The Collaborative International Dictionary of English v.0.48:

Circumdenudation \Cir`cum*den`u*da"tion\, n. [Pref. circum- +
   denudation.] (Geol.)
   Denudation around or in the neighborhood of an object.
   [1913 Webster]

   Hills of circumdenudation, hills which have been produced
      by surface erosion; the elevations which have been left,
      after denudation of a mass of high ground. --Jukes.
      [1913 Webster]