Coasts Systems and Processes Flashcards
(53 cards)
1
Q
Inputs in Coastal Systems
A
- Precipitation
- Sediment carried by rivers/waves
- Waves
- Tides
- Currents
- Sun
- Wind
- Pollution
- Weathering
2
Q
Stores in Coastal Systems
A
- Spits
- Tombolos
- Bars
- Beaches
- Landforms
3
Q
Outputs in Coastal Systems
A
- Deposition
- Eroded material taken out to sea
- Ocean Currents
- Evaporation
4
Q
Transfers in Coastal Systems
A
- Transportation Processes
- Longshore Drift
- Mass Movement
- Wind Blown Sand
5
Q
Energy in Coastal Systems
A
- Wind Strength
- Wind Direction
- Tides
- Sediment Supply
- Fluvial processes
6
Q
Constructive Waves
A
- Limited Energy
- Swash > Backwash
- Calm Weather
- Water around 1m high
- Builds up the beach
- Less Frequent at around 6-9 per minute
7
Q
Destructive Waves
A
- More Energy
- Backwash > Swash
- Stormy Conditions
- Water around 5-6m high
- Erodes the Beach
- More Frequent at around 11-15 per minute
8
Q
High Energy Coastline
A
- Rocky Coastline
- Stretches of Atlantic-facing coast, where waves are strong for much of the year
- Rates of Erosion>Rates of Deposition
- Erosional Landforms e.g. Headlands, Cliffs, Wave-Cut Platforms
9
Q
Low Energy Coastline
A
- Sandy and Estuarine Coastline
- Stretches of coast where waves are less powerful
- Rate of Deposition>Rates of Erosion
- Depositional Landforms e.g. beaches, Spits, Tombolos
10
Q
How are Waves Formed
A
As air moves over the water, frictional drag disturbs the surface and forms ripples or waves. In the open sea, there is little horizontal movement of water. Instead, there is orbital motion of water particles. Close to the coast, horizontal movement of water does occur as waves are driven onshore to break onto the beach.
11
Q
Sediment Cell Definition
A
A stretch of coastline, usually bordered by two prominent headlands, where the movement of sediment is more or less contained
12
Q
Sources of Energy in Coastal Environments
A
- Wind
- Waves
- Currents
- Tides
13
Q
Factors Affecting Wave Energy
A
- Strength of the Wind (determined by the pressure gradient)
- Duration of the Wind
- Fetch
14
Q
Tide Definition
A
Changes in the water level of the seas and oceans caused by the gravitational pull of the moon, and to a lesser extent the Sun
15
Q
Sources of Sediment
A
- Rivers
- Cliff Erosion
- Longshore Drift
- Wind
- Glaciers
- Offshore
16
Q
Negative feedback example of wave refraction:
A
- Variations in rock strength leads to the formation of headlands and bays
- Causes wave refraction which, encourages the erosion of headlands and the deposition in bays- working against the erosion of the softer rock that formed in the bay originally
- If conditions remained stable for a long period of time, equilibrium would be reached
17
Q
Inputs of a Sediment Cell
A
- Rivers
- Coastal Erosion
- Offshore Bars and Banks
18
Q
Transfers of a Sediment Cell:
A
- Longshore Drift
- Ocean Currents
19
Q
What is a Sediment Budget?
A
Material in a sediment cell can be considered in the form of a sediment budget (where losses and gains occur)
20
Q
Losses from a Sediment Budget
A
Deposition in sediment sinks
21
Q
Gains from a Sediment Budget
A
Coastal erosion or sediment brought into the system by rivers or offshore sources
22
Q
Key Geomorphological Processes
A
- Weathering
- Mass Movement
- Erosion
- Transportation
- Deposition
23
Q
Types of Weathering
A
- Mechanical
- Biological
- Chemical
24
Q
What is Mass Movement
A
The downhill movement of weathered material due to the force of gravity
25
Examples of Mass Movement
- Landslides- occur on cliffs made of softer rick or deposition
- Rockfalls- cliffs under-cut by the sea, or on slopes affected by mechanical weathering like frost action
- Mudflows- heavy rain can cause large quantities of fine material to fall downwards
- Rotational slumping
- Soil creep
26
Examples of Transportation
- Solution
- Suspension
- Saltation
- Traction
- Longshore drift
27
What is Hydraulic Action?
Air may become trapped in joints and cracks on a cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion.
28
What is Wave Quarrying?
Destructive waves and storm like conditions plunge heavy hydraulic pressure on cliff faces. The vibration off the cliff can dislodge bits of rock and undercuts the base of the cliff.
29
What is Corrasion/Abrasion?
Bits of rock and sediment transported by the waves smash and grind against rocks and cliffs, breaking bits off and smoothing surfaces.
30
What is Solution/Corrosion?
A mixture of solute and solvent- rocks dissolved into sea water due to different pH.
31
What is Cavitation?
As waves recede, the compressed air expands violently, again exerting pressure on the rock and causing pieces to break off.
32
What is Attrition?
Waves smash rocks and pebbles on the shore into each other, and they break and become smoother.
33
What is Traction?
Large particles like boulders are pushed along the river bed by the force of the water.
34
What is Suspension?
Small particles like silt and clay are carried along by the water.
35
What is Longshore/Littoral Drift?
Where waves come in at an angle to the shore line, and retreat perpendicularly.
36
What is Deposition?
The process by which sediment settles out of the water or wind carrying it.
37
What is Aeolian Deposition?
The entrainment, transport and deposition of sediment by wind.
38
What is Surface Creep?
A process similar to traction, where wind rolls or slides sand grains along the surface.
39
What is Saltation?
Where the wind is strong enough to temporarily lift the grains into the airflow to heights of up to 1m from distances of 20-30m.
40
What is Sub-aerial Weathering?
Land-based processes which alter the shape of the coastline.
41
What is Lithology?
- Refers to the characteristics of rocks, especially resistance and permeability
- May lead to differential rates of erosion
42
What is a Concordant Coastline?
When rocks lie parallel to the coastline (this is where you get one layer of hard rock preventing waves access to soft rock layer behind)
Only allows water to break through in a few places.
43
What is a Discordant Coastline?
When rocks run at right angles to the coastline. This is where headlands and bays form.
Allows the sea to penetrate along the weaker clays + gravels and produces large bays (e.g. Swanage Bay).
44
What is a Rock Dip?
Steepest cliffs tend to form in rocks that have horizontal strata or which dip gently inland.
45
What are the six factors which make up a Rock's Lithology?
- Strata
- Bedding Planes
- Joints
- Folds
- Faults
- Dip
46
Difference between a Joint and a Bedding Plane?
Joint:
- Vertical fractures
Bedding plane:
- Horizontal breaks in strata
47
What is a Rock Fold?
Formed by pressure during tectonic activity, makes rocks bundle and crumple.
E.g. Lulworth crumple
48
Example of Mechanical/ Physical Weathering
- Nature of the climate, in latitudes where temperature fluctuates above + below freezing
- Freeze thaw weathering= pressure release
49
Example of Biological Weathering
- Breakdown of rocks by the action of vegetation + coastal organisms
- Also occurs by animals burrowing in cliffs
50
Examples of Chemical Weathering
- Oxidation
- Hydration
- Hydrolysis
- Carbonation
51
What is Sub-aerial Weathering?
The gradual break down of rock by agents such as ice, salt, plant roots and acids.
52
How do Sub-aerial Processes affect the rate of Erosion?
- Weathering and mass movement create piles of debris that are easily eroded so increased rate of erosion
- Weathering will weaken the rock so erosion will have a greater impact
53
How does Sub-aerial Weathering affect the Development of Coastal Landscapes?
May result in:
- Cliff Retreat
- Wave-cut Platforms
- Headlands + Bays
