38 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



sandstone are several hundred feet of softer, medium grained 

 sandstone. Near the middle of the section there is 100 feet or 

 more of coarse granitic, well cemented sandstone containing a 

 few fossils, among which Scutella norrisi Pack, is the most 

 characteristic. Above this coarse fossiliferous sandstone there 

 are several hundred feet of medium to fine grained sandstone 

 and sandy clays. Near the top of the section, immediately 

 beneath the overlying shales, the beds are essentially soft sandy 

 clays with a few thin seams of tawny colored limestones. This 

 section may be considered representative of the Temblor in 

 the western part of its area. 



East of the San Juan River in the N. E. Yi of T. 30 S., R. 

 17 E., a different sequence of sediments is exposed. Here a 

 rugged and conspicuous mountain mass lies between San Juan 

 River and the western border of the Carrizo plain. When 

 seen from a distance this prominent ridge appears much like 

 the granitic hills west of the San Juan River, and might easily 

 be mistaken for such. On closer observation, however, it is 

 found to consist of massive thick-bedded gray sandstone, 

 usually coarse grained and conglomeratic, but having inter- 

 spersed through it thin beds or layers of clay shale. This 

 massive sandstone, when compared with the beds a few miles 

 to the northwest, could easily be mistaken for this older forma- 

 tion. The finding of well preserved Temblor fossils near the 

 base, however, has shown it to be only a special development 

 of the Temblor beds. Near the top of this section the sedi- 

 ments become soft, fine grained, sandy clays, that grade into 

 clay shales of the character common in the Monterey, but as a 

 good fauna of Temblor species is found in the beds overlying 

 it there can be no mistake that it is also to be included in the 

 Temblor. 



The Temblor group 'of this section can be separated into 

 three distinct lithological divisions. The lowest member is that 

 already described. The next division consists of sandy clay 

 shales and fine grained gray or brownish sandstone with which 

 are interstratified numerous thin layers and lenses of limestone, 

 some of them sparingly fossiliferous. The sandy gray ^shales 

 resemble lithologically some of the strata of the overlying 

 Monterey. The third member of the group is a brownish or 

 gray, arkosic sandstone of medium or coarse texture several 



