Age:

Pennsylvanian

Type designation:

Type area: The Mattoon Formation was named for exposures near Mattoon in Coles County, Illinois (Kosanke, Simon, Wanless, and Willman, 1960, p. 39; Wier, 1970, 1986).

History of usage:

This formation name was proposed for use in Indiana by Wier and Gray (1961) and further defined by Wier (1970).

Description:

The Mattoon Formation in Indiana includes all Pennsylvanian rocks that are younger than the Livingston Limestone Member of the Bond Formation, and contains the Cohn Coal and Merom Sandstone Members (Wier, 1970, 1986). It has a maximum thickness of slightly more than 600 ft (183 m) in Illinois, 750 ft (229 m) or more in western Kentucky, but only 150 ft (46 m) in Indiana, where most of this formation has been eroded (Wier, 1970, 1986).

Distribution: Only the lower 40 ft (12 m) of this formation is present near Merom in western Sullivan County, where the formation consists of a few feet of shale, the Cohn Coal Member, and the Merom Sandstone Member (Wier, 1970, 1986). Near Mumford Hills, northwestern Posey County, the lower 150 ft (46 m) is present. It consists of the Merom Sandstone Member and unnamed shales and thin clay, limestone, and coal (Wier, 1970, 1986).

Correlations:

The use of the name “Mattoon Formation” was extended into western Kentucky at the recommendation of 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: McLeansboro Group
Formation: Mattoon Formation

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

*mt

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:

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.

Kosanke, R. M., Simon, J. A., Wanless, H. R., and Willman, H. B., 1960, Classification of the Pennsylvanian strata of Illinois: Illinois State Geological Survey Report of Investigations 214, 84 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, Mattoon Formation, 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. 107–108.

Wier, C. E., 1986, Mattoon Formation, 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. 90.

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.