the contact surface between younger and older rocks representing a discontinuity in the geological record. Most commonly it represents an erosional surface
unconformity in American English
(ˌʌnkənˈfɔrməti)
nounWord forms: pluralˌunconˈformities
1.
a lack of conformity; inconsistency; incongruity
2. Geology
a.
a break in the continuity of rock strata in contact, separating younger from older rocks and usually resulting from erosion of the surface of the older bed before the younger bed was laid down