COAST RANGES OF THE PACIFIC AND THE SAN ANDREAS FAULT SYSTEM 



The division of the Coast Ranges from San Francisco Bay southward to 

 Santa Maria will here be designated the Central Coast Ranges ( Fig. 29.2), 

 and the division north of San Francisco Bay to the Klamath Mountains 

 will be called the Northern Coast Ranges. A division in southern California 

 with pronounced east-west trends including the Santa Barbara, Ventura, 

 and Los Angeles districts is referred to as the Southern Coast Ranges or 

 Transverse Ranges. The Coast Ranges of Oregon and Washington are a 

 unit geologically and will be considered as a fourth division. They are 

 separated from the Northern Coast Ranges of California by the Klamath 

 Mountains, which are part of the Nevadan orogenic belt. 



The Sierra Baja California of southermost California or the Peninsular 

 ranges, and the peninsula of Baja California is a fifth division, but will be 

 discussed in Chapter 30. It is a complex of Nevadan geology and later 

 Cretaceous and Tertiary beds affected by folding and block faulting. 



Still another division, the sixth, remains to be mentioned, namely, the 

 submarine area south of the Transverse Ranges. This ocean bottom has 

 been found in recent years to be one of rugged relief, and the researchers 

 who have ventured a diagnosis of the topography there agree that it is 

 part of the continental framework. It is discussed in Chapter 32. 



CENTRAL COAST RANGES OF CALIFORNIA 



San Joaquin Embayment and the Diablo Uplift 



In the tectonic map of the Late Cretaceous, Plate 12, it will be seen that 

 the uplift of Salinia separated a basin of sedimentation to the north and 

 south in the region of the Central Coast Ranges. The chief change that 

 occurred in Early Tertiary time is that Salinia altered position and size 

 somewhat and became the Diablo uplift; and another small uplift, the 

 San Rafael, came into existence just to the south. The details of these 

 changes are shown in the paleotectonic maps of Fig. 29.3. Also, the trough 

 of deposition, the San Joaquin embayment, became less constricted op- 

 posite the uplifts and received from 5000 to 15,000 feet of sediments in the 

 site of the Central Coast Ranges, and 30,000 feet in the Southern Coast 

 Ranges. 



Under a later heading, the San Andreas fault system, it will be shown 



r. , 



Fig. 29.2. Index map of the Coast 

 Ranges and fault systems of Cali- 

 fornia. Compiled from the fault map 

 of California (1955), from Dibblee, 

 unpublished maps, and other sources. 



