Birdhead sandstone member of Thermopolis shale [of Colorado group]. Rim-forming sandstone 0 to 15 feet thick, lying about 130 feet above base of Thermopolis shale in Bighorn County and Crow Indian Reservation, Montana. Birdhead Coulee cuts across the sandstone in T. 3 S., R. 27 E., Yellowstone County, central southern Montana. Age is Late Cretaceous.

Source: US geologic names lexicon (USGS Bull. 896, p. 191).

Pg. 43. Birdhead sandstone member of Cloverly formation. Tentatively correlated with Newcastle sandstone of Black Hills and Powder River basin areas and Muddy sandstone of Bighorn basin and included in Thermopolis shale by Thom and others (1935), is top of Cloverly formation as herein described. Member is mostly fine-grained sandstone, in part silty and argillaceous. Commonly 10 to 15 feet thick. Not sharply set off from underlying beds; underlies zone of black shale with hard ironstone concretions, this shale is basal unit of Thermopolis shale. In some places a thin (few feet thick) unnamed sandstone and shale unit, assigned to uppermost Cloverly, occupies interval between Birdhead and Thermopolis. Age is Early Cretaceous. Report includes geologic map, columnar section, measured sections.

Source: US geologic names lexicon (USGS Bull. 1200, p. 347); supplemental information from GNU records (USGS DDS-6; Denver GNULEX).

Revised the Birdhead Sandstone Member reassigned to the top of the Skull Creek Shale from central MT, [Central Montana uplift] to the eastern Bighorn Mountains of WY in the Powder River basin. described as a lenticular sandstone Is recognized in this report over a larger area than in previous studies. Overlies Skull Creek undivided. Disconformably underlies lower part of Mowry Shale. Correlative lenticular sandstone bodies are called: "J" sandstone in southeast WY; Newcastle Sandstone Member in the Black Hills, Williston basin, and northeastern Powder River basin; Muddy Sandstone at all these localities. Newcastle is restricted to the three areas listed above. The "J" and Muddy are not used in this area. Nomenclature chart. Cross sections. Of late Albian, Early Cretaceous age.

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

Birdhead Sandstone Member of Cloverly Formation as used by Richards (1955, USGS Bull. 1026, USGS Bull. 1026, p. 42-45) in Bighorn Canyon-Hardin area, south-central Montana, abandoned. Rocks now included in Fall River Sandstone. [Adopted by the USGS (see Changes in stratigraphic nomenclature, 1975, USGS Bull. 1422-A, p. A4-A5, A66-A67).]

Source: Changes in stratigraphic nomenclature, 1975 (USGS Bull. 1422-A, p. A4-A5, A66-A67).