The New International Encyclopædia/Piedmont Plain

PIEDMONT PLAIN. A name used in the physiography of the United States to designate that part of the Atlantic coast-plain which lies between the Appalachian highland and the low coastal plain proper. It is distinguished from the latter topographically by being more rugged and eroded with deeper river-valleys, and geologically by consisting of much older and harder rock strata. The change from the hard to the soft and recent formation is marked by a definite line of escarpments over which nearly all the Atlantic rivers fall in rapids or cataracts, and the line is known as the ‘fall line.’ The Piedmont Plain is less defined in New England than in the Southern States. It is narrowest and also approaches closest to the sea in New York, and broadens southward, being about 300 miles wide in North Carolina.