272 THE CANADIAN NATURALIST. [Vol. X. 



Hypothetical Glacier Origin of the Lakes. The hypothesis 

 that the lakes were excavated by glaciers will now be briefly ex- 

 amined. One cannot do better then give a summary of what 

 Prof Whitney (in Climatic Changes) says with regard to the 

 erosive power of ice. " Ice per se has no erosive power." 

 Glaciers are not frozen to their beds. Ice permeated with water 

 acts as a flexible body and can flow accordingly. In neither the 

 2;lacier regions of California nor in the shrunken i>;laciers of the 

 Alps will it be found that ice scoops out channels with vertical 

 sides as water does. 



" No change of form can be observed at the former line of ice. 

 Aside from the morainic accumulations, there is nothing to prove 

 the former existence of the glacier, except the smooth, polished 

 or rounded surfaces of the rocks, which have no more to do with 

 the general out line of the cross-section of the valley than the 

 marks of the cabinet-maker's sandpaper have to do with the 

 shape and size of the article of furniture whose face he has gone 

 over with that material." 



The most important work of a glacier is the scratching and 

 grooving of surfaces. This may however, be done by dry rub- 

 bing, and therefore isolated scratched stones or patches are no 

 evidence. The underlying rock j^urfaces may lose their sharp- 

 ness, owing to contained detritus in the ice, and become rounded. 

 The ground moraine is neither characteristic nor important. 

 There is but little detrital material beneath Alpine glaciers, and 

 this is the result of water more than ice. The only characteristics 

 of ice action are striation and polishing. All floating ice shod 

 with stones frozen in them will scratch surfaces over which they 

 rub. The only glacial lakes that are formed are those where the 

 pre-existing valleys have been closed by morainic matter, but the 

 waters will soon re-open these dams by running over them. 



Such are the deductions of the late Director of the Geological 

 Survey of California, a man who has had opportuaities for study- 

 ing the action of glaciers better than most geologists in America. 

 So far Prof. Whitney's investigations are applicable to our great 

 lakes. 



Mr. George J. Hinde, F.G.S., one of the few geologists who 

 has written from a Canadian standpoint is an uncompromising 

 glacialist. On the uncertain evidence of ice scratches in the 

 north eastern end of Lake Ontario, and also on those of others 

 in a similar direction at the western end of the lake, he asserts 



