166 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser, 



The Jacalitos-Etchegoin, upper Miocene or lower Pliocene, 

 in middle California, still retains Ficiis, Lyropecten, Janira, 

 and tropical types of Ostrea. The contemporary Carrizo fauna 

 of the head of the old Gulf of California is much more decidedly 

 tropical, with Clypeaster, Dolium, and Astraeidae. 



In the Fernando-Purisima epoch of the lower Pliocene 

 climatic zones are already definitely established. The faunas 

 of this age from near Cape Mendocino, (Wild cat), and Puget 

 Sound, contain Pecten caurimis, numerous giant Chrysodomus, 

 Buccinum, Volutopshis, and indicate a temperature colder than 

 the present in those latitudes. 



The Purisima of middle California contains a few of the 

 giant Chrysodomus, and other northern types, but has also 

 many southern forms, such as Dosinia, Chione elsmerensis, 

 Pecten healeyi. Cape Mendocino was then the dividing line 

 between the northern and the southern faunas, just as Pt. 

 Conception is now. 



The Fernando of southern California has Ficus, Janira, 

 Lyropecten, giant Conus and Astrodapsis, tropical forms lack- 

 ing in the Purisima, indicating a milder temperature than that 

 of the present Santa Barbara Channel. 



In the Merced epoch the Puget Sound climatic zone has 

 shifted south of Cape Mendocino, and some of the northern 

 forms range down to the San Diego formation of Los Angeles 

 and San Diego {Pecten caurinus), although the large numbers 

 of Janira and Ostrea veatchi in the San Diego indicate a 

 temperature nearly as warm as the present. 



In the upper Pliocene Santa Barbara fauna, of Santa Barbara 

 and San Pedro, the almost total extinction of southern types, 

 and the prevalence of a Puget Sound fauna, indicate a sea 

 temperature not higher than 50° F. min. Whether this 

 chilling by the oncoming Glacial Epoch was felt south of Cali- 

 fornia is not known. 



The lower Pleistocene (lower San Pedro) shows the entire 

 coast, from Alaska to San Diego, in the grip of the cold 

 northern climate, a southward shifting of the isotherms of at 

 least a thousand miles, and a general lowering of temperature 

 by about 12° F., as far south as Los Angeles. 



