428 University of California Publications in Geology [Vol. 8 



Mediterranean Sea, and should be classed as middle temperate. 

 Twenty-nine Keeent species are known from the San Pablo and of 

 these eighteen range as far south as San Diego. 



We may conclude therefore that the fauna of the San Pablo lived 

 under fairly warm temperate conditions. 



CORRELATION 

 For the purpose of this paper the writer considers the Neocene 

 section of California to be divisible into Lower, Middle, and Upper 

 Neocene. The Lower Neocene as used here includes the "Vaqueros," 

 "Temblor," and "Monterey;" the Middle Neocene includes the San 

 Pablo Group (including the Santa Margarita of the southern part of 

 the state) ; the Upper Neocene includes the Etchegoin, Purissima, 

 Merced, Fernando, Wildcat, and the Pliocene deposits at San Diego 

 and San Pedro. 



Previous Contributions 



Before the position of the San Pablo in the marine Neocene section 

 of California is discussed, the writer will briefly review the papers 

 which contain data concerning the correlation of the San Pablo. 



No attempt was made by the early palaeontologists, Gabb, Conrad, 

 Cooper and others, to divide the Upper and Middle Neocene of Cali- 

 fornia into definite faunal zones. Even as late as 1895 little was known 

 about the faunal zones in the Upper and Middle Neocene. 



G. H. Ashley, 25 in a paper entitled, "The Neocene Stratigraphy of 

 the Santa Cruz Mountains in California," included all the Upper Neo- 

 cene of that area in the Merced Series. The base of the series was 

 believed to be close to the border line between Miocene and Pliocene. 

 Ashley recognized that in going from the bottom to the top of the 

 Merced series there was a change in the fauna. The fauna from the 

 base of the series was believed to be more closely related to the Miocene 

 than to the Pliocene, and these lower beds were called transitional 

 beds. On page 330, in speaking of these transition beds, he says : 



It would therefore seem that the lowest, or what might be called the Pecten 

 beds, are more closely related to the Miocene, but a rapidly changing fauna 

 soon gives the beds a Pliocene aspect which is maintained through most of 

 the section. 



" Proc. Calif. Acad. Sci., 2nd series, vol. 5, pp. 273-365, 1895. 



