Type locality and description in Illinois: This unit was originally named the Clore Formation by Stuart Weller (1913, p. 129) for exposures near Clore School, Randolph County, Ill. Later the unit was restricted, designated the Clore Limestone (Weller, 1920b, p. 212-213), and described as a crystalline to shaly limestone and calcareous shale as much as 40 feet (12 m) thick. Swann (1963, p. 40-41, 64) redefined the Clore as a formation and described it as 50 to 110 feet (15 to 34 m) thick and having "limy or shaly" upper and lower parts and a "sandy or shaly" middle part. Willman and others (1975, p. 161) similarly described the Clore Formation as "dominantly shaly throughout most of its extent." Consequently, the Clore is the most non distinctive of ail the formations in the standard Chesterian section, and it is the most uncertainly applied.
History of name and description in Indiana: In the earliest definitive study of outcropping upper Chesterian rocks in Indiana (Malott, 1925), this "shale interval" was not named, at an undocumented correlation of these rocks with the Clore of Illinois was later asserted (Malott, 1931, p. 222). Malott and Esarey (1940) apparently were the first to apply the name Clore Limestone in Indiana, and Malott, Esarey, and Bieberman (1948, p. 25) more fully described the Clore as 20 to 45 feet (6 to 14 m) of "shale with thin yellow impure limestones." The boundaries of this unit were, however, never made clear (see the discussion of boundary problems under "Tar Springs Formation"), and in a study of outcropping upper Chesterian rocks, Gray (1978) did not use the name, preferring instead to leave this unit undifferentiated within the Tobinsport Formation.
The term Clore is now restricted in Indiana to subsurface use, where the formation is uncertainly known from Dubois and Knox Counties southwestward. Detailed descriptions and reliable thickness data are not available. The Clore overlies the Palestine Sandstone and is overlain by the Degonia Sandstone or by the Mansfield Formation (Morrowan) where uppermost Chesterian formations have been removed by pre-Pennsylvanian erosion.
For Indiana usage the Clore Limestone is here assigned to the Buffalo Wallow Group.