Breathitt Formation is informally elevated to group rank and subdivided into the following eight informal formations: Pocahontas, Bottom Creek, Alvy Creek, Grundy, Pikeville, Hyden, Four Corners, and Princess formations. Bulan shale member is here informally named and assigned to the upper portion of the Four Corners formation. These marine or brackish-water strata overlie the Francis coal zone and underlie the Hindman coal at the top of the formation. [Revisions made in this paper are strongly contested by C. Rice and other USGS scientists who work in this area (oral commun., 9/3/93).]

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

Corr. chart. Bulan shale member (informal) of Four Corners Formation of Breathitt Group. Shale and/or mudstone. Recognized in eastern Kentucky [in Southwestern and Hazard districts]. Lies below the Stoney Fork Member of Princess Formation and above Arnett Member of Four Corners Formation, between the lower Broas (Princess No. 4) and the upper Peach Orchard (Hazard No. 8) coal zones. Correlates with McGhee Gap member, an informal member of Cross Mountain Formation in Tennessee, and the Lowellville (Poverty Run) limestone, an informal, unranked unit in upper part of Pottsville Group in Ohio, Pennsylvania, and Maryland. Age is Middle Pennsylvanian (Westphalian; Atokan).
[Peppers, 1996 (GSA Memoir 188, p. 9, pl.) placed the Princess No. 4 and Hazard No. 8 coals in Westphalian C, TORISPORA SECURIS-T. LAEVIGATA (SL) miospore assemblage zone of western Europe. Eble and others, 2009 (Kentucky Geol. Survey, Spec. Pub. no. 10, ser. XII, fig. 5.2) placed base of Bulan (= Coalburg coal of West Virginia) in lower part of Bolsovian (lower part of Westphalian C) on basis of miospores. Unpublished collections from overlying Stoney Fork Member of Princess Formation in Kentucky, and its equivalents, informal Lake City member of Cross Mountain Formation in Tennessee and Blunt Run (Boggs) limestone of Pottsville Group in Ohio, yielded distinctive conodonts correlative with the marine Aegir bed (=base of Westphalian C) thus shifting the Four Corners, Vowell Mountain, lower part of Cross Mountain, and upper part of Pottsville, downward into Westphalian B (R.G. Stamm, USGS, pers. commun., Oct. 17, 2013).]
[See also Chesnut, 1997 (revised Oct. 12, 1999), Stratigraphy of the coal-bearing strata of the Eastern Kentucky coal field, available online through the Kentucky Geol. Survey (http://www.uky.edu/KGS/coal/coalcorrel.htm).]

Source: Publication.