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Map showing publication footprint
  • Usage in publication:
    • Shellmound Formation*
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
    • Calcarenite
  • AAPG geologic province:
    • Appalachian basin
Publication:

Milici, R.C., and Wedow, Helmuth, Jr., 1977, Upper Ordovician and Silurian stratigraphy in Sequatchie Valley and parts of the adjacent Valley and Ridge, Tennessee: U.S. Geological Survey Professional Paper, 996, 38 p.


Summary:

Shellmound Formation named in the southern Sequatchie Valley area of southeastern TN and northwestern GA. Sequatchie Formation is geographically restricted to the northern part of the Sequatchie Valley. Composed of gray to greenish-gray, fossiliferous, silty glauconitic limestone, overlain by argillaceous limestone, calcisiltite, and calcarenite. Thickness 29 m. Includes Fernvale Member (revised). Overlies Leipers Formation and underlies Rockwood Formation. Age is Late Ordovician.

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


Map showing publication footprint
  • Usage in publication:
    • Shellmound Member
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Appalachian basin
Publication:

Rindsberg, A.K., and Chowns, T.M., 1986, Ringgold Gap; progradational sequences in the Ordovician and Silurian of northwest Georgia, IN Neathery, T.L., ed., Southeastern Section of the Geological Society of America, Centennial field guide: Geological Society of America, Northeastern Section, The Decade of North American Geology (DNAG), Centennial Field Guide, v. 6, p. 159-162.


Summary:

At Ringgold Gap in northwestern GA, Shellmound reduced in rank to Member of Sequatchie Formation. Overlies informal "Ringgold" Member and underlies Mannie Shale Member. Age is Richmondian.

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


Map showing publication footprint
  • Usage in publication:
    • Shellmound Member
  • Modifications:
    • Overview
  • AAPG geologic province:
    • Appalachian basin
Publication:

Chowns, T.M., 1989, Structure and stratigraphy of the Valley and Ridge province in Georgia; Day 1, IN Dallmeyer, R.D., ed., Tectonostratigraphic expression of terrane accretion in the southern Appalachian Orogen; a geotraverse excursion: International Geological Correlation Programme Field Trip Guidebook, July 23-31, 1989, v. 4, p. 1.1-1.19., International Geological Correlation Programme (IGCP) Project No. 233, Terranes in the Circum-Atlantic Paleozoic Orogens


Summary:

The Shellmound Member of the Sequatchie Formation at Ringgold Gap is 16 m thick. Though it contains some red beds, it consists mainly of gray dolomitic siltstones and shales with interbedded bryozoan-brachiopod limestones. Environments range from supratidal to subtidal and suggest a variety of tidal flats with subtidal channels and embayments. The top of the Shellmound Member is truncated by a phosphatic hardground overlain by the Mannie Member. The Shellmound overlies the Ringgold Member of the Sequatchie. Age is Late Ordovician.

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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