THE [CE-FREE REFUGIA OF NORTHWESTERN SCANDINAVJA 327 



1951; Gross, 1958; Klein, 1953; Klute, 1951; Manley, 1951; Mortensen. 

 1952; Penck, 1938; Poser, 1948; Woldstedt, 1958; etc.). For central Europe 

 a reduction of 10 to 13°C in the mean annual temperature is commonly 

 accepted; for western Europe a somewhat smaller temperature decrease is 

 thought to have occurred. From a biological .iewpoint, however, information 

 about the summer temperature ought to be of even greater interest. The arctic 

 tree line which approximately coincides with the July 10°C isotherm, seems 

 to have run south of the Pyrenees in western Europe (Biidel. 1951; Frenzel 

 and Troll, 1952); for the coldest part of the WUrm, Gross (1958) has calculated 

 a temperature of about 5°C in middle Germany, i.e. about 14°C lower than 

 now. Naturally such temperature calculations are very rough; but at least 

 they justify the hypothesis that the temperature must have been very low on 

 the northwestern side of the Scandinavian ice sheet, much too low to make 

 forest vegetation possible on ice-free areas, if such existed. 



The meteorological situation also has been treated in connection with the 

 climatological considerations. One such discussion may be mentioned, owing 

 to the importance of the problems involved and the special competence of the 

 author. On the basis of his meteorological studies in Antarctica, Liljequist 

 (1956) deals with the effect of the growing Scandinavian ice sheet. According 

 to him an accentuated temperature contrast between snow- and ice-covered 

 areas and bare ground should have developed. As the ice sheet grew this 

 frontal zone — and the cyclonic tracks corresponding to this zone — moved 

 southward. During the maximum of the glacial epoch the main cyclonic 

 tracks thus ought to have come from west-northwest or west, passing middle 

 Europe on their way to the eastern part of the Mediterranean region and 

 southern Russia (Fig. 3). This atmospheric circulation ought also to have 

 influenced the sea-currents according to Liljequist. South of the main 

 cyclonic tracks westerly and southwesterly winds dominated, whereas to 

 the north, easterly winds prevailed. This should have caused the warm 

 North Atlantic Drift to bend toward the Bay of Biscay and Spain, while a 

 cold current probably went to the west between Iceland and the British Isles, 



The regressive stage of the Wiirm glaciation at first was characterized by 

 lability, by fluctuations in the climatic trend. The Younger Dryas was a 

 rather cold period, when the ice border according to general opinion made 

 long stillstands at the Salpausselka (Finland) — Middle Swedish moraines — 

 Raerne (Norway). During that time the July temperature in Denmark went 

 down again to about 10 C (Iversen, 1954); in the Netherlands cryoturbation 

 in the earlier deposited Allerod layers has been demonstrated to have occurred 

 and the existence of permafrost during Younger Dryas seems thereby to have 

 been proved (van der Hammen and Maarleveld, 1952). The last ice remnants, 

 still active glaciers, receded to the highest mountain regions, such as the 

 Sarek area in northern Sweden (Hoppe, 1960), and disappeared 7000 to 8000 

 years ago. 



