Type section: The Underwood type section is in the SE¼ sec. 21, T. 2 N., R.7 E., 2 miles (3.2 km) southeast of Underwood in Clark County, Indiana (Hasenmueller, 1986) (Otisco quadrangle).
History of usage:
The Underwood was originally designated as a formation by Campbell (1946) but was later assigned as a bed to the upper part of the Clegg Creek Member of the New Albany Shale by Lineback (1968, 1970) (Hasenmueller, 1986).
The Underwood consists of 0.4 foot (0.1 m) of greenish-gray fossiliferous shale at the type section (Lineback, 1970; Hasenmueller, 1986). Distribution: This unit, overlain by the Henryville Bed and underlain by the Falling Run Bed, is of extremely limited extent and cannot be recognized away from the immediate area of the type section (Hasenmueller, 1986).
Regional Indiana usage:
Cincinnati Arch (COSUNA 13)
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.
Burger, A. M., 1970, Underwood Bed, 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. 180.
Campbell, Guy, 1946, New Albany Shale: Geological Society of America Bulletin, v. 57, p. 829–908.
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.
Hasenmueller, N. R., 1986, Underwood Bed, 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. 158–159.
Lineback, J. A., 1968, Subdivisions and depositional environments of New Albany Shale (Devonian-Mississippian) in Indiana: American Association of Petroleum Geologists Bulletin, v. 52, p. 1,291–1,303.
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.
For additional information, contact:
Nancy Hasenmueller (email@example.com)Date last revised: January 29, 2019