Usage:
Barker Porphyry (MT*)
Geologic age:
early Tertiary (Eocene)*
Type section, locality, area and/or origin of name:
Type locality not stated. Forms Big Baldy Mountain to south of Barker, Little Belt Mountains, central MT; [also forms Barker Mountain, in Fort Benton quadrangle] (Weed, 1899).
AAPG geologic province:
Sweetgrass arch*
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 ([ ]).