A beach is a narrow, gently sloping strip of land that lies along the edge of an ocean, lake, or river. Materials such as sand, pebbles, rocks, and seashell fragments cover beaches.

Most beach materials are the products of weathering and erosion. Over many years, water and wind wear away at the land. The continual action of waves beating against a rocky cliff, for example, may cause some rocks to come loose. Huge boulders can be worn down to tiny grains of sand.

Beach materials may travel long distances, carried by wind and waves. As the tide comes in, for example, it deposits ocean sediment. This sediment may contain sand, shells, seaweed, even marine organisms like crabs or sea anemones. When the tide goes out, it takes some sediment with it.

Tides and ocean currents can carry sediment a few meters or hundreds of kilometers away. Tides and currents are the main way beaches are created, changed, and even destroyed, as the currents move sediment and debris from one place to another.

Beaches are constantly changing. Tides and weather can alter beaches every day, bringing new materials and taking away others.

Beaches also change seasonally. During the winter, storm winds toss sand into the air. This can sometimes erode beaches and create sandbars. Sandbars are narrow, exposed areas of sand and sediment just off the beach. During the summer, waves retrieve sand from sandbars and build the beach back up again. These seasonal changes cause beaches to be wider and have a gentle slope in the summer, and be narrower and steeper in the winter.

Beach Berms

Every beach has a beach profile. A beach profile describes the landscape of the beach, both above the water and below it. Beaches can be warm, and rich in vegetation such as palm or mangrove trees. Beaches can also be barren desert coastlines. Other beaches are cold and rocky, while beaches in the Arctic and Antarctic are frozen almost all year.

The area above the water, including the intertidal zone, is known as the beach berm. Beach berm can include vegetation, such as trees, shrubs, or grasses. The most familiar characteristic of a beach berm is its type of sand or rock.

Sandy
Most beach sand comes from several different sources. Some sand may be eroded bits of a rocky reef just offshore. Others may be eroded rock from nearby cliffs. Pensacola Beach, in the U.S. state of Florida, for instance, has white, sandy beaches. Some sand is eroded from rocks and minerals in the Gulf of Mexico. Most sand, however, is made of tiny particles of weathered quartz from the Appalachian Mountains, hundreds of kilometers away.

The sandy beaches surrounding Chameis Bay, Namibia, are also full of quartz and seashells. However, the beaches of Chameis Bay contain another type of rock—diamonds. Mining companies have dug mines both on the beach and offshore to excavate these precious stones. Other gems, such as sapphires, emeralds, and garnets, are present on many beaches throughout the world, as tiny grains of sand.

Rocky
Some beach berms are not sandy at all. They are covered with flat pebbles called shingles or rounded rocks known as cobbles. Such beaches are common along the coasts of the British Isles. Hastings Beach, a shingle beach on the southern coast of England, has been a dock for fishing boats for more than a thousand years.

A storm beach is a type of shingle beach that is often hit by heavy storms. Strong waves and winds batter storm beaches into narrow, steep landforms. The shingles on storm beaches are usually small near the water and large at the highest elevation.

Other types of beaches
Some beaches, called barrier beaches, protect the mainland from the battering of ocean waves. These beaches may lie at the heads of islands called barrier islands. Many barrier beaches and barrier islands stretch along the Atlantic and Gulf coasts of the United States. These narrow beaches form barriers between the open ocean and protected harbors, lagoons, and sounds.

Beaches near rivers are often muddy or soft. Soil and sediment from the river is carried to the river’s mouth, sometimes creating a fertile beach. Hoi An, Vietnam, is an ancient town that sits on the estuary of the Thu Bon River and the South China Sea. Hoi An’s soft beaches serve as resort and tourist centers.

Beach berms can be many different colors. Coral beaches, common on islands in the Caribbean Sea, are white and powdery. They are made from the eroded exoskeletons of tiny animals called corals. Some coral beaches, such as Harbour Island, Bahamas, actually have pink sand. The coral that created these beaches were pink or red.

On some volcanic islands, beaches are jet-black. The sand on Punaluu Beach, Hawaii, is made of basalt, or lava that flowed into the ocean and instantly cooled. As it cooled, the basalt exploded into thousands of tiny fragments. Some volcanic beaches, such as those on the South Pacific island of Guam, are green. The basalt in these beaches contained a large amount of the mineral olivine.

Threats to Beaches

Coastal Erosion
The most significant threat to beaches is natural coastal erosion. Coastal erosion is the natural process of the beach moving due to waves, storms, and wind. Beaches that experience consistent coastal erosion are said to be in retreat.

Coastal erosion can be influenced by weather systems. Beaches on the island nation of Tuvalu, in the South Pacific, were retreating very quickly in the 1990s. Meteorologists linked this to the weather system known as the El Nino-Southern Oscillation (ENSO). As ENSO events slowed, Tuvalu’s beaches began to recover.

People respond to coastal erosion in different ways. For years, coastal erosion threatened the Cape Hatteras Lighthouse, on Hatteras Island in the U.S. state of North Carolina. The Cape Hatteras Lighthouse is the tallest lighthouse in the United States. For more than 100 years, it has warned ships of the low-lying sandbars and islands known as the Outer Banks. Coastal erosion made the beach beneath the lighthouse unstable. In 2000, the entire lighthouse was moved 870 meters (2,870 feet) inland.

People also combat coastal erosion with seawalls. These large structures, built of rock, plastic, or concrete, are constructed to prevent sand and other beach material from drifting away. Residents of Sea Gate, a community in Coney Island, New York, for instance, invested in a series of seawalls to protect their homes from powerful storms and waves from the Atlantic Ocean.

However, shifting sand is a natural part of the beach ecosystem. Seawalls may protect one section of beach while leaving another with little sand. Seawalls can also increase the speed at which beaches retreat. When tides and waves hit massive seawalls instead of beaches, they bounce back to the ocean with more energy. This tidal energy causes the sand in front of a seawall to erode much more quickly than it would without the seawall.

Hurricane Sandy was a deadly storm that struck the East Coast of the United States in October 2012. Many of the seawalls of Sea Gate crumbled, and more than 25 homes were lost.

Sea Level Rise
Beaches are also threatened by sea level rise. Sea levels have been gradually rising for many years, drowning some beaches completely.

New Moore Island, for example, was a small, uninhabited island in the Bay of Bengal. Both India and Bangladesh claimed the island, which was little more than a strip of sandy beach. In March 2010, rising sea levels drowned the island completely. New Moore Island is now a sandbar.

Development
Although the natural forces of wind and water can dramatically change beaches over many years, human activity can speed up the process. Dams, which block river sediment from reaching beaches, can cause beaches to retreat. In some places, large quantities of sand have been removed from beaches for use in making concrete.

Development threatens the natural landscape of beaches. People develop homes and businesses near beaches for many reasons. Beaches are traditional tourist destinations. Places like the U.S. state of Hawaii, the island nation of Tahiti, and the islands of Greece are all economically dependent on tourism. Businesses, such as charter boat facilities, restaurants, and hotels, are built on the beach.

People also enjoy living near beaches. Beachfront property is often very highly valued. “The Hamptons” are exclusive beach communities on the eastern end of Long Island, New York. Homes in the Hamptons are some of the most expensive in the United States.

Development can crowd beaches. As more buildings and other facilities are built, beaches become narrower and narrower. The natural, seasonal movement of beach sediment is disrupted. Communities spend millions of dollars digging, or dredging, sand from one place to another in order to keep the beach the same all year.

Disappearing beaches are bad for coastal facilities. Natural beaches reduce the power of waves, wind, and storm surges. Without these barrier beaches, waves and storm surges crash directly into buildings. In 1992, a storm swept away more than 200 homes in the Hamptons. It cost the government more than $80 million to replace the barrier beach.

On Kauai, one of the islands in Hawaii, more than 70 percent of the beach is eroding, partly because of construction of seawalls and jetties, and from clearing out stream mouths. Geologists say Oahu, another Hawaiian island, has lost 25 percent of its shoreline. Tourism is the state’s main industry, so disappearing beaches are a major concern. The destruction of Hawaii’s beaches could also mean a loss of habitat for many plants and animals, some of which are already endangered.

Beach Pollution

Many beaches, especially in urban areas, are extremely polluted. Waves wash up debris from the ocean, while drainage pipes or rivers deposit waste from inland areas. Some of this waste includes sewage and other toxic chemicals. After strong storms, some beaches are closed. The amount of bacteria, raw sewage, and other toxic chemicals is hazardous to human health. Sometimes, it takes days or even weeks for the toxic waters to wash out to sea.

Beach pollution also includes garbage, such as plastic bags, cans, and other containers from picnics. Medical waste, such as needles and surgical instruments, has even washed up on beaches.

All beach pollution is harmful to wildlife. Birds may choke on small bits of plastic. Marine mammals such as sea lions may become tangled in ropes, twine, or other material. Floating plastic may prevent algae or sea plants from developing. This prevents animals that live in tide pools, such as sea anemones or sea stars, from finding nutrients.

Protecting Beaches

Reducing pollution is an important way to protect beaches. Visitors should never leave trash on the beach or throw it in the ocean.

Beachgoers should also leave wildlife alone—including birds, plants, and seaweed. Taking shells or live animals from the beach destroys the habitat.

People can also protect beaches from excess erosion. Limiting beachfront development can be an important step in protecting the natural landscape of beaches. Along some beaches, areas of vegetation known as “living shorelines” protect the beach ecosystem from erosion and protect the inland area from floods and storm surges.

In some places, machinery is used to dredge sand from the seabed just offshore and return it to the beach. Miami Beach, in the U.S. state of Florida, was restored by this method.