Coasts Flashcards
(79 cards)
1
Q
How is the coast a natural system?
A
- Inputs of energy and sediment
- Erosional landforms and landscapes
- Depositional landforms and landscapes
- Outputs of energy, sediment removal and sediment above tidal limit
2
Q
What are the coastal zones?
A
Offshore, Nearshore, Foreshore, Backshore, Swash Zone, Breaker Zone, Surf Zone
3
Q
Zones of the coast in order moving from sea to land
A
Offshore > Nearshore > Foreshore > Backshore
4
Q
Wave zones in the correct order
A
Swash Zone > Breaker Zone > Surf Zone
5
Q
What is the Offshore?
A
Beyond the point where waves have an impact on the seabed
6
Q
What is the Nearshore?
A
Between Low Water Mark and area where waves cease to have an influence on the seabed
7
Q
What is the Foreshore?
A
Between High Water Mark and Low Water Mark
8
Q
What is the Backshore?
A
Above High Water Mark up to landward limit of marine activity
9
Q
What is the Swash Zone?
A
Turbulent water rushes up the beach as the swash
10
Q
What is the Breaker Zone?
A
Waves approaching begin to break
11
Q
What is the Surf Zone?
A
Between waves breaking and moving up the beach as swash
12
Q
What are the sources of energy?
A
- Waves
- Winds
- Tides
- Wave Refraction
- Currents
13
Q
Wind as a source of energy
A
The energy depends on the strength, duration and fetch
14
Q
Tides as a source of energy
A
Gravitational pull of the moon, and the sun, create a spring tide every 14 days when aligned and neap tide every 14 days when at a right angle.
15
Q
Wave Refraction as a source of energy
A
Energy of a wave becomes concentrated on headlands and dissipated at bays, as waves in shallow water slow down due to friction with the sea bed.
16
Q
Features of a Destructive Wave
A
- High height
- 10-14/minute
- Backwash more powerful than swash
- Sediment removed
- Steep beaches
17
Q
Features of a Constructive Wave
A
- Low height
- 6-8/minute
- Swash more powerful than backwash
- Beach built up
- Gentle beaches
18
Q
Why do tides vary?
A
- Morphology of sea bed
- Proximity of land masses
- Coriolis force
19
Q
Three different types of currents
A
- Longshore currents
- Rip currents
- Upwelling
20
Q
What are longshore currents?
A
Longshore drift
21
Q
What are Rip currents?
A
Move away from the coastline, e.g. at a headland
22
Q
What is Upwelling?
A
Cold water makes its way to the surface
23
Q
What are Sediment cells?
A
A stretch of coastline, usually bordered by two headlands, where the movement of sediment is largely contained.
24
Q
How many sediment cells are there around England and Wales?
A
11
25
What is the Sediment Budget?
The amount of sediment that is available and tries to be in dynamic equilibrium. Can be upset by a storm or sudden increase in discharge or by human activity.
26
What are the geomorphological processes?
- Erosion
- Transportation
- Deposition
- Weathering
27
Definition of geomorphological process
Processes involved in the change of landforms
28
What are the coastal processes of erosion?
- Wave Quarrying
- Attrition
- Solution
- Hydraulic Action
- Abrasion
29
What is Wave Quarrying?
Cavitation that traps air causing huge pressure, which is released when wave withdraws
30
What is Attrition?
Material being carried by the sea hits against each other becoming smaller, rounder and smoother
31
What is Solution?
Rocks, normally limestone or other rocks containing carbon, are dissolved. This is normally by rainfall and is therefore not technically erosion.
32
What is Hydraulic Action?
Sheer force of water puts pressure on the rocks and forces them apart
33
What is Abrasion?
Material is used by the waves e.g. shingle which is thrown at the cliff
34
What are the coastal processes of transportation?
- Saltation
- Traction
- Solution
- Suspension
- Longshore Drift
35
What is Saltation?
Sediment bounces along the bed of the sea and dislodges other particles
36
What is Traction?
Bedload rolls along the seabed
37
What is Solution? (T)
Minerals are dissolved and are carried in the water
38
What is Suspension?
Particles are carried along in the water
39
What is Longshore Drift?
Swash comes in at an angle due to prevailing wind direction, backwash straight back down due to gravity moves material in a zig zag along the coast
40
What are the coastal processes of Deposition?
- Where marine energy is lost
| - Aeolin (carried/deposited by the wind)
41
How does Deposition occur Where Marine Energy is Lost?
- When wave slows down after breaking
- Where accumulation is quicker than removal
- Where the coast changes direction
- Just before backwash
42
What is the term to describe where the wind picks up and transports sand?
Entrain
43
What are Sub-Aerial Processes?
Land-based that happen below the air
44
What are the THREE different types of Weathering?
- Mechanical
- Chemical
- Biological
45
What are the examples of Mechanical Weathering?
- Freeze-thaw
- Salt Crystallisation
- Wetting & Drying
- Exfoliation
46
What is the process of Freeze-Thaw weathering?
Water gets into the cracks, expands 10%, puts pressure on rocks until they crack and break. The shattered, angular fragments are found at the base as scree (talus)
47
What is the process of Salt Crystallisation weathering?
Salt crystals are deposited in cracks and accumulate under drier conditions, over time it applies pressure to the rocks and they crack.
48
What is the process of Wetting & Drying weathering?
Common on the coastline, in the inter-tidal zone, with clay and shale which expands when wet and contracts when dry. This produces cracks which are then vulnerable.
49
What is the process of Exfoliation weathering?
Rock under considerable heat will expand and then cooled by the sea causing rapid contraction. This repeated process causes the layer to crack and peel off.
50
What is another name for Exfoliation?
Onion skin weathering
51
What are examples of Chemical Weathering?
- Oxidation
| - Carbonation
52
What is the process of Oxidation?
Rocks containing iron (ferrous) compounds experience this when turned into a ferric state (rusting) when oxygen and water are available, leading to disintegration
53
What is the process of Carbonation?
Sea and rain absorb carbon dioxide forming carbonic acid which then dissolves the calcium carbonate in rocks such as limestone or chalk into calcium bicarbonate, especially
54
What two animals are responsible for Biological weathering?
Puffin
| Piddock
55
How do plants cause biological weathering?
Growing plant roots widen cracks, in windy conditions these can widen even further. Seaweed also moves a lot in stormy conditions which weakens rock
56
How do Piddocks cause biological weathering?
Piddocks drill holes into the rocks which weaken and get wider over time.
57
How do Puffins cause biological weathering?
Puffins excavate nests into the rocks which weakens them
58
What is Mass Movement?
A sub-aerial process, involving the downhill movement of material under the influence of gravity
59
What are the SIX types of mass movement?
- Soil Creep
- Rotational Slumping
- Rock Falls
- Landslides
- Mudflows
- Runoff
60
What is Soil Creep?
Very slow movement, dislodged by raindrops or wave splash and freeze/thaw or wetting/drying
61
What is Rotational Slumping?
Heavy rain infiltrates unconsolidated soil. Impermeable soil traps water adding weight, undercutting causes collapse on slip plane.
62
What are Rock Falls?
Physical weathering, weaknesses are exposed and it can't be supported
63
What are Landslides?
Significant sections of unconsolidated shales and sandstones, that have been lubricated
64
What are Mudflows?
Excessive amounts of rainfall, infiltration can't take place, fine particles of mud become dislodged
65
What is Runoff?
Intense rainfall, impermeable surface, transports fine material
66
Examples of Caves/Arches/Stacks
- Old Harry, Swanage
- The Needles
- The 12 Apostles
67
Examples of Cliffs/Wave Cut Platforms
- Watchet, West Somerset
| - Kimmeridge Bay
68
Examples of Headlands & Bays
Swanage Bay
69
What is a swash-aligned beach?
No drift, bays, waves parallel to beach
70
What is a drift-aligned beach?
Drift, waves oblique, regular coastline
71
What are the landforms of coastal deposition?
- Beaches
- Simple and Compound Spits
- Tombolos
- Offshore Bars
- Barrier Islands
- Bar/Barrier Beach
- Sand Dunes
- Saltmarsh/mudflat
72
What is the process of the development of cliffs and wave cut platforms?
- Waves attack the base of the cliff, via abrasion and hydraulic action
- Create a wave-cut notch which is undercut, becomes unstable and collapses
- Notch migrates inland and cliff retreats leaving a gently sloping wave-cut platform, exposed at low tide
- Wave cut platform is smoothed by abrasion and solution
- Most are less than 0.5km
73
What is a concordant coastline?
Geology runs parallel to the coast e.g South Dorset and Dalmatian Coastline
74
What is a discordant coastline?
Geology positioned at right angles e.g. Purbeck, Dorset
75
What are the factors in the development of cliff profile features?
- Structure
- Lithology
- Geomorphology
76
How does Lithology affect cliff profile feature development?
Physical properties of a rock such as its resistance to erosion, or rock type
77
How does structure affect cliff profile feature development?
Whether the rocks run parallel or perpendicular, joints and bedding planes.
- Horizontal: produce steep cliffs
- Dip towards sea: less stable, joints exposed
- Dip towards land: more stable
78
How does Geomorphology affect cliff profile feature development?
shape of the coastline e.g. refraction
79
What are inputs into coastal systems?
- Energy from waves, wind, tides and sea currents
- Sediment
- Geology of the coastline
- Sea level change
