3D MODELING OF GROUND PENETRATING RADAR USED TO CORRELATE FORELAND STRATIGRAPHY, BERING GLACIER, ALASKA

Buried within the foreland of Bering Glacier are Neoglacial tills and forest beds exposed by gully erosion during retreat from the 1995 surge limit. Although well exposed and replete in content, lateral correlation of these units is limited to random exposures that have escaped colluvial accumulation. Ground penetrating radar (GPR) was used in an attempt to trace one such buried till and its associated forest bed. As a control for GPR interpretation, a well exposed stratigraphic section within a distance of decimeters from the GPR grid contains a 10-14 centimeter-thick till at a depth of 2 meters beneath the surface and a forest horizon within glacio-fluvial sands and gravels at 4.5-5 meters depth.

Preliminary GPR data obtained using a 100 MHz antenna in conjunction with signal spacing of 30 cm, with an EKKO 1000 sensor pulse and related software, supports the recognition of these units beneath the recently deglaciated surface. Based on the success of this reconnaissance survey, follow-up field work planned for 2009 will target similar objectives in adjacent portions of the foreland for the purpose of determining the lateral extent of these stratigraphic units.