7. Coasts Flashcards
abraison
whenrocks are thrown against the side of the river
arch
a coastal feature created by the erosion of back-to back caves
attrition
when rocks bash against eachother and break down, eventually getting really small
backwash
the waves that are reatreating
bay
an area of sea between two headlands
beach
material which the sea deposits on the coast
corrosion/solution
a chemical process involving the dissolving away of sediment
erosion
the wearing away of material
estuary
the final section of a river, where freshwater and saltwater mix
headland
a promontory of resistant rock which juts out in the sea
hydraulic action
when the water bashes against the side of a river and rocks break off
longshore drift
the movement of sand and pebbles along a beach by wave action
saltation
the transport of sediment hopping on the sea floor
spit
an extended beach which grows by deposition across a bay or river mouth
suspension
a method of transporting very fine (small) sediment in a river
swash
wave going towards the coast
traction
the transport of boulders in a rolling motion in water
weathering
the breaking down of a material
describe how headlands and bays are made
headlands are made of hard rock & bays are made of soft rock
*as the soft rock is weaker, then it erodes more easily and then a bay is formed
describe wave cut platforms
*the area between the high tide and the low tide is the wave cut notch
*due to hydraulic action and abrasion, it creates a dent in the cliff and that is the wave-cut platform
describe how CASS (caves, arches, stacks and stumps) are made
It starts with a fault in the cliff.
- Waves attack the fault by hydraulic action and abrasion.
- This makes a cave. A blowhole may appear on top of the cliff due to upward erosion by waves hitting the roof of the cave.
- Hydraulic action and abrasion widen and deepen the cave and eventually cut through the cliff to form an arch.
- Due to a lack of support, the area above the arch collapses, creating a stack.
- Weathering and erosion turn the stack into a stump.
describe longshore drift
The swash moves up the beach at the angle of the prevailing wind and then down at a 90° angle until it reaches a barrier (if there is one)
*This is how rocks and pebbles move up a beach.
describe the features of a constructive wave
*They have a large swash meaning they carry material far up the beach.
*Frequency of 6-9 waves per minute.
*Smaller and shorter waves
*Weak backwash that carries little sediment
describe the features of a destructive wave
*Created in storm conditions
*Have a strong backwash which erodes the coast
*Wave has travelled over a long fetch (how far it has travelled) - big
*Frequency of 11-15 per minute
*Larger and bigger waves
*Weak swash that moves little sediment up the beach
describe how a spit is created
- Longshore Drift (LSD) moves material up the coastline.
- The coastline suddenly changes direction and deposition continues into shallow, sheltered areas and material continues to be deposited.
- A spit is formed from this deposited material.
- Over time, the spit turns into a curve due to the wind.
(5.) Sometimes a salt marsh will appear on the sheltered side of the spit.
give examples of soft engineering (min 2)
*Beach nourishment: Sand is added to a beach to flatten it out. It is cheap but does not last for very long.
*Managed Retreat: lets the areas of low value get flooded and protects the important areas further down the coast.
*Cliff Stabilisation: Cliffs are covered in vegetation planted there to help make them more stable and erosion resistant.
*Do nothing: The cheapest and most eco-friendly way. Lets nature erode the coast how it is meant to.
give examples of hard engineering (min 2)
*Sea Wall: Put at the base of a cliff to reflect the waves energy. Very expensive - £10,000 per km. Ugly but effective at protecting areas from flooding.
*Gabions: Cages of wire with rocks to absorb the energy from the waves. Effective and cheap, but ugly.
*Groynes: Wood or rock structures placed at right angles to the beach to trap sediment. Helps build up the beach and protect the cliff from erosion. results in areas further down the coast being starved of beach material meaning more erosion.
*Rip-Rap (rock armour): Large rocks put at the bottom of the cliff to absorb the wave’s energy. Effective at dispersing the waves energy and are cheap, but are ugly.
what is CASS
Cave
Arch
Stack
Stump
