The Hartselle Sandstone

The cliffs and moss-covered boulders along Bear Creek in Tishomingo State Park are Hartselle Sandstone, a tightly cemented sandstone with thin shale beds laid down in the Late Mississippian, more than 320 million years ago. The outcrops sit at the southwestern end of the plateau country that runs down from the Appalachians, and they have more in common with the rocks of the southern Appalachians in Alabama, Tennessee and Georgia than with anything else in Mississippi. Its rock walls reach 15 to 20 meters high in places, and the whole Hartselle outcrop area in the state covers less than 30 square kilometers.

The Hartselle is one of the Paleozoic formations that surface only in the northeastern corner of Mississippi. It rests on the shales of the Pride Mountain Formation and crops out in southern Tishomingo County, and the Mississippi Office of Geology describes it as having limited potential as an aquifer. Paleozoic rocks in this area dip to the south-southwest at 25 to 50 feet per mile, passing beneath the Cretaceous sand, gravel and clay of the Gulf Coastal Plain.

Bear Creek Canyon, cut through these outcrops, is the main feature of Tishomingo State Park, which the Natchez Trace Parkway crosses near milepost 304.5. The same rock is the only habitat in Mississippi for the green salamander, an Appalachian species at the edge of its range.