Ridge-and-Valley Appalachians

Blue Mountain in the Lehigh Valley region of Pennsylvania

Ridges and valleys near Norton, Virginia in southwestern Virginia

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 in the north through northwestern New Jersey, westward into Pennsylvania through the Lehigh Valley, 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.

The river valleys were areas of indigenous settlements for thousands of years. In the historic period, the Cherokee people had towns along many of the rivers in western South Carolina and North Carolina, as well as on the western side of the Appalachian Mountains in present-day Tennessee. Similarly, the Catawba people occupied areas along the upper Catawba River in Western North Carolina, to the east of Cherokee County.

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 European-American migrants who walked or rode horses traveling west to settle the Ohio Country, and later the Northwest Territory and Oregon Country. 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. These were later improved as America's first National Roads (respectively Wilderness Road, Cumberland Road, Lincoln Highway or designated U.S. 40 and U.S. 30 in later years). Early settlers of the Ohio country tended to enter it via the Ohio River; river systems were the most important transportation corridors. It was difficult in the late 19th and 20th centuries to construct railroads and modern highways through this area.

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. The Valley and Ridge is located on the west side of the Blue Ridge Mountains.

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. Here, strata have been folded westward, and forced over massive thrust faults; there is little metamorphism, and no igneous intrusion. 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)

Name	State
Shawangunk Ridge	New York
Kittatinny Mountain	New Jersey
Bald Eagle Mountain	Pennsylvania
Blue Mountain	Pennsylvania
South Mountain	Pennsylvania
Jacks Mountain	Pennsylvania
Moosic Mountains	Pennsylvania
Nittany Mountain	Pennsylvania
Tuscarora Mountain	Pennsylvania
Tussey Mountain	Pennsylvania
Wills Mountain	Pennsylvania and Maryland
Dans Mountain	Maryland
Sideling Hill	West Virginia, Maryland, and Pennsylvania
Cacapon Mountain	West Virginia
Knobly Mountain	West Virginia
Mill Creek Mountain	West Virginia
New Creek Mountain	West Virginia
North Fork Mountain	West Virginia
Patterson Creek Mountain	West Virginia
Sleepy Creek Mountain	West Virginia
South Branch Mountain	West Virginia
Allegheny Mountain	Virginia and West Virginia
Great North Mountain	Virginia and West Virginia
North Mountain	Virginia and West Virginia
Shenandoah Mountain	Virginia and West Virginia
Massanutten Mountain	Virginia
Pine Mountain	Kentucky, Virginia, and Tennessee
Clinch Mountain	Tennessee and Virginia
Powell Mountain	Tennessee and Virginia
Bays Mountain	Tennessee
House Mountain	Tennessee
Sharp's Ridge	Tennessee
Taylor Ridge (Georgia)	Georgia
White Oak Mountain	Tennessee and Georgia
Missionary Ridge	Tennessee and Georgia
Stringer's Ridge	Tennessee
Lookout Mountain	Tennessee, Georgia, and Alabama
Red Mountain	Alabama

Photo gallery

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  Shaded relief map of Cumberland Plateau and Ridge and Valley Appalachians on the Virginia/West Virginia border

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  Pennsylvania's ridge country from Clarks Knob

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  Oblique air photo of Massanutten Mountain, looking southwest. The south fork of the Shenandoah River is visible to the left, as well as a part of the Blue Ridge Mountains.

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  Oblique air photo facing north of central Bedford County, Pennsylvania, in December 2006, showing Wills, Evitts, and Tussey Mountains from center to right.

See also

• Geology of the Appalachians
• Allegheny Front
• Eastern Continental Divide
• Tennessee Valley Divide

References

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