Unit 1 C Coastal Landscapes In The Uk Flashcards
What is mechanical weathering
The breakdown of rock without changing its chemical compositions
What is chemical weathering
The break down of rock by changing its chemical composition
How does freeze-thaw weathering break up rock
- happens when temperatures alternates above and below 0°c
- water gets into rock that has cracks
- when water freezes it expands,putting pressure on the rock
- when water thaws it contacts,releasing pressure on rock
- repeated freezing and thawing widens the crack and causes rock to break up
How do carbonation weathering break up rocks
- rainwater has co2 dissolved in it which makes weak carbonic acid
- carbonic acids reacts with rock containing calcium carbonate so that rocks are dissolved by rainwater
What are the 3 types of mass movement
- slides-material shifts in a straight line
- slumps-material shifts with a rotation
- rockfalls-material breaks up and falls down slope
What are the 3 processes of erosion by waves
- hydraulic action
- abrasion
- attrition
How do wave cut platforms form
- Wave erodes base of cliff which forms wave-cut notch which is enlarged as erosion continues
- rock above notch becomes unstable and eventually collapses
- collapsed material washed away and new wave-cut notch starts to form
- repeated collapsing results in cliff retreating
- a wave-cut platform is the platform left behind as the cliff retreats
How are are Headlands and bays formed
- where there are alternating bands of resistant and less resistant rock along coast
- less resistant rock is eroded quickly and this forms a bay- bays have a gentle slope
- the resistant rock is eroded more slowly and its left jutting out,forming a headland- headlands have steep sides
Formation of caves,arches and stacks
- waves crash into the headlands and enlarge the cracks—mainly by hydraulic action and abrasion
- repeated erosion and enlargement of cracks causes a cave to form
- continued erosion and enlargement deepens the cave until it breaks through the headland forming an arch
- erosion continues to wear away the rock supporting the arch until it eventually collapses
- this forms a stack—an isolated rock that’s separated from the headland
How does longshore drift transport material along the coast
- waves follow direction of the prevailing wind
- they usually hit the cost at an oblique angle
- the awash carries material up the beach in the same direction as the waves
- backwash then carries material down beach at right angles,back towards the sea
- over time material zigzags along the coast
What are the 4 processes of transportation
Traction—large particles like boulders are rolled along the sea bed by force of water
Saltation—pebble-sized particles are bounced along sea bed by force of water
Suspension—small particles like silt and clay are carried along in the water
Solution—soluble materials dissolve in water and are carried along
What is deposition and when does it occur
When material being carried by seawater is dropped on the coast. Occurs when water carrying sediment slows down so isn’t moving fast enough to carry so much sediment
When can the amount of material deposited be increased
- when there’s lots of erosion elsewhere on the coast so lots of material available
- when there’s lots of transportation of material into an area
Characteristics of sand beaches
- flat and wide
- sand particles are weak
- long, gently sloped
Characteristics of a shingle beach
- steep and narrow
- shingle particles are large
- steep slope