2-4 University of California Publications in Geology [Vol. 8- 



"With the exception of the new species noted in this list, practically 

 all the forms occur in the fauna of the Marysville Buttes, and the 

 most characteristic of these species, Siphonalia sutterensis, Phos {?) 

 'martini Dickerson, and Drillia ullreyana Cooper, are found at both 

 localities. Another characteristic feature of this fauna is the peculiar 

 association of the Pleurotomidae and Tritonidae. The striking differ- 

 ence between the fauna at Oroville and that of the Marysville Buttes 

 is the absence of such forms as Trochocyathus striatus (Gabb) and 

 Schizaster lecontei Merriam and of glauconite. In both of these faunas 

 two of the commonest Tejon species, Turritella uvasana and Amau- 

 ropsis alveata, are missing. The fauna of South Table Mountain 

 Eocene is merely a different facies than that of the Marysville Buttes 

 and the absence of the coral, echinoclerm, and glauconite mentioned 

 above is due to differences in bathymetric conditions. The South 

 Table Mountain Eocene was deposited under littoral conditions, while 

 that the Marysville Buttes was deposited in considerably deeper 

 water. The differences in lithology confirm this conclusion. These 

 faunas are of approximately the same age, but deposited under quite 

 different conditions. 



A surface outcrop somewhat higher than that described as locality 

 No. 2225 yielded Barbatia morsei Gabb, Meretrix Jiornii Gabb, Paphia 

 (?) sp., Placunanomia inornata Gabb, Turritella merriami Dickerson, 

 and Ostrea, sp. The presence of wood and lignite suggest that this 

 fauna was deposited in brackish water. Tbis brackish water deposit 

 gave another important facies. In general, the zonal relations cannot be 

 found by a study of this phase, as it is commonly represented by only 

 a few forms which have a great stratigraphic range. This facies is 

 characterized by the following forms : Avicula pellucida Gabb, Bar- 

 batia morsei Gabb, Placunanomia inornata Gabb, Ostrea aviculaf ormis 

 Anderson, Ostrea iclriaensis Gabb, Corbicula penultimus (Gabb), Ceri- 

 thiopsis alternata Gabb, and Potamides carbonicola Cooper. 



TRANSGRESSION OF THE TEJON SEA 

 A study of the relationship between zone 3, Mount Diablo region, 

 and the Siphonalia sutterensis zone and their geographic position 

 suggest that the uppermost strata of the Marysville Buttes and Oro- 

 ville were deposited by a transgressing sea, and that only in favored 

 places along the western borders of the Sierras have the latest Eocene 

 sediments been preserved from erosion. Lava caps such as that of 

 the Older Basalt of South Table Mountain have preserved these 



