ICE AGE REFUGIA IN ICELAND 305 



wherever conditions were favorable for their growth. But the fact remains 

 that only a httle more than half of the Icelandic higher plants occur all 

 over the country. Even so, there are often considerable gaps in their 

 distribution, although no natural obstacles to their continuous distribution 

 be found. 



Then the question is posed: how did the plants originally reach Iceland? 

 There we must hold to the theory that a land-bridge connected Iceland to the 

 neighboring countries during the Tertiary period, or that at least there may 

 have been a lesser distance between Iceland and other countries both before 

 and during the Ice Age itself than there is now. This might have faciUtated the 

 migration of biota, both before the Ice Age and in the Interglacial periods. 



Assuming that biota have survived the Ice Age in Iceland, we must obtain 

 answers to two questions. First, are there geological possibilities for the 

 existence of ice-free regions in the country during the Ice Age ? Second, has the 

 existence of vegetation in the Interglacial periods been proved ? 



The first question has been answered by Thorarinsson (1937), who pointed 

 out at least four districts in the country, which in all probability have only 

 been partially glaciated during the Last Glaciation. 



The answer to the second question is also in the affirmative, as fossil 

 plants from Interglacial formations are found at several places in the 



Although the evidence of some ice-free areas in the country during the Ice 

 Age can be proved, we cannot state with certainty that plants have survived in 

 such places when the greater part of the country was covered by glaciers, and 

 the climate was entirely of an Arctic character. But inferences may be drawn 

 from the conditions prevailing at the present time in Arctic countries such as 

 Greenland, where a fair number of species are found on nunataks which are 

 completely surrounded by the inland glacier, and the climate cannot differ 

 very much from that of the Ice Age. 



In this connection it may be pointed out that near the glaciers in the central 

 plateau of Iceland are found patches with luxuriant vegetation on the south 

 sides of hills and slopes. 



The first hints about survival of biota in refugia in Iceland were expressed 

 by scientists some thirty years ago (Lindroth, 1931; Gelting, 1934). I myself 

 took up the question for closer investigation in the years 1936-40. 1 especially 

 tried to find out whether the distribution of species in any way indicated the 

 possibihty of overwintering in probable refugia. I pubUshed the first remarks on 

 this problem in a small paper in 1937, and in a somewhat more exact form in 

 a second paper in 1949. In the latter I pointed out five districts in the country 

 which I considered as probable refugia. This view was based on the strange 

 mode of distribution of almost 100 species of plants which seemed to be 

 concentrated in these districts and their immediate vicinity. Further investiga- 

 tions have confirmed my early statements on this subject. 



