Beaches are coastal landforms that are formed by the action of waves. They are made of sediment that has been deposited by waves. The resulting material can be carried by the wind or the tides and can travel long distances.
There are two main kinds of beaches: sand and shingle. They differ in their morphology and accretion. Sand beaches are often popular recreation areas. On the other hand, shingle beaches are usually shaped by wave action.
Sand dunes, also called sand dune systems, are hills of sand created by wind. When a wave strikes them, the sand is carried away and worn away. Some sand dunes are naturally worn down and others are man-made structures. These sand dunes can be shacks, changing rooms, and lifeguard posts. However, they do not last long.
The most important way in which sand is transported is by ocean currents. This means that the sand can be carried hundreds of kilometers. Ocean currents can be positive or negative. In the former, the sediment is carried to calmer regions. In the latter, the sand is deposited in coastal shallows.
In the United States, there are 80,000 miles of coastline that are subject to erosion. Many homeowners spend a lot of money protecting their homes from erosion. One example of this is the Waikiki beach in Honolulu, Hawaii. Another example is Manhattan Beach, California. As these beaches become eroded, they are often refilled with sand from other locations.
When a storm arrives, the sea waves become strong and carry large volumes of sand and other materials to the shore. This can result in rapid erosion. To combat this, people have built man-made structures to reduce the erosion. Such structures include groynes, which are a type of breakwater that enables the breaking of waves. Surfers may use these groynes to surf.
Man-made structures also affect the character of the beach. Buildings and parking lots are common in many beaches. Aside from these, the seawall and other structures are used to protect the land from wind. Also, the burning of vegetation may change the surface wind pattern. For example, if the vegetation is cleared, the wind will be more likely to move across the land instead of through it.
Other ways in which sand is moved are by bouncing or saltation. When a wave reaches the shore, it is pulled back out by the next wave. Since each wave can carry a small amount of sand, these sand particles can be distributed over a large area.
If the beach is nourished, the new sand is compacted and consolidated. This process, sometimes called dune accretion, causes a more steep profile of the beach. While this can be a desirable result, it can also create an artificial look. Consumers are unaware that these beaches are actually artificial.
Other forms of sediments can also be deposited on the beaches. For instance, there are marine organisms and coralline algae that provide a biological source of sediments.