tag:digital.library.illinois.edu,2005:/items/a4813420-994e-0134-2096-0050569601ca-8Illinois-Iowa, Keithsburg quadrangle2022-09-15T18:31:54Ztag:digital.library.illinois.edu,2005:Item/700612016-11-30T19:20:07Z2022-09-15T18:31:54ZIllinois-Iowa, Keithsburg quadrangleContour intervals 10 and 20 feet changing on the 580 foot contour.University of Illinois at Urbana-Champaign Library