Named as a formation in the Morrow series of the Bendian period. Formerly called Johns Valley shale (term now abandoned). Type locality designated in NE1/4 NE1/4 SE1/4 sec 2, T2S, R12E, Atoka Co, OK in the Ouachita tectonic belt province. Occurs south of the frontal part of the Ouachita Mountains in southern OK. At type locality, consists of a lower boulder bed separated from an upper bouldery shale by two or three beds of calcareous, fossiliferous sandstones; upper bouldery shale overlain by 10-15 ft of jet black, fissile, fossiliferous shale, locally siliceous. Both bouldery shales have exotic boulders of Ordovician limestone. Thickness varies from 400 to 600 ft; in some places, is more than 800 ft. Overlies Union Valley formation; underlies Barnett Hill formation (new), both of the Morrow series of the Bendian period. Foraminifers, ostracodes, conodonts, brachiopods, gastropods, ammonoids. Geologic map. Correlation chart. Of Carboniferous age.

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