1917] Nomland: The Etchegoin Pliocene of Middle California 223 



Total number of species reported from the upper Pliocene near Sargent ... . 45 

 Number of species common to the Etchegoin and the upper Pliocene beds 



near Sargent 26 



Total number of species reported from the Purisima 59 



Number of species common to the Etchegoin and Purisima 32 



Total number of species reported from the lower Merced 41 



Number of species common to the Etchegoin and lower Merced 25 



Age and Correlation op the Etchegoin 

 histoey of coeeelation 



The name Etchegoin Beds, used by F. M. Anderson 34 in the first 

 descriptions of the formation, included only the upper Etchegoin as 

 used by the writer. These beds were thought by Anderson to be of 

 approximately the same age as the San Pablo formation, this corre- 

 lation being based chiefly on lithology. The Etchegoin Beds and the 

 San Pablo were both included in the Pliocene. The thick series of 

 strata immediately underlying the Etchegoin Beds, including the 

 Jaealitos, Santa Margarita and a portion of the Vaqueros as later 

 mapped by Ralph Arnold and Robert Anderson, were grouped by 

 P. M. Anderson as the Coalinga Beds. These beds were believed to 

 be of upper Miocene age and to be separated from the Etchegoin Beds 

 by an unconformity. 



The Jaealitos and Etchegoin formations as mapped by Arnold and 

 Anderson 35 were held to represent the middle and upper Miocene. 

 The Etchegoin was considered equivalent to a considerable part of 

 the San Pablo. The Etchegoin was also believed to be equivalent to, 

 or possibly older than, the Purisima and was thought to be earlier 

 than the Merced. 



According to Professor J. P. Smith, 38 "The lower division of the 

 upper Miocene consists of the San Pablo-Santa Margarita-Jacalitos 

 faunas, which are a unit, or nearly so . . . the Jaealitos being merely 

 the upper division of the Santa Margarita, and both together being 



3-* Anderson, F. M., A stratigraphic study in the Mount Diablo Eange of 

 California, Proc. Calif. Acad. Sci., 3d ser., vol. 2, no. 1, 1905; A further study 

 in the Mount Diablo Eange of California, Proc. Calif. Acad. Sci., 4th ser., vol. 3, 

 1908. 



35 Arnold, Ealph, and Anderson, Eobert, Preliminary report on the Coalinga 

 Oil District, U. S. Geol. Surv. Bull. 357, 1908; Arnold, 'Ealph, Palaeontology of 

 the Coalinga District, Fresno and Kings counties, California, U. S. Geol. Surv. 

 Bull. 396, 1909; Arnold, Ealph, and Anderson, Eobert, Geology and oil resources 

 of the Coalinga District, California, U. S. Geol. Surv. Bull. 398, 1910. 



36 Smith, J. P., Geologic range of Miocene invertebrate fossils of California, 

 Proc. Calif. Acad. Sci., 4th ser., vol. 3, pp. 161-182, 1912. 



