1916] 



Diekerson: Tejon Eocene of California 



373 



The Tejon on the south side of Mount Diablo is on the average 

 about 2600 feet thick and it has a general strike of N 60° W. In 

 the northwestern portion of the area under discussion, it has a 

 dip of 60° south in Pine Canon. Going southward along the strike, 

 these strata become vertical and finally overturned in the vicinity 

 of Cave Point, where they have a dip of 70° to 85° N. Two to three 

 miles southeast of Cave Point the Tejon is pinched out by a 

 great overthrust fault. Very extensive collections were made 

 throughout the entire extent of the Tejon. A particularly good 

 section for study was found in an unfaulted area lying between 

 Cave Point and Oyster Point. At least three faunal zones were 

 recognized in this area. 



FAUNA 



TURBINOLIA ZOXE 



A very large fauna Avas obtained from the basal beds. These 

 strata, consisting of four to five feet of irregularly bedded lime- 

 stone, conglomerate, and hard calcareous sandstone, and about two 

 feet of thin-bedded sandstone, lie unconformably upon the Chico 

 limestone and sandstone. Numerous pholad borings mark this 

 ancient shoreline of the Tejon sea. This same horizon also occurs 

 in the Pacheco syncline near Muir Station, Concord Quadrangle. 

 The last three localities listed below are from this vicinity. A list 

 of species from the Turbinolia Zone is given below : 



Nummuloid(f), sp., Thamnasteria sinuata Nomland, Turbinolia 

 pusillanima Nomland, Yoldia(f), sp., Thracia harquinezensis Weaver, 

 Tellina martinezensis Weaver, Paphia conradi, n. sp., Pholadidea, sp., 

 Metula harrisi, n. sp., Natica gesteri, n. sp., Nyctilochus eocenicus 

 (Weaver), Strepsidura howardi, n. sp., and Perissolax gabbi. n. sp., 

 appear to be restricted to this zone. Modiolus merriami (Weaver), 

 Solen stantoni Weaver, and Turritella conica Weaver are forms which 

 occur in the underlying Martinez but are not found in the Tejon of 

 the type locality. Dosinia elevata Gabb and Lucina gyrata (Gabb), 

 although not characteristic, are very common at this horizon. Led a, 

 gabbi Conrad makes up a large bulk of the thin-bedded sandstones 

 of this member. The rarity of Turritella uvamna, Conrad and the 

 absence of Rimella simplex Gabb are particularly noteworthy, as 



