CONDITIONS OF CONTINENTAL ICE. 245 



Professor Nordenskjbld, as we have seen, found that 

 the upper surface of the icy plain of Greenland has 

 an elevation of 7000 feet, 280 miles from the coast. 

 If the Antarctic ice -sheet has an equal slope, this 

 would give 35,000 feet as the thickness of the ice at 

 the Pole. 



But to avoid all objections on the score of over- 

 estimating the thickness of the cap, let us assume that 

 a slope of an eighth of a degree, or less than one-half 

 that of the Greenland sheet, would be sufficient to 

 produce the necessary motion ; the thickness of the 

 sheet would of course be one-fourth that represented 

 in the diagram, but still it would be three miles thick 

 at the Pole ! 



There is another cause which tends to mislead us 

 in forming an estimate of the actual thickness of the 

 Antarctic ice. It is not in consequence of any a priori 

 reason that can be urged against the probability of 

 such a thickness of ice, but rather because it so far 

 transcends our previous experience that we are so 

 reluctant to admit such an estimate. If we never 

 had any experience of ice thicker than what is found 

 in England, we should feel startled on learning for 

 the first time that, in the valleys of Switzerland, the 

 ice lay from 200 to 300 feet in depth. Again, if we 

 had never heard of glaciers thicker than those of 

 Switzerland, we could hardly credit the statement 

 that, in Greenland, they are actually from 2000 to 

 3000 feet thick. We in this country have long been 

 familiar with Greenland ; but till very lately no one 

 ever entertained the idea that that continent was 

 buried under one continuous mass of ice, with scarcely 

 a mountain top rising above the icy mantle. And 

 had it not been that the geological phenomena of the 

 Glacial Epoch have for so many years accustomed our 



