Type locality: According to reviews by Templeton and Willman (1963) and Buckley and Buehler (1904, p. 111), the name "Plattin" was originally proposed, but not published, by E. O. Ulrich for exposures along Plattin Creek, Jefferson County, Missouri (Droste and Patton, 1986).
History of usage:
Reclassification: After long use of the term “Plattin Limestone or Formation” in the upper Mississippi Valley area, the rocks of this unit were reclassified as a subgroup in the Platteville Group of Illinois (Templeton and Willman, 1963, p. 78; Droste and Patton, 1986). In Illinois they were underlain by the Pecatonica Formation of the Platteville Group (Droste and Patton, 1986).
In gross aspect the Plattin is made up of the lithographic limestone that characteristically is associated with Black River rocks in many places in the eastern United States; dolostone is an abundant component of the Plattin only in northwestern Indiana and northeastern Illinois (Droste and Patton, 1986). The Plattin ranges in thickness from less than 100 ft (30 m) in northwestern Indiana to more than 400 ft (120 m) in southwestern Indiana (Droste and Patton, 1986).
The Plattin Formation is overlain with minor unconformity by the more coarsely bioclastic rock of the Trenton Limestone except for places in southern Indiana where rocks of the Kope Formation (Maquoketa Group) or of the Lexington Limestone lie above (Droste and Patton, 1986).
The Plattin Formation in Indiana is correlated with the Plattin Subgroup of Illinois, the Plattin Formation of western Kentucky and the upper part of the High Bridge Group elsewhere in Kentucky, and the upper parts of the Black River Group of Michigan and of the Black River Limestone of Ohio (Droste and Patton, 1986). Some named subdivisions of these units in adjacent states are recognized in some wells in Indiana (Droste and Patton, 1986). For example, marker bed I of Stith (1979) in the Black River Limestone of Ohio is recognized in many wells in Indiana (Droste and Patton, 1986). These same rocks in Indiana correspond essentially to the uppermost member (Briton Member) of the Mifflin Formation, Plattin Subgroup, of northern Illinois (Droste and Patton, 1986). The Brickeys Member of the Mifflin Formation of Illinois has a characteristic lithology that can be identified in wells in Indiana in the lower part of the Plattin Formation (Droste and Patton, 1986). K-bentonite deposits called the Mud Cave and Pencil Cave Bentonite Beds in Kentucky and several K-bentonite units noted by Stith (1979) in Ohio are recognized in some wells in Indiana (Droste and Patton, 1986).
Regional Indiana usage:
Illinois Basin (COSUNA 11)
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.)
Buckley, E. R., and Buehler, H. A., 1904, Quarrying industry of Missouri: Missouri Bureau of Geology and Mines, 2nd Series, v. 2, 371 p.
Droste, J. B., and Patton, J. B., 1986, Plattin 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. 113-114.
Gutschick, R. C., 1983, Geology of the Kentland Dome structurally complex anomaly, northwestern Indiana (Field Trip 15), 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. 105-138.
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.
Stith, D. A., 1979, Chemical composition, stratigraphy, and depositional environments of the Black River Group (Middle Ordovician), southwestern Ohio: Ohio Geological Survey Report of Investigations 113, 36 p.
Templeton, J. S., and Willman, H. B., 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
For additional information contact:
Nancy Hasenmueller (firstname.lastname@example.org)Date last revised: October 29, 2014