noun
: the succession of stages through which a newly uplifted land mass must pass before it is worn down to a peneplain or a surface near sea level including juvenile stages in which the original surface is sharply cut by canyons, mature stages in which the original surface may disappear and the topography be characterized by high steep hills and fairly open valleys, and old-age stages in which the land is so worn down that the streams meander sluggishly across a lowland