Unconformity

unconformity -- Any interruption of the continuity of a depositional sequence.
undifferentiated -- adj. Unable to distinguish between. Undifferentiated rocks: rocks for which it is not possible to specify finer age divisions.

unconformity A buried erosion surface separating two rock masses.
uniformitarianism The principle that applies to geology our assumption that the laws of nature are constant As originally ...

Angular Unconformity:
An erosional surface that separates rock units of differing dips. The rocks below the surface were deposited, deformed and eroded. The younger rocks above then accumulated upon the erosional surface.
Anthracite: ...

Unconformity A break in the sequence of sedimentary strata. Often the unconformity surface is the result of erosion. Undercut Bank Steep bank found on the inside of stream meanders.

Interface options used include a depositional surface (e.g. the two dimensional grid is deposited on the next lower surface without truncating any underlying suface) and an unconformity (e.g.

See also: Area, Sediment, Plate, Layer, Erosion