The Botany of Iceland - 01.12.1949, Síða 12

10
EMIL HADAC
enormous in such places. The result of this action is a rapid disintegra-
tion of the palagonitic and morainic material. All the sand and dust
from disintegrated rocks is blown by the foehn wind to a considerable
height and deposited as aeolic sediment at some distance from Sand-
kluftir being caught by the vegetation (especially birch copses). Thus
we can see close to each other a deflation area and an accumulation
area. Simultaneously this provides us with a proof of the fact that
loess still originates even nowadays; another place where loess creation
may be observed is e. g. Skálafell SE from Kolviðarhóll and in other
places.
How intensive the loess sedimentation is may be seen from figures
published by Emilsson. He found in recent peat bogs about 50 %
anorganic dust i. e. loess. Recent loess formation in Greenland was
described also by O. Nordenskjö 1 d, who also emphasizes the
function of the vegetation in the formation of loess.
It is obvious that it is for these reasons not necessary to presuppose
the existence of a windless period, climatically different from the recent
one, for loess sedimentation, although we know very well that the
climate has changed radically since the end of the glacial period. In
my experience only such places are deprived of a loess cover, as have
no copse vegetation. Birch-copse community is (at least in the lowland)
the climax community. From the history as well as from subfossil
deposits we know that birch “woods” were distributed all over the
country in the “Landnáma” time. Man has destroyed a great part of
these “woods” for heating and similar purposes. But the greater part
has been and still is being destroyed by sheep. To-day there are about
600.000 sheep in Iceland, i. e. about 6 per 1 km2. These creatures are
grazing for the greater part of the year freely all over the country, and
it is known that such has always been the case already from the first
beginning of colonization (cf. e. g. Laxdalasaga). When thousands of
men and thousands of sheep for several hundreds of years (hitherto
about 1000 years!) destroy birch copses and vegetation in general, we
cannot expect any other results than those we see round us to-day.
The whole loess history many be summed up in the following
manner: The loess originates on Iceland by weathering of tuff and
morainic material (palagonite formation) and becomes caught by the
vegetation. The vegetation tends to the c 1 i m a x i. e. the birch copse
vegetation. Before the colonization of the Island the vegetation
cover was practically in equilibrium. All wounds
caused by wind or rain etc. were soon healed. The first settlers and