Cryostatic pressures in nonsorted circles (mud hummocks), Inuvik, Northwest Territories

Abstract

Experiments were carried out during the 1967–1972 period in an attempt to measure cryostatic (frost-induced) pressures by means of soil pressure cells installed in nonsorted circles (mud hummocks) at Inuvik, N.W.T. Although slight soil pressure increases were measured in the hummocks during the freeze-back period, the field evidence shows that the hummock centers became desiccated, overconsolidated, and immobile rather than saturated, underconsolidated, and mobile, because of water loss to growing ice lenses at the top and bottom of the active layer. Cryostatic pressures during the freeze-back period are considered to be no more important than thaw displacement in the summer. The Inuvik mud hummocks appear to maintain considerable stability and individual identity over a time span of hundreds of years.