Named as lower of two members in Niobrara formation for exposures in the Sage Breaks, T46N, R63W, Weston Co, WY in Powder River basin. Gray noncalcareous mudstone and shale with many large light-gray calcareous septarian concretions. Fossils scarce but consist of marine species. Commonly forms scarps and buttes. Included in Carlile of previous reports. Thickness 250-325 ft. Overlies Turner sandy member (new) of Carlile shale, underlies Beaver Creek chalky member (new) of Niobrara formation. Type section not given. Crops out on west side of Black Hills in northeastern WY and southeastern MT in Williston and Powder River basins. Samples of Upper Cretaceous claystone, shale, and marl, including a sample of Beaver Creek chalky member, compared for their mineralogy, chemical composition, grain size, density, porosity, fissility, and bedding laminations. Late Cretaceous in age.

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

Lithologic term dropped from name. Removed from Niobrara formation and reassigned as uppermost member of Carlile shale on western side of Black Hills, northeastern WY and southeastern MT, Powder River and Williston basins. Consists of black-gray shale containing an abundance of gray-weathering septarian concretions. Thickness 195 ft, 6 mi north of Belle Fourche, Butte Co, SD, Williston basin. Underlain by Turner sandy member; overlain by Niobrara formation (as restricted). Discusses correlations, lists representative fossils, and shows faunal zonation. Late Cretaceous (latest Turonian) in age.

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

A member of Carlile shale. Is only 70 ft thick 9 mi south-southeast of Rapid City, Pennington Co, SD in Williston basin--in contrast to about 200 ft 60 mi northwestward at Belle Fourche, Butte Co, SD, and 300 ft farther northwest in Carter Co, MT, all in Williston basin. In all of the areas is conformable with the [underlying] Turner sandy member, and is disconformable with the chalky beds of the [overlying] Niobrara formation. Late Cretaceous (Turonian) in age.

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

Member of Carlile shale. Lists index fossils and discusses their stratigraphic and geographic distribution in the Powder River basin [including Carter Co, MT in adjacent part of Williston basin]. Late Cretaceous (Turonian) in age.

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

Mapped as upper member of three members of Carlile shale in western and eastern Crook Co, WY, Powder River basin and west-central and southwestern Butte Co, SD, Williston basin. Carlile assigned to Colorado group. Consists of dark-gray noncalcareous shale containing many limestone concretions. Near Belle Fourche, SD, unit is 195 ft thick; thickness increases to northwest to 300 ft. Forms prominent outcrops. Measured section; geologic map; columnar section. Overlies Turner sandy member of Carlile; underlies Niobrara formation. Late Cretaceous age.

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

Mapped as uppermost of three members of Carlile Shale. Outcrops as narrow band striking northwest along Black Hills monocline, Powder River basin. [Also mapped in nearby Fanny Peak quad (Brobst, Epstein, 1963, USGS Bull. 1063-I), Inyan Kara Mountain quad (Mapel, Pillmore, 1963, USGS Bull. 1121-M), and Newcastle area (Maple, Pillmore, 1963, USGS Bull. 1141-N.] Consists of grayish-black shale that contains several beds of septarian limestone concretions, most of which range from 1-3 ft long. Thickness is about 290 ft. Measured section; generalized stratigraphic column. Overlies Turner Sandy Member of Carlile; underlies Niobrara Formation.

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

Mapped as upper of three members (lower member is unnamed) of Carlile shale along flanks of Black Hills uplift, WY and MT, Powder River basin. Consists of gray noncalcareous shale with numerous beds of light-gray-weathering septarian limestone concretions. Thickness is 200-300 ft. Fossils scarce and poorly preserved; fossil list. Measured sections; stratigraphic chart. Overlies Turner sandy member of Carlile; conformably underlies Niobrara formation. Late Cretaceous age.

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

Is upper member of Carlile Shale. Sage Breaks is normally considered to be late Turonian in age. However upper part may be Coniacian to early Santonian age in Black Hills region, Weston Co, WY, Powder River basin. Age assignment is based on ranges of planktonic forams found in Sage Breaks and the strong indication of lateral equivalency with Fort Hays Limestone Member of Niobrara Formation. Fig. 3 shows stratigraphic distribution and relative abundance of microfossils; microfauna consists of benthonic and planktonic foraminifers, ostracods, and one radiolarian. Planktonic species include ARCHAEOGLOBIGERINA CRETACEA, which does not occur in rocks older than Coniacian in Gulf Coast area and is common only in Santonian or younger rocks; and HASTIGERINOIDES SUBDIGITATA, that occurs in upper one foot of Sage Breaks and is considered to be early Santonian to early Campanian age. Measured sections.

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

Assigned to Cody Shale (revised) on various cross sections in western Powder River basin and eastern Wind River basin. As shown on four cross sections (OC-73 to OC-76) Sage Breaks is assigned to Cody Shale in central Johnson, southwesternmost Campbell, and western two-thirds of Converse Cos, WY, western Powder River basin and in eastern Natrona Co, WY, Wind River basin. Elsewhere in WY portion of Powder River basin, Sage Breaks is member of Carlile Shale. Where Sage Breaks is member of Cody, conformably overlies Wall Creek Sandstone Member of Frontier Formation and conformably (in places unconformably) underlies Niobrara Member (revised) of Cody. Where Sage Breaks is member of Carlile, conformably overlies Turner Sandy Member of Carlile and conformably (in places unconformably) underlies Niobrara Formation. Late Cretaceous age.

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

Assigned formation rank (Sage Breaks Shale) in northwest Carbon Co, WY, Greater Green River basin. Here unit overlies Frontier Formation and underlies Niobrara Formation. Assigned as lower member of Cody Shale in Natrona Co, WY, in Wind River basin and as upper member of Carlile Shale in Weston Co, WY, eastern Powder River basin. Representative electric log; cross section. On correlation chart Sage Breaks shown to be late Turonian to Santonian age.

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

Extends from surface to depth of 85 m in cored borehole in Osage oilfield on west flank of Black Hills, SWNW sec 30, T46N, R63W, Weston Co, WY, Powder River basin. Is upper of three members of Carlile Shale. Consists of calcareous and noncalcareous shale with scattered limestone concretions. Fig. 1 shows ranges of bivalves and ammonites from cores. Fossils representing zones SCAPHITES CORVENSIS (upper Turonian) to CREMNOCERAMUS? WALTERSDORFENSIS (lower Coniacian) are present. Overlies Turner Sandy Member of Carlile. Fossil list.

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

Raised in stratigraphic rank to Sage Breaks Shale in subsurface of western Powder River basin in Converse, Niobrara, Johnson, western Campbell, and Sheridan Cos, WY, and Big Horn Co, MT where it conformably overlies Frontier Formation and unconformably underlies Niobrara Formation. Eastward in the subsurface of the Powder River basin in Weston, eastern Niobrara, eastern Campbell, and Crook Cos, WY, and Powder River Co, MT, and in the Williston basin of Carter Co, MT, Sage Breaks is assigned as Sage Breaks Member, upper member of Carlile Shale where it overlies Turner Sandy Member of Carlile and unconformably underlies Niobrara Formation. Late Cretaceous age. [Name used on 22 cross sections in this OC series.]

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

Uppermost of three members of Carlile Shale on eastern flank of Powder River basin and lowermost of three members of Cody Shale on southwestern flank of Powder River basin. On eastern flank: 1) Unit rarely crops out though where it does it forms gentle slopes, flats, and valleys. 2) Consists of medium-dark-gray to grayish-black, noncalcareous shale that encloses several conspicuous layers of closely spaced concretions. 3) Conformably overlies Turner Sandy Member of Carlile; and in southern part of basin disconformably underlies Niobrara Formation. 4) In outcrop in Black Hills, thickness ranges from 60-95 m, 38 m in eastern Niobrara Co, and in subsurface thickness ranges from less than 30 m to more than 90 m. In southwestern part of basin: 1) Consists mostly of poorly indurated, noncalcareous, slightly silty shale. 2) Overlies and interfingers with Wall Creek Member of Frontier Formation; conformably underlies Niobrara Member of Cody; in south-central part of basin disconformably underlies Niobrara Member. 3) Thickness ranges from 94 m in south-central Johnson and west-central Converse Cos to 53 m and less in southern Campbell Co. Measured sections; geophysical logs; stratigraphic and biostratigraphic charts; cross sections. Marine molluscan fossils are latest Turonian to middle Coniacian age; outcrops in Weston Co contain late Turonian to possibly Santonian Foraminifera (Evetts, 1976).

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