Unit 1C- Coastal Landscapes In The UK Flashcards
What is mechanical weathering and an example?
The breakdown of rock without changing its chemical composition.
Freeze-thaw weathering
What are four steps of freeze-thaw?
1) Water enters rock that has cracks, e.g. granite
2)When the water freezes it expands, which puts pressure on the rock
3)When the water thaws it contracts, which releases the pressure on the rock
4)Repeated freezing and thawing widens the cracks and causes the rock to break up
What is chemical weathering and an example?
The breakdown of rock by changing its chemical composition
Carbonation weathering
What are two steps of carbonation weathering?
1) Rainwater has carbon dioxide dissolves in it
2)This reacts with a rock that contains calcium carbonate, e.g. limestone
What are the three different types of mass movement?
Slides, slumps and rockfalls
Explain the three different types of mass movement?
Slides – material shifts in a straight line along a slide plain
Slumps – material rotates along a curved slip plane
Rock falls – material breaks up and falls down a slope
What do destructive waves have?
High frequency and are high and steep
The backwash is more powerful than the swash, so material is removed
What do constructive waves have?
Low frequency and are low and long
The swash is more powerful than the backwash, so material is deposited
Explain the three processes of erosion
Hydraulic action– Waves crash against rock and compress the air in the cracks
Abrasion – eroded particles in the water scrape against rock, removing small pieces
Attrition – eroded particles in the water collide, break into small pieces and become more rounded
What is longshore drift?
When prevailing winds hit the coast at an angle.The swash carries material up the beach, in the same direction as the waves.The backwash then carries material down the beach at right angles back towards the sea. Overtime, material zigzags along the coast.
Explain the four processes of transportation
Traction – large particles are pushed along the sea bed by the force of the water
Suspension – small particles are carried along in the water e.g clay
Saltation – pebble sized particles are bounced along the sea bed by the force of the water
Solution – soluble materials dissolved in the water and are carried along e.g limestone
How does deposition occur?
When water carrying sediment loses energy and slows down
What are discordant coastlines?
They are made up of alternating bands of hard and soft rock at right angles to the coast
What are concordant coastlines?
They are alternating bands of hard and soft rock that are parallel to the coast
How do headlands and bays form along discordant coastlines?
The less resistant rock is eroded faster, forming a bay with a gentle slope.
Because the resistant rock erodes more slowly, it juts out, forming a headland with steep sides
What is an example of an arch we have studied?
Durdle Door, Dorset
What is an example of a stack that we have studies?
Old Harry, Dorset
What are the four stages of headlands eroding to form caves, arches, stacks and stumps?
1) Waves crash into the headlands and enlarge the cracks by hydraulic power and abrasion
2) Repeated erosion causes a cave to form
3) Continued erosion deepens the cave until it breaks through the headland to form an arch
4) The rock supporting the arch eventually collapses, this forms a stack, then a stump overtime
How do wave-cut notches and wave cut-platforms form?
Erosion causes a wave-cut notch to form, repeated erosion causes the rock above the notch to eventually collapse. Collapsed material is washed away and a new wave-cut notch starts to form, after repeated collapses the cliff retreats, leaving a wave-cut platform.
What is the difference between sand beaches and shingle beaches? (constructive waves)
Sand beaches are created by low energy waves and are flat and wide- sand particles move back down the beach, long gentle slope
Shingle beaches are created by high energy waves and are steep and narrow- larger shingle stay behind, steep slope
How do spits form?
Longshore drift transports sand and shingle past the bend and deposits it in the sea. strong winds and waves can curve the end of the spits. Overtime,the sheltered area can become marsh land
How do bars form?
A Bar forms when a spit joins two headlands together.
The bay between the headlands gets cut off from the sea, forming a lagoon.
How do sand dunes form?
Sand deposited by Longshore drift is moved up the beach by the wind.
Obstacles decrease wind speed so sand is deposited, forming small embryo dunes.
Vegetation stabilises the sand, forming foredunes and eventually mature dunes.
What is the difference between hard and soft engineering?
Hard engineering are man-made structures, whereas soft engineering uses knowledge to reduce the effects of flooding and erosion.
