1970. Geological Survey (U.S.). Spatial references;Sectional grid;Roads, waterways, major public works, railroads, land and cultural features;Relief shown by contours and spot hei... State Geological Survey Division (Urbana, Ill.) and Geological Survey (U.S.).
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1906. Geological Survey (U.S.). Contour interval 10 feet.;"Surveyed in 1905.";"Surveyed in cooperation with the State of Illinois.";Includes "diagram of township.";Relief indicate... Geological Survey (U.S.) and Geological Survey Division (Urbana, Ill.).