unconformability

from The Collaborative International Dictionary of English v.0.48

Unconformability \Un`con*form`a*bil"i*ty\, n.
   1. The quality or state of being unconformable;
      unconformableness.
      [1913 Webster]

   2. (Geol.) Lack of parallelism between one series of strata
      and another, especially when due to a disturbance of the
      position of the earlier strata before the latter were
      deposited.
      [1913 Webster]