Erosion Processes (CHASA)
- Fragments of rock are picked up and hurled at the cliff by the sea.
- The rocks scrape and gouge the cliff face.
- The power of the waves as they smash into the cliff face.
- Trapped air is blasted into cracks causing the rock to break apart.
- Rock fragments carried in the sea knock against each other in the water,
- The rocks become smaller and rounder.
Erosion Processes (CHASA)
- Some rocks can be dissolved by seawater.
- The main rocks that do this are, limestone and chalk.
- Limestone and chalk form many cliffs in the UK
- The sandpaper effect.
- Pebbles grind over a rocky platform.
- Creating a smooth platform.
Types of Weathering
- This is where rocks are broken down without any change in the chemical nature of the rock.
- The rocks are 'torn' apart by physical force, rather than by a chemical breakdown.
- E.g. Energy form the earth's crust or freezing.
- This is caused by living organisms.
- E.g. Digging animals, microscopic plants, algae and Fungi.
- Takes place in almost all rock types.
- Reactions break the bond holding rocks together and they fall apart.
- Common where there is water
- E.g. Oxidation, Carbonation or Hydrolysis
- The process of moving sediment down the beach
- Prevailing winds mean the Swash carries sediment up the beach.
- The Backwash carries the sediment back down the beach.
- The waves are at an angle when they approach the beach.
- It doesn't happen at all beaches because most waves come straight on.
Hard and Soft Engineering
- Artifical structures are used to control natural processes.
- E.g. Sea Walls, Rock Armour or Groynes
- A sustainable approach, which uses natural techniques, is used to control natural processes.
- E.g. Beach nourishment, Dune regeneration, Mananged Retreat
Impacts of Coastal Erosion
- A wave-cut notch occurs because of erosion then the cliff becomes unstable and collapses.
Impacts Of Coastal Erosion
- Loss of houses
- Loss of habitat for wildlife
- Job losses
- No house insurance
- Loss of tourism and money
Salt Marsh Case Study - Keyhaven Marshes, South Co
- The beach is retreating up to 6m per year.
- The marsh is eroding which exposes the beach.
- More tourism is causing pollution and damage to the Marshes.
- Sea levels are rising and the low sea wall is under threat.
- The Ringed Plover feeds and nests on the salt marsh.
- The Wold Spider clings to Cordgrass waiting for food.
- The Sea Lavender attracts Wildlife and is pretty.
- Rock Armour and beach Nourishment was introduced in 1996, and the spit has not been breached.
- The marsh is now a SSSI so access is limited and the area is being watched.
Formation of a Spit
- Longshore Drift transports sediment down the coast.
- When the coast changes direction (e.g. a headland) the sediment starts to build out to sea.
- This continues until a sand barrier has bulit away from the coast.
- If the prevailing wind changes direction then the spit can get a curved end.
- A spit can turn into a bar.
Headlands and Bays
Headland - resistant sections sticking out from the coast. They are more vulnerable to powerful waves creating a wave-cut notch.
Bays - weaker sections erode quicker. These are sheltered, and less powerful waves build a sandy beach.
Caves, Arches, Stacks and Stumps
Caves - a soft part of a rock cracks and gets eroded by Hydraulic power. This carried on until the cave gets bigger, but doesn't go all the wat through.
Arches - an arch is where a cave has been eroded all the way through on a headland.
Stacks - the top of an arch has fallen down after years of erosion as it can't be supported any more.
Stumps - a stack has been eroded so much that in shrinks in size becoming a Stump.