The beaches are extensions of the surface almost flat, with gentle slopes that are on the banks of rivers, seas or oceans. They are formed by sediments deposited by the waves or currents of water, which can be thick materials (boulders, gravel, etc.) Fine sediments (sand, silt) or a combination thereof. The characteristics of the sediment depends on its origin may come from the channel or the banks of the river, the bottom of the sea or ocean, or on the coast, where water, wind and other agents moving structure and erode the sediments to the beaches . The area of the shore has a gentle relief and is made up of fine sediments, whereas the area behind the beach, which only achieved by large waves during storms, it is generally steeper and the constituent materials are larger.
The waves can be destructive or constructive. The first came in force, eroding the coastline and move sediment from the beach to the sea. By contrast, the second break gently and carry materials to the shore.
Upon reaching the beach, the waves of translation leading to coastal currents and undertow.