how are coastal landforms developed Flashcards
what are the major process that shape a coastline?
- longshore drift (transport of material up and down the beach)
- deposition by constructive waves (build up of sediment)
- erosional process
- gravity, causing rocks to fall
- sub aerial weathering
- mass movement processes
what flows of energy could be influencing a coastal landscape
- kinetic energy
- gravitational energy
- solar energy
what flows of materials could be influencing a coastal landscape
- ocean currents
- longshore drift
what are 4 main process occurring on a coastline (TWED)
- weathering
- transport
- erosion
- deposition
what are the 5 conditions that deposition can occur under
- where the rate of sediment accumulation, exceeds the rate of removal
- when waves slow down immediately after breaking
- at the top of the swash, where for a brief moment the water is no longer moving
- during backwash when water percolates into the beach material
- in low energy environments like those sheltered from wind
know the basics of the table in the booklet 2A
what is abrasion
is when waves, armed with rock particles hit the coastline, causing a scouring effect.
what is attrition
when rocks, collide with each other whilst being transported, meaning that they tend to become much smoother and much more round
what is hydraulic action
occurs, when waves break against a cliff face, and air and water trapped in cervices becomes compressed, as pressure is realised it expands causing the rocks to crack.
what is pounding
occurs, when the mass of breaking waves, exerts pressure on a rock, thus leading to it becoming weaker and weaker over time (this force can be up to 30 tonnes per meter squared
what is soloution
works, by dissolving minerals, in the water, that can erode the rock, due to the sea being particularly acidic. (example would be magnesium carbonate)
what is suspension
small particles of sand, can be carried by currents (explains why sea water doesn’t tend to be clear of colour.
what is traction
where the largest particles in the load, may be pushed along the sea bed by the shear flow force of the sea.
saltation
when the sediment is to heavy to be carried by suspension, it may be bouncing along the sea floor when there is not enough energy for it to be suspended.
what is the difference between flows and slides
flow, involves lots of water however, landslides are due to undercutting a line of weakness
what is the difference between landslides and landslips
a landslide happens on a flat surface, whilst a landslip happens on a curved surface
what is the difference between rock falls and slumping
rock falls involve a sudden collapse and flow of sediment, and is most common of steep cliffs, whilst slumping tends to be a much slower process
how do swash aligned beaches form
they form in low energy environments such as bays that are affected by waves arriving roughly parallel to the shore
where do drift aligned beaches form
these form where the waves approach the coast at an angle, Longshore drift moves sediment along the bay, causing it to accumulate and lead to the formation of a spit
what are the three sources of sediment for beaches (typically)
- cliff erosion (5%)
- offshore, from the sea bed (mainly during periods of rise in sea level) (5%)
- rivers tend to provide around 90% of sediment, that is supplied to beaches