Type locality: The Davis Formation was named by Buehler (1907, p. 231) and Buckley (1908, p. 33-44) for exposures along Davis Creek, St. Francois County, Missouri, where it underlies what were then called the Derby and Doe Run Dolomites (Droste and Patton, 1986).
History of usage:
Extended: The Davis was traced eastward from Missouri into central Illinois by Workman and Bell (1948) and thence into Indiana by Becker, Hreha, and Dawson (1978) (Droste and Patton, 1986).
In Indiana the Davis Formation consists of the gradational rocks between the Potosi Dolomite and the sequence made up of the Galesville and Ironton Sandstones and the Franconia Formation (Droste and Patton, 1986). These rocks are composed of siltstone, shale, limestone, and dolostone (Becker, Hreha, and Dawson, 1978). The Davis attains a maximum thickness of more than 200 ft (61 m) in western central Indiana (Droste and Patton, 1986).
The rocks of the Davis Formation are conformable with the subjacent Eau Claire Formation and superjacent Potosi Dolomite (Droste and Patton, 1986).
The whole of the Davis Formation of Indiana correlates with the Franconia Formation, including the Davis Member, of Illinois and with the Davis Formation of eastern Missouri; with the Galesville and Franconia rocks of the Lower Peninsula of Michigan; with the Elvins Formation of western Kentucky; and with the Conasauga into lower Knox sequence as recognized by Janssens (1973) (Droste and Patton, 1986). Trilobites of the Elvinia Zone recovered from a core taken from a deep well in Vermillion County, Indiana, helped to establish the Franconian age of part of the Davis Formation (Palmer, 1982).
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 features in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Buckley, E. R., 1908, Geology of the disseminated lead deposits of St. Francois and Washington Counties: Missouri Bureau of Geology and Mines, 2nd Series, v. 9, pt. 1, p. 33-44.
Buehler, H. A., 1907, The lime and cement resources of Missouri: Missouri Bureau of Geology and Mines, 2nd Series, v. 6, p. 217-232.
Droste, J. B., and Patton, J. B., 1986, Davis 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. 34-35.
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.
Janssens, Adriaan, 1973, Stratigraphy of the Cambrian and Lower Ordovician rocks in Ohio: Ohio Geological Survey Bulletin 64, 197 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.
Workman, L. E., and Bell, A. H., 1948, Deep drilling and deeper oil possibilities in Illinois: American Association of Petroleum Geologists Bulletin, v. 32, p. 2,041-2,062; Illinois Geological Survey Report of Investigation 139, 22 p., 1949.
For additional information, contact:
Nancy Hasenmueller (email@example.com)Date last revised: August 27, 2014