- Usage in publication:
-
- Bell Mountain Rhyolite
- Modifications:
-
- Named
- Dominant lithology:
-
- Rhyolite
- Tuff
- AAPG geologic province:
-
- Midcontinent region
Summary:
Bell Mountain Rhyolite. Unit is part of sequence of Precambrian volcanic rocks associated with Taum Sauk caldera in western part of St. Francois Mountains, southeast Missouri (Midcontinent region). Notable exposures on College Hill, and Bell, Crane, Lee, North Bell, Russell, Taum Sauk, and Wildcat Mountains. Consists of maroon to dark-maroon air-fall tuff containing lapilli and a 2 to 5 m-thick zone containing lithophysae from a few mm to nearly 25 cm in diameter. Thickness 25 m. Overlies Wildcat Mountain Rhyolite (new); underlies Royal Gorge Rhyolite (revised). Age is Precambrian. Report includes geologic map. Unit named and described on stratigraphic column (table 1).
Bell Mountain Rhyolite replaces: Hogan Mountain Rhyolite (Bell, Lee, North Bell, and Wildcat Mountains), Middlebrook Group (College Hill), and Stouts Creek Rhyolite (Crane, Russell, and Taum Sauk Mountains) as mapped by Tolman and Robertson (1969, Missouri Geol. Survey Rpt. Inv., no. 44); upper part of Unit D of tuff of Stouts Creek of Anderson (1970, Missouri Geol. Survey Rpt. Inv., no. 46); and Unit 790 of Berry and Bickford (1972, Bull. Volcanology, v. 36, p. 303-318).
Type section: in SE/4 NE/4 sec. 2, T. 33 N., R. 1 E., Edgehill quadrangle, MO. Named from exposures along crest of Bell and North Bell Mountains, Reynolds and Iron Cos., MO.
Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Bell Mountain Rhyolite
- Modifications:
-
- Revised
- AAPG geologic province:
-
- Midcontinent region
Summary:
Bell Mountain Rhyolite of /Taum Sauk Group (new) of /St. Francois Mountains Volcanic Supergroup. Study area is St. Francois Mountains, southeast Missouri. Overlies Wildcat Mountain Rhyolite and underlies Royal Gorge Rhyolite (both of Taum Sauk). Age is Precambrian Y. Nomenclature listed in table 1.
[Conflicts with nomenclature guidelines (ACSN, 1970; NACSN, 1983, 2005, 2021): name Taum Sauk used for both group and formation within it (Taum Sauk Rhyolite has priority); name St. Francois Mountains applied concurrently to two different units in same area; a [supergroup] name combines a geographic name with the term ["supergroup,"] and no lithic designation is included.]
Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).
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 ([ ]).