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Geologic Unit: Graptolite Canyon
Map showing publication footprint
  • Usage in publication:
    • Graptolite Canyon Member*
  • Modifications:
    • Named
    • Biostratigraphic dating
  • Dominant lithology:
    • Shale
  • AAPG geologic province:
    • Alaska West-Central region
Publication:

Churkin, Michael, Jr., and Carter, Claire, 1996, Stratigraphy, structure, and graptolites of an Ordovician and Silurian sequence in the Terra Cotta Mountains, Alaska Range, Alaska: U.S. Geological Survey Professional Paper, 1555, 84 p., (incl. geologic maps, scale 1:24,000)


Summary:

Unit is named the Graptolite Canyon Member of the Post River Formation for Graptolite Canyon, McGrath 1:250,000 quad, AK. Consists predominantly of graptolitic shale; also contains banded siliceous mudstone. Conformably overlies the upper siltstone member; conformably underlies the limestone member; both of the Post River Formation. Thickness is about 220 m at type; overall thickness is 300 m. Age is Early Ordovician (Arenig) through middle Early Silurian.

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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