- Usage in publication:
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- Bald Mountain gneiss
- Modifications:
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- Original reference
- Dominant lithology:
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- Gneiss
- AAPG geologic province:
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- Blue Mountains province
Summary:
Pg. 105; Univ. Oregon Bull., v. 16, no. 7, p. 105. Bald Mountain gneiss. [Named evidently] for metamorphic rock outcrop on north slope of Bald Mountain [now called Mt. Ireland] along headwaters of north fork of John Day River, Grant County, northeastern Oregon. Covers area less than 15 sq mi. Consists of biotite gneiss embedded in granodiorite. Thought to be oldest known rocks of Blue Mountains, eastern Oregon. Age is Archean(?) (Lindgren, 1900-1901, USGS 22nd Ann. Rpt., pt. 2, p. 594).
Source: US geologic names lexicon (USGS Bull. 896, p. 105); GNU records (USGS DDS-6; Menlo 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 ([ ]).