Shoal - Sandbars and Longshore Bars

Sandbars and Longshore Bars

This bar forms (sometimes seaward of a trough) where the waves are breaking, because the breaking waves set up a shoreward current with a compensating counter-current along the bottom. Also known as a trough bar. Sand carried by the offshore moving bottom current is deposited where the current reaches the wave break. Other longshore bars may lie further offshore, representing the break point of even larger waves, or the break point at low tide.