250 0. H. Hershey — River Terraces of California. 



supposed sub-marine river cliannels that I see corroborate 

 evidence of elevation inland. Each tilting to which is due 

 the river terraces described in this paper, served only the more 

 effectually to depress the drowned valleys. Even the recent 

 drowning of the mouths of the modern rivers west of the 

 Klamath region tells the story of tilting, as the tide runs up 

 them only a few miles. 



The writer long accepted elevation as the direct cause of the 

 great Quaternary glaciatious, but that theory of late has seemed 

 very questionable. The uplifts and the glaciations should 

 connect more closely than they do. Further, the disappear- 

 ance of the glaciers should have been brought about by depres- 

 sion of the land. In the Klamath region, the glaciated val- 

 leys, as already mentioned, appear to be at present as high 

 above sea-level as they were at any time during the Glacial 

 Period ; therefore, the theory of elevation as the sole cause of 

 glaciation seems inadequate. 



Berkeley, California. 



