9: Rocky Coasts Flashcards
What are type A cliffs?
These are almost completely vertical cliffs that reflect the incoming waves back towards their source. This means that they are not subject to any significant erosion.
What are type B and C cliffs?
These are shore platforms cliffs. Type B are ramp styled and Type C are sub-horizontal styled.
What are type D cliffs?
Like type A except they are incised at the point in the cliff that where the sea level is. This is because these cliffs are composed of limestone
What are type E and F cliffs?
These cliffs feature either a beach or talus deposit at the base of the cliff
What are active cliffs?
Cliffs that are actively affected by sea processes
What are inactive cliffs?
Cliffs that are not being affected by sea processes
What are relic cliffs?
cliffs that used to be affected by sea level processes
What are re-activated cliffs?
Cliffs that were active then relic and are now subject to active processes again
Who was the first to realise wave cut platforms?
Darwin
What did Dana observe
The effectiveness of erosion on shore platforms
What did Davis observe?
How fluvial processes can erode volcanic islands and cause them to subside resulting in the obvious presence of coral reefs coming to the fore
What did Davis name this process he identified?
Skeletonisation
Describe dolerite
basaltic rock that forms hexagonal shape once it is eroded
Describe basalt
form tall hexagonal landforms when eroded
Describe Granite
forms rounded eroded boulders that are distinctively smooth
Describe sandstone
forms sharp vertical cliffs
Describe laterites
High iron concentration in rock strucutre
Describe eolianite
fossil dune deposits that feature very clear horizontal banding and are prevalent around Australia
Describe Calcarenite
sandy calcerous material
Order basalt , limestone, granite, eolianite, chalk and shale rock in order from least to most resistant
Eolianite, chalk, shale rock, limestone, granite, basalt
What are the 4 categories of processes affecting the erosion of cliffs?
Hydraulic
Mechanical
Physiochemical
Biological
What are the 5 hydraulic processes of erosion and explain them?
Hydrostatic pressure
wave quarrying (waves lodging rocks from surface)
water hammer (shear force of water)
pneumatic (pocket of air trapped between air and rock)
cavitation (similar to pneumatic and exploits small rock cavities)
What are the 2 mechanical processes of erosion?
Abrasion
Attrition
What are the 3 physiochemical processes of erosion and explain them?
Wet/dry (water layer levelling - physiochemical processes of the water levelled on a rock surface e.g. dissolving)
Freeze/thaw weathering
Salt weathering (tafoni)
Explain salt weathering (tafoni)?
Been described as honeycomb weathering as a result of the rock surface that is produced. Essentially salts crystallise in the rock and as they break away they take the rock with them
What are the 2 biological processes of erosion and explain them?
Grazers (limpets erode at the surface of rocks)
Borers (certain organisms bore in to and erode from inside the rock)
What happens to Type A cliffs at low, mid and high tides?
At all tides the process is the same because the cliff is completely vertical for a long vertical range. The waves are just reflected back out towards the sea
What happens to Type B cliffs at low, mid and high tides
A ramped shore platform will always cause the incoming waves to trip up and break. The different tides will just affect how early the waves breakW
What happens to Type C cliffs at low, mid and high tides
At the low tide the sea will not be able to overcome the platform and so will resemble what happens all the time for Type A cliffs. At mid tide it might be able to overcome the platform and so if it does it will only be a thin layer. At high tide there is a much greater chance it will be able to overcome the platform and so the waves will likely be able to cut away at the cliff
What is whether the coast forms a cliff or a ramp determined by?
Local lithology and breaking wave force
What is another way apart from erosion that coasts can be created?
Construction - tectonic uplift
Give an example of somewhere (coastline) that is caused by tectonic uplift?
Huon Peninsula
What is important to remember about how constructed coasts appear?
Eventhough they are constructed they can also be subject to later erosional processes
The faster the erosion at the base, the faster the…
erosion overall
