- Usage in publication:
-
- Ramsay Formation*
- Modifications:
-
- Original reference
- Dominant lithology:
-
- Argillite
- Metasiltstone
- Metavolcanics
- AAPG geologic province:
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- Lake Superior region
Summary:
Pg. 6-8, pl. 1 (geol. map). Ramsay Formation. Metamorphosed and generally somewhat schistose siliceous arkosic argillite, micaceous and arkosic siltstone, and volcanic tuff and breccia. Thinly laminated to massive. Thickness at least a few thousand feet. Grades upward into Whiskers Creek Gneiss (new). Intruded by Puritan Quartz Monzonite (new) and Sunset Creek Intrusive Complex (new). Is oldest known stratigraphic rock in region. Age is early Precambrian (Precambrian W); [late Archean].
[Type locality]: exposures extend southward from edge of village of Ramsay along west side of Black River, in SW/4 sec. 13, NW/4 sec. 24, and within area 1,000 ft (330 m) south and west of northeast corner of sec. 23, T. 47 N., R. 46 W., [Bessemer 7.5-min quadrangle], western Gogebic Co., Northern Peninsula, northwestern MI.
Source: Publication; US geologic names lexicon (USGS Bull. 1564, p. 138); ; Changes in stratigraphic nomenclature, 1976 (USGS Bull. 1435-A, p. A86).
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 ([ ]).