240 tropessor james geikie, ll.d., d.c.l., f.e.s., etc., on 



boulder-clays in various parts of our islands, and the similar 

 occurrence of marine and brackish-water shells in and under- 

 neath the " diluvium " of North Germany, etc., proves clearly 

 enough that just before the coming-on of glacial conditions 

 neither Britain nor the present maritime lands of the con- 

 tinent were far removed from the sea. It is true that the buried 

 river-channels of Scotland indicate a preglacial elevation of 

 some 200 or 300 feet above the existing sea-level, but it is 

 quite certain that the Minch, St. George's Channel, the 

 Irish Sea, the North Sea, and the Baltic, were all in existence 

 at the commencement of the glacial period. And we are led 

 to similar conclusions with regard to the geographical condi- 

 tions of North America at that time, from the occurrence of 

 marine shells in the boulder-clays of Canada and New 

 England. 



Thus there appears to be no evidence either direct or 

 indirect in favour of the view that glacial conditions were 

 superinduced by great continental elevation. But it may be 

 argued that even although no evidence can be cited in proof 

 of such elevation, still, if the glacial phenomena can be well 

 explained by its means, we may be justified in admitting it 

 as a working hypothesis. Movements of elevation and de- 

 pression have frequently taken place — the Pleistocene 

 marine deposits themselves testify to oscillations of the sea- 

 level — and there can be no objection, therefore, to such pos- 

 tulations as are made by the hypothesis under review. All 

 this is readily granted, but I deny that the conditions that 

 obtained in Pleistocene times can be accounted for by eleva- 

 tion and depression. Let us see how the desiderated eleva- 

 tion of northern lands would work. Were North-Western 

 Europe and the corresponding latitudes of North America to 

 be upheaved for 3,000 feet, and a land-passage to obtain 

 between the two continents by way of the Faaroe Islands, 

 Iceland, and Greenland, how would the climate be affected ? 

 It is obvious enough that under such changed conditions the 

 elevated lands in higher latitudes might well be subjected to 

 more or less extensive glaciation. Norway would become 

 uninhabitable and glaciers might well appear in the mountain- 

 valleys of Scotland. Butitmay be doubted whether the climate 

 of France and Spain, or the corresponding latitudes of North 

 America would be much affected. For were a land-passage 

 to appear between Britain and Greenland no Arctic current 

 would flow into the North Atlantic, while no portion of the 

 Gulf-stream would be lost in Arctic seas. The North Atlantic 



