tag:digital.library.illinois.edu,2005:/itemsItems2022-09-15T18:31:22Ztag:digital.library.illinois.edu,2005:Item/668222016-11-15T17:24:28Z2022-09-15T18:31:22ZErie quadrangle, Illinois : 15 minute seriesRelief shown by contours and spot heights.University of Illinois at Urbana-Champaign Library