PHYSIOGRAPHIC AND GEOLOGIC DEVELOPMENT 259 



the western flanks of the granite range no corresponding sedi- 

 mentary deposits are found in this latitude. The sea thus appears 

 to have stood farther west of the Coast Range in Paleozoic times 

 than at present. 



For the later history it is necessary to assemble the various 

 Tertiary sections described on the preceding pages. First of all 

 we recognize three quite distinct types of accumulations, for which 



Coarse alluvium alternating with fine wind- 

 blown desert deposits. 

 Upper sandstone series. 



Lower sandstone series. 



Quartzites. 



Volcanic flows. 



Granite-gneiss. 

 Fig. 177 — Composite structure section at Aplao. 



we shall have to postulate three sets of conditions and possibly 

 three separate agents. The first or lowermost consists of even- 

 bedded deposits of red and gray sandstones, the former color pre- 

 dominating. The material is in general well-sorted save locally, 

 where lenses and even thin beds of conglomerate have been devel- 

 oped. There is, however, about the whole series a uniformity and 

 an orderliness in striking contrast to the coarse, cross-bedded, and 

 irregular material above the unconformity. On their northeast- 

 ern or inner margin the sandstones are notably coarser and 

 thicker, a natural result of proximity to the mountains, the source 

 of the material. The general absence of wind-blown deposits is 

 marked; these occur entirely along the eastern and northern por- 

 tions of the deposits and are recognized (1) by their peculiar 

 cross-bedding, and (2) by the fact that the cross-bedding is di- 

 rected northeastward in a direction contrary to the regional dip 

 of the series, a condition attributable to the strong sea breezes 

 that prevail every afternoon in this latitude. 



The main body of the material is such as might be deposited 

 on the wide flood plains of piedmont streams during a period of 



