Type area: The term “Lead Creek Limestone” was applied by Crider (1913, p. 279) to exposures of limestone, shaly limestone, and shale along Lead Creek in Hancock County, Kentucky, and to similar exposures elsewhere in the Kentucky parts of the Tell City and Owensboro quadrangles (Shaver, 1986).
History of usage:
Crider (1913) referred to three or four ledges ranging in thickness from 8 to 10 ft (2.4 to 3.0 m) through an interval of 30 to 40 ft (9 to 12 m) (Shaver, 1986). The Lead Creek of Kentucky was later described by Chisholm (1931, p. 224-225) as 5 to 11 ft (1.5 to 3.4 m) of shaly limestone (above) and hard limestone (below) that lies 85 ft (26 m) below the Lewisport Limestone (Shaver, 1986).
In the southernmost Indiana outcrop area of Mansfield rocks, the Lead Creek Limestone Member characteristically consists of a 15- to 24-foot (5- to 7-m) interval made up of three lithologic units: a lower dark dense shaly or argillaceous limestone that has a shaly parting in some places, (2) a middle shale and siltstone that generally is 10 to 15 ft (3 to 4.6 m) thick and that has thin coal and clay in some sections, and (3) an upper massive limestone that is light colored, fine grained, and cherty and that becomes nearly all chert in some places (Shaver, 1986). The two limestones, ranging from less than 1 foot (0.3 m) to nearly 5 ft (1.5 m) in thickness, are named the Fulda Bed and the Ferdinand Bed (Shaver, 1986).
The Lead Creek is overlain and underlain by clastic rocks in the approximately upper 50 to 60 ft (15 to 18 m) of the Mansfield Formation and in places is much nearer the top of the formation (Shaver, 1986).
At times in the past, the ledges of limestone in Indiana and Kentucky that are now called the Lead Creek have been confused, either as presumably traceable correlatives or more strictly in the age sense, with limestones now called the Lewisport and Curlew Limestone Members (Tradewater Formation) in Kentucky and the Perth Limestone Member (Brazil Formation) in Indiana and with what was once called the Curlew Limestone Member of Illinois, all of which are now known to be younger than the Lead Creek (Shaver, 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.)
Chisholm, D. B., 1931, The geology of Hancock County, Kentucky: Kentucky Geological Survey Bulletin, ser. 6, v. 41, p. 213-247.
Crider, A. F., 1913, Economic geology of Tell City and Owensboro quadrangles: Kentucky Geological Survey, ser. 4, v. 1, p. 263-317.
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.
Hopkins, M. E., and Simon, J. A., 1975, Pennsylvanian 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. 163-201.
Knox, Larry, 1975, Ostracods from the type rocks of the Morrowan Series (Lower Pennsylvanian), Arkansas and Oklahoma: Bloomington, Indiana University, Ph.D. thesis, 130 p.
Rexroad, C. B., Brown, L. M., and Wilke, N. A., 1999, Conodont paleontology of the Lead Creek Limestone Member of the Mansfield Formation (Pennsylvanian) in Indiana: American Association of Petroleum Geologists Bulletin, v. 83, p. 1,372.
Shaver, R. H., 1986, Lead Creek 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. 74-75.
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.
For additional information contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: November 22, 2016