18 



University of California Publications in Geology [Vol. 8 



Fort Tejon apparently does not represent nearly so much of upper 

 Eocene time as does the section south of Mount Diablo. In the section 

 south of Mount Diablo three major faunal zones have been recognized. 

 These horizons are respectively lower, middle, and upper Tejon. In 

 addition to these major zones, the Tejon group has in it well-marked 

 zonal facies due to conditions of deposition. One of these faunal 

 variations is due to development in brackish water, while the other 

 is due to development in moderately deep water on the edge of the 

 continental shelf. 



STEATIGEAPHY OF THE TEJON SOUTH OF MOUNT DIABLO 

 The Tejon group south of Mount Diablo is a northwest-southeast 

 strip about ten miles in length. It has an unconformable relation to 

 the underlying Chico and Martinez. For a distance of six miles this 

 unconformity is marked by basal Tejon strata containing boring 

 shells which penetrate the underlying Chico or Martinez rocks. In 

 some places these borings are found in limestone of Martinez age, 

 again in Chico sandstone and Chico limestone containing fragments 

 of Inoceramus. 



Sect/ on of the Te/on 



Cave Pt 



Fig. 1 



The Tejon group south of Mount Diablo is a northwest-southeast 

 difference in dip and strike was found between the two in this field. 

 An unconformity or disconformity probably exists here. At a locality 

 in the bed of Walnut Creek about one and one-half miles southwest 

 of the town of that name, the overlying Miocene beds contain frag- 

 ments of coal and sandstone of probable Tejon age which were evi- 

 dently derived from the underlying Tejon. Walnut Creek is only 

 a short distance from the Tejon area south of Mount Diablo and 

 conditions are probably the same in both places. 



