Southern mountains a peninsula of northern climes
Geographically speaking, where are the Great Smoky Mountains in regard to the other mountain ranges in the southern Appalachians. Where is the line between the southern and the northern Appalachians? In other words, where are we?
One of the handouts I use during natural history workshops is headed “Southern Blue Ridge Province: Geographic Location and Influences.” It is the best “concise” approximation of the situation that I have been able to devise, as yet.
The Appalachians — created between 300 and 250 million years ago as a result of periods of mountain building brought about when the North American continental plate collided with the plates forming the European and African continents — extend some 2,000 miles from Canada’s Gaspe Peninsula to north Georgia and Alabama. They have been described as “The most elegant mountain range in the world.”
The Southern Appalachians can be defined as the ranges south of the point in northeastern Pennsylvania to which glacial ice sheets extended at the height of the Wisconsin epoch 18,000 years ago. (Where not impeded by mountainous terrain the ice extended much farther south in the Ohio River valley to the outskirts of Cincinnatti.)
The unglaciated Southern Appalachians consist of four geographic provinces: Piedmont, Blue Ridge, Ridge and Valley, and Plateau. The Piedmont is the ancient eroded eastern rim of the Appalachians. Pilot Mountain, Parris Mountain, Stone Mountain, and the other small mountains in the Piedmont are remnants of what once was much higher terrain.
The Ridge and Valley extends from northwest Georgia through the valley in east Tennessee, where Knoxville is situated, into the Shenandoah Valley of Virginia and on into Pennsylvania. The Plateau extends from north Georgia through Tennessee and Kentucky northward. (The portion of the Plateau south of the Cumberland Gap where Tennessee, Kentucky, and Virginia corner is usually called the Cumberland Plateau.)
The Blue Ridge Province is by far the most significant in regard to mountainous terrain. It extends from just south of Harrisburg, Penn., to the hills of north Georgia just north of Atlanta, encompassing mountainous portions of southwestern Virginia, Western North Carolina, East Tennessee, northwest South Carolina, and north Georgia.
The Blue Ridge can be divided into northern and southern provinces, with the Southern Blue Ridge Province (SBRP) consisting of the terrain south of Mt. Rogers in southwestern Virginia to Mt. Oglethorpe in north Georgia.
The eastern front, or escarpment, of the SBRP is clearly defined from Virginia into South Carolina. On its western front the SBRP consists of the Unaka, Great Smoky, Unicoi, and other massive ranges. Connecting the eastern and western fronts are transverse ranges: Blacks, Great Craggies, Great Balsams, Nantahalas, and many others. The Appalachian system as a whole reaches its greatest elevation, largest mass, and most rugged topography in the SBRP where numerous peaks rise 5,000 feet or more, with 50 or so of them surpassing 6,000 feet. (From Mt. Rogers in Virginia northward to the Gaspe Peninsula, only Mt. Washington in New Hampshire exceeds 6,000 feet.) Perhaps 40 of the 6,000-foot peaks are in Western North Carolina
This topography profoundly influences the region’s average temperature (and thereby its plant and animal life, which exhibit strong northern affinities). The principle of verticality states that for each 1,000 feet gained in elevation the mean temperature decreases about 4 degrees Fahrenheit, equivalent to a change of 250 miles in latitude. (This means that if you travel from the lowest elevations in the SBRP at about 1,000 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.)
The SBRP is situated where winds bringing saturated air masses from the Gulf of Mexico and the southern Coastal Plain are cooled and lose much of their content. (Air cools while rising to pass over a mountain range and can hold less moisture than warm air; therefore, heavy condensation occurs where large fronts first encounter massive ranges, as is the instance along the Blue Ridge divide.)
The heaviest rainfall in the entire Appalachian region occurs along the Ga.-N.C.-S.C. borders, resulting in annual rainfalls of over 90 inches in many areas. (As much as 145 inches have been recorded since 1935 along the Ga.-N.C. line by the Coweeta Hydrologic Lab located near Otto). Taking this into consideration, some professional observers now refer to the area as a temperate rain forest.
The higher elevations of the SBRP can be thought of as a peninsula of northern terrain extending into the southeastern US where typical flora and fauna of northeastern and southeastern North America flourish. The region features approximately 1,500 vascular plants (many of which are considered to be showy wildflowers) and 125 species of trees (in all of Europe there are only about 75 species).
Seventy miles long, the Great Smokies is the largest mountain range in eastern North America. The national park, which incorporates most of the Smokies within its boundaries, consists of 520,000 acres. Even so, the range is just one of the numerous mountain ranges on the southwestern edge of the SBRP.