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 Mountainsextending from northern New Jerseywestward into Pennsylvaniaand southward into Maryland, West Virginia, Virginia, Tennessee, and Alabama. They form a broad arc between the Blue Ridge Mountainsand the Appalachian Plateauphysiographic province (the Allegheny and Cumberland Plateaus).
These mountains are characterized by long, even
ridges, with long, continuous valleys in between. From a great enough altitude, they look almost like corduroy, except that the widths of the valleys are somewhat variable and ridges sometimes meet in a vee.
The eastern edge 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.
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, and the Potomac Riverare evidently older than the present mountains, having cut water gaps that are perpendicular to hard strata ridges. The evidence point 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.
These mountains are at their highest development in central Pennsylvania, a phenomenon termed the "Pennsylvania climax".
Name State Allegheny Mountain Virginia and West Virginia Bald Eagle Mountain Pennsylvania Bays Mountain Tennessee Blue Mountain Pennsylvania Cacapon Mountain West Virginia Clinch Mountain Tennessee and Virginia Great North Mountain Virginia and West Virginia Jacks Mountain Pennsylvania Kittatinny Mountains New Jersey Knobly Mountain West Virginia Mill Creek Mountain West Virginia New Creek Mountain West Virginia Nittany Mountain Pennsylvania North Mountain Virginia and West Virginia North Fork Mountain West Virginia Patterson Creek Mountain West Virginia Powell Mountain Tennessee and Virginia Red Mountain Alabama Shawangunk Ridge New York Sideling Hill West Virginia, Maryland, and Pennsylvania Sleepy Creek Mountain West Virginia South Branch Mountain West Virginia Spruce Knob West Virginia Tuscarora Mountain Pennsylvania Tussey Mountain Pennsylvania Wills Mountain Pennsylvania and Maryland
Geology of the Appalachians
Eastern Continental Divide
Tennessee Valley Divide
*Stanley, Steven M. "Earth System History". New York: W.H. Freeman and Company, 1999. ISBN 0-7167-2882-6
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