The Botany of Iceland - 01.12.1942, Blaðsíða 28

26
JOHS. GRONTVED
wind, and only the coarse gravel and boulders are left on the surface of
immense areas of the inland plateau. Thus the wind often prevents the
formation of a surface soil in which plants can root. And in places
where a carpet of vegetation is formed it often happens that strong
sandstorms destroy the plant-cover. The dried out soil-layer consisting
of fine material will then be carried away down to the underlying gravel
or rock, sometimes leaving more resistant parts standing like ruins on
the outblown plain.
The fine dust and sand may be carried away to the remotest quarters
of the country and there be deposited as a layer all over the surface.
Most of the material, however, naturally falls in the districts bordering
the tufa areas or in places situated within these, as the tuff formations
yield abundant material to the dust-storms, owing to pronounced
disintegration. The Icelandic name for tuff dust and fine sand which
is carried down into the lowland by the wind, and in places has formed
layers up to fOO metres or even more, is “móhella”. It is of a loess-like
character and plays a most important part in forming the principal
material of the Icelandic soil and subsoil over immense areas.
In some parts of the central plateau, as also in the lowlands, large
stretches of land are covered with blown sand of a coarser quality. Such
areas are as a rule destitute of vegetation, since the sand is constantly
moving, owing to the shifting winds; in other places the sand dunes are
overgrown with a more or less scattered vegetation of lyme grass (Elymus
arenarius). The sand, which consists mainly of disintegrated basaltic
material, is dark of colour, often nearly black.
Soil Conditions. A short but very elucidatory view of the
peculiarities of the Icelandic soil has been given by the late Prof. Fr.
VVeis in a paper printed in the Yearbook of the Agricultural College
in Copenhagen, 19331. The results of his investigations are set forth in
a table (p. 8, loc. cit.) , and I take the liberty of giving it here in extenso
(Table 1, p. 24—25). As will be seen, in all 18 samples of soil were
investigated. Where nothing else is stated the samples are derived from
the upper soil layer to a depth of about 15 cm.
The reaction figures indicate soils which, with one exception (no.
IV) are practically non-acid and in some cases approach the neutral
point (pH = 7).
It will be seen that most of the Icelandic soils contain considerable,
in some cases surprisingly large, amounts of organic matter. Exceptions,

1 Fr. Weis, Some investigations on Icelandic soil types.