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GL 5 Flashcards

(52 cards)

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1
Q

What is a periglacial landscape?

A

Landscape that undergoes seasonal freezing and thawing
25% of Earths landscape contains permafrost

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2
Q

What is permafrost

A

Ground that remains frozen for 2 or more consecutive years

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3
Q

What are some factors that impact permafrost

A

Proximity to water bodies
Slope angle and orientation
What surface is made from
Vegetation cover
presence of snow

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4
Q

What is the mean annual temperature needed for permafrost to occur?

A

-2 degrees celcius

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5
Q

How deep can permafrost be?

A

up to 1500m

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6
Q

What is the active layer

A

Thin layer of soil on top of permafrost that can thaw, plants grow here

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7
Q

What is continuous permafrost?

A

Forms in the colder areas of the world, where temperatures are below -6 degrees Celsius, extending down hundreds of meters

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8
Q

What is sporadic permafrost?

A

Like continuous but fragmented and thinner

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9
Q

What is discontinuous permafrost?

A

Occurs at margins of periglacial environments and is fragmented and only a few meters thick

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10
Q

Why is the melting of permafrost so detrimental to climate change

A

Permafrost contains lots of methane, due to dead organisms being broken down during anarobic respiration the melting of which releases it.

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11
Q

What are some negative impacts of permafrost melting?

A

Damage to infrastructure, Loss of habitats, Global warming

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12
Q

What percentage of animals live in permafrost environments

A

Half

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13
Q

What makes methane worse for global warming then carbon dioxide

A

Methane is 25x more potent, meaning high global warming potential

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14
Q

How is pore ice formed?

A

Develops in pore space between sediment particle

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15
Q

How is needle ice formed?

A

form in moist soils overnight

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16
Q

What is an ice lenses

A

cause up doming of ground (earth hummocks) during frost heave, up to several meters in high and diameter

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17
Q

Explain the formation of an ice lenses

A

bodies of ice are formed when moisture, mixed within soil or rock, accumulates in a localised zone, because rates of freezing are unequal in the active layer

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18
Q

What are ice wedges

A

downward narrowing lens,

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19
Q

Explain the formation of ice wedges

A

In winter, ice is in the crack, in summer, this ice thaws, in the second winter Water freezes and expands by 9%, forming layer, annual freezing and thawing causes expansion, ridges form as sediment is pushed off.

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20
Q

Explain the formation of ice wedge polygons

A

Ground contracts and cracks in winter, in summer crack fill with water, this freezes and keeps the cracks open

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21
Q

What is patterned ground?

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A

stones arranged in geometric shapes, (stripes, circles and polygons)

22
Q

Explain why stones move to the surface in periglacial environments?

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A

Ground will freeze downwards, stones are good conductors of heat, so when temperatures drop and expanding ground begins to lift the stone. Small amounts of moisture beneath the stone freeze and turn into ice, expanding by 9%. Cryostatic pressure, raises the stone (frost heave). Ice thaws, wet sediment slumps into gap beneath the stone, after many repetitions, stones break through the surface.

23
Q

What happens after stones break through the surface

Study These Flashcards
A

Sones roll to the base of mound, steep hills, cause stripes, gradual gradients form polygons or circles

24
Q

Why are patterns formed in patterned ground?

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A

Different patterns are formed by the topography of the ground (rocks roll)

25
What is a pingo
Ice cored hill
26
What is the largest pingo
Kadleroshilik Pingo, Alaska, 54m high
27
Where are closed system pingos found, where are open system pingos found
Closed - continuous permafrost Open - discontinuous permafrost
28
Explain stage 1 open system pingo formation
Groundwater is confined beneath the permafrost. It finds a weakness in the permafrost and rises due to artesian pressure. As the water rises, it cools and freezes, if it reaches the surface by summer it may form a spring.
29
Explain stage 2 of open system pingo
During winter the rising water freezes before reaching the active layer, forming an ice lens. As more groundwater rises from below the permafrost, it grows, displacing the overlying sediment, forming a domed ice hill, known as an open system pingo
30
Explain stage 1 of closed system pingo
Lakes form withing active layer during summer months, during winter this begins to freeze. Unfrozen water and lake sediment insulate the underlying ground, preventing ground from freezing (talik)
31
Explain stage 2 of a closed system pingo
During cold, permafrost advances, encroach on Talik, liquid water freezes, becoming an ice lens. Ice lens grows, exerting cryostatic pressure, displacing overlying lake, sediment at bottom of lake now covers top.
32
What is a thermokarst landscape
irregular surfaces, marshy hollows and depressions
33
What is a thermokarst landscape formed by
Permafrost thawing due to warming climate.
34
What is solifluction, what is this caused by
Wet, saturated active layer moves slowly downhill, due to gravity
35
What are thermokaust lakes, what is one cause
Formed in a depression by meltwater from thawing permafrost Pingo collapse, water cannot percolate downwards into impermeable permafrost
36
Explain pingo collapse
Temperatures warm, increased meltwater, ice lens begins to be exposed, solifluction of sediment in both directions atop the ice lens occurs, causing a depression when ice lens is reduced.
37
What is the Batagay crater, where is it, what is happening to it
In russia, permafrost is melting, forming a crater
38
What is causing the batagay crater?
Global warming - artic warms 2x faster (artic amplification) South facing slopes experiencing most melting mass solifluction
39
What proportion of Russia has permafrost?
Over half
40
What is the problem with melting permafrost in Russia?
In villages like bataguy, the ground gives way and buildings collapse
41
How much is the bataguy crater increasing each year?
10-15cm
42
What is a block field Example
surface covered by large angular rocks, product of freeze thaw on a flat plateau Glyder Fawr - Nant Ffrancon valley
43
Explain the formation of a scree slope Example
Freeze thaw occurs at the top of a drop, rock falls to the base this reduces slope angle, overtime weathered rock from the top accumulates at the base Cwm Idwal
44
Explain the formation of a protalus Rampart, Example
Same formation as a scree slope, but with added ice in the middle, this causes rocks to build up around the ice. When the ice melts, a bulge in a slope is left. Cwm Idwal
45
Outline the process of solifluction
Active layer thaws, permafrost remains frozen, surface layer becomes water logged because water cannot infiltrate and percolate into permafrost.
46
Explain frost creep
On slopes, during summer, the active layer thaws, in winter, when this freezes, it expands outwards (frost heave), during the next summer, particles drop vertically, forming terracettes
47
Explain solifluction sheets and lobes
Solifluction occurs at different rates due to the topography of the land, causing lobes and sheets to be formed
48
Explain the formation of dry valleys in periglacial environments
Develop in areas of permeable rock in active layer, surrounded by permafrost, When ice masses retreat, meltwater erodes and deepens river 'V' shaped valleys, when permafrost has melted, water can infiltrate, reducing surface run off and leaving river valley dry
49
Give an example of a dry valley
Yorkshire dales
50
What is Loess deposits
Fine rock debris transported (deflation) and deposited by winds, creating flat plateaus
51
Explain Loess deposits
derived from glacial abrasion, which is transported by meltwater to sandurs, during colder months, large parts of the sandur will dry out, exposed to strong winds
52
How can wind impact of glacial depris
Loess deposit Abrasion

GEOGRAPHY (21 decks)

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