The Blue Ridge Mountains are noted for having a bluish color when seen from a distance.Trees put the "blue" in Blue Ridge, from the isoprene released into the atmosphere, thereby contributing to the characteristic haze on the mountains and their distinctive color.
Although the term "Blue Ridge" is sometimes applied exclusively to the eastern edge or front range of the Appalachian Mountains, the geological definition of the Blue Ridge province extends westward to the Ridge and Valley area, encompassing the Great Smoky Mountains, the Great Balsams, the Roans, the Brushy Mountains (a "spur" of the Blue Ridge) and other mountain ranges.
The Blue Ridge contains the highest mountains in eastern North America south of Baffin Island. About 125 peaks exceed 5,000 feet (1,500 m) in elevation. The highest peak in the Blue Ridge (and in the entire Appalachian chain) is Mt. Mitchell in North Carolina at 6,684 feet (2,037 m). There are 39 peaks in North Carolina and Tennessee higher than 6,000 feet (1,800 m); by comparison, only New Hampshire's Mt. Washington rises above 6,000 feet (1,800 m) in the northern portion of the Appalachian chain.
The Blue Ridge Parkway runs 469 miles (755 km) along crests of the Southern Appalachians and links two national parks: Shenandoah and Great Smoky Mountains. In many places along the parkway, there are metamorphic rocks (gneiss) with folded bands of light-and dark-colored minerals, which sometimes look like the folds and swirls in a marble cake.
Blue Ridge Mountains, viewed from the Chimney Rock Mountain Overlook in Virginia
Most of the rocks that form the Blue Ridge Mountains are ancient graniticcharnockites, metamorphosed volcanic formations, and sedimentary limestones. Recent studies completed by Richard Tollo, a professor and geologist at George Washington University, provide greater insight into the petrologic and geochronologic history of the Blue Ridge basement suites. Modern studies have found that the basement geology of the Blue Ridge is made of compositionally unique gneisses and granitoids, including orthopyroxene-bearing charnockites. Analysis of zircon minerals in the granites completed by John Aleinikoff at the U.S. Geological Survey has provided more detailed emplacement ages.
The northernmost extension of the Blue Ridge Mountains, in northern Maryland
Many of the features found in the Blue Ridge and documented by Tollo and others have confirmed that the rocks exhibit many similar features in other North American Grenville-ageterranes. The lack of a calc-alkaline affinity and zircon ages less than 1,200 Ma suggest that the Blue Ridge is distinct from the Adirondacks, Green Mountains, and possibly the New York-New Jersey Highlands. The petrologic and geochronologic data suggest that the Blue Ridge basement is a composite orogenic crust that was emplaced during several episodes from a crustal magma source. Field relationships further illustrate that rocks emplaced prior to 1,078-1,064 Ma preserve deformational features. Those emplaced post-1,064 Ma generally have a massive texture and missed the main episode of Mesoproterozoic compression.
The Blue Ridge Mountains began forming during the Silurian Period over 400 million years ago. Approximately 320 mya, North America and Europe collided, pushing the Blue Ridges up higher.
The Blue Ridge Mountains in the background from Lynchburg, Virginia
The English who settled colonial Virginia in the early 17th century recorded that the native Powhatan name for the Blue Ridge was Quirank. At the foot of the Blue Ridge, various tribes including the SiouxManahoacs, the Iroquois, and the Shawnee hunted and fished. A German physician-explorer, John Lederer, first reached the crest of the Blue Ridge in 1669 and again the following year; he also recorded the Virginia Siouan name for the Blue Ridge (Ahkonshuck).
At the Treaty of Albany negotiated by Governor Spotswood with the Iroquois between 1718 and 1722, the Iroquois ceded lands they had conquered south of the Potomac and east of the Blue Ridge to the Virginia Colony. This treaty made the Blue Ridge the new demarcation point between the areas and tribes subject to the Six Nations, and those tributary to the Colony. When colonists began to disregard this by crossing the Blue Ridge and settling in the Shenandoah Valley in the 1730s, the Iroquois began to object, finally selling their rights to the Valley, on the west side of the Blue Ridge, at the Treaty of Lancaster in 1744.
The forest environment provides natural habitat for many plants, trees, and animals.
The Blue Ridge Mountains have stunted oak and oak-hickory forests and comprise most of the Appalachian slope forests. Flora also includes grass, shrubs, hemlock and mixed-oak pine forests. While the Blue Ridge includes the highest summits in the eastern United States, the climate is nevertheless too warm to support an alpine zone, and thus the range lacks the tree line found at lower elevations in the northern half of the Appalachian range. The highest parts of the Blue Ridge are generally coated in a dense spruce-fir stand.
The John Denver hit "Take Me Home, Country Roads" (1971), mentions them in the line "Blue Ridge Mountains, Shenandoah River", a song supposedly about West Virginia. (These geographic features only traverse a tiny portion of the easternmost tip of the state, but the song was written in the Blue Ridge Mountains outside of the state according to its authors.)
The song "Battle Born" by The Killers contains the line "From the Blue Ridge to the Black Hills".