Longshore Sediment Movement

Longshore Sediment Movement. Littoral Drift. , Most shore bathers soon realize the back-and-forth motion of the waves breaking on the shore not only stirs the sand but also persistently carries them down the beach. This unseen force is called a “longshore or littoral current.” In general, the direction of this current along the East Coast is from north to south, although there are many variations., When combined with the turbulence of breaking waves, the current can carry large amounts of sand for miles. The sand is redeposited either at the end of an island or within “inlets,” where tidal currents move it in and out with each changing tide. Littoral drift carries an annual average of 200,000 to 300,000 cubic yards of sediment along the mid-Atlantic coast. Storms shift or strip away huge quantities of sediment, especially on steeply-sloped upper beaches. In the end, gravity transfers most beach material to the sea bed., Atlantic waves are continuously reshaping the coastal habitats along this section of the Jersey Shore. The waves strike the beach in such a way that sand and other sediments are carried both north and south. The material swept northward adds to the spit known as Sandy Hook. Material carried southward has formed a series of barrier islands, beginning with Island Beach.