468 University of California Publications in Geology [Vol. 9 



Diablo and in the vicinity of Coalinga register these oscillations by 

 local unconformities, which indicate a fluctuating condition of the 

 strand line, the major movements being those of subsidence. Ap- 

 parently this subsidence continued and the consequent transgression 

 of the sea caused the sediments which contain the Siphonalia sut- 

 terensis fauna to be laid down upon the western foothills of the 

 Sierra Nevada. 



The Los Angeles Basin during Eocene time appears to have 

 undergone movements quite different from those in the San Fran- 

 cisco Basin. So far as known, the Tejon sea did not extend as far 

 eastward as the Martinez sea and only the middle portion of the 

 Tejon was deposited along a strand line which extended only five to 

 ten miles east of the present coast. The Tejon fauna of San Diego 

 County represents only the middle zone, both the lowermost and 

 uppermost zones being lacking. It seems very doubtful if either was 

 ever present. Orogenic movements have not been as vigorous in 

 Southern California since the deposition of the Tejon as in Northern 

 California, since the beds at San Diego and in the Santa Ana 

 Mountains are but slightly inclined. In .brief, the movements in the 

 two basins were just opposite, the Martinez exhibiting the greater 

 subsidence in the Los Angeles Basin, the Tejon in the San Francisco 

 Basin. 



The presence of islands is suggested by Fairbank's work. A wide 

 channel probably connected the Tejon Eocene of the San Joaquin Val- 

 ley with that of the Santa Clara Valley of the south. These islands 

 were probably somewhat similar to the Channel Islands of southern 

 California. No large land-locked bays appear to have been present in 

 the southern portion of the San Francisco Basin during Tejon time, 

 as the marine faunas are not, broadly speaking, estuarine but those of 

 a more open coast. Coal seams, however, do occur locally at several 

 horizons in the Tejon with an associated estuarine fauna. They prob- 

 ably represent sedimentation at the mouths of large rivers which 

 flowed westward from the Eocene Sierra Nevada. 



The earliest sediments of the Tejon Eocene were deposited in an 

 enlarged, elongated San Francisco Basin (see figure 11). The 

 northern extent of this area of deposition is doubtful, but it probably 

 extended as far north as Mendocino County. The Turbinolia zone is 

 typically represented south of Mount Diablo and it also occurs in the 

 vicinity of Coalinga. It is probably represented in Santa Barbara 

 County at the base of the so-called Topatopa formation. 



