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ALASKA PALEOGLACIER ATLAS
Three decades after the last Alaska-wide compilations of glacial geology (Karlstrom et al., 1964; Coulter et al., 1965), we have coordinated a broadly collaborative effort to create a digital map of reconstructed Pleistocene glaciers. Our goal is a comprehensive and consistent overview of former glacier limits across Alaska, with emphasis on Pleistocene maximum and late Wisconsin (LGM) extents. The geospatial database is targeted for a scale of 1:1,000,000 -- suitable for visualization and regional analyses. The atlas is now available online at http://instaar.colorado.edu/QGISL/ak_paleoglacier_atlas, and includes layers for Geographic Information Systems (GIS), as well as images and documentation.
A first draft was created by digitizing the statewide map of Coulter et al. (1965). Polygons delineating paleoglaciers were then modified to incorporate decades of glacial-geologic research (see Hamilton, 1994). This draft was updated after community review to include contributors' unpublished maps and information. In all, the first version integrates information from 15 publications and 38 source maps. We encourage further contributions to this evolving resource. Modern glaciers were added from ESRI's Digital Chart of the World.
The digital atlas depicts glaciers that once covered >1,200,000 km2, from the continental shelf bordering the North Pacific to the northern foothills of the Brooks Range. Late Wisconsin glaciers occupied 727,800 km2 -- only 48% of the state but nearly ten times the area of modern glaciers. A companion paper (Kaufman and Manley, subm.; part of an INQUA effort for a global atlas with regional reviews) summarizes the glacial-geologic evidence and highlights recent revisions, remaining uncertainties, and implications for paleoclimate forcing.