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Physical case studies Flashcards

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1
Q

How did Borrowdale form?

A

2 million years of glacial and interglacial periods
tectonic movement - 2 major periods of mountain building - uplift and folding
discordant radial drainage pattern made across rock bands

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2
Q

how did lakes and troughs form in Borrowdale?

A

originally u-shaped valley
ribbon lakes - BVGs eroded landscape

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3
Q

how/where did corries form in Borrowdale?

A

BVGs - hilly and mountaneous area
south - lower and weaker ice movement - not high enough for corries
to form hard/resistant rock is needed - south would collapse

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4
Q

how does altitude affect Borrowdale?

A

lower hills in north
higher in south
glacier moves from corries hills -> lower
weathering

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5
Q

how does geology affect Borrowdale?

A

2 million years of glacial cycles
BVGs - resistant, hard, steep sloped, jagged profiles
north - Skiddaw slates - smoother, less resistant

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6
Q

how does aspect affect Borrowdale?

A

corries in N
N-S orientation of ice
few corries formed e/w due to more solar isolation

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7
Q

how does climate affect Borrowdale?

A

upland areas temperature is lower
wet and cold - more precipitation and snow
mechanical and chemical weathering

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8
Q

how does relief affect Borrowdale?

A

hills created by BVGs - steep, cragged
west more smoothly sloping

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9
Q

What are the flows of material in Borrowdale?

A

Rock/moraine moved along valley
weathering and mass movement
ice

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10
Q

what are the flows of energy in Borrowdale?

A
  1. meltwater - warming climate = more kinetic energy to move sediment (Derwent water filling up)
  2. GPE higher up and decreases with ice/rock flow, ice on gradient = kinetic energy
  3. thermal energy - ice melts and sediment is deposited
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11
Q

Short-term changes in Borrowdale

A

mass movement - rockfall, slide, slump
material high up no longer there - changes valley - scree

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12
Q

medium term changes in Borrowdale

A

seasonal/annual
1. large differences (+ve and -ve balances affect retreat and advance which affects deposition and transportation)
2. moraines - variation - more deep = -ve snout position changes

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13
Q

long term changes to Borrowdale

A

interglacial and glacial periods
repeated periods of erosion = features

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14
Q

what are the main erosional landforms in Borrowdale?

A
  • glacial trough - Borrowdale valley
  • corrie - the Combe
  • ribbon lake - Derwent water
  • hanging valley - Gillercomb
  • high mountains - Great Gable - climate - temperature decrease, altitude increases snow - corries formed - nivation/accumulation
  • Jaws of Borrowdale - local variation in rock resistance harder - less able to erode
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15
Q

what are the main depositional landforms in Borrowdale?

A
  • drumlins - Derwent water island/near Keswick
  • recessional moraine (rothswaite)
  • hummocky moraine - upper areas of trough/corries
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16
Q

what is the different significance of depositional and erosional landforms?

A

Erosional - larger and more dramatic (valleys created by repeated periods of erosion. climate and geology influenced

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17
Q

How does mass movement affect geomorphic processes?

A

slumps and slides - smoother slopes
rockfalls - steep relief

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18
Q

how does weathering affect geomorphic processes?

A

frost shattering
freeze-thaw cycles
rock weakened when water expands so break - joints formed
deglaciation - pressure release - dilation

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19
Q

how does glacial transport and deposition affect geomorphic processes?

A

climate change - repeated cycles - till deposited reworked over time
features today present from last glacier - either see last glacier or long term

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20
Q

how does glacial erosion affect geomorphic processes?

A

glacial and interglacial periods - colder = more plucking and abrasion - repeated cycles - more prominent features
geology - hard resistant BVGs eroded by cycles, rocks will not collapse easily, some features do not remain
N-facing slopes - corries form, cold climate and erosion

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21
Q

How are landforms in Borrowdale interrelated?

A

corries on N side (angle tarn) - ice formed N facing and glaciers flowed S–>N valleys - deeper, wider, steep sides
truncated spurs formed
ribbon lake - overdeepened valley
hanging valley - smaller troughs up steep river valleys/waterfalls
roche mountonees - floor of trough where glacier cannot erode as easily - wouldn’t exist without ice movement
Jaws of Borrowdale - valley narrowing due to more resistant rock - connects with depositional - drumlins where moraine deposited at snout - repeated = recessional - location die to direction of ice flow up valley
all connected due to their formation from glacial activity

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22
Q

what is the location and profile of Alaska?

A

massive
above the Arctic circle
coastal and interior regions and mountain ranges
extreme climatic variability - wet maritime south to extreme cold north
periglacial

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23
Q

why is human activity occuring in Alaska?

A

natural resources - diversity, 4th largest glaciated area, gold, minerals, 40% surface water, fisheries etc
nomadic lifestyle still present
WW2 - desired to be self-sufficient
Gulf war 1990-91 and oil price crisis
ANWR drilling

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24
Q

what are the benefits of drilling in Alaska?

A

1973 protected NA hunting
univasive techniques being developed
jobs
$1000 bonus per Alaskan per year
reduces trade defecit

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25
Q

what human activity has occured in Alaska?

A

20% US oil produced
gold rush
2450km Alaskan highway - war
1959 depressed 2/3rd gov employees
found largest oil field
1977 Trans-Alaskan pipeline completed
12.8bn barrels transported
crisis = depression (single commodity income)
Valdez harbour
cities for workforce

26
Q

How much oil remains in Alaska?

A

3 billion barrels - depleted by end of decade

27
Q

how has human impact been minimised?

A

pipeline built on flexible stays for natural hazards and to allow migration and river movement underneath
insulation of buildings and roads to prevent permafrost melting
12 stations

28
Q

what are the main flows of material in Alaska as a result of human activity?

A
  1. gravel pads for construction - extracted from streams and beds as insulating layer for roads
    loss of gravel = alters rate of transportation and deposition downstream, equilibrium changes - more erosion - beds and banks change course
    groundwater levels fell by 1m in 2km radius from extraction site, aquifer Palmer groundwater fell
  2. extraction of material from borrow pits - material removed for road/airstrip construction. holes in the ground formed - active layer removed, permafrost exposed. thermokarst rapid - stablises 10 years, subsidence - water table lowers
29
Q

what are the flows of energy in Alaska due to human activity?

A
  1. release gas/burning of gas in drilling
    flaring - chemical energy –> heat/light release gas/energy
    carbon dioxide and methane contribute to enhanced greenhouse effect, terrestrial radiation trapped in lower atmosphere - snow cover is reduced locally, causing increased temperature and an increased active later = more veg = more disruption to permafrost
  2. heat from buildings and infrastructure
    urban island heat - Barrow 2.2 degrees higher than surroundings - domestic buildings
    9% fewer days of temperatures below zero (freeze-thaw)
30
Q

what are the 4 main impacts on Alaska’s periglacial environment due to human activity?

A
  1. deeper active layer, permafrost table drops, discontinuous and sporadic permafrost increase rapidly
  2. patterned ground change - less freezing and thawing (less frost heave in summer) - fewer stones pushed up, patterns are not maintained
    mass movement by creep degrades domes
  3. solifluction rate increases, active layer increases, lobes, stepped profile - soil slides
  4. collapse of pingos - temperature rise = ice core thaws = ognip dome collapses rampart surrounding left
31
Q

what are the consequences of human activity on Alaksa?

A
  1. formation of thermokarst - landscape dominated by surface depression due to thawing of ground ice. extensive areas of hummocky ground interspaced with waterlogged hollows - depressions fill with water to form lakes
    vegetation is removed - decreases insulation and more subsidence
    formed when barrow pits are dug
    movement vehicles - heat emissions, turn land up - expose land to surface, melting, veg destroyed
  2. formation of alases - flat-floored, steep-sided depressions , widespread thawing of ground ice causes subsidence - can contain lakes
    several combine - alas valley
32
Q

key facts of the Amazon basin?

A

6 million km2 in south america
high average temperatures (25-30 degrees) no seasonal variation
high annual precipitation (>2000mm) seasonal variation but no dry season
biodiverse - 1/4 of medicines
390bn trees - 20% carbon in biomass

33
Q

how does geology affect the water cycle in the Amazon?

A

two contrasting geologies
large areas of impermeable - minimal storage/high run-off/limited throughflow/infiltration
permeable porous rock (limestone) in west

34
Q

how does temperature affect the water cycle in the Amazon?

A

high temperature = high evapotranspiration, strong convection = high humidity, thunderstorm clouds and intense precipitation
continuous cycle of water between land, trees and atmosphere

35
Q

how does relief affect the water cycle in the Amazon?

A

gentle, undulating relief helps store water in summer months causing water logging, more throughflow/run-off
high run-off in west - steep catchments

36
Q

how does geology affect the carbon cycle in the Amazon?

A

contrasting geologies
igneous/metamorphic little storage of carbon
west - some limestone - significant short-term stores

37
Q

how does temperature affect the carbon cycle in the Amazon?

A

high temperature and sunlight = more photosynthesis
high temperature, rainfall, sunlight stimulate NPP - 2500 g/m2/year, Amazonia 25% all NPP in terrestrial ecosystems
promotes rapid decomposition

38
Q

how does biomass affect the carbon cycle in Amazon?

A

main carbon store
absorbs 2.4bn tonnes carbon dioxide/year
60% trees, 40% roots/soil
global sink

39
Q

short term changes in the amazon basin to the water/carbon cycle?

A

More vegetation in summer months - more evapotranspiration, more interception, larger biomass store, less runoff
More vegetation in summer - more photosynthesis - less carbon in atmosphere

40
Q

short term changes in the tundra to the water and carbon cycle

A

In summer - active layer thaws and overland flow occurs - forms pools of water
In winter - very limited plant growth so low biomass store
Low temperatures mean slower decomposition

41
Q

long term changes in the tundra to the water and carbon cycles?

A

Temperatures rising over time - permafrost will melt and increase run-off and surface store
Increase in vegetation if temperatures are rising year on year - more photosynthesis

Warmer temps could encourage more life - more respiration?

42
Q

long term changes in the rainforest to the water and carbon cycle?

A

More co2 in atmosphere and then more evapotranspiration from plants - more likely to get acid rain - damaging/killing the rainforest - reduction in interception and erosion of soils - so more run-off
Enhanced greenhouse effect means that there is more carbon in the atmosphere and so temperatures rise

43
Q

human management strategies in the tundra?

A

Paragraph 1: Technology
Lateral drilling - better oil detection resources
Lowers impact of damage to ground with fewer insertion sites

Paragraph 2: Human adaptations
Infrastructure built gravel pads to protect permafrost from melting
Buildings and pipelines built on piles to allow cold air to circulate to stop melting and allows for migration of animals
Refrigerated supports on Trans-Alaskan pipeline - insulates

Paragraph 3: Changing legislation and attitudes
Change in emphasis from destruction to protection
Protests for protection
Other reasons too -
Melting - increasing subsidence and thermokarst - damages the buildings and infrastructure

44
Q

how does human activity affect the water cycle in the tundra?

A

Oil and gas exploitation has increased snow melting and so flooding becomes more likely
Extensive wetlands in summer - increase evaporation and disrupt drainage networks
Artificial lakes created by srip mining store water from creeks is extracted for local industry

45
Q

how does human activity affect the carbon cycle in the tundra?

A

Melting of permafrost - decreases carbon store, increases thickness of active layer - flows become more rapid = fast cycle speeds up
Heat is directly diffused by humans - melting, dust deposition which darkens snow surface - absorbs more sunlight. Removal of vegetation means less insulation
POSITIVE FEEDBACK - more CO2 and methane in atm = more melting
May be able to overcome with vegetation growth

46
Q

how does human activity affect the water cycle in the rainforest?

A

Deforestation increases ground temperatures but reduces cloud formation so can lead to permanent climate change
Reduction of water storage in trees, soils and geology and atmosphere
Increased run-off
Floods in porto velho - 68,000 evacuated and 60 killed

47
Q

How does human activity affect the carbon cycle in the rainforest?

A

Deforestation will reduce carbon in biomass and soil
Trees replaced by crops still reduce carbon store
Less decomposers in areas of deforestation so less carbon
Slowing of the cycle

48
Q

how do physical factors affect the water cycle in the tundra?

A

geology:
Low permeability - water cannot get in easily
Crystalline hard rocks only add to low permeability
temperature:
Low temperatures keep water as permafrost
Active layer thaws in summer - more overland flow etc.
Little evapotranspiration
relief:
Gentle, undulating relief helps to store water during summer

49
Q

how do physical factors affect the carbon cycle in the tundra

A

geology:
Most carbon locked in permafrost
Little impact on carbon
temperature:
Slow photosynthesis and respiration
Slow decomposition
biomass:
Loss of carbon in permafrost when it melts
Small store due to limited water and sunlight

50
Q

how do physical factors affect the water cycle in the rainforest?

A

geology:
Contrasting geologies
Large parts of Amazon catchment impermeable - minimal storage and high run-off
Porous limestone - store water and slow run-off
temperature:
More evapotranspiration in the summer
Strong convection
Water continually cycled
relief:
High run-off in steep catchment areas
Extensive gentle lowlands help store water
More throughflow

51
Q

how do physical factors affect the carbon cycle in the rainforest?

A

geology:
2 contrasting geologies
Little storage of carbon in igneous and metamorphic rock
Limestone outcrops are significant stores of carbon
temperature:
High temp and sun light means more photosynthesis
Promotes rapid decomposition
Biomass:
Main carbon store
Absorbs 2.4bn tons of carbon/year
60% trees 40% roots
Global sink

52
Q

medium term changes in Minnesota

A

Lobes of ice advance and abrade striations on rock
More steep hills in SE where less covered in ice
Ice sheet erosion means no spectacular landforms are formed unlike in valley glaciers

53
Q

short term changes in Minnesota

A

Warren river drained Lake Agassiz
Water overflowed and the drainage strategy helped form the mississippi river

54
Q

long term changes in Minnesota

A

Laurentide ice sheet is 1km thick and erodes mountains down 500-700m
Creates ellipsoidal basin - now filled with lakes

55
Q

what are the main depositional landforms in Minnesota and how were they formed?

A

Till from each lobe is different as it originates at different places
Wadena lobe
Red, sandy till
Formed Alexandria and Itasca moraine
Created drumlins in Otter, Wadena and Todd countries
Rainy and Superior lobe:
Till strewn across NE, mixture of basalt, granite, red sandstone, slate and greenstone
Des Moines lobe:
Tan colour - as rich in clay
Till more than 160m deep
Repeated periods of deposition lead to erosional landforms
Different till deposited creates different erosional landforms

56
Q

what are the main erosional landforms in Minnesota and how were they formed?

A

Ice sheet is 1 km thick
Mountains were worn down 500-700m
Creation of an ellipsoidal basin and thousands of lakes
More erosion on the weak shale in the NE
Less erosion in the SE - as not much ice cover
Erosional landforms created through deposits of till and moraine

57
Q

what pro-glacial lake is important and what does this do to the landscape?

A

Ice sheet damned natural water drainage in the area
Pro-glacial lakes formed largest lake - Lake Agassiz - 440 km 2
Glaciers blocked water drainage to the North
Lakes developed to the South
During melting - these lakes overflowed and created the Minnesota and River Valleys and fertile, rich soil now used for farming

58
Q

grande dixence key facts

A

Grande Dixence is a gravity dam that is located in the Val Des Dix in Southwest Switzerland
It has 350km2 of catchment and 35 glaciers providing seasonal melt
It was constructed in 1960 for hydroelectric power and stores 400 million m3 of water
Local moraine was used in the construction
Water flowed through dam - drives 4 power stations and powers 400,000 swiss homes
Summer glacial meltwater is stored and used to generate energy to meet the high winter demand

59
Q

how has Grande dixence changed water flow?

A

Reduced water flow in Borgne river
Leads to a higher concentration of pollutants at Les Haudere
More meltwater than river water
Meltwater more polluted - more melting

60
Q

how has Grande Dixence changed energy flows?

A

Water stored behind the dam creates lack of flow and loss of energy
This leads to deposition of sediment behind the dam
Deposited sediment gets flushed out periodically and creates high sediment concentrations at these times
More moraine
More glaciofluvial landforms - eskers and kames etc.

61
Q

how has Grande Dixence changed sediment flows?

A

Trapped sediment creates clearer water downstream
Clearer water will flow faster and erode land and landforms faster and more impactfully

Geography (8 decks)

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