HOLOCENE HISTORY OF BERING GLACIER, ALASKA: A PRELUDE TO THE 1993–1994 SURGE

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Abstract
Within the last few centuries, Bering Glacier, the largest and longest glacier in continental North America, began to retreat from its Neoglacial maximum position. This position also represents the Holocene maximum extent of the glacier. For much of the period between 8000 yr B.P. and about 1500 yr B.P., the Bering Glacier was in a retracted position, although a readvance may have occurred about 5000 yr B.P. A major readvance began about 1500 yr B.P., culminating with the glacier reaching its Holocene maximum extent between 1000 and 500 years ago. During the last millennium, the glacier margin fluctuated near this maximum position, only beginning to retreat within the last 100–200 years. This century, the recession from the Neoglacial maximum position has been interrupted by at least six surges that have displaced parts of the glacier's terminus forward. Prior to the latest surge, beginning in 1993, retreat resulted in the net loss of more than 130 km2 of glacier in the terminus region, as much as 12 km of ice-marginal retreat from the Neoglacial end moraine, and as much as 180 m of glacier thinning. Stagnation, continued thinning, and the resumption of recession follow the completion of each surge. Following the end of the last complete surge in 1967, parts of the glacier entered a phase of drastic retreat, receding as much as 10.7 km. As with past retreat phases, this rapid retreat has been interrupted by the surge that began in 1993.