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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • St. Clair limestone
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Arkoma basin
Publication:

Penrose, A.R.F., Jr., 1891, Manganese, its uses, ores and deposits, IN Arkansas Geological Survey Annual Report, 1887-1892: Arkansas Geological Survey Annual Report, 1887-1892, v. 1, 642 p.


Summary:

Named the St. Clair limestone in northern AR and central eastern OK for St. Clair Springs, Independence Co., AR. Consists of highly crystalline, granular, light-gray, pink, chocolate brown, or purplish-black, fossiliferous limestone. Contains nodules and layers of oxides of manganese and is source of manganese ores. Thickness is 0 to more than 150 feet. Overlies Izard limestone and underlies the Sylamore sandstone or Boone chert. The St. Clair is of Silurian age.

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


Map showing publication footprint
  • Usage in publication:
    • St. Clair Limestone Member*
  • Modifications:
    • Revised
    • Overview
  • AAPG geologic province:
    • Upper Mississippi embayment
    • Illinois basin
Publication:

Harrison, R.W., 1999, Geologic map of the Thebes quadrangle, Missouri and Illinois: U.S. Geological Survey Geologic Quadrangle Map, GQ-1779, scale 1:24,000 [http://ngmdb.usgs.gov/Prodesc/proddesc_19294.htm]


Summary:

Following usage of Thompson (1993) in MO, St. Clair is reduced in rank to St. Clair Limestone Member of Bainbridge Formation in MO and IL (previously used as St. Clair Formation of Bainbridge Group by Illinois Geological Survey). Mapped undivided with Moccasin Springs Member and Seventy-Six Shale Member (not noted during mapping but possibly present). Consists of gray, fine- to medium-grained, locally silty, noncherty limestone. Characteristically contains abundant iron-stained red fossil fragments. Partings of blue-green clay or mudstone are common. Age is Silurian (Niagaran).

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


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).