Age:

Mississippian

Type designation:

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).

Principal reference section: A type section was not designated, but an excellent exposure of the formation exists in an abandoned quarry north of the abandoned Monon Railroad on the west side of Paoli (SW¼SE¼SE¼ sec. 35, T. 2 N., R. 1 W.) (Smith, 1970; Carr, 1986). This exposure was designated as the principal reference section (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 Paoli Limestone was correlated with the middle and upper parts of the Renault Formation of subsurface usage in western Indiana (Pinsak, 1957; Gray, Jenkins, and Weidman, 1960, table 5); however, in 1990, Droste and Carpenter (p. 27) adopted the name “Paoli Limestone” rather than the name “Renault Formation” for use in the subsurface. They also recommended the abandonment of the use of the name “Popcorn Member,” replacing it with the term “Aux Vase Member.” And, they proposed that the name “Renault Member” replace the term “Shetlerville Member.”

Description:

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 ranges from about 20 to 35 ft (6 to 11 m) in thickness throughout most of its outcrop (Carr, Leininger, and Golde, 1978, p. 18); it reaches thicknesses of 100 ft (30.5 m) in the subsurface in Posey County (Droste and Carpenter, 1990, figs. 15 and 16).

Boundaries:

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).

Correlations:

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).

The Paoli of Indiana contains the crinoid Talarocrinus (Malott, 1952, p. 12), and on this basis it has been correlated with the lower part of presumably post-Platycrinites penicillus rocks in the Talarocrinus Range Zone of other areas, for example, with a part of the Gasper Oolite of Butts (1917, p. 64) in Kentucky (Carr, 1986). [See Cumings, 1922, p. 515, 518; Perry and Smith, 1958, p. 30-31; and Swann, 1963, p. 33, 83 (Carr, 1986)]. The Paoli correlates with rocks within North American foraminiferal Zone 16i of Mamet and Skipp (1971) and within the Visean Series (approximately Zone V3ci) of European usage (Carr, 1986). The formation is within the middle part of the Gnathodus bilineatus-Cavusgnathus charactus Assemblage Zone of conodonts (Collinson, Rexroad, and Thompson, 1971; Carr, 1986).

Economic Importance:

Industrial Minerals: Cement products from the Paoli Limestone (Mississippian) include the following: Portland and masonry cement from a quarry in Putnam County (Shaffer, 2016).

Crushed stone products from the Paoli Limestone (Mississippian) include the following: aglime, crushed stone, crushed stone for Portland masonry cement production, hot and cold asphalt, lime, pugmill material, riprap, scrubber stone, and manufactured sand from quarries in Crawford, Harrison, Lawrence, Monroe, Orange, and Putnam Counties (Shaffer, 2016).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Blue River Group
Formation: Paoli Limestone
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Blue River Group
Formation: Paoli Limestone

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

Mp

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.

References:

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.

Carr, D. D., Leininger, R. K., and Golde, M. V., 1978, Crushed stone resources of the Blue River Group (Mississippian) of Indiana: Indiana Geological Survey Bulletin 52, 225 p.

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 Publication No. 21, pt. 4, p. 403–570.

Droste, J. B., and Carpenter, G. L., 1990, Subsurface stratigraphy of the Blue River Group (Mississippian) in Indiana: Indiana Geological Survey Bulletin 62, 45 p.

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.

Gray, H. H., Jenkins, R. D., and Weidman, R. M., 1960, Geology of the Huron area, south-central Indiana: Indiana Geological Survey Bulletin 20, 78 p.

Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7^th 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.

Perry, T. G., and Smith, N. M., 1958, The Meramec-Chester and intra-Chester boundaries and associated strata in Indiana: Indiana Geological Survey Bulletin 12, 110 p.

Pinsak, A. P., 1957, Subsurface stratigraphy of the Salem Limestone and associated formations in Indiana: Indiana Geological Survey Bulletin 11, 62 p.

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.

Shaffer, K. R., compiler, 2016, Directory of industrial mineral producers in Indiana: Indiana Geological Survey Directory 11-2016, 287 p.

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.