68 



University of California Publications. 



[Geology 



coarser gravels. They show no fossil beds, and seem to be of the 

 nature of a river deposit. They lie conformably above the Sono- 

 ma Tuff and are dipping toward to the valley to the west. At 

 Freestone, conformably above the Sonoma Tuff and lying almost 

 horizontally, is a yellow sandstone of almost identical character 

 to that at Wilson's Ranch. It extends northward toward Tren- 

 ton and dips gently toward the northeast. No fossils were found 

 in it. In Petalnma is a small exposure which may be a remnant 

 of these beds. 



Franciscan jooo ft. 6000 ft 



Fig. 1. 



Section from the Russian River to Windsor, across the Santa 

 i?osa Valley, showing the stratigraphic relations of the Merced, 

 Sonoma Tuff, Bed Gravels, and Franciscan, and the position 

 of the Merced shell beds at Wilson's Ranch. 



The only good shell beds observed in this formation are 

 located at Wilson's Ranch, on the east bank of Russian River 

 some three miles southwest of Windsor and one mile north of 

 Trenton. They occur about 1,000 feet above the Sonoma Tuff. 

 The writer made several trips to this locality and collected a 

 number of fossils, which he was enabled to identify as follows : 



Tapes staleyi Gabb. 



Macoma nasuta Con. 



Standella nasuta ( ?) Gld. 



Schizothoerus Nuttali Con. 



Natica clausa Brod. and Sby. 



Natica lewisii Gld. 



Olivella biplicata Sby. 



Chrysodomus tabulatus Baird. 



Area trilineata Con. 



Nassa near calif orniana Con. 



Cardium eorbis Martyn. 



Crepidula grandis ( f) Midd. 



Purpura saxicola Val. 



