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 What are the pressured that this coastline is                                facing?   

The Needles

The Needles is a row of three distinctive stacks of chalk that rise about 30m out of the sea off the western extremity of the Isle of Wight, United Kingdom, close to Alum Bay, they have been created through erosion. At the moment, The Needles is at point 6 but in the end, they will just form a stump to complete erosion where there is nothing left in that particular spot.

There are 2 types of waves constructive and destructive, with a constructive wave, the swash is stronger than the backwash. With a destructive wave, the backwash is stronger than the swash. For the Needles the waves are obviously destructive as there is a large fetch which creates larger waves, which also means they have more energy to break down the cliffs. Destructive waves can erode the coast line (the Needles) in 4 different ways:

  • Hydraulic action is the force of water hitting the cliff and squeezing air into the cracks. The trapped air is compressed which weakens the cliff and causes erosion, basting the rock apart.

  • Abrasion/ Corrasion is when The force of bits of rock and sand are carried by the waves are thrown into the cliff

 

  • Attrition / Corrosion is the process of rocks and pebbles hitting each other and they break into smaller rocks.

  • Solution is when a chemical reaction (acids in the sea) react with the sea water and minerals dissolve some types of rock such as chalk or limestone. Lots of the cliffs in the Isle of Wight are made from chalk this could easily effect most of the Isle of Wight.

 

  Rank for the Needles:

  1. Hydraulic action – There is so much force coming from the waves as there is such a large fetch and since it is so small weakening the rock would not take a large length of time.

  2. Solution - Lots of the cliffs in the Isle of Wight are made from chalk this could easily effect most of the Isle of Wight including the Needles.

  3. Abrasion / Corrasion – since it is in the middle of the sea is harder for large rock to travel such a distance but the strength of the weaves could hit the rock against the Needles hard.

  4. Attrition / Corrosion – They would hit the coast line however it would take a long time to create a lot of damage.

 Military Road 

This road is nearest the bay of Brighstone however it goes all around the Isle of Wight. Brighstone bay is a bay on the south west coast of Brighstone. It is south west of the village of Brighstone and to the faces south west towards the, its shoreline is 7 km in length and is gently curving from erosion. Like most of the coast along the South-West of the Island, Brighstone Bay is suffering from. The sea bed is a mixture of mud, sand and shells and the cliffs are made from chalk.

The yellow line going across the island is military road.

This is a picture of the fast eroding Brighstone Bay. Weathering is one aspect that could affect the cliffs there are 3 types biological, physical and chemical, also erosion. Weathering is breaking down of rocks and minerals by physical and chemical processes then rocks are moved by erosion. Physical weathering is caused by animals or plants. An example is water voles they nest in chamber in the winter. This creates cracks in the rock where freeze thaw weathering (congelifraction) a take effect. As it rains or the waves crash against the cliffs in high tide water gets into the cracks and freezes. Water expands as it freezes leaving the cracks to get wider ( physical weathering) and wider letting erosion begin.

The most effective to least:

  1. Biological weathering- this could create it holes which would lead to cracks as this is a country side area this is likely.

  2. Physical – once the cracks are made from biological weathering, congelifraction can affect it, making pot holes

  3. Chemical – this would affect a cliff more than a road I believe as it would year to affect it drastically.

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