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Physical Geog = Cold and Arid > Cold - KQ1 (processes and factors giving cold environment their distinctive characteristics) > Flashcards

Cold - KQ1 (processes and factors giving cold environment their distinctive characteristics) Flashcards

1
Q

What are the three types of cold environments?

A
  • Glacial/polar
  • Periglacial
  • Mountainous
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2
Q

What are glacial/polar characteristics?

A

EXAMPLE = Ambleside, Lake District

  • Snow and ice all year
  • Very cold and dry
  • -60C to 10C on coast
  • Winter temperatures = -70c to -25C
  • Summer temperatures = -40C to -2C
  • Katabatic winds form as dense cold airs over central plateau drains into valleys
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3
Q

What are kebatic winds?

A

Cold mountains winds - dense air flows down from the mountains to the lowlands, chilling the ground as it passes over

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4
Q

What are periglacial characteristics?

A

EXAMPLE = Tromso, Norway

  • Significant cover of snow and ice but not all year round
  • Found in areas of high altitude or high latitude
  • Large seasonal temperature ranges
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5
Q

What are mountain characteristics?

A

EXAMPLE = Verkhoyanks, Syria

  • Once covered in ice
  • Landforms which were formed during cold periods continue to exert and influence over how local people live
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6
Q

What are the reasons for cold climates?

A
  • High altitude
  • Winds
  • Albedo
  • Mountain environments
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7
Q

Why do high altitudes make cold climates?

A
  • Incoming solar radiation is spread out over a greater area at poles = heating is less intense
  • High altitudes = less solar radiation = more is lost as it passes through greater distance in atmosphere = scattering and reflection
  • Equator is shorter distance from sun = less incoming solar radiation lost
  • Polar night = sun does not rise at all so no heat for long time periods
  • Lower pressure (less oxygen, nitrogen and carbon dioxide as altitude increases) = molecules are further apart = less kinetic energy = less heat
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8
Q

Why do winds make cold climates?

A
  • Difference in air pressure between air masses causes winds
  • Blow from high pressure to low pressure (controlled by pressure gradient)
  • In cold = sinking cold dense air can flow rapidly downslope which cools land surface
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9
Q

Why does albedo make cold climates?

A

Albedo = measure of how reflective a surface is (out of 1 like probability)

  • High albedo = reflect incoming solar radiation = stays cold
  • Fresh snow = 0.9 so only 0.1 units of solar energy is absorbed
  • Arctic sea and Antarctic ice mass and ice shelves all reflect incoming solar radiation
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10
Q

Why do mountain environments make cold climates?

A
  • Often lie between 45 and 60 degrees north of equator (eg Lake District) = at junction between two types of air (cold polar air north and warmer tropical aril south)
  • Mixing air masses = uplift of warmer air along junctions = produces unstable, bad weather with rain (especially in winter)
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11
Q

How do glaciers move?

A

1 - Internal flow/deformation = movement within glacier due to gravity stresses
- Where ice crystals orientate themselves in direction of glacier’s overall movement = may slide past each other
- Results in crevasses within and at surface of ice
2 - Basal slippage = sliding effect of a glacier over bedrock by regelation slip/creep
- On upper side of obstacle = increasing pressure in lower ice = pressure melting locally
- Meltwater allows ice to slip over obstacle but then refreezes in lower pressure conditions on downglacier side of obstacle

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12
Q

How do glaciers erode?

A
  • Abrasion
  • Plucking
  • Bulldozing
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13
Q

How does abrasion erode glaciers?

A
  • debris trapped in sides and base of ice abrades/scratches bedrock = broken down into finer debris (rock flour at glacier snout)
  • Abrasion evidence = shown by striations (scratch lines) left on rocks of deglaciated areas
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14
Q

How does plucking erode glaciers?

A
  • Melting and refreezing of water around obstacles and rocks in bed of glacier
  • Upstream of obstacles = high pressure = lowers melting point = melting
  • Downstream = lower pressure = ice refreezes and plucks loose rocks from bed of glacier as ice moves downstream
  • Can form landforms known as Roche Mountains
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15
Q

How does bulldozing erode glaciers?

A

Pushing already weathered rock debris

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16
Q

What are factors affecting erosion?

A
  • Speed of ice (faster = more erosion)
  • Temperature of lower ice (below freezing = sticks = little erosion)
  • Basal water (water at base of ice = slides = little erosion)
  • Ice thickness (thicker = more = more weight)
  • Debris particle size and shape (large angular = more erosion)
  • Amount of meltwater (more = less erosion = lifts up glacier off bed so rocks in ice and bedrock are not in contact)
  • Bedrock (soft = more erosion)
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17
Q

What are the processes of weathering in cold areas?

A
  • Freeze thaw
  • Dilation
  • Carbonation
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18
Q

How does freeze thaw cause weathering in cold areas?

A
  • Ice melts during day and gets into cracks and joints
  • Freezes at night and expands by 9% = exerts pressure on rock = crack gets bigger
  • Repeated process = rock will break away
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19
Q

How does dilation cause weathering in cold areas?

A
  • Weight of glacier ice = pressure on underlying bedrock
  • At end of glacier or snout (seasonal changes) = ice melts and pressure is released
  • Bedrock expands and cracks
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20
Q

How does carbonation cause weathering in cold areas?

A
  • CO2 dissolves quicker in cold water = meltwater streams carry weak carbonic acid
  • On carbonate rocks (eg limestone) carbonate ions are attacked by acid and dissolve = forms bicarbonate ions which are carried away by meltwater
21
Q

What are factors affecting weathering?

A
  • Rock type (harder = less)
  • Altitude (higher = higher pressure = more)
  • Time of day (colder = more carbonation // night = more freeze thaw)
  • Temperature
22
Q

What are the landforms of glacial erosion?

A
  • Cirques/corries
  • Arêtes
  • Glacial troughs
  • U-shaped valleys
  • Truncated spurs
  • Ribbon lakes
  • Hanging valleys
  • Fjords
23
Q

What are corries/cirques?

A

EXAMPLE = 2 glacial cirques behing Mounth Tjamuhas in Abisko National Park, Sweden

  • An arm-chair shaped landform
  • Formed by various forms of erosion
  • Surrounded by steep ridges and almost vertical headwall
  • A rock lip is present which hold back the lake (or tarn) at base of landform
24
Q

How do corries/cirques form?

A
  • Snowflakes collect in a hollow = compressed and air is squeezed out to become firn or neve (by nivation)
  • Pressure from more layers of snow = firn becomes glacier ice over 1000s of years
  • Erosion and weathering by abrasion, plucking and freeze thaw = hollow is bigger
  • Ice is trapped in hollow and cannot move downhill = gravity still tries = rotational slip = causes ice to pull away form from back wall creating crevice or bergshrund
  • Plucked debris from back wall = further erosion through abrasion = deepens corrie
  • Some debris deposited at edge of corrie = builds lip
  • Create rounded, armchair shaped hollow with steep back wall
  • When ice in corrie melts, circular lake is often formed at bottom of hollow (called tarn)
25
Q

What is an Arête?

A

EXAMPLE = Striding edge, on mountain of Helvellyn in Lake District

  • Formed when two neighbouring corries run back to back
  • As each glacier erodes either side of the ridge edge becomes steeper and ridge becomes narrower
26
Q

How are glacial troughs/u-shaped valleys formed?

A
  • Channelling of ice through valleys and erosion
  • Before glaciation = active freeze thaw weathering under periglacial process weakens floor and sides of valley = preparation for rapid erosion during glaciation
  • During interglacial periods periglacial processes return and weaken further
  • As glaciation occurs ice begins to move (and down valley) deposited material is used for abrasion = created u shape
27
Q

What is periglacial?

A

An area either adjacent to a glacier or subject to repeated freezing and thawing

28
Q

What are the periglacial processes?

A
  • Mass movement
  • Freeze thaw weathering
  • High wind erosion
29
Q

What are truncated spurs?

A
  • Begin as interlocking spurs
  • as glaciation occurs ends of interlocking spurs are eroded through plucking and erosion (lie in the path of oncoming glacier)
  • Distructive effect forms truncated spurs
30
Q

How are ribbon lakes formed?

A

EXAMPLE = Lake Windermere, Lake District

  • Formed when ice extrusion erodes away at the floor of the valley and causes deep rok basin
  • Rock basin is eventually filled by precipitation and any meltwater that runs in off the mountain sides
31
Q

What are Fjords?

A

EXAMPLE = Sogne Fjord Norway

  • Glacial tough partly below sea level
  • Forms as any other u-shape valley does (but partly submerged) = cut into more resistant rock
  • Often long with great depth (sogne fjord = 1300m) extreme depth = lots of glacial erosion to construct landform
  • Sogne Fjord rises as closer to mouth of Fjord on coast
  • Suggests erosional power of glacier as it advanced to the seaward end of fjord was reduced = example of how shaped due to glacial erosion
32
Q

What are the processes/types of deposition?

A
  • Ablation
  • Directly from ice (unstratified till/boulder clay)
  • Fluvioglacial deposits (meltwater flowing from a glacier = stratified)
  • Deposits in front of glacier (proglacial deposits)
33
Q

What is stratified and unstratified?

A 
Stratified = sorted
Unstratified = not sorted
34
Q

What is ablation?

A

The removal of material (ice, debris) from a glacier such as melting, evaporation and sublimation

35
Q

What are the landforms of glacial and fluvioglacial deposition?

A
  • Till plains
  • Drumlins
  • Moraines
  • Varves
  • Esker
  • Kames
36
Q

What are till planes?

A

EXAMPLE = NW Norfolk

  • Mix of clay and stones deposited by glacier
  • Formed below a vast ice sheet covering Norfolk
  • Deposited during and after ice melted (450,000 years ago) in Anglian Glaciation
37
Q

What are drumlins?

A

EXAMPLE = Kendal Drumlins, Lake Districts

  • Small low hills in the shape of an inverted spoon
  • Blunt end of hill faces upstream direction and tapered end faces downstream in ice movement
38
Q

How do drumlins form?

A
  • Deposited from moving ice

- Form a swarn or field of a similar size/shape of hills (up to 40m high and 500m long)

39
Q

What are lateral moraines?

A

Formed by freeze thaw = above the glacier
Plucking = on valley sides
- Both lead to rocks falling into or onto valley glacial sides

40
Q

What are medial moraines?

A

Found at the tributary between two glaciers

41
Q

What are terminal moraines?

A

Found at furthest point reached by a glacier when the glacial snout bulldozes material ahead of it
- Formation depends on amount of material carried, rate of movement and rate of ablation (and amount of meltwater)

42
Q

What are moraines and how do they form?

A

Terminal, medial or lateral
EXAMPLE = Gorner Glacier, Zermatt, Sweden
- Unstratified deposits of angular rock fragments
How they form:
- When glacial ice melts = different types of rocks that have been carried are deposited forming moraines

43
Q

What are varves?

A

EXAMPLE = Lakes in Sweden and Finland

  • Layers of silt and sand which were deposited on the floor of a lake in advance of a glacier
  • Found in proglacial lakes in ice margins
44
Q

How do varves form?

A
  • Form from fluvial deposition
  • Each varve consists of 2 layers of sediment = fine sand sized particles and another of clay and silts
  • In summer = large flows of meltwater deposit thick layers of coarser sediment = bigger flow = more material is transported and deposited (usually fine sand)
  • In winter = smaller meltwater flows deposit finer material as lower velocity can only carry finer material (eg clays and silts) = each year = 1 year melting
  • Flow of meltwater affects rate of deposition of different sediments
45
Q

What are eskers?

A

EXAMPLE = Blakeney Esker, Norfolk

  • Long low winding ridge of stratified sands and gravels deposited in meltwater tunnel by meltwater under a glacier or ice sheet
  • Rarely well preserved
46
Q

How do eskers form?

A
  • Fluvial deposition
  • Sometimes transported load volume exceeds velocity required = deposition in tunnel = ice melts = eskers appear
  • Vary in size from few metres high to 50m high
47
Q

What are kames?

A

EXAMPLE = Talkin Tarn, Carlisle, Cumbria
- Mounds of stratified sands and gravels deposited along the front of a melting or stationary glacier, consisting of sands and gravels

48
Q

How do kames form?

A
  • Talkin Tarn is kettle-hole lake formed by glaciers 10,000 years ago when ice melted and permanent lake is created (water filled in it)
  • Fluvial-glacial sediments are washed into lake = stratified deposits forming in and around it (especially as velocity drops = deposition occurs)

Physical Geog = Cold and Arid (9 decks)

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