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  • Usage in publication:
    • Red Mountain subgroup [informal]
  • Modifications:
    • Named
  • Dominant lithology:
    • Argillite
    • Siltstone
    • Limestone
  • AAPG geologic province:
    • Cascades province
Publication:

Danner, W.R., 1977, Paleozoic rocks of northwest Washington and adjacent parts of British Columbia, IN Stewart, J.H., Stevens, C.H., and Fritsche, A.E., eds., Paleozoic paleogeography of the western United States; Pacific Coast paleogeography symposium I: Society of Economic Paleontologists and Mineralogists, Pacific Section, Pacific Coast Paleogeography Symposium, Bakersfield, CA, April 22, 1977, 1, p. 481-502.


Summary:

Pg. 489. Red Mountain subgroup [informal] of Chilliwack Group. Consists of lower argillite-siltstone unit (312 to 625 m [825 m?] thick in Washington) and upper limestone unit (1 to 200 m thick) which contains abundant microfauna, brachiopods, bryozoans, and corals. Fusulinids indicate Early Pennsylvanian age for limestone. Overlies Sumas Mountain subgroup [informal] (new); underlies Black Mountain subgroup [informal] (new) (both of Chilliwack Group). Age is Early Pennsylvanian.
Type area: quarry exposures on Red Mountain and Black Mountain, Whatcom Co., WA. Extends north into Chilliwack region of British Columbia.
["Subgroup" not recognized as a formal stratigraphic rank term (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). Considered informal and should not be capitalized.]

Source: US geologic names lexicon (USGS Bull. 1564, p. 140-141); supplemental information from 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 ([ ]).

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