The Botany of Iceland - 01.12.1914, Blaðsíða 108

IV. ACCOUNT OF THE GENERAL DISTRIBUTION
OF PLANT-LIFE.
In connection with the description of the physiographical and
climatic conditions, I shall now try to give a very brief account
of the distribution of plant-life on the rocky substratum of Iceland.
The following should be regarded merely as an attempt towards a
description of the main features for general orientation. It is ex-
pected that later on in this work a more accurate and detailed
account of the plant-geographical conditions will be given, and the
ecological conditions and the different plant-formations will be de-
scribed and analysed by different specialists.
Geological investigation has proved that Iceland in early Tertiary
times was in all probabilitjr connected with Greenland and with
Scotland across the Færöes by a land-bridge of volcanic, especially
basaltic, rocks; the depression of this land-bridge had probably oc-
curred and the countries been separated even in the Miocene peiiod.
During Pliocene times Iceland was somewhat larger than it is now,
but subsidence continued; during this period the submarine coastal
platform was formed, wliich occurs around the whole island, and
also the now submarine fjord-grooves which lead off from the mouths
of the present-day fjords. At the end of Pliocene times the climate
gradoally became colder until the Glacial period laid a continuous
snow-covering over the whole island. Some botanists are of the
opinion that a land-bridge connected Iceland and the Færöes with
Greenland and Scotland during post-Glacial times also, but tliis
hypothesis is highly improbable as it is at variance with many
geographical and geological facts which are enumerated in the works
cited helow.1 No geologist who is closely acquainted with the
1 Th. Thoroddsen: Hypothesen om en postglacial Landbro over Island og
I'æroerne, set fra et geologisk Synspunkt. Ymer, Stockholm, 1904, pp. 392—399.
Endnu nogle Ord om Landbro-Hvpothesen. Ymer, 1906, pp. 93—101. Naturwissen-
schaftliche Itundschau, XXI Jahrg., No. 31. Island, Grundriss der Geologie und