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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Fortymile series*
  • Modifications:
    • Named
  • Dominant lithology:
    • Marble
    • Quartzite
    • 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:

Named for exposures along Forty-mile Creek, tributary to Yukon River, east-central AK. Consists of intercalated marbles and quartzites with hornblendic, micaceous, garnetiferous, and sometimes graphitic schists. Thickness can not be given; however it probably is somewhat less than the 25,000-ft thickness of Birch Creek series (new) which it conformably overlies. Underlies Rampart series (new). [Age not given]

Source: GNU records (USGS DDS-6; Menlo GNULEX).


Map showing publication footprint
  • Usage in publication:
    • "Fortymile series"†
  • Modifications:
    • Abandoned
  • AAPG geologic province:
    • Alaska East-Central region
Publication:

Mertie, J.B., Jr., 1930, Geology of the Eagle-Circle district, Alaska: U.S. Geological Survey Bulletin, 816, 168 p., (incl. geologic maps, scale approx. 1:26,000 and 1:250,000)


Summary:

"Fortymile series" of Spurr (1898) abandoned. Its rocks assigned in part to Precambrian Birch Creek schist and in part to the Paleozoic.

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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