Coasts Flashcards
1
Q
What makes up a coastal system
A
- Inputs
- Sores and components
- Flows / transfers
- Outputs
2
Q
Fetch
A
The distance a wave has travelled
3
Q
What does larger fetch mean
A
The waves can be acted upon by the wind for a longer time so gain more energy
4
Q
Inputs
A
Wind, precipitation, sediment
5
Q
Flows/transfers
A
LSD, mass movement, erosion
6
Q
Stores and components
A
Beaches, headlands, bays, sand dunes
7
Q
Outputs
A
Evaporation, ocean currents, rip tides
8
Q
What might dictate sediment in cell
A
- Weather = storms
- Humans = coastal defence
9
Q
UK sediment cells
A
11 major cells which are subdivided into sub cells local to an area
10
Q
Subcells
A
Generally bordered by 2 large headlands or deep water
11
Q
Dynamic equilibrium
A
An ever changing state but in balance
12
Q
Causes of tides
A
Gravitational pull of the sun and moon
13
Q
Wave formation
A
Waves form when winds blowing across the water’s surface transfer their energy to the Water
14
Q
What happens to sediment in the direction of prevailing wind
A
Gets smaller and rounder due to LSD and attrition
15
Q
High energy coast
A
- Rough landscape
- Little deposited material
- High erosion
16
Q
Low energy coasts
A
- Smooth coastline
- Calm waves
- Sheltered areas
17
Q
Constructive waves
A
Add material to the coastline with strong swash
18
Q
Destructive waves
A
Remove material with strong backwash with high erosion
19
Q
Why are sediment cells considered closed systems
A
- Sediment exclusively moves between the stores retained by the two headlands
- Sediment created through the erosion of cliffs
20
Q
Why is the coastal orientation key to determining coastal characteristics
A
Winds prevailing direction and magnitude
21
Q
Coastal weathering
A
- Biological
- Chemical
- Mechanical
22
Q
Sediment cell example
A
Flanborough head
23
Q
Biological weathering 2
A
- Plant roots growing into cracks
- Animals burrow into weak points
24
Q
Mechanical weathering 3
A
- Freeze thaw
- Salt crystallisation
- Wetting and drying
25
Freeze thaw erosion
Water enters a fault, freezes and then expands repeatedly
26
Crystallisation erosion
Can grow within cracks and expand
27
Wetting and drying erosion
Rock wetting of certain rocks make them expand and shrink
28
Positive feedback
Feedback that speeds up processes
29
Negative feedback
Feedback that slows processes
30
Mass movement
Downhill movement of sediment under gravity adding sediment
31
Geomorphical processes
- Erosion
- Transportation
- Deposition
32
Factors that affect erosion 4
- pH
- Geology
- Human presence
- Wind speed/direction
33
Transportation methods 4
- Traction
- Suspension
- Saltation
- Solution
34
Traction
Large boulders rolled along seabed
35
Saltation
Pebble sized particles bounced along seabed
36
Suspension
Small particles carried along water
37
Abrasion
Eroded material thrown against the rock
38
Attrition
Rocks carried are thrown against each other, smoothing them
39
Solution
Soluble materials dissolved in water
40
Factors affecting transportation
- Strength of waves
- Size of sediment
41
Wave cut platform
Flat area of rocks extending from base of cliff
42
Long shore drift alternative name
Littoral drift
43
Effect of wave cut platform
Waves have further to travel in shallow water and so break earlier, dissipating energy
44
Formation of wave cut platform
- Waves produce a wave cut notch on a cliff
- As cliff is undercut it collapses and gradually retreats
- Leaving behind a platform made from the base of the cliff
45
Bedding planes
Flat surfaces along which rocks tend to separate or break
46
Cliff profiles are influenced by
Geology and tectonic movement dips
47
Vertical bedding planes
When rock below is eroded it is on the same plane which means the whole plane stumps
48
Horizontal bedding planes
Rock above not affected by erosion below
49
Where can’t wave cut platforms be formed
- Soft rock
- Steep bedding planes
50
Causes for weaknesses in cliff
- Rock band orientation
- Bedding plane
- Layering of sediment
51
Salt marsh formation
The area behind a spit will become a salt marsh due to low energy
52
Formation of a spit
- LSD continues in direction of prevailing wind until coastline changes
- Sediment is taken out to sea until it looses energy and deposits, building up over time
- Hooks round due to secondary wind direction
53
Depositional landforms
- Beaches
- Spits
- Tombolos
- Offshore bars
54
Tombolo
Spit that connects an island to the mainland
55
What causes the hook on a spit
- Wave refraction curves sediment
- Second dominant wind direction
56
Wave refraction
The bending of waves due to reduction in velocity so they move nearly parallel to the shoreline
57
Neep tide
Sun and moon fight against each other, pulling in opposite planes, spreading water evenly
58
Spring tide
Sun and moon pull in the same plane, highest tides
59
Sand dune
Accumulation of mounds of sand blown by the wind (aeolian)
60
Stack formation 4
1. Weakness in headland
2. Carves out cave, punching through, forming an arch
3. Erosion attacks base, weathering attacks roof, roof cannot hold itself up and collapses
4. Forming a stack until it topples and leaves behind a stump
61
Tidal range
Difference in height between the high and low tide lines
62
Tidal range influences on processes
Dictates how long a process can act on a cliff face, small range focuses on the same area for longer
63
Sand dune formation
1. Sediment accumulates on beach with large tidal range to dry
2. At low tide, wind carries sand by creep or suspension
3. And obstacle that causes the sand to lose momentum and settle, forming an embryo
64
Pioneer species
First species to populate an area
65
Flocculation
Particles come out of suspension and lump to form something larger
66
Halophytes
Salt tolerant plants
67
Conditions for mudflats 4
- Sheltered low energy environment
- large tidal range
- Supply of sediment
- Prevailing wind
68
Succession of salt marshes
- Pioneer plants first move
- Builds up land allowing other plants to move in
- makes area an extension of land
69
Isostatic change
A LOCAL rise or fall in land level causing RELATIVE sea level change
70
Eustatic change
An ACTUAL change in sea level
71
Emergent landforms
Raised beaches, abandoned cliffs, marine terraces
72
Submergent landforms
Rias, fjords
73
Effects of climate change on coastline 4
- Major infrastructure nearby
- Disrupt fresh water supplies
- Damage environments
- Urban environments at risk
74
What is a sediment cell
Areas that encompass the intertidal and nearshore moment of sediment
75
Sediment cell advantages
Allows for a sediment budget to be established to understand coastal changes
76
Sediment cell disadvantages
Fine sediment is not confined by boundaries and so model is not entirely closed
77
Swash aligned beach 3
- Smooth curved beach
- Waves aligned with beach
- Likely a closed sediment cell
78
What is a swash aligned beach
- The deposited sediment moves up and down the beach
- Shaped by waves arriving parallel to the shore
79
Drift aligned beach 4
- Angle of beach based on prevailing wind
- Backwash at 90°
- Material is moved and becomes smaller over time
- Sediment moves to another beach
80
What is a drift aligned beach
Drift aligned beaches are produced where waves break at an angle to the the coast
81
Wave quarrying
Waves breaking against cliffs traps air which compresses it into gaps which creates explosive effect
82
Sea level rise facts
- only 2/3 of ice sheets have potential to melt
- can cause 72 meters of sea level rise
83
Offshore bar formation
- Destructive waves remove sediment parallel from the beach and form the offshore bar
- constructive do the opposite
84
Sources of energy
- wind
- waves
- currents
- tides
85
Why do areas receive variable wave energy
- Direction of prevailing wind
- Larger fetch
- Wind circulation (Gulf Stream)
86
Sources of sediment
- river estuaries
- cliff erosion
- offshore sediment
- wind
87
Factors that affect rate of erosion 5
- geology
- wind
- pH
- landscapes
- coastal defences
88
Required conditions for mudflats 5
- Sheltered low energy environment
- Larger inter tidal range
- Dominant wind direction
- sediment supply
- Occasional flooding
89
Threats to salt marshes 3
- SLR
- Wave energy increase
- Higher rates of flooding
90
What is the difference between weathering and erosion
- Weathering = land based
- Erosion = water
91
Weathering and processes
- Land based processes above water line
- Weathering
- Mass movement
92
Erosional processes 5
- Hydraulic action
- Abrasion
- Attrition
- Solution
- Wave quarrying
93
Causes for joints in bedding planes
- Igneous rock cooling
- Compression/stretching sedimentary
94
Joint
Fractures in rocks created without displacement increasing erosion rates by creating cracks
