Topic 4: Flashcards
1
Q
How are igneous rocks formed and what are there characterisitics?
A
Formed when molten rock from the mantle cools down and hardens, the rock forms crystals as it cools.
2
Q
How is sedimentary rock formed and what are its characteristics?
A
Formed when layers of sediement are compacted together until they become solid rock
3
Q
How is metamorphic rock formed and what are its characterisitcs?
A
Its formed when other forcks are changed by heat and pressure. The new rocks become harder and more compact
4
Q
What are the three maun ways that past tectonic processes have shaped the Uk landscape?
A
Active volcanoes
- land used to be much closer to a plate boundary than it is now. Active volcanoes forced magma through the earth’s crust which cooled to form igneous rocks.
Plate Collisions
- caused rocks to fold and uplift causing mountain ranges. (Uplands)
- the intense heat, pressure caused by plate collisions formed hard metamorphic rocks
Plate movements
- britain was in the tropics and partly underwater - carboniferous limestone formed in the warm shallow seas.
- youngest rocks in Uk are the chalks and clays, formed in shallow seas and swamps, form lowland landscapes as softer.
5
Q
What are the characteristics of Granite?
A
- very resistant and forms upland landscapes.
- has joints (cracks) which aren’t evenly spread - parts with joints wear down faster and ones with fewer wear down slower so stick out forming tors
-impermeable - creating moorlands - waterlogged land
6
Q
What are the characteristics of slate and schist?
A
- slate forms in layers creating weak planes in rock.
- generally hard and resistant to weathering but it is easily split into thin slabs
- schist - bigger crystals, splits easily
- both form rugged landscapes
- they are impermeable
7
Q
What are the characteristics of carboniferous limestone?
A
Rainwater eats away at limeston through carbonation weathering. Usually happens along joints.
- permeable, dry valleys, resurgent rivers (rivers opping out at surface).
8
Q
What are the characteristics of chalk and clay?
A
- Chalk is harder than clay.
- Forms escarpments (hills) in lowland and cliffs at coast.
- permeable - water flows through it and emerges as a spring where it meets impermeable rock.
- clay is very soft and easilt eroded.
-forms wide flay valleys in lowlands. - impermeable - water flows pver the surface (streams, rivers, lakes).
9
Q
Explain how back in the day the UK used to be covered in ice?
A
-Parts of the uk were covered in a massive ice sheet during the glacial periods.
- ice is powerful, so able to erode landscape, carving out U-shaped valleys
- glaciers deposited material as they melted.
10
Q
Name the 4 physical processes changing the landscape?
A
Weathering - weathering breakdown of rock into smaller pieces, mechanical, chemical or biological.
Erosion - wears rock away. Ice eroded landscape, rivers do aswell.
Post-glacial river processes - melting ice at end of glacial periods made rivers much bigger than normal with more power to erode the landscape. The ice also left distinctive landforms when melted.
Slope processes- including mass movements- rock falls, slides, slumps.
11
Q
Physical processes created distinctive upland landscapes…. like…..
A
U-SHAPED VALLEYS
- misfit rivers
-
12
Q
Physical processes create distinctive lowland landscapes….like……
A
Flooding forming flood plain
Dry valleys- no streams, formed during colder glacial periods eith freeze thaw weathering so when glaciers melted they had much more water in them.
13
Q
Humans have changed the landscape through agriculture….
A
- cleared forest for farming.
- hedgerows and walls have been put in for fields
- different landscapes are best for different types of farming: arable = flat land with good soil.
- dairy = warm and wet areas with large, grassy fields.
- sheep = takes place in harsh conditions in uplands. Sheep farming led to lack of trees as young trees are eaten or trampled on before they get a chance to mature
14
Q
Humans have changed the landscape through forestry..
A
- uk was covered in deciduous trees, very little left.
- coniferous (evergreen) forest planted for timber.
- straight line planted to not natural
- in some areas, deciduous is trying to be replantes to return areas to natural stae
15
Q
Humans have changed the landscape through settlement
A
- upland- because of hills it means that there is isolated homes. Less likely to have village and towns so you will not have a modern lifestyle because of holls.
-lowland- bridging points ovee rivers. Land was concreted over for roads, buildings. Some rivers diverted through underground channels
-some rivers striaghtened and had embankments. More urban than natural
16
Q
What is mechanical weathering and explain an example of it (salt weathering)?
A
Mechanical weathering is the breakdown of rock without changing its chemical composition.
Salt weathering:
- seawater gets into cracks in rock
- when the water evaporates, salt crystals form. As the salt crystals form they expand, which puts pressure on the rock.
- repeated evap of saltwater and the forming of salt crystals widens the cracks and causes the rock to break up.
17
Q
What is chemical weathering and give an example ( carbonation weathering):
A
Breakdown of rock by changing its chemical composition.
Carbonation weathering:
- seawater + rainwater have carbon dioxide dissolved in them, making them weak carbonic acids.
- carbonic acids react with rock that contains calcium carbonate.
18
Q
What is biological weathering?
A
Breakdown of rock by living things ….. plant roots grow into cracks pushing them apart
19
Q
What is mass movement?
A
The shifting of rocks and loose material down a slope. Causes coasts to retreat rapidly and more likely to happen if material is full of water and acts as a lubricant
20
Q
What are the three main types of mass movement? Explained
A
Slides - material shifts in straight line
Slumps - material shifts with a rotation
Rockfalls- material breaks up and falls down slope
21
Q
Describe the three processes of erosion and explain them?
A
Hydraulic action -
waves crash against rock and compress the air in the cracks. This puts pressure on the rock. Repeated compression widens cracks and makes bits of rock break off
Abrasion- eroded particles in the water scrape and rub against rock, removing small pieces.
Attrition - eroded particles in the water smash into each other and break into smaller peices, makes edges rounded.
22
Q
What will be formed at a concordant and discordant coastline and what is the lay out of them?
A
Discordant:
- hard soft hard soft,,,,,, at right angles to the ocean. Bays and headlands found at these coastlines
Concordant:
- parralel to coastline , fewer erosionalcland forms here.
Hard
Soft
Hard
Soft
23
Q
What do storms bring?
A
Destructive waves
24
Q
What does mild temperature bring?
A
Salt weatherung uncrease due to water evaporating quicker.
25
Describe the attributes of a destructive and constructive wave?
Constructive wave ---> big swash, small backwash, low, long frequency. Deposits material onca beach as bigger swash.
Destructive wave --> small wash, big backwash. High, steep frequency. Removes material from a beach aa bigger backwash
26
How are cracks, cabes, arches and stacks formed?
Waves crash into headland (mainly by hydraulic power and abrasion) causing the enlargment of CRACKS over time causing a CAVE to form.
Continued erosion deepens the cave until it breaks through the headland - forming an arch.
Erosion continues to wear away the rock supporting the ARCH, until it eventually collapses.
This forms a STACK - isolated rock that's separate from the headland
27
Explain how wave-cut platforms are formed?
-Waves cause erosion at front if cliff, forming wave-cut notch, which is enlarged as erosion continues.
- rock above notch becomes unstable and eventually collapses
- collapsed material washed away and new wave-cut notch sarts
- the process repeats so cliff retreats
- wave- cut platform is the platform left behing as the cliff retreats.
Look cgp top of page 51
28
How are spits formed and what are they?
-Spits form at sharp bends in the coastline.
- longshore drift transports sand and shingle past bend and deposits in sea.
-strong winds and waves can curve the end of soutl
- the sheltered area behind spit is protected from waves- lots of material accumulates there, so plants can grow there.
- can become a mud flat or salt marsh.
29
How are bars formed and what are they?
A bar is formed whenca spit joins two headlands together.
-the bar cuts off the bay between the headlands from the sea.
- this keans a lagoon can form behind the bar
30
What is longshore drift and how does it transport sediment along coasts?
Waves follow the direction of the prevailing wind.
- they usually hit the coast at an angle
- the swash carries material up the beach, in the same direction as the waves.
- the backwash then carries material down the beack at rught andgles, back towards the sea. Over time, material zigzags along coast.
See top of cgp 52
31
What are direct effects on the coastline and indirect effects?
Direct effects: are the immediate result of human activities on coastline.
Indirect effects: happen as a result of the direct effects. Building coastal defences in one place may increase erosion further along the coast.
32
What are human activities that have direct and indirect effects on the coast? (Agriculture)
-Algricultural land use has low economic value meaning left unprotected.
-clearing vegetation would expose cliff and soil leVing it vulnerable to weathering because vegetation help to bind the soil and stablise cliffs
33
What are human activities that have direct and indirect effects on the coast? (Coastal management)
-Some managment strategies alter sediment movement, which reduces the amount of protective beach material firther along the coast increasing erosion.
- coastal defences can also reduce erosion.
- this has a direct effect on the coast because ut prevents the landscaoe from changing.
34
What are human activities that have direct and indirect effects on the coast? (Development)
Coastal areas are popular to live.
- areas with more settlement will mean more protection as its higher value.
- lands better protected so positive direct impact.
- indirectly effects cliffs by causing restriction of sediment to the beach.
35
What are human activities that have direct and indirect effects on the coast? (Industry)
-Quarries expose large areas of rock, making them more vulnerable to chemical weathering.
-Taking gravel away from beaches for extraction removes proctection for cliffs.
36
Explain how climate change is increasing risk of coastal flooding (rising sea levels and storm frequency)?
Rising sea levels
- threats low-lyihg coastal areas
- higher tudes may be caused which removes largee material meaning less protection.
- it exposes ,ore of the coastline to erosion as beaches will become narrower as the sea will be able to move further inland.
Storm frequency:
- climate change causes increased storm frequency
- storms increase waves erosional power, more high energy waves meaning more material moved so less protection for cliffs. And more powerful waves mean hard rock is more vulnerable
37
What are the threats to people and the envrionmnet of climate change (coastal flooding)
Threats to people People:
X low lying coastal areas could flood, become impossible to inhabit.
X industries may shut because of damhe to building/eauipment.
X roads and railnetworks (infastructure) damaged.
THREATS TO ENVIRONMENT
X ecosystems damaged
X floodwater uproots trees
X conservation areas damaged
38
How can managment strategies be sustainable?
They must manage the cost in proportion to the benefits. Is it worth doing, is it long term, how much work will be needed.
39
Describe the two hard engineering coastal defences and the benefits and costs of them. (Groynes..
SEA WALL - ( a wall made of hard material like concrete thst reflects waves back to sea) - prevents erosin + acts as barrier.
- it creates a strong backwash, which erodes under the wall. They are expensive to build/maintain
GROYNES - (wooden or stone fences that are built at right angles go the coast. They trap material transported by longshore drift) - creates wider beach which slow the waves. Giving greater proctection from flooding/erosion. Cheap.
- it starves beaches further down coast of sand making them narrower which dont protect cosst as well. Leading to erosion/floods.
40
Describe the 3 soft engineering coastal managments and the benefits and costs? Slope stabilisation..........
BEACH REPLENISHMENT ( adding sand to beach) - creates wider beach (slows waves), more protection from flooding/erosion as stuff to protect cliffs.
- takes material from seabed can kill organisms. Very expensive
STRATEGIC RELIGNMENT (removing defences and allowing the land behind it to flood) - land can become marshland - creating new habitats, flooding/ erosion are recued behind marhsland.
- people disagree over what land is allowed to flood (farmland being flooded would affect livelihood of farmers.
SLOPE STABILISATION ( reinforcing slope with concrete naiks and covering with metal netting. - -Prevents mass movement by increasing strength of slope.
- Very expensive, very difficult to install sometimes.
41
What is integrated coastal zone management?
Is an approach thst aims to protect the coast while taking everyone's interests into account.
42
What is hard and soft engineering?
HARD engineering is man- made structures built to control the flow of the sea and reduce flooding and erosion.
SOFT engineering schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion.
43
Explain how the interaction of physical processes is causing change to the Holderness coast?
- most of cliffs are boulder clay (easily eroded). Causing cliffs to collapse when wet. (Slump)
- beaches are narrow which means they don't provide enough protection for cliffs
- Holderness faces prevailing wind direction bringing waves from the Norwegian sea. Waves increase in power over long distances, so the coast is battered by highly erosional waves
- eroded material moved further along the coast by longshore drift instead of staying in the place it came from exposes a new area of cliff to erosion causing coastline to retreat.
- busier areas have more hard engineering strategies in place
44
Explain how human processes have caused problems further down the Holderness coast?
Groynes cause narrow beaches further down coast, increases erosion further down coast.
In some areas, retreat is increasing because less new material is being added
Material produced from erosion of Holderness is normally transported down the coast.
Reducing amount of material that's eroded and transported south increases the risk of flooding south because less material to slow the floodwater down.
45
Describe the features of the upper, lower and middle course?
UPPER - steep, V-shaped valley, steep sides, narrow, shallow channel.
LOWER- gentle, very wide, almost flat valley, very wide, deep channel
MIDDLE- medium, gently sloping valley sides. wider, deeper channel
46
What is the course of a river?
The path of a river as it flows downhill
47
What is the upper course?
Closest to the source of the river
48
What is the lower course?
Closest to the mouth of river
49
Middle course?
Middle path of a river
50
What is the long profile?
Shows you how the gradient (steepness) changes over the different courses.
51
What is the cross profile?
Shows you what a cross-section of a river looks like
52
What is vertical erosion?
Deepens river valley (V-shaped). Dminant in Upper course of river.
53
What is lateral erosion?
This widens river valley during the formation of meanders.
54
Describe the characteristics of the middle course of the river EDEN?
- made of sandstone (soft, less resistant so easily eroded meaning river valley = wider due to more lateral erosion).
- as river channel also becomes wider and deeper. Discharge increases as more streams join the main river.
- river's sediment load is made up of smaller and more rounded rocks than it was in upper course.
55
Describe the characteristics of the Upper course of the river EDEN?
- hard, resistant rock.
- steep sided valley due to vertical erosion.
- the channel has a steep gradient.
- river channel is narrow and shallow, meaning discharge is low.
- velocity is low due to friction from the rough channel sides and bed.
- the river carries large, angular stones.
56
Describe the characteristics of the Lower course of the river EDEN?
-Valley is very wide and flat.
- only a few metres above sea level.
- high velocity because there's very little friction from the channel's smooth sides.
- very large discharge because rivers join it.
- river channel is very wide and deep
- material is fine and well rounded carried by the river.
57
What are thenfour processes of erosion decribed?
HYDRAULIC ACTION- the force of the water breaks rock particles away from the river channel.
ABRASION: eroded rocks picked up by the river scrape and rub against the channel, wearing it away. Most erosion happens by abrasion.
ATTRITION - eroded rocks picked up by the river smash into each other and break into gmaller fragments. Their edges also get rounded off as they rub together. The further material travels, the more groded It gets - attrition causes particle size to decrease between a river's source and its mouth.
SOLUTION: river water dissolves some types of rock, e.g. chalk and limestone.
58
Decribe freeze-thaw weathering?
Happens when temp alternates between above/below 0°. Water freezes in cracks, expands = pressure. When it thaws it releases pressure creating more cracks
59
What is traction?
Large particles like boulders are pushed along the river bed by the force of the water
60
What is suspension?
Small particles like slit and clay are carried along by the water
61
What is saltation?
Pebble- sized particles are bounced along the river bed by the force of the water
62
What is solution?
Soluble materials dissolve in the water and are carried along
63
Deposition?
When a river drops eroded material it's transporting
64
Why do rivers slow down and deposit material?
The volume of water falls.
The amount of eroded material in the water increases.
The water is shallower
The river reaches its mouth
65
Describe interlocking spurs?
Upper course of river = verticsl eorion
Creates V-shaped
- rivers aren't strong enough to erode laterally they have to wind around the hills. Creating hillsides that interlock.
66
Describe OX-bow lakes? Cgp 63
Current is faster on outside of bend because river is deeper.
More erosion takes place on outside forming river cliffs
67
Describe Meanders? Cgp 63
- erosion causes outside bends to get closer.
- until there's only a bit of land left.
- river breaks through, during flood.
- river flows along shortest course.
- deposition eventually cuts off meander forming Ox-bow lake
68
Waterfalls and gorges are found in the upper course of a river. Describe how they form....
- waterfalls form when river meets hard rock then soft rock.
- softer rock eroded quicker than harder rock creating a 'step' in river.
- as water goes over step it erodes softer rock even more,
- steep drop is eventually created. (Waterfall)
- hard rock eventually undercut. Becoming unsupported and collapsing.
- collapsed rock is swirled around at bottom where they erode softer rock by abrasion - creatingnplunge pool
- more undercutting = more collapsing. Watefall retreats (gorge formed).
69
What are hydrographs?
Show changes in river discharge around the time of a storm
70
River discharge
Volume of water that flows in a river per second
71
Peak discharge
Highest discharge in period of time being looked at
72
Lag time
Delay between peak rainfall and peak discharge.
73
Rising limb
Increase in river discharge as rainwater flows in river
74
Falling limb
Decrease in river discharge as river returns to normal level
75
Describe the physicsl factors that affect lag time, discharge and shape of the hydrograph
Geology: water can filtrate into impermeable rocks, so more runoff
SOIL TYPE: more impermeable soil can't absorb so increases runoff.
SLOPE: steeper the slope, less infiltration and the higher runoff
DRAINAGE BASIN TYPE: circular basins - shorter lag time, higher discharge compared to narrow ones.
ANTECEDENT CONDITIONS: previously wet or cold weather increases runoff as wayer csn't filtrate through frozen soil
76
Describe the human factors that affect lag time, discharge and shape of the hydrograph
Urbanisation - water can't infiltrate through concrete.
Deforestation - trees take up water. Without them it increases surfsce runoff.
77
Explain why the river Eden is prone to flooding (human factors)
- large, built up. Lots of development on flood plain so its ability to absorb gets worse.
-natural woodland cleared for building so increase surface runoff.
- parts have been drained to better suit farming. Meaning water flows rapidly in drainage ditches.
78
Explain why the river Eden is prone to flooding (physical factors)
- it faces south- westerly winds - mild/wet climate.
- intense rainfall there - floodingl
- bordered by hard rock, impermeable so more surface runoff.
- snow is common so when it melts lots of water in a short space of time in the river
79
The risk of flooding is increasing in the Uk because of increased storm frequency and land use changes....
INCREASED STORM FREQUENCY
- could be because of climate change
- more intense rainfall- flooding
- more periods of wet mean soil = saturated = more flooding.
LAND USE CHANGES
- pop growth - expansion of urban areas- impermeable surfaces - more funoff.
- removing vegetstion for urban growth= water flows down stream wuick as is was stored in it.
- more people living on flood plain and if defences fail = flooding.
80
Explain how flooding threatens people and the environment:
People:
- Killed or injured
- roads, bridges destroyed.
- floodwayer contaminstes sewage = disease
-Possessions can be lost
- people made homeless
- businesses shut down
ENVIRONMENT:
- floodwter contaminates sewage and rubbish polites rivers, damaging wild life.
- farmland ruined by sediment deposited after flood
- river banks eroded, causing huge changesnto river landscape.
- force of floodwater uproots trees and plants, could die, increase flood for future as more surfsce run off as less vegetation
81
What are flood plains?
Flood plains are wide valley floors on either side of a river which occasionally get flooded.
82
What happens when a river floods on a flood plain?
The water slows down and deposits the eroded material that it's transporting. This builds up the flood plain.
Meanders migrate across flood plain, making it wider.
Meanders also migrate downstream, flattening out the valley floor.
The deposition that happens on the slip-off slopes of meanders also builds up the flood plain.
83
What are levees?
Levees are natural embankments along the edges of a river channel.
84
How are levees made during a flood?
Diring a flood, eroded material is deposited over the whole flood plain.
The heaviest material is deposited closest to the rivee channel, because it grts dropped first when the river slows down.
Over time, the deposited material builds up, creating levees along the edges of the channel.
85
What are deltas?
Deltas are low-lying areas where a river meets the sea or a lake
86
How do deltas form?
- rivers are forced to slow down when they meet the sea or a lake.
- this causes them to deposit the material that they're carrying
- if the sea doesn't wash away the material it builds up and the channel gets blocked.
- this forces the channel to split up into lots of smaller rivers called DITRIBUTARIES.
- the material builds up so much that low-lying areas of land called deltas are formes
87
Describe how contour lines give the direction a river flows
They tell you the height of the land by the numbers marked on them, and the steepness of the land by how close together they are.
Rivers cant flow up hill. Rivers flow from hgihee contour lines to lower ones.
88
Describe what evidence of river landforms looks like on a map to do with the upper course.
Waterfalls are often marked on maps, the symbol for a cliff (black/blocky lines) and close contour lines can also be evidence for waterfalls
89
Describe what evidence of river landforms looks like on a map to do with the lower course?
Look in cgp 65 bottom of page
90
Why does lag time happen?
Because most rainwater doesn't land directly in the river channel - there's a delay as rainwater gets to the channel. It gets there by flowing quickly overland, or by soaking into the ground and flowing slowly underground
91
Describe how river landscapes and sediment load are influenced by climate...
CLIMATE:
- rivers in wetter climates have higher discharge as more watee entering river.
- higher discharge increases rate of erosion - if rivee has high volume of water, more power to erode. Adding more material to river load.
- shapes landscape (V-shaped valleys) in upper course and a wide flat flood plain in lower course
- transportstion increases when high discharge as river has mor energy to carry material.
- weathering increases river's sediment load and csn affect shape of landscape.
92
Describe how river landscapes and sediment load are influenced by geology....
- rivers flowing through areas of hard rock have a slower rate of erosion because hard rocks are more resistant. Meaning rivee has lower sediment load.
- areas with softer rocks will experience more erosion- this adds more material to the river's sediment load.
- landscapes with more resistant rocks tend to have steeper valley sides. Landscapes with less resistsnt rocks have gentle sloping valley sides.
- waterfalls form where there is a layer of hard rock on top of softer rock.
Interlocking spurs form where softer rock is eroded first, leaving areas of harder rock sticking out.
93
Describe how river landscapes and sediment load are influenced by slope processes....
-Vertical erosion by rivers makes valley sides steeper, increasing the movement of material down the slopes.
- mass movement
- soil creep is when soil particles move down a slope because of gravity. It's caused by the expansion and contraction of the soil. Water adds weight to the soil and makes it expand - causes it to move down slope. When the soil dries out, it contracts. Adds fine material to waters load.
94
Flood walls description
Artificial barries designtaed to raising the height of the river banks to hold more water.
95
Embankments descriptions
High banks built on or near riverbanks.
96
Flood barriers descriptions
Floodgates builts near the river path to prevent a storm surge or spring tide from flooding the area behind the barrier.
97
Demountable flood barriers descriptions.....
A temporary structure that is only installed when needed
98
Flood plain retention description:
Strategies to maintain and restore the river's original flood plain
99
Rivee restoration description
Using a variety ofnstrategies to restore the river's original source
100
Advantages and disadvantages of Embankments
AD:
- stop water from spreading into area and flood, can be earth or grass banks (blend in)
- cheaper than others.
DIS:
- water may go over the top and get trapped behind.
- can burst due high pressure, even greater damage
101
Ads and dis's of flood walls
Ads:
- prevents water from spreading into areas that would have a high impact (houses).
DIS:
- expensive
- water flows quickly but causes flooding downstream.
- They do not look natural, spoils view
102
Demountable flood barriers ads and dis's
ADS:
- put in when flood is forecast, then taken down after. Doesn't interupt view permanentaly.
DIS:
- only used in specific locations that it has been set to be deployed.
- There is risk of defence not being installed in time.
103
Flood barriers ads, dis's
ADS:
- gates can be closed when high tide or surge is forecast. Able to protect large areas from storm surge conditions.
DIS:
- construction costs are high and they need regular maintanence
104
Flood retention ads and dis's
ADS:
- allowing rivers to flood slows flood water down and recovers rivers nstural sedimentation process.
- This helps to restore soil structure + more efficient at storing water.
DIS'S:
- allowing land to flood may mean a change of land use, formexample, a change in farmland
105
RIVEE RESTORATION Ads and dis's
ADS:
- restores rivers to natural course by taking embankments away and restoring meanders, allowing rivers to flood but does slow them down.
- natural rivers look better in environment
