Physical - Coastal Environments Flashcards
Creation of a wave
Friction with wind (fetch) sets the wave into motion
IN shallow water, friction with the seabed causes the wave to tip forward
Wave eventually breaks (Swash)
Water runs back down the beach under gravity (Backwash)
Constructive waves
Strong Swash, Weak backwash, Long wavelength, Shallow gradient waves, Deposition
Destructive Waves
Weak Swash, Strong Backwash, Tall waves, short wavelength, Beach eroded
Hydraulic Action
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Force from the waves hitting the cliff face, forcing pockets of air into cracks and crevices, causing them to widen
Abrasion
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Waves picking up sediment and hurling them at cliffs, causing them to wear away
Corrosion (solution)
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The dissolving of rocks by sea water
Attrition
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Material carried by waves becomes rounded and smaller over time as it collides with other material
Weathering
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The breakdown of rocks which is caused by freeze-thaw and the growth of salt crystals, by acid rain and the growth of plant roots
Erosion
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The wearing away of rocks by wing and rain
Mass movement
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The removal of the cliff face material under the influence of gravity in the form of rock falls, slumping and landslides
Concordant coastline
Discordant Coastline
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Concordant coastline: the outcrops of rock runs parallel to the coastline
Discordant coastline: the outcrops of rock run perpendicular to the coastline
Formation of headlands and bays (6)
- At a discordant coastline
- Outcrops of rock run perpendicular to the coast
- Soft rock is eroded faster
- Forms Bays
- Hard rock is more resistant and is eroded slower
- Forms headlands
Headland to Stump (6)
- Headland is eroded by hydraulic action, abraision
- Causes a crack to expand into a cave
- Cave expand to other side, forms arch
- Top of the arch collapses under gravity
- Leaves a stack
- Stack is eroded and collapses, leaves stump
Formation of a beach (6)
- Formed by the deposition of material
- Material is eroded from elsewhere along the coastline
- Attrition causes smaller, rounder sediment
- In sheltered bays, shorter fetch
- Weaker waves, constructive
- Causes deposition of sediment
Formation of a spit (4)
- At a change in the direction of a coastline or an estuary
- Material transported by longshore drift is deposited
- Causes a spit to grow
- Salt marsh forms behind the spit, stabilising it
Formation of sand dunes (4)
- Sand from beaches is blown inland by wind
- Forms sand dunes
- Vegetation stabilises dunes
- Ridges of sand dunes form parallel to the coastline
Human Activity: Settlemet
- Coastal lowlands attract people
- Most densely populated area are located on the coast
Human Activity: Development
- Coast offers economic opportunities
- Eg. Land for agriculture, fishing, trade, tourism
- May have negative impact on the coastal environment
Human Activity: Coastline management
- Hard and soft engineering methods to prevent impacts of erosion
Factors affecting distribution of Coral Reefs [5]
- Temperature: Ideal temp is 23-25 C
- Light: Need light for photosynthesis
- Water depth: Need light, shallow water, less than 25m deep
- Salinity: Can only survive in saltwater ph 8 - 8.5
Commonly found between the tropics
Factors affecting the distribution of mangroves
- Found in the intertidal zone
- Between 30* latitude
Value of coral reefs [4]
- Biodiversity
- Protect low lying coasts from storms
- Rich fish stocks
- Appeal to tourists, recreational
Threats to coral reefs [4]
- Pollution of water: lack of sunlight
- Increasing temperatures: Coral Bleeching
- Tourism, human interaction kills them, delicate
- Increased fishing, leads to imbalance
Value of mangroves [4]
- Fish and shelfish
- Mangrove roots create more land
- Protection from storm surges
- Provides timber fuel and building material
