240 DESCRIPTIVE GEOLOGY. 



have already seen, at the head of Red Creek. To the west of Red Creek, 

 along the flanks of the mountains, they are upturned at a considerable angle, 

 and show a very distinct non-conformity with the beds of the Green River 

 series. In Henry's Fork basin, north of the Big Horn Ridges, they are rep- 

 resented by a series of red, somewhat clayey sandstones, which dip 25° to 

 the northward, at the base of a line of bluffs of buff calcareous sandstonse 

 of the Green River series, which have a dip of only 5° to the northward. 

 These beds are continued to the Avest of Green River in a series of red 

 banded sandstones, which fonii bluffs bordering the valley of Henry's Fork 

 on the north, and which, to the west of Henry's Fork, are underlaid by 

 coarse conglomerates dipping 25° to 35° northward, which represent the 

 lowest beds of the series observed here. The red sandy and clayey beds 

 are again found at the eastern base of Mount Corson, lying unconformably 

 beneath the Tertiaries of the Bridger group. At no point in this region was 

 a continuous section of the whole series of this group observed, nor, owing 

 to their non-conformity with the Laramie beds, was the base ever deter- 

 mined, hence their thickness is not known, but is estimated at not less than 

 3,000 feet. 



Geeen River Eocene. — The most characteristic development of the beds 

 of the Green River Eocene isfound in the hills along the west bank of the Green 

 River in the vicinity of Green River City. To the north of the railroad, they 

 form a plateau country, having a bluff face from 800 to 1,000 feet in height 

 to the south and east along the valley of Bitter Creek and that of its northern 

 tributary, and sloping off gently to the north and west. Through the 

 western portion of this plateau, the valley of Green River has been cut, 

 exposing along its eastern bank a line of bluffs, about 600 feet in height, 

 whose forms are peculiarly characteristic of the weathering of the beds of 

 this group. They are represented in Plate V, which gives a view taken 

 from a mile above Green River City, looking southwestward down the val- 

 ley of the Green River, along their base. To the south of the railroad, they 

 form a peculiar series of steeply-rounded ridges, which have received the 

 name of Alcove Ridges, from the shape of the deep, narrow ravines eroded 

 out of their western face. The aggregate thickness of the beds exposed in 

 this region is about 2,000 feet. They comprise a development of 800 to 



