St Ivo Geography – AQA GCSE Revision Abrasion – caused by waves picking up material Define the key terms: which is forced against the cliff face wearing it - Abrasion away - Attrition Attrition – where stones and pebbles in the sea re knock against each other causing them to become e h smoother and rounded. ong l a d l Yr 11 - Coasts www.geobytes.org.uk o www.geobytes.org.uk F St Ivo Geography – AQA GCSE Revision Fetch – The distance over which wind has blown to form a wave 1. Define the key terms: Backwash – the movement of water back down a a. Fetch beach b. Backwash re Swash – the movement of water up a beach e h c. Swash ong l a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytes.org.uk F St Ivo Geography – AQA GCSE Revision - 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 Describe and explain the way in which waves - as a wave reaches shallow water, friction between the sea bed and the base form of the wave – causes the wave to slow down – shape becomes more elliptical re - top of the wave however – unaffected by the friction – becomes steeper – e h eventually breaks ong l - when it breaks – water moving up the beach in the swash and the water a d l moving back down the beach in the backwash. Yr 11 - Coasts www.geobytes.org.uk o www.geobytes.org.uk F St Ivo Geography – AQA GCSE Revision - Low <1m - Low energy Outline the main characteristics of constructive - Low frequency (<10/min) waves - Swash>Backwash re - Deposition e h ong l a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytes.org.uk F St Ivo Geography – AQA GCSE Revision - High (>1m) - High energy Outline the main characteristics of destructive waves - High Frequency (>10 min) - Swash<Backwash re - Erosion e h ong l a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytes.org.uk F St Ivo ScSthoo Ivol Ge Geooggrraapphhyy De – ApaQArtm GCSEent -R GCSEevisio REVISIONn - Strength and speed of wind – faster the wind – more energy transferred – bigger wave produced Describe 3 factors which will affect the strength of a - Duration of the wind – length of time for which the wind has wave blown – longer the wind blows for, the more energy is transferred to the wave. re - Fetch – the distance over which the wind has blown (i.e. how e h far the wave has travelled) – longer the fetch the stronger ong l a the wave. d Yr 11 - Coasts www.geobytes.org.uk l o www.geobytesgcse..wordpress.com F St Ivo ScSthoo Ivol G Geeooggrraapphhyy De – ApaQArtm GCSEent -R GCSEevisio REVISIONn Frost Shattering – water gets into cracks in the rocks – if temperatures fall below freezing at night the water freezes and expands (9-10%); puts pressure on the rock around – then thaws. Freeze-thaw cycle gradually Outline a form of physical weathering operating at forces the rock apart. the coast Salt crystal growth – sea water contains salt from spray from the re e waves – when evaporates leave salt behind – salt crystals growing in h the cracks in the rock can force the rocks apart ong l a d www.geobytes.org.uk l www.geobytesgcse..wordpress.com Yr 11 - Coasts o F St Ivo School Geography Department - GGCSECSE REVISION d. Abrasion – where rock fragments in the wave are flung against the cliff face Name and outline four examples of erosion e. Hydraulic action – waves break against cliff face – pressure of the breaking wave compresses air in cracks – ‘mini-explosions’ force processes operating at the coast the rocks apart f. Corrosion – occurs where salt water is able to dissolves some of re e minerals in the rock (e.g. limestone cliffs gradually weakened). h g. Attrition – rock fragments carried by the waves – hit against ong l a each other and gradually wear down. d l Yr 11 - Coasts www.geobytes.org.uk o www.geobytes.org.uk F St Ivo ScSthoo Ivol G Geeooggrraapphhyy De – ApaQArtm GCSEent -R GCSEevisio REVISIONn Slumping – erosion at base of cliff may lead to rotational slipping of cliff above – particularly on clay cliffs – during dry periods the Outline the mass movement processes of clay contracts and cracks and will become saturated during wet periods – moving downslope due to gravity. (i) slumping and (ii) soil creep re Soil Creep – slow downhill movement of soil e h ong l a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytes.org.uk F St Ivo ScSthoo Ivol G Geeooggrraapphhyy De – ApaQArtm GCSEent -R GCSEevisio REVISIONn - Headlands and Bays - Wave Cut Platform Name 4 examples of erosion landforms at the coast - Cliff - Cave re - Stack and Stump e h - Arch ong l a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytes.org.uk F St Ivo Geography – AQA GCSE Revision Name 3 examples of deposition landforms at the - Beaches coast - Spits - Bars re e h ong l a d l Yr 11 - Coasts www.geobytes.org.uk o www.geobytes.org.uk F St Ivo Geography – AQA GCSE Revision This is the movement of material along the coastline. Material is moved up the beach by the swash at an angle controlled by Describe and explain the process of longshore drift 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 re coastline, its direction controlled by the prevailing wind e h direction. ong l a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytesgcse..wordpress.com F St Ivo Geography – AQA GCSE Revision Headlands and Bays (Swanage Bay and the Give named examples of the following features: Foreland – Dorset) a. Headlands and Bay Wave-cut platform – Kimmeridge (Dorset b. Wave-cut platform Coast) c. Stack re Stack – Old Harry (Dorset) e h d. Arch Arch – Durdle Door ong l a d l Yr 11 - Coasts www.geobytes.org.uk o www.geobytesgcse..wordpress.com F St Ivo Geography – AQA GCSE Revision - Headlands form along discordant coastlines (bands of hard and soft rock outcrop at right angles to the coast) - Leads to differential erosion (soft rock eroding quicker than the harder Describe and explain how Headlands and Bays form resistant rock) - Bays (indents in coastline) form where the erosion of the soft rock is rapid re - Headlands (hard rock outcrops) – left sticking out into the sea e h - The exposed headland then becomes vulnerable to the force of the ong l destructive waves a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytes.org.uk F St Ivo Geography – AQA GCSE Revision - Erosion of cliff at base in wave-attack zone (hydraulic action and solution) – undercuts the cliff and forms a Describe and explain how cliffs and wave-cut wave-cut notch - Cliff face affected by abrasion (rock fragments hurled platforms form against cliff) - Undercutting continues – overhanging cliff eventually re e collapses – cliff retreats h - As cliff retreats – gently sloping rocky platform (wave-cut ong l a platform) left behind and exposed at low tide. d www.geobytes.org.uk l Yr 11 - Coasts o www.geobytes.org.uk F St Ivo ScSthoo Ivol G Geeooggrraapphhyy De – ApaQArtm GCSEent -R GCSEevisio REVISIONn - The sea attacks foot of cliff – erodes weaknesses such as joints / cracks (processes like hydraulic action and abrasion) - Cracks get larger – form into small caves Describe and explain the erosion of a headland - 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 – weakens structure – roof of arch eventually collapses – leaves a stack (free re e h standing column of rock) ong l - Stack eventually collapses forming stump (covered at high tide) a d l www.geobytes.org.uk Yr 11 - Coasts o www.geobytesgcse..wordpress.com F St Ivo ScSthoo Ivol Ge Geooggrraapphhyy De – ApaQrAtm GCSEent -R GCSEevisio REVISIONn - Spits – Spurn Head (Holderness Coast) - Beach – Hunstanton Give named examples of a (i) spit (ii) beach and (iii) - Bar – Slapton Sands (Devon) bar re e h ong l a d Yr 11 - Coasts www.geobytes.org.uk l o www.geobytesgcse..wordpress.com F St Ivo School Geography Department - GCSE REVISION - Rivers – where fine muds and gravels and deposited at the river mouth Give 3 main sources of beach material - Longshore drift (bringing material from elsewhere along the coast) - Constructive Waves (bringing material up the beach from the sea) and from cliff erosion re e h along d l Yr 11 - Coasts www.geobytes.org.uk o www.geobytesgcse..wordpress.com F St Ivo School Geography Department - GCSE REVISION Resistance of Rocks – limestone / chalk and granite – more resistant and less resistant rocks (e.g. clay) erode faster Shape of the Coastline – where discordant coastline – outcrops Describe 3 factors which affect the rates of coastal of hard and soft rock – resulting in differential erosion erosion Strength of the Waves – longer the fetch the stronger the winds – greater the rates of cliff recession re e Coastal defence – rates of cliff recession are slower where h coastal defence techniques are used. ong l a d Yr 11 - Coasts www.geobytes.org.uk l o www.geobytes.org.uk F St Ivo ScSthoo Ivol G Geeooggrraapphhyy De – ApaQArtm GCSEent -R GCSEevisio REVISIONn - Lyme Regis is built on unstable land Describe 3 reasons why coastal management is - the town is exposed to strong destructive waves from the SW with a long fetch.