PHYSICAL GEOGRAPHY 201 



through their glaciers and glacier-rivers they exert a great influence 

 upon the surface and climate of the country and upon the condi- 

 tions of life of the inhabitants. The Icelandic climate is specially 

 adapted to the development of large glaciers, for the air is raw and 

 cold and moist, the amount of rainfall considerable and the summer- 

 heat slight. The amount of precipitation is greatest towards the 

 south-east and there the interior tahle-land is covered bv the sreat 



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Vatnajokull. The altitude of the snow-line varies from 400 to 1400 

 metres in the different parts of the country, and the level above 

 the sea at which the glaciers end differs greatly: in the north on 

 the north-western peninsula, and in the south near Vatnajokull, the 

 glaciers descend almost to the sea, to 25 metres and 9 metres above 

 sea-level respectively at the lowest points to which they descend. 

 The great ice-mountains of Iceland are without exception closely 

 associated with the plateau. Large areas of the highest part of the 

 plateau are covered with neve which occurs as slightly-arching 

 domes or undulating snow-fields of great thickness. Prominent 

 mountain-peaks are rare; the latter do not appear until near the 

 edges of the snow-fields and usually as outstanding summits of the 

 underlying rock. The surface of these snow -fields is devoid of 

 gravel; this does not appear until it does so at the extremities of 

 the glaciers which are often quite black with it and with sand and 

 blocks of rock. The large glaciers which descend from these /Re- 

 covered flats have., on an average, a very slight declivity ; only in 

 places where precipitous mountain-peaks project from the edge of 

 the snow-field, do steep glaciers of small dimensions occur. The 

 large glaciers of Iceland closely resemble the glaciers typical of 

 Arctic countries; but there are a great man} 7 small glaciers which 

 resemble those of the Alps. Several of the broad glaciers which 

 descend from Vatnajokull cover a very considerable area (e. g. Dyngju- 

 jokull 400 square km., Bruarjokull 500 square km., etc.). Peculiar 

 to Iceland are the so-called "glacier-torrents 1 ' (Jokul-hlaup). When 

 the glaciers, by the eruption of volcanoes hidden under the ice, are 

 broken to pieces and melt, the large stretches of land beneath them 

 are inundated by a roaring sea of dirty water with swirling ice- 

 bergs. Such catastrophes may cause great changes in the surface- 

 features of the surrounding country, as the waterfloods often carry 

 along with them an incredible quantity of gravel and rocky blocks. 

 In this way the volcano of Katla especially has caused considerable 

 changes the course of rivers are constantly changed, the smaller 



