One of the largest naturally exposed fossil beds in the world opened about 10 years ago at Indiana's Falls of the Ohio State Park along the Ohio River in Clarksville (about 100 miles southwest of Cincinnati, just across the river north of Louisville, Kentucky).
The 200-acre fossil beds extend up the river's rocky banks before giving way to forested floodplain. Naturalists lead hikers across the beds from June through October, when the river is low and you can see the imprints of creatures from more than 380 million years ago. Visitors can examine up close the outcroppings and colonies of coral and sponges. Fossils range from the size of a toddler's tiny thumbprint to big enough for an adult to stretch out in full length.
The park's "falls" today actually are a one-mile stretch of white water. In late summer, when the water level drops, visitors can hike to more fossils on Goose Island in the river. You can't reach these outer beds at any other time. The park also hosts a variety of programs and special events; check the website for details.
A bluff-top Interpretive Center shows a movie that recounts the area's history. The complex also includes a museum, learning center, exhibit gallery and aquariums.
Open daily 7 a.m. to 11 p.m. (Interpretive Center open 9 a.m. to 5 p.m. Mondays-Saturdays and 1 to 5 p.m. Sundays). For more details, contact the park (812/280-9970).