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Keywords:

  • frost weathering;
  • frost cycles;
  • ice segregation;
  • bidirectional freezing;
  • rockfalls;
  • permafrost thawing

Abstract

This paper reviews frost-weathering studies in the last five years and proposes key questions to be answered. New techniques have enabled us to monitor moisture contents and crack movements in near-surface hard jointed bedrock and to evaluate seasonal rockfall activity in high mountains. Field monitoring has highlighted the roles of diurnal and annual frost cycles in controlling the timing and magnitude of frost weathering. In the laboratory, bidirectional freezing in soft, porous rocks has produced fractures containing segregated ice layers near the permafrost table, which imply the development of ice-filled fractures in permafrost bedrock over long time-scales. This finding, combined with numerical modelling of the thermal regime in permafrost rock slopes, contributes to the prediction of large-scale rockfalls and rock avalanches triggered by permafrost degradation. Future studies should also focus on explosive shattering, frost weathering of hard-intact rocks, field monitoring of ice segregation and bedrock heave, and the role of frost weathering in landscape evolution. Copyright © 2008 John Wiley & Sons, Ltd.