Faults and Earthquakes

Geologic Window

The collision of continental plates is also expressed in the rocks by folds (bends) and faults (breaks). Damaging earthquakes happen because of slippage along a fault. Although earthquakes are now rare in the Southern Appalachians, during the time of continental collision, earthquakes were a common occurrence.

One place where the effects of the faulting can be seen is in Cades Cove in the Great Smoky Mountains National Park. In a normal sequence, younger rocks are deposited on top of older ones. However, in Cades Cove, the limestone that makes up the floor of the cove is younger than the rocks in the surrounding mountains. The older rocks of the surrounding mountains moved over the limestone on a low-angle fault. Erosion made an opening to expose younger rocks below the fault, in a feature called a window. The rocks that we see through the Cades Cove window formed in the inland sea that once covered this area.

Many faults have been identified throughout the Southern Appalachian Mountains and the Ridge and Valley province. Huge masses of rock moved along these faults for distances of 60 miles or more. A major fault area can be seen at Linville Falls, north of Asheville, N.C. The rocks that make up the mountains above the falls are older than the resistant ledges that form the falls. Ground-up rocks of the fault zone are between the older rocks above and the younger rocks below the falls in Linville Gorge.