Oconaluftee (Great Smoky Mountains) - Geology

Geology

Near Newfound Gap, several small creeks converge to form Beech Flats Prong. This stream flows south along the southern base of Mount Kephart, dropping 2,000 feet (600 m) over 10 miles (16 km) before merging with Kephart Prong, Kanati Fork, and Smith Branch to form the Oconaluftee River. The Oconaluftee continues southward, cutting a valley between the Richland Mountain massif to the east and the Thomas Ridge massif to west. The confluence of the Oconaluftee River and Bradley Fork at Smokemont strengthens the river considerably, with the valley broadening as a result. Near the park boundary, a large and relatively flat bottomland has been created by the river's junction with Raven Fork, which flows down from the northeast. Past Cherokee, the river turns west en route to its mouth along the Tuckasegee River, near Bryson City.

The rock formation underlying the area around the Oconaluftee-Raven Fork junction contains some of the oldest exposed rocks in the Eastern United States. This formation, which is composed primarily of an Early Precambrian basement rock known as granite gneiss, was formed over a billion years ago from the gradual accumulation of marine sediment and igneous rocks.

The upper elevations of the Oconaluftee Valley are underlain by a Late Precambrian metamorphic rock of the Ocoee Supergroup, which is the dominant rock class in the Great Smokies. These rocks were formed from ocean sediments nearly 400 million years ago, and were thrust upward during the Appalachian orogeny, when the North American and African plates collided.

The Greenbrier Fault, which crosses the Oconaluftee River between Tow String Creek and Mingus Creek, divides the basement formation from the Late Precambrian formation. Exposures of both rock formations can be seen along U.S. Route 441 between Newfound Gap and Cherokee.