THE SERPENTINE INTRUSION AND ITS EFFECT. 99 



In places the disturbance could not have been felt to any extent, as in 

 Tehama county, where the relations of the Shasta-Chico series have been 

 studied so carefully by ^[r Diller. In that region along the west side of 

 the Sacramento valley Avhere the Cretaceous is so enormously thick the 

 Chico is found several miles from the line of intrusion of the serpentine 

 in the Lower Cretaceous and older rocks, and the disturbance is not 

 noticeable at that distance. Mr Diller even remarks the greater amount 

 of disturbance exhibited by the Knoxville and the lack of it in the Chico, 

 but accounts for it by the fact that the Upper Cretaceous does not at 

 present appear superimposed on the Lower, but at a considerable distance, 

 where the axial movements were not felt.* An upheaval accompanjdng 

 the serj)entine might account for the greater amount of sandstone in the 

 Chico, especially toward the south. 



Tertiary of the Coast Ranges. 



EOCENE. 



So little is yet known of the detailed geology of much of the southern 

 Coast ranges that the relation of the Eocene to the Chico cannot be stated 

 with certainty. Fossils from both upper and lower divisions of the series 

 have been found in different portions of Ventura and Santa Barbara 

 counties in an apparentl}^ conformable series of rocks, but there is no 

 blending of the faunas. The extent and character of the series has been 

 already described. 



MIOCENE. 



The most extensive of all the formations in the southern Coast region 

 is the Miocene. Not only does it form the greater portion of the vallej^s, 

 but in many instances isolated patches are found capping some of the 

 higliest ranges. At the close of the Miocene and before denudation began, 

 strata of this age formed an almost universal covering, gradually decreas- 

 ing in importance toward the north. It is this fact which led the earlier 

 geologists to claim a Miocene age for the Coast ranges. It seems proba])le 

 that after the beginning of the Miocene and as deposition went on a sul)- 

 sidence took place, for the basal portion wherever exposed shows a 

 loose granitic sand rock, characterized in many [)laces b}^ the gigantic 

 oyster, Ostrea titan. 



The nonconformity of the Miocene on the Chico-Tejon is one of tlie 

 most striking facts to l)e o])served, notwitlistanding tlie existence in geo- 

 logic hterature of many references to the conformit}' of these two forma- 

 tions. The unconformity was noted in tlie liigli ranges in northern 



* Bull. Geol. Soc. Am., vol 4, p. 222. 



