St Clair Limestone (geologic formation)

St. Clair Limestone
Stratigraphic range: Silurian
Sheinwoodian–Homerian
~433–427 Ma
TypeFormation Member – Illinois and Missouri
Unit ofBainbridge Group Hunton Megagroup
UnderliesLafferty Limestone in Arkansas and Moccasin Springs Formation in Illinois, Indiana, and Missouri
OverliesBrassfield Limestone in Arkansas and Sexton Creek Limestone in Illinois, Indiana, and Missouri
Lithology
PrimaryLimestone
OtherDolomite
Location
Region
CountryUnited States
Type section
Named forSt. Clair spring, Independence County, Arkansas[1]
Named byRichard Alexander Fullerton Penrose Jr. 1891

The St. Clair Limestone is a geologic unit in Arkansas, and Oklahoma. It is classified as a Geologic Member in Indiana and Missouri. It dates back to the Middle of Silurian period. It is high density, high magnesium dolomitic limestone.[2] It was originally classified as a marble in Oklahoma due to the fact that it would hold a high polish, hence Marble City. It is sold in slabs and as tiles, in a similar manner as marble would be.[3] This unit has many economic uses in Arkansas and Oklahoma. It is used as a construction material, manufacture of quicklime, and manganese deposits are mined as well.[4] The St Clair is designated as a member of the Bainbridge Group in the State of Indiana.[5] In Illinois, Missouri, Arkansas and Oklahoma it is part of the Hunton Megagroup. The St. Clair is the Basal member of the Niagaran Series, making it part of the Tippecanoe sequence. Throughout most of the Southern extent the unit is roughly 10 to 20' thick. Moving northward it thickens to approximately 80 to 100' thick in the Illinois Basin. At its northernmost reaches where it grades in to the Joliet and Racine Formations it is about 150' thick.

  1. ^ Penrose Jr., R.A.F. (1891). "Manganese: its uses, ores, and deposits". Annual Report of the Geological Survey of Arkansas for 1890. 1: 101–102, 112–114, 124–128, 166–203, 214–215.
  2. ^ Schrenk, Steven (September 2017). "The Grey American Limestone that Acts Like a Marble". The Slippery Rock Gazette: 36, 37.
  3. ^ "Saint Clair Limestone - Grey Limestone - StoneContact.com". www.stonecontact.com. Retrieved 2023-12-19.
  4. ^ Ham, W.E.; Dott, R.H.; Burwell, A.L.; Oakes, M.C. (1943). "GEOLOGY AND CHEMICAL COMPOSITION OF THE ST. CLAIR LIMESTONE NEAR MARBLE CITY OKLAHOMA" (PDF). Oklahoma Geological Survey. Retrieved 18 December 2023.
  5. ^ Willman, H. B.; Atherton, Elwood (1975). "Handbook of Illinois Stratigraphy: Illinois State Geological Survey". Handbook of Illinois Stratigraphy: Illinois State Geological Survey. Bulletin 95: 261.