Type section: The Leopold Limestone Member was named by Gray (1978, p. 10) for exposures near Leopold in central Perry County, Indiana (Gray, 1986). The type section is in a road cut on former Indiana Highway 37 and was initially described by Malott, Esarey, and Bieberman (1948, p. 13).
At the type section the Leopold Limestone Member is 12 ft (4 m) thick and consists of three beds of limestone separated by shale (Gray, 1986). This section was also reported by Rexroad and Nicoll (1965, p. 15).
According to Gray (1978, p. 10), the Leopold Limestone Member is "the most continuous member in the outcropping upper Chesterian of Indiana," and for this reason it was selected to mark the top of the Branchville Formation (Gray, 1986). The Leopold conformably overlies shale of the upper part of the Branchville Formation (Gray, 1986). It is overlain conformably by the Tobinsport Formation and is truncated northward by the disconformable base of the Mansfield Formation (Morrowan) (Gray, 1986).
The Leopold Limestone Member is a tongue of the Menard Limestone (Gray, 1986). If the "Chapman sand" of the Owensboro, Kentucky, area (Swann, 1963, p. 38) is equivalent to Malott's (1925) Wickliffe Sandstone, as seems likely, then the Leopold probably represents the basal part of the Scottsburg Limestone Member, the middle of three limestone members that are separated and overlain by three unnamed shale members and that make up the Menard Limestone of the standard Chesterian section (Swann, 1963, p. 38-39; Atherton and others, 1975, p. 160; Gray, 1986). The Leopold Limestone Member is the surface extension of the Walche Limestone Member of the Menard Limestone (Droste and Keller, 1995). The Leopold Limestone Member correlates with rocks within North American foraminiferal Zone 17 of Mamet and Skipp (1971) and with rocks of the Namurian Series near the boundary between Zones El and E2 of European usage (Gray, 1986). Conodonts representative of the Kladognathus-Cavusgnathus naviculus Assemblage Zone of the standard North American zonal scheme were reported by Rexroad and Nicoll (1965) from collecting sites now assigned to the Leopold Limestone Member (Gray, 1986).
Regional Indiana usage:
Illinois Basin (COSUNA 11)
Geologic Map Unit Designation:
Note: Hansen (1991, p. 52) in Suggestions to authors of the reports of the United States Geological Survey noted that letter symbols for map units are considered to be unique to each geologic map and that adjacent maps do not necessarily need to use the same symbols for the same map unit. Therefore, map unit abbreviations in the Indiana Geologic Names Information System should be regarded simply as recommendations.
COSUNA areas and regional terminology
Names for geologic units vary across Indiana. The Midwestern Basin and Arches Region COSUNA chart (Shaver, 1984) was developed to strategically document such variations in terminology. The geologic map (below left) is derived from this chart and provides an index to the five defined COSUNA regions in Indiana. The regions are generally based on regional bedrock outcrop patterns and major structural features in Indiana. (Click the maps below to view more detailed maps of COSUNA regions and major structural features in Indiana.)
COSUNA areas and numbers that approximate regional bedrock outcrop patterns and major structural featuers in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Atherton, Elwood, Collinson, Charles, and Lineback, J. A., 1975, Mississippian System, in Willman, H. B., Atherton, Elwood, Buschbach, T. C., Collinson, Charles, Frye, J. C., Hopkins, M. E., Lineback, J. A., and Simon, J. A., Handbook of Illinois stratigraphy: Illinois State Geological Survey Bulletin 95, p. 123-163.
Gray, H. H., 1986, Leopold Limestone Member, in Shaver, R. H., Ault, C. H., Burger, A. M., Carr, D. D., Droste, J. B., Eggert, D. L., Gray, H. H., Harper, Denver, Hasenmueller, N. R., Hasenmueller, W. A., Horowitz, A. S., Hutchison, H. C., Keith, B. D., Keller, S. J., Patton, J. B., Rexroad, C. B., and Wier, C. E., Compendium of Paleozoic rock-unit stratigraphy in Indiana–a revision: Indiana Geological Survey Bulletin 59, p. 76-77.
Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7th ed.): Washington, D.C., U.S. Geological Survey, 289 p.
Malott, C. A., 1925, The upper Chester of Indiana: Indiana Academy of Science Proceedings, v. 34, p. 103-132.
Mamet, B. L., and Skipp, B. A., 1971, Lower Carboniferous calcareous Foraminifera–preliminary zonation and stratigraphic implications for the Mississippian of North America: Sixieme Congres International de Stratigraphie et de Geologie du Carbonifere Sheffield, 1967, Compte rendu, v. 3, p. 1,129-1,146.
Shaver, R. H., coordinator, 1984, Midwestern basin and arches region–correlation of stratigraphic units in North America (COSUNA): American Association of Petroleum Geologists Correlation Chart Series.
Swann, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.
For additional information, contact:
Nancy Hasenmueller (email@example.com)Date last revised: April 13, 2017