Glaciation

Question 1

What is an ice age?

Answer 1

An ice age is a period of time when a part(s) of Earth is covered in ice.

Question 2

How long ago did the last ice age end?

Answer 2

The last ice age hasn’t ended yet. However, the last glaciation ended 15 000 - 18 000 years ago. We are currently in an inter-glacial.

Question 3

How much of the world did the ice cover and where?

Answer 3

Ice covered about 30% of the world in Northern countries, high altitudes and Antartica.

Question 4

What happened to places not covered by ice?

Answer 4

cooler / different ecosystems / different. (Everywhere changed).

Question 5

Why do ice ages start and finish?

Answer 5

Ice ages start and finish because of natural climate changes on Earth.

Question 6

On average, how much cooler was the world in the last ice age?

Answer 6

The was about 7°C colder in the last ice age.

Question 7

What animals lived in the last ice age but are now extinct?

Answer 7

Some animals which lived in the last ice age but are now extinct are:

• the wooly rhino
• the mammoth
• the saber-toothed tiger
• ground sloths
• the stag moose
• etc.

Question 8

Did dinosaurs exist during the last ice age?

Answer 8

No, dinosaurs did not exist during the last ice age.

Question 9

How much lower were sea levels during the last ice age?

Answer 9

Sea levels were about 100-200m lower during the last ice age.

Question 10

What is a glacier?

Answer 10

A glacier is a large sheet of ice made up of snow that has been compressed over many years to form solid ice.

Question 11

How does a glacier start?

Answer 11

Glaciers start when snow falls and a part of it doesn’t melt during the summer (a small bit remains). Over the years, this procedure will build up to form a glacier (made of snow which has also compressed during a long period of time (hundreds of years) to create ice).

Question 12

Why do glaciers start near the top of mountains on north facing slopes?

Answer 12

Glaciers start near the top of mountains on north facing slopes because this is where it is coldest and therefore the snow will not melt during the summer.

Question 13

How do glaciers move?

Answer 13

Glaciers move slowly down the mountain with help from gravity. The overlying ice causes the ice to deform around the rock and ‘flow’. The under-glacier rivers also help it move.

Question 14

What is glaciation?

Answer 14

The effects of large bodies of ice on the landscape and the distinctive landforms created by erosion, transportation and deposition.

Question 15

What is plucking?

Answer 15

A procedure that happens when the glacier ‘flows’ slowly down the mountain. As it moves it will pick stones up on the way which will stick to the ice.

Question 16

What is abrasion?

Answer 16

The process will take place when the ‘plucked’ stones scrape at the landscape on the sides of the glacier when it is slowly ‘flowing’ down the mountain. Friction between the rocks will smoothen out the landscape rock.

Question 17

What is nivation?

Answer 17

Snow compresses into ice and molecules…

Question 18

How is a corrie / cirque / cwm formed?

Answer 18

Snow builds up in a shallow hollow behind a small lip and nivation takes place as it is compressed during the years. As its own weight and gravity will encourage it to move downhill in rotational slip, the glacier will pull away from the steep backwall to form a bergschrund. It will also pluck stones from the rock and pull them along to cause abrasion which will smoothen the landscape. All of this will steepen the corrie sides and deepen the corrie floor. Later on, the ice will melt in the corrie and becomes a small lake.

Question 19

In icy places, how can flowing water also help to shape the landscape?

Answer 19

Flowing water will help to form the landscape because it helps the glacier to flow down the mountain which is what carves out the landscape.

Question 20

How are pyramidal peaks formed?

Answer 20

Formed when three or more corries are weathered and eroded backwards into a mountain top, until a sharp peak is created.

Question 21

How are aretes formed?

Answer 21

Formed as the backwall and sides of a corrie are weathered and eroded.

Question 22

What are striations and how are they formed?

Answer 22

Striations are approx. 1mm grooves made by rocks which have been ‘plucked’ at the bottom of the glacier, scraping against the rock. The grooves are all parallel and this indicates the glaciers’s route.

Question 23

What are truncated spurs and how are they formed?

Answer 23

When the glacier bulldozes through the old inter-locking spurs of the old river valley it cuts them short, or ‘truncates’ them.

Question 24

How are U-shaped valleys formed?

Answer 24

When the glacier digs deeper into the land, making a straight, deep valley shaped like a ‘U’.

Question 25

What are ribbon lakes and how are they formed?

Answer 25

Long, narrow lakes found in glaciated valleys formed in locations where the glacier had more erosive power, e.g. in areas of softer rock, where the valley gradient temporarily steepened or a tributary glacier joined the main valley.

Question 26

What are roche moutonnées and how are they formed?

Answer 26

Glacier flows over rock, ice at base melts under pressure. Rock scraped smooth on ‘uphill side’ where the glacier moves over it. On ‘far’ side water refreezes, gluing rock to the ice….
… which moves on downhill and ‘plucks’ chunks out of the rock

Question 27

What are hanging valleys and how are they formed?

Answer 27

When the glacier melts in the carved out ‘U’ shaped valley, the floor of the main valley is far below the floor of the tributary valleys, leaving the floor of the tributary valleys suspended or ‘hanging’ high above the main valley floor.

Question 28

What and how are kettles holes formed?

Answer 28

These form from detached blocks of ice, left behind when the glacier retreats. When the ice melts it leaves behind a depression (hole), which sometimes fills with water (kettle hole lake)

Question 29

What is glacial till?

Answer 29

Material deposited by the glacier.

Question 30

What is a moraine, and what are the different types?

Answer 30

Rock particles carried by the glacier.

• Ground Moraine
• Lateral Moraine
• Medial Moraine
• Terminal Moraine

Question 31

What are outwash plains and how are they formed?

Answer 31

These are flat areas where meltwater has flushed moraine out from under and in the glacier to wide areas below the snout of the glacier.

Question 32

What are eskers and how are they formed?

Answer 32

Eskers are long, winding ridges of sand and gravel typically oriented parallel to ice flow. They were deposited by glacial meltwater streams flowing in channels or tunnels in, on, or beneath the ice.

Question 33

What are erratics and how are they formed?

Answer 33

These are ‘Alien’ boulders, scattered over the valley floor, left behind after the glacier retreated. They are most likely pieces of ground moraine.