Soller, D.R., 1998, Map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains - northern Great Lakes states and central Mississippi Valley states, the Great Lakes, and southern Ontario (80 degrees 31' to 93 degrees west longitude): U.S. Geological Survey, Miscellaneous Geologic Investigations Map I-1970-B, scale 1:1,000,000