Ridge-and-Valley Appalachians

The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending from southeastern New York through northwestern New Jersey, westward into Pennsylvania and southward into Maryland, West Virginia, Virginia, Kentucky, Tennessee, Georgia and Alabama. They form a broad arc between the Blue Ridge Mountains and the Appalachian Plateau physiographic province (the Allegheny and Cumberland Plateaus). They are characterized by long, even ridges, with long, continuous valleys in between.

Ridge-and-Valley

Ridges and valleys near Norton, Virginia

The ridge and valley system presents an important obstacle to east–west land travel even with today's technology. It was a nearly insurmountable barrier to railroads crossing the range as well as to walking or horse-riding migrants traveling west to settle the Ohio Country, Northwest Territory and Oregon Country, before the days of motorized transportation. In the era when animal power dominated transportation there was no safe way to cross east–west in the middle of the range; crossing was only possible nearer its extremes except for a few rough passages opened mid-range during the colonial era such as Cumberland Gap, Braddock's Road and Forbes Road, later improved into America's first National Roads (respectively Wilderness Road, Cumberland Road, Lincoln Highway or designated U.S. 40 and U.S. 30 in later years).

Geography

The eastern head of the Ridge and Valley region is marked by the Great Appalachian Valley, which lies just west of the Blue Ridge. The western side of the Ridge and Valley region is marked by steep escarpments such as the Allegheny Front, the Cumberland Mountains, and Walden Ridge.

Geology
Appalachian zones in the US – USGS

These curious formations are the remnants of an ancient fold-and-thrust belt, west of the mountain core that formed in the Alleghenian orogeny (Stanley, 421-2). Here, strata have been folded westward, and forced over massive thrust faults; there is little metamorphism, and no igneous intrusion.(Stanley, 421-2) The ridges represent the edges of the erosion-resistant strata, and the valleys portray the absence of the more erodible strata. Smaller streams have developed their valleys following the lines of the more easily eroded strata. But a few major rivers, such as the Delaware River, the Susquehanna River, the New River, and the Potomac River, are evidently older than the present mountains, having cut water gaps that are perpendicular to hard strata ridges. The evidence points to a wearing down of the entire region (the original mountains) to a low level with little relief, so that major rivers were flowing in unconsolidated sediments that were unaffected by the underlying rock structure. Then the region was uplifted slowly enough that the rivers were able to maintain their course, cutting through the ridges as they developed.

Valleys may be synclinal valleys or anticlinal valleys.

These mountains are at their highest development in central Pennsylvania, a phenomenon termed the Pennsylvania climax.

Significant ridges (from north to south)
NameState
Shawangunk RidgeNew York
Kittatinny MountainNew Jersey
Bald Eagle MountainPennsylvania
Blue MountainPennsylvania
Jacks MountainPennsylvania
Moosic MountainsPennsylvania
Nittany MountainPennsylvania
Tuscarora MountainPennsylvania
Tussey MountainPennsylvania
Wills MountainPennsylvania and Maryland
Sideling HillWest Virginia, Maryland, and Pennsylvania
Cacapon MountainWest Virginia
Knobly MountainWest Virginia
Mill Creek MountainWest Virginia
New Creek MountainWest Virginia
North Fork MountainWest Virginia
Patterson Creek MountainWest Virginia
Sleepy Creek MountainWest Virginia
South Branch MountainWest Virginia
Spruce KnobWest Virginia
Allegheny MountainVirginia and West Virginia
Great North MountainVirginia and West Virginia
North MountainVirginia and West Virginia
Shenandoah MountainVirginia and West Virginia
Massanutten MountainVirginia
Pine MountainKentucky, Virginia, and Tennessee
Clinch MountainTennessee and Virginia
Powell MountainTennessee and Virginia
Bays MountainTennessee
House MountainTennessee
Sharp's RidgeTennessee
Taylor Ridge (Georgia)Georgia
White Oak MountainTennessee and Georgia
Missionary RidgeTennessee and Georgia
Stringer's RidgeTennessee
Lookout MountainTennessee, Georgia, and Alabama
Red MountainAlabama
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See also

References
    • Stanley, Steven M. Earth System History. New York: W.H. Freeman and Company, 1999. ISBN 0-7167-2882-6
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