Coastal Weathering Mechanical weathering is breaking down rock

Coastal Weathering Mechanical weathering is breaking down rock without changing its chemical composition. Main type at the coast is freeze-thaw weathering. Chemical weathering breaks down rock and changes its chemical composition so rainwater is a weak acid that dissolves rocks. Mass Movement The shifting of rocks and loose material down a slope like a cliff. It happens when the material is full of water. Slides- material shifts in a straight line. Slumps- Material shifts with a rotation. Rockfalls - material breaks up and falls down a slope. Erosion Hydraulic Action- power of the waves forces into cracks causing the rock to break apart. Solution-dissolves. Attrition-rocks bash together become smaller. Abrasion-rocks rub against the cliffs. Corrasion-rocks are thrown at the cliffs Landforms from erosion Waves cut platformserosion at the base of cliff causes a wave-cut notch. Nothing supports the cliff above and collapses causing cliff retreat. Headlands and bays- soft and hard rock next to each other. Soft rock erodes into a U shaped bay. Headlands stick out into the sea. Stacks- Headland eroded. Crack becomes a cave, then arch. Arch roof collapses and then a stack is formed. Durdle Door in Dorset-Arch Old Harry Dorset - Stack Transportation and deposition Traction-rolls along bed. Saltation- bounces Suspension-tiny particles carried. Solution- dissolves Sand Beaches are flat and wide and made from deposition. Shingle beaches are steep and narrow. Spits- form at a bend in the coastline. Longshore drift moves the sand deposits it. Winds make it curve at the end. Salt marsh forms behind the spit. Bars- When a spit joins 2 headlands together. Behind is a lagoon. Sand dune- Longshore drift moves sand up the beach. Obstacles decrease wind speed and sand is deposited and plants will start to grow. Plants stabilise the sand forms embryo dunes. Overtime the oldest dunes migrate inland. Waves Constructive waves- build up the beach (deposition). Strong swash and weak backwash. Small waves. Destructive waves- destroy beaches. (erodes) Weak swash and strong back wash. High waves, Coastal Management Hard Engineering at Lyme Regis- needed due to increase in erosion over last 100 year. 4 phases put in place to manage the coast. New sea wall and rock armour used as part of the protection near The Cobb. Phase 3 did not happen and was left to natural processes due to the land being of low value. Soft Engineering - Beach nourishmentmakes the beach steeper and wider. This was also used. Pos-increase tourism. Neg-some didn’t like the sea wall. Other soft- Dune regeneration- restores sand dunes. Managed retreat- allows the area to flood. River landscapes Erosion Hydraulic Action- power of the waves forces into cracks causing the rock to break apart. Solution-dissolves. Attrition-rocks bash together become smaller. Abrasion-rocks rub against the beds and banks. Transportation Traction-rolls along bed. Saltation- bounces Suspension-tiny particles carried. Solution- dissolves Upper course- v-shaped, steep sides and shallow channel. Mainly vertical erosion Middle course- gently sloping, wider and deeper channel. Lateral erosion Lower course- almost flat, very wide and deep channel Lateral erosion. River erosion landforms. Interlocking spurs are found in V-shaped valleys they stick out. Waterfalls- hard rock sits on soft rock hydraulic action erodes the soft rock leaving an overhang. The overhang will collapse into the plunge pool making the waterfall retreat leaving a steep sided gorge. The plunge pool is found at the base of the waterfall and becomes deeper through abrasion. High Force in England is an example. River deposition landforms. Floodplains is wide and flat found in the middle and lower course. Made of alluvium deposited in floods- fertile soil. Levee- is a raised bank next to a river. The coarser material is deposited first. Estuaries- in the UK most river mouths form one. In rising tide the velocity falls and sediment is deposited. Overtime mudflats are made and develop into saltmarshes. Flooding-physical- precipitation-too much rain. Geological- impermeable rock. Steep slopes –travels fast. Human- urbanisation-concrete. Deforestation-less interception. Hydrographs show if a river will flood. River erosion and deposition landforms. Meanders-bends. Change shape through lateral erosion. Thalweg is the fast flow. Pool is a deep section near the outside of the bend. Riffles are sections with deposited sediment. Ox-bow lakes-the meander will migrate (travel) and start to erode towards another. They will meet causing the loop to be cut off, this is the ox-bow. Managing river floods Hard engineering- Dams and reservoirs. Channel straightening and building embankments- these take lots of building and costs a lot. Soft Engineering- Flood zoning- not building on certain land. River restoration puts it back to its normal course. Flood warnings. Banbury- in the Cotswolds. 1998 large flood. £ 12 million damage. River Cherwell. 2012 new flood defence built- 2. 9 km embankment to create flood storage. Storage is on floodplain. There is a flow control structure and so excess fills up a reservoir. Benefits- reduced depression, new Biodiversity Action Plan habitat. Costs£ 18. 5 in total for whole project

Coastal Weathering Mechanical weathering is breaking down rock without changing its chemical composition. Main type at the coast is freeze-thaw weathering. Chemical weathering breaks down rock, rainwater is a weak acid that dissolves rocks. Mass Movement The shifting of rocks and loose material down a slope like a cliff. It happens when the material is full of water. Slides- material shifts in a straight line. Slumps- Material shifts with a rotation. Rockfalls - material breaks up and falls down a slope. Erosion Hydraulic Action- power of the waves forces into cracks causing the rock to break apart. Solution-dissolves. Attrition-rocks bash together become smaller. Abrasion-rocks rub against the cliffs. Corrasion-rocks are thrown at the cliffs Landforms from erosion Waves cut platformserosion at the base of cliff causes a wave-cut notch. Nothing supports the cliff above and collapses causing cliff to move back. Headlands and bays- soft and hard rock next to each other. Soft rock erodes into a U shaped bay. Headlands stick out into the sea. Stacks- Headland eroded. Crack becomes a cave, then arch. Arch roof collapses and then a stack is formed. Durdle Door in Dorset-Arch Old Harry Dorset - Stack Transportation and deposition Traction-rolls along bed. Saltation- bounces Suspension-tiny particles carried. Solution- dissolves Sand Beaches are flat and wide and made from deposition. Shingle beaches are steep and narrow. Spits- form at a bend in the coastline. Longshore drift moves the sand drops it. Winds make it curve at the end. Salt marsh forms behind the spit. Bars- When a spit joins 2 headlands together. Behind is a lagoon. Sand dune- Longshore drift moves sand up the beach. Obstacles decrease wind speed and sand is deposited and plants will start to grow. Plants hold the sand in place. Waves Constructive waves- build up the beach (deposition). Strong swash and weak backwash. Small waves. Destructive waves- destroy beaches. (erodes) Weak swash and strong back wash. High waves, Coastal Management Hard Engineering at Lyme Regis- needed due to increase in erosion over last 100 year. 4 phases put in place to manage the coast. New sea wall and rock armour used as part of the protection near The Cobb. Phase 3 did not happen and was left to natural processes due to the land being of low value. Soft Engineering - Beach nourishmentmakes the beach steeper and wider. This was also used. Pos-increase tourism. Neg-some didn’t like the sea wall. Other soft- Dune regeneration- restores sand dunes. Managed retreat- allows the area to flood. River landscapes Erosion Hydraulic Action- power of the waves forces into cracks causing the rock to break apart. Solution-dissolves. Attrition-rocks bash together become smaller. Abrasion-rocks rub against the beds and banks. Transportation Traction-rolls along bed. Saltation- bounces Suspension-tiny particles carried. Solution- dissolves Upper course- v-shaped, steep sides and shallow channel. Mainly vertical erosion Middle course- gently sloping, wider and deeper channel. Lateral erosion Lower course- almost flat, very wide and deep channel Lateral erosion. River erosion landforms. Interlocking spurs are found in V-shaped valleys they stick out. Waterfalls- hard rock sits on soft rock hydraulic action erodes the soft rock leaving an overhang. The overhang will collapse into the plunge pool making the waterfall retreat leaving a steep sided gorge. The plunge pool is found at the base of the waterfall and becomes deeper through abrasion. High Force in England is an example. River deposition landforms. Floodplains is wide and flat found in the middle and lower course. Made of alluvium deposited in floods- fertile soil. Levee- is a raised bank next to a river. The heavier material is deposited (dropped) first. Estuaries- in the UK most river mouths form one. In rising tide the velocity falls and sediment is deposited making a mudflat. Flooding-physical- precipitation-too much rain. Rock type- impermeable rock. Steep slopes –travels fast. Human- urbanisation-concrete. Deforestation-less interception. Hydrographs show if a river will flood. River erosion and deposition landforms. Meanders-bends. Change shape through lateral erosion. Thalweg is the fast flow. Pool is a deep section near the outside of the bend. Riffles are sections with deposited sediment. Ox-bow lakes-the meander will migrate (travel) and start to erode towards another. They will meet causing the loop to be cut off, this is the ox-bow. Managing river floods Hard engineering- Dams and reservoirs. Channel straightening and building embankments- these take lots of building and costs a lot. Soft Engineering- Flood zoning- not building on certain land. River restoration puts it back to its normal course. Flood warnings. Banbury- in the Cotswolds. 1998 large flood. £ 12 million damage. River Cherwell. 2012 new flood defence built- 2. 9 km embankment to create flood storage. Storage is on floodplain. There is a flow control structure and so excess fills up a reservoir. Benefits- reduced depression, new Biodiversity Action Plan habitat. Costs£ 18. 5 in total for whole project