394 ASKELL LOVE 



that this North Atlantic land-mass had connections northwards and eastwards 

 but hardly all the way to the present American continent. Davis Strait may 

 thus be older than other parts of the North Atlantic Ocean and have acted as 

 an effective barrier to dispersal for a long period of time (cf. Lindroth, 1960). 

 It is, however, also evident that the early Tertiary flora of Iceland was 

 largely American, or, perhaps more correctly, belonged to the so-called 

 "Arcto-Tertiary" or rather "Tertiary-mesophytic" flora that was — and still 

 in part is — common to eastern North America and eastern Asia (cf. Li, 1952). 

 That Denmark Strait— between Iceland and Greenland — apparently has 

 also acted as a strong barrier when this flora was replaced by a more boreal 

 one, seems to be indicated by the fact that the Icelandic flora at present is as 

 typically European as the Greenland flora is typically American, a puzzle 

 not explained at this Symposium. 



Although it is possible to draw conclusions hke these based on our present 

 knowledge of the history of the North Atlantic and its biota, one ought not to 

 forget that this knowledge still is so hmited as to make many of these con- 

 clusions very preliminary, and thus, controversial. 



Even if we feel that the general picture of the history of the North Atlantic 

 and its biota is emerging into greater clarity, this symposium also has shown 

 that we are in the happy situation of still being confronted by unsolved 

 problems of considerable importance for the problem of the geological and 

 biological history of this region. The answers to even some of the apparently 

 minor questions might aff'ect the major picture considerably. These may be 

 geological as well as biological, and it seems futile to try to mention more than 

 a few problems in need of consideration. Important geological problems 

 are connected with the identification of refugia and unglaciated forelands 

 after the ice has left; these questions need to be investigated in the North 

 Atlantic region where glaciers are still active, although research in the Antarctic 

 may give us some answers. Another geological problem concerns the bottom 

 of the North Atlantic and, then, especially the transatlantic submarine ridges; 

 bottom cores from carefully selected localities might tell us if thftse ridges ever 

 have been raised above the sea, and if so, when and for how long a time. 

 Such cores taken close to the existing basaltous islands may perhaps reveal 

 in what way the hypothetical land connection has been formed in the Cretace- 

 ous. According to a common hypothesis, it should have been formed by 

 eustatic changes in the crust or by some kind of continental drift, whereas 

 another hypothesis assumes that it has been formed by volcanic eruptions 

 only, without drastic changes in sea level (cf. Tr. Einarsson, 1961). If the 

 latter hypothesis is correct, the more than 5000 m thick basalt plateau ought 

 to stand firmly on palagonite formed during suboceanic volcanic eruptions, 

 whereas the lack of such a palagonite formation would at least indicate 

 that the other explanations were more likely. Cores from the deeper parts of 

 the ocean might solve the mystery of the "Scandic", or perhaps of the 



