How the Process Works
Longshore drift occurs as a result of wave action. Waves approaching the shore carry lots of energy. As these waves approach the beach, the base of the wave collides with the seabed. As a result, the waves topple and break apart.
In the process, they pick up sediment The sea bed determines what size particles will be picked up by the waves. Particle size is also determined by the force of the wave and how powerful it is. Once the wave approaches the shore, sediment is carried up the shore in angles by the waves. This is known as swash.
The wave then recedes back down the beach at an angle perpendicular (90 degrees) to the shore. This is known as backwash and as the wave backwashes, it carries sediment back down. Backwash occurs due to gravity and the resulting waves follow a different path down the beach as compared to when on their way up.
The entire process occurs in a somewhat zig-zag pattern. Material transported down the shoreline is carried by weak currents, known as longshore currents, that are produced as a result of the breaking waves.
The direction of the waves is dependent on the prevailing winds. The winds determine what path the waves will take and how the material will be swashed as well as back washed along the shore.
For example, if the winds are traveling in a north-west direction, then the waves will follow the same path picking up the sediment from the north-west and transporting it down the shoreline. Littoral drift is responsible for the formation of many natural features such as spits, barriers and tidal inlets. Let us briefly look at how these features are formed as a result.