Type locality: The Degonia Sandstone was named by Stuart Weller (1920, p. 403-405; 1920, p. 216) for exposures of massive cliff-forming cross-bedded sandstone and thin-bedded ripple-marked sandstone in Degonia Township, Jackson County, Illinois (Gray, 1970, 1986).
History of usage:
Revised name: In an early study of outcropping upper Chesterian rocks in Indiana, Malott (1925) named a thin sandstone unit the Mount Pleasant Sandstone (Gray, 1986). Approximate equivalence of this sandstone to the Degonia was later recognized by Malott (1931, p. 222) "after he had made a study of the Chester formations in southern Illinois" (Malott, 1952, p. 6; Gray, 1970, 1986). No other documentation was ever given, but the name “Degonia” was used in a few later papers (for example, Malott and Esarey, 1940; Malott, Esarey, and Bieberman, 1948; Gray, 1970, 1986). The lithologic character, thickness, and nature of the boundaries of this unit were never made clear (Gray, 1986).
The dominant lithology of the Degonia Formation is medium- to dark-gray shale; light to dark shades of red and green shales are found in the upper part of the formation in many areas in Indiana (Droste and Keller, 1995). Thin beds of light-gray and light-brown, very fine grained sandstone are present in numerous places. The maximum thickness of sandstone is 60 ft (18 m) in a restricted area in western Posey County (Droste and Keller, 1995). The Degonia Formation ranges from less than 10 ft (3 m) near the area of outcrop to a maximum thickness of 68 ft (21 m) in western Posey County (Droste and Keller, 1995).
The Degonia Formation overlies the Clore Limestone and is overlain by the Kinkaid Limestone, but over much of the area of its occurrence, pre-Pennsylvanian erosion has removed the Kinkaid, so that the Degonia is overlain by the Pennsylvanian Mansfield Formation (Morrowan) (Gray, 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.)
COSUNA areas and numbers that approximate regional bedrock outcrop patterns and major structural featuers in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Gray, H. H., 1970, Degonia Sandstone, 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. 42-43.
Gray, H. H., 1986, Degonia Sandstone, 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. 35.
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., 1952, Stratigraphy of the Ste. Genevieve and Chester formations of southern Indiana: Ann Arbor, Michigan, Edwards Letter Shop, 105 p.
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.].
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.
Weller, Stuart, 1920, The Chester Series in Illinois: Journal of Geology, v. 28, p. 281-303 and 395-416.
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 (firstname.lastname@example.org)Date last revised: November 22, 2016