408 THE CANADIAN NATURALIST. [Vol. vi. 



The second leading point to which I would direct attention is 

 the relative value of land ice and water-borne ice as causes of 

 geological change in the Post-pliocene. On this subject I have 

 for the last sixteen years constantly maintained that moderate 

 view which has been that of Sir Roderick Murchison and Sir 

 Charles Lyell, that the Post-pliocene subsidence and refrigera- 

 tion produced a state of our Continent in which the lower levels 

 and at certain periods even the tops of the higher hills were 

 submerged, under water filled every season with heavy ice de- 

 rived from glaciers, and that at certain stages of submergence 

 the hilly ranges were occupied with glaciers, sending down their 

 ice to the level of the sea. I need not reiterate the arguments for 

 this view ; but may content myself with a reference to the changes 

 of opinion on the subject. The glacier theory of Agassiz and 

 others may be said to have grown till, like the imaginary glaciers 

 themselves, it overspread the earth. All northern Europe and 

 America were covered with a mer-de-glace, moving to the 

 southward and outward to the sea. This great ice-mantle 

 not only removed stones and clay to immense distances, and 

 glaciated and striated the whole surface, but it cut out great 

 lake basins and fiords, ground even the tops of the highest hills, 

 and accounted for everything otherwise difiicult in the superfi- 

 cial contour of the land. It was even transferred to Brazil, and 

 employed to excavate the valley of the Amazon. But this was 

 its last feat, and it has recently been melting away under the 

 warmth of discussion until it is now but a shadow of its former 

 self. I may mention a few of the facts which have contributed 

 to this result. It has been found that the glacial Boulder-clays 

 are in many cases marine. Cirques and other Alpine valleys, 

 once supposed to be the work of glaciers, are now known to have 

 been produced by aqueous denudation. Great lakes, like those 

 of America, supposed to be ihexplicable except by glacier erosion, 

 have been found to admit of being otherwise accounted for. The 

 transport of boulders and direction of striation have been found 

 to conflict with the theory of continental glaciation, or to require 

 too extravagant suppositions to account for them in that way. 

 Greenland, at one time supposed to be a modern example of an 

 ice-clad continent, has been found to be merely a mass of rocky 

 hills and table-lands with local glaciers. The relation of Green- 

 land to Baffin's Bay and Davis Straits, proves to be similar to 

 that which may have obtained between the Laurentide hills and 



