1925. Geological Survey (U.S.). Contour interval 10 feet.;"Surveyed in 1923.";Relief shown by contours and spot heights.;1 map, colored;45 x 35 cm.;1:62,500. Geological Survey (U.S.) and Geological Survey Division (Urbana, Ill.).
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1915. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1912.";"Surveyed in cooperation with the State of Illinois.";Relief shown by contours and spot heights.;1 ma... Geological Survey Division (Urbana, Ill.), 1915. and U.S. Geological Survey (Washington, D.C.).