112 



PHYSIOGRAPHY 



The area of Greenland has been variously estimated at from 

 400,000 to 600,000 square miles, and all except its borders is buried 

 beneath one vast field of ice and snow. Except on a narrow border 

 of a mile or so at the edge of the ice-sheet, not even a bowlder or a 

 pebble relieves the great expanse of white. 



The thickness of the Greenland ice is not known, but where 

 thickest, it is probably thousands of feet. Near its margin the 

 ice is much crevassed, but the interior is comparatively smooth 

 so far as now known. The ice of this great field is creeping slowly 

 outward. The rate of movement has never been measured, and 

 is probably not the same at all points, but it has been estimated 

 not to exceed a foot a week. This ice-cap is, in one sense, more of 

 a desert than the Sahara, since it is inhabited even less than that 

 desert by plants and animals. 



Where the edge of the Greenland ice-cap lies a few miles back 

 from the coast, the rock plateau outside it has numerous valleys 

 leading down to the sea. Where the edge of the ice-cap reaches 



Fig. 114. An iceberg. 



the heads of these valleys, ice moves down them, making valley 

 glaciers. Many of them reach the sea where their ends are broken 

 off and floated away as icebergs. This is the source of most of the 

 bergs (Fig. 114) seen by the steamers which cross the North Atlantic. 

 Some of them are so large that they float far to the south before they 

 are melted. While the number of valley glaciers in Greenland is 



