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:
15
Q
Coral Reef:
A
- Coral reefs support a great diversity of life
- Built from the limestone remains of coral skeletons &
coralline algae
16
Q
Conditions requried for coral reefs:
A
- Warm water/seas; temperatures above 20°C
- Shallow water; not more than 60 meters deep
- Water free from sediment/clear/availability of light
- Plentiful supply of oxygen in water/unpolluted
- Plentiful supply of plankton
- Lack of strong current
17
Q
Types of croal reef:
A
Fringing reef
Barrier reef
Coral Atoll
18
Q
Fringing reef
A
Coral reefs grow in the shallow water of the coast in
tropical areas
19
Q
Barrier reef
A
- Due to plate tectonics island starts to sink
- Reef grows to keep up with the sinking, but a lagoon
develops between reef & land
20
Q
Carol Atoll
A
- These form around islands that are sinking.
- Coral growth keeps up with this & island keeps sinking
- Eventually island sinks below sea level forming a ring
of coral with a lagoon in the centre.
21
Q
Coastal oppurtunities:
A
- Tourism
- Sport
- Fishing
- Oil and Gas
- Housing
- Industry
- Transport
22
Q
Tourism and Sport:
A
- Tourism: Resorts along coasts; tourists enjoy using
coast.
e.g. swimming and sunbathing - Sport: Many sports use coasts e.g. sailing, surfing,
diving
23
Q
Fishing and Oil and Gas:
A
- Fishing: Many people make their living from catching &
selling fish on coasts - Oil & Gas: Reserves are found under oceans near
coasts
24
Housing, Industry, Transport:
- Housing: Many people live along coasts because of its
beauty and relaxing lifestyle
- Industry: Many industries locate near coasts for easy of
trade
- Transport: Many ports are found in coastal areas &
help trading 7 travelling between countries
25
Coastal Hazards:
- Sea level rises
- Pollution
- Overfishing
- Erosion
- Tropical Storms
26
Sea level rising:
Caused by global warming, low lying countries become vulnerable to flooding
27
Pollution:
Sewage discharge, oil spills, litter thrown into the sea can harm coastal ecosystems and environment
28
Overfishing:
Many fish stocks around the world are being over fished to dangerous levels
29
Erosion:
Many coastlines are being eroded by stronger
storms & raising seal levels
30
Tropical Storms:
Frequency of storms & magnitude increase causing floods, storm surges & wind damage
30
Tropical Storms:
Frequency of storms & magnitude increase causing floods, storm surges & wind damage
