Coasts Flashcards
Coasts
What is longshore drift?
Material being transported along the coast
Coasts
How does longshore drift work?
Waves follow prevailing wind. Hit coast at oblique angle. Swash carries material on beach in direction of wind, backwash carries material off beach at 90 degrees.
Coasts
What are the 4 processes of transportation?
Traction, saltation, solution and suspension
Coasts
What is traction?
Large particles (boulders) pushed along sea bed by force if water
Coasts
What is saltation?
Pebble sized particles bounced along sea bed by force of water
Coasts
What is suspension?
Small particles (silt/clay) carried along in sea water
Coasts
What is solution?
Soluble materials dissolve in sea water and carried along
Coasts
What is deposition?
When material carried by sea water is dropped on coast
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When do coasts build up?
When amount of deposition is higher than amount of erosion
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How is amount of deposition increased?
When lots of erosion elsewhere on coast - lots of material available.
When lots of transportation of material into an area
Coasts
What do low eve energy waves do?
(Slow) lots of deposition, less erosion
Coasts
What do constructive waves do?
Deposit more than erode. Break up on beach, build up beaches
Coasts
When are constructive waves created?
In calm weather
Coasts
What are the characteristics of constructive waves?
Stronger swash than backwash. Less powerful than destructive. Low, long wavelength. Low frequency (6-8 per minute).
Coasts
What is transportation?
The movement of material
Coasts
What is longshore drift?
Material being transported along the coast
Coasts
How does longshore drift work?
Waves follow prevailing wind. Hit coast at oblique angle. Swash carries material on beach in direction of wind, backwash carries material off beach at 90 degrees.
Coasts
What are the 4 processes of transportation?
Fractions, saltation, solution and suspension
Coasts
What is traction?
Large particles (boulders) pushed along sea bed by force if water
Coasts
What is saltation?
Pebble sized particles bounced along sea bed by force of water
Coasts
What is suspension?
Small particles (silt/clay) carried along in sea water
Coasts
What is solution?
Soluble materials dissolve in sea water and carried along
Coasts
What is deposition?
When material carried by sea water is dropped on coast
Coasts
When do coasts build up?
When amount of deposition is higher than amount of erosion
Coasts
How is amount of deposition increased?
When lots of erosion elsewhere on coast - lots of material available.
When lots of transportation of material into an area
Coasts
What do low eve energy waves do?
(Slow) lots of deposition, less erosion
Coasts
What do constructive waves do?
Deposit more than erode. Break up on beach, build up beaches
Coasts
When are constructive waves created?
In calm weather
Coasts
What are the characteristics of constructive waves?
Stronger swash than backwash. Less powerful than destructive. Low, long wavelength. Low frequency (6-8 per minute).
Coasts
What is transportation?
The movement of material
Coasts
What is weathering?
Erosion of rocks in situ
Coasts
What is erosion?
Wearing away of moving rocks
Coasts
What are 3 examples of biological weathering?
Vegetation roots break up rocks.
Bird ps excrete on rocks - acidic.
Rabbit burrows loosen soil making inundation by water easier.
Coasts
What is rainwater?
Carbonic acid (weak)
Coasts
What is mechanical weathering?
Breakdown of rocks without changing chemical composition
Coasts
What is chemical weathering?
Breakdown of rocks by changing chemical composition
Coasts
What is carbonation?
Rainwater (carbonic acid) dissolves rocks e.g. Limestone or clay
Coasts
What is freeze thaw weathering?
Temp alternatives above/below freezing. Frozen water expands in cracks and contracts when it thaws. Repeated expansion widens cracks/breaks rock.
Coasts
What is hydration?
Rocks like clay swell and expand in rainwater (carbonic acid)
Coasts
What is mass movement?
Shifting in rocks and loose materials down a slope when gravity acting ok slope is greater than force supporting it.
Coasts
What is oxidation?
Some rocks react with air and break down
Coasts
What does mass movement cause?
Coasts to retreat rapidly
Coasts
What is sliding?
Material shifts in one sheer vertical piece (straight line), often quickly
Coasts
When is mass movement most likely?
When material is full of water (lubricant)
Coasts
What is slumping?
Water soaks through permeable top layer of sand and collects above impermeable layer. Lubricated layer causes slumping on a curved axis.
Coasts
What do destructive waves do?
Carry out erosional processes
Coasts
When do destructive waves occur?
When wave energy is high and wave has travelled over a long fetch
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What are the characteristics of destructive waves?
High frequency (10-14 per min).
High and steep.
Short wavelength.
Backwash more powerful than swash.
Coasts
How are destructive waves created?
In storm conditions when wind is powerful and blowing over long time.