tag:digital.library.illinois.edu,2005:/items/a7249f10-994e-0134-2096-0050569601ca-6Illinois-Iowa-Missouri, Keokuk quadrangle2022-09-15T18:31:56Ztag:digital.library.illinois.edu,2005:Item/700892016-11-30T19:20:15Z2022-09-15T18:31:56ZIllinois-Iowa-Missouri, Keokuk quadrangleContour intervals 10 and 20 feet changing on the 500 foot contour.University of Illinois at Urbana-Champaign Library