Rather than a top-down origin, a pediplain is assumed to have formed by the lateral cutting back of a cliff or scarp so that a steep slope becomes progressively gentler. The origin proposed for an etchplain is by deep weathering (common in the humid tropics to depths of a hundred meters...
OPOSSUM CREEK DRAINAGE BASIN, CUMBERLAND COUNTY, PA: REMNANTS OF A PENEPLAIN, PEDIPLAIN, OR SIMPLE EROSION?SEVON, W.D