Type locality: This unit was first named the Menard Formation by Stuart Weller (1913, p. 128) for exposures in a quarry at the Menard State Hospital (NE¼ sec. 23, T. 7 S., R. 7 W.) near Menard, Randolph County, Illinois (Gray, 1970; Atherton, Collinson, and Lineback, 1975, p. 160; Gray and Keller, 1986, p. 90-91). The formation is also exposed in the Mississippi River bluffs at Menard (Atherton, Collinson, and Lineback, 1975, p. 160).
History of usage:
History of use of neme in Illinois: In 1920, Weller (p. 202, 205-206) described the unit as 80 to 120 ft (24 to 37 m) of dark-gray thin-bedded fine-grained limestone and changed the name to Menard Limestone (Gray, 1970; Gray and Keller, 1986). Swann (1963, p. 38-39, 74) redescribed the Menard as being 30 to 150 ft (9 to 46 m) thick and consisting of three named limestone members and three unnamed shale members (Gray, 1970; Gray and Keller, 1986). The Menard Limestone is a unit in the standard Chesterian section (Atherton and Collinson, and Lineback, 1975, p. 160).
The Menard was redesignated by Gray and Keller (1986) with the lithologic term limestone in recognition of its most consistent and widespread usage. Three subunits, informally designated "upper," "massive," and "little" Menard, are recognized (Gray and Keller, 1986). Where the upper Menard is recognizable, it is a limestone 10 ft (3 m) thick (Gray and Keller, 1986). The massive or main Menard consists of 30 to 60 ft (9 to 18 m) of limestone. Beneath this are 15 ft (5 m) of dark-gray shale that is not named and the little or lower Menard, which is limestone and is 8 to 10 ft (2 to 8 m) thick (Gray and Keller, 1986). The principal type of carbonate rock in all three limestone members is light-gray micritic limestone; some dark-gray fossiliferous limestone is present in the upper part of the main Menard (Gray and Keller, 1986).
The Menard Limestone overlies the Waltersburg Sandstone and is overlain in most places by the Palestine Sandstone (Gray and Keller, 1986). Both contacts are probably conformable. Where uppermost Chesterian formations have been removed by pre-Pennsylvanian erosion, the Mansfield Formation (Morrowan) disconformably overlies the Menard (Gray and Keller, 1986).
The Menard Limestone correlates with rocks that are near the boundary of North American foraminiferal Zones 17 and 18 of Mamet and Skipp (1971) and within the Namurian Series, near the boundary of Zones El and E2, of European usage (Gray and Keller, 1986). The Menard Limestone and all its members have been assigned to the Kladognathus-Cavusgnathus navicuIus Assemblage Zone of the standard North American conodont sequence (Collinson, Rexroad, and Thompson, 1971).
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.)
Atherton, Elwood, Collinson, Charles, and Lineback, J. A., 1975, Mississippian System, in Willman, H. B., Atherton, Elwood, Buschbach, T. C., Collinson, Charles, Frye, J. C., Hopkins, M. E., Lineback, J. A., and Simon, J. A., Handbook of Illinois stratigraphy: Illinois State Geological Survey Bulletin 95, p. 123-163.
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.
Gray, H. H., 1970, Menard 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. 108-109.
Gray, H. H., and Keller, S. J., 1986, Menard 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. 90-91.
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.
Malott, C. A., 1925, The upper Chester of Indiana: Indiana Academy of Science Proceedings, v. 34, p. 103-132.
Malott, C. A., 1931, Geologic structure in the Indian and Trinity Springs locality, Martin County, Indiana: Indiana Academy of Science Proceedings, v. 40, p. 217-231.
Malott, C. A., and Esarey, R. E., 1940, Outcrop of the Chester Series of southern Indiana: Indiana-Kentucky Geological Society, May 18, 1940, 9 p. [mimeo.].
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.
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.
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.
Swann, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.
Weller, Stuart, 1913, Stratigraphy of the Chester Group in southwestern Illinois: Illinois State Academy of Science Transactions, v. 6, p. 118-129.
Weller, Stuart, 1920, The geology of Hardin County and the adjoining part of Pope County: Illinois State Geological Survey Bulletin 41, 416 p.
For additional information contact:
Nancy Hasenmueller (email@example.com)Date last revised: April 5, 2017