How were the Jocassee Gorges formed?

The Blue Ridge Mountains in the Jocassee Gorges region. (Photograph by Dirk Frankenberg. More about the photograph)

Basically, erosion formed the Jocassee Gorges. For most of its length, the eastern continental divide, which separates land that drains to the Atlantic Ocean from land that drains to the Gulf of Mexico, runs northeast to southwest parallel to the Blue Ridge escarpment. In the Jocassee Gorges region, however, the divide breaks from this pattern, taking an abrupt westward turn. Water running off the divide here forms five major rivers — Horsepasture, Thompson, Whitewater, Chattooga, and Toxaway — all of which have waterfalls and deep gorges as they make their first step toward the sea. Through the erosive power of flowing water, the rivers have gradually cut the gorges into the escarpment.

The shape of the gorges is also responsible for making this region a rain forest. The escarpment faces south here, and the half-moon shape created by the back-cutting rivers forces warm, moisture-laden air from the Gulf of Mexico to rise. The rising air cools, and its moisture condenses to form clouds and rain.

You can see these clouds above the ridge in the previous photograph. They are typical of the thunderheads that usually dot the sky above Jocassee on summer afternoons. As the rivers erode away more and more land, more space for warm, moist air to get trapped is created. The more air that rises and cools, the more moisture is released as rain in the gorges. This heavy rainfall in turn powers the rivers that cut through the escarpment, making the gorges deeper and continuing the processes of erosion and water recycling.

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