Type designation:

Type section: The name “Siberia Limestone” was introduced by Malott and Thompson (1920); however, they did not define the unit (Burger, 1970; Gray, 1986). Malott (1925, p. 110) described the Siberia and designated a type section in the J. Schilling quarry, 2.5 miles (4 km) southeast of Siberia in northern Perry County (Burger, 1970; Gray, 1986).

History of usage:

Equivalence of this bed to the Menard Limestone of southwestern Illinois was later asserted (Malott, 1931, p. 222), and the name “Siberia” was abandoned (Gray, 1986). The scope of the Menard as applied in Indiana was expanded by Malott and Esarey (1940) and Malott, Esarey, and Bieberman (1948), but boundary criteria were never specified (Gray, 1986).

Recognizing that this thin bed of limestone did not represent the entire Menard as most widely understood, Rexroad and Nicoll (1965, p. 8-9) reinstated the Siberia as a member of what they designated as the Menard Formation (Gray, 1986). The limits of that formation, however, remained unspecified, and in a restudy of outcropping upper Chesterian rocks, Gray (1978, p. 11) placed the Siberia Limestone Member within the newly named Tobinsport Formation (Gray, 1986).


Near its type locality the Siberia Limestone Member commonly is a single bed of gray skeletal limestone 3 to 5 ft (0.9 to 1.5 m) thick; southward it is a somewhat thinner yellow-brown micrite and is discontinuous (Gray, 1986). To the north, in eastern Dubois County, isolated limestone exposures as much as 20 ft (6 m) thick are uncertainly identified as Siberia; they may instead represent the Leopold Limestone Member, which is stratigraphically somewhat lower (Gray, 1986).


The Siberia Limestone Member appears to be a tongue of the so-called main or massive Menard of subsurface usage, and therefore it probably represents a part of the Scottsburg Limestone Member of the Menard Limestone in the standard Chesterian section of Swann (1963, p. 38-40) and Atherton, Collinson, and Lineback (1975, p. 160) (Gray, 1986). Conodont studies by Rexroad and Nicoll (1965) support this correlation and place the Siberia and associated shale near the base of the Kladognathus-Cavusgnathus naviculus Assemblage Zone (Gray, 1986). Some of the sites they reported, however, are now assigned to the Leopold Limestone Member (Gray, 1986). The Siberia Limestone Member correlates with rocks within the Namurian Series of European usage, probably those near the boundary of Zones El and E2 (Gray, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Buffalo Wallow Group
Formation: Tobinsport Formation
Member: Siberia Limestone 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.


Atherton, Elwood, Collinson, Charles, and Lineback, J. A., 1975, Mississippian System, in Willman, H. B., Atherton, Elwood, Buschbach, T. C., Collinson, Charles, Frye, J. C., Hopkins, M. E., Lineback, J. A., and Simon, J. A., Handbook of Illinois stratigraphy: Illinois State Geological Survey Bulletin 95, p. 123-163.

Burger, A. M., 1970, Siberia Limestone Member, 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. 166.

Gray, H. H., 1978, Buffalo Wallow Group upper Chesterian (Mississippian) of southern Indiana: Indiana Geological Survey Occasional Paper 25, 28 p.

Gray, H. H., 1986, Siberia Limestone 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. 143-144.

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.

Malott, C. A., 1925, The upper Chester of Indiana: Indiana Academy of Science Proceedings, v. 34, p. 103-132.

Malott, C. A., 1931, Geologic structure in the Indian and Trinity Springs locality, Martin County, Indiana: Indiana Academy of Science Proceedings, v. 40, p. 217-231.

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.].

Malott, C. A., and Thompson, J. D., Jr., 1920, The stratigraphy of the Chester Series of southern Indiana [abs.]: Science, new ser., v. 51, p. 521-522.

Malott, C. A., Esarey, R. E., and Bieberman, D. F., 1948, Upper and Middle Mississippian formations of southern Indiana: Indiana Division of Geology Field Conference Guidebook 2, 27 p.

Rexroad, C. B., and Nicoll, R. S., 1965, Conodonts from the Menard Formation (Chester Series) of the Illinois Basin: Indiana Geological Survey Bulletin 35, 28 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.

For additional information contact:

Nancy Hasenmueller (
Date last revised: April 7, 2017