424 GEOLOGICAL SURVEY OF THE TERRITORIES. 



running clown into the valley, and terminating in tongues of sloping 

 mesa. 



Between longitude 107° 55', and the mouth of Roubideau's Creek, 

 the Gunnisora occupies the bottom of this valley, with a fertile bottom 

 upward of two miles in width, in which the river is very sluggish and 

 winding, with numerous sloughs and backwaters. Below the mouth of 

 Eoubideau's Creek the river does not occupy the lowest part of the val- 

 ley ; the latter lies between the river and the great plateau, about three 

 miles, generally speaking, east of the former, and follows its general 

 course. From this lowest part of the valley the laud rises slowly toward 

 the west, and, in a canon, which originated in a monoclinal fracture, 

 closely huggiug the plateau on the west side of the valley, the Gunnison 

 has its course. This canon, known to the Indians as the Unaweep, is in 

 stratified rocks, of the most brilliant colors. It has an average depth 

 of about 800 feet, with walls absolutely vertical. The river-bottom is 

 quite broad, and the river is sluggish and winding, now undermining 

 one wall, now wandering across the broad and fertile bottom to the 

 other. The soil in this bottom must be excellent for agricultural pur- 

 poses. 



The remainder of this great valley lies on the south side of the Gun- 

 nison River, extending up the Uncompahgre River for upward of forty 

 miles, with an average width of eighteen to twenty miles. On the west 

 it rises gradually into a plateau. On the east it is limited by the plateau 

 in which the Grand Canon of the Gunnison is cut, and by spurs from 

 the Uncompahgre range, and on the south by this range. The stream- 

 bottoms in this part of the valley are, as in the otber, very fertile, 

 and quite broad, with a heavy growth of cottonwoods. The rest of 

 this portion of the valley consists of perfectly flat bench-land, rising 

 in regular steps from the streams to an elevation of about 200 feet above 

 them. Throughout the valley the bench-land is very poor, with a clay or 

 gravelly soil, containing always some alkali, and in many places strongly 

 impregnated with it. There is very little grass, indeed. Sage, grease- 

 wood, and several species of cactus, form almost the sole vegetation. 

 A great deal of the water sinks, so that, except in the spring, only the 

 larger streams contain any water, and the water of the larger streams 

 is more or less alkaline. Between the Grand and the Gunnison, Kahnah 

 Creek and b creek (of the Gunnison) are almost the only streams 

 containing water in October, and, south of the Gunnison, the Uncom- 

 pahgre is the only stream in the valley which is not dry at that time of 

 the year. Cedar Creek and Roubideau's Creek are dry. It is in this 

 valley of the Uncompahgre and the Gunnison that the Utes usually 

 have their winter quarters. 



The Gunnison River heads under Italian peak, and its upper branches 

 drain the southern slopes of the Elk Mountains and the western slopes 

 of the Sawatch range. The branches which drain the Elk Mountains 

 have a general direction of 30° east of south, as is the case with Slate 

 River, East River, Ohio Creek, and the numerous parallel streams west of 

 Ohio Creek. The main stream is in a narrow valley for several miles below 

 its head, extending nearly down to the mouth of Pass Creek. Thence 

 to Park Cone it is in a broad valley of gravelly soil, which is mainly a 

 glacial deposit. At Park Cone, it enters a caiion, by which it cuts its 

 way through the eastern range of the Elk Mouutains. This caiion is 

 cut in granite, is sixteen miles long and is, on an average, 1,200 feet 

 deep. In this canon, a large branch, Taylor River, enters the Gunnison 

 from the north. Just below its foot, the next large tributary, Slate 

 River, comes in. This stream and its tributary, East River, drain a 



