The Botany of Iceland - 01.12.1945, Síða 25

THE VEGETATION OF CENTRAL ICELAND
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2. Víðidalur and Kollumúli. Víðidalur is a fairly
long valley situated south of the small glacier Hofsjökull. Its upper
part almost reaches Vatnajökull and is here very shallow and poor in
vegetation. Farther down, where the valley is deepest, there is a very
luxuriant vegetation, but here the actual highland vegetation ceases,
the bottom of the valley being elevated only a little more than 400 m
above the sea. On the mountain sides the typical highland vegetation
is met with. The same applies to Kollumúli, the mountain ridge south
of Víðidalur, between the latter and Jökulsá í Lóni. Farthest
down along Jökulsá there occur birch scrub and other types of lowland
vegetation, while higher up there are screes devoid of vegetation, mossy
heaths or gravelly flats, and altogether a very poor vegetation.
D. Síðumannaafrjettur.
The fourth highland region investigated by me is Síðumanna-
afrjettur southwest of Vatnajökull, or more correctly, the highest part of
it. Still this area is the lowest of the areas investigated, being situated
about 400 m above sea-level. The greater part of it consists of a slightly
sloping stretch of mýri or flói with countless lakelets or pools. Higher
up there occur extensive gravel plains, above which rise some tuff
mountains, in which either gravel flats or Grimmia heaths are found.
A very large part is covered with immense lava masses from the
tremendous eruption of the Laki in 1783. The lava is now covered
with Grimmia heaths, but has a very scattered and poor phanerogamous
vegetation. Although a great part of this region falls outside the limits
I had set myself, as I chiefly intended to describe the vegetation found
above an altitude of 500 m, the vegetation of this region may serve as
a type of the transitional form between the highland and the lowland
vegetation. It also differs from the other areas in that the vegetation
here is continuous with the lowland vegetation, whereas in the other
regions it is separated from it by large barren tracts of land. This neces-
sarily sets its mark on the vegetation and makes it richer and more like
that of the lowland than is otherwise the case.
E. Oases in the centre of the country.
1. Near Geldingsá. The area investigated lies partly in
the small depression extending along the small river Geldingsá before
it empties into Jökulsá eystri, partly near Jökulsá in the so-