The Atlantic Seaboard Fall Line runs through Maryland on its way from New Jersey toward Georgia. It is generally a cliff marking a boundary between two geologic formations, the Piedmont and the Atlantic coastal plain. [1, 2]
You can see waterfalls along this line, including at Elkton, Perryville, Baltimore, Elkridge, Laurel, and Washington. Historically, boats approaching from downriver would have to stop at the waterfalls, and either terminate their journey or be ported over land to continue upriver. A number of towns and cities grew near these falls, taking advantage of water power for mills, and becoming nexuses in transportation networks. U.S. Route 1 links many of the fall line cities. [3, 4]
1. "A Tapestry of Time and Terrain: The Fall Line", U.S. Geological Survey, [ tapestry.usgs.gov/features/14fallline.html ], accessed 2013-07-05.
2. "A Brief Description of the Geology of Maryland", Maryland Geological Survey, [ www.mgs.md.gov/esic/brochures/mdgeology.html ], accessed 2013-07-05.
3. "Altantic Seaboard fall line", Wikipedia, [ en.wikipedia.org/wiki/Atlantic_Seaboard_fall_line ], accessed 2013-07-05.
4. "Highroad Guide to the Chesapeake Bay", by Deane Winegar, 1998, [ books.google.com/books ], accessed 2013-07-30. See the section titled "Fall Lines" on page 5.
5. "Disequilibrium profile of the Potomac River near Washington, D.C. – A result of lowered base level or Quaternary tectonics along the Fall Line?", John C. Reed, Jr., in Geology, v. 9, no. 10, p. 445-450, The Geological Society of America, [ geology.gsapubs.org/content/9/10/445.short ], accessed 2013-07-30.