Mississippian System
Type and reference sections and use of name in Indiana: The Yankeetown Sandstone was named by Weller (1913, p. 120) for an exposure of about 20 feet (6 m) of sandstone and chert near Yankeetown School, Monroe County, Ill. (NE cor. SE¼ sec. 26, T. 4 S., R. 9 W.). In Indiana a shaly middle member of the Paoli Limestone, sometimes informally called the mid-Paoli shale break, has been recognized for many years in both surface and subsurface studies (Malott, 1952, p. 12; Pinsak, 1957, p. 17; Peay and Smith, 1958, p. 23; Gray, Jenkins, and Weidman, 1960, p. 49; Carr, Leininger, and Golde, 1978, p. 13). Swann (1963, p. 33), among others, correlated this unit with the Yankeetown Sandstone of Illinois. The name Yankeetown is adopted here for this member. A reference section for the Yankeetown Member is the principal reference section for the Paoli Limestone, an abandoned quarry just north of the former railroad tracks on the west side of Paoli, Ind. (SW¼SE¼SE¼ sec. 35, T. 2 N., R. 1 W.). There the member is about 3 feet (0.9 m) thick and consists of calcareous fossiliferous shale (Malott and Esarey, 1940, unnumbered plate). It underlies the Downeys Bluff Member of the Paoli Limestone and overlies the Shetlerville Member.
Description: The Yankeetown Member aver-ages about 4 feet (1.2 m) in thickness along the outcrop in south-central Indiana, but it is absent, probably depositionally, from the northern part of the outcrop and is as much as 9 feet (2.7 m) thick in the southern part (Kissling, 1967, p. 66). The Yankeetown is similar in composition to the Popcorn Member and commonly consists of alternating, subparallel, and discontinuous beds of greenish-gray calcareous shale and brownish-gray micritic, skeletal, or oolitic limestone, but in places it is gray argillaceous or sandy limestone or greenish-gray calcareous shale or siltstone. The shale and the limestone are fossiliferous, and crinoids, brachiopods, and gastropods are the most commonly found fossils. Beds equivalent to the Yankeetown Member are widely recognized in the subsurface as the middle part of the Renault Formation of subsurface usage.
Correlation: The Yankeetown Member of the Paoli Limestone contains the crinoid Talarocrinus, which is considered to indicate an early Chesterian age.
