THE NEOCENE STRATIGRAPHY OF THE SANTA 

 CRUZ MOUNTAINS OF CALIFORNIA. 



BY GEORGE H. ASHLEY. 



["With Plates xxii-xxv. ] 



INTRODUCTION. 



The following paper gives the results of a preliminary 

 study of the Tertiary stratigraphy of the Santa Cruz 

 Mountains, but such additional notes upon the earher and 

 later rocks are given as may be of value to subsequent 

 observers. 



The data from which the stratigraphic column herein 

 given has been worked out were obtained chiefly in the 

 cliffs along the sea coast, backed up by a reconnoissance 

 of the mountains themselves. A large number of fossils 

 were collected and determined, and a beginning was 

 made upon a detailed geological map of the mountains, 

 chart No. 3055 of the U. S. Coast and Geodetic Survey 

 being used as a foundation. ^ 



To determine how far the conditions found in the Santa 

 Cruz Mountains hold good in other parts of the Coast 

 Ranges, short excursions were made into the Mount 

 Hamilton Range, the Gavilan Range, and to a number of 

 points in Los Angeles county. 



Altogether about five months were spent in the field. 



TOPOGRAPHY AND PHYSICAL GEOGRAPHY. 



Santa Cruz Mountains This name has been given to 



the series of parallel ridges extending from the Bay of 

 Monterey northward to Point San Pedro. The ridges 

 have a strike of nearly northwest and southeast. They 

 reach their highest point in Mount Bache, 3780 feet 

 above sea-level; further to the north Black Mountain 

 reaches a height of nearly 3000 feet. Further to the 

 northwest, and south of Pilarcitos Lake and Creek, the 



2d Ser., Vol. V. ( 18 ) August 1, 1895. 



