Lesson video

Hello, geographers.

My name's Mrs. Hormigo.

I'm really looking forward to teaching you today.

I hope you're going to enjoy the lesson and learn lots.

Let's get started.

Today's lesson looks at an example of a river valley.

We're going to use the River Eden.

And by the end of the lesson, you'll be able to identify the major landforms of erosion and deposition in the River Eden valley and explain their formation.

There are three keywords for today's lesson, erosion, deposition, and weathering.

Erosion is the process by which flowing water wears away the land, shaping the landscape over time.

Deposition is the process by which rivers drop sediment they have been carrying.

And weathering is the breakdown of rocks but without the material being moved.

It occurs in place.

We say in situ.

There are three parts to today's lesson.

The first is where is the River Eden valley located? The second, what erosional landforms are in the valley? And the third, what depositional landforms are in the valley? Let's get started with our first learning cycle, where is the River Eden valley located? This map shows us the location of the River Eden.

We can see in the little map in the top left-hand corner that we are in the northwest of England.

And we can see here this river is bordered by the Pennines to the east and the Lake District to the west.

The mouth of the River Eden flows out into the Solway Firth and then into the Irish Sea, and the source is on Black Fell Moss.

It flows in a northwesterly direction for 145 kilometres, and it flows through some towns.

Kirkby Stephen in the upper course, Appleby in the middle course, and Carlisle in the lower course.

Which of these correctly describe the location of the Eden Valley? A, the River Eden is to the west of the Lake District, B, the River Eden flows in a northwesterly direction, or C, the mouth of the river is at the Solway Firth? Pause the video and decide which ones you think are correct.

Did you say the River Eden flows in a northwesterly direction and the mouth of the river is at the Solway Firth? Well done.

The River Eden is to the west of the Lake District.

Well done.

We can see here we have a geology map of the UK, and if we look at the colour coding on the map and the key, we can see that the River Eden flows over sandstone and limestone, both of which are fairly resistant to erosion.

And this contributes to the formation of several distinct landforms along the river's course, which we'll have a little look at later on in the lesson.

True or false then? The River Eden does not flow through any urban areas.

Pause the video, and come back when you've decided.

Hopefully you said false and you remembered that much of the upper and the middle course of the river is in farming and rural areas, but the river does flow through Kirkby Stephen, Appleby, and Carlisle, and these are all urban areas.

Let's have a look now at your first task.

Describe the location of the River Eden valley.

Jacob said, "I think it's useful to know its location within the UK," so you may need to use compass points, "and then more specific information.

For example, where it starts and finishes and the towns it flows through." Pause the video, and come back when you've had a go.

Your answer might have looked something like this: The River Eden valley is in the northwest of the UK.

It is bordered by the Lake District to the east and the Pennines to the west, and the river flows northwest for 145 kilometres.

Its source is in Black Fell Moss, and its mouth is at the Solway Firth, which flows into the Irish Sea.

The River Eden flows through Kirkby Stephen, Appleby, and Carlisle.

Well done if your answer was similar to this one.

Let's move now to the second learning cycle, what erosional landforms are found in the valley? If you can remember, erosional landforms are formed by the wearing away of the river's bed and banks, and there are four main ways in which a river can erode.

Hydraulic action, when air is trapped in the cracks of the river bank and forced apart.

Attrition, when sediment load in the river rubs together to form smaller and smaller particles.

Abrasion, when the scraping of material along the beds in the bank of the river wear it away.

And solution, when certain things will dissolve in the water.

These processes of erosion can create distinct landforms, such as this one, a V-shaped valley, we can see there, interlocking spurs, and waterfalls.

Hell Gill Beck is an example of a V-shaped valley on the River Eden.

It's found in the upper course.

We've used a 3D visualisation on Esri's Geography Visualiser to show you what Hell Gill Beck looks like.

A V-shaped valley is created by the vertical erosion as the river cuts into the bedrock.

If you can remember, up in the upper course of a river, vertical erosion is dominant.

And this vertical erosion, together with the weathering of the valley sides, creates this steep-sided, V-shaped valley.

This shows an OS map with Hell Gill Beck, the V-shaped valley marked on it.

We can identify it by seeing that the contour lines are very close together, showing the very steep gradient of the valley sides.

And the contour lines, if you look closely, have a V shape in the cross-section, which shows the shape of the valley.

Let's have a little check now for you.

What erosional landform is found on this OS map extract of the River Eden? Pause the video, and come back when you've had a go.

Hopefully you remembered it was Hell Gill Beck and you could identify it.

You might have identified it by using a grid reference, 7997.

Hell Gill Force is found in the upper course of the River Eden in the Mallerstang Valley, and we can see here a brilliant image of this waterfall.

It has formed as the river flows across a change in geology.

So we've got limestone and sandstone.

The limestone is more resistant to erosion than the softer sandstone.

And as a result, the river has eroded the softer rock, forming a step in the river channel.

So as the river has flowed over these two adjacent rocks, it's eroded the sandstone more quickly and created this step.

Below the water valley, there is a steep-sided gorge left behind as the waterfall has retreated up the valley.

We can see there it's pointing into the steep-sided gorge, the vertical sides of the gorge.

How do waterfalls form? Let's think back.

Hell Gill Beck erodes the softer, less resistant sandstone more quickly than the harder, more resistant limestone, and that creates a step in the riverbed.

Over time, this erosion continues, and the Hell Gill Beck will flow over this step.

Hydraulic action and abrasion erodes the softer rock below, and this creates a deeper area known as the plunge pool.

Over time, the harder limestone is undercut.

It's no longer supported by the softer rock, and eventually it will collapse.

This rock collapses into the channel, and it contributes to the erosion of the softer sandstone through abrasion.

As Hell Gill Force retreats, it's left behind a steep-sided gorge downstream, which the river continues to run through.

Let's have a check now then.

Why does the River Eden have a waterfall in the upper course? Is it A, because river velocity increases? Is it B, because there's a change in bedrock geology? Or is it C, human activity is leading to land use change? Pause the video and make your decision.

Hopefully you said it was a change in bedrock geology.

If you remember, Hell Gill Beck is flowing over soft sandstone and harder limestone, and this results in the formation of a waterfall.

Let's have a look at your second task.

Can you name an example of an erosional landform found in the upper course of the Eden Valley? And can you explain how the landform is created? So think back over what we've looked at.

Could you use a V-shaped valley perhaps, or a waterfall? Make your decision, and come back when you're ready.

You may have chosen a waterfall, and your answer might have included this: Hell Gill Force is a waterfall found in the upper course of the River Eden in the Mallerstang Valley.

You might have written this to explain how it's created: The softer sandstone rock erodes more quickly than the harder limestone rock through hydraulic action and abrasion.

This creates a step in the riverbed, which, over time, the river forms a vertical drop as the softer sandstone continues to erode and the harder limestone forms a ledge.

The water falls over the edge, creating a plunge pool at the base due to the force of the falling water.

The waterfall slowly retreats upstream as the harder limestone rock is undercut and collapses, creating a gorge.

Well done if you've managed to explain that formation correctly.

Let's move now to our third learning cycle, what depositional landforms are in the valley? So let's think.

Deposition is when a river drops the sediment, such as silt, sand, and gravel that it's been carrying.

And this occurs where the river loses energy.

This can be due to a decrease in river velocity, so the speed, or the river discharge.

River landforms created by deposition are commonly found in the middle and lower course of the river.

And we can see here on this OS map extract of the River Eden in its lower course, we have meanders, we've got a floodplain, and we've got an estuary, all depositional landforms. So meanders form due to the process of lateral erosion, so side-to-side erosion, in the middle course of the river.

And we can see here we've got lots of meanders on the River Eden near to Appleby and Westmorland, which is in the middle course of the river.

We have here a meander loop, and we can see that the river velocity is fastest on the outside of the bend.

So where the river velocity is fastest, we get erosion.

So the river erodes banks on the outside of the bend because it's got more energy.

River velocity is slower on the inside of the bend, and so the river deposits sediment on the inside of the bend because it has less energy.

The key at the bottom shows you that where we have the brown areas on the outside of the bend, we have erosion, and where we have deposition on the inside of the bend where the river is slower.

Think, let's have a little check now and a think.

Which of these statements correctly explain how meanders develop? Is it A, river velocity is faster on the outside of the bend? Is it B, the river erodes banks on the inside of the bend as the river has more energy? Is it C, river velocity is slower on the outside of the bend? Or is it D, the river deposits sediments on the inside of the bend as it has less energy? Pause the video, read them through again, and think carefully which one is correct.

Hopefully you identified that the first statement, river velocity is faster on the outside of the bend, and the fourth statement, the river deposits sediment on the inside of the bend as it has less energy, is correct.

Well done.

If we were to use statement B, the river erodes banks on the inside of the bend as the river has more energy, we'd need to change inside to the outside of the bend.

And if we were to use C as the correct answer, we'd need to say that river velocity is faster on the outside of the bend.

Well done.

So, the River Eden meanders through its middle and lower course near to Carlisle, and we can see here those floodplains north of Carlisle.

During high discharge events, it floods onto the surrounding flat land.

And when the river floods, it deposits lots of silt and clay over these wide, flat areas, which create these floodplains over time.

These areas are often very fertile due to the silt, and they're commonly used for farming.

The River Eden meets the Solway Firth at its mouth, and it forms an estuary.

So as the river flows out into the Solway Firth, its velocity decreases, causing the river to deposit its load of silt and sand.

And the deposited sediment builds up in layers, which forms mudflats, and you can see those mudflats on the Solway Firth.

Check for you now.

What and where are these depositional landforms on the River Eden? Pause the video, and come back when you've decided.

Hopefully you recognised it as the mudflats on the Solway Firth and the floodplains north of Carlisle, both landforms caused by deposition in the lower course of the river.

Right, let's have another check for you here.

Identify four depositional landforms on this OS map extract of the River Eden.

Pause the video, and come back when you're ready.

Did you get mudflats, the estuary, floodplains, and meanders? If so, well done.

Right, your last task for today's lesson, can you name an example of a depositional landform found in the River Eden valley? And then can you explain how that landform is created? So you might want to pick meanders or floodplains or even mudflats.

Have a go, and come back when you've finished.

Your answer might have included this: Floodplains can be found to the north of Carlisle as the river meanders through its lower course.

And your answer explaining its creation could read something similar to this: In the Eden Valley, the River Eden sometimes floods when there is heavy rainfall.

During a flood, the river spreads out over the surrounding land and loses energy.

As the water slows down, it deposits sediment like silt, sand, and clay across the valley floor.

Over time, repeated floods build up layers of sediment, making the land flat and fertile.

And this process creates a wide, flat floodplain, which is typical in the lower course of the river, such as near Carlisle.

Well done if your answer was something similar to that.

Let's have a look now at a review of today's lesson.

So, the River Eden valley is located in the northwest of England, and it flows for 145 kilometres through Kirkby Stephen, Appleby, and Carlisle.

Its source is on Black Fell Moss, and its mouth flows into the Irish Sea.

It has erosional landforms in its upper course, including a V-shaped valley, Hell Gill, and a waterfall, Hell Gill Force.

It has depositional landforms in its middle and lower course, including meanders across floodplains near to Carlisle, and an estuary as the river flows out into the Solway Firth.

Well done.

I hope you now feel that you can confidently describe and explain the erosional and depositional landforms found on the River Eden in the northwest of England.

Well done.

I look forward to seeing you all again soon.