Glaciation Flashcards
(214 cards)
1
Q
In the northern hemisphere, in what compass direction do glaciers form and why?
A
N/NE facing slopes
More sheltered from solar radiation
2
Q
What is the density of snow fall?
A
90% air, so 0.1g/cm3
3
Q
What is the density of Firn/Neve?
A
50% air, so 0.5g/cm3
4
Q
What is the density of glacial ice?
A
10% air, so 0.9g/cm3
5
Q
What is a cirque?
A
- Found in high altitude glaciers
- Armchair/amphitheater shaped hollow
- Constrained by the shaped bedrock hollows
6
Q
An example of a cirque
A
Cirque du Maudit on Mont Blanc
7
Q
Synonym for Neve
A
Firn
8
Q
Synonyms for cirque
A
Cwm
Corrie
9
Q
Synonyms for high altitude glacier
A
Alpine
Temperate
10
Q
What is a valley glacier?
A
- Found in high altitude glaciers
- River of ice tens of thousands of kms
- Constrained by steep valley sides
- Can also be a tributary glacier
11
Q
An example of a valley glacier
A
Mer de Glacé
12
Q
What is a piedmont glacier?
A
- Found in high altitude glaciers
- A valley glacier reaches a flat plane, it forms a fan shaped lobe tens of kms wide
- Unconstrained
13
Q
An example of a piedmont glacier
A
Skaftarjokull
14
Q
What is a highland ice field?
A
- Found at high altitude glaciers
- Similar in size to an ice cap but not as thick and they do not have a dome like surface
- Constrained by underlying topography
15
Q
Examples of highland ice fields
A
Vallée Blanché
Eyjafjallajökull
16
Q
Synonym for high latitude glaciers
A
Polar glaciers
17
Q
What is an ice cap?
A
- Found at high latitude glaciers
- It submerges an entire landscape under ice
- Unconstrained
18
Q
Examples of ice caps
A
Langjokull
Vatnajokull
19
Q
What is an ice sheet?
A
- Found at high latitude glaciers
- Larger than 50,000km2
- Similar to ice caps, but submerge entire landscape under ice dome
- Unconstrained
20
Q
Examples of ice sheets
A
Antarctica
Greenland
21
Q
Variations in solar output
A
- Total amount of energy received by the earth from the sun varies by 0.1%
- Sunspots create an increase in the solar constant and warmer temperatures
22
Q
What is the cryosphere?
A
- Refers to the cold environments of our planet
- Where water is in its solid form of ice
- Includes snow cover, river and lake ice, sea and ice shelves and periglacial features
23
Q
What is a periglacial environment?
A
- A non-glacial environment
- Often on the edge of glacial environments where there is permafrost
- Part of the cryosphere
24
Q
What is a glacial environment?
A
- A large, slow moving body of ice that flows downhill due to gravity
- Includes high latitude and high altitude glaciers
25
What is a polar glacial environment like?
* Very cold
| * Low levels of precipitation
26
What is an alpine glacial environment like?
* Wise temperature range
* High levels of precipitation
* Rapid flowing glaciers
27
What is a relic Pleistocene landscape?
Not currently covered in ice, but features fossilised glacial landforms did to past glaciations
28
What is Loch Lomond Stadial/Younger Dryas event?
* Rapid de-glaciation which began 18,000 yrs BP until by 15,000 yrs BP, temperatures were similar to today
* Between 12,500-11,500 yrs BP, there was a sudden cooling with temperatures dropping 6-7’C
* Glaciers, permafrost and tundra formed in the UK
29
What caused the Younger Dryas event?
* Disruption to the Thermohaline circulation
* Meteorite impact in N.America
* Volcanic eruption in Germany
30
Disruption to the thermohaline circulation (theory)
* Thermohaline circulation: warm ocean currents at surface, moisture evaporates, salt in sea doesn’t evaporate, dense cool water sinks at 5B gallons/sec and the current pulls the water down
* Glacial Lake Agassiz formed due to melting ice, water entered the Gulf Stream and shut it off and Europe re-enters an ice age
31
Meteorite impact (theory)
* 60 ice age animals suddenly became extinct
| * Possible airborne meteorite explosion
32
Laacher See volcanic eruption (theory)
* 12,900 yrs BP
* VEI 6
* 2km wide caldera volcanic lake
* Release of ask blocked out solar radiation causing global cooling
33
What was the medieval warm period?
800-1300 AD
| The Vikings colonised Iceland and Greenland -5000 ppl
34
What was the little ice age?
* 1350-1850
* 1-1.5’C lower than today
* Communications between Iceland and Greenland ceased due to icy seas
35
What was the mystery of the Greenland Vikings?
* A ship from Iceland was blown off course, reaching Iceland in 1410
* A ship reaches Greenland and finds the frozen corpse of a man an no survivors in 1540
36
Why does Antarctica remain cold?
* It was severed from South America, creating the Drake passage
* It became completely surrounded by ocean
* Antarctic Circumpolar current began to flow round the continent, isolating Antarctica from the warmth of global oceans
37
What is the albedo effect?
The ability of a surface to reflect solar radiation
38
The closure of the Panama Isthmus
* Prevented warm ocean currents flowing west
| * More snow created in Northern regions as moist air mixes with cold air - produces white surface for Albedo effect
39
What is the environmental lapse rate?
E.L.R
| For every 100m, you lose 0.6’C
40
Mountain building
Air currents are forced to rise up when they hit mountains and the relief rainfall becomes snow as altitude increases.
41
What is a glacial period?
A cold period that lasts about 100,000 yrs
42
What is an interglacial period?
A warm period that lasts about 10,000 - 20,000 yrs
43
Reasons for the fluctuations between glacial and interglacial periods
Milankovitch cycles
44
What is a Milankovitch cycle?
Tiny changes in the earths orbit around the sun responsible for glacial and interglacial periods
45
Eccentricity (Milankovitch cycle)
* An elliptical or increases seasonality(cold winters and not summers), causes snow to melt in summer - less Albedo effect, causing interglacial conditions
* A circular orbit has the opposite effect, causing glacial conditions
46
Obliquity (Milankovitch cycle)
* Measure of the tilt of the earths axis
* Minimum tilt - 22.1 degrees, polar areas receive less sunlight in summer - expansion of ice, causing glacial conditions
* Maximum tilt - 24.5 degrees, has the opposite effect
47
Precession/the wobble (Milankovitch cycle)
* Occurs on a 21,000 yr cycle
* Winters milder, summers cooler - reduces seasonality, making glacial conditions more likely
* 10,000 yrs BP - earth closest to the sun during N.H summer - increases seasonality, making interglacial conditions
48
What is a greenhouse earth?
No continental ice sheets on earth due to warmer temperatures resulting from higher concentrations of greenhouse gases
49
What is an ice house earth?
Ice sheets cover a large proportion of the land due to overall temperatures of Earth being lower than average.
There are at 5 known ice house earth periods.
Fluctuates between glacial and interglacial.
50
What is the quaternary ice age?
Divided into two epochs:
•Pleistocene - 2.6M yrs BP -> 10,000 yrs BP
•Holocene - 10,000 yrs BP -> present day
51
What’s odd about the last 2.6 million years?
Much colder than normal on earth
52
Why is the world so cold now?
Continental drift.
| Land mass on south pike rather than sea - land cools quicker than water, allowing ice to form on Antarctica.
53
What is climactic feedback?
* Either amplify a small change and make it larger - positive feedback
* Or diminish the change and make it smaller - negative feedback
54
What was the Devensian Period?
* Last glacial period to occur
* 110,000 yrs BP - 10,000 yrs BP
* Maximum glacial advance was about 18,000 yrs BP
55
What’s the thermohaline circulation?
A global system of surface and deep water ocean currents driven by differences in temperature and salinity between areas of the oceans.
56
What is glacial mass balance?
The difference between total accumulation and total ablation for the whole glacier over a year.
57
What is an ice wedge? (Periglacial feature)
* Dominant feature of periglacial environments.
* Irregular polygons on valley floors
* Shark tooth shaped wedge of ice tapering into the permafrost
* Patterned ground
58
How is an ice wedge formed? (Importance of ground ice)
When the active layer thaws, water flows into cracks which subsequently freeze and contract, allowing the wedge of ice to build up in width over time.
59
What is an open system pingo? (Periglacial feature)
* An ice core mound between 100-500m in diameter
| * Conical or elongated
60
How is an open system pingo formed? (Importance of ground ice)
* Found in discontinuous permafrost where groundwater is freely available
* Surface water trapped in upper layers freezes and expands, forming a dome
* Water is drawn to the expanding ice core forming below the ground surface.
61
What is a closed system pingo? (Periglacial feature)
* Ice vote mounds between 100-500m in diameter
| * Conical or elongated
62
How is a closed system pingo formed? (Importance of ground ice)
* Found in continuous permafrost
* Form when a small lake drains an no longer offers insulation from permafrost, making it freeze and expand
* This forms a dome shape, pushing up the earth around it
63
What are stone polygons/stone stripes? (Periglacial features)
* Polygonal and stripe shaped ridges of stones
| * Patterned ground
64
How are stone polygons/stone stripes formed? (Importance of ground ice)
* Frost heave brings rocks to the surface
* The doming of the circle by heave means the larger stones roll outwards
* On gradients, stripes are formed
65
What is a tor? (Periglacial feature)
A jumbled mass of exposed bedrock rising abruptly from a hilltop
66
How is a tor formed? (Importance of freeze thaw)
* Resistant rock has managed to resist freeze thaw
* Formed by pressure-release and/or the removal of the active layer by solifluction
* Then attacked by freeze thaw
67
What is a blockfield? (Periglacial feature)
Where the surface of the ground is covered in large angular boulders
68
How is a blockfield formed? (Importance of freeze thaw)
Accumulations of frost shattered rock accumulate on plateaus due to in situ freeze thaw weathering
69
What is a nivation hollow? (Periglacial feature)
Enlarged hollows often on the N side of a hillside containing a snow patch
70
How is a nivation hollow formed? (Importance of freeze thaw)
* Freeze thaw weathering disintegrates the rock below the snow patch
* The broken material is washed out by meltwater from the snow patch
71
What is a scree slope/talus? (Periglacial feature)
A slope of accumulated, angular rock fragments at the foot of a slope
72
How is a scree slope/talus formed? (Importance of freeze thaw)
* Freeze thaw weathering of a cliff face
| * The loosened material then falls to the base of the cliff
73
What is a solifluction lobe? (Periglacial feature)
A lobe or terrace of head deposits at the base of a slope
74
How is a solifluction lobe formed? (Importance of mass movement)
During the summer melt, the active layer becomes saturated over an impermeable layer of permafrost, causing mass movement of deposits into a lobe shape
75
What is frost creep? (Periglacial feature)
Where material moves down slope by a few cm per year
76
How does frost creep occur? (Importance of mass movement )
* Very slow form of mass movement
| * Ice needles lift soil particles to 90’ to the surface, then particles are let down slowly vertically
77
What is a Loess plain? (Periglacial feature)
Layers of wind blown deposits of fine grained silt or clay
78
How is a loess plain formed? (Importance of wind/meltwater)
Created by wind erosion over a vast open tundra
79
What are braided streams? (Periglacial feature)
A river with multiple intertwining channels and sometimes vegetated islands of sand/gravel banks between the channels
80
How are braided streams formed? (Importance of wind/meltwater)
* Water erosion is highly seasonal, occurring mainly in spring/summer
* Due to the large volumes of load the meltwater carries, the drainage pattern becomes braided
81
Why is winter always a period of positive balance? (Glacial mass balance)
The temperatures are cold, snow falls, accumulation
82
Why is summer always a period of negative balance? (Glacial mass balance)
Warm temperatures,snow and ice melts, rainfall, ablation
83
Information about Jostedalsbreen ice cap, Norway🇳🇴(Briksdalsbreen glacier case study)
* Largest glacier in mainland Europe
* 487km2
* Over 80km long
* Remnant of Scandinavian ice sheet
84
What is the Briksdalsbreen/Briks Dale glacier?🇳🇴(case study)
* A temperate glacier
* Outlet valley glacier from Jostedalsbreen Ice Cap
* Ranges in altitude from 1910m to 350m
85
What happened to the snout of the Briks Dale glacier in 1950?🇳🇴
Dramatic decrease - almost 40m
86
What happened to the snout of the Briks Dale Glacier in 1993?🇳🇴
It advanced by 80m
87
For how many of the 51 years from 1950 to 2001 did the Briks Dale Glacier have a negative mass balance and for how many did it have a positive mass balance?🇳🇴
Negative - 22 years
| Positive - 29 years
88
In 15 exceptional years, the glacier advanced or retreated by more than 20m. How many of these periods were of positive mass balance?🇳🇴
13 years
89
What is the main trend over the last 50 years?🇳🇴
The glacier is increasing in size
90
In 1996, how much longer was the glacier compared to its 1950 length?🇳🇴
525m longer
91
Why is the glacier constantly changing?🇳🇴
It’s affected by its environment
92
What is talik?
* Was once permafrost, now unfrozen
| * Kept above 0’C due to geothermal heat or insulation from a body of water
93
What is permafrost?
* Permanently frozen ground
* Soil temperatures remain below 0’C for at least 2 consecutive yrs
* Covers approx 25% of earths land surface
94
What is the difference between open, through and closed talik?
Open - open at the top
Closed - isolated
Through - all the way to the bedrock
95
What is the active layer?
* Up to 5m deep - gets deeper with a reduction of latitude
* Seasonal melting often saturates it because meltwater cannot infiltrate frozen ground below - unlikely to evaporate in large quantities due to low temperatures
96
Solifluction (Periglacial process)
* Form of mass movement
* Waterlogged sediment moves slowly downslope over impermeable material
* Occurs where melting during the warm season leads to saturation of the active layer
97
Frost heave (Periglacial process)
* Due to thermal conductivity of stone, they cool quicker than the soil in which they rest
* Water in the active layer freezes beneath the stone, forming an ice lens
* Water is attracted to the ice lens which continues to grow, forcing the active layer to buckle and the stone is pushed vertically
* Subsequent freezing forces the stone up further until it breaks the surface
* The stone is prevented from falling back down in summer due to infil by sediments - the stone rolls to the outer edges of the hump
98
Frost creep (Periglacial process)
* Water freezers and expands by 9%
| * Soil to heave at 90% to the plane when it melts, the soil grains drop directly vertically
99
Ground contraction (Periglacial process)
* Refreezing of active layer during winter causes the soil to contract
* Cracks open up
* During the following summer, these cracks full with meltwater and wind blown deposits
* The following winter, the crack refreezes and widens further
* This process is repeated
100
Freeze thaw weathering (Periglacial process)
* Water enters and expands by 9% as it freezes, forcing the joints apart
* More water is able to enter
* Repeats until the rock fractures open
101
What are the 2 theories on how tors are formed?
* Pressure release - after deglaciation, the lack of mass over the rocks means that joints open up, allowing meltwater in and freeze thaw occurs
* Palmer theory - solifluction washes away the active layer, exposing the rock to freeze thaw
102
How is a protalus rampart formed? (Periglacial feature)
* If there is a snow patch at the foot of the cliff, the rocks and boulders will slide along the snow to the foot of the snow
* When the snow melts, this leaves a rampart of boulders at a distance from the cliff
103
Nivation (Periglacial process)
* Type of erosion that comes from isolated patches of snow that remains through the summer
* Freeze thaw disintegrates rocks under the snow patch
* During the melt, the meltwater washes away the weathered material
* Forms a nivation hollow
104
What is warm ice?
Release meltwater during summer months which helps the glacier move
105
Why does a cold based glaciers surface travel faster than the base?
Lacks lubrication at its base, so base is frozen to bedrock
106
Why does a warm based glaciers base move faster than a cold based glaciers base?
Because the meltwater created by friction acts as a lubricant
107
Why is a tongue shape made in a valley glacier?
Friction from the valley sides slows down the glacier at the edge
108
What are the inputs of a glacier system? (Glacial mass balance)
* Snowfall
* Avalanches
* Wind blown snow
109
What are the processes in a glacier system? (Glacial mass balance)
* Erosion
* Transportation
* Deposition
110
What are the outputs in a glacier system? (Glacial mass balance)
* Melt
* Iceberg calving
* Sublimation
111
Why are glacier systems in a state of dynamic equilibrium? (Glacial mass balance)
It is constantly trying to rebalance itself as the climate changes either by advancing or retreating until a new state of zero mass balance is achieved
112
What is intragranular slip? (Glacier movement)
* Main mechanism behind ice creep
| * When individual ice crystals deform due to shear stress
113
What is regelation slip? (Glacier movement)
* Constant changes in pressure affecting the movement of the glacier
* High pressure - melting
* Low pressure - refreezing
114
Information about the Hubbard Glacier, Alaska🇺🇸(surging glaciers case study)
* 150km long
* Advanced by 10m/day
* Ice blocked mouth of Russel Fiord - May 1986
* Created a lake 50km long out of the Fiord
* Many marine mammals became trapped
* Lake levels rose by 25m, driving birds forms their nests and destroying eggs
* Town of Yakutat and the airport were threatened
* Lake broke through the ice dam - Oct 1986
* Occurred again in 2002
115
What is abrasion?
Where individual clasts wear away rock. Rock flour also polishes the underlying rocks by sand paper action
116
What is plucking?
Plucking occurs when rocks and stones become frozen to the base or sides of the glacier and are plucked from the ground or rock face as the glacier moves. It leaves behind a jagged landscape.
117
What is entrainment?
The incorporation of debris onto or into the glacier from supraglacial or subglacial sources
118
What are the three ways debris can be carried by a glacier?
* Supraglacially - on the ice
* Englacially - in the ice
* Subglacially - below the ice
119
What factors influence the landscape?
* Erosion (rate affected by mass)
* Deposition
* Weathering
* Differential geology
120
What is a cirque (macro erosional feature)
An amphitheater shaped depression in the mountain side with a steep back wall and a rock lip
121
How is a cirque formed? (Macro erosional feature)
Freeze thaw weathering, pressure release weathering, abrasion, plucking and rotational ice movement
122
What is an arête? (Macro erosional feature)
Narrow knife edged ridge
123
How is an arête formed? (Macro erosional feature)
Two cirques cut back towards each other
124
What is a pyramidal peak (Macro erosional feature)
Pointed peak with radiating arêtes
125
How is a pyramidal peak formed? (Macro erosional feature)
Three or more cirques cut backwards
126
What is a glacial trough? (Macro erosional feature)
Steep sided valley with a wide, flat floor and a misfit stream
127
How is a glacial trough formed? (Macro erosional feature)
Widened, deepened and straightened by a valley glacier
128
What is a hanging valley? (Macro/meso erosional feature)
Tributary valley left high above the main valley
129
How is a hanging valley formed? (Macro/meso erosional feature)
Ice in the main valley eroded more rapidly than ice in the tributary valley, often producing a waterfall
130
What is a truncated spur? (Macro erosional feature)
Steep cliff-like valley sides
131
How is a truncated spur formed? (Macro erosional feature)
Valley glaciers have removed the ends of interlocking spurs by abrasion
132
What is a ribbon lake? (Macro erosional feature)
Long narrow lake in a glacial trough
133
How is a ribbon lake formed? (Macro erosional feature)
A valley glacier over deepens more easily eroded parts of the valley floor
134
What is a roche moutonnee? (Meso erosional feature)
Ice smoothed rocks with a steeper side facing down valley
135
How is a roche moutonnee formed? (Meso erosional feature)
Resistant bedrock remains after ice abrasion on the ice direction facing stoss side and plucking on the lee
136
What are striations? (Micro erosional feature)
Rocks scarred with thin parallel scratches
137
How are striations formed? (Micro erosional feature)
Abrasion from subglacial rock debris in the ice dragged along the bedrock (debris has been plucked)
138
What is a knock and lochan? (Macro erosional feature)
Chaotic combination of rounded hills and eroded hollows
139
How is a knock and lochan formed? (Macro erosional feature)
Ice moving over soft, heavily jointed and resistant rocks which are abraded and plucked, forming a chaotic landscape
140
What is a crag and tail (Macro erosional feature)
Resistant rock outcrop isolated from higher ground
141
How is a crag and tail formed? (Macro erosional feature)
Glacier erodes surrounding softer material, leaving the resistant outcrop protruding from surrounding terrain, frequently serving as a shelter to softer material in the lee
142
What are chatter marks? (Micro erosional feature)
Irregular crescent shaped gouges on bedrock
143
How are chatter marks formed? (Micro erosional feature)
Pressure and impact of boulder moved along subglacially in a vibratory or irregular rolling or sliding
144
What are the stoss and lee?
Stoss - up ice
| Lee - down ice
145
What is a Fjord?
* Caused by flooding of a glacial valley with sea water
* Formed when a glacier cuts a U-shaped valley by the abrasion of the bedrock
* Glacial melting is accompanied by rebound of earths crust as the ice load and eroded sediment is removed
146
What is areal scouring?
* Large scale scraping of the landscape as the glacier enters lowland areas
* Glacier is no longer constrained by the valley, so the features created cover large tracts of land
147
What is a drumlin? (Ice contact/till feature)
An elongated hill composed of glacial deposits.
| Stoss end is steep and used to face me to the ice flow, gentle lee
148
How is a drumlin formed? (Ice contact/till feature)
* When the competence of the glacier is reduced, material is deposited
* A drumlin will continue to form because of the way it modifies the flow of ice over and around it
* Deposited by lodgement - when the friction between the particle embedded (subglacial)in the base of the glacier and the glacial bed exceeds the drag imposed by the overlying ice so the clast stops moving
149
What are till plains? (Ice contact/till feature)
* A large relatively flat plain
* Given enough subglacial debris beneath the glacier, low areas within the landscape can be completely filled in by lodgement till
* Changes undulating landscape into a broad, flat expanse
150
What are the different types of moraine? (Ice contact/till feature)
* Lateral
* Medial
* Push
* Terminal
* Recessional
* Erratic boulders
151
What is moraine? (Ice contact/till feature)
Any glacially formed accumulation of unconsolidated(mixed) glacial debris
152
What is lateral moraine? (Ice contact/till feature)
* Parallel ridges of debris deposited along the sides of a glacier
* Can be deposited on top of the glacier by frost shattering of the valley walls and from tributary streams flowing into the valley
153
What is medial moraine?(Ice contact/till feature)
* A ridge of moraine that runs down the centre of a valley floor
* Formed when two glaciers meet and the debris on the edges of the adjacent valley sides join and are carried on top of the enlarged glacier
154
What is terminal moraine? (Ice contact/till feature)
* Forms at the snout of the glacier - marks the max advance of the glacier
* Debris that has been accumulated by plucking and abrasion, that has been pushed by the front edge of the ice is dumped in a heap
* Size is proportional to the time the glaciers snout is stationary
155
What is recessional moraine? (Ice contact/till feature)
* Form at the end of the glacier, so they are found across the valley, not along it
* They form where a retreating glacier remained stationary for long enough to produce a mound of material
156
What is push moraine? (Ice contact/till feature)
•Material that had already been deposited is pushed into a pile as the ice advances
157
What are erratic boulders? (Ice contact/till feature)
* A piece of rock that differs from the size and type of rocks native to the area
* Carried by glacial ice - can be transported by ice rafting
158
What are the characteristics of till?
* Angular/sub-angular
* Clay matrix
* Aligned in direction of ice flow
* No imbrication
* Unstratified
* Poorly sorted
* Could contain erratics
159
What are the characteristics of fluvio-glacial deposits/outwash?
* Rounded/sub-rounded
* Clast support
* Align in in direction of river flow
* Imbricated
* Stratification & grading
* Well sorted
* Could contain erratics
160
What is an esker? (Fluvio-glacial)
* Ridges of stratified coarse sand and gravel deposition
| * Most common in glaciated lowlands
161
How is an esker formed? (Fluvio-glacial)
* Created by meltwater that flowed through channels subglacially and englacially due to high pressure in channels/tunnels
* When glacier retreats, debris is deposited to form a ridge
162
What are kames? (Fluvio-glacial)
* Deposits that have mainly come from supraglacial meltwater deposition
* Made from sand and gravel
* Tend to be concentrated near glacial snout
163
How are kames formed? (Fluvio-glacial)
As stagnant (melting) ice melts away, the deposit is lowered down to the valley floor, forming a mound which is typically steep-sided and conical. Often disturbs stratification
164
What is a kame terrace? (Fluvio-glacial)
* Look like long flat benches with a lot of pits on the surface made by kettles
* Tend to slope down valley
165
How is a kame terrace formed? (Fluvio-glacial)
* Form when sediment accumulates between a glacier and the valley sides
* As the valley walls warm up, the warm rock helps to melt the ice near to it - forms a long depression or trough along which meltwater flows
* When the glacier retreats, sediment falls to valley floor
166
How to distinguish between lateral moraine and kame terraces
* Kame terraces - deposits become sorted - outwash
| * Lateral moraine - deposits exhibit no sorting
167
How is a proglacial lake formed? (Fluvio glacial)
A lake formed by the damming action of a moraine or ice dam during the retreat of a melting glacier, or by meltwater trapped against an ice sheet - e.g. lake Missoula
168
How is a kettle hole formed?(Fluvio-glacial)
* Formed by blocks of ice that are separated from the main glacier by either glacial retreat or by calving off the glacier snout and falling forwards
* If conditions are right, the blocks of ice become partially buried in meltwater sediment
* When the ice blocks melts they leave behind depressions
* Kettle holes filled with water become kettle hole lakes
169
What is outwash plain/sandur? (Fluvio-glacial)
A flat expanse of fluvio glacial sand and gravel
170
How is an outwash plain/sandur formed? (Fluvio-glacial)
•Meltwater carries sediment away from the glacier and deposits it on a broad plain as it loses velocity - size sorted by water
171
What is a varve deposit? (Fluvio-glacial)
* Annual layer of sediment
* Form distinct layers of sand and clay - form in lakes near to glacial margins
* During the peak meltwater in spring and summer, a light coloured sandy layer is deposited - meltwater at leak discharge - able to carry max load
172
How are till plains formed? (Ice contact)
When a sheet of ice retreats, large amounts of material are deposited over a large area due to melting
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What was the perception of the wilderness until 1700s?
* Frightening, ugly, primitive etc
| * Inhabited by wolves, bandits, witches etc
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What was the US national park movement? (Value of glacial and periglacial landscapes)
Wilderness campaigners like Jon Muir (1838-1914) helped to establish:
•Yellowstone National Park (1872 - oldest in the world)
•Yosemite National Park (1890)
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Norwegian culture: food🇳🇴(value of glacial and periglacial landscapes)
* Fjords and glaciated uplands provide food sources
* Smoked and dried food - long dean Arctic winter
* Reindeer grazing on Arctic tundra grass
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Norwegian culture: transport🇳🇴(value of glacial and periglacial landscapes)
* Fjords - key transport routes in western Norway
* Seafaring culture from vikings to present
* Until 1850s, main route from north to south Norway was across the Jostedalsbreen ice cap - cattle herders crossed in early summer while snow still covered the crevasses
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Norwegian culture: winter sports🇳🇴(value of glacial and periglacial landscapes)
* Skiing - used in Norway for over 5000 years
* First skiing competitions in Norway, 1840s
* Norway has won over 329 winter Olympic medals - more than any other country, but only has a population of 5.2M
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Norwegian culture: skiing and national identity🇳🇴(value of glacial and periglacial landscapes)
Ammonia factory at Rjuken, Telemark used by nazis to try and build an atomic bomb. Destroyed but Norwegian resistance fighters - escaped by outskiing 3000 German troops for 400km to Sweden
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Norwegian culture: a rural society🇳🇴(value of glacial and periglacial landscapes)
* Glaciated upland environment with thin souls and flooded fjord valley leads to a sparse population
* Isolated rural communities developed at fjord heads on small patches of land
* Wood from coniferous forests was main building material
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Norwegian culture: farm culture🇳🇴 (value of glacial and periglacial landscapes)
* Today 57% of population live in rural settlements of <2000
* Norsk Folkemuseum, 1881 - oldest open air museum and one of the top attractions in Norway - marketing Norwegian culture
* Bunad costumes - traditional farming costumes unique to each area of Norway
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Pros for agriculture
* Glacial till plains are very fertile
| * Soils on the base of u-shaped valleys can be several metres deep - Glencoe Valley, Scotland
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Cons for agriculture
* Glacial till deposits have a clay matrix - retain water - poor drainage -e.g. English Fenlands
* Only suitable for farming if expensive drainage/pumping systems are installed
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Different landforms usefulness for farming
* Till deposits in gentle hills or and undulating plain - soils are fertile, slopes allow water to drain but matrix means plants have sufficient moisture
* Flat valley bottoms don’t drain well
* Sandar are stable and good for drainage - used for building - Belmont in Hereford
* Glacial eroded lowland areas are sometimes free of soil cover - inhospitable - e.g. Knock and Lochan in Outer Herbrides
* Dead Ice topography - chaotic drainage pattern
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Communications
* Communication links are facilitated where valleys are straightened and have straight flat wide floors
* Abandoned spillways from proglacial lakes provide natural gaps or passes through upland areas - e.g. main road in gorge in Herefordshire
* Fjords provide natural harbours - e.g. Royal Navy’s nuclear submarine base
* Eskers provide foundations for some Finnish roads and railways
* Clay rich till deposits are very prone to landslides, especially after heavy rain
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Settlements
* Crag and tails can provide defensive sites - e.g. Edinburgh Castle on the crag, city on tail
* Jokulhlaups can sometimes threaten settlements and cause loss of life
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Tourism and leisure
* Glacial landscapes are very popular with tourists - 120M people visit the Alps each year, highlands of Scotland, Lake District, north wales attracts tourists
* Over steepened slopes encourage avalanches
* Glacial scoured mountains are fragile and unable to cope with mass tourism
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CHECK NOTES FOR
The impact of human activity on glacial environments (anthropogenic climate change) case studies
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What are wilderness areas? (Alaska)🇺🇸
* Much of the arctic tundra and Antarctica typifies ‘wild areas’
* The remoteness/extremes of physical processes keep them inaccessible to mass tourism - instead, exploited for oil
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Pressure to develop (Alaska)🇺🇸
* Comes from National and transnational groups that require both energy and natural resources to support industrial growth
* Difficult to balance development pressures and the need to conserve
* Biggest pressure is the need for oil
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What is the trans-Alaskan oil pipeline case study about? (Alaska)🇺🇸
* How we use periglacial:glacial environments
| * How humans affect environments
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Prudhoe Bay oilfield (Alaska)🇺🇸
* Discovered in 1968 - pumping since 1977
* Largest oil field in North America
* 18th largest oilfield in the world
* Estimated 25B barrels of oil trapped below ground
* Icebound - can’t use ships to transport oil
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Fragile environment (Alaska)🇺🇸
* Slow rate of plant growth - 50 yrs to return to former state after being disrupted
* Low productivity and limited species diversity makes regeneration difficult
* Crosses paths of caribou, musk oxen, grizzly bears, wolves, moose
* Concern due to shale oil reserves in North Alaska
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Dead horse town, Prudhoe Bay (Alaska)🇺🇸
* 5,000 employees
* Average of 680,000 barrels per day produced
* US receives 17% of its domestic oil by this process, making Prudhoe Bay a vital contributor to the country’s overall oil resources
* Over 10B barrels of crude oil have been produced so far
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Pollution worries (Alaska)🇺🇸
* The pipeline is beginning to corrode
* In Jan, 2011 a leak occurred, releasing 13,000 gallons of oil at the North Slope Pump Station - a large spill would be dire due to a diminished capacity to recover spilled oil in Alaskan waters
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Where does the oil get transported to? (Alaska)🇺🇸
Prince William Sound, Gulf of Alaska
| 1200km
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What mountain ranges does the pipeline cross? (Alaska)🇺🇸
Brooks Range
Ray Mountains
Alaska Range
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What national parks does the pipeline cross or come near to? (Alaska)🇺🇸
Arctic National Park
Arctic National Refuge
Wrangell St Elias National Park
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How many rivers/streams does the pipeline cross? (Alaska)🇺🇸
Over 800
| Including the Yukon - major river
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USE ‘POLESAPART RESOURCES IN THE ARCTIC’ TO MAKE FACTS AND FIGURES FLASHCARDS
For extra facts and figures
200
READ ‘OPPORTUNITIES PROVIDED BY GLACIAL ENVIRONMENTS’
For the benefits
201
Positive impacts of ski lifts
* Essential for downhill skiing - attracts a mass market
* Used by locals to get up and down mountains
* Allows access and enjoyment of the mountains for other sports in winter and summer
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Negative impacts of ski lifts
* Energy consumption
* Noisy
* Eyesore all year round
* Require buildings up the mountain as well as the base
* Construction process is invasive and leaves scars from access roads created to get machinery up
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Positive impacts of artificial snow
* Guarantee the season for the resort - allowing it to economically depend on skiing
* Snow depths are guaranteed, protecting the land underneath
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Negative impacts of artificial snow
* Energy consumption
* Uses a lot of water - France uses as much as a town with 170,000 people
* Reservoirs are required to collect water - e.g. Val D’Isère, 36,000 m2
* Takes longer to melt at the end of the season - impacts vegetation growth
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Chamonix tourism negatives🇫🇷
* Noisy and congested roads
* Footpath erosion
* Expensive
* Avalanches
* Light pollution
* Snow fences - eyesore
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READ ‘HUMAN IMPACT ON GLACIAL LANDFORMS AND PROCESSES’
For extra information
207
READ ‘THREATS TO GLACIATED LANDSCAPES’
For extra information
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How may a glacial lake outburst flood occur? (Threats from natural hazards)
* Lakes blocked by moraine increase in size due to glacial melting
* Moraine wall collapses
* Causes a glacial lake outburst flood
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Examples of natural threats facing active and relict glacial landscapes
* Avalanches
* Glacial outburst floods
* Thick, unstable till deposits
* Natural climate change
* Extreme cold temperatures
* Thin soils
* Fragile ecosystems
* Steep rugged terrain
* Seasonal extremes
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Examples of human threats facing active and relict glacial landscapes
* Footpath trampling by tourists
* Introduction is invasive species
* Visual pollution
* Water & air pollution
* Noise pollution
* Overfishing
* Construction
* Resource exploitation
* Human-induces climate change disrupting natural cycles
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How did Greenland threaten glacial landscapes in 2014?(threats from human activity)🇬🇱
* Government reversed ban on uranium mining
* Areas of Southern Greenland could be opened up to large scale mining projects
* Conversationists feared impact would be widespread and irreversible
* Radioactive waste endangers fisheries and farmland - southern Greenland is only part capable of supporting farming
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How can political disputes threaten glacial landscapes?(threats from human activity)
* In 2007, Russia claimed part of Arctic seabed in North Pole
* Caused conflict with other arctic nations
* Other nations have now staked their own claim to sections of Arctic seabed
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How have the military used the arctic?
•During Cold War missiles travelled over arctic - shortest route
•Nuclear submarines under ice
•Used as a nuclear testing ground
NOT USED ANYMORE
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Generic benefits of glacial environments (opportunities)
* Tourism - e.g. winter tourism
* Energy production - e.g. HEP system
* Water supply - e.g. glacier meltwater
* Quarrying - e.g. pressure release after melting - cracks open up
* Agriculture - e.g. sheep farming
* Transport/communication - e.g. produces routes
* Settlement - e.g. depositional features raise settlements above the ground, away from floods
