GCSE 1.C - Physical Landscapes in the UK Flashcards
How are waves formed?
Wind blowing over the sea, causing friction to create ripples that form waves
What is fetch and how does it affect the strength of the wave?
The distance the wind has to blow over the water, the lnger the fetch the more powerfull the wave
How are tsunamis formed?
when earthquakes or volcanic eruptions shake the seabed
What happens when waves reach the coast?
the seabed interupts the circular movement of water. As the water becomes shallower, the corcular motion becomes eliptical. This causes the crest of the wave to rise up and eventually collapse on the beach
Constructive waves
- low wave height
- Far wave crests
- Gently sloping wave front
- Spilling forwards ( strong swash, weak backwash )
- deposit sediment on beach
gentle beach
Destructive waves
- High wave height
- Close wave crests
- steep wave front
- Plunging downwards ( strong backwash, weak swash)
- removes sediment on beach
steep beach
What are coasts?
Where the land meets the sea
Fetch
The distance the wind blows over the water
Longer fetch = more powerfull wave
How do waves form
Wind blows over the sea
- Wind against water cause friction causing ripples
- The surface water is pushed in the direction of the wind
- a wave is formed!
How are tsunamis formed?
when earthquakes or volcanic eruptions shake the seabed
Why dont waves fully form in the sea?
There is little horizontal movement of water when in the sea. Only when waves approach the shors is there forward movement of water as waves break up and surge towards the beach.
What is the first stage of a wave breaking?
Circular orbit in open water
What is the second stage of a wave breaking?
Friction with the seabed as the wave starts to get into shallower water distorts the circular motion
What is the 3rd stage of a wave breaking?
The top of the wave moves faster, creating an icreasingly eliptical orbit.
What is the 4th stage of a wave breaking?
The wave begins to break
How does the motion of the wave relate to the depth of the seabed?
As the water becomes shallower, the circular motion becomes eliptical
What is mechanical weathering?
(physical weathering)
The disintegration of rocks.
What is chemical weathering?
This weathering is caused by chemical changes. rainwater is slightly acidic and slowly dissolves some rocks
What is biological weathering?
Weathering due to the actons of flora and fauna. Plant roots grow in cracks in the rocks. Animals such as rabbits burrow into weak rocks such as sands.
D
Describe the process of Freeze-thaw
Mechanical
- Water collects in cracks or pores in the rock.
- At night the water freezes and expands, making the cracks bigger
- When the water melts it will seep deeper into theses cracks and repeat this process.
What is Scree?
Piles of rock fragments
Describe the process of salt weathering
Mechanical
When seawater evaporates it leaves behind salt crystals.
In cracks and holes these salt crystals grow and expand
This puts pressure in the rocks and makes them crack or flake.
Describe the process of carbonation weathering
Chemical
Rainwater absorbs CO2 from the air and becomes slightly acidic
Contact with alkaline rocks such as chalk and limestone produces a chemical reaction causing the rocks to slowly dissolve
What is mass movement?
The downward movement of material under the influence of gravity.
What are the main 3 types of mass movement?
Sliding
Slumping
Rock falls
What is the process of sliding?
Large blocks of rock slide down a cliff face as a landslide, often triggered by heavy rain fall or earthquakes
What is the process of slumping?
Also called slipping, it is the collapse of saturated or weak rocks, often along a curved surface
What is the process of rock falls?
Fragments of rock breaking away from a cliff face, often resulting from freeze-thaw weathering, to form scree at the cliff foot.
What is erosion?
The removal or material and the shaping of landforms
What are the 3 main processes of erosion?
Hydraulic power
Abrasion
Attrition
Describe the process of Hydraulic power
The power of the waves as they smash into a cliff. Trapped air is forced into holes and cracks in the rock, eventually causing it to break apart. The explosive force of trappe air operating in a crack is called a cavitation.
Describe the process of abrasion
The “wearing away” of cliffs or rocky platforms by rock carried by the sea. Corrasion is the fragments of rock that are hurled at a cliff by the sea.
Describe the process of attrition
Rock frgamnets carried by the sea knock against one anothe causing them to become smaller and mroe rounded. It is not responsible for eroding landofrms.
What is coastal transportation?
The movement of sediment.
What are the 4 types of coastal transportation
Solution
Suspension
Saltation
Traction
Solution
The trabnsportation of dissolved chemicals derived from limestone or chalk.
Suspension
Particles carried ( suspended)
Saltation
A hopping or bouncing motion of particles to heavy to be suspended
traction
Large pebbles rolled along the seabed
Why does longshore drift happen?
If waves approach the beach, the sediment is solely moved up and down the beach. But if the waves approach at an angle, sediment will be moved along the beach.
Longshore drift
the movement of material along a coast by waves which approach at an angle to the shore but recede directly away from it.
Swash
Waves carry sediment up the beach
Backwash
Sediment carried back down the beach as the wave draws back
Where does Coastal deposition happen?
In areas where the flow of water slows down, waes loose energy in sheltered bays and where water is protected by spits or bars.
How does coastal deposition happen?
Sediment can no longer be moved in sheltered bays and is therfore depositied
This is why beaches are found in bays, where the wave energy is reduced.
Where are mudflats and saltmarshed often found?
In sheltered estuaries behind spits where there is little flow of water.
COASTAL EROSION
Concordant and discordant coasts
Rock type and Geological structure can influence the erosional landforms that develop on a coast line:
-> Hard rocks like granite take a long time to erode, while softer rocks like sandstone erode more quickly
-> Rocks with lots of joints and faults erode faster
Discordant coastline - alternating bands of soft and hard rock perpendicular to the coast
Concordant coastline - Alternating bands of soft and ahrd rock parralel to the coastline
Folding
The crumpling of rock layers cuased by extreme tectonic pressures
Faulting
The displacement of rock along a crack
COASTAL EROSION
Rock type
(lithology)
Some rocks are tougher and more resistant than others. For example, rocks such as granite, limestone and chalk are more resistant to erosion than sand and clay
How do headlands and bays form?
Along Discordant Coastlines - where there are alternating bands of resistant and less resistant rock along a coast
The less resistant rock is eroded faster, forming a bay with a gentle slope
The resistant rock erodes more slowly, it juts out, forming a headland with steep sides
How are Wave-cut platforms formed?
1) Waves cause erosion at the foot of a cliff, forming a wave-cut notch which is enlarged over time
2) Repeat erosion causes the rock above the notch to become unstable untill it eventually collapses
3) The collapsed material is washed away and a new wave-cut notch begins to form
4) After repeated collapses the cliff retreats, leaving a wave-cut platform
How do caves form?
1) The resistant rock that makes up headlands often has weaknesses - like cracks or faults
2) Waves crash into the headlands and enlarge the cracks ( mainly by hydraulic power and abrasion)
3) Repeated erosion and enlargement of cracks causes a cave to form
How do arches form?
Continuous erosion deepens the cave untill it breaks through the headland to form an arch e.g. Durdle Door
or two back-to-back caves breaking through to form an arch.
How do stack form?
From an arch, gradually the arch is enlarged by erosion at the base by weatheing process acting on the roof. The erosion wears away the rock supporting the arch untill it eventually collapses, forming a stack.
What is a floodplain?
A floodplain is an area of land which is covered in water when a river bursts its banks.
How do floodplains form?
Floodplains form due to both erosion and deposition .Erosion removes any interlocking spurs, creating a wide, flat area on either side of the river. During a flood, material being carried by the river is deposited (as the river loses its speed and energy to transport material). Over time, the height of the floodplain increases as material is deposited on either side of the river.
Where are floodplains often found?
Floodplains are often agricultural land, as the area is very fertile because it’s made up of
alluvium
(deposited silt from a river flood). The floodplain is often a wide, flat area caused by
meanders
shifting along the valley
Where do levees occur?
Levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs.
How do levees form?
Sediment that has been eroded further upstream is transported downstream.When the river floods, the sediment spreads out across the floodplain.When a flood occurs, the river loses energy. The largest material is deposited first on the sides of the river banks and smaller material further away.
After many floods, the sediment builds up to increase the height of the river banks, meaning that the channel can carry more water (a greater discharge) and flooding is less likely to occur in the future.
What are river landscapes and sediment load influenced by?
Climate - long term rainfall and temp in area
Geology - Type of rocks
Slope processes
What are some examples of river landscapes and sediment load being influenced by climate?
- Wetter climates = Higher discharge = increased rate of erosion = River’s load = more transport of material
- More weathering = more freeze thaw = shapes landscape
What are some examples of river landscapes and sediment load being influenced by geology?
- Harder rock = less erosion = lower load
- Hardrock on softrock = waterfalls
- More resistand rock = Steeper valley sides
What is river discharge?
Volume of water flowing in a river per second ( Mesured in cumecs )
What do hydrographs show?
how the discharge at a certain point in a river changes over a time in relation to rainfall
What does the rising limb of a hydrograph show?
The increase in river discharge as rainwater flows into the river
In a Hydrograph, what does the gap between peak rainfall and peak discharge show?
Lag time - the delay between peak rainfall and peak discharge
What does the top of the rainfall graph in a hydrograph show?
Peakrainfall
What does the top of the discharge line on a hydrograph show?
The highest discharge in the period of time you’re looking at
What does the falling limb of a hydrograph show?
the decrease in river discharge as the river returns to normal level
Why does lag time occur in a hydrograph/river
- Most rainwater doesnt land directly in the river channel, it flows quicky overland (surface runoff), or soaks into the ground (infiltration) and then flows slowly undeground to the channel
When does flooding occur?
when a river’s level rises so much that it spills over its banks
What physical and human factors affect flood risk? (5)
These shorten the lag time, so peak discharge is higher and flooding is more likely to occur:
Heavy rainfall
Geology ( Rock type )
Prolonged Rainfall
Releif ( changes in land height )
Land use
How does heavy rainfall affect risk of flood?
This means the water arrives too quickly to infiltrate, so theres a lot of surface runoff, which increases discharge
How does geology affect risk of flood?
(rock type) Clay soild and some rocks e.g. granite and shale, are impermeable (i.e they dont allow infiltration), so runoff is increased
How does Releif affect risk of flood?
Releif (changes in and height)
If a river is in a steep-sided valley, water will reach the river channel quicker because it can flow faster down the steep slopes - this rapidly increases discharge
How does land use affect risk of flood?
1) Buildings are often made of impermeable materials (concrete) and surrounded by roads (tarmac) increasing surface runoff. Man made drains then quickly transport runoff to rivers, increasing drainage
2) Trees intercept rainwater on their leaves, which then evaporates. Trees also take up and store water from the ground. This means that cutting down trees increases the volume of water that enters the river channel
What economic factors increase risk of floods?
Increased frequency of storms
- Consequence of global climate change
- Storms are also becoming more extreme- more intense rainfall increases scale of floods
- More wet weather means that the ground is more often saturated allowing floods to happen fatsr.
What is the increasing risk of flooding in the Uk due to?
Storm frequency increasing and changing land use ( Urbanisation and deforestation)
What impacts can UK Flooding have?
- Water born diseases, people injured
- Damage to home and possesions
- Silt deposition on farmland
- Pollution of land Via spread sewage water and landfill
- Erosion of land
What is hard engineering? ( Rivers)
Man-made structures built to control the flow of rivers and reduce flooding
What is soft engineering? ( Rivers)
Schemes set up using knowledge of a river and its processes to reduce the effects of flooding
What are the 4 examples of River Hard engineering methods?
Dams and reservoirs
Channel straightening
Embankments
Flood relief
What are the 4 examples of River Soft engineering methods?
Flood warnings and preparation
Flood plain zoning
Planting trees
River restoration
What are Dams and Resevoirs?
Barriers built across rivers, usually in the upper course. Reservoir ( Artificial lake ) is formed behind the dam.
What is Channel Straightening?
Meanders are removed by building straighter, artificial channels
What are embankments?
Raised walls are built on embankments.
What are flood relief channels?
Channels are built to divert around built-up areas or to divert excess water if the river level gets too high.
What are flood warnings and preparation?
The Environment Agency issues flood warnings through various media (TV,Radio,internet)
What is flood plain zoning?
Restrictions prevent building on parts of a flood plain that are likely to be affected by flood
What is soft engineering of planting trees?
Planting trees in the river valley increases the interception of rain water (and lag time)
What is soft engineering of River restoration?
Making the river more natural. e.g. by removing man made levees, and so that the flood plain can flood naturally.
What are the Benefits and disadvantages of Channel straightening?
+ Water leaves the area more quickly rather than building up, so the flood risk is lower
- Flooding may happen downstream instead, fast moving water may cause more damage downstream
What are the Benefits and disadvantages of Embankments?
+ The river can hold more water, so floods are less frequent
- Expensive, and create a risk of severe flooding if the water rises above them or they break.
What are the Benefits and disadvantages of Flood warning preparation?
+ Gives people time to move possessions upstairs, or evacuate, reducing impact of flood
- No prevention, May not broadcast to everyone or give a false sense of security
What are the Benefits and disadvantages of soft engineering by planting trees?
+ Discharge and flood risk decrease, protects soil and provides habitats
- Less land is available for farming
Where is Oxford situated, why does this make it susceptible to river flooding?
- at the confluence of the river Thames (west) and the tributary river Cherwell (east)
- The proximity makes it susceptible to flooding during periods of heavy rain
What happened in July 2007 Oxford ( rivers ) ?
The river discharge increased rapidly causing flash flooding
What were the effects of the 2007 floods in Oxford ( rivers ) ?
- Over 250 homes had to be evacuated in the Botley area and the A420 Road had to be evacuated
- A later flood in Jan 2014 caused trains to be canceled and drains to overflow
= Restricting peoples access to work an services, as well as damaging the local economy by preventing tourists from visiting Oxford’s local historic centre
When did planning for flood management scheme in oxford start?
2014
The Oxford Flood Alleviation Scheme
Span 5km and include both hard and soft management strategies
What did the Oxford Flood Alleviation Scheme entail?
Diverting water away from more densely populated areas
- Increasing water storage in the flood plain and in an existing bypass channel southwest of Oxford to slow runoff and decrease peak discharge
400 000 m3 of earth will be dug up to increase capacity
- Excavated material to create embankments
What are the social issues of the Oxford flood management scheme?
Compulsory Purchase Orders were sent to landowners to widen flood plains.
Construction may disrupt residents lives - noise pollution - large vehicles blocking roads
What are the Economic issues of the Oxford flood management scheme?
- Costs 150 million, and not all funding has been secured yet
What are the social benefits of the Oxford flood management scheme?
- Improve public footpaths - more opportunities for recreation
- Resident confidence that their homes wont flood
What are the Economic benefits of the Oxford flood management scheme?
Homes and business will be better protected, so there is less expensive damage, reducing insurance costs
What are the Environmental issues of the Oxford flood management scheme?
Over 2000 trees and 2 hectares of rare grassland will be removes - replanted but long to grow back
What are the Environmental benefits of the Oxford flood management scheme?
Create over 20 hectares of riverside habitats, increasing biodiversity
what is your example for a coastal landscapes location?
What are the 4 structures there?
Dorset
Durdle Door - arch
Ludworth cove - Bay
Chestil Beach - Bar (tombolo)
Swanage bay
What is your example for coastal management?
Lyme Regis
Why do the cliffs of Lyme Regis need protecting from erosion?
1) Powerful waves from the south-west erode the sea cliffs, causing them to collapse
2) In May 2008, about 400m of cliff slipped between Lyme Regis and Charmouth
3) Much of the town’s eastern side is built along the edge of cliffs, and many properties have been damaged by landslides, slumps and waves breaching the sea walls
Why is around 1km of coastline on Lyme Regis is managed using hard engineering strategies?
1) Lyme Regis has a population of over 3600 people, and around 500 000 tourists visit each year
2) Around 900m of the A3052 road, which links Lyme Regis to other towns along the coast, would’ve been lost within 50 years
3) The Local economy depends on tourism (about £42 million spent by tourists in 2015), but erosion of the coast could threaten the historic town centre and the tourism industry
What was the 1990 West Dorset District Council scheme to provide long-term protection for Lyme Regis?
1) Phase 1 (completed 1995) involved building new rock armour on the eastern end of the sea front
2) Phase 2 (completed 2007) protected the front of the main town - the sand and shingle beaches were replenished and stabilised - existing rock armour was extended (Beacon rocks) and re-aligned ( North wall rockery), and drainage systems were improved ( to reduce water build up and prevent landslides) - Cost £26 Million
3) Phase 3 was meant to prevent landslides to the west of Lyme Regis, but it was never carried out - expensive
4) Phase 4 (completed 2015) cost £19.5 million. It included 390m of sea walls and rock armour, and protects roads in the town
What are the positive effect of the defences in Lyme Regis?
1) Improved beaches have increased trade by 20% in some parts of the town
2) The rock armour absorbs the energy of the powerful waves, protecting the harbour and the boats inside
3) People feel more secure buying property in Lyme Regis - New defences have made it easier to insure houses against coastal erosion and landslides
What are the negative effect of the defences in Lyme Regis?
1) Greater number of tourists = More traffic, litter, pollution
2) Important fossils have been found but defences prevent them from being exposed
3) Some residents think it was very expensive for a short-term solution, as the defences could need re-building in 60 years time
How are beaches formed?
Depostition
-> Found on coasts between the high and low water marks
-> Formed by constructive waves depositing material
How are the Lowlands in the UK distributed?
To the South and East, are formed of softer sedimentary rocks (e.g. Chalks and clays) that erode more easily
Most cities are in Lowland areas and are often on the UK’s main rivers (e.g. London - On the Thames, Liverpool - on the Mersey, and Cardiff - On the Servern Estuary)
What is the River Clyde?
Lower Valley (NW)
-> The River Clyde has a wide lower valley and a flood plain
-> The City of Glasgow is situated on the flat ground of the Clyde’s flood plain
What is the Grampian Mountains
(Very North, like a band through Scotland)
Part of the Highlands and home to Ben Nevis (the highest mountain in the UK), The Grampians are steep, rocky and sparsely populated
What is the Lake District?
Middle East England (On the Knob)
A national park that is very popular with tourists, the Lake District is an upland area that has alot of Glacial Features
How do sand beaches form?
Sand beaches - created by low energy waves and are flat and wide - sand particles are small so the weak backwash can move them back down the beach, creating a long, gentle slope
How are shingle beaches formed?
Shingle beaches are created by high energy waves and are steep and narrow - sand particles are washed away but larger shingle is left behind. The shingle particles build up to create s steep slope
How do spits form?
1) Form at sharp bends in the coastline e.g. a river mouth
2) Longshore drift transports sand and shingle past the bend and deposits it in the sea
3) Strong wind and waves can curve the end of the spit (forming a recurved end)
What happens once a spit forms?
1) The area behind a spit is sheltered from waves, so material accumulates and plants are able to grow
2) Over time, this area can become a mud flat or a salt marsh e.g. Welwick saltmarsh, Yorkshire
How are Bars formed?
1) When a spit joins two headlands together
2) The bay between the headlands gets cut off from the sea
3) This means a lagoon can form behind the bar
4) Off shore bars can form if the coast has a gentle slope - friction with the sea bed causes waves to slow down and deposit sediment offshore, creating a bar that is not connected to the coast
How do sand dunes form?
1) Sand dunes (e.g. Camber Sands, East Sussex) are formed when sand deposited by longshore drift is moved up the beach by the wind
2) Obstacles (e.g. driftwood) can cause wind speed to decrease so sand is deposited, forming small embryo dunes
3) Embryo dunes are colonised by grass (e.g. Marram grass). The roots of the vegetation stabilise the sand, encouraging more sand to accumulate there.
4) This forms foredunes and eventually mature dunes. New embryo dunes form infront of stabilised dunes
5) Dune slacks can form in hollows between dunes
What is the course of a river?
The path of a river as it flows downhill
How is the river course distributed?
1) Steep Upper course (nearer source) , gently sloping middle course and an almost flat lower course (near mouth)
What does the long profile of a river show you?
How the gradient changes (of the river course)
What can rivers do as they flow downhill?
1) Form Channels and valleys
2) Erode the landscape and transport eroded material to somewhere further along the course, where its deposited
How does the shape of the river change along its course?
The shape of the valley and channel changes along the river course depending on whether erosion or deposition is the main process
What does the cross-profile of a river show you?
What a cross section of a river looks like
What is the middle course of a river like?
Gradient- Medium
Valley and channel shape - Gently sloping valley sides. Wider, deeper channel
Cross profile looks like a D with a smaller D for the channel
What is the lower course of a river like?
Gradient- Gentle
Valley and channel shape - Very wide, almost flat valley. Very wide, deep channel
Cross profile looks like a Valley is offside netball channel is the D
What is the upper course of a river like?
Gradient- steep
Valley and channel shape - V-shaped valley, steep sides. Narrow, shallow channel
Cross profile looks like a V
How can Vertical erosion affect the cross profile of a river?
This deepens the river valley and channel, making it V shaped. Its dominant in the upper course of the river. High turbulance causes the tough, angular particles to be scraped along the river bed, causing intense downward erosion
How can lateral erosion affect the cross profile of a river?
Widens the river valley and channel during the formation of meanders. Dominant in the middle and lower parts of the river course
How are waterfalls formed?
1) Waterfalls are where a river flows over an area of hard rock followed by an area of soft rock
2) The softer rock is eroded ( by hydraulic action and abrasion), more than the hard rock, creating a “step” in the river
3) As water flows over the step it erodes more and more of the softer rock
4) A steep drop is eventually created, called a waterfall.
E.g. High force watefall on the river tees, County Durnham
How are plunge pools and gorges created from waterfalls?
1) The hard rock is eventually under cut by erosion. It becomes unsupported and collapses
2) The collapsed rocks are swirled around the foot of the waterfall where they erode the softer rock by abrasion. This creates a deep plunge pool
3) Overtime, more undercutting causes more collapses. The waterfall retreats, leaving behind a steep-sided gorge
What does fluvial mean?
river
How are interlocking spurs formed?
1) In the upper course of the river most of the erosion is vertically downwards. This creates steep-sided, V-shaped valleys
2) The river lacks the power to erode laterally, So they have to wind around the hillsides that stick out into their paths on either side
3) The hillsides that interlock have rivers that wind around them called interlocking spurs
Where are meanders formed?
Rivers develop large bends called meanders in their middle and lower courses, in areas where their channel has both shallow and deep sections
How are meanders formed?
1) The current is faster on the inside of a bend because the river channel is deeper ( theres less friction to slow the water down)
2) So more erosion takes place on the outside of the bend, forming river cliffs
3) The current is slower on the inside of the bend because the river channel is shallower - more friction
4) So eroded material is deposited on the inside of the bend, forming slip-off slopes
What are estuaries?
Tidal areas where the river meets the sea
Where are estuaries found and what are their features?
1) They are found at river mouths - where the land is close to sea level and the river valley is at its widest
2) The water is tidal (rises and falls each day)
3) When the water floods over the banks of the river, it carries silt and sand onto the valley floor.
4) As the tide reaches its highest point, the water moves slowly with little energy - so it deposits sediment
5) Overtime, more mud builds up, creating large mud flats
6) At low tide, the low muddy banks are exposed
Rivers
Hydraulic action
The force of the river water colliding with rocks breaks rocks away from the river channel
Rivers
Abrasion
Eroded rocks picked up by the river scrape and rub against the channel, wearing it away
Rivers
Attrition
Eroded rocks picked up by the river crash into eachother and break into smaller fragments. Their edges get more rounded off as they rub together. The further the material travels, the more it is eroded - the attrition causes particle size to decrease from a river’s source to its mouth
Rivers
Solution
River water erodes some types of rock e.g. chalk and limestone
What are the types of erosion in rivers?
Hydraulic action
Abrasion
Attrition
Solution
The faster a rivers flowing, the more erosion that happens
What are the 4 types of transportation in rivers?
Movement of eroded material
Traction
Saltation
Suspension
Solution
RIvers
Traction
Large particles like boulders are pushed along the river bed by the force of water
RIvers
Saltation
Pebble-sized particles are bounced along the river bed by the force of water
Rivers
Suspension
Small particles like silt and clay are carried along by water
Rivers
Solution
Soluble materials (e.g. limestone) dissolve in the water and are carried along
What are the reasons for river deposition?
1) The volume of water falls
2) The amount of eroded material increases
3) The water is shallower, e.g. inside of a bend
4) The river reaches its mouth
5) Particle size affects how far material is transported, small particles are transported further and deposited close to the rivers mouth
What are the Examples of coastal features In Dorset?
Durdle Door - Arch
Ludworth Cove - Bay
Chestil Beach - (Tombolo) Bar
The foreland (headland) and Swanage bay/Studland bay (Bays) - also featuring old harry (stack) and his wife (stump)
