Figure 6. — Tabular iceberg off Scott Island. 



five times tlie exposed hei«j:lit for tlie blockiest bergs, and may be as low 

 as one or two times the heiglit for the pinnacled and irregular types. 



Tabular bergs, the most common type in Antarctic waters, are de- 

 rived by breaking ojff floating portions of the continental ice sheet. 

 Bergs of great size, much larger than any found in the North, may be 

 produced in this way. In January 1927 the whale-catcher Odd I 

 sighted one off Clarence Island which was about 100 miles in length 

 and width and floated about 130 feet out of water. There are nu- 

 merous reports from the Antarctic of bergs 1,000 feet out of water 

 and even higher, but these observations were made from sailing ships 

 and have never been confirmed by a trained scientific observer. Poul- 

 ter measured the average thickness of the floating ice barrier in the 

 Bay of AA^hales as 760 feet with 94 feet out of water, or a draft of seven 

 times the height. He determined that this ice was formed from com- 

 jKicted snow and frost, without glacier material from the highlands. 

 Elsewhere in the Antarctic, neve bergs are encountered with a draft 

 only about twice the height. These are formed at localities like Kob- 

 ertson Bay, where precipitation is at a rate greatly in excess of abla- 

 tion. Where glaciers in the Antarctic lead across a sloping foreland 

 to the sea, irregular bergs like those of the Arctic are produced. 



On a clear day an iceberg can be seen at a great distance, owing to 

 its brilliant luster; during foggy weather it may not be perceptible 



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