BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 29, pp. 297-308 June 3o, i918 



PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



MAEINE OLIGOC^ENE OF THE WEST COAST OF NOETH 



AMERICA- 



BY BRUCE L. CLARK AND RALPH ARNOLD 



{Bead before the raleonlological Society January 2, 1918) 



CONTENTS 



I'age 



[iitroductor,^- remarks 297 



Oligoceiie of California 299 



San Lorenzo formation 299 



I *aleogeograpli.v 300 



Stratigrapliic relationsliip to Upper Eocene 300 



Comparison of distributions of Oligocene and Lower Miocene 301 



Distribution of Oligocene in Oregon and Washington 303 



Fauna and climatic conditions of Oligocene 303 



Cieneral ol)sei'vations 303 



Faunal zones , 304 



Climatic conditions 306 



Eocene-Miocene relationships 307 



iN^TRODrcroiiy Eemarks 



k 



This paper comprises a general survey of the known data concerning 

 tlie ])aleogeographv, climatic conditions, and faunal relationships of the 

 Oligocene as Found in Califoi-nia, Oregon, Washington, and Vancouver 

 Lsland. 



Tlie great thickness of the marine Tertiary sediments on the West 

 (^oast forms a striking contrast to the much thinner deposits of the same 

 age found in the Gulf and Atlantic Coastal Plain province; also the evi- 

 dences of crustal movements of enormous magnitude, which are repre- 

 sented by great angular unconformities at various liorizons in the Ter- 

 tiary of the West (V)ast, indicate conditions very diflercnt from those 

 which existed during the same gcnci-al pci'iod in tlie east(u-n region. Tlie 



* Manuscript received by tlie Secretary ul" (lie Society March r>. lOlS. 



XXI n— Bull. Gkol. Soc. Am.. Vol. L>n. 1017 (297) 



