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Geography May 2018 > Glaciation > Flashcards

Glaciation Flashcards

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1
Q

When did the the Ice Age in Britain begin?

A

1,000,000 years ago.

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2
Q

When did the the Ice Age in Britain end?

A

20,000 years ago.

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3
Q

What happened during the Ice Age in Britain?

A

During this temperatures fluctuated and ice advanced and retreated four times. The northern and eastern parts of the British Isles were covered in ice.

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4
Q

The ice that covered nearly all of the UK grew from what ice sheet?

A

The Scandinavian Ice sheet which was centred on Sweden and Finland.

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5
Q

Large glaciers also formed in mountain ranges around Europe, give examples.

A

The Alps and Pyrenees.

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6
Q

During the last Ice Age how much of the earth’s surface was covered in ice?
When did it begin?

A

30% and 2,000,000 years ago.

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7
Q

What are Ice advances called?

A

They are called glaciations, the last one began 70,000 years ago and ended 10,000 years ago.

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8
Q

What are warm periods between glaciations and what happens?

A

They are called ‘Interglacial’ periods and this is when temperatures can be higher than they are to-day.

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9
Q

What is an ice sheet?

A

Ice sheets are masses of ice which cover large areas of a continent.

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10
Q

What are some suggestions of what caused the Ice Age?

A
  • Variations in the sun’s energy.
  • Changes in the earth’s orbit so that for certain periods we were further from the sun.
  • A massive volcanic eruption-the ash and dust blocking the suns energy.
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11
Q

What is a glacier?

A

A glacier is a large river of ice. They move slowly downhill and change the shape of land by erosion and deposition.

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12
Q

What happens when snow layers are built up year after year?

A

The lowest layers are compacted into ice and this gradually moves down slope under the force of gravity.

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13
Q

Where are the biggest glaciers currently found?

A

They are found in Antarctica and Greenland.

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14
Q

What is an ice cap?

A

Ice caps are extensive sheets of ice. Technically, they cover an area smaller than 50,000 km2, anything bigger called an Ice sheet. Eg, the Greenland Ice Sheet.

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15
Q

Give two facts on the Mer de Glace glacier.

A
  • The Mer de Glace is 7km long, 1200 metres wide and up to 200 metres thick.
  • Ice moves within the glacier at a speed of about 70 metres each year.
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16
Q

The glacier system consists of what four things?

A

Inputs, transfers (flows), stores and outputs.

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17
Q

What is an input?

A

An input comes from avalanches from the sides of a glacier but mainly from precipitation as snow.

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18
Q

What is a store?

A

Overtime snow accumulates and is compressed into ice. The water held in storage is the glacier.

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19
Q

What are transfers/flows?

A

Under the force of gravity, the glacier flows downhill.

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20
Q

What is an output?

A

Meltwater is the main output from the glacier, along with some evaporation.

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21
Q

What is the accumulation zone?

A

All glaciers move slowly downhill, the highest part, where snow falls and turn to ice is called the accumulation zone. It is extremely cold here, lots of snow falls and the temperature rarely rises above rising.

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22
Q

What is the ablation zone?

A

As the glacier moves downhill it starts to warm up and melt. The place where the glacier starts to melt is known as the ablation zone.

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23
Q

How many years can a snowflake spend up to before it melts?

A

It can spend up to 400 years before it melts.

24
Q

How can glacial ice appear solid and behave like a fluid.

A

When it pushes up against an object it is solid enough to erode it but fluid enough to move around it like water in slow motion.

25
Q

What does meltwater do in a glacier?

A

Meltwater lubricates the glacier and help it to slip along the valley bottom, often refreezing around rocks and carrying them with it. This movement can change the shape of a valley in which the glacier moves.

26
Q

What are the two main processes of glacial erosion?

A

Plucking and Abrasion.

27
Q

What is plucking?

A

Plucking is the tearing away of blocks of rock which have become frozen onto the base and sides of a glacier.

28
Q

What is abrasion?

A

Abrasion is the wearing away of rocks at the base and sides of the glacier by the scouring action of ice containing rocks plucked by the Earth’s surface. The ice acts rather like an enormous sheet of sand paper.

29
Q

What is freeze thaw weathering?

A

Freeze thaw weathering is a type of weathering where water repeatedly freezes and puts pressure on rocks to break them down. It happens in areas where the temperature regular rises above and falls below freezing.

30
Q

What is the process of freeze thaw weathering?

A
  • Water collects in cracks in rocks.
  • Overnight the water freezes and expands.
  • This expansion puts stress and pressure on the sides of the crack.
  • During the day when the temperature rises the ice thaws/melts and contracts.
  • This happens over and over again and eventually the rock cracks open.
31
Q

What is a corrie?

A

A corrie is a steep sided hollow high up in the mountains. Often described as ‘armchair shaped.’

32
Q

How is a corrie formed?

A

Snow and ice collects in the hollows, as ice moves down the mountain, it erodes the back and bottom of the hollow, a deep bowl shaped hollow begins to form.

33
Q

What is a tarn?

A

A tarn is a lake that forms in a corrie.

34
Q

What is an arete?

A

An arete is steep rocky ridges between two corries.

35
Q

What is a pyramidal peak/how is it formed?

A

A Pyrimadal peak forms when 3 or more corries form around a mountain. They cut back to leave a ‘horn’ or ‘Pyramidal Peak’ in the middle.

36
Q

How are U shaped valleys formed?

A
  • As the glacier flows down an old V-shaped valley

- As the glacier flows it erodes the sides and bottom of the valley by abrasion and plucking.

37
Q

What is a ribbon lake?

A

A ribbon lake is a long, narrow lake found on the valley floors.

38
Q

How is a ribbon lake formed?

A

A ribbon lake is formed when the glacier retreats, the meltwater fills the areas that have been cut out by the glaciers erosion.

39
Q

What are striations?

A

Striations are scratches cut into bedrock by process of glacial abrasion.

40
Q

Why are striations important?

A

Striations are important as they show us the direction the ice moved.

41
Q

What are crevasses?

A

Crevasses are large cracks in the ice. They are usually a few metres wide and several metres deep.

42
Q

How are crevasses formed?

A

Crevasses are formed when the ice is forced to stretch and then crack as it flows down a steep slope.

43
Q

Where can you find the deepest crevasses and how deep are they?

A

The deepest crevasses are found in Antartica and are over 30 metres deep.

44
Q

When does glacial deposition occur?

A

Glacial deposition occurs when a rise in temperature causes ice to melt and the glacier is no longer able to carry as much material so it dumps it.

45
Q

Where would the material be deposited?

A

The material would be deposited either on the valley floors or across lowlands at the foot of highland areas by the ice or meltwater streams.

46
Q

What is a moraine?

A

A moraine is a type of material that is created when a glacier deposits the material (till) that it has been transporting.

47
Q

What is till?

A

Till is a mixed angular material formed on the valley floor.

48
Q 
What are the differences between the following moraines:
Medial moraine?
Lateral moraine?
Ground moraine? 
Terminal moraine?
Recessional moraine?
A

Medial moraine-material that is carried in the middle of the glacier.

Lateral moraine-material deposited at sides of glacier.

Ground moraine-material deposited on the ground and underneath the glacier.

Terminal moraine-material deposited at the furthest point the glacier reached. Before it started to melt.

Recessional moraine-material at the snout as the glacier retreats.

49
Q

What are erratics?

A

Erratics are large boulders that have been carried by the glacier and then deposited in an area of different rock type, so that they look completely out of place. Erratics can have originated from hundreds of miles away.

50
Q

What are drumlins?

A

Drumlins are smooth mounds of deposited material that are formed parallel to the direction of the movement of the glacier. It is thought that they were formed when ice became overloaded with sediment.

51
Q

How is a drumlin formed and describe it?

A

Drumlins are formed from boulder clay.
They are elongated (stretched out) features. Egg shaped hills that can reach a kilometre or more in length, 500 metres or so in width and over 50 metres high. One end is quite steep, whilst the other end tapers away to ground level. The stoss end is the steeper of the two ends and used to face into the ice flow.

52
Q

During the Ice Age there were four main stages of Ice advance in Northern Ireland, what were they.

A
  1. An ice sheet in Donegal which moved North Eastwards.
  2. A Scottish ice sheet moved across Northern Ireland from the East.
  3. An Irish Ice sheet which moved East and North.
  4. A re-advance of Scottish Ice which affected the coastal areas of East and North Antrim.
53
Q

What is an avalanche?

A

An avalanche is a mass of snow and ice that moves rapidly down a mountainside. They are very sudden and generally do not last longer than a few minutes. They are extremely powerful!

54
Q

How does an avalanche occur?

A
  • When the snow melts it turns to water.
  • If temperatures drop low enough the water may freeze again and turn to ice. This creates a slide surface.
  • Snow will build up on top of this but will move or slide easily if enough pressure is put on it.
55
Q

What are the affects of an avalanche?

A
  • People can die or get injured
  • Property damage
  • Can cause roads to close
56
Q

How can avalanches be reduced?

A
  • Using radar technology to reduce it
  • Start an avalanche with explosive before
  • Ski-checking

Geography May 2018 (3 decks)

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