WASATCH EPOCH. 9 



basis, besides several genera of pulmonate gastropods, including both thelimnophile and 

 geophile divisions. The Green Eiver Group has become somewhat noted for the fossil 

 fishes that have been discovered in its strata in Wyoming, and, like the Wasatch Group, 

 it has at various localities also furnished considerable collections of fossil vertebrates 

 and plants. 



Of the few vertebrate fossils known from the Green River division, 

 some are identical with those of the Wasatch, while at least one genus of 

 fishes is common to the Bridger. 



The Wasatch beds proper are much more widely distributed than those 

 of the Green River. They appear first in the south in Northwestern New 

 Mexico, and extend thence into the adjacent parts of Colorado. They are 

 exposed over extensive areas of Colorado west of the Rocky Mountains, 

 and reappear in Southwestern Wyoming. They extend along the western 

 portion of the Green River Valley, whose northern portion they entirely 

 occupy. On the eastern side of the Wind River Mountains it has, accord- 

 ing to Hayden, an exposure of from one to five miles in width for a distance 

 of one hundred miles, from the source of the Wind River to the Sweet 

 Water River. North of this point it fills the extensive basin of the Big 

 Horn River to the borders of Montana. It does not occur east of the Rocky 

 Mountain range. The thicknesses given by geologists are the following: 



Northwestern New Mexico (Cope). 



Feet. 



Ked-striped marls 1,500 



Eeddishbrown sandstone 1,000 



2,500 

 Bio San Juan, Colorado (Holmes). 



Coarse yellowish sandstones, alternating with variegated marls 1,200 



White and Tampa Reservations (Endlich and White). 



Chiefly yellow and reddish sandstones, alternating with shales 1,600 



Bear Eiver, Wyoming (Hayden). 



Eed-bauded marls 700 



Sandstones and shales 800 



1,500 

 Wind River Valley (Hayden). 



Variegated marls and sandstones 5,000 



The Green River division of the Wasatch is much less extensively 



distributed than the Wasatch proper. Its exposures are confined to the 



