Geography 2010A/B Study Guide - Quiz Guide: Thermokarst, Landslide, Permafrost

• School: Western University
• Department: Geography
• Course: Geography 2010A/B
• Professor: Mark Moscicki

Document Summary

These processes occur during both diurnal and seasonal freeze-thaw cycles. Diurnal freeze-thaw supports frost creep and small scale movements: annual freeze-thaw is more associated with gelifluction and sliding and leads to larger slope movements. Localized rapid mass movements are common in areas underlain by permafrost, especially in ice-rich unconsolidated sediment. Active layer detachments (ald) are common on higher and middle slope areas. Represent failure and movement of the active layer downslope, usually in a few hours to days. Caused by the reduction of shear strength at the base of the active layer: due to increasing soil water from precipitation or ice melt, the underlying permafrost acts as a lubricated failure plane for the movement. Ald may move a few metres to hundreds of metres and usually have distinctive morphologies. A lower accumulation area occurs where material stops moving and may stack or form extensive deformation zones.