180 University of California Publications in Geology [Vol. 7 



Modelo, Puente. Sespe, Topatopa, — presumably to emphasize 

 their lack of correspondence with established formation groups, 

 or the marked dissimilarity of the conditions under which they 

 were formed. For, besides using one of the "standard" names, 

 one of the authors of the bulletin presents a "Standard Cali- 

 fornia Section" (p. 143) and makes comparisons with it. Fur- 

 thermore, in the descriptions of the formations, special attention 

 is called to the dissimilarity even between formations as close 

 together as the two sides of the Santa Clara Valley, and the 

 difficulty of correlating or even of using the same formation 

 names for the two areas is pointed out and discussed (e.g., p. 21). 



It was therefore with considerable interest that the writer 

 entered the southern field to get a better understanding of those 

 conditions which produced there a different province of depo- 

 sition from that of the country north of Santa Barbara. It 

 must be admitted that the descriptions in the bulletin of the 

 various stratigraphie members gave hints of some striking simi- 

 larities between the Santa Clara region and the central Coast 

 Range region, but in several ways the order of events and the 

 major divisions appeared to show abnormalities that required 

 explanation. 



Unfortunately opportunity was not given to make careful 

 detailed studies of contacts or sections such as are necessary for 

 an accurate understanding of the details of formational rela- 

 tionships. However, some of the more general features appeared 

 to indicate so definitely the general relationships that it is be- 

 lieved a statement of them will aid in a better understanding 

 of an important period of sedimentation. 



Previously Described Section North of Santa Clara Valley 



The most complete Tertiary section of the southern California 

 region that has been described is that found to the north of the 

 Santa Clara Valley in Ventura County, commencing with the 

 Topatopa range anticlinal axis and running southeastward to- 

 wards the valley. The following section has been prepared from 

 the descriptions in Bulletin 309, plate 1 of which may be con- 

 sulted for the areal distribution of the formations : 



