194 DESCEIPTIVE GEOLOGY. 



transversely through the heart of the range, to emerge again into the open 

 region south of the Colorado Plateau. 



The sinuousness and irregularity of the course of Green River through 

 the Uinta Range, and its independence of the present topographical fea- 

 tures of the region, suggest that it must have been determined originally in 

 rocks of an entirely different nature from those, through which it now lies; 

 and a confirmation of this idea is found, as will be seen later, in the exist- 

 ence of undisturbed Tertiary beds at a level higher than the present walls 

 of the different canons of the river, and which must once have extended 

 across, and in a great measure covered, that part of the mountains through 

 which it flows. 



Uinta Range. — The Uinta Range, which forms the southern boundary 

 of the Green River Basin, is the only considerable mountain uplift within 

 the limits of our exploration, and, indeed, with few exceptions in the whole 

 Cordilleran system of the United States, which has an east and west trend. 

 In its physical features, as well as in geological structure, it differs essentially 

 from all of the mountain-ranges of the region examined by us, and in both 

 respects is characterized by a grand simplicity and regularity of structure. 



Its extreme length is about 1 50 miles, of Avhich the western 25 extend 

 beyond the limits of this map. Of this extent, the eastern third is some- 

 what irregular in form, but the main body of the range is a broad, 

 straight ridge, whose crest, which has an average elevation of 10,000 to 

 11,000 feet, is a forest-covered region of rounded glacier-basins, studded 

 by hundreds of shallow lakelets, and scored on either flank by deep, 

 straight glacier-canons. Out of the higher portion of this crest rises a series 

 of narrow precipitous ridges and peaks, entirely bare, of vegetation, ^vhose 

 principal summits attain elevations of over 13,000 feet. 



The scenery of this elevated region is singularly wild and picturesque, 

 both in form and coloring. In the higher portions of the range, where the 

 forest-growth is extremely scanty, the effect is that of desolate grandeur ; 

 but in the lower basin-like valleys, Avhich support a heavy growth of conif- 

 erous trees, the view of one of these mountain-lakes, with its deep-green 

 water and fringe of meadow-land, set in the sombre frame of pine forests, 

 the whole enclosed by high walls of reddish-pui-ple rock, whose horizontal 



