Contour interval 20 feet.;"Surveyed in 1917.";"Surveyed in cooperation with the War Department and the State of Illinois.";Relief shown by contours and spot heights.;1 map, colored;45 x 34 cm.;1:62,500
Creator:
Geological Survey (U.S.)
Publisher:
Geological Survey (U.S.)|Geological Survey Division (Urbana, Ill.)|War Dept., Corps of Engineers, U.S. Army (U.S.)