Pennsylvanian System

Type section: The Pirtle Coal Member of the Shelburn Formation was named by Wier (1961, 1965) for exposures of Ashley's (1899) Coal VIIa near the Pirtle Cemetery in secs. 15 and 27, T. 8 N., R. 8 W., Sullivan County, Ind. The type section is in the SE¼SE¼SW¼ sec. 15, T. 7 N., R. 8 W.

Description: The Pirtle Coal Member is thickest in Sullivan County and in northern Knox County, where the coal is bright banded and shaly in places. It averages 1 to 1.5 feet (0.3 to 0.5 m) in thickness and lies more than 60 feet (18 m) above the Danville Coal Member of the Dugger Formation. The Pirtle coal is very thin in Vigo and Vermillion Counties or is absent. It is seen in few places in outcrop in Gibson and Posey Counties but may not be recognized on many geophysical logs because of its thinness.