Glaciated Landscapes Flashcards
(162 cards)
1
Q
What is an esker?
A
A long sinuous ridge of sorted glacio-fluvial sand and gravel, deposited by sub-glacial meltwater streams flowing within, beneath, or on top of a glacier
2
Q
What are the key characteristics of eskers?
A
- Long, winding ridges (up to 100km)
- Composed of stratified, sorted sediment (sand, gravel)
- Material is rounded due to water transport
- Run parallel to former ice-flow direction
- Can be up to 30m high and several metres wide
- Often occur in groups or braided systems
3
Q
What is the formation process of an esker?
A
1) During warmer periods, meltwater channels form beneath or within a glacier (sub-glacial or en-glacial).
2) These channels carry high-pressure meltwater loaded with sediment.
3) As the glacier retreats, these sub-glacial streams begin to deposit sediment (as velocity and pressure fall).
4) The deposited sediment builds up within the ice tunnel.
5) When the glacier fully melts, the sediment ridge is left behind as an esker.
4
Q
Why are eskers often curved, twisted, and elevated above surrounding ground?
A
Meltwater channels beneath glaciers are pressurised, and don’t follow gravity alone - they follow the path of least resistance.
5
Q
What shape is an esker?
A
Long sinuous ridge
6
Q
Is the material deposited within an esker sorted?
A
Yes, sorted and stratified
7
Q
Where do eskers form?
A
Inside / under glaciers
8
Q
What type of landform is an esker?
A
A glacio-fluvial landform
9
Q
What is a pingo?
A
An ice-cored, dome-shaped hill found in permafrost environments, created by the freezing and expansion of groundwater which heaves the overlying ground.
10
Q
Where are pingos found?
A
Permafrost environments / periglacial areas, e.g Alaska. Also found as relict features, e.g in Norfolk.
11
Q
What is the life-cycle of a pingo?
A
1) Water accumulates beneath surface (from slope water or groundwater).
2) Water freezes and expands, forming an ice core.
3) Ground surface is pushed upward, and a dome shape forms
4) Over time, the pingo grows as the ice core expands
5) If the ice core melts (due to climate warming or human disturbance), the pingo collapses.
6) Collapse forms a pingo scar / ognip, a depression that may fill with water.
12
Q
What is the water-source for an open system pingo?
A
External groundwater from surrounding slopes (runoff) (slope-fed)
13
Q
What is the water-source for a closed system pingo?
A
Trapped groundwater (from a lake)
14
Q
What type of permafrost do open system pingos form in?
A
Continuous permafrost zones
15
Q
What type of permafrost do closed system pingos form in?
A
Discontinuous permafrost zones
16
Q
Where do open system pingos form?
A
Valley bottoms
17
Q
Where do closed system pingos form?
A
Flat, poorly drained lowlands
18
Q
How do pingos link to climate?
A
- Warming temperatures or human activity lead to melting of the ice core and collapse of the dome, leaving behind a pingo scar
- Pingo scars provide evidence of past periglacial conditions
19
Q
Where in the world can you find active pingos?
A
Alaska, Northern Canada, Siberia
20
Q
Where in the world can you find pingo scars / ognips
A
East Anglia, UK
21
Q
What is moraine?
A
The accumulated, unsorted debris (till) deposited by a glacier. It consists of a mixture of clay, sand, gravel and boulders - and is usually angular, as it’s produced by plucking and freeze-thaw.
22
Q
What are the key characteristics of moraine?
A
- Unsorted (unlike glacio-fluvial landforms).
- Made of sub-glacial and en-glacial debris.
- Deposited when the glacier loses energy, particularly at the snout or margins.
- Formed by direct glacial deposition, not by meltwater.
23
Q
What are the different types of moraine
A
- Lateral
- Terminal
- Recessional
- (Medial)
- (Ground)
24
Q
Where does lateral moraine form?
A
Along the sides of a glacier
25
How does lateral moraine form.
Valley walls are weathered, debris falls onto the glacier and is transported along. When the ice melts, it leaves a ridge of debris.
26
How does terminal moraine form?
Forms at the furthest extent of glacial advance (the snout). A ridge of till marks the maximum point the glacier reached, indicating past glacier size and power. This is good evidence for past climate conditions.
27
How does recessional moraine form?
Behind terminal moraine, created during temporary stand-stills or re-advances in a glacier's retreat. Forms as a series of ridges marking pauses in retreat.
28
What is the formation process of moraine?
1) Glacial processes like plucking & freeze-that break off rock.
2) Debris is carried on, in, or under the ice (supraglacial, englacial, subglacial).
3) As the glacier melts or retreats, it drops this unsorted material.
4) Depending on where it's deposited, different types of moraine form.
29
What is a kame?
An irregularly shaped mound or hill of sorted glacio-fluvial sand and gravel, deposited by meltwater in contact with glacial ice.
30
What are the key characteristics of kames?
- Composed of sorted sands and gravels (unlike moraines).
- Formed by meltwater, so they're glacio-fluvial, not glacial.
- Often found in lowland areas near former glacier margins.
- Can be single mounds or found in groups (kame fields).
- Associated with retreating glaciers.
31
What is the formation process of a kame?
1) Meltwater streams on top or along sides of the glacier carry sediment.
2) Sediment accumulates in depressions, crevasses, or between ice and valley walls.
3) As the glacier melts, the sediment is deposited in place.
4) Once ice melts away completely, the deposited material remains as mounds or ridges - these are kames.
32
What are the 2 types of kames?
- Delta kame: Forms where meltwater flows into a pro-glacial lake, drops load.
- Kame terrace: Sediment builds up between glacier and valley side - forms flat bench.
33
Where are kames found?
In areas formerly covered by glaciers, especially:
- Scotland
- Canada
- Northern USA
34
Are kames sorted?
Yes, by meltwater
35
Describe the appearance of a kame
Mound / hummock
36
What is basal shear stress?
THe frictional force that's exerted at the base of a glacier, caused by the glacier's weight and gravity pulling it downslope.
37
What does abrasion do to surfaces
Erodes and smooths them, which is important for U-shaped valleys as well as corries.
38
What does plucking do besides contribute to erosion?
Steepens back walls, and sharpens ridges.
39
What is the rock below a glacier called?
Bedrock
40
What is the material picked up and incorporated into a glacier called?
Entrained material
41
What is rotational slip?
The curved, down-slope movement of glacier ice along a concave (spoon shaped) slip plane under the influence of gravity.
- Occurs mostly in corries
- Instead of sliding straight down-hill, the ice moves in an ark-like path, eroding and deepening the hollow into a bowl shape.
42
What is a U-shaped valley?
A wide, steep-sided valley with a flat floor.
- It was initially a V-shaped valley formed by fluvial processes.
- When a valley glacier flows through it, the huge erosive power of the glacier widens, deepens, and straightens the valley.
- The slope changed from a "v" (narrow and steep), to a "U" (wide, steep sides, flat base.
43
What processes form U-shaped valleys / glacial troughs?
Abrasion: Glacier's basal debris scrapes and polishes the valley floor and sides.
Plucking: Glacier freezes onto rocks at valley sides and base, pulling them away as it moves.
Basal shear stress helps move the glacier forward with high erosive energy.
Rotational slip and pressure can intensify erosion on some sections.
Result: The valley becomes wider, deeper, and straighter, forming a glassic U-shaped valley / glacial trough.
44
What is a ribbon lake?
A long, narrow, deep lake occupying the over-deepened parts of a glacial trough. They form where differential erosion occured.
45
What is differential erosion?
When a glacier erodes soft, less resistant rock faster than hard, resistant rock. This uneven erosion creates landforms like ribbon lakes.
46
How does a ribbon lake form?
1) Glacier flows through a V-shaped valley.
2) Abrasion and plucking widen, deepen and straighten the walls of the valley into a U-shaped valley.
3) Where softer rock bands occur, differential erosion causes over-deepening.
4) Glacier melts and post-glacial meltwater fills the over-deepened hollows, forming a ribbon lake.
47
What is a corrie?
A bowl-shaped hollow formed by nivation enlarging a hollow, then further deepening from rotational slip, plucking, abrasion and freeze-thaw.
48
How does a pyramidal peak form?
When three or more corries develop back-to-back, and the corries erode towards each other, steepening their back walls. Erosional processes steepen and narrow the ridges between the corries, creating a sharp, pointed pyramidal peak.
49
How does a corrie form?
1) Snow accumulates in a hollow on a mountainside, compressing into ice.
2) The glacier moves by rotational slip, eroding the hollow by abrasion and plucking.
3) Erosion is most powerful at the back wall and base, deepening the hollow and steepening the back wall.
4) A raised lip forms at the front due to reduced erosion or deposition.
5) When the glacier melts, a tarn (corrie lake) may form in the deepened hollow.
50
What is a hanging valley?
A hanging valley is a smaller valley that joins a main glacial trough but is left suspended above the main valley floor after glaciation, often a waterfall flows from the main hanging valley into the main U-shaped valley.
51
How does a hanging valley form?
1) A smaller tributary glacier flows into a main glacier valley.
2) The main glacier is larger and more powerful, so it erodes its valley much deeper through abrasion and plucking.
3) The tributary glacier, being smaller, erodes less deeply.
4) After the glaciers melt, the tributary valley is left "hanging" above the main U-shaped valley.
5) Waterfalls often form where rivers flow from the hanging valley into the main valley below.
52
What is nivation?
Nivation is a combination of freeze-thaw weathering and erosion that happens beneath a patch of snow, usually in sheltered hollows. The snow protects the ground but also causes repeated freezing and thawing, which breaks up the underlying rock. When the snow melts, the meltwater carries away the loosened debris, gradually enlarging the hollow. This process can eventually lead to the formation of a corrie.
53
What is a roche moutonnée?
A rock outcrop shaped by glacial erosion. It featurs a smooth, gently sloped upstream side (stoss), and a steeper, jagged side (lee), formed as a glacier moves over resistant bedrock.
54
How does a roche moutonnée form?
1) A glacier flows over a resistant rock outcrop in its path.
2) On the upstream (stoss) side, pressure and friction cause abrasion, smoothing and polishing the rock.
3) On the downstream (lee) side, pressure drops, causing meltwater to refreeze and pluck rock away, leaving a jagged, steep slope.
4) The result is an asymmetrical landform with a smooth, gently sloping stoss side and a rough, steep lee side.
55
Why is a glacier an open system?
Because it has:
- Inputs e.g snowfall, solar energy
- Flows / Transfers e.g movement of ice, basal sliding
- Stores e.g glacial ice, debris
- Outputs e.g meltwater, evaporation
Energy and material move in and out of the system - it's not closed.
56
What is mass balance?
The difference between accumulation and and ablation over a year.
57
What does a positive mass balance mean?
The glacier is growing year-on-year.
58
What does a negative mass balance mean?
The glacier is shrinking year-on-year.
59
What is accumulation?
Gain of ice / snow.
60
What is ablation?
Loss of ice e.g melting, evaporation.
61
What is dynamic equilibrium?
The balance between inputs (e.g. snowfall, avalanches) and outputs (e.g. meltwater, sublimation) in a glacial system. When this balance is maintained, the glacier's size and mass remain relatively constant over time, even though material is continuously moving through the system.
62
What is feedback?
When a change amplifies (positive) or counteracts) further change in the system.
63
What is are 2 examples of positive feedback?
1) Albedo effect & melting (most common)
- Initial change: melting exposes darker rock
- Effect: decreased albedo, so more melting
2) Meltwater lubrication (advanced)
- Initial change: Increased melting produces more meltwater at the glacier bed.
- Effect: More basal sliding (as meltwater acts as lubricant), so glacier moves forward, leading to more friction, therefore more melting, and faster movement.
64
What is are 2 examples of Negative feedback?
1) Snowfall recovery
- Initial change: Glacier melts and retreats slightly.
- Effect: Cooler local micro-climate or increased snowfall leads to increased accumulation, restoring the glacier mass and stabilising the glacier size.
2) Reduced ice mass slows ablation (advanced)
- Initial change: Glacier retreats and thins.
- Effect: Thinner glacier has less surface area, which leads to less absorption of solar energy, leading to a slower rate of ablation, slowing down glacial retreat.
65
What is sublimation?
The process by which ice turns into water vapour without passing through the liquid phase.
66
What are periglacial landscapes?
Periglacial landscapes are cold, non-glaciated areas found on the edge of glacial regions. They experience intense freeze-thaw cycles and are dominated by permafrost, permanently frozen ground.
67
What features are present within periglacial landscapes?
Pingos, patterned ground, and solifluction lobes.
68
Which processes take place within periglacial landscapes?
Frost heave, freeze-thaw, solifluction, nivation, ground ice dynamics, and seasonal melting.
69
How can glacial landforms be used as evidence for past climate change?
1) Terminal moraines
- Mark the maximum extent of glaciers
- If we find multiple terminal moraines at different positions, it suggests glaciers have retreated over time, showing progressive warming.
2) Erratics
- Glacial erratics found far from their source show the previous movement of ice over large distances.
- Their presence far south compared to current ice sheets suggests past periods of colder climate followed by warming.
70
What happens if equilibrium in a glacial system is disturbed?
Self-regulation takes place to restore equilibrium, resulting in dynamic equilibrium.
71
Why are glaciated landscapes viewed as systems?
- Stores and processes
- They transfer energy and material
72
Which physical factors influence glaciated landscapes?
Climate:
- Wind
- Precipitation
- Temperature
Geology
- Lithology
- Structure
Latitude & Altitude
- High latitudes
- Low latitude but high altitude
Relief & Aspect
- Microclimate
- Aspect facing away from sun
73
How does wind influence glaciated landscapes?
Picks up material and uses it in the processes of erosion, deposition and transportation (aeolian processes.
74
How does precipitation influence glaciated landscapes?
Provides the input of snow, sleet and rain. This may have a large seasonal variation.
75
How does temperature influence glaciated landscapes?
Affects input & output to the system - if temperature rises, snow melts and becomes output. In areas of high altitude, there may be summer snowmelt, and in areas of high latitude temperatures may never rise above zero.
76
How does lithology influence glaciated landscapes?
Affects the impact of weathering, erosion and mass movement processes. For example, clay has a weak lithology, and erosion is very effective. Limestone is vulnerable to chemical weathering because of its calcium carbonate.
77
What is lithology?
The chemical and physical composition of rocks.
78
What is structure?
The existence of joints, bedding planes, faults, and the permeability of rocks.
79
How does structure influence glaciated landscapes?
Primary permeability: When a rock has pores that can absorb and store water, e.g chalk.
Secondary permeability: When water seeps into joints & cracks e.g limestone.
Angle of dip is also influential, for example horizontal strata result in steep profiles of valley sides.
80
How does latitude influence glaciated landscapes?
At high latitudes, e.g Arctic and Antarctic circles have cold dry climates; Landscapes develop under relatively stable ice sheets.
At low latitudes but high altitudes, landscapes develop under dynamic valley glaciers, e.g Rocky mountains.
81
How do relief and aspect influence glaciated landscapes?
- Microclimate can be affected by relief and aspect.
- Steep relief gives more energy to a glacier because of gravity
- Where an aspect faes away from the sun, temperatures remain below 0 for longer and so there will be less melting: glacial budget will be positive.
Where aspect faces the sun there is more melting / ablation, and a potentially negative budget.
82
What is the case study for human impacts on glaciated landscapes?
Grande Dixense Scheme
83
What and where is the Grande Dixense Scheme?
It's a hydro-electric power scheme located in Switzerland. It features the largest gravity dam in the world. The power supplies 400,000 households.
Glacial meltwater is collected from 35 glaciers, then diverted through 100km of tunnels and pipelines, and stored in a reservoir behind the dam. When electricity is needed, water is released from the reservoir. This then flows down high-pressure pipes, into four hydro-electric power stations. There, the meltwater drives turbines. The water is then discharged into the river Rhone.
84
What is are the positive impacts of the Grand Dixence scheme?
- Provides renewable hydroelectric power (~2,000 GWh/year) from glacial meltwater, reducing reliance on fossil fuels.
- Helps regulate seasonal meltwater, preventing flooding and managing water supply.
- Supports sustainable tourism and economic development in alpine areas.
🧠 Fact to remember: Collects water from 35 glaciers and supplies electricity to 400,000 households.
85
What is are the negative impacts of the Grand Dixence scheme on glaciated landscapes
- Disrupts sediment transport as stored meltwater is sediment-poor, leading to downstream erosion.
- Reduces summer river flow by 10–20%, affecting aquatic ecosystems and the natural hydrological regime.
- Alters the visual landscape and contributes to local ecological imbalance.
86
What is a periglacial environment?
An environment found on the edges of glacial areas, characterised by permafrost (permanently frozen ground), intense freeze-thaw processes, and seasonal temperature variation.
87
What are the key characteristics of periglacial environments?
- Presence of permafrost
- Intense freeze-thaw action
- Short, cool summers and long, cold winters
- Low precipitation (cold deserts)
88
What are the three types of permafrost?
- Continuous: Covers nearly all ground, very cold regions
- Discontinuous: Patchy, with thawed areas
- Sporadic: Isolated patches, near margins of periglacial zones
89
What processes operate in periglacial environments?
- Frost heave
- Solifluction
- Nivation
- Freeze-thaw weathering
- Groundwater freezing and thawing
- Permafrost dynamics (e.g thawing, active layer movement)
89
What is the active layer?
The top layer of soil above permafrost that thaws in summer and re-freezes in winter. It is prone to mass movement and ground instability.
90
What is frost heave?
The upward movement of soil and stones due to ice lens growth beneath them during freezing. It helps form patterned ground.
91
What is solifluction?
The slow downhill flow of water-saturated active layer material over frozen ground, forming solifluction lobes.
92
What is patterned ground and how does it form?
Surface materials like stones and soil are rearranged into polygons, circles, or stripes due to frost heave and freeze-thaw cycles.
93
What are thermokarst landscapes?
Depressed landforms formbed by the melting of ground ice, causng surface subsidence. Often found where permafrost has been disturbed.
94
What are the impacts of oil extraction in Alaska on periglacial landscapes?
- Permafrost thaw due to heat from infrastructure
- Thermokarst formation and ground subsidence
- Disrupted sediment and ater flows from gravel pads, roads, and pipelines
- Damage to patterned ground and ice wedges
- Altered energy flows (anthropogenic heat)
95
How is the extracted oil in Alaska transported?
Via the Trans-Alaska Pipeline (1,300km) from Prudhoe Bay to Valdez
96
How is infrastructure in periglacial landscapes adapted to reduce impact on permafrost?
- Elevated pipelines to allow air circulation
- Gravel pads to insulate permafrost
- Winter-only roads to minimise active layer disruption
97
How does patterned ground form?
1) Water in the active layer freezes, forming ice lenses.
2) The ice lenses expand, lifting finer particles (frost heave).
3) Upon thawing, larger stones migrate downward and outward (frost sorting).
4) Repeated freeze-thaw cycles cause stones to arrange into patterns such as circles, polygons, or stripes depending on slope gradient and soil type.
98
What type of landform is a corrie?
Erosional (upland)
99
What are the processes involved with the formation of a corrie?
Nivation, freeze-thaw, rotational slip, abrasion, plucking
100
What type of landform is an arete?
Erosional
101
What are the processes involved with the formation of an arete?
Abrasion, Freeze-thaw (between corries)
102
What type of landform is an pyramidal peak?
Erosional
103
What are the processes involved with the formation of an pyramidal peak?
Plucking, Abrasion, Freeze-thaw (intersection of 3+ corries)
104
What type of landform is a U-shaped valley?
Erosional
105
What are the processes involved with the formation of a U-shaped valley?
Abrasion, plucking, basal shear stress, rotational slip
106
What type of landform is a hanging valley?
Erosional
107
What are the processes involved with the formation of a hanging valley?
Reduced glacial erosion in tributaries, Abrasion, Plucking
108
What type of landform is a ribbon lake?
Erosional
109
What are the processes involved with the formation of a ribbon lake?
Abrasion, Over-deepening, Differential erosion, Basal melt
110
What type of landform is a truncated spur?
Erosional
111
What are the processes involved with the formation of a truncated spur?
Abrasion, Ice bulldozing, Plucking
112
What type of landform is a roche moutonnée?
Erosional
113
What are the processes involved with the formation of a roche moutonnée?
Abrasion (stoss), Plucking (lee), Pressure melting
114
What type of landform is a drumlin?
Depositional
115
What are the processes involved with the formation of a drumlin?
Lodgement, Reshaping by ice, Subglacial deformation, Basal melting
116
What type of landform is terminal moraine?
Depositional
117
What are the processes involved with the formation of terminal moraine?
Direct deposition (lodgement), Bulldozing
118
What type of landform is recessional moraine?
Depositional
119
What are the processes involved with the formation of recessional moraine?
Direct deposition (during stillstand)
120
What type of landform is lateral moraine?
Depositional
121
What are the processes involved with the formation of lateral moraine?
Deposition of weathered supraglacial material
122
What type of landform are erratics
Depostional
123
What are the processes involved with the formation of erratics
Deposition
124
What type of landform are eskers?
Glacio-fluvial
125
What are the processes involved with the formation of eskers?Meltwater deposition (fluvial sedimentation within ice-walled tunnel)
Meltwater deposition (fluvial sedimentation within ice-walled tunnel)
126
What type of landform are kames?
Glacio-fluvial
127
What are the processes involved with the formation of kames?
Meltwater deposition (from supraglacial streams)
128
What type of landform are outwash plains?
Glacio-fluvial
129
What are the processes involved with the formation of outwash plains?
Meltwater deposition (braided river system
130
How can you tell glacio-fluvial landforms from glacial ones?
Glacio-fluvial landforms are sorted and stratified due to meltwater deposition. Glacial landforms are unsorted and unstratified due to direct ice deposition.
131
How do geology and relief affect glacial landform development?
Harder rock resists erosion (e.g., forms roche moutonnées), softer rock erodes faster (e.g., ribbon lakes). Steep relief accelerates ice flow, increasing plucking and abrasion.
132
What are relict landforms and why are they important?
Landforms created by glaciers or permafrost that no longer exist under current climate. They show evidence of past climates, e.g. pingos in East Anglia, terminal moraines marking former glacier extent.give m
133
How are glacial erosional landforms linked in a landscape system?
Corries form in mountain hollows; erosion between them creates arêtes; 3+ corries eroding back-to-back form pyramidal peaks. Glaciers flowing from corries form U-shaped valleys, ribbon lakes, truncated spurs, and hanging valleys — a connected erosional system.
134
What is stratification in glacio-fluvial landforms and why is it important?
Stratification refers to the layering of sediment by particle size due to varying meltwater flow. It's evidence of water-deposited landforms and helps distinguish glacio-fluvial features from glacial ones
135
How does patterned ground provide evidence of periglacial processes?
Patterned ground (polygons, circles) is caused by frost heave and freeze-thaw action in permafrost zones. It shows active freeze-thaw cycling and ground ice movement.
136
What is the difference between subglacial and englacial deposition?
Subglacial: material deposited beneath the glacier (e.g. drumlins, ground moraine).
Englacial: debris transported within ice, often contributing to medial or lateral moraine after melting.
137
What is an ognip / pingo scar and what does it indicate?
An ognip is a collapsed pingo (pingo scar). Its presence in temperate areas like East Anglia indicates past periglacial conditions and long-term climate change.
138
How do moraines show evidence of glacier retreat?
- Terminal moraine shows maximum ice extent.
- Recessional moraines form during standstills, marking stages of retreat.
- Their sequence shows how glaciers responded to past climate changes.
139
Explain how a glacier can be viewed as a system.
- Open system with inputs, outputs, stores, and transfers
- Inputs: snow (precipitation), debris, solar energy
- Stores: ice, meltwater, debris
- Transfers: ice and debris movement downslope
- Outputs: meltwater, calving, sublimation, erosion
- Linked by mass balance and can reach dynamic equilibrium
140
Explain how glaciated landscapes can be viewed as systems.
- Open systems with inputs, processes, stores, and outputs
- Inputs: kinetic (wind, moving ice), thermal (sun), potential (gravity), snowfall, debris
- Processes: ice/debris movement, basal sliding
- Stores: ice, water, debris
- Outputs: meltwater, sublimation, evaporation, erosion
- Can be in equilibrium or dynamic equilibrium (via feedback)
141
What is a kame terrace?
A linear bench of sorted sediment deposited between the glacier and valley side by meltwater.
142
What is a delta kame?
A mound formed when meltwater streams deposit sediment at the edge of a proglacial lake.
143
How does glacier ice form?
Snow accumulates and compresses into firn (granular ice). Over years, compaction and pressure recrystallise firn into dense glacier ice, expelling air and forming stratified glacial layers.
144
What are striations and how do they form?
Striations are linear scratches or grooves in bedrock caused by debris embedded in the base of a glacier scraping over the surface during abrasion.
145
What is a till sheet?
A large, relatively flat expanse of unsorted glacial till, deposited when an ice sheet melts in place. Often found in lowland areas; less mounded than moraines.
146
What is till?
Unsorted, unstratified sediment deposited directly by glacier ice.
It includes clay, sand, gravel, and boulders, often angular due to plucking and freeze-thaw.
147
What is a key difference between landforms created by ice sheets and valley glaciers?
Ice sheets create broad depositional features like till plains and drumlins. Valley glaciers create more dramatic erosional landforms (e.g., corries, U-shaped valleys) due to confined flow and greater relief.
148
How can glacial landforms be modified after glaciation?
Freeze-thaw weathering, fluvial erosion, vegetation colonisation, and human activity (e.g., farming, urbanisation) can reshape glacial landforms like moraines and troughs after ice retreat.
149
How might future climate change impact periglacial landforms?
Warming may increase permafrost thaw, expand thermokarst, collapse pingos, and reduce patterned ground development, transforming periglacial landscapes into temperate ones.
150
What is the difference between warm-based and cold-based glaciers?
Warm-based glaciers experience basal melting and move by basal sliding. Cold-based glaciers remain frozen to the bedrock and move by internal deformation. Warm-based = more erosion and landform creation.
151
What’s the difference between ice-contact and proglacial fluvioglacial landforms?
Ice-contact (e.g. eskers, kames) form within or alongside the glacier. Proglacial (e.g. outwash plains) form beyond the glacier from meltwater streams.
152
How do short- and long-term climate changes affect glaciated landscapes?
Short-term (seasonal melt) alters meltwater and flow; long-term (warming/cooling trends) reshape landforms and cause glacier advance or retreat.
153
What are the major ice sheets and where are they located?
- Antarctic Ice Sheet – Present day; covers ~14 million km²
- Greenland Ice Sheet – Present day; covers ~1.7 million km²
= Laurentide Ice Sheet – Pleistocene; covered most of North America
154
What are ellipsoidal basins and how do they form?
Ellipsoidal basins are large, shallow, bowl-shaped depressions formed by the erosive action of continental ice sheets.
They result from:
- Abrasion and plucking over vast, low-gradient areas
- Over-deepening of weak or jointed bedrock
- Often enhanced by multiple glaciations
155
What is the case study corrie?
Cwm Idwal
156
What is the case study arete?
Crib Goch
157
What is the case study pyramidal peak?
Mount Snowdon
158
What is the case study U-shaped valley / glacial trough?
Nant Ffrancon
159
What is the case study lateral moraine?
Llyn Idwal
160
What does supraglacial mean?
Anything located on the surface of a glacier. The prefix "supra-" means "above" or "on top of," so "supraglacial" pertains to features or materials situated atop the glacier ice.
161
What is supraglacial load?
Debris and sediment that rest on the surface of a glacier.
This material typically originates from rockfalls, avalanches, or erosion of the valley walls adjacent to the glacier.
As the glacier moves and eventually melts, this debris is deposited, often forming features like lateral or medial moraines.
