Type designation:

Type section: The Yankeetown Sandstone was named by Weller (1913, p. 120) for an exposure of about 20 ft (6 m) of sandstone and chert near Yankeetown School, Monroe County, Illinois (NE cor. SE¼ sec. 26, T. 4 S., R. 9 W.) (Carr and Gray, 1986, p. 169).

Reference section: Carr and Gray, (1986, p. 169) proposed that an Indiana reference section for the Yankeetown Member was the principal reference section for the Paoli Limestone, an abandoned quarry just north of the former railroad tracks on the west side of Paoli, Indiana (SW¼SE¼SE¼ sec. 35, T. 2 N., R. 1 W.).

History of usage:

In Indiana a shaly middle member of the Paoli Limestone, sometimes informally called the mid-Paoli shale break, has been recognized for many years in both surface and subsurface studies (Malott, 1952, p. 12; Pinsak, 1957, p. 17; Perry and Smith, 1958, p. 23; Gray, Jenkins, and Weidman, 1960, p. 49; Carr, Leininger, and Golde, 1978, p. 13; Carr and Gray, 1986). Swann (1963, p. 33), among others, correlated this unit with the Yankeetown Sandstone of Illinois (Carr and Gray, 1986). The name “Yankeetown” was adopted by Carr and Gray (1986) for surface exposures of this member. At the reference section the member is about 3 ft (0.9 m) thick and consists of calcareous fossiliferous shale (Malott and Esarey, 1940, unnumbered plate; Carr and Gray, 1986). Droste and Carpenter (1990, p. 34, fig. 23) recognized the Yankeetown Member in both the subsurface and outcrop areas of Indiana as a member of the Paoli Limestone. The member occupies the stratigraphic position between the Renault Member below and the Downeys Bluff Member above (Droste and Carpenter, 1990, fig. 2 and p. 34).


The Yankeetown Member averages about 4 ft (1.2 m) in thickness along the outcrop in south-central Indiana, but it is absent, probably depositionally, from the northern part of the outcrop and is as much as 9 ft (2.7 m) thick in the southern part (Kissling, 1967, p. 66; Carr and Gray, 1986). The Yankeetown commonly consists of alternating, subparallel, and discontinuous beds of greenish-gray calcareous shale and brownish-gray micritic, skeletal, or oolitic limestone, but in places it is gray argillaceous or sandy limestone or greenish-gray calcareous shale or siltstone (Carr and Gray, 1986). The shale and the limestone are fossiliferous, and crinoids, brachiopods, and gastropods are the most commonly found fossils (Carr and Gray, 1986).


The Yankeetown Member of the Paoli Limestone contains the crinoid Talarocrinus, which is considered to indicate an early Chesterian age (Carr and Gray, 1986).

Regional Indiana usage:

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

Misc/Abandoned Names:


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.


Carr, D. D., and Gray, H. H., 1986, Yankeetown 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. 169-170.

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.

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.

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 (7th ed.): Washington, D.C., U.S. Geological Survey, 289 p.

Kissling, D. L., 1967, Environmental history of lower Chesterian rocks in southwestern Indiana: Bloomington, Indiana University, Ph.D. thesis, 367 p.

Malott, C. A., 1952, Stratigraphy of the Ste. Genevieve and Chester formations of southern Indiana: Ann Arbor, Michigan, Edwards Letter Shop, 105 p.

Malott, C. A., and Esarey, R. E., 1940, Outcrop of the Chester Series of southern Indiana: Indiana-Kentucky Geological Society, May 18, 1940, 9 p. [mimeo.].

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.

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.

Swann, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.

Weller, Stuart, 1913, Stratigraphy of the Chester Group in southwestern Illinois: Illinois State Academy of Science Transactions, v. 6, p. 118-129.

For additional information contact:

Nancy Hasenmueller (
Date last revised: August 26, 2014