This important report was produced in 1860 but not issued until 1876 due to the Civil War. Included is the very rare Map of Explorations and Surveys in New Mexico and Utah… (34 x 28.5"), which is considered by Wheat to be a landmark in the mapping of the region and "one of the most beautiful maps every published by the Army." According to Wheat there are several reasons for its importance. First, it is the first to show a trail to the junction of the Green and Grand Rivers. Second, he praises the map for its depiction of numerous routes of other explorers. Finally, it demonstrates the culmination of the process developed by Egloffstein to convey the idea of altitude. The process used a combination of extremely fine lines and applying acid to the plate for varying times, thus giving the map a remarkable 3-dimensional realism unmatched in the period. It is also the first to correctly establish the relationship between the San Juan and Colorado Rivers. The map covers Arizona, Utah, New Mexico and about 30% of Colorado.

This highly sought after report is complete with eleven black and white engravings and eleven chromolithograph prints, and also features "Descriptions of the Cretaceous fossils collected on the San Juan Exploring Expedition under Capt. J. N. Macomb, U.S. Engineers." by F. B. Meek. 4to. Complete. Hardbound in brown cloth with gilt title on spine.

References: Wheat (TMW) #983.

Condition: B

There are a number of fold separations and splits at fold intersections, some of which have been repaired on verso with archival material, including a clean 5" fold separation crossing the title that has not been closed. There is some light toning along folds, minor offsetting, and a few small spots. Text and plates are very good with some light toning and occasional small spots. The covers and spine are worn with the front cover loose and almost detached. The binding is almost perished with some pages separated from text block.