Glaciation

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What is greenhouse earth?
A time where there are no ice sheets/glaciers on Earth, warmer temperatures, normal state
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What is icehouse earth?
A global ice age, where ice sheets cover a large proportion of land due to cooler temperatures, includes inter-glacial and glacial periods
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What is the Quaternary period?
The most recent ice age, started 2.6 million years ago, divided into two epochs (Pleistocene and Holocene)
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What are the Pleistocene and Holocene
Pleistocene: glacial period, 10,000 years ago. Holocene: now, began 10,000 years ago, inter-glacial period
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How was Antarctica formed?
Continental drift moved it over the South Pole, ice sheets formed, became severed from South America, surrounded with ocean and cut off global ocean warmth
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What is the Albedo effect?
The proportion of solar radiation reflected by a surface, snow and ice reflect 90%, melting reduces the Albedo effect and so even more melting will occur.
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What is climatic feedback?
Can amplify a small change and make it larger (positive) or diminish the change and make it smaller (negative)
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What is a glacial period?
Cold periods where glacial ice advances, lasts 100,000 years
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What is an interglacial period?
Warm periods where glacial ice retreats, lasts 10-20,000 years
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What are Milankovitch cycles?
Changes in Earth's orbit, axis and tilt- affect amount of radiation received so determine glacial or interglacial periods.
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What is eccentricity?
The shape of Earth's orbit: elliptical (lasts 10-20,000 years) so Earth receives less radiation at some points, increases seasonality, interglacial period. Cicular orbit (100,000 years), decreases seasonality, glacial periods
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What is obliquity?
The tilt of Earth's axis, varies between 22.1 and 24.5 degrees (41,000 year cycles): maximum tilt=more sunlight in polar areas, interglacial period. Minimum tilt= less sunlight in polar areas, glacial period
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What is precession?
Earth's wobble on its axis(21,000 year cycles): season during which Earth is closest to Sun varies, changes intensity of seasons.
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What was the Loch Lomond stadial?
Last glacial advance in UK, 12,000-10,000 years ago at end of Pleistocene epoch, permafrost and tundra over most UK, glaciers in Lake District and North Wales, 6-7 degree drop in temperature.
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What is thermohaline circulation?
A global system of surface and deep ocean currents driven by temperatures and salinity. e.g. warm water from Gulf of Mexico rises to north-west Europe, then sinks quickly in cold North Atlantic.
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What happened with Lake Missoula?
This huge lake in North America flooded into the Atlantic, diluting oceans and disrupting the circulation, leading to global cooling.
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What is the meteorite theory?
A meteorite 11,000 years ago exploded in Earth's atmosphere, blocking light and resulting in global cooling.
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What is the sun-spot theory?
Intense magnetic activity in Sun's interior, more sun-spots=more energy=increases Earth's temperatures, 11-year cycles.
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What was the Laacher See eruption?
12,900 years ago, VEI of 6, released so much ash it contributed to global cooling.
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What was the Medieval warm period?
899-1300AD, more North Sea melted, allowed Vikings to colonise Greenland
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What was the Little Ice Age?
1300-1870 cooler temperatures, Greenland Vikings died out as they couldn't get through ice, stopped by warming of industrial revolution
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What is the cryosphere?
Cold environments, water is ice e.g. snow, river and lake ice, sea ice, periglacial environments, glacial environments, tributary glaciers
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What are unconstrained/ constrained glaciers?
Unconstrained: larger glaciers, so thick they submerge landscapes and can flow away. Constrained: forced to stay within a landscape.
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What are high latitude/polar glaciers?
Very cold, low precipitation, slower glaciers, ice caps and ice sheets.
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What are high altitude/alpine glaciers?
Wide range of temperatures, high levels of precipitation, fast glaciers, cirques, valley glaciers, piedmont, highland ice fields.
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Give examples of different types of glacier.
Ice cap: Greenland. Ice sheet: Antarctic. Cirque: du Maudit. Valley glacier: Mer de Glace. Piedmont: Skaftarjokull. Highland ice field: Vallee Blance
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What is a relic Pleistocene landscape?
Landscape not currently experiencing glacial activity, features fossilised glacial landforms, e.g. UK
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Why are glaciers useful?
Major source of water, evidence for past climates and events
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How is glacial ice formed?
Snow falls (90% air), more snow falls, condenses into firn/neve (50% air), eventually compresses into 10% air, ice becomes thicker, moves down-slope due to gravity, pressure melting infiltrates gaps, re-freezes and increases density further
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What is the significance of positive degree days?
The fewer days where temperatures are above 0 degrees, the more snow will survive summer, causing net accumulation.
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Where are peri-glacial landscapes found?
50N-60N
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What is permafrost?
Permanently frozen ground, soil temperatures below 0 for 2+ years, 2.5% Earth's surface, continuous (surface to bedrock) or discontinuous (not all the way to bedrock)
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What is the active layer?
Varies in depth from few cm to 5m, often saturated as meltwater cannot infiltrate permafrost beneath
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What is talik?
An unfrozen patch or layer, kept above 0 degrees by geothermal heat or insulation by water,
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What are the processes in peri-glacial landscapes?
Solifluction, frost heave, ground contraction, frost creep, weathering, nivation
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What is the process of solifluction?
Mass movement where waterlogged sediment moves slowly downslope over impermeable permafrost, due to melting in the warm season leading to saturation of the active layer.
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What is the process of frost heave?
Stones cool faster than soil, an ice lens will form beneath stones, ice expands by 9% so the above stone is pushed up until it breaks the surface, larger stones fall outwards, forms stone polygons, stripes or patterned ground.
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What is process of ground contraction?
Refreezing of active layer in winter, soil contracts, cracks open, fill with meltwater in summer, freeze again in winter and widens further, creates ice wedges and patterned ground.
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What is the process of frost creep?
Ice in the soil pushes up stones and soil diagonally on a slope, this resettles back down vertically when the ice melts, causes material to move slowly downslope.
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What is the process of weathering?
The breakdown and changes in rock at or near the surface, in situ, physical and chemical methods: physical action of water and ice, or freeze thaw weathering where expansion of frozen water cracks rock.
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What is the process of nivation?
Some snow patch melts in summer, meltwater fills cracks in rock, freeze thaw disintegrates rock, meltwater erodes the crack into a hollow, glacier can form in the hollow
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What features are created in peri-glacial landscapes?
Solifluction lobe, stone polygon/stripes/patterened ground, ice wedges, nivation hollow, pingos, blockfields, tors, scree slopes, protalus ramparts, loesses, braided stream, thermokarst
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What is an open system pingo?
Groundwater is freely available, water gets into upper layers of ground by artesian pressure through discontinuous/thin permafrost, water freezes around sediments, expands, forces above sediments up into a dome
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What is a closed system pingo?
Lake drains, talik shrinks due to loss of insulating layer, hydraulic pressure from advancing permafrost causes water in talik to concentrate in centre, freezes into ice, expands, deforms upper sediments into a dome
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What is a blockfield?
Angular rock fragments, accumulated frost shattered stones and boulders on a flat surface, resistant rock protrudes, e.g. Stone Run, New Zealand
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What is a tor?
Jumbled mass of exposed bedrock rising abruptly, soil often removed by solifluction, rock exposed to weathering, e.g. in Dartmoor
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What is a scree slope?
Slope of accumulated rock fragments at a cliff foot, large boulders at the bass due to higher mass e.g. Lake District wastewater
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What is a protalus rampart?
Snow patch at cliff foot causes falling rocks to slide along snow, when snow melts a rampart of rock is left at a distance from the cliff e.g. North slopes of Cwm Idwal Snowdonia
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What is a loess?
Wind-blown deposits of fine silt, aridity and lack of vegetation allows for wind action
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What is a braided stream?
A river with multiple interwining channels, sometimes vegetated islands between them, formed due to erosion in summer and subsequent deposition
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What is thermokarst?
Created when vegetation is cleared from active layer, exposes ground to radiation, reduces insulation, melts permafrost, creates irregular ground interspersed with waterlogged holes.
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What impacts can thermokarst cause and what can be done about it?
Can damage buildings and infrastructure due too subsidence, structures can be built on aggregate pads and utilidors, which can substitute the insulating effect of vegetation and keep building heat away from the ground to prevent melting of permafrost
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What are glacial inputs/accumulation?
Snowfall, avalanches, windblown snow
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What are glacial processes?
Erosion, transportation, deposition
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What are glacial outputs/ablation?
Melting, iceberg calving, sublimation
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What is negative feedback?
Minimises effect of new inputs e.g. more snowfall pushes more ice into ablation zone, means more melting occurs and balances the advance.
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What is positive feedback?
Increases effects of new inputs e.g. more snowfall=glacier grows=increased Albedo=fall in temperatures=further growth
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What is mass balance?
Difference between total accumulation and total ablation for whole glacier over a year.
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What is dynamic equilibrium?
Glacier system tries to re-balance as climate changes, tries to reach a state of 0 mass balance.
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Brilksdalsbreen glacier, Norway
Largest in mainland Europe, 80km long, constantly retreats and advances
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What are the types of glacial movement?
Basal sliding, intragranular slip, crevasses, regulation slip
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What is basal sliding?
Imbalance of ablation and accumulation, mass builds up, weight exerts downslope force due to gravity, greater friction at base reduced velocity, stress produced when ablation and accumulation are not equal
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What is intragranular slip?
When individual ice crystals deform under sheet stress
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What is a crevasse?
Extending and compressing flows, when glacier speeds up downslope the ice extends and creates transverse crevasses, when it slopes at the bottom it compresses into reverse faults.
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What is regulation slip?
In rough landscapes, pressure is highest going uphill, melting occurs, reduces friction, allows glacier to flow on, pressure lower on downslope so can continue moving.
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Hubbard glacier, South Alaska
150km long, advanced 10m a day, blocked fjord, created lake, trapped animals and threatened towns
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What factors affect rate of glacial movement?
Geology (permeable so meltwater infiltrates, less lubrication, or unconsolidated material which offers little resistance), slope angle, climate, thickness of ice (pressure melting), excessive calving
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Stress of glacier equation
Stress glacier exerts on ground= density of ice x acceleration due to gravity x thickness of glacier
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What is erosion?
The removal of soil and rock and subsequent transportation by agents of erosion e.g. glacier, wind, sea, rivers
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What is glacial crushing?
Direct fracturing of bedrock due to weight of ice
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What is plucking?
Once crushed and fragmented, rock can be entrained (picked up), often leaves rough surface
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What is abrasion?
Sub-glacially, material plucked acts as sandpaper, smoothing rock
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What is a fluvio-glacial meltwater channel?
Under enough pressure meltwater can erode rock, especially when transporting rock in it, gouges out a channel.
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Name some glacial erosional landforms?
Chatter marks, striations, rouche moutonee, glacial trough, truncated spur, cirque, arete, pyramidal peak, ribbon lake, fjord, hanging valley, areal scouring, knock and locan, crag and tail
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What are chatter marks?
Irregular chips in rock made by vibratory chipping on bedrock by rock fragments carried sub-glacially, crescent shaped, right angles to direction of movement
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What are striations?
Scratches on surface where plucked fragments are dragged smoothly on surface, elongated grooves/etchings, show direction of movement
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What is a rouche moutonee?
Ice smoothed rock, stoss (upstream) is gently sloping and smooth due to abrasion, lee (downstream) is steep and rough due to plucking
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What is a glacial trough?
Straight, trench-like valley, wide, flat, steep sides, fill entire valley, huge erosion power, direct route, widened, deepened, straightened
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What is a truncated spur?
Former spur eroded in lower part by valley glacier, steep cliff sides formed
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What is a cirque?
Bowl-shaped hollow with steep back wall and rock lip, NE facing slopes, tarn can form in hollow, moraine dams it, hollow forms as it is the convergence zone of ice flows from multiple directions, begins as nivation hollow.
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What is an arete?
Thin, knife-like ridge, when two glaciers erode parallel U-shaped valleys, or two cirques erode backwards.
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What is a pyramidal peak?
Pointed peak with steep radiating sides, three or more cirques erode backwards, sharpened by frost shattering e.g. Matterhorn
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What is a ribbon lake?
Long, narrow lake, fill many U-shaped valleys, terminal moraine dams, begin due to glacial erosion of valley forming a trough.
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What is a fjord?
Flooding of glacial valley with sea water, glacier cuts valley, when melting the ground rebounds, normally have terminal moraine at the mouth, deepest in back or middle where glacier was longest, e.g. 1300m deep Sognefjord
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What is a hanging valley?
Tributary valley whose mouth ends abruptly part way up side of main valley due to lower erosion e.g. Mitre Peak, New Zealand
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What is areal scouring?
Process which creates large scale scraping of landscapes as glacier enters lowlands
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What is a knock and locan landscape?
Alternating features, knock is a small rock hill, locan is a small lake, chaotically spaced, depends on rock resistance (knock=most resistant, locan=least resistant)
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What is a crag and tail?
Resistant crags shelter less resistant tail, first the glacier erodes soft rock and leaves behind a resistant outcrop, this shelters softer material in its lee, show ice direction e.g. Royal Mile castle
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What is clast shape?
Roundness, either angular or smoother edged rocks, depending on how much they moved and have been eroded by attrition.
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What is sediment fabric (orientation, support, imbrication)?
The direction the clast points, are they in contact and support each other (class) or supported by smaller particles (matrix), imbrication is whether they are stacked in the direction of flow
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What is sediment stratification?
Stratified is divided into different layers, unstratified is not layered, graded sediment has largest particles at the bottom and fine ones at the top.
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What is sediment sorting?
Unsorted has a range of class sizes, well sorted has the same size
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What is sediment lithology?
Whether rocks are local or erratic
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What are the features of till (ice contact deposition)?
Angular shape, horizontal orientation, supported in matrix, unstratified, unsorted, erratic and local rocks
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What are the features of fluvio-glacial deposits (outwash)?
From meltwater, rounded clasts, some imbrication, no matrix, move into position of least resistance, stratified and graded, sorted, erratic and local rock
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What are the different depositional glacial landforms?
Drumlins, till plain, moraines, erratic boulders
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What is a drumlin?
Made of till, elongated mounds, shallow lee sheltered from ice, steep stoss in the face of the flow, often in swarms, formed due to glacier depositing as it is overloaded with sediment, due to melting or a obstruction, friction exceeds drag
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What is a till plain?
If the glacier is transporting enough sediment, entire low areas can be filled completely with lodgement till, changes undulated landscapes into flat, broad expanses, e.g. East Anglia (30-70m thick)
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What is a moraine?
Glacially formed accumulations of unconsolidated debris deposits
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What is a lateral moraine?
Parallel ridges of debris deposited down glacier sides, supra glacial by frost shattering of valley walls and from tributary streams flowing down the side.
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What is a medial moraine?
Ridge down the centre of the valley, formed when two glaciers meet and debris on the edges join and are carried on to of the enlarged glacier.
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What is a terminal moraine?
At the snout of the glacier, marks the maximum advance, debris from abrasion and plucked is pushed to the front and then dumped in a heap, the longer in one place the more is deposited there
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What is a recessional moraine?
Form where a retreating glacier remained stationary for long enough to produce a mound of material, retreating ice pauses.
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What is a push moraine?
Retreated glaciers advance again, material already deposited is pushed into mounds as the ice advances, different orientations
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What is an erratic boulder?
Piece of rock that differs from the size and type of rock native to the area in which it rests, can be carried 100s kms, range in size, indicate prehistoric glacial movement, can travel in meltwater
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What are the different depositional fluvio-glacial landforms?
Esker, kame, kame terrace, kettle hole lake, outwash plain/sandur, proglacial lake, varve deposit
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What is an esker?
Ridges of stratified coarse sand and gravel,deposited by sub-glacial and en-glacial meltwater channels, can be 100s kms long
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What is a kame?
Deposits from supra-glacial meltwater deposition, concentrated nearer snout, deposited in ice surface depressions and crevasses, when glacier melts these invert into mounds
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What is a kame terrace?
Sediment accumulates between glacier and valley sides from meltwater streams, sorted sand and gravel, the streams formed due to melting at valley sides in summer, look like long flat benches
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What is a kettle hole lake?
Blocks of ice separated from main glacier as glacier retreats or due to calving, blocks may become buried in meltwater sediment, when ice melts, they leave holes that fill with water and become kettle hole lakes.
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What is outwash plain?
Sediments deposited at end of glacier, meltwater carries sediments away from glacier and deposits on a broad plain, size-sorted, smallest furthest deposited e.g. in Svalbard and Iceland
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What is a proglacial lake?
Lake formed by damming of a moraine or ice dam during glacial retreat, or meltwater trapped against an ice sheet, e.g. Lake Missoula
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What is a varve deposit?
Annual layer of sediment, in lakes near glacial margins, peak meltwater a lighter sandy layer is deposited, in winter silt is much finer.
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How are glaciers useful for agriculture?
Fertile till plains e.g. Glencoe valley, clay matrix retain water resulting in poor drainage, e.g. English Fenlands, drainage may be necessary in flat land, but undulating landscapes can naturally drain and are fertile e.g. East Anglia.
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How are glaciers useful for communication?
U-shaped valleys, flat fjords, abandoned spillways from proglacial lakes provide natural gas or passes through uplands e.g. col head in Glencoe valley, fjords as harbours e.g. Royal Navy at Gare Loch, eskers foundations for Finnish roads, landslides
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How are glaciers useful for settlements?
Crag and tails strategic settlements e.g. Edinburgh castle, glacial outburst floods can threaten settlements
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How are glaciers useful for energy and water?
Water stores in lakes, height provides HEP, e.g. in Snowdonia, unused rain water sent to areas of deficit, direct drinking water, e.g. 40% Asia rely on meltwater from Himalayas, Rhone valley uses meltwater for irrigation.
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How are glaciers useful for quarrying?
Release of weight allows easier quarrying, truncated spurs expose rock, e.g. Great Langdale, Lake District, fluvio-glacial sands and gravels used in construction and for cement.
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Alps-Chamonix
Population 10,000, increases to 60,000 in summer and 100,000 in winter due to tourism, Alps receive 120 million tourists a year (10% global tourism)
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What are the positives and negatives of skiing in the Alps?
Positives: mass tourist market, economic growth. Negatives: energy consumptive, noise, eyesore, invasive, deforestation.
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What are the positives and negatives of artificial snow in the Alps?
Positives: guarantees season, can depend on tourism, snow depth protects land. Negatives: energy, water (as much as a town with 170,000), impacts vegetation, additives, increased meltwater in spring.
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What are the positives and negatives of HEP in the Alps?
Positives: 4 reservoirs, 2 power stations, produces 870GWh energy a year, reduced fossil fuels. Negatives: eyesore, affects habitats, damages water ecosystems.
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What are the positives and negatives of machine grading pistes in the Alps?
Positives: ensures mass market, safety, snow lasts longer. Negatives: deforestation, machines ruin land and vegetation, avalanches, energy, oil leaks.
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What are the positives and negatives of transport in the Alps?
12 million lorries, 50 million lorries a year, noise, pollution, congestion, acid rain which 60% forests suffer from.
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Norwegian food
Game, fish, smoked and dried food e.g. smoked salmon, stockfish (main export) and reindeer.
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Norwegian transport
Fjords, Vikings, North-South route across Jostedalsbreen ice cap, cattle herders crossed in early summer while snow covered crevasses at night when frozen, led to skiing.
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Norwegian winter sports
Skiing, used for 5000 years, first competition in Norway, won 329 winter Olympic medals but only has a population of 5.2 million
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Norwegian identity
Nazis tried to build atomic bomb at Rjunkan, destroyed by 6 Norwegian resistance fighters who escaped by out-skiing 3000 German troops for 400km
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Norwegian rural society
Sparse population, houses traditionally from wood, 57% live in settlements under 20,000, Norsk Folkemuseum, Banad traditional farming costume unique to each area.
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Norwegian sagas and stories
Long Arctic winters lead to storytelling and plays.
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What are some natural hazards in glacial landscapes?
Avalanches, rock falls, landslides, flooding. Avalanches occur when sheer stress exceeds sheer mass on a slope, rapidly accelerate, kill 200 a year, Yungay and Ranrahirea avalanche killed 18,000, subsidence in periglacial landscapes, jokulhlaups.
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What are some human hazards in glacial landscapes?
Deforestation (only 30% Nepal's forests remain, for farming, fuel, loss of habitats, soil erosion, landslides, climate change), footpath erosion, water pollution, waste, congestion, air pollution, Everest polluted with rubbish, Arctic fuel spills
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How is global warming impacting glacial landscapes?
Everest glaciers shrank 13% in 50 years, Rocky mountain glaciers lost 25-75% mass since 1850, 95% Himalayan glaciers rapidly retreating, less albedo=exponential retreat, reduces water supply (350 million Chinese farmers rely on it)
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How is global warming impacting glacial landscapes? (2)
More floods, higher lakes, Arctic amplification, 14% carbon stored in permafrost= more CO2 released, rise in 1 degree= 100m higher tree line, closure of ski resorts, 2 degree rise= £2 billion cost for Switzerland
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Lake District
16 million tourists, spend £1.1 billion, support local business, 16,000 jobs. Footpath erosion, trampling, litter, congestion, poor/seasonal jobs. LDNPA manages area but only owns 3.9%.
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What are the different management strategies for glacial landscapes?
1) Do nothing 2) Business as usual: exploit with some pre-existing sustainability l 3) Sustainable management:benefit community but conserve for future 4) Comprehensive conservation:carefully regulated 5) Total protection: no access
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Sagarmatha, Nepal, National Park
Re-establish forests and reduce erosion, sponsored by Sir Edmund Hilary Foundation e.g. for schools, hospitals, bridges, banning goats, use kerosene for fuel, HEP stations for local use, limit development projects.
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What legislative protection is there for glacial landscapes?
International: Antarctic Treaty, international governance, regulates waste, prevents pollution, protects and conserves. Global: International Trade in Endangered Species- protects vulnerable species. National: National Parks
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What legislative protection is there for glacial landscapes?
Alpine Convention: EU and Alpine countries protect environment while promoting economic development, covers water, soil, transport, energy and climate.
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What are some management challenges in glacial landscapes?
Lake District: hotter, drier summers, more extreme weather, loss of species, movement to lower altitudes, more soil washed into lakes= eutrophication. Hard to predict, more extreme weather and disasters, rise in sea levels risking 300 million lives
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What is a wilderness?
Uninhabited, inhospitable, remote regions. Keeps inaccessible to mass tourism, new technology has allowed more exploitation e.g. for oil, energy and resources- makes conservation difficult.
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Why are wilderness environments important?
A 'living lab',contain endemic species, purer gene pools.
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National Parks
Wilderness campaigners like Joh Muir helped establish. Yellowstone, 1872, first National Park. Most UK National Parks are relic glacial landscapes.
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Alaska
Prudhoe Bay largest oil field in North America, 25 billion barrels trapped, ice bound most of the year, Prince William Sound in the South is unfrozen, so a 1200km pipeline was built to transfer the oil. Crosses 3 mountain ranges, major rivers.
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Alaska (2)
Crossed 3 National Parks, fragile tundra environment easily damaged, up to 50 years to recover from minor damage, January 2011 leaked 13,328 gallons of oil, concerns over future exploitation e.g. of shale oil reserves.
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Alaska (3)
Pipeline raised 8-10ft to allow Caribu, Musk oxen, moose and grizzly bear migration. 5000 work in oil fields, 680,000 barrels produced a day, 17% USA domestic oil, 10 billion barrels altogether so far
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