First use of name; intent to name not stated and origin of name not stated. No type locality designated. Is basal unit in newly named Tesnus formation, which occurs in the Marathon region, Brewster Co, TX in Permian basin. Tesnus unconformably overlies the newly named Lower Mississippian? Santiago chert. Rough Creek is 865 ft thick, consisting of hard, compact and brittle, dark-green, occasionally black shale; above are sandstone, shale, chert, and a few lenticular layers of conglomerate of the rest of Tesnus formation. In the northwest portion of the Marathon region near the line of the Southern Pacific RR [Brewster Co], it is likely that the Rough Creek shale member has disappeared. Geologic map.

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