140 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



varying lithology, and the great variety of rapidly changing 

 climatic conditions under which they were laid down. 



Equal confusion has existed concerning the climatic relations 

 of the Pliocene of the West Coast, some having regarded it as 

 indicating a cold climate and others treating it as uniformly 

 warm. W. H. DalP makes a statement that the Pliocene on the 

 West Coast was warmer than the Miocene. The Pliocene of 

 San Diego was certainly warmer than the upper Miocene of 

 Oregon and Washington ; but if the Pliocene is compared with 

 the Miocene of its own latitude it will be seen, without excep- 

 tion, to have been cooler. 



There is much need of revision of the data concerning the 

 Pliocene of California, where the greater part of the work has 

 been done. The writer has therefore prepared detailed tables 

 of this region, showing the present state of our knowledge, 

 and giving the results of researches carried on in the last few 

 years. These results are not final, for this is, at present, the 

 firing line in West Coast stratigraphy. 



The Pliocene appears to have been a time of considerable 

 intermigration between Japan and western America, but all the 

 Oriental types that came over were northern forms. No species 

 characteristic of warm water came from the southern Orient 

 since lower Miocene time. 



* On climatic conditions at Cape Nome, etc. <Amer. Jour. Sci. Vol. 173, (1907), p. 457. 



