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Geologic Unit: Gilbert
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Map showing publication footprint
  • Usage in publication:
    • Gilbert member
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Cincinnati arch
Publication:

Foerste, A.F., 1912, Strophomena and other fossils from Cincinnatian and Mohawkian horizons, chiefly in Ohio, Indiana, and Kentucky: Denison University, Bulletin of the Scientific Laboratories, v. 17, p. 17-172.


Summary:

Named Gilbert member of McMillan formation. Chiefly dove-colored limestone. Underlain by Tate member; overlain by Mt. Auburn member.

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


Map showing publication footprint
  • Usage in publication:
    • Gilbert Member*
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Cincinnati arch
Publication:

Weir, G.W., Greene, R.C., and Simmons, G.C., 1965, Calloway Creek Limestone and Ashlock and Drakes Formations (Upper Ordovician) in south-central Kentucky, IN Contributions to stratigraphy, 1965: U.S. Geological Survey Bulletin, 1224-D, p. D1-D36.


Summary:

Reassigned as Gilbert Member of Ashlock Formation, "a thin resistant sequence of limestone with partings of limy siltstone. The limestone is bluish to olive gray, aphanitic to medium grained, and in crinkly beds a few inches thick. Gray limy siltstone occurs as partings and seams less than 1 inch thick. The member contains abundant well-preserved megafossils, chiefly brachiopods and bryozoans. About 15 feet thick near Gilbert and ranges from about 10 to 20 feet in thickness." Underlain by Tate Member; overlain by Stingy Creek Member.

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


Map showing publication footprint
  • Usage in publication:
    • Gilbert Member*
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Cincinnati arch
Publication:

Wahlman, G.P., 1992, Middle and Upper Ordovician symmetrical univalved mollusks (Monoplacophora and Bellerophontina) of the Cincinnati arch region, IN Pojeta, John, Jr., ed., Contributions to the Ordovician paleontology of Kentucky and nearby states: U.S. Geological Survey Professional Paper, 1066-O, p. O1-O203.


Summary:

The Gilbert Member of the Ashlock Formation in south-central KY consists of bluish- to olive-gray, fine- to medium-grained limestone occurring in thin, wavy beds that are separated by limy siltstone partings. Fossils include brachiopods and bryozoans. Thickness is 10 to 20 ft. Overlies the Stingy Creek Member and underlies the Terrill Member, both of the Ashlock Formation. The environment of deposition is interpreted to be shallow quiet lagoon.

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


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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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