hershby.] The Hirer Terraces of the Orleans Basin. 



475 



proposed in the paper just cited, the Red Bluff horizon occurs 

 at the 850-foot terrace, the space between this terrace and one 

 a1 least as low as the 120-foot terrace represents the Los Angelan 

 epoch, the San Pedran horizon is due al or near the seventy- 

 foot or 120-foot terraces, and the Glacial epoch is represented 

 probably by the forty-five-foot terrace and the space between it 

 ami the seventy-foot terrace, and probably also by the latter. 



During the first few years of my residence in California the 

 river terraces did uol appear to present any interesting prob- 

 lems, but the deeper 1 delve into their history, the more fasci- 

 nating grows the study. They are important because they indi- 

 cate orogenic disturbances and changes of climate, and because 

 by means of them we will be furnished the best chronometer of 

 glacial events. It is possible that they may yield facts bearing 

 strongly on the cause of the great Quaternary glaciations. They 

 furnish the basis for the classification of Quaternary land 

 faunas. Further, the relics of early man in California may be 

 referred to the different terraces, and thus some idea gained of 

 their relative a^es. So far, in the Orleans Basin, I have failed 

 to secure authentic evidence of the presence of man until after 

 the completion of the forty-five-foot terrace. Mr. Pearch 

 reports that he mined out an Indian mortar from a depth of 

 twenty-five feet below the seventy-foot terrace level, but there 

 is no certainty that this mortar did not come from near the top 

 of the bank. 



Berkeley, California, 

 May 25, 1904. 



