UK's Physical Landscape Flashcards
1
Q
What are igneous rocks?
A
Rocks created by immense heat and magma that cools once leaving a volcano- most resistant form of rock (granite and basalt)
2
Q
What are metamorphic rocks?
A
Rocks transformed from either sedimentary or igneous rocks through immense heat and pressure. (Slate and marble)
3
Q
What are sedimentary rocks?
A
Rocks that’s are created by layers of sediment compacting together over 1000s of years (clay, sandstone, limestone)
4
Q
What is freeze thaw weathering (mechanical)?
A
This involves water continually seeping into cracks, freezing as it gets colder, expanding and eventually breaking apart. This occurs when rocks are porous or permeable.
5
Q
What is biological weathering?
A
When plant roots can get into small cracks in rocks. As these roots grow the cracks get larger and the rock breaks away
6
Q
What is tectonic uplift?
A
When the earth’s crust drifts and lifts due to convection currents. This forces land upwards to form ridges and fault scarps (e.g. gigglewick scar)
7
Q
What is scarp and vale topography
A
Caused by rain dislodging soil particles. More resistant rocks form steep escarpments which stick out and softer clays are eroded more easily so form vales between two scarps
8
Q
How has glaciation formed U shaped valleys?
A
Glaciers form in v shaped valleys and move slowly down the valley they erode through plucking and abrasion - making it deeper and wider. Glaciers will then retreat widening the valley even more
9
Q
How have people changed the landscape through agriculture, forestry and settlements?
A
Agriculture-different areas are suited to certain types of farming (sheeps in upland areas and arable farming in lowland areas)
Forestry-planting, managing and caring for forests for different purposes such as conservation, deforestation and industrialisation.
Settlements -often concentrated in areas where landscapes are advantageous (harbours, towns)
10
Q
What is the geology of the UKs north and south?
A
Upland landscapes = u-shaped valleys, mountains streams
Lowland landscapes = rivers, flatter land
11
Q
What is a Concordant coastline?
A
When rock is parallel to to coastlines and often made up of the same rock
12
Q
What are discordant coastlines?
A
When rocks are perpendicular to the coastline and rock types often alternate in layers (formations are usually headlands and bays)
13
Q
How are headlands and bays formed at discontent coastlines?
A
- less resistant rock is eroded away quicker forming bays that grow in size as this rock is continually eroded backwards
- more resistant rock is harder and slower to erode so forms headlands that stick out.
- wave action is now concentrated on the headlands so they often form stacks/stumps and deposition of sediment to form beaches
14
Q
How are coves and wave cut platforms formed at Concordant coastlines?
A
- rock is parallel so is continually eroded backwards in all directions
- wave cut notches are also created as constant wave action is concentrated towards the bottom of the cliff causing undercutting. Above rock then collapses and the cliff front retreats inwards leaving a wave cut platform.
15
Q
How are stacks and stumps created?
A
- faults and joints appear in headlands but high energy destructive wave energy is now concentrated eroding the headland more
- hydronic action and abrasion widens the faults even more and cracks turn to caves to then be eroded through into arches
- they then collapse to form stacks and stumps
16
Q
What are the 4 types of erosion?
A
Abrasion=bits of rock and sand in waves grinding down cliffs
Attrition = waves smash rocks onto the shore and they break it become smaller
Solution= acids contained in sea water will dissolve rock like chalk
Hydrolic action = air becomes trapped in faults and joints and when waves hit the air is compressed weakening the cliff
17
Q
How are waves created?
A
- wind blows over the surface of the sea creating friction, this provides a swell in the water
- energy in the wind causes water particles to rotate in the swell moving the wave forward
- wave breaks as top moves faster than the base due to seabed friction
18
Q
What influences how strong waves are?
A
how long the wind has been blowing for, strength of the wind, the fetch of the wave (how far has it travelled)
19
Q
What are constructive waves?
A
Less powerful waves that have a short fetch so have less energy. Their swash is stronger than their backwash
20
Q
What are destructive waves?
A
Strong waves due to long fetches which build up lots of energy. They have a stronger backwash than swash and are plunging breakers
21
Q
What is swash and backwash?
A
Swash-water is washed up the beach as waves break at 45°
Backwash- water runs back down the beach after the wave has broken (90°)
22
Q
What are sub Ariel processes?
A
Those that occur on the cliff face as oppose to the cliff foot and are influenced by weather and climate
E.g. weathering and mass movement
23
Q
What is cliff slumping?
A
- precipitation infiltrates and percolates through upper cliff soft rock causing it to become saturated and unstable
- it then reaches impermeable hard rock so water builds up
- at a slip plane, the cliff then slumps and is debris is carried away by wave actions
24
Q
What is Chemical weathering?
A
When rain or substances are slightly acidic so rock is eroded. For example this causes limestone to dissolve
25
What is longshore drift?
- The prevailing wind comes from a south western direction so pushes sediment up the beach at a 45° angle (swash)
- gravity then pulls sediment down the back at a 90° angle
- this transports sediment across the beach from west to east
26
What are the 4 transportation processes?
Saltation-when a rock knock into eachother causing it to bounce
Suspension -fine sediment is suspended in water
Traction - when a rock rolls due to the force of the water, making it smaller through friction
Solution - dissolved load in the river
27
Where do sandy beaches occur and how?
Tend to form in bays as they are low energy environments as they are sheltered from high water energy. This allowed deposition by constructive waves
28
Where do pebbled beaches occur and how?
Tend to form in areas with eroding cliffs that are exposed to high energy wave action. Pebbles are often rounded and smoothed by wave action (these beaches are steeper than sandy ones)
29
How does a spit form?
Spits are fingers of sand across and estuary
- sediment is moved along the beach by LSD and when there is a change in the direction of coastline like an estuary the transported material is deposited offshore
- stretches across the estuary but is limited in size due to its velocity of currents and deep waters
- as spit grows sheltered waters appear behind the spit causing finer sediment to settle and fill in the area forming salt marshes
- spit becomes curved due to current and secondary wind direction
30
What might spits form?
- If spits grow a lot they may form a hook if the wind changes direction
- in slack water behind the spit more deposition takes place and may form a salt marsh and eventually new land
31
Why won’t a spit form a bar across an estuary?
As the rivers current stops deposition due to its velocity
32
How is a bar formed?
Bars form the same way as spits through LSD but form across a bay joining up two headlands and creating a lagoon behind the bar as water becomes dammed
33
How are tomobolos formed?
When there is a change in the shape of a headland a spit grows out from the mainland and joins to another island
34
How have humans impacted the coast?
- industry and infrastructure is of high value so often needs protection from erosion e.g. sea walls. Yet this prevents natural costal change
- tourism increases need for beach protection and more pollution
- dredging sediment from seabed construction
- farmland often isn’t protected as its value is too low -less biodiversity
35
Why are costal regions at risk?
- Thermal expansion provides more energy for sea water particles
- destructive waves are more violent - storm surges
- melting of polar ice sheets so sea levels are rising
- post glacial rebound
- land subsidence means land is sinking due to tectonic activity and the weight of infrastructure
36
What us post glacial rebound?
- Ice from glacial periods put pressure on land so it sinks slightly
- as it melts it springs back up causing connecting areas of land to sink and flood with melted ice
- this is isotonic change (change in height of land )
37
What threats to people and the environment face due to coastal issues?
- coastal infrastructure being destroyed means more pollution, displaced people and huge economic issues
- flooding may lead to deaths and injuries
- biodiversity will decrease
38
What are the four shoreline management options?
Hold the line - stop more erosion happening by protecting the current coastline
Advance the line - reclaim land and protect it
Managed retreat- work with nature to allow gradual erosion using natural ecosystems
Do nothing - allow erosion to happen
39
Why is shoreline management important?
As it means we are dealing with the coast in a holistic way. This is called integrated costal zone management (ICZM)
40
What are groynes and their drawbacks (hard engineering)?
Wooden or rock structures that are positioned along the beach at right angles to the land. They trap sediment moved by LSD to build up the coast
- can starve areas down drift of sediment
- wood rots but rocks are more expensive
41
What are revetments and their drawbacks (hard engineering)?
Wooden or rock ramps that line the coast that absorb wave energy and air spaces allows the backwash of the wave to drain away
-wood rots but rocks are more expensive
+look nice
42
What are gabions and their drawbacks (hard engineering)?
Cages of small rocks, stacked along the coast to make a wall and to absorb wave energy
-lightweight so can be moved by storms and don’t look very nice
+fairly cheap
43
What is riprap and its drawbacks (hard engineering)?
Large boulders positioned along the coastline to absorb wave energy
-expensive if including transport costs from a quarry
+ natural looking and relatively cheap
44
What is a sea wall and to drawbacks (hard engineering)?
Concrete barrier that is recurred to reflect the waves and their energy
-most expensive and technical to build
-not very aesthetically pleasing
+one of the most effective methods
45
What is beach nourishment and it’s drawbacks (soft engineering)?
Sand is dredged from the seabed offshore and them pumped onto the beach. The restored beach is a natural barrier and absorbs wave energy
- LSD and destructive waves can remove sand so needs to be redone every few years
- extremely expensive
46
What problems does Barton on sea/Christchurch bay face?
- due to groynes at Bournemouth BOS is now starved of beach material supply and wave actions is concentrated directly on the cliff face
- slumping
- land property is not that profitable
- faces destructive waves and prevailing winds
47
How have rock groynes helped BOS?
- tackles LSD and cliff foot erosion
- replaced wooden groynes and are therefore more durable
- not pretty and costs £2000 per mete
48
How has rip rap helped BOS?
- replaces lost beach next to groynes
- absorbs wave energy and protects cliffs
- looks natural and could promote marine ecosystems
49
How has cliff stabilisation effected BOS?
- cliff drainage to drain the cliff of excess water to prevent slumping
- plastic pipes instead of metal pipes as can rust and break
- cliff regrading involves changing the angle of the cliff to increase stability yet involves a lot of work and machinery
- very expensive
50
What is a cost benefit analysis (CBA)?
Takes into consideration the value of the land and how much there is to loose and then works out what can be spent to protect it
- the higher the value of land the greater the money that can be justified to protect it
- CBA = value of property / cost of defences
51
What is the energy of upper course rivers life?
Energy and velocity is low as it is shallow and narrow. This means there is a low volume of water so it is inefficient as there is a lot of friction which reduces its velocity (low load, high bedload)
52
What are Middle course rivers like?
Rivers become wider, deeper and flatter. This means there is less friction so efficiency and velocity increases. More suspension and solution due to higher erosion levels so more sediment
53
What are lower course rivers like?
Almost flat land that is wide and deep. This makes it very fast flowing so very efficient. Load is high so there is suspended sediment
54
Why does load increase as you travel down the river and water becomes less clear?
Because the river becomes deeper. This means there is less friction so velocity increases and therefore so does erosion levels. There is now also more suspended sediment so water isn’t as clear.
55
How do you increase river efficiency?
- lower down the course so rivers are deeper and there is less friction
- increase the gradient so there is a higher velocity
56
How can climate effect load and river efficiency (more so in the winter)?
- heavy rainfall increases river velocity and volume so there is more erosion
- wind may also transport load into the river
- freeze thaw weathering on river sides may cause rocks to fall in and to be eroded
57
What is deposition and why does it occur?
where material being transported by a river is deposited. Deposition occurs when a river loses energy. This can be when a river enters a shallow area or where it meets another body of water.
58
What is river discharge?
The volume of water flowing through a river channel at a given point and time
59
What are v chapped valleys in rivers (upper course)?
- the river sides aren’t straight as a result of sub Ariel processes
- high turbulence causes the rough angular particles to be scraped along the river bed causing intense downwards vertical erosion
60
What are interlocking spurs?
Fingers of land that protrude into the river and restrict the view down the valley(upper course)
- formed when the river makes diversions around more resistant rocks
- helps with the formations of meanders
61
What are meanders?
Bends in the rivers lower/middle course. The river uses up surplus energy by swinging one way and the other causing lateral erosion of the outside of bends and deposition on the inside
62
Compare the inside and outside of a meander bend?
- On the outside, there is a faster velocity as there is a larger volume of water and it is deeper. Abrasion and suspension tend to form river cliffs through undercutting
- on the inside, velocity is a lot slower and it is very shallow so there is less movement. This forms slip of slopes where sand is deposited
63
What is an oxbow lake (lower/middle course)?
- meanders become so large and tight they are nearly touching
- in times of flood, fast flowing water erodes a more efficient channel so breaks through the land between the meander
- alluvium is them deposited between the new channel and meander, cutting the meander off meaning it will dry up
64
How do waterfalls form?
- when there is resistant rock on top of les resistant rock
- less resistant rock is eroded quickly by hydronic action and abrasion and the more resistant rock is undercut to create an overhang
- this continues to form and plunge pool
- overhang then collapses and the sediment erodes the plunge pool more
- the waterfall retreats upstream and leaves a sleet sides gorge
65
What do humans use waterfall for?
Hydroelectric power as the force of the water can turn a turbine
-they are usually upper course
66
What are floodplains?
The wide, flat areas of land either side of a river that are liable to flooding
67
What are levees and how are they formed?
- an embankment built up either side of a river after flooding
- when a river overflows it inundates the surrounding floodplain
- there is more friction so a lower efficiency resulting in deposition
- the largest sediment is deposited next to the channel as it is the heaviest so a levee builds up
68
What are deltas and how are they formed?
- fan shaped landforms at the mouth of a river
- created when velocity decreases as the river reaches the sea so deposition occurs to form many channels (distributaries)
- they are common when rivers have a high load
69
In what ways are deltas useful and difficult for humans?
- creates fertile land which is god for agricultural purposes
- provides boat lanes for fishing and exports
- yet difficult to build on as land is saturated and prone to flooding
70
On the hydrological cycle, what will increase the chance of flooding?
Any factors that encourage runoff and reduce infiltration or interception as the river will fill up quicker
71
What do Hydrographs show?
How fast rainfall gets to the river
72
What are some attributes of a flashy Hydrograph ( opposite for subdued Hydrograph)?
- Lag time is short
- peak discharge is high
- rising limb is steep
- rainfall reaches the river quickly
- more likely to cause flooding
73
What are some features of a Hydrograph?
- rainfall shown in mm as a bar graph
- discharge in Cumecs as a line graph
- rising limb is the rising levels of flood water in the river
- peak flow is the maximum discharge in the river
- recession limb is the falling flood water in the river
- basin lag time is the difference between peak rainfall and peak discharge
74
Where is the river Wey located?
- in Woking , county of Surrey in south east England. West of Kingston and north of Guildford
- it’s sources are at Alton and haslemere
- flows through Godalming and Guildford to its confluence with the themes at Weybridge
- flooded in January 2014
75
He has urbanisation caused flooding in Woking?
Urbanisation results in a quicker surface run off as less water is infiltrating and percolating into the soil due to impermeable surfaces
This is because there is an increases need for housing with less green belt land
76
How has global climate change leads to flooding in Woking?
Increase in global mean temperatures and changing weather patterns. There is a higher intensity of rainfall in a concentrated time so there will be a surge in the amount of surface run off and discharge
77
How has the jet stream moving led to flooding in Woking?
Brings low pressure systems (depressions) to the UK
- in winter 2014 the jet stream was further south than usual so more storms in the uk
- because the rain kept coming the antecedent conditions were a main cause of the flood
78
How has deforestation led to flooding in Woking?
Trees slow down the course of water due to interception and transpiration. Due to ongoing urbanisation, Woking has made a 10 year plan to remove 100 acres of woodland
-it has also occurred along the A3 which impacts Woking as it is part of the Hoe Stream’s catchment area.
79
What factors increase flood chances?
- Urbanisation means there is less permeable surfaces so there is more surface run off
- antecedent conditions(previous rainfalls) means the ground is saturated so infiltration can’t occur
- colder winters so frozen grounds which are impermeable
- flat land means water has no where to flow
80
What factors decrease flood risks?
- Seasons- in summer if there is less rainfall and more evaporation as well as better growing conditions for crops to increase transpiration and interception
- forested rural areas have more trees to increase interception and transpiration and decrease surface run off.
- permeable surfaces allow percolation sand infiltration
- mountain environments or steep terrains means water can flow away
- dry soil increase absorption
81
What techniques should be taken to mitigate flooding risks?
- flood risk map and zoning
- levees
- dredging
- house barriers/sandbags
82
What order should mitigation techniques be taken in?
- make a catchment area for each drainage basin to see which management is suitable for different places
- work out a chance of a flood occurring
- set up flood warning systems
- asses solutions which are economically viable and environmentally friendly
- give home owners advice to reduce impact
83
What is through flow, groundwater flow and surface run off?
Surface run off= flow of water over ground surface
Ground water flow = flow of water through the rocks
Through flow = the flow of water through the soil
84
Differences in upland and lowland climate?
- up,ands are more susceptible to rainy weather due to high relief and mountainous forces
- more snow up north due to cooler temps
- warmer temps down south as costal regions retain more heat
85
What is salt weathering?
The seawater gets into cracks in rocks
- when the water evaporates, salt crystals form which expand putting pressure on the rock
- this repeated processes widens the cracks and causes the rock to break up
86
Flood plain retention
Buildings not build on the flood plain as this provides an area for floodwater to go
- Conserve ecosystems living on the flood plain
- means buildings are built on more stable ground restricting economic development in this area
87
What is soil creep?
Particles of soil slide down the valley due to gravity which can be further pressurised through high rainfall leading to lots of fine sediment being added to the river load
88
River restoration
The removal of hard engineering techniques in order to restore a river and the surrounding area to its natural state
- often involves the removal of concrete that formed an artificial channel due to the high costs of maintaining it
- benefits local ecosystem as surrounding areas are often removed of human influence allowing natural wildlife corridors to be reinstated
- relocation expensive but long term cheaper
89
What are hard engineering techniques for rivers?
Flood wall are build up barriers
-blocks views so isn’t aesthetically pleasing
Demountable flood barriers
-put up in the events of emergency and don’t destroy surround environment but if not put up quick enough have little effect
