coasts Flashcards
(82 cards)
1
Q
sediment cells
A
Coasts can be split into sections called sediment cells which are often bordered by prominent headlands.
2
Q
how many sediment cells are in the uk?
A
11
3
Q
coastal inputs
A
marine:
-waves
Atmosphere:
-wind
humans:
-pollution
4
Q
coastal outputs
A
-currents
-riptides
-evaporation
5
Q
coastal transfers
A
-longshore drift
-erosion
6
Q
hydraulic action
A
water crashing against the coastline causing material to be dislodged and carried away by the sea.
7
Q
corrosion
A
a process of chemical erosion.
8
Q
attrition
A
rocks hit against each other
9
Q
abrasion
A
rocks carried by the sea are picked up by strong waves and thrown against the coastline.
10
Q
coastal stores
A
-beaches
-dunes
-spits
11
Q
rivers as a sediment source
A
-account for majority of sediment
12
Q
sediment sources
A
-rivers
-cliff erosion
-wind
13
Q
sediment budget
A
the balance of inputs and outputs in the coastal system
14
Q
littoral zone
A
area of land between the cliff’s or dunes on the coast and the
sea.
15
Q
short term factors impacting the littoral zone
A
-tides
-storm surges
16
Q
long term factors impacting the littoral zone
A
-changes in sea level
-human intervention
17
Q
wave formation
A
• Wind blows across the sea surface.
• Energy from the wind is transferred to the water.
• The water moves in a circular motion.
• as the water gets more shallow waves grow in height
18
Q
factors effecting wave energy
A
-strength of wind
-duration of wind
19
Q
constructive wave characteristics
A
-long wavelength
-6-9 per min
-strong swash, weak backwash
20
Q
destructive wave characteristics
A
-short wavelength
-25 per min
-weak swash, strong backwash
21
Q
spring tide
A
-highest high tide, lowest low tide
-occur when the sun and the moon are in
alignment, so their gravitational forces work with each other
22
Q
neap tide
A
-lowest high tide and the highest low tides -when the sun and the moon are
perpendicular to each other, so their gravitational forces work against each other
23
Q
rip currents
A
powerful underwater currents occurring in areas close to the shoreline
24
Q
wave refraction
A
- the bending of waves as they approach an irregular coastline
- causes energy to be concentrated on headlands and spread out in bays, leading to differential erosion.
25
wave quarrying
breaking waves hit the cliff face directly pulling away rocks from a cliff face
26
factors effecting erosion
-Waves
-Beach Size and Presence
- Rock type
27
longshore drift
-Waves hit the beach at an angle determined by the direction of the prevailing wind
-The waves push sediment up the beach in the swash
-The wave then carries sediment back down the beach in the backwash
-This moves sediment along the beach over time
28
mechanical weathering
freeze thaw:
-Water enters cracks in rocks and then the water freezes and expands in volume causing cracks to develop
Salt Crystallisation:
-As seawater evaporates, salt is left behind. Salt crystals will grow over time, forcing the cracks to widen.
29
chemical weathering
carbonation:
-rainwater is slightly acidic
Oxidation:
-When minerals become exposed to the air they become oxidised which increases volume causing the rock to crack.
30
biological weathering
Plant Roots:
- Roots of plants growing into the cracks of rocks, which exerts pressure,
eventually split the rocks
Birds:
-Some birds such as Puffins dig burrows into cliffs weakening them
31
soil creep
The movement of soil particles downhill.
32
mass movement
movement of material down a slope under the influence of gravity
33
mudflow
An increase in the water content of soil can reduce friction, leading to earth and mud to flow over underlying bedrock.
34
landslide
the downslope movement of a mass of rock or debris under the influence of gravity, often triggered by factors like heavy rainfall, earthquakes, or human activity.
35
slump
saturated material slides down a curved surface, often after heavy rain. The movement is rotational, causing the land to slip in a concave shape.
36
Wave-cut Notch
- Erosion is concentrated around the high-tide line creating a wave-cut notch
- As the notch becomes deeper the cliff face becomes unstable and collapses
37
swash aligned beach
Waves break parallele to the coast
38
drift aligned beach
Waves approach at angle, so sediment travels along the beach, which may form
a spit.
39
spit
- Longshore drift deposits sediment at a bend in the coastline.
- Sediment builds out into the sea, forming a spit.
- End curves with wind/wave changes.
- Sheltered area forms a salt marsh.
40
barrier beach/ bar
-Occurs when a beach or spit extends across a bay to join two headlands
-Traps water forming a lagoon which is separated from the sea
41
tombolo
-Bar that connects the mainland to an offshore island
42
offshore bar
-An offshore region where sand is deposited , as the waves don’t have enough energy to carry the sediment to shore. They absorb wave energy
43
sand dunes
- Sand is transported inland by wind
- Obstacles cause sand to accumulate.
- As sand builds up, it forms embryo dunes.
- plants colonise and stabilise the sand.
- Over time, dunes become fixed
44
Isostatic sea level change
- when the land rises or falls relative to the sea
- localised change
-EG. tectonic activity
45
Eustatic sea level change
-affects sea level across the whole planet.
-may be due to thermal expansion/contraction
46
Contemporary Sea Level Change
-Since 1880 sea levels have
increased by around 23cm
47
hard engineering examples
-groynes
-sea wall
-rock armour
-revetments
48
groynes
Timber protrusions that
trap sediment from LSD
49
groynes pros and cons
- build up the beach
- cost effective
x visually unappealing
x increases erosion down shore
50
sea wall pros and cons
- highly effective
- tourism benefits
x expensive to construct and maintain
x visually unappealing
51
rock armour
Large rocks that reduce wave
energy
52
rock armour pros and cons
- cheap
x don't fit natural geology
x can be a safety hazard
53
revetments
Wooden or concrete ramps that
help absorb wave energy
54
revetments pros and cons
-cheap
x visually unappealing
x need constant maintenance
55
soft engineering examples
-beach nourishment
-dune stabilisation
-managed retreat
56
beach nourishment
Sediment is taken from offshore
sources to build up the existing beach
57
beach nourishment pros and cons
-cost effective
-looks natural
x needs constant maintenance
x dredging may have consequences on habitats
58
dune stabilisation
Marram grass planted. The roots
help bind the dunes, protecting land behind
59
dune stabilisation pros and cons
- cost effective
- creates a habitat
x planning is time consuming
60
managed retreat
allowing low-lying areas to flood
61
Integrated Coastal Zone Management
- environmental protection is prioritised over economic development
- must involve all stakeholders
- In 2013 the EU adopted a new initiative which promotes the use of ICZM’s
61
managed retreat pros and cons
- creates a habitat
x farmers have to be given compensation
62
Shoreline Management Plans (SMPs)
-There is an SMP for each UK sediment cell.
-Different factors are considered when choosing a management options: The economic value of
assets that could be protected, and the ecological value of land
63
What are emergent coastal landforms and how do they form?
Emergent landforms are features exposed by a relative fall in sea level, usually due to isostatic rebound. Common after glaciation when land rises as ice melts.
64
Name and describe two emergent coastal landforms.
Raised beaches – former wave-cut platforms now above sea level.
Relict cliffs – cliffs inland from the current coastline, often with notches and caves.
65
What are submergent coastal landforms and how do they form?
Submergent landforms are created by a rise in sea level (eustatic change), often due to melting ice caps or thermal expansion of oceans.
66
Name and describe three submergent coastal landforms.
Rias – drowned river valleys, e.g., Kingsbridge Estuary, Devon.
Fjords – deep, steep-sided glacial valleys flooded by the sea, e.g. Norway.
Dalmation coasts - Submerged parallel valleys creating long, narrow offshore islands, Croatia
67
How might climate change affect submergent and emergent features?
Climate change can increase submergence through sea-level rise, submerging low-lying coasts and altering rias and fjords. It may overwhelm some emergent features.
68
What is glacial subsidence and how does it relate to coastal landforms?
- land sinks because of the weight of a glacier sitting on it.
- When the ice melts, that weight is removed
- the land doesn’t bounce back quickly; it slowly rises again over thousands of years
- This slow rising is called isostatic rebound.
69
example of tectonic activity causing subsidence
2004 Indian ocean earthquake, caused a city to sink by 0.5 meters
70
thermal expansion
- water gets warmer
- heat expands
- higher volume of water
71
positive feedback example
Coastal erosion removes beach material → less protection for cliffs → increased wave energy reaches cliffs → more erosion.
72
negative feedback example
- A section of a cliff is eroded by marine processes
- the cliff becomes unstable and collapses.
- The collapsed material gathers at the base of the cliff, forming a temporary protective layer
- This protects the cliff from further erosion by absorbing wave energy
73
What is the difference between low energy and high energy coasts?
Low energy coasts have limited wave action and deposition dominates; high energy coasts face powerful waves and strong erosion
74
What are currents and tides, and why are they important?
Currents are flows of water caused by wind or salinity; tides are the daily rise and fall of sea levels caused by the moon's gravity — both influence coastal erosion and deposition.
75
What is traction in coastal processes?
large sediment (like boulders and pebbles) is rolled along the seabed by the force of water.
76
What is coastal runoff?
- the flow of water from land to the sea, carrying sediments anf pollutants
- can affect coastal erosion and water quality
77
How are beaches developed?
- formed by the accumulation of sediment deposited by waves, tides, and currents.
- Constructive waves build up beaches
- destructive waves may erode them
78
How are offshore bars formed?
- sediment is deposited by longshore drift in shallow water
- Waves and currents move sediment along the coast and when wave energy decreases offshore, sediment accumulates to form these bars.
79
how are barrier beaches formed?
- sand is deposited by longshore drift, creating a narrow sandbank parallel to the coastline.
- typically form in sheltered areas where wave energy is low
80
What major change in sea level occurred during the last 10,000 years?
Sea levels rose significantly after the last Ice Age, as global temperatures increased, causing glaciers to melt and contributing to the rise in sea level by about 120 meters.
81
How will recent and predicted climatic change impact coasts?
sea level rise leads to increased coastal erosion, flooding, and storm surges, threatening coastal habitats and communities.
