Coastal Processes Flashcards
1
Q
Division of coastal processes
A
- sub-aerial processes (operate on land)
- marine processes (operate in the sea)
- Aeolian processes (driven by the wind)
2
Q
What is erosion?
A
Breakdown and removal of material by wave action
3
Q
What is hydraulic action?
A
- power of the waves hits the cliff face directly and loosens the interior of joints and bedding planes.
- Marine Process
4
Q
What is wave quarrying/pounding?
A
- when high energy, talk waves hit cliff face they have power to enlarge joints and remove large chunks of rock in one go through vibration. Occurs due to intense force of these waves.
- marine process
5
Q
What is abrasion?
A
- high energy waves have energy to carry pebbles with force. As wave breaks at the foot of the cliff, material is thrown at the cliff face and wears it away by chipping fragments off.
- marine process
6
Q
What is solution?
A
- weak carbonic acid in seawater dissolves rock at the coastline and breaks it down
- marine process
7
Q
What is attrition?
A
- rocks and boulders which have already been loosened from the coastline are ground over each other in the water - usually by repeated swash and backwash - and over time the angular edges becomes smoothened and rounded and boulders/fragments become pebbles, pebbles become shingle, and shingle may become sand
8
Q
What is weathering?
A
- the breakdown of rocks at the earth’s surface without the rocks going anywhere
- sub-aerial process
- can be either: physical, chemical or biological
9
Q
What is salt weathering?
A
- salt water evaporating leaves behind salt crystals. These grow in size gradually widening cracks in the rocks.
10
Q
What is wetting/drying?
A
- minerals in rocks may absorb and release moisture as tides rise and fall leading to internal loss of coherence
11
Q
What is freeze-thaw action?
A
- sub-zero air temperatures can cause rain water in surface fissures to freeze and expand
12
Q
What is chemical solution?
A
- minerals in coastal rocks are dissolved by chemicals in sea water and by acid rainfall (known as carbonation)
13
Q
What is biological weathering?
A
- plant roots enlarging rock fissures, nesting sea birds, marine organisms that drill into rock such as the piddock
14
Q
What is mass movement?
A
- Sudden movement of loose material down a slope due to gravity.
- type of mass movement dependent on type of material, the angle of the slope and level of saturation.
- sub-aerial process
15
Q
What is rockfall?
A
- loose fragments of rock break off a cliff face and fall onto the beach below.
- creates talus/scree at the base of the cliff
16
Q
What is a landslide?
A
- blocks of rocks become detached from the cliff face and slide down the cliff face
- occurs when bedding planes dip towards the sea
17
Q
What is a mudflow?
A
- saturated soil and rock flows down a cliff face
- happens after heavy rainfall on loosely consolidated cliffs
18
Q
What is rotational slip (slump)
A
- saturated soil and rock slides down a cliff face with a rotational (curved) movement
- creates a stepped profile in the cliff
19
Q
Types of Transport (Marine Processes)
A
- solution
- suspension
- traction
- saltation
20
Q
What is suspension?
A
- fine material such as clay and sediment is carried by the sea
21
Q
What is solution?
A
- dissolved minerals are carried by the sea
22
Q
What is traction?
A
- large boulders and pebbles are rolled along the sea bed
23
Q
What is saltation?
A
- small stones, pebbles and silt bounces along the sea bed
24
Q
What is longshore drift?
A
- prevailing wind approaches the coast at an angle
- waves approaching at an angle same as wind as does swash
- backwash driven by gravity straight backwards
Swash and backwash cycle repeats moving sediment along the beach
25
Q
What is deposition?
A
- waves drop sediment they are carrying
- occurs when wave energy is reduced
- constructive waves deposit sediment
- calm weather conditions
- sheltered areas of the coast (bays, behind spits)
- at a river estuary - the interaction of river water/currents and the sea encourages deposition
