A beach is a narrow, gently sloping strip of sand, gravel, pebbles, and rock that extends landward from a body of water. This may include a lagoon, bay, or an ocean. Beaches are created by the waves, tides, and currents that wash away debris and sediment from the sea. Some of the material eroded by the ocean may include shells, seaweed, and seashell fragments.
Some beaches are rocky and barren. Others are covered with vegetation, including trees and shrubs. The color of the beach depends on its mineral content. Red beaches come from volcanic rocks rich in iron. Green beaches contain minerals such as olivine. These beaches are common in Hawaii and Bermuda.
In some locations, a beach is called a foredune, because it is a foredune that forms in front of a sand beach. This is because the sand is blown to the back of the beach by the sea wind. Dunes may bury buildings, trees, or soil that is fertile. They are also home to birds and other wildlife. Sea turtles lay their eggs on ocean beaches.
Sands on beaches in temperate latitudes are made from quartz and feldspar. In tropical areas, sands are mainly made of calcium carbonate. Coral reefs are the main source of beach sand. However, some of it can be derived from seaweed, local bedrock, or ocean debris.
Beaches are generally protected from storm surges by a series of barriers, such as a lagoon or bay. When a strong cyclonic storm hits, it produces a high surge of water that can damage beaches. Large storms can erode beaches from both shores. Ocean currents can transport debris and sediment long distances, including inland.
Beaches can be found in many parts of the world, including the Mediterranean, the Black Sea, the Caspian Sea, the Gulf of Mexico, and Hawaii. There are two basic types of beaches, and the exact contour and form of a beach are dependent on a number of factors. Most beaches are narrow, extending landward to a point of change in material. Depending on the type of sediment, the beach can be an active beach, a sand beach, or a barrier beach.
An active beach is one that varies greatly in form and dimension depending on wave parameters, the distribution of sediments, and the morphology of the beach berm. It is also known as a beach terrace. Other characteristics of an active beach are the presence of a beach berm, beach ridges, and beach cusps.
Barrier-island beaches are composed of narrow sand islands detached from the mainland by a bay, lagoon, or a sand ridge. They are particularly vulnerable to storms. As a result, a large cyclonic storm can redistribute sediment and debris and destroy beaches in moderate to low latitudes.
Fossil beaches are coastlines that are thousands of years old. Beaches in the Arctic and Antarctic are frozen almost all year. Beaches in Hawaii are green or black. Tropical beaches are sandy, but they can be cold.