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, including The Great Appalachian Valley, which in the southerly sections divides the mountain system into two unequal 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.
Old fault exposed by roadcut near Harrisburg, Pennsylvania, along Interstate 81. Such faults are common in the folded Appalachians.
Mountains of the Long Range in Newfoundland reach heights of nearly 3,000 ft (900 m). In the Chic-Choc and Notre Dame mountain 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 1,000 to 2,700 ft (300 to 800 m). In Maine several peaks exceed 4,000 ft (1,200 m)., including Mount Katahdin 5,267 feet (1,605 m). In New Hampshire, many summits rise above 5,000 ft (1,500 m), including Mount Washington in the White Mountains 6,288 ft (1,917 m), Adams 5,771 ft (1,759 m), Jefferson 5,712 ft (1,741 m), Monroe 5,380 ft (1,640 m)), Madison 5,367 ft (1,636 m), Lafayette 5,249 feet (1,600 m), and Lincoln 5,089 ft (1,551 m). In the Green Mountains the highest point, Mt. Mansfield, is 4,393 ft (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 (900 m).
In Pennsylvania, there are over sixty summits that rise over 2,500 ft (800 m); the summits of Mount Davis and Blue Knob rise over 3,000 ft (900 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 feet (917 m) and Pidgeon Roost 3,400 ft (1,000 m). In West Virginia, more than 150 peaks rise above 4,000 ft (1,200 m)., including Spruce Knob 4,863 ft (1,482 m), the highest point in the Allegheny Mountains. A number of other points in the state rise above 4,800 ft (1,500 m). Snowshoe Mountain at Thorny Flat 4,848 ft (1,478 m) and Bald Knob 4,842 ft (1,476 m) are among the more notable peaks in West Virginia.
Cliffs overlooking the New River near Gauley Bridge, West Virginia.
The Blue Ridge Mountains, rising in southern Pennsylvania and there known as South Mountain, attain elevations of about 2,000 ft (600 m) in that state. South Mountain achieves its highest point just below the Mason-Dixon line in Maryland at Quirauk Mountain 2,145 ft (654 m) and then diminishes in height southward to the Potomac River. Once in Virginia the Blue Ridge again reaches 2,000 ft (600 m) and higher. In the Virginia Blue Ridge, the following are some of the highest peaks north of the Roanoke River: Stony Man 4,031 ft (1,229 m), Hawksbill Mountain 4,066 ft (1,239 m), Apple Orchard Mountain 4,225 ft (1,288 m) and Peaks of Otter 4,001 and 3,875 ft (1,220 and 1,181 m). South of the Roanoke River, along the Blue Ridge, are Virginia’s highest peaks including Whitetop Mountain 5,520 ft (1,680 m) and Mount Rogers 5,729 ft (1,746 m), the highest point in the Commonwealth.
Chief summits in the southern section of the Blue Ridge are located along two main crests — the Western or Unaka Front along the Tennessee-North Carolina border and the Eastern Front in North Carolina — or one of several “cross ridges” between the two main crests. Major subranges of the Eastern Front include the Black Mountains, Great Craggy Mountains, and Great Balsam Mountains, and its chief summits include Grandfather Mountain 5,964 ft (1,818 m) near the Tennessee-North Carolina border, Mount Mitchell 6,684 ft (2,037 m) in the Blacks, and Black Balsam Knob 6,214 ft (1,894 m) and Cold Mountain 6,030 ft (1,840 m) in the Great Balsams. The Western Blue Ridge Front is subdivided into the Unaka Range, the Bald Mountains, the Great Smoky Mountains, and the Unicoi Mountains, and its major peaks include Roan Mountain 6,285 ft (1,916 m) in the Unakas, Big Bald 5,516 ft (1,681 m) and Max Patch 4,616 ft (1,407 m) in the Bald Mountains, Clingmans Dome 6,643 ft (2,025 m), Mount Le Conte 6,593 feet (2,010 m), and Mount Guyot 6,621 ft (2,018 m) in the Great Smokies, and Big Frog Mountain 4,224 ft (1,287 m) near the Tennessee-Georgia-North Carolina border. Prominent summits in the cross ridges include Waterrock Knob (6,292 ft (1,918 m)) in the Plott Balsams. Across northern Georgia, numerous peaks exceed 4,000 ft (1,200 m), including Brasstown Bald, the state’s highest, at 4,784 ft (1,458 m) and 4,696 ft (1,431 m) Rabun Bald.
Paleogeographic reconstruction showing the Appalachian Basin area during the Middle Devonian period.
There are many geological issues concerning the rivers and streams of the Appalachians. In spite of the existence of the Great Appalachian Valley, many of the main rivers are transverse to the mountain system axis. 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, rivers head into the Blue Ridge, cross the higher Unakas, receive important tributaries from the Great Valley, and traversing the Cumberland Plateau in spreading gorges (water gaps), escape by way of the Cumberland River and the Tennessee River rivers to the Ohio River and the Mississippi River, and thence to the Gulf of Mexico. In the central section, north of the New River, the rivers, rising in or just beyond the Valley Ridges, flow through great gorges to the Great Valley, and then across the Blue Ridge to tidal estuaries penetrating the coastal plain via the Roanoke River, James River, Potomac River, and Susquehanna River.
In the northern section the height of land lies on the inland side of the mountainous belt, and thus the main lines of drainage runs from north to south, exemplified by the Hudson River. However, the valley through which the Hudson River flows was cut by the gigantic glaciers of the Ice Ages — the same glaciers that deposited their terminal moraines in southern New York and formed the east-west Long Island.
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