146 



unconforraably underlies Miocene age sediments. The stratigraphic 

 section is shown diagraraatically in Figure 37 in which two possible 

 interpretations of the structure between the El Segundo oil field 

 and the outer shelf are presented. 



The f ossiliferous shales and mudstones dredged from the rock 

 and gravel area on the outer shelf are Upper Miocene in age and 

 correlate with the shales in the El Segundo oil field. The schist 

 recovered on the outer shelf is, therefore, correlative with 

 either the schist conglomerate or with the basement schist. The 

 structure between the outer shelf and the shore can be explained 

 by one of two theoretical structures or perhaps by a combination 

 of them. They ares (1) A very gentle dipping syncline or trough 

 exists with rocks of Upper Miocene age and possibly the schist 

 basement exposed on the western limb of the syncline, and Plio- 

 cene age rocks in the central part of the bay are covered by 

 sediments of the Quaternary age. Sediments derived from this 

 island and from land to the east eventually filled the trough, 

 (2) The Pal OS Verdes fault zone extends northwestward from the 

 Palos Verdes Hills and has uplifted the outer shelf several 

 thoussmd feet. Rocks younger than Miocene have subsequently 

 been eroded away leaving only Miocene and perhaps basement rocks 

 on the outer shelf. The Palos Verdes fault dips steeply to the 

 northeast along the north side of the hills, but it would have 

 to have a relatively low dip to account for the changes in the 

 thicknesses in overburden on the shelf. It is noteworthy that 

 Corey (1954) and Woodford, e_t al, (1954) show a continuation of 

 the Palos Verdes fault across the Santa Monica shelf. 



