Usage:
John Day Formation (OR*)
Subunits:
(alphabetical) --all in OR: Big Basin Member, Deep Creek tuff [unranked, informal], Haystack Valley Member, Kimberly Member, Turtle Cove Member.
Geologic age:
Tertiary (late Eocene to early Miocene; late Duchesnean to early Hemingfordian NALMA)*
Type section, locality, area and/or origin of name:
Typical exposures are along John Day River. Well exposed in Picture Gorge, north-central OR (Marsh, 1875).
AAPG geologic province:
Eastern Columbia 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 ([ ]).