68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

SUBDIVISION OF ICE-WEDGE POLYGONS, WESTERN ARCTIC COAST

Session: John Ross MacKay Symposium - Permafrost III / Symposium John Ross MacKay - Pergélisol III

Christopher Burn, Carleton University (Canada)
Brendan O'Neill, Carleton University (Canada)

Ice-wedge polygons are characteristic features of unconsolidated sediments in the continuous permafrost zone. They commonly have a well-defined surface expression in lowland basins, but are also ubiquitous on hill slopes. The polygons are outlined by a network of primary ice wedges, in places subdivided by secondary wedges, and even tertiary features. The evolution of ice-wedge networks was thought to be the result of winter climate variation. Three sets of observations suggest that, instead, the development of secondary and tertiary wedges may be due to growth of the primary ridges and troughs influencing snow depth. (1) J.R. Mackay showed that smaller, secondary wedges may crack more frequently than primary wedges. (2) Hill slope polygons are not characteristically subdivided by secondary ice wedges. (3) Thermal contraction cracks expand over winter, responding to cooling of the ground as the season progresses.