322 GUNNAR HOPPE 



The discussion, however, has continued and to a certain extent has also been 

 affected by the progress in different scientific fields connected with the actual 

 problem, by the development of new techniques, by parallels with other 

 areas, etc. The present paper should be regarded primarily as an attempt 

 to apply experience from other fields and areas to the refugium 

 problem. 



SOME EVIDENCE FROM ANTARCTICA 



During the last 15 years a large number of expeditions visited Antarctica 

 and have added immensely to our knowledge of that continent. Many of the 

 results are pertinent to the problem under consideration, and reference should 

 be made to some of them. Naturally this discussion will not solve anything, 

 but it may give some ideas as to the nature of the inland ice of northern Europe, 

 and of what is possible and what is impossible. 1 might first mention that the 

 size of the ice sheet of northern Europe is open to debate, but it ought to have 

 been between 35 and 50 per cent as large as that in Antarctica. 



Seismic, gravity and altimetry measurements have given much information 

 about the thickness of the Antarctic ice sheet. In East Antarctica a value of 

 more than 3000 m was found in a vast area around the U.S.S.R. bases Vostok 

 I and KomsomoFskaya (Shumskiy, 1959). The bedrock topography is totally 

 hidden; the thickness of the ice, however, may be as httle as 1000 m in places. 

 For the smaller region of West Antarctica a mean ice thickness of 1500 to 

 2000 m has been suggested. The greatest thickness, 4270 m, was measured in 

 a place where the bedrock surface lies 2500 m below present sea level. This 

 depth is in a 400 km wide sub-ice channel, which probably bisects West 

 Antarctica. Even if the ice should melt and the rock surface rebound to isostatic 

 equiUbrium, the deepest part of the channel would still be as much as 1500 m 

 below present sea level. It has been suggested that the West Antarctic ice 

 sheet originated as two separate ice sheets in two separate mountainous areas. 

 As these sheets expanded they converged over the intervening open water; 

 they were probably joined at first by a floating ice shelf, which then grew 

 thick enough to fiU the trough completely and produce the present single ice 

 sheet which is aground (Bentley and Ostenso, 1961, p. 895). The minimum 

 time required to build up such a thickness has been computed by Wexler 

 (1961) on the basis of a series of assumptions. Thereby one alternative gives 

 about 20,000 years, another about 40,000 years. Quite recently new calcula- 

 tions of the mean thickness of the Antarctic and other ice sheets have been 

 undertaken (cf. Donn, Farrand and Ewing, 1962). The values obtained for 

 Antarctica vary between 2000 m and 2500 m. On the basis of such data and 

 the statement by Nye (1959) that the thickness of an ice sheet at equilibrium 

 is essentially a function of the areal dimensions of the sheet rather than the 

 accumulation, Donn, Farrand and Ewing have calculated a mean thickness 

 of 1700 to 1800 m for the Scandinavian ice sheet during the WUrm maximum. 



