At head of title: U.S. Miss. Delta Survey. Plate 1. Relief shown by hachures. "Note. This map is mainly reduced from the official map, compiled in the Office of Explorations to exhibit Pacific Rail Road Routes, War Dept., and from Colton's Maps of the several States ... Red figures denote annual downfall of rain ..." "Prepared to accompany the report of Capt. A.A. Humphreys and Lieut. H.L. Abbot, Corps of Top'l. Eng'rs. U.S.A. to the Bureau of Topl. Engrs., War Dept."