Coasts Flashcards
What is mechanical weathering/freeze thaw?
When water gets into cracks freezes and then expands causing the break down of rock
What is chemical weathering?
When rainwater is acidic and falls on the rock a weak chemical reaction takes place causing the rock to break down
What is biological weathering?
Actions of plants and animals widening cracks in rocks causing them to break down
What are the types of mass movement?
Sliding, slumping and rock falls
What is deposition?
When there is not enough energy to carry eroded material any further. It is deposited by constructive waves
What are the types of erosion?
Abrasion, hydraulic action, attrition, solution
What is abrasion?
When fragments of rock are picked up by the waves and thrown against the cliff face causing pieces to fall off
What is hydraulic action?
When waves crash against the cliff air is compressed into cracks under the weight of the water causing the cliff to breakdown
What is attrition?
Rocks and pebbles carried by waves ae reduced in size as they collide against eachother
What is solution?
Chemical action on rocks by seawater. It is most effective on limestone rocks
What are the types of transport?
Traction, saltation, suspension, solution and long shore drift
What is traction?
Large boulders are rolled along the seabed by waves
What is saltation?
Smaller stones are bounced along the seabed
What us suspension?
Sand and small particles are carried along in the flow
What is longshore drift?
- Sediment created from eroded cliffs
- Action of the swash moves in at 45°
- This is in the direction of prevailing wind
- The action of the backwash will bring the Sediment back down at 90° due to gravity
- As waves hit the beach thus zigzag process continues
What is solution (transport)?
minerals dissolved in seawater are carried along in the flow
What is soft rock?
Easily eroded by the sea; cliffs liss rugged and less steep; landscapes include bays
What is hard rock?
More resistant to all types of erosion; cliffs will be steep and rugged; landscapes include wave cut platforms and headlands where caves, arches and stacks form
What does concordant mean?
Coast is made up of the same rock type e.g. White cliffs of Dover
What does discordant mean?
Rock type alternates (hard to soft) perpendicular to coastline to form headlands and bays e.g. jurassic Coast
What are joints and faults?
Joints- small cracks
Faults- large cracks
Both features make the rocks more prone to erosion
What is a destructive wave?
Swash is weak, backwash is strong. Material is dragged into the sea eroding the coast. High energy in stormy conditions
What is a constructive wave?
Material is deposited building up the coast. They gave lower energy and occur in calmer conditions
How does seasonality influence the coast?
Each season has a different impact on the coast. E.g. cold temperatures in winter leading to freeze thaw
What is coastal retreat?
When coastal erosion causes the coastline to move further inland
How does urbanisation impact coastal landscapes?
Weight of buildings make cliffs weaker, changes of drainage increase soil saturation making it more susceptible to mass movement
Whats an impact of agriculture on coasts?
Increases soil erosion and sedimentation. Can create wildlife habitats
How can industry impact coasts?
Increase air, noise and visual pollution. Can destroy habitats for birds, animals and sealife. Brings jobs and wealth to area
What are the different types of coastal defences? HARD ENGINEERING
Sea walls, groynes, rip rap,
What are the different types of coastal defences? SOFT ENGINEERING
Beach nourishment, managed retreat
How do coasts impact humans?
Storm surges, rising sea levels, coastal erosion leads to retreating cliffs and loss of homes, roads and railways. Decreased value of properties dye to difficulties obtaining home insurance
How do humans impact on coasts impact the environment?
Wildlife habitats destroyed, increased deposition further along the coast, coastal flooding
How does stormy weather influence the coast?
-Coasts have strong winds meaning more destructive waves
-Frequent storms damages coastal landforms
-Beach sediment moved along coastline
-Sand dunes can be removed
How does prevailing wind impact coastlines?
From South to West, bringing warm moist air meaning frequent rainfall and strong waves. This leads to increased weathering erosion and mass movement.
What are the advantages or sea walls?
•protects cliff against erosion
•often includes walkways
What are the advantages of groynes?
•quick construction
•stop longshore drift
•£10,000 each (mid range)
•bigger beach = more tourists
What are the disadvantages of seawalls?
•unaesthetic
•expensive to build/maintain (£5000-£10,000 per meter)
What is the disadvantage of groynes?
Effects movement of sediment so can create issues further down the coast by causing increased erosion
What are the advantages of rip rap?
•boulders force waces to break dissipating energy and reducing cliff erosion
•quickly put in place
•cheap to maintain
What are the disadvantages of rip rap?
•transport costs high, rocks usually imported
•can impede access to beach
•do not fit local geology
•expensive £1000 per meter
What are the advantages of beach nourishment?
•beach can absorb more wave energy + protect cost
•sediment obtained locally so fits in/attractive
•easy and cheap to maintain (£100 per meter)
What are the disadvantages of beach nourishment?
•won’t last long if subject to strong swords
•needs constant maintenance
•restricts access to beach
What are the advantages of managed retreat?
•natural process
•allows for increased habitats
Whats the disadvantage of managed retreat?
•impacts function of coastline
What are the impacts of costal erosion on people?
•loss of people’s homes
•cliffs too dangerous for walkers
•disruption to roads and railways
•decreasing value of properties due to difficulties obtaining insurance
When was the Dawlish railway submerged by coastal flooding?
2014
How much does the holderness cost retreat by each year?
2 meters
What is the significance of the holderness coasts location?
•soft boulder clay susceptible to slumping and erosion
•chalk at Flamborough head is more resistance
•location exposed strong waves due to the north sea
What are the physical processes at work on the holderness coast?
•coastal erosion
•mass movement
•transportation
What is the transportation on the holderness coast?
Strong waves move the eroded material away from the coastline deposition happens further south at Spurn Head
What are the human processes at work on the holderness coast?
•rip rap and groynes at mappleton have protected areas from erosion and cliff collapse
•hard engineering in some places prevented transportation meaning more erosion in other areas of coastline
What the changes caused on the holderness coast?
•2m of coastal retreat
•23 villages lost since roman times
•B1242 lost to erosion
