Middle Devonian limestones of central Ohio consist of two formations: below, the Columbus limestone, equivalent of the Onondaga limestone of New York State, 80 to 105 feet thick; above, the Delaware limestone, 35 to 40 feet thick. A bone bed, distinctly visible in the quarries west of Columbus, but absent or recognized with difficulty outside of Franklin County, has been considered the boundary between the Columbus and the Delaware limestones. A second bone bed occurs near the top of the Delaware limestone in the abandoned quarries northwest of the Chesapeake and Ohio Railway station at Delaware, but has not been seen elsewhere. These two bone beds will be referred to as the lower and the upper bone beds. The present paper aims to show that these bone beds, together with certain crinoidal layers in the Delaware limestone, are shallow-water, mechanical sediments.
Four feet below . . .