St. Louis Limestone

The St. Louis Limestone is a large geologic formation covering a wide area of the midwest of the United States. It is named after an exposure at St. Louis, Missouri. It consists of sedimentary limestone with scattered chert beds, including the heavily chertified Lost River Chert Bed in the Horse Cave Member. It is exposed at the surface through western Kentucky and Middle Tennessee, including the city of Clarksville, Tennessee. The limestone deposit is Mississippian in age, in the Meramecian series, roughly 330-340 million years old.

St. Louis Limestone Stratigraphic range: Mississippian Sub-period
Rock anhydrite (St. Louis Limestone; subsurface gypsum mine in Martin County, Indiana)
Type	Geological formation
Unit of	Blue River Group
Sub-units	Dover Chert, Horse Cave Member, Sisson Member
Underlies	Ste. Genevieve Limestone
Overlies	Salem Formation[1]
Thickness	up to 100 feet (30 m)[2]
Lithology
Primary	Limestone
Other	Shale, chert[2]
Location
Region	Illinois, Indiana, Tennessee, Kentucky and Missouri
Country	United States
Type section
Named for	St. Louis, Missouri[1]
Named by	Englemann
Year defined	1847

Geological map of Mammoth Cave National Park, incl. St. Louis Limestone

Outcrops of the St. Louis Limestone near Frenchburg, Kentucky

Fossils commonly found in the St. Louis include the rugosan corals Lithostrotion and Lithostrotionella and the bryozoan Fenestrellina.

See also

• List of types of limestone

References

1. Thompson, Thomas L., 2001, Lexicon of Stratigraphic Nomenclature in Missouri, Missouri Department of Natural Resources, Division of Geology and Land Survey, Report of Investigation Number 73, p. 252
2. Howe, W. B. and J. W. Koenig, The Stratigraphic Section in Missouri, Missouri Geological Survey, 1961, p. 69