KS3 · Geography

How glaciers shape the land: erosion and deposition

A glacier looks like a frozen, motionless lump. It isn't. It's a slow-moving machine, so ride along and see what the ice is doing at every stop.

Ride along a glacier

Which glacial process acts where?

A schematic section of a glacier, drawn in four stops. It is not to scale. Pick a stop to see what is happening there.

Zone 1 of 4

Corrie back wall

Start at the top. Here rock breaks up because water regularly freezes and thaws. That is freeze-thaw weathering. During a glacial period it steepens the back wall of the corrie and adds debris.

  • Water regularly freezing and thawing
  • Rock breaks up
  • Debris added

Four stops, four jobs: weathering at the back wall, erosion beneath, transportation at the base and sides, deposition where the ice melts. The first three happen while the ice is still moving.

Two ways glaciers erode

PluckingvsAbrasion

Both remove rock. The difference is what does the removing.

Focus

How it removes rock

Plucking

Pulls chunks of rock from the bedrock as the glacier moves over it

Abrasion

Scrapes and wears away the surface beneath the glacier

The insight

Plucking takes whole chunks away; abrasion wears the surface down by scraping.

What does the work

Plucking

The glacier itself, pulling at the bedrock

Abrasion

Rocks and debris that the glacier is carrying

What kind of process

Plucking

Glacial erosion

Abrasion

Glacial erosion

Which idea sounds like yours?

When does ice change the land?

Two friends are arguing about a glacier. They can't agree on what it does and when.

Which of these is closest to what you think right now?
How sure are you?

Processes to landforms

Erosion, or carried and then deposited?

Sort each landform by how the glacier made it. Pick a landform, then pick a category, and read the reason.

Still to sort

Made by erosion (0)

The glacier carves through the landscape.

Where the line is: These are carved out of the land. They are not heaps of material the ice dropped.

Made by transportation and deposition (0)

The glacier carries eroded material and then deposits it.

Where the line is: These are made from material the glacier carried and then dropped.

7 of 7 still to sort.

Explain it in your own words

How does a glacier change a landscape?

Explain how a glacier changes a landscape. [4 marks]

0 words · your answer stays on this page and is not sent anywhere.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

How moving ice weathers, erodes, carries and dumps rock

What you need to know

  • Ice covered large parts of the UK in the past, and glacial processes have been responsible for shaping its landscape.
  • A glacier is a large mass of ice that forms on land and moves slowly due to gravity.
  • An ice sheet is a vast, continuous expanse of ice covering a very large area of land.
  • Have a goMaya says: "A glacier is a vast, continuous expanse of ice covering a very large area." Which of the two ice words is she really describing?

    An ice sheet, not a glacier.

    A glacier is a large mass of ice on land that moves slowly due to gravity. The vast, continuous expanse wording belongs to an ice sheet.

  • Freeze-thaw weathering is rock breaking up because water regularly freezes and thaws.
  • Plucking is glacial erosion: the glacier pulls chunks of rock from the bedrock as it moves over it.
  • Abrasion is glacial erosion too: rocks and debris the glacier carries scrape and wear away the surface beneath.
  • Have a goA glacier removes rock in two ways. Which one only works if the glacier is carrying rocks and debris?

    Abrasion.

    Abrasion scrapes with the rocks and debris the ice carries, whereas plucking pulls chunks straight out of the bedrock.

  • Glaciers transport soil and rock, carried unsorted at the base and sides of the ice.
  • When a glacier melts it can no longer carry its load, so it deposits glacial till: a mixture of unsorted debris.
  • Have a goA glacier has just melted. Is the heap it leaves more like a neatly sorted sock drawer, or the messiest bedroom floor ever?

    The messy floor: a jumble of unsorted soil and rock.

    The glacier carries its load unsorted, so the glacial till it deposits is unsorted too.

  • Ice changes the land through continuous erosion, transportation and deposition, not just when it melts.
  • Erosion creates corries, arêtes, pyramidal peaks and glacial troughs; carried then deposited material creates moraines, drumlins and erratics.

The big picture

Glaciers are slow-moving machines. Ice once covered large parts of the UK, and while it moved it broke rock up, pulled it away, scraped the ground, carried a mixed-up load and finally dumped it as till when it melted. All of that shaped the landscape.

Key points

1Freeze-thaw weathering, erosion, transportation and deposition are all glacial processes, and they act at different places along a glacier.
2Glacial erosion happens by plucking (pulling chunks of bedrock away) and abrasion (carried rocks and debris scraping the surface beneath).
3Soil and rock are carried unsorted at the base and sides, then deposited as glacial till when the glacier melts.
4The ice is shaping the land all the time it moves, not only when it melts.
5Erosion creates corries, arêtes, pyramidal peaks and glacial troughs; deposition creates moraines, drumlins and erratics.

Worked example

Problem

Walking in a valley where a glacier used to be, you find a heap of soil and rock lumps jumbled together, with no tidy layers. Which glacial process left it there, and what is it called?

⚠ Watch out

Thinking a glacier only changes the land when it melts. The ice erodes and carries material all the time it moves, and melting is just when it deposits.

🧠

Memory hook

Shatter, pluck, scrape, carry, dump: then you are looking at till.

✓

Check yourself

Cover the page. Name the process at (1) the back wall, (2) beneath the ice, (3) the base and sides, (4) where the ice melts. Then say how the land changed before any melting.

Flashcards

(13)
What is a glacier?
A large mass of ice that forms on land and moves slowly due to gravity.
What is an ice sheet?
A vast, continuous expanse of ice covering a very large area of land.
What is freeze-thaw weathering?
The breaking up of rocks caused by water regularly freezing and thawing.
What does freeze-thaw weathering do to a corrie during a glacial period?
It steepens the back wall of the corrie and adds debris.
What is plucking?
When a glacier pulls chunks of rock from the bedrock as it moves over it.
What is abrasion?
When rocks and debris carried by a glacier scrape and wear away the surface beneath it.
What is transportation in a glacier?
Glaciers carry material such as soil and rock, unsorted, at their base and sides.
What is deposition?
When the glacier melts it can no longer carry material, so it drops the sediment it has been carrying.
What is glacial till?
A mixture of unsorted debris deposited by a melting glacier.
What is moraine?
An accumulation of unsorted debris, such as soil and rock, deposited by a glacier.
Outwash: what do you need to know?
It is named alongside till as part of glacial deposition. You only need to recognise the name.
Which landforms does glacial erosion create?
Corries, arêtes, pyramidal peaks and glacial troughs.
Which landforms come from carried material being deposited?
Moraines, drumlins and erratics.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

Learning with Lightbulb is opening soon

You can use this lesson now. Join the waitlist and we'll let you know when the full Lightbulb experience is ready.

Keep me posted

More KS3 Geography topics

See the full KS3 Geography curriculum →

How this lesson was checked. This KS3 Geographylesson was published through Lightbulb Learning's human-designed editorial process — the educational standards, accuracy rules and publication checks it must pass were authored and approved by Philip Halpin. It passed subject-specific assessment, automated educational checks and technical publication verification before going live (publication checks completed 9 October 2026). Published pages are monitored, human spot-checking is ongoing across the lesson library, and anything found wrong is corrected or withdrawn. How our lessons are made and checked. Spotted a mistake? Email hello@lightbulblearning.co and we'll review it.