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 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

Which mechanical processes are shown in the photographs?                                                             

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)

Which chemical processes are shown in the photographs?

Biological weathering

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

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

Wave terminology

Constructive waves

Destructive waves

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

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

Remember to link landform description to processes 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

Blowholes and cliff slumping video

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

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

Tombolo Video - tombolo

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

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,

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

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

Land allowed to flood and forms salt marshes that absorb wave energy 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