Glaciation

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Lektionsnotizen

Ice Ages and Glaciers

An ice age is a period when ice covers large parts of the Earth's surface, including areas that are now ice-free.
During past ice ages, ice extended over much of the UK, shaping the landscape we see today.
Glaciers are persistent bodies of ice that form where snow accumulates faster than it melts over many years.
Today, glaciers cover about 10% of Earth's land surface, mostly in polar regions and high mountains.
Most glacial ice is stored in vast ice sheets in Antarctica and Greenland.

How Glaciers Form and Move

A glacier forms where the accumulation of snow exceeds ablation (melting and evaporation) over many years.
Over time, snow is compressed into dense ice that behaves like a slow-moving river of ice.
Glaciers move under their own weight, flowing downhill due to gravity.
As they move, glaciers undergo ductile and brittle deformation, creating features like crevasses and seracs.
The process of glacier growth and flow is called glaciation.

Glacial Erosion

Glaciers erode the landscape in two main ways: plucking and abrasion.
Plucking occurs when meltwater freezes onto rocks, and as the glacier moves, it pulls pieces of rock away.
Abrasion is the scraping of rock fragments embedded in the ice against the bedrock, smoothing and wearing it down.
Erosion by glaciers creates distinctive landforms such as corries, arêtes, and U-shaped valleys.

Landforms of Glacial Erosion

A corrie (or cirque) is a bowl-shaped hollow on a mountainside, eroded by a glacier.
An arête is a sharp, narrow ridge between two corries.
A pyramidal peak is a pointed mountain top formed where three or more corries erode back-to-back.
A U-shaped valley is a deep valley with steep sides and a flat floor, carved by a glacier.
A hanging valley is a smaller valley that meets a U-shaped valley high above its floor, often with a waterfall.
A ribbon lake is a long, narrow lake found on the floor of a U-shaped valley.

Glacial Deposition

Glaciers transport material eroded from the landscape and deposit it as moraine.
Moraine is the name for piles of unsorted rock and sediment deposited directly by a glacier.
Drumlins are smooth, oval-shaped hills of deposited material, often found in clusters.
Drumlins are sometimes called 'basket-of-eggs' topography because of their shape.

The Lake District: An Upland Glaciated Landscape

The Lake District in northwest England is a classic example of an upland area shaped by glaciation.
It contains many features of glacial erosion, such as corries, arêtes, and U-shaped valleys.
The long, narrow lakes of the Lake District are examples of ribbon lakes.
Glacial deposition has also left moraine and drumlins in some valleys.

Glaciers and the Environment

Glacial ice is the largest reservoir of fresh water on Earth, holding about 69% of the world's freshwater with ice sheets.
Glaciers store water as ice and release it as meltwater in warmer seasons, providing a vital water source.
Changes in glacial mass are sensitive indicators of climate change.
Melting glaciers contribute to sea level rise.

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1.What is a glacier?
Easy
- AA persistent body of natural ice that is constantly moving under its own weight
- BA large block of sea ice that floats on the ocean surface
- CA seasonal layer of snow that never turns to ice
- DA river of meltwater flowing down a mountain
2.Which process is the opposite of accumulation in a glacier's mass balance?
Easy
- AAblation
- BPlucking
- CAbrasion
- DCalving
3.Which of these is a landform of glacial erosion?
Medium
- ACorrie
- BDrumlin
- CMoraine
- DEsker
4.What is the name for a sharp ridge that separates two corries?
Medium
- AArête
- BPyramidal peak
- CHanging valley
- DRibbon lake
5.Which statement best describes how a glacier forms?
Medium
- ASnow accumulates over many years and is compressed into ice
- BMeltwater refreezes instantly at the base of a mountain
- CSea ice is pushed onto land by ocean currents
- DRainwater freezes in deep cracks in the rock
6.Which of the following is a depositional landform created by a glacier?
Medium
- ADrumlin
- BCorrie
- CArête
- DU-shaped valley
7.What is a pyramidal peak?
Medium
- AA sharp mountain peak formed where three or more corries erode backwards
- BA rounded hill of glacial till deposited at the snout of a glacier
- CA ridge of rock left between two glacial valleys
- DA lake formed in a hollow carved by a glacier
8.Which sequence correctly orders the stages of glacial erosion?
Medium
- ASnow accumulates, ice forms and moves, plucking and abrasion occur, landforms are created
- BIce melts, snow accumulates, landforms are created, plucking occurs
- CPlucking occurs, snow accumulates, ice forms, abrasion occurs
- DLandforms are created, ice moves, snow accumulates, abrasion occurs

Mehr Fragen

9.Which of the following are processes of glacial erosion? (select all that apply)
Medium
- APlucking
- BAbrasion
- CAblation
- DCalving
- EMoraine deposition
10.Which of the following are landforms of glacial erosion? (select all that apply)
Medium
- ACorrie
- BArête
- CPyramidal peak
- DDrumlin
- EMoraine
11.A glacier is a persistent body of ice that moves under its own weight.
Easy
True or false?
12.A hanging valley is a landform of glacial erosion.
Easy
True or false?
13.A ribbon lake is a landform created by glacial deposition.
Easy
True or false?
14.Match each glacial feature with its correct description.
Medium
- Corrie
- Arête
- Pyramidal peak
- Drumlin
- A bowl-shaped hollow on a mountainside
- A sharp ridge between two corries
- A sharp mountain peak formed by three or more corries
- A mound of glacial till deposited under a glacier
15.Put these stages of glacial erosion in the correct order.
Medium
- Snow accumulates and compresses into ice
- The glacier moves downhill under gravity
- Plucking and abrasion erode the underlying rock
- Landforms such as corries and U-shaped valleys are created
16.Which of the following statements about ice ages and the extent of ice over the UK are correct? (select all that apply)
Medium
- ADuring ice ages, ice sheets covered large parts of the UK.
- BIce ages are periods when global temperatures are warmer than today.
- CThe last ice age in the UK ended thousands of years ago.
- DGlaciers in the UK currently cover most of the land surface.
- EIce ages have occurred multiple times in Earth's history.
17.Which of the following best describes the process of glacial plucking?
Medium
- AA glacier freezes onto rock and pulls pieces away as it moves.
- BA glacier scrapes rock with debris embedded in its base.
- CA glacier melts and deposits material it was carrying.
- DA glacier cracks under pressure, forming crevasses.
18.Match each glacial landform with the correct description.
Medium
- Corrie
- Arête
- Pyramidal peak
- U-shaped valley
- A bowl-shaped hollow on a mountainside
- A sharp ridge between two corries
- A pointed mountain top formed by several corries
- A valley with a flat floor and steep sides
19.Put the following stages in the formation of a U-shaped valley in the correct order.
Medium
- A glacier forms in a pre-existing V-shaped river valley.
- The glacier erodes the valley sides and floor by plucking and abrasion.
- The glacier retreats, leaving a wide, flat-floored valley with steep sides.
- The valley is deepened and widened by the moving ice.
20.Which of the following are characteristics of glacial deposition? (select all that apply)
Hard
- AIt creates moraine.
- BIt creates drumlins.
- CIt involves plucking.
- DIt involves abrasion.
- EIt occurs when ice melts and drops material.
21.A hanging valley is a tributary valley that is left high above the main valley floor after glaciation.
Easy
True or false?
22.Which of the following best explains how a ribbon lake forms?
Medium
- AA glacier erodes a deep section of a valley, which later fills with water.
- BA glacier deposits a ridge of material across a valley.
- CA glacier melts and leaves a block of ice that forms a hollow.
- DA river erodes a deep gorge after the ice retreats.
23.Match each glacial term with its correct definition.
Medium
- Glaciation
- Glaciology
- Cryosphere
- Ablation
- The process of glacier establishment, growth and flow
- The study of glaciers
- The part of Earth where water is frozen
- The loss of ice and snow from a glacier
24.Which of the following is the main reason a glacier forms in a particular place?
Easy
- ASnow accumulation exceeds melting and evaporation over many years
- BThe temperature is always below freezing
- CThere is a large body of water nearby
- DThe area receives very little snowfall
25.Why does glacial ice appear blue?
Medium
- ABecause water molecules absorb other colours more efficiently than blue, and air bubbles are squeezed out
- BBecause the ice reflects the blue of the sky
- CBecause of the presence of blue minerals in the ice
- DBecause the ice is very cold
26.Which statement best explains why glaciers are considered sensitive indicators of climate change?
Medium
- ATheir mass changes in response to long-term changes in precipitation, temperature and cloud cover
- BThey only exist in very cold places
- CThey are made of fresh water
- DThey move very slowly
27.Which of the following best describes the difference between an ice sheet and an ice cap?
Medium
- AAn ice sheet is larger than 50,000 km², while an ice cap is smaller than 50,000 km²
- BAn ice sheet is found only in the Arctic, while an ice cap is found only in the Antarctic
- CAn ice sheet is made of sea ice, while an ice cap is made of glacial ice
- DAn ice sheet flows faster than an ice cap
28.Which of the following is a consequence of glacial meltwater in temperate mountain regions?
Hard
- AIt provides a water source for plants, animals and human uses, especially when other sources are scarce
- BIt causes the glacier to grow larger
- CIt increases the salinity of the oceans
- DIt prevents the formation of glacial landforms
29.Which of the following statements about the global distribution of glaciers are correct? (select all that apply)
Medium
- A99% of glacial ice on Earth is contained within ice sheets in the polar regions
- BGlaciers are found on every continent including the Australian mainland
- CBetween 35°N and 35°S, glaciers occur only in the Himalayas, Andes, and a few high mountains
- DPakistan has more than 7,000 known glaciers, the most outside the polar regions
- EGlaciers cover about 10% of Earth's land surface
30.Which of the following are ways in which glaciers move? (select all that apply)
Hard
- ADuctile deformation
- BBrittle deformation
- CSliding over the ground
- DEvaporation
- ECondensation
31.Glaciers can form on the surface of freezing lakes and seas.
Easy
True or false?
32.If both the Antarctic and Greenland ice sheets melted, global sea levels would rise by over 70 metres.
Easy
True or false?
33.Put the following stages in the formation of a corrie in the correct order.
Medium
- Snow accumulates in a hollow on a mountainside
- The snow compresses into ice
- The ice moves downhill by rotational flow
- The ice plucks and abrades the back wall and floor
- The ice melts, leaving a bowl-shaped hollow
34.A satellite image of Antarctica shows an ice sheet covering about 13.2 million km², while the surrounding ocean is frozen in winter. Which statement best explains why the frozen ocean is not classified as a glacier?
Medium
- ASea ice forms on the surface of freezing water, whereas glaciers originate only on land.
- BSea ice is too thin to move under its own weight, whereas glaciers are kilometres thick.
- CSea ice contains too much trapped air to be considered ice, whereas glaciers contain no air.
- DSea ice melts every summer, whereas glaciers never melt at all.
35.A student reads that the Antarctic ice sheet has an average thickness of 2,100 m and covers nearly 13 million km². Which conclusion is best supported by these figures?
Medium
- AAntarctica holds a very large volume of fresh water locked up as ice.
- BAntarctica is the only place on Earth where glaciers exist.
- CThe Antarctic ice sheet is thinner than most valley glaciers.
- DAntarctic ice is mostly sea ice rather than land-based ice.
36.A report states that glaciers hold about 69% of the world's fresh water together with ice sheets. Which of the following is the most direct consequence of this for people?
Medium
- AMelting glaciers can affect water supply for plants, animals and human use.
- BGlaciers provide most of the world's sea water for desalination.
- CGlaciers store water only in winter and release none in summer.
- DGlaciers have no effect on global sea level.
37.A map of a glaciated valley shows a small lake sitting on the valley floor behind a mound of till. A tributary valley joins the main valley high above the lake. Which pair of features is shown?
Medium
- AA ribbon lake and a hanging valley
- BA corrie and an arête
- CA drumlin and a pyramidal peak
- DAn ice shelf and an ice stream
38.
A table shows the number of known glaciers in three areas:
Area Known glaciers
Pakistan more than 7,000
New Zealand several thousand
East Africa a few high mountains
Which statement is best supported by this table?
Medium
- APakistan has more glacial ice than any other country outside the polar regions.
- BPakistan has more glaciers than Antarctica.
- CGlaciers are found only in the Himalayas.
- DEast Africa has no glaciers at all.
39.A geography textbook says: 'Glaciers cover about 10% of Earth's land surface.' Which of the following is the best interpretation of this statement?
Medium
- AAbout one tenth of the land on Earth is covered by glaciers at present.
- BGlaciers cover about one tenth of the world's oceans.
- CGlaciers covered 10% of the land during the last ice age but none today.
- DGlaciers cover 10% of each continent, including Australia.
40.A glacier can form on the surface of a freezing lake or sea.
Easy
True or false?
41.What is the term for a bowl-shaped hollow on a mountainside formed by glacial erosion?
Easy
42.What is the name of the process where a glacier freezes onto rock and pulls pieces away as it moves?
Medium
43.Approximately what percentage of Earth's land surface is covered by glaciers?
Medium
44.How many known glaciers are there in Pakistan?
Medium
45.Complete the sentence about glacial erosion.
Easy
A glacier erodes the land by ____ and ____.
46.Name the three main landforms of glacial erosion in the Lake District.
Medium
The three main landforms are ____, ____, and ____.
47.What is the name for a mound of till deposited by a glacier?
Medium
48.What is the term for the process by which a glacier forms, grows and flows?
Medium
49.Approximately what percentage of the world's freshwater is held in glaciers and ice sheets?
Medium
50.Complete the sentence about glacial ice sheets.
Medium
The only two ice sheets on Earth today cover most of ____ and ____.
51.How many known glaciers are there in Pakistan? Give your answer as a number.
Medium
52.Name the term for a large piece of glacial ice that has broken off and is floating in the sea.
Medium
53.Explain how a glacier forms and moves.
Hard
54.Explain how the movement of a glacier can change the landscape.
Hard
55.Explain why glacial ice appears blue.
Hard
56.Approximately what percentage of Earth's land surface is covered by glaciers?
Medium
- A12 %
- B9 %
- C11 %
- D10 %
57.How many known glaciers are there in Pakistan?
Medium
- A6300
- B7000
- C7700
- D8400
58.Approximately what percentage of the world's freshwater is held in glaciers and ice sheets?
Medium
- A69 %
- B76 %
- C62 %
- D83 %
59.How many known glaciers are there in Pakistan? Give your answer as a number.
Medium
- A6300
- B8400
- C7000
- D7700

Lernnotizen

## Glaciation — KS3 Revision Notes ### Ice ages and ice over the UK - During ice ages, huge ice sheets covered much of the UK. - Ice sheets are continental glaciers larger than 50,000 km². They are several kilometres deep and hide the land beneath; only **nunataks** stick out above the ice. - Today only two ice sheets exist: Antarctica and Greenland. If both melted, global sea levels would rise by over 70 m. ### How glaciers form and move - A glacier is a persistent body of natural ice that is constantly moving under its own weight. - It forms where **accumulation of snow exceeds ablation** over many years, often centuries. - Ice flows and deforms under gravity, by both ductile and brittle deformation, creating surface features such as **crevasses** and **seracs**. - Glaciers cover about 10% of Earth's land surface and hold about 69% of the world's freshwater with the ice sheets. - Glacier ice looks blue because water molecules absorb other colours more efficiently than blue, and because air bubbles (which make ice white) are squeezed out by pressure. ### Glacial erosion - **Plucking** — ice freezes onto and pulls away rock. - **Abrasion** — ice scrapes underlying rock and debris, wearing it down. - These processes create glacial landforms. ### Landforms of erosion - **Corries** (cirques) — armchair-shaped hollows on mountainsides. - **Arêtes** — narrow, sharp ridges between corries. - **Pyramidal peaks** — pointed peaks where several corries cut back. - **U-shaped valleys** — broad, steep-sided valleys carved by ice. - **Hanging valleys** — smaller valleys left high above the main valley floor. - **Ribbon lakes** — long, narrow lakes in glaciated valleys. ### Deposition landforms - **Moraine** — material deposited directly by a glacier. - **Drumlins** — smooth, rounded mounds of deposited material. ### The Lake District - An upland glaciated landscape in England, showing corries, arêtes, pyramidal peaks, U-shaped valleys, hanging valleys and ribbon lakes. ### Key idea - Glacial mass is affected by long-term climate (precipitation, mean temperature, cloud cover), so glaciers are sensitive indicators of climate change and affect sea level. ### Key terms - **Glacier** — a persistent body of natural ice, a form of rock, constantly moving under its own weight. - **Glaciation** — the process of glacier establishment, growth and flow. - **Glaciology** — the study of glaciers. - **Cryosphere** — the frozen parts of the Earth system, of which glaciers are important components. - **Ablation** — loss of ice and snow (e.g. by melting). - **Accumulation** — build-up of snow and ice. - **Nunatak** — a mountain peak protruding above an ice sheet. - **Ice sheet / continental glacier** — glacial body larger than 50,000 km². - **Ice cap / ice field** — large body of glacial ice astride a mountain or range, under 50,000 km². - **Valley glacier (alpine/mountain glacier)** — a glacier that fills a valley. - **Ice shelf** — portion of an ice sheet or cap extending into water. - **Ice stream** — narrow, fast-moving section of an ice sheet. - **Tidewater glacier** — a glacier that terminates in the sea and calves icebergs. - **Calving** — breaking off of ice at the sea to form icebergs. - **Crevasse** — a crack in a glacier's surface. - **Serac** — a block or pillar of ice on a glacier. - **Plucking** — ice freezing onto and pulling away rock. - **Abrasion** — ice scraping and wearing down underlying rock. - **Corrie (cirque)** — armchair-shaped hollow eroded by ice. - **Arête** — narrow ridge between corries. - **Pyramidal peak** — pointed peak formed by several corries. - **U-shaped valley** — steep-sided valley carved by a glacier. - **Hanging valley** — smaller valley left above the main valley floor. - **Ribbon lake** — long, narrow lake in a glaciated valley. - **Moraine** — material deposited by a glacier. - **Drumlin** — smooth, rounded mound of glacial deposit.

Glacier: A persistent body of natural ice, a form of rock, that is constantly moving under its own weight.
Glaciation: The process of glacier establishment, growth and flow.
Glaciology: The area of study of glaciers.
Cryosphere: The frozen parts of the Earth system; glaciers are important components of it.
Accumulation: The build-up of snow and ice on a glacier.
Ablation: The loss of ice and snow from a glacier, for example by melting.
Ice sheet (continental glacier): A glacial body larger than 50,000 km², several kilometres deep, that obscures the underlying topography.
Ice cap or ice field: A large body of glacial ice astride a mountain, mountain range, or volcano, with an area less than 50,000 km².
Valley glacier (alpine or mountain glacier): A glacier that fills a valley.
Nunatak: A mountain peak that protrudes above the surface of an ice sheet.
Ice shelf: A portion of an ice sheet or ice cap that extends into water; tends to be thin with limited slopes and reduced velocities.
Ice stream: A narrow, fast-moving section of an ice sheet.
Tidewater glacier: A glacier that terminates in the sea, often calving icebergs.
Calving: The breaking off of pieces of ice as a glacier reaches the sea, forming icebergs.
Crevasse: A distinguishing surface feature of a glacier; a crack formed as the ice deforms.
Serac: A distinguishing surface feature of a glacier; a block or pillar of ice formed by deformation.
Plucking: A process of glacial erosion in which ice freezes onto and pulls away rock.
Abrasion: A process of glacial erosion in which ice scrapes and wears down underlying rock and debris.
Corrie (cirque): An armchair-shaped hollow on a mountainside eroded by ice.
Arête: A narrow, sharp ridge between two corries.
Pyramidal peak: A pointed mountain peak formed where several corries cut back.
U-shaped valley: A broad, steep-sided valley carved by a glacier.
Hanging valley: A smaller valley left high above the floor of the main glaciated valley.
Ribbon lake: A long, narrow lake found in a glaciated valley.
Moraine: Material deposited directly by a glacier.
Drumlin: A smooth, rounded mound of material deposited by a glacier.

Karteikarten

What is a glacier?

A glacier is a persistent body of natural ice that is constantly moving under its own weight. It forms where snow accumulation exceeds ablation over many years.

How does a glacier form?

A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. The snow compacts into ice under pressure.

What is the difference between accumulation and ablation?

Accumulation is the addition of snow and ice to a glacier, while ablation is the loss of ice through melting, evaporation, or calving.

What is the term for the process of glacier establishment, growth, and flow?

Glaciation.

What is glaciology?

Glaciology is the scientific study of glaciers and ice sheets.

What is an ice age?

An ice age is a period of long-term reduction in Earth's temperature, resulting in the expansion of ice sheets and glaciers. During ice ages, ice covered large parts of the UK.

What evidence is there that ice once covered parts of the UK?

Landforms of glacial erosion and deposition, such as corries, U-shaped valleys, and moraines, are found in upland areas like the Lake District, showing that ice covered these areas in the past.

What is plucking?

Plucking is a process of glacial erosion where meltwater freezes onto rock, and as the glacier moves, it pulls pieces of rock away.

What is abrasion?

Abrasion is the process where rocks and debris carried by a glacier scrape and wear away the bedrock beneath it.

What is a corrie?

A corrie (also called a cirque) is a bowl-shaped hollow on a mountainside, formed by glacial erosion. It often contains a small lake called a tarn after the ice melts.

What is an arête?

An arête is a narrow, sharp ridge of rock between two corries, formed by glacial erosion.

What is a pyramidal peak?

A pyramidal peak is a sharp, pointed mountain top formed when three or more corries erode back-to-back, leaving a pyramid-shaped summit.

What is a U-shaped valley?

A U-shaped valley is a valley with steep sides and a flat bottom, formed by glacial erosion. It contrasts with the V-shaped valleys formed by rivers.

What is a hanging valley?

A hanging valley is a smaller valley that meets a larger U-shaped valley high above its floor, often with a waterfall where the two meet.

What is a ribbon lake?

A ribbon lake is a long, narrow lake found on the floor of a U-shaped valley, formed where glacial erosion deepened a section of the valley.

What is moraine?

Moraine is the material (rock and sediment) that has been eroded and transported by a glacier and then deposited. Different types include lateral, medial, and terminal moraine.

What is a drumlin?

A drumlin is a smooth, oval-shaped hill made of glacial till, often found in groups. Its shape shows the direction of ice flow, with the steep side facing the direction from which the ice came.

Why is the Lake District an example of an upland glaciated landscape?

The Lake District contains many landforms of glacial erosion, such as corries, arêtes, and U-shaped valleys, which were created during past ice ages.

What is the difference between an alpine glacier and an ice sheet?

An alpine glacier forms on the crests and slopes of mountains, while an ice sheet is a vast continental glacier larger than 50,000 km² that covers the underlying landscape.

What is an ice cap?

An ice cap is a large body of glacial ice astride a mountain or mountain range, with an area less than 50,000 km².

What is a tidewater glacier?

A tidewater glacier is a glacier that terminates in the sea, where pieces of ice break off to form icebergs.

Why is glacial ice blue?

Glacial ice appears blue because water molecules absorb other colors more efficiently than blue, and because air bubbles that scatter white light are squeezed out by pressure.

What percentage of the world's freshwater is held in glaciers and ice sheets?

About 69% of the world's freshwater is held in glaciers and ice sheets.

How do glaciers indicate climate change?

Glacial mass changes are sensitive indicators of climate change because they respond to long-term changes in precipitation, temperature, and cloud cover.

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Area	Known glaciers
Pakistan	more than 7,000
New Zealand	several thousand
East Africa	a few high mountains