234 University of California Publications in Geology [Vol. 7 



subsidence quickly immersed in comparatively deep water — or 

 at least far enough from the main shore to receive no earthy 

 deposits. 85 Or certain elevated tracts might have been protected 

 in places from direct wave action by lying behind some head- 

 land or within some embayment. In such inlets there may have 

 been river-born detritus with deposits largely of very fine grain 

 (later becoming shale). Or there may have been no main streams 

 emptying into some of them, and only a meager supply of terrig- 

 enous detritus. Some areas may represent Dixon's lagoon type 88 

 of sedimentation. But whatever their origin, it should be noted 

 that they are the exceptional type, and even some areas that 

 have been so reported have proved on more careful examination 

 to show at least a thin sandy base to the series. 



Effect of Geographical Conditions. — Many phenomena of dis- 

 tribution and lithologic character indicate that the . series was 

 deposited over much of the province on an uneven topography, 

 with many hills and mountainous ridges protruding above the 

 water level and some of these remained above sea-level during 

 the period of greatest depression (or greatest extent of water 

 surface) and gave an archipelagic character to the epicontinental 

 sea. These land masses did not in general carry large streams 

 capable of contributing terrigenous sediments to a considerable 

 area beyond the immediate shore line, and therefore the total 

 thickness of the series and the relative proportions of terrigenous 

 and non-terrigenous material varied rapidly in some localities 

 from point to point. 



The greatest thicknesses of siliceous earths are found near 

 the central and seaward portion of the depositional areas out- 

 lined : in the Santa Maria-San Luis-Monterey region along the 

 coast, where they are said to reach 6000-8000 feet in thickness, 

 and from here directly toward the interior across the present 

 ranges into the hills bordering the great valley on the west in 

 the vicinity of MeKittrick and the Temblor range. This forms 

 an area that projects from the coast into the interior while 



85 Some of the areas which at first glance seem to have this relation- 

 ship have been given this appearance by post-Monterey faulting, the 

 siliceous shales being so displaced as to outcrop against the pre-Monterey 

 formation. 



^•Quar. Jour. Geol. Soc, vol. 67, p. 511 et seq. (1911). 



