- a natural junction, running parallel to the E coast of the US, between the hard rocks of the Appalachians and the softer coastal plain, along which rivers form falls and rapids
Collins Concise English Dictionary © HarperCollins Publishers::
Fall Line n
fall′ line′,
- Geography, Place Namesan imaginary line, marked by waterfalls and rapids, where rivers descend abruptly from an upland to a lowland.
- Geography, Place Names(caps.) [Eastern U.S.]the imaginary line between the Piedmont and the Atlantic coastal plain.
- Sport[Skiing.]the path of natural descent from one point on a slope to another.
- 1880–85, American.