Type section: The Excello Shale Member of the Carbondale Formation (Pennsylvanian) was named by Searight and others (1953) for exposures west of Excello in Macon County, Missouri (Hopkins, and Simon, 1975).
History of usage:
Nance (1970, p. 77) extended the name “Excello Shale Member of the Carbondale Formation” into Illinois. In Illinois, the unit is composed of black fissile shale that is generally 1 to 3 ft (0.30 to 0.9 m) thick and similar in character to the unit in Missouri (Hopkins, and Simon, p. 189).
Hasenmueller and Ault (1991, p. 6) noted in their description of the SDH-306 reference core in Pike County, Indiana, that the interval at a depth of 21.5 to 26.8 ft (6.5 to 8.2 m) was composed of black shale with a few gray silty concretions, two thin vitrain bands, and a few small pyrite nodules and streaks at the base
Regional Indiana usage:
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 features in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Hasenmueller, W. A., and Ault, C. H., 1991, Reference core and correlation of key beds in the Petersburg and Linton Formations (Pennsylvanian) in Indiana: Indiana Geological Survey Occasional Paper 57, 8 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.
Mastalerz, Maria, Ames, P. R., and Drobniak, Agnieszka, 2019, The Survant Coal Member of the Linton Formation (Pennsylvanian) in Indiana–geometry, resources, and properties: Indiana Journal of Earth Sciences, v. 1, 25 p., DOI: https://doi.org/10.14434/ijes.v1i0.26862.
Nance, R. B., 1970, Limestones and phosphatic rocks from the Summun and Liverpool cyclothems in western Illinois: Illinois State Geological Survey Guidebook Series 8, p. 75–83.
Petroleum Database Management System (PDMS), 2018, Petroleum Database Management System: Indiana Geological and Water Survey website, accessed December 3, 2018, at URL https://igws.Indiana.edu/pdms/WellSearch.cfm.
Searight, W. V., Howe, W. R., Moore, R. C., Jewett, J. M., Condra, G. E., Oakes, M. C., and Branson, C. C., 1953, Classification of the Desmoinesian (Pennsylvanian) of the northern Mid-Continent: American Association of Petroleum Geologists Bulletin, v. 37, p. 2,747–2,749.
For additional information, contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: March 29, 2021