ABSTRACT
SEDIMENT TRANSPORT Clastic sediment is mostly rolled along the seabed where it is reached by wave motion in shallow water. Beaches are formed by sand deposition where wave upwash (swash) is greater than the backwash due to water soaking down into the porous sand. Shingle storm beach forms higher up by larger waves. Coastal dunes are of beach sand blown inland by wind. Sediment washed into deeper water is deposited below wave influence, as wave-built terrace or offshore bar. Longshore drift is due to oblique upwash of impacting waves, then backwash directly down beach slope – always away from waves arriving with greatest fetch.
