SG2A: How are glacial landforms developed? (Erosional Landscapes)

Question 1

What are geomorphic processes?

Answer 1

Processes are natural mechanisms of weathering, mass movement, erosion, transportation and deposition which all influence glaciated landscape system

Question 2

What is weathering?

Answer 2

The breakdown of rock due to the atmosphere, miscroscopic organisms and water.

Question 3

What is oxidation?

Answer 3

Some minerals in rocks react with oxygen in the air or in the water.

Question 4

What is freeze-thaw?

Answer 4

Water enters cracks and expands by 10% when it freezes. this exerts pressure on the rock causing it to split into pieces.

Question 5

What is frost-shattering?

Answer 5

At extremely low temperatures water trapped in rock pores freezes and expands. This creates stress which disintegrates the rock into small pieces.

Question 6

What is solution?

Answer 6

Any process by which a mineral dissolves in water. E.g. salts are soluble in water.

Question 7

What is hydration?

Answer 7

Water molecules added to rock minerals of a larger volume. This often causes surface flaking in many rocks because some minerals also expand by 0.5%. during the chemical change as well as absorbing water.

Question 8

What is tree roots?

Answer 8

Tree roots grow into cracks or joints in rocks and exert outward pressure.

Question 9

What is carbonation?

Answer 9

Rainwater combines with dissolved carbon dioxide from the atmosphere to produce weak carbonic acid. This reacts with calcium carbonate in rocks such as limestone to produce calcium carbonate.

Question 10

What is organic acids?

Answer 10

Organic acids are produced during decomposition of plant and animal litter cause soil water to become more acidic and rect with some minerals in a process called chelation.

Question 11

What is hydrolysis?

Answer 11

This is a chemical reaction between rock minerals and water.

Question 12

What is pressure realase?

Answer 12

When the weight of the overlying ice in a glacier is lost due to melting, the underlying rock expands and fractures parallel to the surface.

Question 13

What are the flows of energy for abrasion?

Answer 13

Kinetic- as the glacier moves, it erodes
Thermal- heat energy allows meltwater which aids basal sliding. The more meltwater, the faster the movement and more erosion.

Question 14

What are the flows of energy for plucking?

Answer 14

Kinetic- glacier is moving and as it moves any rock frozen to the ice, will be removed.
Thermal- pressure melting allows meltwater to enter into the cracks in the bedrock and when it freezes and as as the glacier moves, it gets removed.

Question 15

What is mass movement?

Answer 15

The downslope transportation of material under gravity.

Question 16

What are the 3 main processes of mass movement?

Answer 16

• Slides
• Slumps
• Rockfalls

Question 17

When do slides occur?

Answer 17

When an entire material moves downwards along a straight line slip lane until it impacts at the bottom of the slope.

Question 18

What are slumps?

Answer 18

Rotational slides

Question 19

When do slumps occur

Answer 19

Where material slips down a curved slip plane with a rotation movement.

Question 20

When do rockfalls occur?

Answer 20

On a steep slop (over 70 degrees).

Question 21

What flows of energy are involved in mass movement?

Answer 21

Potential energy to kinetic energy.

Question 22

What is abrasion?

Answer 22

A sand papering action. The glacier moves across the surface and debris in the ice scours the surface of the rocks wearing them away.

Question 23

What is plucking?

Answer 23

Meltwater seeps into cracks in rocks of the valley floor/sides. Meltwater freezes, become attached to the glacier. As the glacier moves it pulls pieces of rocks away.

Question 24

What is glacial transportation?

Answer 24

When the material is transported.

Question 25

What are the 3 types of debris?

Answer 25

• Supraglacial
• Englacial
• Subglacial

Question 26

Where is supraglacial found?

Answer 26

Surface of glacier

Question 27

Where is englacial found?

Answer 27

Carried within the glacier.

Question 28

Where is subglacial found?

Answer 28

Bottom of the glacier.

Question 29

What are the two types of glacial deposition?

Answer 29

Glacial till and Glacio-fluvial material

Question 30

What are the two types of glacial till?

Answer 30

Lodgement till and ablation till

Question 31

What is lodgement till?

Answer 31

Material deposited at the base of advancing glaciers due to basal melting.

Question 32

What is ablation till?

Answer 32

Material deposited as the ice melts away from retreating/ stagnant glacier.

Question 33

What is a corrie?

Answer 33

An arm shape hollow found on upland hills or mountain sides.

Question 34

What is the size of a corrie?

Answer 34

15km wide

Question 35

What is the formation of corries?

Answer 35

1. Nivation forms a small hollow
2. At this high altitude location the glacier has a large store of potential energy.
3. A Bergschrund crevasse forms at the top of the glacier, as it moves forward. Meltwater runs down the crevasse and freezes in cracks within the back wall causing freezings-thaw weathering which weakens the back wall.
4. As the glacier moves it plucks away frost-shattering lumps of rocks, causing the steepening of the back wall.
5. Rock fragments eroded from the back wall become incorporated into the glacier as subglacial debris and cause abrasion which deepens the hollow.
6. At the end of the glaciation the glacier melts leaving behind a tarn. The rock lip acts as a dam.

Question 36

What is an arete?

Answer 36

A narrow, steep sided ridge often called a knife edge ridge.

Question 37

Size of an arete?

Answer 37

Vary in size but striding edge is 200-300m high

Question 38

How does an arete form?

Answer 38

When 2 neighbouring corries that are back to back erode towards each other so that the land between them gets narrower.

Question 39

An example fo an arete?

Answer 39

Stridging Edge, Lake District.

Question 40

What is a pyramidal peak?

Answer 40

An angular, sharply pointed mountain.

Question 41

Size of an pyramidal peak?

Answer 41

Peak is over 1200m high

Question 42

An example of a pyramidal peak?

Answer 42

Matterhorn, Switzerland.

Question 43

How does a pyramidal peak form?

Answer 43

When 3 or more corries develop on all sides of the same mountain, their back walls retreat and the remaining mass will be steepened to form a pyramid shape.

Question 44

What is a glacial trough?

Answer 44

A U shaped valley with steep, straight sides and a flat or rounded bottom.

Question 45

Size of an glacial trough?

Answer 45

1km- 50km length and width is 0.5km-3km.

Question 46

How does a glacial trough form?

Answer 46

1. Freeze thaw weathering will have weakened the valley sides. As the glacier erodes this material it becomes englacial debris and subglacial.
2. Weathered material that has been eroded from the mountain peaks also falls onto the glacier It can then fall into crevasses and form subglacial debris and englacial.
3. As the glacier deforms and flows downslope, it’s stored gravitational potential energy is transferred to kinetic energy. This energy allows erosion to take place.
4. The sub and englacial debris abrades the side and base of original V shaped river valley. Whereas the river was unable to erode the bands of resistant rock and had to flow around them. Forming truncated spurs.
5. Small river is left behind (misfit)
6. Parabolic shape.

Question 47

What is a roche moutonnee?

Answer 47

A mass of more resistant rock on the floor of a glacial trough which is smooth and rounded on the stops (or up the valley side. The lee side is steep and jagged.

Question 48

What is a hanging valley?

Answer 48

A smaller tributary valley to the side of the main glacial trough, left ‘hanging’ above the main u-shaped valley. A waterfall can often be seen.

Question 49

How is a hanging valley formed?

Answer 49

The main valley is eroded more quickly and deeper than the tributary valleys. This leaves the tributary valleys at much higher level than that of a main valley.