Fort Union Formation

Cretaceous, Late* (local)
Maastrichtian* (local)
Geologic Province:
Powder River basin*
Williston basin*
Uinta basin*
Piceance basin*
Central Montana uplift*
Green River basin*
Big Horn basin*
Wind River basin
Areal Extent:
Type Locality:
Named for exposures at Old Fort Union [later called Fort Buford, and now town of Buford], near mouth of Yellowstone River, McKenzie Co., ND (Meek and Hayden, 1862) [Geologic names lexicons, USGS Bull. 896, 1200].
Reference section: secs. 7, 16, 17, 21, 28, 32, and 33, T. 1 S., R. 8 E., secs. 2, 3, 11, 12, 13, and 23, T. 2 S., R. 8 E., and secs. 7, 18, 19, 20, T. 2 S., R. 9 E., Park Co., MT (Roberts, 1972).
Group rank (alphabetical): Bear Formation (MT), Bullion Creek Formation (MT,ND,SD), Golden Valley Formation (ND), Lebo Formation (MT), Ludlow Formation (ND), Melville Formation (MT), Sentinel Butte Formation (ND), Slope Formation (MT,ND), Tongue River Formation (MT,ND), Tullock Formation (MT).
Formation rank (alphabetical): Belfry Member (MT), Cannonball Member (ND*,SD*), Fort Kipp Lignite Bed (MT), Fort Peck Lignite Bed (MT), Kingsbury Conglomerate Member (WY), Kleenburn Member (WY), Lebo Member (MT,ND,WY*) or Lebo Shale Member (MT*,SD), Ludlow Member (MT*,ND*,SD*), Sentinel Butte Member (MT,ND*,SD), Shotgun Member (WY*), Tongue River Member (MT*,ND*,SD*,WY*), Tullock Member (MT*,SD,WY*), Waltman Shale Member (WY*).
Unit Name History:
Named (F.B. Weeks and F.V. Hayden, 1862, Acad. Nat. Sci. Proc., v. 13, p. 433) [Geologic names lexicons, USGS Bull. 896, 1200]. Areal limits (Hayden, 1869). Revised (Brown, 1907; Stone and Calvert, 1910; Rogers and Lee, 1923; Dobbin and Horn, 1949; Keefer, 1961). Age modified; Revised; Reference section designated (Roberts, 1972). Revised (Jacob, 1973). Biostratigraphic dating (Hail, 1973). Revised (Clayton and others, 1977; Hickey, 1977). Overview (Denson and others, 1980). Revised (Yuretich and others, 1984). Areal limits (Luft, 1986; Luft and Meier, 1986). Biostratigraphic dating (Robinson and Honey, 1987). Overview (Kirschbaum and Nelson, 1988). Revised; Overview (Honey and Hettinger, 1989). Biostratigraphic dating (Hail, 1990). Overview; Areal limits (Johnson and others, 1990). Age modified (Nichols, 1990). Revised (Denson and others, 1990). Biostratigraphic dating (Roberts and Stanton, 1994).


Hayden, F.V., 1869, Preliminary field report [third annual] of Colorado and New Mexico: U.S. Geological Survey, 155 p.

Brown, Barnum, 1907, The Hell Creek beds of the Upper Cretaceous of Montana: American Museum of Natural History Bulletin, v. 23, art. 33, p. 823-845.

Stone, R.W. and Calvert, W.R., 1910, Stratigraphic relations of the Livingston formation of Montana, Part III: Economic Geology, v. 5, no. 8, p. 741-764.

Rogers, G.S. and Lee, Wallace, 1923, Geology of the Tullock Creek coal field, Rosebud and Big Horn Counties, Montana: U.S. Geological Survey Bulletin, 749, 181 p.

Dobbin, C.E. and Horn, G.H., 1949, Geology of the Mush Creek and Osage oil fields and vicinity, Weston County, Wyoming: U.S. Geological Survey Oil and Gas Investigations Map, OM-103, 1 sheet, scale 1:31,630.

Keefer, W.R., 1961, Waltman Shale and Shotgun members of Fort Union Formation (Paleocene) in Wind River basin, Wyoming: American Association of Petroleum Geologists Bulletin, v. 45, no. 8, p. 1310-1323.

Roberts, A.E., 1972, Cretaceous and early Tertiary depositional and tectonic history of the Livingston area, southwestern Montana, IN Geology of the Livingston area, southwestern Montana: U.S. Geological Survey Professional Paper, 526-C, p. C1-C120, (incl. geologic map, scale 1:62,500).

Jacob, A.F., 1973, Depositional environments of Paleocene Tongue River Formation, western North Dakota: American Association of Petroleum Geologists Bulletin, v. 57, no. 6, p. 1038-1052.

Hail, W.J., Jr., 1973, Geologic map of the Smizer Gulch quadrangle, Rio Blanco and Moffat Counties, Colorado: U.S. Geological Survey Geologic Quadrangle Map, GQ-1131, 1 sheet, scale 1:24,000.

Hickey, L.J., 1977, Stratigraphy and paleobotany of the Golden Valley Formation (early Tertiary) of western North Dakota: Geological Society of America Memoir, 150, 181 p.

Clayton, Lee, Carlson, C.G., Moore, W.L., Groenewold, G.H., Holland, F.D., Jr. and Moran, S.R., 1977, The Slope (Paleocene) and Bullion Creek (Paleocene) Formations of North Dakota: North Dakota Geological Survey Report of Investigations, no. 59, 14 p.

Denson, N.M., Dover, J.H. and Osmonson, L.M., 1980, Lower Tertiary coal bed distribution and coal resources of the Reno Junction-Antelope Creek area, Campbell, Converse, Niobrara, and Weston Counties, Wyoming: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1201, 1 sheet, scale 1:125,000, Supersedes U.S. Geological Survey Miscellaneous Investigations Series Map MF-960.

Yuretich, R.F., Hickey, L.J., Gregson, B.P. and Hsia, Yuan-Lun, 1984, Lacustrine deposits in the Paleocene Fort Union Formation, northern Bighorn basin, Montana: Journal of Sedimentary Petrology, v. 54, no. 3, p. 836-852.

Luft, S.J. and Meier, D.H., 1986, Photogeologic and reconnaissance geologic map of the Bear Jaw Creek quadrangle, Custer County, Montana: U.S. Geological Survey Miscellaneous Field Studies Map, MF-1894, 1 sheet, scale 1:24,000.

Luft, S.J., 1986, Photogeologic and reconnaissance geologic map of the Pennock Creek quadrangle, Custer County, Montana: U.S. Geological Survey Miscellaneous Field Studies Map, MF-1893, 1 sheet, scale 1:24,000.

Robinson, L.N. and Honey, J.G., 1987, Geologic setting of a new Paleocene mammal locality in the northern Powder River basin, Montana: Palaios, v. 2, no. 1, p. 87-90.

Kirschbaum, M.A. and Nelson, S.N., 1988, Geologic history and palynological dating of Paleocene deposits, western Rock Springs uplift, Sweetwater County, Wyoming: University of Wyoming Contributions to Geology, v. 26, no. 1, p. 21-28.

Honey, J.G. and Hettinger, R.D., 1989, Cross section showing correlations of Upper Cretaceous Fox Hills Sandstone and Lance Formation, and lower Tertiary Fort Union and Wasatch formations, southeastern Washakie basin, Wyoming, and eastern Sand Wash basin, Colorado: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1964, 1 sheet.

Nichols, D.J., 1990, Geologic and biostratigraphic framework of the non-marine Cretaceous-Tertiary boundary interval in western North America, IN Truswell, E.M., and Owen, J.A., editors, The proceedings of the 7th International Palynological Congress; Part II: Review of Palaeobotany and Palynology, v. 65, nos. 1-4, 7th International Palynological Congress, Brisbane, Australia, August 28-September 3, 1988, p. 75-84.

Denson, N.M., Macke, D.L. and Schumann, R.R., 1990, Geologic map and distribution of heavy minerals in Tertiary rocks of the Sheridan 30' x 60' quadrangle, Wyoming and Montana: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2020, 1 sheet, scale 1:100,000.

Johnson, E.A., Pierce, F.W. and Sigleo, W.R., 1990, Stratigraphic cross section showing upper Paleocene coal-bearing rocks of the Tongue River Member of the Fort Union Formation in the Piney Canyon SE quadrangle, Weston County, southeastern Powder River basin, Wyoming: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2012, 1 sheet, scale 1:24,000.

Hail, W.J., Jr., 1990, Geology of the lower Yellow Creek area, northwestern Colorado, IN Evolution of sedimentary basins; Uinta and Piceance basins: U.S. Geological Survey Bulletin, 1787-O, p. O1-O45.

Roberts, S.B. and Stanton, R.W., 1994, Stratigraphy and depositional setting of thick coal beds in the Grass Creek coal mine, southwestern Bighorn basin, Wyoming, IN Flores, R.M., and others, Organics and the Rockies; field guide: Geological Survey of Wyoming Public Information Circular, no. 33.

Large, D. J., Jones, T. F., Somerfield, C., Gorringe, M. C., Spiro, B., Macquaker, J. H. S., Atkin, B. P., 2003, High-resolution terrestrial record of orbital climate forcing in coal Geology (Boulder), v. 31, no. 4, p. 303-306.

Ayers, Walter B., Jr., 2002, Coalbed gas systems, resources and production and a review of
contrasting cases from the San Juan and Powder River basins: AAPG Bulletin, v. 86, no. 11, p. 1853-1890.

Hartman, Joseph H., Johnson, Kirk R., Nichols, Douglas J., 2002, The Hell Creek Formation and the Cretaceous-Tertiary boundary in the Northern Great Plains., an integrated continental record of the end of the Cretaceous: Geological Society of America, Special Paper, v. 361, p. 9-34.

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Last modified: 1/7/2011