Unit 1 - Section C - Physical landscapes of the U.K Flashcards
Where are the majority of igneous rocks located?
North Scotland
Snowdonia
Wales
Where are the majority of metamorphic rocks located?
North Scotland
Where are the majority of sedimentary rocks located?
East England
Where are the U.K upland areas found and what is the main rock type found?
-North and West of the country
-Igneous rocks (granite) and metamorphic (Slate) which are resistant to erosion
Where are the U.K lowland areas located and what is the main rock type found?
-South and East of the country
-Sedimentary rocks like chalk and clay which erode easily
What are examples of upland areas in the U.K.?
Lake district
What are examples of lowland areas in the U.K.?
Lancashire
Chesire
Define the term coast
The interface between land and sea. They are the dynamic zone where the land meets the sea and where coastal processes operate
Define the term fetch
The distance the wind has blown the wave
Define the term crest
Highest point on a wave
Define the term trough
Lowest point on a wave
Define the term wave length
Distance between each crest
Define the term wave height
The distance between the top of the crest and the bottom of the trough
Define the term breaking wave
A wave that has hit the beach
Define the term swash
Water that travels up the beach after the wave has broken
Define the term backwash
Water that travels back down to the sea by gravity
What are the two types of wave
Constructive wave
Destructive wave
What is a constructive wave?
Constructive waves are low waves that surge up the beach and spill with a powerful swash. They deposit large amounts of materials and construct the beach
What is a destructive wave?
Destructive waves are formed by local storms close to the beach. They are close together and produce a swirling mass of water. They become high and steep but then plunge down onto the beach
What are the properties of destructive waves?
-Close together
-Steep wave front
-Breaking wave plunges downwards
-Steep beach
What are the properties of constructive waves?
Far apart
Gently sloping
Breaking wave spills forward
Define the term hydraulic action
Waves crash against rock and compress the air in cracks. The air then expands and this puts pressure on the rock. This repeats and causes cracks to widen and bits of rock to break off
Define the term abrasion
Eroded particles in the water scrape and rub against rock removing pieces
Define the term attrition
Eroded particles in the water collide. They then break into smaller pieces and become more rounded and smooth
Define the term mechanical weathering
The breaking down of rock without changing its chemical composition
What happens in freeze thaw weathering
-Water enters the crack of a rock
-The water then freezes which expands the rock
-This puts pressure on the rock
-The water then thaws
-This process repeats and the crack widens causing some rock to break off
Define the term chemical weathering
The breakdown of rock by changing its chemical composition
What is mass movement?
The shifting of rocks and loose materials down a slope
How does chemical weathering occur?
Rainwater which is slightly acidic slowly dissolves certain rock like chalk and limestone
What are the three types of mass movement?
Slumping
Sliding
Rockfall
How does slumping occur?
-Since clay is impermeable
-If it rains water sits on top of the clay
-This adds weight to it and the combined weight of water and gravity causes the clay to slump
How does rockfall occur?
-Weathering causes rocks to become loose
-They then slide down the cliff if they break off
How does landslide occur?
-Material shifts in a straight line along a slide plane
-This often happens when there is a wave cut notch at the bottom of the cliff
What is longshore drift?
-Longshore drift occurs when the waves hit the coast at an oblique angle
-The swash carries material up the beach in the direction of the wave
-The backwash carries the material down the beach at right angles towards the sea due to gravity
-Over time material zigzags along the coast
What are the four transportation methds?
Traction
Saltation
Suspension
Solution
What is traction?
Large load like boulders are rolled along the sea bed by the force of water
What is saltation?
Pebble sized particles are bounced along the sea bed by the force of water
What is suspension?
Small particles are carried along the water
What is solution (transport)?
Soluble materials are dissolved in the water and carried along
What is deposition?
When the sediment is placed down
When does deposition occur?
-Deposition occurs when the water carrying sediment loses energy and slows down
-There is erosion further along the coast as there’s more material to place
-Lots of material is transported
What is a concordant coastline?
When the alternating bands of rock are parallel to the coast
What is a discordant coastline?
When the alternating bands of hard of soft rock are at right angles to the coast
What are some examples of erosional landforms on the coast?
Headlands
Bays
Cave
Arch
Stack
Stump
Wave cut platforms
Explain the formation of a headland and bay
-Headlands and bays form when there is a discordant coastline and there is less resistant rock in between more resistant rock
-The less resistant rock erodes quicker then the more resistant rock forming a bay with a gentle slope
-Because the more resistant rock takes longer to erode headlands form with steep sides
Explain the formation of the: Cave, arch, stack and stump sequence
-Headlands typically contain loads of cracks (lines of weakness)
-Waves crash into the headlands
-Because of abrasion and hydraulic action these widen the cracks
-This repeats forming a cave
-Abrasion and hydraulic action continue deepening and widening the cave
-As a result the water breaks through the cave forming an arch
-Abrasion and hydraulic action continue wearing down the rock supporting the arch
-Consequently because of gravity the arch collapses which forms a stack
-Eventually wave cut notches form causing the stack to to collapse which form a stump
Explain the formation of a wave cut platform
-Abrasion and hydraulic action occur at the foot/base of a cliff
-Consequently a wave cut notch forms over time
-Abrasion and hydraulic action cause the wave cut notch to enlarge
-Eventually the cliff will collapse and the material gets cleared
-This process repeats and consequently a wave cut platform is formed
Explain the formation of a spit
-Longshore drift occurs and transports sediment along the beach
-Consequently some sediment is deposited in the sea
-This process repeats making the spit longer
-Strong winds and waves can also form a recurved end
Explain the formation of a bar
-A bar forms when a spit joins across 2 headlands
-The bay gets cut off and this forms a lagoon behind the bar
Explain the formation of sand dunes
-Sand dunes are formed when sand deposited by longshore drift is moved up the beach by the wind
-Objects cause wind speed to decrease so sand is deposited forming embryo dunes
-These dunes are colonised by plants like Marram grass and consequently the roots help stabilize the dune
-More sand accumulates there forming foredunes
-Eventually a mature dune forms and new embryo dunes form in front of the foredunes
What are the 2 types of coastal defences?
Hard engineering
Soft engineering
Define hard enginerring
Man made structures built to control the flow of the sea and reduce flooding and erosion
Define soft engineering
Schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion
What are the benefits of a sea wall?
-Prevents erosion
-Acts as a barrier to prevent flooding
-Can be used as a promenade which can attract tourism
What are the drawbacks to a sea wall?
-Expensive to build and maintain
-Creates a strong backwash that erodes under the wall
-Looks unnatural
What are the benefits of gabions?
-Absorb wave energy which reduces erosion
-Cheap and easy to build
What are the drawbacks to gabions?
-They’re ugly
-The wire cages corrode over time
What are the benefits to rock armour?
.Absorbs wave energy which reduces erosion
.Fairly cheap
.Can be used for fishing
.Can provide interest for the coast
What are the drawbacks to rock armour?
-Needs to be replaced as the boulders can move
-The rock type may not be the same as the typical coast rock type which makes them look obtrusive
What are the benefits of groynes?
-Creates a wider beach which slows down the waves
-Fairly cheap
-Provides useful structures for fishing
What are the drawbacks to groynes?
-They starve beaches further down the coast making them narrower
-They look unnatural
-They increase rate of erosion further down
What are the benefits of beach nourishment and reprofiling?
-Blends in with the existing beach
-Creates wider beaches and slows the waves
What are the disadvantages of beach nourishment and reprofiling?
-Very expensive as it has to be repeated
-Disrupt other envrionments
What are the advantages of dune regeneration?
-Relatively cheap
-Maintains a natural beach environment
-Helps absorb wave energy which prevents flooding and erosion
What are the disadvantages of dune regeneration
-Time consuming
-Can be easily damaged by storms
What are the advantages of managed retreat?
-Works with nature
-Cheap and easy
-Helps protect farmland from flooding
What are the disadvantages with managed retreat?
-People who live by the sea get nervous
-The salt water can damage ecosystems
Where are named examples of coastal landforms?
-Durdle door - Arch
-Chesil Beach - Bar which joins the Isle of Portland to the mainland and behind the bar is The Fleet Lagoon
-Swanage bay, Studland bay and The Foreland - Headland and bays. At the end of the Foreland is a stack called Old Harry and a Stump called Old Harry’s wife
Why does Lyme Regis need to have its coast managed?
Lyme Regis has a population of over 3600 people and around 500,000 tourists each year
Around 900m of the A3052 road which links Lyme Regis to other towns would’ve been lost within 50 years
The local economy relies on tourism (Around £42 million was spent by tourists in 2015)
Erosion would be a threat to the historic town center and the tourism industry
What are the positive impacts to Lyme Regis’ coastal defences?
The improved beaches have increased trade by 20% in some parts of the town
The rock armour absorbs the powerful wave energy protecting the harbour
People now feel more secure when buying properties in Lyme Regis as the defenses ensure that the houses are protected against coastal erosion and landslides
What are the drawbacks/disagreements to Lyme Regis’ coastal defences?
Greater number of tourists increases traffic, litter and noise pollution
The defenses stop new fossils from being located
Some residents think it was expensive for the short-term solutions as the defenses may need rebuilding in 60 years time
What did Lyme Regis do to defend the coast (4 phases)?
Phase 1 - Involved building new rock armour, a sea wall and a promenade. This finished in 1995
Phase 2 - Work started in 2005 and ended in 2007. The rock armour was extended and the old wooden groynes were replaced with new stone groynes . Drainage systems were improved to reduce water build up and prevent landslides. The total cost was £26 million
Phase 3 -Was meant to prevent landslides to the west however was never carried out due to its cost
Phase 4 - Was completed in 2015 and cost £19.5 million . It included 390 metres of sea walls and rock armour to protect roads into the town
What is hydraulic action in rivers?
The force of the river water colliding with rocks breaks rock particles away from the river channel
When do rivers deposit their load?
-The volume of water falls
-The amount of eroded material increases
-The water is shallower
-The river reaches its mouth
Describe the river’s shape and gradient in the upper course
-Steep gradient
-V-shaped valley
-Steep sides
-Narrow
-Shallow
-Water velocity is low
-Vertical erosion is dominant
Describe the river’s shape and gradient in the middle course
-Gently sloping valley sides
-Wider
-Deeper channel
-Lateral erosion is more dominant here
Describe the river’s shape and gradient in the lower course
-Very wide
-Almost flat valley
-Very deep and wide
-Lateral erosion is dominant here
What is vertical erosion?
-Erosion that deepens the river valley and channel making it v-shaped
-It is dominant in the upper course of a river
-High turbulence causes the rough and angular particles to be dragged across the river bed causing vertical erosion
Define lateral erosion
-This widens the river valley and channel during formation of meanders
-It is dominant in the middle and lower course
Explain the formation of a gorge
-Waterfalls form when a river flows over an area of hard rock followed by soft rock
-The soft rock is eroded by abrasion and hydraulic action much quicker than the cap rock which is more resistant (Differential erosion)
-This forms an overhang
-Due to gravity and the weight of the water the overhang will collapse
-The hard rock will then collapse into the plunge pool
-Consequently it will break apart and because of abrasion and hydraulic action it will widen and deepen the plunge pool
-Over time this process repeats forming a gorge
What are interlocking spurs?
-Found in the upper course of a river where most erosion is vertically downwards
-This creates steep v-shaped valley sides
-In the upper course rivers lack the power to erode laterally so they wind around rocks and hillsides that stick out
-Those hillsides that stick out are interlocking spurs
Explain the formation of a meander
-Rivers develop large bends in the river called meanders in the middle and lower course
-The current is faster on the outside of the bend because the river channel is deeper
-Consequently more erosion takes place on the outside of the bend forming river cliffs
-The current on the inside of the bend is slower as the river channel is shallower
-Therfore the river deposits its material which forms slip off slopes
How are ox-bow lakes formed?
-Abrasion and hydraulic action cause the outside of the bends to get closer
-The neck consequently gets shorter
-During a flood, storm or when river velocity is at its fastest the neck of the meander gets cut off
-The river takes the shortest route and consequently deposition occurs which cuts off the old meander
-This forms an ox-bow lake
Explain the formation of a floodplain
-The floodplain is a the wide valley floor on either side of a river
-When rivers flood, water loses energy and deposits the material it’s transporting
-This helps build up the floodplain
-The deposition that happens on slip off slopes also builds up flood plains
Explain the formation of a levee
-Levees are natural embankments along the edges of a river channel
-During a flood eroded material is deposited over the whole flood plain
-The heaviest material gets deposited closest to the river channel
-Over time the deposited material builds up creating levees along the edges
Explain the formation of mudflats
-Estuaries are found at river mouths
-The river level rises and falls each day (tidal)
-When the water floods over the banks of a river it carries silt and sand onto the valley floor
-As the tide reaches its highest point it deposits its sediment
-Over time more builds up creating mudflats
What is an estuary?
Tidal areas where the river meets the sea
What are the factors that affect flood risk by increasing river discharge?
Heavy rainfall
Geology
Prolonged rainfall
Relief of the land
Land use
How does heavy rainfall lead to floods?
Heavy rainfall means that water arrives too quickly to infiltrate so there is more surface runoff which increases river discharge
How does the geology increase river discharge?
Some rocks like clay are impermeable. This means infiltration doesn’t take place so therefore more runoff takes place
How does prolonged rainfall increase river discharge?
Prolonged rainfall can saturate soil. Any further rainfall can’t infiltrate which means runoff is increased
How does relief increase river discharge?
If a river has steep valley sides water will get to the river quicker as it can flow faster. This increases discharge
How does land use affect river discharge?
-Buildings are made from impermeable surfaces like concrete aswell as surrounding roads. This increases runoff. In addition man-made drains quickly transport water increasing discharge
-Trees intercept rainwater on their leaves which then evaporates. If you cut down trees (deforestation) this increases discharge as more water enters the channel
What is peak discharge?
The highest discharge in the river in the period of time you’re looking at
What is lag time?
The delay between peak rainfall and peak discharge
What is the rising limb?
The increase in river discharge as rainwater flows into the river
What is the falling limb?
The decrease in river discharge as the river returns to its normal state
What are the benefits of dams and reservoirs?
-Reservoirs store water after heavy rain, control water flow and prevent floods downstream
-They also create man-made habitats for wildlife
-They can be used to generate hydroelectric power
What are the benefits of channel straightening?
.Water leaves the area more quick;y therefore flood risk is lower
What are the benefits of enbankments?
The river can hold more water so floods are less common
What are the benefits of flood relief channels?
Gates on channels mean that the release of water can be controlled reducing flood risk
What are the benefits of flood warnings and preperation?
Warnings give people time to move possessions upstairs, put sandbags in place and even evacuate
This reduces the impact of flooding
What are the benefits of floodplain zoning?
Flood risk is reduced as there are fewer impermeable surfaces near the river
The impact of flooding is reduced
What are the benefits of planting trees to reduce flood risk on rivers?
Discharge and flood risk is reduced
Vegetation reduces soil erosion and provides habitats for wildlife
What are the benefits of river restoration?
Discharge is reduced so there is less risk of flooding downstream
Little maintenance is needed and there are better habitats for wildlife
What are the drawbacks of dams and reservoirs?
-Dams are expensive to build
-The creation of a reservoir can flood settlements
-Material is deposited in the reservoir not along the river’s course so the land becomes less fertile
What are the drawbacks of channel straightening?
-Flooding may happen downstream instead
-Fast flowing water may cause erosion downstream
What are the drawbacks of embankments?
-They’re expensive
-Risk of severe flooding if the water rises above the embankments
What are the drawbacks of flood relief channels?
-There will be increased discharge where the relief channel joins the river
What are the drawbacks of flood warning systems?
-They don’t prevent floods
-People may not have access to the warnings
-They may not be taken seriously
-It may give people a false sense of security
What are the drawbacks of flood plain zoning?
-The expansion of urban areas is limited
-It can’t help sites that have already been built on
What are the drawbacks of planting trees?
Less land available for farming
What are the drawbacks of river restoration?
Local flood risks can increase especially if nothing is done to prevent major flooding
Why were river management schemes put in place for Oxford?
Oxford is situated right at the confluence of the River Thames and the River Cherwell
These 2 rivers are at huge risk of flooding especially during heavy rainfall
In 2007, river discharge increased rapidly causing flash floods
This meant over 250 homes had to be evacuated
In 2014 a later flood caused trains to be cancelled and drains to overflow
These floods restricted people’s access to work and services as well as damaging the local economy as they prevented tourists visiting Oxford’s historic centre
What were the flood management schemes put in place in Oxford?
Increasing water storage in the floodplain and in the existing bypass channel - 400000 metres cubed of earth will be dug up to increase capacity
Planting 20000 trees - 20,000 trees will be planted to slow runoff and decrease peak discharge
Flood walls - Reused excavated material to build flood walls and embankments to protect at risk areas
What are the social impacts of the flood management schemes in Oxford?
Construction may disrupt residents’ lives because of noise pollution
The scheme will improve public footpaths providing more opportunities for recreation
Residents feel more confident their home won’t flood
What are the economic impacts of the flood management schemes in Oxford?
The total cost is £120 million and not all the funding is secured
Over 1000 homes and businesses will be better protected so there is less risk of expensive damage to property
What are the environmental impacts of the flood management schemes in Oxford?
Over 2000 trees will be removed and 2 hectares of rare grassland will be removed. They will be replanted but it will take a while to regrow
The scheme will create over 20 hectares of riverside habitats which will increase biodiversity
What was phase 1 of the Lyme Regis’ coastal defence?
Phase 1 - Involved building new rock armour, a sea wall and a promenade. This finished in 1995
What was phase 2 of the Lyme Regis’ coastal defence?
Phase 2 - Work started in 2005 and ended in 2007. The rock armour was extended and the old wooden groynes were replaced with new stone groynes . Drainage systems were improved to reduce water build up and prevent landslides. The total cost was £26 million
What was phase 3 of the Lyme Regis’ coastal defence?
Phase 3 -Was meant to prevent landslides to the west however was never carried out due to its cost
What was phase 4 of the Lyme Regis’ coastal defence?
Phase 4 - Was completed in 2015 and cost £19.5 million . It included 390 metres of sea walls and rock armour to protect roads into the town
What did the River Tees do in order to manage floods?
-Cow Green reservoir
-Tees Barrage
-Dredging
-Cutting of meanders
-Yarm flood defence scheme
How did the Cow Green reservoir impact the River Tees?
-It was built in 1970
-It can store water and release water at will
-Is used to store water in order to prevent flooding
How has the Tees barrage impacted the river Tees?
-A man made barrier built across the river
-It was made for recreational purposes and to help make water quality better
-Completed in 1995 and it costed £54 million
-The water is cleaner as it doesn’t mix with any salt water at the estuary
-It helps act as a flood defence during storms
How did dredging impact the river Tees?
-The lower parts of the River Tees are dredged periodically
-This increases the river capacity and therefore decreases flood risk
How has cutting off meanders impacted the River Tees?
-In 1810 the neck of the Mandale loop was cut off
-This shortened the river by 4Km and increases river velocity therefore decreasing flood risk
How has the flood defence scheme in Yarm affected the river Tees?
-Since 1995 flood defence scheme costing £2.1 million has been built
-Flood warning systems have been implemented and building on low lying land has been prohibited
-In the Yarm area the environmental agency have:
-Introduced gabions
-Added concrete walls with metal flood gates
-Used natural earth enbankments
