THE EOCENE OF NORTH AMERICA 453 



group, but at the places where the junction between the two 

 groups have been seen in this region there is an evident uncon- 

 formity, both of displacement and of erosion. The group con- 

 sists of fine and course sandstones, with frequent layers of gravel, 

 and occasionally both cherty and calcareous layers occur. The 

 sandstones are sometimes firm and regularly bedded, and some- 

 times soft and partaking of the character of bad land material. 

 The color varies from gray to dull reddish-brown, the former 

 prevailing north of the Uinta Mountains, the latter south of 

 them." King says the lower members of the Uinta group are, 

 "chiefly rough, gritty conglomerates, passing up into finer 

 grained sandstones, and at certain points developing creamy, 

 calcareous beds." 1 



The vertebrate fossils show the Uinta to be a fresh water 

 deposit. Scott notes that a considerable break [physical ?] 

 occurs between the Bridger and the Uinta, and that earth move- 

 ments took place at this time. He makes the Uinta equivalent 

 to the Paris gypsum deposits 2 . Peterson finds the following 

 succession of strata in the Uinta basin. 3 (i) Wasatch; (2) con- 

 formably upon Wasatch, Green River; (3) conformably upon 

 Green River, a series of hard, brown sandstones, alternating with 

 greenish-gray clays ; (4) conformably upon this are layers of 

 coarse, brown sandstone alternating with shales; (5) "true Uinta 

 or Brown's Park beds of a fine grained soft material .... of 

 brick-red color." These last named beds are about 600 feet 

 thick. Describing the highest three (3, 4, and 5 above) Peterson 

 says : 4 "This uppermost strata [stratum] of the Uinta basin has 

 hitherto been reported as resting unconformably upon the 

 Bridger sediment, but no observable breaks were found to dis- 

 tinguish the true Uinta from underlying Bridger sediment. So 

 the writer found it necessary in collecting fossils to divide the 

 beds overlying the Green River shales into three different levels, 

 which are here arranged alphabetically in ascending position 



1 Loc. cit., p. 405. 2 Science, n. s., Vol. II, p. 499, 1895. 



sQuoted byOsborn, Bull. Amer. Mus. Nat. Hist., Vol. VII, p. 73, 1895. 

 4 Quoted by Osborn, loc. cit., p. 74. 



