A beach is a strip of land along the edge of water, where wind and waves continuously wear away and deposit materials. These materials include sand, gravel, shells, marine organisms and seaweed. Beaches often feature a variety of vegetation, including dunes and sea grasses. They are also home to a variety of animals, such as crabs, birds and sea turtles.
Most beaches are found in areas that are part of the ocean, but they can also be located near lakes and rivers. The primary characteristic of a beach is the accumulation of loose, fine-grained material like sand or pebbles along the water’s edge. This is called sediment deposition. In addition, a beach is generally characterized by a gentle slope toward the water.
A number of factors contribute to the formation of beaches, but they are generally formed through weathering and erosion. The constant action of waves beating against a rocky cliff can cause rocks to come loose, and even huge boulders may be worn down to tiny grains of sand. These sand grains are then carried by currents and winds to the coastline, where they build up over time.
The type of wave that reaches the shoreline plays an important role in the formation of beaches as well. Constructive waves, which allow the sediment to settle and compact between each wave, help to prevent future erosion. However, destructive waves keep the particles in a nearly constant state of suspension in the water and can increase the speed at which sand is lost from a beach.
Many beaches are polluted with garbage, raw sewage and other waste from urban areas, which can contain bacteria and other dangerous chemicals. This pollution often washes ashore after strong storms. In some cases, it can take days or even weeks for the toxic waters to wash out to sea.
In addition to debris, some beaches are also polluted with nutrients that are washed in from inland sources. These nutrients can encourage the growth of plants that are invasive and can damage coastal ecosystems. In addition, they can also harm the health of people and other creatures that use the beach for recreation. This is why many governments and environmental organizations regulate the use of fertilizers and pesticides on beaches. In some cases, these restrictions are based on the location of sensitive wildlife habitats that can be damaged by these chemicals. Other times, they are based on the potential impacts to human populations. This is especially true in areas where tourism and recreational activities are popular on the beach.