Waves approach the beach at an angle due to the prevailing winds. The waves carry sand and sediment down the coastline with the swash and backwash. This process is known as longshore drift. When there is a change in the direction of the coastline (e.g: at a bay) the sediment is deposited in shallower water and weaker currents. The longshore drift process of deposition continues and the sediment forms up to build new land. This is called a spit. When the wind changes direction, this can curve the end of the spit. Behind the spit is sheltered from the waves so mudflats + salt marshes form. This can be seen in Hampshire where the hurst castle spit is formed.
If the spit builds up, eventually joins up to the other headland, this becomes a coastal bar. If it joins from the headland to an island, this is called the tombolo.
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