Fall line
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The fall line has meanings in both geographical features and the sport of alpine skiing.
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Geographical fall line
As a geographical feature, the fall line marks the area where an upland region (continental bedrock) and a coastal plain (coastal alluvia) meet. The fall line is typically prominent where a river crosses it, for there will usually be rapids or waterfalls. Because of these features river boats typically can not travel any farther inland. Because of the need of a port, and ready supply of water power, settlements often developed where the river crosses the fall line.
Fall lines in the United States
Along the eastern coast of the United States, the east-facing escarpment where the Piedmont of the Appalachian Rise descends steeply to the coastal plain forms a fall line over 1500 kilometers long. The fall line is a zone that may be several km wide. Geologically the fall line marks the boundary of hard metamorphosed terrane—the product of the Taconic orogeny—and the sandy, relatively flat outwash plain of the upper continental shelf, formed of unconsolidated Cretaceous and Tertiary sediments.
Since the fall line often represented the head of navigation on rivers at points like the Great Falls of the Potomac River and since falls and rapids, once tamed by flumes, provided water power for early mills, the most prominent feature of fall line settlement was the establishment of the cities along it. As the cities were linked by the early highways, U.S. Route 1 and Interstate 95 pass through many of these cities, roughly tracing the fall line.
Cities along the fall line include, from north to south:
- Lowell, Massachusetts on the Merrimack River
- Pawtucket, Rhode Island on the Blackstone River
- Troy, New York on the Hudson River
- Trenton, New Jersey on the Delaware River
- Washington, D.C./Georgetown/Alexandria on the Potomac River
- Fredericksburg, Virginia on the Rappahannock River
- Richmond, Virginia on the James River
- Petersburg, Virginia on the Appomattox River
- Roanoke Rapids, North Carolina
- Raleigh, North Carolina
- Cheraw, South Carolina on the Pee Dee River
- Columbia, South Carolina on the Congaree River
- Augusta, Georgia on the Savannah River
- Milledgeville, Georgia on the Oconee River
- Macon, Georgia on the Ocmulgee River
- Columbus, Georgia on the Chattahoochee River
- Auburn, Alabama
- Tuscaloosa, Alabama on the Black Warrior River
References
- USGS: The Fall Line: A Tapestry of Time and Terrain
- Virginia Places website: The Fall Line
- Virginia Places website: Rivers and Fall Line Cities provides a more detailed explanation of why some towns and cities along a Fall line grew and others did not.
- The Geology of Georgia
Alpine skiing fall line
In alpine skiing, a fall line refers to the line down a mountain or hill which is most directly downwards. This can be visualized as the route a ball would take if it were started rolling at the summit, and rolled to the bottom.