Coastal systems and Landscapes Flashcards
define coast
the coast is a boundary between land and sea. Its dynamic environment consists of natural processes interacting with human activity
where is an example of a rocky coastline?
the white cliffs of Dover, Kent
where is an example of a coastal plain?
Keyhaven marshes, Hampshire
define littoral zone
the part of the sea close to the shore
explain how waves form
- start as a circular orbit in open water
- wave starts to become more elliptical In movement
- increasing elliptical orbit, the waves begins to break
- wave breaks causing swash and backwash
define swash
the movement of water up the beach when a wave breaks, deposits material
define backwash
the movement of water down the beach caused by gravity, causes erosion
what is the crest?
the highest part of a wave
what is a trough?
the lowest part of the wave
define the wavelength
distance between two successive crests
define wave height
difference in height between the trough and crest
what are factors that affect wave size?
wind speed
wind duration
fetch
what are some properties of a constructive wave?
- strong swash
- deposition
- spilling waves
- 6-8 per minute
- generated by distant weather
- longer wavelength
what are some properties of a destructive wave?
- erosion
- plunging waves
- local storms
- 13-15 per minute
- strong backwash
- shorter wavelength
why do surfers prefer constructive waves?
because they have a greater wavelength
what is an example of a high energy coastline?
Newquay, Southwest UK
what is an example of a low energy coastline?
keyhaven marshes, Hampshire
how do ocean currents influence the coast?
ocean currents move water around the worlds oceans due to thermohaline circulation
they can affect the coast by eroding areas that face ocean currents and deposit in areas facing away from the currents
what are tides caused by?
the gravitational pull of the moon and sun
what is the tidal range?
the difference between height of high tide and the height of low tide
define erosion
marine erosion is the process of the sea wearing away the coast. This occurs by tides and wave action.
what are the 5 types of erosion?
attrition hydraulic solution abrasion cavitation
explain attrition erosion
rough pieces of rock fallen from cliff collide causing them the break down into smoother rocks
explain abrasion erosion
material carried by waves is thrown against the rock edge making it smoother
spring tide
when the sun, moon and earth are in a straight line.
tidal range increases
neap tide
when the sun and moon are at right angles to the earth.
tidal range decreases
name the 8 factors that influence erosion
tides fetch geology beach size human activity location of coastline wave steepness climate change
define landform
an individual feature created by marine processes. Some are created by erosion (caves). some are created by deposition (beaches)
define landscapes
the bigger picture. A combination of land, sea and coast, possible including landforms. (Great Ocean Road, Australia)
backshore
very back of the beach
normally dry
only exposed to waves in extreme conditions
foreshore
fully exposed in low tide
waves break here in high tide
nearshore
waves break here at low tide
safe for paddling at low tide
offshore
out at sea
deeper water
wind turbines can be constructed here
explain hydraulic erosion
waves break against rock compressing water and air into cracks. this repeated stress causes bit of rock to break off
explain solution erosion
weak acids in sea water dissolve calcium carbonate in some rocks
explain cavitation erosion
air bubbles trapped in fast moving water break against rocks underwater causing them to weaken
fetch
distance of water over which the wind blows
describe wave refraction
as waves approach the coast they bend. This means that wave energy and erosion is focussed on headlands and wave energy is dissipated in bays leading to deposition.
it occurs due to shallow water in headlands exerting friction on waves, slowing them. dipper water in bays allows them to keep going at the same speed
differential erosion
the rate at which different rocks erode
weathering
the breakdown of rock in their original place. Breaks rock down into sediment that can be used for erosion
mass movement
downhill movement in response to gravity of a rock and soil. sediment is created for erosion
runoff
heavy rain flowing down a cliff causing erosion
freeze thaw
repeated expansion and contraction of water in cracks
carbonation
carbon dioxide in rain forms carbonic acid which dissolves calcium carbonate in rocks
soil creep
wet soil particles increase in size and weight, they expand at right angles and contract vertically creating a slow movement downslope
rotational slip
heavy saturated soil sits on top of impermeable clay, creating a lubricated slip plane
mudflow
saturated soil flows downhill, triggered by heavy rain
landslide
rapid movement of detached slabs of rock slide down a slide plane
rockfall
individual rock fragments fall off cliff face often due to freeze thaw
salt crystallisation
salt water from waves evaporated leaving behind crystals, these grow over time and apply pressure to crack the rocks
wetting and drying
clay particles of soil expand when wet and contract when dry, this weakens soil and makes cracks vulnerable to other weathering
biological weathering
- roots grow in cracks of rocks
- birds and animals dig burrows in soft rock
- rain passing through dead matter becoming acidic
- marine organisms can secreate acids
examples of metamorphic rock
marble, slate
northern scotland
examples of igneous rock
basalt, granite
giant causeway, northern ireland
examples of sedimentary rock
sandstone, limestone, clay, chalk
malham cove
strata
layers of rock
bedding planes
horizontal natural breaks in the strata
joints
vertical fractures caused by contraction of sediment or tectonic movement
folds
formed by pressure during tectonic activity making rocks buckle
faults
formed when pressure on a rock exceeds its internal strength and causes fractures
dip
angle at which the strata lies
traction
BEDLOAD
large materials are dragged along the seabed. this requires the most energy
saltation
BEDLOAD
smaller particles bounce along the sea bed. requires less energy
suspension
SUSPENDED LOAD
fine silt and clay material is carried by the water. it may discolour it. requiring minimal energy
solution
DISSOLVED LOAD
minerals like limestone and chalk are dissolved in water. requires little energy
long shore drift
movement of sediment along a coastline.
swash comes in at same direction to prevailing wind. backwash at right angles to the beach
what are influences of coastal transport
weight of sediment
energy of waves
conditions required for deposition
when sediment loads exceeds ability of water and wind to carry it
sheltered coastline
low energy coastline
marine deposition
sediment carries by water
aeolian deposition
sediment carried by wind
what are the 3 types of dip
horizontal
landward dipping
seaward dipping
pebble beaches are
steep and narrow
water percolates through the shingle meaning backwash is limited
sandy beaches are
flat and wide
very little percolation happens meaning backwash can carry material down the beach
storm ridge
large material thrown at the back of the beach by more powerful waves
berms
a step ridge found at high tide marks. material deposited by swash. often lots of ridges as tides move from spring to neap
cusps
crescent shaped indentations forming on beaches.
sides channel incoming swash into centre of cusp and a strong backwash drags material down from centre of cusp
runnels
grooves in sand running parallel to the shore.
formed by strong backwash draining to sea. exposed at low tide
swash aligned beach
orientated parallel to incoming waves.
minimal longshore drifts.
constructive wave patterns
(eg. loee cornwall)
drift aligned beach
waves approach at angle to shoreline.
longshore drift transport sediment. beaches are narrow
(eg. ordforness suffolk)
spit
extended stretch of beach that projects out to sea and joined to mainland at one end
(eg. spurn point yorkshire)
tombolo
a spit that joins an island to mainland
eg. st ninians isle
bar/ barrier beach
long stretch of beach that joins two headlands.
eg. slapton ley devon
barrier island
when a beach becomes separated from the mainland
offshore bar
ridge of material created by waves offshore from the coast.
eg. culbin sands Scotland
how are spits formed
sediment from erosion is transported by longshore drift and is deposited at the point where the coastline changes direction.
plants colonies behind the barbs to form salt marsh.
what is a compound spit
a spit that forms barbs due to a change in wind and wave direction
how do destructive waves create offshore bars
destructive waves can erode sediment from the beach with their strong backwash and deposit it offshore
how do gently sloping coats create offshore bars
friction between the waves and seabed cause waves to break at a distance from the coast. over time the materials are built up parallel to the coast to from a offshore bar.
dynamic equilibrium
a balance between input and outputs of a system
open system
has inputs from outside the system
closed system
transfers of energy both into and beyond the system boundary. but there’s no transfer of matter
positive feedback
changes are amplified. system responds by increasing the effects of change moving the system even further from its original state
negative feedback
system responds by decreasing the effects of change. keeping the system closer to its original state
sediment budget
balance between sediment being added and removed from a sediment cell
examples of positive sediment budget
cliff collapse
increase river discharge
more constructive waves
examples of negative sediment budget
storm conditions
groynes
human activity
natural succession
the evolution of plant communities over time
pioneer species
plants that initially colonise and can withstand extreme conditions
climax vegetation
the vegetation is in a state of equilibrium with the environment. Oak woodland in the UK
plagioclimax
if human interference takes place (eg. cattle grazing) then the climatic climax vegetation will not be reached and it will be a plagioclimax instead
psammosere
plant succesion in a sand dune environment
what 6 features are needed for sand dunes to form
- plentiful supply of sand
- strong onshore winds
- an obstacle to trap sand
- large tidal range
- gentle slope beach
- large flat backshore area
sand dune
an accumulation of sand shaped into mounds by the wind. Sometimes found at the back of beaches on low energy coastlines and swash aligned beaches
why do dunes nearer the sea have a ph above 7
the contain more shell fragment containing calcium carbonate which is alkaline making the dune more alkaline
what is the dominant plant species in sand dunes
marram grass
how does marram grass create larger dunes
its growth is triggered by being burried in sand
halophytes
plant that can withstand saline conditions
what conditions must pioneer plant endure
salty conditions, periodic submergence
example of pioneer plant in dune environment
sea rocket
how do dune slacks occur
when the land dips below the water table, creating a wet environment and ponds when it rains
estuary
the transition zone between fresh water environment and maritime water environment. A mixture of salty and fresh water
flocculation
individual clay particles stick together forming larger heavier particles that sink to the sea bed
examples of mudflat areas
morcambe bay, uk
cape cod, usa
dominant plant species in salt marsh environment
spartina
how do spartinas roots create salt marsh
fine mat surface roots bind mud together.
thick deep roots can secure up to 2m of deposited material
halosere
plant succession in a salt marsh environment
why might some coastlines be protected
high population
cost benefit analysis
tourism
important landmarks
what are some argument FOR coastal protection
stops cliff collapse
stops coastal flooding
saves economic, social, environmental damage
creates jobs
what are some arguments AGAINST coastal protection
very expensive with ongoing costs money needed elsewhere management in one area may disrupt another area aesthetics don't fit surroundings interferes with nature
how many sediemnt cells are there in England and wales
11
shoreline management plan
manage a cell rather than a political area, this means that management in one area wont affect another
hold the line
maintain current position of coastline
advance the line
building defences out to sea. Not common in the UK
managed retreat/ strategic realignment
allowing coast to move naturally, managing process to direct it to another area
do nothing
let nature take its course
hard engineering
coastal protection that uses engineered man made structures. Eg. sea wall
soft engineering
coastal protection that works with nature. Eg. Beach nourishment
cost benefit analysis
only when the benefits exceed the cost can a coastal protection project go ahead
outflanking
protection in other areas leading to differential erosion. Over time town project out to sea meaning they require more management which is unsustainable and unaffordable
eustatic change (global)
the change in the amount of water in the sea.
global warming increases sea levels due to thermal expansion as water gets warmer. It is also due to melting freshwater ice sheets.
isostatic change (local)
the change in the position of the land relative to the sea.
when large ice sheets cover the land it weighs it down causing the land to sink, this is called isostatic subsidence
when the ice melts the weight is lifted, this is called isostatic readjustment.
tectonic change (local)
at destructive and collision plate boundaries tectonic plates push into each other causing lands to be lifted. This leads to a relative fall in sea level.
Tectonic activity can cause the land to fall leading to a relative rise in sea level.
Ria
drowned river valley
when sea levels rise the lower courses flood leaving high land visible.
affected by high tides, low tides reveal extensive mudflats
branching v shape with gentle profile
commonly found in southwest England
E.g Falmouth, Cornwall
Fjord
drowned glacial valley
as sea levels rise u shaped valleys left behind by glaciers are submerged
they are relatively straight and narrow with very steep sides
u shaped cross section
shallower section at mouth due to reduced erosion as glacier came into contact with sea
E.g Sogne Fjord, Norway
Dalmation coast
long slim islands parallel to coast
sea levels rise and flood low valleys
Higher ground remained above sea level and form a pattern of islands
E.g Croatia
Raised beaches
areas of former wave cut notches and their beaches which are at a higher level than the present sea level.
over time, beach sediment becomes vegetated and develops into soil
(eg. Isle of Arran, Scotland)
marine platforms
a wave cut platform that now exist as an extensive flat area in front of a relict cliff, which has features such as caves, arches and stacks.
They are no longer eroded by the sea.
They slowly get covered in vegetation.
The raised features are degraded by weathering and mass movement.
(eg. Isle of Arran, Scotland)
landforms of submergence
caused by sea levels rising
rias
fjord
Dalmatian coast
landforms of emergence
caused by sea levels falling
raised beaches
marine platforms
