Blue Ridge Mountains
The Cherokee called them Sagonige Tsalegi, which means blue mountain ridge. The English name for the Blue Ridge Mountains carries the same idea. It is a strange label for a mountain range. Most mountains look green or gray or brown, depending on how close the viewer stands. So why do these slopes look blue from a distance? How did a range once among the tallest on Earth end up so worn down? And what happened when European colonists reached the foot of this ridge and found others already living and hunting there? The answers begin with a color that no one painted.
Isoprene is the chemical behind the name. Trees across the range release it into the air, and it hangs in the atmosphere around the slopes.
That isoprene feeds the characteristic haze of the Blue Ridge. Together, the haze and the gas shape the bluish tint the eye perceives when it looks across the valleys. The color belongs to the air as much as to the land.
The tint also raises a practical question for anyone trying to map the range. Whether a viewer is looking at the Blue Ridge proper depends on which definition of the name is in use.
Geologists and everyday speakers draw the line in different places. In ordinary use, Blue Ridge can mean only the front range along the eastern edge of the Appalachian Mountains. The geological definition reaches west to the Ridge and Valley area. That wider province takes in the Great Smoky Mountains, the Great Balsams, the Roans, the Blacks, and other ranges.
On the geological definition, the province is a division of the larger Appalachian Highlands. It stretches 550 miles, or 885 kilometers, southwest from southern Pennsylvania. Along the way it crosses Maryland, West Virginia, Virginia, North Carolina, South Carolina, Tennessee, and Georgia. A northern and a southern region divide near the Roanoke River gap. To the west lies the Great Appalachian Valley, and beyond that valley sits the Ridge and Valley province.
A few lower ranges hover at the edges of the definition. In North Carolina, the Brushy Mountains and the South Mountains lie to the east, and people often count them as spurs. In Virginia, the Southwest Mountains form an anticlinal range that runs parallel to the Blue Ridge.
At the northern end, South Mountain in Pennsylvania dwindles to hills between Gettysburg and Harrisburg. The ancient band of rock at the core of the Blue Ridge does not stop there. It continues northeast through the New Jersey and Hudson River highlands, then reaches the Berkshires of Massachusetts and the Green Mountains of Vermont. At the opposite end, far to the south, the province finishes at Mount Oglethorpe in Georgia.
About 125 peaks in the Blue Ridge rise above 5000 feet. No mountains in eastern North America stand higher, apart from those on Baffin Island far to the north.
Mount Mitchell in North Carolina is the champion, at 6684 feet. It is the highest point in the Blue Ridge and in the entire Appalachian chain.
The contrast with the northern Appalachians is sharp. In North Carolina and Tennessee, 39 peaks climb above 6000 feet. In the northern portion of the chain, only New Hampshire's Mount Washington clears that mark.
Peak baggers who chase every one of the 6000-foot summits have a name for the group. They call them the Southern Sixers.
Charnockites, a kind of ancient granitic rock, make up much of the Blue Ridge. The rest comes from metamorphosed volcanic formations and sedimentary limestone.
Richard Tollo, a professor and geologist at George Washington University, has sharpened the picture of the basement rocks. His work covers their petrology and the timing of their formation. The basement turns out to be built from unusual gneisses and granitoids, including charnockites that contain orthopyroxene. John Aleinikoff of the U.S. Geological Survey added detail by analyzing zircon minerals in the granite, which gave more precise ages for when the rock was emplaced.
The findings link the Blue Ridge to other North American terranes of Grenville age. Yet the rocks lack a calc-alkaline affinity, and the zircon ages are younger than 1.2 billion years. Those clues suggest the Blue Ridge differs from the Adirondacks and the Green Mountains, and possibly from the New York and New Jersey Highlands.
The data describe a composite crust, emplaced across several episodes from a crustal magma source. Rocks emplaced before 1.078-1.064 billion years ago preserve signs of deformation. Those emplaced after 1.064 billion years ago generally have a massive texture, because they missed the main episode of Mesoproterozoic compression.
When these mountains first emerged, they ranked among the highest in the world and matched the much younger Alps. Hundreds of millions of years of weathering, erosion, and mass wasting have cut the peaks far lower. The first European known to stand on the surviving crest was a German physician, and he arrived in 1669.
Long before that physician arrived, several nations used the land at the foot of the ridge. The Siouan Manahoacs, the Iroquois, and the Shawnee all hunted and fished there.
John Lederer, the German physician-explorer, returned to the crest the following year. He also recorded the Virginia Siouan name for the range, Ahkonshuck.
Between 1718 and 1722, Virginia Lieutenant Governor Alexander Spotswood negotiated the Treaty of Albany with the Iroquois. Under it, the Iroquois ceded to the Virginia Colony the lands they had conquered south of the Potomac River and east of the Blue Ridge. The ridge became a boundary. On one side lay the areas and tribes subject to the Six Nations. On the other lay those tributary to the colony.
The boundary did not hold. In the 1730s, colonists began crossing the Blue Ridge and settling the Shenandoah Valley on its western side. The Iroquois objected. They finally sold their rights to that valley at the Treaty of Lancaster in 1744.
Stunted oak and oak-hickory forests cover most of the Appalachian slope forests in the Blue Ridge. Grasses, shrubs, hemlock, and mixed oak-pine forests fill out the plant life.
The highest ground has no tree line, even though it holds the highest summits in the eastern United States. The climate is too warm to support an alpine zone. Statistical modelling predicts that at this latitude, a tree line would appear only above 7,985 feet, or 2434 meters. In practice, dense Southern Appalachian spruce-fir forests cover the highest parts.
The Ocoee salamander is one of many amphibians and reptiles in the region. The rivers hold a large diversity of fish, and many of those species are endemic.
American black bears roam the forests, along with bobcats, coyotes, red foxes, and gray foxes. Whitetail deer, wild boar, raccoons, and North American river otters also live here. Grouse and wild turkeys share the habitat with songbirds and other birds.
People share this habitat too, in towns and cities set among the mountains themselves.
The Blue Ridge Parkway runs 469 miles along the crest lines of the southern Appalachians. This scenic highway links Shenandoah National Park in the northern section with Great Smoky Mountains National Park in the southern section. The Appalachian Trail follows the same crest lines.
Along the parkway, outcrops of gneiss show folded bands of light and dark minerals. In places they look like the folds and swirls in a marble cake.
Eight national forests also lie within the province. They include George Washington and Jefferson, Cherokee, Pisgah, Nantahala, and Chattahoochee.
Roanoke, in Southwest Virginia, is the largest city in the Blue Ridge. Other notable cities include Charlottesville, Frederick, Hagerstown, Chambersburg, Asheville, Johnson City, and Lynchburg.
The biggest metropolitan area is a different matter. It is the Greenville metropolitan area in Upstate South Carolina, which gives the range a large urban population on its southern flank.
Updated
Common questions
What does Blue Ridge mean in Cherokee?
The Cherokee name is Sagonige Tsalegi, which means blue mountain ridge.
Why do the Blue Ridge Mountains look blue?
Trees release isoprene into the atmosphere. This contributes to the haze on the mountains and to their perceived bluish color.
How long is the Blue Ridge province?
It extends 550 miles, or 885 kilometers, southwest from southern Pennsylvania to Georgia.
What is the highest peak in the Blue Ridge?
Mount Mitchell in North Carolina, at 6684 feet. It is also the highest peak in the entire Appalachian chain.
What does the Blue Ridge Parkway connect?
The 469-mile parkway links Shenandoah National Park in the north with Great Smoky Mountains National Park in the south.
What was the Treaty of Lancaster in 1744?
It was the agreement in which the Iroquois finally sold their rights to the Shenandoah Valley, on the western side of the Blue Ridge.
All sources
14 references cited across the entry
- 1Blue RidgeU.S. Geological Survey
- 2Physiographic divisions of the conterminous U. S.U.S. Geological Survey
- 3BookInvitation To Organic ChemistryJohnson, A. W. — Jones & Bartlett Learning — 1998
- 4Blue Ridge Parkway, Frequently Asked QuestionsNational Park Service — 2007
- 5Blue Ridge Physiographic ProvinceDr. Robert D. Leighty — Defense Advanced Research Projects Agency (DOD) Information Sciences Office — 2001
- 6Physiography of North CarolinaM.A. Medina — North Carolina Geological Survey, Division of Land Resources — 2004
- 8JournalPetrology and Geochronology of Grenville-Age Magmatism, Blue Ridge Province, Northern VirginiaRichard P. Tollo et al. — Geological Society of America — 2004
- 9BookSouthern United States: An Environmental HistoryDonald E. Davis et al. — ABC-CLIO — 2006
- 11NewsBlue Ridge Mountains
- 12JournalPredicting Treeline Elevation in the Southern AppalachiansCharles V. Cogbill et al. — 1997
- 13Partners in Flight: Bird Conservation Plan for the Southern Blue RidgeChuck Hunter et al. — Partners in Flight, American Bird Conservancy — December 1999