Type locality: The term "Lower Block Coal" was first used formally by Ashley (1909, p. 57-58), who earlier (1899, p. 90, 103) had cited "lower block coal" as an informal usage (Hutchison and Hasenmueller, 1986). Numerous descriptions of this coal were taken from deep mines and outcrops around Brazil, which suggests that the type locality is about 2 to 3 miles (3.2 to 4.8 km) northeast of Brazil near the old mining town of Cardonia (Hutchison and Hasenmueller, 1986).
History of usage:
In 1899, this coal bed was also designated as Coal III in the sequence in northern Clay County and in Vigo County, where Ashley had based his numbering of Indiana coal beds (Hutchison and Hasenmueller, 1986).
In northern Clay County the Lower Block Coal Member consists of dull to moderately dull banded coal that is slabby or blocky and that has two conspicuous sets of vertical joints, called slips by miners, which trend about N. 20° W. and N. 70° E. and are 0.3 to 2.0 ft (0.09 to 0.6 m) apart (Hutchison, 1970; Hutchison and Hasenmueller, 1986). The coal ranges from 0.7 to 5.8 ft (0.2 to 1.8 m) in thickness (Hutchison, 1960, p. 14; Hutchison and Hasenmueller, 1986). At many localities the Lower Block member has a bone coal at the base on which the main part of the coal rests directly (Hutchison, 1970; Hutchison and Hasenmueller, 1986). In places, the upper part of the coal bed is separated from the bone coal by as much as 12 ft (3.7 m) of gray shale (Ashley, 1899, p. 522-596; Hutchison, 1970; Hutchison and Hasenmueller, 1986).
Gray shale that is hard, sandy, and thin bedded to massive and interbedded laminae of light-gray fine-grained sandstone generally form the roof of the coal. The floor consists of a gray, sandy underclay or silty shale (Hutchison, 1960, p. 15-16; Hutchison, 1970; Hutchison and Hasenmueller, 1986).
According to Hutchison (1961, 1976, p. 24-25) the Lower Block is absent or unidentifiable north of southern Parke County, but Peppers (1982, p. 14-19) correlated a coal in northern Parke County with the Lower Block coal on the basis of palynology, which suggested a greater northward extent of the Lower Block coal (Hutchison and Hasenmueller, 1986).
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.)
Ashley, G. H., 1899, The coal deposits of Indiana: Indiana Department of Geology and Natural Resources Annual Report 23, p. 1-1,573.
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.
Hutchison, H. C., 1970, Lower Block 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. 100-101.
Hutchison, H. C., and Hasenmueller, W. A., 1986, Lower Block 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. 85.
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.
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.
Searight, T. K., 1979, The stratigraphy and sedimentation of the Abbott and lower portion of the Spoon Formation in the outcrop belt of southern Illinois, 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 State Geological Survey Guidebook Series 15a, p. 81-86.
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.
Wanless, H. R., 1939, Pennsylvanian correlations in the Eastern Interior and Appalachian coalfields: Geological Society of America Special Paper 17, 130 p.
Wanless, H. R., 1962, Pennsylvanian rocks of Eastern Interior Basin, in Branson, C. C., ed., Pennsylvanian System in the United States: Tulsa, Oklahoma, American Association of Petroleum Geologists, p. 4-59.
Williams, D. A., Williamson, A. D., and Beard, J. G., 1982, Stratigraphic framework of coal-bearing rocks in the Western Kentucky Coal Field: Kentucky Geological Survey Information Circular 8, 201 p.
For additional information contact:
Nancy Hasenmueller (email@example.com)Date last revised: April 5, 2017