160 N. S. SHALER — EVIDENCES AS TO CHANGE OF SEALEVEL. 



the average the seat of a greater rainfall than that of the western shore 

 of the continent. 



It seems to me that the facts do not permit us to assign any value to 

 the absence in this part of the world of the submarine accumulations 

 which are so marked a feature along the shoreline of the North Atlantic 

 ocean. 



Turning to the matter of flooded valleys, we find the first distinct indi- 

 cation of their presence at the Golden Gate. At this point there appears 

 to have been a considerable river which has been extensivel}^ invaded 

 by the sea. 



From San Francisoo bay northward all the larger stream valleys as 

 far as Alaska show more or less flooding. The waters of Puget sound 

 appear to be those of a river-system which have been deeply borne down, 

 though the details of the topography may have been considerably afl'ected 

 by ice-action. 



In the peninsular part of the Alaskan district the flooding of the val- 

 leys does not seem to be so conspicuous as in the more southern portions 

 of the Pacific shore. It may indeed be that this part of the continent has 

 in recent times had a distinct excess of elevation as compared with the 

 other marine shores. 



RESULT OF THE OSCILLATIONS. 



In considering the ocean coastline of North America as a whole, we find 

 that the facts go to show that in the region north of Mexico the changes 

 in relative level of sea and land which have taken place in recent 

 times have resulted in a tolerably uniform gain in the height of the 

 sea. The fact must not, however, be overlooked that other evidence 

 shows that this general downward tendency has been associated with 

 many minor swayings which have occasionally carried the margin of the 

 sea to much higher levels, and in one instance, and this in very recent 

 times, has brought the continent on its eastern face to a relatively more 

 elevated state than it has at present. 



The various raised beaches, extending from North Carolina to high 

 latitudes, indicate a brief subsidence in connection with the glacial event, 

 while the submerged forests, extending from North Carolina at least as 

 far north as the gulf of Saint Lawrence, containing plants of recent spe- 

 cies, show very clearly a considerable downward movement since the 

 Glacial epoch. 



The impression left upon the mind of the observer is that, taking ac- 

 count only of the time which has elapsed since the beginning of that 

 epoch, the eastern shore of North America from the Rio Grande to 



