78 A SUMMER IN GREENLAND 



often basalt, that has been formed by the slow 

 cooling and crystallisation of molten material 

 forced from below through cracks and fissures in 

 the overlying strata. The softer rocks fall an easier 

 prey to the action of the weather than the harder 

 and more compact dykes which are left as great 

 ribs or dark brown buttresses projecting on a light 

 yellow background of less resistent material. 



The photograph reproduced in Fig. 35, taken 

 near Skansen, a small Settlement on the south-east 

 coast of Disko Island, shows in the distance the 

 basaltic plateau with an occasional glacier descend- 

 ing from the inland ice; in the foreground the 

 sloping sides of the valley are formed of light 

 yellow sandstones and beds of dark shale which at 

 a higher level are covered and protected by vol- 

 canic rocks that were formerly continuous with the 

 rest of the plateau. A cap of dark brown rock, 

 part of a basaltic dyke, has saved the small hill of 

 sandstone in the middle of the valley from the 

 destructive action of weathering agents. Fig. 36 

 shows a much narrower zigzag valley eroded by 

 ice streams through the sandy sediments; the cliffs 

 in the foreground have been weathered into 

 slender pinnacles and intersecting ridges; a little 

 lower down the ravine a brown jagged dyke of 

 basalt casts its shadow on the sloping surface of a 

 smooth embankment of light yellow sand, and the 

 sides of the farther hill are scarred with a succession 

 of small gulleys. Beyond the lower heath-covered 

 ground lies Disko Bay with scattered icebergs, 

 and on the opposite shore, too far away to be seen 



