410 THE CANADIAN NATURALIST. [Vol. vi. 



4,500 feet above its present height, and considering the uneven 

 nature of the intervening country this is far too little. From 

 this imaginary plateau 6000 to 7000 feet high, flowed a glacier 

 over an intervening valley at least 5000 feet deep and thence 

 over the Green and White Mountains. The glacier must con- 

 sequently have been itself at least 7000 to 8000 feet thick. 

 Farther "on nearing the St. Lawrence the lower part of its 

 mass yielded to the impulse of gravity according to the slopes of 

 this transverse valley, so that along this valley only .southwest 

 scratches were made." But the southwest scratches of the St. 

 Lawrence valley run from Labrador to the lake region and 

 beyond, and have been produced by a force acting from the 

 northeast, so that the actual fact must have been the flowing of 

 a transverse glacier under the other up the slope of the country, 

 then on the hypothesis probably greater than at present. But 

 the whole assumption of an unequal elevation of the continent, 

 80 as to give a mountain region of the required elevation is des- 

 titute of proof ; and not only so but contrary to the observed 

 facts, which indicate very equable movements of elevation and 

 depression as high at least as the terraces and raised beaches 

 extend. In short, while our continental glacialists demand a 

 glacier that shall move up the St. Lawrence valley and over the 

 Niagara escarpment into Lake Erie, they also demand tlie crea- 

 tion of a mountain north of the St. Lawrence, high enough to 

 enable a glacier to glide from it over the White Mountains. 

 These extravagant assumptions are fatal to their theory, and 

 shew that they will be driven to have recourse to floating ice 

 to explain a large part at least of the phenomena. 



Mr. J. Geikie, one of the most stubborn of land glacialists, is 

 doing a similar service to the cause of truth, in a series of articles 

 now appearing in the London Geological Magazine. He can- 

 didly admits that the " evidence which has been accumulating 

 during recent years will compel us to modify materially" the 

 views of the extreme glacialists. He further admits that the 

 Boulder-clay or till contains stratified gravel, clay and sand, with 

 marine shells. He still maintains that the Boulder -clay proper 

 is moraine matter produced on land, though there is evidence 

 that this Boulder-clay as well as the stratified beds included in 

 it, sometimes at least holds marine shells. He further seems to 

 maintain that Boulder-clay proper, being an unstratified deposit, 

 cannot be of marine origin, though this assumption is contro- 



