Marine record of surge-induced outburst floods from the Bering Glacier, Alaska

Abstract

The Bering Glacier, Alaska, is the largest temperate glacier in the world. It episodically surges with rapid advances of the glacier terminus followed by large outburst floods delivering freshwater and sediment to the adjacent Gulf of Alaska. We describe the marine record of the 1993–1995 surge and document a 100 yr history of surges recorded in marine sedimentary deposits seaward of the Bering Glacier. In 1994 and 1995, we collected box cores that contained high-porosity laminated sediments at the seabed surface. Profiles of 234 Th and chlorophyll-a indicate that these sediments were deposited very rapidly (0.1 cmṁday −1 ) in association with the surge. A 250-cm-long kasten core extended this record, in which 7 laminated beds, 10–30 cm thick, alternated with bioturbated sediments. On the basis of 210 Pb chronology, 6 of these beds accumulated in the past 100 yr and can be correlated with historical surges.