PHYSICAL AND CLIMATAL CONDITIONS. 99 



covered, and from the scarcity of the icebergs on the 

 eastern compared with the western coast of that land, it 

 may be concluded that the general slope of the surface is 

 to the south-west, and in the exact direction of the glacial 

 markings and of what is known to have been the- course 

 of transported boulders in north-eastern America. 



" Moreover, if we bear in mind the ascertained fact that 

 during the glacial period the glaciers moving from the 

 heights of Greenland toward the sea could not have 

 formed detached icebergs, as now, but must have for the 

 time blocked up all avenues except the one of easiest 

 escape for the immense accumulation of ice, we may 

 reasonably assume that this avenue was south-westward 

 directly across British America and the north-eastern 

 parts of the United States." 



Probably few even of the more extreme glacialists will 

 think this explanation at all feasible, and Torell himself, 

 if acquainted with the additional facts ascertained in 

 recent years, would probably see that it is unnecessary to 

 go so far for the sources of ice. This will appear clearly 

 when we consider the following leading facts already 

 referred to in preceding pages : 



1. There is no such universal glaciation of higher 

 summits as that supposed. On these summits glaciated 

 surfaces are rare and not strongly marked, and are most 

 distinctly seen in the valleys and plains, to which also 

 the boulder formation and till are for the most part 

 limited. 



2. There are the best reasons to believe that in the 

 Pleistocene period the Laurentian highlands were propor- 

 tionally more elevated than at present. 



3. We now know with certainty that the prevalent 

 drift on the north side of the Laurentian axis, as well as 



