In earlier columns, we reviewed current theories about the uplift of the Appalachian Mountains about 250 million years ago, as well as opinions about how high the Appalachians might have been when originally uplifted; took a closer look at the Southern Blue Ridge Province, the geographic area of the Southern Appalachians in which we reside; and surveyed the distinctive forest zones of that region. Other significant factors that influence the geophysical makeup of the province would be its high annual rainfall; its drainage patterns as determined by the Eastern Continental Divide; and the fact that the region is comprised of so much terrain rising above 4,000 feet that it serves as a refuge for numerous plants and animals that wouldn’t otherwise flourish this far south.
The Southern Blue Ridge Province — which extends southward from the water gap at Roanoke, Virginia, to Mt. Oglethorpe in north Georgia, including the mountainous portions of Tennessee, North Carolina and South Carolina — is situated where prevailing winds direct warm, water-saturated air masses from the Gulf of Mexico. These air masses are cooled while rising to pass over the southern end of the province, causing condensation. The heaviest amounts of rainfall in the entire Appalachian system have been recorded from about Hayesville, North Carolina, eastward in the Nantahala Mountains and along the borders of Georgia, North Carolina, and South Carolina. An annual rainfall of 90 inches is not uncommon. Not every year or always in the same place — but with regularity — as much as 120 to 145 inches of annual rainfall has been recorded within this specific terrain. Appropriately, some observers now refer to the area — which includes Highlands, Cashiers, and Brevard, North Carolina — as a “temperate” or “Appalachian” rain forest.
An important factor, often overlooked, in the topography of the Southern Blue Ridge Province is the Eastern Continental Divide. It is the almost imaginary pencil-thin boundary that establishes the divide between waters that flow eastward via various river systems into the Atlantic and those that flow westward via the Tennessee, Ohio, and Mississippi river systems to the Gulf of Mexico.
Just south of the Roanoke River water gap, the divide enters the province at the tiny village of Copper Hill, Virginia. It then winds southward along the Blue Ridge front over the crests of familiar landmarks like Bluff and Grandfather mountains. In the area of Sassafras Mountain, the divide becomes the boundary between North Carolina and South Carolina. From there, it veers back into North Carolina and traverses Cold Mountain south of Waynesville and numerous peaks in the Highlands, North Carolina, area such as Whiteside, Satulah, and Little and Big Scaly mountains. It then crosses back into Georgia at Rabun Bald and Black Rock State Park, just south of Dillard, Georgia, before entering North Carolina yet again. After circling the Standing Indian basin in the headwaters of the Nantahala River, it passes back into Georgia and follows the Appalachian Trail to Young Lick Knob at a point about 18 miles southwest of Clayton, Georgia.
At 3,800 feet in elevation, Young Lick Knob is one of the more inconspicuous peaks along the section of the Appalachian Trail between Dicks Gap (U.S. 76) and Unicoi Gap (Ga. 75). But geographically it is one of the most significant points in the eastern United States. Here the Eastern Continental Divide reaches its southernmost terminus at a point geographers recognize as a “terminal divide.” On the northeastern flank of Young Lick Knob, waters flow into the Atlantic via the Chattooga and Savannah rivers. On its southeastern flank, waters run directly into the Gulf of Mexico via the Chattahoochee and Apalachicola rivers. On its western flank, waters follow a long circuitous route to the Gulf via the Hiwassee, Tennessee, Ohio, and Mississippi river systems.
There are many places along the Eastern Continental Divide where you can stand at a springhead feeding its waters into the Atlantic and throw a rock over the ridge to the west, where it would land near a springhead feeding its waters into the Mississippi and Gulf of Mexico. It’s probable, in my opinion, that the unique cliff-face/gorge systems found in the Highlands-Cashiers-Panthertown region are the result of significant and dramatic erosion along that section of the Eastern Continental Divide at the end of the last Ice Age 15,000 or so years ago.
The Appalachian system as a whole reaches its greatest elevation, largest mass, and most rugged topography in the Southern Blue Ridge, where, according to Marcus B. Simpson Jr., in Birds of the Blue Ridge Mountains (1992), “there are 25 mountains over 5,000 feet and 49 that rise above 6,000 feet in elevation.” This topography profoundly influences the region’s average temperatures — and thereby its plant and animal life, which exhibit strong northern affinities. For each 1,000 feet gained in elevation the mean temperature decreases about four degrees F, equivalent to a change of from 200 to 250 miles in latitude. This means that if you travel from the lowest elevations in the Southern Blue Ridge at about 1,500 feet to the higher elevations above 6,000 feet, it’s the equivalent of traveling more than 1,200 miles northward in regard to the habitats you will encounter.
(Editor’s Note: This column is part of George Ellison’s new book, Blue Ridge Nature Journal: Reflections on the Appalachian Mountains in Essays and Art, which will be published next month by The Natural History Press, a subsidiary of The History Press in Charleston, S.C. In addition to 30 chapters devoted to the region’s topography, plants, and animals, the large-format volume will feature 40 full-color paintings and 30 decorative chapter illustrations by artist Elizabeth Ellison.)