A Look at the Valley and Ridge

Viewed from above, the Valley and Ridge physiographic province is one of the most defining features of the Appalachian Mountains; its alternating, narrow ridges and valleys almost resemble a corduroy pattern. The province is situated west of the Blue Ridge Mountain province and east of the Appalachian Plateau. Like the rest of the Appalachian Highlands Region, the Valley and Ridge moves from southwest to northeast (from Alabama to New York).   The Great Valley, which makes up the eastern portion of the Valley and Ridge, is known by more than 10 different regional names over its 1,200-mile path. It has hosted settlements on its fertile soils and served as a north-south travel route for a very long time.  The western half of the Valley and Ridge is comprised of the Cumberland Mountains to the south and Allegheny Mountains to the north; the boundary between the two is located in West Virginia. Many mountain ridges in the province rise upwards of 4,000 feet. Geologic Background Geologically, the Valley and Ridge is very different than the Blue Ridge Mountain province, even though the neighboring provinces were shaped during many of the same mountain building episodes and both rise to above-average elevations. The Valley and Ridge rocks are almost entirely sedimentary and were initially deposited during the Paleozoic era. During this time, an ocean covered much of eastern North America.  You can find many marine fossils in the province as evidence, including brachiopods, crinoids and trilobites. This ocean, along with the erosion of bordering landmasses, generated large amounts of sedimentary rock.   The ocean eventually came to a close in the Alleghanian orogeny, as the North American and African protocontinents came together to form Pangea. As the continents collided, the sediment and rock stuck between them had nowhere to go. It was put under stress from the approaching landmass and folded into great anticlines and synclines. These layers were then thrust up to 200 miles westward.   Since mountain building ceased around 200 million years ago, the rocks have eroded to form the present-day landscape. Harder, more erosion-resistant sedimentary rocks like sandstone and conglomerate cap the tops of ridges, while softer rocks like limestone, dolomite and shale have eroded into valleys.  The folds decrease in deformation moving west until they die out underneath the Appalachian Plateau.   Places to See Natural Chimney Park, Virginia - These towering rock structures, reaching heights of 120 feet, are the result of karst topography. Hard columns of limestone rock were deposited during the Cambrian and withstood the test of time as the surrounding rock eroded away.   Folds and faults of Georgia - Dramatic anticlines and synclines can be seen within roadcuts throughout the entire Valley and Ridge, and Georgia is no exception. Check out Taylor Ridge, Rockmart slate folds and the Rising Fawn thrust fault.   Spruce Knob, West Virginia - At 4,863 feet, Spruce Knob is the highest point in West Virginia, the Allegheny Mountains and the entire Valley and Ridge province.   Cumberland Gap, Virginia, Tennessee and Kentucky - Often referenced in folk and blues music, the Cumberland Gap is a natural pass through the Cumberland Mountains. Daniel Boone first marked this trail in 1775, and it served as the gateway to the West into the 20th century.   Horseshoe Curve, Pennsylvania - Although more of a historical or cultural landmark, Horseshoe Curve is a great example of geologys influence on civilization and transportation. The imposing Allegheny Mountains long stood as a barrier to efficient travel across the state. This engineering marvel was completed in 1854 and reduced the Philadelphia-to-Pittsburgh travel time from 4 days to 15 hours.