Age:

Pennsylvanian

Type designation:

Type locality: The term “Raccoon Creek Group” was first used by Wier and Gray (1961) in a generalized columnar section. Wier (1970) formally proposed the name for rocks in the lower part of the Pennsylvanian System that crop out along Raccoon Creek in southern Parke County, Indiana, in T. 14 N., Rs. 5, 6, 7, and 8 W., and T.15 N., R. 8 W. (Wier, 1970, 1986).

Reference sections: The following cores were designated as reference cores for the Raccoon Creek Group in Indiana by the Tri-State Committee on Correlation of the Pennsylvanian System in the Illinois Basin (2001, p. 3) with the stipulation that the Seelyville Coal Member is placed in the Carbondale.

(1) Indiana Geological Survey drill hole (SDH) 31 (Indiana Geological Survey Petroleum Database Management System No. 124926) located 5 miles (8.05 km) southwest of Rockville, Parke County, Indiana, in the NENE sec. 3, T. 14 N., R. 7 W. This core was designated as a reference section for the Mansfield Formation, namely, the lower part of the Raccoon Creek Group by Hutchison (1976, p. 26-27; p. 52-55).

(2) A composite section of core from SDH 30 and SDH 174 (Indiana Geological Survey Petroleum Database Management System Nos. 125034 and 125033) located 1 mile (1.6 km) northwest of Mansfield, Parke County, Indiana, in the SESW sec. 31, T. 15 N., R. 6 W. These core drill holes were designated as reference sections for Mansfield Formation, i.e., the lower part of the Raccoon Creek Group by Hutchison (1976, p. 26-27; p. 55-57).

SDH 33 (Indiana Geological Survey Petroleum Database Management System No. 124940), which is located in the SENWSW sec. 5, T. 14 N., R. 8 W., Parke County, Indiana, includes continuous core from the top of the Raccoon Creek Group down to the upper part of the Mansfield Formation. [Mecca quadrangle; elevation 560 ft (170.7 m).] See Friedman (1989, p. 35-41) for detailed core description.

Description:

The Raccoon Creek Group consists of, in ascending order, the Mansfield, Brazil, and Staunton Formations, is overlain by the Carbondale Group, and is underlain by rocks ranging in age from Middle Devonian to Late Mississippian (Wier, 1970, 1986).

Shale and sandstone compose more than 95 percent of the group, and clay, coal, and limestone make up nearly all the rest; small amounts of chert and sedimentary iron ore are in the lower part of the group (Wier, 1970, 1986). Shale is more common than sandstone, and most of it is light-gray to dark-gray shale and soft nonsilty shale to hard silty and sandy shale (Wier, 1970, 1986). A small amount of black fissile shale is also present (Wier, 1970, 1986). The sandstone is mostly fine grained; coarse-grained size is rare (Wier, 1970, 1986). Where the sandstone is present in the subsurface, massive cross-bedded sandstone seems to be most common (Wier, 1970, 1986).

The Raccoon Creek Group generally thickens toward the southeast but in some places has thickness variations of more than 300 ft (91 m) because of irregular unconformity on the surface of underlying rocks (Wier, 1970, 1986). It ranges in thickness from less than 100 ft (30 m) in some locations in Parke and Vermillion Counties to more than 1,000 ft (305 m) in Vanderburgh County (Wier, 1970, 1986). It crops out in southwestern Indiana along the easternmost margin of Pennsylvanian rocks (Wier, 1970, 1986).

Correlations:

The Raccoon Creek Group correlates with the Caseyville and Tradewater Formations in Illinois and western Kentucky (The Tri-State Committee on Correlation of the Pennsylvanian System in the Illinois Basin, 2001).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Raccoon Creek Group
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Raccoon Creek Group
Kankakee Arch (COSUNA 14)
Supergroup: none
Group: Raccoon Creek Group

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

*rc

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.

References:

Friedman, S. A., 1989, Geology and coal deposits of the Clinton area, west-central Indiana: Indiana Geological Survey Special Report 42, 50 p.

Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7^th ed.): Washington, D.C., U.S. Geological Survey, 289 p.

Hutchison, H. C., 1976, Geology of the Catlin-Mansfield area, Parke and Putnam Counties, Indiana: Indiana Geological Survey Bulletin 54, 57 p.

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.

The Tri-State Committee on Correlation of the Pennsylvanian System in the Illinois Basin, 2001, Toward a more uniform stratigraphic nomenclature for rock units (formations and groups) of the Pennsylvanian System in the Illinois Basin: Indiana Geological Survey, Illinois Basin Consortium Illinois Basin Studies 5, 26 p.

Wier, C. E., 1970, Raccoon Creek Group, in Shaver, R. H., Burger, A. M., Gates, G. R., Gray, H. H., Hutchison, H. C., Keller, S. J., Patton, J. B., Rexroad, C. B., Smith, N. M., Wayne, W. J., and Wier, C. E., Compendium of rock-unit stratigraphy in Indiana: Indiana Geological Survey Bulletin 43, p. 136–137.

Wier, C. E., 1986, Raccoon Creek Group, 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. 120–121.

Wier, C. E., and Gray, H. H., 1961, Geologic map of the Indianapolis 1° x 2° quadrangle, Indiana and Illinois, showing bedrock and unconsolidated deposits: Indiana Geological Survey Regional Geologic Map, Indianapolis Sheet, scale 1:250,000.