Chapter 11: Glaciation

Question 1

Ice age

Answer 1

Ice age is the period during which large parts of several continents are covered by ice sheets.
During the ice age, the temperatures in the northern hemisphere were so low that snow and ice did not get a chance to melt. Year after year, layers of snow and ice built up until it was compressed or compacted together to form huge masses of ice called glaciers

Question 2

What causes an ice age

Answer 2

Earths orbit and axis
Earths atmosphere, when there is less carnon dioxide in the atmosphere to trap the suns heat global temperature can drop

Ocean currents, distribute heat. When they change course, ice sheets can build up.

Question 3

Processes of glacial erosion

Answer 3

Plucking

Abrasion

Question 4

Processes of glacial erosion: Plucking

Answer 4

As a glacier moves, there is friction between the glacier and the ground beneath it. This friction causes the bottom of the glacier to melt. The meltwatwr makes its way into cracks in the rocks underneath the glacier. The meltwater then refreezes around the rocks.
When the glacier moves, it plucks the frozen meltwater and the rocks from the ground. The rocks are then carried away with the glacier.

Question 5

Processes of glacial erosion: Abrasion

Answer 5

As the glacier moves, the rocks attached to it scratch and scrape the surface rock underneath and on the sides of the valley. The scratch marks left behind on rocks are called striations. These marks tells us the direction in which the glacier moved.

Question 6

Cirques

Answer 6

A cirque is a basin-shaped hollow in a mountain it looks like an armchair. It has three steep sides and often contains a lake. A cirque was the birthplace of a glacier.

Question 7

Formation of Cirque

Answer 7

A cirque is formed when snow accumulates (builds up) in a hollow high up on a mountain. The snow is compressed to form ice.
The ice plucks rocks from the sides of the mountain as it begins to move. These rocks make the hollow deeper through the process of abrasion.
The ice eventually overflows from the hollow and gravity causes the ice to move downhill.
The ice that is left behind melts and forms a lake in the hollow. This lake is called a tarn
Examples: Devil’s Punchbowl, Co. Kerry.

Question 8

Arêtes

Answer 8

An arê is a narrow, steep-sided ridge between two cirques.

Question 9

Pyramidal peaks

Answer 9

A pyramidal peak is a steep-sided peak between three or more cirques

Question 10

U shaped Valleys

Answer 10

A glaciated or U-shaped valley has a wide, flat floor and steep sides.

Question 11

Formation of a U-shaped valleys

Answer 11

When a glacier moves out of a cirque and down the mountain, it follows the easiest route possible.
This route is often a V-shaped valley that has previously been carved out by a river.
The glacier uses plucking and abrasion to widen and deepen the valley. This changes it from a V-shaped valley to a U-shaped valley.
As a glacier moves through the valley, it also cuts off the tips off the interlocking spurs created by the river, leaving behind truncated spurs.
Example: Gap of Dunloe, Co. Kerry

Question 12

Ribbon lakes

Answer 12

A ribbon lake is a long, narrow lake on the floor of a U-shaped valley.

Question 13

Hanging Valleys

Answer 13

A hanging valley is a smaller glaciated valley that hangs above the main glaciated valley.

Question 14

Fjords

Answer 14

A fjord is a drowned U-shaped valley that is very deep and has steep sides.

Question 15

How glaciers transport their load

Answer 15

As a glacier moves, it transports eroded material. These materials are carried

On the surface of ice (supraglacial transport)

Within the ice (englacial transport)
Materials fall through cracks or crevasses in the glacier

Underneath the glacier
(Subglacial transport)

The material that is transported by the glacier, and later deposited by it, is called a moraine.

Question 16

Landforms of glacial erosion

Answer 16

Boulder clay plains
Drumlins
Erratics
Moraines

Question 17

Boulder clay plains

Answer 17

Is a lowland area that is covered in a layer of boulders, clay, sand and stones called boulder clay.

Question 18

Drumlins

Answer 18

Drumlins are oval-shaped hills made of boulder clay

Question 19

Formation of Drumlins

Answer 19

A drumlin forms when a glacier deposits mounds of boulder clay.
The glacier then continues its journey and smooths the boulder clay as it moves over it.
The steep slope or stoss end of the drumlin shows us what direction the glacier was coming from. The gentle slope or lee slope shows us what direction the glacier was travelling in
Drumlins usually occur in clusters, forming what is called a ‘basket of eggs’ landscape.
Example: Clew Bay, Co. Mayo

Question 20

Erratics

Answer 20

Large boulders that were transported from their original location by a glacier and then deposited in an area where the rock type is different.

Question 21

Moraines

Answer 21

A moraine is the name given to the material transported and later deposited on the valley floor by a glacier.

Question 22

Landforms of meltwater (fluvio-glacial) deposition

Answer 22

The heavier material, such as stones and gravel, is deposited first, and then the lighter material, such as sand, is deposited. Features associated with this type of deposition are called fluvio-glacial.

Question 23

Eskers

Answer 23

An esker is a long, narrow ridge of sand and gravel that winds its way along a lowland landscape.

Question 24

Formation of Eskers

Answer 24

When a glacial begins to melt, streams of meltwater carrying a load of eroded material flow through a tunnel that is carved out under the glacier.
When the load becomes too great, some material is deposited on the bed of the meltwater stream.
The stream loses its energy when it exits the tunnel and it deposits the remaineer of its load. This forms a ridge of sand and gravel on the surrounding plain.
This ridge is known as an esker. Roads have been built on eskers in many areas as they provide good foundations.
Example: Esker Riada, Co. Galway

Question 25

Outwash plains

Answer 25

An outwash plain is a low, flat area of land made of sand and gravel. It is found in front of a terminal moraine.

Question 26

Benefits of glaciation

Answer 26

Agriculture
Tourism
Hydroelectricty
Roads
Industry

Question 27

Negatives of glaciation

Answer 27

Poor agricultural land in upland areas
Poor drainage
Flooding