The movement of sand and shingle along the coast. Waves usually surge onto a beach at an oblique angle and their swash takes sediment up and along the beach. The backwash usually drains back down the beach at an angle more nearly perpendicular to the coast, taking sediment with it. Thus there is a zigzag movement of sediment along the coast. Longshore currents, initiated by waves, also move beach material along the coast. The term littoral drift is synonymous.