View source for Historical:St. Louis Limestone

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{{Tree
|tree1=Mammoth Cave Limestone Megagroup 
|tree2=St. Louis Limestone 
|tree21=Paleozoic Erathem 
|tree22=Mississippian Subsystem 
|tree23=Valmeyeran Series 
|tree31=Kaskaskia Sequence 
|category1=Paleozoic Erathem
|category2=Mississippian Subsystem
|category3=Kaskaskia Sequence
|category4=Mammoth Cave Limestone Megagroup
|category5=Valmeyeran Series
|category6=Limestone
}}
==Authors==
Elwood Atherton, Charles Collinson, and Jerry A. Lineback

==Name Origin==
The St. Louis Limestone (Engelmann, 1847, p. 119-120; Ulrich, 1904, p. 103) is named for St. Louis, Missouri, where it is extensively exposed.

==Type Section==
No type section was designated for the St. Louis Limestone.

==Extent and Thickness==
The St. Louis is typically exposed in Illinois in the Mississippi River bluffs at Alton, Madison County (Collinson et al., 1954) (fig. M-1B). It is also well exposed in the Mississippi and Illinois Valleys in western and southern Illinois (fig. M-1D) and along the Ohio River in Hardin County (fig. M-21). The St. Louis is 500 feet thick in southeastern Illinois and thins northwestward to less than 200 feet before being truncated by pre-Pennsylvanian erosion.

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Figure M-1B.jpg|{{file:Figure M-1B.jpg}}
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==Stratigraphic Position==
The St. Louis overlies the Salem Limestone except in the parts of western Illinois where it lies on the Warsaw Shale or the Sonora Formation. It is overlain by the Ste. Genevieve Limestone. The lower part of that formation grades laterally into the St. Louis Limestone, and in those places the formations are separated by a vertical cut-off.

==Description==
The St. Louis Limestone in Illinois is characterized by fine-grained, micritic to lithographic, cherty limestone, but it contains beds of dolomite, crystalline limestone, fossiliferous limestone, and evaporites. The evaporites are represented in the outcrop areas by limestone breccias. The outcrop areas of the St. Louis are characterized by abundant sink holes.

==Fossils==
The rugose coral ''Lithostrotionella'' is common and characteristic (fig. M-4). In the St. Louis--Alton area the lower part of the St. Louis is included in the conodont ''Taphrognathus varians'' -- ''Apatognathus'' Zone and the upper part in the ''A. scalenus'' -- ''Cavusgnathus'' Zone. The upper St. Louis has common ''Eoendothyranopsis, Koninckopora pruvosti'', and large archaediscids.

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==References==
COLLINSON, CHARLES, D. H. SWANN, and H. B. WILLMAN, 1954, Guide to the structure and Paleozoic stratigraphy along the Lincoln Fold in western Illinois: Illinois State Geological Survey Guidebook Series 3, 75 p.<br>
ENGELMANN, GEORGE, 1947, Remarks on the St. Louis Limestone: American Journal of Science, v. 3, p. 119-120.<br>
ULRICH, E. O., 1904, in E. R. Buckley and H. A. Buehler, Quarrying industry of Missouri: Missouri Bureau of Geology And Mines, v. 2, 371 p.

{{Codes 
 | membercode   = 5150
 | geo_unit  = Msl
 | geo_image =
}}