Compilers: James S. Aber, John P. Bluemle, Julie Brigham-Grette, Lynda A. Dredge, David J, Sauchyn, and David L. Ackerman

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One sheet, in color, about 48.5" X 35", with 6-page text. From text: An ARC/INFO data base of geographic and glaciotectonic features was constructed for the glaciated portion of North America. The geographic data base consists of multiple coverages that include general geography and topography, continental geology, and glaciation limits. Glaciotectonic features were digitized from 1:250,000 (or 1:500,000) topographic maps for compilation into the continental map. Glaciotectonic features are classified in four main categories: (1) basement faults and seismic zones induced by glacial loading and/or unloading, (2) concealed structures that have no morphologic expression, (3) ice-shoved hills that have constructional morphologic expression, and (4) source basins for material displaced into adjacent ice-shoved hills. Distribution of glaciotectonic features over the continent is related primarily to the presence of thick deformable substrata. Such substrata generally include poorly consolidated Mesozoic and Cenozoic sedimentary rocks as well as unconsolidated Quaternary sediments. Glaciotectonic features are particularly abundant in the northern Great Plains region, where ice sheets advanced upslope over soft substrata. Other major glaciotectonic regions include the Atlantic Coastal Plain of southern New England, Baldwin Peninsula and Kotzebue Sound of northwestern Alaska, and the Yukon Coastal Plain of northwestern Canada. Basement faults and seismic zones are common in areas of hard bedrock, particularly the northern Appalachian region. The local presence or absence of glaciotectonic phenomena may reflect variations in glacier dynamics, land slope, ground-water conditions, proglacial lakes or seas, permafrost, substratum lithology, buried hardrock structures, or such other features that varied geographically or temporally during glaciation.

Published: 4/01/1995

Pages: 6 plus 1 sheet

Product Category: Maps and Charts