Topic 4: UK Landscape And Coats Flashcards
Sedimentary rock
Made from layers of sediment deposited by the river or the sea and compacted.
Limestone, chalk and clay
Igneous rock
Created from volcanic activity when magma or lava cools forming rocks made of crystals that are usually hard.
Granite
Metamorphic rock
These are existing rocks that have been changed by extreme heat or pressure. They are usually compromised of layers and are very hard.
Slate and schist
Upland areas
• Hilly and mountainous areas
• North and West Snowdonia or Lake District
• Harder rocks that resist erosion e.g. slate and schist
• Gradient of the land is steep
• Climate is cooler and wetter
• Rough vegetation in the thin soils and harsh climate
• Land uses include sheep farming, quarrying and tourism
Lowland areas
• Flatter land with gentle rolling hills
• South and East Cambridgeshire, the Weald
• Softer rocks that erode more easily e.g. chalk and clay
• Gradient of the land is flatter
• Climate is warmer and drier
• Fertile soils support grassy meadows and forests
• Land uses include dairy and arable farming, most urban areas and industry are found here.
How has the UK landscape been influenced by physical processes?
1) Tectonic process
2) Glacial processes —> U shaped valleys
Tectonic processes
Convection currents uplift a line or weakness and the land snaps and rises and forms a fault scarp.
Glacial processes
• U-shaped valleys started as V-shaped valleys
• Ice accumulated in the V-shaped valleys in the ice age and forms glaciers.
• As they move through the valley there is plucking and abrasion, sand paper like effect, this movement continues until valleys eventually become less steeper and more U-shaped
• These glaciers can form misfit streams.
What physical processes can change a landscape?
1) Weathering
2) Deposition
3) Geology
4) Erosion
5) Post glacial river processes
6) Mass movements
7) Climate
8) Tectonic processes
Mass movements
• Sliding
• Slumping
• Soil creep
• Rock falls
Sliding
Soil becomes saturated, becomes really heavy and slides down the hillside
Slumping
Cliffs are made out of different layers or rock.
• The first layer is permeable rock and allows rain to infiltrate, then percolate onto it.
• The second layer is clay. This is impermeable so water builds up to make the cliff saturated.
• Saturated rock becomes heavy and unstable.
• A slip plain (crack) develops and a section of the click eventually slumps.
• Sediment is eventually removed by longshore drift and wave action.
Soil creep
Soil slowly slides down the hillside.
Sub ariel slope processes
Mass movements
Weathering
Biological weathering
Tree roots grow between cracks in rocks and force them apart.
Chemical weathering
(Acid rain)
Caused by a chemical reaction when rainwater hits rock and begins to break it down.
Mechanical weathering
(Freeze thaw)
Rocks are broken down (physically) without changing their chemical composition.
Rock falls
Suddenly when pieces of rock fall from cliff that has been weathered or undercut.
Erosion
The breaking down and wearing away of rocks on a coastline.
Transportation
The movement of sediment along a coastline.
Deposition
The deposition of sediment, as a result of waves loosing their energy and ability to carry sediment any further.
It happens when the swash is stronger than the backwash and is associated with constructive waves.
Destructive waves
• Weak swash and strong backwash
• The strong backwash recodes sediment from the beach
• The waves are steep and close together
• High energy
Constructive waves
• Strong swash and weak backwash
• The strong swash brings sediment to build up the beach
• The backwash is nor strong enough to remove the sediment
• Low energy
• Waves are low and further apart
How are waves created?
Friction of the wind on the surface of the sea.
3 main influence’s on the strength of a wave
• Fetch
• Strength of wind
• How long the wind has been blowing for
4 types of erosion
Hydraulic action
Abrasion
Attrition
Solution
Hydraulic action
Sheer power of waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.
Abrasion
Pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.
Attrition
This is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.
Solution
This is when sea water dissolves certain types of rocks.
Discordant coastline
Rock is perpendicular to the coastline.
Discordant coastline landforms
1) Headlands and bays
2) Caves, arches, stacks and stumps
Headlands and bays
• Headlands and bays form when there are alternating bands of hard and soft rock.
• Wave action erodes the less resistant rock quicker due to hydraulic action and abrasion to produce bays.
• The more resistant rock is left sticking out as a headland.
• Wave energy is now concentrated on the headland and the bay becomes sheltered.
• This results in the formation of beaches as sediment is deposited.
Caves, arches, stacks and stumps
1) Large crack opened up by hydraulic action
2) The crack grows into a cave by hydraulic action and abrasion
3) The cave becomes larger
4) The cave breaks through the headland forming a natural arch
5) The arch is eroded and collapses
6) This leaves a tall rock stack
7) The stack is eroded forming a stump
Old Harry’s rock, Swanage
How can geological structure influence the rate of erosion?
• Joints and faults
• Discordant/concordant coastlines
Concordant coastline
Rock is parallel to the coastline.
Concordant coastline landforms
• Coves
• Wave cut platforms
Coves
1) Destructive waves hit the Concordant coastline in the winter and result in hydraulic action and abrasion exposing faults and joints in the resistant limestone.
2) Eventually the waves erode through to the less resistant clay
3) Erosion is now rapid in all directions creating the circle shape of the cove
4) Erosion eventually slows down as the more resistant chalk layers are reached and a cove has been produced
Lulworth cove Dorset
Wave cut platforms
1) The sea creates a wave cut notch through the waves undercutting the cliff through hydraulic action and abrasion.
2) The cliff retreats inland because the waves erode the less resistant rock.
3) A wave cut platform is left because the base of the cliff is left after the cliff is forced to retreat.
Sub aerial processes
Sub aerial processes refer to those that occur on the cliff face as opposed to the cliff foot. They are influenced by weather and climate as opposed to the sea.
What factors have an effect of rates of erosion?
• Cold winter temperatures —> More freeze thaw weathering, cliff becomes less stable and retreats
• More rain in winter —> More slumping as ground becomes more saturated, higher rate of cliff retreat
• Prevailing wind direction —> Stronger waves with more energy, more erosion
• More frequent storms in winter —> More destructive waves, more erosion
Longshore drift
Movement of material along a coast.
Longshore drift process
Waves approach the coast at an angle because of the direction of prevailing wind. The swash will carry the material towards the beach at an angle. The backwash then flows back to the sea, down the slope of the beach. The process repeats itself along the coast in the zigzag movement.
Deposition landforms
Beaches
Spits and bars
Beaches
Beaches are formed from deposition when the sea looses energy and it drops sediment along the coastline. This happens when the swash is stronger than the backwash and is associated with constructive waves.
Spit
1) Sediment is moved along the coast by longshore drift.
2) When there is a change in direction of the coastline, longshore drift continues.
3) When there is a change or break in the coastline, a slight drop in energy happens and so waves loose energy, depositing material at a faster rate than it can be removed. As deposition continues, material gradually builds up and a spit is formed.
4) The largest sediments are deposited first. Finer material is carried further along the spit before being deposited as it’s lighter.
5) The spit grows and may form a hook if the wind direction changes.
6) In the slack (more still) water behind the spit, more deposition takes place and a salt marsh may develop with salt loving plants helping to trap sediment. New land is eventually created.
Hurst castle spit Hampshire
Bars
A bar is a ridge of sand or shingle across the entrance to a bay or river mouth. A bar begins to form in the same way as a spit. Material is transported along the coast by longshore drift and deposited when there is a change or break in the coastline. Deposition continues in a line right across the entrance to the bay or river mouth. This means that water is trapped behind it too form a lagoon.
Slapton sands, Devon
How have humans influenced the coast?
1) Coastal management
2) Agriculture
3) Industry
4) Tourism
Coastal management
Large cities and industrial areas have high economic value leading to hard-engineering coastal management techniques which prevent the coastline from changing naturally.
Agriculture
Many farms divert or control coastal rivers for irrigation, which can result in a decreased supply of beach material to the shoreline, leading to erosion.
Industry
Ferry and shipping ports are located all along the coastline, built to process safe mooring and navigation for vessels, but it can result in the trapping of sediment resulting in sediment starvation.
Tourism
Coastal management plays a massive part in local economics. In order to protect tourist beaches, structures like groynes are built to trap sand. But removing sediment from the system results in increased erosion further along the coast.
Hard engineering techniques
Built structures to try and control natural processes.
• Groynes - wooden or rock structures that are positioned along a beat at right angles from the coast. They trap sediment that is moved by LSD and build up the beach.
• Sea walls - concrete barrier that is recurved to reflect the waves and their energy.
Soft engineering techniques
Allow and encourage natural processes to occur
• Slope stabilisation - drains are installed at the top of the cliff to remove groundwater. Often wire mesh is placed over it and long nails pushed into the cliff to hold it in place.
• Beach nourishment - sand is dredged from the seabed offshore and then pumped onto the beach. The restored beach is a natural barrier and absorbs wave energy.
Advantages of hard engineering
• Protects the base of the cliffs, land and buildings against erosion
• Longer lasting
• Can create jobs in maintenance
Disadvantage of hard engineering
• Expensive
• Unatural/ugly
Advantages of soft engineering
• Asthetically pleasing/more natural processes
• Cheaper
• Incorporates habitats as well as stopping erosion
• More eco friendly
• Attracts more tourists
Disadvantages of soft engineering
• Don’t last as long
• Less effective at stopping erosion
Cost benefit analysis
• Takes into consideration the value of the land and how much there is to loose and then works out what can be spent to protective it.
• The higher the value of the land, the greater the money that can be spent protecting it.
CBA = Value of property / Cost of defences
Coastal management strategies
• Hold the line e.g. Barton-on-sea - Stop more erosion and protect current coastline using a mixture of hard and soft engineering.
• Advance the line - Reclaim land and protect it using hard and soft engineering
• Strategic realignment - Work with nature to allow gradual erosion using natural ecosystems
• Do nothing
Challenges for coastal landscapes
• Flooding
• Storm frequency increased
• Increased storm intensity/severity
• Rising sea levels
• More coastal erosion
• Ocean acidification - coral bleaching
How have humans influenced the Uk?
Agriculture
Forestry
Settlement
