Type designation:

Type area: The Bailey Limestone was named for exposures of argillaceous limestones and shales along the Mississippi River between Bailey's Landing and Red Rock Landing in Perry County, Missouri (E. O. Ulrich, as published by Buckley and Buehler, 1904, p. 110).

History of usage:

Extended: Collinson and others (1967, p. 940) delineated the general distribution of the Bailey in the Illinois Basin (Droste and Shaver, 1986).

Areal extent: Becker (1974) mapped its occurrence in the southwestern Indiana subsurface (Droste and Shaver, 1986). Although Silurian conodonts had been discovered in a part of the Bailey in Illinois (Collinson and others, 1967, p. 940), Becker (1974) treated the formation as mostly Devonian in age and included as its top part a few tens of feet of white medium- to coarse-grained pure bioclastic limestone as had been the practice in Illinois (Droste and Shaver, 1986).

Restricted: The upper limestone has been found to have Devonian conodonts and also to coextend with the Backbone Limestone (Lower Devonian). Becker and Droste (1978, p. 3-4) removed the uppermost limestone from the Bailey (Droste and Shaver, 1986). This reassignment left the Bailey of Indiana wholly within the Silurian System (Droste and Shaver, 1986).


The Bailey Limestone consists of drab, neutrally colored limestones and some dark-gray limestone (Droste and Shaver, 1986). They are mostly very fine grained, somewhat cherty, and slightly dolomitic (Droste and Shaver, 1986).

The Bailey has a reef-and-bank facies consisting of light-colored granular, rather pure carbonate rocks that are distributed in so-called "pinnacle reefs," in coalesced reef masses, and as reef detritus that helps to make up the feature called the Terre Haute Bank (Droste and Shaver, 1986). Insofar as known, the Bailey reef rocks are upward continuations of reefs that began to grow in the St. Clair Limestone and the Moccasin Springs Formation (Droste and Shaver, 1986).

Its nonreef thickness is as much as 375 ft (114 m) but reaches zero in its northern occurrence in Indiana, where the Bailey is erosionally truncated below Middle Devonian rocks (Droste and Shaver, 1986).


The bottom part of the Bailey Limestone is lithologically transitional to the Moccasin Springs Formation below, but the conformable contact is placed at the top of the blackish dense dolomitic shale and dark greenish-gray limestone of the Moccasin Springs (Droste and Shaver, 1986). The top of the Bailey is placed at the base of the whitish granular bioclastic Backbone Limestone (Droste and Shaver, 1986). This contact appears to be conformable in deeper basin areas but may be unconformable in the more distal basin area (Droste and Shaver, 1986). Middle Devonian rocks unconformably overlie the Bailey in a small part of its area of occurrence (Droste and Shaver, 1986).

The Bailey has a more or less vertical cutoff boundary with upper Wabash rocks along the basin margin of the Terre Haute Bank (Droste and Shaver, 1986).


Like all the formations in the Bainbridge Group, some diachroneity along contacts may apply to the basin-to-shelf relationships among these rocks as well as to the equivalent section eastward ranging upward from the Salamonie Dolomite and culminating in the Wabash Formation (Droste and Shaver, 1986). These general statements on correlation may be made, however: The Bailey of Indiana has coextension with the Bailey in the Illinois Basin parts of Illinois and Kentucky (Droste and Shaver, 1986). In Illinois, the highest Bailey rocks as generally defined there are Devonian in age and therefore are younger than the Bailey of Indiana. In Kentucky, an equivalent of the lower Bailey of Indiana is called the Decatur Limestone (Droste and Shaver, 1986). Northeastward in Indiana and northward and some westward in Illinois, upper Wabash rocks (Kokomo, Kenneth, and Liston Creek Members) and upper Racine rocks respectively are correlative of the Bailey of Indiana (Droste and Shaver, 1986).

Fossil data for the subsurface Bailey are sparse, but Silurian conodonts (Collinson and others, 1967) and Silurian ostracods (Schwalb, 1975; Becker and Droste, 1978, p. 4) have been found in Illinois and Kentucky (Droste and Shaver, 1986). These fossils and the principles of sequence stratigraphy suggest that the Bailey ranges from about late Ludlovian through Pridolian in age (Cayugan in the American standards) (Droste and Shaver, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Bainbridge Group
Formation: Bailey Limestone

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.

See also:

Liston Creek Limestone Member


Becker, L. E., 1974, Silurian and Devonian rocks in Indiana southwest of the Cincinnati Arch: Indiana Geological Survey Bulletin 50, 83 p.

Becker, L. E., and Droste, J. B., 1978, Late Silurian and Early Devonian sedimentologic history of southwestern Indiana: Indiana Geological Survey Occasional Paper 24, 14 p.

Buckley, E. R., and Buehler, H. A., 1904, Quarrying industry of Missouri: Missouri Bureau of Geology and Mines, 2nd Series, v. 2, 371 p.

Collinson, Charles, James, G. W., Swann, D. H., Becker, L. E., Carlson, M. P., Dorheim, F. H., and Koenig, J. W., 1967, Devonian of north-central region, United States, in International symposium on the Devonian System: Alberta Society of Petroleum Geologists, v. 1, p. 933-971.

Droste, J. B., and Shaver, R. H., 1986, Bailey 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. 8-9.

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.

Schwalb, H. R., 1975, Oil and gas in Butler County, Kentucky: Kentucky Geological Survey, ser. 10, Report of Investigations 16, 65 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.

For additional information contact:

Nancy Hasenmueller (
Date last revised: November 22, 2016