Type locality and use of name in Ohio: Originally described as the Sunbury Black Slate (Hicks, 1878, p. 216, 220), the Sunbury Shale was named for Sunbury, Delaware County, Ohio, where 10 to 15 feet (3.0 to 4.6 m) of black carbonaceous shale overlies the Berea Sandstone and underlies what was called the Raccoon Shales (now part of the Cuyahoga Formation).
Description: In the Michigan Basin part of northernmost Indiana, the Sunbury is a carbonaceous brownish-black shale and lies stratigraphically between the greenish-gray Ellsworth Shale (below) and the Coldwater Shale. The unit was recognized by Hasenmueller and Bassett (1979) in Steuben, Lagrange, Noble, and DeKalb Counties. The Sunbury Shale is slightly more than 10 feet (3 m) thick in Steuben County in northeasternmost Indiana and thins southward and westward (Lineback, 1968, 1970 Hasenmueller and Bassett, 1981). The Sunbury is absent west of Lagrange County.
Correlation: The Sunbury is laterally equivalent to the uppermost part of the Ellsworth Shale of Michigan and northern Indiana and probably correlates with the Henryville Bed of the Ellsworth and Clegg Creek Members of the New Albany Shale in the Illinois Basin (Lineback, 1968, 1970; Hasenmueller and Bassett, 1981).