BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 28, pp. 677-684 SEPTEMBER 30, 1917 



OIL FIELDS OF THE PACIFIC COAST^ 



BY ROBEllT W. PACK 



[Presented before the Society December 28, 191(>) 



CONTENTS 



Page 



Introduction 677 



Location of the oil fields 678 



The coast fields and the valley fields 679 



Origin of the oil 679 



Effect of geologic structure on accumulation of oil 680 



Migration of the oil 681 



Effect of unconformities on accumulation of oil 682 



Geologic features determining presence of oil 682 



The province of the geologist 682 



Introduction 



In a space so limited as tiiat whicli is available here one can not do 

 more than sketch, in the shortest sort of an outline, the features charac- 

 teristic of the oil fields along the Pacific coast of North America. The 

 writer will, therefore, present here only a brief discussion of the broader 

 geologic features that appear to be common to the California fields. Al- 

 though these fields are among the more recently developed ones, and 

 although the geology — stratigraphy and structure alike — of the region in 

 which the fields lie is woefully complicated, still the larger geologic feat- 

 ures that govern the occurrence of petroleum in these fields are pretty 

 well known, probably better known than they are for many other fields in 

 the United States. No attempt will be made to outline or to discuss the 

 areas of prospective value or to estimate the quantity of petroleum avail- 

 able in this region. 



1 This paper is one of a series composing a "Symposium on the Geology of Petroleum. 

 See this volume, p. 156. 



Manuscript received by the Secretary of the Society May 4, 1917. 



(077) 



