260 The Realm of Nature CHAP. 



sea-water. On the west coast of Scotland Loch Morar, a 

 fresh-water lake 178 fathoms deep, with its surface 30 feet 

 above sea-level, is connected with the sea by a short river. 



Loch Etive, exactly simi- 

 lar in configuration but 

 filled with sea- water, and 

 only 80 fathoms deep, 

 has its sill so near the 



FIG. ss.-Section of Loch Goil, a typical rock Surface that, although it 



basin, the slopes exaggerated 10 times. The is in free Communication 

 upper line shows by its varying thickness the . , , , . .. . , 



true slope of the bed of the basin. With the SCa at high tide, 



the current rushing out 



at low tide forms a veritable waterfall. Loch Nevis, with a 

 depth of 70 fathoms, has its sill 8 fathoms below the surface. 

 The gigantic Sogne Fjord in Norway, more than 100 miles 

 in length, is a rock-basin with a maximum depth of 700 

 fathoms. 



340. Ice-caps. In very cold climates, where the snow- 

 line approaches sea-level, the whole surface of an extensive 

 region may be covered by snow to such a depth that it is 

 compacted into ice, filling up all the valleys and standing 

 high over the mountains ; such a covering is called an ice- 

 cap. Greenland is covered with an ice-cap presenting a 

 shield-shaped surface, which Dr. Nansen in his adventurous 

 journey across the peninsula in 1888 found to be about 

 10,000 feet above sea-level, and nearly flat in the interior, 

 sloping rapidly to the sea on each side. The weight of this 

 shield of ice is always squeezing out its edges in the form of 

 glaciers to the sea, and there is probably a constant though 

 very slow outward movement of the ice from the centre over 

 the hills and valleys of the deeply buried land. The Ant- 

 arctic continent appears to be covered with a still larger and 

 probably thicker ice-cap, regarding which little information 

 has been obtained, except that the glaciers from it give rise 

 to fleets of immense flat-topped icebergs ( 234, 276). 



REFERENCES 



1 Osborne Reynolds, " On Model Estuaries," British Association 

 Reports, 1889, p. 328, and 1890, p. 512. 



