Coasts Flashcards
What is mechanical weathering?
Mechanical weathering is the breakdown of rock without changing its chemical composition. Eg: freeze thaw
What is freeze thaw?
It happens when water enters rock that has cracks
When the water freezes it expands which puts pressure on the rock
When the water thaws it contracts which releases the pressure on the rock
Repeated freezing and thawing widens the cracks and causes the rock to break up
What is chemical weathering?
It’s the breakdown of rock by changing its chemical composition.
Eg:carbonation weathering
How does carbonation weathering happen?
Rainwater has co2 dissolved in it which makes it a weak carbonic acid
Carbonic acid reacts with rock that contains calcium carbonate
So the rocks are dissolved by the rainwater
What is mass movement?
It’s the shifting of rocks and lose material down a slope
It happens when the force of gravity acting on a slope is greater than the force supporting it
What are slides?
Slides are when the material shifts in a straight line along a side plane
What are slumps?
Slumps are when material rotates along a curved slip plane
What are rock falls?
Rock falls are when material breaks up and falls down a slope
What is erosion?
Erosion is when rocks are broken down and carried away by something
What is fetch?
Fetch is the distance the wind blows over the sea
What is a storm surge?
Storm surges are temporary sea level rises caused as strong winds push water onshore
What are destructive waves?
Destructive waves erode the coast as their backwash is more powerful than their swash
What are some properties of destructive waves?
They have a high frequency and are high and steep
What is backwash?
Backwash is water moving down the beach
What is swash?
Swash is water moving up the beach
What are some properties of constructive waves?
They have a low frequency and are low and long
What are the 4 erosional processes?
Hydraulic action, abrasion, attrition and solution
What is hydraulic action?
When waves crash against rock they compress air into the cracks and this puts pressure on the rock
Repeated compression widens the cracks and causes bits of rock to break off
What is abrasion?
Eroded particles in the water scrape and rub against rock removing small pieces
What is attrition?
Eroded particles in the water collide, break into smaller pieces and become more rounded
What is longshore drift?
The prevailing wind brings the waves in at an angle
The swash is then carried up the beach in the same direction of the wave
The backwash then carries material down the beach at right angles
Overtime this causes sediment to move in a zig zag along the beach
What are the processes of transportation?
Traction, suspension, slatation and solution
What is traction?
Traction is large particles like boulders being pushed along the sea bed by the force of water
What is suspension?
Suspension is when small particles like silt and clay are carried along in the water
What is saltation?
Saltation is when pebble sized particles ard bounced along the sea bed by the force of water