Coasts KQ1 Flashcards
Examples of inputs of energy?
Waves
Wind
Solar sources
Definition of a “system”?
An association of components that are connected to each other and the surrounding environment through flows of material and energy.
Examples of outputs of energy?
Noise and
Heat…
Because material is constantly being moved.
Examples of inputs of material?
Sediments from... Ocean Rivers Cliffs Coastal areas from further along the coast
Examples of outputs of material?
Sediment is moved to other parts of the coast and offshore.
Definition of a “landform”?
A physical feature on the earth surface.
Definition of “erosion”?
The wearing away of material by the action of…
Water
Ice
Wind
Definition of “weathering”?
Disintegration of rocks by the action of... Weather Plants Animals Chemical action
Definition of “marine processes”?
Action of the sea on coastal landforms.
Definition of “sub-aerial processes”?
Processes that are active on the face and the top of cliffs.
Name 2 factors that affect the rate of marine erosion?
Geology
Climate
Definition of “physical weathering”?
The rock is disintegrated into pieces that are normally angular and coarse.
Definition of “chemical weathering”?
Rock is disintegrated because the chemical structure of the rock and its minerals are altered.
Explain salt crystallisation (physical)?
Happens in well jointed, porous rocks.
The sea water evaporates leaving salt crystals behind.
Which then grow in the cracks and pores and prises the rock apart into angular fragments.
Explain “wetting and drying” (physical)?
Occurs in exposed rock surfaces.
The rocks are periodically wetted and dried.
The rocks expand when wetted and contract when cry causing the rock to break up = slaking
When this is repeated it causes disintegration and HONEYCOMB weathering is produced.
Explain “frost shattering / freeze thaw” (physical)?
Well jointed, bedding rocks.
Water enters the cracks/joints in planes.
In fluctuating temp. areas 0-9 degrees the rock expands by 9%.
Exerting pressure on the rocks = residue of angular fragments called SCREE.
Explain “insolation and exfoliation weathering / heating and cooling weathering” (physical)?
Exposed, igneous rocks like granite.
Thermal expansion and contraction during rising and falling temps. between 30-50 degrees.
Stresses are created = explosive failure.
Exposed rock heats up more than cooler rocks below = spall curves sheets called ONION SKIN weathering.
Explain “carbonation” (chemical)?
Well jointed, bedding rocks like limestone.
CO2 gas in atmosphere reacts with rain and pore water in soil to form carbonic acid.
Air in soil from plant decay makes it even more acidic.
Resulting in a residue of insoluble clays and dissolves the cements leading to rock collapse.
Explain “oxidation” (chemical)?
The rocks contain minerals with Fe
Some of the minerals react with O2 dissolved in the water to form oxides and hydroxides.
Fe2+ is changed to Fe3+ = collapse of molecular structure
Resulting in the formation of rust (limonite)
Explain “chelation” (chemical)?
Lichens and decaying matter on any rock
The organic acids enter cracks, joints and pore spaces.
Organic acids attack certain minerals releasing Fe and Al
Leading to the Fe and Al being lost and the rock disintegrating.
The types of geology that affect the rate of erosion are?
Rock cohesion - the stronger the grains in the rock are cemented together the longer it takes for erosion to take place (granite and clay)
Lines of weakness - waves attack the weaknesses and are easily eroded.
Composition - when rocks are made of resistant minerals eg Quartz they are eroded slowly compared to Calcium made rocks that are soluble in water therefore erode quickly.
The types of climate that affect weathering?
Precipitation - increased = increased chemical weathering (especially in hot weather)
Temperatures - warm/hot = increased chemical weathering = evaporation
Cold = increase in mechanical weathering = freeze-thaw.
Name the slow types of mass movements?
Soil creep - individual soil particles are moved to the surface through wetting and freezing (rate is 1mm in UK and 5mm in rainforest p/a)
Rain splash - on flat surfaces rain droplets compact soil and dislodge particles on steep slopes so downwards push increases.
Name the flow types of mass movements?
Surface wash - soil infiltration capacity is exceeded leading to the formation of gullies.
Sheet-wash - un-channeled flow of water over soil and carries material from rain splash.
Throughflow - water moving down through the soil in a natural channel allowing material to be transported at a higher volume.
Name the fast types of mass movement?
Slides - slides of material that maintain their shape until the base of the slope (caused by prolonged rainfall)
Falls - occur on steep edges >70 degrees originally caused by weathering, weakening the rock and causing a fall. If the fall is short it causes a talus/straight scree if long it causes a concave scree.
Slumps - occur with weaker rocks like clay as it absorbs the water, becomes heavy and flows along the slip plane to the base where is will be undercut and further weaken the strength.
Explain hydraulic action?
The pressure of the water moves rock and sand.
This pressure can loosen rocks, cause pneumatic pressure (trapped air in joints) then causing wave quarrying (explosive decompression of air when wave retreats) and swash and backwash remove sediment from swash zone.
The LANDFORMS created are: BLOW HOLES/GEOS/CAVES/CLIFF PROFILE AND RETREAT
Explain abrasion?
Waves use pebbles and sand to wear away rock in the inter-tidal zone.
This is slow in hard rocks creating a smooth area.
Differential erosion is accentuated with more resistant rocks protruding and temporarily protecting the less resistant rocks.
This forms : WAVE CUT NOTCHES/CAVES/INTER-TIDAL PLATFORMS.
Explain corrosion?
Wave action aerates the water allowing more weathering.
In shallow water organisms release CO2 = increasing carbonation
Effects are mostly seen in limestone coasts where rounded hollows are formed and are enlarged by abrasion.
Can also create lapies and visors.
