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EMS Geography GCSE Revision FLASH CARDS:Unit 1 – Coastal Landscapes (AQA)

EMS Geography GCSE Revision: Question(s) Answer(s)COASTAL LANDSCAPES

Define the key terms: a. Fetch b. Backwash c. Swash d. Creste. Troughf. Wave heightg. Wave lengthh. Wave frequency

Fetch – The distance over which wind has blown to form a waveBackwash – the movement of water back down a beach Swash – the movement of water up a beachCrest – the top of the waveTrough – the bottom of the waveWave height – the vertical distance from trough to crestWave length – the horizontal distance between two successive crests or troughsWave frequency – the number of waves breaking per minute


Describe and explain how waves form

- Wind blows over surface of water – creates friction - Frictional drag causes water particles to begin to rotate and energy is transferred forward in the form of a wave - As a wave reaches shallow water, friction increases between the sea bed and the base of the wave – causes the wave to slow down - Top of the wave – unaffected by the friction – becomes steeper – eventually breaks - When it breaks – water moving up the beach in the swash and the water moving back down the beach in the backwash


Outline the main characteristics of constructive waves

- Height: Low <1m - Energy: Low - Frequency: Low (<10/min) -Wave Shape: Elliptical- Strong Swash; Weak Backwash - Coastal Process: Deposition


Outline the main characteristics of destructive waves

- Height: Higher >1m - Energy: Higher- Frequency: Higher (>10/min) -Wave Shape: Orbital (round)- Strong Backwash; Weak Swash - Coastal Process: Erosion



Describe 3 factors which will affect the strength of a wave

- Strength and speed of wind – faster the wind – more energy transferred – bigger wave produced - Duration of the wind – length of time for which the wind has blown – longer the wind blows for, the more energy is transferred to the wave. - Fetch – the distance over which the wind has blown (i.e. how far the wave has travelled) – longer the fetch the stronger the wave.


Define these sub-aerial processes: (a) weathering(b) mass movement

Weathering – ways that rocks are broken down in situ.

Mass movement – material moves down a slope, pulled by gravity.


What is the difference between Mechanical (physical) weathering & Chemical weathering

Mechanical (physical) weathering is when rocks break apart rather than decomposes (usually caused by extreme temperatures)

Chemical weathering is caused by a chemical reaction between rainwater and alkaline rocks which dissolves at the surface (decomposes).


Explain the terms: Mechanical (Physical) weathering:

(a) Freeze-thaw weathering(b) Salt weathering

Freeze-thaw weathering is when water gets into a crack in a rock, freezes & expands, forcing the rock to crack and eventually splitSalt weathering is when salt spray gets into a crack in a rock, evaporates and crystallises, putting pressure on the surrounding rock.


Explain the terms: Chemical weathering:

(a) Carbonation(b) Hydrolysis(c) Oxidation

Carbonation - is when carbonic acid in rainwater reacts with alkaline rock such as limestone (calcium carbonate) and dissolves at the surface (calcium bicarbonate - soluble).Hydrolysis is when acidic rainwater breaks down rock causing it to decompose (rot)Oxidation is when rocks are broken down by oxygen and water.



Explain these types of mass movement:(a) Landslide(b) Rockslide(c) Mud slide(d) Rock falls(e) slumping

Landslide – Large amounts of rocks, soil & mud slide quickly down a steep cliff. This is caused by weathering and heavy rain infiltrating the soil, creating a steep slip plane- a line of weakness in saturated rock.

Rockslide – Large amount of rock slides quickly down a straight slip plane but keeps in contact with the cliff.

Mud slide – On wet, steep slopes (over 10 degrees). Rapid movement creates a lobe (spread of saturated soil) at the base of the cliff.

Rock fall – Bare, well-jointed cliffs such as limestone or chalk, lose contact with cliff and fall rapidly due to freeze-thaw weathering. This creates a scree slope at the base of the cliff.

Slumping – erosion at base of cliff may lead to rotational slipping of cliff above (concave slip plane) – particularly on clay cliffs – during dry periods the clay contracts and cracks and will become saturated during wet periods – moving downslope due to gravity.


Name and outline four examples of erosion processes operating at the coast

- Abrasion – where sands in the wave are flung against the cliff face - Hydraulic action – waves break against cliff face – pressure of the breaking wave compresses air in cracks – ‘mini-explosions’ force the rocks apart - Corrosion – occurs where slightly acidic sea water is able to slowly dissolve alkaline rock (e.g. limestone or chalk cliffs gradually weakened). - Attrition – pebbles or small boulders carried by the waves – hit against each other and gradually wear down


Describe 3 factors which affect the rate of coastal erosion / recession

Geology - Resistance of Rocks – limestone / chalk and granite – more resistant - whereas clay = less resistant rocks = erode faster Shape of the Coastline – where discordant coastline (bands of rock at right angles to coast) – outcrops of hard and soft rock – resulting in differential erosion Strength of the Waves – longer the fetch the stronger the winds – greater the rates of cliff recession Coastal defence – rates of cliff recession are slower where coastal defence techniques are used.



Name 4 examples of erosion landforms found along the Dorset coastline

- Headland / Cliff (Peveril point) and Bays (Swanage)- Wave Cut Platform (Kimmeridge) - Stack (Old Harry) and Stump (Old Harry’s wife)- Arch (Durdle Door)


Describe and explain the process of longshore drift

- This is the movement of material along the coastline. - Material is moved up the beach by the swash at an angle controlled by the prevailing wind. - The backwash then carries materials back down the beach at right angle to the coastline under the influence of gravity. - Gradually the material is moved along the coastline in a zig-zag movement - its direction controlled by the prevailing wind.


What causes deposition?

Constructive low-energy waves leaves more sediment than it removes. This occurs in: - sheltered bays;- wide, flat sandy beaches that encourages a large swash- engineered structures like groynes trap sediment updrift.


What is the difference between a concordant and discordant coastline?

Concordant coastline – Alternating layers of hard and soft rock run parallel to the coast = coves (Lulworth).

Discordant coastline – Alternating layers of hard and soft rock at right angles to the coast = headlands & bays (Swanage).



Explain the formation of cliffs and wave-cut platforms

- Cliff formation – sea erodes base of cliff by hydraulic action and abrasion (destructive waves).- Over time this creates a wave-cut notch and overhang- Lack of support (gravity) of overhung cliff creates pressure / cracks and subsequent collapse- Action of sea compacting rock into wave-cut platform which protects coast at low tide e.g. Kimmeridge, Dorset- Formation of steep cliff which over time recedes


Explain the formation of headlands and bays

- Headlands and bays are formed in areas of hard and soft rock (discordant coastline)- Erosion is greater on the soft rock e.g. Clay (Swanage Bay, Dorset) – as these are less resistant to wave processes such as hydraulic action and abrasion- Headlands are more resistant – therefore erodes more slowly – protruding into the sea e.g. Limestone (Peveril Point, Swanage, Dorset)- The exposed headland eventually becomes more vulnerable to erosion from destructive waves. This is due to:

Wave refraction, where the crest of the wave refracts (bends) to the shape of the coastline due to friction, which concentrates high energy destructive waves on the headland and transportation of eroded material by longshore drift in to the bay and deposition by waves which are now low energy.



Describe and explain the erosion of a headland

- The sea attacks base of cliff – erodes weaknesses such as joints / cracks in e.g. chalk - by processes such as hydraulic action and abrasion.- Cracks get larger – form into small caves - Further erosion widens the cave – where the fault line runs through the headland – eventually forms arch which passes through the headland - Further wave attack at base of arch and weathering of roof of arch (e.g. Durdle Door, Dorset) – weakens structure – roof of arch eventually collapses – leaves a stack (free standing column of rock) e.g. Old Harry, Purbeck, Dorset- Stack eventually collapses forming stump (covered at high tide) e.g. Old Harry’s Wife, Purbeck, Dorset


Explain the formation of beaches

- Made of sand and pebbles - Found on straight coastlines where longshore drift is happening- Also found in bays where the sea is shallower so the waves lose their energy and deposit what they are carrying – constructive waves (Strong swash, Weak backwash)


Describe the differences between sandy and pebble (shingle) beach profiles.

Sandy Beach Profile:- Generally shallow, wide, almost flat- Constructive waves- Sand dunes (sometimes) at back of beach- Low tide= water-filled depressions called runnels with parallel ridges either side and ripples in the wet sand.

Pebble Beach Profile:- Steep- Destructive waves- Narrower beach- Pebbles increase inland with a storm beach at the back.



Why do beach profiles change?

Berms (a parallel ridge on the beach) are formed in calm weather by constructive waves (strong swash).

In Winter:- Berms are eroded by destructive waves and sediment is transported offshore to create an offshore bar.- Destructive waves make the beach narrower and steeper.

In Spring & Summer:- Constructive waves rebuild the beach, with sediment from the offshore bar to rebuild the berms.


Explain how sand dunes are formed

E.g. Studland, Dorset- Wide, flat, sandy beaches with onshore winds will move a large supply of sand inland by mainly saltation (grains bounce along).- An obstacle such as driftwood will trap sand, creating a small ridge, which becomes stable at a angle of between 30-34 degrees.- The stronger the wind, the higher the dune.


Explain how sand dunes change inland

Dunes grow taller inland e.g. embryo dunes only a few metres whereas mature dune up to 15 metres. This is due to vegetation such as marram grass, which has long roots that binds the sand.Dunes are yellow and become grey inland. This is due to increased vegetation (and decomposition) as conditions become less harsh (sheltered, with increased acidity – ph5).Dunes are separated by a trough called a slack, which can be eroded as far down as the water table. Large depressions are called blowouts due to strong winds removing vegetation.

EMS Geography GCSE Revision: Question(s) Answer(s)


COASTAL LANDSCAPES

Explain the formation of:(a) Spits(b) Bars

(a) Spit (E.g. Hurst Spit, Dorset)- Spit formed by movement of material along a coastline due to longshore drift- Occurs where there is a change in direction of the coastline and builds out beyond headland.- May form re-curved end due to change in wind / wave direction.- Formation of salt marsh behind spit as sheltered from wave attack.

(b) Bar (as above + below)- Bars are spits which go across a bay- This is only possible if there is shallow water and no river entering the sea.- A lagoon is formed behind the bar E.g. Slapton Sands, Devon


What are the differences between hard and soft engineering in coastal management ?

Hard engineering involves the construction of expensive artificial defences to control the natural processes (e.g. groynes and sea walls) whereas;Soft Engineering works with natural processes, not involving construction. It is usually visually unobtrusive and considered more environmentally friendly


Explain how effective hard engineering techniques are in controlling coastal erosion in the UK

(A) = advantages (D) = disadvantages

Recurved seawall: usually made of concrete; modern ones have a recurved face. (A) Very visible – make residents feel safe; can be long lasting (D) Can cause wave scouring (erosion of the beach) if not positioned correctly; can be expensive e.g. £5,000 per metre.Groynes: wooden fences which run at right-angles to the coastline. (A) Keep beach in place for tourist industry; can last up to 40 years (D) Stops longshore drift - narrows beach and increases erosion down-drift; unattractive and unsafe as creates deep water on down-drift side.Rip-rap: Large rocks placed in front of the cliff. (A) Relatively cheap at £1,000-£3,000 per metre; Effective for many years. (D) Unattractive – do not fit in with local geology; and unsafe as makes access to beach hazardous.Gabions: Wire cages filled with stones to reduce erosion (A) Cheap - £110 per metre and can last 25 years; Rock cages absorb wave energy. (D) Wire cages can break (hazardous) and so can only be used on sandy beaches; need to be securely tied down.

EMS Geography GCSE Revision: Question(s) Answer(s)


COASTAL LANDSCAPES

Explain how effective soft engineering techniques are in controlling coastal erosion in the UK

(A) = advantages (D) = disadvantages

Beach nourishment: Placing sand and pebbles on a beach. (A) Looks natural; wider beach can protect from coastal flooding. (D) Needs constant maintenance – lost sand through longshore drift = beach recycling = resentment from residents in donor area; though cheaper than hard engineering, there are high overhead costs e.g. dredger = £300,000.Beach reprofiling: Artificially re-shaping beach using existing beach material e.g. bulldozers moving shingle (pebbles) back up the beach after a winter storm. (A) Beach still looks reasonably natural; residents feel safe. (D) Bulldozers restrict access to beach; costs can be high e.g. £200,000 at Selsey (West Sussex).Sand dune regeneration: Artificial creation or restoration of existing dunes to protect land from sea. (A) Regeneration at Studland maintains bio-diversity e.g. 6 species of reptiles including adders; volunteer labour means costs are low. (D) Regenerated dunes are fenced off and may deter tourists; regeneration can be damaged by storms.Managed retreat: Allowing the sea to gradually flood land or erode cliffs. (A) Cheap & creates new habitats; sustainable in long-term due to increased sea levels as a result of climate change (D) Upsetting for landowners who lose land; short-term costs (compensation) may be high.


For a named example, explain how the coast is being managed.

Exam hint: This is a common extended answer question. Make sure you have plenty of PLACE-SPECIFIC examples & explain why they were used.

Medmerry (West Sussex) – Coastal realignment scheme (largest in Europe)

Why was the scheme needed?:Environment Agency (EA) identified area west of Selsey to be the area in S.E. England to be most at risk from flooding due to climate change.Current reprofiling of shingle ridge costs £200,000 per year = unsustainable.At risk – 348 properties (Selsey); water treatment plant; main road between Chichester & Selsey; and holiday homesLast flood cost £5 million (2008)

What strategy was used?:Building 2km clay embankment to enclose future intertidal area60,000 tonnes of rock armour placed on seaward edges to link to old shingle ridge.110 metre breach made in shingle bank to flood land and create intertidal area.


COASTAL LANDSCAPES

For a named example, explain the resulting effects and conflicts of coastal management.

Exam hint: This is a common extended answer question. Make sure you have plenty of PLACE-SPECIFIC examples & explain why they were used and any controversies or conflicts.

Medmerry (West Sussex) – Coastal realignment scheme (largest in Europe)

What happened as a result?:Positive effectsSocial – protection to 1:1000 year event & successfully avoided flooding in storms of 2013; also provides 10kms of footpaths & 7kms of bike paths.Economic – Tourism to increase with 2 new car parks, 4 new viewing points & numbers to the nearby holiday village.Environmental – 300 hectares of new intertidal habitats – salt marsh, mud flats = huge nature reserve managed by RSPB.

Controversy and conflicts?:Social – some local residents wanted to continue beach reprofiling; others outside area resented investment – what about other vulnerable areas such as Somerset Levels?Economic - £28 million = very expensive though current scheme long-term will cost more; 3 farms had to be abandoned.Environmental – Despite planning, habitats will still be disturbed e.g. for badgers.

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