Source : Webster's Revised Unabridged Dictionary (1913)

Exfoliation \Ex*fo`li*a"tion\, n. [Cf. F. exfoliation.]
   The scaling off of a bone, a rock, or a mineral, etc.; the
   state of being exfoliated.

Source : WordNet®

exfoliation
     n 1: the peeling off in flakes or scales of bark or dead skin;
          "exfoliation is increased by sunburn"
     2: a thin flake of dead epidermis shed from the surface of the
        skin [syn: {scale}, {scurf}]