256 Tertiary. 



chiefly arenaceous, were deposited in greater thickness than either of 

 the other groups, and extended from the base of the Park range to 

 the flanks of the Wasatch mountains. The beds of the Green river 

 series contrast with those of the other two groups by the relative prev- 

 alence of calcareous material, and the fineness of their sediments. They 

 consist of a lower series of calcareous sandstones and impure limestones, 

 containing some lignite seams, overlaid by a great thickness of re- 

 markably fissile calcareous shales, abounding in remains of fish and 

 insects, which reach an aggregate thickness of about 2,000 feet, and 

 are characterized throughout b^^ their prevailing white color. The 

 Bridger Group consists of a thickness of about 2,500 feet of arenaceous 

 beds, with a small development of calcareous material, of a prevailing- 

 dull, greenish-gray color, characterized by the great quantity of verte- 

 brate remains which have been buried in them. Its greatest develop- 

 ment is in the southern portion of the Bridger basin. In the Washakie 

 basin, on the western borders of the Little Muddy creek, and at Wash- 

 akie mountain and Cathedral bluff's, the Wasatch series are exposed, 

 weathering in castellated forms, and recognizable from great distances 

 by their bright pinkish and reddish coloring. Washakie mountain 

 and the line of bluflfs which extend to Cathedral bluff's, are formed of 

 beds of the Green river series in the upper portion, and with the red 

 Wasatch beds at the base, the line of division can be distinctly traced, 

 descending somewhat in horizon toward Barrel springs, and ascending 

 again beyond toward Cathedral bluff's. A section taken at Sunny 

 Point, near Little Snake river, gave a thickness from the river to the 

 summit of the cliff' of about 2,000 feet. The upper 950 feet belonging 

 to the Green river series, and the remaining 1,050 feet to the Wasatch 

 Group. The Green RiA^er Group is exposed in the valle^^ of Brown's 

 Park, which is a bay-like depression, from 6 to 8 miles in width, occu- 

 pying the geological axis of the eastern end of the Uinta mountains, 

 from 1,000 to 1,200 feet in thickness. Throughout the valleys of the 

 Little Snake and Yampa rivers, these groups have been worn into 

 rounded ridges, where, generally, only disintegrated material is found. 

 In the basin of Vermillion creek, the beds of the Wasatch Group have 

 their greatest development. It was on one of the broad benches, be- 

 tween the branches of this creek, to the east-of Rub}^ Gulch, that the 

 originators of the famous diamond fraud, of the summer of 1872, lo- 

 cated their pretended discovery. An exposure of coarse, iron-stained 

 sandstone, on the surface of the mesa, at' the foot of Diamond Peak, 

 was strewn bv them with rough diamonds and rubies, which were in- 



