Processes of Marine & Aeolian Deposition Flashcards
Where is deposition occurring?
An environment with low energy waves - they have less energy to carry material
Abundant supply of material - an environment with intensive erosion
Sand and shingle accumulate faster than they are removed
Water pauses at the top of the swash - depositing material
Water is removed from waves as it percolates into beach material causing it too loose energy and deposit sediment
What are the types of deposition?
Aeolian, sub-aerial
What does aeolian deposition mean?
Wind deposition
What can aeolian deposition do?
Entrain, transport and deposit sediment
What factors influence aeolian deposition?
The time of day,
How does the time of day influence aeolian deposition?
Temperature influences size of the winds - pressure differential between land and sea - land is warmer, creates winds
Availability of sand - Low tides - leaves sand exposed to wind
How does the wind influence sand movement?
The wind tends to transport sand through saltation on or surface creep
What depositional land forms can Aeolian deposition cause?
Sand dunes
What are the main types of sub-aerial processes?
Weathering and mass movement.
What is weathering?
The breakdown of the coastline through the weakening of the underlying rocks in the area
Happens in situ
What are the types of weathering?
Mechanical, biological, chemical
What is mechanical weathering?
This type of weathering is influenced by climate - free thaw (takes place when water enters crack in rock, water freezes and expands, causing the rock to crack)
What is biological weathering?
Is the action of vegetation or organisms in coastal environments - birds or rabbits nest in cliff, weakening it. Seaweed can attach itself to rock, causing
What are the types of chemical weathering?
Hydrolysis, hydration, carbonation, oxidation, solution, acid rain,
What is chemical weathering?
Weathering that takes place because rock is exposed to air and moisture in coastal environment
What is hydrolysis chemical weathering?
Mildly acidic water combines with minerals to create clays and salts which wears down rocks
What is hydration chemical weathering?
Rocks absorb water and swells up, putting stress on rock causing it to eventually crack
What is carbonation chemical weathering?
CO2 dissolves in water to form carbonic acid which can dissolve chalk and limestone (common in coastal environment)
What is oxidation chemical weathering?
Causes the rock to disintegrate when oxygen dissolves in water forming oxides and hydroxides, this can dissolve rock
What is solution chemical weathering?
Dissolving of rocks
How does acid rain work as a chemical weathering?
Gases in the air combine with rain water - becoming acidic and dissolving rock
What is mass movement effected by?
Temperature or level of saturation
Height/angle of slope
Grain size within sediment
Why does the level of saturation effect mass movement?
More saturated - easier for landslides and the soil moves a lot
How does the height/angle of the slope effect mass movement?
Steeper cliffs will tend to have more rock falls as they become undercut by erosion causing instability - collapse
What are the different types of mass movement?
Landslides Rockfalls Mudflows Soil Creep Rotational slip
What is a landslide?
Softer rock will slip over each other - tends to happen after rainfall and steep gradient
What is rockfall?
Cliffs are undercut by sea, the rock will eventually collapse
What are mudflows?
Mud slips off slope after the lubricating of rainfall takes place
What is soil creep?
Continuous movement of soil down a slope at a slow pace?
What is rotational slip?
Has rotational movement on a concave cliff as soft material overlies more resistant material, whole sections of cliff face move downwards, accentuated by rainfall as it lubricates material
What is run off?
The running of water over land
Act as a depositional feature as water carries sediment and material through flooding, intense rain, stream cascades over the cliff edge, it also aids mass movement as it helps lubricate cliff
