AQA Geography A Coasts

Natalia  Cliff
Flashcards by , created over 2 years ago

GCSE Geography (Physical Geography) Flashcards on AQA Geography A Coasts, created by Natalia Cliff on 05/20/2017.

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Natalia  Cliff
Created by Natalia Cliff over 2 years ago
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Question Answer
What affects the formation of a wave? -Fetch -Strength of the wind -Obstacles
Why do waves break? -Out at sea, waves have a circular orbit -When they come into land, friction with the seabed makes the orbit elliptical -The orbit becomes more elliptical due to increased friction until the top of the wave breaks
Diagram of waves breaking Waves Breaking (image/jpeg)
Characteristics of constructive waves -Weak backwash -Strong swash -Means that it deposits -Formed by distant storms
Characteristics of destructive waves -Weak swash -Strong backwash -Means it erodes -Closely spaced and interfere with each other resulting in chaos -Crash down on the beach -Formed by local storms
What are the 3 kinds of weathering? -Chemical (e.g. salt water against certain rocks) -Biological (e.g. tree roots) -Physical/Mechanical (freeze thaw)
What are the kinds of mass movement? -Rockfall -Landslide -Mudflow -Rotational slip
What happens in Rockfall? fragments of rock break away from the face of the cliff, usually due to freeze thaw
What happens in a Landslide? blocks of rock slide downhill
What happens in a Mudflow? Saturated soil and weak rock flows down
What happens in a Rotational Slip? slump of saturated soil and weak rock along a curved surface
Types of erosion at the coast -Hydraulic power -Corrasion -Abrasion -Solution -Attrition
Corrasion Fragments of rock being picked up and hurled at the cliff by the sea
Hydraulic power the sheer force of the waves breaking bits off cliffs
Abrasion The sandpapering effect of pebbles grinding over a rocky platform
Attrition fragments of rock caught by the sea knock against one another, causing them to be smaller and rounder
Solution Some rocks (e.g. limestone and chalk) are susceptible to being dissolved by saltwater
Types of Transportation -Traction -Saltation -Suspension -Solution -Long shore drift
Traction large pebbles rolled along the seabed
Saltation hopping or bouncing motion along the sea bed of particles too heavy to be suspended
Suspension particles carried by the water
Solution dissolved chemicals, often derived from chalk and limestone
Longshore drift -Waves approach beach at the angle of the dominant wind (north west in northern hemisphere) -Retreat at 90 due to gravity -Causes zigzagging motion that carried sediment along the beach
Where does deposition occur? Deposition tends to occur in bays, where the energy of the wave is reduced
Formation of headland and bays -Bands of resistant (hard) and less resistant (soft) rock -Soft rock get's eroded away over time -Leaves headlands of hard rock and bays of soft rock
Diagram for formation of headlands and bays Headlands And Bays (image/jpeg)
Formation of a wave-cut notch -Waves break against a cliff -Erosion (hydraulic action and corrasion) occurs near the high tide line -Over time the notch gets deeper -The cliff can no longer support itself, so collapses
Formation of a wave-cut platform -Continual wave-cut notches and cliff collapse the cliff line retreats -This leaves behind a gently sloping rocky platform called a wave-cut platform -Normally very smooth due to abrasion
Diagram of cliff collapse (including mass movement, wave-cut notches and wave-cut platforms) Cliff Collapse (image/jpeg)
Formation of a stump -Headland sticks out to sea with a lot of destructive wave -Corrasion and hydraulic action erode a crack in the headland -Crack get's eroded into a cave -Eventually breaks through to the other side, leaving an arch -Top of the arch collapses due to lack of support and gravity leaving a stack -Stack is eroded down to a stump by weathering
Formation of a stump diagram Stump (image/jpeg)
Beaches -Beaches are a deposition of sand and shingle -Sandy beaches are often found in sheltered bays -Waves refract as they enter the bay and therefore lose their energy so deposition occurs
Formation of a spit -Spits occur when there is a break in the coast -Longshore drift continues depositing however -Eventually the spit breaks the surface forming new land -If there is a wind opposing the prevailing wind it can form a hook at the end
Diagram of the formation of a spit Spit (image/jpeg)
Formation of a bar -Sometimes long shore drift continues and the spit grows across the bay, leaving a freshwater lagoon behind it
Rising Sea Levels -Over the last 15 years seas have risen by 3 mm -Predicted 28-43 cm by the end of the century -Caused by thermal expansion of seawater
Rising Sea Levels Norfolk -Norfolk broads is a popular tourist destination -Brings £5+ mill to the local area -Rising sea levels would cause bad flooding
Rising Sea Levels Happisburgh -Rising sea levels will probably mean an increase in erosion -Threatens settlements of cliffs like Happisburgh -Coastal defences will be expensive
Rising Sea Levels East Anglia -Storm surge in 1953 that killed 300 people -Such occurrences more likely with rising sea levels -22% of East Anglian salt marshes could be gone by 2050
Rising Sea Levels Thames Barrier -Protects buildings worth £80 bn -needs replacement in the next 30 to 50 years -As sea levels rise lower areas of Thames estuary at risk of flooding -Affects housing and farmland
Barton-on-Sea Hampshire Location and Issue -Stretch of coastline in Christchurch bay -Number of buildings lost due to cliff collapse -Extensive coastal defences built, but new landslip in 2008 -Development of houses just 20 m from cliff edge -Estimated that they will be lost in 10 to 20 years -Rate of erosion up to 2 m
Barton-on-Sea Hampshire Natural causes -Rocks are weak sands and clays, easily eroded and little resistance to cliff collapse -Permeable sand over impermeable clay causes water to pond up and increase the weight and pressure of the cliff -Faces prevalent westerly winds with a long fetch -Several small streams flow toward the cost but disappear in permeable sand
Barton-on-Sea Hampshire Human causes -Buildings of cliff top have made it heavier and more prone to collapse
Shoreline management plan an integrated coastal management plan for a stretch of coast Details areas of high risk of erosion, flooding etc. and puts plans into place for how to cope with the issues
Sea Wall Description and cost -Concrete or rock barrier built at the foot of a cliff or the head of a beach - 3-5 m high -curved face to reflect waves -Up to £10 million per km
Sea Wall Advantages and disadvantages -Effective -Often has a walkway for people -Can be obtrusive -Very expensive -High maintenance costs
Groynes Description and cost Timber or rock structures built out to sea from the coast -Trap sediment moving from longshore drift -Wider beach offers more protection -Up to £5 000 per m
Groynes Advantages and Disadvantages -Bigger beach for tourists -Useful structures for fishing -Not too expensive -Starve beaches downdrift thereby increasing erosion there -Unnatural and can be unattractive
Rock Armour Description and Cost -Piles of large boulders dumped at the foot of a cliff -Force the waves to break and absorb their energy -£1 000 - £4 000 per m
Rock Armour Advantages and disadvantages -Cheap and easy to maintain -Often used for fishing -Rocks from elsewhere in the country can be expensive to transport -Can be obtrusive -Don't fit with natural geology
Beach Nourishment Description and cost -Adding sand or shingle to a beach -Sediment obtained locally so blends in -£3 000 per m
Beach Nourishment Advantages and Disadvantages -Relatively cheap -Easy to maintain -Blends in -Bigger beach means more tourists -Needs constant maintenance unless structures are built to keep it in place
Dune Regeneration Description and cost -Sand dunes are easily destroyed -So marram grass is planted to stabilise the dunes -Areas are then fenced off to keep people off the newly planted dunes -£20 per m
Dune Regeneration Advantages and disadvantages -Natural coastal environment for people and wildlife -Relatively cheap -Planting is time consuming -Can be damaged by storms -People don't like being fenced off
Marsh Creation Description and cost -Type of managed retreat -Low-lying coastal areas are flooded to become salt marshes -Salt marshes are effective barriers against the sea -Cost depends on value of land -£5 000 - £10 000 per ha
March Creation Advantages and disadvantages -Cheap in comparison to expensive defences for low-value land -Much needed habitat for wildlife -Land is lost -Farmers/landowners need to be compensated
Managed retreat Allowing controlled flooding of low-lying areas or cliff collapse in areas where the value of the land is low, e.g. poor quality grazing land
Minehead Location and Issue -North Coast of Somerset -:Large tourist resort -1990s realised if nothing was done, storm damage would cost £21 m -1997 sea defences officially opened -Cost £12.3 m
Minehead Main features -o.6 m high curved sea wall -Rock armour at the base of the wall Beach nourishment built the beach up 2 m in height -Four rock groynes retain the beach -Wide walkway for tourists
Salt Marsh -Starts as an accumulation of mud behind a spit -Mud breaks the surface forming mud flats -Pioneer plants with high salt tolerance (cordgrass) called pioneer plants grow on these -Cordgrass has a high salt tolerance and long rots stop it from being swept away -Tangled roots keep mud in place -Mud level rises and is no longer often covered by water -Rainwater washes out salt -New plants (e.g. sea asters) start to colonise -Slowly succession of plants develops called vegetation succession
Vegetation succession diagram Vegetation Succession (image/jpeg)
Keyhaven, Hampshire Species -Cordgrass -Ringed Plover (bird, feeds and nests in salt marsh) -Sea Lavender -Oystercatcher (bird, feeds and nests in salt marsh) -Wold Spider (clings to submerged stems of cordgrass waiting for low tide to bring it food
Keyhaven, Hampshire Issues -Salt marsh retreating 6 m a year -1989 storm breached Hurst Castle Spit, exposing 50 - 80 m that was eroded in 3 months -Tourism means people could trample, park and pollute the saltmarsh
Keyhaven Hampshire Solutions --1996 Rock armour and beach nourishment protected spit £5 m -Keyhaven is a SSSI and Nation Nature Reserve