overburden

(ōˌvər-bûrˈdn)

1. To burden with too much weight; overload.
2. To subject to an excessive burden or strain; overtax.

1. An excessive burden; an overload.
2. Geology
   a. Material overlying a useful mineral deposit.
   b. Sedimentary rock covering older crystalline layers.
3. Archaeology A sterile stratum overlying a stratum bearing traces of the culture being studied.