Chemical composition, stratigraphy, and depositional environments of the Black River Group (Middle Ordovician), southwestern Ohio.

The chemical composition and stratigraphy of the Black River Group in southwestern Ohio were studied. Chemical analyses were done on two cores of the Black River from Adams and Brown Counties, Ohio. These studies show that substantial reserves of high-carbonate rock are present in the Black River at depths of less than 800 ft, in proximity to Cincinnati and the Ohio River. Stratigraphic studies show that the Black River Group has eight marker beds in its middle and upper portions and three distinct lithologic units in its lower portion; these marker beds and units are present throughout southwestern Ohio. The Black River Group correlates well with the High Bridge Group of Kentucky. Depositional environments of the Black River are similar to those of the High Bridge and to present-day tidal flats in the Bahamas.-Author