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A-Level Geography > Coasts > Flashcards

Coasts Flashcards

1
Q

Are coasts an open or a closed system

A

Open system

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2
Q

Inputs

A

Material or energy moving into the system to the outside. Eg: Precipitation and wind

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3
Q

Output

A

Material or energy moving from the system to the outside. Eg: Ocean currents, rip tides, sediment transfer and evaporation

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4
Q

Energy

A

Power or driving force. Eg: Energy associated with flowing water, the effects of gravity on cliffs and moving air

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5
Q

Stores/Components

A

The individual elements or parts of a system. Eg: beach, sand dunes, nearshore sediment

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6
Q

Flows/transfers

A

The links between the components. Eg: Wind-blown sand, mass movement processes, longshore drift

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7
Q

Positive feedback

A

Where a flow/transfer leads to increase or growth. Eg: coastal management leading to an increase in erosion elsewhere

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8
Q

Negative feedback

A

Where a flow/transfer leads to a decrease or decline

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9
Q

Dynamic equilibrium

A

This represents a state of balance within a constantly changing system

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10
Q

Wave length

A

The difference between the two wave crests

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11
Q

Wave crest

A

The top of the wave

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12
Q

Wave trough

A

The bottom of the wave

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13
Q

What happens to a wave when it reaches the beach

A

It starts to create an elliptical wave orbit (the wave motion becomes more like an oval)

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14
Q

Features of a constructive wave (4)

A

-Low waves with a long wavelength
-Strong swash, weak backswash
-Builds the beach
-Associated with a gentle beach profile but will make the beach steeper over time

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15
Q

Features of a destructive wave (4)

A

-High waves with short wavelengths
-Weak swash, strong backwash
-Beach loss (destructive)
-Usually associated with a steeper beach profile but will flatten the beach over time

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16
Q

How can constructive and destructive waves be an example of a negative feedback loop?

A

Constructive waves make a flatter beach steeper, which creates more destructive waves which flatten the beach

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17
Q

Tides

A

Tides are changes in water levels of seas and oceans caused by the gravitational pull of the moon

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18
Q

Rip currents

A

Strong localised underwater currents that pull things back out to the sea when things are caught in them

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19
Q

Wave refraction

A

The distortion of wave fronts as they approach an indented shoreline. This causes wave energy to be concentrated on headlands and dissipated at bays

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20
Q

What are the sources of sediment for a sediment cell (6)

A

-Rivers
-Cliff erosion
-Longshore drift
-Wind (wind blown sediment)
-Glaciers
-Offshore (sediment being transferred from offshore by waves

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21
Q

Sediment cells

A

A stretch of coastline, usually bordered by two prominent headlands, where movement of sediment is more or less contained

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22
Q

Sediment budget

A

The losses and gains of sediment in a sediment cell

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23
Q

Fill in the blank: The sediment budget aims to achieve a state of __________________.

A

Dynamic equilibrium

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24
Q

Weathering

A

The breakdown or disintegration of rocks in situ (in place)

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25
What are the three types of weathering
-Mechanical weathering -Biological weathering -Chemical weathering
26
What are the different types of mechanical weathering (3)
-Frost shattering (freeze-thaw) -Salt crystallisation -Wetting and drying
27
Frost shattering (freeze-thaw) weathering
When water enters a crack or joint in the rock and then freezes. This causes the water to expand by 10% which exerts pressure on the rock and forces the crack to widen.
28
Salt crystallisation
When salt water evaporates, it leaves salt crystals behind, which can grow over time and exert stress on the rock
29
Wetting and drying
Rocks rich in clay expand when they get wet and contract when they are dry, causing cracks to form
30
Biological weathering
The break down of rocks by organic activity
31
How can biological weathering occur (4)
-Thin plant roots grow into cracks in the rocks, and as the roots grow the cracks widen and break -Water running through decaying vegetation becomes acidic, which leads to chemical weathering -Birds and animals dig burrows into cliffs -Marine organisms burrowing into rocks or secreting acid
32
Chemical weathering
A chemical reaction that allows for rocks to be easily eroded
33
Three types of chemical weathering
-Carbonation -Oxidation -Solution
34
Carbonation
Rainwater absorbs carbon dioxide from the air to form weak carbonic acid. This reacts with calcium carbonate in rocks (such as limestone and chalk) to form calcium bicarbonate which is easily disolved
35
Oxidation
The reaction of minerals with oxygen to form a rusty red powder leaving rocks more vulnerable to weathering
36
Solution
The dissolving of rock minerals
37
Mass movement
The downhill movement of material under the influence of gravity
38
What are the 5 types of mass movement
-Soil creep -Mudflows -Landslide -Rockfall -Landslip or slump
39
Soil creep
An extremely slow form of movement of individual soil particles down a hill. This usually happens as a response to wetting and freezing
40
Mudflows
Earth and mud flowing downhill, usually after heavy rainfall and over weak bedrocks such as clay
41
Landslide
A block of rock moving rapidly downhill, that remains largely intact
42
Rockfall
The sudden collapse or break away of individual rock fragments at a cliff face
43
landslip/slump
They are a curved plane of land where permeable rock lies of impermeable rock, causing the permeable rock on top to slip
44
Name the five types of coastal erosion
-Hydraulic action -Abrasion -Corrasion -Solution -Wave Quarrying
45
Hydraulic action
When wave traps and compresses air in cracks in the cliff face and then retreats, it causes the compressed air to expand
46
Wave quarrying
Waves scooping out materials such as gravel or sand, similar to a digger
47
Corrasion
When bits of sediment get hurled at a cliff by waves
48
Abrasion
When sediment is dragged up and down the shoreline, eroding and smoothing rocky surfaces
49
Solution
Weak acids in salt water dissolve
50
What are the 4 coastal transportation methods
-Traction -Saltation -Solution -Suspension
51
Traction
The rolling of sediment along the sea bed
52
Saltation
Sediment is bounced along the sea bed
53
Suspension
Sediment is picked up and carried with the flow of the water
54
Solution
Sediment is dissolved in water
55
What type of rock is required for steep cliffs
Hard rock
56
What type of rock creates gentle cliffs
Softer rock
57
Coastal morphology
The underlying geology, rock type and physical composition of a coastline
58
What are the 6 characteristics that make up the coastal morphology
-Strata -Bedding planes -Joints -Folds -Faults -Dips
59
Strata (coastal morphology)
Layers of rock
60
Bedding planes (coastal morphology)
Horizontal, natural breaks in the strata, caused by gaps in time during periods of rock formation
61
Joints (coastal morphology)
Vertical fractures caused either by contractions as sediments dry out, or by earth movements during uplift
62
Folds (coastal morphology)
Formed by pressure during tectonic activity, which makes rocks buckle and crumple
63
Faults (coastal morphology)
Formed when the stress or pressure to which a rock is subjected exceeds it's internal strength. The faults then slip or move along fault planes
64
Dip (coastal morphology)
Refers to the angle at which rock strata lie
65
Geo
An inlet or gully or a narrow deep cleft in the face of a cliff
66
How do Geos form?
When there is a layer of soft rock that is surrounded by hard rock (on a discordant coastline) then a geo can be formed as the soft rock gets eroded away but the hard rock doesn't
67
Discordant coastlines
When you have layers of hard rock and soft rock that are perpendicular to the coastline
68
Concordant coastlines
When you have layers of hard and soft rock that are parallel to coastline
69
What is a swash aligned beach
Low energy energy environments (because of wave refraction), where most of the beach is made up from sediment brought in by the waves
70
What is a drift aligned beach
Where the waves approach the beach at an angle. Longshore drift will move sediment along the beach often forming a spit
71
How is a spit formed
When longshore drift move sediment along a coastline and there is a sudden change in the coasts direction (The mouth of a river) then the sediment will extend out into the sea making a spit. The end of the spit will then begin to curve back towards the coast
72
Tombolo
A beach or ride of sand that has formed between a small island and the mainland
73
Offshore bars
Submerged ridges of sand or coarse sediment created by waves offshore from the coast. They absorb wave energy and reduce the impact of erosion on the coastline
74
Barrier beaches (bars)
When a beach or a spit extends across a bay to form two headlands it forms a barrier beach or a bar (Slapton Leigh)
75
What are the 5 stages of sand dunes
-Embryo -Fore dunes -Yellow dunes -Grey dunes -Dune slack -Woodland (mature dunes)
76
Humus
Organic material that forms in soil when plant or animal matter decays
77
Explain the process of sand dune formation
Embryo dunes develop first as sand and shingle gets built up on a beach. Then the fore dunes are created, and held together with sea rocket and couch grass. Then as the plants die and the humus of the sand dunes increase, yellow dunes are formed and held together by marram grass. The dunes now start to darken and turn into grey dunes with low shrubs and brambles. Then dune slacks are formed where there is a depression that is close to the level of the sea, so water often fill up the hole. The behind it you have the mature dunes r woodland with gorse bushes and oak and pine trees.
78
What happens to the soil PH of sand dunes
Embryo - 8.5 Yellow dunes - 7.5 Grey dunes - 6.5 Woodlands (mature dunes) - 4.5
79
What happens to the % humus in sand dunes
Fore dunes - 1% Yellow dunes - 2.5% Grey dunes - 10% Woodland (mature dunes) - 40%+
80
Saltmarshes
Areas of flat,silty sediment that accumulate around estuaries and lagoons
81
The three conditions for salt marshes
-In sheltered areas where deposition occurs -Where salt and freshwater meet -Where there are no strong tides or currents to prevent sediment deposition and accumulation
82
Eustatic change
When the sea level itself rises or falls
83
Isostatic change
When the land rises or falls, relative to the sea
84
Where does eustatic change occur
Globally, sea levels falling or rising
85
Where does isostatic change occur
Locally, areas of land sink or rise because of lost weight from ice in glacial periods
86
What part of the UK is sinking and which is rising?
-Scotland is rising -South is sinking
86
Emergent coastal landforms (1)
Raised beaches
87
How are raised beaches formed
When wave-cut platforms rise above the sea level, raised beaches are formed
88
Submergent coastal landforms (2)
-Rias -Fjords
89
How are rias formed
When low lying valleys become flooded due to higher sea levels
90
How are Fjords formed
When a glacier runs melts it runs out to see making a wide and deep U-shaped valley. When this floods a Fjord is formed
91
Fill in the gap: The _____________ is relatively shallow in fjords because of all the glacial sediment deposited there
Mouth of the river
92
What is the dalmatian coastline an example of?
It is a submergent coastline where a series of flooded valleys has caused a ria to be created
93
Thermal expansion
When water heats up it expands
94
Name the 6 different types of hard engineering strategies for coastal management
-Groynes -Gabions -Sea walls -Rock armour -Revetments -Offshore breakwater
95
Groynes
Timber structures on beaches, built at right angles to the coast
96
Gabions
Metal baskets filled with rocks that absorb the energy from the waves

A-Level Geography (6 decks)

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