Usage:
Trowbridge Formation (OR)
Trowbridge Shale (OR*)
Subunits:
(alphabetical) --all in OR: Magill Member, Officer Member, Rosebud Member, Shaw Member.
Geologic age:
Jurassic, Middle*
Type section, locality, area and/or origin of name:
Type area: trends northeast across South Fork Valley along Mowich anticline where beds dip steeply to southeast, Grant Co., OR (Lupher, 1941).
AAPG geologic province:
Blue Mountains 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 ([ ]).