Vol. VII] GESTER -GEOLOGY McKn TRICK DISTRICT 227 



In the Belridge, and possibly in the Lost Hills, some oil comes 

 from the Tulare, but the Etchegoin is here, also, the principal 

 oil producing formation. The Santa Margarita of these fields 

 is productive of some light oil from its more sandy members. 



In all of these West Side fields both surface exposures and 

 well records indicate distinct unconformities between the Santa 

 Margarita and Etchegoin and between the latter and the 

 Tulare, and place by far the greater part of the present oil pro- 

 duction from oil sands in the Etchegoin formation. 



