- Usage in publication:
-
- Lewis Canyon Rhyolite*
- Modifications:
-
- Named
- Dominant lithology:
-
- Rhyolite
- AAPG geologic province:
-
- Yellowstone province
Summary:
Named for exposures in Lewis Canyon between Lewis Lake and the Snake River, Teton Co, WY in Yellowstone province. Type area established on north side of Glade Creek between Snake River and east end of Grassy Lake Reservoir. Has 30-40 percent conspicuous phenocrysts, including sodic oligoclase, generally 5 mm long and less abundant smaller phenocrysts of quartz, sanidine, clinopyroxene, and opaque oxides. Is about 300 m thick at type. Consists of several (no more than one in a single section) bulbous nonstratiform lava flows. Overlies Huckleberry Ridge Tuff (new) of Yellowstone Group at type and Cretaceous sedimentary rocks elsewhere. Is overlain by Lava Creek Tuff (new) of Yellowstone Group. Is part of the first volcanic cycle of the Yellowstone Plateau sequence and younger than 2.0 m.y. Age has not been determined isotopically. Stratigraphic table; cross section.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Lewis Canyon Rhyolite*
- Modifications:
-
- Geochronologic dating
- AAPG geologic province:
-
- Yellowstone province
Summary:
An age of 900,000 yrs (K-Ar), or a Pleistocene age, obtained on rhyolite in Lewis Canyon in Yellowstone National Park, WY, Yellowstone province.
Source: GNU records (USGS DDS-6; Denver 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 ([ ]).