Coal that crops out 40 to 70 ft above the Reynoldsburg is "herein named" the Tunnel Hill Coal Bed of the Abbott Formation. [Elsewhere in the report authors state all units within the Abbott, except the Reynoldsburg Coal Bed and the Murray Bluff Sandstone Member are named informally.] Though no type section is designated, unit is described at a surface mine in NW1/4NW1/4, sec. 6, T12S, R4E, once operated by the Holly Mining Co. Coal here is 12 to 14 in. thick where exposed. Measures 28 in. in test hole C-5. Tunnel Hill is classified as latest Morrowan (early Westphalian B stage) and is palynologically equivalent to the Bell (1B) coal bed of western KY. Conodonts from the overlying limestone are indicative of a late Morrowan or early Atokan age.

Source: GNU records (USGS DDS-6; Reston GNULEX).