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F. E. PEABODY AND J. M. SAVAGE 



strait at the southern end of the future corridor opened directly 

 westward from the southern San Joaquin embayment. In view of 

 the many complexities of Coast Range geology it is difificult to 

 follow in detail the rapid geomorphic changes attending Coast Range 

 orogeny. However, the distribution of the modern herpetofauna in 

 California suggests strongly that there was an important marine 

 barrier in the position of the present Southern Coast Ranges, in fact 



• PLANTS 



o VERTEBRATES 



Fig. 4. Distribution of terrestrial Pliocene and early Pleistocene 

 localities for plants and mammals suggestive of southern strait connect- 

 ing Pacific with San Joaquin embayment. 



precisely coincident with the strait shown in Fig. 3. Also a con- 

 tinuity northwestward from the strait is indicated. The continuity 

 need not have been geographic but was almost certainly zoogeo- 

 graphic, allowing free access to northern species of the herpetofauna 

 but not to southern species. Paleobotanical data (Axelrod, 1957) 

 indicate that the marine strait was not a barrier to northward ex- 

 tensions of tropical and subtropical floras (Fig. 5). In terms of the 

 herpetofauna, it seems reasonable to conceive of a long peninsula 

 or a series of closely adjacent islands forming a zoogeographic unit 

 extending southward from the San Francisco region and including 

 the Santa Lucia basement rocks as a relatively stable component. 



