Desmoinesian and Missourian Series
Type area and use of name: The name McLeansboro Formation was first used by De Wolf (1910, p. 181) for all rocks of Pennsylvanian age above the Herrin (No. 6) Coal of Illinois exposed near McLeansboro, Hamilton County, Ill. The name McLeansboro was later (Kosanke and others, 1960, p. 36) used in Illinois with the rank of group for all Pennsylvanian rocks above the Danville (No. 7) Coal. Wier and Gray (1961) extended the use of this name into Indiana.
Description: The McLeansboro Group as recognized in Indiana extends from the top of the Danville Coal Member of the Dugger Formation to the top of the Pennsylvanian sequence. This group consists in ascending order of the Shelburn, Patoka, Bond, and Mattoon Formations, but in Indiana it does not include the entire section represented in the type area because of eastward erosional truncation. In Indiana the outcrop belt of the McLeansboro Group extends from western Warrick County northward to southwestern Vermillion County. The maximum thickness of 770 feet (235 m) is reached in the Mumford Hills in northern Posey County. Shale and sandstone make up more than 90 percent of this sequence, but minor amounts of siltstone, limestone, clay, and coal are present (Wier, 1961, 1965).