Submitted on: 10 September 2006.
Revised on: 01 October 2006.
Accepted on: 27 October 2006.
___________________JOURNAL OF GLACIOLOGY---CAMBRIDGE UNIV PRESS
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Submitted on: 25 October 2006.
Revised on: 16 December 2006.
Accepted on: 09 January 2007.
___________________JOURNAL OF GLACIOLOGY---CAMBRIDGE UNIV PRESS
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