WHITE EIVER EPOCH. 



15 



The foUowinop diagi-am represents without much detail the section in 

 Eastern Coloi-ado, along the Horse Tail Creek, from the Chalk Bluffs south- 

 ward. (See fig. 6, p. 16.) 



At both localities the lower beds cany the bones of the gigantic Chali- 

 cotJieriidce, Mevodus in Nebraska, and Symhorodon with Menodus in Colorado. 

 But few other types occur in this bed in Colorado, the great number of 

 genera and species being found in bed B, in which I did not discover' any 

 fragments of ChalicotJieriidce among a large quantity of remains of Ungu- 

 lata, Carnivora, Bodentia, etc. The lithology is as follows: Bed A is a 

 white calcareous soft clay rock, breaking into angular fragments. Bed 

 B has a similar mineral character, with frequently a red color of different 

 obscure shades. Bed C is a sandstone of varying persistence. Bed D is 

 a white argillaceous rock like that of bed A. Fossils are less numerous 

 than in bed B, and included no Symhorodons nor other ClinlicotJieriidce. 



The eastern area of this formation is the true White River epoch of 

 Hayden; the western deposits form the Truckee epoch of King. I named 



