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 probability connected with Greenland and with 

 Scotland across the Faaroes 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 period. 

 During Pliocene times Iceland was somewhat larger than it is now, 

 but subsidence continued; during this period the submarine coastal 

 platform was formed, which 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 

 gradually 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 Faeroes with 

 Greenland and Scotland during post -Glacial times also, but this 

 hypothesis is highly improbable as it is at variance with many 

 geographical and geological facts which are enumerated in the works 

 cited below. 1 No geologist who is closely acquainted with the 



Th. Thoroddsen: Hypothesen om en postglacial Landbro over Island og 

 Faeroerne, set fra et geologisk Synspunkt. Ymer, Stockholm, 1904, pp. 1592 399. 

 Endnn nogle Ord om Landbro-Hypothesen. Ymer, 1906, pp. 93101. Naturwissen- 

 schaftliche Rundschau, XXI Jahrg. , No. 31. Island. Grundriss der Geologie und 



