Category Seashores

WHICH IS THE LONGEST NATURAL SAND BEACH?

Cox’s Bazar in Bangladesh is the world’s longest natural sea beach. This beach distinguishes being the world’s longest ‘natural sea’ beach, stretching across 93 miles. It’s an exciting place that is one of the most popular tourist attractions in Bangladesh but remains relatively little known amongst tourists since Bangladesh is not considered a top destination for the average family.

The people who go here will find three different spots to enjoy: Laboni Beach, the main beach close to town, Humchari, which is loved for its waterfalls, and Inani Beach, which is favoured for suntanning. You may hear people here calling the beach Panowa; the term means ‘little flower’ and is the nickname that locals know the place by.

Credit: BEST TOPPERS

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HOW ARE COASTS FORMED?

When waves, tidal waves in particular, hit land, the force of water has the power to break and crush rocks and to erode the soil. But they also bring in seashells, seaweed, other organic matter and debris from the sea, which all gets mixed and deposited among the crushed rocks to shape the coastline. Coasts are formed over hundreds of years and can be quite changeable, changing with time as tidal waves constantly crush, erode, wash away, bring in and deposit materials.

The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the ocean or a lake.

Geologists classify coasts on the basis of tidal range into macrotidal coasts with a tidal range greater than 4 meters (13 feet); mesotidal coasts with a tidal range of 2 to 4 meters (7 to 13 feet); and microtidal coasts with a tidal range of less than 2 meters (7 feet). The distinction between macrotidal and mesotidal coasts is more important. Macrotidal coasts lack barrier islands and lagoons, and are characterized by funnel-shaped estuaries containing sand ridges aligned with tidal currents. Wave action is much more important for determining bedforms of sediments deposited along mesotidal and microtidal coasts than in macrotidal coasts

Waves erode coastline as they break on shore releasing their energy; the larger the wave the more energy it releases and the more sediment it moves. Coastlines with longer shores have more room for the waves to disperse their energy, while coasts with cliffs and short shore faces give little room for the wave energy to be dispersed. In these areas, the wave energy breaking against the cliffs is higher, and air and water are compressed into cracks in the rock, forcing the rock apart, breaking it down. Sediment deposited by waves comes from eroded cliff faces and is moved along the coastline by the waves. This forms an abrasion or cliffed coast.

Credit: Wikipedia

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HOW ARE WAVES FORMED?

When sunlight enters Earth’s atmosphere, the energy from the Sun heats up the air. This hot air expands and rises, creating space under it for cooler air to rush in. This movement causes winds. Winds that blow over the surface of ocean water transfer energy to the water, setting off ripples. As these ripples get bigger, they become waves.

The ocean is in constant motion. Waves form as a result of the water’s motion, gravitational forces, and winds. The most common waves we see are created by wind. However other waves include those created by gravitational forces (e.g. tidal waves) and those created by underwater disturbances, such as earthquakes (e.g. tsunamis).

There are three main factors that affect wave formation: wind velocity, fetch, and duration. Wind velocity is the speed of the wind, fetch is the distance over the water that the wind can blow uninterrupted (which can be huge distances out at sea), and duration is the amount of time the wind blows over that patch of water. The greater the wind velocity, the longer the fetch, and the greater duration the wind blows, then the more energy is converted to waves and the bigger the waves. However, if wind speed is slow, the resulting waves will be small, regardless of the fetch or duration. It takes all three factors acting together to create big waves.

Waves often result from storms, which tend to move across the ocean with the prevailing winds. So although a storm might only have 500 nautical miles (nm) of fetch, the storm can travel greater distances, say 1,000 nm, creating a travelling fetch of more than 1,000 nm.

Credit: UBC EOAS

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HOW IS A ROCK ARCH CREATED?

When a high, rocky outcrop juts out into the water, the crashing of waves over the years erodes the base. If the layer of rock higher up stays intact as the base is worn through, a natural rock arch is carved out.

Most people understand that erosion plays an important role in creating arches and bridges. A natural rock arch is formed by erosion. There are two types of erosive forces that account for most arches and bridges – weather erosion and water erosion.

If a crack forms in the soft layers of a sandstone fin, it allows wind to penetrate into the rock. In the desert, winds are common, and they carry lots of sand – kind of like a natural sandblaster – this can cause the cracks to widen. Acidic rain can accumulate in these cracks, chemically weakening the rock. Then, freezing and thawing frosts can cause fractured sections of rock to break off. With enough time, the constant cycle of wind, ice and rain will form an arch. This is weather erosion, and most arches and bridges throughout the world were formed this way.

Water erosion relies, as the name suggests, almost entirely on running water to create arches and bridges. Streams and rivers may eventually cut through a fin of sandstone (this is how Rainbow Bridge was formed) or acidic rain-water might pool in depressions and create an arch from above (Double Arch in Arches National Park is the perfect example of this).

Credit: NATURAL UNIVERSAL SECRETS

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WHAT IS A SHINGLE BEACH?

When stone, pebbles and small rocks are deposited along the coast, they create a porous layer that is not as tightly packed together as sand is. These are shingle beaches. Common to New Zealand, Japan and the United Kingdom, shingle beaches support little vegetation and mostly have lichen-covered rocks.

The term shingle beach refers to a beach along any body of water that is made up of stones, pebbles, and other small rocks. These materials, also known as shingles, may vary in size from 2 to 200 millimeters and can also be mixed with other sediments, like sand or silt. Shingle beaches are primarily characterized by a steep profile, which means the area further inland sits at a higher elevation than the section of the beach found along the water. These beaches are located along a number of geological formations, including spits, barrier islands, and pocket beaches. Since the stones and pebbles that make up these beaches do not fit tightly together, they create a rather porous environment. These large pores prevent the beach from retaining any significant amount of water, although they also prevent evaporation in the soil below. Many shingle beaches can be found in New Zealand, Japan, and the United Kingdom.

Geologists have linked the formation of many shingle beaches to areas around the world that were subjected to glaciation during the Pleistocene era. These areas tend to be located at higher latitudes, and glaciers brought with them rocks and pebbles that were deposited on the shorelines. Sometimes the rocks and pebbles on shingle beaches are deposited by rivers that empty into the ocean. Additionally, shingle beaches may be formed from intense wave activity that erodes larger pieces of rock located further inland. Over time, continued wave activity carries these large pieces of sediment onto the shores, depositing the biggest pieces further from the water and at higher elevations. The composition of these beaches works to decrease the strength of the tide as it moves back out to the ocean.

Credit: World Atlas

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WHAT IS A COAST?

Land that runs along a sea or ocean is called a coast. The edge of the land where it meets the water is called the coastline. Coasts can be wide swathes of soft, sandy beaches, narrow, rocky stretches or sheer cliff faces. Coastlines are given shape by waves, currents and tides. They are ever changing and form an important and unique environment.

If you’ve ever been to the beach, you’ve been on a coast. The coast is the land along a sea. The boundary of a coast, where land meets water, is called the coastline.

Waves, tides, and currents help create coastlines. When waves crash onto shore, they wear away at, or erode, the land. But they also leave behind little parts of the sea, such as shells, sand dollars, seaweeds, and hermit crabs. Sometimes these objects end up as more permanent parts of the coastline.

Coastal changes can take hundreds of years. The way coasts are formed depends a lot on what kind of material is in the land and water. The harder the material in the land, the harder it is to erode. Coastlines of granite, a hard rock, stay pretty stable for centuries. Sugarloaf Mountain, on the coast of Rio de Janeiro, Brazil, is made mostly of granite and quartz. It has been a landmark for centuries.

Tides, the rise and fall of the ocean, affect where sediment and other objects are deposited on the coast. The water slowly rises up over the shore and then slowly falls back again, leaving material behind. In places with a large tidal range (the area between high tide and low tide,) waves deposit material such as shells and hermit crabs farther inland. Areas with a low tidal range have smaller waves that leave material closer to shore.

Credit:  National Geographic Society

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Why have beach sands different colors?

Sand is basically the small particles of eroded larger rocks. The erosion is caused by several factors, including water and wind. Depending on the geography, the composition and colours of the sand vary. For instance, beach sand could be lighter because of calcium carbonate desposits from shells and skeletons of marine creatures. Meanwhile, desert sand comprises fine, light-weight particles that have been brought in by wind. River sand is likely to be coarse, containing even bright-coloured stones.

On some beaches, sand grain size composition varies with distance from the water. A greater proportion of finer, smaller sand grains may be pushed higher up the beach by waves or by wind, whereas larger, coarser grains are deposited closer to the water. However, beaches are complex and highly variable environments, and there are many areas where this distribution is not found because there are many conditions that affect sand size and distribution. Additional factors influencing sand grain size include the nearshore and offshore seafloor features, substrate type, sand source, currents, wind exposure, and coastline shape.

Beach sand can appear fairly uniform, but it is actually a complex mixture of substances with various dimensions. When scientists study sand, some qualities are particularly useful in characterizing the type of sand. These qualities include the colors, texture, and size of the sand grains and their material origins. In general, sand observations can be divided into three broad categories:

observations about size,

observations about shape, and

observations about the probable source of the sand.

 From these three characteristics scientists can learn about the physical, chemical, and biological processes at the beach from which the sand came.

The Wentworth scale is one system used to classify sediments, including sand, by grain size. The word sediment is a general term for mineral particles, for example individual sand grains, which have been created by the weathering of rocks and soil and transported by natural processes, like water and wind. In decreasing order of size, sediments include boulders, gravel, sand, and silt.

Credit : Manoa Hawaii

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What is seashore?

 

 

 

The seashore is where the land meets the sea. Sometimes seashores are rocky and have high cliffs. Other seashores are gently sloping, sandy beaches. In some places seashores are made from lots of smooth stones.

 

 

 

 

 

These waves are crashing against cliffs.

This seashore is made from hard rock and has steep cliffs. When waves smash against the cliffs, they slowly wear them away or crack the rock. Sometimes the cliff breaks apart and large pieces of rock fall down into the sea. Under the water, the fallen rocks are tumbled together by the waves and break up into tiny pieces.

 

 

 

 

A sandy beach slopes down into the sea.

When land made from soft rocks meets the sea, the seashore is flat and sandy. Sand is made up of billions of tiny pieces of rock and broken shells.

 

 

 

 

Shingle beaches are covered with stones.

Shingle beaches are made up of small pebbles that have been smoothed by the waves. Shingle seashores are hard places for animals and plants to live because the sea moves the stones around. Most wildlife lives high up on the shore out of reach of the waves.

Different seashores

 

 

 

There are different seashores all over the world. Some seashores are hot and some are icy cold. The animals found on icy seashore can live where it is very cold. They keep warm by having thick fur or oily feathers and a layer of fat under their skin.

 

 

 

 

These birds are looking for food in the mud.

When rivers reach the sea they spread out into wide, muddy seashore called an estuary. Huge flocks of birds feed on muddy estuaries. They hunt for worms, shellfish or crabs in the mud. When the sea flows into the estuary and covers the mud, the birds fly ashore and wait until it goes out again.

 

 

 

 

These penguins live on cold, icy seashore.

In very cold parts of the world, the seashore is icy. Penguins nest on the icy seashores of the Antarctic. It is so cold that they huddle together to keep warm. They keep their egg on top of their feet to stop it from freezing on the ice.

 

 

 

 

 

This seashore is in a hot part of the world.

Coral reefs grow in warm, shallow seas. Coral reefs are made by small animals that live close together. They protect themselves by building hard cases. It is the hard cases that form the coral reef. Coral reefs are important because they are home to many animals.

Changing tides

 

 

Twice a day, the sea moves up and down the seashore. It is high tide when the beach is covered with sea. After high tide, the sea turns and goes back out again. When the sea is far out and the beach is uncovered, it is low tide.

 

 

 

At high tide the seashore is covered.

At high tide, the seashore is covered with water. The high tide line is the highest place the water reaches up the seashore. The tides are caused by the gravity of the Moon and Sun pulling the seawater towards them.

 

 

 

The seashore is uncovered at low tide.

At low tide, the seashore is uncovered and the sea is far out. On some seashore the difference between high and low tides is big. On others it is small. Low tide happens twice in about 25 hours.

 

 

 

 

Waves are made by the wind.

The waves that move across the sea and break on seashore are made by the wind. When the wind blows over the sea, it pushes and drags against the surface and forms waves. Strong storm winds make huge waves. On days when there is no wind blowing, the sea is calm and the waves are very small.

Seashore plants and animals hold on tight

The waves that crash on to a seashore are very strong. Seashore plants and animals must hold on tight to keep themselves safe. If they let go, they could be washed away or smashed on the rocks.

 

 

These limpets are holding on to a rock.

Seashore animals have different ways of holding on. Limpets use their strong foot to grip tightly on to rocks and stop them from being washed away. Some animals, like sea urchins, cling on to rocks with lots of tiny feet that look like tubes. Mussel shellfish anchor themselves down to rocks with tough threads.

 

 

 

 

This seaweed grips on tightly to the rocks.

Seaweeds anchor themselves on to rocks to stop them from being washed away by strong waves. Large seaweeds grip on to rocks with strong, finger-like rootlets called holdfasts. During storms, seaweed is ripped off rocks.

 

 

 

 

 

Sea otters wrap themselves in seaweed.

When sea otters sleep, they wrap themselves in giant kelp seaweed. They grab a floating end of kelp and spin around in the water. The kelp wraps around the otter and anchors it down. It stops the sea from carrying the sea otter away in its sleep.

 

Seashore Shells

 

 

 

Shellfish are small animals that live inside shells. Their hard shells help to keep them safe from being eaten by other animals or smashed by waves. When shellfish are out of water, their shells stop them from drying out.

 

 

 

 

 

      These shellfish live in one shell.

Some shellfish live in one shell. The animal that lives inside has a very strong, muscular foot which it uses to move itself and to cling to rocks with. If the animal is in danger, it withdraws and hides inside its shell. These shellfish feed on seaweed or on other animals.

 

 

 

 

This shellfish has two shells joined together.

Some shellfish have two shells that are hinged together. Scallop shellfish swim by flapping their shells open and shut. Shellfish with two shells feed by sucking in water, and straining out small bits of food.

 

 

 

 

 

This hermit crab lives in an old shell.

Hermit crabs have a long soft body which they protect by living in an empty shell. They have a pair of strong hooks on their rear end to hold them safely in their shell. When a hermit crab grows too big for its shell, it will find a bigger shell to live in.

Life in a rock pool

 

 

When the tide goes out, some water is left behind in hollows in the rocks. Many different seaweeds and animals live in these rock pools. They can stay safely underwater in the rock pool until the sea comes in again.

 

 

 

 

 

Starfish live in rock pools.

 

The underside of a starfish is covered with lots of tiny tube feet. It uses the feet to move and to grip on to rocks. Starfish feed on shellfish and use their arms to force open the shells to reach the soft animal inside. If a starfish loses any of its arms, it can grow new ones.

 

 

 

 

 

Sea anemones are animals.

Sea anemones look like flowers, but they are animals. They catch food with their tentacles. When a sea anemone is out of the water, it pulls in its tentacles to stop itself from drying out. It looks like a blob of jelly!

 

 

 

 

 

This is a rock pool food chain.

A food chain shows the link between plants and animals in a habitat. All food chains start with plants, which are eaten by plant-eating animals. Plant-eaters are eaten by flesh-eating animals. In a rock pool, seaweeds are food for animals like limpets. Limpets are eaten by whelks.

Seashores animals – Digging in

 

 

 

Many seashore animals bury themselves in the sand, mud or rock. They dig themselves in to try to keep themselves safe from being eaten. Some animals hide in the sand when the tide is out. This stops the animal from drying out in the wind or Sun.

 

 

 

 

 

These are lugworm casts on a sandy beach.

Lugworms live in U-shaped burrows on sandy or muddy seashores. They swallow mud and eat any pieces of food they find in it. The sand comes out of the worms’ bottom at the other end of the burrow, and makes a squiggly worm cast on the surface of the mud.

 

 

 

This dog whelk hides in cracks in rocks.

Some shellfish protect themselves by digging into rock or squeezing into gaps between rocks. Dog whelks hide under rocks, crawl into cracks and wedge themselves into crevices on rocky seashores when the tide goes out. When the tide comes back in the dog whelks come out to feed.

 

 

 

 

Cockles bury themselves in the sand.

Cockles use their muscular foot to bury themselves in the sand. This helps to protect them from being eaten by birds and animals. Cockles and razorshells feed using long siphons that suck water and strain food from it.

Seashore plants

 

 

Many plants live on the seashore. Seaweeds are seashore plants that can live in salty seawater. Some seashore plants can only live on the land. They grow high up the shore, out of the reach of the waves.

 

 

 

 

 

This seaweed floats in the water.

Bladder wrack seaweed has pockets of air and jelly to help it float in the water. Its tough leathery leaves are covered in a slippery, gummy substance to protect it from drying out at low tide. Bladder wrack can survive out of water while the tide is out.

 
 
 
 
 
 
 
 

 

Kelp seaweed grows very fast.

Californian kelp seaweed is the fastest growing plant in the world. It can grow up to one metre in a day and can reach lengths of 100 metres. Kelp grows in huge underwater forests, which are home to many fish and other animals.

 

 

 

 

 

 

These tough grasses grow on sand dunes.

Marram grass is a tough plant that grows on sand dunes at the seashore. It has thin, curled leaves to protect it from drying out in the wind and the Sun. Marram grass has long roots to reach down to water. The roots stop the plant blowing away.

 

Seashore birds

 

 

Seashore birds feed on different foods. They hunt for food on the land and in the sea. Some birds dig in the sand to find worms and shellfish. Fish-eating birds dive into the sea to catch their food.

 

 

 

 

 

 

 

 

Seashore birds build their nests on steep cliffs.

Seashore birds often nest together in huge, noisy colonies. They make their nests on high, rocky cliffs because it is very difficult for predators to reach them there. Some seabirds make nests, but others just lay their eggs on a rocky ledge.

 

 

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Seashore Fishes

 

 

 

At low tide, seashore fish hide. They squeeze into cracks in rock pools or hide under the sand. When the tide comes in, they come out to feed. Seashore fish have eyes near the top of their head. They look out for seabirds that try to catch them from above.

 

 

 

 

 

This fish lives in rock pools.

Goby fish live in rock pools. Their skin is patterned to help them hide against the rocks and seaweed. Some goby fish have their lower fins joined together to make a sucker. They use the sucker to cling on to rocks and stop them from being swept away by waves.

 

 

 

 

These pipefish are hard to see.

Pipefish can hide themselves so well that they are very hard to see. They have a long, thin body that helps to disguise them when they hide in seaweed. They live in rock pools and feed on other small fish and shellfish.

 

 

 

 

This fish can breathe air.

Mudskipper fish live on warm, muddy seashores. Most fish can only breathe in water. Mudskipper fish can breathe in air and water. They use their front fins as legs and crawl about on mud to look for food.

Seashores visitors

 

 

Some of the animals that we see on seashore do not live there all the time. They spend most of their life in the sea, and only visit the seashore for a short time. They may visit the shore to rest or to have babies.

 

 

 

 

 

 

These seals have come to the shore to rest.

Seals spend most of their time in the sea, but they sometimes visit the seashore. Seals are excellent swimmers but move very slowly on land. They haul themselves up on to rocks or sand banks to rest and bask in the Sun. Seals give birth to their pups on quiet seashores where they will not be disturbed.

 

 

 

 

 

Puffins visit the seashore to nest.

Puffins visit the seashore each year to breed. They nest on the top of cliffs. They dig burrows or take over an old rabbit tunnel. Puffins usually have only one chick. They feed their chicks on sand eels and fish.

 

 

 

 

 

 

Turtles visit the shore to lay their eggs.

Female turtles come ashore at night to lay their eggs above the high tide line. They dig a hole in the sand, lay their eggs in it and cover the eggs with sand. When the babies hatch, they dig themselves out and crawl down to the sea.

Looking after the seashore

 

 

 

Seashores can be harmed by people. If we leave rubbish on a beach, it can hurt or kill wildlife. Plants and animals often lose their homes when we build on the seashore. We all need to take care of the seashore and the wildlife that lives there.

 

 

 

 

 

 

This rubbish has been washed up on a beach.

Rubbish is often dumped in the sea. It can be carried long distances and washed up on beaches. Rubbish like plastic bottles and bags, fishing line and glass can hurt or kill animals. Turtles eat plastic bags because they look like jellyfish.

 

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