Massive ground ice cores many hills of the coastal lowlands near the mouth of the Mackenzie River. The ice, when exposed by landslide or coastal erosion, often shows plastic deformation typical of creep movement. The stability of these ice-cored hill slopes is of particular concern for hazard studies, engineering design and for assessing terrain impacts of global change. Creep is important in the evolution of these distinctive hills and its surface expression is an indication of significant massive ice. The process may promote exposure of ice at over steepened margins leading to retrogressive slope failure. Creep is temperature dependent so climate change or other thermal disturbance will result in an altered rate of the geomorphic process.

Field studies of in-situ creep of permafrost slopes have been limited, in part because of the cost of field installations and the long monitoring period required to accurately measure creep rates. Involuted Hill, located approximately 15 km east of the village of Tuktoyaktuk, is one of these ice-cored hills that has been intensely studied in the subsurface by drilling and geophysics over the past 25 years. Because of the detailed knowledge of the ice body at the site it was selected by the GSC for a monitoring program to detect and measure the process of deep-seated creep and its relationship to landform development and land use in a dynamic and sensitive environment.

Two 35 m boreholes were continuously cored for stratigraphic, petrographic and geochemical information. Special casing was installed to allow repeated access with an instrument that measures tilt at close intervals. These measurements and temperature monitoring have been obtained in late winter and summer, and at other opportunities, since the late 1980s.

The record from the borehole near the interior of the hill (IH88-1) shows simple downslope deformation within the base of the ice body analogous to gravity induced creep in glacial ice. This deformation has successfully been modelled by colleagues at l'École Polytechnique de Montréal. In contrast the record from the edge of the hill (IH88-2) is complex, showing several levels of deformation in the upper half of the section and significant subsidiary seasonal upslope movement even at depth.