108 



TITANOTHEKES OF ANCIENT WYOMING, DAKOTA, AND NEBRASEA. 



Chadron. Fonnatioii 

 (TitanotheT-ibUTL 7,OTie} 



C OLORAD O 



Castle Rock 



K A N" S A S 



100 120 140 160 MILES 



Figure 75. — Map showing principal exposures of tlie Chadron formation {Titanotherium zone) of Montana, Soutli 



Dakota, Wyoming, Nebraska, and Colorado 



Chiefly after Darton, 1905, United States Geological Survey. Includes the exposures at Castle Rock (Castle Rock conglomerate), south of Denver, in 

 Weld and Logan Counties, Colo., where the early collections of Marsh and Cope were made: iu the outlying localities of Bates Hole and Hat Creek, 

 Wyo., from which the Reed and Hatcher collections were made; and in the Big Badlands of Pennington, Custer, and Washington Counties, S. Dak. 

 The Titanotherium zone was first observed by Hayden at point X on map and was first subdivided faunistically by Hatcher. 



