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  • Usage in publication:
    • Chalk Mountain Rhyolite*
  • Modifications:
    • Age modified
  • AAPG geologic province:
    • Eagle basin
Publication:

Tweto, Ogden, 1974, Geologic map and sections of the Holy Cross quadrangle, Eagle, Lake, Pitkin, and Summit Counties, Colorado: U.S. Geological Survey Miscellaneous Investigations Series Map, I-830, 2 sheets, scale 1:24,000


Summary:

Occurs 2 mi east of this quad in Summit Co, CO in the Eagle basin. Correlated with a map unit called "rhyolite porphyry (Trp)." Has a radiometric age (K-Ar) of 29 m.y. Age, therefore, changed from Eocene to Oligocene.

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 ([ ]).

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