GEO-REFERENCED CONTROL OF STRATIGRAPHIC ASSOCIATIONS, EASTERN SECTOR, BERING GLACIER, ALASKA

Two kilometers of retreat from the 1995 surge limit has exposed multiple stratigraphic sections of foreland tills, stratified drift, and stable organic horizons represented by peat layers and buried forests on Weeping Peat, Peat Falls, Bentwood, and Arrowhead Islands. Dozens of GPS control points obtained in the field and located on exceptionally high-resolution aerial photography provide geo-referenced control (+/- 3 m) for mapping physiographic features and stratigraphic section locations. This comprehensive database is developed for stratigraphic interpretation and paleo-topographic reconstruction.

Lateral stratigraphic correlation is based on relative elevation above lakes and connecting channels (all graded to Vitus Lake), physical stratigraphic criteria, peat layers, and buried forest sequences. Confirmation awaits radiocarbon dates.

The typical stratigraphic sequence (from the bottom up) consists of a sand and gravel outwash in which rooted mature trees are held in the growth position by 2 m of lacustrine sand deposited when the forests were flooded. Trees were sheared by the Neoglacial passage of overriding ice that deposited a thin till (15-20 cm) and/or isolated, angular ablation boulders, upon which is several meters of proximal outwash, which is in turn covered by a veneer of thin deformation till (15 -20 cm) emplaced during the 1993-95 surge. Nowhere on the entire eastern sector is bedrock exposed beneath foreland drift.