GLACIATION OF NORTH CENTRAL CANADA 149 



sons to believe that the oscillations of the land were exception- 

 ally rapid in early glacial and immediately preglacial times. 

 But it would seem probable that the drainage has always fol- 

 lowed the main valleys which still trench the surface, running 

 more or less at right angles to the mountains. 



The pre-Cambrian valley of Chesterfield Inlet, extending 

 eastward towards Hudson Strait, and westward towards Great 

 Slave Lake, and the post-Cretaceous valley of the Saskatchewan, 

 extending towards the lower valley of the lower Nelson River, 

 and many other valleys running more or less parallel to these, 

 go to prove the general correctness of this statement. 



In the opinion of the writer almost all of this country was 

 overspread by the Keewatin glacier, which centered in what is 

 now the comparatively low country west of Hudson Bay. Evi- 

 dences of its presence may be seen almost everywhere in stri- 

 ated rock surfaces, giant's kettles, widespreading sheets of 

 unstratified till, stratified inter-till deposits, moraines, eskers, and 

 transported bowlders. 



The causes of the great cold of the glacial epoch are yet 

 enshrouded in mystery, and the most that has been suggested is 

 that if such and such things had been so, if the land had been 

 higher here or lower there, ice would have accumulated in 

 northern latitudes, but as yet there is little or no proof that such 

 conditions did exist. At present it would appear to be much 

 more satisfactory to spend our energies in endeavoring to fol- 

 low up the traces left by the glaciers and lakes of the glacial 

 epoch, and to first determine the conditions that existed at one 

 time, or the order in which certain conditions existed, rather 

 than to devise elaborate theories to account for conditions that 

 may never have occurred. When the country has been thor- 

 oughly examined, and the glacial deposits, striae, etc., are well 

 known, the proximate causes of these phenomena will in all 

 probability be easily determined. 



The information with regard to the conditions of glaciation 



ada, by George M. Dawson, Trans. Roy. Soc. Can., Vol. VIII, Sec. 4, pp. 1-74. 

 Ottawa, 1890. 



