6 University of California Publications in Geology [Vol.12 



STRATIGRAPHY 

 GENERAL FEATURES 



The formations exposed in the area are of sedimentary origin, 

 with the exception of a few igneous rocl<s in the Franciscan series 

 (Jurassic?). These rocks are the oldest in the district and are made 

 up chiefly of sandstones, shales, and radiolarian cherts similar to 

 those of the type section around San Francisco Bay. The Cretaceous 

 is represented by conglomerates, sandstones, and shales which are in 

 part of Knoxville (Lower Cretaceous) and Chico (Upper Cretaceous) 

 age. The Tertiary comprises three groups of rocks. The Eocene is 

 represented by the Meganos and Tejon formations (Middle and Upper 

 Eocene), no Martinez (Lower Eocene) being recognized. Uncon- 

 formably above the Tejon is the Sespe formation (Oligocene?) which 

 is probably of continental origin. This is followed by the Monterey 

 group (Miocene) in conformable sequence. The Fernando (Pliocene) 

 formation overlies these with a marked unconformity; this is in the 

 main of marine origin, but towards the upper part passes into fresh 

 water clays, sandstones, and conglomerates which may be equivalent 

 to the Paso Robles formation to the north. Pleistocene terrace deposits 

 are common along the Santa Ynez River, and remnants of them are 

 present as high as 1500 feet above the level of the river 



jurassic(?) system 



Franciscan Series 



The Franciscan series as exposed in the northern part of the Santa 

 Ynez district occurs in two areas, one considerably larger than the 

 other. The larger area extends along the southern slope of Little 

 Pine j\Iountain and is a continuation of the Franciscan series mapped 

 in the Santa ]\Iaria oil district.^ Towards the east, near the big bend 

 in the river, it becomes only a narrow strip marking the course of a 

 fault. 



1 Arnold, Ralph, Geology and oil resources of the Santa Maria district, Cali- 

 fornia, U. S. Geol. Surv. Bull. 322, 1907. 



