Type designation:

Type locality: Near the town of Borden in Clark County, Indiana (Cumings, 1922, p. 487) (Borden quadrangle).

History of usage:

Name: The name "Borden" was proposed to replace the older nongeographic term Knobstone (Rexroad, 1986).


The Borden Group includes three formations that represent three major deposition settings: the New Providence Shale resulted from prodelta deposits, the Spickert Knob Formation from delta-slope deposits, and the Edwardsville Formation from delta-platform deposits (Rexroad, 1986). The Borden is composed dominantly of gray argillaceous siltstone and of shale; fine-grained sandstone is common (Rexroad, 1986). Interbedded limestones form discontinuous lenses and facies that are minor except for the interval of the Floyds Knob Limestone Member at the base of the Edwardsville Formation (Rexroad, 1986).

The Borden ranges from about 485 to 800 ft (138 to 244 m) in thickness on outcrop (Stockdale, 1939, p. 27).

Distribution: The Borden outcrop belt is as much as 36 miles (58 km) wide and extends in Indiana from the Ohio River in southern Harrison County northward and northwestward to Benton County (Rexroad, 1986).

The group consists of a series of lobate deltaic pods of sediment that thin in a southwesterly direction; the group is represented only by very thin time-equivalent shale in the subsurface of the southwesternmost part of Indiana (Rexroad, 1986; Rupp, 1991, fig. 27). North of Putnam and Parke Counties thinning of the unit is the result of the Mississippian-Pennsylvanian erosional unconformity (Pinsak, 1957, p. 30).


The Borden Group rests on the Rockford Limestone or, where that is absent, on the New Albany Shale (Gates and Rexroad, 1970; Rexroad, 1986). It is unconformable at the base except in northwestern Indiana, where it is apparently conformable with the Rockford (Rexroad and Scott, 1964, p. 19). The Borden is overlain with apparent disconformity by the Ramp Creek Formation and the laterally equivalent Muldraugh Formation (Rexroad, 1986). Along the northern part of the Borden outcrop area in central western Indiana, the Mississippian-Pennsylvanian unconformity truncates younger Mississippian rocks down to the New Albany Shale, so that the Mansfield Formation (Morrowan) overlies the Borden Group in part of that area (Rexroad, 1986).


In Kentucky, the Borden Group is termed the "Borden Formation" and includes the Muldraugh Member, which is a postdeltaic equivalent of the Ramp Creek Formation (Rexroad, 1986). The Muldraugh was deposited in the topographic basin left after cessation of Borden sedimentation and is not time correlative with any part of the Borden Group of Indiana (Rexroad, 1986). In Illinois, the group is represented in the subsurface by the Borden Siltstone, and according to Shaver (1984), it correlates with the Springville and Warsaw Shales, the Fern Glen Formation, and the Meppen, Burlington, and Keokuk Limestones. Rexroad and Scott (1964, p. 19) showed that the base of the Borden Group in Benton County was in the Bactrognathus-Polygnathus communis Assemblage Zone (conodonts) and correlated with the lower part of the Burlington Limestone of the upper Mississippi Valley. In part of southern Indiana the base belongs in the younger Bactrognathus-Taphrognathus Assemblage Zone and is no older than late Burlington in age (Rexroad, 1986). Indeed, a number of workers (for example, Kammer, Ausich, and Lane, 1983; Kammer, 1984; Butts, 1915) correlated the lower interval with the Keokuk Limestone. Conodonts recovered from the Floyds Knob Limestone Member of the Edwardsville Formation indicated correlation with part of the Keokuk Limestone of the upper Mississippi Valley (Gates and Rexroad, 1970; Whitehead, 1978), as did crinoids from the upper part of the group in Montgomery County (Van Sant and Lane, 1964).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Borden Group
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Borden Group
Cincinnati Arch (COSUNA 13)
Supergroup: none
Group: Borden Group
Kankakee Arch (COSUNA 14)
Supergroup: none
Group: Borden Group

Misc/Abandoned Names:

Borden Series, Borden Siltstone, Knobstone

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, 1915, Geology and mineral resources of Jefferson County, Kentucky: Kentucky Geological Survey, ser. 4, v. 3, pt. 2, 270 p.

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.

Gates, G. R., and Rexroad, C. B., 1970, Borden Group, 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. 20-22.

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.

Kammer, T. W., 1984, Crinoids from the New Providence Shale Member of the Borden Formation (Mississippian) in Kentucky and Indiana: Journal of Paleontology, v. 58, p. 115-130.

Kammer, T. W., Ausich, W. I., and Lane, N. G., 1983, Paleontology and stratigraphy of the Borden delta of southern Indiana and northern Kentucky (Field Trip 2), in Shaver, R. H., and Sunderman, J. A., eds., Field trips in midwestern geology: Bloomington, Indiana, Geological Society of America, Indiana Geological Survey, and Indiana University Department of Geology, p. 37-71.

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., 1986, Borden Group, 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. 17-18.

Rexroad, C. B., and Scott, A. J., 1964, Conodont zones in the Rockford Limestone and the lower part of the New Providence Shale (Mississippian) in Indiana: Indiana Geological Survey Bulletin 30, 54 p.

Rupp, J. A., 1991, Structure and isopach maps of the Paleozoic rocks of Indiana: Indiana Geological Survey Special Report 48, 106 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.

Stockdale, P. B., 1939, Lower Mississippian rocks of east-central interior (U.S.): Geological Society of America Special Paper 22, 248 p.

Van Sant, J. F., and Lane, N. G., 1964, Crawfordsville (Indiana) crinoid studies: University of Kansas Paleontological Contributions, Echinodermata, art. 7, 136 p.

Whitehead, N. D., III, 1978, Lithostratigraphy, depositional environments, and conodont biostratigraphy of the Muldraugh Formation (Mississippian) in southern Indiana and north-central Kentucky: Southeastern Geology, v. 19, p. 83-109.

For additional information contact:

Nancy Hasenmueller (
Date last revised: December 6, 2013