THE OCEANIC CORAL-ISLAND SUBSIDENCE. 3G7 



portions of the continent: — we cannot say western portions 

 also, since in t\\Q first place, the facts, according to Prof. J. D. 

 Whitney, do not sustain the statement ; and, in the second, the 

 great mountain ranges of the west would have been a barrier 

 to all influences from any central continental elevation, and, be- 

 sides, the slopes of these ranges, even if the Pacific border were 

 higher to the north than now, would have determined the 

 course of all western glacial movements. 



The idea that the two arms of the great Azoic V were 

 raised together, is not without some support. For the courses 

 of the two were the courses of great continental uplifts or move- 

 ments, again and again, through the successive subsequent ages ; 

 and the present outline of the continent is but the final expres- 

 sion of the great fact ; moreover, the elevations parallel to the 

 western arm of the V have been much the greatest. Even the 

 exceptional courses, such as the nearly north and south trend of 

 the Green Mountains, were marked out first in the Azoic, the 

 Azoic peninsula of northern New York with the line of the Ad- 

 irondacks being an exhibition of it. And all this uniformity 

 of movement, from the laying of the first stone in the develop- 

 ing continent to the last, has been shown by the author to be 

 directly connected with the fact that the continent has always 

 been bordered by the same two great oceanic depressions, the 

 Atlantic, and the larger Pacific, the same in trend of axis as 

 now, the North Atlantic having a northeast and southwest 

 trend, parallel with one arm of the Azoic, and the Pacific a 

 northwest and southeast parallel with the other arm of the 

 Azoic. It is therefore reasonable that, late in geological his- 

 tory, during the Glacial era, after the great mountain chains 

 of the continent had been made and raised to their full height, 

 and the surface crust thickened over all the continent, except 

 that of the Azoic nucleus, by successive beds to a thickness of 



