Type locality: The Brazil Formation as originally named by Fuller and Ashley (1902, p. 2) for Brazil, Clay County, Indiana, included the rocks in the interval between the top of the Mansfield Sandstone and the bottom of the Petersburg Coal (Springfield Coal Member of present usage) (Hutchison and Hasenmueller, 1986).
History of usage:
Revised contacts: Cumings (1922, p. 525) amended the Brazil Formation to include only the rocks in the interval between the base of the Lower Block Coal Member and the unconformity above what was then called Coal II (Hutchison, 1970; Hutchison and Hasenmueller, 1986).
In the Brazil area, the Brazil Formation consists of shale, sandstone, underclay, and coal and ranges from 40 to 90 ft (12 to 27 m) in thickness (Hutchison, 1960, p. 13; Hutchison, 1970; Hutchison and Hasenmueller, 1986). The formation consists of, in ascending order, the Lower Block, Upper Block, and Minshall Coal Members and other rocks unnamed to member (Hutchison, 1970; Hutchison and Hasenmueller, 1986). In places, a thin coal bed referred to as "the rider of the Upper Block Coal Member" is present in the interval between the Upper Block and the Minshall Coal Members (Hutchison, 1970; Hutchison and Hasenmueller, 1986).
North of southern Parke County, the Lower Block coal is absent or untraceable, so that it is nearly impossible to separate the Brazil Formation from the underlying Mansfield Formation; in southern Indiana, in Daviess County (Hutchison, 1971), Dubois County (Hutchison, 1964), and Spencer County (Hutchison, 1959), coal beds believed to be equivalent to the Block coals are present over most of the area but are difficult to distinguish from upper Mansfield coals (Hutchison and Hasenmueller, 1986).
The rocks assigned to the Brazil Formation in Indiana are equivalent to part of the Tradewater Formation of Illinois and western Kentucky (The Tri-State Committee on Correlation of the Pennsylvanian System in the Illinois Basin, 2001, pl. 1).
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.
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.
Fuller, M. L., and Ashley, G. H., 1902, Description of the Ditney quadrangle: U.S. Geological Survey Geologic Atlas, Folio 84, 8 p.
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.
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, Brazil 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. 24–25.
Hutchison, H. C., and Hasenmueller, W. A., 1986, Brazil 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. 21.
Shaver, R. H., 1984, Atokan Series concepts with special reference to the Illinois Basin and Iowa, in Sutherland, P. K., and Manger, W. L., eds., The Atokan Series (Pennsylvanian) and its boundaries–a symposium: Oklahoma Geological Survey Bulletin 136, p. 101–113.
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.
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.
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.
For additional information, contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: June 9, 2023