1916] 



Dicker son: Tejon Eocene of California 



413 



the Tertiary Calaveras River, which here debouches into the plains 

 but which is not visible in this vicinity ' '. Evidently the deep gravels 

 should be correlated with the basal sands and gravels of the lone ; 

 the rhyolite and interrhy otitic channel has an equivalent in the last 

 three members of the lone ; the andesite of the Sierras is coextensive 

 with the andesitic tuft's and Neocene shore gravels of the valley border. 



The third member of the lone, the red sandstone, contains casts 

 of Venericardia planicosta merriami and other Eocene shells which 

 are characteristic of the Siphonalia sutterensis zone of the Tejon 

 group ; hence the lower portion of the rhyolitic beds and the inter- 

 rhy olitic channel, the correlatives of second and third members of 

 the lone formation, are Eocene in age. No fossils have yet been found 

 in the fourth member of the lone, the "clay rock" of Turner. This 

 correlative of the uppermost portion of the rhyolite of the Sierra 

 Nevada is apparently conformable with the third, the red sandstone 

 member. On the basis of stratigraphy, the fourth member is prob- 

 ably Eocene in age, in part at least. If there is any genetic connec- 

 tion between the white shale of the Coalinga District and the rhyolite 

 of the Sierra Nevada, then an Oligocene age is suggested for the 

 uppermost part and Eocene age for the lower portion. However, as 

 interesting as this possibility may be, it is a difficult one to verify 

 and its consideration is merely a suggestion for future investigation. 



Wide-spread unconformity between the andesite and the rhyolite 

 is shown in many places in the Sierra Nevada, and the same relations 

 exist between their correlatives of the valley border, the Neocene 

 shore gravels and the uppermost rhyolitic member of the lone. In 

 places the andesite is coextensive with the andesitic tuffs which over- 

 lie the rhyolite of the uppermost lone ; hence the stratigraphic rela- 

 tions between the andesite of the mountains and the andesitic tuffs 

 of the valley border are entirely clear. The andesitic tuffs have 

 yielded several floras, but no fauna which is properly authenticated 

 has been reported from them. 



The floras listed by Knowlton 00 from Corral Hollow and south of 

 Mount Diablo are both from the San Pablo, an upper Miocene for- 

 mation as determined by Clark.'' 1 The age determination of the 

 andesitic tuffs will probably be made when larger floras from the 



so Knowlton, F. H., Flora of the Auriferous Gravels of California in 

 Tertiary Gravels of the Sierra Nevada of California, Professional Paper No. 

 73, TJ. S. Geological Survey, pp. 57 to 04, 1911. 



6i Clark, Bruce L., The Fauna of the San Pablo Group, Univ. Calif. Publ. 

 Bull. Dept. Geol., vol. 8, pp. 442-443, 1915. 



