Glaciation EQ3 > Lesson 7 > Flashcards

Lesson 7 Flashcards

(67 cards)

Study These Flashcards
1
Q

What is everything in periglacial processes related to?

A

Freezing and thawing and the issues it causes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why are periglacial landscapes distinctive?

A

They form where temperature varies between -6°C and 6°C
This causes the freezing and melting needed to form the landscape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What % does water expand by upon freezing?

A

9%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the expansion of freezing water by 9% create?

A

Can cause frost shattering (freeze-thaw weathering)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 4 periglacial processes?

A
  1. Freee-thaw weathering
  2. Ground ice
  3. Solifluction
  4. Nivation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What other processes exist in periglacial environments (though aren’t exclusively periglacial)?

A
  • Wind
  • Fluvial action
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does periglacial mean?

A

Edge of glacial

Next to glacial areas on one side and non-periglacial areas on the other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where are periglacial landforms located?

A

On the fringes of polar environments, at high latitudes
Also at high latitudes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do periglacial landscapes contain?

A

Permafrost, however, the surface of ground thaws during the brief warmer summers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does permafrost vary with latitudes?

A

Levels of permafrost decrease as latitudes decrease
Continuous > Discontinuous > Sporadic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe where permafrost is found:

A

Found on the fringes of polar regions
In between polar and boreal conditions
In sub arctic conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does permafrost change from continuous > discontinuous > sporadic?

A
  • Depth of permafrost decreases
  • Level of melting increases
  • There is more talik
  • The active layer is thicker
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is talik?

A

Unfrozen areas in permafrost regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 3 layers of permafrost?

A
  • The top layer: the active layer - this melts and freezes with summer and winter temperature changes
  • The middle layer: the permafrost zone - temperatures are too cold to ever melt
  • Bottom layer: unfrozen ground - unfrozen due to geothermal gradient (pressure melting point reached)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name the ground ice features?

A
  • Ice wedge polygons
  • Patterned ground
  • Open system pingo
  • Closed system pingo
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ice wedge polygons
What are they?

A

Downward narrowing masses of ice, between 2-3m wide at the base and extend below the ground surface up to 10m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Ice wedge polygons
How do they form?

A

https://www.youtube.com/watch?v=8latUfAVFCA&t=12s

  • Refreezing of the active layer during winter causes the soil to contract and cracks to open
  • During the melting of the summer, cracks fill up with meltwater
  • Sediment then refreezes the following winter, widening and deepening the cracks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Patterned ground
What is it?
What changes the pattern?

A

A ground surface that has a pattern made from frost action separating soils.
The pattern changes with gradient (flatter surface creates more round polygons)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Patterned ground
How does it form?

A
  • Frost push propels the stones upwards by 9%
  • Beneath the stones fills with sediment
  • Frost heave causes stones to migrate outwards, forming circles
  • The up doming of the circle created by frost heaving means that larger stones move outwards due to gravity, leaving finer sediments in the centre
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Define frost push:

A

The horizontal movement of material at the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Define frost heave:

A

The vertical movement of material at the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Patterned ground
What is the gradient limit for patterned ground to form on?
What forms after this?

A

30°
Rock avalanches may occur (look like scree slopes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q
A

Ice wedge polygons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q
A

Patterned ground

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Open system pingo What are they also known as?
Hydraulic pingos
26
Open system pingo Where are they found?
Areas of discontinuous permafrost
27
Open system pingo How does it form?
- There is an ice core in the ground - The ice core grows due to freely available groundwater being drawn to it - As it grows, dilation cracks form. Air gets in, causing melting of the exposed ice - Process restarts
28
Open system pingo
29
Closed system pingo What are they also known as?
Hydrostatic pingos
30
Closed System Pingos Where do they form?
Low lying flat areas in zones of continuous permafrost with no free groundwater
31
Closed System Pingos How do they form?
As sediment is deposited in a lake, it loses its insulating effect on the permafrost below. The permafrost grows downwards, eventually forming dilation cracks and contributing to it melting
32
Give an example of a location with ice wedge polygons
Yukon Coastal Plain, Canada
33
Give an example of a location with patterned ground
Spitsbergen, Svalbard
34
Name a location with open system pingos
Lagoon Pingo Located in Adventdalen, Svalbard
35
Name a location with closed system pingos
Ibyuk pingo Tuktoyaktuk Peninsula, Canada
36
Name some processes associated with periglaciation
-Frost heave - Frost shattering
37
What is frost heave?
When freezing temperatures cause the upward swelling of soil and rock, elevating stones. Water feeds the frost, forcing the top layer upwards more and more
38
What is frost shattering?
Freeze-thaw weathering in periglacial environments When water in cracks freezes, it puts pressure on any cracks in the rock and can shatter them
39
What can frost shattering form?
- Block fields - Scree/talus slopes
40
What are the 2 main forms of mass movement?
- Frost creep - Solifluction
41
What is frost creep?
The very slow movement of material downslope due to expansion caused by freezing and contraction during thaws
42
Where does solifluction occur?
In regions with permafrost where, during the summer, the active layer melts, forming a mobile water saturated layer
43
What does solifluction create?
Stone banked or turf banked lobes on slopes of 10-20°
44
What is solifluction?
The slow, downhill flow of saturated soil The active top layer provides enough water to allow flow to occur and as saturated soil slumps downhill during the summer it forms solifluction lobes
45
What side of a valley would solifluction occur more on?
The side with sun
46
What are asymmetric valleys?
Valleys that have uneven valley sides
47
What forms asymmetric valleys?
Differing rates of solifluction and frost creep The side with the more gentle gradient has experienced more solifluction/frost creep
48
How do asymmetric valleys form in the northern hemisphere?
- South-facing slopes are more exposed to the sun so thaw more frequently - This increases soil moisture, promoting mass movement and leading to less steep slopes
49
What is nivation?
The localised process of both weathering and erosion taking place around or beneath a snow patch
50
Explain the process of nivation
- Snow accumulates in a hollow and due to temperature doesn’t melt - Year after year it grows and turns to ice in the lower layers under the pressure of the above snow - Eventually, the ice begins to move under its own weight downhill and erodes the ground to form a nivation hollow
51
52
What landform is nivation the start of?
Corries
53
Wind action Why does wind pay a large role in processes associated with periglaciation?
Due to periglacial environments generally suffering from extreme aridity due to being locked up in ice and a lack of flora
54
Wind action How can it impact the environment?
Wind can blow away nutrients
55
Wind Action How did winds impact periglacial landscapes in the Pleistocene?
Sediments forming sandurs were blown southwards and deposited as loess
56
What are loess
The most fertile ground on the planet
57
Give 2 examples of loess:
Pleistocene sediments formed loess over large areas of Europe and North America Winds of the Gobi desert are blowing fine material to the loess plateau in Northern China (therefore, loess are not unique to periglacial areas)
58
Water erosion When does water erosion occur?
Spring and summer Water erosion is highly seasonal
59
Water erosion Why does water erosion occur in spring and summer?
The melting of the active layer leads to short periods of high discharge
60
Water erosion What does the river discharge create?
Braided rivers Due to the high amount of material carried during higher discharge
61
Water erosion Are braided rivers unique to periglacial regions?
No - it can also be seen on many rivers in mountainous areas which suffer high discharge
62
How do braided rivers impact Keswick?
It's a major cause of flooding
63
What are paraglacial conditions?
The unstable conditions that begin to happen after a significant mass of ice has melted - exposing previously glacial landscapes to new processes
64
How can paraglacial conditions impact periglacial landscapes?
Can create a thermokarst landscape
65
What is a thermokarst landscape and how does it form?
A landscape with large surface depressions and irregular shaped lakes The ice in permafrost melts, so the active layer sinks (sinking creates the depressions, meltwater creates lakes)
66
How are relict periglacial landscapes in the UK determined?
Comparing current periglacial landscapes with features in the UK - the Principle of Uniformitarianism suggests that these areas were once periglacial
67
How does permafrost melt destabilise areas?
- As permafrost melts, the land becomes over saturated with water, causing it to be unstable - Ice wedges join together to form small lakes and then larger lakes as the active layer deepens - This destabilises areas
Glaciation EQ3
flashcards
Decks in class (5)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions