Coasts are dynamic environments undergoing constant change, they can both erode and accrete. We have mapped horizontal erosion, which is wearing back of the land, and horizontal accretion, which is seaward movement of the land, also known as progradation. Erosion causes coastal cliffs and beaches to move landward over time, whereas accretion occurs when sand or gravel is deposited along the coast allowing beaches to build up and grow seaward (prograde). Sediment can be deposited by waves and currents or brought to the coast by rivers and landslides.