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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Inyan Kara group*
  • Modifications:
    • Named
  • Dominant lithology:
    • Sandstone
    • Shale
    • Conglomerate
    • Lignite
  • AAPG geologic province:
    • Powder River basin
Publication:

Rubey, W.W., 1931, Lithologic studies of fine-grained Upper Cretaceous sedimentary rocks of the Black Hills region, IN Shorter contributions to general geology, 1930: U.S. Geological Survey Professional Paper, 165-A, p. A1-A54.


Summary:

Named from exposures along Inyan Kara Creek in the northeastern part of the Moorcroft quad, WY in Powder River basin. Includes (descending): Fall River sandstone (which was called Dakota sandstone in previous reports in the Black Hills, thereby restricting areal limits of Dakota); Fuson shale; and Lakota sandstone. Thickness 150-350 ft. An extremely variable group consisting of discontinuous beds of sandstone, sandy shale, conglomerate, lignite, and variegated siltstone. In general, though not in detail, the higher sandstones are more heavily iron stained and slabby and the lower ones lighter gray and massive. Continental fossils throughout greater part, but marine fossils in upper 20 ft. Is of Early Cretaceous age.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara group*
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Williston basin
Publication:

Dobbin, C.E., and Larsen, R.M., 1934, Geologic and structure contour map of the southern half of the Cedar Creek Anticline, Fallon County, Montana and Bowman County, North Dakota: U.S. Geological Survey [Monograph], Accompanied by DOI Press Memo 94227, p. 2, 1935


Summary:

Extended name in subsurface to the Cedar Creek anticline southeast MT, and southwest ND in Williston basin. Is about 200 ft thick. Overlies Morrison formation; underlies Colorado group. Is of Early Cretaceous age.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara group*
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Powder River basin
Publication:

Waage, K.M., 1958, Regional aspects of Inyan Kara stratigraphy, IN Bibb, T.W., Jr., chairman, Powder River basin: Wyoming Geological Association Field Conference Guidebook, no. 13, p. 71-76.


Summary:

Divided into Fall River sandstone, and an underlying Fuson-Lakota sequence separated by a regional transgressive disconformity, in Powder River basin. Rocks above the disconformity are dominantly marine and marginally marine in origin and are related to overlying Skull Creek shale; those below are continental and related to underlying Morrison formation or Unkpapa sandstone. Assigned to the Early Cretaceous.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara group*
  • Modifications:
    • Reference
    • Revised
  • AAPG geologic province:
    • Chadron arch
Publication:

Waage, K.M., 1959, Stratigraphy of the Inyan Kara group in the Black Hills, IN Contributions to general geology, 1958: U.S. Geological Survey Bulletin, 1081-B, p. B11-B90.


Summary:

Subdivision and nomenclature of Inyan Kara group adjusted to conform to a two-fold lithologic subdivision including a redefined Fall River formation and unconformably underlying redefined Lakota formation, Fuson formation, and Minnewaste limestone, and are reduced to members of Lakota formation. Reference section for the group given in Fall River Canyon, 4-5 mi by road southeast of Hot Springs, SD, secs 29, 32, and 33, T7S, R6E, Fall River Co, SD on the Chadron arch. Is of Early Cretaceous age.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara Group*
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Chadron arch
    • Powder River basin
Publication:

Mapel, W.J., and Chisholm, W.A., 1964, Nonopaque heavy minerals in sandstone of Jurassic and Cretaceous age in the Black Hills, Wyoming and South Dakota, IN Contributions to general geology, 1962: U.S. Geological Survey Bulletin, 1161-C, p. C1-C59.


Summary:

Compares petrology of Fall River, Lakota, and Morrison Formations and Unkpapa Sandstone. Nonopaque heavy suites in Fall River and Lakota Formations differ at most places in the proportions of rounded grains (more abundant in Lakota Formation) and in the presence in Fall River Formation of hornblende and chloritoid. Discusses source and origin. Is of Early Cretaceous age.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara Group*
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Williston basin
    • Powder River basin
Publication:

Robinson, C.S., Mapel, W.J., and Bergendahl, M.H., 1964, Stratigraphy and structure of the northern and western flanks of the Black Hills uplift, Wyoming, Montana, and South Dakota: U.S. Geological Survey Professional Paper, 404, 134 p.


Summary:

Shows distribution and lithologic variation of the group and its subdivisions in western and northern Black Hills, Powder River and Williston basins. Is of Early Cretaceous age.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara Group
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Williston basin
    • Powder River basin
Publication:

Bolyard, D.W., and McGregor, A.A., 1966, Stratigraphy and petroleum potential of Lower Cretaceous Inyan Kara Group in northeastern Wyoming, southeastern Montana, and western South Dakota: American Association of Petroleum Geologists Bulletin, v. 50, no. 10, p. 2221-2244. [Available online, with subscription, from AAPG archives: http://www.aapg.org/datasystems or http://search.datapages.com]


Summary:

Consists of (ascending) Lakota and Fall River Formations. Unconformably overlies Morrison Formation. Underlies Thermopolis Shale. Revised in that the Fall River is divisible into three newly named members --the Liscom Creek, Morton, and Coyote Creek of Early Cretaceous age. Isopach map of entire group in northeast WY and southeast MT and western SD of the Williston basin. Ranges from 22 to 700 ft thick; area of maximum thickness lies between the Black Hills northwest to southeast MT. Cross sections. E-logs.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara Group*
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Chadron arch
    • Powder River basin
Publication:

Gott, G.B., Wolcott, D.E., and Bowles, C.G., 1974, Stratigraphy of the Inyan Kara Group and localization of uranium deposits, southern Black Hills, South Dakota and Wyoming: U.S. Geological Survey Professional Paper, 763, 57 p., (incl. geologic maps, scale 1:48,000)


Summary:

Compiled detailed mapping of 13 71/2-minute quadrangles showing details of stratigraphy and distribution of the group and its subdivisions in the southern Black Hills, Fall River and Custer Cos, SD and Weston Co, WY, on Chadron arch and in Powder River basin. Divided into Lakota and Fall River Formations. Lakota, at base, 200-500 ft thick, constitutes lower two-thirds of the group, and Fall River, at top, 100-160 ft thick, constitutes the upper one-third. Rocks are of continental origin and were deposited under variable depositional environments, resulting in a sequence of many rock units, each composed of several facies. Basal Lakota Formation underlain by Morrison Formation of Jurassic age in western part of mapped area, but in eastern part of area it is underlain by Unkpapa Sandstone (thought by Imlay, 1947, to be equivalent in age to Morrison). Upper, Fall River Formation overlain by Skull Creek Shale of Early Cretaceous age. Group is of Early Cretaceous age. Geologic map, cross sections.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara Formation
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Williston basin
Publication:

Bluemle, J.P., Anderson, S.B., and Carlson, C.G., 1980, North Dakota stratigraphic column: North Dakota Geological Survey, Chart included with North Dakota Geol. Survey Rpt. Inv., no. 71


Summary:

Assigned formational rank and made the basal formation in Dakota Group in Williston basin, western ND. Overlain by Skull Creek Formation, underlain by Morrison Formation. Is Cretaceous in age.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara Formation
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Williston basin
Publication:

Ballard, W.W., Bluemle, J.P., and Gerhard, L.C., 1983, Northern Rockies / Williston basin region: American Association of Petroleum Geologists Correlation Chart Series (COSUNA), Correlation of stratigraphic units of North America (COSUNA) project


Summary:

Assigned formational rank in ND, except for Adams County in the southwestern part of the state where equivalent rocks are assigned to the Fall River and Lakota Formations, undivided. Overlain conformably by the Swift Formation, or by older rocks locally along the eastern side of the Williston basin. See Columns 17-19.

Source: GNU records (USGS DDS-6; Denver GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Inyan Kara Group*
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Powder River basin
Publication:

Fox, J.E., 1993, Stratigraphic cross sections showing electric logs of Upper Cretaceous and older rocks, Powder River basin, southeastern Montana and northeastern Wyoming: U.S. Geological Survey Oil and Gas Investigations Chart, OC-135 to OC-138., Sections A-A' through F-F'; G-G' through L-L'; M-M' through R-R'; S-S' through V-V'


Summary:

Identified as an undivided unit throughout the subsurface of the Powder River basin in MT and WY where it overlies Morrison Formation unconformably and underlies "Dakota silt," a driller's term. Of Early Cretaceous age. [This nomenclature shown on 22 cross sections in this OC series.]

Source: GNU records (USGS DDS-6; Denver GNULEX).


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Asterisk (*) indicates published by U.S. Geological Survey authors.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

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