Geological Survey Bulletin 612 Guidebook of the Western United States: Part B

SHEET No. 11. (click on image for an enlargement in a new window)

The station at Grenville (see sheet 11, p. 68) is little more than a pump house. Water from the wells that furnish the domestic supply for the town of Rawlins is not suitable for use in locomotives because it contains mineral matter that incrusts the boilers. Consequently water for generating steam is pumped to Rawlins from North Platte River at Fort Steele, a distance of 15 miles, with a lift of 236 feet.

Far to the north may be seen the Seminoe Mountains, named for Seminoe Lajeunesse,¹ a French trapper and fur trader. In plain sight also north of Grenville, although about 30 miles away, is a range of mountains with striking white scallops on their southern flank. These are the Ferris Mountains, lying just west of the Seminoe Range. The white scallops are vertical beds of limestone which have resisted erosion while the softer beds around them have been worn away. These mountains were named for George Ferris, one of the early settlers in this region, whose name has been applied to several of its natural features and many of its enterprises.

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¹It is said that Lajeunesse's real name was Basil and that the name Seminoe was corrupted from a French nickname, "Cimineau," although some reports have it that Seminoe was the name given to him by his Snake squaw. Lajeunesse established a trading post on the Overland Trail above Devils Gate. Early in the sixties, with two men and fifteen pack animals loaded with goods, he started out to trade with the Sioux. On the way the party was attacked by Indians in Bates Hole, southwest of Casper, and Lajeunesse was killed. Lajeunesse was a successful hunter and trapper, and the old settlers who remember him say that the mountains were called Seminoe to perpetuate the name of one of the bravest and truest pioneers of Wyoming. He accompanied Frémont on the first expedition into Wyoming, and was one of those chosen to make the ascent of Fremont Peak. He is reported to have accompanied United States troops as a scout on a number of expeditions. His uncle, Gabriel Lajeunesse, was, so tradition says, the hero of Longfellow's "Evangeline."

It is interesting to note that some recent maps show these mountains as the Seminole Mountains, the compilers of the maps evidently assuming that they were named for the Seminole Indians and that the "l". had been omitted by mistake from the maps on which they were shown as Seminoe.

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South of Grenville the rocks, which have been domed, are eroded so deeply that the Mowry shale is exposed at the surface in the center of the dome and the several sandstones of the Frontier formation lie in concentric ridges around it. The shale between these sandstones contains limestone concretions in which are shark teeth, ammonites, scaphites, and other fossils of marine animals that indicate Upper Cretaceous (Benton) age. These sandstones contain oil in some places, and for the purpose of ascertaining their depth south of Rawlins, where a well was started near the base of the Mesaverde formation, the shale was carefully measured at a favorable exposure south of Grenville, where it was found that the sandstone lies 2,200 feet below the lowest sandstone ledge of the transitional zone between the Mesaverde and the Steele shale. The shale between the base of the Mesaverde and the Frontier is therefore somewhat more than 2,200 feet thick.

A few miles east of Rawlins the outcropping edges of the several formations are passed over in rapid succession. These strata are upturned around the Rawlins dome¹ and range in age from Cambrian up to Cretaceous. (See table on p. 2.) Some of these formations can not be seen to advantage from the train. From the geologist's point of view it is unfortunate, though inevitable, that railroads are built where the easiest grades can be obtained rather than where the rocks are best exposed. The sandstone of the Frontier formation may be recognized by low ridges through which shallow cuts have been made, and the Cloverly forms a prominent ridge seen to the right (north) of the track. The pink beds of the Morrison formation appear to the south and the brick-red beds of the Chugwater formation to the north.

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¹ The center of the Rawlins uplift consists of granite which reaches an altitude of more than 7,600 feet in the hills north of the railroad. Around this granite core and sloping away from it are the sedimentary rocks. The oldest, the Cambrian quartzite, is very hard and forms conspicuous slopes. The railroad is built through a narrow gap in these rocks west of Rawlins. (See Pl. XIII, A, p. 61.) The Carboniferous limestone lies in general unconformably on the Cambrian quartzite, but is separated from it in some places by beds of iron ore. Red sedimentary rocks that lie above this limestone are separated into two parts by a layer of similar limestone. It is possible that the upper part represents the Chugwater red beds and the lower part the Casper formation of the Laramie region.

PLATE XIII.—A (top) GAP IN THE CAMBRIAN QUARTZITE THROUGH WHICH THE WESTBOUND TOURIST PASSES AFTER LEAVING RAWLINS, WYO. Sagebrush in the foreground. B (bottom), CHARACTERISTIC VIEW OF THE RED DESERT. The plain is formed on Tertiary beds and covered with sand and sagebrush. The distant buttes are capped with harder beds which have prevented the rain and wind from wearing them down to the general level of the plain. Photograph furnished by Union Pacific Railroad Co.

The Sundance formation comes next, with its characteristic marine Jurassic fossils, and above it lie the variegated Morrison beds. These are succeeded by the Cloverly, which here, as elsewhere, consists of two sandstones, the lower one conglomeratic separated by dark shale. Above the upper sandstone is the Mowry shale, the sandstone of the Frontier formation and a body of shale which includes equivalents of the Steele shale and the Niobrara formation.

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The spring from which the town of Rawlins took its name was so designated in honor of Gen. J. A. Rawlins, Secretary of War under President Grant. The town is a shipping point for a large area both north and south of the railroad. It is the connecting station for Baggs and Dixon, in southern Wyoming, 70 miles to the south, and before the building of the "Moffat road" (Denver & Salt Lake) it supplied Craig, Hayden, and other places still farther south in northwestern Colorado. It is also a railroad division point.

In the old days a Government road ran southeastward from Rawlins to the White River Indian Agency, in what is now Rio Blanco County, Colo. Mail service was maintained on this road, and the bridge which the Government built across Snake River at Baggs is still in good condition.¹

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¹When the White River Utes massacred Indian Agent Meeker and his family the command sent south from Fort Steele under Maj. Thornburg followed the Government road as far as Baggs then swung west, crossing Little Snake River about 12 miles farther down and striking out southwest across the great rolling sage brush country which lies between Little Snake and Bear rivers. Their guide must have known the country thoroughly, for their route, still known as the Thornburg road, takes advantage of every topographic feature and every safe watering place. Some miles after crossing Bear River Maj. Thornburg decided, it is said against the remonstrances of his subordinates, to lead his command through a narrow valley. Here they were ambushed, and for three days and nights defended themselves as best they could, using the few wagons which they could get together and the bodies of dead horses as barricades. Two of the number escaped during the first night and brought word to Rawlins. When the relief expedition reached the scene, Maj. Thornburg and more than two-thirds of his command were dead.

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The dark-colored Cambrian quartzite is conspicuously exposed north of Rawlins, where it is overlain by light-colored Carboniferous limestone. The red oxide of iron at the base of the Carboniferous was formerly mined north of the town for paint.

West of Rawlins the formations on the Rawlins dome that were crossed east of the town are passed over in reverse order.

From points west of Rawlins the Ferris Mountains are again plainly visible far to the north, and a noticeable notch, called Whisky Gap, may be discerned at the west end of the range. Through this gap runs the old Rawlins-Lander stage road. West of this range are the Green Mountains, which are terminated on the West by a pass known as Crooks Gap, named for Gen. George H. Crook, a noted Indian fighter, whose name was given also to the creek that flows through the gap and to the mountain that lies just west of it.

Near Ferris siding the railroad crosses a low ridge of hills formed by the upturned sandstones of the Mesaverde formation, which constitute the eastern rim of the Great Divide Basin, a great depression in the older rocks filled with younger sediment. West of the ridge are the younger Cretaceous rocks, which are here steeply upturned, but which flatten out as they extend westward under this basin. About 2 miles east of Knobs siding the road reaches Tertiary beds, also steeply upturned here, but flattening out farther west. They consist of conglomeratic sandstone alternating with dark-colored shale, and in some places contain beds of coal. These rocks contain some fossil plants and shells of fresh-water mollusks.

Near the station called Daley's Ranch the train crosses the wide valley of Separation Creek, which, after following an erratic course for 60 miles, is lost in the Great Divide Basin. North of the railroad (to the right) may be seen in this valley the barns and corrals of a large sheep ranch. Less than 30 years ago the owner of this ranch was a section hand on the Union Pacific, but he is now a large property owner and has been a member of the State legislature. Many tales might be told of sudden rise to fortune in the early days of the sheep industry, before the ranges had been overstocked and depleted.

In Wood's cut, about 2 miles west of Cherokee, there is a poorly consolidated yellow conglomeratic sandstone resting with uneven base on dark-colored shale. This cut was made through a rise in the rolling plain, and here, as at hundreds of other places along the Union Pacific, the road needs protection against drifting snow. The windbreaks for this one cut cost $3,500.

At Creston siding the train crosses the divide between the Atlantic and Pacific slopes and a sign south of the track reads: "Divide of the Continent." As a matter of fact, the traveler is also within the Great Divide Basin. The ordinary conception of a divide is that of a mountain crest but here is the anomaly of a continental divide passing through an undrained basin that is about 60 miles across from north to south and 100 miles from east to west. This basin contains numerous salt and alkaline lakes, mud flats, and mud springs. Hayden, one of the earlier Government geologists, states that in the region between the Seminoe Hills and Rawlins he saw an interesting group of mud springs, analogous to the mud puffs of the geyser region in Yellowstone Park. About 400 of these curious springs were found and examined.

Throughout this part of the route the strata lie nearly horizontal, but there are long stretches of desert on which little can be seen except the bunches and tangled growths of stunted sagebrush and greasewood. (See Pl. XIII, B, p. 61.) This part of the Great Divide Basin is called the Red Desert. Coal beds crop out in it west of Latham siding, about 5 miles beyond Creston, but the coal is of poor quality and little use has been made of it. West of Creston is obtained the first comprehensive view of the Red Desert. A few miles north of the track is a great stretch of sand dunes, which extends 100 miles, from Green River to North Platte River. The dunes, many of them more than a hundred feet high, are constantly traveling with the prevailing winds in a direction a little north of east. If a few camels and an Arab or two were added to the scene, the spectator could easily imagine himself in the Sahara Desert. Frequent mirages, endless variety of feature, and wonderful coloring make the desert far from the monotonous stretch it may seem to be at first glance. As the name suggests, the dominant colors are red—russet, brick-red, and vermilion—but there is every tone of gray and brown, with not a few shades of green, purple, and yellow. Unlike the colors of an eastern landscape, those of the Red Desert are not dependent on the season, for there is little vegetation to hide the coloring of the rocks and soil.

Despite the sparsity of vegetable growth, the Red Desert is a winter sheep range. The scattered "bunch grass," which looks so meager and dry, is in fact excellent forage, curing into hay where it grew and having a high nutritive value. In summer, when the desert is dry and water holes are few, the sheep are herded in the mountains, where water is abundant and grass is green and tender. The early snows, falling first in the higher mountains and extending week by week to lower altitudes, drive the flocks into the rough fall range between the mountains and the desert. Here they are held until the snow falls on the desert itself, but with the first heavy snowfall they are driven from the foothills to spend the winter in the open, where they find pasture in the spaces cleared of snow by the winds. The winds are not tempered here, but neither is the lamb shorn, and Wyoming winter winds make heavy wool when shearing time comes.

It may be noted that the great problem of stock raising in this western country is not so much to find pasturage—although the range has been greatly overstocked—as to find water. This is true not only in the Red Desert but in almost every grazing area throughout the semiarid States. Places at which stock may be watered are so few that control of them in general means control of the entire pasture range. In years gone by it was the custom for large stock owners to acquire a number of water holes and so possess themselves of great grazing areas as effectively as if they owned every acre of them. In recent years the Government has attempted to break up this practice by creating public water reserves which are open to the use of all comers, thus giving the small stock grower an equal chance with his more powerful rival.

In the Indian days the southern Red Desert constituted a more or less neutral territory among the numerous tribes. To the north were the Shoshones or Snakes, to the northeast the Crows, and to the south the Utes, but this territory was the common hunting ground and battle ground of all. In 1906, when the Uncompahgre Utes jumped the reservation in northeastern Utah and ranged northeastward across Wyoming, they held a great antelope round-up in the Red Desert, forming in genuine Indian style a great circle of riders which gradually drew in until the frightened antelope were concentrated in the center and killed. About 400 Indians took part in this round-up. Although they traveled several hundred miles from their reservation, and although it required a regiment of United States troops to awe them into surrender, no one was killed.

Wamsutter, formerly called Washakie, is a division point on the railroad. It is the site of old Fort Washakie, built for the protection of railroad employees and emigrants from the Shoshone and Arapahoe Indians. Three deep wells have been sunk to water here by the railway company, the deepest boring going down 1,900 feet. The coal beds of the Wasatch group (Tertiary) were penetrated near the surface, and those in the undifferentiated Tertiary at several lower levels. The color and lithologic character of the beds penetrated indicate that the well probably did not go entirely through the Tertiary beds. Similar beds were struck in a well 1,115 feet deep at Red Desert station, 9 miles west of Wamsutter.