Retrogressive thaw slumps are the most active geomor‐phic features of permafrost terrain (NRC 1988). Also called ground‐ice slumps (Mackay 1966), they consist of a layer of ice‐poor overburden, an ice‐rich face and a low‐angle mudflow downslope (figures 1 and 2). They are common along northern rivers and lakeshores and the western Arctic coast. Some have been initiated by terrain disturbance associated with road construction and mineral exploration (Lambert 1972). Insulation of ice‐rich slopes (e.g., using woodchips) may reduce thaw slumping. Initially, this appears to have been successful along the pipeline route from Norman Wells, NWT, to Zama, Alberta. Copyright