Blue Ridge Mountains

The Blue Ridge Mountains are a major physiographic province within the Appalachian Highlands. Located in the Eastern United States, this range extends 550 miles (885 km) southwest. It travels from southern Pennsylvania through Maryland, Virginia, North Carolina, South Carolina, Tennessee, and Georgia.

To the west of the range lies the Great Appalachian Valley. This valley separates the Blue Ridge from the Ridge and Valley province. The Blue Ridge is famous for its distinct bluish appearance when viewed from a distance. This color comes from isoprene released by trees into the atmosphere. This chemical creates a characteristic haze that gives the mountains their name.

The geography of the province is quite complex and varied. While some use the term for just the eastern edge, the geological definition is much broader. It includes the Great Smoky Mountains, the Great Balsams, the Roans, and the Blacks. In North Carolina, the Brushy and South Mountains are considered spurs of the range. In Virginia, the Southwest Mountains form an anticlinal range that parallels the main Blue Ridge. The range reaches as far north as South Mountain in Pennsylvania. From there, the ancient rock core continues through the New Jersey and Hudson River highlands. It eventually reaches the Berkshires in Massachusetts and the Green Mountains in Vermont.

The mountains contain some of the highest elevations in eastern North America. Only Baffin Island sits further north with similar heights. About 125 peaks in the range exceed 5,000 feet (1,500 m) in elevation. The highest point is Mount Mitchell in North Carolina, which reaches 6,684 feet (2,037 m). This is the highest peak in the entire Appalachian chain. In North Carolina and Tennessee, there are 39 peaks higher than 6,000 feet (1,800 m). Mountain climbers often refer to this specific group of high peaks as the Southern Sixers.

The geology of the Blue Ridge is shaped by very ancient processes. Most of the mountains consist of granitic charnockites, metamorphic volcanic formations, and sedimentary limestone. Geologists like Richard Tollo have studied the basement suites of these rocks. These basement rocks are made of unique gneisses and granitoids. Some of these rocks contain orthopyroxene, a specific type of mineral. Analysis of zircon minerals by the U.S. Geological Survey has helped determine their ages. The Blue Ridge basement is a composite orogenic crust. This means it was formed by several episodes of crustal magma activity.

These rocks provide clues about the Earth's deep history. Many features in the Blue Ridge match other North American Grenville-age terranes. However, the Blue Ridge is distinct from the Adirondacks and the Green Mountains. Zircon ages of less than 1.2 billion years suggest a different history. Rocks emplaced before 1.078 billion years ago show signs of deformation. Rocks formed after 1.064 billion years ago usually have a massive texture. This is because they missed the main period of Mesoproterozoic compression. When they first emerged, these mountains were as high as the Alps. Over hundreds of millions of years, weathering and erosion have lowered them.

Human history in the region involves many different groups. The Siouan Manahoacs, Iroquois, and Shawnee once hunted and fished at the foot of the mountains. In 1669, the explorer John Lederer reached the crest of the range. He recorded the Virginia Siouan name for the mountains, which was Ahkonshuck. Later, treaties changed how the land was managed by colonial powers. The Treaty of Albany between 1718 and 1722 set the Blue Ridge as a boundary. It separated lands belonging to the Iroquois from those of the Virginia Colony. Eventually, the Treaty of Lancaster in 1744 saw the sale of rights to the Shenandoah Valley.

The environment supports a wide variety of life. The slopes feature stunted oak-hickory forests, grass, shrubs, and hemlock. The highest areas are covered in dense Southern Appalachian spruce-fir forests. Unlike northern mountains, the climate here is too warm for a true alpine tree line.

Many animals live here, including American black bears, bobcats, and coyotes. You can also find whitetail deer, wild boar, and many species of fish. Some fish species are endemic, meaning they are found nowhere else.

Visitors can explore the area through Shenandoah and Great Smoky Mountains National Parks. The 469-mile Blue Ridge Parkway connects these two major parks.