Fairbanks.] 



Geology of Point Sal. 



5 



bituminous shales, and the lower, the gypsiferous clays. Below 

 the clays are sandstone, shales, and conglomerates resting on the 

 gabbro and serpentine. 



The bituminous shales form the most of the higher portions of 

 the ridge. They also appear on the coast in the northeast corner 

 of the map, and in the southern part constituting the coast line 

 south of the serpentine. In the two latter occurrences they are 

 richly impregnated with bituminous matter. The strata of volcanic 

 ash appear in the lower Miocene beds. There are three distinct 

 horizons, the lowest resting on the gabbro. 



The Knoxville is represented by two areas in the valley of Corra- 

 litos Creek. The upper one is much the more extensive, forming 

 almost the whole of the head of the valley. These are the first rec- 

 ognized beds of lower Cretaceous age in Santa Barbara County, 

 and the most southern point at which the genus Aucella has been 

 discovered in California. 



The eruptive rocks, though presenting great variations, are, with 

 the exception of some unimportant facies, very basic. They range 

 in age from a period probably antedating the Knoxville to post- 

 Miocene. The youngest eruptive body has a character very similar 

 to the analcite diabase, previously described by the author, from San 

 Luis Obispo County, California.* Carefully conducted investigations 

 upon the material from Point Sal have, it seems to the author, 

 conclusively demonstrated that this eruptive should be classed with 

 the group of rocks known as the teschenites, and that this group, 

 although its individuality is in dispute among European petrog- 

 raphers, has a real existence as a distinct type. The different oc- 

 currences of this rock at Point Sal all possess a diabasic structure, 

 appearing in the form of dikes in the Miocene. 



The eruptive which seems to be the next in age is that of which 

 the gabbro and peridotite are differentiated products. It extends 

 easterly from Point Lospie for three miles in the form of a long, 

 narrow dike. For two miles there are clean-cut exposures in the 

 ocean cliffs, and then it passes inland, terminating about a mile from 

 the sea, in a rounded hill rising to a hight of 700 feet. The 



*Bull. Dept. Geol., Univ. Cal., pp. 273-300. 



