The 1870s was a period of intense effort, by such prominent people as Clarence King, Ferdinand Hayden, and John Wesley Powell, to advance the geographical knowledge of the West. These various surveys presented a threat to the Army's supremacy in the field of mapping and to the related appropriations from Congress. As a result of these pressures, the Army Corp of Engineers developed a plan to systematically survey the entire West to be called the U.S. Geographical Surveys West of the One Hundredth Meridian. The region was divided up into 95 rectangles, with atlas sheets to be prepared for each, comprising an area 2°45' of longitude and 1°40' of latitude on a scale of eight miles to the inch. Lieutenant George Wheeler was chosen to head this immense project. Surveys were conducted each summer from 1872 to 1878, after which Congress cut off appropriations for field work; thus the survey was not completed as originally envisioned. Wheeler published annual reports from 1873 to 1884, as well as the final Geographical Report published in 1889. The maps from this report are a valuable document of the record of Western exploration.

This is the complete Volume III (Supplement - Geology) of Wheeler's Survey dated 1881. This scarce volume contains the first detailed mapping of the region from Trinidad, Colorado to Los Alamos, New Mexico. Included are three maps with both topographical and geological information: Parts of Southern Colorado and Northern New Mexico, No. 70A; Part of North Central New Mexico, No. 70C; Parts of Atlas Sheets No. 69B, 69D, 77B and 78A. Each of the maps shows different geological strata in vibrant color that are overlaid on top of relief shown in hachure. In addition to the maps are 4 plates showing geology and fossils along with an accompanying 420-page report (10 x 12"). Hardbound in original brown cloth and gilt title on spine.

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Condition: B+

Maps are brightly colored with just a hint of toning along one fold. Text is clean with light uniform toning. Hinges are starting and the covers and spine show moderate shelf wear.