coasts Flashcards
what is is and what are the four components
the littoral zone
the littoral zone is the part of the coasts between high water and low water marks
( the area that is sometimes covered in water and sometimes exposed to air )
the area of the shoreline where the land is subject to wave action
- offshore
- nearshore
- foreshore
- backshore
where is this area
offshore
the area of deeper water out to sea , beyond the influence of waves
where is this area
Nearshore
the area of shallow water beyond the low tide mark
withi which friction between the seabed and waves causes them to break
where is this area
foreshore
the area between the high tide and low tide mark
intertidal zone - covered by high tide exposed by low tide
where is this area
backshore
the area above the high tide mark
not covered even at high tide
affected by wave action only during major storm events
* why are they an open system * inputs * processes * outputs
coasts as an open system
the coast can be considered an open system , which means energy and matter can enter and leave the system
* * inputss-
deposition
the laying down of sediments carried by wind or water
coastal erossion
the process in which cliffs are wor away and transported by the sea
transportation
the movement of material
weathering
the breaking down of of rocks by the action of rain water ,extremes in temperature and biological activity
masss movement
the large scale movement of material
eg land slides , rockfalls
erosion
abrasion
as peices of material knock into each other , they get smaller , smoother and more rounded
erosion
attrition
material (e.gpebbles) is hurled against the cliff by the waves ,wearing away at it
erosion
hydraulic action
wghere the waves crash into the base of the cliff, forcing air and water into the cracks /joints . this exerts a pressure , and the cracks growin size until the rock detaches
erosion
soloution
solouble particles can be dissolved by the acids in the sea water (e.g calcium carbonate n chalk is dissolved by seawater )
transportation
traction
large materials such as boulders are rolled along the sea bed ( because they are heavy , the waves do not have enough energy to carry them )
transportation
saltation
pebbles or small stones are lifted by the sea when it has enough energy , but dropped when it loses energy . as a result pebbeles are bounced alng the sea bed
transportation
suspension
smaller particles such as sand foat in the sea
transportation
solution
particles such as clay are dissolved into the sae, and constantly move with the water
2 things
transportation is influenced by
- angle of wave attack - if the wind is lowing directly onshore materiall is moved up and down the beach by waves but is not transported along the beach - swash aligned beach . but if if the waves are coming in at an angle then material is transported along the beach in a zigzag fashion by longshore drift .
- tides and currents - currents are the fow of water in a perticular direction , these currents transport sediment to the nearshore and offshore zones .
what is it + 2 methods
deposition
when the sea loses energy , it drops the sand , rock particles and pebbles it has been carrying
1. gravity settling
2. flocculation
deposition
gravity settling
the waters velocity decreases so sediment begins to be deposited
deposition
flocculation
this is an important process in salt and tidal marshes . clay particles clump together due to chemical attraction and then sink due to their high density
sub-aerial processes
are land based process wich alter the shape of the coastline
meathering
massmovement
