unconformity (geology)

In geology, an unconformity is a buried erosion surface separating two rock masses of different ages, indicating that deposition was not continuous. In general, the older layer was exposed to erosion for long interval of time before deposition of younger, but the term is used to describe any break in the sedimentary geologic record. If older rocks were deformed and not horizontal at time of subsequent erosion and deposition (without metamorphic alteration of the older rock beds), the surface of separation is called an angular unconformity. If older rocks remained essentially horizontal during erosion, the surface separating them from younger rocks is called a disconformity. Any unconformity that develops between massive igneous or metamorphic rocks exposed to erosion and then covered by sedimentary rocks is called a non-conformity.

Unconformity (Geology)

See also