1912] Martin: Type Locality of Monterey Series in California 149 



Marcia oregonensis Conrad has not been found below lower 

 Miocene in this part of the coast ranges. It is most commonly 

 found above middle Miocene. Ficus kernianum Cooper was first 

 obtained from the lower Miocene of Kern River, Kern County, 

 California. It is believed to be characteristic of middle and 

 lower Miocene. The number of species comprising the fauna of 

 the Monterey is very limited; some of them, however, are con- 

 fined to a small vertical range and serve definitely to place the 

 beds within middle and lower Miocene. 



CORRELATION WITH THE MONTEREY MIOCENE OF 

 CONTRA COSTA COUNTY 



Miocene strata, supposed to be of the same age as the Mon- 

 terey, occur along the east shore of San Pablo Bay and in the 

 vicinity of Mount Diablo. One of the largest and most important 

 of these areas extends from San Pablo Bay southeast toward the 

 town of Walnut Creek. The strata have been folded into a broad 

 syncline whose axis strikes approximately N. 50° W. Along the 

 northern border of the syncline, near Selby Smelter, the beds lie 

 unconformably upon a dark shale which is considered to be of 

 lower Eocene age. Along their southern boundary they rest in 

 part, presumably, upon the Tejon formation, of upper Eocene 

 age. The San Pablo beds lie upon this series. At Selby the sec- 

 tion is composed of brownish-gray sandstone and rusty, yellowish 

 shale. The strata are inclined toward the southwest at a high 

 angle. In a few localities they are standing almost vertical. The 

 thickness is between three and four thousand feet. The south 

 side of the syncline is composed of both sandstone and shale. The 

 shale in the lower portion is composed of a white, well-stratified 

 rock which resembles very closely the shale at Monterey. The 

 shale occurring in the upper part of the section is more argil- 

 laceous and of a rusty-yellow color. The sandstone is principally 

 a gray, medium-grained rock. The dip of the strata is toward 

 the northeast at angles varying between thirty and forty degrees. 

 The total thickness is very close to five thousand five hundred feet. 



The correlation of the Miocene on San Pablo Bay known as 

 the Miocene of Contra Costa County with the type section of 



