Pennsylvanian System
Type locality and use of name: The name Upper Mariah Hill Coal was originally used for a coalbed mined by the Mariah Hill Super Block Coal Co. in secs. 19 and 20, T. 4 S., R. 4 W., one-quarter mile (0.4 km) southeast of Mariah Hill, Spencer County, Ind. (Franklin and Wanless, 1944, p. 87, 89). No specific type section was cited, however. This coal was later mapped as the Mariah Hill Coal by Hutchison (1959, 1964), who still later (1967) assigned it member rank in the Mansfield Formation.
Description: The Mariah Hill Coal Member consists of moderately bright coal that is slightly pyritiferous and semiblocky. It ranges from 1.5 to 6.0 feet (0.5 to 1.8 m) in thickness. The roof of the coal is a dark-gray silty carbonaceous shale that in places is calcareous and fossiliferous and that encloses lenticular limestone that is shaly to massive, argillaceous, fossiliferous, and cherty in places. The floor of the coal is gray carbonaceous underclay or clay shale.
The Mariah Hill can be traced along its outcrop throughout Spencer County (Hutchison, 1959) and into Dubois County (Hutchison, 1964), where it was called the Lower Huntingburg Coal by Franklin and Wanless (1944, p. 87). Toward the north edge of Dubois County, the coal becomes spotty in its distribution and is difficult to identify.
Correlation: The Mariah Hill has been traced by mapping along its outcrop in Spencer County (Hutchison, 1959), Dubois County (Hutchison, 1964), Martin County (Hutchison, 1967), Daviess County (Hutchison, 1971a), and Perry County (Hutchison, 1971b). Although the Mariah Hill has been tentatively correlated with the Upper Block Coal Member to the north (Franklin and Wanless, 1944) and therefore with part of the Brazil Formation, this coal actually lies within the Mansfield Formation, as shown by Hutchison (1959), some 20 to 40 feet (6 to 12 m) below the Ferdinand Bed. The Mariah Hill has also been correlated with the Dunbar Coal Bed of western Kentucky (Peppers and Popp, 1979) and on the basis of spore assemblages with the lowest coal exposed at Roaring Creek in northern Parke County, Ind. (Peppers, 1982).
