1
Q
Define:
- littoral zone
- offshore
- nearshore
- backshore
A
- lz: area of shoreline where land is subject to wave action
- o: The area beyond the influence of breaking waves
- n: The intertidal area within the breaker zone, it is used for trade, fishing and leisure
- b: The area above high tide and the influence of normal wave patterns; may have a storm beach further up
2
Q
Why can the littoral zone be described as dynamic?
A
it is constantly changing due to the forces acting upon it and human management and influence
3
Q
What are the 5 ways of classifying coasts?
A
- Primary v Secondary coast
- Emergent or Submergent coast
- Tidal range:mirco, miso and macro
- Low energy v High energy
4
Q
What is a primary coast and example?
A
a coast that is dominated by subaerial processes - eg Nile Delta
5
Q
What is a secondary coast and an example?
A
a coast that is dominated by marine processes - West Cornwall, Holderness
6
Q
- What are the reasons for a coast being emergent + eg?
A
- glacier melt reduces the weight of the land causing it to rise
- tectonic uplift
- West Scotland
7
Q
example of a submergent coastline?
A
west norway (fjords)
8
Q
tidal ranges?
micro, miso, macro
A
- micro: 0-2 metres
- miso: 2-4 m
- macro: >4 m
9
Q
What is a high energy coastline + eg?
A
- an exposed coast that faces prevailing winds -> long fetch and powerful destructive waves
- Holderness coastline and West Scotland
10
Q
what landforms are likely to occur at a high energy coastline?
A
caves, arches, stacks, stumps
11
Q
what is a low energy coastline + eg?
A
- a sheltered coast with limited fetch and a low wind speed -> small constructive waves
- Cardigan Bay, Wales
12
Q
what landforms are likely to occur at a low energy coastline?
A
spits, marshes, bars, beaches
13
Q
characteristics of a rocky beach?
A
- Main Processes present: erosion, weathering and mass movement
- Beach profile: steep to vertical beach
- Geology: formed of resistant rocks
- Waves/Energy: high energy environment - destructive
14
Q
characteristics of a coastal plain?
A
- processes: deposition and transportation (accretion)
- Beach profile: gentle and flat beach profile
- Waves/Energy: low energy environment - constructive waves
15
Q
landforms on a coastal plain?
A
beaches, spits, bars, marshes, dunes
16
Q
what is a concordant coastline + eg?
A
- rock strata runs parallel to coast
- Lulworth Cove, Dorset
17
Q
What is a discordant coastline + eg?
A
- Rock strata intersects coasts at a right angle
- Studland Bay -> Durlston Head, Swanage Bay, Dorset
18
Q
what is formed on a discordant coastline?
A
headlands and bays
19
Q
how are headlands and bays formed?
A
- less resistant rocks eroded at a faster rate -> form bays
- resistant rocks erode slower -> headlands
- once the headlands are formed they are more likely to erode than bays
20
Q
What is wave refraction?
A
the bending of waves as they approach a coastline and concentrate waves into headlands - may form a tombola as area behind is low energy and depositional
21
Q
headlands and bays: rock type at Swanage Bay, Dorset vs Durlston Head
A
- Swanage: Clay
- Durlston: Chalk
22
Q
What is a cliff profile influenced by?
A
- resistance of rock
- dip of rock strata
23
Q
cliff profile:
1. most stable
2. most vulnerable to landslides
cliff profile
3. vulnerable to wave cut notches and weathering?
A
- stable - inland dip
- landslides - (steep) seaward dip
- horizontal bedding planes
24
Q
What is a bedding plane?
A
horizontal cracks in strata, caused by gaps in the time during periods of rock formation
25
what is a joint?
Vertical cracks caused by concentration as sediment dries or by earth movement
26
example of igneous rock + recession rate? example where
| few joints = strong
granite 1mm/year - west cornwall, dartmoor
27
metamorphic rock example + recession rate?
slate 1mm - 1cm/year
28
sedimentary rock + recession rate?
chalk - 20-80cm/year @ 7 sisters East Sussex
29
unconsolidated material example
clay or sand
| very weak -> erodes easily + vulnerable to mass movement
30
differential erosion
when rocks are eroded at different rates due to their different hardness
31
factors that influence differential erosion? (5)
* permeability
* wave energy
* lithology
* rising sea level
* coastal management
32
effect of permeability on rates of coastal recession?
* water weakens permeable rock by removing the cements that binds sediment together
* water emerging at a join between a permeable and impermeable layer can cause surface runoff erosion and instability
* -> slumping
33
what rock types are impermeable?
metamorphic (slate) and igneous (graite)
34
dune ecosystem? (psam_____)
psammosere
35
salt marsh ecosystem? (😇)
halosere
36
what type of rock is most vulnerable to chemical weathering?
| carbonation
calcite rocks
| limestones/chalk
37
why do waves slow and wave height increase when approaching the coast?
* the sea bed gets shallower because of a submerged wave cut platform
* friction with the sea bed slows the waves and increases the wave height
38
Concordant coast example in Croatia?
Dalmation Coast
39
what is a fold and how is it formed?
* folding occurs as a result of sedimentary rocks being folded by tectonic forces
* eg Lulworth Crumble, Purbeck -> folding created heavy jointing making the Purbeck Limestone erode more rapidly that the adjacent Portland Limestone
40
how do plants protect consolidated sediment from erosion? (4)
* roots bind sediment particles together
* submerged plants provide a protective layer so the surface of sediment is not directly exposed to moving water and erosion
* reduced surface runoff
* intercept rainfall reducing splash erosion
41
what type of plants can tolerate salt water + example? 😇
halophytes - glasswort
42
what types of plants can tolerate very dry conditions + eg? 🩻0️⃣
xerophytes - marram grass
43
what are halophytes and xerophytes called? (____ species)
pioneer
44
what physical processes help the formation of sand dunes?
* lots of sand
* onshore winds
* large area for sand to dry out
* obstacles
45
what conditions are required to create salt marshes?
* low energy tidal environment
* limited erosion from the sea
* shelter from the wind and waves
46
features of constructive waves (3)
* low surging waves = long wavelength
* strong swash, weak backwash
* beach gains sediment
47
features of destructive waves (3)
* high plunging waves with short wave length
* weak swash, strong backwash
* beach loses sediment
48
what does wave energy depend on? (2)
* fetch of the wave
* strength of the wind
49
how do tides influence erosion?
tidal surges increase erosion
50
summer beach profile?
* sediment is returned by constructive waves
* berms
* steeper
51
winter beach profile?
* sediment is dragged offshore by destructive waves so faster rates of erosion
* storm ridges
52
why are beach profiles steeper in summer?
constructive waves are less frequent as there are fewer storms\nso stronger swash deposits more material
53
cause of sediment sorting?
* swash deposits larger material at the top of the beach creating a berm
* the berm builds up weakening backwash as the water rains by percolation
* so beach material becomes smaller towards the shoreline forming a steeper beach profile
54
features that destructive waves cause in winter? (3)
* Weak swash and powerful backwash produces a net transport of sediment down the beach -> reducing beach gradient as berms are eroded
* Some sediment is thrown forwards in detached spray of high impact breaking wave -> accumulates above high tide mark as storm ridge
* Large sediment dragged is down beach by backwash to form a wide ridge of material below the low tide mark at start of offshore zone
55
why does sand produce beaches with shallower gradients?
the sand is compacted when wet which allows very little percolation
56
why does shingle produce beaches with steeper gradients?
larger gaps between sediment allows for rapid percolation => little backwash occurs and material is left at the top of the beach
57
hydraulic action
wave pounding - sheer force of waves repeatedly hitting the rock wears it down
58
cavitation (3)
| mechanical weathering
* Wave advances trapping air under high pressure in cracks or fissures
* As waves retreat air is released outwards and expands
* Continued processes of repeated release of pressure cause cracks to grow
59
abrasion + what rock is most vulnerable?
sediment load from waves hurled at a cliff face breaking pieces off
* soft sedimentary eg chalk
60
corrosion + which waves most increase corrosion + which rocks?
| chemical weathering
acidic sea water dissolves minerals in the rock which weakens it
* Constructive waves - slow, long wavelength prolongs the contact of rock with the water => more time for chemical reaction
* carbonate/calcite rocks
61
formation of a wave cut notch?
* during high tide and stormy conditions destructive waves reach the base of the cliff
* hydraulic action and abrasion occur, eroding the base of the cliff
* this forms a wave cut notch between the level of high and low tide
62
formation of a wave cut platform?
* a wave cut notch undercuts the rock above, leaving it unsupported
* this causes the cliff face to collapse
* the cliff will retreat and leave flat sloping areas of the collapsed rock
63
formation of cave, arch, stack stump?
1. headlands cause the waves to refract
1. -> energy is concentrated and hydraulic action and abrasion act on lines of weakness
1. eventually caves meet from opposite sides and form an arch
1. the roof of the arch will become too heavy and collapse forming a stack
1. the base of the stack will continue to be eroded and eventually collapse to form a stump
64
how is material transported along the coast? (4)
* traction
* saltation
* suspension
* solution
65
traction
| tractor 🚜
large sediment is rolled along the sea floor by waves and currents
66
saltation
| ⛹️
sand sized sediment bounces along the water due to the force of the water
67
suspension (and eg)
| 🟫
* sediment is carried in the water column
* suspended clay particles give the sea a cloudy, muddy brown colour on soft-rock coasts, e.g. Holderness
68
solution
| 💧
sediment carried is dissolved within the water
69
UK prevailing and dominant wind direction?
from the south west
70
formation of beaches?
* produced by material deposited by constructive waves
* swash carries material up the beach, but the backwash only has enough energy to transport some of the material back down the beach
* leaving the remainder deposited
71
drift aligned beach?
Sediment is transferred along the coast by longshore drift
72
swash-aligned beach?
Sediment moves up and down the beach with very little lateral transfer
73
explain the formation of a spit
* Longshore drift moves sand and sediment
* Change in the direction of the coastline leads to a build up of sediment
-> a hooked spit may form due to wave refraction round the distal end
-> transports and deposits sediment for a short distance in the landward direction
74
what happens when a spit forms at the mouth of an estuary?
the river flow prevents the mouth from being blocked
75
how does an offshore bar form?
* form from sediment eroded by destructive waves and carried seawards by backwash
* the sediment is deposited at the boundary of the offshore and nearshore zone
76
formation of a bar? (2 ways)
* On drift-aligned coastlines, when longshore drift extends a spit across the entire width of the bay
* rising sea levels -> constructive waves drive a ridge of sediment onshore to coastlines with a gently sloping shallow sea bed
77
formation of a tombolo? (2 ways)
| drift aligned swash aligned
* On drift aligned coastlines, when longshore drift builds a spit out from land until it contacts with an offshore island
* On swash aligned coasts when there is wave refraction around both sides of the island -> collision of wave fronts on the landward side -> cancelling each other out and producing a zone of still, calm water where deposition occurs, between the island and the coast
78
formation of a cuspate island?
* when longshore drift currents from opposing directions converge at the boundary of two sediment cells
* sediment is deposited out into the sea by both currents creating a triangular shaped area of deposited material.
79
example of a low energy coast + why
Cardigan Bay, wales because sheltered by Ireland
80
fjord example
snogfjord, Norway
81
features of emergence - relic cliffs and caves example
King's Caves, Isle of Arran, West coast of Scotland
82
location of Old Harry stack?
Purbeck, Dorset
83
ria example
The Kingsbridge Estuary, Devon
84
longshore drift (7)
* process responsible for moving significant amounts of sediment along the coast
* usually occurs in one direction as dictated by the prevailing wind
-> eg. the prevailing wind along the Holderness Coast is north-easterly
* waves break on to the beach obliquely at an angle of around 45 degrees
* swash moves beach material along the beach
* the backwash, under gravity, pulls the material back down the beach at right angles to the coastline
* over time this creates a net shift of material along the coast.
85
define the sediment cell concept?
areas along the coastline and in the nearshore area where the movement of material is largely self-contained
86
sediment cell example (source, transfer, sink)
1. Flanborough head - source region
2. Holderness coast - transfer zone
3. Spurn head - sink region
87
sediment cells inputs (sources)
* Cliff erosion
* Onshore currents
* River transport
* Wind blown (aeolian) sediment from land
* Subaerial processes
* Marine organisms
88
sediment cell transfers
* Longshore drift
* Swash
* Backwash
* Tidal currents
* Sea/ocean currents
* Wind (onshore, offshore or along shore)
89
sediment cell outputs (sinks)
* sand dunes (backshore)
* beaches (foreshore)
* bars (nearshore)
* barrier islands (offshore)
90
negative feedback in sediment cell (2)
| blockfall + sand dune erosion
* when erosion leads to blockfall mass movement -> collapsed debris acts as a barrier protecting the cliff base -> slowing or preventing erosion for a period of time
* major erosion of sand dunes -> excessive deposition offshore, -> an offshore bar that reduces energy -> allowing the dunes time to recover and further erosion of dune slows
91
positive feedback in a sediment cell
wind erosion of a dune section during high velocity storms = remove stabilising vegetation -> further wind erosion occurs -> increased depletion of dune sand
92
freeze thaw weathering process (4)
| how much does water's volume increase by when it freezes? %
1. Water seeps into cracks in rocks
2. when water freezes, it expands in volume by 9% exerting a tensional force that widens the rock
3. thawing allows more water to enter the crack
4. the process repeats until cracks are forced open and fragment of rock break off
93
salt crystallisation process (3)
1. Seawater penetrates small cracks or pores in rock at high tide -> evaporates at low tide -> leaving precipitated salt crystals
2. Repeated tidal cycles lead to growth of salt crystals -> begin to press against the sides of cracks or pores = exerted tensional pressure
3. Eventually fragments of rock are broken off
94
what kind of rock is most vulnerable to salt crystallisation?
porous and fractured rocks, like many sandstones and limestones
95
carbonation process (4)
1. rainwater mixed + co2 forms a weak carbonic acid
2. acidic rain + calcium carbonate -> form soluble calcium bicarbonate solution
3. minerals dissolve
4. clay particles left from limestone
96
oxidation process (2)
1. addition of oxygen to minerals such as iron produces an oxide
2. increased volume contributes to mechanical breakdown
97
biological weathering process
| tree roots
1. seeds in cracks in rock germinate
2. as the plant grows the roots expand and thicken
3. roots exert tensional force => widening the crack
eventually fragments of rock break away
98
rock boring process
| piddocks
1. piddocks drill depressions into rocks by rotating their sharp edged shell
2. weakening the rock
99
weathering increases the rate of coastal recession by?
weakening rocks and making them more vulnerable to mass movement and cliff retreat
100
blockfall process and initiation + cliff prone to blockfall + eg -> landform?
1. rock fragment breaks away and drops vertically
2. initiated by mechanical weathering + marine erosion
* many joints/faults + steep verticle strata dip
* St Oswald's Bay - 80m chalk detached
-> talus scree slope
101
rotational slumping process + rocks prone rotational slumping + landform?
1. rock failure + movement along a curved rock plane
* weak rocks//uncolsolidated//permeable rock strata over impermeable beds
-> rotational scar terraced cliff face
102
landslide process and initiation -> landform
1. downslope movement of discrete blocks of rock down a linear slip plane
2. discrete blocks released by mechanical weathering of well jointed rocks
3. gravity pulls the loosened blocks down the flat slip plane
103
rate of erosion per year of Holderness coast?
2 metres per year
104
stability of high angle of strata (>4 degrees landward) vs stability of low angle dip (<45 seaward)
* sloping, low-angled profile with one rock layer facing the sea -> vulnerable to rock slides down the dip slope when uppermost strata are attacked by sub-aerial processes
* steep profile -> overhanging rock -> very vulnerable to rock falls = frequent small-scale mass movement of material weathered from cliff face / major cliff collapse when undercutting by marine erosion makes overhang
105
most recent glacial period and global sea levels relative to sea levels today
Devensian -> **120 metres lower**
106
thermal contraction rises sea level by how many mm per year
**3mm per year**
107
inverse barometer effect
a decrease in air pressure of 1 millibar raises the water level by 1 cm
108
rate of sea level is accelerating
**doubled** from **1.4mm** per year in the 20th century -> to **3.6mm** per year 2006 - 2015
109
tectonic uplift from an earthquake example
boxing day tsnumai 2004 led to a permanent rise in sea level of 0.1 mm
110
Holderness Coast rock
chalk and boulder clay
111
Holderness Coast erosion in the winter
2-6 metres
112
Holderness fetch distance
1500 km
113
Coastal defences Holderness coast and its impact of erosion down south the cell
| 🗺️🍎
* **Mappleton groynes**
* Withernsea seawalls -> accelerated erosion from **1 metre to 10 metre**
114
example of infrastructure changing erosion
**Aswan Dam**, Nile delta -> decreased aggradation: sediment volume fell by ~**80%** = less deposition => delta can't rebuild itself ->> **Rosetta erosion increased from 20 metres to over 200 metres per year**
115
dredging example
Hallsand, Devon
* Lost village 1917
* 1,600 tons of material removed each day
* -> beach decreased in size due to decreased sediment supply
* -> depth increase in the occurrence of destructive waves at the coast because they can maintain their energy further towards the shoreline
116
are rates of recession constant
no!!!!
117
influences of rates of recession
* wind direction/fetch
* tides
* seasons
* weather systems
* storm occurance
118
factors that increase flood risk on low lying/estuarine coasts
* height
* degree of subsidence
* vegetation removal
* global sea level rise
lack of coastal sediment to dissipate wave energy and slow storm surges
119
mangrove removal spev 🌴 + importance of mangroves as natural buffers??
- **45% of mangroves in Bangladesh** have been removed for industrial shrimp farming
- in the first 20 metres of mangrove forests, 50 - 70% of the wave energy is dissipated
120
By how much has the Po Delta, Italy sunk from methane extraction?
3.7 metres
121
increased flood risk in Bangladesh: causes + impacts
* mangrove removal 45%
* subsidence 8 - 18 mm
* low lying plain
* loss of farmland due to salt contamination
* wet condition = breeding ground for malaria
* salt water incursion impacting the drinking water of 20 million
122
explain how the building of dams increases coastal flooding risk
water trapped so sediment transportation is disrupted and slowed\nless aggradation so less sediment between the coast and land
123
define storm surge
a short term rise in sea level (above the high tide mark) caused by low air pressure\nstrong winds push heightened waves onshore
124
economic impact of coastal recession
- The collapse of the section of coast supporting the South Devon Main Line Railway in February 2014 cost **£35 million to repair** + **UK economy lost £1.2 billion** through disrupted tourism and fishing
- loss of tourism in Maldives (lowest lying islands)
125
Blackwater Estuary in Essex is an area of tidal salt marsh and low-lying farmland - adopted solution against flooding?
- Essex Wildlife Trust purchased Abbotts Hall Farm (vulnerable to flooding) -> realignment scheme -> used it to form new in land salt marshes
**BENEFITS**
- Abbotts Hall Farm owners received the market price for their threatened farm
- high costs of a 'hold the line' policy were avoided + flood risk was reduced
- Water quality in the estuary improved because of expansion of reed beds that filter + clean the water
- Additional income streams from ecotourism and wildlife watching were created - Important bird and fish nurseries were enhanced.
## Footnote
The Blackwater Estuary shows that environmentalists, landowners, coastal managers and local people and businesses can all be kept happy, even when radical plans are adopted.
126
cost of beach nourishment per km?
## Footnote
in the millions
£20 million
127
3 main aspects of Integrated Coastal Zone Management?
1. entire coastline should be considered
2. recognition of the coastal zone's importance to the livelihood of people, and that economic activity sometimes degrades the environment
3. management must be sustainable
128
What are the 4 Shoreline Management Plans?
- hold the line
- advance the line/strategic realignment
- no active intervention
- managed retreat
129
4 aspects that might determine which SMP is chosen?
- the economic value of the land being protected
- the technical feasibility of engineering defences
- the cultural and environmental value of the land
- pressure from communities
geography edexcel a level case studies
flashcards
Decks in class (9)
# Cards
-
tectonic processes and hazards spev and key processes88
-
hydrological cycle and water security83
-
the carbon cycle43
-
coasts key terms/located examples etc129
-
globalisation spev 🌐53
-
superpowers spev 💪🏻32
-
diverse places located examples (better)36
-
HHRI31
-
recent examples for globalisation/superpowers23
