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P1 - Glaciation Flashcards

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1
Q

Name 4 pro glacial landforms

A
  • pro-glacial lakes
  • kettleholes
  • sandurs (outwash plains)
  • Meltwater channels
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2
Q

Describe how a pro-glacial lake is formed

A
  • Formed along the front of glaciers and ice sheets where melt water from the glacier becomes impounded with a deposition blocked by glacier ice and bounded by high grounds
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3
Q

Describe how kettles are formed

A

During ice retreat, blocks of dead ice become detached. Sediment builds up around the dead ice and when they eventually melt, a small hollow is formed in which water accumulates to form a lake

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4
Q

Describe how a sandur (outwash plain) is formed

A

What is it?
- a flat expanse of sediment deposited in form of a glacier
How does it form?
-as the melt water streams gradually lose energy due to entering lowland areas, they deposit their material. The largest material is deposited nearest the snout and the finest further a way.

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5
Q

Describe how a melt water channel is formed

A

Melt water on the surface of the glacier melts its way through the glacier to the base through a ‘moulin’. Once the melt water comes out from the base of the glacier it forms a channel in front of to the glacier

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6
Q

Name three fluvioglacial landforms

A

Esker, Kame, Kame terrace

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7
Q

Describe how an esker is formed

A

Subglacial streams carry large amounts of rock debris due to their hydrostatic pressure inside the tunnels. The stream often meanders beneath the glacier, when the glacier retreats, the debris load is deposited at a consistent rate and forms a ridge.

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8
Q

Describe what an esker is

A

A long, narrow, sinuous (widening and meandering) ridge of sand and gravel

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9
Q

Describe how a Kame is formed

A

A meltwater stream emerges into an outwash plain or peri glacial lake at the glacier snout, their velocity falls and energy is lost causing sediment to be deposited.

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10
Q

Describe what a Kame is

A

An undulating mound of sand and gravel deposited on the valley floor

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11
Q

Describe how a Kame terrace is formed

A

During the summer, the valley sides radiate heat. This melts the edge of glacier forming a meltwater stream. This deposits sediment. When the glacier retreats, the sediment will fall to the valley floor, forming a Kame terrace.

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12
Q

Describe what a Kame terrace is

A

A flat, linear deposit of sand and gravel along the valley sides

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13
Q

Name 3 peri glacial landforms

A

Pingo (open and closed), patterned ground, ice wedges

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14
Q

Describe how a closed system pingo is formed

A

The lake insulates the talik preventing it running to permafrost. Water begins to drain from the lake reducing the amount of talik. Pressure from the advancing permafrost allows land (talik) to settle above.
Hydrostatic pressure causes the water to turn to ice. Hydrostatic pressure also pushes the land above causing the land to be disformed.

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15
Q

What is talik

A

Unfrozen ground in a periglacial area that surrounds the permafrost

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16
Q

Describe how ice wedges are formed

A

A thin piece of ice (around 3-4 metres in length) causes a crack in the rock. In the winter, ice freezes and expands. When the temperature rises, the ice melts. More water fills the crack and permafrost freezes it. This process repeats itself until a polygon of ice goes deep into the ground.

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17
Q

Describe what an ice wedge is

A

It is a wedge of ice extending 3-4 metres underground, usually in a polygon shape

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18
Q

Describe how patterned ground is formed

A

Ice wedges form underneath granite. As the ice wedges continue to expand (by 10%) the land above buckles and creates a trough with small mounds. Ice wedges melt causing land to fall in its place. This leaves new mounds in between where the ice wedges used to be.

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19
Q

Describe how an open system pingo is formed

A

Groundwater moves through the ground and eventually finds a weakness in the permafrost. Hydraulic pressure causes the water to rise up through the cracks. As the water gets closer to the surface, the temperature decreases turning into ice. Hydrostatic and hydraulic pressure causes the ice to continue moving upwards. This creates an open system pingo

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20
Q

Name 5 macro erosion landforms

A

U-shaped valley, hanging valley, ribbon lake, pyramidal peak, corrie/cirque

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21
Q

Describe how a ribbon lake is formed

A

Meltwater at the glacier base plays a role, and where PMP is exceeded, the glacier can basically slide encouraging even more erosion.
Differential erosion= some parts of the valley floor are over dependant creating ribbon lakes.

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22
Q

Describe how a corrie is formed

A

Snow accumulates in a hollow. Snow compacts making a neve/firn and glacial ice. Ice becomes too big for the hollow and moves down the slope. It will move in a rotational slip. The hollow deepens through invasion, abrasion and plucking. Freeze thaw shatters rocks above the hollow and delivers shattered rock (scree) to the ice - abrasion. Pressure melting point is often surpassed allowing melting to exist which allows basal slippage. This creates a steep back wall and a hollow known as a corrie.

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23
Q

Describe how a pyramidal peak is formed

A

If three or more corries development on all sides of a mountain a pyramidal peak is formed. The feature has steep sides and several arêtes radiating from the central peak.

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24
Q

Name an example of a pyramidal peak

A

The Matterhorn, Alps

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25
Describe how a U-shaped valley is formed?
As the glacier leaves the Corrie it moves down the old river valleys that are V-shaped. As the valley glacier moves down the valley, it plucks material from the valley sides and base. This allows abrasion to occur making the valley deeper and wider. Lateral and ground moraine abrade the valley sides and the floor further. The front of the glacier acts like a bulldozer and shifts and removes the plucked material turning the interlocking spurs into truncated spurs.
26
Describe how a hanging valley is formed
Hanging valleys are created due to different rates of erosion between the main valley and the tributary valleys that enter it along its sides. The floors of the tributary valleys are eroded and deepened by abrasion and plucking at a slower rate than the floor of the main valley, so the difference between the depths of the two valleys steadily increases over time. The tributaries are left high above the main valley, hanging on the edges. In the post glacial, rivers and streams return and enter the main valley by either a series of small waterfalls or a single impressive fall.
27
Name 3 messo erosional landforms
Roche mountonness, crag and tail, knock and lochan
28
Describe how a crag and tail is formed
The glacier erodes soft rock and then reaches a band of hard rock. Once the band of hard rock is reached, pressure builds and pmp is reached enabling the glacier to overcome the hard rock. This causes a rapid decrease in pressure and a fall below pmp. This causes a loss in energy, causing the glacier to drop sediment. This forms the tail of the crag and tail.
29
Describe how a Roche mountonness is formed
The glacier encountered the obstacle, pressure increases and allows melting to occur (PMP exceeded). This allows the ice to melt and basal slippage to occur, rocks trapped in this ice abrade the bedrock. This abrasion on the up-valley sides of the glacier can leave striations as pieces of rock debris with the ice were dragged across the surface under great pressure. Once the Lee side pressure fails and the water refreezes (regelation) and as the ice moved downhill it pulls away masses of rock; plucking the rocks underneath. This leaves a steeper sided, more jagged Lee slope.
30
Describe how a knock and lochan is formed
Alternating Roche mountonness and eroded hollows often containing small lakes
31
Give an example of a crag and tail
The royal mile, Edinburgh
32
Name two micro glacial erosion landforms
Crescentic gouges and striations
33
Describe how crescentic gouges are formed
Plucking
34
Describe how striations are formed
Caused by abrasion
35
Name 5 glacial depositional landforms
Lateral moraine, recessional moraine, terminal moraine, medial moraine and drumlins
36
Name the two theories of how drumlins are formed
Boulton Menzies, shaw theory
37
What are the 4 types of moraine?
Lateral moraine, recessional moraine, terminal moraine, medial moraine
38
Describe how lateral moraine is formed
Debris from freeze thaw weathering falls onto the glacier and then is transported and then deposited at the edge of the glacier when in melts
39
Describe how recessional moraine is formed
Debris is deposited during the interrupted retreat of the glacier, when the glacier is stationary long enough for there to be a build up of material
40
Describe how terminal moraine is formed
Debris is deposited at the maximum extent of the glacier, especially if the snout is stationary and the glacier is in the equilibrium. It will be continuously supplied in the same place.
41
Describe how medial moraine is formed
At the confluence of two tributary glaciers, the lateral moraines join together medial moraine, which is deposited during ice melt and retreat.
42
Describe the boulton menzies theory of drumlin formation
An obstacle gets in the way of the glacier and this leads to deposition on the Lee side. The obstacle is the core of the drumlin and the ground moraine is around it.
43
Describe the shaw theory of drumlin formation
Subglacial meltwater causes channels and bars to the channel which are shaped by the glacier (streamlined)
44
What are the three long term milankovitch cycles?
1. eccentricity 2. obliquity 3. precession
45
What is eccentricity?
How the earts orbit of the sun changes from circle to oval It changes every 96,000 years
46
What is obliquity?
The earths tilt It is currently at 23.5 degrees, but it varies between w21.5 degrees and 24.5 degrees with a period of about 41,000 years
46
What is precession?
A process that happens between 19,000 and 21,000 years
47
Positive feedback
Increasing the warming or cooling rates
48
Negative feedback
Decreasing the warming or cooling rates
49
Where was the Loch Lomond stadial?
Northern Scotland
50
What was the date of ice sheet retreat and rapid retreat?
Ice sheet retreat- 18,000 years ago Rapid retreat- 15,000 ago
51
What is the vegetation in Northern Scotland?
Deciduous woodland
52
What was the cause of the Loch Lomond stadial?
Drainage if the huge proglacial Lake Agassiz distrusted the THC and changed ocean currents
53
What were the long term effects of the Loch Lomond stadial?
It changed the landscape
54
What was the location of the little ice age?
Global
55
When was the little ice age?
1550 and 1750
56
What were the impacts of the little ice age?
Widespread abandonment of upland farms Arctic sea spread further south Curling developed as a national sport in Scotland
57
What dramatically halted the cold period of the little ice age?
Industrial Revolution
58
What do some researchers argue was the cause of the little ice age
A stadial period
59
What is the cryosphere?
The term given to the frozen water on the earths surface. It takes into account ice, glaciers, and ice caps
60
Ice sheet
Complete submergence of regional topography
61
Ice cap
Smaller version of ice sheet occupying upland areas
62
Ice field
Ice covering an upland area but not thick enough to bury topography, many do not extend beyond highland source
63
Valley glacier
Glacier confined between valley walls and terminating in a narrow tongue. Forms from ice caps/ sheets or cirques
64
Cirque glaciers
Smaller glacier occupying a hollow on the mountain side- carves out a corrie or cirque
65
Ice shelf
Large area of floating glacier ice extending from the coast where several glaciers have reached the sea
66
What are warm based glaciers?
Glaciers which occur in high altitude areas outside the polar region
67
What are cold based glacier?
Glaciers which occur in high latitudes
68
Basal slip
Meltwater reduces frictional stress by lubrication which allows the glacier to move
69
Internal deformation
Movement between or within individual grains of ice, including grains slipping over each other, melting and recrystallising
70
Regulation creep
Occurs when ice melts under pressure, usually because it encounters an obstacle. The meltwater flows around the obstacle and refreezes as the pressure drops
71
What are rifts?
A kind of ice fracture that penetrates the full thickness of a floating ice plate
72
What are basal crevasses?
Large scale structural weaknesses that can both control meltwater ponding and induce surface crevassing
73
What is icefall?
They form in steep sections of the glacier. As these falls, flow is extremely fast and the ice stretches and thind
74
What are En Échelon crevasses?
A series of marginal crevasses that occur as a result of rotational strain in the ice at an angle to the glacier margin Nearly equal sizes and grouped in rows
75
What are bergschrund’s?
The crevasses occurring at the head if a mountain glacier, which separates the moving snow and ice if the glacier from the relatively immobile snow and ice adhering to the head wall of the valley
76
What are splaying crevasses?
They appear along the edges of a glacier and result from shear stress from the margin of the glacier and longitudinal compressing stress from lateral extension
77
What are transverse crevasses?
They form in a zone of longitudinal extension where the principle stresses are parallel to the distinction of the glacier flow, creating extents a, tensile stress
78
Compress flow
Occurs where there is a reduction in the gradient of the valley floor leading to ice deceleration and a thickening of the ice mass
79
Extending flow
Occurs when the valley gradient becomes steeper. The ice accelerates and becomes thinner, leading to reduced erosion
80
Internal flow
This occurs when ice crystals orientate themselves in the direction of the glaciers movement and slide past each other. As the surface moves faster, crevasses develop
81
Frost heave
Groundwater freezes and expands. This moves the glacier up and disrupts the soil
82
Nivation
Freeze thaw but with meltwater
83
Scree
Freeze thaw happens at the top and the rock falls onto the glacier
84
Plucking
Two stage process: 1. Initial widening of joints by fracture 2. Subsequent entrainment of loosened material
85
Abrasion
Rock floor polishes rocks by ‘sand paper’ action
86
How can the shape of debris cause more or less erosion?
Angular debris will cause the glacier to erode more because the rocks are sharp and uneven
87
How can the amount of debris cause more or less erosion?
If there is more debris it will increase the rates of abrasion and plucking
88
How can the thickness of glacial ice cause more or less erosion?
Thicker ice will cause more fracture and traction as the ice weighs more
89
How can the speed of ice movement abuse more or less erosion?
Can be determined by the angle of the slope. Abrasion is greater at the base of fast flowing glaciers
90
How can bedrock characteristics cause more or less erosion?
Gradient of bedrock can influence compressional and extensional flow. The bedrock characteristics also determine how susceptible to erosion it is
91
How can the type of glacier cause more or less erosion?
Warm based glaciers have more meltwater so will have more erosion as it helps the ice movement
92
Periglacial
Has traditionally. Been used to refer to the climate co dictions and landscapes that are near margins of glacial ice cause
93
Continuous permafrost
Found at the coldest regions where there is little thawing even in the summer
94
Discontinuous permafrost
Found in slightly warmer regions where freezing conditions do not penetrate at such great depths. There are breaks in the permafrost under lakes, rivers and the sea
95
Sporadic permafrost
Mean annual temps are around or just below freezing point and permafrost occurs only in isolated spots
96
Talik
Unfrozen soil surrounding the permafrost. Does not include the active layer
97
Soil creep
The slow downslope movement of soil and sediment because of frost heaving and thawing
98
Solifluction
In winter, water freezes in the soil causing expansion of the soil and segregation of individual soil particles As it moves over the permafrost it carries segregated soil particles and deposits them further downslope as a solifluction lobe or terracette
99
Nivation hollows
Snow falls and is protected in hollows The snow is slowly compacted by further snow and melts into névé and then into firn Weathering can weaken the soil and rocks underneath the snow and create a slope failure at the back of the snow patch Erosion from meltwater can wash sediments out of the base of the snow patch The weathered particles are moved downslope Nivation hollows can develop into corrie glaciers
100
Wind erosion
Strong winds can move large quantities of loose sediment and soil which will help wind erosion
101
Cirque orientation
The direction that the corrie (cirque) is facing. This is important because it will have determined that direction if ice flow during the last glacial or stadial period
102
What is the drumlin elongation ratio equation?
Drumlin elongation ratio = maximum length / maximum width
103
Wilderness
A natural environment that is remote, has a thrash physical environment and has little to no pop
104
When was the Antarctic treaty signed?
1959
105
According to the Antarctic Treaty, what can the continent be used for?
Peace and science
106
How many countries and how many researchers are there in the Antarctic Treaty?
Countries- 60 Researchers- 10,000
107
How much did the Antarctic Treaty cost?
$1.5Bn
108
What is the percentage of ice cover in Greenland?
80%
109
What is the percentage of global ice mass in Greenland?
10%
110
What is the depth of the permafrost I the Yamal Peninsula in Russia?
300m
111
CASE STUDY: Greenland What is the name of the native people?
Inuits
112
CASE STUDY: Greenland How are endemic species, wilderness recreation, and scientific research values to Greenland?
The land and waters support fragile biodiversity if endemic plants, large mammals, and a diverse range of fish and birds The ecosystems offer scientific research and wilderness recreation
113
CASE STUDY: Greenland How is the global water cycle important for Greenland?
The ice sheet contains approx. 10% of the total global ice mass
114
CASE STUDY: Greenland How is hunting important for Greenland?
Greenlandic Inuits now live in towns with modern homes however still maintain their traditional lifestyle Pressure from environmental groups have led to restrictions for most species
115
CASE STUDY: Greenland How is HEP important for Greenland?
Has the world biggest unexploited hydropower capacity
116
CASE STUDY: Greenland How are minerals and metals important for Greenland?
As the ice sheet retreats it reveals highly valuable deposits of oil, gas, metals and minerals
117
CASE STUDY: The Yamal Peninsula, Russia How is the biodiversity of the tundra important for The Yamal Peninsula?
Provides a summer home for many migratory species and plays a role in worldwide food webs
118
CASE STUDY: The Yamal Peninsula, Russia How is the permafrost important for The Yamal Peninsula?
Large scale carbon sink, storing an immense amount of carbon and methane In the warming climate, permafrost is expected to melt
119
CASE STUDY: The Yamal Peninsula, Russia How is the Nenets sustainable living important for The Yamal Peninsula?
Their understanding harsh climate and fragile ecosystem has enables them to live sustainably in thus inhospitable land
120
CASE STUDY: The Yamal Peninsula, Russia What is the name of the native people from The Yamal Peninsula
Nenets
121
CASE STUDY: The Yamal Peninsula, Russia How is reindeer herding important for The Yama Peninsula?
Economy driven by the reindeer meat they sell Reindeer herding supports more than 10,000 nomads who herd over 300,000 domesticated reindeer
122
CASE STUDY: The Yamal Peninsula, Russia How are gas reserves important for The Yamal Peninsula?
Contains the biggest gas reserves on the planet, holding almost 1/4 of the worlds known gas reserves
123
What are slab avalanches cause by?
Heavy snowfall overloading reduces cohesion between particles Deforestation makes the slope less stable Steep slopes increase the speed of movement The wind direction can pile snow which can overhang a mountain
124
What are glacial lake outburst floods?
They occurs them the dame ( ice/moraine dammed) containing a glacial lake fails
125
How is climate change a human threat to Greenland?
It can cause sea ice retreat, and the exposure of land containing valuable resources = as sea ice retreats, new commercial fishing routes are created in the Arctic. Could increase marine pollution and cause overfishing = causes stress on the environment
126
How is uranium mining a human threat in Greenland?
In 2014 the gov. reserved a ban on radioactive uranium mining = areas in the south. Outfits be opened up got large scale mining projects = radioactive waste could affect fisheries and farming in the region. These are important to local communities = conservationists fear this could lead to irreversible damage to the environment
127
How are cruises a human threat in Greenland?
Cruises in 2003-15 ships, cruises in 2008-38 ships = Belfast water is discharged into the Arctic Ocean = may displace resident species = can introduce non-native species
128
How are political disputes a human threat in Greenland?
Russia staked claim over a section of the Arctic seabed = explorers put a metal flag in the seabed near the North Pole = in response Canada and Denmark have also staked a claim of other sections
129
Relict landscape
One that was once covered in glaciers and ice, but since disappeared. What remains are landscapes which huge environmental, cultural and economic value
130
Active landscape
A periglacial environment that is affected by snow and frost action currently
131
CASE STUDY: Lake District Is the Lake District a relict or active landscape?
Relict
132
CASE STUDY: Lake District What is the value of the Lake District?
Over 16 million tourists visit every year and provide over 16,000 jobs Tourism is worth over £1.1Bn to the local economy Local services such as roads are improved for tourism which benefits the locals
133
CASE STUDY: Lake District What are the threats to the environment?
Additional tourist traffic causes congestion Footpath erosion which can destroy vegetation and compact soil Rubbish discarded by tourists Increase of non-native species which push out the native species Greater risk of extreme weather events Migration of certain habitats upwards due to warming
134
CASE STUDY: Lake District Who are the key players in management?
LDNPA (Lake District National Park Authority) work to repair footpaths and manage the area
135
Basal melting
On warm based glaciers when base temp is at PMP a sped can create sub-glacial tunnels by eroding bedrock and emerge at the snout in caves
136
Glacial period
A cooler interval of time during thousands of years off an ice age, when a glacier advances
137
Interglacial period
A warmer interval of time during the long span of an ice age, when a glacier retreats
138
Stadial period
Cooler periods of time within an interglacial period
139
Interstadial period
Warmer periods of time within a glacial period
140
Albedo effect
Sun reflecting off white ice

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