Pennsylvanian System

Type locality and use of name: The term Minshall Coal was first applied formally by Ashley (1909, p. 57) to the coalbed below the limestone at the now-abandoned mining town of Minshall, Parke County. In now-obsolete usage the name Minshall was also applied to the closely overlying limestone as well as other limestones. The Minshall was assigned member rank by Wayne, Johnson, and Keller (1966) .

Description: Minshall coal is moderately bright to very dull, pyritiferous, semiblocky to blocky, and extremely irregular in extent and thickness. In the northern part of the coalfield, it ranges from less than 1 foot to more 6 feet (0.3 to 1.8 m) in thickness and averages about 4 feet (1.2 m) where mined. The roof is gray shale that is clayey to silty and fossiliferous in places. The roof in many areas contains the Perth Limestone Member, a lenticular gray fossiliferous limestone as much as 18 feet (5.5 m) thick. In some places the limestone lies directly on the coal. The floor is gray carbonaceous plastic underclay. Stratigraphically, the Minshall Coal Member lies 15 to 20 feet (4.6 to 6.1 m) below the top of the Brazil Formation and about 22 feet (6.7 m) above the Upper Block Coal Member.

Correlation: The Minshall has been recognized as far north as Warren County (Hutchison, 1961) and as far south as Switz City in Greene County (Kottlowski, 1960; Hutchison and Hasenmueller, in preparation). Spore assemblages of the Buffaloville and Minshall Coal Members are similar, and Hutchison (1959) assigned the Buffaloville Coal Member to the Brazil Formation and considered that it is continuous with the Minshall.

Although the Minshall has been correlated as low as the coal below the Lead Creek Limestone Member in Hancock County, Ky., it more likely correlates with a higher Kentucky coal, at least as high as that once mined southwest of Lewisport in Daviess County. According to Peppers (1970, p. 29) and Hopkins and Simon (1975, p. 184), the Murphysboro Coal Member of Illinois is probably equivalent to the Minshall, but the same Illinois coal has also been correlated with an unnamed coal in the Staunton Formation of Indiana (Peppers, 1982, p. 27-31). The Minshall coal has also been correlated with the Litchfield and Assumption Coal Members of southern Illinois and the Rock Island (No 1) Coal Member of northern Illinois (Peppers and Popp, 1979, p. 70).