Ice wedges on hillslopes and landform evolution in the late Quaternary, western Arctic coast, Canada

Abstract

In rolling to hilly areas of the western Arctic coast of Canada, anti-syngenetic wedges, which by definition are those that grow on denudational slopes, are the most abundant type of ice wedge. Through prolonged slope denudation, hilltop epigenetic wedges can evolve into hillslope anti-syngenetic wedges, and some bottom-slope anti-syngenetic wedges, by means of deposition from upslope, can evolve into bottom-slope syngenetic wedges. The axis of a hillslope wedge is oriented perpendicular to the slope, so the wedge foliation varies according to the trend of the wedge with respect to the slope. Because the tops of hillslope wedges are truncated by slope recession, the mean chronological age of anti-syngenetic wedge ice decreases with time, so the growth record for an old wedge is incomplete. Summer and winter measurements show that a thermally induced net movement of the active layer of hillslope polygons tends to transport material from their centres towards their troughs independent of the trends of the troughs relative to the slope. Wedge-ice uplift, probably diapiric, has been measured. Some hillslope polygon patterns may predate the development of the present topography. Many Wisconsinan wedges, truncated and buried during the Hypsithermal period, have been reactivated by upward cracking.