244 University of California Publications. [Geology 



been to determine the extent, character, and stratigraphie posi- 

 tion of these beds in the Coast Ranges of central California. In 

 addition an attempt has been made to study the fauna and show 

 its relation to that of the Monterey and the Merced. 



This investigation was begun several years ago by Professor 

 J. C. Merriam. Important collections of fossils were made at 

 several localities and much detailed stratigraphie work was done 

 in the field. Two years ago a continuation of this investigation 

 was suggested to the writer and the present paper is the result 

 of a study of the known San Pablo outcrops of middle California 

 and of their fauna. A number of detailed sections were made 

 across the strike of the beds and collections of fossils were made 

 at intervals along the sections. From the information obtained 

 an attempt has been made to set forth the main characteristics 

 of the formation from base to top, and the variations in the 

 character of the strata at the same horizon in different localities 

 within the area studied. The study of the fauna shows the pres- 

 ence of seventy-three species. The formation as a whole is a dis- 

 tinct feature of the Tertiary of middle California. 



HISTORICAL EEVIEW. 



The formation now known as the San Pablo was first referred 

 to by T. A. Conrad 1 in 1857 in the Pacific Railroad Reports. He 

 described several fossils collected in the San Pablo Bay area and 

 considered them to be of Miocene age and to correspond to the 

 Miocene fauna of Virginia. In 1865 J. D. Whitney in his report 

 on the Geological Survey of California refers to the San Pablo 

 localities at Kirker's Pass and Corral Hollow, and on the basis 

 of the fossil leaves considered the formation to be Pliocene in 

 age. In the same volume W. M. Gabb referred 2 to the San Pablo 

 beds at Kirker's Pass. He gave a short list of its fauna and de- 

 scribed its stratigraphie relations, and on the basis of its large 

 percentage of living species called it Pliocene. He stated that 

 it lies conformably upon the Miocene and is overlain conformably 

 by ashes and tuff. In volume 2, Palaeontology of California 



i Pacific E. E. Eeports, vol. 6, p. 70. 



- Geol. Surv. of Calif. Geology, vol. I, p. 31. 



