One our readers forwarded the link to the Ives' 1857-58 expedition map of the Colorado River. This small picture on the right does not do it justice. Follow the link to an interactive map that you can zoom in on. Note too that this is a shaded relief presentation.
The plate is titled, "Rio Colorado of the West / explored by 1st. Lieut. Joseph C. Ives, Topl. Engrs. under the direction of the Office of Explorations and Surveys, A. A. Humphreys, Capt. Topl. Engrs. in charge, by order of the Hon. John B. Floyd, Secretary of War ; drawn by Frhr. F. W. v. Egloffstein, topographer to the expedition."