Usage:
No current usage.
(†Dean Lake Chert Member of Madison Limestone or †Dean Lake Chert (MT-local) considered abandoned.)
Geologic age:
Early Mississippian (Tournaisian; Kinderhookian)
Type section, locality, area and/or origin of name:
Type locality: southeast side of Pentagon Mountain, in SW/4 sec. 14, T. 25 N., R. 14 W., [Pentagon Mountain 7.5-min quadrangle, Flathead Co.], northwestern MT. Named from Dean Lake, a small cirque lake lying at foot of cliffs that form upper part of east side of Pentagon Mountain (Deiss, 1933).
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 ([ ]).