Costal Sediment Sources Flashcards
What are the 3 sources of coastal sediment?
Terrestrial
Offshore
Human
What is terrestrial sediment?
This is sediment that came from the land including fluvial deposition, weathering and mass movement, marine erosion, aeolian deposition and longshore drift
What is fluvial Deposition?
This is deposition carried out by rivers
Rivers transport sediment obtained via erosion, mass movement and weathering
As the river meets the sea it has a reduction in forward energy as it is prevented which then causes energy to dissipate resulting in deposition
What are 2 examples of mechanical weathering?
Freeze thaw- expands 9%
Salt crystallisation
What is Van’t Hoff’s law?
10 degree increase in temperature = 2.5x increase in rate of chemical reactions
What is marine erosion?
Using the energy of waves to shape the coastal landscape
What is hydraulic action?
when water is forced into cracks & joints breaking the rock apart
What is pounding?
The mass of breaking wave exerts pressure on the Rock, weakening it
What is abrasion?
When the waves launch rocks within the wave at the rock, wearing away at it
What is solution?
When the salts and acid in water dissolve minerals
How does climate impact the rates of solution?
As the climate warms there is more CO2 and as a result more acid rain and therefore more solution
What is attrition?
When rocks crash into each other and break into smaller pieces
What are mass movements?
When forces acting on a slope (gravity) are greater than the forces keeping the sediment on the slope (friction)
What are rock falls?
When rocks detached by weathering fall down the slope
What are landslides?
Layers slide sue to saturation & undercutting
How fast do winds have to be for Saltation and surface rolling?
40km/h
How does the wind Carry sand?
The wind raley carries sand in suspension due to its weight
Sand abrasion only occurs in heights up to 1m
What impact does sand abrasion have on rocky Coastlines?
The effects of sand abrasion scales with wind velocity
usually not much impact
Explain the process of longshore drift?
The swash of the waves travels in the direction of the wind vertically up the beach
Backwash then comes straight down due to gravity
Attrition occurs along the process so sediment becomes smaller and more rounded as distance increases
When does marine deposition occur?
Marine deposition occurs in low energy environments such as estuaries & lagoons
What is beach nourishment?
The process of taking sad from the bottom of the ocean and pumping it on to the beach
the goal is to create a wide sandy beach that can absorb energy and prevent coastal erosion
What is beach nourishment?
The process of taking sad from the bottom of the ocean and pumping it on to the beach
the goal is to create a wide sandy beach that can absorb energy and prevent coastal erosion
What happens to beach nourishment?
As soon as the sand is pumped onto the beach it is subject to Longshore drift
