Age:

Silurian

Type designation:

Type section: The Kenneth Limestone Member was named as a formation by Cumings and Shrock (1927, p. 77) for about 30 ft (9 m) of light-colored dense to fine-grained bedded to massive cherty limestone that is typically exposed in an abandoned France Stone Co. quarry near Kenneth, Cass County, Indiana (Shaver, 1970; Droste and Shaver, 1986).

History of usage:

Location of type section: Pinsak and Shaver (1964, p. 81) thought that, according to Cumings and Shrock (1928, p. 134), the Kenneth type section is in the large composite quarry in the center of sec. 30 and in the N½SW¼ sec. 30, T. 27 N., R. 1 E. (Shaver, 1970; Droste and Shaver, 1986). Some question remains, however, about the location of the type section because Cumings and Shrock (1928, p. 177) also mentioned quarrying in the adjoining section (sec. 25, T. 27 N., R. 1 W.); also, because still another large quarry, once operated by the same company that operated the composite quarry, is in the SW¼SE¼ sec. 30 (Shaver, 1970; Droste and Shaver, 1986). The Kenneth in this area both overlies and appears to be interlensed with laminated dolomitic limestone assigned to the Kokomo Limestone Member (Wabash Formation) (Droste and Shaver, 1986).

Change in rank: The rank of the Kenneth was changed to that of member by Pinsak and Shaver (1964, p. 51) and assigned to the Salina Formation (Droste and Shaver, 1986).

Change in assignment: The Kenneth was later assigned to the Wabash Formation when the latter unit, together with the Pleasant Mills Formation, was assigned to the elevated-in-rank Salina Group (Droste and Shaver, 1982, p. 21; Droste and Shaver, 1986).

Description:

Besides the Kenneth lithologic features noted above, the unit appears to be coarsely mottled in places (in its fine-grained facies); in some other places it consists of whitish to pinkish granular (even sparry) limestone that commonly is abundantly fossiliferous (Droste and Shaver, 1986). This facies includes coquinas of brachiopods (for example, Coelospira congregata and pentamerid brachiopods) and ranges in its character to reef-framework rock (dolomitized in places) complete with abundant corals of the Halysites and Coenites types (Droste and Shaver, 1986).

The Kenneth has very limited distribution because of the definitive intraformational relations within the Wabash (Droste and Shaver, 1982, p. 23). Its basic character as cherty dolomitic limestone and its high stratigraphic position hardly distinguish the Kenneth from the similar Liston Creek; the Kenneth is to be distinguished, therefore, only where Silurian rocks of its type are underlain by the distinctively laminated Kokomo Member (Droste and Shaver, 1986). The Kenneth ranges in thickness from an erosional zero to an average of 25 to 30 ft (7.6 to 9.2 m) and a maximum of about 45 ft (14 m) where this unit is beneath Devonian cover (Droste and Shaver, 1986).

Distribution: The Kenneth is hardly known outside the type county (Cass), although older reports of its occurrence in Howard County above the Kokomo are surely correct (Droste and Shaver, 1986). It is now known in Miami County (Ault and Carr, 1983, p. 24; Shaver and Sunderman, 1983, p. 177-178), but its occurrence there was said to be of the Liston Creek in older literature (Droste and Shaver, 1986). As a matter of similar confusion, older reports of the Kenneth in Carroll County have proved to refer to other rocks, but a modern report (Indiana University Paleontology Seminar, 1980) has again identified probable Kenneth rocks in Carroll County (Droste and Shaver, 1986).

Boundaries:

The lower Kenneth contact appears to be fairly sharp in places but involves gradational lithology with the Kokomo in others (Droste and Shaver, 1986). The sand grains and other clastic sediments found in many places associated with this contact are not evidence of intra-Silurian unconformity rather, of pre-Middle Devonian karst (Droste and Shaver, 1986). The upper Kenneth contact everywhere coincides with the pre-Middle Devonian unconformity (Droste and Shaver, 1986).

Correlations:

Within the Wabash, the Kenneth correlates with an upper part of the Liston Creek, this being a matter of coextension, but the highest Liston Creek rocks in Indiana, both on the northern outcrop and in the southwestern subsurface, are possibly slightly younger than the Kenneth (Droste and Shaver, 1986). The Kenneth, therefore, correlates, as do upper Liston Creek rocks, with the upper part of the Bailey Limestone of the Illinois Basin (Droste and Shaver, 1986). Further, the Kenneth is known to have rare kinds of pentamerid brachiopods that in Illinois and Indiana are known only in high stratigraphic positions, but the collective conodont and ostracod evidence indicates a very late Silurian age (Pridolian in European terms; late Cayugan in American terms) (Droste and Shaver, 1986). The ostracod fauna, abundantly represented by Dizygopleura hallii and Thlipsurella parva, and associated fossils suggest even a post-Salina age and correlation with highest Silurian rocks of New York and other Appalachian Basin states, but the conodonts have not yet been definitive between late-Salina depositional time or post-Salina (Bass Islands Group) depositional time with respect to the Salina section of the Michigan Basin parts of northern Indiana, northwestern Ohio, and southern Michigan (Droste and Shaver, 1986).

Economic Importance:

Industrial Minerals: Cement products from the Kenneth Limestone Member (Silurian) include the following: Portland cement from a quarry in Cass County (Shaffer, 2016).

Crushed stone products from the Kenneth Limestone Member (Silurian) include the following: aglime, crushed stone, crushed stone for Portland masonry cement production, flagstone, riprap, screenings, and shot rock from quarries in Cass, and Miami Counties (Shaffer, 2016).

Regional Indiana usage:

Kankakee Arch (COSUNA 14)
Supergroup: none
Group: Salina Group
Formation: Wabash Formation
Member: Kenneth Limestone Member
Michigan Basin (COSUNA 15)
Supergroup: none
Group: Salina Group
Formation: Wabash Formation
Member: Kenneth Limestone Member

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

Swkn

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:

Ault, C. H., and Carr, D. D., 1983, Directory of crushed stone, ground limestone, cement, and lime producers in Indiana: Indiana Geological Survey Directory [unnumbered], 36 p.

Cumings, E. R., and Shrock, R. R., 1927, The Silurian coral reefs of northern Indiana and their associated strata: Indiana Academy of Science Proceedings, v. 36, p. 71–85.

Cumings, E. R., and Shrock, R. R., 1928, The geology of the Silurian rocks of northern Indiana: Indiana Department of Conservation Publication No. 75, 226 p.

Droste, J. B., and Shaver, R. H., 1982, The Salina Group (Middle and Upper Silurian) of Indiana: Indiana Geological Survey Special Report 24, 41 p.

Droste, J. B., and Shaver, R. H., 1986, Kenneth 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. 67–68.

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.

Indiana University Paleontology Seminar, 1980, Stratigraphy, structure, and zonation of large Silurian reef at Delphi, Indiana: American Association of Petroleum Geologists Bulletin, v. 64, p. 115–131.

Pinsak, A. P., and Shaver, R. H., 1964, The Silurian formations of northern Indiana: Indiana Geological Survey Bulletin 32, 87 p.

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

Shaver, R. H., 1970, Kenneth 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. 81–82.

Shaver, R. H., and Sunderman, J. A., 1983, Silurian reef and interreef strata as responses to a cyclical succession of environments, southern Great Lakes area (Field Trip 12), in Shaver, R. H., and Sunderman, J. A., eds., Field trips in midwestern geology: Bloomington, Indiana, Geological Society of America, Indiana Geological Survey, and Indiana University Department of Geology, v. 1, p. 141–196.

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.