260 DESCRIPTIVE GEOLOGY. 



exposed farther east in Connor's Valley. They correspond in 4ip and strike 

 with the Jurassic limestones before mentioned. 



Following the Sheep Creek trail, which passes up this valley, the 

 flanks of the main Uinta elevation are found to consist at first of wooded 

 ridges, running in general, parallel, to the strike of these rocks, and rising 

 higher as one proceeds. Of these, the first seems to be formed still of the 

 sandstones of the Triassic formation. The second and third ridges, how- 

 ever, show outcrops of the limestones of the Upper Coal-Measure group, 

 beyond which, in a basin-like country at the head of Sheep Creek, are 

 found the red sandstones and quartzites of the "Weber group, still striking 

 east and west, and dipping 30° to 35° north. This dip, however, soon 

 flattens out to 10° and 15°, and when the line of the main elevation, just 

 north of Leidy's Peak, is reached, the strata have already their gentle 

 southern dip, and in the sections exposed the greenish clay beds remarked 

 at Gilbert's Peak and farther west can be distinctly traced. On the sum- 

 mit of the range, the trail crosses a broad basin country, extending from 

 the eastern base of Marsh's and Leidy's Peaks nearly to Mount Lena, 

 in which the almost horizontal beds of Weber Quartzite have been smoothed 

 and furrowed by neves and glacial ice, their surface being now covered by 

 dense forests, and numerous shallow lakes, too small and too much hidden 

 by the trees to have been indicated on the map. 



Returning to the northern slope. Mount Corson, which lies between 

 the valley of Burnt Fork and that at the junction of Henry's Fork and 

 Green River, which we call the Henry Fork Basin, is a remnant of Tertiary 

 beds which has escaped erosion. It is a broad, flat-topped hill,^whose sum- 

 mit, and the upper portion of its slopes, are covered with timber ; at its 

 southern base lies Connor's Valley, already mentioned. The main mass 

 is composed of beds of the Bridger series, while the upper thousand feet 

 are made up of the conglomerates of the Wyoming group, — a more con- 

 siderable thickness of this formation than has been observed at any other 

 point. At its eastern base were found outcrops of coarse reddish sand 

 and gravel beds, whose angle of dip, though indistinct, shows an evident 

 unconformity with the horizontal Bridger beds of the main mass, and 

 which have been referred, as before mentioned, to the Vermillion Creek 



