Geographical and Topographical Atlas accompanying the report of the Geological Exploration of the Fortieth Parallel, made by authority of the Hornorable Secretary of War, under the direction of Brig. and Bvt. Major General A. A. Humphreys, Chief of Engine

Contains a title, legend, and 11 folio maps in the folio. Contains a topographic (shaded) map of Cordilleran region, limiting meridians 104° and 124°; limiting parallels 29° and 50°. Scale, 60 miles to the inch. Also contains four geologic and four topographic (shaded) maps, on scale of 4 miles to the inch, of the following areas: Sheet I. Longitude, 104° 30'-107° 37'; latitude, 40° 20'-41° 54'. Sheet II. Longitude, 107° 37'-110° 43'; latitude, 40° 16'-41° 50'. Sheet III. Longitude, 110° 43'-113° 50'; latitude, 40° 13'-41° 46'. Sheet IV. Longitude, 113° 50'-116° 56'; latitude, 39° 55'-41° 29'.