Vol. 6] Jones: The Geology of the Sargent Oil Fielel. 



69 



vary. The formation undoubtedly covered a much larger area 

 than it now does, and what is left, though complete in section, 

 is but a remnant of a once very extensive formation. 



The complete section of the San Pablo formation in this 

 region is then as follows : 



Feet. 



E. Coarse conglomeratic sandstones, fossiliferous 

 at the base, and holding much volcanic 

 material 400 



D. Fine to medium grained brown sandstone, 

 with several hard layers, extremely 

 fossiliferous 300 to 600 



B. and C. Azure blue sandstone coarse at the 



base and very fine near the top 300 to 1000 



A. Coarse conglomerates and dark colored 



sandstones 150 to 1000 



1150 to 2600 



THE SANTA MARGARITA FORMATION. 



About one mile west of the edge of the area mapped, and 

 just north of the Pajaro River, is a formation composed of white 

 sandstone which is quite friable and which breaks down into a 

 pure white quartzose sand. Fossils are plentiful in these beds but 

 no complete collection was made. There are many beds prac- 

 tically composed of specimens of Astroelapsis antiselli, the char- 

 acteristic echinoid of the Santa Margarita formation. These 

 beds have quite a wide areal distribution through Santa Cruz 

 county and in the Salinas Valley on the south 8 . The uncon- 

 formable relations between these beds and the Monterey shale 

 are well defined but nowhere have the actual relations in the 

 field between the Santa Margarita and the San Pablo been noted. 

 It seems impossible that two such dissimilar formations could 

 have been contemporaneously deposited so close together as is 

 the case in the Pajaro Valley region without some interdigitation. 

 It would appear from the text of the Santa Cruz folio that the 

 beds there mapped as Santa Margarita are the downward con- 

 formable continuation of the Purisima which passes up equally 

 conformably into the Merced. It is thus highly probable that 

 the white sandstones here referred to, and which in the folio 

 are called Santa Marguarita, are later than San Pablo of the 



8U. S. Geol. Surv., folio No. 163, 1909. 



