Longshore drift is simply the sediment moved by the longshore current. Longshore currents will tend to replenish beach sediments and repair storm damage. Ocean currents move sand along the coast in a natural process known as longshore drift. Rip currents can occur wherever there is strong longshore variability in wave breaking. In the ocean, groynes create beaches or prevent them being washed away by longshore drift. Sediment is transported along the coast in the direction of the prevailing current (longshore drift). This sediment then enters the coastal system and is transported by longshore drift. During storms, sea walls help longshore drift. It is gradually extending westwards due to wave action and longshore drift. A baymouth bar is a depositional feature as a result of longshore drift. Most revetments do not significantly interfere with transport of longshore drift. The island is built from sand moving south via longshore drift building the island's length. There are numerous calculations that take into consideration the factors that produce longshore drift. Bridges left the sea for longshore work in San Francisco in 1922. In 1960, Westport purchased Longshore Club Park.