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- Usage in publication:
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- Glenn Creek shale member
- Modifications:
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- Original reference
- Dominant lithology:
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- Shale
- Limestone
- AAPG geologic province:
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- Montana folded belt
Summary:
Pg. 42 and passim. Glenn Creek shale member of Jefferson limestone. Recognized in northwestern Montana. Underlies Lake limestone and overlies White Ridge limestone; all members of Jefferson limestone. Thickest (66 feet) at type locality on White Ridge; thinnest (7 feet) in Nannie basin region. Type locality on south side of southwestern peak of White Ridge, [Slategoat Mountain 7.5-min quadrangle, Lewis and Clark County, northwestern Montana], where it consists of (descending): (1) 31 feet of dull- and brighter-red calcareous shale with several beds (up to 14 inches thick) of gray argillaceous limestone, and at top thinner bedded very argillaceous lavender-red limestone; (2) 20 feet of thin-bedded red clay shale with green-gray fissile shale in upper 2 feet; (3) 8 feet of dull-red thick-bedded calcareous shale and shaly argillaceous red-gray limestone. Named for Glenn Creek, [Saypo quadrangle, Lewis and Clark County, northwestern Montana], whose middle branch heads at eastern base of White Ridge. On Saypo topographic sheet the names Glenn Creek and Moose Creek have been interchanged. Age is Middle Devonian.
Source: US geologic names lexicon (USGS Bull. 896, p. 828-829).
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 ([ ]).