Appalachian Mountains

The Appalachian Mountains, often referred to as the Appalachians, are a vast system of mountains in eastern North America. Definitions vary on the precise boundaries of the Appalachians. The United States Geological Survey (USGS) defines the Appalachian Highlands physiographic division as consisting of thirteen provinces: the Atlantic Coast Uplands, Eastern Newfoundland Atlantic, Maritime Acadian Highlands, Maritime Plain, Notre Dame And Megantic Mountains, Western Newfoundland Mountains, Piedmont, Blue Ridge, Valley and Ridge, Saint Lawrence Valley, Appalachian Plateaus, New England province, and the Adirondack provinces. A common variant definition does not include the Adirondack Mountains, which are often said to have more in common with the Canadian Shield than the Appalachians.

The range is mostly located in the United States but extends into southeastern Canada, forming a zone from 100 to 300 miles (160 to 480 km) wide, running from the island of Newfoundland 1,500 miles (2,400 km) south-westward to central Alabama in the United States (with foothills in northeastern Mississippi). The system is divided into a series of ranges, with the individual mountains averaging around 3,000 ft (900 m). The highest of the group is Mount Mitchell in North Carolina at 6,684 feet (2,037 m), which is the highest point in the United States east of the Mississippi River.

The term Appalachian refers to several different regions associated with the mountain range. Most broadly, it refers to the entire mountain range with its surrounding hills and the dissected plateau region. However, the term is often used more restrictively to refer to regions in the central and southern Appalachian Mountains, usually including areas in the states of Kentucky, Tennessee, Virginia, Maryland, West Virginia, and North Carolina, as well as sometimes extending as far south as northern Georgia and western South Carolina, as far north as Pennsylvania, and as far west as southern Ohio.

The Ouachita Mountains in Arkansas and Oklahoma were originally part of the Appalachians as well, but were disconnected through geologic history.

While exploring the northern coast of Florida in 1528, the members of the Narváez expedition, including Álvar Núñez Cabeza de Vaca, found a Native American town whose name they transcribed as Apalachen. This name and its pronunciation were applied to the Apalachee Native Americans, as well as a nearby body of water, now spelled Apalachee Bay, to the Apalachicola River, Apalachicola Bay, and the Apalachicola Native Americans, and to the city known as Apalachicola, Florida.

The word Apalachen was also applied to an inland mountain range, and through the course of time it became applied to the entire range and its spelling was changed.

Geography

Regions

The whole system may be divided into three great sections: the Northern, from the Canadian province of Newfoundland and Labrador to the Hudson River; the Central, from the Hudson Valley to the New River (Great Kanawha), in Virginia and West Virginia; and the Southern, from the New River onwards.

The northern section includes the Long Range Mountains and Annieopsquotch Mountains on the island of Newfoundland, Chic-Choc Mountains and Notre Dame Range in Quebec and New Brunswick, scattered elevations and small ranges elsewhere in Nova Scotia and New Brunswick, the Longfellow Mountains in Maine, the White Mountains in New Hampshire, the Green Mountains in Vermont, and The Berkshires in Massachusetts and Connecticut, the Metacomet Ridge Mountains in Connecticut and south-central Massachusetts. The central section comprises, besides various minor groups, the Valley Ridges between the Allegheny Front of the Allegheny Plateau and the Great Appalachian Valley, the New York - New Jersey Highlands, the Taconic Mountains in New York, and a large portion of the Blue Ridge. The southern section consists of the prolongation of the Blue Ridge, the Unaka Range, and the Valley Ridges adjoining the Cumberland Plateau, with some lesser ranges.

The Adirondack Mountains in New York are sometimes considered part of the Appalachian chain but, geologically speaking, are a southern extension of the Laurentian Mountains of Canada.

In addition to the true folded mountains, known as the ridge and valley province, the area of dissected plateau to the north and west of the mountains is usually grouped with the Appalachians. This includes the Catskill Mountains of southeastern New York, the Poconos in Pennsylvania, and the Allegheny Plateau of southwestern New York, western Pennsylvania, eastern Ohio and northern West Virginia. This same plateau is known as the Cumberland Plateau in southern West Virginia, eastern Kentucky, western Virginia, eastern Tennessee, and northern Alabama.

The dissected plateau area, while not actually made up of geological mountains, is popularly called 'mountains', especially in eastern Kentucky and West Virginia, and while the ridges are not high, the terrain is extremely rugged. In Ohio and New York, some of the plateau has been glaciated, which has rounded off the sharp ridges, and filled the valleys to some extent. The glaciated regions are usually referred to as hill country rather than mountains.

The Appalachian region is generally considered the geographical dividing line between the eastern seaboard of the United States and the Midwest region of the country. The Eastern Continental Divide follows the Appalachian Mountains from Pennsylvania to Georgia.

The Appalachian Trail is a 2,175-mile (3,500 km) hiking trail that runs all the way from Mount Katahdin in Maine to Springer Mountain in Georgia, passing over or past a large part of the Appalachian system. The International Appalachian Trail is an extension of this hiking trail into the Canadian portion of the Appalachian range.

Chief summits

The Appalachian belt includes, with the ranges enumerated above, the plateaus sloping southward to the Atlantic Ocean in New England, and south-eastward to the border of the coastal plain through the central and southern Atlantic states; and on the north-west, the Allegheny and Cumberland plateaus declining toward the Great Lakes and the interior plains. A remarkable feature of the belt is the longitudinal chain of broad valleys—the Great Appalachian Valley—which in the southerly sections divides the mountain system into two subequal portions, but in the northernmost lies west of all the ranges possessing typical Appalachian features, and separates them from the Adirondack group. The mountain system has no axis of dominating altitudes, but in every portion the summits rise to rather uniform heights, and, especially in the central section, the various ridges and intermontane valleys have the same trend as the system itself. None of the summits reaches the region of perpetual snow.

Mountains of the Long Range in Newfoundland reach heights of nearly 3,000 ft (910 m). In the Shickshocks and Notre Dame ranges in Quebec the higher summits rise to about 4,000 ft (1,200 m). elevation. Isolated peaks and small ranges in Nova Scotia and New Brunswick vary from of 1,000 - 2,700 ft (820 m). In Maine several peaks exceed 4,000 ft (1,200 m)., including Mount Katahdin (5,267 ft). In New Hampshire, many summits rise above 4,000 feet (1,200 m), including Mount Washington in the White Mountains (6,288 ft), plus Adams (5,771), Jefferson (5,712), Monroe (5,380), Madison (5,367), Lafayette (5,260), and Lincoln (5,089) In the Green Mountains the highest point, Mt. Mansfield, is 4,393 feet (1,339 m) in elevation; others include Killington Peak at 4,226 ft (1,288 m)., Camel's Hump at 4,083 ft (1,244 m)., Mt. Abraham at 4,006 ft (1,221 m)., and a number of other heights exceeding 3,000 ft (910 m).

In Pennsylvania, there are over sixty summits that rise over 2,500 ft (760 m); the summits of Mount Davis and Blue Knob rise over 3,000 ft (910 m). In Maryland, Eagle Rock and Dans Mountain are conspicuous points reaching 3,162 ft (964 m). and 2,882 ft (878 m)., respectively. On the same side of the Great Valley, south of the Potomac, are the Pinnacle (3,007 ft) and Pidgeon Roost (3,400 ft). In West Virginia, more than 150 peaks rise above 4,000 ft (1,200 m)., including Spruce Knob (4863 ft), the highest point in the Allegheny Mountains. A number of other points in the state rise above 4,800 ft (1,500 m). Thorny Flat (4,848 ft) and Bald Knob (4,842 ft) are among the more notable peaks in West Virginia.

The Blue Ridge Mountains, rising in southern Pennsylvania and there known as South Mountain, attain in that state an elevation of about 2,000 ft (610 m).; southward to the Potomac its altitudes diminish, but once in Virginia the Blue Ridge again reaches 2,000 ft (610 m). and higher. In the Virginia Blue Ridge, the following are the highest peaks east of the New River: Mary's Rock (3,523 ft), Stony Man (4,031), Hawksbill Mountain (4,066), and Peaks of Otter (4001 and 3875).

In the southern section of the Blue Ridge is Grandfather Mountain (5,964 ft), with three other summits above 5,000, and a dozen more above 4000. The Unaka Ranges (including the Black and Great Smoky Mountains) have eighteen peaks higher than 5,000 ft (1,500 m)., and eight surpassing 6,000 ft (1,800 m). In the Black Mountains, Mt. Mitchell (the culminating point of the whole system) attains an altitude of 6,684 feet (2,037 m). In the Great Smoky Mountains, Clingman's Dome (6,643 ft) is the highest peak, with several others above 6,000 and many higher than 5,000.

In spite of the existence of the Great Appalachian Valley, the master streams are transverse to the axis of the system. The drainage divide of the Appalachians follows a tortuous course which crosses the mountainous belt just north of the New River in Virginia; south of the New River the rivers head in the Blue Ridge, cross the higher Unakas, receive important tributaries from the Great Valley, and traversing the Cumberland Plateau in spreading gorges, escape by way of the Cumberland and Tennessee rivers to the Ohio and Mississippi, and thus to the Gulf of Mexico; in the central section the rivers, rising in or beyond the Valley Ridges, flow through great gorges (water gaps) to the Great Valley, and by south-easterly courses across the Blue Ridge to tidal estuaries penetrating the coastal plain; in the northern section the height of land lies on the inland side of the mountainous belt, the main lines of drainage running from north to south.

Geology

A look at rocks exposed in today's Appalachian Mountains reveals elongated belts of folded and thrust faulted marine sedimentary rocks, volcanic rocks and slivers of ancient ocean floor, which provides strong evidence that these rocks were deformed during plate collision. The birth of the Appalachian ranges, some 300 million years ago, marks the first of several mountain building plate collisions that culminated in the construction of the supercontinent Pangaea with the Appalachians near the center. Because North America and Africa were connected, the Appalachians form part of the same mountain chain as the Anti-Atlas in Morocco. To the northeast, the same mountain chain continues into Scotland, from the North America/Europe collision.

During the middle Ordovician Period (about 496-440 million years ago), a change in plate motions set the stage for the first Paleozoic mountain building event (Taconic orogeny) in North America. The once-quiet Appalachian passive margin changed to a very active plate boundary when a neighboring oceanic plate, the Iapetus, collided with and began sinking beneath the North American craton. With the birth of this new subduction zone, the early Appalachians were born. Along the continental margin, volcanoes grew, coincident with the initiation of subduction. Thrust faulting uplifted and warped older sedimentary rock laid down on the passive margin. As mountains rose, erosion began to wear them down. Streams carried rock debris down slope to be deposited in nearby lowlands. The Taconic Orogeny was just the first of a series of mountain building plate collisions that contributed to the formation of the Appalachians, culminating in the collision of North America and Africa (see Appalachian orogeny).

By the end of the Mesozoic era, the Appalachian Mountains had been eroded to an almost flat plain. It was not until the region was uplifted during the Cenozoic Era that the distinctive topography of the present formed. Uplift rejuvenated the streams, which rapidly responded by cutting downward into the ancient bedrock. Some streams flowed along weak layers that define the folds and faults created many millions of years earlier. Other streams downcut so rapidly that they cut right across the resistant folded rocks of the mountain core, carving canyons across rock layers and geologic structures.

The Appalachian Mountains contain major deposits of anthracite coal as well as bituminous coal. In the folded mountains the coal is in metamorphosed form as anthracite represented by the Coal Region of northeastern Pennsylvania. The bituminous coal fields of western Pennsylvania, western Maryland, southeastern Ohio, eastern Kentucky, southwestern Virginia, and West Virginia is the sedimentary form. Some plateaus of the Appalachian Mountains contain metallic minerals such as iron and zinc.

Sources: Brooks, Maurice (1965), The Appalachians: The Naturalist's America; illustrated by Lois Darling and Lo Brooks. Boston; Houghton Mifflin Company; Caudill, Harry M. (1963), Night Comes to the Cumberlands; Constantz, George (2004), Hollows, Peepers, and Highlanders: an Appalachian Mountain Ecology (2nd edition). West Virginia University Press; Morgantown; Weidensaul, Scott (2000), Mountains of the Heart: A Natural History of the Appalachians. Fulcrum Publishing.