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Physical Landscapes of Britain > Frost and Wind > Flashcards

Frost and Wind Flashcards

1
Q

What is the peri-glacial concept?

A

Processes in cold-but not glacial environments, more subtle than glacial processes

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2
Q

What’s more common in Britain? Glacial processes or peri-glacial processes?

A

Peri-glacial processes

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3
Q

What are para-glacial processes? Give an example

A

Non-glacial processes greatly affected and conditioned by glaciation or deglaciation.
e.g. sediment transfer process may greatly increase after deglaciation if a slope is unstable after ice-retreat.

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4
Q

What’s the difference between peri-glacial processes and para-glacial processes?

A

Peri: cold but non glacial
Para: non-glacial but affected by glaciers

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5
Q

What is cryotic ground?

A

Ground with a temperature below 0

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6
Q

What is permafrost?

A

Ground that remains below 0 for at least 2 consecutive years

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7
Q

What is seasonally cryotic ground?

A

Ground that undergoes seasonal thawing and freezing

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8
Q

Describe the general typical effect of frost weathering.

A

Rocks often fracture along pre-existing weaknesses, this can cause rock disintegration and create fine material that then settles to leave a coarse top layer

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9
Q

What is the difference between macrogelivation and microgelivation?

A

macro: produces larger clasts
micro: produces finer debris

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10
Q

What types of rocks are more susceptible to microgelivation?

A

smaller debris –> Micaceous rocks (commonly igneous and metamorphic)

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11
Q

What types of rocks are more susceptible to macrogelivation?

A

larger debris –> massive schists, gneisses, granulites

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12
Q

What are the main 4 processes by which micro and macrogelivation take place?

A

Splitting
Flaking
Granular disintegration
Comminution

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13
Q

What is solifluction?

A

Slow downslope movement of soil under seasonal thawing and freezing.

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14
Q

What is frost creep?

A

Repeated swelling and resettling of soil/sediment

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15
Q

What is gelifluction?

A

Slow saturated flow during the thawing of ice rich soil

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16
Q

What is plug-like flow?

A

Localised sliding within clay rich soils due to thawing and melting

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17
Q

Name three types of solifluction.

A

Frost Creep, Gelifluction, Plug-like flow

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18
Q

What are block-deposits?

A

A surface cover of boulders with little or no fine material in the gaps

19
Q

What is the difference between autochthonous blockfields and allochthonous blockfields?

A

auto –> result of weathering of rocks that were already there
allo –> glacial deposits weathered

20
Q

What is the general 3 stage process of blockfields forming?

A

macrogelivation
then solifluction (moving downslope)
then immobilisation (no fine material to move boulders)

21
Q

What age are blockfields usually?

A

Can be relic features from the Neogene protected by glaciers or caused by weathering during glacial periods in the Quaternary

22
Q

What are debris-mantled surfaces and slopes?

A

Poorly sorted stony surfaces with a mix of larger clasts and a fine matrix (fine sediment)

23
Q

What is a diamict?

A

A poorly sorted deposit

24
Q

What is a tor?

A

A residual section of bare bedrock on high ground

25
Q

What are the two possibilities for explaining the formation of tors?

A
  • Preferential deep weathering of densely jointed bedrock
  • Removal of regolith around hard rock by solifluction and frost weathering
26
Q

What is relic-patterned ground?

A

terrain with surface patterns defined by micro-relief rocks, vegetation cover and fine and coarse debris.

27
Q

What are the two types of relic patterned ground? What causes them?

A

Sorted: differential frost heave
Unsorted: same as sorted but without a concentration of clasts.

28
Q

What are solifluction landforms?

A

Landforms on gentle to moderate slopes, often occur on larger hills/mountains but terminating at a steep rise or step

29
Q

What are solifluction sheets?

A

A continuous top layer of frost-weathered deposit over bedrock - successive sheets can look like stairs

30
Q

What are solifluction lobes?

A

Lobate extensions of sheets on steeper gradients, can override sheets on downslope ends

31
Q

What are talus deposits?

A

deposits at the bottom of steep rock walls - predominantly through rockfalls

32
Q

What is a frost related cause of rock falls?

A

Macrogelivation

33
Q

What are 3 types of talus deposits?

A

Sheets - uniform delivery of the debris.
Cones - concentrated or funnelled in certain spots.
Coalescing cones - cones that intersect laterally.

34
Q

What are deflation surfaces? What causes them?

A

Surfaces with almost all vegetation and loose sand stripped away - carpeted with fine gravel and flat lying boulders.
- Caused by strong wind

35
Q

What are deflation scars? What causes them?

A

Patches of bare ground in vegetated terrain
- Caused by needle ice action and wind erosion

36
Q

What are wind stripes?

A

Selective wind erosion on plateaux surfaces, stripes of vegetation and bare ground perpendicular to dominant wind direction

37
Q

What are wind polished boulders? What do they tell us?

A

Wind erosion on bedrock and boulders caused by transfer of KE to rock particles over a long time
- can evidence wind direction

38
Q

What is debris flow activity? What are the two types?

A

Rapid downslope flow of poorly sorted debris when it’s mixed with water.

Either Hillslope debris flow (usually initiated by a landslide) or valley confined which is usually initiated by water pressure in sediment.

39
Q

What does alluvial mean?

A

Alluvial refers to the stuff left behind by running water.

40
Q

Why are most alluvial landforms paraglacial?

A

Because most of the sediment carried in upland rivers is reworked glacial sediment.

41
Q

What are alluvial river fills?

A

Deposits of sediments in a river

42
Q

What are river terraces?

A

major steps in a valley side corresponding to previous river flow

43
Q

What are alluvial fans?

A

low gradient fans caused by tributary streams that end in one trunk valley

Physical Landscapes of Britain (13 decks)

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