| Notes: | Computer generated map.
"Developed from Vaiden and Curry (1990) and U.S. Geological Survey topographic base maps."
"This map was generated using the TIN module of the ARC/INFO software package from bedrock topography maps digitized at 1:62,500 and surface topography maps digitized at 1:24,000. These data are on file at the Illinois State Geological Survey as of June 1989. Locations of some features may be offset by 500 feet or more due to errors in the source maps, the contour generation process, digitizing, or a combination of these factors. The Illinois State Geological Survey does not guarantee the validity of accuracy of these data."
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