Notes: | Computer generated map. "This map has been modified as of June 1989 from maps contained in: Wickham, S.S., Johnson, W.H., and Glass, H.D. (1988), Regional geology of the Tiskilwa Till Member, Wedron Formation, northeastern Illinois, Illinois State Geological Survey Circular 543, 35 pp. Locations of some features may be offset by 500 feet or more due to errors in the original data, digitizing, or a combination of these factors. The Illinois State Geological Survey does not guarantee the validity or accuracy of these data."
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