Name Centerville formation is here provisionally proposed for the supposed OH equivalent of the Edgewood formation of IL and MO. Until recently the Brassfield limestone was regarded as the oldest Silurian formation in the area traversed by the Cincinnati anticline. The Belfast is merely a local phase at the base of the Brassfield. In Indiana and Ohio the base of the Brassfield is underlain by a clay shale previously referred to the Elkhorn member of the Richmond. Several years ago, however, a Silurian fauna was discovered locally in the uppermost part of this clay. At a quarry east of Centerville, Montgomery Co., OH, distinctly Silurian fauna was collected [listed]. Such an association of Silurian and Ordovician fossils is known also in the Edgewood formation of southwestern IL and adjacent parts of MO. Hence the OH faunules here mentioned are correlated provisionally with the Edgewood, although no species known to be diagnostic of the Edgewood have been found. Presence of PLATYMERELLA MANNIENSIS at base of the Brassfield at Lawshe, Adams Co., OH, appears to confirm this correlation. Age is earliest Silurian.

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

Chart 3. Shown on correlation chart as Centerville clay; stratigraphically below Brassfield limestone. Age is Early Silurian (Albion).

Source: US geologic names lexicon (USGS Bull. 1200, p. 697).