1919] Kcw Geology of a Part of the Santa Ynez Eivcr District 15 



strata which contain an abundance of fish scales. The shale has 

 the peculiarity of being extremely well bedded, and on weathering 

 breaks up into very thin plates. The upper portion consists mainly 

 of thin rhythmically banded cherty and calcareous beds. A gradual 

 transition from the lower phase takes place, as the cherty type is found 

 interbedded with the clay shales. The calcareous bands in the shale 

 give off a strong fetid odor when struck with a hammer. The best 

 exposures of this section are seen on Little Pine Mountain, Loma 

 Alta, east of Oso C^afion, and on the hill immediately behind the 

 ranger station on IMono Creek. At the latter locality the thickness of 

 the Salinas shale is about 600 feet. 



Pi.iocENE Series 

 Fernando Formation 



The Fernando occupies a synclinal basin on the north side of the 

 Santa Ynez River, extending from the large area in the Santa JMaria 

 district as far east as Redroek Creek. The great accumulation of 

 deposits representing 3000 feet of shales, sandstones, and conglomer- 

 ates described by Arnold^" from the Santa ]\Iaria district is partly 

 represented in the area here described. At Redroek Canon the beds 

 aggregate about 1000 feet, but become thicker to the west. 



A light gray biogenic shale lying above the Salinas shale probably 

 is the base of the Fernando, since it conforms to the later folding. 

 It closely resembles some of the Salinas shale beds but differs in that 

 it is much softer. Overlying this is a series of fossiliferous sandstones 

 which, in their lower part, are conglomeratic. The pebbles in the 

 conglomerate have been derived almost entirely from the chert of the 

 Salinas shale. Above this, a softer tan and gray sandstone contain- 

 ing Dcndrastcr ashleiji var. ijtezanus Kew (Ms.), grades up into a hard 

 gray sandstone containing this same echinoid and also Nassa califor- 

 nica Conrad. In the small syncline within the main synclinal trough, 

 beds of continental origin are found. These consist of reddish, buff 

 colored muds and sands interbedded with layers of unsorted conglom- 

 erate. Teeth and limb bones of rodents were obtained from the clays 

 and sands of these beds. Farther to the west, these deposits become 

 thicker and more extensive. Their lithologie nature, together with the 



in Arnold, Ralph, Geology and oil resources of the Santa Maria oil district, 

 Santa Barbara County, California, U. S. Geol. Surv. Bull. 322, 1907. 



