THE ICE-FREE REFUGIA OF NORTHWESTERN SCANDINAVIA 323 



The lowering of sea level at the same time is computed as being between 105 

 and 123 m. 



Another result of the measurements in Antarctica is an increased knowledge 

 of the subglacial relief. In several places the ice sheet covers alpine landscapes 

 with valleys of the fjord type as well as well-defined peaks (Fig. 1). Such 

 observations demonstrate the impossibility of recognizing a real "nunatak 

 topography". Furthermore Robin (1958, p. 130) found in the "mountain ice 

 sheet area"' of Queen Maud Land that "in the case of larger features, such as 

 the valleys at 180, 310 and 410 km (Fig. 1) from Maudheim, the rock relief 

 controls the direction of ice flow, so that the greatest velocities of movement 

 will be along the line of such valleys. The erosion resulting from the flow of the 

 glacier will therefore tend to accentuate the underlying relief." 



The slope of the ice surface varies considerably. For instance, a number of 

 outlet glaciers leading to the Ross Ice Shelf have slopes between 1 :90 and 

 1 :25 (Kosack, 1955, p. 86), whereas Robin (1958, p. 109) has Hsted inclinations 

 between and 1:16. For a part of the "mountain ice sheet area" Robin's 

 thorough investigation has confirmed Nye's general hypothesis that the 

 thinnest ice cover is indicated by the steepest surface slope. 



In many cases ice shelves exist over considerable depths of water. In front 

 of the Ross Ice Shelf systematic soundings have demonstrated that depths of 

 500 to 700 m are normal (according to U.S. Navy Hydr. Office, 6636, 1957), 

 while the Filchner Ice Shelf seems to extend over depths of more than 1000 m 

 (Thiel and Ostenso, 1961, p. 828). The considerable depths under the inland 

 ice — referred to above — emphasize that sea depths greater than those of a 

 normal shelf do not form a definite limit for expanding ice sheets. "Whether 

 or not the ice would extend further out to sea would depend largely on the 

 heat supply and circulation of the sea water" (Robin 1958, p. 132). 



According to Bauer (1955) 0.6 x 10" km^ or about 4 per cent of the Antarc- 

 tic continent is ice-free. Nunataks are common features, especially in the 

 marginal zones. At the edge of the continent ice-free lowlands appear, forming 

 re-entrants in the ice sheet. Such so-called "oases" are known from almost 

 all parts of the coastal region of Antarctica. The largest one, Bunger's 

 "oasis" (Fig. 2), has been described in several Russian reports (for instance: 

 Avsyuk, Markov and Shumskiy, 1956a, 1956b). It has an area of about 

 600 km^ and is surrounded by ice, which consists in part, however, of shelf 

 ice and old pack ice. Roches moutonnees, striae, erratics, and till demonstrate 

 that the "oasis" once was glaciated, but it seems to have been ice-free for at 

 least 4500 years (loc. cit. p. 15; cf. Rozycki, 1961): it now seems to be quite 

 stable. The deglaciation of this "oasis" as well as of others (cf. Bull, McKelvey 

 and Webb, 1962) is believed to be the result of starvation, caused by a decrease 

 in the surface level of the ice sheet in connection with an increasing influence 

 of rock thresholds. A quite unique climate is formed in the "oasis". Precipita- 

 tion is rather heavy, probably 600-700 mm a year, only in the solid state. In 



