A. Gray's Geological Map of the United States, circa 1873, hand color (26.8 x 16.4"). Very striking and graphic map that details the geological composition the United States. Nine geological types are shown in different hand color. Locates Eozoic, Silurian, Devonian and Lower Carboniferous, Coal Measures and Permo-Carboniferous, Triassic and Jurassic, Cretaceous, Tertiary, Alluvium, and Volcanic. Includes political boundaries, major cities and watersheds. The map is based on Hitchcock’s map for the American Institute of Mining and was published by O.W. Gray and Son of Philadelphia. Condition: A colorful example with a centerfold separation that extends 0.5" into the image at bottom that has been closed on verso with tape.

B. Geological Map of the United States, from Statistical Atlas of the United States…Ninth Census, 1870, dated 1874, printed color (28.5 x 19.8"). This large and very colorful thematic map is the third edition of a map first issued in 1872. The map identifies forts, watershed, major towns and more. The legend at lower left provides an explanatory key to the colors used to indicate nine distinct geological types, e.g. Eozoic, Cambrian, Devonian, Triassic, Cretaceous, Tertiary, Volcanics, etc. The carefully drawn map shows good geographical detail as well as remarkable geological information conveyed in strongly applied color. The geography of the map is from the War Department's "Military Map of the United States," used by permission of the Chief of Engineers. Reference: Marcou & Marcou #70; Phillips (A) #1330. Condition: Clean and colorful with very faint color offsetting.

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Condition: B+

See description above.