Pg. 93-94, 253-254, figs. 2, 11. Bar B formation of Magdalena group. Consists dominantly of thin-bedded limestone and shale in alternating thin intervals. Cherty and noncherty limestone present. Chert commonly mottled and weathered tan or yellowish-brown. Uppermost beds intercalated with reddish-brown siltstone, limestone conglomerate, and calcareous sandstone through interval of about 50 feet. Comprises upper third of group and is 339 feet thick at type section. Underlies Abo formation with transitional contact (locally contact is irregular or divergent); conformably overlies Nakaye formation (new). Whereas 80 percent of Nakaye formation is limestone and remainder shale, ratio is nearly reversed in the Bar B formation. Resembles Red House formation (new), the lower formation of Magdalena group and appears to have originated in a similar sedimentary environment. Fossiliferous (abundant bryozoans). Age is Pennsylvanian or Permian.
Type section: South Ridge section, Caballo Mountains, in sec. 10, T. 15 S., R. 4 W., Sierra Co., NM. Named from Bar B Draw east of Blue Mountain where, near head of draw, formation is widely exposed.

Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 212-213); supplemental information from GNU records (USGS DDS-6; Denver GNULEX).

Bar B Formation of Magdalena Group. In Caballo Mountains, south-central Sierra County, New Mexico, is upper formation of Magdalena. Upper and lower boundaries not well defined. Occurs above Nakaye Formation of Magdalena; overlying unit not stated. Shown on correlation chart generally equivalent to: Panther Seep Formation of San Andres Mountains, eastern Sierra County; basal Beeman and uppermost Holder Formations of Magdalena Group in Sacramento Mountains, northern Otero County, New Mexico; uppermost Los Moyos Limestone and Wild Cow Formation of Madera Group in Manzano Mountains, western Torrence County, New Mexico. Age is Late Pennsylvanian (Missourian and Virgilian).

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

Bar B Formation of Magdalena Group. Present in Mud Springs Mountains, Sierra County, New Mexico. Occurs above Nakaye Formation and below Permian Bursum Formation (both of Magdalena). Age is Pennsylvanian.

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

Pg. 106-107 (fig. 3, strat. chart). Bar B Formation of Madera Group. Previously a formation of Magdalena Group [use of Magdalena Group discarded]. Recognized in southwestern New Mexico (Mud Springs, Caballo, and Fra Cristobal Mountains). Overlies Gray Mesa Limestone of Madera Group. Underlies Abo Formation; in Mud Springs Mountains, underlies Bursum Formation of Madera Group. Is partly equivalent to Atrasado Formation of Madera Group. Age is late Middle to Late Pennsylvanian (late Desmoinesian to Virgilian).

Source: Publication.