COASTS! Flashcards
what is the littoral zone?
a series of sub-zones to represent the features of the wider coastline from sea to land
sub-zones of the littoral zone:
foreshore
nearshore
backshore
offshore
what do concordant coastlines have?
alternating bands of hard and soft rock parallel to the coast
what kind of cliff profile do bedding planes that dip towards the sea create?
gentle
types of coastline:
discordant
concordant
names of coastlines:
concordant (aka Pacific coasts)
discordant (aka Atlantic coasts)
what is the dip?
the angle that the rock layer forms with the horizontal bedding plane
what is an example of a rock type in Dorset is most resistant to erosion?
Portland limestone
what are Dalmatian coasts?
made up of offshore islands and coastal inlets running parallel to the coast eg. Lulworth Cove, SW Dorset coastline
which kind of rock is most susceptible to erosion and weathering?
sedimentary
bedrock lithology:
igneous eg. basalt, granite
sedimentary eg. limestone, chalk
metamorphic eg. slate, marble
what are typical plants that colonise embryo and foredunes?
sea rocket and sea crouch- have deep roots and can tolerate high concentrations of salt
which type of dune plant can withstand high concentrations of salt from seawater?
halophyte
which are some mobile dunes nearer the sea?
yellow dunes
foredunes
embryo dunes
bedrock lithology:
the physical properties of different rocks
igneous rocks:
form from the crystallisation of magma
sedimentary rocks:
form from build up, compacting and hardening of sediments into layers over time by lithification
metamorphic rocks
formed from the change in the structure of sedimentary and igneous rocks, caused by variations in heat and pressure
types of wave:
constructive waves
destructive waves
what are the processes of erosion that affect coastal landscapes?
hydraulic action
abrasion
attrition
corrosion
corrosion:
when there is a chemical reaction between the seawater and susceptible rocks
abrasion:
where pieces of rock are picked up by waves and hit against the bed, beach or cliffs
hydraulic power:
where the force of the waves hitting against other rock causes the rock to break down
attrition:
where pieces of bedload are hit against one another
erosion of headland -> landforms:
cave
arch
stack
stump
formation of wave cut platforms:
erosion causes a wave-cut notch to form
erosion of the wave-cut notch causes the rock above it to collapse
waves wash away the collapsed material and begin eroding the cliff again
multiple collapsing events lead to the cliff retreating leaving behind a wave-cut platform
examples of coastal landforms created by the erosion of headlands:
cave
stack
arch
when does longshore drift happen?
when waves move up the beach at an angle because of a prevailing wind direction
examples of coastal landforms caused by deposition:
bar
spit
beach
what are transfers in the sediment cell concept?
longshore drift
onshore and offshore winds
tides
the process of longshore drift:
wind approaches coast at an angle
swash moves up beach at this angle
backwash falls back to sea at right angles to coastline
next swash comes in at same angle and deposits sediment further down beach
what are spits?
long fingers of sand sticking out from one side in a coastline. often have salt marshes behind them
when is a bar formed?
when a spit grows across a bay
what is the sediment cell concept?
a closed system operated by sources, transfers and sinks driven by erosion, transportation and deposition processes
what are the sources in the sediment cell concept?
subaerial processes
erosional processes
sediments brought coastline by rivers
salt weathering:
seawater gets into cracks in rocks
salt crystals form when seawater evaporates
salt crystals expand and put pressure on rock
repeated evaporation of saltwater widens cracks
weathering processes:
biological weathering
chemical weathering
mechanical weathering
what are slumps?
a type of mass movement in which material moves with a rotation
what are slides?
type of mass movement in which material moves in a straight line
what is the main type of mechanical weathering affecting coasts?
salt weathering
types of mass movement:
slumps
slides
rockfalls
isostatic change processes:
during an ice age the weight of the ice makes the land sink
the ice age finishes
the land rebounds back up like a spring
what is the name for the change causing land to either rise or sink at the boundaries where tectonic plates meet?
tectonic change
types of coastlines that cause the formation of different landforms:
emergent
submergent
according to the IPCC, how much had sea levels risen between 1901-2010?
0.19m
what is an example of eustatic change?
water is stored in the form of ice when the world is experiencing an ice age which causes the sea level to fall. as the world moves out of an ice age the ice melts which results in the sea levels rising again
an example of an emergent coastline:
Fife (Scotland)
how will the increased frequency of storms caused by climate change affect coasts?
strong winds create high energy destructive waves
more material can be transported and for greater distances
frequency of storm surges will increase
what is an example of a subaerial process that increases the rate of coastal recession?
mass movement
what is the rate of coastal recession varied and caused by?
several factors including short and long term wind direction, tides, seasons, weather systems and storm occurrence
what does dredging involve?
the removal of sediment for use in construction
impacts of dredging:
sediment is removed in dredging
removal of sediment causes the depth of the ocean to increase
there are more destructive waves at the coast because they can maintain their energy further towards the shoreline
the coast gets eroded more quickly so coastal recession is sped up
the effect of tides on coastal retreat:
when the gravitational pull is at its strongest, there are high tides
when the gravitation pull is at its weakest, there are low tides
impacts of climate change on coastal flooding:
- changing frequency and intensity of low pressure depressions
- causes oceans to warm, triggering these low pressure systems
- causes more unusual weather conditions
how is the disturbance of mangroves in the Maldives leading to increased wave energy and height?
because the trees would normally act as a barrier helping to dissipate wave’s energy before it reaches land
what threatens the lives of people living near the coast in Bangladesh?
storm surge
consequences of coastal flooding in the Maldives:
threatens freshwater sources
tourism industry declining
risk of being completely submerged
losses from coastal recession: and
economic: eg. UK economy lost £1.2bn from disruption caused by 2 month closure of railway, eg. $216bn worth of infrastructure lost to rising sea levels in Australia
social: eg. people in Maldives relocating, eg. jobs in tourism in Maldives declining
examples of hard engineering coastal defences:
sea walls groynes rip-rap offshore breakwaters revetments
what is a cost of beach nourishment and reprofiling?
removing sand and shingle from the seabed threatens certain organisms such as corals and sponges
pros and cons of offshore breakwaters:
:( expensive to install
:) provides calmer conditions behind breakwater
:( can cause wave patterns to change
:) allow the beach to be used safely for recreational sports
examples of soft engineering coastal defence strategies:
cliff regrading
dune regeneration
beach nourishment and reprofiling
the ICZM:
created in 1992 at the Earth Summit
considers social, economic and environmental implications
considers implication of coastal recession on local economy
what does ICZM stand for?
Integrated Coastal Zone Management
shoreline management approaches:
strategic realignment
hold the existing defences
advance the line
no active intervention
what does CBA stand for?
cost- benefit analysis
what does no active intervention mean?
no management used along the coastline with physical processes allowed to work naturally
ways to assess whether to manage a coastline:
CBA determines economic value
EAI determines implications on environment
what does EIA stand for?
Environmental Impact Assessments
