The swash action can move beach materials up and down the beach, which results in the cross-shore sediment exchange.
2.
Beach materials come from erosion of rocks offshore, as well as from headland erosion and slumping producing deposits of scree.
3.
Beach material does not get washed away because of these groynes but can cause damage to other parts of the coast.
4.
However, there is a corresponding loss of beach material on the updrift side, requiring that another groyne to be built there.
5.
The cliff base is protected by the beach material held behind the barriers, as the revetments trap some of the material.
6.
However, the return of water ( backwash ) is at right angles to the beach, resulting in the net movement of beach material laterally.
7.
In other circumstances, spits are formed when long shore drift moves beach material down the beach until the coastline makes an abrupt change in direction, leading to the beach material'spilling over'the corner to create a protrusion.
8.
In other circumstances, spits are formed when long shore drift moves beach material down the beach until the coastline makes an abrupt change in direction, leading to the beach material'spilling over'the corner to create a protrusion.
9.
The majority of cuspate forelands are formed over a coastline that juts out into the sea at enough of an angle to allow the drifting beach material to'spill over'as a result of long shore drift in both directions.
10.
Beach material builds up on the downdrift side, where littoral drift is predominantly in one direction, creating a wider and a more plentiful beach, therefore enhancing the protection for the coast because the sand material filters and absorbs the wave energy.
