coastal environments. mechanical weathering freeze thaw salt crystal growth exfoliation wet/dry...
TRANSCRIPT
Mechanical Weathering
•Freeze thaw
•Salt Crystal growth
•Exfoliation
•Wet/dry
•Granular disintegration
•Block disintegration
•Pressure release
•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
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?
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 factors
Waves control ENERGY and MOVEMENT
•Wave shape
•Wave size
•Fetch
•Roughness
•Depth and gradient
•Load
•Tides
•Storm surges
EROSION
http://gatm.org.uk/geographyatthemovies/coasts.html
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
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
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
Gatm – lsd video
4th one down
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
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 sitesCase studies:- Tenby, Holderness,
Hallsands, Abbotts Hall Farm,
Coastal management and defence - gatm
Groynes and beach renourishment – gatm Hard Engineering Protection Schemes
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