- Usage in publication:
-
- Bouchard formation*
- Modifications:
-
- Original reference
- Dominant lithology:
-
- Quartzite
- Argillite
- AAPG geologic province:
-
- Northern Rocky Mountain region
Summary:
Pg. 567-568, pl. 28. Bouchard formation. Olive-gray, olive-brown thin- to medium-bedded sericitic quartzite and interbedded clark-olive-gray to olive-black argillite more abundant near bottom and top of section. A few beds of vitreous white quartzite and clark-gray fissile shale. Weathers rusty brown to olive drab. Thickness about 4,000 feet. Conformably overlies Sloway formation (new); unconformably underlies vitreous quartzite of Middle Cambrian age. Age is Precambrian (Belt).
Type section: in secs. 24 and 25, T. 16 N., R. 26 W., [Superior 15-min quadrangle], Mineral Co., northwestern MT. Named from exposures near Bouchard Lake, in sec. 23, T. 17 N., R. 27 W., St. Regis-Superior area, [Superior 15-min quadrangle], Mineral Co., northwestern MT.
Source: US geologic names lexicon (USGS Bull. 1200, p. 438).
- Usage in publication:
-
- Bouchard Formationâ€
- Modifications:
-
- Abandoned
- AAPG geologic province:
-
- Northern Rocky Mountain region
Summary:
†Bouchard Formation of Missoula Group of Belt Supergroup abandoned. Replaced with Garnet Range Formation of Missoula Group.
Source: Changes in stratigraphic nomenclature, 1977 (USGS Bull. 1457-A, p. A6-A7).
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 ([ ]).