Age:

Devonian

Type designation:

Type locality: The name “Geneva Limestone” was first used by Collett (1882, p. 63, 81, and 82) for exposures of a buff dolomitic limestone exposed along the Flat Rock River near Geneva, Shelby County, Indiana (Burger and Patton, 1970; Droste and Shaver, 1986).

Reference sections: No type section was designated, but the following reference sections were suggested by Burger and Patton (1970, p. 62).

(1) 23.7 ft (7.2 m) in the McCorkle Stone Co. quarry near Milroy, Rush County, in the SW¼ sec. 8, T.12 N., R. 9 E.,

(2) 28.6 ft (8.7 m) in the Meshberger Stone Co. quarry, Bartholomew County, in the SE¼SE¼NE¼ sec. 6, T. 8 N., R. 7 E. (Elizabethtown quadrangle), and

(3) 20 ft (6.1 m) in the Standard Materials quarry near Hanover, Jefferson County, in the SE¼SE¼ sec. 16, T. 3 N., R. 9 E. (Droste and Shaver reported in 1986 that this quarry was underwater.)

Droste and Shaver (1986) designated the two following reference sections because they felt that the sections reveal the differing relations that the Geneva has with the classic biozones described in the Jeffersonville Limestone at the Falls of the Ohio.

(1) A section along Big Camp Creek, Jefferson County, Indiana, in the NE¼NE¼SW¼ sec. 13, T. 4 N., R. 8 E. This section was described by Dawson (1941, p. 38) and Shaver (1974, p. 4). Here the Geneva underlies a part of the Coral Zone.

(2) A section in the North Vernon quarry, formerly the Berry Materials Corp. quarry, at North Vernon, Jennings County, Indiana, in the NE¼ sec. 34, T. 7 N., R. 8 E. (Butlerville quadrangle). This section was described by Patton and Dawson (1955, p. 24-96) and Droste and Shaver (1975, p. 405). Here the Geneva underlies the Amphipora Zone and the Coral Zone is not recognized.

History of usage:

Foerste (1898, p. 234-235) called these same rocks the Shelby Bed. Most early usage, however, was "Geneva," and in accord with the advice of Kindle (1901, p. 536), the term “Shelby” was abandoned (Droste and Shaver, 1986).

The term “Geneva Formation” was used by Dawson (1941).

Droste and Shaver (1975, p. 403-404) designated this unit as the Geneva Dolomite Member of the Jeffersonville Limestone.

Description:

The Geneva Dolomite Member is typically a calcareous dolostone that is buff to chocolate brown, rather soft, granular, and vuggy and that contains bands and partings of carbonaceous material (Burger and Patton, 1970; Droste and Shaver, 1986). It is massive to thick bedded in its lower part and more commonly thin bedded in its upper part (Burger and Patton, 1970; Droste and Shaver, 1986). The distinctive colors are due to a high organic content, and near-surface beds are commonly oxidized to pale tan, cream, or even white. White crystalline, coarsely cleavable calcite masses (spar) ranging from 1 inch to more than 1 foot (0.3 m) in cross section, resulting from calcification of fossils, are scattered through the fine-grained dolomite matrix (Burger and Patton, 1970; Droste and Shaver, 1986). Some calcite masses make up beautifully preserved, taxonomically identifiable fossil casts (Droste and Shaver, 1986). Chert is present in some sections, and quartz sand is especially common in basal rocks.

Although dolomitization is pervasive, pelletoidal, burrowed, and bioclastic textures (including those referred to grainstones and packstones) and molds, casts, and other evidences of many kinds of highly altered fossils are recognized (Droste and Shaver, 1986).

The Geneva variably overlies other Jeffersonville rocks (Dutch Creek Sandstone Member, subsurface area) conformably and Silurian rocks unconformable that range stratigraphically from the upper part of the Salamonie Dolomite to the lower part of the Wabash Formation (Droste and Shaver, 1986). It is overlain variably and conformably by other Jeffersonville rocks, including those of the Coral and Amphipora Zones and of the Vernon Fork Member (Droste and Shaver, 1986). It ranges in thickness from zero foot to more than 60 ft (18 m) in its roughly semicircular area of distribution in the parts or all of about 30 counties of central and central western Indiana (Droste and Shaver, 1975, fig. 8; Droste and Shaver, 1986). Along the northern and eastern limits of the Geneva, the zero thickness is due to erosion, but the southern zero limit is a nondepositional and facies effect (Droste and Shaver, 1986).

Correlations:

Despite the abundance of fossil material in the Geneva, age assessment and correlation have long been controversial for at least three reasons: (1) preservation for taxonomic purposes is poor, (2) outcrop and subsurface studies tend to support different conclusions, and (3) age and correlation are partly matters of different definitions of what shall constitute the Geneva (Droste and Shaver, 1986).

Early 20th century geologists thought that the Geneva was a facies of the Jeffersonville Limestone or was a facies of both the Jeffersonville Limestone and the overlying North Vernon (Sellersburg) Limestone (Burger and Patton, 1970), or that it was Schoharie (pre-Onondaga, New York standard) in age on the basis of its fossils (Droste and Shaver, 1986). In a middle period of study, Sutton and Sutton (1937, p. 331) considered that the Geneva, on the basis of faunal study, was a northward facies of the Jeffersonville (Burger and Patton, 1970; Droste and Shaver, 1986). Patton and Dawson (1955, p. 37) and, by inference, Dawson (1941, p. 25-27), however, considered that Sutton and Sutton's (1937) sections and Kindle's (1913) fossils belonged to the Jeffersonville rather than to the Geneva (Droste and Shaver, 1986). The semantics of definition, therefore, seem to have been part of a continuing problem.

Subsurface studies have supported the idea of a Geneva-Jeffersonville facies relationship, for example, those of Meents and Swann (1965), who correlated the Geneva with lower Grand Tower Limestone (Jeffersonville rocks in Illinois), and those of Becker (1974) (Droste and Shaver, 1986). Droste and Shaver (1975), taking the already extant subsurface view, acknowledged (p. 404) that definition of what rocks should be called the Geneva enters into a solution to the correlation problem and presented evidence in itself for a Geneva-lower Jeffersonville relationship (Droste and Shaver, 1986). In their understanding, the Geneva correlates not only with other lower Jeffersonville and Grand Tower rocks but also with a lower to middle part of the Detroit River rocks in the Michigan Basin part of northern Indiana and adjacent Ohio and with lower Onondaga rocks in the Devonian standard of New York (Droste and Shaver, 1986).

Economic Importance:

Industrial Minerals: Crushed stone products from the Geneva Dolomite Member (Devonian) include the following: aglime, crushed stone, riprap and manufactured sand from quarries in Bartholomew, Clark, Jennings, Marion, Rush, and Shelby Counties (Shaffer, 2016).

Dimension stone products from the Geneva Dolomite Member (Devonian) include the following: hand-picked building stone from a quarry in Rush County (Shaffer, 2016).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Geneva Dolomite Member
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Geneva Dolomite Member
Cincinnati Arch (COSUNA 13)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Geneva Dolomite Member
Kankakee Arch (COSUNA 14)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Geneva Dolomite Member

Misc/Abandoned Names:

Shelby Bed

Geologic Map Unit Designation:

Djg

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:

Becker, L. E., 1974, Silurian and Devonian rocks in Indiana southwest of the Cincinnati Arch: Indiana Geological Survey Bulletin 50, 83 p.

Burger, A. M., and Patton, J. B., 1970, Geneva Dolomite, 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. 62–64.

Collett, John, 1882, Geology of Shelby County: Indiana Department of Geology and Natural History Annual Report 11, p. 55–88.

Dawson, T. A., 1941, Outcrop in southern Indiana, pt. 1 of The Devonian formations of Indiana: Indiana Division of Geology, 48 p.

Droste, J. B., and Shaver, R. H., 1975, The Jeffersonville Limestone (Middle Devonian) of Indiana—stratigraphy, sedimentation, and relation to Silurian reef-bearing rocks: American Association of Petroleum Geologists Bulletin, v. 59, p. 393–412.

Droste, J. B., and Shaver, R. H., 1986, Geneva Dolomite 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. 50–52.

Foerste, A. F., 1898, A report on the Niagara limestone quarries of Decatur, Franklin, and Fayette Counties, with remarks on the geology of the Middle and Upper Silurian rocks of these and neighboring (Ripley, Jennings, Bartholomew, and Shelby) counties: Indiana Department of Geology and Natural Resources Annual Report 22, p. 195–256.

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.

Kindle, E. M., 1901, The Devonian fossils and stratigraphy of Indiana: Indiana Department of Geology and Natural Resources Annual Report 25, p. 529–758.

Kindle, E. M., 1913, The unconformity at the base of the Onondaga Limestone of New York and its equivalent west of Buffalo: Journal of Geology, v. 21, p. 301–319.

Meents, W. F., and Swann, D. H., 1965, Grand Tower Limestone (Devonian) of southern Illinois: Illinois State Geological Survey Circular 389, 34 p.

Patton, J. B., and Dawson, T. A., 1955, Stratigraphy, in Murray, H. H., compiler, Sedimentation and stratigraphy of the Devonian rocks of southeastern Indiana: Indiana Geological Survey Field Conference Guidebook 8, p. 16, 21–22, 25–26, and 37–43.

Shaffer, K. R., compiler, 2016, Directory of industrial mineral producers in Indiana: Indiana Geological Survey Directory 11-2016, 287 p.

Shaver, R. H., 1974, The Muscatatuck Group (new Middle Devonian name) in Indiana: Indiana Geological Survey Occasional Paper 3, 7 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.

Sutton, D. G., and Sutton, A. H., 1937, Middle Devonian of southern Indiana: Journal of Geology, v. 45, p. 320–331.

Wilmarth, M. G., 1938, Lexicon of geologic names of the United States (including Alaska): U.S. Geological Survey Bulletin 896, 2,396 p.