Type section: The Branchville Formation was named for a settlement near the headwaters of Oil Creek in Perry County, Indiana (Gray, 1978, p. 8; Gray, 1986). A section near Branchville, earlier described by Malott (1925, p. 125-126), was designated as the type section (Gray, 1986). The type section is located in the SE¼, sec. 14, T. 4 S., R. 2 W., Perry County (Branchville quadrangle) (Gray, 1986).
In SDH 132 the Branchville Formation is 92 ft (28 m) thick and consists mainly of mudstone, shale, siltstone, and sandstone, all in relatively thin beds (Gray, 1986). Where the entire Branchville Formation is present, it is 85 to 105 ft (26 to 32 m) thick (Gray, 1986).
At the base of the Branchville Formation is the Vienna Limestone Member, and marking its top is the Leopold Limestone Member (Gray, 1986). It conformably overlies the Tar Springs Formation and is clearly distinguishable from that formation only where the Vienna Limestone Member is present (Gray, 1986). It is conformably overlain by the Tobinsport Formation, and this distinction can commonly be made only where the Leopold Limestone Member is present (Gray, 1986). Along the north edge of its extent, the Branchville Formation is truncated and disconformably overlain by the Mansfield Formation (Morrowan) (Gray, 1986).
The Branchville Formation is equivalent to the lower part of the Buffalo Wallow Formation of Kentucky usage and to the Vienna Limestone, the Waltersburg Formation, and some part of the Menard Limestone of the standard Chesterian section (Gray, 1986). The Branchville equates with rocks within North American foraminiferal Zone 17 of Mamet and Skipp (1971) and within Zone E1 of the Namurian Series of European usage. On the basis of contained conodonts, the Branchville belongs to the Kladognathus primus Assemblage Zone and the lower part of the overlying Kladognathus-Cavusgnathus naviculus Assemblage Zone of North American standard usage (Collinson, Rexroad, and Thompson, 1971; Gray, 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.)
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.
Collinson, Charles, Rexroad, C. B., and Thompson, T. L., 1971, Conodont zonation of the North American Mississippian: Geological Society of America Memoirs 127, p. 353-394.
Gray, H. H., 1986, Branchville 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. 19-20.
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.
Malott, C. A., 1925, The upper Chester of Indiana: Indiana Academy of Science Proceedings, v. 34, p. 103-132.
Mamet, B. L., and Skipp, B. A., 1971, Lower Carboniferous calcareous Foraminifera–preliminary zonation and stratigraphic implications for the Mississippian of North America: Sixieme Congres International de Stratigraphie et de Geologie du Carbonifere Sheffield, 1967, Compte rendu, v. 3, p. 1,129-1,146.
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.
For additional information contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: July 31, 2017