A beach is a landform that lies along the shore of a waterbody, such as an ocean or sea. It usually consists of loose particles, such as sand, gravel, or shingle. During high tide, the sea covers much of the beach and at low tide, the sea retreats.
There are many different types of beaches, and they can vary in shape and size. Some are very wide and long, while others are narrow and flat. They can also be sandy, rocky, or even muddy.
Sand is the most common material used for beaches. It can be made from sand grains (the smaller pieces of broken up sand) or from other materials, such as sandstone and gravel. The color of a beach is determined by the type of sand and by other factors, such as the color of shells that have been mixed in with it.
Most of the sand on beaches is quartz and feldspar. These minerals are light colored and translucent. Some beaches have a gray or brown color, but this is from iron-stained sand grains.
These sands are the primary source of nutrients for marine organisms. They help plants, crabs, and sea weeds grow in the sea. They can also be eaten by marine animals, including sea turtles and birds.
Beaches also act as a natural filter for runoff from coastal areas. When a large amount of runoff comes into the ocean or river, it can be polluted by bacteria and other chemicals. These chemicals can be toxic to people and wildlife.
In addition to acting as a filter, beaches also protect coastlines from erosion. The waves and tides that wash over them can erode softer rock, such as granite or limestone, which can cause the beach to recede.
The weather also plays a role in coastal erosion, as it can cause sands to dry out and become soft. For example, the island nation of Tuvalu in the South Pacific experienced rapid coastal erosion in the 1990s. Meteorologists believe that the El Nino-Southern Oscillation was responsible for this.
During heavy storms, the ocean can flood some beaches and cause them to sink in. This can be dangerous for swimmers and can also cause damage to homes.
Beaches are extremely popular places for recreation, and people can spend a lot of time there. However, they are often extremely polluted. Some of this pollution is due to drainage pipes and rivers, and it can be harmful to humans, especially after a storm.
Other sources of pollution include garbage and medical waste. These pollutants can be harmful to human health and to wildlife, including sea anemones and marine mammals such as sea lions.
The most common forms of beach erosion are caused by waves, wind, and weather systems. When waves crest, they may break the sand and create a rip current. In addition, sandstorms can be very strong, and the winds can blow for hours at a time, which can cause beaches to erode rapidly.