Glaciation Flashcards

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1
Q

What is an ice age

A

When there is a period of time when thick ice sheets cover vast areas of land as the global temperature stays below 0°C

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2
Q

How long ago did ice cover 30% of land in the world

A

18,000 years ago

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3
Q

What was the temperature of the last ice age

A

The temp stayed below 0 which allowed the ice to remain on the land all year.

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4
Q

What is a glacier

A

A large body of ice moving down a slope or over a wide area of land.
Glaciers once covered large areas of the earth and shaped the landscape around them. The legacy of ancient glaciers lives on for example, in areas such as the Lake District.

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5
Q

What’s an example of a glacier in Europe

A

The Mer De Glace glacier in the French alps

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6
Q

What processes does glaciation affect

A

Erosion
Transportation
Deposition

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7
Q

How does a glacier form

A

They form in very cold places. Lots of snow falls but not all of it melts. This means that a lot of different layers of snow lie on top of each other.
The bottom layer of the snow got compressed by the top layers. This means the air is pushed out and the snow turns into ice forming a glacier.
The glacier gradually moves down the slope under the force of gravity.

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8
Q

What’s the difference between an ice sheet and a glacier

A

Masses of ice which cover large areas of a continent are called ice sheets.
Those which occupy mountain valleys are called valley glaciers

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9
Q

What European countries were covered in ice during the last ice age

A

Iceland
All of Ireland
Norway
Sweden
Finland
Denmark

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10
Q

What are interglacials

A

We call times with large ice sheets “glacial periods” (or ice ages) and times without large ice sheets “interglacial periods”

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11
Q

What’s another name for ice age

A

Glacial periods

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12
Q

What % of earths surface is covered with glaciers today

A

10%

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13
Q

Where are the biggest glaciers currently found

A

Antarctica and Greenland

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14
Q

Where can smaller glaciers be found

A

At high altitudes in various mountain ranges in the lower, middle and higher altitudes.
E.g. Mont Blanc, Canadian rockies and the alps

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15
Q

What does the glacier system consist of

A

Inputs, transfers (flows) , stores and outputs .
In the same way as a river

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16
Q

Tell me about inputs

A

Inputs come from avalanches along the sides of the glacier, but mainly from precipitation as snow.

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17
Q

Tell me about storage/stores

A

Over time snow accumilates and is compressed into ice. The water hold in storage is the glacier.

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18
Q

Tell me about flows

A

Under the force of gravity the glacier
flows downhill.

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19
Q

Tell me about outputs

A

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

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20
Q

Accumulation + ablation

A

The balance between inputs and out puts leads to accumlation and ablation

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21
Q

Accumulation

A

In the winter, more is added to the glacier system than is lost. This happens near to the land of a glacier that leads to a zone of accumilation. This can cause a glaier to advance.
Accumilation = inputs > outputs

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22
Q

Ablation

A

In the summer and at lower altitutes, more is lost from the glacier system than is added. This leads to a zone of ablation and can cause the glacier to retreat.
Ablation = outputs > inputs

23
Q

What are the 3 main processes that operate in the glacier system

A

Frost shattering.
Plucking
Abrasion

24
Q

What is frost shattering

A

The action of glacial meltwater on joints , cracks and hollows in rock.

25
Q

Frost shattering during the day

A

When it’s above 0°C water enters cracks in a rock.

26
Q

Frost shattering during the night

A

When below 0°C (reaches freezing point) the water inside cracks, freezes , expands and causes the cracks to widen.
When the temperature rises the water will then thaw and contraction. This eventually causes rocks to break up.

27
Q

What is Abrasion

A

The moraine frozen into the glacier scours the valley sides and base. This is a sandpapering effect, similar to corrosion by a river but on a far larger scale .

28
Q

What is plucking

A

The water at the bottom of the glacier freezes onto rock at the valley base. As the glacier moves the rock is pulled away from the valley base. Plucking mainly occurs when the rock is well jointed.

29
Q

What are some landforms that are created by glacial erosion ?

A

Corries
Arête
Pyramidal peaks
U shaped valleys

30
Q

What is a corrie

A

Snow collects in a natural hollow on the side of a mountain. Overtime further snow collects in the hollow. This extra weight compresses the snow underneath, turning it into ice.

31
Q

What are the 5 steps of now a corrie forms

A
  1. Snow gathers in a hollow and turns to ice
  2. Material from the base of the hollow is plucked out by the ice and a braids the hollow to make it deeper.
  3. Eventually the ice out grows the hollow and goes down slope, due to gravity.
  4. When the ice melts it leaves a deepened hollow called a corrie.
  5. Sometimes the corrie fills up with water to form a lake. This is called a tarn
32
Q

What is an arête

A

A knife edged ridge formed between 2 corries.
When 2 corries form next to each other , and their adjacent walls are eroded backwards until they meet, a narrow and pointed rock ridge is formed. This is often likened to a knife edge with near vertical sides and a sharp top edge.

33
Q

What’s a pyramidal peak

A

A pyramidal peak is formed when three or more corries are formed back to back.
The Matterhorn in the alps and mount everest in the Himalayas are famous Pyramidal peaks.

34
Q

What’s a u shaped valley

A

•As glaciers move downhill they change V-Shaped valleys into U-shaped valleys or gacial troughs. The ice has great erosive power
• Whereas a river creates a V-Shaped valley because it acts mainly on the base of the valley, glaciers fill The valley and create steep sides and wide bases.

35
Q

formation of a U shaped valley

A

Before glaciation a v shaped valley is formed by a river. During the ice age a glacier moves down this valley.
Rocks trapped in the bottom of the ice act like sandpaper wearing the valley away by abrasion.
The glacier deepens, Straightens and widens the valley by abrasion.
After the ice melts, a U-Shaped valley remains.

36
Q

What are some characteristics of a glacial trough or U shaped valley

A

Misfit stream .
Hanging valleys.
Wide and flat valley floor.
Truncated spurs.
Steep valley sides.

37
Q

What’s another name for a u shaped valley

A

Glacial trough

38
Q

What’s a misfit stream

A

A river that flows through the valley after the ice age is described as a misfit stream. This river could never have eroded the valley

39
Q

What’s a truncated spur

A

Interlocking spurs are truncated as the glacier cuts straight through the landscape.

40
Q

What are hanging valleys

A

Between truncated spurs are hanging valleys which have not been eroded as the main valley.

41
Q

When does deposition occur

A

Glaciers erode and transport large amounts of material.
Deposition occurs when a rise in temperature causes ice to melt and the glacier is no
longer able to cary as much material, so it dumps it.

42
Q

What are the different types of moraines

A

Medial
Lateral
Terminal
Ground
Recessional

43
Q

What are 3 landforms created by glacial deposition

A

Moraines
Drumlins
Erratics

44
Q

What’s a moraine

A

Moraine is a type of landform that is created when a glacier deposits the material (till) that it has been transporting. It is made up of unsorted angular rocks There are several types ot Moraine

45
Q

Terminal moraine

A

found at the turthest (end) part ot a glacier

46
Q

Lateral moraine

A

found along the sides ot a glacier

47
Q

Medial moraine

A

found at the junction between 2 glaciers

48
Q

Ground moraine

A

disorganised piles of rocks of various shapes, sizes and rock types found on the ground

49
Q

Recessional moraine

A

material found at the snout ot the glacies as it retreats/advances

50
Q

What’s a drumlin

A

Drumins are smooth mounds of deposited material that reach a kilometre or more in length,
500m or so in width and over 50m in height.
It is thought that they were formed when the ice became overloaded with sediment.

51
Q

What’s a group of drumlin’s called

A

A swarm

52
Q

What are striations

A

These are scratches on material that the glacier is carrying. They give an indication of the direction that the glacier was travelling in.

53
Q

What are erratics

A

Eratics are large boulders that have been carried by the glacier and ther deposited in on area of different rock type, so that they look completely out of place