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geography > ❄️ glaciation sg6 > Flashcards

❄️ glaciation sg6 Flashcards

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1
Q

what is a periglacial area

A

areas with permafrost, seasonal temp variations & ftw cycles

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2
Q

what are the characteristics of permafrost

A

ground remains frozen for at least 2 consecutive years and is overlain by an active layer

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3
Q

what % of the earth is covered in periglacial landscape

A

25%

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4
Q

what is solifluction

A
  • upper layer of soil melts so water can’t drain away
  • active layer of soil is saturated & moves downslope
  • very slow mass movement so active layer moves downhill when slope is over 2 degrees
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5
Q

what is nivation

A

occurs under permanent snow patch = enlargement of hollows

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6
Q

what is frost heave

A

uplift of soil or individual stones within soil due to formation of ground ice

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7
Q

what are pingos

A

rounded, ice core hills up to 90m high & 800m wide

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8
Q

how does a pingo form

A
  • water percolates through talik within permafrost
  • groundwater from surrounding slopes collects on valley floor
  • water rises to surface under artesian pressure and when it encounters colder ground it freezes
  • ice lens continues to grow & becomes large
  • this displaces the sand & gravel above to form a pingo
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9
Q

how does an ognip form

A

when an ice lens grows so large that it ruptured surface so sun will melt the ice. done will collapse and a ridge is left around the circular depression

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10
Q

what are the characteristics of patterned ground

A

stone stripes or polygons
1-5m in diameter
done height between 10cm-10m

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11
Q

how does patterned ground form

A
  • stones have high shc so when soil drips below 0^c water beneath a stone freezes = ice lens
  • these grow & push stones up through soil
  • temps rise so ice lens thaws but fine material infill under risen stones so stones can stay high up
  • repeated ftw = stones pushed up & eventually reach surface
  • frost heave = domed surface & surface stones roll downhill to edge of mounds
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12
Q

how can patterned ground be modified with climate change

A
  • permafrost thaws = depressions sink within polygon
  • more meltwater in active layer = solifluction
  • biological weathering
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13
Q

what is a thermokarst landscape

A

areas of hummocky, irregular ground interposed by waterlogged depressions created as ground ice thaws.
depressions fill with water to form shallow lakes

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14
Q

what is a positive feedback loop within thermokarst landscape

A
  1. increases flows of energy into periglacial system
  2. permafrost thaws = waterlogged depressions
  3. water has higher shc = retains heat for longer than surrounding land
  4. permafrost thaws
  5. depth of active layer increases
  6. more permafrost thaws
    back to 2.
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15
Q

what human activity takes place in a periglacial landscape

A
  • oilfields in prudhoe bay
  • trans alaskan pipeline (tap): 800 miles long & transports oil from bay to valdez
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16
Q

why does human activity take place in prudhoe bay

A
  • in top 20 largest oil fields in the world
  • provides 20% of country’s oil consumption
  • takes dependency away from middle east for oil as it could be unreliable
  • 1/3rd of Alaskan jobs
17
Q

what is the impact of human activity on flows of material

A

gravel taken from river beds to put under buildings = altered rates of erosion & deposition of gravel & in river

18
Q

what is the impact of human activity on flows of energy

A
  • oil rigs & oil drilling release heat to ground
  • has released & then burnt = fossil fuels = temp increase
  • airstrips = lower albedo = more heat absorbed
  • dust from gravel roads kill vegetation = less shade = melting
19
Q

how does removal of vegetation influence periglacial landscape

A
  • deeper active later
  • an area without vegetation will have an active layer 7m deeper than an area with vegetation after 26 years
20
Q

how does increased solifluction influence a periglacial landscape

A
  • thawing of perfmasfrost = active layer is created = saturated material
  • layer moves downslope
21
Q

how does an alas form

A

when an ice wedge melts and the depression fills with water. water evaporates when temps warm so lake is replaced with vegetation

geography (27 decks)

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