Greinar (Vísindafélag Íslendinga) - 01.01.1977, Blaðsíða 22

20
on one hand, and the structure of the rocks, on the other, make
early and late stages of Pleistocene glaciations in Iceland, as
well as the late-glacial frost effect quite different from those
in Scandinavia and in Canada.
The extreme asymmetry of the Scandinavian ice sheets rela-
tive to the ice divide, as it is inferred from the vestiges of flow-
ing ice, must now be explained. This has no doubt been done
before, so that my explanation will add nothing new.
We should first look at Greenland with its extremely loose
and light surface snow and, hence, the huge quantity of snow,
blown from the interior of the high ice cap. Very loose and
light snow indicates formation at a high altitude — a low
temperature combined with low humidity in the air. Such condi-
tions would be natural over the high Scandinavian ice divide,
just as they are today over central Greenland.
Very strong westerly winds, which brought the hmnidity
would, therefore, transport a great quantity of loose snow to-
wards the east and nourish the extensive ice sheet. A classical
evidence of strong westerly winds in the glaciated northern
Europe, is the loess belt extending from western Europe all
the way to China, see also (10) and (11). In contrast to Green-
land and glaciated Scandinavia up to the maximum stage, the
Icelandic glaciers of Older and Younger Dryas time, were
much lower. The surface snow would have been coarser and
heavier. But in fact, the clearest evidence of blowing of snow
by east- to southeasterly winds, is the great asymmetry of
the Bláfjöll glacier, Fig. 4. And now we understand that it
was just wind from the east-southeast, which caused the main
glacier to extend and flow in the WNW-direction towards the
Hvítárvatn area. For the same reason the Langjökull did not
extend much farther east than now during the Dryas Stages.
On the other hand, it might have extended much farther to
the west-northwest, and just this is indicated by lake areas
(Arnarvatnsheiði, Tvídægra) and gullies, as we suggest in
Fig. 2.
During the Climatic Optimum, some 3000 years ago, the
Vatnajökull did not exist (12). Instead, there were only se-