, so it turns to the left a short distance beyond Grassy siding and climbs out of the shale valley. In making this climb the road turns and twists about some of the barren shale hills, cuts through others, and finally, at Cedar siding, approaches the margin of the shale and at the same time attains the level of the great terraces that were so conspicuous from points near Grassy siding. When seen from their own level these terraces are very extensive and appear like a vast flat plain.

FIGURE 56.—Terraces at head of Grassy Creek valley.

In the vicinity of Cedar siding the lower part of the shale contains many beds of sandstone and some conglomerate. This part of he formation thickens considerably toward the south for 20 or 30 miles to a place where it contains several valuable beds of coal and is known as the Ferron sandstone. About a mile west of Cedar siding a sharp upward bend of the rocks terminates the outcrop of the shale and brings to the surface the Dakota sandstone and, underlying the maroon and green beds of the McElmo. The railroad at this point t is on the bank of a creek called Sunnyside Wash, and it follows the valley of this stream to the north until near milepost 600 the railroad passes from the varicolored beds of the McElmo into a broad flat valley cut in the Mancos shale.