Type locality: The term “Minshall Coal” was first applied formally by Ashley (1909, p. 57) to the coal bed below the limestone at the now-abandoned mining town of Minshall, Parke County, where it was mined extensively underground in secs. 8 and 17, T. 14 N., R. 7 W. (Hutchison, 1970; Hutchison and Hasenmueller, 1986).
History of usage:
In now-obsolete usage, the name “Minshall” was also applied to the closely overlying limestone as well as other limestones (Hutchison and Hasenmueller, 1986). The Minshall was assigned member rank by Wayne, Johnson, and Keller (1966) (Hutchison and Hasenmueller, 1986).
The Minshall coal is moderately bright to very dull, pyritiferous, semiblocky to blocky, and extremely irregular in extent and thickness (Hutchison and Hasenmueller, 1986). In the northern part of the coalfield, it ranges from less than 1 ft to more 6 ft (0.3 to 1.8 m) in thickness and averages about 4 ft (1.2 m) where mined (Hutchison, 1970; Hutchison and Hasenmueller, 1986). Stratigraphically, the Minshall Coal Member lies 15 to 20 ft (4.6 to 6.1 m) below the top of the Brazil Formation and about 22 ft (6.7 m) above the Upper Block Coal Member (Hutchison, 1970; Hutchison and Hasenmueller, 1986).
The roof of the coal is gray shale that is clayey to silty and fossiliferous in places (Hutchison and Hasenmueller, 1986). The roof in many areas contains the Perth Limestone Member, a lenticular gray fossiliferous limestone as much as 18 ft (5.5 m) thick (Hutchison, 1970; Hutchison and Hasenmueller, 1986). In some places the limestone lies directly on the coal (Hutchison, 1970; Hutchison and Hasenmueller, 1986). The floor is gray carbonaceous plastic underclay.
The Minshall has been recognized as far north as Warren County (Hutchison, 1961) and as far south as Switz City in Greene County (Kottlowski, 1960; Hutchison, 1970; Hutchison and Hasenmueller, 1986, 1988). Spore assemblages of the Buffaloville and Minshall Coal Members are similar, and Hutchison (1959) assigned the Buffaloville Coal Member to the Brazil Formation and considered that it is continuous with the Minshall.
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 features in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Ashley, G. H., 1909, Supplementary report to the report of 1898 on the coal deposits of Indiana: Indiana Department of Geology and Natural Resources Annual Report 33, p. 13–150.
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.
Hopkins, M. E., and Simon, J. A., 1975, Pennsylvanian System, in Willman, H. B., Atherton, Elwood, Buschbach, T. C., Collinson, Charles, Frye, J. C., Hopkins, M. E., Lineback, J. A., and Simon, J. A., Handbook of Illinois stratigraphy: Illinois State Geological Survey Bulletin 95, p. 163–201.
Hutchison, H. C., 1961, Distribution, structure, and mined areas of coals in Fountain and Warren Counties and the northernmost part of Vermillion County, Indiana: Indiana Geological Survey Preliminary Coal Map 9, scale 1:126,720.
Hutchison, H. C., 1970, Minshall 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. 110–111.
Hutchison, H. C., and Hasenmueller, W. A., 1986, Minshall 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. 92–93.
Peppers, R. A., 1970, Correlation and palynology of coals in the Carbondale and Spoon Formations (Pennsylvanian) of the northeastern part of the Illinois Basin: Illinois State Geological Survey Bulletin 93, 173 p.
Peppers, R. A., 1982, Palynology of coals along Roaring Creek, in Eggert, D. E, and Phillips, T. L., Environments of deposition, coal balls, cuticular shale, and gray-shale floras in Fountain and Parke Counties, Indiana: Indiana Geological Survey Special Report 30, p. 14–19.
Peppers, R. A., and Popp, J. T., 1979, Stratigraphy of the lower part of the Pennsylvanian System in southeastern Illinois and adjacent portions of Indiana and Kentucky, in Palmer, J. E., and Dutcher, R. R., eds., Depositional and structural history of the Pennsylvanian System of the Illinois Basin–Pt. 2, Invited papers, Ninth International Congress Carboniferous Stratigraphy and Geology, Illinois Geological Survey Guidebook Series 15a, p. 65–72.
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.
Wayne, W. J., Johnson, G. H., and Keller, S. J., 1966, Geologic map of the 1° x 2° Danville quadrangle, Indiana and Illinois, showing bedrock and unconsolidated deposits: Indiana Geological Survey Regional Geologic Map No. 2, Part A [bedrock units], scale 1:250,000.
For additional information, contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: December 4, 2017