Distribution of Surging Glaciers in Western North America

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.

Late nineteenth to early twenty-first century behavior of Alaskan glaciers as indicators of changing regional climate

“…It is also a surging glacier (Post, 1960(Post, , 1969. Post (1960), who described the 1956-1957 surge, reported that an analysis of moraine patterns on the glacier's surface suggests that at least four prior surges occurred within the past several hundred years, with the most recent pre-1956 surge occurring between 1906 A.D. and 1912.…”

“…Most glaciers in the regions that support surging glaciers do not surge. Post (1969) noted only 205 surging glaciers out of several thousand western North American glaciers that he examined. About 75% of these were in Alaska.…”

“…Glacier surges have been observed in many parts of the world, but the greatest concentration of surging glaciers is in western North America, especially in the St. Elias Mountains, eastern Chugach, Mountains, eastern Wrangell Mountains, parts of the Alaska Range, and in the Icefield Ranges adjacent to the U.S.-Canada border (Post, 1969). Most glaciers in the regions that support surging glaciers do not surge.…”

“…The terms "galloping glacier" and "runaway glacier" were widely used to report this occurrence. Post (1969) offers the following definition for a surging glacier; one which periodically (15-100+ years) discharges an ice reservoir by means of a sudden, brief, large-scale ice displacement, which moves 10 to 100 or more times faster than the glacier's normal flow rate between surges. Post continues, Glacier surges are not unique events which might result from exceptional conditions such as earthquakes, avalanches, or local increases in snow accumulation.…”

Formation and reorientation of structure in the surge‐type glacier Kongsvegen, Svalbard

“…Surge-type glaciers oscillate between short periods of extremely rapid movement and long periods of relative inactivity or quiescence (Post, 1969). Studies of glaciers during surge suggest that fast flow is associated with basal conditions (Clarke et al, 1984;Kamb et al, 1985;Raymond, 1987;Fowler 1987).…”