| 1. |  | Illinois, Prophetstown quadrangle. | Prophetstown (Ill.); Illinois; Maps; Topographic maps; Topography | 1 map : col.; Relief shown by contours and spot heights.; "Culture and drainage in part compiled from aerial photographs taken by Air Corps, U.S. Army"; "Surveyed in 1928 and 1931-1932"; "Contour interval... |
