UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 6, No. 15, pp. 333-383, pis. 34-43 Issued December 2, 191 1 



NOTES ON THE LATER CENOZOIC HISTORY 

 OF THE MOHAVE DESERT REGION IN 

 SOUTHEASTERN CALIFORNIA 



BY 



CHAELES LAUEENCE BAKEE 



CONTENTS 



PAGE 



Introduction 334 



Location and Boundaries of the Mohave Desert 335 



Metamorphic, Plutonic, and Volcanic Eocks older than the Upper 



Miocene ......... '. 336 



The Oro Grande Series : 336 



Basement Eocks of the San Bernardino Eange : < 337 



Granitic Bedrock of the Mohave Desert and Contiguous Banges 338 



Lavas Perhaps Earlier in Age than Upper Miocene 338 



The Eosamond Series of Upper Miocene Age ..- 339 1 



Definition and Distribution of the Series 339 



Eosamond Exposure North of Barstow 342 



Basal Breccia Member 342 



Tuff -breccia Member .'. 342 



Fine Ashy and Shaly Tuff Member 343 



Eesistant Breccia Member 344 



Fossiliferous Tuff Member 345 



Structure of the Eosamond Series in the Barstow Locality 346 



The Black Mountain Eosamond Exposure 347 



Tuff-breccia Member , 347 



Fine Ashy and Shaly Tuff Member 347 



Upper Member of Breccia and Tuff 348 



Structure of the Eosamond at Black Mountain 348 



Eosamond Beds in the Calico Mountains 349 



Tuff-breccia Member 351 



Borate Member 351 



Structure of the Eosamond Series in the Calico Mountains 352 



The Eosamond Series in the Type Locality at Eosamond 353 



The Eosamond Series in Eed Eock Canon 354 



Age of the Eosamond Series 357 



Origin and Mode of Deposition of the Eosamond Series :. 357 



