294 THE EARTH'S SURFACE AND PLANT LIFE 



ice is not known, but probably in some places is at least 

 several thousand feet. Although along the coast moun- 

 tains rising from 5000 to 8000 feet are not uncommon, 

 yet in the interior the thickness of the ice is so great that 

 no peaks rise above it. 



The surface of the inland ice is a smooth snow plain. 

 Extending from this ice field are huge glaciers having at 

 their ends a thickness of from 1000 to 2000 feet. 



In the Antarctic region an area vastly greater than 

 Greenland is covered with ice probably of a greater thick- 

 ness. Although little is known about this ice cap, it is 



thought by some ex- 

 plorers to be nearly 

 as large as Europe 

 and to rest partly on 

 an Antarctic conti- 

 nent and partly on 

 the sea bottom. 



Icebergs. When 

 a glacier extends out 

 into the sea, the 

 water tends to float 

 the ice. If it ex- 

 tends out into deep 



enough water, the buoyancy of the water will be sufficient 

 to crack the ice, and the end of the glacier will float off as 

 an iceberg. Glacial ice is about eight ninths under water 

 when it floats. 



Icebergs may float for long distances before they melt. 

 In the North Atlantic the steamer routes are changed in 

 the summer months for fear of running into floating bergs. 



AN ICEBERG 



