Near-surface wedges of massive ice commonly outline polygons in tundra lowlands, but such polygons have been difficult to identify on hillslopes because soil movement flattens the ridges and infills the troughs that form beside and above the ice wedges.Over the past three decades, the active layer has thickened near the western Arctic coast of Canada and consequent thawing of ice wedges has been detected by remote sensing for flat terrain but not, generally, on hillslopes. Annual field surveys at the Illisarvik field site of thaw depth and ground surface elevation show the mean subsidence rate above hillslope ice wedges has been up to 32 mm a À1 since thaw depth reached the ice-wedge tops in 2007. Annual mean ground temperatures at the site are about À3.0 C beneath late-winter snow depths characteristic of the ice-wedge troughs but about À5.3 C under conditions of the intervening polygons.The rate of thaw subsidence is high for natural, subaerial disturbances because meltwater from the ice wedges runs off downslope. The rate is constant, because the thickness of seasonally thawed ground above the ice wedges and the ice content of the ground remain the same while the troughs develop. Observations of changes in surface elevation in northern Banks Island between the late 1970s and 2019 show troughs on hillslopes where none was previously visible. Development of these troughs creates regional thermokarst landscapes, distinct from the widely recognized results of thawing relict glacier ice, that are now widespread over Canada's western Arctic coastlands. Recognition of ice-wedge occurrence and accelerated thaw subsidence on hillslopes is important in the design of infrastructure proposed for construction in rolling permafrost terrain.

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Long-term, satellite-tracked iceberg trajectories were analyzed relative to the larger spatial and temporal scales of iceberg drift in Baffin Bay and Davis Strait. Berg movements were concentrated in the core of the Baffin Current which flows along the continental. slope in a primarily southerly direction. The net rate of southward movements was found to be governed by a combination of grounding and landfast ice entrapment which tended to be of particular significance in areas of the coastal shelf adjacent to major submarine canyon systems.

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Illisarvik is a lake basin on Richards Island, NWT, that was experimentally drained in 1978. Surveys were conducted in 2016 at 110 sites within and surrounding the basin to study vegetation succession. These surveys extended previous records provided by L.Ovenden for 1985, 1993, and 2001. The vegetation at Illisarvik indicated a gradual shift towards undisturbed tundra species but was still compositionally distinct in 2016. Early colonizing species were rarely observed in 2016. Grasses and sedges have steadily increased in cover since drainage. Erect willows have become well-established since 1993, and the increased vegetation height has resulted in deeper snow packs. Surveys of other environmental characteristics in the basin indicated that volumetric water content and vegetation height were the primary factors controlling active-layer thickness and ground temperatures at Illisarvik. The vegetation height likely acts as a proxy for the insulating influence of the snow. iii ACKNOWLEDGEMENTS