16 MARTIN SCHWARZBACH 



With higher temperatures in the polar region there is, of course, no change 

 in the unusual distribution of day and night so characteristic for high latitudes ; 

 that means we have the additional problem of the polar night, of short- and 

 long-day plants. But, considering the successful cultivation of hundreds of 

 plants by Icelandic greenhouse gardeners, among them many plants from 

 subtropical regions, we must admit that this problem cannot be a difficult 

 one. 



There exists the real difficulty that we do not know the exact age of the 

 Tertiary polar floras. In part they seem to be of older Tertiary age. Pollen- 

 analysis also points in that direction. But we can only express conjectures 

 as long as we have no reference to securely dated beds of mammals or marine 

 faunas or have no absolute age determinations. 



We must suppose — as everywhere on the Earth — that the younger Tertiary 

 was cooler than the older, and that there was a gradual transition to the 

 Quaternary Ice Age. The Pliocene marine beds of Tjornes in northern Iceland 

 — the only Pre-Quaternary marine sediments of the island — indeed show such 

 faunas. The faunas of the lower parts of the Tjornes beds required higher 

 temperatures than the recent sea. (I have supposed a difference of 5°C 

 according to the faunal list of Bardarson, 1925.) But the temperatures of the 

 youngest Phocene can have been only slightly higher than now. 



Of special interest in this connection are the studies by Jon Jonsson (1954) 

 in the region of Hornafjordur, southeastern Iceland. He found tilhtes there, 

 overlain by hgnites. The pollen-analytic investigations by Pflug (1956) in the 

 Geological Institute of Cologne showed that the hgnites may be from younger 

 Tertiary, meaning that moraine-depositing glaciers already existed before 

 this time (i.e. also in Early Tertiary time). We do not need to imagine a large 

 Vatnajokull at this time, but at least we must take into account small Tertiary 

 glaciers. The general gradual cUmatic deterioration of the Tertiary in Iceland 

 led temporarily and locally to glacial chmatic conditions. We know nothing — 

 at least not directly — of the other North Atlantic regions in this respect, but 

 we can suppose similar conditions in Greenland and Spitsbergen; all the more 

 so because Early Tertiary glaciers already existed in Alaska, according to 

 studies by Miller (1953). 



For the problem of the development of biota in the North Atlantic it is of 

 great interest to know a little not only about the Tertiary climate but also 

 about paleogeographic conditions on the whole. Generally we can say that the 

 climatic picture allows no room for continental drift, at least not on a big 

 scale. That is in agreement with paleo-magnetic results. We must suppose that 

 the cause of the warm Tertiary climate in Europe was partly a powerful 

 Gulf Stream which could flow unchecked far to the east and northeast. 

 Therefore, paleoclimatologists have no reason to construct a land-bridge 

 between Europe and North America; on the contrary, the evidence speaks 

 more against an emerged Faeroes-Iceland ridge. I mention, by the way, that 



