PHYSICAL GEOGRAPHY 293 



geology of Iceland has been able to find any support for this 

 hypothesis. 



The Tertiary vegetation probably from Eocene and Miocene 

 times which, as already mentioned, is found in the clay beds 

 and in the so-called "Surtarbrand" in the middle of the basalt 

 formation, was probably much altered in character even in Pliocene 

 times, but unfortunately from this period there has as yet been 

 found only a few small and undeterminable fragments of plants 

 (conifers). When the Glacial period buried Iceland beneath an icy 

 covering the Tertiary flora died out entirely, and the present flora 

 must consequently have immigrated after the Glacial period and 

 perhaps even partially during it, in intervening milder periods when 

 the glaciers retreated slightly. As yet there are no real proofs to 

 hand of an interglacial period in Iceland when the country was 

 entirely free from ice and partially plant-covered. 



As already mentioned, only a very small part of Iceland is 

 really plant-covered. The continuous carpets of vegetation are only 

 of slight extent compared with the considerable area of the island, 

 and even in low-lying, inhabited districts large areas are occupied 

 by rocky flats, Grimmia-heaths, sandy stretches poor in plant-life, 

 lava-streams, etc. This is of course primarily due to the northerly 

 situation of the island and the climatic conditions. The climatological 

 chapter shows that the climate of Iceland is raw and cold. The 

 winter is long, but generally not very severe; the summer is com- 

 paratively short and cold and the weather is usually changeable 

 and damp; during spring, cold winds and sea ice accompanied by 

 fogs do great damage as they often occur in the beginning of the 

 growth-period. In many places the plants many of which are 

 evergreens are protected from the cold of winter by a lasting 

 snow-covering, but, as we have seen in the above, in several districts, 

 especially in South Iceland, this snow-covering is variable and of 

 short duration so that plant-growth suffers greatly under the in- 

 fluence of the cold wind; it is easily seen that there is great dif- 

 ference in the vegetation of the bare gravelly flats where the snow 

 drifts off and of the depressions and localities in the shelter of rocks 

 where the snow persists. Differences in the temperature and weather 

 conditions of the different vears according to whether Polar ice 



* 



visits the coast or not, are of the greatest importance to plant-life. 



Geographic. Gotha 1906, pp. 229-242. Islands Fjorde og Bugter (Geografisk Tids- 

 skrift. XVI, 1901. pp. 5882). 



