The ridge named blue
Last week, we reviewed current theories concerning the uplift of the Appalachian Mountains about 250 million years ago. And we also reviewed several theories about how high the Appalachians might have been when originally uplifted. Opinions among various authorities range from about 10,000 feet to 30,000 feet in elevation. This week, let’s take a closer look at the area of Appalachians in which we reside — the Southern Blue Ridge Province.
I consider the Southern Appalachians to be those mountains located south of that point in northeastern Pennsylvania to which glacial ice extended 18,000 years ago at the height of the last Ice Age. The region is made up of four distinct geographic provinces: Piedmont Province, Blue Ridge Province, Valley and Ridge Province, and Appalachian Plateau Province.
The Piedmont Province lies between the Coastal Plain and the Blue Ridge. This belt extends from New Jersey to Georgia, and is about 50 miles wide in its northern portion and from one hundred to 150 miles wide in its southern. It is the eroded eastern rim of the ancient Southern Appalachians. Piedmont peaks — sometimes called monadnocks or inselbergs — such as Smith Mountain in Virginia, Pilot Mountain in North Carolina, Parris Mountain in South Carolina, and Stone Mountain in Georgia are the remnants of what was once much higher terrain.
The Ridge and Valley Province lies to the west of the Blue Ridge and east of the Appalachian Plateau. It begins in northeast Alabama and northwest Georgia as a broad fertile valley that extends 1,200 miles northeastward through the Valley of East Tennessee (where Knoxville is located) through Virginia (via the Shenandoah Valley) and continues through portions of West Virginia, Maryland, and Pennsylvania before terminating as the Hudson-Champlain Valley in New York. In its northern portions, parallel ridges separated by narrow valleys gave the province its name. In Field Guide to the Land Forms of the United States (1972), John A Shimer provided this description: “From the air the landscape is distinctive and striking. The ridges ... extend to the horizon and appear like ordered wave crests, separated by relatively broad, flat troughs.” In Pennsylvania and New York, the province extends beyond the Southern Appalachians into the glaciated Northern Appalachians.
The Appalachian Plateau Province extends from north Alabama to western New York, including the easternmost portions of Tennessee, Kentucky, Ohio, and Pennsylvania. In eastern Ohio, Pennsylvania, and New York this province also extends beyond the Southern Appalachians into previously glaciated terrain. The sub-division of the province that extends southward from the Cumberland Gap — where Kentucky, Virginia, and Tennessee corner — to a point just south of Birmingham, Alabama, is known as the Cumberland Plateau. Because it was originally a part of the ancient North America plate that predated Appalachian uplift, some geologists don’t consider the Appalachian Plateau Province to be a part of the Southern Appalachians. But the region was so deformed by the cataclysmic events of 250 to 300 million years ago, I see no reason to exclude it from the Southern Appalachians.
In regard to mountainous terrain and flora, the Blue Ridge Province is by far the most significant region in eastern North America. It extends about 575 miles from southwest of Harrisburg, Pennsylvania, to the hills of north Georgia. The eastern front of the Blue Ridge is clearly defined from Virginia into South Carolina as a steep escarpment that descends into the adjacent Piedmont. This front reaches its greatest height of 2,500 feet near Blowing Rock, North Carolina. When viewed from a distance, it appears as a continuous blue wall of mountains — the aspect that gave the province its name.
Where the Roanoke River passes through a water gap at Roanoke, Virginia, geographers have divided the Blue Ridge into two almost equal sections. North of the water gap, the Northern Blue Ridge Province is a ridge five to fifteen miles in width and about 3,000 feet in elevation. This extends almost 275 miles through central Maryland to a point southwest of Harrisburg, Pennsylvania, where it expires in a series of low ridges.
South of the water gap, the Southern Blue Ridge Province extends southwestward for 300 miles — encompassing portions of Tennessee, North Carolina, and South Carolina — before reaching its terminus at Mt. Oglethorpe, about 35 miles north of Atlanta. The Southern Blue Ridge is bounded on the east by the range called the Blue Ridge Mountains. On its western front, the province consists of the Iron, Great Smoky, Unocoi, and other massive ranges known as the Unakas. Connecting the Blue Ridge Mountain eastern front and the Unakas western front are numerous transverse ranges such as the Blacks, Great Craggies, Newfounds, Great Balsams, Cowees, and Nantahalas.
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.” All of those exceeding 6,000 feet are located in either western North Carolina or east Tennessee, mostly in North Carolina. Situated northeast of Asheville, North Carolina, Mount Mitchell at 6,684 feet is the highest mountain in eastern North America. The terrain of the province becomes even more impressive when you consider that from the North Carolina-Virginia state line northward in the Appalachians to the Gaspe Peninsula in Canada only Mt. Washington in New Hampshire exceeds 6,000 feet.
(Editor’s Note: This column is part of the opening section of George Ellison’s new book, A Blue Ridge Nature Journal, which will be published by The History Press (Charleston) in September 2006. In addition to 30 essays by the author, the large-format hardcover volume will feature 40 full-color paintings and 30 decorative chapter illustrations by artist Elizabeth Ellison.)