Topic 4 coastal changes and conflict Flashcards
What are the main ways the tectonic activity has shaped the UK’s landscape?
Plate movements
Plate collisions
Active volcanos
What type of rock was formed by magma cooling on the earth’s surface?
Igneous
Charactaeistics of slate:
- Slate is hard and resistant
- formed from heating of shale
- impermeable
- metamorphic rock
(but, because it forms in layers, it can easily be split into thin slabs.)
Characteistics of schist
- very resistant
- impemeable
- metamorphic rock
Schist is made up of bigger crystals and also splits easily into small flakes.
What do slate and schist together commonly form for a landscape?
These rocks often form upland landscapes with waterlogged and acidic soils because of their resistance and impermeability.
Characteristics of chalk:
- harder than clay(medium resistance)
- forms slopes in UK low lands
- cliffs in UK coastline
- permeable (water flows through it)
- younger form of limestone
- sedimentary rock
Charactaeisitics of clay:
- forms wide and flat valleys because it is easily eroded
- sedimentary rock
- not resistant
-lots of water features in clay landscape rock is IMPERMABLE and so water flows to the surface.
Caracteristics of carboniferous limestone:
- heavily affected by carbonation weathering (occurs in joins and causes arches and caves, caverns)
- sedimentary rock
- permeable
- permeable: dry valleys resurgent rivers(i think it means underwater)
-less resistant than igneous rocks but more resistant than other sedimentary rocks.
Characteristics of granite:
- hard and resistant-forms upland landscapes
- unevenly spread joints
- fewer joints-slowed erosion areas can end up sticking out as tors
Moorlands are created on top of granite because it is impermeable.(moorlands-large areas of waterlogged and acidic soil.)
-impermeable
When did an ice sheet most recently cover much of the UK?
About 20,000 years ago.
What did Plate collisons do to the UK landscape?
Mountains were formed by rocks folding and uplifting due to plate collisions
- collisions also generated intense heat and pressure which
- led to the formation of hard metamorphic rocks
(in northern Scotland and Northern Ireland.)
What did active volcanos do to the UK landscape?
- active volcanos erupted magma onto the landscape, cooled and formed igneous rock(granite)
(UK was much closer to a plate margin 520 million years ago.)
What did Plate movements do to the UK landscape?
Remember:345-280 million years ago, the UK was in the tropics.
What rock does volcanos form?
Igneous rock
What rock did plate collisions create?
Metamorphic
How long ago were volcanos erupting magma that is now the land that makes up the UK?
520 million years ago
Which of the following would NOT be found in a chalk landscape?
Cliff
Tor
escarpment (steep slope)
Tor(exposed rock of broken blocks)
Where was britian 345-280 million years ago?
In the tropics
Dueing the tropics where did carbonifeous limestone form?
The warm and shallow seas
Characteristics of granite:
- very resistant
- impermeable
- forms upland landscapes
- lots of unevenly spread joints
- often topped by moorland
What is moorland?
A habitat found in upland areas.
-low growing vegitation and acidic soils
Types of weathering processes:
Mechanical
Chemical
Biological
Examples of slope processes?
Mass movement
- soil creep.
- landslide
What are climatological processes?
The climate affects how physical processes happen.
Eg. Freeze thaw weathering is more likely if tempratures regualy fluctuate above and below 0 degrees C
What are post glacial river processes?
At the end of glacial periods, rivers became much bigger and more powerful as melted ice flowed into them. They eroded the landscape with great force.
When ice melts glacial landforms are left behind
E.g: hanging valleys
- truncated spurs
- glacial troughs
What does erosion proccess mean?
Erosion is the wearing away of rocks as
As a result, rocks being picked up and moved elsewhere.
What are the pysical landscape processes?
Weathering processes Erosion processes Slope proccesses Cimatological processes Post-glacial river processes
What human activities have shaped distinctive landscapes over time?
- agriculture
- settlement
- forestry
What affects where settlements are built?
- water supply
- easy defence
- shelter
- bridging points over rivers
- resource avalibility
The uk is mainly _____ woodland.
Deciduous(leaves fall of every year)
What type of forest are humans replacing decidous woodland so they can manage their timber?
Coniferous(ever green)
Forest has been cleared to make space for ______
Agriculture
What has been installed in some places to make the land dry enough to be farmed?
Drainage ditches
How has settlement changed rivers?
- diversion througg underground channels
- straightening
- embarkments built
What is chemical weathering?
When the chemical composition of rocks changes
When the climate is warm and wet, carbonic dioxide can dissolve in rain to create a ‘carbonic acid’.
The carbonic acid in rainfall hits rocks and dissolves the parts of the rock made of calcium carbonate.
This also breaks down rock.
What is mechanical weathering?
-it is also called physical weathering
physical changes causes rocks to break down(e.g a change lf temprature from day to night)
-the chemical composition of rocks stay the same
- water expands when it freezes.
- water fills cracks,freezes, it expands, putting pressure on the rock.
The water will then melt, but it has put pressure on the rock.
Eventually, this process of freezing and thawing will wear down rock.
What is biological weathering?
-living orginisms break down rock(e.g tree roots by pushing cracks apart
Mass movement: what are slides?
Slides are when material moves down a slope in a straight line.
Mass movement: what are slumps?
a slip plane forms under the cliff. The cliff then slumps down in layers.
Mass movement: what are rockfalls?
When the cliff materials break and crumble down the cliff.
What are the three types of mass movement?
Slides
Slumps
Rockfalls
_____ movement describes the movement of rocks on a hill or cliff.
These movements are caused by weathering, erosion, and g____. Small changes over time can mean that a cliff’s centre of gravity hangs over the sea, instead of over land.
- Mass
2. Gravity
If conditions are warm and what kind of weathering is more likely to take place?
Chemical weathering
What affects the type of coastline?
Type of rock
- joints and faults
- concordant or discordant coastline
What is a discordant coastline?
alternating chunks of hard rock and soft rock at 90o to the coast.
The sea’s waves will hit both hard rock and soft rock when they meet the coast.
-bays are headlines are formed due to hard and soft rock eroding at diffrent rates
What are concordant coastlines?
1 layer of spft rock
Then 1 layer of hard rock.
The sea’s waves will only hit 1 type of rock when they meet the coast.
What is the softest rock?
Talc is the softest
And clay is softer than chalk.
Which of the following rocks is the most resistant to erosion?
Shale
Clay
Limestone
Limestone
Impacts of Climate on Coastal Erosion and Retreat:
Storm frequency
-if storms happen more often there is more destructive waves
This means erosion and weathering will occur more quickly
Impacts of Climate on Coastal Erosion and Retreat:
Seasonality
Temprature changes and a range of temprature can affect erosion and weathering for rocks.
(Freeze-thaw weathering)
Impacts of Climate on Coastal Erosion and Retreat:
Prevailing wind and wind speed.
- The prevailing winds affect where sediment is carried.
- Strong prevailing winds can lead to lots of destructive waves.
(Winds from the Atlantic Ocean hit the south-west of England.)
Impacts of Climate on Coastal Erosion and Retreat:
Rainfall
- at times of heavy rain fall soil can become saturated.
- this causes MASMOVEMENTS to become more likely.
- After heavy storms, chemical weathering may be more likely to happen.
- heavy rainfall usually comes with storms and destructive waves.
What are the 4 features of the UK climate that impact rates of coastal erosion and retreat?
- Prevailing winds
- rainfall
- storm frequency
- seasonality
_______movement becomes more likely during storms because the intense rainfall means that soil is more ________
- Mass
2. Saturated
Describe the prevailing winds on the UK’s south coast.
-south-westerlies
Warm
Bring adlantic storms
What is responsible for most the erosion at the base of a cliff?
Destructive waves.
Wave cut platform:Stage 1:What does destructive waves eroding the base of the cliff form?
A wave-cut notch
Wave cut platform:stage 2:Continued erosion of the _______causes the rock above it to become less and less stable until it _______.
- Wave-cut notch
2. Collapses
What is stage 3 of wave-cut platforms?
Waves wash away the debris from the cliff collapse.
The destructive waves begin to erode the cliff, causing a new wave-cut notch to form.
Wave-cut platforms:Stage 4:
As stages 1-3 happen again and again, more debris falls into the ocean and the cliff retreats.
What is left behind is called a wave-cut platform.
What is left behind after cliffs retreat due to erosion?
Wave cut platform
Headlands and bays:
Headlands and bays are formed in areas that have ________ of hard and soft rock facing the sea.
alternate areas
How are headlands and bays formed on a discordant coastline?
Rock with lots of cracks and joints is called soft rock.
When the sea hits both the soft and hard rock, more of the soft rock is eroded.
The soft rock erodes inwards, creating a bay.
The hard rock that erodes more slowly is called a headland.
What are 2 coastal landforms of discordant coastlines?
- Headlands
2. Bays
Rock with lots of cracks and joints is called ___ rock.
Headlands are made of ______ rocks with not many weaknesses. As headlands are eroded, these landforms can be created:__________
- Soft
- Resistant
- Caves,arches and stacks
How are caves formed?
There are cracks, joints and weaknesses in rocks.
When cracks get larger (due to the 3 types of erosion) they can become large enough to create a cave.
How are arches formed?
Caves can be eroded from one side of the rock through the other,creating an arch.
(You can see through an arch to the other side)
How are stacks formed?
When the top of an arch collapses because of gravity,
A column called a stack is left behind(isolated rock)
What are 3 costal landforms caused by the erosion of headlands?
- cave
- arch
- stack
What is needed for headlands and bays to form?
Bands of hard and soft rock
Which if the four is not created by the erosion of headlands?
Cave
Spit
Stack
Arch
Spit
The process of longshore drift:
- Waves approach the beach at an angle (due to prevailing wind’s direction)
- Waves are controlled by the wind, so this angle will be the direction the SWASH moves up the beach.
- Gravity is the only force that acts on the backwash. So it goes back to the sea at a right angle to the coast line (it goes straight back)
- This causes sediment to repeatedly move in the shape of a right-angled triangle. Over time, sediment is carried along a beach.
What determines the angle at which the swash moves up the beach?
Prevailing wind
What is costal deposition?
the sea dropping sediment (or material) being carried by the water at the coastline.
(Coasts grow in size when more sediment is deposited on the coast than lost to erosion)
What increases the amount of deposition?
- if erosion on a nearby coast is high
- The more sediment in the ocean, the more deposition there will be.
Why eoes costal deposition happen?
Constructive waves swash is stronger than their backwash.
This means sediment carrried by the sea is deposited on the coastline by destructive waves.
(This usually creates beaches made of sand or shingle between the ‘high’ water mark and the ‘low’ water mark.)
What is the high water mark?
the point the highest up the beach that the sea level rises to.
What is the low water mark?
the point the lowest down the beach that the sea level falls to.
Why are some beaches sandy & some shingle?
Sand:
Sandy beaches are created by sand being deposited on the shoreline.
Sandy beaches are very long, side, and flat because particles of sand are very small and easy to wash back into the ocean with the backwash.
Shingle:
Shingle beaches are made when pebbles and shingle are deposited on the coast.
Shingle and pebbles are big and hard to wash back into the ocean, so they build up (making short and steep beaches)
Coasts get built up when there is more deposition than _____
Erosion
What are sand dunes?
hills of sand created at the back of a beach.
How are sand dunes formed?
The wind blows deposited sand up the beach.
Objects like wood, driftwood or human rubbish can block the wind, leading to hills of sand.
The hills of sand can allow plants and vegetation to grow.
This leads to more sand building up.
What are older sand dunes(hills) and newer sand dunes called?
Older:mature dunes
Newer:embryo dunes.
What are spits?
Spits are piles of sand that create sheltered zones on the coast.
How are spits formed?
When the coast changes direction at an estuary (where a river meets the sea), longshore drift continues to move sediment.
The river doesn’t let the longshore drift completely join to the coast on the other side because the river has the energy to move the sediment.
Spits are the long fingers of sand sticking out from one side on a coastline. They often have marshland forming in the sheltered zone.
What are bars?
When a spit joins twp headlands together.
How are bars formed?
A bar is created when a spit grows across a bay.
What are 3 costal landforms caused by deposition?
Spit
Bar
Sand dune
_____are piles of sand that create sheltered zones on the coast. When the coast changes direction at an ______(where a river meets the sea), longshore drift continues to move sediment across the inlet.
- Spit
2. Estuary
What is managed retreat?
Managed retreat involves accepting defeat. Instead of trying to stop the sea advancing, coastal defences are removed, and land is flooded.
Advantages of managed retreat:
- Don’t have to do anything
- No money and no maintenance needed
- moves the coast(coatal realinment)
- protects land behind the now mangroves and swamps
What does ICZM atand for?
Integrated Coastal Zone Management
What does ICZM do?
look at citizens’ long-term needs and businesses’ long-term needs,
balancing soft & hard engineering with coastal realignment.
What are the disadvantages of managed retreat?
- land lost to sea
- people may lose their land or livelihoods if farmland is allowed to be flooded.
- someones house could be lost if the area becomes a marshland.
What is costal realignment?
- prioritising certain areas of land, protecting them against floods and erosion.
- some acceptance that this could affect the coastline north or south of the protected area
- Towns are more likely to be protected than grassland
Examples of soft engineering costal defences:
- beach reprofiling
- beach nourishment
- dune regeneration
In managed retreat, what do the flooded sections of coastline eventually turn into?
Marshland
Cost of sea walls:
- Expensive to build and maintain
- create a strong back wash
Which of the following is a soft engineering coastal defence strategy?
Gabions
Groynes
Dune regeneration
Rock armour
Dune regeneration
What is beach reprofiling?
Changing the type of sediment to protect a coastline.
Creating wider beaches slows waves and reduces their energy when they hit the shore
It can damage wildlife living amongst it
What is dune regeneration?
focuses on improving and maintaining sand dunes
Nourishing or planting plants can help to support the dunes and help them resist wind and absorb destructive waves’ energy.
Planting lots of vegitation can be expensive.
What is beach nourishment?
Beach nourishment involves adding more sand to a beach.
Sand can come from another beach(more erosion on the other beach)
Sand and shingle will naturally be pushed up against groynes and this sediment can be put back on other parts of the beaches.
How do gabions work?
Gabions are wire cages full of rocks.
The gabions absorb some of the pressure and energy transferred by waves.
This leads to less erosion, but the wire in the cages is corroded over time.
How do sea walls work?
Sea walls are made out of materials that block waves.
Making them out of hard rock or concrete means that they are more resilient and last longer.
Their shape can be designed to reflect a wave’s power back out to sea, instead of being absorbed by the sea wall head-on.
Sea walls can reduce coastal erosion.
Very expensive
How do groynes work?
Groynes are fences that stick out at 90o to the coast.
Groynes stop the process of longshore drift by trapping material against the fence.
Groynes create wide beaches, which are better for protecting the coastline from erosion and floods.
Building fences is also cheap.
What is rock armour?
a pile of rocks or boulders.
The rocks absorb some of the pressure and energy transferred by waves.
Enormous waves can remove the boulders, but very cheap to build
Examples of hard engineering costal defences:
Gabions
Groyne
Rock armour
Sea wall
4 examples of cotal landforms on the Dorset coast:
Swanage and studland bays
Lulworth cove
Chesil beach
Durdle door
Lulworth Cove is a _____ or cove next to the town of West Lulworth.
Bay
What is the headland between Studland and Swanage bay called?
Foreland
Is there a lagoon behind the bar at Chesil beach?
Yes
What is durdle door?
A famour arch
The headland in Dorset is usually made of what?
Limestone and sandstone
What is chesil beach?
A bar
Studland Bay and Swanage Bay are __. areas of ____ rock that have beaches very close to each other.
- 2
2. Soft
What are the hard engineering and soft engineering costal defences?
Hard engineering:
- rock armour
- Groynes
- sea walls
- gabions
Soft engineering:
- beach nourishment
- beach reprofiling
- dune regeneration
Name some igneous rocks:
- granite
- basalt
Examples of metamorphic rocks:
- slate
- schist
Examples of sedimentary rocks:
Chalk
Clay
Limestone
What is solution?
When the water dissolves certain types of rocks, eg limestone.
What is soil creep?
Slow downward progression of rock and soil down a low grade slope
(Caused by gravity)
What causes landslides?
Someething(rain)make the slope unstable
What is a glacial through
A ushaped valley
What is a truncated spur?
A ridge that goes down to the valley floor from a high point
V shape
What are spits?
When land carries on going out to see with a recurved end
Caused by longshore drift and sharp bends in coast line
Hat is an example of physical weathering?
Freeze thaw
What is an example of chemical weathering?
Carbonation
What is freeze thaw weathering?
When water gets into craks, freezes and expands-breaking the rocks apart.
What is carbonation weathering?
Mising of warer with Co2 to make carbonic acid.
-important for the formation of caves.
What is a rotiational slumping
Saturated soil slimps down a curved surface:
-some rocks are more permeable than others. This means water can get trappes between layers. Causing the soil on top to become saturated and heavy. It becomes to heavy for the sand(at the coast and sinks down Causing the rotational slump/slip
Causes by heavy rain
What causes a rock fall?
Freeze thaw weathering
Why sea levels rise:
Ice melting
Thermal expansion
And possibly storm frequency
What is thermal expansion?
Due to rising tempratures of water, the water level increases and expands -causing sea level rise
What is solution?
Dissolved chemicals often derived from limestone and chalk
What is suspension?
Particles carried(suspended) within water.
What is saltation?
The ‘hopping’ motion of particles that are to heavy to be suspended.
What is traction?
Large pebbles rolled along the sea bed.
What are tors formed by and ehat are they?
Caused by freeze thaw weathering
They are exposed rocks in broken blocks.
What are slides?
When matieral moves down a slope in a straight line.
What are the physical landscape processes?
Climatological processes Erosion Post glacial-river Slope Weathering
What are Climatological processes
how physical processes happen and interact.
What are some landscapes left by post-glacial river processes?
- hanging valleys
- truncates spurs
- glacial troughs
Slides are when material moves down a slope in a _______ line.
Straight
How do destructive waves erode the coast?
Hydraulic power
Abrasion
Attrition
The more joints and faults the_________
Softer and quicker to erode.
_____ movement becomes more likely during storms because the intense rainfall means that soil is more saturated.
Mass
Can sea walla create a strong backwash?
Yes
What are the festures of sand beaches?
Flat and wide
Gradual slope
Examples of mass movement:
Rockfalls
Landslides
Rotational slip.
What is rotational slip?
When saturated sojl slumps down a curved surface.
Where does carbonation weathering mainly happen?
In joints
Which rock type commonly forms wide, flat valleys?
Clay
How does salt weahtering break up rock?
Rock splitting by salt crystal growth in cracks
