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FIRST YEAR SCIENCE 



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. Some of the most appalling disasters of 

 the sea have been due to ships colliding with icebergs. 

 As the berg melts, the rocks and gravel or whatever it 



BOWLDERS AND SAND LEFT BY A RETREATING GLACIER. 



may have upon it drop into the sea, so that the waste 

 brought down to the sea by the glacier may be spread over 

 the sea bottom far away from the place where it origi- 

 nated. Much of the knowledge of the geology of the 

 Antarctic continent has been gained from the bowlders 

 dredged up at sea. 



Although icebergs in the northern seas are sometimes 

 very large, those in the Antarctic region are vastly larger. 

 They have been seen extending above the water 200 or 



