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Coastal Environments

Coastal Environments. Mechanical Weathering. Rock crystals expand and contract very common as sea has high salt content Water expands 9% when it freezes to form ice less common as sea keeps coast mild As crystals grow they exert pressure Weight is taken off the rock Surface layer flakes off

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Coastal Environments

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  1. Coastal Environments

  2. Mechanical Weathering • Rock crystals expand and contract very common as sea has high salt content • Water expands 9% when it freezes to form ice less common as sea keeps coast mild • As crystals grow they exert pressure • Weight is taken off the rock • Surface layer flakes off • Expands when wet and contracts when dry, very common in inter tidal areas • Jointed rock • Freeze thaw • Salt Crystal growth • Exfoliation • Wet/dry • Granular disintegration • Block disintegration • Pressure release Match the starter with the correct ending

  3. Which mechanical processes are shown in the photographs?

  4. Chemical weathering • Oxidation - speeds up in moist coastal areas • Carbonation - limestones dissolve in carbonic acid • Hydrolysis - this affects rocks with feldspar minerals • Hydration - when minerals absorb water, expand and change • Solution - some rocks dissolve in water • Acids - acid rain from pollution ( coastal power stations)

  5. Which chemical processes are shown in the photographs?

  6. Biological weathering

  7. Mass Movement Remember….. The processes that shape a river environment are also affected by slope processes as well as weathering processes. Mass movement is…. The movement of material under the force of gravity. It tends to reduce the slope angle, It is classified on speed and water content Slow ~ soil creep and rain splash Fast ~ flows (wet), slides and slumps (dry) Very fast~ falls, avalanches

  8. Factors which control type and rate of movement~ • Climate • Rock type • Rock structure • Relief • Vegetation • Rates of weathering • Aspect • Shock from something to trigger it eg storm • Human activity

  9. Wave terminology

  10. Constructive waves

  11. Destructive waves

  12. Wave factors Waves control ENERGY and MOVEMENT • Wave shape • Wave size • Fetch • Roughness • Depth and gradient • Load • Tides • Storm surges

  13. EROSION Abrasion~load wearing away cliff Hydraulic action~ sheer force and weight of falling water; especially in cracks ( air pressure) Attrition~ load collides and grinds away (results in sand) Solution~ removal of chemical ions Factors controlling rate of erosion ~ marine factors and coastal factors p15 revision book http://gatm.org.uk/geographyatthemovies/coasts.html

  14. Landforms of erosion Remember there are large scale and small scale landforms and you have studied these using named areas. video video 2 Remember to link landform description to processes

  15. Blowholes and cliff slumping video

  16. Transportation processes~ Traction~ rolled along the bed Saltation~ bouncing along the bed Solution~ dissolved in the water Suspension~ held in the water Flotation ~ on the surface Gatm – lsd video 4th one down Tester – GATM Bond 20th down Deposition Rate of deposition is determined by energy loss and the weight of the load. A shallow gradient, wider beach, calmer climate and meeting a river are examples. Marine deposits include:- Bed load, Suspension, Solution

  17. Depositional Landforms Video – spit formation Remember for depostion to take place the following factors are important:~ • Plentiful supply of sediment • Longshore drift to transport sediment • An indented coastline – coastline changes direction • Energy levels drop –slow down for example at a river mouth • Bioconstruction – plants to help stabilize the sediment

  18. Tombolo Video - tombolo

  19. Coastal Protection • Physical reasons for protection:~ • Climate – global warming • Relief – low-lying areas • Aspect – open to large wave fetch • Depth of water • Drainage – deltas – flooding threats • Vegetation • Ecosystem • Geology

  20. Human reasons for coastal protection:~ • Settlement – Tenby – lots of expensive properties • Source of raw materials – Hallsands – sands and gravels • Industrial needs – • Transport – Mappleton on the Holderness coast • Ports • Fishing • Military ranges – MOD in Castlemartin Pembrokeshire • Tourism & Recreation – Tenby Pembrokeshire • Cultural and historic sites Coastal management and defence - gatm Case studies:- Tenby, Holderness, Hallsands, Abbotts Hall Farm,

  21. Hard Engineering Protection Schemes Groynes and beach renourishment – gatm Identify the scheme describe how it works

  22. Soft Engineering Protection Schemes • Which shows:~ • Replenishment • Beach re-profiling • Fencing – to trap blown sand • Planting vegetation – like marram

  23. Land allowed to flood and forms salt marshes that absorb wave energy. Managed retreat is cheap and natural but needs and area with little or no population. Managed Retreat

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