The Geological Exploration of the Fortieth Parallel was a geological survey made by order of the Secretary of War according to acts of Congress of March 2,1867, and March 3, 1869, under the direction of Brig. and Bvt. Major General A. A. Humphreys

Andrew A. Humphreys

Andrew Atkinson Humphreys , was a career United States Army officer, civil engineer, and a Union General in the American Civil War. He served in senior positions in the Army of the Potomac, including division command, chief of staff, and corps command, and was Chief Engineer of the U.S...

, Chief of Engineers, by Clarence King

Clarence King

Clarence R. King was an American geologist, mountaineer, and art critic. First director of the United States Geological Survey, from 1879 to 1881, King was noted for his exploration of the Sierra Nevada. He was born in Newport, Rhode Island.-Career:...

, U. S. geologist. More commonly known as the Fortieth Parallel Survey, the survey conducted six years of field work exploring area along the fortieth parallel north

40th parallel north

The 40th parallel north is a circle of latitude that is 40 degrees north of the Earth's equatorial plane. It crosses Europe, the Mediterranean Sea, Asia, the Pacific Ocean, North America, and the Atlantic Ocean....

 from western Nevada

Nevada

Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

 to eastern Wyoming

Wyoming

Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

.

Results

The results of the survey were published in eight volumes of the Fortieth Parallel Survey:

• Vol. I. Systematic geology, by Clarence King, U. S. Geologist. 1878. xii, 803 pp., and atlas of 12 sheets.
• Vol. II. Descriptive geology, by Arnold Hague and S. F. Emrnons. 1877. xiii, 890 pp.
• Vol. III. Mining industry, by James D. Hague, with geological contributions by Clarence King. 1870. xv, 647 pp. and atlas of 14 sheets.
• Vol. IV. Part I, Palaeontology. by F. B. Meek. Part II, Palaeontology, by James Hall and R. P. Whitfield. Part III, Ornithology, by Robert Ridgway. 1877. xii, 669 pp.
• Vol. V. Botany, by Sereno Watson, aided by Prof. Daniel C. Eaton and others. 1871. liii, 525 pp.
• Vol. VI. Microscopical petrography, by Ferdinand Zirkel. 1876. xv, 297 pp.
• Vol. VII. Odontornithes: A monograph on the extinct toothed birds of North America, by Othuiel Charles Marsh. 1880. xv, 201 pp.
• Special Publication: List of plants collected in Nevada and Utah, 1867-69; numbered as distributed. Sereno Watson, collector.

Atlases:

• Atlas accompanying the report of the Geological Exploration of the Fortieth Parallel. by Clarence King, U. S. geologist-in-charge. 1876. Julius Bien, Lithographer. Folio, 2 11., (title and legend), 1 single and 11 double folio sheets (1 single folio map, 10 double folio maps, 1 double folio section).
• Atlas accompanying Volume III on mining industry. [List of plates.] Engraved and printed by Julius Bien, New York. Folio, 11. (title page), 14 plates.

Additional Sources

• USGS Historical Photography Library - Collection of photographs from the 40th Parallel Survey.