Costal Environments Flashcards
Describe a constructive wave
Strong swash
Weak backwash
Describe a destructive wave
Weak swash
Strong backwash
Explain the erosional processes.
Hydraulic action - air in a rock crack, sea water crashes against it and forces rock to break apart as air has nowhere else to go
Abrasion - rocks rub together and scour the coast
Corrosion - sea water corrodes the rocks and slowly dissolve
Attrition - rocks bash together
Explain longshore drift
Eroded rock is picked up by waves and dragged along the coast.
Moves in direction of wind.
Backwash is at 90 degree angle to swash.
When run out of energy or coastline changes direction, sediment is deposited forming depositional landforms.
What are the three land processes?
Weathering - freeze-thaw, salt crystals, acid rain
Erosion - wind and rain
Mass movement - gravity, slumping and landslides
What is a concordant and discordant coastline?
Concordant - straighter coastline, outcrops run parallel to the sea, eroded to form wave cut notch, if hard rock is on edge, rock crashes down, if soft, rock slumps down
Discordant - rocks outcrop at right angles, eroded to form headlands (by crack, cave, arch etc) and bays - different strengths of rock on the coastline
How are caves, arches, stacks and stumps formed?
Erosion in a headland opens up to a cave
The cave extends back to form an arch
The arch widens and the roof collapses
A stack is left separated for the headland
Further erosion cause a stump
How are spits formed?
- long shore drift occurring along coast
- coastline changes direction
- waves have to drop sediment forming a spit
How are waves created?
By winds as they blow over the surface of the sea
Strength depends on the wind and fetch
What is a tombolo?
Spits that have continued to grow and joined to an island.
What is a cuspate foreland?
Triangular shape accumulations of sand and shingle
Longshore drift has occurred from two directions
What are sand dunes?
Made up of dry sand blown inland by wind
Forms series of ridges
Vegetation helps stabilise them
What factors affect coasts?
Geology
Vegetation
Sea level changes
Human activities
Explain what a submergent coastline is
When sea level rises
Downward river valleys and glacial valleys
Explain what an emergent coastline is
Falling sea level
Raised beaches
What conditions do coral reefs need to grow?
Temperature - 23-25 degrees C Shallow water for more warmth and light - less than 25 metres deep Wave action - oxygenated salt water Exposure to air - too long they die Sediment - clean water No alge - alge can suffocate Fish to inhabit
Where are coral reefs distributed?
Between the Tropic of Cancer and Capricorn
Where are mangroves found?
Within 30 degrees latitude of the equator
Describe what a mangrove is and what it does?
One foot on land one in the sea Live in a changing environment Range in size from shrub to 60m Filtration System keep salt out Make new land
What are the main reasons for coastal conflict?
- all competing for same site
- reclaiming land
- no special protection or conservation areas
- over developed
- no protection plan
What are the threats to coral reefs?
Humans taking bits of coral Pollution Overfishing Coral for building stones Farm run off Sea level change Sea temperature rising
What are the threats to mangroves?
deforestation
land reclamation
herbicides
aquaculture
Give an example of hard and soft engineering?
hard - sea wall, rip rap, rock islands, gabion, break water
soft - beach replenishment, managed retreat, fencing
What are the advantages or disadvantages of engineering?
Hard
adv - quick, effective
dis - can be expensive, unattractive
Soft
adv - cheaper generally
dis - doesn’t last as long, not effective
Why are coasts constantly changing?
Used by humans
Weathered
Eroded
Transported
Explain how headlands retreat to produce new coastal landforms.
Front on: Cliffs & Wave Cut Platforms:
- waves form wave cut notch via abrasion
- overhang becomes too heavy
- collapses (either crashes or slumps) and headland retreats
- draw diagram
Side on: Crack, Cave, Arch, Stack, Stumps:
- sea erodes areas of weaknesses i.e. cracks
- further erosion leads to larger cracks developing into small caves
- further erosion widen caves until two caves erode into back of each other forming an arch
- wave attack at base of arch weakens structure until roof of arch collapses leaving stack
- continued erosion in stack causes collapsing to a stump
- stump then covered by water at high tide.
What is a bar?
Long shore drift has occurred on the outsides of two headlands making its way to the bar inbetween
Waves drop sediment on corners of headlands
Over time so much sediment has dropped just inside the bay region of each headland that two piles of sediment join up to form a bar of sediment across a bay
What is a beach?
- depositional landform
- made up of an accumulation of sand and sediment between high and low tide
- created by constructive waves
- includes berms and storm beaches
How do coasts change with sea level rises?
- rias formed (drowned river valleys)
- fjords formed (drowned glacial valleys)
How do coasts change with sea level drops?
- raised beaches formed (wave cut platform emerges)
- relict cliffs formed (caves, arches, stacks emerge)
What conditions do mangroves need to grow?
- intertidal zones
- tropics
- a mix of salt and fresh water
What conditions do sand dunes need to grow?
- wind
- lots of sand
- vegetation
What conditions do salt marshes need to grow?
- a mix of salt and fresh water
- form behind a spit
- calm water
What is the importance of, threats to and management of sand dunes and salt marshes?
Importance:
- habitat
- recreation
- protection
Threats:
- recreation
- development
Management:
- zone off
- prohibit development
- educate
Why is casual conflict caused by different users of the coast?
- conservationists don’t want any coastal activities
- fishermen want no tourism so they can fish for a living
- tourists want water sports and touristic activities
Give examples of hard and soft engineering.
Hard:
- sea wall
- groynes
- gabion cages
- rip rap
- revetments
Soft:
- cliff stabilisation
- beach replenishment
- zoning
- managed retreat
Why are coasts retreating in one named area and how is it being managed?
Barcelona, Spain
- long shore drift
- increased storms
- human activity
- huge fetch from South East
- beach reolenishment
- groynes
- breakwaters
- rock islands
- rip rap
For an ecosystem you have studied, discuss the threats to the ecosystem and how successfully they are managed.
Sand dunes
- roads / housing / general development
- walking (footpath erosion)
- litter / pollution
- planning laws to restrict development
- rope barriers
- educational signs
- boardwalks, playgrounds
- bins, sign posts
What is deposition?
When accumulated material / sand / shingle / sediment is deposited all at once.
How do headlands and bays form?
- form only on discordant coastlines
- (where soft and hard types of rock all meet the sea)
- soft erodes more easily forming a bay further back
- leaving hard rock in either sides of it as two headlands
What factors affect the distribution of coastal ecosystems?
Coral reefs:
- temperature
- light
- water depth
- salinity
- wave action
Mangroves:
- warm temps (30degrees latitude of equator)
- intertidal zones
What are the threats to sand dunes?
Human activities
Development
Pollution
What are the threats to salt marshes?
Development
Human activities
Reclaimed land
