Harrodsburg Limestone
The Harrodsburg Limestone is a geologic formation, a member of the Sanders Group of Indiana Limestone, of Mississippian age. It was named for Harrodsburg in southern Monroe [County, Indiana] by T. C. Hopkins and C. E. Siebenthal. It is made up primarily of calcarenite and calcirudite. It also may include some beds of dolomite and shale.
Harrodsburg Limestone is found throughout the part of the Illinois Basin running through southern Indiana.