E. H. L. Sclmarz — The Thickness of the Ice-Cap. 123 



^hat the lowering of the melting-point of ice due to pressure is not 

 materially affected by the intense cold at the surface, and that 

 therefore we may take the physicists' estimate of the maximum 

 thickness as approximately correct. 



Scott found the Antarctic ice-cap to be flat on the surface of the 

 land with an edge of rock which, from the sea, appeared to consist 

 of lofty mountains, but the highest points of these sank below the 

 horizon directly the level of the ice-cap was reached. Peary and 

 Nansen have found the same thing in Greenland. The tops of the 

 mountains look as if they once were part of a peneplain, but Nausea 

 maintains that it is not likely that a great land-mass like Greenland 

 should be all on a level beneath the ice. In his later researches, 

 however, Nausen has demonstrated the existence of a vast sub- 

 marine plateau in the Arctic Ocean, and if the plateau here rose 

 above the sea by block-uplift it would be covered by ice and 

 protected from denudation by ice. Douglas Freshfield, in his 

 address to the British Association at Cambridge, stated that it is at 

 the face of the glacier that denudation begins, and the configuration 

 of the coastline in Greenland and in the Antarctic regions beai's 

 this out ; the valleys go but a short way inland, and are ended 

 abruptly. If, then, there is some reason to suppose that the polar 

 ice-caps lie on level land, the argument for estimating the thickness 

 of ice above the limit which physicists say is the maximum is shown 

 to be of doubtful value. 



The only way by which a sheet of ice over the 1,600 feet limit 

 can exist is when the surface of the ground on which it rests is 

 below the temperature of the melting-point of ice, and to obtain 

 such a condition of things there must be a cause of abstraction of 

 heat from within the earth, as the ice-sheet forms a blanket to 

 protect the surface of the ground from radiation from above. The 

 heat of the earth's interior is always creeping outwards, and instead 

 of abstracting heat from the ice it is the ice that is abstracting heat 

 from the earth. Not only is this true for the existing ice-caps, 

 but it must have been true for the ice in the Glacial periods of the 

 northern hemisphere and the Palaeozoic ice-ages of the southern, 

 and I cannot, therefore, see how it is possible, in the light of 

 physical experiment, supplemented by actual observation, to obtain 

 the great thickness of ice that glacialists ordinarily call in to explain^ 

 the phenomena which they have described. 



Finally, there is one observation of Commander Scott's ^ which 

 perhaps explains the enormous apparent thickness of glacier ice in 

 past ages as seen in the evidence afforded by ice-scorings on the sides 

 of the valleys. In the Ferrar glacier the ice had once been from 

 3,000 to 4,000 feet higher than it is at present. There is also reason 

 to suppose that the climate was milder at the period of maximum 

 glaciation, because it is physically impossible for cold air to contain 

 much moisture and consequently to feed the glacier streams. With 

 a milder climate the ice must have melted more easily, and yet even 



1 <' Yoyage of the ' Discovery,' " p. 416. 



