Type area: Weiss and Sweet (1964) proposed the name "Kope Formation" for 240 ft (75 m) of shale and minor interbedded limestone that "lies between the Point Pleasant formation and shaly limestones equivalent to the Fairmount and MacMillan formations" in the Maysville area of Kentucky and Ohio (Burger, 1970; Gray, 1986). The name was taken from Kope Hollow north of Levanna, Ohio (Burger, 1970; Gray, 1986).
History of usage:
Former names: The Kope Formation includes the lowermost Cincinnatian rocks, rocks that were formerly for the most part assigned to the Eden Shale or the Eden Group (Gray, 1986). Gray (1986) noted that those terms had acquired a chronostratigraphic connotation and that the name “Kope Formation” is intended to be strictly lithographic.
The Kope Formation includes not only the bluish- to brownish-gray shale that is exposed at many places in the classic outcrop area in southeastern Indiana but also a thick basal dark-brown to nearly black shale that is known only in the subsurface, the Utica Shale of drillers' old terminology (Gray, 1986). As illustrated and described by Gray (1972), more than 95 percent of the formation is shale, and in places as much as two-thirds of the shale is brown (Gray, 1986).
The upper contact of the Kope Formation is apparently conformable but is picked at different horizons in different places because the criterion that distinguishes the Kope from the overlying Dillsboro Formation is the dominance of shale in the Kope as contrasted to a significant, though not dominant, amount of limestone in the Dillsboro (Gray, 1986). In many places this contact must be arbitrarily placed in a transitional sequence (Gray, 1986). The basal contact of the Kope is more complex (Gray, 1986). In southeastern most Indiana the Kope conformably overlies the Lexington Limestone, but limestone of that formation gives way northwestward and interfingers with dark shale of the basal Kope (Gray, 1972, fig. 9). In a narrow linear area that extends from southern Franklin County to northern Harrison County, basal dark shale of the Kope Formation overlies the Plattin Formation of the Black River Group (Keith, 1985). Northwest of that area, and to the limit of its recognition, the Kope Formation overlies the Trenton Limestone along a time-transgressive discontinuity (Brian D. Keith, oral communication, 1984; Gray, 1986).
The greater part of the body of rocks now assigned to the Kope Formation was once explicitly assigned to the Eden Group; this part of the formation is now considered to be Edenian in age (Gray, 1986). The dark shale that forms the basal part of the Kope, however, is in part late Champlainian in age (Sweet and Bergstrom, 1971, fig. 2), and to the extent that the upper contact of the formation steps upward to the northwest, some of the Kope in that area may be Maysvillian in age (Gray, 1986).
Regional Indiana usage:
Cincinnati Arch (COSUNA 13)
Eden Group, Eden Shale, Utica Shale
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 features in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Brown, G. D., Jr., and Lineback, J. A., 1966, Lithostratigraphy of Cincinnatian Series (Upper Ordovician) in southeastern Indiana: American Association of Petroleum Geologists Bulletin, v. 50, p. 1,018–1,023.
Burger, A. M., 1970, Kope 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. 85–86.
Gray, H. H., 1986, Kope 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. 72–73.
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.
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.
Sweet, W. C., and Bergstrom, S. M., 1971, The American Upper Ordovician standard–[Pt.] 13, A revised time-stratigraphic classification of North American upper Middle and Upper Ordovician rocks: Geological Society of America Bulletin, v. 82, p. 613–627.
Weiss, M. P., and Sweet, W. C., 1964, Kope Formation (Upper Ordovician)—Ohio and Kentucky: Science, v. 145, p. 1,296–1,302.
For additional information, contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: October 27, 2014