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Beach

earth science Maturity 11-13 Next article →

A beach is a landform located alongside a body of water, such as an ocean, sea, lake, or river.

Key West Beach Access
Key West Beach Access

It is composed of loose particles known as sediments. These particles can be made of rock, such as sand, gravel, shingle, or pebbles. They can also be biological, meaning they come from living things like mollusk shells or coralline algae.

00065 sand collage
00065 sand collage

Beaches are important geological units and small systems where materials move onshore, offshore, or along the shore. They serve as vital biomes for marine biodiversity, providing essential breeding grounds for sea turtles and nesting areas for seabirds or penguins.

Kemp's Ridley sea turtle nesting
Kemp's Ridley sea turtle nesting

The shape and structure of a beach are defined by its profile. A key part of this is the beach berm, which is a nearly horizontal deposit of material that forms the active shoreline. The berm has a crest, or top, and a face, which is the slope leading down to the water. Below the face, there may be a trough and several longshore bars. These bars are underwater embankments that form where waves first begin to break.

Beach zones
Beach zones

At the highest reach of the daily tide, a wrack line forms where organic and inorganic debris is deposited by wave action. If the particles are small enough, wind can move them inland from the berm to create coastal dunes.

Waves are the primary force that shapes a beach through two different processes. Constructive waves have a long period between their crests. This allows the water to recede and the sediment to settle and compact before the next wave arrives. These waves move material up the beach toward the berm. In contrast, destructive waves have a short period between crests. These high-energy waves keep sediment in suspension, making it easier for waves to carry material away.

Summer versus winter beach
Summer versus winter beach

This process can result in a gently sloping beach on sandy shores or a steep beach on pebble and shingle shores. On pebble beaches, the large particle size allows water to percolate through quickly, which reduces the power of the backwash.

Seasonal changes also significantly alter the beach profile. In temperate areas, summer is often characterized by calmer seas and longer periods between wave crests. During this season, the beach profile is typically higher because gentle waves transport sediment toward the berm. Conversely, the storm season, or winter, brings higher energy waves that break in quick succession. These waves mobilize sediment from the shallows and carry it out to sea to form longshore bars. This seasonal movement means that sand is effectively stored offshore during the winter months.

The composition of beach sediment depends on local geology and the energy of the environment. White sand beaches often consist of quartz or eroded limestone, which reflects sunlight. Tropical white sand is frequently composed of calcium carbonate from the skeletons of marine organisms.

00065 sand collage
00065 sand collage

Some beaches, like those in Bermuda, feature pink coral sand due to coral fragments. The energy of the water also dictates particle size. Coastlines facing energetic wind and wave systems usually only hold large rocks, as smaller particles are carried away. Protected areas allow finer sediments, like clay and mud, to settle and form mud flats.

Human activity and climate change are currently causing rapid alterations to beach geologies. Many sandy beaches are used for recreation and tourism, leading to the construction of hotels, resorts, and infrastructure. However, poor construction practices on dunes and coastlines can damage these systems. Human forces also contribute to water and plastic pollution. Furthermore, climate change is making natural forces like extreme weather events more intense. Some estimates suggest that as much as 50 percent of the Earth's sandy beaches could disappear by the year 2100 due to sea level rise.

To manage these changes, different coastal strategies are used. Some practices focus on preserving or restoring natural processes, while others use beach nourishment to actively restore sand to a coastline. These efforts are critical because beaches protect inland ecosystems and human infrastructure from extreme weather.

Summer versus winter beach
Summer versus winter beach

Whether they are developed for tourism or remain as "wild" undeveloped beaches, these landforms are deeply connected to the health of the global marine environment and the stability of our coastlines.

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🖼️ Images & Media (11)
File:Beach zones.png
Beach zones.png
File:Summer versus winter beach.png
Summer versus winter beach.png
File:00065 sand collage.jpg
00065 sand collage.jpg
File:Llandudno.jpeg
Llandudno.jpeg
File:Brighton, the front and the chain pier seen in the distance.jpg
Brighton, the front and the chain pier...
File:The promenade, Blackpool, Lancashire, England, ca. 1898.jpg
The promenade, Blackpool, Lancashire,...
File:Monte Carlo Casino seaside facade before 1878 - Bonillo 2004 p113.jpg
Monte Carlo Casino seaside facade before...
File:The Queen Mary's Army Auxiliary Corps during the First World War, France Q11512.jpg
The Queen Mary's Army Auxiliary Corps...
File:Key West Beach Access.JPG
Key West Beach Access.JPG
File:Romantic_beach_entrance.jpg
Romantic_beach_entrance.jpg
File:Kemp's Ridley sea turtle nesting.JPG
Kemp's Ridley sea turtle nesting.JPG
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