184 THE CANADIAN NATURALIST. [Vol. X. 



afforded by the Pleistocene deposits of Cao;id;i, and he continues 

 to regard the supposed evidence of a teniiin;il moraine of the 

 great Continental glacier as nothing but the southern limit of the 

 ice-drift of a period of submergence. In .such a period the 

 southern maririn of an ice-Ltdon sea where its floe-ice and berirs 

 grounded, or where its ice was rapidly melted by wainier w.iter, 

 and where consequently its burd<-'n of boulders and other debris 

 was deposited, would neccs.sarily present the aspect of a moraine, 

 which by the long continuance of such conditions might assume 

 gigantic dimensions. 



In the recent remarkable work on glaciers by Messrs. Shaler 

 and Davis, it is appurently maintained that in North America a 

 continental glacier extended in temperate latitudes from sea to 

 8ca, and this glacier must, in many places at least, have exceeded 

 a mile in thickness. Independently of the physical difficulties 

 attending the movement of sucli a m iss without any adequate 

 slope, diflBcultieswith which the authors endeavour to deal, though 

 not very satisfactorily, it is obvious, from the considerations above 

 stated, that the amount of snow necessary to the production of 

 such a glacier could not possibly be obt lined. With a depressioQ 

 such as we know to have existed, admitting the Arctic currents 

 along the St. Lawrence Valley, thiough gaps in the Jiaurentian. 

 watershed, and down the great plains between tiie Laurentian 

 areas and the Il<icky Mountains, we can easily understand the 

 covering of the hills of eastern Canada and New England with 

 ice and snow, and a similar covering of the mountains of the west 

 coast. The sea also in this case miirht be ice-laden and boulder- 

 bearing as far south as 40 ■, while there might still be low i.-latids 

 far to the north, on which vegetation and animals continued to 

 exist. We should thus have the conditions necessary to explain 

 all the anomalies of the glacial deposits. Even the glaciation of 

 high mountains south of the St. Lawrence Valley would then 

 become explicable by the grounding of floe-ice on the tops of 

 these mountains when reefs in the sea. The so-called moraine, 

 traceable from the great Missouri coteau in the we>t, to the 

 coasts of New Jersey, would thus become the mark of the 

 southern limit of the subsidence, or of the line along which the 

 cold currents bearing ice were abruptly cut off by warm surface 

 waters. 



Whatever difficulties may attend such a supposition, they are 

 small compared with those attendant on the belief oi'a continental 



