Correct Answer - Option 1 : A surface of erosion or non-deposition as detected in a sequence of rocks
Concept:
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous.
An unconformity is a contact between two rock units in which the upper unit is usually much younger than the lower unit.
The contact is more obvious than a disconformity because the rock units are not parallel and at first appear cross‐cutting.
Note:
An angular unconformity is the contact that separates a younger, gently dipping rock unit from older underlying rocks that are tilted or deformed layered rock.
Angular unconformities generally represent a longer time hiatus than do disconformities because the underlying rock had usually been metamorphosed, uplifted, and eroded before the upper rock unit was deposited.