1916] 



Dickerson: Tejmi Eocene of California 



471 



Without any marked change in deposition and without any appar- 

 ent unconformity between the Turbinolia Zone and the Rimella 

 simplex Zone, the sediments containing the Rimella simplex fauna 

 were laid down on top of the earlier sediments in the San Francisco 

 Basin. By gradual enlargement of the San Francisco Basin through 

 sinking and the consequent transgression of the Tejon sea, the shore 

 line was extended in this basin further east, further north and further 

 south across the present site of Canada de las Uvas, the type locality 

 of the Tejon. At this time the Los Angeles Basin again became an 

 area of deposition as is shown by the Tejon sandstones of the Santa 

 Ana Mountains and of San Diego County (see figure 12). The 

 deposition during this period was probably interrupted by slight up- 

 lifts followed by slight depressions and the shore line was a decidedly 

 shifting one as is indicated by slight, local unconformities south of 

 Mount Diablo and by the alternations of estuarine and marine faunas. 



Apparently the Los Angeles Basin did not remain beneath the sea 

 during the deposition of the rocks containing the two succeeding 

 faunas, as the Rimella simplex fauna is the only one represented there. 

 The Balanophyllia zone is typically represented in the Mount Diablo 

 region, and probably occurs in the vicinity of Lower Lake as well. 

 The fauna from the top of the white sandstone member of the Tejon 

 north of Coalinga represents this zone. Apparently the present site 

 of the Tehachapi Mountains was a land-mass at this time. Land con- 

 ditions probably extended for fifty miles further north, shutting out 

 the Tejon sea from the vicinity of the type Tejon. 



The San Francisco Basin was still further lowered to receive the 

 sediments containing the Siphonalia sutterensis fauna and the ad- 

 vancing shore line of the transgressing Tejon sea moved farther and 

 farther to the eastward and the golden sands of the earlier gravel 

 period and the rhyolitic tuffs were deposited across the truncate 

 edges of the Mariposa slates and associated intrusives of the Bedrock 

 series. Far to the north between the Klamath and the Sierra Nevada 

 a great bay extended and estuarine deposits were laid down across the 

 present site of the town of Redding. Into this bay and the Tejon- 

 Pacific Ocean the rivers of the Klamath Mountains and Sierra Nevada 

 plunged rapidly, bringing with their waters the sands and gravels. 

 According to Diller, the Klamath Province was a peneplain at this 

 time and according to Lindgren the Sierra Nevada region had ad- 

 vanced in topographic development to middle or late maturity with 



