The Botany of Iceland - 01.12.1914, Side 109

PHYSICAL GKOGRAPHY
293
geology of Iceland has been able to find any support for tbis
hypothesis.
The Tertiary vegetation — probablv from Eocene and Miocene
times — which, as alreadjr mentioned, is found in the clay beds
and in the so-called “Surtarbrand” in the middle of the basalt
formation, was probably much altered in character even in Pliocene
times, but unfortunately from this period there has as yet been
found only a few small and undeterminable fragments of plants
(conifers). When the Glacial period buried Iceland beneath an icy
covering the Tertiarv flora died out entirely, and the present flora
must consequently have immigrated after tlie Glacial period and
perhaps even partialljr during it, in intervening milder periods when
the glacíers retreated slightly. As yet there are no real proofs to
hand of an intergiacial period in Iceland when the countrv was
entirely free from ice and partially plant-covered.
As already mentioned, onljr a verv small part of Iceland is
really plant-covered. The continuous carpets of vegetation are onljr
of slight extent compared with the considerable area of the island,
and even in low-lying, inhabited districls large areas are occupied
by rocky flats, Grimmia-heaths, sandjr stretches poor in plant-life,
lava-streams, etc. This is of course primarily due to the northerly
situation of the island and the climatic conditions. The climatological
chapter shows that the climate of Iceland is raw and cold. The
winter is long, but generally not very severe; the summer is com-
paratively short and cold and the weather is usually changeable
and damp; during spring, cold winds and sea ice accompanied bv
fogs do great damage as they often occur in the beginning of the
growth-period. In many places the plants — many of which are
evergreens — are protected from the cold of winter by a lasting
snow-covering, but, as we have seen in the above, in several districts,
especially in South Iceland, this snow-covering is variable and of
short duration so that plant-growth suffers greatly under the in-
fluence of the cold wind; it is easilv seen that there is great dil'-
ference in the vegetation of the bare gravelly flats where the snow
dril'ts off and of the depressions and localities in the shelter of roeks
where the snow persists. Differences in the temperature and weather
conditions of the different vears according to whether Polar ice
visits the coast or not, are ol' the greatest importance to plant-life.
Geographie, Gotha 1906, pp. 229-242. Islands Fjorde og Bugter (Geogralisk Tids-
skrift, XVI, 1901, pp. 58—82).