Fichas
Coasts key terms
Fichas del conjunto (71)
- 1Coastal systemA system including inputs, outputs, flows and stores
- 2Coastal inputsMarine - Waves, tides and currents
Geology - Rock type and tectonics
Atmospheric - Climate change, weather and climate
People - Leisure, industry, housing, urban planning and coastal management - 3Coastal ProcessesMarine erosion - Abrasion, attirtion, hyraulic action and solution
Marine Transportation and deposition - Longshore drift
Sub Aerial - Mass movement and weathering - 4Coastal outputsLandforms produced by erosion - Blowhole, stacks, stumps, arches, headlands, wave cut platforms and cliffs
Landforms produced by deposition - Bays, spits, bars, salt marshes, beaches, cusps, berms, runnels and sand dunes - 5Sediment Cells•Where deposition and erosion take place in specific place
•These are closed systems and no sediment
moves from one to another
•The boundaries of these cells are determined by the shape and relief of the land
•Sub-cells exist within the sediment cells - 6Factors affecting waves•Fetch - Distance of open water in which the wind blows over
•Wind strength
•Wind duration - 7Constructive waves•Spilling waves
•Build up the beach
•6-8 waves per minute
•Swash greater than backwash
•Distant weather systems cause these waves
•Deposit material onto the beach - 8Destructive Waves•Plunging waves
•13-15 waves per minute
•Erode the coastline
•Remove material from the beach
•Local storms cause these waves
•Backwash greater than swash - 9Hydraulic actionThe force of the water hitting the bed and banks
- 10AbrasionRocks and sediment smash against the cliffs and ocean bed
- 11AttritionRocks smashing against each other causing them to break in half
- 12SolutionRocks such as chalk or limestone is dissolved in the water
- 13Factors influencing coastal erosion•Human activity
•Geology
•Fetch
•Wave steepness
•Beaches
•Shape of the coastline
•Climate change
•Tides - 14Spring tide•Earth, sun and moon are in a straight line
•Higher hide tide
•Lower low tide - 15Neap tide•Sun and moon are at a right angle to the earth
•Lower high tide
•Higher low tide - 16Tractionlarge boulders and rocks are rolled along the river bed.
- 17Saltationsmall pebbles and stones are bounced along the river bed
- 18Suspensionfine light material is carried along in the water
- 19Solutionminerals are dissolved in the water and carried along in solution
- 20Longshore driftthe method by which sediment is transported along a
coastline - 21Sub-aerial processland-based processes which alter the shape of the coastline
- 22Freeze-thawCracks in rocks are filled with water, when the temperature drops this water then freezes and subsequently expands by 10%. thus putting pressure on the rock causing it to crack and consequently break
- 23Salt crystallisationWhen water evaporates it leaves behind salt crystals in the cracks of rocks. Over time, more crystals will form in the cracks putting pressure on the rock, causing it to break
- 24Biological weatheringGrowing plants roots widen cracks in the cliffs, as do burrowing animals and nests. These cracks will then get bigger with more pressure and age, causing bits to break off and form a scree slope at the bottom.
- 25Chemical weatheringInvolves the decomposing of rocks, It occurs due to a weak chemical reaction between the rocks and the water. When rain water mixes with carbon dioxide in the atmosphere it forms carbonic acid. This reacts with the calcium carbonate in the limestone to form calcium bicarbonate. Bicarbonate is soluble in water which causes the limestone rock to weather when carbonation occurs.
- 26Wetting and dryingClay rich rocks expand when they get wet, so as they dry they subsequently start to crumble and break, making them very vulnerable to freeze-thaw weathering and salt crystallisation
- 27Mass movementthe movement of material downslope as the result of gravity
- 28Soil creepA slow but continuous process. This occurs as a result of repeated expansion and contraction of the material. Alternating hydration and dehydration also has the same effect. As the soil dries it slowly contracts vertically thus moving downslope
- 29MudflowThis is the rapid movement of soil after a period of heavy rain. Eg. Holbeck hall. When there isn't enough vegetation to hold the soil in place the saturated soil flows over the impermeable subsoil
- 30RockfallThe rapid, free fall of rocks from a steep cliff face. Rocks fall from the cliff due to gravity, but it is made worse by freeze-thaw weathering, which loosens the rocks. A scree slope is formed at the bottom of the cliff of the rocks which have fell.
- 31Rotational slipRapid movements of mass land. These can occur due to heavy periods of rain, when the water saturates overlaying rock making it heavy and able to slide. Undercutting of a steep slope by erosion weakens the rock above making it very likely.
- 32Eustatic changeThe change in sea levels due to alteration in volumes of water
- 33Isostatic changeChange in the height of the land due to the melting of glaciers causing weight to be lifted off the land
- 34BermMaterial deposited on the beach due to a limit of the swash. There is usually a series of them as the tides change from spring to neap
- 35CuspCresent shaped indentation usually found on beaches of mixed sand and shingle. Formed when a wave breaks directly onto the beach with a strong swash and backwash
- 36RunnelGrooves in the sand running parallel to the shore, formed by backwash draining to the sea
- 37Storm ridgeLarger material which is thrown up due to powerful waves formed in storm conditions
- 38Pebble beachSteep and narrow
- 39Sandy beachFlat and wide
- 40Sources of beach material•Longshore drift
•Cliff erosion
•Material deposited at the mouth
•Constructive waves - 41Beaches•Usually found in bays
•Wave refraction causes the energy to decrease thus causing deposition to occur - 42Spit•Formed on the coast when the prevailing winds change direction
•Longshore drift continues depositing material which results in a formation of a long bank of sand and shingle
•Overtime this will continue to grow and get longer
•Waves cannot get past the spit so on the inner side of the spit a salt marsh forms due to deposited silt - 43Bar•When a spit joins two headlands together it forms a bar
•A lagoon may form in-between the bar and the land - 44Headlands and Bays•Formed when the sea attacks a cliff with alternating bands of hard and soft rock
•Bands of soft rock eg. clay, erode more quickly than the resistant harder rock
•This leaves sections of the land jutting out, called a headland, and where the soft rock has eroded forms a bay.
•When waves hit the headlands wave refraction occurs which results in the wave losing energy therefore deposition occurs forming a beach in the bay.
Eg. Swanage bay - 45Cliffs and wave-cut platforms•The sea attacks the base of the cliff forming a wave-cut notch.
•The notch increases in size causing the cliff to collapse.
•The backwash carries the rubble towards the sea forming a wave-cut platform.
•The process repeats and the cliff continues to retreat. - 46Caves, arches, stacks and stumps•Caves are formed on cliffs when the ocean attacks the base of the cliff due to hydraulic action, also water gets into the crack and causes the rocks to chip away, over time a cave will form.
•If formed in a headland it may eventually become an arch, due to hydraulic action or two caves joining together from either side
•The roof will eventually collapse due to the weight leaving behind a stack.
•The stack is then attacked at the base like a wave-cut notch, this will weaken the structure and it will collapse leaving behind a stump.
Eg. 12 apostles, Great ocean road Australia - 47Blowhole•Formed when a joint between a cave and the land above becomes enlarged and air can pass through it
•As water flows into the cave, air is expelled through the pipe, sometimes producing a blast or a spray - 48Sand dunes•These are landforms formed when sand deposits have been blown off the beach, it is transported by saltation by the blowing of the wind.
•Only form when rate of deposition is greater than erosion
•When the dried sand reaches the top of the beach it is trapped by debris such as driftwood or plants.
•If sand isn't eroded then it will be colonised by plants and then trap more sand, increasing in side - 49Embryo dunes•Contain saltwort, sandwort and seacouch
•These plants add organic matter to the dune making it hospitable for other vegetation
•Poor water
•Little humus
•1m height - 50Foredunes/yellow dunes•Initially yellow but darken due to the organic material which increases the humus
•Slightly alkaline
•5m height
•Maram grass
•More stable
•Little moisture - 51Grey dunes•Fixed dunes
•Acidic
•humus increases, increasing water retention
•Creeoing willow forms
•8-10m height
•improved soil
•Sheltered - 52Dune slack•Intersects the water table
•Aquatic plants
•Low lying land - 53Ria•Flooded river valley
•As sea levels rise, in the lower course the river channel and the floodplain either side of the river are submerged and drowned.
•Only the higher land is exposed
Eg. Kingsbridge Estuary, Devon - 54Fjord•A drowned glacier valley
•It has steep cliff like valley sides and the water is uniformly deep (1000m deep)
•Formed when a glacier erodes below sea level, so when it melts the valley becomes flooded
eg. Milford sound fjord, New Zealand - 55Submerged forest•These are forests which have been submerged due to a rise in sea level, but can sometimes be seen at low tide.
•In wales, it is believed that thy have been preserved due to acidic anaerobic conditions - 56Barrier beach•A strip of dune formed by longshore currents
•They are divided into 3 sections, beach, dune and marsh
•Due to a rise in sea level it causes some sediment to be bulldozed towards the coast resulting in a barrier beach - 57Raised beach•An area of land which has a previous wave cut platform and cliff with signs of a beach
•Due to isostatic change
eg. Isle of Arran, Scotland - 58Relict cliff•An old cliff showing features of caves, arches and stacks
•The water used to be very close to these cliffs however now isn't - 59Hard EngineeringCoastal protection using engineered man-made structures, such as seawalls to reduce coastal erosion. Usually expensive and unsustainable
- 60Sea Wall•A concrete wall built at the edge of the coastline
+ It stops erosion of the cliff, land and buildings
Can prevent coastal flooding
- Expensive £6000 pm
Looks unsightly
Curved walls refract wave energy back into the sea keeping the waves very powerful - 61Groyne•A timber or rock structure going out to sea at a right angle to the beach
+Prevent beach erosion and the transport of sediment by longshore drift
Allows build up on the beach which are natural defences of erosion
- Unsightly
Expensive £5000 - £10000
Costly to manage - 62Riprap•Rocks and large boulders placed at the bottom of the cliff to absorb wave energy
+Absorb wave energy to reduce coastal erosion
Still allows build up on the beach
Last a long time
-Expensive to build and transport boulders - 63Revetment•Similair to riprap, wooden or rock barriers placed in front of the cliff to reduce the energy of waves before it reaches the cliff
+Allows sediment to pass through allowing the beach to build up
Successfully reduces coastal erosion by absorbing wave energy
-Prevent access to the ocean
Unsightly
Stops beach sediment further down the coast - 64Gabion Boxes•Rocks and pebbles enclosed in a wire cage at the base of cliffs, often used to also stabilise cliffs
+Can eventually blend in with the beach when vegetation grows on the rocks
Relatively cheap
Allow cliffs behind to drain
-Unsightly if don't blend
Wire may break which is a health and safety risk
Don't last a long time, 5-10 years - 65Barrages•Largescale engineering structure, partially submerged wall in a bay
+Can generate electricity
Controls flow of water
-Very unnatural
Expensive - 66Soft EngineeringCoastal protection that works with the natural environment and doesn't change the characteristics of the land, relatively cheap and sustainable
- 67Beach Nourishment•Addition of sand and pebbles on a beach to increase its height and width
+Looks natural and blends in with previous sand
Cheap
Increase tourism
-One storm may remove all sand from the beach
Needs constant management
Eg. Miami Beach 17.7 million m3 - 68Land Use•Preventing certain land to be used to prevent the effects of flooding
+No cost
Appropriate management
-Some people won't want certain land not to be used
Could disrupt holiday parks - 69Marsh Creation•Allowing low-lying coastal land to be flooded which in time creates a salt marsh
+Creates habitats and new wildlife
Maintains a natural coastline environment
Absorbs tidal energy
-Compensation is very costly since it is destroying agricultural land
Homes are sacrificed - 70Dune Regeneration•Creating and restoring sand dunes by nourishment and planting vegetation to stabilise sand
+Absorbs wave energy
Provides a barrier between land and sea
-Flood protection is only limited to certain areas
Nourishment can be expensive - 71Why do sea levels change?•Global warming
•Glacial periods
•Sea levels have risen 140m over 200,000 years, 10mm every year
•Used to be 1-2mm per year but due to global warming it is now 4-5mm per year
Información
- Descripción
- A-Level (Coasts) Geography Fichas sobre Coasts key terms, creado por Isobel Wagner el 15/04/2015.
- Creado por
- Isobel Wagner · abr 2015
- Actualizado
- 7 mar 2018
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