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
what are runnels
ridges running parallel to the shore
what are berms
berns are smaller ridges that develop at the position of the mean high tide mark
what are cusps
they are small semi-circular depressions, (remember they are temporary features)
what happens to the sandbar in summer and winter
during summer it is pushed up the beach, by the stronger swash, causing a larger build up of sediment on the beach whereas in the winter the swash pulls the sediment down to form the sand bar
how are spit formed
A spit is an extended stretch of beach material that projects out to sea and is joined to the mainland at one end. Spits are formed where the prevailing wind blows at an angle to the coastline, resulting in longshore drift . An example of a spit is Spurn Head, found along the Holderness coast in Humberside.
what is floculation
a process, by which salt causes the aggregation of minute clay particles, into larger masses, that are to heavy to remain suspended in the water
name 3 types of weathering
- freeze thaw weathering
- solution
- organic acids (chelation)
what is freeze thaw weathering
water enters a fault in the rock and expands, when the water freezes. over time repetition of this process, causes a build up of pressure which in turn means that the fault gets weaker and weaker until eventually the rock breaks off
what is solution weathering
`this is a general type of weathering when minerals dissolve in water. Carbonation is a specific type of solution weathering
what is organic acid weathering (chelation)
when animals and plants decompose they release organic acids which are capable of dissolving minerals in rocks
describe the process of longshore drift
Longshore drift is a process of transportation that shifts eroded material along the coastline. Waves approach the coast at an angle. Swash carries sediment up the beach at an angle. Backwash carries sediment down the beach with gravity – at right angles to the beach.
what is dynamic equilibrium
dynamic equilibrium is a state at which erosion of rock and land is countered by an equal deposit of rock or land, resulting in no change to the geomorphology of a place.
what effect does sediment size have on beach morphology
the larger the sediment, the more likely it is to cause the beach to become more built up with sand deposits (sediment deposits)
what is the difference between a beach summer and winter profile
in the summer more deposition so there is no sandbar, meaning sediment is pushed up the beach, however during winter sediment is pulled off the beach more resulting in the formation of a sandbar
how are tomobolos formed
A tombolo is formed when a spit connects the mainland coast to an island. A spit is a feature that is formed through deposition of material at coastlines. The process of longshore drift occurs and this moves material along the coastline.
how are bays formed
bands of soft rock, such as clay are weaker meaning they are eroded quickly causing bay’s to form
how are headlands formed
when the sea attacks a section of coastline, with hard and soft rock, soft rock is eroded and hard rock juts out to from the bay.
how are shore platforms formed
attacks a weakness in the base of the cliff, forming a notch, later it collapse, then the cliff retreats and the left over land is the wave cut platform, this process repeats over time.
how are geos formed
an inlet or gully, or narrow and deep cleft. they are created by wave erosion going along faults in the hard rock.
how are blow holes formed
can be seas based, likely to occur in areas where there are crevices. Water, is then able to shot out of the top of the cliff
how are cliffs formed
through abrasion, hydraulic action, pounding, solution, freeze thaw weathering etc.
how are caves formed
when a crack in a cliff is formed by attrition, the hydraulic action widens it. Also, oxidation helps to from the cave. remember caves are only found on hard rock or they would collapse
how are arches formed
formed when a cave, breaks through to leave an arch
how are stacks formed
rocks are weakened by waves, forming an arch, that eventually breaks into a stack.
how are stumps formed
when the stack breaks, at the base the bit of rock remaining is called as stump, formed due to attrition, abrasion and hydraulic action.
what is wave refraction
Wave refraction involves waves breaking onto an irregularly shaped coastline, e.g. a headland separated by two bays. Waves drag in the shallow water approaching a headland so the wave becomes high, steep and short. The part of the wave in the deeper water moves forward faster causing the wave to bend.
how does the size of sediment affect beach morphology
the larger the sediment, the more built up it may become, whereas smaller sediment may take longer to build up sediment
what are the five erosional process, that can occur
- abrasion
- attrition
- hydraulic action
- pounding
- solution
what are the four transportation process that can take place?
- suspension
- traction
- solution
- saltation
why does deposition occur
- due to insufficient energy, to move sediment further.
- tidal range of 3 meters of less, is when we find large depositional features
- wave and wind direction, the supply of sediment, and the depth of the water all effect deposition rates.
