Usage:
Fort Duncan Member of Tomstown Formation (MD*,WV*,PA,VA*)
Geologic age:
Early Cambrian*
Type section, locality, area and/or origin of name:
Type section: along C&O Canal, MD side (Washington Co.) of first northward meander of the Potomac River, west of Harpers Ferry, WV (Brezinski, 1992).
AAPG geologic province:
Appalachian basin*
Piedmont-Blue Ridge province*
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 ([ ]).