COMBINING GIS AND REMOTE SENSING APPLICATIONS TO MAP THE COMPLEX FIORD SYSTEM THAT UNDERLIES ALASKA'S BERING GLACIER

Bering Glacier, Alaska is the longest and largest glacier in continental North America, with a length of 190 km and an area of ~5,200 km². During the Pleistocene, it was significantly larger and longer, extending at least another 75 km seaward of its present terminus position, cutting Bering Trough, a large u-shaped erosional depression cut nearly 500 m into the seafloor of the Gulf of Alaska. The relationship between the present Bering Glacier and Bering Trough had been assumed, but until recently when GIS and remote sensing technologies were combined, it was not clearly defined. Joining these technologies in order to define this relationship and to understand the bedrock morphology of the glacier and its proglacial environment has revealed that a complex fiord system underlies much of the southern part of Bering Glacier, its ice-marginal lake, its coastal foreland, and much of the adjacent Gulf of Alaska continental shelf. Remotely sensed data were needed to define the extent, morphology, depth, and relationship between the individual components of the fiord system: subglacial, sub-ice-marginal-lake, sub-coastal-foreland, and continental shelf. The remotely sensed data were produced by five complimentary geophysical investigations: ice-surface radio-echo sounding and airborne monopulse radar profiling to define the subglacial portion of the fiord; high-resolution mini-sparker seismic reflection profiling to define the morphology of the fiord underlying the proglacial ice-marginal lake; binary-explosive seismic refraction profiling to confirm the presence of the fiord underlying the Bering Foreland coastal plain; and marine air-gun and sparker seismic profiling to define the bedrock morphology of offshore Bering Trough. The data from each investigation were fed into several GIS analytical programs to produce TINs, contour maps, and scaled cross-sectional profiles for each component. Finally, the results of all five investigations were compiled and combined using several GIS approaches and mapped to a geo-rectified Landsat image base to produce a properly scaled visualization of the entire, complex, ~125-km-long fiord system that underlies much of the southern part of Bering Glacier and its adjacent proglacial areas. This presentation describes the process involved in producing the final map.