74 



University of California Publications. 



[Geology 



CORRELATION OF THE NEOCENE STRATA. 



It has been thought advisable to discuss in some detail the 

 correlation of the various strata included in this paper between 

 Monterey and Pleistocene. 



Stated in tabular form and in descending order, the writer 

 believes the Neocene of this territory to be made up as follows : 



/ 



St. Helena Ehyolite. 



Wilson Ranch 

 Beds 



West of Santa Eosa 

 Valley : Sandstones and 

 a small proportion of 

 shales and fine volcanic 

 conglomerate, marine 

 fauna, Area trilineata, 

 etc. 



East of Santa RosaValley : 

 Sandstones, shales and a 



, large proportion of coarse 

 volcanic conglomerate. No 

 fossils. Coarseness of 



' gravel and close bedding 

 indicating fluviatile 

 origin. 



Sonoma Tuff 



West of Santa Rosa 

 Valley: Interbedded 

 with rather coarse vol- 

 canic conglomerate and 

 carrying casts of ma- 

 rine shells. 



East side Santa Rosa 

 Valley: Interbedded with 

 heavy volcanic gravel and 

 fluviatile in origin. 

 East of Mark West Creek 

 Basin : Interbedded with 

 heavy volcanic agglomer- 

 ates and largely of aeolian 

 deposition. 



Mark West Andesite. 



UNCONFORMITY. 



Orindan (?) 



Sedimentables of Peta- 

 luma Creek and Lig- 

 nitic Beds of Lawlor's 

 Ranch and Mark West 

 Creek. 



Sandstones, shales and 

 non-volcanic conglomer- 

 ates. Fresh-ivater fauna. 

 Neohrpparion, etc., and 

 Cyrena calif ornica. 



San Pablo (?) 



San Pablo 



( Pre-Voleanic 

 1 Freestone 

 ) Pleasant 

 v Valleys. 



Beds of 

 Trenton, 

 and Capay 



f Blue Sandstone (tuff) 

 \ of Carneros Creek. 



Sandstones, shales, and 

 non-volcanic conglomer- 

 ates. Marine fauna ; 

 dementia su bdiap liana. 

 Pccten caurimis, etc. 



When we try to correlate the different members above tabu- 

 lated with well known formations in ether localities we can at 

 once refer the blue sandstone of Carneros Creek to the typical 

 San Pablo of Kirker's Pass and the San Pablo Bay sections. 



