Distribution of Surging Glaciers in Western North America

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Abstract
In western North America 204 surging glaciers have been identified by aerial photographic observations. These glaciers exhibit either intense crevassing and rapid ice displacements during surges or distinctive surface features which have resulted from past surges. Distribution of these unusual glaciers is not random throughout the glacierized areas, as they occur only in the Alaska Range, eastern Wrangell Mountains, eastern Chugach Mountains, Icefield Ranges, and the St Elias Mountains near Yakutat and Glacier Bay. No surging glaciers have been identified in the Brooks Range, Kenai Mountains, west and central Chugach Mountains, west and central Wrangell Mountains, Coast Mountains, Rocky Mountains, Cascade Range, Olympic Mountains, or Sierra Nevada. No definite reason for this restricted distribution is apparent. Surging glaciers are found in maritime to continental and temperate to subpolar environments. Practically all physical forms of glaciers are represented. The restricted distribution does not relate to topography, bedrock type, altitude, orientation, or size of glacier. Some surging glaciers are associated with fault-related valleys, but neither recent faulting nor earthquakes have initiated surge activity. Possible causes for the limited distribution of surges are unusual bedrock roughness or permeability in certain areas, anomalously high ground-water temperatures, and/or abnormal geothermal heat flow.