Topic 4 Uk Coasts Flashcards
What is weathering
The breakdown of rocks from where they are
What is erosion
When the rocks are broken down and carried away by something
What is mechanical weathering
The breakdown of rock without changing its chemical composition
What is salt weathering (mechanical weathering)
Sea water gets into cracks in the rock, when the water evaporates salt crystals form. As the salt crystals forms it expands ans puts pressure on the rock. Repetition of this process widens the cracks and causes the rock to break
What is chemical weathering
The breakdown of rock by changing its chemical compostion
What is carbonation weathering (chemical weathering)
Seawater and rainwater have carbon dioxide dissolved in them which makes them weak carbonic acids. When carbonic acids reacts with rock that contains calcium carbonate, in warm and wet conditions, rocks are dissolved.
What is biological weathering
The breakdown of rock by living things
Give an example of biological weathering
Plant roots break down rocks by growing into cracks pushing them apart
What is mass movement
The shifting of rocks and loose material down a slope
What are the three types of mass movement
Slides
Slumps
Rockfalls
What is hydraulic action
Waves crashing against rock and compress the air in the cracks. Repeated compression puts pressure and widens the cracks making bits of rock fall off.
What is abrasion
Eroded particles in the water scrape and rub against rocks removing small pieces of rock.
What is attrition
Eroded particles in the water smash into each other and break into smaller fragments. Their edges get rounded off as they rub together
What are the two types of coastlines
Concordant
Discordant
What are joints and faults
Cracks and weeknesses in the rock
What are discordant coast lines
Alternating bands of hard and soft rock that face the rock
What are concordant coast lines
Alternating bands of hard and soft rock parallel to the coast
What erosional landforms at discordant coastlines are commen
Bays and headlands because the bands of rock are being eroded at different rates
What erosional landforms are common concordant coastlines
Concordant coastlines erode at the same rate so there are less erosional landforms
What are 5 charactaristics of destructive waves
Destructive waves are high, steep, stronger backwash, weaker swash and have a high frequency
How does a bay and headland noccur
The less resistent rock (soft rock) is eroded quickly creating a bay whilst the more resistent rock (hard rock) is eroded slower and is left jotting out forming a headland
Explain the process of cracks,cave,arch to stack.
Hydraulic action and abrasion occur creating cracks, repeated erosion and enlargment of the cracks cause a cave to form, more erosion deepens the cave until it breaks through the headland creating an arch. Erosion continuos to wear away the rock untill it eventually collapses forming a stack.
Explain the process of longshore drift
The swash carries materiel up the beach, the same direction as the waves. The backwash carries the material down the beach at rught angles towards the sea creating zig zags down the shore
What is deposition
When material being carried by the sea water slows down so is dropped on the coast but not collected back by the backwash
What are constructive waves
Waves thta deposit more material than they erode
Give 5 characteristics of constructive waves
They are low, long,low frequency, stronger swash, weeker backwash
What are spits
They form at sharp bends on the coastline. Longshore drift transports sand and shingle past the bend. The material builds up forming the spit. Strong winds and waves curvee the end of the spit creating a recurved end. The sheltered area on the other side of the spit is protected and lots of material gets accumulated meaning plants can grow there.
What is a bar
When a spit joins two headlands together. A lagoon is formed behind the bar.
What are direct effects on the coast
The immediate result of human activities . Building coastal defences will prevent erosion.
What are indirect effects on the coast
They happen as a resultbof direct effects. For exampple building coastal defences will stop erosion in one place but it can increase erosion further along the coast
Explain one way agriculture has an effect on coastal landscapes
Agricultural land has a low economic value and therefore is usually left unprotected.
Explain one way development has an effect on coastal landscapes
Coastal areas are popular places to live and work so they often have lots of development and may have more coastal defences than other places because people want to protect their homes and buisnesses.
Explain one way industry has effect on coastal landscapes
Gravel has been extracted from some beaches for use in the construction industry. This has removed material from the coast and increased risk of erosion due to less protection
Explain one way coastal managment has an effect on the coastal landscape
Some managment strategies alter sediment movement which reduces the amount of protective beach material further down the coast which increases erosion
What is the impact of rising sea levals
They pose a threat to low lying and coastal areas. They can cause higher tides that will cause floods, remove large amount of material from beaches meaning they become more vunerable to erosion.
What is the impact of storm frequency
Storm give the sea more erosional power therefore rock will be more vulnerable to erosion. The sea will also have more energy to transport material starving some areas of material leading to them being vulnereable to flooding.
How can low coasts impact people
Coastal industries may need to shut down due to floods. A risk of damaged infustructure like roads and rail networks.
How can high coasts cause threats to the environments
Ecosystems will be affected because sea water has a high salt content. This can damage or kill organisms in an ecosyste. The flood water can drown some plants and trees.
What is hard-engineering
Man-made structures built to reduce flooding and erosion
Soft engineering
Schemes set up to reduce the effects of flooding and erosion
What is a sea wall and its benefits and costs
A wall made out of hard material that reflects waves back to the sea. It prevents erosion to the coast and can act as a barrier to prevent flooding. Sea walls are very expensive to build and maintain.
What are groynes and what are their benefits and costs
Wooden or stone fences that are built at right angles to the coast. They trap material transported by longshore drift. They create wider beaches and slows waves giving greater protection from flooding and erosion. They are fairly cheap. They starbe beaches down the shore making them narrow and vunerable to erosion.
What is beach replenishment and benefits and costs
Sand and shingle from one part of the beach added to another part of the beach. It creates wider beaches which slow the waves preventing flooding and erosion. Taking material from the seabed can kill organisms and very expensive due to the repetition needed for the defence.
What is slope stabalisation and what are its benefits and costs
Slopes are reinforced by covering the slope with metal netting. It prevents mass movement by increasing the strength of the slope. Slope stabalisation is very expensive and can be very difficult to install
