The Botany of Iceland - 01.12.1914, Blaðsíða 51

PHYSICAL GEOGRAPHY
235
even as late as in the lðth century. Where the basalt mountains
are not too steep nor the mountain-streams too torrential, the flat
gravel-cones upon the valley sides, below the notches in the moun-
tain, are often overgrown with plants. These gravel-cones often
underlie the home-fields of tlie farmsteads.
In the fjord districts of Iceland the vegetation upon the hasalt
mounlains differs considerably in passing from the sea inwards.
Owing to the effect of the sea-water, the violent storms and the rawness
of the climate, the outermost points are comparatively poor in plants,
while the vegetation increases inwards towards the valley, and in
the bottom of the valleys, especially on the north-western peninsula,
remains of coppice woods are often found; but woods could not
thrive out along the fjords, still less at the extreme points. Where
the basalt does not occur as steep cliffs and is not covered bjr loose
layers of clay, glacial gravel and soil it is usually strewn with loose
sharp-edged fragments, split and torn off by frost. The severance
of these fragmenls usually follows the cleavage of the basalt, and
they are sometimes slaty and in thin plates, a condition which is
especially common in the uppermost part of the basalt formation.
Upon the split and torn basalt in the uppermost part of the moun-
tains, plants have difficulty in gaining foothold, especially wlien
the climate is as raw and stormy as is the case in Iceland. There-
fore, large areas of the higher-lying basalt districts are extremely
poor in plant-life even in places, where according to the situation,
the conditions might be expected to be somewhat more favourable.
The landscape in the tuff and breccia districts has a different
appearance. Basalt mountains usually have sharp, and breccia
mountains soft outlines. Those areas of the cultivated districts and
on the lower spurs of the highland which are built up of tuff and
breccia have often a more or less undulating appearance; the moun-
tains are broken down into numerous rounded ridges and pro-
tuberances with intervening stretches of level ground and valleys
of irregular shape; but here and there are seen tabular inountains
or promontories with steep sides and a flat surface, where the basalt
or dolerite has covered and protected the tuft' and the breccia. On
the plateau, where through centuries storms liave been continually
altering the sculpture of the surface, the soft tuff-mountains have
sufifered in particular; here the tuff-ridges are connected into irregular
chains wliich liave been eroded in every possible way, and often
resemble fantastic ruins with numerous sharp peaks, protuberances
The Botany of Iceland. I. 16