1914] 



DicJcerson: Faunal Zones of the Tejon Group 



21 



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

 stones of this member. The absence of Turritella uvasana Conrad is 

 particularly noteworthy, as it is one of the most characteristic forms 

 of the Tejon group. The fauna taken as a whole is a littoral one. 



Above the basal portion is about twenty-five to fifty feet of a 

 deep-water facies of this zone consisting of fine-grained, gray, fora- 

 miniferal shales, which yielded Pecten interradiatus Gabb, Schizaster 

 lecontei Merriam, Yc pericardia planicosta Lamarck, and several species 

 of foraminifers. These beds are far better developed in the south 

 limb Muir syncline, where they have yielded a much larger fauna. 



A partial list of the fauna obtained at Muir syncline from this 

 .same horizon is as follows : 



Nummuloid (?). 

 Orbitoides, sp. 



Schizaster lecontei Merriam. 

 Cardium cooperii Gabb. 

 Modiolus merriami (Weaver). 

 Tellina hornii Gabb. ' 

 Tellina martinezensis Weaver. 

 Thracia karquinezensis Weaver. 

 Solen parallelus Gabb. 

 Solen stantoni(?) Weaver. 

 Venericardia planicosta Lamarck. 



Bela cf. elathrata Gabb. 

 Fieopsis remondii Gabb. 

 Megistostoma striata Gabb. 

 Cassidaria tuberculata (Gabb). 

 Perissolax, n.sp. 

 Rimella eanalifera Gabb. 

 Spiroglyphus ( ? ) tejonensis Arnold. 

 Turris monolifera Cooper. 

 Turritella conica Weaver. 

 Tritonium eocenicum Weaver. 

 Tritonium impressum Weaver. 



Several of these species as Nummuloid ( ?) sp., Modiolus merriami, 

 and Tellina martinezensis have not been found elsewhere. So dis- 

 tinctive was this fauna that Dr. Weaver 1 classed it with the upper 

 Martinez, but the relationship of this fauna to that of the basal zone 

 described above and its stratigraphic relationships places it with the 

 Tejon. Rimella eanalifera, Venericardia planicosta var. hornii, Bela 

 elathrata, Megistostoma striata, Cassidaria tuberculata, Turris mono- 

 lifera, Spiroglyphus (?) tejonensis are typical Tejon forms. These 

 beds are decidedly glauconitic. The presence of glauconite and 

 Schizaster lecontei in abundance in these beds indicate that they were 

 deposited in moderately deep water. As in the case of the Turbinolia 

 fauna described above, Turritella uvasana does not occur at this hori- 

 zon. The writer regards this fauna as a deep-water facies of the 

 Turbinolia fauna. The importance of the depth factor in interpre- 

 tation of Martinez and Tejon faunas can scarcely be overemphasized. 



This facies is not quite so well developed south of Mount Diablo 



i Weaver, Chas E., "Contribution to the Palaeontology of Martinez Group," 

 Univ. Calif. Publ. Bull., Dept. Geo!., vol. 4, pp. 101-123, 1905. 



