No current usage.
(Rocks of †Fork Ridge Sandstone Member of †Mingo Formation (KY*,TN*) reallocated to Breathitt Formation [or Pikeville Formation of Breathitt Group] in KY, and to Slatestone Formation in TN. See Breathitt, Pikeville, and Slatestone.)
late Early to early Middle Pennsylvanian (late Bashkirian to early Moscovian; Westphalian; latest Morrowan to early Atokan)
Named from Fork Ridge, Bell Co., southeastern KY (US geologic names lexicons, USGS Bull. 896, 1200).
Appalachian basin
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).