Unit 8 Essays - Coastal Landforms - SIMPLE ENGLISH UPDATED Flashcards
Assess the extent to which rock type and rock structure are important factors in explaining the characteristics of coastal cliffs.
Paragraph 1: How Rock Type (Lithology) Affects Cliffs
Main Idea:
The type of rock a cliff is made of affects how fast it erodes and how strong it is.
Soft rock erodes quickly, while hard rock erodes slowly and stays standing longer.
Case Studies:
Holderness Coast (East Yorkshire):
Made of soft glacial till (clay, sand, and gravel), which is weak and falls apart easily.
Erodes at 1.8 meters per year, one of the fastest erosion rates in Europe.
Waves quickly wash away the material, leading to cliff collapses.
Jurassic Coast (Dorset):
Made of harder rocks like limestone, sandstone, and chalk.
Portland limestone erodes at 1-2 mm per year, which is thousands of times slower than Holderness.
These rocks create tall, steep cliffs and dramatic coastal features.
Extra Explanation:
Where cliffs are located (spatial variation) makes a difference – some areas have soft rock, others have hard rock.
Over long periods of time (temporal variation), soft coasts retreat much faster than hard rock coasts.
Paragraph 2: How Rock Structure Affects Cliff Stability and Shape
Main Idea:
The way rocks are arranged (rock structure) affects how cliffs break apart and what shapes they form.
Case Studies:
Holderness Coast:
The soft glacial till has no strong layers or structure, making it very weak.
Cliffs collapse often because they do not have strong support.
This creates low, sloping cliffs with lots of landslides.
Jurassic Coast:
Lulworth Cove:
Has layers of hard and soft rock.
The soft rock erodes quickly, while the hard rock stays standing, creating a circular bay.
Durdle Door:
Rocks are tilted at an angle, making it easier for waves to erode parts of them.
This has led to the formation of a natural stone arch.
Old Harry Rocks:
Chalk cliffs with cracks (joints and bedding planes) allow waves to break them into stacks and stumps.
Extra Explanation:
Different rock structures create different landforms.
Over time, cracks and faults allow waves to shape cliffs into arches, stacks, and coves.
Paragraph 3: The Role of Waves in Eroding Cliffs
Main Idea:
Waves are a powerful force that wears down cliffs.
Even strong rocks will erode if waves hit them hard enough for a long time.
Case Studies:
Holderness Coast:
Strong North Sea waves constantly crash against the cliffs.
Longshore drift moves sand away, so there is no beach to protect the cliffs.
This makes the cliffs even more exposed to wave attack.
Jurassic Coast:
Old Harry Rocks:
Waves slowly erode the base of the cliffs, creating stacks and stumps.
Wave-cut platforms (e.g., Kimmeridge Bay):
The sea wears away the base of cliffs, making them collapse and leaving behind a flat rocky surface.
Extra Explanation:
Cliffs with strong waves erode faster, even if the rock is hard.
Over time, waves change cliff shapes, creating caves, arches, and stacks.
Paragraph 4: The Impact of Weather and Climate on Cliffs
Main Idea:
Rain, storms, and temperature changes make cliffs weaker and easier to erode.
Case Studies:
Holderness Coast:
Heavy rain makes cliffs wet and heavy, causing landslides (slumping).
Winter storms increase erosion by making waves stronger.
Jurassic Coast:
Freeze-thaw weathering:
Water enters cracks, freezes, and expands, slowly breaking rock apart.
Salt weathering:
Salt from seawater dries in rock cracks, making them weaker over time.
Extra Explanation:
Weathering happens slowly, but over time it weakens cliffs.
Climate change is making storms stronger, increasing erosion in many places.
Paragraph 5: How Humans Affect Cliff Erosion
Main Idea:
People try to stop erosion, but sometimes they make it worse.
Case Studies:
Holderness Coast:
Groynes (wooden/stone barriers) at Mappleton protect some areas by stopping sand from moving.
But this means less sand reaches other areas, making erosion worse further down the coast.
Sea walls protect cliffs but also make waves stronger in nearby areas.
Jurassic Coast:
No big sea defences because it is a UNESCO World Heritage Site.
Instead, they use soft engineering, like:
Beach nourishment (adding sand to beaches to slow erosion).
Managed retreat (letting some areas erode naturally).
Extra Explanation:
People can slow down erosion, but they can also make it worse.
Some areas get more protection than others, which changes how cliffs erode.
Conclusion
Rock type and structure are very important in shaping cliffs.
Holderness Coast shows how soft, weak rock erodes very quickly.
Jurassic Coast shows how harder rocks create famous landforms like arches and stacks.
But other factors also matter:
Waves wear away cliffs.
Weather and storms make cliffs weaker.
Humans try to control erosion but sometimes make it worse.
Final judgment: Rock type is one of the most important factors, but it must be considered alongside waves, weather, and human activity to fully understand why cliffs change over time.
‘Sea-level rise affects coastal depositional landforms more than coastal erosional landforms.’ How far do you agree with this view?
Paragraph 1: How Sea-Level Rise Affects Depositional Landforms (Tombolos, Barrier Beaches, and Barrier Islands)
Main Idea: These landforms are made of sand and other loose materials, so rising sea levels wash them away easily.
Examples:
Tombolo at St Ninian’s Isle (Shetland, UK)
A tombolo is a sandy strip connecting an island to the mainland.
The sea is washing away the sand, making it smaller.
Slapton Sands (Devon, UK) – Barrier Beach
A barrier beach protects land from the sea.
It is eroding by 1 meter per year because rising sea levels bring stronger waves.
Outer Banks (North Carolina, USA) – Barrier Islands
A group of sandy islands off the coast.
They are moving inland by 1.5–2.5 meters per year because of stronger waves.
Key Points to Explain:
These landforms need a steady supply of sand to stay stable.
Rising sea levels change wave patterns and make it harder for sand to stay in place.
Tropical and warm places have even bigger problems because of hurricanes.
Link to Next Paragraph: Sand dunes, saltmarshes, and mudflats, which also need steady sand and mud supply, are facing similar risks.
Paragraph 2: How Sea-Level Rise Affects Sand Dunes, Saltmarshes, and Mudflats
Main Idea: These landforms act as natural barriers, but rising sea levels are making them weaker.
Examples:
Formby Sand Dunes (Liverpool, UK)
These dunes are shrinking by 4 meters per year because storms and rising sea levels wash the sand away.
The Wash (East England) – Saltmarsh
Saltmarshes protect the coast by slowing down waves.
Rising sea levels flood them more often, killing plants that hold the mud together.
Morecambe Bay (UK) – Mudflats
Mudflats need a balance of mud being deposited and removed.
Higher tides spread the mud too far, causing erosion and loss of habitat.
Key Points to Explain:
Rising sea levels flood these areas more often, damaging plants and removing sand and mud.
Over time, they will disappear if the sea rises too much.
If these landforms disappear, towns behind them will have no protection from storms.
Link to Next Paragraph: Spits, cuspate forelands, and beaches, which also depend on moving sand, are also being affected.
Paragraph 3: How Sea-Level Rise Affects Spits, Cuspate Forelands, and Low-Lying Beaches
Main Idea: These landforms depend on longshore drift (waves moving sand along the coast). If sea levels rise, this process is disrupted.
Examples:
Spurn Head (Humber Estuary, UK) – Spit
A spit is a long, thin piece of land made of sand.
It is eroding by more than 3 meters per year because waves are carrying the sand away faster than new sand can replace it.
Dungeness (UK) – Cuspate Foreland
A triangular-shaped landform made of pebbles.
Rising sea levels are changing the wave direction, making it harder for new pebbles to stay in place.
Maldives – Low-Lying Beaches
80% of the Maldives is less than 1 meter above sea level.
If the sea rises by just 50 cm, many beaches and islands will disappear.
Key Points to Explain:
These landforms need waves to bring in new sand.
If sea levels rise, waves get stronger and take sand away instead.
Tropical areas (like the Maldives) are at the biggest risk of disappearing completely.
Link to Next Paragraph: Erosional landforms, like cliffs and wave-cut platforms, are also affected, but they erode more slowly.
Paragraph 4: How Sea-Level Rise Affects Erosional Landforms (Cliffs, Wave-Cut Platforms, Headlands, Bays)
Main Idea: Erosional landforms are harder and take longer to erode, but rising sea levels still affect them.
Examples:
Holderness Coast (UK) – Cliffs
This coast is made of soft clay, which erodes by 2 meters per year.
Rising sea levels mean bigger waves, which cause even more erosion.
Kaikoura (New Zealand) – Wave-Cut Platforms
These are rocky platforms that form when waves erode cliffs.
Higher sea levels mean they are covered in water for longer, which speeds up erosion.
Dorset Coast (UK) – Headlands, Bays, and Stacks (Old Harry Rocks)
Rising sea levels make waves hit cliffs harder, causing caves, arches, and stacks to form faster.
Key Points to Explain:
Cliffs and rock formations erode more slowly than beaches or spits.
However, rising sea levels increase wave power, making erosion happen faster over time.
Link to Next Paragraph: Some landforms, like rias, fjords, and mangroves, are affected differently.
Paragraph 5: How Sea-Level Rise Affects Rias, Fjords, Raised Beaches, and Mangroves
Main Idea: Some landforms get flooded, while others are above the current sea level and are less affected.
Examples:
River Fal (Cornwall, UK) – Ria
A flooded river valley.
Rising sea levels push saltwater further inland, changing ecosystems.
Sognefjord (Norway) – Fjord
A deep valley flooded by seawater.
Rising sea levels change tides and erosion patterns.
Portland Raised Beach (UK) – Raised Beach
Formed when sea levels were higher in the past.
Not affected much because it is above current sea levels.
Sundarbans (Bangladesh) – Mangroves
These trees protect the coast by trapping mud.
Losing 200 km² of forest per year due to rising sea levels.
Key Points to Explain:
Some landforms are already underwater, so rising sea levels make them worse.
Others, like raised beaches, are too high up to be affected.
Conclusion
Restate main point: Depositional landforms are affected more than erosional landforms.
Summary:
Beaches, dunes, and spits disappear quickly because they are made of loose sand.
Cliffs and hard rock erode slowly, so the impact is smaller.
Final judgement: Rising sea levels are a bigger problem for depositional landforms.
Assess the Relative Importance of the Factors Influencing the Formation of Coastal Saltmarshes and Mangroves
Paragraph 1: Calm Water and Mud Build-Up
Point:
Both saltmarshes and mangroves need mud and sand to settle so plants can grow.
However, mangroves can survive in places with stronger waves, but saltmarshes need very calm water.
Saltmarshes (The Wash Example):
Found in bays, estuaries, and behind spits where the water is calm.
Fine mud and sand settle because waves are weak.
The Wash (UK) is a big bay with slow tides, allowing mud to build up.
Mangroves (The Sundarbans Example):
Can trap sediment even in places with stronger waves.
Their roots hold the mud in place and stop erosion.
In the Sundarbans, rivers and tides bring mud, and mangroves help trap it.
Evaluation:
Saltmarshes can only grow where the sea is calm, while mangroves can survive in more places.
This makes mangroves more flexible because they don’t always need very low-energy environments.
Paragraph 2: Special Plants That Trap Mud
Point:
Both saltmarshes and mangroves have special plants that trap sediment and make the land stronger.
Saltmarshes (The Wash Example):
Plants like Spartina anglica (cordgrass) grow in salty mud.
They trap more sediment, making the land rise.
More plants grow over time, creating a stable marsh (vegetation succession).
But if storms come, the plants can be washed away.
Mangroves (The Sundarbans Example):
Have stronger roots that anchor them in muddy water.
Rhizophora (Red Mangrove) has stilt roots that help hold the soil.
Avicennia alba has pneumatophores (roots that stick out of the mud) to survive in waterlogged soil.
These roots help the mangroves stay strong, even during storms.
Evaluation:
Saltmarsh plants take longer to build up land, while mangrove trees create stronger coastal protection faster.
Saltmarshes are weaker against erosion, but mangroves hold the coastline together better.
Paragraph 3: The Role of Temperature and Climate
Point:
Saltmarshes grow in cooler climates, but mangroves only grow in warm tropical places.
Saltmarshes (The Wash Example):
Grow in places below 20°C.
The UK’s Wash has an average temperature of 10°C – too cold for mangroves.
Saltmarsh plants survive well in these temperatures.
Mangroves (The Sundarbans Example):
Need temperatures above 20°C to grow properly.
Sundarbans temperature = 26°C (warm all year round) – perfect for mangroves.
Warm weather makes mangroves grow faster and spread easily.
Future Changes (Climate Change Impact):
If the world gets hotter, mangroves might spread into saltmarsh areas.
Saltmarshes could disappear if they can’t survive in higher temperatures.
Evaluation:
Mangroves are more climate-dependent, but they might spread further in the future as temperatures rise.
Saltmarshes are more limited in where they can grow.
Paragraph 4: The Role of Tides and Rising Sea Levels
Point:
Both saltmarshes and mangroves depend on tides, but mangroves can handle deeper flooding.
Saltmarshes (The Wash Example):
Need a medium tidal range (not too high, not too low).
The Wash has a tidal range of 6.5m, which is good for saltmarshes.
Sea-level rise could flood saltmarshes permanently, making them disappear.
Mangroves (The Sundarbans Example):
Can survive in places with big tidal changes.
The Sundarbans has tides up to 5m, and mangroves can handle being underwater for longer periods.
If sea levels rise, mangroves can adapt better by trapping more sediment and growing upwards.
Evaluation:
Saltmarshes may not survive long-term if sea levels rise too much.
Mangroves are more adaptable to rising water levels.
Paragraph 5: Storms and Extreme Weather
Point:
Mangroves are much better at protecting the land from storms than saltmarshes.
Saltmarshes (The Wash Example):
Can reduce small waves, but strong storms can wash them away.
The Wash experiences storm erosion, causing marshes to shrink.
Mangroves (The Sundarbans Example):
Mangroves act as a barrier against storms and floods.
Cyclone Amphan (2020): The Sundarbans mangroves helped reduce flooding damage in Bangladesh and India.
Mangrove roots absorb wave energy, protecting inland areas.
Evaluation:
Saltmarshes offer little protection from extreme weather.
Mangroves are much stronger and provide better flood protection.
Conclusion
Both saltmarshes and mangroves depend on calm water and special plants.
Mangroves can survive in more places, while saltmarshes need very specific conditions.
Mangroves are stronger against storms, rising sea levels, and erosion.
Final Judgement:
Saltmarshes are important in cooler places, but mangroves are more useful overall because they are stronger, last longer, and protect coastlines better.
With climate change, mangroves may spread while saltmarshes may shrink.
Assess the Role of Longshore Drift in the Formation of Depositional Landforms in Coastal Environments
Paragraph 1: How Longshore Drift Creates Spits and Tombolos
🔹 Main Idea: Spits and tombolos form because longshore drift moves sand along the coast and drops it in certain places.
Spits (Example: Spurn Head, UK)
Spurn Head is a spit on the Holderness Coast, UK.
Longshore drift moves 400,000 tonnes of sand each year, pushing the spit further into the sea.
The spit creates a sheltered area behind it, where salt marshes can form.
Spits can change over time—storms or rising sea levels can break them apart.
Tombolos (Example: St Ninian’s, Scotland)
A tombolo is a sandy bridge that connects an island to the mainland.
St Ninian’s Tombolo in Shetland was formed by waves moving sand from both sides.
Tombolos can disappear in storms, showing how landforms change over time.
Paragraph 2: Barrier Beaches and Barrier Islands – Protecting the Coast
🔹 Main Idea: These landforms act as natural walls that protect land from strong waves.
Barrier Beaches (Example: Slapton Sands, UK)
Slapton Sands in Devon was formed after the Ice Age when glaciers left behind gravel.
Longshore drift has moved and shaped this gravel into a long beach.
Barrier beaches can be washed away by storms—some have disappeared completely!
Barrier Islands (Example: Outer Banks, USA)
The Outer Banks are barrier islands in the USA that stretch for 320 km along the coast.
Longshore drift moves sand along the islands, but storms and sea-level rise make them move inland.
Some parts of the Outer Banks are eroding at 30 meters per year, showing how fast these islands can change.
Paragraph 3: Sand Dunes and Salt Marshes – Longshore Drift Helps, But Other Forces Are More Important
🔹 Main Idea: Longshore drift brings some sand and mud, but wind and water are the main forces shaping these landforms.
Sand Dunes (Example: Formby, UK)
Formby Sand Dunes were formed by wind blowing sand inland.
Longshore drift supplies some of the sand, but wind is the most important force.
The dunes are shrinking by 4 meters per year because of human activity and rising sea levels.
Salt Marshes (Example: The Wash, UK)
Salt marshes form in calm, low-energy areas behind spits or barrier beaches.
The Wash in eastern England is one of the largest salt marshes in the UK.
Longshore drift brings some mud, but rivers and tides are the main reason the marsh exists.
Rising sea levels (3mm per year) are changing the shape of the marsh over time.
Paragraph 4: Mudflats and Cuspate Forelands – A Mix of Processes
🔹 Main Idea: Longshore drift plays some role, but other forces are also important.
Mudflats (Example: Morecambe Bay, UK)
Mudflats form when mud and fine sand settle in calm waters.
Morecambe Bay is a large mudflat area in the UK.
Longshore drift brings some of the mud, but tides and rivers are the main cause.
Cuspate Forelands (Example: Dungeness, UK)
A cuspate foreland is a triangular-shaped landform.
Dungeness in the UK is a 12 km² foreland made of pebbles.
Longshore drift moves the pebbles, but wave action from two sides shapes the land.
The foreland is always changing as more material is added or eroded.
Paragraph 5: Low-Lying Beaches and Mangroves – Little Influence from Longshore Drift
🔹 Main Idea: These landforms form mostly from coral, rivers, and tides—longshore drift plays only a small role.
Low-Lying Beaches (Example: The Maldives)
The Maldives’ beaches are made of coral and shell fragments, not sand from longshore drift.
Longshore drift moves some material around, but coral reefs are the main source of sediment.
Rising sea levels are a big threat—many islands could disappear in the future.
Mangroves (Example: The Sundarbans, Bangladesh & India)
Mangroves grow in muddy, coastal areas where rivers bring large amounts of sediment.
The Sundarbans mangrove forest is the largest in the world.
Rivers, tides, and monsoons shape this land, while longshore drift plays almost no role.
Climate change and stronger storms are changing the way sediment is deposited.
Conclusion
Longshore drift is very important for some landforms, like spits, tombolos, and barrier beaches, because it moves large amounts of sand along the coast.
However, it is not the only process at work. Some landforms, like sand dunes and salt marshes, are shaped more by wind, tides, and rivers.
Spatial variation: In some places, longshore drift is stronger due to winds and waves, while in other areas, tides and rivers are more important.
Temporal variation: Over time, storms, rising sea levels, and human activity are changing how depositional landforms develop.
Final judgement: Longshore drift is a key process, but it does not act alone—other forces help shape the coast as well.
Evaluate the role of wind in the formation and characteristics of coastal dunes
Paragraph 1: How Wind Forms Coastal Dunes
🡪 Main Idea: Wind picks up sand from the beach and moves it inland to form dunes.
Wind is the main force that carries sand from the beach further inland.
At Formby, the strong southwest winds (blowing from the Atlantic Ocean) move sand from the beach to the land.
For dunes to form, three things are needed:
Enough dry sand – Sand must be dry and loose so the wind can move it.
Strong enough wind – Wind must blow at least 4.5 meters per second to lift sand.
An obstacle to stop sand – Sand builds up around plants, driftwood, or rocks.
Small sand mounds (embryo dunes) form first. Over time, these grow into larger dunes.
Extra details to include:
Dunes at different locations are affected differently by wind. Some areas have more wind, so dunes grow faster there.
Dunes change over time. They take years to form but can be destroyed in one big storm.
Paragraph 2: How Wind Shapes the Characteristics of Dunes
🡪 Main Idea: Wind affects the size, shape, and movement of dunes.
At Formby, dunes are shaped by how fast and from which direction the wind blows.
Different types of dunes at Formby:
Embryo dunes – Very small, close to the beach, and change shape often.
Yellow dunes – Larger (up to 10 meters high), still moving.
Grey dunes – Covered in plants, more stable, and don’t move much.
How wind changes dunes:
Stronger winds make dunes steeper and taller.
If the wind blows from one direction for a long time, dunes become crescent-shaped (barchan dunes).
Seasonal changes:
Winter storms remove a lot of sand, making dunes smaller.
Summer winds are calmer, allowing dunes to build up again.
Extra details to include:
Some parts of Formby dunes change quickly, while others stay the same for a long time.
Dunes have moved further inland over the years because the wind keeps carrying sand.
Paragraph 3: How Plants Help to Stabilise Wind-Formed Dunes
🡪 Main Idea: Plants stop sand from blowing away and help dunes last longer.
At Formby, marram grass grows on the dunes. It:
Traps sand, helping dunes grow.
Has deep roots that hold the sand together so it doesn’t blow away.
Over time, plants change the dunes:
Yellow dunes (with little plant cover) turn into grey dunes (with more plants and soil).
Blowouts:
If plants die or are damaged, wind can blow the sand away quickly, creating holes in the dunes.
At Formby, tourists walking on the dunes have damaged plants, making more blowouts.
Some areas have strong plant cover (stable dunes), but others have lost plants and are eroding.
Paragraph 4: How Human Activity Affects Wind’s Role in Dune Formation
🡪 Main Idea: People have changed how wind shapes the dunes by damaging them or trying to protect them.
Tourism and foot traffic:
More than 300,000 people visit Formby each year.
Walking on dunes damages plants, making it easier for wind to erode sand.
Tree planting (Afforestation):
Pine trees were planted to stop sand from blowing inland.
This has made some areas more stable, but it also stopped dunes from moving naturally.
How people try to protect the dunes:
Sand fences slow the wind down and help trap sand.
Boardwalks stop people from trampling plants.
Planting more marram grass helps rebuild damaged dunes.
Different parts of Formby dunes are affected in different ways. Some are well protected, while others are eroding fast.
Over time, human impact has increased, so more protection is needed.
Paragraph 5: How Climate Change May Affect Wind and Dune Systems
🡪 Main Idea: Climate change could make wind’s impact on dunes stronger and more unpredictable.
Rising sea levels
The Formby coastline is moving inland by 4 meters per year.
Less beach means less sand for wind to move, which could stop new dunes from forming.
Stronger storms and higher wind speeds
Storms remove large amounts of sand very quickly.
Dunes may not recover before the next storm hits.
Wind patterns may change in the future
If winds start blowing from a different direction, dunes could shift or disappear.
What is being done?
Scientists are studying Formby’s dunes to predict future changes.
More conservation projects may be needed to protect the dunes.
Conclusion
Wind is the most important factor in dune formation.
However, wind does not act alone – sand supply, plants, and human activity also change the way dunes form.
Different areas of Formby dunes are affected differently. Some dunes are shaped by wind, others by people or plants.
Dunes also change over time. Wind builds them slowly, but storms and human activity can destroy them quickly.
Final Judgement: Wind is the main force shaping dunes, but its effects are becoming more unpredictable because of human activity and climate change.
‘Sea level change has a very limited role in the formation of coastal landforms.’ How far do you agree?
Paragraph 1: Raised Beaches – Portland Raised Beach (Formed by Sea Level Change)
Point:
What is a raised beach?
A beach that used to be at sea level but is now higher up because the sea level fell or the land rose.
Example: Portland Raised Beach (Dorset, UK)
125,000 years ago, sea levels were 7-9 meters higher than today because of a warm period.
Then, during the last ice age, sea levels fell by about 120 meters, leaving the old beach above today’s sea level.
Development:
Why did sea levels fall?
Ice sheets grew, trapping water, and making the sea level drop (eustatic change).
Why did the land rise?
When ice melted, land that had been squashed by the ice lifted up (isostatic change).
Counterpoint:
Before sea levels changed, waves and deposition helped create the beach.
Without waves and sand movement, there would be no beach to lift up!
Judgment:
Sea level change played a big role in raising the beach, but waves and sand movement created the beach in the first place.
Paragraph 2: Fjords – Sognefjord, Norway (Mostly NOT Due to Sea Level Change)
Point:
What is a fjord?
A long, deep, narrow coastal valley that was shaped by glaciers and later flooded by the sea.
Example: Sognefjord, Norway
It is 204 km long and over 1,300 meters deep.
How was it formed?
20,000 years ago, a huge glacier carved the valley out.
When the glacier melted, sea levels rose by 120 meters, flooding the valley.
Development:
The glacier did all the hard work in shaping the fjord.
The sea level rise only flooded it to make it look like it does today.
Counterpoint:
Without sea level rise, it would just be a dry valley instead of a coastal landform.
However, the fjord would still exist as a valley even if the sea hadn’t flooded it.
Judgment:
Sea level rise helped make the fjord look the way it does now, but it was not the main reason it exists.
Glaciers did most of the work!
Paragraph 3: Rias – River Fal Ria, Cornwall (Mostly Due to Sea Level Change)
Point:
What is a ria?
A drowned river valley that was created when sea levels rose and flooded a river’s path.
Example: River Fal Ria (Cornwall, UK)
20,000 years ago, the River Fal flowed through a normal valley.
When sea levels rose by 120 meters, the valley filled with seawater, creating a ria.
Development:
The river shaped the valley first by cutting through the land.
Then, sea level rise flooded the valley, turning it into a ria.
Counterpoint:
If sea levels had never risen, the valley would still exist, just as a river valley instead of a coastal feature.
The river did most of the shaping before the sea got involved.
Judgment:
Sea level change was very important in making the River Fal a ria.
But, it needed the river to carve the valley first.
Paragraph 4: Isostatic Change – Land Moving Up and Down
Point:
Sometimes, land moves instead of the sea!
Scotland is rising (1-2 mm per year) after being squashed by glaciers.
Southern England is sinking (1-1.5 mm per year), making the sea seem higher.
Development:
Raised beaches in Scotland: Land is rising, lifting old beaches above the sea.
Coastal flooding in Southern England: The land is sinking, making sea levels seem higher.
Counterpoint:
These local changes don’t affect the whole world’s coastlines.
Other processes like waves and erosion are more important overall.
Judgment:
Isostatic change affects some landforms, but it’s not the main reason most coastal features exist.
Paragraph 5: Other Important Coastal Processes (Why Sea Level Change is NOT Always the Main Factor)
Point:
Many coastal landforms are NOT created by sea level change.
Wave erosion creates cliffs, caves, arches, and stacks.
Longshore drift moves sand to form spits and barrier islands.
Development:
Example: The White Cliffs of Dover (UK)
These chalk cliffs are shaped by waves, not sea level change.
Example: Spurn Head (Holderness Coast, UK)
This spit was formed by longshore drift, moving sand along the coast.
Counterpoint:
Rising sea levels can speed up erosion, but they don’t create most landforms.
Judgment:
Waves, sediment movement, and erosion are more important than sea level changes in many cases.
Conclusion
Sea level change is important for some landforms, especially rias, fjords, and raised beaches.
But many coastal landforms are shaped by other processes, like waves, rivers, and glaciers.
Sea level change is NOT the main factor in most cases.
Instead, wave erosion, sediment movement, and river or glacial processes have a bigger impact.
Final judgment: Sea level change plays a role, but it is not the biggest factor in shaping most coastal landforms.
To what extent is sediment supply the most important factor influencing the characteristics and formation of depositional landforms in coastal environments?
Paragraph 1: Why Sediment Supply is Important
Main Point: Without enough sand, mud, or pebbles, depositional landforms cannot form.
Examples & Explanation:
St Ninian’s Tombolo (Scotland) – This is a sandy strip that connects the mainland to an island. It was formed by waves carrying and dropping sand and small stones over time. However, storms and seasonal changes can wash away some of the sediment, making the tombolo change shape.
Slapton Sands (Devon) – A barrier beach made of shingle (small stones). It was created because of long-term sediment supply, but today, rising sea levels and coastal defences (like sea walls) stop new sediment from arriving, which could cause the beach to disappear.
Key Point: While sediment is needed to create these landforms, it is not enough on its own—other factors like waves and currents decide where and how the sediment is placed.
Paragraph 2: How Waves and Longshore Drift Shape Landforms
Main Point: Even if there is plenty of sediment, waves and currents move it around and decide where it will build up.
Examples & Explanation:
Spurn Head (Holderness Coast, UK) – The Holderness Coast erodes quickly (about 2 meters per year), which provides a lot of sediment. However, the reason Spurn Head exists is because of longshore drift, which moves the sediment south and deposits it at the mouth of the Humber Estuary.
Outer Banks (North Carolina, USA) – A group of long islands made of sand (called barrier islands). These islands are constantly being reshaped by waves and storms. Sometimes they grow, and sometimes they shrink because of strong waves moving the sand away.
Key Point: Sediment supply alone is not enough—waves and currents decide where the sediment goes and whether a landform will grow or be destroyed.
Paragraph 3: How Coast Shape and Vegetation Affect Deposition
Main Point: Some coastlines trap sediment, making landforms grow, while vegetation (plants) helps to hold sediment in place so it doesn’t wash away.
Examples & Explanation:
Dungeness (Kent, UK) – A triangular landform called a cuspate foreland. Here, waves carry sediment from two directions and deposit it in the same place. This only happens because of the coastline’s unique shape.
Formby Sand Dunes (Sefton Coast, UK) – Sand dunes are formed by wind blowing sand inland. However, these dunes would disappear if not for marram grass, which helps hold the sand in place and stops it from being blown away.
Sundarbans Mangrove Forest (Bangladesh & India) – The largest mangrove forest in the world. Mangrove trees trap sediment with their roots and protect the coastline from erosion. Without the mangroves, waves would wash the sediment away.
Key Point: Some landforms need more than just sediment—they need the right coastal shape or plant life to keep the sediment from moving away.
Paragraph 4: Human Activity and Climate Change Can Change Sediment Supply
Main Point: People have changed coastal areas by building structures, removing sediment, or even adding new sediment. Climate change is also affecting sediment supply and deposition.
Examples & Explanation:
Morecambe Bay (UK) – This area has large mudflats, but human activities like dredging (removing sediment from the seabed) and land reclamation (turning coastal areas into land for farming or buildings) have changed how sediment moves and settles.
The Wash (Eastern England) – A large salt marsh area where human flood defenses and managed retreat (letting areas flood on purpose) affect how much sediment is deposited and where it builds up.
Maldives (Indian Ocean) – These islands have very low-lying beaches. Climate change is causing rising sea levels and stronger storms, which are washing away more sand than is being deposited. Without enough sediment, these islands could disappear.
Key Point: Even if sediment supply is naturally high, human activities and climate change can reduce or stop sediment from being deposited in the right places.
Paragraph 5: How the Importance of Sediment Supply Changes Over Time and Space
Main Point: Sediment supply is more important for some landforms than others, and its role changes over different time periods and locations.
Examples & Explanation:
Barrier Islands and Spits (like the Outer Banks and Spurn Head) take centuries to form and are shaped by slow changes in sea level.
Salt Marshes and Mudflats (like those in Morecambe Bay and The Wash) can form in just a few decades, depending on how much sediment is available.
Sundarbans Mangrove Forest – The amount of sediment available has changed over time due to monsoons and tectonic activity (movements of the Earth’s crust).
Key Point: Sediment supply is very important for some landforms but less important for others, especially if other forces like waves, vegetation, or human activity have a bigger effect.
Conclusion
Sediment supply is important, but it is not the only factor that controls depositional landforms.
Waves and longshore drift move the sediment and decide where it builds up.
Coastal shape and vegetation help keep sediment in place and stop it from washing away.
Human activities and climate change can change how much sediment is available and where it gets deposited.
The importance of sediment supply changes depending on time and location—some landforms need a lot of sediment, while others rely more on waves, plants, or human activity.
Final Judgment: Sediment supply is necessary, but it is not the most important factor on its own. The interaction between all the other factors is what really shapes depositional landforms.
