ANTARCTIC ADVENTURE AND RESEARCH 



of the berg, and so it had taken up a new position by 

 September. The old water Hne on the berg is usually 

 indicated by a smooth concavity cut by the waters under 

 the surrounding pack ice. 



No bergs seen in the Arctic rival those of Antarctic 

 seas in size. On the last voyage of the ''Terra Nova" 

 in January, 1913, Captain Pennell passed close to a 

 berg twenty-one miles long (in latitude 64° 15' S.). 

 But perhaps the largest recently seen was that meas- 

 ured by Mawson in 191 2 off the Mertz Glacier, which 

 appears to have been forty miles long. It was seen 

 again next year about fifty miles to the northwest of 

 the glacier. Most of the bergs are formed of ''cloudy 

 bubbly ice" (in Priestley's phrase) of which the typical 

 ice tongues are formed. The ice is, however, often 

 stratified showing its origin as snow in the distant past. 

 But sometimes true bergs formed of neve were seen. 

 Here the ice consists of loosely coherent grains, each 

 about one-sixth of an inch in diameter, with much air 

 between. 



Priestley has classified icebergs into the following 

 groups : 



(a) Tabular bergs, derived from ice shelf or tongue 



(b) Glacier bergs, irregular, broken by crevasses 



(c) Unconformity bergs, partly blue ice, partly neve 



(d) Ice Island bergs, domed bergs easily mistaken for 



islands 

 {e) Neve bergs, from regions of unusually heavy snowfall 

 (/) Weathered bergs, overturned, irregular and of ob- 

 scure origin 



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