Coasts KQ1- How can coastal landscapes be viewed as systems? Flashcards
What kind of system is the coastal system?
an open system
Why is the coastal system considered to be an open system?
Energy and matter can be transferred both in and out
What are the 8 factors that interact to form a coastal landscape?
- soils
- air and climate
- landforms
- geology
- wind
- waves
- tides and currents
- humans
Define sediment cell
A stretch of coastline and its associated nearshore area within which the movement of course sediment, sand, and shingle is largely self-contained
What type of systems are sediment cells?
Closed systems however in reality it is likely they are completely closed
How many sediment cells are there around England and Wales?
11
What determines sediment cells?
Topography and shape of coastline (e.g lands end acts as a large natural barrier)
Name 3 inputs of energy into the coastal system
- Winds
- waves
- solar sources
Name 4 sources of sediment inputted into the coastal system
- oceans
- rivers
- cliffs
- coastal areas further along the coast
Give two outputs of energy
- heat
- noise
How is material outputted in the coastal system?
-it is moved to other parts of the coast and offshore
Give 6 examples of (geomorphic) processes
- erosion
- transportation
- deposition
- sedimentation
- weathering
- mass movement
Give 5 examples of stores
- saltmarshes
- mudflats
- sand banks
- beaches of varying material type
- spits
Which 5 physical factors influence the coastal landscape?
- winds
- waves
- tides
- geology
- ocean current circulation
Define erosion
the wearing away of material by the action of ice, wind, and water
Define weathering
The disintegration of rocks by the action of the weather, plants, animals, and chemicals in-situ
Define landform
A physical feature on the Earth’s surface
A range of sub-aerial and marine processes are responsible for coastal landforms. What factors determine the effectiveness of these processes?
- Geology
- Aspect
- Wind
- Sea level change
- Climate
- Time
How are winds important for landforms?
They:
- form waves
- erode landforms
- transport and deposit materials
What are dominant winds?
-perpendicular to the coast, usually storm winds and the strongest winds
What are prevailing winds?
-the most common direction
3 factors that affect wave strength
- strength of wind
- length of time it blows for
- distance which the wave has travelled
Define fetch
The distance the wind blows across the sea
Define swell
Where the waves first form initially in the ocean
Define swash
Where a wave washes up a beach
Define backwash
Where a wave moves down a beach
What sort of beaches do constructive waves tend to occur on?
Why?
- beaches with a low angle/gradient
- because there is a wide area for the wave to move across and so energy soon dissipates
What sort of beaches do constructive waves tend to occur on?
Why?
- beaches with a steep gradient
- because energy is concentrated on a smaller area
What are the key characteristics of constructive waves?
- strong swash
- weak backwash
- a lot of peculation through sand
What are the key characteristics of destructive waves?
- weak swash
- strong backwash
- little peculation through sand
What are the 4 factors that affect wave energy?
- swell size and frequency (fetch/windspeed/distance travelled)
- Tides
- Local weather conditions
- Form of the beach
What are the 4 factors affecting waves in the ocean?
- Storms (generate high energy waves)
- Size of swell window
- Sea floor gradient (shallow offshore gradients absorb wave energy and reduce wave height)
- Fetch
What is the swell window?
The amount of open ocean facing a stretch of coastline
Give 2 examples of the landforms typically found on low energy coastlines
- beaches
- spits
Give 2 examples of the landforms typically found on high energy coastlines
- headlands
- wave-cut platforms
How do the rates of erosion and deposition differ between low and high energy coastlines?
- at low energy coasts the rate of deposition exceeds the rate of erosion
- whereas along high energy coastlines the rate of erosion exceeds the rate of deposition
What is the promontory effect? What does this mean for the coastline?
- Waves are refracted towards headlands
- Wave energy is concentrated on headlands rather than bays
Why does the promontory effect occur?
- water shallower at headlands than bays
- shallower water means waves slow down more so refraction caused
- refraction causes energy to be concentrated on headlands
What do winds control?
- fetch
- swell window
Besides wave energy, what other factors may influence the development of landforms by erosion, transportation and deposition? (6)
- beach slope
- form of coastline
- geology
- sediment supply
- sea level change
- human acitivity
Why do tides occur?
-they are the result of the gravitational attraction of the moon and sun
How do spring tides compare with neap tides?
-spring tides are the highest tides whilst neap tides are the lowest tides
Why are spring tides the highest?
-the sun, moon, and earth are all in alignment so there is an increased gravitational pull
What is the Coriolis effect?
-the effect the of Earth’s rotation on air and water
What 3 factors affect tidal range?
1- Coastal configuration (e.g in Liverpool the channel narrows causing funnelling
2- Water depth- a tidal wave can undergo refraction and focus on some stretches of coastline
3- Width of continental shelf, causes friction and increases wave height
What direction does the ebb tide go?
Out
What direction does the flood tide go?
In
How do tidal ranges influence the landscape?
- width of intertidal zone
- location of wave activity
- erosion, deposition, transportation
- wetting and drying
How does wetting and drying influence the landscape?
- wet sand is less likely to blow away
- salting weathering is influenced by wetting and drying
How would the UK be classified in regard to tidal range?
Macrotidal
Define lithology
The chemical composition of the rock and the physical arrangement of its grains
How can bedding planes, faults, and joints increase erosion of rock?
- allows water into the rock
- increases permeability
- increases susceptibility to weathering (e.g freeze-thaw weathering)
- therefore increasing erosion
How can cementation affect rock?
- poorly cemented rock is porous
- also permeable along faults
- surface area of rock exposed to weathering is increased
- leads to weakening of the rock
How can a discordant coastline lead to differential erosion?
- lines of weakness exposed
- waves can actively select lines of weakness to erode
Why are discordant coastlines less likely to be eroded?
-they have fewer lines of weakness exposed to wave action
What causes permeability?
-the incidence of pores, fissures, cracks, and joints in rocks
Why is rock hardness an important factor?
- affects the ease of erosion
- affects the chances and time it takes for cliff recession
What is differential erosion?
The process by which, due to different characteristics, rocks break down at different rates
How does tidal range affect weathering?
-a larger tidal range means more time for weathering (e.g salt crystallisation)
Define clastic
Small fragments of pre-formed rock
Define crystalline
Composing of interlocking crystals
Define rock
A mass of mineral matter
