1916] Martin: Pliocene of Middle and Northern California 233 



In all of the localities visited by the writer, these beds appeared to 

 overlie conformably a formation which is closely related, faunally, 

 to the Etchegoin of the Coalinga district, but which was called 

 San Pablo by Jones. In reviewing the literature, on a previous 

 page, it was pointed out that an unconformity had been reported 

 by Jones between the Merced and this underlying San Pablo. 

 The most careful observations made by the writer have not given 

 us any evidence of a lithologic change between the beds referred to 

 the San Pablo and the beds referred to the Merced, nor was any 

 evidence of a stratigraphic break seen. The strata are composed of 

 gray and brownish-gray, medium-grained sandstones with some clays 

 and occasional seams of gravel. 



The fauna from the upper horizon contains a number of forms 

 common to the Etchegoin as well as to the Purisima and Merced 

 formations. The percentage of living forms, however, is as great 

 as in the Merced at Seven Mile Beach, and ten per cent greater 

 than in the Purisima south of Half moon Bay. We are justified 

 therefore, in correlating these beds with the Merced at the type 

 locality. 



The following species have been collected from the Merced of 

 the Sargent Oil Field: 



Pelecypoda Spisula falcata Gould 



Acila castrensis Hinds Spisula voyi Gabb 



Area canalis Conrad Semele rubropicta Dall 



Area trilineata Conrad Transennella californica Arnold 



Cardium meekianum Gabb Gasteropoda 

 Cryptomya ovalis Conrad Astyris richtbofeni Gabb 



Cryptomya quadrata Arnold Bittium asperum Gabb 



Dosinia ponderosa Gray Calyptraea filosa Gabb 



Macoma nasuta Conrad Cancellaria tritonidea Gabb 



Mactra coalingensis Arnold Drillia mercedensis Martin 



Marcia oregonensis Conrad Littorina scutulata Gould 



Modiolus rectus Conrad Neverita, sp. 



Mytilus coalingensis Arnold Nassa moraniana Martin 



Pandora (Clidophora) punctata Nassa mendica Gould 



Conrad Natica clausa Brod. & Sby. 



Panope generosa Gould Neverita recluziana Petit 



Paphia staleyi Gabb Olivella biplicata Sby. 



Paphia staminea Conrad Olivella pedroana Conrad 



Paphia tenerrima Carpenter Thais canaliculata Duel. 



Schizothaerus nuttalli Conrad Thais lamellosa Gmelin 



Schizothaerus pajaroanus Conrad Thais saxicola Valenciennes 

 Siliqua nuttalli Conrad Cirripedia 

 Solen sicarius Gould Balanus, sp. 



Spisula albaria Conrad 



MERCED OF THE SANTA ROSA VALLEY 

 The general stratigraphic, lithologic, and fauna! relations of 

 the Merced of the Santa Rosa Valley have been outlined in review- 



