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University of California Publications in Geology [Vol. 10 



the percentage method are of little value. The finer age determina- 

 tions will probably have to be made by comparing highly specialized 

 forms from the various horizons and by a direct comparison with 

 faunal zones, the position of which lias already been found in a section 

 of known stratigraphic sequence. 



In regard to the Pliocene beds of Florida Dr. Dall 43 states : 



In the discussion of these tables, if we adopt the old-fashioned method, it 

 appears that, throwing all doubtful species into the category of extinct forms, 

 we have from the Waccamaw beds 125 out of 180 species still living, or about 

 70 per cent; while from the Crotan beds we have 80 out of 96 species repre- 

 sented in the recent fauna, or over 83 per cent. By this method the Pliocene 

 character of the beds is obvious, according to the numerical rule. 



Also for the Miocene of Maryland the same writer 44 shows that the 

 number of Recent species ranges from 8.5 to 20 per cent. It will thus 

 be seen that the percentage of Recent species in the Etchegoin, 39+ 

 per cent, falls between these two series of figures. 



The Etchegoin of the Coalinga district rests unconformably on the 

 Santa Margarita, which, as shown by Dr. B. L. Clark, 45 is probably 

 of the same age as the upper part of the San Pablo. The percentage 

 of Recent species in the San Pablo is 23+. According to Dr. Clark, 

 this would place the San Pablo in the upper Miocene or possibly lower 

 Pliocene. 



In regard to the mammalian remains found in the Etchegoin 

 Professor J. C. Merriam 40 states: "The time-relations of the Jaca- 

 litos [lower Etchegoin] vertebrates to the faunas of the Great Basin 

 Province are not entirely clear, but the closest relationships seem to 

 be with the lower Pliocene." 



CORRELATION WITH OTHER PLIOCENE FORMATIONS 

 On comparison of the Etchegoin in the region studied by the writer 



with other Pliocene faunas of California it is found that at no other 



locality do we find a section that corresponds to the whole Etchegoin 



studied at Coalinga. 



The fauna most closely related to the lower Etchegoin is found in 



the lower Fernando near Newhall, Los Angeles County. Of the sixty 



« Dall, W. H., Tertiary mollusks of Florida, Trans. Wagner Inst. Sci., vol. 3, 

 pt. 2, p. 215, 1892. 



44 Dall, W. H., The relations of the Miocene of Maryland to that of other 

 regions and to the Recent fauna, Md. Geol. Surv., Miocene, p. 147, 1904. 



« Clark, B. L., Fauna of the San Pablo Group of Middle California. Univ. 

 Calif. Publ. Bull. Dept. Geol., vol. 8, no. 22, 1915. 



40 Merriam, J. C, Tertiary vertebrate faunas of the North Coalinga Region, 

 Trans. Am. Philos. Soc, vol. 22, pt. 3, p. 30, 1915. 



