Horse Spring Formation

Usage of Geologic Unit Name:
Horse Spring Formation*

Oligocene, late*

Horse Springs Formation along the North Shore Road in Lake Mead National Recreation Area.

Geologic Province:
Great Basin province*
Plateau sedimentary province*
Geologic Extent:

Type Locality:
Not designated; named for Horse Spring in the Virgin Mountains, Clark Co, NV (Longwell, 1921). Principal reference section: Longitude 114 36' and 114 37' W; latitude 36 15' 45" and 36 19' 30" N, Muddy Peak 15' quad, Clark Co, NV (Bohannon, 1984)
(ascending) Rainbow Gardens, Thumb, Bitter Ridge Limestone, and Lovell Wash Members
Unit Name History:
Principal reference section and area (Bohannon, 1984). Named (Longwell, 1921). Overview (Longwell, 1928). Age modified (Barnes, 1982). Areal limits (Bohannon, 1983). Divided into Rainbow Gardens, Thumb, Bitter Ridge Limestone, and Lovell Wash Members (Bohannon, 1984). Isotopic dating (Bohannon, 1984). Age modified (Beard, 1993).


Longwell, C.R., 1921, Geology of the Muddy Mountains, Nevada, with a section to the Grand Wash Cliffs in western Arizona: American Journal of Science, 5th series, v. 1, no. 1, p. 39-62.

Longwell, C.R., 1928, Geology of the Muddy Mountains, Nevada, with a section through the Virgin Range to the Grand Wash Cliffs, Arizona: U.S. Geological Survey Bulletin, 798, 152 p., (incl. geologic map, scale 1:250,000).

Barnes, Harley, Ekren, E.B., Rodgers, C.L. and Hedlund, D.C., 1982, Geologic and tectonic maps of the Mercury quadrangle, Nye and Clark Counties, Nevada: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1197, 1 sheet, scale 1:24,000.

Bohannon, R.G., 1983, Mesozoic and Cenozoic tectonic development of the Muddy, North Muddy, and northern Black Mountains, Clark County, Nevada, IN Miller, D.M., Todd, V.R., and Howard, K.E., editors, Tectonic and stratigraphic studies in the eastern Great Basin: Geological Society of America Memoir, 157, p. 125-148.

Bohannon, R.G., 1984, Nonmarine sedimentary rocks of Tertiary age in the Lake Mead region, southeastern Nevada and northwestern Arizona: U.S. Geological Survey Professional Paper, 1259, 72 p., (incl. geologic map, scale approx. 1:790,000).

Beard, S.C., 1993, Tertiary stratigraphy of the south Virgin Mountains, southeast Nevada, and the Grand Wash Trough, northeast Arizona, IN Sherrod, D.R., and Neilson, J.E., editors, Tertiary stratigraphy of the highly extended terranes, California: U.S. Geological Survey Bulletin, 2053, p. 29-32.

Beard, L.S., 1996, Paleogeography of the Horse Spring Formation in relation to the Lake Mead fault system, Virgin Mountains, Nevada and Arizona,in Reconstructing the History of Basin and Range Extension using sedimentology and stratigraphy, Beratan, K.K., ed., Geological Society of America Special Paper 303, p. 27-60.

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Last modified:8/10/2006