Spit

A spit is a narrow ridge of sand or shingle attached to the coast at one end and extending into the sea. Longshore drift supplies its sediment. Waves approach the beach at an angle, so swash moves material diagonally up the shore; backwash carries it down the beach slope.

To understand a spit, first follow the sediment. Longshore drift moves sediment along the coast: waves approaching at an angle carry material diagonally up the beach in the swash, while backwash carries it down the slope. Repetition produces a net movement along the shore.

Waves and currents also move sediment and deposit it elsewhere, building beaches, spits and bars. Sediment includes loose sand, shingle and finer particles. It can reach the coast from eroding cliffs, rivers or neighbouring stretches of shoreline.

Erosion removes material from the coast; deposition builds features from transported material. These processes are connected: sediment released by erosion can later help build a beach or spit.