IGNIS
Glen Dean Limestone

Age:

Mississippian

Type designation:

Type locality: Exposures near Glen Dean, Breckinridge County, Kentucky, were named the Glen Dean Limestone by Butts (1917, p. 97-102) (Gray, 1970; Gray and Horowitz, 1986).

History of usage:

The Glen Dean Limestone, as defined by Butts (1917, p. 97-102), consisted in descending order of 40 to 100 ft (12 to 30 m) of gray and red shale and thin beds of limestone, 30 to 60 ft (9 to 18 m) of gray crinoidal limestone, and as much as 10 ft (3 m) of red and green shale (Gray, 1970; Gray and Horowitz, 1986).

In Indiana rocks equivalent to the lowest of the three parts described above have long been a part of the Hardinsburg Formation (Malott and Thompson, 1920, p. 521-522; Malott, Esarey, and Bieberman, 1948, pl. 2; Gray, 1970; Gray and Horowitz, 1986). Equivalents of the upper part, formerly at least in part assigned to the Glen Dean, were excluded from the Glen Dean by Gray, Jenkins, and Weidman (1960, p. 38) to make the upper boundary more readily determinable and consistent (Gray and Horowitz, 1986). Thus defined, the name “Glen Dean” is applied in Indiana only to the main or massive limestone unit of former usage (Gray, 1970; Gray and Horowitz, 1986).

Description:

The Glen Dean Limestone is a thick-bedded skeletal to oolitic to biomicritic limestone (Gray, 1970; Gray and Horowitz, 1986). In Indiana the greatest known thickness of the Glen Dean Limestone is about 55 ft (16.8 m) in the shallow subsurface in southern Perry County (Droste and Keller, 1995). Throughout most of the subsurface in Indiana the formation ranges from 20 to 30 ft (6.1 to 9.1 m) in thickness (Droste and Keller, 1995).

Its typical fauna consists of brachiopods, blastoids of the genus Pentremites, and bryozoans including Archimedes (Perry and Smith, 1958, p. 94; Gray, 1970; Gray and Horowitz, 1986). Many of the faunal elements described in the literature on the Glen Dean come from shaly beds once regarded as upper Glen Dean but now assigned to the Tar Springs Formation (Gray and Horowitz, 1986). The fauna of the Glen Dean of present usage is not well documented but seems to include most of the larger invertebrates reported from the basal Tar Springs (Gray and Horowitz, 1986).

Distribution: The Glen Dean Limestone is known in surface exposures from south-central Greene County to the Ohio River and is recognized in the subsurface from Greene County southwestward (Gray, 1970; Gray and Horowitz, 1986).

Boundaries:

The Glen Dean Limestone conformably overlies the Hardinsburg Formation and is overlain with apparent conformity by the Tar Springs Formation or disconformably by the Mansfield Formation (Pennsylvanian) (Gray, 1970; Gray and Horowitz, 1986).

Correlations:

Although the name "Glen Dean" is applied throughout the Illinois Basin, the upper boundary of the Glen Dean is not consistently defined (Gray and Horowitz, 1986). In the subsurface of southwestern Indiana, a widely recognized limestone unit about 10 ft (3 m) thick and a little above the so-called main Glen Dean is commonly called the upper Glen Dean (Gray and Horowitz, 1986). This unit is thicker in Illinois where it is assigned to the Glen Dean proper and in places is a major part of the formation (Gray and Horowitz, 1986). In Kentucky an upper unit of variable thickness consisting of shale and thin beds of limestone and sandstone is retained in the Glen Dean (Gray and Horowitz, 1986).

The Glen Dean Limestone and overlying marine beds of the Tar Springs Formation are within the Zone of Pterotocrinus acutus Wetherby and embrace the ranges of P. bifurcates Wetherby and P. spatulatus Wetherby (Horowitz and Strimple, 1974) and the lower part of the range of the blastoid Pentremites broadheadi Hambach (= P. spicatus Ulrich) and its variants (Gray and Horowitz, 1986). These distinctive forms are readily recognizable in the field (Gray and Horowitz, 1986). In a broadly based paleontologic study, Horowitz and others (1979, p. 206) correlated the Glen Dean of northern Tennessee and therefore the Glen Dean of the Illinois Basin with rocks in North American foraminiferal Zone 17 of Mamet and Skipp (1971) and in the lower part of the Namurian Series (Zone El) of European usage (Gray and Horowitz, 1986). The Glen Dean has been assigned to the Gnathodus bitineatus-Kladognathus mehli Assemblage Zone of the standard North American conodont sequence (Collinson, Rexroad, and Thompson, 1971; Gray and Horowitz, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Stephensport Group
Formation: Glen Dean Limestone
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Stephensport Group
Formation: Glen Dean Limestone

Misc/Abandoned Names:

Little lime

Geologic Map Unit Designation:

Mgd

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.)

Map showing the COSUNA areas (heavy black line) that approximate regional bedrock outcrop patterns and major structural features in Indiana, and the COSUNA numbers (large bold font) for these areas. The COSUNA boundaries are limited to state and county boundaries that facilitate coding.

COSUNA areas and numbers that approximate regional bedrock outcrop patterns and major structural features in Indiana.

Map showing major tectonic features that affect bedrock geology in Indiana.

Major tectonic features that affect bedrock geology in Indiana.

References:

Butts, Charles, 1917, Mississippian formations of western Kentucky: Descriptions and correlations of the Mississippian formations of western Kentucky: Kentucky Geological Survey, ser. 4, v. 5, pt. 1, 119 p.

Collinson, Charles, Rexroad, C. B., and Thompson, T. L., 1971, Conodont zonation of the North American Mississippian: Geological Society of America Memoirs 127, p. 353-394.

Droste, J. B., and Keller, S. J., 1995, Subsurface stratigraphy and distribution of oil fields of the Stephensport Group (Mississippian) in Indiana: Indiana Geological Survey Bulletin 64, 21 p.

Gray, H. H., 1970, Glen Dean Limestone, 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. 64-65.

Gray, H. H., and Horowitz, A. S., 1986, Glen Dean 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. 52-53.

Gray, H. H., Jenkins, R. D., and Weidman, R. M., 1960, Geology of the Huron area, south-central Indiana: Indiana Geological Survey Bulletin 20, 78 p.

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.

Horowitz, A. S., and Strimple, H. L., 1974, Chesterian echinoderm zonation in eastern United States: Septieme Congres International de Stratigraphie et de Geologie du Carbonifere Krefeld, August 23-28, 1971, Compte rendu, v. 3, p. 209-220.

Horowitz, A. S., Mamet, B. L., Neves, R., Potter, P. E., and Rexroad, C. B., 1979, Carboniferous paleontological zonation and intercontinental correlation of the Fowler No. 1 Traders core, Scott County, Tennessee, U.S.A.: Southeastern Geology, v. 20, p. 205-228.

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.

Mamet, B. L., and Skipp, B. A., 1971, Lower Carboniferous calcareous Foraminifera–preliminary zonation and stratigraphic implications for the Mississippian of North America: Sixieme Congres International de Stratigraphie et de Geologie du Carbonifere Sheffield, 1967, Compte rendu, v. 3, p. 1,129-1,146.

Perry, T. G., and Smith, N. M., 1958, The Meramec-Chester and intra-Chester boundaries and associated strata in Indiana: Indiana Geological Survey Bulletin 12, 110 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 (hasenmue@indiana.edu)
Date last revised: July 28, 2016

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