164 CALIFORNIA ACADEMY OF SCIENCES [Proc. 30 Ser. 



of the Miocene. The brown color of these shales is proba- 

 bly due in large part to bituminous matter contained therein ; 

 but this will be referred to later. 



Both above and below the Kreyenhagen Shales are sands, 

 which at some points are sufficiently consolidated to form 

 hard rock. 



South of the Kreyenhagen wells there is a great thickness 

 of sandstone exposed along the canyon of Canoes Creek with 

 a thin basal bed of conglomerate resting upon the Lower 

 Cretaceous shales. The strata stand almost vertical with a 

 dip of 75° or 80'^ toward the north and an east-west strike. 



At least the upper four hundred feet of this sandstone, 

 and possibly all of it, is to be referred to the Eocene. A 

 few miles to the east, at Tar Springs, the lower portion of 

 the Eocene consists of about four hundred feet of concre- 

 tionary sandstones which are very fossiliferous. The con- 

 cretions occupy a place immediately below the Kreyenhagen 

 Shales, while lower down are thin beds of sandstone, and at 

 the base a bed of pebbly conglomerate six to ten feet in 

 thickness, resting upon strata of Cretaceous age. The Avenal 

 wells at Tar Springs are drilled to penetrate these sands. 

 These basal and concretionary sandstones can be followed 

 for several miles both east and west from Kreyenhagen's, 

 being exposed at Tar Springs on the east and at the Sulphur 

 Springs on the Zapata Chino Creek to the west. On account 

 of their development at the Avenal wells (Tar Springs) they 

 may be conveniently termed the Avenal Sandstones. 



The species of invertebrate fossils obtained from these 

 sandstones include the following: 



Cardita horni Gabb ( C. planicosta Architectonica horni Gabb 



Conrad) Ancellaria elongata Gabb 



Cardiiitn cooperi Gabb Dentalium cooperi Gabb 



Cardita sp. Fusus martinez Gabb 



Corbula paratis Gabb Fusus diaboli Gabb 



Solen paratellus Gabb Turritetta uvasana Gabb 



Meretrix horni Gabb Turritetta pacheco'ensis Stanton 



Amauropsis atveata Gabb Neverita gtobosa Gabb 



A stratigraphic section of the rocks at Tar Springs is 

 shown in the accompanying sketch (PI. xxxiv, fig. i). 



