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AQA GLACIAL SYSTEMS AND LANDSCAPES > Geomorphological processes > Flashcards

Geomorphological processes Flashcards

1
Q

What are the two types of weathering processes?

A
  • Frost Action

- Nivation

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2
Q

What is frost action?

A
  • water enters cracks during day (as temperatures are warmer during the day) amd freezes at night (as temperatures are usually are colder at night).
  • As it freezes it expands by approximately 10%, exerting pressure
  • this process repeats itself
  • When repeated the crack widens and causes rock fragments to break off
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3
Q

Typical mistake

A

The frequency of freeze thaw cycles is more effwvtive in frost action than in sub-zero temperatures.

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4
Q

What is nivation

A

A process of weathering

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5
Q

How does nivation occur?

A
  • a series of processes that occur underneath patches of snow
  • freezethaw and chemical weathering processes loosen rock and melt water removed debris
  • the repetition of this process of meltomg amd freezing over seasons forms nivation hollows
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6
Q

What are the two zones of movement?

A
  • upper zone

- lower zone

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7
Q

Characteristics of the upper zone?

A
  • brittle

- breaking and forming crevasses

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8
Q

Characteristics of the lower zone?

A
  • steady pressure

- meltwater from pressure melting and frictional heats leads to more rapid movement.

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9
Q

What are the types of movement?

A
  • internal deformation
  • rotational flow
  • compressional flow
  • extensional flow
  • basal sliding
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10
Q

How many types of movement are there?

A

5

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11
Q

What is internal deformation

A
  • ice crystals orientate themselves in the direction of movement of the glacier
  • they slide past eachother
  • main tupe of flow in cold glaciers in the absence of meltwater
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12
Q

How does rotational flow occur?

A
  • occurs within corries (cirque)
  • a depression on which the glaciers occur
  • the ice pivots/rotates as it starts to move downhill
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13
Q

What is a gradient in geography?

A

an increase or decrease in the magnitude of a property (e.g. temperature, pressure, or concentration) observed in passing from one point or moment to another.

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14
Q

Pressure caused by the ice mass leads to ice …

A

Melt at temperatures well below freezing

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15
Q

What is compressional flow

A
  • reduction in gradient

- leads to a thickening in ice mass and slowing of movement

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16
Q

What extensional flow?

A

This is where a steeper gradient leads to the thinning and acceleration of the ice

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17
Q

What is basal sliding?

A
  • As ice moves over bedrock there is fiction
  • causes pressure and subsequently heat
  • heat leads to melting
  • the resulting meltwater acts as a lubricant and the ice flows more rapidly
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18
Q

What are the two procwsses of erosion?

A
  • Abrasion

- plucking

19
Q

Describe the process of abrasion

A
  • as material at the bottom of a glacier rubs away at the valley sides and floor.
  • scratches may be left - stritations
  • if debris is very fine it is called rock flour
20
Q

What is plucking?

A

The glacier freezes onto and into rocks

  • as the glacier moves the rocks are plucked out
  • mainly occurs at the base of the glacier where jointed rocks have been weakened by freeze thaw action
21
Q

What type of landscape does plucking leave?

A

A jagged landscape

22
Q

What is transportation?

A

This is where glaciers carry large amounts of debris from weathering and erosion processes and rock falls from valley sides.

23
Q

What are the three types of transportation?

A
  • supraglacial
  • englacial
  • subglacial
24
Q

What is supraglacial?

A

On the surface

25
Q

What in englacial?

A

Within the ice

26
Q

What is subglacial?

A

At the base of the glacier

27
Q

What is deposition

A

When ice melts at the snout, material is deposited.

28
Q

What is a snout?

A

The end point of the glacier

29
Q

When does deposition occur?

A

When the glacuer changes between conpressing and extensional flow

30
Q

What is meant by the term till?

A

Unsorted rocks, clay, and sand debris.

31
Q

What does the composition of till show?

A

It reflects the geological conditions over which the ice has travelled.

32
Q

Fluvioglacial processes

A
  • Meltwater is formed when glaciers melt.
  • large quantities are produced
  • large quantities which are produced transport large amounts of debris.
33
Q

Characteristics of meltwater channel (fluvioglacial)

A
  • steep sided
  • deep
  • straight
34
Q

Why do meltwater channels have significant levels of erosive power?

A
  • high discharge

- turbulent flow

35
Q

What are periglacial environments?

A
  • not glaciated
  • exposed to cold conditions
  • intense frost and permanently frozen ground
36
Q

Permafrost

A
  • permanently frozen ground

- in areas where temperatures below ground surface remain below 0° continuously for more than 2 years

37
Q

Whatvare the three categories of permafrost?

A
  • continuous
  • discontinuous
  • sporadic
38
Q

Continuous permafrost

A
  • coldest regions of Siberia

- can be 1500 m thick

39
Q

Discontinous permafrost

A
  • slightly warmer regions

- 20-30 m thick

40
Q

Sporadic permafrost

A

Isolated spots of permafrost occur in areas where there is summer thawing.

41
Q

What are the three mass movement processes that occur in periglacial areas?

A
  • solifluction
  • frost creep
  • rock fall
42
Q

Solifluction

A
  • in the summer, water in surface layer melts
  • this is due to an impermeable frozen layer below it cannot drain away
  • lack of evaporation = surface layer become very wet, soil particles become lubricated and will move down the most gentle slopes
43
Q

Frost creep

A

The gradual downslope movement of individual soil particles due to freeze-thaw weathering.

AQA GLACIAL SYSTEMS AND LANDSCAPES (6 decks)

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