Age:

Mississippian

Type designation:

Type locality: Swann (1963, p. 45) named the unit for exposures in a road cut and nearby gullies to the west of a nearly abandoned roadway that climbs the Caseyville escarpment about 0.3 miles (.48 km) northwest of Cedar Grove Church and 1.25 miles (2.01 km) east of the village of Lick Creek, west line of the NE¼NW¼ sec. 31, T. 11 S., R. 2 E., Carbondale quadrangle, Johnson County, Illinois.

Reference section: The subsurface reference section in Indiana for the Grove Church is the interval from 1,725 to 1,764 ft (525.8 to 537.7 m) in the R. K. Petroleum Corporation No. 1 E. Bandy et al. well (Indiana Geological Survey Petroleum Database Management System No.112286), NE¼NW¼NW¼ sec. 10, T. 6 S., R. 14 W., Posey County (Droste and Keller, 1986).

History of usage:

Before designation as a separate formation, the Grove Church rocks were included in the subjacent Kinkaid Limestone (Droste and Keller, 1986).

Description:

The Grove Church Shale in Indiana is the uppermost formation of the Buffalo Wallow Group and is the youngest known Mississippian unit (Droste and Keller, 1986). The formation is predominantly fossiliferous shale in drab shades of medium and dark gray and green; brownish and grayish maroon are subordinate colors (Droste and Keller, 1986, 1995). The shale is thin bedded to platy and quite soft and appears to be free of siliceous material (Droste and Keller, 1986). Several thin beds of limestone as thick as 2 ft (0.6 m) are interbedded in the shale (Droste and Keller, 1986). The limestones are moderately fossiliferous light- to medium-brown and gray mudstones and wackestones; packstones are present in subordinate amounts (Droste and Keller, 1986, 1995). The maximum known thickness of the Grove Church in Indiana is 50 ft (15 m) (Droste and Keller, 1986, 1995).

Distribution: The Grove Church Shale is recognized only in the subsurface of Posey County (Droste and Keller, 1986).

Boundaries:

The Grove Church Shale conformably overlies the Kinkaid Limestone and may or may not conformably underlie rocks of Pennsylvanian age (Droste and Keller, 1986). In 1985, Rexroad and Merrill noted that uninterrupted deposition in marine environments locally prevailed across the Mississippian-Pennsylvanian boundary in the Illinois Basin, that is, across the Grove Church-Caseyville formational boundary (Droste and Keller, 1986, 1995).

Correlations:

No biostratigraphic data have been reported from the Grove Church in the subsurface of Indiana, but the probable age relations of the Grove Church may be inferred from the data obtained in studies of surface exposures in Illinois (Droste and Keller, 1986, 1995). Fusulinids of the genus Millerella that are found in the Grove Church have affinities with Pennsylvanian forms (Cooper, 1947). Rexroad and Burton (1961) reported that the Grove Church in Illinois contains conodonts of the Adetognathus unicornis Assemblage Zone, which are distinct from the fauna of the underlying Kinkaid Limestone (Droste and Keller, 1986, 1995).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Buffalo Wallow Group
Formation: Grove Church Shale

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

Mgc

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 features in Indiana.

Major tectonic features that affect bedrock geology in Indiana.

References:

Cooper, C. L., 1947, Upper Kinkaid (Mississippian) microfauna from Johnson County, Illinois: Journal of Paleontology, v. 21, p. 81–94.

Droste, J. B., and Keller, S. J., 1986, Grove Church Shale, 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. 53–54.

Droste, J. B., and Keller, S. J., 1995, Subsurface stratigraphy and distribution of oil fields of the Buffalo Wallow Group (Mississippian) in Indiana: Indiana Geological Survey Bulletin 63, 24 p.

Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7^th ed.): Washington, D.C., U.S. Geological Survey, 289 p.

Rexroad, C. B., and Burton, R. C., 1961, Conodonts from the Kinkaid Formation (Chester) in Illinois: Journal of Paleontology, v. 35, p. 1,143–1,158.

Rexroad, C. B., and Merrill, G. K., 1985, Conodont biostratigraphy and paleoecology of Middle Carboniferous rocks in southern Illinois: Courier Forschungsinstitut Senckenberg, v. 74, p. 35–64.

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.