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  • Usage in publication:
    • Fortymile granite*
  • Modifications:
    • Named
  • Dominant lithology:
    • Granite
    • Schist
  • AAPG geologic province:
    • Alaska East-Central region
Publication:

Spurr, J.E., 1898, Geology of the Yukon gold district, Alaska, IN Walcott, C.D., Eighteenth annual report of the United States Geological Survey to the Secretary of the Interior, 1896-1897; Part III, Economic geology: U.S. Geological Survey Annual Report, 18, pt. 3, p. 87-392.


Summary:

Occurs in belt several mi wide on Miller Creek trail between Fortymile and Sixtymile Creeks, Fortymile district, Yukon River, east-central AK. Rock is sometimes massive but usually gneissic or schistose structure and occasionally is altered into mica-schists. Underlies Birch Creek series (new). Is considered "by analogy with fundamental granites in other regions" to be Archean age.

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 ([ ]).

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