Gaps in rock layers that develop when agents of erosion remove existing rock layers are known as unconformities.
Each unconformity represents a missing layer of rock or a gap in the rock layers. It is a contact between sedimentary rocks which are different in age or between sedimentary rocks and older, eroded igneous or metamorphic rocks.
Unconformities represents gaps in geologic record, periods of time which are not represented by any rocks. Unconformities may take three different forms, namely, the disconformities, angular unconformities and the nonconformities.
