basics Flashcards
what type of system is the coastal system?
open
why is the coastal system an open system?
it interacts with other systems (e.g. rivers and climate systems)
how does the climatic system interact with coast?
- wind erodes (creates LSD)
- storms erode coastline
- sea level change
dynamic equilibrium
inputs are equal to outputs
what is the dynamic equilibrium affected by?
- supply of sand
- energy of waves
- location of shoreline
landforms
individual features which are created by coastal processes
landscapes
- the entire area of sea, coastline and immediate land behind the sea front
- within the landscape are characteristic landforms
how are waves formed?
- wind causes friction with water and transmits energy
- creates a wave crest
- wave travels in circular motion
- as shoreline inteferes with wave it causes a more horizontal wave movement and the wave breaks
which area of the UK is subject to the most powerful waves? why?
- south west coastline
- strong prevailing winds from that direction
- fetch of 3600km
constructive landscapes contain what features?
- spits
- bars
- tombolos
- beaches
destructive landsapes contain what features?
- arches
- stacks
- wave cut platforms
- caves
neap tides
- when are they formed?
- characteristics?
- when the sun and moon create right angle
- low tidal range
- high low tides
- low high tides
spring tides
- when are they formed?
- characteristics?
- sun and moon in line with each other
- high tidal range
- high high tides
- low low tides
sources of sediment within the coastal system?
- fluvial sediment from rivers
- cliff erosion
- offshore sediment transported by waves/tides
- wind transports sand (sand dunes)
what is ‘beach morphology’
the shape of the coast/beach
sweep zone
area between high and low tide
examples of stores within coastal system
- beach
- spit
- bar
- sand dunes
examples of transfers/flows within coastal system
- erosion
- LSD
- evaporation
- mass movement
examples of inputs within coastal system
- wind
- precipitation
- fluvial sediment
examples of outputs within coastal system
- ocean currents
- headlands
- bays
- riptides
- wave cut platforms
example of feedback within coastal system
mass movement reduces cliff foot erosion
atmospheric factors influencing coastline
- solar energy
- temperature
- winds
- precipitation
- climate change
terrestrial factors influencing coastline
- tectonics
- glaciations
- supply of sediment
- sub-ariel processes
- fluvial processes
human factors influencing coastline
- tourism/recreation
- pollution
- industry and residential development
- sea defences
- conservation
positive feedback of weathering
when the rate of debris removal exceeds the rate of weathering/mass movement, the weathering may increase
negative feedback of weathering
- if debris removal is slow, it will lead to a build up of debris
- this reduces exposure of cliff face to elements so weathering slows and mass movement decreases
factors that influence erosion
- wave type
- rock type and rock angle
- coastal defences
- high or low energy coastline
- weather
- material
- sub ariel processes
deposition in high energy coasts
- small particles easily transported
- larger/heavier material is deposited which forms shingle beaches
deposition in low energy coasts
- even smallest material is deposited forming mudflats and salt marshes
concordant coastlines
- rocks on these coastlines run parallel to the sea
discordant coastlines
- rocks on these coastlines run perpendicular to the sea
how does a wave cut platform develop?
- waves breaking at cliff-foot produce wave-cut-notch
- undercutting is result of abrasion etc
- as cliff is undercut, rock above collapses so the cliff gradually retreats
- sloppy rocky platform is left
what effect do wave cut platforms have on erosion?
- waves have a larger distance to travel in shallow waters so will break earlier
- erosion of cliff face should decrease
strand line
strands of material (e.g. seaweed) on beach that gets deposited and shows high tide line
characteristics of high energy coastline
- erosion exceeds deposition
- rocky coastline
- contains cliffs, headlands
characteristics of low energy coastline
- sheltered areas
- less powerful waves
- deposition exceeds erosion
- sandy / estuarine
- beaches and spits
formation of a spit
-
what is a spit?
a long narrow piece of land made up of sand/shingle joined to the mainland which protrudes out to sea or across a river estuary
how is a spit formed?
- LSD will move material along a coastline in direction of prevailing winds
- as the coastline changes direction, waves lose energy and deposit material
- this material builds upwards and outwards
- wave refraction and second dominant wind cause the material to move away causing a curved end
the area behind a spit turns into a…?
why?
- salt marsh
- low energy waves enter area and deposit material
- this material builds up and vegetation begins to grow
simple vs compound spits
simple - no hooks or barbs
compound - do have hooks and barbs
what is a tombolo?
a narrow strip of sediment going the mainland and an island
how is a tombolo formed?
- LSD occurs and moves sediment outwards from mainland
- the island stops the sediment from extending further and joins the island to mainland
what are sand dunes?
accumulations of sand blown into mounds by the wind
how are sand dunes formed?
- sand accumulates on the beach from LSD
- at low tide the sand dries out allowing the prevailing winds to move the sand up the beach
- debris such as driftwood traps sand and dune starts
- lyme grass grows to stabilise dunes
- need large inter tidal zones for sand to be dry
stages of dunes
- embryo dune
- fore dune
- yellow dune
- grey dune
- dune slack
- mature dune
swash aligned beaches
- form in low energy environments (bays)
- no LSD
- parallel waves
- sediment moves forward and backward
drift aligned beaches
- form where waves approach coast at an angle
- LSD occurs
- leads to tombolos, spits, bars
- material eroded quickly
beaches
- where and why do they form?
- low energy coastline
- in littoral zone between low and high tide
- constructive waves deposit material
- sediment origin: cliff/dune erosion, river sediment
beach ridges and runnels
ridges: furthest deposited material at each high tide
runnels: separate pools of standing water at low tide/ perpendicular channels through which theres backwash
required conditions for mudflat formation
- sheltered areas where deposition occur
- where salt and freshwater meet
- where there are no strong tides or currents
pioneer species?
flocculation?
halophytes?
pioneer species: plants tolerant to salt(e.g.sea blite)
flocculation: mud/material is dropped out of the water close to the hight tide line
halophytes : plants that can live in saltwater environments
what is a salt marsh?
area of coastal grassland that is regularly flooded by seawater
