There are many causes of shoreline erosion. Most of them are natural. These are currents, storms, earthquakes, winds, waves, tides, and also the gradual movement of tectonic plates. Some beaches are also
destroyed by men when harbors and dams are built, or any other structures that disrupt the fragile balance of nature.
There are several different ways that the ocean can cause erosion: hydraulic action, wave pounding, abrasion, corrosion, and attrition. Hydraulic action takes place when air in a joint is suddenly compressed by a wave closing the entrance of the joint causing the joint to crack. Wave pounding is when the sheer energy of the wave hitting the cliff or rock breaks pieces off. Abrasion or corrasion is caused by waves launching seaload at the cliff. This is by far the most rapid form of shoreline erosion . Corrosion is the dissolving of rock by carbonic acid in sea water. Limestone cliffs are the most vulnerable to this kind of erosion.
Finally, attrition is where particles carried by the waves are worn down as they hit each other and the cliffs. This then makes the material easier to wash away. Sediment is transported along the coast in the direction of the current. When the incoming current amount of sediment is less than the amount being carried away, erosion occurs.
According to the Army Corps of Engineers, the most important cause of human-induced erosion is interruption of sediment sources and longshore sediment transport. Examples include the disruption of sediment sources with seawalls, revetments, and bulkheads, and the interruption of longshore sediment transport by the construction of groins and jetties.