Walnut Grove Limestone Member
Lithostratigraphy: Hunton Limestone Megagroup >>Lingle Formation >>Walnut Grove Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Devonian System >>Middle Devonian Series
Allostratigraphy: Kaskaskia Sequence
Primary source
Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
Contributing author(s)
Charles Collinson and Elwood Atherton
Name
Original description
The Walnut Grove Limestone Member of the Lingle Formation (North, 1969, p. 29-30).
Derivation
Named for Walnut Grove Church, Union County, 1 mile southeast of the type section.
Other names
History/background
Type section
Type location
The type section of the Walnut Grove Member is an outcrop near the head of a small tributary of Clear Creek (SE SE SW 22, 11S-2W), where the member is 29 feet thick.
Type author(s)
Type status
Reference section
Reference location
Reference author(s)
Reference status
Stratigraphic relationships
The Walnut Grove Limestone Member is the uppermost member of the Lingle Formation.
Extent and thickness
The Walnut Grove occurs only in and near the outcrop area in Jackson, Union, and Alexander Counties (fig. D-15), and its maximum thickness is about 50 feet.
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Lithology
The Walnut Grove Member is cherty, very silty, glauconitic, spore-bearing, fine-grained, fossiliferous limestone locally interbedded with very dark brown, calcareous shale. The Rendleman Oolite Bed near the base is a distinctive key bed.
Core(s)
Photograph(s)
Contacts
Well log characteristics
Fossils
Fossils include crinoids, corals, brachiopods, and sporangites.
Age and correlation
Environments of deposition
Economic importance
Remarks
References
NORTH, W. G., 1969, Middle Devonian strata of southern Illinois: Illinois State Geological Survey Circular 441, 45 p.
ISGS Codes
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