In the study of the physiography of the Appalachians, uplift and tilting of the peneplains toward the sea have been generally recognized and differential uplift resulting in folding of the erosion surfaces has been postulated by some, but, so far as the writer recalls, no one has postulated faulting of these peneplains. The writer has had opportunity to study the physiography of a large part of the Appalachians, supplemented by a study of topographic maps, and some general conclusions on the peneplains of part of Virginia and detailed physiographic descriptions of local areas in Pennsylvania, New Jersey, Maryland, and West Virginia have been published.2
In these physiographic studies a series of peneplains has been observed in the Piedmont province and another series in the Blue Ridge and Appalachian ridges, but correlation of the two series of erosion surfaces has been made with difficulty and considerable . . .