COASTS
8/17/2019 Coasts Ppt for Year 11
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The coast is a narrow contact zone
between land and sea. It isconstantly changing due to theefects o land, air and marine
processes. The power o the waves the seacarries determines the type oprocesses that take place.
8/17/2019 Coasts Ppt for Year 11
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Wave Energy
1. Waves are created when wind blowsover the surace o the sea creatingriction.
. The size and energy o a wave variesaccording to its speed and theamount o time the wave has been
moving.
• Waves are biggest and have themost energy when the wind isstrong, has been blowing or a longtime and has come a long way.
• The distance over which a wave has
travelled is called fetch.!. "riction with the sea bed slows down
the bottom o the wave but the topo the wave continues moving at thesame rate and topples orward,braking against a clif or beach.
• Swash is water that washes up abeach
8/17/2019 Coasts Ppt for Year 11
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The size of the wave depends on…
• The strength of thewind.
• How long the wind blowsfor.
• The length of the waterthe wind blows over –called the fetch.
Extension: which waveswould be stronger? Why?
A: aribbean – !"#: $outh A%erica & Africa
A
B
#$oasts lesson % wave ormation
8/17/2019 Coasts Ppt for Year 11
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#rea'ing waves
• &s waves approachthe shore, thebottom o the wave
catches on the seabed ' causing thewave to build up(become taller).
The wave thenspills over (breaks)onto the beach.
(otice how the wave is )falling forward* – ithas built up and is brea'ing onto the shore.
*$oasts lesson % wave ormation
Extension: Tsunami+s are a
type o wave but are notcaused by wind. $an yousuggest what causes themLO1: I can describe how a wave
8/17/2019 Coasts Ppt for Year 11
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T"#ES O$ WA%E
There are two types o wave-
• $onstructive
• estructive
8/17/2019 Coasts Ppt for Year 11
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Constr&ctive
This wave haslimited energymost o this is used
by the swash totransport materialup the beach.
8/17/2019 Coasts Ppt for Year 11
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'estr&ctive
This wave hasmuch more energy./ost o this is used
by the backwash totransport materialback down thebeach.
8/17/2019 Coasts Ppt for Year 11
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0ot all waves are the same. The beachprole (shape o the beach) can be diferentdepending on how the waves break
Constr&ctive
• 2uild beaches.
/aterial is carried upthe beach in thestrong swash and isdeposited as thebackwash is weak '3ummer.
'estr&ctive
• estroy beaches. They
are very high andre4uent. Thebackwash is strongand transports beachmaterial out to sea 'Winter.
5
$oasts lesson % wave ormation
Extension: add 6beach prole+ toyour glossary with an accuratedenition.
LO(: I can identify the di)erences between constr&ctive and
8/17/2019 Coasts Ppt for Year 11
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$wash +s #ac'washSwash * oveent of water
&+ the beachBac,wash * oveent ofwater down the beach
Happens when the wave breaks:water rushes up the beach
Happens after the swash, when thewater is draining back into the sea.17
$oasts lesson % wave ormatio
Extension: 8ow might seasons afect theswash and backwash
8/17/2019 Coasts Ppt for Year 11
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The #each ,rofile
Constr&ctive 'estr&ctive
Gentle beaches are formed by
constructive waves.
Steep beaches are formed by
destructive waves. 11
$oasts lesson % wave ormation
Extension: name e9amples oplaces you might nd constructiveand destructive beach proles.
LO-: I can ex+.ain how di)erent waves can sha+e a variety
8/17/2019 Coasts Ppt for Year 11
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Which parts of the #ritish -sles willreceive the biggest waves and why?
Thin, abo&t the $ETC/0.ength of the water
Extension: Which +arts ofthe British Is.es wi.. receive
the sa..est waves andwhy2
he !epublic of "reland, and South#$est England %&ornwall' receive
the biggest waves as the fetch stretches across the (tlantic )cean.
$ e t c h
1
$oasts lesson % wave ormation
LO1: I can describe how a wave
8/17/2019 Coasts Ppt for Year 11
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Coasta. #rocesses
There are three main processes atwork in the sea-
:rosion
Transportation
eposition
8/17/2019 Coasts Ppt for Year 11
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Erosion
This is destructive waves wearing away the coastline. It happenswhen the waves are packed with energy. :rosion destroys landorms.
Waves erode in fo&r ways-
• /ydra&.ic action% Is when waves crash against clifs trapping and
compressing air and water in rock cracks. &s the waves move back,pressure is released causing the air and water to e9pand. Thise9plodes breaking of rock ragments.
• Abrasion%Is when breaking waves pound rocks and pebbles againstthe clifs wearing the land away in a sandpaper efect.
• Attrition%Is when waves smash rock ragments against each othermaking pebbles smoother, rounder and smaller. In time, the particlesare ground into grit and sand.
• Corrosion% Is when the chemicals in the sea water dissolve or rotrocks like limestone and chalk
8/17/2019 Coasts Ppt for Year 11
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What is coastal erosion % ;ouTube.mp#
8/17/2019 Coasts Ppt for Year 11
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The waves $O3CEwater into crac,s in
the roc,s!
This is ca..ed/"'3A4LIC
ACTIO5
8/17/2019 Coasts Ppt for Year 11
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This isca..ed
AB3ASIO5
The +ebb.esact .i,e
sand+a+er!
3o&gh seas 6ing+ebb.es against the
roc,s
8/17/2019 Coasts Ppt for Year 11
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The waves ,noc, ch&n,s of roc,together!
The roc,s end&+ as +ebb.eson the beach
This is ca..edATT3ITIO5
8/17/2019 Coasts Ppt for Year 11
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The water 'ISSOL%ES
so.&b.e ateria. frothe roc,s!This is ca..ed
SOL4TIO5
$ f t
8/17/2019 Coasts Ppt for Year 11
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he waves throw
sand, pebbles andlarge stones againstthe rock. hey wear
it away like sand
paper. his is calledabrasion.
he water dissolves
the rock. his iscalled solution.
&hunks of rock getknocked together
and worn into
smaller pieces. hisis called attrition.
$aves force waterinto cracks in therock, this pressurebreaks up the rock
# called hydraulicaction.
8/17/2019 Coasts Ppt for Year 11
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./ovie<%<$oastal<=ung<"u.wmv
8/17/2019 Coasts Ppt for Year 11
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CO#" T/E 'IA73A8 A5' A'' T/E CO33ECT LABEL$3O8 T/E $OLLOWI57:• 3eova. of stac, to create a st&+9• en.argeent of cave to for an arch9
• geo.ogica. wea,ness 0e!g fa&.t9• foration of sea cave by erosion9• co..a+se of arch to for st&+
8/17/2019 Coasts Ppt for Year 11
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Trans+ortation
Is the movement o material in the sea and along thecoast by waves.
• Transport along the coast is when waves move material
across a beach. This is long shore drit.• The prevailing wind causes the waves to break on the
beach at an angle
• 3wash carries the material up the beach at an angle.2ackwash drags the material back down the beach at right
angle.• :ach wave pushes material urther along the beach.
• /aterial is moved along the beach in the direction o theprevailing wind.
8/17/2019 Coasts Ppt for Year 11
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ransport *rocesses
8/17/2019 Coasts Ppt for Year 11
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ransport
*rocesses
+ongshore rift
raw an annotated diagra% to e/plain the process of longshoredrift.
8/17/2019 Coasts Ppt for Year 11
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'irection of+revai.ing wind
'irection of .ongshore driftoveent
swash
Bac,wash
Backwash isalways at rightangles to thebeach
>ongshore drit
8/17/2019 Coasts Ppt for Year 11
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Evidence forLS'
8/17/2019 Coasts Ppt for Year 11
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Which way is LS' oving sedient2
8/17/2019 Coasts Ppt for Year 11
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What is a storm beach
8/17/2019 Coasts Ppt for Year 11
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'e+osition
Is the dumping oeroded material onthe land by
constructivewaves. It happenswhen the waveshave less energy.
eposition createsland orms such asbeach,spit, marshand dune belts.
8/17/2019 Coasts Ppt for Year 11
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Beach
& beach is alandorm along theshoreline o an
ocean, sea, lake orriver. It usuallyconsists o looseparticles which are
oten composed orock, such as sand,gravel, shingle,pebbles or
cobblestones
8/17/2019 Coasts Ppt for Year 11
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S+it
& spit is ane9tended stretch obeach material that
only ?oins themainland at oneend. They start toorm where there is
a change in thedirection o thecoastline.
8/17/2019 Coasts Ppt for Year 11
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3tages o spitdevelopment-
8/17/2019 Coasts Ppt for Year 11
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Spits and salt marshes
8/17/2019 Coasts Ppt for Year 11
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Sa.t arsh
3alt marshes maybe ormed behind aspit. The zone
behind a spitbecomes asheltered area.Water movement
slows down and somore material isdeposited.eposition may
orm a salt marsh.
8/17/2019 Coasts Ppt for Year 11
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A sa.t arsh fors when incoing tides carry andde+osit sedient across .ow.ying .and; res&.ting in
wet &d6ats! Sa.twater grasses then s.ow.y ta,eho.d and s+read; stabi.ising the .and thro&gh thegrowth of root systes! As the +.ants decay andsedient b&i.ds &+; +eat de+osits acc&&.ate;
foring a rich habitat that s&++orts the growth of
8/17/2019 Coasts Ppt for Year 11
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Salt -arshes
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They often deve.o+in the .ee 0she.tered+art of a s+it!
8/17/2019 Coasts Ppt for Year 11
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The sand dunes
at HengistburyHead are in the
early stages of
formation…
Sand unes
Sand une formation.
8/17/2019 Coasts Ppt for Year 11
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f
$hat you need is:
8/17/2019 Coasts Ppt for Year 11
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$actors which a)ect the s+eed that
8/17/2019 Coasts Ppt for Year 11
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$actors which a)ect the s+eed thatthe coast.ine is eroded:
. !ock type
/. $ave type
0. "f there1s a beach
2. Human activity
%pollution3walking'
4. 5egetation
ask: 0ist thesefactors which affectthe speed of coastal
erosion. 1or each2write one sentencee/plaining how this
affects erosionspeed.
8/17/2019 Coasts Ppt for Year 11
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These are sea stac's. -n groups of two write down a shortparagraph about how you thin' that they for%ed.
8/17/2019 Coasts Ppt for Year 11
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How do we protect the coast• To be able to e/plain how different types of coastal
defences wor'.• To be able to e/plain the advantages and the disadvantages
of all of the different %ethods of protection.
Coasta.8anageent
8/17/2019 Coasts Ppt for Year 11
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SEA WALLAbsorb wave energyso the c.i) foot is
+rotected froerosion
8/17/2019 Coasts Ppt for Year 11
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3i+ra+: @ip%rap is basically giantboulders placed at the oot (bottom) oclifs. @ip%rap is designed to absorb thewaves energy and protect the clifsbehind. @ip%rap can be efective, butdoes look ugly, may reduce access tothe beach and can be e9pensive.
@IA% @&A
8/17/2019 Coasts Ppt for Year 11
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7royne
s
Wooden ences built out into thesea. They stop long shore drit andbuild up the beach. & wide beachabsorbs more wave energy
8/17/2019 Coasts Ppt for Year 11
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3E%ET8E5T
They are similar to sea walls, but oten builtout o wood. Bten ound at the oot o clifsthey are designed to absorb the waveenergy. &gain they need replacing regularly
and do not protect against big storms.
CLI$$
8/17/2019 Coasts Ppt for Year 11
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CLI$$3E73A'I57
This means make clifs less steep. $lifsoten become unstable because oundercutting. 2y reducing the angle youshould reduce the undercutting and the
risk o the clif collapsing.
$lifs oten collapse because they
8/17/2019 Coasts Ppt for Year 11
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p ybecome saturated and theincreased stress causes them tocollapse. 2y removing some o thee9cess water you should reduce
stress on the clif.
Beach'rainage
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BEAC/
$EE'I57
:9tra sediment is dumpedon the beach to increase itssize. & wider beach willabsorb more wave energy
and protect clif
How can the coastline be protected?
8/17/2019 Coasts Ppt for Year 11
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p
Hard engineering techniques aim to stop coastal processes
from occurring. Soft engineering methods try to work with
nature to protect the coast.