i6 



University of California. 



[Vol. a. 



sandstone that it presents the appearance of having been peppered 

 with balls. No recognizable fossils were found in any of these beds, 

 with the exception of scales and fragments of fish. 



From what is known of the geology of the Coast Ranges it 

 would appear that the basal portion of the beds embraced under 

 the designation Gypsiferous clays represents as low a horizon as has 

 yet been detected in the Miocene. 



No outcrops of the jasper beds and associated sandstone are 

 known within many miles, and the presence of numerous pebbles 

 of that series in the conglomerates on the northern side of the 

 gabbro area would suggest the possibility of the existence, during 

 a portion of the Miocene, of a land area to the south from which 

 the fragmental material could have been derived. A gradual sub- 

 sidence of this area as the period of the deposition of the upper 

 Miocene beds of Point Sal approached would account for the fact 

 that the silicious rocks of the bituminous shales on the south rest 

 directly on the serpentine. 



Gypsum Deposits. — In years past, Point Sal was the most 

 important center for gypsum mining in the state. The chute was- 

 built just south of Point Morrito, for the purpose of loading vessels. 

 The gypsum occurs in bunches and irregular veins scattered here 

 and there in the soft clays. The clays have the same character as 

 elsewhere in the Miocene of the southern Coast Ranges. They are 

 richly impregnated with calcium salts and alkalies. This fact points 

 to the existence of bodies of water shut off from the open ocean in 

 which the beds were formed. It seems quite possible that in this 

 portion of California land may have existed west of the present 

 coast line. 



Volcanic Ash. — There are three strata of a hard, light-colored 

 or greenish rock interstratified in the lower Miocene on the southern' 

 slope of the Point Sal ridge. Being so much more resistant to 

 erosion than the Gypsiferous clays, they are among the first features- 

 in the landscape which attract the attention. They are finely 

 exposed along the three canons which cut transversely through the 

 lower hills. The upper bed possesses the greatest extent, reaching 

 from a spot north of Point Morrito southeasterly about two miles,, 

 to the valley in which the dairy is situated. It marks nearly the 



