ICE IN THE SHORE ZONE AND THE GEOMORPHOLOGY OF COLD COASTS

Approximately 90% of Canada's ocean coastline is affected by seasonal or multiyear sea ice and winter ice develops on most lakes. Recent stu dies of ice effects in the shore zone have included investigations of ice-congested and protected shores in the north-west Canadian Arctic A rchipelago, processes involved in the construction by ice of large sho re ridges in the same region, direct ice scour and enhanced hydrodynam ic scour in the presence of ice (strudel scour and ice wallow), partic ularly as potential hazards to buried pipelines in the Beaufort Sea, a nd the dynamics of boulder-strewn tidal flats and boulder barricades i n eastern Canada. The extent and frequency of shore nourishment by ice and details of the processes involved, including die relative importa nce of ride-up versus pile-up, remain important research questions. Re ports emphasizing the contribution of ice rafting to shoreface retreat along the Alaskan coast of the Beaufort Sea suggest the need for quan titative studies of this phenomenon in Canada, in particular with resp ect to prodelta sedimentation at the mouth of the Mackenzie River. The coastal zone in the Beaufort Sea is particularly sensitive to climate change through effects on thermokarst processes, rising sea level, th e relation between ice cover and wave energy through fetch limitation, and potential changes involving ice dynamics and freeze-up processes.