Type locality: The Paoli Limestone was named by Elrod (1899, p. 259) for the town of Paoli in Orange County, Indiana, near which are many exposures of the formation (Smith, 1970; Carr, 1986).
History of usage:
As currently defined, the Paoli comprises the rocks between the Ste. Genevieve Limestone (below) and the West Baden Group (Droste and Carpenter, 1990), but the Paoli of Elrod (1899) included the rocks above the Lost River Chert Bed, in the lower part of the Ste. Genevieve, and below the lowest Chesterian sandstone, which at that time was incorrectly thought to be what is now the Sample Formation (Carr, 1986). In later use (Cumings, 1922, p. 515), the Paoli was defined essentially as it is now and was considered to be the lowest Chesterian unit (Carr, 1986). The Paoli of Malott (1952, p. 12), however, excluded the lower sandy and shaly rocks, assigned to the Popcorn Member of the Paoli, that Malott (1945, p. 1,180; 1946, p. 322-323) had correlated with Keyes's (1892, p. 296) Aux Vases Sandstone of Missouri. Stating that these rocks do not correspond either to the classic Aux Vases Sandstone or to the Aux Vases Formation of subsurface usage in the Illinois Basin; Gray, Jenkins, and Weidman (1960, p. 49) rejected the name “Aux Vases” and reassigned these rocks to the lower part of the Paoli (Carr, 1986). Carr (1986, p. 108) noted that much of the exposed Paoli was characterized by four principal lithologies and designated them as the following members in descending order; (1) the Downeys Bluff Member, (2) the Yankeetown Member, (3) the Shetlerville Member, and (4) the Popcorn Member.
The principal lithologies of the four members in descending order were described by Carr (1986). The Downeys Bluff Member is a gray to light-gray medium-grained thin- to thick-bedded skeletal and oolitic limestone. The Yankeetown Member is characterized by gray or greenish-gray calcareous shale and thin discontinuous beds of skeletal and micritic limestone. The Shetlerville Member, now renamed the Renault Member, is a gray to greenish-gray skeletal, oolitic, and micritic limestone. And, the Popcorn Member, now called the Aux Vases Member, is characterized by gray calcareous sandstone, dark shale, and impure limestone, which in places grade without apparent break into the overlying member.
The Paoli Limestone rests on the Ste. Genevieve Limestone with little evidence of more than a minor break in sedimentation (Perry and Smith, 1958, p. 32-33; Gray, Jenkins, and Weidman, 1960, p. 50), and it is associated with that formation in the outcrop belt extending from Crawford and Harrison Counties, on the Ohio River, to central Owen County, where rocks of the West Baden clastic belt (see under "Elwren Formation") in places cut out the Paoli (Malott, 1952, p. 45-49), and to west-central Putnam County, where Pennsylvanian rocks disconformably overlap the Paoli (Carr, 1986).
The Paoli Limestone is correlated with the Illinois standard section with the ascending sequence consisting of the Shetlerville Limestone Member of the Renault, the Yankeetown Sandstone, and the Downeys Bluff Limestone (Pinsak, 1957, p. 17-18; Swann, 1963, p. 32-34, 51, 77; Carr, 1986). It is precisely equivalent, therefore, to the Cedar Bluff Group of Swann (1963) (Carr, 1986). Shetlerville (Renault?)-equivalent rocks extend to the middle shale break, a determination borne out by conodont ratios of Cavusgnathus, Gnathodus, and Spathognathodus (Rexroad and Liebe, 1962; Carr, 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.
Butts, Charles, 1917, Mississippian formations of western Kentucky: Descriptions and correlations of the Mississippian formations of western Kentucky: Kentucky Geological Survey, ser. 4, v. 5, pt. 1, 119 p.
Carr, D. D., 1986, Paoli Limestone, 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. 108-109.
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.
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 Publications 21, pt. 4, p. 403-570.
Elrod, M. N., 1899, The geologic relations of some St. Louis Group caves and sinkholes: Indiana Academy of Science Proceedings for 1898, p. 258-267.
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.
Keyes, C. R., 1892, The principal Mississippian section: Geological Society of America Bulletin, v. 3, p. 283-300.
Malott, C. A., 1945, Rosiclare and Aux Vases Sandstones in southern Indiana [abs.]: Geological Society of America Bulletin, v. 56, p. 1,180.
Malott, C. A., 1946, The geology of Cataract Falls, Owen County, Indiana: Journal of Geology, v. 54, p. 322-326.
Malott, C. A., 1952, Stratigraphy of the Ste. Genevieve and Chester formations of southern Indiana: Ann Arbor, Michigan, Edwards Letter Shop, 105 p.
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.
Rexroad, C. B., and Liebe, R. M., 1962, Conodonts from the Paoli and equivalent formations in the Illinois Basin: Micropaleontology, v. 8, p. 509-514.
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.
Smith, N. M., 1970, Paoli Limestone, 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. 125-128.
Swann, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.
For additional information contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: March 29, 2017