Lesson video

Hello, and welcome.

My name is Ms. Harrison, I'm so excited to be learning with you today.

Today's lesson is called Examples of Coastal Landforms. Grab everything that you might need for today's lesson, and let's begin our learning.

By the end of today's lesson, you'll be able to describe and explain landforms of coastal erosion and deposition on the Jurassic Coast.

Before we can begin this learning, we need to define the keywords that we'll be using throughout today's lesson.

The keywords in today's lesson are: coastal erosion landforms, and coastal deposition landforms. Coastal erosion landforms, these are landforms resulting from a dominance of coastal erosion, and coastal deposition landforms, are landforms resulting from a dominance of coastal deposition.

Now that we've defined these keywords, we can begin our learning.

The first question we're going to explore in today's lesson is, why is the Jurassic Coast significant? The Jurassic Coast is part of the southern coastline of England.

It stretches all the way from Exmouth in Devon to Studland Bay in Dorset, on your screen is a satellite image of the area.

We have used GIS to be able to measure the distance from Exmouth in Devon, all the way to Studland Bay in Dorset.

Sofia has cleverly noted that, "Judging from the measurement on the satellite image, the Jurassic Coast is 154 kilometres long!" The Jurassic Coast is named for its rich history of fossil records from the Jurassic Period.

The coastline is part of a UNESCO World Heritage Site.

The Jurassic Coast is one of the most famous coastlines in the world, but did you know that it isn't just from the Jurassic Period? The name comes from the Jurassic Period, but the rocks along the coastline actually come from three different geological periods, spanning over 250 million years of Earth's history, let's break it down.

The Triassic Period, it started 250 to 200 million years ago, these the oldest rocks found along the Jurassic Coast, at this time, the UK was parts of a hot, dry desert, and the rocks that formed were red sandstone.

They were created by compacted desert sand, and these rocks provide evidence of an ancient arid environment, very different from today's coastline.

Then we have the Jurassic Period, 200 to 145 million years ago.

The Jurassic Period is what gives the coast its name.

During this time, the area was covered by warm, shallow sea, filled with marine creatures, like Plesiosauruses.

As these creatures died, their remains were buried and fossilised in the limestone and clay found along the coast.

Today, these fossils provide scientists with an incredible record of prehistoric life, and then we have the Cretaceous Period, these are the youngest rocks on the Jurassic Coast.

By this time, the sea levels have risen, and the airs covered by deep tropical seas, the white chalk cliffs found along the coast, such as those at Old Harry, formed by the calcium-rich shells of tiny sea creatures that settled on the ocean floor, and compacted over millions of years.

So even though it's called the Jurassic Coast, it actually represents a huge chunk of Earth's history recording over 200 million years of environmental changes, from deserts to shallow seas to deep oceans, this is why the Jurassic Coast is a UNESCO World Heritage Site, it's like a giant natural time capsule, revealing the incredible story of the planets past life.

On your screen is a cartoon illustration of Mary Anning, who discovered fossils at Lyme Regis that were very important in the history of science.

True or false, the Jurassic Coast is only made up of rocks from the Jurassic period? Pause the video here whilst you attempt this task, and press play when you're ready to continue.

Excellent work, the answer is false.

I would now like you to explain why this answer is false.

Pause the video here whilst you attempt this task, and press play when you're ready to check your answers.

Fantastic, the reason why the statement is false is because, the Jurassic Coast is actually made up of rocks from three different geological periods: the Triassic, Jurassic, and Cretaceous Periods.

The Jurassic Coast is famous for its fossils from the Jurassic Period.

Excellent work, if you managed to explain that correctly.

The Jurassic Coast has stretches of discordant coastlines and stretches of concordant coastline.

This makes it really interesting for geographies! The map on your screen is a geological map of the area.

I'm going to label where the discordant coastlines are and the concordant.

Here is the discordant coastline, where layers of rock run perpendicular to the coast, and here is the concordant coastline, where layers of rock run parallel to the coastline.

What is the geological structure of the Jurassic Coast? Is it, A.

discordant and concordant coastlines, B, only discordant coastlines, or C only concordant coastlines? Pause the video here whilst you attempt this task, and press play when you're ready to continue.

Excellent, the geological structure of the Jurassic Coast is, A, discordant and concordant coastlines.

Well done if you managed to identify that correctly.

I would now like you to fill in the blanks using the words below.

The text summarises the location of the Jurassic Coast, and to highlight its geological significance.

Pause the video here whilst you fill in the blanks using the words below, and press play when you're ready to check your answers.

Excellent, let's check our answers.

Your answer should read like this.

The Jurassic Coast is located on the southern coast of England, stretching from Exmouth in Devon to Studland Bay in Dorset, covering about 154 kilometres.

It is significant because it reveals over 200 million years of Earth's history, with rocks from three main geological periods: The Triassic period known for the red sandstone, the Jurassic Period, famous for fossils, and the Cretaceous Period, marked by its white chalk cliffs.

The Jurassic Coast is a UNESCO World Heritage Site due to its exceptional geological importance.

Well done if you managed to get all of those correct.

We're now going to explore our second question of today's lesson.

What coastal erosional landforms are found there? Coastal erosion landform are formed through wave action, weathering, and mass movements.

Waves erode cliffs in three main ways: through hydraulic power, attrition, and abrasion.

Let's take a moment to recap what these three words mean.

Hydraulic power is when waves compress air inside cracks in the rock face, which weaken it.

Attrition is when rocks hit each other in the waves and are broken into smaller pieces.

Abrasion, this is when rocks carried by the waves scrape against the rock face.

The Jurassic Coast has a number of different examples of coastal erosion landforms, for example, headlands and stacks, like Old Harry, arches like Durdle Door, and coves, like Lulworth Cove.

Along the east coast of the Isle of Purbeck, there are alternating layers of harder and softer rock that are perpendicular to the coast, Andeep has cleverly noted that, "This is a discordant coastline, where bays and headlands are found." On the map on your screen, I've labelled where the headlands are, where there's slower rates of erosion, and where bays are, where there's a faster rate of erosion.

The Jurassic Coast is shaped by erosion and deposition, with different types of rocks creating unique coastal landforms. A great example of this is found around Swanage Bay and The Foreland, where the headlands and bays have formed due to varying rock resistance, let's start with The Foreland.

The Foreland is a chalk headland located between Swanage Bay and Studland Bay to the north, chalk is a hard, resistant rock, meaning it erodes more slowly than other rock types.

Now let's look at Swanage Bay.

Swanage Bay lies between the headlands of Ballard point and Peveril Point.

Unlike The Foreland, the rocks here are soft sandstone and clay, which erode more easily.

Because soft rocks wear away faster, the coastline here have been pushed back, creating the wide, curved shape of the bay.

So when we look at Swanage Bay and The Foreland, we can clearly see how geology influences coastal landscapes.

The hard chalk headlands stand out as resistant rock formations, and soft sandstone and clay, erode quickly, forming sheltered beds.

This constant battle between waves and rock types is what shapes the dramatic landscapes of the Jurassic Coast.

Old Harry is one of the most famous features of the Jurassic Coast.

It's a chalk stack located at the tip of The Foreland.

Old Harry was once part of the headland, but over thousands of years, the relentless power of the sea has shaped into the isolated stack we see today.

The process follows a classic sequence of coastal erosion.

The headland was originally a solid chalk, but waves attack the points in the rock, the power of hydraulic power and abrasion enlarged the cracks, eventually forming a cave.

Over time, the cave was eroded further, and expanded until it broke through the other side of the headland, forming a natural arch.

The arch became weakened by weathering and erosion, especially at its base, where waves attacked constantly.

Eventually, the arch collapsed, leaving behind a tall, isolated pillar of rock, this is Old Harry, now standing as a chalk stack.

Until 1896, there was another stack known as Old Harry's Wife, but erosion caused it to tumble into the sea, leaving just a stump.

The map on your screen shows the change at Old Harry between 1890 and the modern day.

You'll be able to see in the modern-day map, that Old Harry's Wife is no longer labelled.

I would now like you to identify the four-figure grid reference for Old Harry.

I'd like you to take a closer look at the map, once you identify where Old Harry is, and find the correct four-figure grid reference for it.

Pause the video here, and press play hen you're ready to check your answers.

Well done, the answer is Old Harry is located in grid reference 0582, well done if you managed to identify that correctly.

Durdle Door is another iconic landmark on the Jurassic Coast.

Like Old Harry, Durdle Door was shaped through a sequence of erosional processes acting on weak points in the rock over thousands of years.

The coastline here is made up of limestone, a hard, but fractured rock that contains natural faults and joints.

Waves targeted these weak points through hydraulic power and abrasion, and the cracks expanded creating a cave.

As erosion continued, the cave grew wider and deeper, eventually breaking through to the other side of the headland.

This left a natural limestone arch, with sea now flowing through it.

The future of Durdle Door is like this.

Over time, erosion will continue to weaken the arch further, especially at its base where the waves attack its strongest.

Eventually, the top of the arch will collapse, leaving behind a stack, which will then erode farther into the stump, before disappearing completely.

Durdle Door is a classic example of coastal erosion, and a perfect demonstration of how sea caves evolve into arches, stacks, and eventually stumps.

This continuous process of erosion, weathering, and geological change is what makes the Jurassic Coast a living example of Earth's history.

A wave-cut platform forms the base of the cliff due to the relentless action of waves eroding the rock, for example, through hydraulic power and abrasion.

The cliffs at West Bay are a perfect example of this, where the soft clay and hard limestone layers have been eroded to form high, steep cliffs, and leaving a wave-cut platform in the front of it.

I'm now going to show you on your screen, the way this area would've been eroded.

Many, many years ago, this is where West Bay Cliffs would've been standing, through abrasion and hydraulic power, they were eroded, eventually retreating back, to now where they stand today.

I would now like you to think what coastal erosion landscapes is located here, is it, A, an arch, Durdle Door, B, a stack, Old Harry, C, a wave-cut platform, West Bay? Pause the video here whilst you attempt this task, and press play when you're ready to continue.

Excellent, the answer is C, a wave-cut platform, West Bay, well done if you managed to identify that correctly.

Limestone runs parallel along the southern coastline, forming a concordant coastline.

This map illustrates that fewer erosion land forms are present along a concordant coastline, but that doesn't mean that there aren't any original landforms found here.

Lulworth Cove formed at a point where the more resistant limestone layer of the concordant coastline has been eroded through to the less resistant layer behind it.

Waves have been able to erode a wider area in the softer rocks behind the more resistant limestone.

As you can see on the image, the harder rocks have not been eroded and are still headlands, but the softer rock, has now formed a bay.

Which of the following best describes the formation of Lulworth Cove? Is it, A, Lulworth Cove was formed by erosion of a limestone headland, B, Lulworth Cove is a flooded river valley that was formed by glacial activity, C, Lulworth Cove was formed by the erosion of softer rock behind a resistant layer of limestone? Pause the video here whilst you attempt this task, and press play when you're ready to continue.

Fantastic, the answer is C, Lulworth Cove was formed by the erosion of softer rock behind a resistant layer of limestone, excellent work on this task.

True or false, Old Harry's Rocks are made entirely of sandstone and have not changed in shape for thousands of years? Pause the video here whilst you decide, and press play when you're ready to continue.

Excellent, the answer is false.

I would now like you to explain why this answer is false.

Pause the video here whilst you attempt this task, and press play when you're ready to continue.

Brilliant, the reason why this statement is false is because, Old Harry Rocks are made of chalk, not sandstone.

They've been eroded over time by the sea, leading to their current shape.

Old Harry's Wife has been eroded and is no longer visible.

Well done if you managed to explain that correctly.

I would now like you to use the table below and your own knowledge, to explain how each feature along the coast has been formed.

We're going to focus on Old Harry, Durdle Door, and Lulworth Cove.

Pause the video here whilst you attempt this task, and press play when you're ready to continue.

Great work, let's check our answers.

Your answer might include some of the following points.

For how old Harry was formed, Old Harry is a chalk stack that formed through erosion of a headland: a sea cave would've become an arch and then a stack.

Old Harry's Wife was also a stack, but due to erosion, it no longer exists.

Durdle Door, Durdle Door is a natural limestone arch.

The arch began as a sea cave that was erosion along the natural faults in the rock.

Over time, this cave has widened into an arch.

Lulworth Cove, Lulworth Cove is a circular cove formed by the erosion of a layer of soft rock, such as clay, behind a more resistant layer of limestone.

The soft rock had eroded more quickly, creating the cove shape.

Fantastic work on this task, I hope you managed to get some of those points in your answers.

We're now going to explore our final question of today's lesson.

What coastal deposition landform are there? Coastal deposition landform occur when waves lose energy and drop the sediment they carry, creating distinctive landforms. Izzy says that, "She knows that sediment is transported along the coastline through longshore drift.

This is when sediment is moved in a zigzag pattern along the coast." The Jurassic Coast also has a number of different coastal deposition landforms. For example, a bar and tombolo at Chesil Beach, and sand dunes at Studland Bay.

Chesil Beach is a unique coastal deposition landform, combining both a bar and a tombola.

On the image on your screen, I've labelled where the tombola is, and where the bar and lagoon are.

A tombola is a narrow ridge of sand and shingle, that forms when sediment is deposited by the movement of waves, creating a natural bridge between an island and the mainland.

How did Chesil Beach form? The key process behind the formation of Chesil Beach is longshore drift, where waves move sediment along the coastline.

Waves approach the shore at an angle, driven by the prevailing winds.

Sediment is carried up the beach through swash at an angle, and then gravity pulls the water back down the beach, through the backwash in a straight line.

The zigzag movement of sediment gradually transports sand and pebbles along the coast, eventually forming the long ridge of Chesil Beach.

This image shows the view from the Isle of Portland, looking back towards the mainland, highlighting how Chesil Beach connects two land masses.

A bar has also formed through longshore drift in front of the coast enclosed in the Fleet Lagoon.

It is the largest tidal lagoon in the UK.

It is also a protected marine area because of the wildlife that lives there.

Which of the following statements best describes Chesil Beach bar and tombolo, is it, A, Chesil Beach is a tombolo connecting the Isle of Portland to the mainland, while the bar is submerged feature under the water, B, Chesil Beach is a bar formed by longshore drift, while the tombolo connects the Isle of Portland to the mainland, or, C, Chesil Beach is a bar formed by tidal currents, and the tombolo is a feature that connects Chesil Beach to the Isle of Portland? Pause the video here whilst to attempt this task, and press play when you're ready to continue.

Great work, the answer is B, Chesil Beach is a bar formed by longshore drift, while the tombolo connects the Isle of Portland to the mainland, well done on this task.

Studland Bay has six kilometres of sandy beaches within sheltered waters leading onto sand dunes.

Sand dunes form when there are certain conditions, they need a large, wide flat beach, plenty of sand, a wide tidal range, onshore winds, and obstacles on the beach that trap the sand.

Sand dunes form when the wind deposits sand on top of each other until a small ridge starts to form.

The wind will continue to deposit sand on the ridge until it collapses.

This process is going to be repeated several times, causing the dunes to move inland.

On the diagram on your screen, I have labelled how this process happens.

The dune builds up until it becomes unstable, and then eventually, the process will continue to be repeated, causing the gene to move inland, but this will take some time.

Plants like marram grass, begin to grow in the sand, stabilising the dunes.

The roots help attract more sand, leading to the gradual buildup of the dune.

Over time, layers of sand accumulate and grow into larger sand dunes, and this process can take many years.

Nested along the southern coast of England, Studland's dunes are an ecological wonder.

One of the most striking features of the coastal area is the formation of a freshwater lake, known as the Little Sea.

Here, inland from the dunes, a triangle body of water has emerged, providing a rare environment within the sandy landscape.

The dunes themselves are made of acidic sand, a composition that shapes their ecosystem in a really significant way.

The acidity limits the types of plants that can thrive there, and while many of these dunes across the country are dominated by grasses, Studland's dunes are home to something different.

Instead of grasses, the acidic soil fosters the growth of dune heather, which flourishes here, creating an iconic heath-like atmosphere.

But this unique vegetation is not the only thing that makes these dunes special.

Sadly, the biodiversity of Studland's dunes is on the decline.

Once teaming with various species, the changing climate alongside increasing human pressure, threatened for delicate balance of life here.

What feature is found behind sand dunes at Studland Bay, Is it A, a bar, B, a freshwater lake, or C, a river? Pause the video here whilst you attempt this task, and press play when you're ready to continue.

Excellent, the answer is B, a freshwater lake.

True or false, the sand dunes at Studland Bay were formed by the Little Sea, which provides a constant flow of water to move the sand? Pause the video here whilst you decide if this statement is true or false, and press play when you're ready to continue.

Excellent, the answer is false.

I would now like you to explain why this answer is false.

Pause the video here, and press play when you're ready to continue.

Brilliant, the reason why this statement is false is because, the sand dunes at Studland Bay were formed by the wind, not the Little Sea.

The wind blows sand from the beach, gradually building up the dunes over time.

The Little Sea is a freshwater lake, but it doesn't help to create the dunes.

Well done if you manage to explain that correctly.

I would now like you to explain why Chesil Beach is an unusual coastal deposition landform.

Aisha has cleverly noted that, "She can spot two coastal deposition landform in this image." I hope you can too.

Pause the video here whilst you attempt this task, and press play when you're ready to check your answers.

Fantastic, let's check our answers.

Your answer could have included the following points.

Chesil Beach is a unique because it is both a tombolo, connecting the Isle of Portland to the mainland, and a bar, enclosing the Fleet Lagoon, an important wildlife habitat.

It formed through longshore drift, where waves and currents moved pebbles and shingle along the coast, creating this distinct landform.

Well done if you to explain that correctly.

We've now come to the end of our lesson of Examples of coastal landforms. You've done brilliantly, but before we end this lesson, let's summarise everything we've learned today.

The Jurassic Coast is a UNESCO World Heritage Site on the southern coast of England, it's known for its rich geological history and diverse coastal landforms. Coastal erosion landforms include Old Harry and Durdle Door.

Lulworth Cove is a circular cove created as softer rock, was eroded behind harder limestone, along a concordant coastline.

Coastal deposition landforms include Chesil Beach and Studland Bay sand dunes, and they're formed by sediment carried by wind and water.

Well done on today's lesson.

, you've done brilliantly, I look forward to learning with you again very soon.