288 Adventures in Scenery 



Where does the oil come from? If we knew the origin of oil 

 it would help in locating pools or sources from which oil might 

 be obtained. This is one of the problems of the petroleum 

 geologist. The nitrogenous element of California petroleum 

 furnishes perhaps the strongest evidence that the proteids (from 

 animal tissues) contribute a share to the make-up of petroleum, 

 and show that these particular oils are of animal origin. Emi- 

 nent geologists have regarded liquid petroleum as a natural 



Photo by W. S. W. Kew, U. S. Geol. Survey 

 FIG. 80. Simi Oil Field, Ventura County. 



distillate from carbonaceous deposits, which latter were laid 

 down at depths below the horizons where the oil is now found. 

 The heat generated during metamorphism is supposed to be 

 the dynamic agent in this process, although many productive 

 regions show no evidence that any violent metamorphism ever 

 occurred. In most cases geologists have subscribed to the 

 theory of the organic origin of petroleum, but their reasons 

 for so doing are generally the absence of igneous activity, and 

 the great mass of sediments containing organic remains in the 

 oil fields. The organic origin of petroleum seems to be best 



