U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Geologic Unit: Inkom
Search archives
Map showing publication footprint
  • Usage in publication:
    • Inkom Formation
  • Modifications:
    • First used
  • AAPG geologic province:
    • Great Basin province
Publication:

Woodward, L.A., 1970, Tectonic implications of structure of Beaver and northern San Francisco Mountains, Utah, IN Note and Discussion: Geological Society of America Bulletin, v. 81, no. 5, p. 1577-1584.


Summary:

First use of the Inkom Formation [credited to Crittenden and others (in press?)]. Age is Precambrian.

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


Map showing publication footprint
  • Usage in publication:
    • Inkom Formation*
  • Modifications:
    • Named
  • Dominant lithology:
    • Phyllite
  • AAPG geologic province:
    • Northern Rocky Mountain region
Publication:

Crittenden, M.D., Jr., Schaeffer, F.E., Trimble, D.E., and Woodward, L.A., 1971, Nomenclature and correlation of some upper Precambrian and basal Cambrian sequences in western Utah and southeastern Idaho: Geological Society of America Bulletin, v. 82, no. 3, p. 581-602.


Summary:

Pg. 586, 591. Inkom Formation. Present in Pocatello area, Bannock County, southeastern Idaho, and possibly Huntsville area, Weber County, northern Utah. Consists of greenish phyllite that grades upward into greenish-gray to light-olive-gray argillite or slate, siltite, and very fine-grained quartzite. Contains a few beds of conglomerate or impure micaceous quartzite. Thickness at type section 305 m [approx. 1,000 feet]; ranges from 240 to 730 m [approx. 780 to 2,400 feet]. Tentatively assigned to the Brigham Group (revised) in the Huntsville area. Overlies Caddy Canyon Quartzite (new) (only tentatively in Huntsville area); lower contact placed at top of highest quartzite of Caddy Canyon, though some phyllite beds are present below it. Underlies Mutual Formation (extended into Pocatello area); upper contact placed at base of massive quartzite ledges of Mutual. Age is late Precambrian (Precambrian Z). (Inkom Formation adopted by the USGS.)
Type section: north of Portneuf River, in head of small canyon which joins river about a mile (2 km) west of town of Inkom, in northwest part of T. 7 S., R. 36 E., Bannock Co., ID (Northern Rocky Mountain region). Named from town of Inkom.

Source: GNU records (USGS DDS-6; Denver GNULEX, Menlo GNULEX); US geologic names lexicon (USGS Bull. 1520, p. 148-149); Changes in stratigraphic nomenclature, 1971 (USGS Bull. 1372-A, p. A10-A11).


Map showing publication footprint
  • Usage in publication:
    • Inkom Formation*
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Wasatch uplift
Publication:

Sorensen, M.L., and Crittenden, M.D., Jr., 1974, Preliminary geologic map of the Huntsville quadrangle, Weber and Cache Counties, Utah: U.S. Geological Survey Miscellaneous Field Studies Map, MF-592, 1 sheet, scale 1:24,000, See also Sorensen, M.L. and Crittenden, M.D., 1979, "Geologic map of the Huntsville quadrangle, Weber and Cache Counties, Utah," USGS Geol. Quad. Map GQ-1503, 1 sheet, scale 1:24,000. http://ngmdb.usgs.gov/Prodesc/proddesc_1053.htm


Summary:

Inkom Formation is definitely included in the Brigham Group in Utah. Age is Precambrian.

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


Map showing publication footprint
  • Usage in publication:
    • Inkom Formation
  • Modifications:
    • Areal extent
    • Revised
  • AAPG geologic province:
    • Great Basin region
Publication:

Christie-Blick, Nicholas, 1982, Upper Proterozoic and Lower Cambrian rocks of the Sheeprock Mountains, Utah; regional correlation and significance: Geological Society of America Bulletin, v. 93, no. 8, p. 735-750.


Summary:

Inkom Formation. Extended into the Sheeprock Mountains of north-central Utah (Great Basin region) as 1 of 4 formations of the Brigham Group. Thickness 30 to 145 m. Consists of olive-drab, liver-colored, blue or gray siltstone, shale, and slate, and interbeds of greenish-gray, very fine-grained, ripple-marked sandstone. In northwest part of mapped area, white, medium-grained quartzite is present in upper part. Upper part of the Inkom (this report) = lower argillite member of Cohenour's (1959) Mutual Formation. Overlies Caddy Canyon Quartzite and underlies Mutual Formation (both of Brigham). Age is Late Proterozoic. Report includes geologic map, stratigraphic sections.

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


Map showing publication footprint
  • Usage in publication:
    • Inkom Formation
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Northern Rocky Mountain region
Publication:

Link, P.K., and Jansen, S.T., 1987, Stratigraphy of Brigham Group (Late Proterozoic-Cambrian), Bannock, Portneuf, and Bear River Ranges, southeastern Idaho, IN Miller, W.R., ed., The thrust belt revisited: Wyoming Geological Association Field Conference Guidebook, 38th Annual Field Conference, Jackson Hole, WY, September 8-11, 1987, no. 38, p. 133-147.


Summary:

Assigned as 1 of 6 formations to the Brigham Group (group rank extended to southeast ID) in the northern Bannock and Portneuf Ranges and as 1 of 7 formations in the southern Portneuf and Bear River Ranges, Bannock and Bear Lake Cos, ID in the Northern Rocky Mountain region. Overlies Caddy Canyon Quartzite of Brigham; underlies Mutual Formation of Brigham. The lower contact is gradational and the upper contact is disconformable. Is also assigned to depositional sequence 2, a marine sequence. Is one of the most laterally persistent units in the Brigham. Cross section. Late Proterozoic age.

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


Map showing publication footprint
  • Usage in publication:
    • Inkom Formation*
  • Modifications:
    • Age modified
  • AAPG geologic province:
    • Great Basin province
Publication:

Pampeyan, E.H., 1989, Geologic map of the Lynndyl 30' x 60' quadrangle, west-central Utah: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1830, 1 sheet, scale 1:100,000 [http://ngmdb.usgs.gov/Prodesc/proddesc_9946.htm]


Summary:

Age of the Inkom Formation is revised from Proterozoic Z to Late Proterozoic.

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


Search archives

For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

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 ( ).

Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).

Accessibility FOIA Privacy Policies and Notices

USA Gov U.S. Department of the Interior | U.S. Geological Survey
Supported by the National Cooperative Geologic Mapping Program
Page Contact Information: Personnel
Page Last Modified: Thu 04 Apr 2024 03:42:29 PM MDT