| 1. |  | Illinois-Iowa, Oquawka quadrangle. | Oquawka (Ill.); Illinois; Maps; Topographic maps; Topography | 1 map : col.; Relief shown by contours and spot heights.; "Surveyed in 1931 and 1934"; "Culture and drainage in part compiled from aerial photographs taken by Air Corps, U.S. Army."; "Contour intervals... |
