Ordovician Outcrop Belt
Today, the Late Ordovician rocks crop out in a very specific bullseye pattern around Cincinnati. The oldest rocks are nearest the center of this bullseye and the younger rocks are exposed toward the edges. The reason for this pattern is that the rocks in this region have been warped into a dome or arch feature by tectonic events related to the later tectonic development of the Appalachian Mountains. At the time the Cincinnatian strata were deposited, the region was a shallow ramp of less than 1 degree slope, with the deepest water in the southeast of the outcrop belt and the shallowest water in the northwest of the outcrop belt.