Arnheim Formation (OH,TN*)
Arnheim Shale (OH*)
Arnheim Formation of Cincinnati group [informal] (OH)
(Cincinnati group considered informal by the OH Geol. Survey. The rank or lithologic term should not be capitalized.)
(ascending): Sunset Member (OH), Oregonia Member (OH).
Late Ordovician (late Maysvillian to Richmondian)*
Named from Arnheim, Brown Co., southwestern OH (US geologic names lexicons, USGS Bull. 896, 1200).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.
"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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).