HOLOCENE STRATIGRAPHY AND OUTBURST DEPOSITS, EASTERN SECTOR, BERING GLACIER FORELAND, ALASKA

Bering Glacier, Alaska, fronts on a 30 km foreland of lakes and islands. The stratigraphic record exposed in bluffs on Weeping Peat Island (1 km²) is characterized by units depicting Late Holocene events. A surface till (1 - 5 m) mantles most of the island and covers a diamicton up to 4 m thick, below which is a 15 m sequence of well stratified outwash sand and gravel. Spatial distribution and prevailing occurrence of coarse gravel indicate proximal accumulation. Contacts within the outwash are generally distinct, although subtle unconformable relationships may be obscured by normal cut-and-fill structures. Up to four, well sorted, flood sand sheets may be found below the diamicton within the outwash. Each contains basal organic horizons in which small trees are rooted. Buried in the growth position by sand, these trees have been bent and sheared in a manner suggestive of deformation by overriding ice. The till above is thought to have been deposited during the 1965-67 surge, which may have also deformed the substrate, thus generating the diamicton and distorting the trees. Subglacial outbursts at the close of the 1993-95 surge significantly altered the surface of Weeping Peat Island and portions of adjacent lake basins, initially by erosion followed by sandar formation. Data from small-scale sandar landforms and outburst gravel are used to estimate lower-limit paleo-discharge (~1,300 m³) across Splitlake Sandur on Weeping Peat Island and in the formation of Icewall Sandur in the adjacent Tsivat Lake basin.