2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 1
Presentation Time: 8:00 AM-12:00 PM

IMPACTS OF GLACIER SURGES AND JÖKULHLAUPS AT TWO LARGE TEMPERATE OUTLET GLACIERS: BERING GLACIER, ALASKA AND SKEIÐARÁRJÖKULL, ICELAND


FLEISHER, P.J.1, RUSSELL, A.J.2, BAILEY, P.K.3, NATEL, E.M.4, TWEED, F.S.5 and HARRIS, T.D.5, (1)Earth Sciences, SUNY Oneonta, Oneonta, NY 13820, (2)School of Geography, Univ of Newcastle upon Tyne, Newcastle, NE1 7RU,UK, United Kingdom, (3)Anchor Point, AK 99556, (4)R&D, Eastman Kodak, Rochester, NY 14650, (5)Department of Geography, Staffordshire Univ, College Road, Stoke-on-Trent, Staffordshire, ST4 2DE, UK, United Kingdom, andy.russell@newcastle.ac.uk

Although originating in distinctively different geologic settings, Bering Glacier and Skeiðarárjökull share a remarkably similar history of glacial events, and host unique characteristics uncommon to most other glacial systems. The Bering is the largest surge-type glacier in North America and consists of a 10 km wide main trunk glacier which feeds a 35 km wide piedmont lobe. Skeiðarárjökull exits the Vatnajökull ice cap and expands from a 10-15 km wide upland valley into a 23 km wide lobe which feeds one of the worlds largest active outwash plains. Both glaciers are temperate, occupy over-deepened basins, and are subject to periodic, short-lived, high-pressure jökulhlaups that interrupt or terminate surges, as well as storage-release jökulhlaups. Geomorphological and sedimentological evidence of subglacial and proglacial high-water-pressure events of common genesis are present at both glaciers. These glaciers and associated landform assemblages are of a proper scale to serve as analogues for lower latitude Quaternary ice-masses. Discharge of high pressure, subglacial meltwater created a distinctive suite of landforms and deposits consisting of: (1) sediment-packed, hydro-fracture networks developed in glacier ice and substrate materials, (2) large englacial eskers, (3) large supraglacial, sediment-floored, ice-walled canyons, and (4) ice-contact outwash deposits displaying ice block obstacle marks and kettle-hole pits. Push moraines, extensive areas of subglacial flutes and drumlinoid topography were produced by surge-related ice flow. The development of a series of large proglacial trenches at both glaciers has allowed the development of a peripheral, ice-marginal drainage system during ice retreat. Landform-sediment assemblages at Bering Glacier and Skeiðarárjökull, known to be associated with specific surges and jökulhlaups, provide a model for the interpretation of the sedimentary record of Quaternary ice sheet margins.