Evaluate the view that rates of coastal recession are largely controlled by geological factors (20)

What is coastal recession?

The net loss or displacement of land, or the long-term removal of sediment and rocks along the coastline due to the action of waves, currents, tides, wind-driven water, or other impacts of storms

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How igneous does rock type impact rate of coastal recession and stability?

Igneous rock will erode very slowly due to crystalline structure

How does metamorphic rock type impact rate of coastal recession and stability?

Metamorphic rock will erode very slowly due to crystalline structure

Where is an example of limited and slow costal recession due to rock type?

Kettlness, N. Yorkshire

where a headland made from erosive resistant rock forms the end of a bay, removing wave energy going into the bay

How does sedimentary rock type impact the rate of coastal recession and stability?

Erode much faster due to being clastic and therfore having low erosive resistivity

Where is an example of extensive and fast coastal recession due to rock type?

Holderness coastline looses 7-10cm per year due to being mad of low erosive resistant boulder clay and chalk.

Evaluate how rock type impacts the rate of coastal recession and stability?

High errosive resistant rock structures have low rates of recession, whilst low errosive resistant rock types have high rates

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How can mechanical weathering impact rate of coastal recession and stability?

Breaks down rocks due to freeze thaw and salt crystallisation

What rocks are susceptible to mechanical weathering?

any rocks with cracks, joints or high up are vulnerable

How can chemical weathering impact rate of coastal recession and stability?

weakens rock structure through chemical changes

What rocks are susceptible to chemical weathering?

limestone and carbonate

How can biological weathering impact rate of coastal recession and stability?

often speeds up mechanical or chemical weathering through the action of plant roots and animal boring.

What rocks are susceptible to biological weathering?

rock falls off cliffs where there is vegetation on sedimentary rocks

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When will the most erosion from wave processes occur?

When waves are at there largest, as they have enough energy to errode coast

What influences wave size?

wind speed and fetch

What is an example of a low energy coast?

Dunkirk

Why is Dunkirk a low energy coast?

short fetch, calmer conditions, far out and the seabed is shallow

therefore constructive waves and deposition

What is an example of high energy coastlines?

North coast of Scotland

Why is the north coast of Scotland a high energy coast?

longer fetches, storm conditions and the sea bed is deep

therefor destructive waves

Compare recession at constructive and destructive beaches.

Low energy rarely experience recession

High energy constantly receding

How does time of year affect the rate of recession/deposition?

During summer months beaches usually experience higher levels of deposition due to calmer conditions

In winter destructive waves are more frequent so experience higher rates of erosion

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How has human activity increased rates of coastal recession?

By interrupting the operation of the sediment cell

How do sea defences increase rates of coastal recession?

Riffraff prevents LSD, and Sea walls prevent erosion,

starving sediment from other areas allowing for less protection by beaches and greater cliff erosion as a result

Give an example of sea defences increasing rates of coastal recession?

Holderness

Sea defences at Maplton have lead to sedement starvation to the south by reducing LSD. This has lead to increased cliff errosion

How does dredinging impact costal recession?

Same process

Removing sedemnt from the sedemnt cell leading to beach loss

How does beach lose lead to cliff errosion?

beaches that once protected the cliffs from the effects of erosion by absorbing wave energy are removed therefore Cliff erosion will increase

HOWEVER managed retreat allows for...

sediment to be reintroduced with the aim of maintaining beaches and limiting coastal recession elsewhere