April Flashcards
What is weathering
The action of weather, plants and animals on rock
What is erosion
Wearing away and removal of rock, soil etc by rivers, sea, ice and wind
Hard rock coast &example
Lands end.
Cliff face bare
High steep& rugged
Sea is clear
Soft rock coast& example
Yorkshire coast
Mud on cliff
Less rugged not as steep
Sea is brown
Erosion examples
Abrasion-waves hurl small pebbles or sand at the cliff
Hydraulic Action-breaking waves smash into cliffs, air is forced into cracks in cliff, air loosens and breaks away rock
Attrition-when rocks&pebbles collide together
Solution-minerals in rock eroded away by salt water
What are waves
Wind dragging on the waters surface
What is the “fetch”?
The distance the wind blows over the surface of the water
Size and energy of a wave is influenced by:
- How long wind has been blowing
- wind strength
Swash
——>
Backwash
Swash > backwash
Constructive waves
Swash
Deconstructive waves
Constructive waves
Strong swash Weak backwash Long wavelength Low height Hits 6-9 times a minute
Destructive waves
Weak swash Strong backwash Created in storm conditions Big strong waves because of powerful wind High wave Short wave length Tail breaker breaks downwards with force eroding coast Travels over fetch
The stronger the wind
The longer it blows for
The longer the fetch
The larger the waves will be
Explain how headlands and bays form
Due to waves, soft rock erodes faster than harder rocks. As the soft rock erodes faster, a bay is then left. The hard rock remains and doesn’t erode like the soft rock, so it remains as a headland
What is a concordant coast?
When hard and soft rock is parallel. Example Lulworth Cove. Limestone at front and clay at back. Waves cut through a weak spot at front. There is more resistance chalk at back so it takes longer to erode.
How does longshore drift cause spits??
Swash and backwash causes longshore drift. Sediment is moved through the beach until it reaches headland and attaches itself
The zig zag pattern follows wind direction
A change in wind direction causes the longshore drift to curve and go back on itself
This is what causes the curved shape of the spit
Discordant coast
Hard and soft rock at right angles to the coast Swanage bay Hard rock- limestone Soft Rock- clay Creates headland and bay effect
Explain formation of wave cut platforms
- when there’s high tide at the bottom of a cliff, overtime part will wear and erode, creating a wave cut notch.
- the wave cut notch tries to hold up the top heavy cliff but eventually collapses.
- the process then starts again, leaving behind a wave cut platform that is only visible in low tides
Transport
Waves also carry eroded material
What is longshore drift?
Movement of sediment along beach. Provailing winds hit at an angle, causing swash at a diagonal angle. The swash picks up sediment which is then brought straight down into the sea by back wash. This process will repeat causing a zig zag motion.
What are groynes?
- put in place where longshore drift occurs
- stop sediment from moving along beach
- causes a build up of sediment depending on where the wind is blowing
- positives: reduce/get rid of sediment on beach
- negatives: reduced sand in some areas means places behind beach may not be protected
Three different types of weathering
Biological
Mechanical
Chemical
Biological weathering
- action of plants and animals on rock
- when a seed is put in a tree by an animal (e.g a rat)
- the seed is still able to receive some sunshine and rain water
- its roots grow, pushing rocks apart
Mechanical weathering
- the sea has salt in it so when the sea hits rock, small salt crystals are forced into cracks in the rock
- the salt crystals grow and collide, pushing rock apart and causing it to crumble.
Chemical weathering
- action of water, contains small amounts of acid
- it hits the rock, causing parts to fall off and dissolve
- acid rain causes this
- you get acid rain from pollutants in factories, cars etc
What is geology?
The study of rocks and how they’re arranged
