Beach ridge

A beach ridge is a wave-swept or wave-deposited ridge of sand and other beach sediment running parallel to a shoreline. It builds up through the combined action of littoral transport, which moves sediment generally along the shore, longshore transport, which moves it parallel to the coast, and on-offshore transport, which moves it perpendicular to the coast, with the ridge height depending on the size and energy of the waves that built it. A beach ridge can be capped with sand dunes, and it can become stranded inland when water levels fall or the land rises, or conversely be submerged and worn down again if water levels rise; in the Netherlands, isolated beach ridges provided the only dry routes across wet peatland and became the sites of towns such as The Hague, Haarlem and Alkmaar.