Permafrost Development in the Intertidal Zone at Churchill, Manitoba: A Possible Mechanism for Accelerated Beach Lift


  • Roger I.C. Hansell
  • Peter A. Scott
  • Richard Staniforth
  • Josef Svoboda



Coast changes, Intertidal zones, Permafrost beneath oceans, Beech Bay region, Manitoba, Churchill region, Hudson Bay


Boreholes drilled in the Beech Bay area during July to November 1929 indicated that a sill of permafrost had extended below the high-water line, tapering in depth towards low water. The boreholes revealed thick layers of fine sediments on top of deep underlain bedrock. Recent borings determined the upper limits of permafrost in 1981. Examination of the data shows that there has been a permafrost expansion into the emerging tidal zone. These observations suggest an additional mechanism for accelerated uplift of coastal exposed "soft" sediments: the vertical expansion of refrozen, water-saturated silts and clays as new permafrost forms. The existing rates of isostatic uplift are enhanced by the process.

Key words: permafrost, active zone, isostatic uplift, Breech Bay, Churchill, Hudson Bay