Type locality: The name "Dugger Formation" was used by Wier (1950, 1952, p. 17) in describing rocks exposed in secs. 31 and 32, T. 8 N., R. 7 W., and secs. 5 and 6, T. 7 N., R. 7 W., 2 miles (3.2 km) northeast of Dugger, Sullivan County, Indiana (Burger and Hasenmueller, 1986).
History of usage:
Revised contact: Wier’s descriptions (1950, 1952, p. 17) placed the lower boundary of the formation at the top of the Alum Cave Limestone Member; later, however, this boundary was lowered to include the Alum Cave and the underlying black shale (Wier in unpublished manuscripts; Wier and Gray, 1961). As now recognized, the Dugger Formation extends from the top of the Springfield Coal Member of the Petersburg Formation to the top of the Danville Coal Member (Burger, 1970; Burger and Hasenmueller, 1986).
The Dugger Formation, the uppermost formation in the Carbondale Group, includes, in ascending order, the Bucktown, Herrin, Hymera, and Danville Coal Members; the Alum Cave, Antioch, Providence, and Universal Limestone Members; the Anvil Rock and Bridge Junction Sandstone Members; and unnamed beds of clay, sandstone, and shale (Burger and Hasenmueller, 1986). The basal unit of the formation is commonly an unnamed black fissile shale that contains fish remains and concretions of ironstone and limestone as much as 3 ft (0.9 m) in diameter (Wier, unpublished manuscripts; Burger, 1970). In places, a thin pyritic limestone underlies the black shale (Wier, 1952, p. 15).
The Dugger Formation is underlain by the Petersburg Formation of the Carbondale Group and overlain by the Shelburn Formation of the McLeansboro Group (Burger and Hasenmueller, 1986).
The Dugger is correlative with the upper part of the Carbondale Formation and lower part of the Shelburn Formation of 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)
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.
Burger, A. M., 1970, Dugger 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. 49.
Burger, A. M., and Hasenmueller, N. R., 1986, Dugger 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. 39.
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.
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., 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.
For additional information contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: July 28, 2017