Paper 1 Coasts Flashcards
Why can coastal landscapes be viewed as systems?
Open systems - They have inputs, outputs and throughputs. They store and transfer energy and material.
What are the components of a coastal open system?
Inputs - kinetic energy from wind/waves, potential energy from deposition of material, thermal energy from the sun.
Throughputs - stores, longshore drift, nearshore sediment accumulations.
Outputs - wind erosion of beaches, marine erosion (hydraulic action) and evaporations.
What is dynamic equilibrium?
The system has a disturbance and then undergoes self-regulation to restore the original equilibrium.
Mudflats v salt marshes
Mudflats, usually found closer to the water, are prone to flooding from high tide so are harder to grow vegetation on. Salt marshes are further back and can grow more vegetation on.
What is a sediment cell?
A stretch of coastline in which sediment movement is largely self-contained. It is a closed system but impossible to be completely a closed system as fine sediment can still move through variations with tidal currents and wind direction changes, but it is largely closed because of large physical barriers like headlands. In the UK an example is Lands end.
What is weathering?
Breakdown or disintegration of rock in situ. It leads to the transfer of material. It is active at coasts where rock faces are exposed to elements and cliffs are kept fresh by regular removal of debris by the sea.
What is chemical weathering and what are the types?
Chemical weathering involves a chemical reaction where salts may be dissolved. Examples are carbonation, oxidation and solution.
What is carbonation in chemical weathering?
When rainwater absorbs carbon dioxide from the air, it forms a weak carbonic acid. When it hits rock, it reacts with calcium carbonate which is easily dissolved. It is more effective in winter as the cooler the rainwater, the more carbon dioxide is absorbed. This happens in limestone for example.
What is oxidation?
The reaction of rock minerals with oxygen to form rust leaving rocks more vulnerable to weathering.
What is freeze-thaw weathering and what is it an example of?
An example of mechanical weathering.
When water enters a crack in a rock, it freeze which expands the rock as the volume increases. This exerts pressure onto the rock and forces the crack to widen. Eventually fragments break away and collect at the base of a cliff for the sea to use in marine erosion.
What is salt crystallisation?
When salt water evaporates, it leaves salt crystals behind. These grow over time to exert pressure on the rock and can corrode rock.
What is biological weathering? Describe some examples of it.
Biological weathering is the breakdown of rocks by organic activity. E.g:
• plant roots growing into small cracks, widening the rock and breaking it up.
• birds digging burrows into cliffs.
• water running through decaying vegetation, making it become acidic and leading to chemical weathering
• marine organisms are capable of burrowing into rocks or secreting acids.
What is mass movement?
The downhill movement of material under gravity. It provides an input to sediment cells and provides rock to be eroded by the sea.
What is soil creep as mass movement?
Slow movement of individual soil particles downhill.
What is a mudflow?
Earth and mud flowing downhill over weak rock. Water pressure forces rock particles apart leading to slope failure. This is a form of energy within the slope system. They are often sudden and fast flowing.
Landslide meaning
Block of rock moving rapidly downhill along a surface. This block of material remains largely in tact. Triggered by land becoming lubricated, for example by earthquakes or heavy rainfall.
Rockfall explanation
Sudden collapse of individual rock fragments at a cliff face. Commonly associated with steep or vertical cliffs. Triggered by mechanical weathering. The scree that it forms at the base of a cliff is a temporary store within the coastal system.
Landslip
Slide surface is curved rather than flat. Commonly occurs in weak clays and sands. Sharp break up of slope to form a scar.
What are ocean currents?
Generated by the earths rotation, they act as a conveyor belt to transport cold and warm water across the globe. (Thermal energy) This helps to regulate global climate change as it counteracts the uneven distribution of solar radiation. They can modify local climate and influence weathering and other subaerial processes.
Describe warm and cold currents.
Warm - transfer heat from low latitudes to the poles. They have more energy.
Cold - move cold water from polar regions to the equator.
How can ocean currents affect coastal landscapes?
• Warmer currents have more energy so in some places can create more erosion and weathering.
•rising sea levels and changing climate patterns can accelerate coastal erosion and alter sediment budgets.
Describe the relationship between ocean currents and climate change.
•ocean currents regulate climate change by counteracting the uneven distribution of solar radiation on the surface.
•climate change can affect this, as waters warm up more there will be less of an even distribution and conveyor belts will not work.
What is a fetch?
The distance of open water which wind can blow over as it approaches a coastline.
Describe some terrestrial sources of sediment into the coastal system.
•Terrestrial and mass movement - from nearby cliff breaks or rock falls driven by gravity
•terrestrial and fluvial - rivers directly deposit sediment at the coasts.
•marine erosion - erosion of weak cliffs by high energy waves, can be amplified by storm surge events.
•longshore drift - supplying sediment from one coastal area to another.
•aeolian deposition - blowing fine sediment over locations.
Give an example of an offshore source of sediment.
Marine deposition - waves bringing sediment to shore from offshore locations.
What does beach nourishment do?
It is a human factor of sediment reaching the coastal system.
When a sediment budget is in deficit, it adds sand to the beach to maintain equilibrium to preserve the coastal environment.
