Usage:
Switchback Shale (MT*)
Geologic age:
Middle to Late Cambrian*
Type section, locality, area and/or origin of name:
Type locality: upper-middle part of the cliffs which form east side of peak 1 mi S. 48 deg. E. of Pentagon Mountain, in NE/4 sec. 23, T. 25 N., R. 12 W., northwestern MT. Named from Switchback Pass, about 0.25 mi south of these cliffs (Deiss, 1933).
Type locality (emended): on ridge east of Kid Mountain and west of cirque on southwest side of Gordon Mountain, in SW/4 sec. 9, T. 19 N., R. 13 W., northern Lewis and Clark Range, [Una Mountain 7.5-min quadrangle, Powell Co.], northwestern MT (Deiss, 1938, 1939).
AAPG geologic province:
Montana folded belt*
North Western Overthrust*
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 ([ ]).