G: Glaciation > EQ3 > Flashcards

EQ3 Flashcards

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1
Q

What are the glacial erosion types?

A

-Abrasion
-Plucking
-Fracture and traction
-Dilation

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2
Q

What is abrasion?

A

Physical wearing of a surface through friction by material carried in water or ice

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3
Q

What is plucking?

A

Ice moving over bedrock freezes and then pulls away blocks of rock that are already weakened or jointed

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4
Q

What is fracture and traction?

A

The crushing effect of the weight of ice moving over rocks

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5
Q

What is dilation?

A

The removal of weight from the above, causes the bedrock to adjust and crack

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6
Q

How do you categorise the size of glacial landforms

A

Micro- <10m
Meso- 10m - 1km
Macro- >1km

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7
Q

What are corries?

A

Bowl-shaped hollows formed by rotational slip, plucking and abrasion of ice on a mountain slope.

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8
Q

What are aretes?

A

Sharp ridges formed when two corries erode back-to-back.

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9
Q

What are pyramidal peaks?

A

Pointed mountain tops formed when three or more corries erode into the same mountain.

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10
Q

What are truncated spurs?

A

Cliff-like valley sides formed when a glacier cuts straight through interlocking spurs.

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11
Q

What are u-shaped valleys?

A

Wide, deep valleys with steep sides formed when glaciers over-deepen and widen V-shaped river valleys.

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12
Q

What are hanging valleys?

A

Smaller valleys left high above the main valley floor where tributary glaciers joined a bigger glacier.

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13
Q

What are ribbon lakes?

A

Long, narrow lakes formed in over-deepened parts of glacial troughs.

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14
Q

What are whalebacks?

A

Smooth, rounded rock hills formed by abrasion on resistant rock.

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15
Q

What are roches moutonnées?

A

Asymmetrical rock outcrops with a smooth stoss side (abraded) and steep lee side (plucked).

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16
Q

What are striations?

A

Scratch marks cut into rock by debris at the base of a glacier, showing ice movement direction.

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17
Q

What are chatter marks?

A

Small crescent-shaped marks formed when rocks in the ice chip the bedrock under pressure.

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18
Q

What are crescentic gouges?

A

Curved depressions formed when ice plucks chunks of rock from the bed.

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19
Q

What are the 5 glacial sub-aerial processes?

A

-Freeze-thaw Weathering
-Frost Shattering
-Nivation
-Mass Movement
-Solifluction

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20
Q

What is freeze-thaw weathering?

A

Water enters cracks, freezes and expands, breaking rock apart.

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21
Q

What is frost shattering?

A

Repeated freezing and thawing weakens exposed rock, causing it to fracture.

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22
Q

What is nivation?

A

Weathering and erosion beneath snow patches, combining freeze-thaw, chemical weathering and meltwater erosion.

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23
Q

What is mass movement?

A

Blocks of rock break off steep slopes (often after freeze-thaw) and fall to the base.

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24
Q

What is solifluction?

A

Slow downslope flow of saturated soil over frozen ground in periglacial areas.

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25
Once rocks enter the glacial system and transported, it's classified as either:
-Supraglacial: On top -Englacial: Within the ice -Subglacial: Bottom of the ice
26
What are the 4 processes of glacial deposition?
-Lodgement -Ablation -Deformation -Flow
27
What is lodgement?
When subglacial debris is dropped and plastered onto the valley floor as the glacier loses energy.
28
What is ablation till?
Debris deposited as ice melts at the surface or snout of the glacier.
29
What is deformation till?
Material that is smeared and reshaped when subglacial sediment is deformed by the moving ice.
30
What is flow till?
Till deposited when water-saturated debris flows and spreads out from the glacier, often at the snout.
31
What are the 3 depositional landforms?
-Erratics -Drumlins -Moraines
32
What are erratics?
-Large rocks/boulders transported and deposited by a glacier, often sitting on completely different bedrock. -Formed when glaciers pick up resistant rocks and drop them far from their source.
33
What are drumlins?
Smooth, elongated hills of glacial till, with a steep stoss side and tapered lee side. Formed by ice reshaping subglacial debris, often moulded by lodgement and deformation.
34
What are moraines?
Ridges of till deposited by glaciers.
35
Name the 7 types of moraines
-Lateral -Medial -Terminal -Ground -Recessional -Push -Hummocky
36
What is a lateral moraine?
A ridge of debris along the sides of a glacier, formed from material falling off valley walls and carried by the ice.
37
What is a medial moraine?
A line of debris running down the middle of a glacier, formed when two lateral moraines merge where glaciers join.
38
What is a terminal moraine?
A ridge of till deposited at the glacier’s furthest advance, marking its maximum extent.
39
What is a ground moraine?
A thin, uneven blanket of till deposited beneath a glacier as it melts and retreats.
40
What is a recessional moraine?
A ridge of debris left behind when a glacier pauses during retreat, forming a series of smaller ridges behind the terminal moraine.
41
What is a push moraine?
A ridge of material shoved into place by the snout of an advancing glacier.
42
What is a hummocky moraine?
Irregular, mounded deposits of till formed as stagnant or dead ice melts in place, leaving uneven heaps of debris.
43
What are the main sources of glacial meltwater?
Surface melting (from insolation), pressure melting at the base, and geothermal heat.
44
Where does meltwater occur in a glacier?
On the surface (supraglacial), within the ice (englacial), and beneath the glacier (subglacial).
45
How does meltwater affect glacier movement?
It reduces friction at the base, enabling basal sliding and faster ice flow.
46
What is the role of meltwater in erosion?
It carries rock debris that can abrade bedrock and also helps plucking by freezing onto rock.
47
What is the role of meltwater in transportation?
It transports fine sediment (glacial flour) and larger debris through glacial streams and rivers.
48
What is the role of meltwater in deposition?
It sorts and stratifies sediments, depositing sands and gravels in outwash plains, eskers, and kames.
49
How does seasonal meltwater vary?
More abundant in summer due to higher melting, less in winter; this causes seasonal changes in glacial movement and deposition.
50
What the 4 landforms are created by meltwater deposition?
-Eskers -Kames -Outwash planes -Kettle holes
51
How are eskers formed?
Long, winding ridges of sand and gravel deposited by meltwater streams flowing through subglacial tunnels. When the ice melts, the sediments are left behind as raised ridges.
52
How are kames formed?
Mounds of sand and gravel deposited in hollows on the glacier surface by meltwater streams. When the ice melts, the debris collapses to form irregular hills.
53
How are outwash plains formed?
Broad, flat areas of sand and gravel deposited by meltwater streams beyond the glacier snout. Sediment is sorted and stratified as meltwater spreads out, losing energy.
54
How are kettle holes formed?
Depressions formed when blocks of dead ice are buried in outwash or moraine, then melt, leaving behind hollows that may fill with water to form small lakes.
55
What is a proglacial lake?
A lake formed in front of a glacier where meltwater is dammed by moraines or ice.
56
What does peri-glacial mean?
Areas at the edge of glaciers, subject to intense freeze–thaw and permafrost conditions
57
What is freeze–thaw?
Water enters cracks in rocks, freezes, expands by ~9%, and fractures the rock. This produces angular debris (scree/talus) and contributes to blockfields.
58
What is the movement of subsurface water?
In permafrost areas, only the active layer thaws in summer. Meltwater moves above the frozen ground, causing frost heave, patterned ground, and pingos.
59
What is mass movement?
The downslope movement of saturated soil and debris over impermeable permafrost, especially solifluction, forming lobes and terraces.
60
What are wind, snow and fluvial processes?
Strong winds transport fine material (loess), snow patches erode hollows (nivation), and meltwater streams create braided rivers and deposit sorted sediments.
61
Name the 10 periglacial landforms
-Ice Wedge Polygons -Pingos -Patterned ground -Terraces, benches and coombes -Asymetrical valley -Scree slopes -Nivation hollows -Sandurs -Loess -Braided rivers
62
What are ice wedge polygons and how do they form?
Networks of cracks in permafrost that fill with ice, widening over time. Repeated freeze–thaw creates polygon-shaped surface patterns.
63
What are pingos and how do they form?
Dome-shaped hills of ice-covered by soil. They form when groundwater freezes and expands under pressure (open-system or closed-system pingos).
64
What is patterned ground and how does it form?
Surface stone/soil arranged in polygons, stripes, or circles. Caused by frost heave pushing larger rocks upward, then sorting them by size.
65
What are terraces, benches and coombes in periglacial areas?
Step-like features on slopes. Formed by solifluction or nivation processes where material moves downslope, leaving flat or hollowed-out surfaces.
66
What are asymmetrical valleys in periglacial areas?
Valleys where one slope is steeper than the other due to differential frost action, solifluction, and aspect (sunlight exposure).
67
What are scree slopes and how do they form?
Slopes of angular rock fragments at the base of cliffs, produced by freeze–thaw weathering (frost shattering).
68
What are nivation hollows and how do they form?
Small depressions beneath persistent snow patches. Freeze–thaw, meltwater erosion, and chemical weathering enlarge the hollow.
69
What are sandurs and how do they form?
Outwash plains made of sand and gravel, deposited by meltwater streams flowing from glaciers.
70
What is loess and how does it form?
Fine silt and dust blown by strong periglacial winds from outwash plains, deposited in thick layers far from the glacier.
71
What are braided rivers and how do they form?
Meltwater rivers carrying high sediment loads, splitting into multiple interweaving channels across outwash plains as energy changes.
72
What is an example of a periglacial environment and its features? (Baffin Island, Northern Canada)
-Baffin Island is in the Canadian Arctic, characterised by continuous permafrost, low precipitation, and long cold winters. -Periglacial processes include freeze–thaw and solifluction. -Landforms found there include ice wedge polygons, pingos, patterned ground, scree slopes, and braided meltwater streams in summer. -Human impacts (mining, settlements, infrastructure) are affected by permafrost thaw, causing ground instability.
G: Glaciation
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