ENVIRONMENT OP THE TITANOTHERES 



87 



fossiliferous Uinta A, to the south. Its contempo- 

 raneity with Bridger D is established through the 

 common presence of the following species: 



Uintatherium robustum. 

 Uintatherium mirabile. 

 Manteoceras manteoceras. 

 Notharctus tenebrosus Leidy. 

 Hyrachyus princeps Leidy. 

 Sinopa. 



Palaeosyops copei Osborn. 

 Mesatirhinus megarhinus. 

 Mesatirhinus petersoni. 

 Hyopsodus. 

 Paramys. 



I bench, which constitutes the lower rim of the basin 

 I on its northern border. This "lower brown sand- 

 I stone" passes at a low angle southward beneath the 

 floor of the basin. Below it, and apparently conform- 

 able with it, lie gray sandy shales, which are pro- 

 visionally referred to the Green River but which 

 were probably laid down in lower Bridger time 

 (Bridger A and perhaps Bridger B). As these deposits 

 I show no marked evidence of erosion it seems probable 



fShale? 

 Nos. 35,36,37 



[Sandstone 



Nos. 25, 26a, 26 b 



Nos. 20,21, 22 



STACK MT^ 



LOWER BROV 



Figure 59. — Diagrammatic vertical section of deposits near Barrel Springs, Washakie 

 Basin, southern Wyoming 



Shows the alternation of tuffs, siliceous, calcareous, and sandstone materials. Johannsen (1914.1), after 

 Granger, with modifications. The numbers refer to lithologic specimens examined by Johannsen. 



This fauna of the Uintatherium zone occurs in 260 

 feet of Washalde A, which is composed largely of 

 altered eruptive rocks, probably dacite tuffs, of cal- 

 careous and siliceous shales, and of glass tuffs mingled 

 with grains of quartz, hornblende, feldspar, according 

 to the analysis of Johannsen (1914.1, p. 214). 



The "lower brown sandstone" layer yields a rich 

 fauna of uintatheres. This layer forms a persistent 



that the Washakie Basin was filled wi^h a lake in 

 Green River time whUe Bridger A was being deposited 

 to the west. 



Washakie B {Metarhinus and Eohasileus-DolicJio- 

 rhinus zones, upper Eocene). — The upper Eocene 

 Washakie B horizon is described on pages 89-90, in 

 the description of upper Eocene faunal zones 13 and 

 14, to which it belongs. 



