Rocks erode and sediment is deposited, and No sediment is deposited over a long time.
Explanation:
The most common reason for the formation of uncomformity is erosion. The times of formation of the rocks above and below the uncomformity are different when no sediment is deposited over a long time.
The rock above the uncomformity are younger than the rocks below the uncomformity. Types of uncomformity are angular uncomformity, discomformity and non comformity.
In angular discomformity horizontal sedimentary rock layers are formed above sedimentary rock layers that are in tilted position. Discomformity lies between two horizontal sedimentary rock layers. Non comformity lies between sedimentary and igneous rock layers or metamorphic rocks.
