Historical:Harrodsburg Limestone Member
Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The Harrodsburg Limestone Member of the Ullin Limestone (Hopkins and Siebenthal, 1897, p. 296-297; Stockdale, 1939, p. 72-73; Smith, 1965, p. 11; Lineback, 1966, p. 33) is named for Harrodsburg, Monroe County, Indiana.
The original type section of the Harrodsburg Limestone Member was destroyed by highway construction, but an exposure 1 mile north of Harrodsburg is used as a standard reference section (Shaver et al., 1970).
Extent and Thickness
The Harrodsburg Member is exposed along the Mississippi Valley in western and southwestern Illinois and in Hardin County in southeastern Illinois. It is over 800 feet thick in Hamilton County, but it thins northward and pinches out at the margin of the formation.
The Harrodsburg consists of light-colored bryozoan and crinoid debris. In Monroe County the Harrodsburg strata were included in the Kidd Member of the Salem by Baxter (1960a), but they were excluded from the Kidd by Lineback (1972).
BAXTER, J. W., 1960a, Salem Limestone in southwestern Illinois: Illinois State Geological Survey Circular 284, 32p.
HOPKINS, T. C., and C. E. SIEBENTHAL, 1897, Bedford oolitic limestone of Indiana: Indiana Department of Geology and Natural Resources, Annual Report 21, p. 291-427.
LINEBACK, J. A., 1966, Deep-water sediments adjacent to the Borden Siltstone (Mississippian) delta in southern Illinois: Illinois State Geological Survey Circular 401, 48 p.
LINEBACK, J. A., 1972, Lateral gradation of the Salem and St. Louis Limestones (Middle Mississippian) in Illinois: Illinois State Geological Survey Circular 474, 23 p.
SHAVER, R. H., et al., 1970, Compendium of rock-unit stratigraphy in Indiana: Indiana Geological Survey Bulletin 43, 229 p.
SMITH, N. M., 1965, Sanders Group and subjacent Muldraugh Formation (Mississippian) in Indiana: Indiana Geological Survey Report of Progress 29, 20 p.
STOCKDALE, P. B., 1939, Lower Mississippian rocks of the east-central interior: Geological Society of America Special Paper 22, 248 p.
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