systems and processes Flashcards
what is a source of energy for a coastal environment?
wind (south easterly wind)
how does wave refraction occur?
it occurs when energy is concentrated at the headland and the wave bends and the energy is dissipated into bays either side
what happens when a wave enters shallow water?
The front of the wave slows and the wavelength shortens which causes the height to increase
What is wave energy affected by? (3 things)
strength of wind
duration of wind
the fetch
What do constructive waves look like?
they are low surging waves with a long wavelength
what do destructive waves look like?
they are high plunging waves with a short wavelength
which type of wave causes beach gain
constructive wave
Which type of wave causes beach loss
destructive wave
What is the beach profile needed for a destructive wave?
steeper but over time flattened
What is the beach profile needed for constructive wave?
gentle but over time made steeper
What is a marine process?
a process that occurs on a coastline and operates with the sea
What is a sub aerial process?
process that slowly breaks down the coastline
How does freeze thaw weathering work?
water fills crack in rock, then freezes, then breaks the rock as it expands
How does salt crystallisation weathering work?
saline creeps into the rocks and evaporates, leaving salt crystals behind
How does wetting and drying weathering work?
clay rocks expand when they are wet and contract when they are dry. this causes cracks that are prone to other weathering methods
What is a mass movement rockfall?
When pieces of rock fall off the cliff edge.
What is a mass movement mudflow?
saturated soil falls down a slope
What is a mass movement landslide?
Large blocks of rock sliding downhill
What is a mass movement rotational slip?
saturated soil slumps down a curved surface
What is erosional hydraulic action?
The force of fast flowing water hitting the bed and banks and forcing water and air into cracks. The changes in air pressure cause the river bed to weaken
What is erosional wave quarrying?
High energy waves hit the cliff face and enlarge joints and have the power to remove large chunks of rock
What is erosional cavitation?
compressed air in joints causes water to be under a lot of pressure and air comes out of the joints in fizzing enlarging fissures
What is transportation traction?
large stones and boulders roll along the seabed by moving water
What is transportation saltation?
small stones bounce along seabed, particles are thrust up and down causing continuous bouncing
what is transportation suspension?
particles of sand and silt are carried along by moving water which causes murky water
what is transportation solution?
dissolved materials transported through moving water
What is long shore drift?
waves approach the shore at an angle and material is pushed up the beach as swash. as the water runs back down the beach the backwash goes back down the beach and is picked up by an incoming wave. Sediment moves in zigzag movement.
What is a high energy coastline?
Waves are powerful
Rate of erosion faster than rate of deposition
Headlands, cliffs and wave cut platforms
What is a low energy coastline?
Waves are not powerful
Rate of deposition exceeds the rate of erosion
Beaches and spits
How are waves formed?
Frictional drag disturbs the surface and creates ripples. In open water there is orbital motion of water particles. Horizontal movement of water occurs near the coast as waves are driven onshore
What is marine deposition?
Takes place where the waves are low energy. The sea lays down material when there is a reduction in energy resulting in a decrease in volume of water.
What is aeolian deposition?
The transport and deposition of material by the wind
What are inputs of a coastal environment
energy from waves, tides and sea currents
sediment
geology of the coastline
sea level change
What are outputs of a coastal environment
dissipation of wave energy
accumulation of sediment above the tidal limit
sediment removed beyond sediment cells
How is wind an input into the coastal environment?
The fetch is the distance of open water which a wind blows interrupted
It places vital role in wave formation
