Lably
Skip to content

Great Appalachian Valley

  • 10 min read
  • 5 chapters

Related on Lably

Through North America and Massachusetts

Geography

The Great Valley marks the eastern edge of the Ridge and Valley physiographic province. There are many regional names of the Great Valley, such as the Shenandoah Valley. From a large perspective the Great Valley can be divided into a northern section and a southern section.

Northern section

In its northern section, the Great Valley includes the Champlain Valley around Lake Champlain and the upper Richelieu River that drains it into the Saint Lawrence, the Hudson River Valley, Newburgh Valley, and Wallkill Valley, and the Kittatinny Valley, Upper Delaware River Valley, Lebanon Valley, and Cumberland Valley.

A series of mountains bounds the northern half of the Great Valley on both sides. To the east or coastward side, these include, from north to south, the Green Mountains of Vermont, the Taconic Mountains of Vermont, New York, Massachusetts, and Connecticut, the Reading Prong, which includes the New York–New Jersey Highlands, also known as the Hudson Highlands, Schunemunk Mountain, and Ramapo Mountains, and South Mountain in Pennsylvania beyond Harrisburg. There is a wide gap between the Reading Prong and South Mountain at Harrisburg, through which the Susquehanna River passes, connecting the Great Valley with the Piedmont region of southeast Pennsylvania. This gap is often considered the dividing point between the northern and southern sections of the Great Valley.

To the west or continental side, a series of more impenetrable mountain regions border the northern Great Valley. The northernmost is the Adirondack Mountains, a southern extension of the Canadian Shield, which reach the valley along the shores of Lake Champlain and Lake George. To their south, beyond the Mohawk Valley and Albany, New York, the Catskill Mountains, which form the northeastern terminus of the Allegheny Plateau, border the valley in the form of the dramatic Catskill Escarpment, which overlooks the middle reaches of the Hudson River and Hudson Valley. Just south of the Catskills, the first folds of the Ridge-and-Valley Appalachians border the valley, in the form of a continuous ridge (heading south) and known as the Shawangunk Ridge in New York, Kittatinny Mountain in New Jersey, and Blue Mountain in Pennsylvania. This long ridge is broken by several narrow and dramatic gaps, known as wind and water gaps, including Culver's Gap in New Jersey, the Delaware Water Gap, where the Delaware River passes into the Lehigh Valley along the border between New Jersey and Pennsylvania, and many gaps in Pennsylvania, including the Pennsylvania Wind Gap, the Lehigh River Gap north of Allentown, the Schuylkill River Gap, the Swatara Gap, the Susquehanna River Gap, and others.

Southern section

In its southern section, the Great Valley is bounded to the east by the Blue Ridge Mountains, which extend north into Maryland and Pennsylvania as South Mountain. Regional names of the southern Great Valley include Hagerstown Valley in Maryland, Winchester Valley, and Shenandoah Valley in Virginia and West Virginia, the upper valley of the James River, Roanoke Valley, and New River Valley in Virginia, the Holston River Valley in Virginia and Tennessee, and the East Tennessee Valley extending from Virginia through Tennessee to Alabama. The Coosa River Valley is often considered the southernmost part of the Great Valley. These southern portions of the Great Valley are sometimes grouped into two parts, the Valley of Virginia and the Tennessee Valley.

The southern Great Valley is bounded on the east by the Blue Ridge physiographic province, which includes, from north to south, South Mountain in Pennsylvania and Maryland, the Blue Ridge of Virginia, Holston Mountain in Tennessee, and the Unaka Range and the Great Smoky Mountains of Tennessee and North Carolina. A gap in these mountains exists near Roanoke, Virginia. Other gaps of note in the Blue Ridge of Virginia, connecting the Piedmont region with the Great Valley, include Thornton Gap, Swift Run Gap, and Rockfish Gap.

Another series of mountains bounds the southern Great Valley to the west, including North Mountain and Great North Mountain, the Allegheny Front, Powell Mountain, the Cumberland Mountains, Walden Ridge, and the Cumberland Plateau. The Cumberland Gap connects the Great Valley region with Kentucky and Tennessee lands to the west. Massanutten Mountain lies in the middle of the Valley of Virginia portion of the Great Valley. The Valley of Virginia is a region of karst, with sinkholes and caverns.

Climate

The climate of the Great Valley is generally Warm- or Hot-summer Humid continental in the northern third and Humid subtropical from Pennsylvania southward. The first weather box is from the temperate portion and the second subtropical portion of the valley.

Sign in to keep reading

4 more chapters are free with a Lably account.

More in Earth science