194 THORODDSEX 



Vatnajokull cover an area of about 8000 square km. The axis of 

 elevation lies from NW. to SE., from somewhere near the head of 

 Hvammsfj6r5ur to Hornafjor5ur; it does not, however, consist of 

 one continuous ridge, but of a series of snow-covered, dome-shaped 

 mountains separated by broad stretches of more level ground. These 

 snow- and ice-covered domes are strictly speaking a series of small 

 plateaus which rise from the main plateau to an absolute height 

 of 1400-2000 metres, as compared with 600 1000 metres above 

 the plateau. The most easterly of the great glacier-bearing moun- 

 tains is Vatnajokull which is separated from the much smaller 

 Tungnafellsjokull (100 square km.) by Vonarskard (1000 metres); be- 

 tween Tungnafellsjokull and Hofsjokull (1350 square km.) lies the 

 broad stretch of level ground, Sprengisander (650 metres); west of 

 Hofsjokull and between the latter and Langjokull (1300 square km.) 

 lies Kjolur or Kjalvegur (600 metres); and between Langjokull and 

 Eiriksjokull (100 square km.), Flosaskar5 (800 metres). The plateau 

 north of the last-mentioned ice-mountains abound in lakes and bogs. 

 The interior plateau consists chiefly of deserts almost destitute of 

 vegetation, but the surface varies somewhat in character in accord- 

 ance with the geological nature of the underlying rock. Where 

 basalt or dolerite forms the substratum, the surface is strewn with 

 innumerable angular blocks of rock, split asunder by the action of 

 frost; where tuff and breccia form the foundation, the surface is 

 usually covered with gravel and fragments of slaggy lava which 

 have been loosened from the breccia bv the action of weathering. 



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More than one- half of the plateau is overlain by more recent 

 formations lava, blown sand, volcanic ashes, glacial forma- 

 tions, clay and river-gravel. The lava-fields, taken together, cover 

 a very large area in the interior and present a most desolate 

 scene; as far as the eye can reach only a black, hardened mass is 

 seen, and the dark colours are only here and there interrupted by 

 mounds of reddish slag, smoking craters, scattered snow-drifts, and 

 in the distance by glistening, white Jokull-domes; there is no sign 

 of life and an oppressive silence reigns over the land. 



The interior plateau is trenched by many valleys, chiefly towards 

 the north and east; between these valleys long mountain spurs 

 the skeletal ribs of the eroded plateau branch outwards toward 

 the sea. Of these, the mountain- mass which extends towards the 

 south, and is crowned at the top by Myrdalsjokull , is the most 

 considerable. Towards the west the two volcanic mountain-chains 



