Ohio may be missing Mesozoic rocks (which contain dinosaur fossils), but its rock record is rich nonetheless. Most surface rocks in Ohio are Paleozoic in age. Many of these rocks were deposited from ancient seas or coastal plains. As a result of these depositional environments, the state's marine fossil record is particularly rich. Ohio's surface rock record also includes Quaternary Period (“ice age”) rocks, which are much younger than Paleozoic and Mesozoic rocks. These rocks contain fossils such as mammoths and mastodons.
