- Usage in publication:
-
- Spectacle Formation*
- Modifications:
-
- Named
- Biostratigraphic dating
- Dominant lithology:
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- Conglomerate
- Limestone
- Siltstone
- AAPG geologic province:
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- Okanogan province
Summary:
Named for Spectacle Lake. Type locality is area between Wannacut Lake on east and Palmer Mountain on west, Loomis 15' quad, Okanogan Co, WA. Is basal unit of Anarchist Group. Thickness is at least 15,000 ft. Consists of metamorphosed interbedded sharpstone conglomerate, limestone, graywacke, siltstone, and black slate. Divided into conglomerate-free and conglomerate-bearing members. Includes limestone bed ranging from 100 to 150 ft thick but locally as much as 2,500 ft thick with fossils of brachiopods, pelecypods, and gastropods, identified by J.T. Dutro, Jr. and E.L. Yochelson of USGS. Base not exposed. Conformably underlies Bullfrog Mountain Formation (new) also of Anarchist Group. Age is considered Late(?) Permian based on brachiopods.
Source: 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 ([ ]).