NEOCENE STRATIGRAPHY. 287 



has been found to extend upward to the Tertiary, it will 

 be assumed here, purely upon their evidence, that such a 

 break does exist here between the metamorphics and the 

 Pescadero series. The series has a thickness of several 

 thousand feet. 



During the next period of sedimentation there were laid 

 down the two formations known as the 



Monterey and Merced Series. — The Monterey series is 

 a considerable thickness of white, or light colored, fre- 

 quently bituminous, shale, with some sandstone, and is 

 overlain conformably by soft sandstones, shales and con- 

 glomerates or grits, the whole, known as the Merced 

 series, having locally a thickness of nearly a mile. The 

 Monterey series contains but few fossils, those being of 

 Miocene age. The Merced series is very fossiliferous, 

 at the bottom containing many Miocene forms and at the 

 top appearing to run nearly if not quite into the Pleisto- 

 cene. 



The two formations appear to grade into each other so 

 that locally sedimentation seems to have been continuous 

 from the beginning of the Monterey period at least through 

 the Pliocene. On the other hand there is evidence of 

 many minor movements during this long period, many 

 parts of the area now covered by the formations having 

 evidently been land areas during part of the time. 



These two formations were laid down unconformably 

 upon the preceding Pescadero series. 



Unconformably upon all the preceding formations there 

 are all around the edge of the Santa Cruz Mountains un- 

 consolidated deposits of Pleistocene or Recent age. 

 Locally, as just south of Mussel Rock and one or two 

 other places, these reach a thickness of over two hundred 

 feet; but generally they average from live to fifty feet 

 in thickness. An interesting feature of these deposits is 

 the part that wind-blown sands play in them, appearing 



