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