Five Weathering Processes in the Formation of Beaches

Longshore Drift

• Longshore drift moves sand and sediment along beaches. This happens because waves hit beaches at a slight angle and pick up sediment along the way. The waves move back from the beach diagonally and drop the sand and sediment as they move. This gradual back-and-forth movement shifts large quantities of sand along beaches. On some beaches, municipal or county authorities install artificial spits or bars to prevent too much sand from moving away.

Wave Action

• The force of waves against coastal rocks helps to form beaches. The constant crashing of waves on the rocks gradually breaks them up, forming sediment which, after time, is rubbed smooth by wave motion to form tiny sand particles. In stormy areas lashed by wind and rain, this process will accelerate. Coastal rock erodes at different rates, depending on the type of rock. Soft chalks and limestones erode much more quickly than hard volcanic rocks, such as granite.

Deposition

• Rain falling on land gradually washes into rivers that run into seas and oceans. Large quantities of mud and sediment wash into oceans and onto beaches every year. This process is particularly noticeable around large river estuaries, where beach-goers may see extensive mud flats.

Tidal Action

• The tides of the ocean make a big impact on beaches. Tides rise and fall every day and the change of water level helps to erode beaches, moving large quantities of sediment and sand. Tidal action will also break down coastal rocks, adding to beach formation.

Sand Bar Formation

• Another common beach feature is the sand bar, sometimes known as a spit. These form when beach sand and sediment is deposited off the coast by longshore drift, forming a large structure alongside the original beach. Sand bars sometimes form lagoons or permanent islands.