Type designation:

Type locality: The name "Cypress Sandstone" was first used by Engelmann (1863, p. 189-190) for massive sandstone exposures in the bluffs along Cypress Creek, Union County, Illinois (Burger, 1970; Gray, 1986).

History of usage:

Revised: As redescribed by Swann (1963, p. 35) and Atherton and others (1975, p. 155), the Cypress is a complex of sandstone bodies totaling 100 ft (30 m) or more in thickness (Gray, 1986).

Miscorrelation: Following usage established by Malott (1919), the name "Cypress Sandstone" was for many years incorrectly applied in Indiana to the somewhat younger unit now called the “Big Clifty Formation” (Burger, 1970; Gray, 1986). The Cypress Formation is equivalent to the Elwren Formation of Indiana outcrop terminology (Burger, 1970; Gray, 1986).


According to Puscas (1953) the Cypress Formation consists of white fine- to medium-grained sandstone, gray siltstone, and shale (Burger, 1970). It reaches a maximum thickness of 125 ft (38 m) (Gray, 1986).

Distribution: The Cypress extends from Parke and Owen Counties southwestward (Gray, 1986). According to Sullivan (1972, p. 20), the Cypress is recognizable in only about 40 percent of its potential area of distribution because over wide areas the underlying Reelsville Limestone is absent (Gray, 1986).


The Cypress is underlain conformably by the Reelsville Limestone where the Reelsville is present. But, where that formation is absent, in and adjacent to an area called the "West Baden clastic belt," the position of the base of the Cypress cannot be determined because of the lithologic similarity of the Cypress to the underlying Sample Formation (Gray, 1986). The Cypress Formation is overlain conformably by the Beech Creek Limestone or disconformably by the Mansfield Formation (Morrowan) (Gray, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: West Baden Group
Formation: Cypress Formation

Misc/Abandoned Names:

Cypress Sand

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:

Elwren Formation


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, Cypress Formation, 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. 41.

Engelmann, Henry, 1863, On the Lower Carboniferous System in northern Illinois: Academy of Science of St. Louis Transactions, v. 2, p. 188-190.

Gray, H. H., 1986, Cypress Formation, 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. 33-34.

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., 1919, The "American Bottoms" region of eastern Greene County, Indiana–a type unit in southern Indiana physiography: Indiana University Studies, v. 6, no. 40, 61 p.

Puscas, George, 1953, The study of the Aux Vases Formation in the Monroe City oil field, Knox County, Indiana: Bloomington, Indiana University, master's thesis, 33 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.

Sullivan, D. M., 1972, Subsurface stratigraphy of the West Baden Group in Indiana: Indiana Geological Survey Bulletin 47, 31 p.

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: November 30, 2016