Vol. IV] ANDERSON AND MARTIN— NEOCENE RECORD 37 



Neocene Rocks. — The oldest sedimentary rocks with which 

 we are directly concerned are of lower Miocene age and belong 

 to the Temblor group. The Temblor sediments range in 

 character from conglomerates and coarse granitic sandstone 

 at the base to finer sandstone, sandy clays, and argillaceous 

 shale at the top. The coarseness and composition of the rocks 

 and their hardness vary considerably, and there are few sec- 

 tions that are alike in sequence and character, although coarse 

 materials predominate at the bottom and finer materials at the 

 top, as a rule, and in this respect there is some uniformity. 



The rocks of the Temblor group occupy a long narrow strip 

 of varying width extending from the Salinas Valley, near 

 Atascadero, southeast to San Juan River and beyond. In 

 a few localities stream gravels and alluvium have completely 

 covered these beds so that they can not be traced continuously 

 across the district. One notable occurrence of this alluvium 

 may be seen between Cammattii Canyon and Navajoa Creek in 

 the northern part of T. 29 S., R. 16 E. The general strike of 

 the beds is N. 60° to 70° W. in the western part of the area 

 and about N. 40° to 50° W. in the eastern part of the district 

 near La Panza. They dip away from the granite toward the 

 northeast at angles which rarely exceed 30°. 



The lov/est beds of the group rest directly upon the eroded 

 surface of the granite, there being no intervening marine sedi- 

 ments such as are found elsewhere in the Coast Ranges of 

 California. Between the marine sandstone and the unaltered 

 granite there is a zone of weathered granite consisting of 

 numerous large boulders and angular fragments which do 

 not show the rounded surfaces so characteristic of water worn 

 materials. The degree of weathering shows every gradation 

 from slightly weathered granite to coarse arkose sandstone, 

 so that in some localities it is difficult to draw a sharp line of 

 demarkation. In the N. W. V^ of Section 26, and the N. E. 

 Ya: of Section 27, T. 28 S., R. 14 E., there are several good 

 exposures of this zone of weathered granite. These exposures 

 occur in the canyon walls and the creek banks near the county 

 road. Above this zone of weathered granite there are several 

 hundred feet of coarse granitic sandstone. The degree of com- 

 pactness varies considerably, many well-cemented layers being 

 interstratified with softer materials. Overlying the coarse 



