Phosphoria Formation

Usage of Geologic Unit Name:
Phosphoria Formation (ID*,MT*,NV*,UT*,WY*)
Permian, Early*
Geologic Province:
Idaho Mountains province*
Montana folded belt province*
Powder River basin
Wasatch uplift*
Snake River basin*
Denver basin
Green River basin*
Wind River basin*
Great Basin province*
Areal Extent:

Type Locality:
Not designated, but section measured in sec. 12, T. 10 S., R. 44 E., and in sec. 7, T. 10 S., R. 45 E, Bear Lake Co., ID. Named for Phosphoria Gulch, Bear Lake Co., UT (Richards and Mansfield, 1912).

(alphabetical): Ervay Tongue (WY*), Meade Peak Member (ID*,MT*,NV*,UT*,WY*) or Meade Peak Tongue (ID*,NV*,UT*), /Retort Phosphatic Shale Member (ID*,MT*,NV*,UT*,WY*) or Retort Tongue (ID*,MT*,UT*,WY*), Rex Chert Member (ID*,MT*,UT*,WY*) or Rex Tongue (UT*), Tosi Chert Member (ID*,MT*,UT*,WY*) or Tosi Tongue (ID*,MT*,UT*,WY*).

Unit Name History:
Named and divided into phosphate shale part and Rex Chert Member (new) (Richards and Mansfield, 1912). Areal limits (Mansfield, 1916). Sybille and Ervay Tongues named (Thomas, 1934). Revised; Areal limits; Overview (Condra and others, 1940). Revised; Overview (McKelvey and others, 1959). Overview (Robinson and Barnett, 1963). Revised (Skipp and others, 1979). Biostratigraphic dating; Age modified (Behnken and others, 1986).


Richards, R.W. and Mansfield, G.R., 1912, The Bannock overthrust; a major fault in southeastern Idaho and northeastern Utah: Journal of Geology, v. 20, no. 8, p. 681-709.

Mansfield, G.R., 1916, A reconnaissance for phosphate in the Salt River Range, Wyoming: U.S. Geological Survey Bulletin, 620, p. 331-349.

Thomas, H.D., 1934, Phosphoria and Dinwoody tongues in lower Chugwater of central and southeastern Wyoming: American Association of Petroleum Geologists Bulletin, v. 18, no. 12, p. 1655-1697.

Condra, G.E., Reed, E.C. and Scherer, O.J., 1940, Correlation of the formations of the Laramie Range, Hartville uplift, Black Hills, and western Nebraska: Nebraska Geological Survey Bulletin, no. 13, 52 p., Revised 1950.

McKelvey, V.E., Cheney, T.M., Cressman, E.R., Sheldon, R.P., Swanson, R.W. and Williams, J.S., 1959, The Phosphoria, Park City, and Shedhorn formations in the western phosphate field, IN Shorter contributions to general geology, 1936: U.S. Geological Survey Professional Paper, 313-A, p. A1-A47, Also, 1956, Summary description of Phosphoria, Park City, and Shedhorn Formations in western phosphate field, American Association of Petroleum Geologists, v. 40, no. 12, p. 2826-2863 (advance summary).

Robinson, G.D. and Barnett, H.F., 1963, Geology of the Three Forks quadrangle, Montana, with sections on petrography of igneous rocks by H.F. Barnett: U.S. Geological Survey Professional Paper, 370, 143 p.

Skipp, Betty, Hoggan, R.D., Schleicher, D.L. and Douglass, R.C., 1979, Upper Paleozoic carbonate bank in east-central Idaho-Snaky Canyon, Bluebird Mountain, and Arco Hills Formations, and their paleotectonic significance: U.S. Geological Survey Bulletin, 1486, 78 p.

Behnken, F.H., Wardlaw, B.R. and Stout, L.N., 1986, Conodont biostratigraphy of the Permian Meade Peak Phosphatic Shale Member, Phosphoria Formation, southeastern Idaho: University of Wyoming Contributions to Geology, v. 24, no. 2, p. 169-190.

Perkins, Robert B., McIntyre, Brandie, Hein, James R., Piper, David Z., 2003, Geochemistry of Permian rocks from the margins of the Phosphoria Basin; Lakeridge Core, western Wyoming: U.S. Geological Survey, Open-File Report OF 03-0021, 60 p.

Hiatt, Eric, and Budd, David A., 2003, Extreme paleoceanographic conditions in a Paleozoic oceanic upwelling system., organic productivity and widespread phosphogenesis in the Permian Phosphoria Sea: In, Extreme depositional environments; mega end members in geologic time: Chan, Marjorie A., and Archer, Allen W., editors, Geological Society of America, Special Paper, v. 370, p. 245-264.

Piper, David Z., and Link, Paul Karl, 2002, An upwelling model for the Phosphoria Sea; a Permian, ocean-margin sea in the Northwest United States; AAPG Bulletin, v. 86, no. 7, p. 1217-1235.

Knudsen, A. C., Gunter, M. E., Herring, J. R., and Grauch, R. I., 2001, Mineralogical characterization of strata of the Meade Peak phosphatic shale member of the Permian Phosphoria Formation., channel and individual rock samples of measured section J and their relationship to measured sections A and B, central part of Rasmussen Ridge, Caribou County, Idaho: U.S. Geological Survey, Open-File Report OF 02-0125, 38 p. <>.

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Last modified: 1/7/2011