Rivers carry sediments from the land to the sea. When a river flows into the ocean, the sudden loss of velocity typically results in the formation of a delta. However, if wave action is high, a delta will not form. Instead, waves will spread the sediments along the coastline and create a beach. Waves also erode sediments from cliffs and shorelines and transport them onto beaches. Beaches are most likely to form in quiet areas along a shoreline. For example, a beach may form where water comes ashore in a protected bay. Waves continually move sand on beaches down the shoreline. Waves also move... Show more

Rivers carry sediments from the land to the sea. When a river flows into the ocean, the sudden loss of velocity typically results in the formation of a delta. However, if wave action is high, a delta will not form. Instead, waves will spread the sediments along the coastline and create a beach.

Waves also erode sediments from cliffs and shorelines and transport them onto beaches. Beaches are most likely to form in quiet areas along a shoreline. For example, a beach may form where water comes ashore in a protected bay. Waves continually move sand on beaches down the shoreline. Waves also move sand back and forth from beaches on shore to bars of sand offshore as the seasons change. In the summer, waves have lower energy, so they deposit sand on beaches. In the winter, waves have higher energy, so they carry the sand back offshore to sandbars.    
Besides beaches, several other features may be formed by wave-deposited sand. Barrier islands are islands of sand that are deposited by waves parallel to shore. They are usually just a few kilometers wide but tens of kilometers long. They tend to form along shores that are flat or gently sloping. In their natural state, barrier islands are the first defense against powerful wave erosion during hurricanes and other storms. They bear the brunt of the wave energy and help to protect shorelines from serious wave erosion. However, when barrier islands are built up with homes and other structures, they offer less protection to the shore, and the structures built on them may suffer serious wave damage.    

Two other features deposited by waves are spits and tombolos. A spit is a sand deposit that is connected to land and extends out into the water. If a spit develops a curved, hook-like end, it is called a tombolo.    

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