This is the Seventh Report from the seminal Hayden survey, covering Colorado. The work is divided into four main parts: Geology, Mineralogy, and Mining Industry; Special Reports on Paleontology; Zoology; and Geography and Topography. There are two appendices, one by Arch. R. Marvine focusing on the Gold Hill Mining Region, and the other by B. Silliman describing the Telluride ores. There are 11 maps, 7 of them folding, and copious illustrations throughout the text, including 10 folding plates. Wheat cites one map, Preliminary Map of Central Colorado Showing the Region Surveyed in 1873 (17.2 x 22.8"), as evidence that Hayden and his survey "were becoming much more knowledgeable about map construction" in the lead-up to his lauded Atlas of Colorado (1877). The map, with primary triangulation by J.T. Gardner and topography by G.R. Bechler, Henry Gannett, and A.D. Wilson, depicts field operations in the region and identifies occupied areas with triangles and located peaks with circles. 718 pages. Hardbound in brown cloth with gilt title on spine.

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Condition: B+

Contents are clean with even light toning. The triangulation map has an edge tear at right that extends 1.5" into the image that has been closed on verso with archival tape. There is also a 3.5" tear to one of the geological sections. Rear hinge is starting. Covers are lightly worn with bumped corners.