GEOLEX

Summary of Citation: Quadrant

Publication:
Peale, A.C., 1893, The Paleozoic section in the vicinity of
   Three Forks, Montana, with petrographic notes by G.P. Merrill:
   U.S. Geological Survey Bulletin, 110, 56 p.

Usage in Publication:
Quadrant formation*

Modifications:	Geologic Province:	Dominant Lithology:
First used	Montana folded belt province	Limestone Quartzite

Summary:
First published use of name. No type locality given. Mapped with Madison formation north of East Gallatin River and on east side of Missouri River, Gallatin Co, MT and on west side of Gallatin River, Broadwater Co, MT in Montana folded belt province. Overlies Lower Carboniferous Madison (new) conformably. Consists of red limestones and overlying cherty limestones. Lower red unit includes brecciated limestone or limestone conglomerate at base, coarse arenaceous beds about 50 ft thick succeeded by gray and bluish fossiliferous limestone, banded red, about 120 ft thick; and an upper gray fossiliferous limestone 50 ft thick. Fossils are brachiopods, corals, bryozoans. Upper cherty unit is a 150 ft sequence of thin-bedded cherty limestone that alternates with quartzite. Is beneath the Jura-Trias Ellis formation (new). Assigned to the Late Carboniferous.

Summary of Citation: Quadrant

Publication:
Iddings, J.P. and Weed, W.H., 1894, Livingston atlas sheet
   [Montana]: U.S. Geological Survey Geologic Atlas of the United
   States, Livingston folio, no. 1, 4 p.

Usage in Publication:
Quadrant quartzite*

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

Summary:
Redescribed from Quadrant formation to Quadrant quartzite. Present in the Montana folded belt province, eastern Gallatin and Park Cos and extended to the Central Montana uplift, Sweetgrass Co, MT. Conformably overlies Lower Carboniferous Madison limestone. Lower part consists of impure, arenaceous limestones with much earthy magnesian [dolomite] rock and red clay that grade upward into beds that are dominantly compact [silica-cemented] white or pinkish quartzites and cream-colored limestones. In the southern part of the mapped area, Quadrant is capped by dark-colored quartzite with chert concretions [Phosphoria Formation]. Overlain by Ellis limestone of the Juratrias period. Generalized columnar section. Geologic map included. Assigned to Late Carboniferous.

Summary of Citation: Quadrant

Publication:
Weed, W.H., 1896, Yellowstone National Park sheets; sedimentary
   rocks: U.S. Geological Survey Geologic Atlas of the United
   States, Yellowstone National Park folio, no. 30, p. 4-5

Usage in Publication:
Quadrant quartzite*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Revised	Yellowstone province

Summary:
Shown as Quadrant formation on geologic map explanation. Type section not designated but name taken from resistant bluff that encircles Quadrant Mountain in the southern Gallatin Range of northwest Yellowstone Park, in the vicinity of 110 deg, 50 min W, 44 deg, 55 min N, Yellowstone province. Beds range in thickness from 4 to 25 ft and weather in massive blocks or locally into smaller fragments that form debris slopes as seen in the Teton Range. Average total thickness is 400 ft in the Gallatin Range. Exposures less prominent in the southwest corner of Yellowstone Park. Revised to restrict Quadrant quartzite to beds conformably below the cherty and fossiliferous limestones and shales of Teton formation of "Jura-trias" age which were formerly assigned to the upper part of Quadrant formation of Peale (1893) and to cherty quartzites of upper part of Quadrant found in the southern part of the Livingston sheet (Iddings and Weed, 1894). Overlies Madison limestone. Is Late Carboniferous in age.

Summary of Citation: Quadrant

Publication:
Peale, A.C., 1896, Description of the Three Forks sheet [Montana]:
   U.S. Geological Survey Geologic Atlas of the United States,
   Three Forks folio, no. 24, 5 p.

Usage in Publication:
Quadrant Formation*

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

Summary:
Extended to areas in the northern Gravelly Range, Tobacco Root Mountains, and Madison Range, Madison, Gallatin, and southeast Jefferson Cos, MT in the Montana folded belt province. Name changed from Quadrant quartzite to Quadrant formation. In many localities contains a basal limestone conglomerate. In ascending order, consists of a lower red, arenaceous and argillaceous magnesian limestone [dolomitic] 170-200 ft thick that forms red-weathering ravines above the Madison limestone; and an upper unit (150-180 ft thick) of thin-bedded cherty limestone alternating with quartzitic layers that become increasingly sandy toward the top. Overlain by a prominent bed of sandstone which may be equivalent to red Juratrias sandstones at more southern localities [Teton formation]. These sandstones are widespread and mapped with Ellis formation of Juratrias age. Columnar section and geologic map included. Is considered Late Carboniferous in age on the basis of fossils found in the lower red limestone unit.

Summary of Citation: Quadrant

Publication:
Iddings, J.P. and Weed, W.H., 1899, Descriptive geology of the
   northern end of the Teton Range, Chapter 4, IN Geology of
   the Yellowstone National Park: U.S. Geological Survey Monograph,
   32, pt. 2, p. 149-164

Usage in Publication:
Quadrant quartzite*

Modifications:	Geologic Province:	Dominant Lithology:
Overview Areal limits	Yellowstone province

Summary:
Called Quadrant quartzite, but on map explanation shown as Quadrant formation. Extended southward into northern end of Teton Range, Teton Co, WY in Yellowstone province. Weathers into small, angular fragments at Berry Creek or into compact [indurated], great cubical blocks near summit of Crimson Peak. Is nonresistant near junction of Owl and Berry Creeks. Generalized measured section at Survey Peak. In the Birch Hills area, southwestern part of Yellowstone Park consists of white, granular quartzite and interbedded marble limestones. Resembles the formation as developed in the Gallatin Range to the north. Overlain by Teton sandstone or, near Birch Creek, by unnamed soft and micaceous pyrite-bearing shales. Overlies Madison formation or limestone. Is of Carboniferous age.

Summary of Citation: Quadrant

Publication:
Hague, Arnold, 1899, Descriptive geology of the Huckleberry
   Mountain and Big Game Ridge, Chapter 5, IN Geology of the
   Yellowstone National Park: U.S. Geological Survey Monograph,
   32, pt. 2, p. 165-202

Usage in Publication:
Quadrant quartzite

Modifications:	Geologic Province:	Dominant Lithology:
Not used

Summary:
Not mapped [although present] in the vicinity of the upper Snake River near Snake River Hot Springs, southern part of Yellowstone Park, WY in Yellowstone province. Reference map is the Geologic Atlas Folio 30 by Weed (1896). [Quadrant not recognized and was probably included in Teton Formation.] At the confluence of Red Creek and Snake River, buff-red, arenaceous limestone and overlying pure sandstone are speculated beds of Quadrant, but are mapped as Madison limestone. Overlain by bright-red sandstone of the Teton formation. Along east side of Big Game Ridge in Yellowstone Park and northern Teton Co, WY, Quadrant not mapped [probably included with Madison limestone] except for small area north of Sickle Creek. No age given [probably Carboniferous].

Summary of Citation: Quadrant

Publication:
Iddings, J.P. and Weed, W.H., 1899, Descriptive Geology of the
   Gallatin Mountains, Chapter 1, IN Geology of the Yellowstone
   National Park: U.S. Geological Survey Monograph, 32, pt. 2,
   p. 1-59

Usage in Publication:
Quadrant quartzite*

Modifications:	Geologic Province:	Dominant Lithology:
Redescribed	Yellowstone province	Sandstone

Summary:
Measured sections in the southern Gallatin Mountains, approximately 110 deg, 50 min W, 44 deg, 55 min N, northwest Yellowstone Park, WY, Yellowstone province. Called Quadrant quartzite and redescribed to include distinct sandstone beds shown as Quadrant formation on geologic map explanation. White sandstone layers within Quadrant form an [conspicuous] escarpment on all sides of Quadrant Mountain. Three sections described and compared along the sides of Quadrant Mountain are: at southeast corner (401 ft); at the "Pocket" (209 ft); and on the west side at Fawn Creek "amphitheater" (326 ft). Other sections located at Little Quadrant Mountain, Bannock Peak, and on the southeast spur of Electric Peak. Partial section measured just west of Joseph Peak. Locally, contains slickensides. Overlain by Teton formation or limestone. Is Carboniferous in age.

Summary of Citation: Quadrant

Publication:
Weed, W.H., 1899, Description of the Fort Benton quadrangle
   [Montana]: U.S. Geological Survey Geologic Atlas of the United
   States, Fort Benton folio, no. 55, 7 p.

Usage in Publication:
Quadrant formation*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Revised Age modified	Sweetgrass arch

Summary:
Extended to Little Belt Mountains area, southeast Cascade and southern Judith Basin Cos, north-central MT on Sweetgrass arch. Geologic map and columnar section included. Revised to include 2 unranked units: basal Kibbey sandstone (new name), and an overlying Otter shale [formerly Otter Creek shales of Weed, (1892). Near Riceville [approximately located along Belt Creek, center part of T17N, R6E] the total thickness is 456 ft. Best exposures noted are along banks of Belt Creek. Overlies [unranked] Castle limestone of upper Madison limestone. Is overlain by Ellis formation, containing Jurassic fossils. Age refined from Carboniferous to Early Carboniferous on the basis of fossils contained within limestones of Otter shale.

Summary of Citation: Quadrant

Publication:
Weed, W.H., 1900, Geology of the Little Belt Mountains, Montana:
   U.S. Geological Survey Annual Report, 20, pt. 3, p. 257-462

Usage in Publication:
Quadrant group*

Modifications:	Geologic Province:	Dominant Lithology:
Revised Overview	Sweetgrass arch Montana folded belt province

Summary:
Present in southern Judith Basin Co, and southeast Cascade Co, Sweetgrass arch and in northeast Meagher Co, Montana folded belt province, central MT. Shown on geologic map as Quadrant formation in the Little Belt Mountains, where outcrops encircle the area and form inliers created by synclines. In text, Quadrant is raised in rank to Quadrant group which now includes basal Kibbey sandstone and overlying Otter shale. Gross thickness ranges from 300 to 1,400 ft. Measured sections shown at: Judith River near Utica where part of thick Otter (1,225 ft) resembles Jurassic beds; and at Dirty Creek [near T11N, R13E]. Columnar sections shown for sections near Martinsdale, at Dirty Creek, near Riceville and west of Utica. Overlies Castle limestone [unranked upper Madison limestone] and unconformably underlies Ellis formation. Near Riceville, Otter limestone beds contain Early Carboniferous or Mississippian? aged brachiopods; near Dry Fork of Belt Creek, fauna taken inches below Jurassic fossils are also Early Carboniferous.

Summary of Citation: Quadrant

Publication:
Weed, W.H., 1901, Geology and ore deposits of the Elkhorn mining
   district, Jefferson County, Montana, IN Ore deposits, Part
   II: U.S. Geological Survey Annual Report, 22, p. 399-550

Usage in Publication:
Quadrant formation*

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

Summary:
Redescribed to include, locally, metamorphosed sandstone and limestone. Mapped as Quadrant formation in the Elkhorn mining district, Jefferson Co, MT in the Montana folded belt province. Measured sections 3 mi below town of Elkhorn contain 2 thin, igneous intrusions of augitic rock. Along Queen Gulch, sandstones and shales are unaltered--but at Crow Ridge, the formation consists of quartzite [metaquartzite] and lime-silicate hornfels. At Crow Ridge, beds overlying Madison limestone and underlying Mesozoic rocks are considered Quadrant and have an estimated thickness of 380 ft. Is of Neocarboniferous age.

Summary of Citation: Quadrant

Publication:
Fisher, C.A., 1909, Geology of the Great Falls coal field,
   Montana: U.S. Geological Survey Bulletin, 356, 85 p.

Usage in Publication:
Quadrant formation*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Age modified	Sweetgrass arch

Summary:
Mapped in eastern part of Great Falls region, Cascade and Judith Basin Cos, MT on the Sweetgrass arch. Kibbey sandstone not recognized because a 352 ft measured section along Belt Creek near Riceville contains little (less than 20 ft) sand. Probable hiatus at base is indicated by the abrupt Quadrant formation-Madison limestone contact. Unconformably overlain by basal limestone and conglomeratic sandstone of the Jurassic Ellis formation. Quadrant pinches out entirely between Belt Creek in the northern Little Belt Mountains and Sand Coulee Creek in Cascade Co, southeast of Great Falls. Previously considered Early Carboniferous or Mississippian?--now considered Early Pennsylvanian in age based on opinion provided by George H. Girty (written communication).

Summary of Citation: Quadrant

Publication:
Calvert, W.R., 1909, Geology of the Lewistown coal field, Montana:
   U.S. Geological Survey Bulletin, 390, 83 p.

Usage in Publication:
Quadrant formation*

Modifications:	Geologic Province:	Dominant Lithology:
Redescribed Areal limits	Sweetgrass arch Central Montana uplift	Coal

Summary:
Present in southeast Judith Basin Co, MT in Sweetgrass arch and is extended to western Big Snowy Mountains, Judith Mountains, and South Moccasin Mountains, Fergus Co, in Central Montana uplift. At least 100 ft exposed on west side of Judith uplift at Deer Creek dome (northwest of Judith Peak); only upper Quadrant shaly beds are exposed in dome south of South Moccasin Mountains. Near Deer Creek, lowest member [beds] exposed is a soft reddish sandstone overlain by dark shale, bituminous limestone and shale. Near Judith and Moccasin Mountains, is non-resistant and forms valleys but near west end of Big Snowy Mountains, limestone member [uppermost beds] is a ridge former. Geologic map. Reported occurrence of 6 in thick uneconomic coal prospect about 400 ft stratigraphically below coal-bearing Kootenai formation in sec 23, T13N, R17E, western Fergus Co in Big Snowy Mountains. Where Quadrant is exposed in core of domal structures, igneous material is believed to have intruded along interval of dark shale and thin limestone. Both unconformably overlies Madison limestone and underlies Ellis formation. Numerous invertebrate fossils listed from upper limestone member [beds] at several localities in eastern Little Belt Mountains, north flank of Big Snowy Mountains and near Deer Creek in Judith Mountains. G. Girty (written communication) considers age to be both Mississippian and Pennsylvanian.

Summary of Citation: Quadrant

Publication:
Calvert, W.R., 1912, The Electric coal field, Park County,
   Montana, IN Contributions to economic geology, 1910; Part 2,
   Mineral fuels: U.S. Geological Survey Bulletin, 471-E, p.
   406-422

Usage in Publication:
Quadrant formation*

Modifications:	Geologic Province:	Dominant Lithology:
Age modified	Montana folded belt province

Summary:
Is present in extreme southern Park Co, MT just north of Yellowstone National Park in Montana folded belt province. Best exposed in vertical beds at Cinnabar Mountain (sec 31, T8S, R8E). Contains in ascending order: variegated and distinctively red gypsiferous shale; thin platy sandstone; and massive quartzitic sandstone which is locally ripple marked. Measured section reveals 200 ft but thickness may be greater if limestone beds now assigned to underlying Madison limestone are included in the lower Quadrant. No fossils found but is considered correlative with strata in Little Belt and Big Snowy Mountains that yield Mississippian and Pennsylvanian fauna. Upper part believed missing and is overlain disconformably by Late Jurassic Ellis formation. Is considered older than Pennsylvanian or Mississippian? in age.

Summary of Citation: Quadrant

Publication:
Emmons, W.H. and Calkins, F.C., 1913, Geology and ore deposits
   of the Philipsburg quadrangle, Montana: U.S. Geological Survey
   Professional Paper, 78, 271 p., Also, U.S. Geological Survey
   Bulletin 1237.

Usage in Publication:
Quadrant formation*

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Montana folded belt province

Summary:
Present in Philipsburg area, Granite and Deer Lodge Cos, MT in Montana folded belt province. Erosionally overlies Madison limestone and unconformably underlies Jurassic Ellis formation. Has a lower red magnesian limestone and shale member with pale-green nodules and an upper quartzitic member which is subdivided into 2 light-colored, pure, thick-bedded quartzite or quartzitic sandstones separated by a thinner cherty limestone. Measured section of limestone unit of upper member includes dark beds of high grade, oolitic phosphate rock, phosphatic shale, chert and limestone. Elsewhere, interval is mixture of mottled chert with limestone, a middle calcareous sandstone, and black rusty shale at top. Lower member locally metamorphosed to biotite-bearing maroon altered rock; limy beds locally altered to greenish-banded fine-grained rocks; and upper member altered to resistant outcrops. Upper quartzite is less pure than lower, and calcareous near top causing higher porosity and deeper weathering. Geologic map and columnar section. Lower quartzite bed in upper member considered equivalent to Weber quartzite of UT, and upper quartzite bed to Park City formation of UT according to H. Gale. Lower shaly member may correlate with Morgan formation or similar beds in basal Weber of UT. Pennsylvanian faunas identified by G. Girty from lower red shale beds and calcareous beds between quartzites yield Pennsylvanian and Permian? fossils.

Summary of Citation: Quadrant

Publication:
Pardee, J.T., 1913, Some further discoveries of rock phosphate
   in Montana, IN Contributions to economic geology, 1911: U.S.
   Geological Survey Bulletin, 530-F, p. 285-291

Usage in Publication:
Quadrant formation*

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

Summary:
Redescribed to include thin beds of potentially minable high-grade phosphate in western MT in Montana folded belt province. Phosphate closely associated with (usually overlain by) limy or sandy chert. Float of phosphate-bearing units recognized by oolitic texture, thin bluish-white coating and greater heaviness [density?]. Phosphate beds overlie a few feet of limy shale that separate phosphate rock from the pure, massive quartzite member. Lower part contains red shale. Beds are generally steeply tilted; in as much as 700 ft thick. Generalized measured sections in Garnet Range area (central Powell Co), Elliston (east Powell Co), Phillipsburg (southeast Granite Co), and near Cardwell (northern Madison Co). Overlies Madison limestone; unconformably underlies Ellis formation. Is considered Pennsylvanian in age.

Summary of Citation: Quadrant

Publication:
Barnett, V.H., 1917, Geology of the Hound Creek district of the
   Great Falls coal field, Cascade County, Montana: U.S. Geological
   Survey Bulletin, 641, pt. 2, p. 215-231

Usage in Publication:
Quadrant formation*

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

Summary:
Is mapped south of Great Falls in the Hound Creek District, southern Cascade and extreme northwest Meagher Cos, MT in Montana folded belt province and Sweetgrass arch. Although missing in southern part of Great Falls coal field (Fisher, 1909), measured section in sec 34, T17N, R3E, southern Cascade Co shows about 190 ft of exposed Quadrant. Fossiliferous in upper part. Shale of lower part rests abruptly on Madison limestone; has concealed contact with overlying Ellis formation. Is doubtfully assigned to Pennsylvanian Period, following G. Girty (written communication).

Summary of Citation: Quadrant

Publication:
Pardee, J.T., 1917, The Garrison and Phillipsburg phosphate
   fields, Montana, IN Contributions to economic geology, 1916;
   Part 1, Metals and nonmetals except fuels: U.S. Geological
   Survey Bulletin, 640-K, p. K195-K228

Usage in Publication:
Quadrant quartzite*

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

Summary:
Previously named Quadrant formation in Phillipsburg folio 10 mi to the south; now called Quadrant? quartzite in Garrison phosphate field, Garnet Range in western Powell and northeastern Granite Cos, MT in Montana folded belt province. Revised to exclude beds above lower quartzite of upper member as originally shown by Pardee (1913); beds excluded now assigned to Phosphoria formation of southeastern ID. In Phillipsburg phosphate field, limestone that overlies lower quartzite is tentatively included with Quadrant. Lower shale member unconformably? overlies Madison limestone where locally, weathering of red and ocher shales stains underlying Madison. Upper quartzite is resistant and is directly overlain by phosphatic portion of Phosphoria formation in Garrison field. Geologic map and generalized stratigraphic sections. Is assigned to Pennsylvanian? Period.

Summary of Citation: Quadrant

Publication:
Condit, D.D., 1919, Relations of late Paleozoic and early Mesozoic
   formations of southwestern Montana and adjacent parts of
   Wyoming, IN Shorter contributions to general geology, 1918:
   U.S. Geological Survey Professional Paper, 120-F, p.
   F111-F121

Usage in Publication:
Quadrant quartzite*

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Montana folded belt province Yellowstone province

Summary:
Is present in southwestern MT in Montana folded belt province and in Yellowstone province, northwestern WY. Consists of a variably thick, basal sandy and slightly calcareous red shale member; a middle carbonaceous shale and fossiliferous limestone member that is locally absent but may thicken to 250 ft; and an overlying quartzitic sandstone interbedded with minor sandy dolomitic or thin, clayey limestone. Upper unit is locally cherty and may be sparsely fossiliferous. Average thickness exceeds 300 ft. Is thickest in Snowcrest Mountains where unit is nearly 1000 ft. Columnar and measured sections. Overlies Madison limestone and unconformably underlies rocks equivalent to part of Park City and Phosphoria formations (formerly considered Teton formation). Lower part correlates with Amsden formation of WY. Is of Late Mississippian and Pennsylvanian age.

Summary of Citation: Quadrant

Publication:
Freeman, W.O., 1922, Oil in the Quadrant formation in Montana:
   Engineering and Mining Journal, v. 113, no. 19, p. 825-827

Usage in Publication:
Quadrant formation

Modifications:	Geologic Province:	Dominant Lithology:
Revised Areal limits	Central Montana uplift Williston basin

Summary:
Revised to include Kibbey sandstone (base), Otter shales, Tyler sandstone (new), gray shale, Alaska Bench limestone (new), and black shale (part) (top) in central MT, Central Montana uplift. Locally used [unranked] nomenclature presented because author suggests WY names--Tensleep, Embor, and Chugwater--not be applied to Quadrant beds of mid-MT. Present as probable oil source for younger rocks at Cat Creek field, Petroleum Co, in the Williston basin. Also contains possible reservoir rocks to be tested in eastern third of MT. Wide variability in lithology and thickness reported from well logs around and east of Big Snowy Mountains. Not present near: Stockett and Sand Coulee in north half of Front Range of the Montana Rockies [disturbed belt], and in Little Rocky Mountains (except for few ft of shale). Not mappable north of latitude of Missouri River. Correlates with Tensleep formation of WY. Measured sections. Overlies Madison limestone and unconformably underlies Ellis formation. Fossils from lower part closely resemble Mississippian fossils. Generally regarded as Pennsylvanian or Late Carboniferous in age. Part may be Permo-Carboniferous.

Summary of Citation: Quadrant

Publication:
Hammer, A.A. and Lloyd, A.M., 1926, Notes on the Quadrant
   formation of east-central Montana: American Association of
   Petroleum Geologists Bulletin, v. 10, no. 10, p. 986-996

Usage in Publication:
Quadrant formation

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Overview	Central Montana uplift Williston basin

Summary:
Present in east-central MT, Central Montana uplift and Williston basin. Lies east of Bridger Range and as far east as any data [wells] are available. Measured section in secs 2 and 11, T10N, R22E located just southeast of Big Snowy and Little Snowy Mountains in Fergus Co. Upper unit, or rocks assigned to "possible Quadrant" contains reddish sandstone, limestone, conglomerate, and minor sandy shale. Lower unit, or rocks assigned to "definitely Quadrant" are capped by Pottsville-age (Early Pennsylvanian) fossiliferous limestone. Chesterian (Late Mississippian) fossils identified in beds 400 ft below Pottsville beds. Author states that sandstones of this interval (below Pottsville beds) very similar to sandstone phase of Tensleep of southern MT and WY. Interval below Chester beds contains shale, limestone, and green shales--forms widespread marker bed. Cross sections, isopach map, and location data. Mississippian sandstones, red shales, and limestones about 200 ft thick that overlie Madison thought to be equivalent to Amsden formation. Age refined to Early Pennsylvanian and half assignable to Chesterian age (to top of Madison). In Big Snowy Mountains, series referred to as Quadrant not found in southern MT, WY, and believed absent in western MT. [Doesn't resemble mostly sandy beds of Yellowstone province]. Unconformably overlain by Chugwater red beds in south and Ellis formation in north. Absent north of Missouri River.

Summary of Citation: Quadrant

Publication:
Reeves, Frank, 1931, Geology of the Big Snowy Mountains, Montana,
   IN Shorter contributions to general geology, 1930: U.S.
   Geological Survey Professional Paper, 165-D, p. D135-D149

Usage in Publication:
Quadrant formation*

Modifications:	Geologic Province:	Dominant Lithology:
Overview Revised	Central Montana uplift

Summary:
In Big Snowy Mountains, Central Montana uplift, is divided into four informal units (descending): thin-bedded, fossiliferous limestone with red shale (100-200 ft); red, brown, and black sandstones and shales (300-400 ft); variegated limy shale with thin limestone beds and prominent green shale bed in middle (500 ft); basal yellow sandstone, sandy shale, and lenticular gypsum beds. Affiliated units Tyler, Otter, Kibbey, and Alaska Bench not used. Detailed description of northward pinchout beneath overlying Ellis formation. Conformably overlies Madison limestone. Detailed measured sections. Age refined from Carboniferous to mostly Mississippian except for highest beds of limestone at top of Quadrant which contain Pottsville fauna. Should not be correlated with Tensleep sandstone and Embor formation of southern MT and northern WY. Upper limestone beds probably equivalent to Amsden and is somewhat similar in lithology to basal Quadrant in southwest MT (also considered Amsden equivalent). Greater part of Quadrant in central MT older than Quadrant of southern MT, and Tensleep and Amsden of southern MT and WY.

Summary of Citation: Quadrant

Publication:
Scott, H.W., 1935, Some Carboniferous stratigraphy in Montana
   and northwestern Wyoming: Journal of Geology, v. 43, no. 8,
   pt. 2, p. 1011-1032

Usage in Publication:
Quadrant formation

Modifications:	Geologic Province:	Dominant Lithology:
Not used Revised Areal limits

Summary:
Redescription of type [never designated] section of Iddings and Weed (1899) to include Amsden formation in basal part at southeast corner of Quadrant Mountain, Yellowstone Park, MT in Yellowstone province. Basal talus unit (no. 13 of Iddings and Weed, 1899) now reassigned to Amsden on basis of lithostratigraphic correlation with Amsden strata in Bighorn Mountains. At Quadrant Mountain is restricted to rocks lying conformably below Phosphoria formation and unconformably above Amsden formation. Grades eastward into Tensleep sandstone. Name used working northward and eastward [but west of Bighorn basin] from Quadrant Mountain. In Central Montana uplift, Quadrant formation as revised is absent and thus not used. In central MT, above Madison limestone and below Ellis formation, the upper limestone unit of Reeves (1931)--also Alaska Bench limestone of Freeman (1922)--is reassigned to Amsden. Subjacent unnamed units of Reeves, or previously unranked units Tyler sandstone of Freeman (1922), Otter shale of Weed (1899), and Kibbey sandstone of Weed (1899) reassigned to Big Snowy Group (new). Is of marine origin. Age tentatively considered Pennsylvanian on basis of sponge spicules collected from Tobacco Root Mountains, MT and by stratigraphic equivalence to Pennsylvanian Tensleep. Regional stratigraphic diagrams, measured section, history of nomenclature chart.

Summary of Citation: Quadrant

Publication:
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.

Usage in Publication:
Quadrant Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Overview Age modified	Idaho Mountains province Snake River basin

Summary:
Is a unit in the central Beaverhead Mountains shown as of Late Mississippian (Chesterian) to Early Permian (Wolfcampian) age that correlates with the Bluebird Mountain Formation (new), the Snaky Canyon Formation (new) and its newly named Bloom (base), Gallagher Peak Sandstone, and Juniper Gulch Members. Beaverhead Mountains extend into the Snake River basin and Idaho Mountains province.

Summary of Citation: Quadrant

Publication:
Sando, W.J., Sandberg, C.A. and Perry, W.J., Jr., 1985, Revision
   of Mississippian stratigraphy, northern Tendoy Mountains,
   southwest Montana, IN Sando, W.J., ed., Mississippian and
   Pennsylvanian stratigraphy in southwest Montana and adjacent
   Idaho: U.S. Geological Survey Bulletin, 1656-A, p. A1-A10

Usage in Publication:
Quadrant Sandstone*

Modifications:	Geologic Province:	Dominant Lithology:
Age modified	Montana folded belt province

Summary:
Overlies newly named Conover Ranch Formation of Snowcrest Range Group in northern Tendoy Mountains, MT in the Montana folded belt province. Conodonts of latest Mississippian age found in lower 7 m. Age of formation ranges from Late Mississippian to Pennsylvanian.

Summary of Citation: Quadrant

Publication:
Wardlaw, B.R. and Pecora, W.C., 1985, New Mississippian-Pennsylvanian
   stratigraphic units in southwest Montana and adjacent Idaho,
   IN Sando, W.J., ed., Mississippian and Pennsylvanian stratigraphy
   in southwest Montana and adjacent Idaho: U.S. Geological
   Survey Bulletin, 1656-B, p. B1-B9

Usage in Publication:
Quadrant Sandstone*

Modifications:	Geologic Province:	Dominant Lithology:
Age modified	Montana folded belt province

Summary:
The lowest beds vary in age from latest Mississippian to Early Pennsylvanian, generally becoming younger northeastward in southwest MT, Montana folded belt province. Overlies and intertongues with Conover Ranch Formation (new) of Snowcrest Range Group (new). Overlies Lombard Limestone (new) of Snowcrest Range. Correlation chart.

Summary of Citation: Quadrant

Publication:
Verville, G.J., Sanderson, G.A., Baesemann, J.F. and Hampton,
   G.L., III, 1990, Pennsylvanian fusulinids from the Beaverhead
   Mountains, Morrison Lake area, Beaverhead County, Montana:
   The Mountain Geologist, v. 27, no. 2, p. 47-55

Usage in Publication:
Quadrant Formation

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

Summary:
Early Desmoinesian fusulinid WEDEKINDELLINA sp. collected from about 125 ft below top of Quadrant about one mile east of Garfield Peak, in Beaverhead Mountains, Beaverhead Co, MT, Montana folded belt province. Authors consider Garfield Peak-Lima Peaks as southern end of Tendoy Mountains rather than an eastern spur of Beaverhead Mountains. Weart (1950, unpub. PhD thesis) reports FUSULINA sp. and WEDEKINDELLINA sp. 171 and 380 ft below top of Quadrant in Big Sheep Creek Canyon, in Tendoy Mountains, Beaverhead Co, MT. These fossils establish that Quadrant is no younger than early Desmoinesian in this part of southwest MT. Other workers have speculated that age of Quadrant in this area may be as young as Permian. Authors propose that contact with overlying Phosphoria Formation is probably disconformable, rather than conformable as suggested by Sloss and Moritz (1951, AAPG Bull, p. 2135-2169), and rocks of late Desmoinesian to Wolfcampian age are missing or very thin. Quadrant restricted from area of Morrison Lake, in Beaverhead Mountains, Beaverhead Co; here, interval is assigned to Snaky Canyon Formation.