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

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1
Q

What are geomorphic processes?

A

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

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2
Q

What is weathering?

A

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

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3
Q

What is oxidation?

A

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

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4
Q

What is freeze-thaw?

A

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

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5
Q

What is frost-shattering?

A

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

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6
Q

What is solution?

A

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

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7
Q

What is hydration?

A

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.

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8
Q

What is tree roots?

A

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

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9
Q

What is carbonation?

A

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.

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10
Q

What is organic acids?

A

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.

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11
Q

What is hydrolysis?

A

This is a chemical reaction between rock minerals and water.

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12
Q

What is pressure realase?

A

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.

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13
Q

What are the flows of energy for abrasion?

A

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.

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14
Q

What are the flows of energy for plucking?

A

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.

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15
Q

What is mass movement?

A

The downslope transportation of material under gravity.

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16
Q

What are the 3 main processes of mass movement?

A
  • Slides
  • Slumps
  • Rockfalls
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17
Q

When do slides occur?

A

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

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18
Q

What are slumps?

A

Rotational slides

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19
Q

When do slumps occur

A

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

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20
Q

When do rockfalls occur?

A

On a steep slop (over 70 degrees).

21
Q

What flows of energy are involved in mass movement?

A

Potential energy to kinetic energy.

22
Q

What is abrasion?

A

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

23
Q

What is plucking?

A

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.

24
Q

What is glacial transportation?

A

When the material is transported.

25
Q

What are the 3 types of debris?

A
  • Supraglacial
  • Englacial
  • Subglacial
26
Q

Where is supraglacial found?

A

Surface of glacier

27
Q

Where is englacial found?

A

Carried within the glacier.

28
Q

Where is subglacial found?

A

Bottom of the glacier.

29
Q

What are the two types of glacial deposition?

A

Glacial till and Glacio-fluvial material

30
Q

What are the two types of glacial till?

A

Lodgement till and ablation till

31
Q

What is lodgement till?

A

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

32
Q

What is ablation till?

A

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

33
Q

What is a corrie?

A

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

34
Q

What is the size of a corrie?

A

15km wide

35
Q

What is the formation of corries?

A
  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.
36
Q

What is an arete?

A

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

37
Q

Size of an arete?

A

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

38
Q

How does an arete form?

A

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

39
Q

An example fo an arete?

A

Stridging Edge, Lake District.

40
Q

What is a pyramidal peak?

A

An angular, sharply pointed mountain.

41
Q

Size of an pyramidal peak?

A

Peak is over 1200m high

42
Q

An example of a pyramidal peak?

A

Matterhorn, Switzerland.

43
Q

How does a pyramidal peak form?

A

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.

44
Q

What is a glacial trough?

A

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

45
Q

Size of an glacial trough?

A

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

46
Q

How does a glacial trough form?

A
  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.
47
Q

What is a roche moutonnee?

A

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.

48
Q

What is a hanging valley?

A

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.

49
Q

How is a hanging valley formed?

A

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.