Coastal Environments

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?

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

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

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 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

Managed Retreat 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.