Changing Landscapes: Coasts Flashcards
Name 2 types of sedimentary rocks.
Chalk, sandstone, limestone
Name 2 types of igneous rocks.
Granite, basalt
Name 2 types of metamorphic rocks.
Marble, slate
Name a characteristic of sedimentary rocks.
Formed in layers, can contain fossils, formed from layers of sediment being compressed…
Name a characteristic of igneous rocks.
Hard, formed in crystals, formed from volcanic activity…
Name a characteristic of metamorphic rocks.
Formed from great heat and pressure exerted onto igneous or sedimentary rocks, can appear squashed, can have large crystals…
What types of rock mostly cover the north-west of the UK?
Metamorphic and igneous
What types of rock form the upland landscapes?
Harder metamorphic and igneous
What types of rock mostly cover the south-east of the UK?
Sedimentary
What types of rock form the lowland landscapes?
Softer sedimentary
How did tectonics create mountains in the UK?
Millions of years ago, when the UK was close to two plate boundaries, plates converged to form the upland landscapes of the Scottish Highlands, the Lake District and north Wales.
What is mechanical weathering?
Where cracks in rocks fill up with water which freezes and melts. This process repeats to expand the cracks until, eventually, the rock breaks apart
What is chemical weathering?
Rainwater absorbs carbon dioxide from air, rainwater and alkaline rocks which produces a chemical reaction to weather away rocks
What is biological weathering?
Plant and animal activity weathering away rocks (e.g: plant roots widening cracks in rocks, burrowing animals/nesting birds weakening and decaying rocks)
Describe the process of longshore drift.
- Waves approach coast at an angle due to direction of prevailing wind
- Swash carries material towards beach at an angle
- Backwash flows back to sea
- Process repeats, carrying sediment in a zigzag motion
What is slumping?
Where a river erodes the bottom of a valley slope, making it steeper. This causes the material above to slide downwards
What is sliding?
Where sediment moves down in a slope. Sediment shifts in a straight line (horizontally)
What is abrasion?
Rocks scrape against a cliff face, giving a sandpaper effect
What is attrition?
Rock fragments and pebbles bounce off each other in waves to break each other down into smaller particles
What is hydraulic action?
Fragments of rock are picked up by the force of wave and thrown at the cliff face -> pieces broken off and become further eroded
What is solution?
Chemical reaction on rock by seawater - small particles dissolved into water
What is solution?
When minerals in rock are dissolved and carried by the sea
What is suspension?
Small particles suspended in the flow of water
What is saltation?
Sediment bounced along the seabed
What is traction?
Pebbles and larger sediments rolled along the seabed
Name 3 characteristics of constructive waves.
Strong swash, weak backwash, have less energy, encourage deposition, low in height…
Name 3 characteristics of destructive waves.
Strong backwash, weak swash, taller, breaks frequently, leads to coastal erosion…
What sort of coastline are headlands and bays formed at?
Discordant
How are headlands formed?
Softer rock and hard rock eroded by hydraulic action and abrasion.
Softer rock eroded quicker as less resistant.
This leaves the harder, more-resistant rock as a headland.
How are bays formed?
As waves hit a headland, energy is lost so it loses sediment. This means that sand carried by the waves is deposited either side of the headland, creating a bay.
How are wave-cut platforms formed?
- At high tide, cliff face eroded by hydraulic action and abrasion.
- Waves undercut cliff, creating a wave-cut notch.
- Notch further eroded -> cliff above collapses.
- Debris from collapse removed by waves.
- This continues so that the cliff face + coastline retreat inland.
- Leaves behind a wave-cut platform.
What is a wave-cut platform?
A gently-sloping rocky area left at the bottom of a retreating cliff
Describe how cracks in cliffs turn into stumps.
- Hydraulic action and abrasion erode a crack or fault in cliff until it becomes a cave
- Backwall of cave is eroded until it becomes an arch
- Arch erodes further and top is unsupported so collapses into stack.
- Stack is undercut by HA + abrasion -> collapses into stump.
What is a spit?
A long, thin ridge of sediment deposited in shallow water
Describe how spits are formed.
- Sediment transported along beach via LSD in direction of prevailing wind
- Change in shape of coastline -> sediment deposited.
- Change in wind direction gives the spit a hooked end.
- Waves cannot get past a spit -> water behind sheltered
How are salt marshes/mud flats formed?
Behind a spit:
Waves cannot get past a spit so water behind is sheltered.
Silts deposited here form salt marshes or mud flats.
How are bars formed?
- Gap in coastland with water in it (such as a spit)
- LSD carries sediment across front of bay
- Deposited material eventually joins with other side of bay, creates strip of sediment
- Strip of sediment blocks off water in bay -> lagoon.
How do rising sea levels affect the coastline?
High tides can take away sediment
How do storm surges affect the coastline?
Strong winds eroding sediment
What is our case study for Changing Landscapes?
Dawlish Warren Spit
What is the location of the Dawlish Warren Spit?
Devon, England, near town of Dawlish. Sandy beach.
How is the Dawlish Warren Spit important socially?
Tourist destination, nearby railway line at risk from sea
How is the Dawlish Warren Spit important economically?
Tourist destination
How is the Dawlish Warren Spit important environmentally?
Diverse ecological site with high biodiversity -> habitat for many
How has human activity caused change at Dawlish Warren?
Hard engineering methods, boulders on spit, houses built cause more erosion
How has the physical environment caused change at Dawlish Warren?
High tides, strong winds, storms, erosion -> change in shape, etc
Name 3 (coastal) hard-engineering strategies.
Sea wall, rip-rap, groynes
Name 2 advantages of sea walls.
- Effective at stopping sea
- Often include a walkway or promenade
Name 2 disadvantages of sea walls.
- Obtrusive and unnatural to look at
- Can restrict beach access
- Expensive to build and maintain
- Can increase erosion of beach
Name 2 advantages of rip-rap.
- Force waves to break -> dissipate energy, protecting cliffs
- Quickly assembled
- Cheap and easy to maintain
Name 2 disadvantages of rip-rap.
- Boulders often transported from far -> transport costs can be high
- Don’t fit with local geology
- Can restrict beach access
Name 2 advantages of groynes.
- Quick to construct
- Trap sediment so broaden beach
- A bigger beach can attract more tourists
Name 2 disadvantages of groynes.
- Interrupt natural processes
- Obtrusive to look at
What is a sea wall?
Concrete wall around 3-5m high - lessen impact of erosion
What is rip-rap?
Large boulders piled at foot of cliff or top of beach - lessen impact of erosion
What are groynes?
Wooden or rock structures built along beach at right angle - lessen impact of erosion
Name 2 (coastal) soft-engineering strategies.
Beach nourishment, managed retreat
What is beach nourishment?
Sand/shingle added to beach to make it higher
Name 2 advantages of beach nourishment.
- Protects coastline easily - beach absorbs more wave energy
- Sediment local - blends in
- Cheap and easy to maintain
- Encourages tourism
Name 2 disadvantages of beach nourishment.
- High maintenance
- Work often done in summer - can disrupt beachgoers
What is managed retreat?
To let the land flood and erode as natural.
Name 2 advantages of managed retreat.
- Cheap
- Natural process
- Saves - more disposable income
Name 2 disadvantages of managed retreat.
- Losing land
- Losing businesses, potentially homes, farmland
What is a concordant coastline?
Bands of resistant and less resistant rock run parallel to coastline
What is a discordant coastline?
Bands of resistant and less resistant rock run perpendicular to coastline
How are coves formed?
- Harder rock acts as a barrier to less resistant rock behind.
- When breached, less resistant rock eroded
- Which creates a circular area of water with a narrow entrance to the sea
What is the name of a coastline that we have studied?
The Holderness Coast
Why is the Holderness Coastline so vulnerable to erosion?
Retreats around 1-2m a year due to numerous physical factors:
1. Susceptible to strong prevailing winds from North Sea
2. Discordant coastline, much of it is soft rock so it is vulnerable to erosion
Name 3 negative impacts on the Holderness Coast due to erosion.
- 29 villages lost
- Damage to buildings
- Decline in tourism
- Loss of farmland and wildlife
What is an SMP?
Shoreline Management Plan
How has an SMP been used at the Holderness Coast?
£2 million SMP introduced at Mappleton, Holderness Coast:
-> Rip-rap and 2 groynes added which:
1. Reduced risk of erosion, sediment no longer transported downstream
2. However coastal erosion has increased downstream of Mappleton
When were the upland landscapes of the UK formed?
~520 million years ago
What happened 50-60 million years ago?
2 diverging tectonic plate boundaries caused the Atlantic Ocean to open up.
What is an example of an upland landscape?
Dartmoor
What are Dartmoor’s tors formed as a result of?
Granite intrusions becoming vulnerable to processes of weathering, erosion, mass movement
What is an example of a lowland landscape?
North and South Downs
How was the landscape in/between the North and South Downs formed?
Cretaceous Period (75 million years ago) - marine deposits created a chalk dome.
Fluvial erosion has eroded the centre of the dome over many years, leaving escarpments either side of the dome
How much of the South Downs National Park is occupied for farming?
85%
Name 2 advantages of farming in South Downs.
- Supports local economy
- Supports rare species
- Supports formation of hedgerows
Name 2 disadvantages of farming in South Downs.
- Damage to habitats
- Decline in grassland due to fertilisers used
How has human activity affected the South Downs National Park?
- Deforestation
- Farming
