248 PROFESSOR JAMES GEIKIE, LL.D., D.C.L., F.R.S., ETC., ON 



out of a difficulty. Having postulated an amount of eleva- 

 tion for which no evidence can be cited, but which they 

 conceive necessary for the generation of great ice-sheets 

 and glaciers, they next attribute the subsidence of the highly 

 elevated continents to the weight of those ice-masses. The 

 ice-sheets, in fact, are supposed to have brought about their 

 own destruction. Thus the responsibility for the various 

 earth-movements required by the hypothesis is partly shifted 

 from Pluto's shoulders. We first have great continental 

 uplifts induced by subterranean action ; next, the lands sink 

 down again under their load of snow and ice. Thus reduced 

 in elevation they cease to favour the accumulation of snow 

 and ice, whereupon the mers de glace melt away, and the 

 overburdened crust, relieved of its load, again rises. It seems 

 all very simple and plausible, but let us see what it involves. 

 The thickness attained by the European ice-sheet in the 

 basin of the North Sea probably did not exceed 3,500 ft. or 4,000 

 ft. ; and if we take 3,000 feet as its average thickness 

 throughout the whole area covered by it we shall certainly 

 be over the mark. Now let it be remembered that at 

 the beginning of the Ice Age Europe is supposed to have 

 stood some 3,000 feet higher than at present, and to have 

 subsequently become depressed for some 500 or 600 feet 

 below the existing sea-level. In other words, we are asked 

 to believe that an ice-sheet, not 3,000 feet thick, succeeded 

 in pressing down ihe crust of the earth to the extent of 3,500 

 or 3,(500 feet ! The North American ice-sheet was consider- 

 ably greater than ours, but even allowing it to have been 

 three times thicker, we shall yet hardly be persuaded that it 

 could possibly depress the crust for 3,000 to 5,000 feet. We 

 may safely conclude, then, that if the raised beaches and 

 marine beds of the Atlantic borders owe their origin to sub- 

 mergence caused by the weight of ice-sheets, the continents 

 could not have been so highly elevated at the advent of 

 glacial conditions. On the other hand, if we accept the 

 hypothesis of former great elevation of the land, then we 

 must infer that the subsidence indicated by the raised beaches 

 cannot have resulted from the pressure of the ice-sheets. 



There are many other objections to the earth-movement 

 hypothesis which the limits of this paper forbid me entering 

 upon. But those already indicated may suffice to show that 

 the hypothesis is not only baseless but wholly fails to explain 

 the facts, most of which, indeed, tell strongly against it. It 

 accounts neither for the wide-spread phenomena of the Ice 



