19161 



Dickerso'H : Tcjon Eocene of California 



417 



(1) Pre-Chico erosion. 



(2) Chico transgression. Shore line moves eastward to present ele- 

 vations of 300 feet. 



(3) Post-Chico erosion. Shore line moves west of the eastern valley 

 border. 



(4) lone (Eocene) transgression. Shore line moves eastward at least 

 to present elevations of 1000 to 1200 feet. 



(5) Post-lone erosion. Shore line moves permanently west of valley 

 border. 



(6) Deposition of interandesitic shore gravels. 



(7) Pliocene and Pleistocene erosion — Sierran period. 



(a) Deposition of "Pleistocene shore gravels" up to eleva- 

 tion of 450 feet. 



(b) Deepening of stream beds along valley border by 100 to 

 300 feet, 



( c) Deposition of lower bench gravels. 



(d) Deposition of present alluvium. 



Such in brief outline is the series of events as interpreted in accord- 

 ance with the results given above. This sequence does not apply to 

 the southern end of the valley border, as a different series of events 

 seems to have taken place in that region. 



SUMMARY 



(1) The sedimentary strata beneath the Older Basalt of Oroville 

 Table Mountain and Oroville South Table Mountain represents the 

 uppermost Tejon of California, the Siphonalia sutterensis zone. 



(2) The beds beneath the Older Basalt are strand-line deposits. 



(3) The auriferous gravels as represented by the channels ex- 

 posed at the Cherokee Mine and in Morris Ravine are stream-laid 

 deposits, the correlatives of the marine sediments exposed at Oroville 

 South Table Mountain and hence their age is Tejon Eocene. 



(4) The correlative of the so-called lone formation is represented 

 in the Marysville Buttes region by deep-water sediments of Tejon 

 age. These strata have yielded an abundant fauna which has a close 

 relationship to the littoral fauna of Oroville and other lone localities. 



(5) The lone formation is of Eocene age and is merely a facies 

 of the Tejon group. If the name is retained, it should be interpreted 

 as the uppermost or Siphonalia sutterensis zone of the Tejon group. 



(6) The lone has been repeatedly correlated with the auriferous 



