Source : Webster's Revised Unabridged Dictionary (1913)

Overburden \O`ver*bur"den\, v. t.
   To load with too great weight or too much care, etc. --Sir P.
   Sidney.

Overburden \O"ver*bur`den\, n.
   The waste which overlies good stone in a quarry. --Raymond.

Source : WordNet®

overburden
     n 1: the surface soil that must be moved away to get at coal
          seams and mineral deposits
     2: an excessive burden [syn: {overload}]
     v 1: burden with too much work or responsibility
     2: load with excessive weight