Coasts EQ2 (2B.2) Flashcards
What is fetch ?
How far the wave travels in open water
What are steps to a wave braking ?
When the orbital motion hits the seabed it creates friction which slows down the wave. As they approach the shore the wavelength decrease and the wave height increases. The crest moves faster than the trough and eventually the wave breaks.
What is beach morphology ?
The shape of a beach including its width and slope(beach profile) and features such as berms,ridges and runnels. It also includes the type of sediment found at different locations on the beach. These change during the summer and winter for example during winter there might be shallower beach progiles and more offshore bars whereas in summer there might be a steeper beach profile due to constructive waves being mroe common.
What are some of the temporal factors effecting a beach ?
- over a day as a storm passes and there are constructive and destructive waves
- between summer and winter (annually)
- climate change over a long period
What does wave size depend on ?
- strength of wind
- duration wind blows for
- water depth
- wave fetch
what are the 4 types of marine erosion ?
hydraulic action- water being forced in to the cracks in the rock which expands the cracks
abrasion-transported material such as rocks are hurled at the cliff face chipping away part of the cliff
corrosion-when the acid in seawater reacts with the alakaline rock to slowly disolve it
attrition- sediment moved by the ocean is colliding with other htings meaning parts are chipped off to make it smaller and smoother over time
what are the 4 types of transportation ?
traction-large and heavy rocks rolled along
saltation-smaller and lighter rocks bounced along
suspension-light sediments carried
solution-disolved sediments
what are some examples of depositional land forms ?
spits,bars and tombolos
what are the 3 components of the sediment cell process ?
- sources which is where sediment is generated for example erosion of cliffs or wind blowing sediment from land
- transfers which is places where sediment is moving such as through long shore drift or wave transport.
- sinks are areas where the dominat process is deposition so depositional landfroms are created
what is a sediment budget ?
the amount of sediment within a cell
what is negative and positive feedback ?
Normally the sediment output and input is equal but you can have negative and positive feedback which pushes the balance back if it isn’t equal. An example of negative feedback is wave erosion creating rock falls which protect the base of the cliff from further erosion. Positive feedback would be wind blowing sand away from dunes so plants can’t grow causing further erosion.
what are sub aerial processes ?
weathering processes that cause the gradual breakdown of rock in situe. There are 3 types:
- biological which is the weakening of the rocks by plants animals or microbes
- chemical which is erosion caused by chemical reactions rather than mechanical processes
- mechanical which is physical disintegration of rock without any change in the chemical composition
what are the 3 different sub aerial processes ?
mechanical, chemical and biological
what are some examples of biological sub aerial processes ?
- plant roots growing in to cracks and forcing them open
- birds and animals burrowing in to cliffs
what ares some examples of mechanical sub aerial processes ?
- freeze thaw is when water gets in to cracks and expands to further enlarge the crack
- wetting and drying which causes the rock to crack due to expansion and contraction at different temperatures
