Coasts Revision

Igneous Rocks

• rock properties- grain structure.
• how to they form- Igneous rocks form when magma cools.
• examples of Igneous rock- Pumice and Granite.
• UK location- the Scottish highlands have spectacular mountains made of old Igneous rocks.

Metamorphic Rocks

• rock properties- layers.
• how do they form- Sedimentary and Igneous rocks under heat o pressure form metamorphic rocks.
• examples of Metamorphic rocks- State and Marble.
• UK location- slate is found in north Wales and is about 400 million years old!

Sedimentary Rock

• rock properties- layers.
• how do they form- loose bits of rock and soil that are piled up and pressed together under lakes or oceans.
• examples of Sedimentary rocks- Sandstone and Limestone.
• UK location- oceans and lakes.

weathering

Freeze-thaw weathering, also known as frost weathering, is caused by water freezing in gaps and cracks in stones and rocks, When the water freezes the ice expands and cracks and crumbles the rock.

 Onion Skin

Rocks heat during the day, causing them to expand. When temperature falls during the night the rocks cool and contract. This expansion and contraction can apply stress to the outer layers of the rock, which, over time, causes the outer layers to peel away or flake off.

Chemical

Chemical weathering is the breaking down of rocks by chemical reactions. It takes place in almost all types of rocks.

Biological

Biological weathering is a type of weathering caused by plants, animals, and microbes.One way in which biological weathering can affect the landscape is, It includes any action taken by a living thing that wears down a material.

EROSION

Hydraulic action- this occurs when the motion of water against a rock surface produces mechanical weathering.

Abrasion-Waves cause the rocks to crash against each other, breaking them down into smaller and rounder pieces.

Solution- this is minerals that are dissolved in the water and carried along in solution.

Attrition-this is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.

What are constructive waves?

Constructive waves are low energy waves that deposit materials on a coast. As the waves approach such as coast, the friction between the waves and the sea bed causes the waves to slow down at some distance from the coast. The waves break gently over a long distance.

What are deconstrictive waves?

Destructive waves are more powerful and cause erosion, whereas constructive waves are less violent and encourage deposition. Destructive waves are formed by strong winds with large fetch areas. These waves have high energy levels that have been built up by travelling long distances and being exposed to strong winds.

Where are they found? Cave,arch, stack, stump are found on a headland,where the rock is exposed to enosional prosesses that eventtualy break through.

caves

They are formed by Hydraulic action and Corrosion,joints,falts and lines of weakness in the rock are eroded. These are widened in the cliff to form a cave.

Arches

Arches are formed when continuous erosion over a long period may lead to back-to-back breaking through a headland forming a arch.

Stacks

They form by erosion at the base and sides and weathering prosesses acting on the roof,the arch becomes bigger and eventualy collapses, forming a single piller (Stack).

Stump

They are formed by hydralric action and abbrasion,the stack collapses leaving a stump which is normaly covered at high tide.

Named examples of headlands in the UK

There are many named examples of Cave,arch,stack,stump (Headlines).....

•  Old Harry Rocks- located in Dorset,
• Durdel Door- located in Dorset.
• Cape Cornwall-located in Cornwall.
• Berry Head- located in Brixham.
• Cape Wrath- located in midland Scotland.
• Tarbat Ness- located in Tarbat peninsula in Easter Ross Scotland.
• Holborn Head- located in the Scottish highlands.
• Ramore Head- located in Ireland.

The process of longshore drift?

Longshore drift is a geological process that consists of the transportation of sediments (clay, silt, sand and shingle) along a coast parallel to the shoreline, which is dependent on oblique incoming wind direction. Oblique incoming wind squeezes water along the coast, and so generates a water current which moves parallel to the coast.

formation 

Material that is transported by the waves along a coastline is eventually deposited forming distinctive deposition features. There are four main deposition features that you need to learn the formation of. These are:

1. Beaches
2. Spits
3. Bars

Beach - The zone of deposited material that extends from the low water line to the limit of storm waves. The beach or shore can be divided in the foreshore and the backshore.

Spit - A depositional landform formed when a finger of sediment extends from the shore out to sea, often at a river mouth. It usually has a curved end because of opposing winds and currents.

Bar - Where a spit grows across a bay, a bay bar can eventually enclose the bay to create a lagoon. Bars can also form offshore due to the action of breaking waves.

I think we should keep them safe to keep animals habitats normal and calm. Without coastlines some animals don't have homes. Also i think we should protect them so coastlines can be seen for many generations to come!  

Where is it? The Holderness cost is in North England has one on the highest rates of costal erosion in Europe. It extends 61km from Flamborough in the North, to Spurn Point in the South.

Reasons for high rates of erosion.

The Holderness Coast is one of Europe's fastest eroding coastlines. The average rate of erosion is around 2 metres per year! The reasons are because the cliffs are made from soft bolder clay witch erodes quickly due to the waves crashing ageist them. The prevailing  winds mean that the eroded debris  is moved south along the coast by longshore drift, instead of staying in the place it came from. This exposes the cliff to further erosion.

 How is the coastline being managed?

The coastline is being managed by hard engineering,rock armour is placed along the base of the cliff to help absorbed the power of the waves,two rock groynes trap sand and create a beach to absorbed the power of the waves,the government chooses beaches the protect and leaves the other beaches to erode naturally and local and regional authorities are setting up an integrated costal management programmes for the whole Holderness coastline and the Humber Estuary.

Mapleton-450m of coastline around has been protected at a cost of £2million pounds. They used over 61,000 tonnes of rock.

 Bridlington-There is a 4.7m long sea wall to protect the sea front and a wide beach which is encouraged by wooden groynes.

 Hornsea- They have a sea wall and some groynes.Gabions help protect the local caravan park.

 Withersea-All are protected by the government, due to the amount of people living there. They are protected by a sea wall, groynes and rock armour.

 Kilnsea-Coastal defences are being threatened by erosion an possibly within 5 years, there is no plans to replace them which would leave a pretty village at the destruction of the sea and its villagers without home

 How is the coast line being managed further south - In recent years we as a country have seen changes in the approach to managing coastal change in England and Wales. The cost and environmental impact of building defences against erosion and tidal flooding mean that our government can’t afford to defend everywhere. This will mean that controversially communities will see a change in how their coastline is managed. We know have Shoreline Management Plans in place which means that some areas will be managed and some coastlines left to erode naturally.We now use a mixture of hard and soft defences, Hard defences include embankments, boulders (rock armour), sea walls and rock filled baskets (gabions),Beaches, sand dunes and saltmarshes

What is a Stormsurge?

High rainfall might cauze high river discrarge leaveles near the mouth of the river with high tides or stormsurges and this can cauze coastal areas to flood,

Dawlish case study

Dawlish is affected by stormsurge,some of the impacts of the storm include homes and the railway near the sea were damaged and destroyed. A large section (300m) of road and land collapsed into the sea (due to the weather). this left the railway hanging in the air (15ft). No trains could be opparated during this time. Sea walls didn't hold and collapsed into the sea, all power and electricety was damaged. In total the damage costed Dawlish £35 million to repair!