Type designation:

Type section: The name "Herrin," taken from Herrin, Williamson County, Illinois, was first used by Worthen (1870, p. 93) and later by Shaw and Savage (1912, p. 6), who designated the type section in subsurface exposures in mines near Herrin (Wier, 1970; Wier and Ault, 1986).

History of usage:

Informal name: The name “Herrin Coal Member” (of the Dugger Formation) was first proposed for use in Indiana by Wier in unpublished manuscripts (Wier, 1970; Wier and Ault, 1986).

Formal name: The name "Herrin Coal Member" was first formally introduced by Wier in 1970 (Wier, 1970; Wier and Ault, 1986).


The Herrin is represented by streaks of coal and thin smut streaks that are found below the Providence Limestone Member along its outcrop in Warrick County (Wier, 1970; Weir and Ault, 1986). This coal is thin and discontinuous on Indiana outcrop and has not been mined in the state, but it thickens westward in Vanderburgh and Posey Counties, where it ranges from 2 to more than 5 feet (0.6 to 1.5 m) in thickness (Wier, 1970; Wier and Ault, 1986). It is a bright-banded coal that contains clay or shale partings (Wier, 1970; Wier and Ault, 1986). A prominent parting (the blue band) occurs in the lower part of the coal where the coal reaches minable thicknesses (Wier and Ault, 1986). Florally, the Herrin is dominated by Lycospora granulata; Laevigatosporites minutus is subordinate (Jacobson and others, 1985).


Early correlations of the Herrin coal in Illinois and Indiana with the Herrin Coal Bed of Kentucky (W. Ky. No. 11) have been confirmed by Jacobson and others (1985) (Wier and Ault, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Carbondale Group
Formation: Dugger Formation
Member: Herrin Coal Member

Misc/Abandoned Names:


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 featuers in Indiana.

Major tectonic features that affect bedrock geology in Indiana.


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.

Jacobson, R. J., Trask, C. B., Ault, C. H., Carr, D. D., Gray, H. H., Hasenmueller, W. A., Williams, D., and Williamson, A. D., 1985, Unifying nomenclature in the Pennsylvanian System of the Illinois Basin: Illinois State Academy of Science Transactions, v. 78, p. 1-11.

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.

Shaw, E. W., and Savage, T. E., 1912, Description of the Murphysboro and Herrin quadrangles, Illinois: U.S. Geological Survey Geologic Atlas, Folio 185, 15 p.

Wier, C. E., 1970, Herrin Coal Member, 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. 72.

Wier, C. E., and Ault, C. H., 1986, Herrin Coal 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. 60.

Worthen, A. H., 1870, Geology of Fulton County, in Geology and paleontology: Illinois State Geological Survey, v. 4, p. 90-110.

For additional information contact:

Nancy Hasenmueller (
Date last revised: November 22, 2016