CGRG Bibliography of Canadian Geomorphology
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Author : Allard, M.; and Kasper, J.N.
Date : 1998
Title : Temperature conditions for ice-wedge cracking: field measurements from Salluit, Northern Québec
Publication : Permafrost, Seventh International Conference, June 23-27, Yellowknife, Canada. Edited by: A.G. Lewkowicz and M. Allard. Université Laval, Centre d'études nordiques, Collection Nordicana.
Issue : 57:
Page(s) : 5-12.
Abstract
The temperatures at which thermal cracking occurred along ice-wedges around a tundra polygon were measured over two years near Salluit, northern Québec. Electrical cables were buried in the active layer across furrows or cracks in the soil at various places around the polygon. The time of breaking of the electrical cables, and the air, soil surface and ground temperatures down to 2.5 m were monitored with a datalogger. In the course of the two winters, several cables broke with the opening of thermal cracks. Over the two years, the first cracks opened in late December-early January when the temperature at the permafrost table was about -15°C, and after a drop of air temperature from about -20°C to below -32°C. Mean cracking temperature at wedge top was -20°C in the first year and -19.7°C in the second year. The data also allow estimates of the minimum temperature changes and cooling rates required to induce ice-wedge cracking. The cracks closed (or narrowed) and re-opened (or widened) in response to winter temperature fluctuations at the soil surface. The measured thermal conditions for cracking substantiate the previous theoretical work on this basic process at the origin of tundra polygons.
Bibliography of Canadian Geomorphology