GEOLEX

Summary of Citation: Bighorn

Publication:
Darton, N.H., 1904, Comparison of the stratigraphy of the Black
   Hills, Bighorn Mountains, and Rocky Mountain Front Range:
   Geological Society of America Bulletin, v. 15, p. 379-448

Usage in Publication:
Bighorn limestone*

Modifications:	Geologic Province:	Dominant Lithology:
Named	Powder River basin Bighorn basin	Limestone

Summary:
Name Bighorn limestone applied in Powder River basin and Bighorn basin, WY to hard, massive, light-gray or buff limestone that makes high cliffs in the east slope of Bighorn Mountains. No type locality designated. Name derived from Bighorn Mountains. Has a reticulating network of silica and its weathered surfaces are irregularly pitted or honeycombed. Thickness ranges from 200 to 300 ft. Overlies Cambrian Deadwood formation and underlies Mississippian Littlehorn limestone (new) [but the nature of its contacts not discussed]. Fossils in lower part are of Trenton age, and those in upper part are Richmond age. Numerous corals recognized. Considered Late Ordovician.

Summary of Citation: Bighorn

Publication:
Darton, N.H., 1906, Fish remains in Ordovician rocks in Bighorn
   Mountains, Wyoming, with a resume of Ordovician geology of
   the northwest: Geological Society of America Bulletin, v.
   17, p. 541-566

Usage in Publication:
Bighorn limestone*

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Bighorn basin Powder River basin Wind River basin

Summary:
Occurrences in Bighorn Mountains, WY in the Powder River and Bighorn basins, and in the Owl Creek Mountains, WY in the Bighorn and Wind River basins discussed. Composed in Bighorns of a basal, gray, coarse-grained sandstone usually 25 to 30 ft thick, middle, buff, massive limestone that has irregular, siliceous masses one-half to 1 inch diameter that give the outcrop a ragged appearance, and an upper, soft, white to gray, fine-grained limestone. Basal sandstone is very distinctive and helps separate Bighorn from the unconformably underlying Deadwood formation. Underlies Madison limestone. Is 300 ft thick north of the Powder River. Thins southeast. Ranges from 40 to 150 ft thick in Owl Creek Mountains where only massive limestone is present. Fossil fish found in basal sandstone in Bighorns indicate correlation with Harding sandstone of CO. Middle limestone is Trenton age (corals, brachiopods). Upper limestone is Richmond age. Of Ordovician age.

Summary of Citation: Bighorn

Publication:
Blackwelder, E., 1918, New geological formations in western
   Wyoming: Washington Academy of Sciences Journal, v. 8, no.
   13, p. 417-426

Usage in Publication:
Bighorn dolomite*

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Greater Green River basin

Summary:
A thin (30 to 40 ft thick) dolomite on the west slope of Dinwoody Canyon, north side of Wind River Range, Sublette Co, WY in the Greater Green River basin, at top of Bighorn dolomite and beneath Darby formation (new) named Leigh dolomite member of Bighorn. At most localities the upper and lower contact of the member is a disconformity. No type locality designated for member. Source of geographic name of member not stated. Member recognized as being distinct from rest of Bighorn in that it is thin, dense, brittle, and flaggy whereas typical Bighorn is massive. Fauna (ostracods, pelecypods, gastropods) found at a few localities date member as Richmond or late Ordovician age.

Summary of Citation: Bighorn

Publication:
Miller, A.K., 1930, The age and correlation of the Bighorn
   Formation of northwestern United States: American Journal of
   Science, 5th series, v. 20, p. 196-213

Usage in Publication:
Bighorn formation

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Wind River basin

Summary:
Thought to be a widespread unit that underlies most of MT, WY and southeast ID. Fossils occur throughout the formation. Is 300 ft thick at "type locality" on east slope of Bighorn Mountains where it can be divided into a thin basal sandstone (25 to 30 ft thick), a massive-bedded cliff-forming dolomite member, and an upper thin-bedded dolomite member (75 to 100 ft thick). Is thinner in Wind River basin [than at the type?] and may be absent in southeast WY. Disconformably overlies Gallatin Limestone in Wind River basin where it can be divided into a basal 1 to 4 ft thick sandstone named Lander sandstone member, middle massive dolomite member, and the upper or Leigh dolomite member. All three members are fossiliferous. Fossils (gastropods, cephalopods, corals, worms, crinoids, brachiopods) listed. The thin Lander is correlated with the basal sandstone in the Bighorn Mountains. The Lander has a fauna of Richmond age. The Leigh has a Richmond fauna.

Summary of Citation: Bighorn

Publication:
Dorf, E., 1934, Stratigraphy and paleontology of a new Devonian
   formation at Beartooth Butte, Wyoming: Journal of Geology,
   v. 42, no. 7, p. 720-737

Usage in Publication:
Bighorn dolomite

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Bighorn basin

Summary:
Upper contact revised at Beartooth Butte, T58N, R105W, Park Co, WY in the Bighorn basin. At this locality, Bighorn disconformably underlies the newly named Lower Devonian Beartooth Butte formation.

Summary of Citation: Bighorn

Publication:
Dorf, E. and Lochman, Christina, 1940, Upper Cambrian formations
   in southern Montana: Geological Society of America Bulletin,
   v. 51, no. 4, p. 541-556

Usage in Publication:
Bighorn dolomite

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Bighorn basin

Summary:
Revised in that Bighorn unconformably overlies newly named Upper Cambrian Grove Creek formation in southern Carbon Co, MT in Beartooth Mountains, Bighorn basin. Ordovician age.

Summary of Citation: Bighorn

Publication:
Sloss, L.L. and Moritz, C.A., 1951, Paleozoic stratigraphy of
   southwestern Montana: American Association of Petroleum
   Geologists Bulletin, v. 35, no. 10, p. 2135-2169

Usage in Publication:
Bighorn dolomite

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits	Montana folded belt province

Summary:
Within study area unit occurs only as far west as west flank of Madison Range, eastern Madison Co, MT, Montana folded belt province. Study area includes extreme southwest MT south of Boulder batholith and west of Yellowstone National Park within parts of Beaverhead, Madison and Gallatin Cos, MT, Montana folded belt province. Overlies Red Lion formation; underlies Devonian rocks. Equivalent to Saturday Mountain formation in central ID and Fish Haven dolomite in southeast ID. Thickness ranges from 10-50 ft. Isopach map of Ordovician. Middle and Late Ordovician age.

Summary of Citation: Bighorn

Publication:
Lochman-Balk, Christina, 1956, The Cambrian of the Rocky Mountains
   and southwest deserts of the United States and adjoining
   Sonora province, Mexico, IN Rodgers, John, ed., El Sistema
   Cambrico, su paleogeografia y el problema de su base; Symposium;
   Parte II, Australia, America: International Geological
   Congress, 20th, Report, Mexico City, 1956, p. 529-661

Usage in Publication:
Bighorn dolomite

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Williston basin

Summary:
Revised in that Bighorn dolomite overlies the Zortman member (new) of the Emerson formation in the Little Rocky Mountains, Blaine and Phillips Cos, MT in the Williston basin.

Summary of Citation: Bighorn

Publication:
Ross, R.J., Jr., 1957, Ordovician fossils from wells in the
   Williston basin, eastern Montana, IN Contributions to general
   geology, 1955: U.S. Geological Survey Bulletin, 1021-M, p.
   M439-M510

Usage in Publication:
Bighorn group*

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Williston basin

Summary:
Raised to group status to include the Red River and overlying Stony Mountain formations in the subsurface of the Williston basin. The term Bighorn dolomite is retained for undivided surface occurrences in MT and WY. No effort has been made to differentiate between dolomitic strata, designated by others as the Stonewall formation, and the upper Stoney Mountain formation. As long as the so-called Stonewall strata seem assignable to the Upper Ordovician, it would seem best to regard them as a member of Stoney Mountain formation, if they were to be separately designated. Underlain by Winnipeg formation; overlain by Silurian rocks [Interlake formation]. Discusses faunas in drill cores from wells in Roosevelt, Dawson, Wibaux, and Fallon Cos, MT in the Williston basin. Late Ordovician in age.

Summary of Citation: Bighorn

Publication:
Porter, J.W. and Fuller, J.G., 1959, Lower Paleozoic rocks of
   northern Williston basin and adjacent areas: American
   Association of Petroleum Geologists Bulletin, v. 43, no. 1,
   p. 124-189

Usage in Publication:
Bighorn group

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Williston basin

Summary:
Revised by addition of Stonewall formation as uppermost unit of Bighorn. Ross (1957) included Stonewall in his Stony Mountain formation. Group now consists of (ascending) Red River, Stony Mountain, and Stonewall formations. Stony Mountain is divided into (ascending) Stony Mountain shale [member] [same name should not be applied both to unit as a whole and to part of it] and Gunton member. Cross sections; table of nomenclature. Late Ordovician age.

Summary of Citation: Bighorn

Publication:
Reeves, C.C., Jr., 1964, New Cambrian, Ordovician, Devonian,
   and Mississippian measured sections, west flank Teton Mountains,
   Wyoming: The Mountain Geologist, v. 1, no. 4, p. 213-225

Usage in Publication:
Bighorn Dolomite

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Yellowstone province

Summary:
Two measured sections described on west flank, Teton Range, Teton Co, WY in the Yellowstone province. Lower part is 275.5+ ft thick in Darby Canyon and 229.5+ ft thick in Badger-North Leigh Canyon divide, approximately 11.5 mi N 42 deg W of Grand Teton. The upper part, or Leigh Member, is 36.8 ft thick on the Badger-North Leigh Canyon divide proposed as "type, or...reference section for the Leigh". The second section totals 266.3+ ft thick. Forms massive cliffs. Weathers into giant talus blocks. Has a "pit and cusp" weathered surface. Emits fetid odor when struck by pick. Is younger than Flathead Sandstone and older than Darby Formation. Lower part is usually dark brown, massive, yellow-brown-weathering dolomite with many white chert stringers and chert nodules. Upper part, or Leigh Member, is a gray, vugular dolomite with ripply striations. Is fossiliferous (horn corals, pelecypods, brachiopods, all poorly preserved). Ordovician age.

Summary of Citation: Bighorn

Publication:
Armstrong, F.C. and Oriel, S.S., 1965, Tectonic development of
   Idaho-Wyoming thrust belt: American Association of Petroleum
   Geologists Bulletin, v. 49, no. 11, p. 1847-1866

Usage in Publication:
Bighorn Dolomite*

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Greater Green River basin

Summary:
Represents all of Ordovician rocks in western WY, Greater Green River basin. Correlates with Fish Haven Dolomite in southeastern ID. [Fish Haven used in ID and Bighorn used in WY.] Isopach map and generalized section. Assigned Late Ordovician age.

Summary of Citation: Bighorn

Publication:
Keefer, W.R. and Van Lieu, J.A., 1966, Paleozoic formations in
   the Wind River basin, Wyoming, IN Geology of the Wind River
   basin, central Wyoming: U.S. Geological Survey Professional
   Paper, 495-B, p. B1-B60

Usage in Publication:
Bighorn Dolomite*

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Wind River basin Greater Green River basin Bighorn basin

Summary:
Forms cliffs. Divisible into basal sandstone, the Lander Sandstone Member; middle massive dolomite; and an upper thin-bedded dolomite, the Leigh Dolomite Member. The Lander occurs locally along the east flank of the Wind River Range where it is a lenticular gray to tan, partly red, fine- to coarse-grained sandstone less than 5 ft thick. Fragments of the unconformably underlying Gallatin Limestone are commonly incorporated in the lower part. The middle member is uniform, resistant, cliff-forming, buff to gray granular dolomite 230 ft thick in central and northern Wind River Range to 15 in southern part of basin, that has rough pitted surface. The Leigh is a white, gray, pink, thin-bedded to platy dolomite 85 ft thick in northwest end of Wind River Range; thins south owing to erosional unconformity at top at contact with Darby Formation. Fossiliferous: poorly preserved corals, mollusks, crinoids. Most of Bighorn considered Late Ordovician but Lander may be Middle Ordovician. Lander is a transgressive marine deposit whose source is not known. The main body of the Bighorn was deposited in a warm shallow sea. Cross sections. Isopach map shows extent of Bighorn in Wind River basin and adjacent Sublette Co, Greater Green River basin, and Hot Springs and Washakie Cos, Bighorn basin.

Summary of Citation: Bighorn

Publication:
Witkind, I.J., Hoskins, P.A., Lindsey, V.L. and Mitchell, E.L.,
   1972, Geologic map of the Henrys Lake quadrangle, Idaho and
   Montana: U.S. Geological Survey Miscellaneous Investigations
   Series Map, I-781-A, 1 sheet, scale 1:62,500

Usage in Publication:
Bighorn? Dolomite*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits	Montana folded belt province Snake River basin

Summary:
Mapped undivided with Snowy Range? Formation and Pilgrim? Limestone in Henrys Lake Mountains, Gallatin Co, MT, Montana folded belt province and Fremont Co, ID, Snake River basin. Thickness is 100-125 ft. Unconformably underlies Jefferson Formation. Late Ordovician age.

Summary of Citation: Bighorn

Publication:
Poole, F.G., Stewart, J.H., Palmer, A.R., Sandberg, C.A., Madrid,
   R.J., Ross, R.J., Jr., Hintze, L.F., Miller, M.M. and Wrucke,
   C.T., 1992, Latest Precambrian to latest Devonian time;
   development of a continental margin, Chapter 2, IN Burchfiel,
   B.C., Lipman, P.W., and Zoback, M.L., eds., The Cordilleran
   Orogen; conterminous United States: Geological Society of
   America, The Geology of North America, The Decade of North
   American Geology (DNAG), v. G-3, p. 9-56

Usage in Publication:
Bighorn Dolostone*

Modifications:	Geologic Province:	Dominant Lithology:
Redescribed	Montana folded belt province	Dolostone

Summary:
Is redescribed as dolostone. The name "dolostone" is used for rocks composed predominantly of the mineral "dolomite" on Figure 2 and throughout this chapter, although in the literature it has been common practice to use dolomite rather than dolostone in formal names of dolomitic formations and members. Occurs in stratigraphic column for southwest MT (Montana folded belt province). Unconformably above Snowy Range Formation (Upper Cambrian and Lower Ordovician); unconformably below Beartooth Butte Formation (Lower Devonian). Assigned to Cincinnatian Series (Upper Ordovician).

Summary of Citation: Bighorn

Publication:
Sprinkel, D.A., 1994, Stratigraphic and time-stratigraphic cross
   sections; a north-south transect from near the Uinta Mountain
   axis across the Basin and Range transition zone to the western
   margin of the San Rafael Swell, Utah: U.S. Geological Survey
   Miscellaneous Investigations Series Map, I-2184-D, 31 p., 2
   sheets

Usage in Publication:
Bighorn Dolomite*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits	Uinta uplift

Summary:
Name used for Ordovician rocks on hanging wall of Absaroka thrust fault in Summit Co, UT, Uinta uplift. These are the only Ordovician rocks present along line of section of study area. Bighorn generally restricted to rocks in WY, whereas time-equivalent rocks in north-central UT have been assigned to Fish Haven Dolomite, though nomenclatural boundary has varied in this part of UT. Unconformably underlies Jefferson Formation; unconformably overlies Lynch? Dolomite. Late Ordovician age.