Coasts

Frage	Antworten
what is hard engineering?	man made structures built to control the flow of the sea and reduce the flooding and erosion
what is soft engineering?	schemes that are set up using knowledge of the sea and it's processes to reduce the effects of flooding and erosion
where is an example of a stump and a stack?	old harry and old harrys wife in Dorset
why can't caves and arches be seen n maps?	because of the rock above them
what do stacks look like on maps?	little blobs in the sea
how are cliffs and over steep slopes shown on a map?	as little black lines
how are wave cut platforms shown on maps?	as bumpy edges along the coast
how are wave cut platforms shown on maps?	as bumpy edges along the coast
what are the 3 main factors for protecting coastlines?	1.economical 2.social 3.environmental
name 3 economical factors as to why to protect a coastline	1.tourism-flooding and erosion can put people off visiting popular tourist destinations, and ruined attractions 2.businesses near cliffs 3. coastal flooding damages agricultural land salt water reduces soil fertility
name 3 social factors of why to protect a coastline	1.flooding can cause deaths 2.water supplies affected-flood water can pollute drinking water with salt/sewage 3.loss of housing-people can become homeless because their houses have collapsed into the sea
name 2 environmental factors why to protect a coastline	1.ecosystems affected-seawater has high salt content that can damage and kill organisms in ecosystem 2.Some SSSIs are threatened by coastal erosion
what does SSSIs stand for?	sites of special scientific interest
what is longshore drift?	when materials get moved along the coast
which way do the waves go?	in the direction of the prevailing wind
swash hits the coastline at an...	angle
the backwash the travels back into the sea at...	90 degrees
what is traction?	large particles (boulders) being pushed along the sea bed by the force of water
what is saltation?	pebble sized particles bouncing along the sea bed by the force of water
what is suspension?	small particles like clay get carried along in the water
what is solution?	soluble materials dissolve in water and are carried along
what is deposition?	when material being carried by the sea water is dropped on the coast
how do coasts build up?	when the amount of deposition is greater than the amount of erosion
2 ways the amount of deposition along the coast is increased	1.lots of erosion-lots of material available 2.lots of transportation-of material into the coastal area
name one characteristic of low energy waves..	they are slow waves that carry material to the coast via swash but they are not strong enough to take a lot of material away again afterwards-backwash meaning a lot of deposition and little erosion
what are constructive waves?	waves that deposit more material than they erode (they build up the coast)
what are coastlines called that a built up by constructive waves?	constructive coastlines
name 5 characteristics of constructive waves?	1.they have low frequencies between 6-8 waves per minute) 2.they're low and long 3.their swash is powerful and carries material up the coast 4.they have a weak backwash doesn't wake material away from coast 5.made by weak winds and they have a shorter fetch than destructive waves
how are beaches formed?	by deposition
where are beaches found?	on the coast between the high water mark and the low water mark
what wave are beaches formed by?	constructive waves
name 2 characteristics of sand beaches?	1.they are flat and wide 2.sand particles are small and weak so backwash can move them back down beach creating a long gentle slope
name 2 characteristics of shingle beaches?	1.they are steep and narrow 2.single particles have a large backwash can't move them back down the beach so create a steep slope
what is a spit?	a beach that sticks out into the sea joint to the coast at one end
what is a bar?	a spit that had stuck out so far that it connects to another bit of mainland
5 things about spits	1.they are formed at sharp bends in coastlines eg the river mouth 2.longshore drift transports past bend and deposits in the sea 3.strong winds and waves can curve the end of the spit 4.the sheltered area behind the spit is protected from the waves, so there is lots of material there where plants can grow 5.over time the sheltered area could become a mudflat or salt marsh
3 things about a bar?	1.formed when a spit joins two headlands together 2.it cuts off the bay between the headlands from the sea 3.a lagoon can form behind a bar
whats a bar called that connects the shore to an island(often a stack)?	A TOMBOLO
cliffs retreat as a result of...	erosion, weathering and mass movements
where do waves cause most erosion?	at the foot of the cliff
describe how a wave cut notch is formed.	1.erosion is taking place as waves hit against cliff 2. forming a wave cut notch where the waves has eroded a dent in the headland, making the material above unstable 3.the material then collapses 4.the material is then washed away and a new wave cut notch is formed 5.due to repetition of collapsing the cliff retreats making a wave cut platform
name two things the rate of retreat depends on...	1. The Geology of the cliff-cliffs formed from soft rock or loose material can retreat very quickly(several metres a year), cliffs formed from hard rock can be eroded over thousands of years 2.Vegetation-cliffs covered in vegetation are more stable so they erode less easily and retreat more slowly
what is mass movements?	the shifting of rock and loose materials down a slope
when does it happen?	when force of gravity acting on the slope is greater than the force supporting it eg when notch has become unstable
name the 3 different types of mass movements	1.slides 2.slumps 3.rockfalls
what happens in a slide?	material shifts in a straight line
what happens in a slump?	material shifts with rotation
what happens in a rockfall?	materials shift vertically
how are headlands and bays formed?	when erosion resistance alternates along the coast.
give an example of resistant rock and what land form is created	chalk-eroded slowly, left jutting out HEADLAND
give an example of a less resistant rock and what landform is created?	clay, eroded quickly forming material to mass move downwards forming a BAY
which two erosion methods cause cracks to enlarge in a headland?	hydraulic action and corrasion
how is an arch formed?	a cave gets eroded deeper till it breaks through the headland causing an arch
how is a stack formed?	erosion causes collapsed material meaning gap in the headland
how is a stump formed?	erosion means collapsed material falls down stumps can be covered in water at high tide
how are coves formed?	when there are parallel bonds of hard and soft rock. weakening in bond of hard rock a narrow gap will be eroded. the softer rock behind will then be eroded more to form a cove
what is a cove?	a wide circular bay with a narrow entrance
what is weathering?	the breakdown of rocks where they are
what is erosion?	when rocks are broken down then transported by something else eg seawater
what is mechanical weathering+example	the breakdown of rocks without changing it's chemical composition eg freezing thaw weathering method
what are the 5 main stages of the freeze thaw weathering method?	1.happens when temperatures alternate above and below 0 degrees c 2.water gets into rocks that have cracks eg granite 3.water freezes making it expand putting pressure on rock 4.water melts(thaws) it contracts which releases pressure on the rock repeated freezing and thawing widens the cracks causing the rock to break up
what is chemical weathering and example	the breakdown of rock by changing it's chemical composition eg carbonation weathering (acid rain)
what are the two steps of carbonation weathering?	1.rainwater has carbon dioxide dissolved in which makes it a weak carbonic acid 2.the carbonic acid reacts with rock that contains calcium carbonate eg limestone so the rocks are dissolved by the rainwater
what is hydraulic action?	when waves crash against rock compressing air in the cracks. putting pressure on the rock, repeated compression widens the cracks and makes bits of rock break off
what is corrasion?	when eroded particles in the water scrape and rub against the rock removing small pieces
what is Attrition?	eroded particles in the water smash into each other and break into small fragments their edges also get rounded off as they rub together
what is corrosion?	weak carbonic acid in seawater dissolves rock like chalk and limestone
what is a destructive wave?	a wave that carries outs erosional processes
what are coastlines being eroded by destructive waves called?	destructive coastlines
do destructive waves have a high or low frequency? and what is it?	HIGH between 10 and 14 waves per minute
what two properties do they have?	1.they are high and steep 2.their backwash is greater than their swash meaning material is removed from the coast
what are the two main factors affecting the size and power of a destructive wave and how much erosion takes place?	1.wind- the force of wind causing the waves. 2.Fetch-the distance of water over which the wind has blown to produce a wave. the greater the fetch the bigger the wave
what is backwash?	the movement of water back down the beach
what is swash?	the movement of water up the beach

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