coasts exam questions Flashcards
describe the characteristics of a sediment cell
closed systems
sections of coastline split into sub cells
headlands act as boundaries
no transfer between cells of material
what kind of influence do offshore currents have on the coast
large
how are ocean currents created
through earths rotation and convection
what is the global circulation belt driven by
salty dense water sinks down
pulls across warm water and nutrients are carried
name 5 transportation processes
solution
suspension
saltation
traction
LSD
describe the global pattern of ocean currents
warm ocean currents transfer heat from low latitudes to the poles
cold ocean currents move cold water from polar regions to equator
ho
how do global patterns of ocean currents affect coastal systems
transfer of hear energy directly affects air temp affecting sub aerial processes
what is a coast
narrow zone where land meets the sea
what is the importance of coasts
50% of the word live on coastal planes
name a
marine factor affecting coasts
atmospheric factor
terrestrial factor
wave type and tides
sun and moon and precipitation
rock type
what is a landscape
what is a landform
water is the main geomorphic agent
individual shape and character formed from processes in landscape
what is an example of an open system
what is an example of a closed system
open- the ocean as matter can enter and leave
the water cycle as matter doesn’t enter or leave
what is a system
set of intercalated objects comprising of stores and processes working together
name the two types of systems and explain them
open- transfers matter and energy across boundary
closed- transfers energy but NOT matter
what are the main energy and matter inputs in the coast
energy- solar energy, gravitational energy, geothermal
matter- rivers (90%), glaciers, offshore, cliffs, biotic
what are the main processes at the coast
erosion, transportation, deposition, weathering
what are the main erosional stores at the coast
what are the main depositional stores at the coast
erosional- stack , arch , cliff
depositional- spit, beach
what are the main outputs at the coast
sediments and landforms
define a sediment cell
what kind of system is a sediment cell
a length of coastline which is self contained
closed system
what are the boundaries like at sediment cells
headlands or estuaries
what type of energy causes tides
gravitational
what is a tide
regular rising and falling movements of the surface of the sea caused by gravitational pull of moon and sun
what is a semidiurnal and diurnal tide
semidiurnal = 2 high tides and 2 low tides a day
diurnal = 1 high and 1 low
what is meant by tidal range
vertical difference between high tide and low tide
what is a spring tide
forms when moon, sun and earth are aligned
what is a neap tide
forms when sun, moon and earth are at a right angle
what type of tide has the biggest tidal range
spring tides
what is the flood and ebb
speed of incoming tide
ebb= speed of outgoing tide
what are the significance of the flood and ebb
determines how long vegetation is exposed
low tidal range means more erosion due to concentrated water
how do low pressure and high pressure systems affect tidal range
low- contribute to cloudy and rainy conditions that are associated with high tides
high- depress sea levels leading to clear sunny days
how do onshore winds affect tidal range
may help pile water on shoreline eliminating low tide exposures
how do tapering channels affect tidal range
when tide enters mouth the height of the tide is increased by contraction of water
what is the most significant factor overall affecting tidal range
high and low pressure systems
what is wind
what are the differences in air caused by
movement of air from areas of high pressure to areas of low pressure
convection currents
what are global winds and local winds
large scale winds and can cause wind to blow in a consistent direction.
local winds are small scale
what are prevailing winds
winds that constantly blow in one direction
what is the Coriolis effect
describes how global scale winds are affected by the earths rotation
name the 3 main factors that affect the energy of waves
strength of wind
length of time wind blows
fetch
what is fetch
maximum length of water wind can blow unobstructed
where in the UK has the highest energy wave and why
south- farther fetch
what is a wave
movement of energy through water
name the main steps in a wave breaking
as waves approach coast and water gets shallower friction slows down base of wave
wave becomes more elliptical
as waves get closed to coast friction increases so top of wave moves faster then base
top of the wave curves and breaks
what is a sea and swell
sea - formed when wind blow directly on the ocean
swell- formed through wind, fetch and wind duration
what are the 3 types of wave
spilling, plunging and surging
what are the 3 main types of currents
ocean, coastal zone, tidal
what are surface ocean currents caused by
the coriolis efect
what is the Coriolis effect
deflection of air
what do ocean currents do to the coast
increase temp
how do rip currents affect the coast
helps transport sediments
remove sediment
what impact do tidal currents have on the coast
can affect weathering
transport sediment
what type of current has the biggest effect on the cost
tidal
what is lithology
chemical and physical characteristics/ properties of rock types
what is rock structure
the ways rocks are disposed or geologically arranged
why is lithology important
it varies the speed and types of coastal processes that occur
name a weak type of rock that erodes quickly
clay
what is porosity a measure of
what is permeability a measure of
how much rock is open space
the ease that water can move through porous rock
how is permeability and porosity similar
both measure the effect water can have on them
what significant process does porosity and permeability have influence over
weathering
describe the characteristics of horizontally bedded cliffs
- differential erosion occurs
-produces wave cut notches
describe the characteristics of seaward bedding planes
- produces gentle cliff
- loose material can slide down
- rockslides occur because of angle
describe the characteristics of landward bedding planes
steep and stable
faces away from erosion
describe the characteristics of landward bedding planes
steep and stable
faces away from erosion
what is weathering
disintegration and decomposition of rocks in situ
where does sub areal weathering occur
above the cliff face
how does the following types of weathering occur
freeze thaw
salt crystallisation
wetting and drying
- water gets into cracks and exerts pressure on rocks shattering it
- water gets into cracks and evaporates leaving crystals making them larger till the shatter the rock
- clay rich rocks expand when wet and contract when dry resulting in cracks which are venerable to other types of weathering
what is the most significant type of physical weathering
freeze thaw
how do the following types of chemical weathering occur
oxidation
hydrolysis
carbonation
oxygen dissolved in water reacts with minerals
when minerals absorb water
dissolving of minerals in water
what are the 3 main factors affecting weathering
temp
water and rainfall
lithology and rock structure
what is an example of biological weathering
tree roots growing into cracks and putting pressure on rocks
what is mass movement
movement of soil, sand and weathered material and tock downslope due to gravity
what 3 main forces influence mass movement
gravity
slope angle
water content of sloped material
what are the following and what are they caused by
rockfall
slides
slumps
rapid free fall of rock from steep cliff face due to gravity
movement are large material with internal structure retained
a slid with a rotational element producing a curved structure
how does water influence slumps
when it rains slumping is more likely to happen
how does the angle of a dip affect mass movement
landward dips reduce the chance of mass movement
seaward dips increase chance
when does attrition occur
materials bump into each other making them smoother and more rounded
when does hydraulic action occur
force of water against the coast causes air to get in cracks and expand
when does abrasion occur
coast is worn down by material carried in waves
when does solution occur
chemical action of sea water, acids slowly dissolve rocks on the coast
when does wave pounding occur
mass and force of breaking wave exerts pressure on rocks weakening it
what is
traction
suspension
solution
saltation
rolling of large and heavy rocks along sea bed
lighter sediment suspended within water
sediment that has dissolved will transported
smaller material bounced along sea bed
what is the swash and backswash
swash- wave that transports material
backwash- picks up and transports material
which way does LSD usually occur
direction of prevailling wind
when does longshore currents occur
when waves reach a beach and release energy the current runs parallel to the shoreline
when does deposition occur
when energy levels decrease and velocity decreases
what if fluvial deposition
when rivers enter the sea due to decrease in velocity
what is flocculation
meeting of freshwater and saltwater
when fine light materials clump together they become heavy and sink to the seabed
when does aeolian erosion occur
wind can carry small dry particles and erodes by abrasion
what is wind deflation
causes the lifting and transport of light particles
what is beach replenishment
replaces beach and cliff material that has been removed by erosion
name the sources, transfers and stores as a river moves into the sea
sources - currents and river
transfers- transportation and deposition
stores- mudflats
sinks- river removes sediment from system
what is the sediment budget
balance between sediment added and removed
what is a positive v negative sediment budget
positive = more inputs then outputs
negative = more outputs then inputs
name an example of what causes a deficit in the sediment budget
coastal erosion
whats an example of inputs outputs stores and transfers in sediment budget
inputs- rivers, glaciers etc
outputs- swept out by sea and storms
stores- beaches
transfers- LSD, longshore currents
what is an erosional landform
landform that has been created by erosional processes
what kind of rock can u fins at the following areas
Purbeck point
swanage bay
ballard point
purbeck limestone
clay and greensand
resistant chalk
what kind of coastline is around Swanage bay
discordant
what is an example of a discordant coastline in the UK
Isle of purbeck
what is Ballard point and what is it formed from
headland made of chalk
what effect does wave refraction have on headlands
concentrates energy on them increasing erosion
what is old harry rocks made of
chalk
what processes occur at a cliff
erosion at bade of cliff and sub areal weathering at top
what is an example of a wave cut notch in the UK and what does it show
Bat’s Head - shows that cliffs are actively being eroded
what factors affect rate of cliff retreat
balance of marine factors, eg wave energy, fetch and terrestrial eg lithology
when do steep cliffs occur
when rock is strong and resistant to erosion and dips landward
when do gentle cliffs occur
rock is weak and dips towards the sea
what is a wave cut platform
narrow flat area found at base of a sea cliff, created by erosion
what are the 2 types of wave cut platforms
sub- horizontal and sloping
what is an example of a wave cut platform in the UK
broad bench in Kimmeridge bay
what does a geo look like
how are they formed
what is an example of one in the UK
steep sided inlet
when a line of weakness is eroded by waves further widening it
due to faults being eroded more rapidly by wave action
North landing, Flamborough
what does a blowhole look like
how are they formed
what is an example of one in the UK
vertical shaft that reaches the top of a cliff
inland roof of a tunnel collapses
kiama blowhole, australia
what is a cove in a concordant coastline in the UK
lulworth cove in Dorset
what is a spit
what processes form spits
narrow linear, depositional landform
longshore drift and longshore currents
what causes spits to become hooked
wave refraction and a second less dominant wind direction
when does a compound spit form
when transport processes are variable over time
when does a bar form
when a spit grows along an embayment
what is an example of a lagoon that has formed behind a spit in the uk
slapton ley
how are tombolo’s formed
by wave refraction
waves slow down close to an island and bend around it causing a convergence of LSD on opposite side
beach sediments moving by transport accumulate there
name the 4 main zones on the beach
offshore, nearshore, foreshore, backshore
how does particle size affect the beach
water percolates more easily into a shingle beach so backwash is reduced increasing gradient of beach
fine sandy beaches have reduced percolation leading to increased backwash
what affect does steep waves have on beaches
tend to be plunging destructive waves which lower beach gradient
how do storm waves affect the beach and what forms as a result of this
erode beach and carry sand offshore
a low winter profile
how do summer swells affect the beach and what forms
build up beach by pushing offshore sand bars onto shoreline building high summer profile
when does a swash aligned beach form
where in the UK is an example of this
when waves break parallel to the shore and there is no significant longshore movement of sediment
Lulworth cove in dorset
when do drift aligned beaches form
when waves break at an angle to the shore
what do berms look like
what are they caused by
small ridged that develop on high tide mark
smaller waves with less energy
what is a storm beach caused by
very strong swash during storm conditions depositing large material
what are ridges and runnels caused by
spreading out of wave energy causes depressions called runnels
what are cusps caused by and what do they look like
semi- circular depressions formed by a collection of waves
what is an estuary
sediment store where sediment is deposited away from fast tidal currents
what is a delta
large areas of sediment found at the mouths of rivers
what is a salt marsh
where do they form
area of flat, silty sediment
sheltered areas, where salt and freshwater meet, no strong tidal currents
name the steps in formation of a salt marsh
1- mud deposited close to high tide line due to flocculation
2- pioneer plants colonise area between high tide and low tide and further trap sediment
3-mudlfats build in height and become colonised by more plants
4-vegetation traps more sediment reducing time plants are submerged allowing more colonisation
5-vegetation creates friction which slows tidal currents
6- land continues to rise and eventually above sea level
what are the benefits of salt marshes
natural defence against erosion and flooding
productive ecosystems
what are the threats of saltmarshes
climate change and rising sea levels
human activity and management
how are the following at high energy coastlines
wave power
height of waves
sheltered or exposed coast
dominant processes
typical landforms
destructive
high plunging
exposed
erosion
stacks, stumps, headlands
how are the following at low energy coastlines
wave power
height of waves
sheltered or exposed coast
dominant processes
typical landforms
constructive
low spilling
sheltered
deposition
spits, bars tombolos
where is farewell spit located
south island in new Zealand, separate’s golden bay from Tasman sea
name 3 characteristics of farewell spit
27km long
width is 0.6-1.25 km wide
comprised of fine, well sorted sand
describe how farewell spit was formed
rivers flowing from southern alps during floods would transfer sediments to Tasman sea
heavy sediments would sink but finest material was carried to the top of the south island
what physical factors helped form farewell spit
longshore drift and longshore currents
wind generated waves (60%)
how is farewell spit linked to golden bay
spit shelters bay from high energy tasman sea
name 2 characteristics of golden bay
37 meters deep
northern side being infilled by drifting sand and mud
name 2 characteristics of saltmarshes and mudflats at golden bay
- occupy area of 320 ha
elevation of 0.3 to 1.5 m above mean sea level
name 2 characteristics of the dunes at golden bay
over 20 m high
comprised of sine well sorted sand
how is the spit and salt marshes related at golden bay
spit provides ideal conditions for shelter for salt marshes
results in low energy environment
high sediment supply and low gradient of tidal flat encourages deposition from rivers
how is the spit dependant on the bay at golden bay
bay provides change in coastal direction for LSD to continue t open sea to create spit
how is the bay dependant on the spit at golden bay
spit shelters bay from high energy Tasman sea and is effected by prevailing winds protecting it from erosion
why are the dunes dependant on the spit at golden bay
spit has increasing supply of sediment and has westerly winds which is ideal for dune formation
name 3 short term changes affecting farewell spit
storms changing shape of spit
tidal flats flooding daily
colonization of spit
name 2 long term changes affecting farewell spit
prevailing wind can return it to pre storm shape
erosion or landward sea rise increase as sea level increases
name 2 human changes over time to the spit
lighthouse building
stock grazing
removal of cattle
what is eustatic sea level change
global sea level change
what is isostatic sea level change
local change in relation to uplift and lowering of crust
which sea level change is a longer term process
isostatic
name 2 factors is eustatic change caused by
thermal expansion( increase in temp means increase in size of water molecules)
ice cover on land (cooling of climate leads to glaciers and ice caps melting meaning fall in sea levels)
changes in shape of sea floor - caused by plate tectonics
what is isostatic depression
sinking of earths crust into atmosphere due to heavy weight eg ice sheets
what is post-glacial isostatic rebound
when load on lithosphere is reduced and ground slowly rebound back to equilibrium levels
what is happening to land in the north of england
still rising due to isostatic recovery
what is happening to land in the south of england
sinking due to north rising
what is a factor that can cause uplift in mountain ranges
destructive plate margins causing relative fall in sea levels
what is a raised beach
once active beach / wave cut platform that are now well above sea level
what may cause a raised beach
sea level dropping( eustatic)
land raised(isostatic)
where is an example of raised beaches
turkiare head, new zeland -6.4 m
why might a raised beach not loo like a beach anymore
weathering, added material
what is an abandoned cliff caused by
cliff forming processes that have stopped as waves can no longer reach the cliff
what is a ria
a drowned river valley
describe the formation of a ria
- sea levels rise relative to land submerging coastal river valley
sue to isostatic or eustatic sea level rise
resulting in large estuary at mouth
give 2 examples of ria characteristics
shallow cross section but deep where river channel was
exposed sides
what is a fjord
long, narrow coastal inlet with steep sided cliffs
how are fjords formed
when a glacial trough is flooded by rising sea levels
name an example of a fjord location
new zeland
name 2 characteristics of fjords
steep, valley like sides
very deep water
shallower at the coast
what are shingle accumulations a result of
past processes
name 2 examples of human activities on the coast
urbanisation
tourism
what is a shoreline management plan
large scale assessment of risks of coastal processes and tries to reduce these risks
what are the 4 approaches to shoreline management plans
do nothing, hold the line, retreat the line, advance the line
what is a cost benefit analysis
analysis of cost effectiveness to see if benefits outweigh risks
what is hard engineering
artificial, manmade structures used to protect coastlines against erosion
what is soft engineering
natural approach to managing the coast
name 2 examples of issues when managing the coast
rising sea levels
hard or soft engineering
name 2 examples of hard engineering processes when managing the coast
sea walls, rock armour
what is beach nourishment
replaces cliff or beach material- sand is brought from offshore deposits and transported back to beach
what is rainbowing
extraction of sand from sea bed and it ejects it through the air
name 3 reasons why sandbanks needs protecting
large number of high value properties
marine, yacht clubs
footpaths and tourist facilities
name 2 economic activities that occur at sandbanks
hotel and haven bring in spending for the local economy
beach is a major tourist attraction with a blue flag award
name 2 physical reasons why sandbanks needs protecting
erosion rates becoming worrying(1.6 m ) per year
longshore drift could cause the harbour to become clogged and shallow
what was done in the 2 phases to protect sandbanks
1- rock groynes and dune regeneration
2- new rock groynes and more dune regeneration
name a consequence of rock groynes at sandbanks
didnt completely stop erosion
why was recharge done at sandbanks and how much did its width increase by
to reduce lowering and narrowing of beach due to groynes
50 meters
what is the pakari and managawhai beach
20km stretch of coastline in NZ
what is the significance of the magawhai beach
sand is used as a mineral resource
sending dredging has occurred here for over 70 years
what is the sediment budget like at the pakari-managwai beaches
extraction rates are 5x higher then inputs so stores are depleted
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the PM beaches
beaches starved of sediment and less affective at absorbing waves so eroded
what impact has dredging had on the sand dunes
base of dunes are being undercut by waves due to beaches not absorbing wave energy
more wind erosion on dunes
what impact has dredging had on spits
storm caused a 28km breach in spit removing material from dune system
