formed due to the transfer of
energy and the direction of the
prevailing wind
DEPENDS ON: the distance
the wind has blown, the
speed its travelling, and how
long its been travelling.
destructive waves
occur in stormy conditions, high
wave height in proportion to
length, high frequency, high
energy, large fetch, responsible
for erosion, greater backwash
than swash, steep beach
constructive waves
occur in calm conditions, low wave height in
proportion to length, low frequency, low
energy, transport material via long shore
drift, responsible for deposition, greater
swash than back wash
LONG SHORE DRIFT
beach sediment is transported along the coast by waves .
LANDFORMS
BEACHES
DEPOSITIONAL LANDFORM, formed by
CONSTRUCTIVE WAVES, consist of SAND OR
SHINGLE, made up of VARYINGLY SIZED
SEDIMENT DUE TO LOCAL GEOLOGY AND
WAVE ENERGY
BAYS & HEADLANDS
EROSIONAL LANDFORM: bays and
headlands develop on discordant
coastlines, eg. a mixture of hard and soft
rock. commonly found where cliffs have
fault lines/ distinctive joints.
the soft rock eg. gravel, sand and clay
erode quickly, forming bays, eg. lulworth
cove, devon.
the hard (resistant) rocks eg. limestone and
chalk take much longer to erode and are left
jutting out into the sea, as headlands-, eg.
lands end, cornwall
WAVE CUT PLATFORMS
EROSIONAL LANDFORM: the erosion of
cliffs by undercut waves at their base
creates a wave cut notch- this leaves an
overhang.
the overhanging rock collapses and the
cliff retreats inland, resulting in a wace
cut platform
CAVES, ARCHES, STACKS & STUMPS
EROSIONAL LANDFORM: CAVES. formed by hydraulic
action widening cracks in the cliff face , generally found
on headlands formed from harder resistant rock.
ARCHES: a cave that is eroded all the way through
the cliff face, eg. durdle door.
STACKS: the apex of the arch collapses as it is
weakened by weathering, leaving a singular pillar
out to sea, eg. canna stack
STUMPS: the stack collapses due to erosion and
weathering, resulting in a collapsed stack, or a
stump . (eg. old harry, dorset.)
SPITS, BARS & TOMBOLOS
DEPOSITIONAL LANDFORMS: SPITS.
created by longshore drift, a stretch
of beach material is carried out to
sea from the mainland, eg. spurn
point, yorkshire. the spit can change
shape dependent on wind direction.
BARS: in the same way as a spit, a
stretch of beach sediment reaches
across a bay, connecting two
headlands eg. Loe bar. a lagoon
forms behind the bar, which
eventually becomes a salt marsh.
TOMBOLO: a bar or spit that reaches
an island, eg. st ninians
COASTAL PROCESSES
EROSION- wears away rock and
removes eroded material
abrasion
pebbles picked up by
waves are flung at cliffs ,
wearing the cliffs away
attrition
pebbles carried by
waves collide with
other particles and
become round and
smooth
corrosion
rocks and minerals are
dissolved by water
hydraulic action
waves hitting the cliffs force air into
cracks- the pressure created breaks up
the rocks.
WEATHERING- wears away
rocks but leaves weathered
material in situ
biological
tree roots and burrowing
animals break soil structure
physical
eg. freeze thaw (water damage),
onion skin (expanding and
contracting due to temperature)
chemical
eg. acid rain, attacking alkali
limestone
MASS MOVEMENT
rock falls
FRAGMENTS OF ROCK created by
WEATHERING FALL to the CLIFF BASE
slumping
the CLIFF BASE is ERODED BY
THE SEA and the TOP IS
SATURATED BY RAIN- the cliff
starts to slide.
soil creep
SLOW MOVEMENT of SATURATED
SOIL creeping down a slope,
resulting in TERRACETTES
COASTAL RECESSION
CLIFF EROSION CAUSES CLIFFS TO RECEDE,
AND THEREFORE THE COASTLINE
IMPACTS
NATURAL:
LOSS OF HABITAT (durlston
bay, dorset, home to 250
species of birds)
HUMAN:
LOSS OF PROPERTY
(durlston bay, dorset,
Happisburg, norfolk) LOSS
OF BUSINESSES (holbeck
hotel, yorkshire, 1993.)
issues caused: DIFFICULT TO GET
INSURANCE, LOWERS PROPERTY
PRICES, LIMITED GOVERNMENT
SUPPORT FOR HOME OWNERS
CAUSES
FETCH- a larger open body of water eg. the atlantic
means a larger fetch, s o bigger more destructive
waves cause more erosion
GEOLOGY- harder more resistant rock eg. in the north
west of the UK erodes slowly compared to soft rocks
aka clay and sand in th south east of the uk.
COASTAL MANAGEMENT- coastal defences can
slow down the rate of erosion and protect the
coastline.
COASTAL
FLOODING
CAUSES
causes are: HIGH TIDE LEVELS,
STORM SURGES the ACTION OF
WAVES (influenced by wind speed)
and RISING SEA LEVELS (caused by
global warming and thermal
expansion)
PREVENTION
BARRIERS to protect against high tides, aka
the thames barrier, FLOOD PLAINS- areas of
open space to allow floodwater to spill over.
FLOOD WALLS built long rivers, eg. the
thames
PLANNING
PREDICTION: the EA monitors sea
conditions to help predict potential
flooding, EARLY WARNING SYSTEMS are
put in place, FLOOD EDUCATION eg. what
to do in the event of a flood , ESCAPE
ROUTES, ADVICE from services such as the
EA nand the health protection agency.
areas at risk are
LOWLYING, aka the
NETHERLANDS, the
MALDIVES,
BANGLADESH,
NORFOLK
manmade elements
COASTAL ENGINEERING
HARD
traditional approach,
involves building
structures
CURVED SEA WALLS
PROS: protects cliffs and
buildings, reassures home
owners, can prevent coastal
flooding
CONS: ugly, can cause
erosion of beach in front,
wall may erode,
maintenance is constant
and expensive. costs
£5000- £100000 to build
per linear metre
eg. blackpool, porthleven
GROYNES
PROS: prevents long shore drift, builds up beach (acts as
natural defense against erosion, attracts tourists),
cheapish to build at £2000 per m
CONS: can cause erosion further along the coast,
ugly, needs replacing regularly
eg. eastbourne
RIP RAP
PROS: absorbs wave energy, helps
build up the beach, relatively cheap
(£1000- £3000 per m)
CONS: not as effective as other
methods, transport can be difficult
eg. dawlish warren
OFFSHORE REEF
PROS: prevents erosion of beach,
disperses wave power
CONS: expensive (£5000 per m),
interferes with fishing,
eg. bournemouth,
happisburgh
SOFT
better for nature, focuses
on tourism and the
environment
DUNE STABILISATION, LONG ROCK-
sand dunes absorb wave energy and
educe coastal erosion- stabiliation
prevents them from receeding
BEACH REPLENISHMENT,
CARLYON BAY- prevents the
loss of coastal footpaths, a
natural defense against
erosion
happisburgh
SMALL TOWN, on NORFOLKS
NORTH COAST
THE ISSUE: one of the fastest
eroding places globally, at 9m
per year
WHY: the village is built on soft rock
which erodes quickly. the cliffs are
only 6-10m high and are made of
laminated clay. the north sea has a
large fetch, resulting in large
destructive waves .
IMPACTS: house prices have dropped from £80
000 to £1, residents will be made homeless, over
20 square miles of farming land would be lost.
PREVENTION: wooden revetments, no longer
maintained as too expensive. off shore reef,
only partially effective. the government is
recommending managed retreatt as
happisburgh not worth saving- CCAG and local
residents disagree