Paper 1: Physical landscapes in the UK Flashcards
What is a wave?
A wave is a disturbance on the surface of the sea or ocean, in the form of a moving ridge or swell.
What causes waves?
Waves are caused by the transfer of energy from the wind to the sea due to the friction of wind on the water€™s surface.
What 3 factors affect the size of waves?
Fetch, wind speed and wind duration
What is the fetch of a wave?
The distance a wave has travelled
What word describes the movement of a wave up a beach?
Swash
What word describes the movement of a wave down a beach?
Backwash
Identify the two types of wave.
Destructive and constructive
Which type of wave builds beaches?
Constructive
Which type of wave has a strong swash and a weak backwash?
Constructive
Describe the swash and backwash of a destructive wave.
Weak swash, strong backwash
What is weathering?
Weathering is the breakdown of rock in situ by the action of rainwater, extremes of temperature, and biological activity.
What is mechanical weathering?
Mechanical weathering is the breakdown of rock without changing its chemical structure (composition).
Describe the processes of freeze-thaw weathering.
Freeze-thaw weathering occurs when rocks are porous (contain holes) or permeable (allow water to pass through). Water enters the rock and freezes. The ice expands by around 9%. This causes pressure on the rock until it cracks. Repeated freeze-thaw can cause the rock to break up.
Describe the characteristics of rock that has recently gone through freeze-thaw.
Recently weathered rock can be seen at the foot of chalk and limestone cliffs and is easily identified because it is angular.
What is chemical weathering?
Chemical weathering is the breakdown of rock through changing its chemical composition.
What is mass movement?
Mass Movement is the downhill movement of cliff material under the influence of gravity.
Identify 4 types of mass movement.
Rock fall, landslide, mudslide and slumping
Describe the process of slumping
The soft boulder clay holds rainwater and run-off. Waves erode the base of the cliff creating a wave-cut notch. The clay becomes saturated and forms a slip plane. The weight of the saturated cliff causes it to slump.
Large blocks of rock sliding downhill is which type of mass movement?
Landslide
Which type of mass movement involves fragments of rock breaking away from the cliff face, often due to freeze-thaw weathering?
Rockfall
Which type of mass movement involves saturated soil and weak rock flows down a slope, typically where cliffs are made up of boulder clay?
Mudslide / mudflow
What is coastal erosion?
Coastal erosion is the wearing away of the land by the sea.
Identify the main processes of coastal erosion.
Corrasion, abrasion, hydraulic action, attrition and corrosion/solution.
Give an outline of what corrasion involves.
Corrasion is when destructive waves pick up beach material (e.g. pebbles) and hurl them at the base of a cliff. Over time this can loosen cliff material forming a wave-cut notch.
Give an outline of what abrasion involves.
Abrasion occurs as breaking waves, concentrated between the high and low watermarks, which contain sand and larger fragments wear away the base of a cliff or headland. It is commonly known as the sandpaper effect. This process is particularly common in high-energy storm conditions.
Give an outline of the steps involved in hydraulic action.
Waves hitting the base of a cliff causes leads to air compression in cracks, joints and folds in bedding planes causing repeated changes in air pressure. As air rushes out of the crack when the wave retreats it leads to an explosive effect as pressure is released. This process is supported further by the weakening effect of weathering. Material breaks off cliffs, sometimes in huge chunks. This process is known as hydraulic action.
What is attrition?
Attrition is when waves cause rocks and pebbles to bump into each other and break up.
What is corrosion/solution?
Corrosion/solution is when certain types of cliff erode as a result of weak acids in the sea.
What is coastal transportation?
The movement of sediment and beach material through wave action.
Identify the 4 main processes of coastal transportation.
Solution, suspension, saltation and traction
What is traction?
Traction – large pebbles and boulders are rolled along the seafloor.
What is saltation?
Saltation – beach material is bounced along the seafloor.
What is suspension?
Suspension – beach material is suspended and carried by the waves.
What is solution?
Solution – material is dissolved and carried by the water.
What is the zig-zag movement of material along the shore by wave action called?
Longshore Drift
Describe how longshore drift transports material.
Waves approach the beach at an angle. The swash carries material up the beach in the direction of the prevailing wind. The backwash carries material back into the sea at right angles. This process slowly moves material along the beach.
What is coastal deposition?
Coastal transportation involves material being transported by the sea being deposited or dropped.
Why does coastal deposition occur?
Wave energy reduces leading to material being deposited.
Give three conditions that lead to coastal deposition happening.
Any three from: Waves enter an area of shallow water / waves enter a sheltered area, e.g. a cove or bay / there is little wind / a river or estuary flows into the sea reducing wave energy / there is a good supply of material and the amount of material being transported is greater than the wave energy can transport.
What is a headland?
A headland is a cliff that sticks out into the sea and is surrounded by water on three sides.
What is a bay?
A bay is an inlet of the sea where the land curves inwards
Do headlands form along concordant or discordant coastlines?
Headlands form along discordant coastlines
What is a discordant coastline?
A discordant coastline is where the geology alternates between strata (bands) of soft and hard rock.
What is a concordant coastline?
A concordant coastline is where the same rock runs along the length of the coast. Concordant coastlines tend to have fewer bays and headlands.
Explain the formation of bays and headlands.
The bands of soft rock, such as sand and clay, erode more quickly than those of more resistant rock, such as chalk. This leaves a section of land jutting out into the sea called a headland. The areas where the soft rock has eroded away, next to the headland, are called bays.
Why are sandy beaches likely to form in bays?
Sandy beaches are often found the sheltered bays where waves lose energy, and their capacity to transport material decreases resulting in material being deposited.
What is a wave-cut platform?
A wave-cut platform is a wide, gently sloping surface found at the base of the cliff and extends into the sea.
Explain the formation of a wave-cut platform.
A wave-cut platform is formed when the sea erodes a weakness in the base of the cliff by hydraulic action and abrasion. As the notch becomes larger the cliff becomes unstable and collapses as the result of gravity The cliff retreats inland. The material from the collapsed cliff face is eroded and transported away. This leaves a wave-cut platform. The process repeats over time.
What are the steps in the formation of a stump?
Crack - cave - arch - stack - stump
Identify your case study location for landforms of coastal erosion.
Jurassic coast - Dorset (Old Harry Rocks)