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Physical Geography: Coasts > EQ2 > Flashcards

EQ2 Flashcards

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1
Q

what does sediment move along in

A

sediment cells

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2
Q

how many major sediment cells are in england and wales

A

11

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3
Q

TRUE or FALSE can major sediment cells be divided further

A

TRUE
Each major cell can be divided into a number of sub cells

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4
Q

what are each sediment cell operating within

A

Each cell operates between physical barriers that prevent sediment from moving any further along the coast

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5
Q

what is interlinked within sub cells

A

erosional processes
transport processes
deposition

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6
Q

can some coastal features operate as sinks, source and transfer zones

A

NO
ONLY some coastal features operate as SINKS AND SOURCES
- depends on whether the dominant processes are erosion or deposition at a given time

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7
Q

what is a source
give examples

A

a place where sediment is generated
such as cliffs, sand dunes or offshore bars and even river systems

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8
Q

what is a transfer zone

A

places where sediment is moving along the shore
via longshore drift and offshore current

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9
Q

what is a sink

A

locations where the dominant process is deposition
-depositional landforms are created such as spits and offshore bars

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10
Q

define sediment budget

A

The amount of sediment available within a sediment cell

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11
Q

what state does a system act in under natural conditions

A

DYNAMIC EQUILIBRIUM

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12
Q

TRUE or FALSE can dynamic equilibrium be disrupted

A

TRUE
dynamic equilibrium can be disrupted by storms leading to increased erosion

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13
Q

what do negative feedback mechanisms do to the dynamic equilibrium

A

Negative feedback mechanisms help maintain the balance by pushing the system back towards equilibrium.

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14
Q

what do positive feedback mechanisms do to dynamic equilibrium

A

Positive feedback mechanism is where one change has led to another change which leads to disequilibrium in the coastal system.

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15
Q

does positive feedback lead to equilibrium or disequilibrium

A

DISEQUILIBRIUM

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16
Q

does negative feedback lead to equilibrium or disequilibrium

A

EQUILIBRIUM

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17
Q

what are 2 factors that impact the state of dynamic equilibrium

A

Coastal management
Global warming

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18
Q

how does coastal management impact the state of dynamic equilibrium

A

can decrease erosion leading to less sediment input

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19
Q

how does global warming impact the state of dynamic equilibrium

A

Increased storms due to global warming could lead to long term erosion of sand dunes with no chance to recover between storm events.

Rising sea level could increase erosion of spits and estuaries, removing sediment faster than it can be replaced.

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20
Q

what do waves directly influence which in return shapes the….?

A

erosion, transportation and deposition,

so they shape the coastline.

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21
Q

how are waves caused

A

by friction between wind and water

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22
Q

what is wave size dependant on

A

-The strength of the wind
-The duration the wind blows for
-Wave fetch - the uninterrupted distance across water over which the wind blows
-Water depth - see waves as they approach a shoreline

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23
Q

how are waves affected when approaching the shoreline

A

the water shallows and the shape of the waves changes significantly.

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24
Q

what happens when the internal orbital motion of water touches the sea bed

A

friction occurs and this slows down the wave

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25
Q

what happens to the wave length and wave height as it approaches the shore

A

wavelength = decreases
wave height = increases
makes waves look like they bunch together

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26
Q

why do waves break in shallow water

A

because the crest of the wave begins to move forward much faster than the wave trough due to friction with the sea bed.

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27
Q

what causes a wave to break

A

the wave crest outruns the trough and the wave topples forward = breaks.

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28
Q

two types of waves

A

constructive
destructive

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29
Q

what is the wave height, energy and frequency of CONSTRUCTIVE waves

A

LOW
LOW
LOW

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30
Q

what is the wave height, energy and frequency of DESTRUCTIVE waves

A

HIGH
HIGH
HIGH

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31
Q

do destructive waves have a greater swash or backwash

A

BACKWASH > swash
beach loss

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32
Q

do constructive waves have a greater swash or backwash

A

SWASH > backwash
beach gain

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33
Q

what is beach morphology

A

the shape of the beach, including its width and slope and features. It also includes the type of sediment found at different beaches location

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34
Q

what creates different beach profiles

A

the seasonal changes in wave type

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35
Q

what wave type create winter beach profiles

A

destructive waves – sediment dragged offshore

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36
Q

what wave type create summer beach profiles

A

constructive waves - sediment dragged onshore

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37
Q

what factors create winter beach profiles

A

-Berms are eroded by plunging waves

-Strong backwash transports sediment offshore(depositing is at offshore bars)

-Sometimes the backwash exerts a current known as a rip/undertow - dragging sediment back as the next wave arrives over the top

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38
Q

what factors create a summer beach profile

A

-Constructive waves are less frequent wave energy dissipates and deposits over a wide area (weakening backswash)

-The swash of constructive wave deposits larger material at the top of the beach creates a berm

-As a berm builds up the backswash becomes weaker. It only has enough energy to move smaller material so the beach materials are smaller the closer you are to the shoreline

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39
Q

what are examples of changes in beach profiles

A

-sediment supply is reduced from rivers due to dams
-coastal management has effect on processes further along the coast
-global warming makes the UK stormier on average, more destructive waves, making winter beach profiles more common

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40
Q

what are the 4 ways sediment is transported

A

solution
saltation
suspension
traction

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41
Q

what is longshore drift

A

the movement of materials along a coast by wave action which approach at an angle to the shore but recede directly away from it

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42
Q

what can affect longshore drift

A

tides and currents

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43
Q

what are tides

A

changes in the level of seas and oceans – caused by the gravitational pull of the moon

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44
Q

what is tidal range

A

The relative difference in height between the high and low tides

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45
Q

what does a high tidal range mean

A

powerful tidal currents, as tides rise and fall

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46
Q

what are examples of depositional landforms

A

Spits
Beaches
Offshore bars
Barrier beaches
Tombolos
Cuspate forelands

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47
Q

what is a spit

A

A spit is a long narrow feature, made of sand or shingle, which extends from the land into the sea

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48
Q

how does longshore drift influence the spits formation

A

Sand or shingle is moved along the coast by longshore drift, but if the coastline suddenly changes direction (e.g because of a river estuary) sediment will begin to build up across the estuary mouth and the spit will start to form

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49
Q

what causes a recurved spit

A

end of the spit will begin to curve round as wave refraction carries material round into the more sheltered water behind the spit

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50
Q

where are beaches commonly found

A

Beaches are commonly found in bays.

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51
Q

what sort of environment does wave refraction create in beaches

A

Wave refraction creates a low-energy environment, which then leads to deposition

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52
Q

what are the two different aligned beaches

A

drift aligned beach
swash-aligned beach

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53
Q

what are offshore bars

A

are submerged ridges of sand - created by waves offshore from the coast

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54
Q

how do destructive waves create offshore bars

A

Destructive waves erode sand from the beach with their strong backwash and deposit it offshore as bars

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55
Q

what is a barrier beach

A

Where a beach or spit extends across a bay to join two headlands, it forms a barrier beach

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56
Q

is it true barrier beaches can form lagoons?

A

YES
Barrier beaches and bars can also trap water behind them to form lagoons.

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57
Q

what is a separated barrier beach called

A

barrier island

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58
Q

what is a tombolo

A

a beach that has formed between a small island and the mainland

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59
Q

how does deposition occur to form the tombolo

A

Deposition occurs where waves lose their energy and the tombolo begins to build up

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60
Q

what is a cuspate foreland

A

triangular-shaped headland that extends out from the main coastline.

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61
Q

how does a cuspate foreland form

A

a coast is exposed to longshore drift from opposite directions. Sediment is deposited at the point where the two meet, which forms a natural triangular shape as it builds up.

62
Q

how does a cuspate foreland stabilise itself

A

vegetation begins to grow on the deposited sediment, it helps to stabilise the landform and protect it from storms that could erode it.

63
Q

how does vegetation stabilise depositional landscapes

A

Depositional landforms are made of unconsolidated sediment and so are vulnerable to change.
Plant succession – salt marshes and sand dunes – bind the loose sediment together and encourage further deposition of sediment.

64
Q

how do depositional landforms become vunerable

A

Depositional landforms are vulnerable when their vegetation is damaged through overgrazing or trampling from tourism and leisure activities.

65
Q

what are the 4 coastal erosional processes

A

hydraulic action
abrasion
attrition
solution

66
Q

explain hydraulic actions process

A

air trapped in cracks and fissures is compressed by the waves force crashing against cliff
The pressure forces cracks open, then more air can then be trapped and greater force is experienced during compression cycles
This process dislodges rock on the cliff face

67
Q

hydraulic actions influence on lithology

A

heavily jointed sedimentary rocks are vulnerable
hydraulic action on the cooling cracks of igneous rock may be the only working erosive process

68
Q

explain abrasion as a process

A

sediment is picked up by waves and is thrown against a cliff
it acts as a chisel gradually wearing down the cliff face by removing small rock particles

69
Q

abrasions influence on lithology

A

for abrasion to be effective loose sediment has to be available.
softer sedimentary rocks are more vulnerable than igneous rocks

70
Q

explain attrition as a process

A

the process acts on already eroded sediment
as sediment is moved by waves collision occurs chipping away fragments of sediment
Overtime sediment becomes smaller and rounder

71
Q

attritions influence on lithology

A

softer rocks are rapidly reduced in size by attrition

72
Q

explain corrosion as a process

A

carbonate rocks are vulnerable to solution by rainwater, spray from seawater

73
Q

corrosions influence of lithology

A

mainly affects limestone, which is vulnerable to solution by weak acids

74
Q

what influences the rate and type of erosion

A

the size and type of waves that reach the coastline

75
Q

when does most erosion occur

A

during winter storms

76
Q

small scale lithology are eroded more..?.. which results in the formation of..?…

A

quickly

different landforms

76
Q

when destructive waves are at their largest and most powerful what erosional processes are going to become more powerful

A

abrasion and hydraulic action

77
Q

TRUE or FALSE bands of more resistant rock erode more quickly

A

FALSE
they erode slowly

78
Q

what is differential erosion

A

the selective erosion of areas of weakness as opposed to more resistant areas

79
Q

what does differential erosion give you

A

caves, arches, stacks and stumps

80
Q

what do areas of resistant rock generally form and what do areas of weaker rock form

A

Resistant rock: headlands and cliffs
Weaker rock: Bays and inlets

81
Q

how does rock type influence erosion

A

erosion is faster when the rocks on the coastline are weaker

82
Q

what are the 9 landforms of coastal erosion

A

headlands
bays
wave cut platform
caves
arches
stack
stump
blowhole
cliffs

83
Q

when waves approach a headland does the water depth increase or decrease

A

DECREASES

84
Q

when waves approach a bay does the water depth increase or decrease

A

INCREASE

85
Q

when waves approach a headland the waves get steeper and the velocity..?.. as they become closer together however the erosional power…?…

A

velocity REDUCES
erosional power INCREASES

86
Q

when waves enter a bay they don’t …?… the velocity and the waves are low and less steep which allows …?… to take place

A

velocity isnt lost as rapidly
deposition rather than erosion takes place

87
Q

how are wave cut notches formed

A

-waves break against the foot of the cliff
-erosion is concentrated close to the high tide line
-creating wave cut notch which begins to undercut the cliff

88
Q

what occurs when the wave cut notch gets bigger

A

the rock above becomes unstable and eventually the upper part of the cliff collapses

89
Q

what causes the wave cut notch to migrate inland

A

erosional processes repeating causing the cliff to retreat

90
Q

what reduces the rate of erosion on the wave cut platform

A

the platforms have grown due to continuous erosion by their width means the wave breaks earlier and its energy is dissipated before it reaches the cliff

91
Q

when joints and faults are eroded this can create

A. spit B. cave C. tombolo

A

B. CAVE

92
Q

when caves are created the overlying rock may collapse forming a

A

BLOWHOLE

93
Q

when caves erode through a headland what forms

A

ARCH

94
Q

what causes the arch to enlarge

A

erosion and weathering

95
Q

when the top of the arch becomes unstable what forms

A

A STACK

96
Q

when a stack is eroded by the sea what does it collapse into

A

a STUMP

97
Q

how do cliffs maintain their steep profile

A

constant wave action and erosion at the cliffs base ensure it remains steep as it retreats inland

98
Q

what are sub aerial processes

A

Weathering
Mass movement

99
Q

what are the 3 types of weathering

A

mechanical
biological
chemical

100
Q

define weathering

A

is the gradual breakdown of rock, in situ (in position) at or close to the ground surface

101
Q

define mass movement

A

is the movement of weathered material down slope, as a result of gravity

102
Q

what 2 factors have influence over weathering experienced

A

precipitation
temperature

103
Q

where does mechanical weathering dominate

A

cold climates

104
Q

where does chemical weathering dominate

A

hot wet conditions

105
Q

what also has major influence on the type of weathering that takes place

A

the lithology of coastal rocks
as some rocks are more prone to certain types of weathering than others

106
Q

define mechanical weathering

A

breaks down rock due to the exertion of a physical force

107
Q

what are the 3 mechanical weathering processes

A

freeze thaw
salt crystallisation
wetting and drying

108
Q

explain freeze thaw as a process

A

water expands in volume when freezing, exerting a force within cracks and fissures, repeated cycles forces rocks to open and loosen rocks

109
Q

what rocks are vulnerable to freeze thaw weathering

A

Any rocks with cracks or fissures, especially rocks away from salt spray, as salt spray reduces the effect of freeze thaw

110
Q

explain salt crystallisation as a process

A

The growth of salt crystals in cracks and pore spaces, can exert a breaking force

111
Q

what rocks are vulnerable to salt crystallisation

A

Porous, fractured rocks e.g sandstone

Its effect is greater in not dry climates where evaporation occurs

112
Q

explain wetting and drying as a process

A

Frequent cycles of wetting and drying of coastal rocks

113
Q

what rocks are vulnerable to wetting and drying

A

Rocks rich in clay (shale) expands when wet and contract as they dry

114
Q

define biological weathering

A

often speeds up mechanical or chemical weathering through the action of plants, bacteria or animals

115
Q

what are the 2 biological weathering processes

A

plant roots
rock boring

116
Q

explain plant roots as a process

A

Thin plant roots grow in cracks in the cliff face, the cracks then widen as roots become thicker, which breaks up the rock

117
Q

what rocks are vulnerable to rock boring

A

Sedimentary rocks especially carbonate rocks (limestone) located in intertidal zones

117
Q

what rocks are vulnerable to plant roots

A

Vegetated cliff tops, contributing to rock fall

118
Q

explain rock boring as a process

A

Many species of clams and molluscs bore into rock and may also secrete chemicals that dissolve rocks

119
Q

define chemical weathering

A

involves a chemical reaction and the generation of new chemical compounds

120
Q

what are the 3 chemical weathering processes

A

hydrolysis
oxidation
carbonation

121
Q

explain carbonation as a chemical weathering process

A

Where slow dissolution of limestone due to rainfall (PH 5.6, weak carbonic acid) producing calcium bicarbonate in solution

122
Q

examples of vulnerable rocks to carbonation

A

Limestone and other carbonate rocks

123
Q

explain hydrolysis as a chemical weathering process

A

The breakdown of minerals to form new clay minerals due to the effect of water and dissolved CO2

124
Q

examples of vulnerable rocks to hydrolysis

A

Igneous and metamorphic rocks containing silicate minerals

125
Q

explain oxidation as a chemical weathering process

A

the addition of oxygen to minerals, especially iron compounds which produces iron oxides and increases volume contributing to mechanical breakdown

126
Q

example of vulnerable rocks to oxidation

A

Sandstones, siltstones and shales often contain iron compounds that can be oxidised

127
Q

how does weathering increase mass movement

A

Weathering weakens rock, making them more vulnerable to erosion or mass movement processes

128
Q

what is the main sub aerial process that causes cliff collapse

A

On some coastlines the dominant cause of cliff collapse is mass movement

129
Q

how can mass movement be classified

A

how rapid the movement is
The type of material

130
Q

the resultant movement is dependant on these 4 factors

A

The angle of the slope/cliff
The rock type and its structure
The vegetation cover
How wet the ground is

131
Q

TRUE OR FALSE soil creep is the fastest form of mass movement

A

FALSE
its the slowest

132
Q

what are the 3 mass movement FLOWS

A

solifluction
soil creep
earth/mud flows

133
Q

is soil creep a continuous process

A

almost continuous process
It’s a very slow downhill movement of individual soil particles

134
Q

where does solifluction occur mainly

A

tundra areas where the ground is frozen

135
Q

explain solifluction as a process

A

When the top layer of soil thaws for summer – but the layer below is frozen (permafrost) – the surface layer becomes saturated and flows over the frozen subsoil and rock

136
Q

an increase in …?… reduces friction causing …?… to flow over underlying bedrock

A

the amount of water due to increased precipitation

earth and mud

137
Q

what is the difference between a mass movement SLIDE and a mass movement FLOW

A

In a slide the material remains intact (it moves ‘en masse’).
In a flow the material becomes jumbled up.

138
Q

what are the 3 mass movement SLIDES

A

rock fall
rock slides
slumping

139
Q

when are rock falls most likely to occur

A

Rock falls are most likely to occur when strong, jointed and steep rock faces/cliffs are exposed to mechanical weathering

140
Q

Rocks falls occur on slopes that are..

A. slopes that are10 degrees and below
B. slopes that are 20-30 degrees
C. slopes over 40 degrees

A

C. slopes over 40 degrees

141
Q

what happens when the rock falls in the mass movement slide rock fall

A

falls vertically causing scree/talus, at the foot of the slope/cliff

142
Q

what rocks are vulnerable to rock slides

A

Rocks that are jointed, or have bedding planes roughly parallel to the slope or cliff surface

143
Q

an increased amount of ..?.. can reduce friction causing …?…

A

And increase in the amount of WATER can reduce friction - causing SLIDING

144
Q

what conditions does slumping occur

A

SATURATED CONDITIONS

145
Q

what type of slopes does slumping occur

A

Slumps occur on moderate to steep slopes

146
Q

what type of material leads to slumping

A

Common where softer materials (clay or sands) overlie more – resistant or impermeable rock, such as limestone or granite

147
Q

what does slumping lead to

A

Slumping causes rotational scars
Repeated slumping creates a terraced cliff profile

148
Q

what are the 3 landforms created by mass movement

A

Rotational scars
talus/scree slope
Terraced cliff profile

Physical Geography: Coasts (5 decks)

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