2.3 Coasts Flashcards
1
Q
Coasts:
A
Coasts are formed by the sea and wind working together
In 3 key tasks: erosion, transportation and deposition
2
Q
Erosion:
A
- Corrasion: large waves hurl beach material at the cliff
- Corrosion: salts and acids slowly dissolve a cliff
- Attrition: waves cause stones to collide and
disintegrate - Hydraulic action: force of waves compresses air in cliffs
3
Q
Transportation:
A
- Waves approach coast at an angle
- Swash moves up the beach at an angle
- Backwash drains straight back down the beach
- Gradually moving material along beach in zig-zag
motion
4
Q
Deposition
Components of waves:
A
- Swash: when a wave breaks & washes up the beach
- Backwash: when the water drains back into the sea
5
Q
Types of waves:
A
- Constructive
- Destructive
6
Q
Constructive waves:
A
- Low wave height
- Beach gradient is gentle
- Spill forward gently
- Creates a strong swash
- Water drains through beach material
- Backwash is weak
- Deposits material
- Builds up beaches
7
Q
Destructive waves:
A
- High wave height
- Beach gradient is steep
- Plunge forward
- Swash is weak
- Rotation of water causes a strong backwash
- Erodes beaches
8
Q
Cliffs & Wave-cut platforms:
A
- Wave erosion is concentrated at the foot of the cliff
- A wave-cut notch is formed
- Cliff is undercut & collapses
- Repeated collapse causes retreat of the cliff
9
Q
Caves, Arches and Stacks
A
- A band of weaker rock extends through a headland
- Erosion produces caves on both sides of headland
- More erosion produces an arch through the headland
- Eventually the roof is weak & collapses forming a stack
10
Q
Beaches:
A
- In bays, the waves diverge outwards
- The wave energy is dissipated creating a low energy
environment hence deposition to form beaches
10
Q
How are caves, Arches and Stacks formed:
A
- Large crack, opened up by hydraullic exam.
- The cracks grows into a cave by hydraullic action and
abrasion - The cave becomes larger
- The cave breaks through the headland forming a
natural arch. - The arch is eroded and collapse
- This leaves a tall long stack
- The stack is eroded and forms a stump
11
Q
Bays and headlands:
A
- Bays are formed due to softer rock getting eroded
easily - Headlands are usually formed since they are made of
resistant rock and so is eroded more difficultly
12
Q
Spits:
A
- Spits form when the coastline changes direction
- Longshore drift carries material in same direction
- Sand & shingle is built up to form a spit
- End of spit curves due to wave refraction or wind
13
Q
Sand dunes:
A
- Sand dunes form behind wide sandy beaches
- Onshore winds pick up the dry sand from above the
high-water mark & carry it landward by saltation - If they encounter an obstacle the wind loses energy &
deposits sand in the lee of the obstacle - Eventually a dune is formed
- Plants grow on it which stabilizes it & traps more sand
14
Q
Mangrove swamps
A
- Mangrove swamps are trees and shrubs that grow in
saline coastal habitats in the tropics and subtropics - Provide a habitat and protection for many fish & other
sea animals, especially when young - They slow water flow encouraging any sediment to be
deposited, keeping sea water clear - Protect the coast from erosion, storm surges,
hurricanes, and tsunamis - They are a source of food and material
- Conditions required for formation of mangrove
swamps:
