Physical Geography- The Costal Zone Flashcards
How are headlands and bays formed?
Some types of rock are more resistant to erosion than others
Headlands and bays form where there are alternating bands of resistant and less resistant rock along the coast
Less resistant eg clay erodes quicker
More resistant eg chalk leaves a headland
How does freeze thaw weathering work?
Temp alternates between about and below 0
Water gets into cracks
Freezes-expands-pressure on rock
That’s-contracts-releases pressure
Repeated freeze thaw widens cracks and causes rocks to break up
What is carbonation?
Rain water has dissolved co2 which makes it a weak carbonic acid
Carbonic acid reacts with rock that contains calcium carbonate eg limestone, which dissolves the rock
Give an example of a spit
Spurn Head, Yorkshire
What is mass movement?
When material shifts down a slope as one under the influence of gravity
Rapid retreat of cliffs
More likely to happen when material is full of water (lubricant)
Give the main characteristics of a constructive wave
Low frequency
Low and strong
Powerful swash
Weak backwash
Give the main characteristics of a destructive wave
High frequency
High and steep
Powerful backwash
Which means material is removed from the beach
Why is sea level rising? (2)
Melting ice- eg the Antarctic ice sheet
Heating oceans- thermal expansion
Name and define the 4 processes of transportation?
Traction- larger particles pushed along sea floor
Suspension- small particles like silt and clay are carried along in water
Saltation- pebble sized particles bounce along sea bed by force of water
Solution- dissolved materials carried along
How does long shore drift occur?
waves follow the direction of the prevailing wind
They usually hit the coast at an angle
The awash carries material up the beach, the the wave direction
Then backwash carries material Down the beach at right angles to the sea due to gravity
What are the two types of mass movement?
Slides- straight line
Slumps- shifts with a rotation
How does a headland go to a crack, cave, arch, stack, stump?
Cracks are opened up by waves mainly by hydraulic power and abrasion until a cave forms
Repeated erosion makes a arch (e.g Durdle Door, Dorset)
Eventually arch collapses to form stack
(Eg old harry)
What increases the amount of deposition on a beach? (3)
Lots of erosion elsewhere on the coast- lots of material available
Lots of transportation of material into an area
Constructive waves
Social impacts of flooding in the Maldives?(2)
Houses damaged or destroyed
Less freshwater available
Name and define the 5 processes of erosion
Hydraulic Power- waves smash against rock and compress air
Abrasion-sand papering
Corrasion-fragments of rock gauging cliff face
Attrition-rocks in sea collide to form smaller pebbles
Solution-rocks dissolved by seawater
What’s the case study for costal habitats?
Studland bay, Dorset
What’s the difference between a sand and shingle beach?
Sand- flat and wide. sand particles are small and the weak backwash can move them down the beach, creating a long gentle slope
Shingle- steep and narrow. Large shingle particles cannot be moved by weak backwash, so build up to create steep slope
How much is sea level rising by per year?
2mm
What is mechanical weathering
Breakdown of rock without changing its chemical composition. Insitu
Define soft engineering
A sustainable approach to managing the coast without using artificial structures
How are bars formed? What does it create?
When a spit joins two headlands together
A lagoon forms behind the bar
How are grebes and snakes and lizards adapted to Studland bay?
Grebes- birds five underwater to find food in the sea. feet are far back on body to help dive and be streamlined
Snakes and lizards- thick scaly skin to reduce water loss from their bodies. Also protects them from rough undergrowth on the heathland
What is rock armour and what are its advantages and disadvantages?
Piles of large boulders dumped at the foot of a cliff. Force waves to break and absorb their energy so protect the cliff. Rocks are brought in by barge to the coast
- relatively cheap and easy to maintain
- provide interest to the coast eg used for fishing
- rocks usually from other parts of the coastline still expensive to transport
- do not fit in with local geology
- can be obtrusive
What is chemical weathering?
Breakdown of rock by changing its chemical composition
At Walton on the Naze 300 tonnes of …………… Was used for Rip rap in …….
Leicester granite
1988 (November)
Social impacts of sea level rise (4)
Deaths
Loss of housing
Lower water supplies
Loss of jobs
How is costal erosion at Walton on the Naze being/been managed?(6)
Sea wall and groynes built in 1977
Paths built to stop erosion by tourists
Vegetation (heather and elder) grown to stop cliffs regrading
Regraded cliff to stop slumping
1999- sand and gravel dredged from harwich harbour
300 tonnes of Leicester granite RIP rap 1988
How are wave cut platforms formed?
Waves cause most erosion as foot of cliff
Forms a wave cut notch, enlargedrock above notch collapses
Collapsed material washed away
Repeats so the cliff retreats
Wave cut platform left behind under the water
Give 5 examples of hard engineering
Sea walls Groynes Revetments Rip rap (Boulder dumping) Gabions
What is happening at Studland bay which is damaging?
The southern end of the bay is unprotected and being eroded
sandy beaches around the bay with sand dunes and heathland behind which is an SSSI and a nature reserve
Environmental impacts of flooding in the Maldives (2)
Loss of beaches
Loss of soil (20cm deep avg)
What is a sea wall, and what are its advantages and disadvantages?
-a concrete or rock barrier to the sea placed at the foot of cliffs or top of a beach. Has a curved face to reflect waves into the sea. Usually 3/5m high
- effective at stopping the sea
- often has a walkway or promenade for people to walk along
- can be obtrusive and unnatural to look at
- very expensive and high maintenance costs
What are the causes of costal erosion at Walton on the Naze?
Red crag- water soaks in through this rock. Mix of gravel and sand
London clay- water cannot pass through but acts as a lubricant so the rock above slumps down the cliff
High tides erode the bottom of the cliff easily as it is clay
LSD is occurring from North East to South west taking the beach away
Give 4 examples of the wildlife at Studland bay
Reptiles- adders, grass snakes, sand lizards, slow worms
Birds- dartford warblers, shelducks, grebes
Fish- only place in England where he spiny seahorse breeds
Plants- marram grass, Lyme grass, heather
Define hard engineering
Building artificial structures such as sea walls to control natural processes (eg erosion)
Political impacts of flooding in the Maldives?(3)
The Maldivian gov asked Japan to give them $60 million to build 3m sea wall that protects Malé the capital city
Carbon neutral policy
Changes to long term plans eg thinking of buying land in Australia and India
Name the adaptations of the marram grass and Lyme grass at Studland bay
Marram-
folded leaves to reduce water loss as sand dunes are windy and dry which increases transpiration.
Long roots to take up water and stabilise itself in loose sand
Lyme- waxy leaves to reduce water loss by transpiration
Within …. Years the Walton on the Naze tower could tumble into the sea
50
3 economic impacts of sea level rising
Loss of tourism
Expensive repairs to damage
Loss of agricultural land
Economic impacts of flooding in the Maldives?(2)
Loss of tourism- ie if main airport cannot work properly
Disrupted fishing industry- fish are the largest export so will reduce countries income
In the Maldives the government had to ask the ……….. Government to give them $……….. To build the …..m high sea wall that protects the capital city- Malé
Japanese
60million
3
What is the case study for costal erosion and costal management?
Walton on the Naze
What is the case study for sea level rising?
What is the average island height about sea level?
How much of the land is below 1m?
Maldives
1.5m
80%
Students results show that the cliff at Walton on the Naze has retreated ……m in ….years
9.6m in 6 years
What is a groyne, and what are its advantages and disadvantages?
-a timber or rock structure build out to the coast. Try trap sediment being moved by LSD, thereby enlarging the beach, which means it’s harder to erode
- results in a bigger beach- enhances tourist potential of the coast
- provide usual structures for people fishing
- not too expensive
- interrupt LSD so often starve beaches down drift, leading to increased erosion there
- seen as unattractive
How deep is the average soil depth in the Maldives?
20cm or less
What is beach nourishment and what are its advantages and disadvantages?
The addition of sand or shingle to an existing beach to make it bigger. Sediment usually obtained locally so blends in. Usually bought ashore by a barge
- relatively cheap and easy to maintain
- blends in with existing beach
- increases tourist potential
-needs constant maintenance unless structures are built to retain beach
What is marsh creation (managed retreat) and what are its advantages and disadvantages?
Allowing low lying coastal areas to be flooded by the sea to become salt marshes
- cheap option compared to maintained sea defences
- probably relatively low value land
- creates habitat for wildlife
- land lost
- farmers or landowners not compensated
The Naze is retreating at approximately ….m per year?
2
How are sea horses in Studland bay affected by boats?
Their anchors are destroying the sea grass where seahorses live. Seahorses are protected by law so owners are being told not to damage the sea grass
How are spits formed?
At sharp bends in the coastline
Swash and backwash moves material along the coast by LSD
Material is deposited on sheltered side of bend eg headland
Behind spit is sheltered so can become mud flat or salt marsh
Give 4 examples of soft engineering
Beach nourishment
Cliff regrading
Do nothing
Vegetate areas
The heathland being the dunes can be damaged by fires caused by things such as cigarettes. E.g. In 2008….
How are the national trust trying to stop this
A fire destroyed 6 acres of heathland.
The national trust is now educating visitors on the dangers of causing fire and has provided fire beaters to extinguish flames
The national trust manages the sand dunes at Studland bay to reduce erosion from people walking across them-how?(3)
Boardwalks used to guide people over the dunes so sand beneath is protected
Some sand dunes are fenced off and have marram grass planted so the dunes have time to recover. Grass stabilises the sand
Info signs are put up to let visitors know why the sand dune habitat is important and how to enjoy it without damaging
Environmental impacts of sea level rise (3)
Ecosystems affected
Vegetation killed by water eg uproot and drowning
Increased soil erosion
Give an example of a less resistant rock that would be eroded to form a bay
Clay
What two things were built in 1977 to protect Walton on the Naze?
Sea wall
Groynes
Give an example of a resistant rock that would form a headland
Limestone/chalk
Name some effects of erosion at Walton on the Naze (5)
Pill boxes on the beach were on top of the cliff in 1945, now 35m away
Results show the cliff has retreated 9.6m in 6 years
The Naze is eroding at aprox. 2m per year
The tower it threatened- within 50 yrs could tumble into the sea
Wildlife is threatened
What is dune regeneration, and what are its advantages and disadvantages?
Marram grass planted in the dunes to stabilise them. Areas also fenced off to protect newly planted dunes
- maintains a natural coastal environment that’s popular with people and wildlife
- relatively cheap
- time consuming to plant and fence areas
- people do not always respond well to being prohibited from certain areas
- can be damaged by storms
At Walton on the Naze in 1999 sand and gravel was dredged from ……….
Harwich harbour
The two types of rock that cause rotational slumping at Walton on the Naze are…
Red crag
London clay
