Late cenozoic geology of Mississippi Valley: southeastern Iowa to central Louisiana, June 12, 1949 to June 25, 1949; itinerary of field conference/ assembled by M.M. Leighton and H.B. Willman.- Urbana, IL.- getr. Pag.: Ill.; 51 Kt - Leighton, Morris M; Willman, H. B (1949)