Great Appalachian Valley
The Great Appalachian Valley, also called The Great Valley or Great Valley Region, is one of the major landform features of eastern North America. It is a gigantic trough, including a chain of valley lowlands, and the central feature of the Appalachian Mountains system. The trough stretches about from Quebec in the north to Alabama in the south and has been an important north–south route of travel since prehistoric times. 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 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