How Do Characterisitc Coastal Landforms Contribute To Coastal Landscapes Flashcards
(18 cards)
Eg of marine erosion
Hydraulic action, abrasion, attrition, solution
Why is the direction and fetch of the wind most sig in affecting marine erosion
The direction can have a direct impact on the transportation, the LSD and movement of material which will help to influence the beach width, beaches r important cuz the bigger the beach, the more energy it can absorb before the waves reach the back shore and cliffs, causing erosion
How is wave type and energy linked to fetch
Fetch= distance which the waves have been able to propagate from and the direction the waves come from.
Wind is the main cause of waves. This will cause friction on the surface and create the wavelets which will join together in the barrels of energy e.g. destructive waves= stronger backwash, moving material back off the beach
How can beach morphology change in the short term
Tides can also have an impact on a daily basis in seasonal terms
More wave energy in autumn and winter months, more erosion.
Spring and summer wil see more high pressure, can generate smaller constructive waves leading to more depositonal features
How can SLR in the long term
RSL
Rising eustatic sea level= change in volume of water due to 1) glacial and interglacial periods, cold conditions in ice age, meant that water is frozen and locked in ice sheets and glaciers, in today’s epoch we r in an interglacial periods (halocene), warmer weather melts ice, more water
2) contemporary changes of CC in advanced greenhouse effect, more extreme weather faster melting of ice sheets in Greenland which can also lead to thermal expansion, warming of ocean using it to expand.
How does lithology of rock affect marine erosion
The hardness and characteristic of rock can influence ME as unconsoidated material r going to be more affected by ME than igneous and metamorphic
LSD (transportation)
The movement of swash and backwash along the beach, depending on the angle of the wave attack will lead to LSD along the shore at the direction of the prevailing wind.
How does spit form
Beaches on drift aligned coasts e.g. Holderness coast, where the prevailing wind and wave direction tends to be from the NE. Because they r drift aligned, there can be much greater rates of LSD although the beaches r there, the beach material is moved rapidly along the CL. This movement of material can be deposited in the more sheltered areas either in the river mouth forming spits where 1 end is washed away by the flow so it doesn’t connect to the other land
Bars
LSD- when prevailing wind forceswaves to approach the beach at an angle, swash carries sediment up the beach, backwash causes water to carry sediment back to the sea due to gravity. This process slowly moves material along the beach
When there is no strong river, bars can form enclosing bays between 2 headlands leaving water behind it, forming a lagoon
Tombolos
LSD
Material is moved along and it joins the mainland to an offshore island w a sandy spit
Cupsate foreland
Where there r 2 main directions of LSD coming down, leading to 2 spits to join up to create a cuspate foreland (depositonal landform), w lots of sand and shingles within it.
Weathering
Breaking down of rock on situ
Mass movement
Material moving down by gravity
Sediment cell
Coasts act as a system with inputs and outputs
How does sediment cell work
Input, can come from eroded material, are transported by transportation and put into sinks where the material is stored e.g. beach
There r limited outputs sometimes this sediment particularly in storm environments can move between different sediment cells e.g. UK has 11 major sediment cells which r often created when there r major headland or changes in directions of the CL.
Dynamic equilibrium
Coastlines by nature try to seek dynamic equilibrium, where sources and inputs r equal to the output
Positive feedback
Accelerate change
E.g. if u put coastal protection in 1 place, it may reduce the sediment flowing to the source lower down the CL, this reduces beach size, more wave energy reaching the coast and cliffs (back shore) more erosion will lead to more coastal protection and so this accelerates change
Negative feedback
Restore equilibrium e.g. w a large storm there’s big erosion of the cliffs and beaches causing sediment to be placed offshore, now as there’s sediment offshore to absorb some of the wave energy meaning that there’s less energy at the beach which can lead to more deposition on the beach forming bigger beach to decrease erosion.
