Paleontology and geology
The Silurian sea was largely mud-free across Ohio and the climate was tropical, much like that of the present-day Bahamas. Large coral/sponge reefs separated the shallower waters across much of Ohio from the deeper waters of the Michigan Basin to the north and the Appalachian Basin in the east. Corals, brachiopods, and stalked echinoderms are common fossils from these ancient reefs. This map shows a prominence of Silurian rocks in the western portion of the state.