unconformity

noun

un·​con·​for·​mi·​ty ˌən-kən-ˈfȯr-mə-tē 

1

a

: lack of continuity in deposition between rock strata in contact corresponding to a period of nondeposition, weathering, or erosion

b

: the surface of contact between unconformable strata

2

archaic : lack of conformity

Word History

First Known Use

circa 1600, in the meaning defined at sense 2