Coastal Environments in the UK Flashcards
What factors affect wave size
Wind strength
Fetch
Time Wind has blown for
What is prevailing wind
The most prominent wind direction at a specific time
What is the prevailing wind in the UK
SW
How does wind strength affect wave size
The stronger the wind, the greater the friction on the sea, the bigger the wave
How does wind duration affect wave size
The longer the wind has been blowing, the more energy is transferred to the surface of the sea, the bigger the wave
Why do waves break
Friction slows the base of waves whilst the top maintains its speed
This causes the top of the wave to topple over the base
What is swash
The movement of the wave up the beach
What is backwash
Gravity moving the wave down the beach
What are constructive waves like
Shallow
Low energy
Strong swash, weak backwash
What do constructive waves do
Build up the beach by depositing material in the swash
What are destructive waves like
Steep
High energy
Weak swash, strong backwash
What do destructive waves do
Erode the beach by dragging material in the backwash
What is coastal erosion
The loss of land and/or the removal of material along the coastline as a result of destructive waves and other hydrological processes
How does hydraulic action work
Waves force water into cracks in rocks, this compresses the air inside
This explosive action of trapped air in a rock is called cavitation
Cavitation leads to loose sediment entering the ocean.
How does attrition work
Kinetic energy transferred to rocks by waves causes the rocks to swash into each other
These rocks get broken up and worn down and eventually end up on the shore
How does solution work
Seawater is slightly acidic and can dissolve material from the coastline
This is particularly apparent in limestone and chalk as they contain calcium carbonate which is easily dissolved
How does abrasion work
Waves smash rocks into the coastline
This causes the coastline to be worn away and chipped
What is coastal transport
The movement of sediment, eroded from the coastline, by waves
What determines how sediment is transported
The size of the sediment
How does solution transport material
Dissolved material is carried along the coastline by waves
How does saltation transport material
Small pebbles moving along the seas floor by hitting each other
How does suspension transport materials
Fine sediment is suspended in the water and moved with the direction of the waves
How does traction move material
Larger pebbles and cobbles roll along the seafloor
What is the direction of coastal transport in the SW
NE
What is weathering
When rock is broken down by physical, biological and chemical means
What is weathering mostly caused by
Meteorological and climatic factors
How can physical processes weather rock
When water freezes it expands and makes cracks in rocks bigger
When the ice thaws, water seeps deeper into the rock
This process repeats and causes fragments of rock to break off and fall to the base fo the cliff (scree)
What types of rocks are more vulnerable to weathering by physical processes
Permeable and porous rocks (as water can seep deeper into them)
How can chemical processes weather rock
Rainwater absorb CO2 from the atmosphere and become slightly acidic
Calcium carbonate in rocks can be dissolved by carbonic acid in rainwater
How can biological processes weather rock
Plants and animals break up and crack rocks
Burrowing animals may break up or destabilise rocks
Plants can break up rocks as their roots grow
What is mass movement
The downwards movement of materials due to gravitational pull
What is a rockfall
The free-fall of rocks from a cliff face
This is worsened by freeze-thaw action
This forms a scree slope at the base of the cliff
What is a mudflow
A rapid movement following rainfall
This occurs when there is not enough vegetation to hold topsoil in place
This occurs on slopes >10°
What is a rotational slip
A rapid movement of earth or rock sliding along a concave plane
This occurs after periods of heavy rain
What is a landslide
Earth, pebbles, rocks and boulders sliding down a slope
What is a landform
A feature of the landscape that has been formed by erosion, transportation or deposition
What is a headland
A piece of land jutting out into the sea, made from more resistant rock
What is a bay
A part of the coast where the land curves in so that the sea is surrounded by land on three sides
By which erosional processes are most coastal landforms made
Abrasion and hydraulic action
What is a discordant coastline
A coastline made up of alternating bands of hard and soft rock
This results in the formation of headlands and bays
Why do discordant coastline result in the formation of headlands and bays
Soft rock erodes faster, leaving an indent, m while hard rock sticks out into the sea to form a headland
What is a wave-cut platform
A flat area the sea has eroded at the bottom of a cliff
This is caused by the cliff collapsing at high-tide level due to wave-cut notches
What is a wave-cut notch
A dent at the base of a cliff that the sea has eroded
This gets bigger and an overhang forms
The weight of the overhang eventually causes the cliff to collapse; the cliff retreats and leaves a wave-cut platform at its base
What is long-shore drift
The transportation and deposition of eroded material along the coastline
How does LSD work
Waves approach the beach at an angle
The backwash carries the sediment down the beach due to gravity
This repeats, moving sediment across the beach laterally
When does water deposit sediment
When the water no longer has the energy to carry the sediment
What is wave refraction
Shallow water results in friction that slows down the wave
This causes other parts of the wave to curve around the area of shallow water, sheltering the regions beside it
What is a spit
A stretch of sand of shingle jutting out into the sea from the land
How do spits form
LSD carries sediment
When the shape of the coastline changes, deposition occurs, forming a spit
When do hooks form on spits
When there is a change in wind direction
How to marshes and mudflats form behind spits
Waves cannot get past the spit, sheltering the water behind it
Silts are deposited here to form marshes and flats
What is a bar
A spit that has grown across a bay, connecting two headlands
How does a lagoon form
A bar traps a body of water behind it
What is a tombolo
A spit that has grown from the shoreline to an island
How do sand dunes form
Embryo dunes are formed around deposited objects
These develop and become stabilised by vegetation
Vegetation rots and adds organic material to the dune, making it more fertile
More plants colonise the dune
What does Marram grass do in the formation of sand dunes
Marram grass is adapted to windy conditions and has long roots to find water
These roots help to bind and stabilise the dune
