Upward movement of the ground surface or of individual particles, due to the formation of lenses of ice up to 30 mm thick in the regolith. It reaches its maximum in silt-dominated material, in which the greatest volume of ice may develop (more than 68% ice by volume). When the total uplift of the surface is measured, it is found to be approximately equal to the sum of the thicknesses of the layers of ice. Surface stones may be heaved by the development of needle-ice columns (‘pipkrakes’).
Subjects: Earth Sciences and Geography.