Age:

Pennsylvanian

Type designation:

Type locality: The type locality includes numerous exposures of parts of the formation along the tributaries of the Patoka River near Patoka in Gibson County, Indiana (Wier, 1970; Wier and Ault, 1986). Other good exposures are along the tributaries of the White River near Hazelton (Wier, 1970; Wier and Ault, 1986).

History of usage:

Rocks now recognized as belonging to the Patoka Formation were called the Merom Group in southern Indiana by Logan (1932) and were included in part of the Shelburn Group of Cumings (1922) (Wier, 1970; Wier and Ault, 1986). The name “Patoka Formation” was first used in a stratigraphic column by Wier and Gray (1961) (Wier, 1970; Wier and Ault, 1986).

Description:

The Patoka Formation is a southward-thickening unit of shale, sandstone, clay, limestone, and coal (Wier, 1970; Wier and Ault, 1986). The formation consists of all rocks above the West Franklin Limestone Member of the Shelburn Formation and below the Carthage Limestone Member of the Bond Formation (Wier and Ault, 1986; The Tri-State Committee on Correlation of the Pennsylvanian System in the Illinois Basin Committee, 2001). It includes, in ascending order, the Ditney Coal, Vigo Limestone, Dicksburg Hills Sandstone, Raben Branch Coal, and Parker Coal Members and includes unnamed beds of shale, clay, and sandstone (Wier, 1970; Wier and Ault, 1986). Shale and sandstone make up more than 85 percent of the formation (Wier, 1970; Wier and Ault, 1986). The formation ranges in thickness from 100 ft (30 m) in northern Sullivan County to 310 ft (94 m) in southwestern Posey County (Wier, 1970; Wier and Ault, 1986).

Correlations:

Wier and Ault (1986) noted that the Patoka was correlative with the upper part of the Modesto Formation of Illinois and the middle part of the Sturgis Formation of Kentucky. In 2001, The Tri-State Committee on Correlation of the Pennsylvanian System in the Illinois Basin Committee extended the use of the name “Patoka Formation” into Illinois and Kentucky.

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: McLeansboro Group
Formation: Patoka Formation
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: McLeansboro Group
Formation: Patoka Formation

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

*p

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:

Cumings, E. R., 1922, Nomenclature and description of the geological formations of Indiana, in Logan, W. N., Cumings, E. R., Malott, C. A., Visher, S. S., Tucker, W. M., Reeves, J. R., and Legge, H. W., Handbook of Indiana geology: Indiana Department of Conservation Publication No. 21, pt. 4, p. 403–570.

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.

Logan, W. N., 1932, The subsurface strata of Indiana: Indiana Department of Conservation Publication No. 108, 790 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, Patoka 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. 128–129.

Wier, C. E., and Ault, C. H., 1986, Patoka 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. 109.

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.