16 EEPOKT UNITED STATES GEOLOGICAL SURVEY. 



the caiion- walls. Moreover, the surroanding rocks are among the soft- 

 est that occur in the region, while those which form the mass of the 

 mountains, and, conseqeutly, the caiion-walls, are the hardest ; and it is 

 not probable that these relative conditions have materially changed 

 since the caiion s were cut. 



There is a considerable amount of irrigable land in the immediate 

 vicinity of the river, in Axial Basin, both above and below Yampa 

 Mountain; but a very large part of the surface of even the lower por- 

 tion of the basin is above the reach of irrigating- waters. 



Lily's Parle. — This park lies between Junction Mountain and the east- 

 ern eud of the Uinta Mountain chain, and is continuous with Axial Ba- 

 sin around both the northern and southern sides of Junction Mount- 

 ain. It is here that Snake River has its confluence with the Yampa, 

 the former river passing between Junction Mountain and the east- 

 ern end of the Uinta Uplift proper. After passing through Lily's 

 Park a distance of six or seven miles, and receiving the influx of Snake 

 River, Yampa River cuts through a line of hogbacks composed of Tri- 

 assic strata, and then almost immediately enters Yampa Caiion, pres- 

 ently to be described. Lily's Park embraces quite a large area of land 

 tUat may be irrigated from both the Yampa and Snake Rivers. Al- 

 though small, it is doubtless the finest body of irrigable land within the 

 district. 



Yampa Caiion. — If it were not for the existence of the much greater 

 and grander caiions of the Green and Colorado Rivers, Yampa Caiion 

 would be worthy of renown for its great length and depth. This caiion 

 begins at tbe eastern end of the Uinta Uplift and ends at Echo Park, 

 where the Yampa has its confluence with Green River. The distance 

 in a straight line from its eastern to its western end is about 25 miles, but 

 its tortuous course makes its actual length much greater. Its general 

 course is east and west and near the northern boundary-line of this dis- 

 trict, but it passes to the north of that boundary-line a few miles be- 

 fore it reaches Green River. Its course is along the southern side of 

 the south flexure of the axial portion of the great Uinta Uplift, and 

 approximately parallel with the synclinal flexure between the Plateau 

 and Uinta Uplifts that I have called the Yampa Flexure. Along the 

 greater part of its length the caiion-walls are nearly or quite perpen- 

 dicular, and often more than a thousand feet in height above the sur- 

 face of the river. 



As one stands upon the north side of Yampa Plateau, at the southern 

 brink of Red Rock Basin, the bottom of which is about 2,000 feet be- 

 neath him, looking northward over and beyond the basin, upon the 

 broad mountain slope that forms its high northern side, he gets only 

 occasional glimpses of the position of the canon as it meanders through 

 that great rugged surface. So sharply perpendicular are the walls of 

 the caiion on either side that the observer from the point mentioned not 

 only sees it imperfectly, even when it is at all visible, but even when he has 

 clambered over the rugged clifts that rise around the caiion, he hardly 

 realizes its presence in the neighborhood until he comes upon its verge 

 and finds himself at a dizzy height above the rushing, roaring river at 

 its bottom — so high that the river looks like a brooklet, and its roaring 

 is changed to a faint murmer before it reaches the ear. These are 

 among the grander and more impressive scenes which this region 

 affords", and once witnessed will never be forgotten. 



Williams Forlc. — This stream, although a small one, is the principal 

 tributary of the Yampa within this district. It rises among the ravines 

 of the western side of White River Plateau and flows across the north- 



