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, describes field operations in the region and identifies occupied areas with triangles and located peaks with circles. 718 pp. Hardbound in brown cloth with gilt title on spine.

References: Wheat (TMW) #1239.

Condition: B+

Maps and plates are in very good condition; the <i>Central Colorado</i> map has just a hint of toning and a 1.5" binding tear. One of the folding maps, <i>Sketch; Showing the Primary and Secondary, Triangulation of 1873,</i> is detached. Front hinge is starting. The covers have light shelf wear and the corners are slightly bumped.