GeographyRivers and coasts30 min★★ difficulty

Coasts: erosion, deposition and a changing landscape

Some stretches of English coast retreat by more than a metre a year. This lesson explains how waves build and destroy coastal landscapes, and how decisions about defending the coast create winners and losers.

Part of your national curriculum

Human and physical geography: Understand how geographical processes interact to create distinctive human and physical landscapes that change over time
Human and physical geography: Understand rivers, coasts and glaciation and the physical processes that give rise to landscapes, and how they change over time

Lesson overview

What you'll learn in this lesson

Understand how geographical processes interact to create distinctive human and physical landscapes that change over time

Key learning points

• Two kinds of wave
• From headland to stack
• Sediment on the move
• Winners and losers

This lesson at a glance

30 minutes
19 parts to scroll through
4 quick checks
Marked quiz at the end
Gentle pace: short sittings with pauses

Words to know

geographicalprocessesinteractcreatedistinctive

Scroll down — the lesson carries on below

Part 1 of 19 · Discover5%

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Part 1 of 19

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Coasts: erosion, deposition and a changing landscape

An English teaching video on this topic from iNewittAll. Watch it, then scroll down for the lesson.

In a nutshell

Understand how geographical processes interact to create distinctive human and physical landscapes that change over time

What you already know

Part 2 of 19

Before we start

What you already know

You should know the four erosion processes from the rivers lesson.

Recap: Rivers: processes and landforms

Key words

Part 3 of 19

Key words

Words you'll need today

Destructive wave: A steep, high-frequency wave with a strong backwash that removes sediment.
Constructive wave: A low, long wave with a strong swash that builds a beach.
Longshore drift: The zig-zag movement of sediment along a coast by angled waves.
Spit: A long ridge of deposited sand or shingle extending out from the coast.
Managed retreat: Deliberately allowing the sea to flood low-value land.

Learning cycle

Part 4 of 19

Learning cycle 1 of 2

Waves that destroy and build

A short piece of teaching, then a check to make sure it has landed.

Explore the idea

Part 5 of 19

Learn

Two kinds of wave

Wave energy depends on wind strength, wind duration and fetch, the open distance the wind has blown over. Destructive waves are steep and frequent with a powerful backwash, so they drag sediment out to sea and erode. Constructive waves are lower and less frequent with a strong swash, so they push sediment up the beach and build it. The same beach can be eroded in a winter storm and rebuilt over a calm summer.

Explore the idea

Part 6 of 19

Learn

From headland to stack

Where rock hardness varies along a coast, softer rock erodes back into bays while harder rock stands out as headlands. Waves then attack the headland's weaknesses: a crack widens to a cave, the cave erodes through to form an arch, the arch roof collapses to leave a stack, and the stack is undercut to a stump. Wave-cut platforms are left at the base as the cliff retreats.

Quick check

Part 7 of 19

Quick check

Which wave type builds a beach?

Quick check

Part 8 of 19

Quick check

Put the sequence in order: cave, arch, stack, stump. Which comes third?

Reset break

Part 9 of 19

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now

Learning cycle

Part 10 of 19

Learning cycle 2 of 2

Managing a coast that moves

A short piece of teaching, then a check to make sure it has landed.

Explore the idea

Part 11 of 19

Learn

Sediment on the move

Waves usually approach at an angle, so swash carries sediment diagonally up the beach and backwash pulls it straight back down. The result, longshore drift, moves material along the coast. Where the coast changes direction or a river mouth interrupts it, sediment is deposited as a spit, which may curve and shelter a salt marsh behind it. Bars and tombolos form the same way.

Explore the idea

Part 12 of 19

Learn

Winners and losers

Hard engineering — sea walls, groynes, rock armour — protects specific places but is expensive and can starve the coast downdrift of sediment, so someone else erodes faster. Soft approaches such as beach nourishment and dune planting work with natural processes but need repeating. Managed retreat gives low-value land back to the sea to protect settlements elsewhere. Every choice involves cost, benefit and someone losing out, which is why coastal management questions ask you to judge, not just describe.

Quick check

Part 13 of 19

Quick check

Longshore drift happens because waves approach…

Quick check

Part 14 of 19

Quick check

One drawback of groynes is that they…

Common mix-ups

Part 15 of 19

Common mix-ups

Things people often get wrong

Groynes stop erosion everywhere — they trap sediment locally and often worsen erosion further along the coast.
Constructive waves are the bigger ones — they are lower and gentler; destructive waves are steep and powerful.
Coastlines are fixed lines on a map — they move, sometimes by metres a year.

Challenge round

Part 16 of 19

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

Challenge round

Part 17 of 19

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

Soft approaches such as beach nourishment and dune planting work with natural ____ but need repeating.

Mastery quiz

Part 18 of 19

Marked quiz

End of lesson quiz: Coasts: erosion, deposition and a changing landscape

6 questions, marked with the reasoning shown. No timer.

1. Fetch means…
2. Bays form where the rock is…
3. A spit often shelters…
4. Beach nourishment is an example of…
5. Managed retreat means…
6. Why do coastal management decisions create losers?

Lesson round-up

Part 19 of 19

Lesson round-up

Ready when you are

Quiz score

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Points this lesson

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Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Flooding on the River Calder

The town of Harbrook sits where a steep valley opens onto a flat floodplain. In December 2015, 120 mm of rain fell in 36 hours onto ground that was already saturated. The river rose 2.4 m in five hours, and 380 homes and 54 businesses flooded. Two roads and the railway closed for eleven days.

Geographers pointed to physical causes — steep slopes, impermeable rock, heavy rainfall — and human causes: moorland drained upstream, new housing built on the floodplain, and drains designed for smaller storms.

Since then the town has planted 40 hectares of woodland upstream, built leaky dams in small streams, and raised flood walls to 1.8 m. In the storm of 2020 the peak river level was 0.3 m lower and 40 homes flooded, not 380.

Written for Good Learning Co.

Reading questions

List two physical and two human causes of the 2015 flood.
Explain how planting woodland upstream lowers the river's peak level.
Using the figures, judge how successful the scheme has been. Quote data in your answer.

Case study notes
Writing
Write the place, the facts and the figures from this lesson so you can revise them later.
Half a page
Explain answer
Writing
Answer in full sentences, giving causes and effects. Use one figure or place name as evidence.
8–10 sentences
Map or sketch
Diagram
Draw the map, cross-section or field sketch with a key, title and labels, then photograph it.
1 map with a key
Data work
Working out
Plot your figures as a graph on paper and write one sentence about the pattern.
1 graph + 1 sentence

Write your answer, notes or working here

Saved as you type.

Photos of paper work, diagrams or working outHow many minutes did the written work take?

Part 1 of 19 · Watch & discover

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Understand how geographical processes interact to create distinctive human and physical landscapes that change over time
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Understand rivers, coasts and glaciation and the physical processes that give rise to landscapes, and how they change over time