VIII 



^ Preface 



deposited in topographic traps where rate of deposition exceeds 

 rate of erosion by water movements. The remains of organisms that 

 live in the water are deposited with other sediments at favorable 

 topographic positions. After compaction to rock, some of this or- 

 ganic matter is yielded as petroleum, which can then be recovered 

 economically where the rocks contain reservoir sandstones of 

 favorable structure and water depth. 



The immediate concern of oil geologists is that of locating 

 favorable sites of accumulation of petroleum, but a thorough under- 

 standing of petroleum includes background information on the 

 manner of deposition and alteration of organic materials. Accord- 

 ingly, an attempt will be made to describe the basic environmental 

 factors of the region and to relate them to each other and, when- 

 ever possible, to the general problem of origin and accumulation of 

 petroleum, one of the most important resources of the region. In 

 many respects the present sea floor basins are similar to ancestral 

 forms of several basins which have become filled with sediments 

 and are now rich oil-producing areas on land in southern California. 

 The similarities were recognized by several workers at about the 

 same time: Trask in 1932 for organic matter, Natland in 1933 for 

 foraminiferal ecology, and Reed in 1933 for structural geology. 

 Since the time of these early publications, much additional material 

 has been uncovered. 



Although the economic view is appreciated, the objective of this 

 book is the integration of basic knowledge rather than the pointing 

 out of prospective sites for mining or oil drilling. Little space will 

 be used to describe methods of samphng because these are ade- 

 quately covered in other works or can best be learned aboard ship. 



Ideas presented in this book have evolved during a period of 

 about twenty-two years through discussions with many workers, 

 questions from students, and sohtary musings. Special thanks are 

 due Dr. Bruce C. Heezen for his critical review of the manuscript. 

 To all others who have aided in one way or another, on land or at 

 sea, the writer expresses his deep appreciation. 



K. O. Emery 



Allan Hancock Foundation 

 University of Southern California 

 Los Angeles, California 

 November 1959 



