Coasts Flashcards
(100 cards)
1
Q
What is the Littoral Zone?
A
- The wider coastal zone including coastal land areas and shallow parts of the sea offshore
2
Q
What are the essential features of the backshore?
A
- Usually above high tide level and only affected by waves during exceptionally high tides and major storms
3
Q
What happens at the foreshore?
A
- Inter-tidal zone or surf-zone
- Wave processes occur here between high and low tide
4
Q
Describe the essential features of the nearshore?
A
- Shallow and usually submerged underneath water
- Used extensively for fishing, coastal trade and leisure
5
Q
What is the offshore?
A
- Area beyond the influence of the waves
6
Q
What are three different criteria that might be used in classifying coasts?
A
- Headlands and Bays
- Sediment Movement
- Erosion Rate
7
Q
What are subaerial processes?
A
- Processes that cause erosion that are caused by the weather
8
Q
Describe the essential features of coastal plains?
A
- Low energy
- low Lying
- A lot of deposition occurs
- Has weaker waves
9
Q
What is a concordant coast?
A
- Rock runs parallel to the coast
10
Q
What is a discordant coastline?
A
- Rock runs adjacent to the coastline
11
Q
What is an example of a concordant coastline?
A
- Lulworth cove, Dorset
12
Q
What is a Haff coastline?
A
- When long sediment ridges that are topped by sand dunes run parallel to the coast.
- Create lagoons between the ridges and the shores
13
Q
What are the micro-features of a cliff?
A
- Caves
- Cracks
- Wave cut notches
14
Q
How are cliff micro-features formed?
A
- Expansion of joints and faults in a cliff
15
Q
What is rock strata?
A
- The layers of the rock
16
Q
What are bedding planes?
A
- Natural breaks in the strata (Often horizontal) caused by gaps in the rock formation
17
Q
What are rock joints?
A
- Fractures (Often vertical) caused without displacement either by contraction as sediments dry out, or by earth movements during uplift.
18
Q
What are rock folds?
A
- When rock buckles and crumbles due to pressure during tectonic activity
19
Q
What are rock faults?
A
- Fractures caused when stress of pressure to which a rock is subjected, exceeds its internal strength.
20
Q
What is rock dip?
A
- The angle at which a rock strata lie
21
Q
What are Igneous rocks?
- Erosion rate?
- Examples?
A
- Very hard that forms 95% of the earths crust. Formed through solidification of lava or magma. No layers.
- ER: Less than 1mm a year
- Examples:
+ Diorite
+ Granite
+ Obsidian
+ Basalt
22
Q
What are Metamorphic rocks?
- Erosion rate?
- Examples?
A
- Rocks formed through the transformation of older rocks . Able to change. may or may not have layers. Relatively harder.
- ER: 1mm a year
- Examples:
+ Slate
+ Quarzite
+ Hornfels
+ Marble
23
Q
What are Sedimentary rocks?
- Erosion rate?
- Examples?
A
- Rocks formed through compaction of sediment. Very permeable. Easy to crumble. Distinctly layered.
- ER: 1cm - 1M a year
- Examples:
+ Sandstone
+ Iron ore
+ Coal
+ Limestone
24
Q
What is morphology?
A
- Combination of ‘Morph” = Shape or form and “Ology” = the study of something
25
How do plants protect the coastline?
- Roots: Bind sediment together
- Sheltering from water: When submerged plants provide a protective layer for sediment.
- Sheltering from wind: Plants slow wind speed and act as protection for sediment.
26
What are halophytes?
(Not essential)
- Plants that can tolerate salt water both around their roots and by their leaves
27
What are Xerophytes?
(Not essential)
- Plants that can tolerate very dry conditions like these found on coastal sand dunes where very little water is retained.
28
What are the 5 stages of sand dune formation?
- Embryo Dune
- Fore Dune
- Yellow Dune
- Grey Dune
- Dune Slack
29
What are embryo dunes:
- Youngest dunes
- Formed from new sand pushed up from the beach.
Stabilised by pioneer plants with their roots.
30
What is a fore dune?
- Second stage of dune creation.
- Sand stabalises and new species begin to grow
31
What is a yellow dune?
- The third stage dune
- The highest dune
- may form a ridge with
Marram grass
32
What is a grey dune?
- 4th stage dune
- Formed when there is a plentiful supply of sand
- Well established and mature
33
What is a dune slack?
- Last stage dune
- Right at the back of all of the dunes
- oldest and furthest away from the sea
34
Apart from colour, what distinguishes yellow dunes from grey dunes?
- Yellow dunes are usually bigger and steeper
35
How are waves formed?
- Action of the wind dragging on the surface of the sea creating friction
36
What is the fetch?
- The distance the wind blows over water with similar speed and direction
37
What is wind duration?
- The time for which the wind has blown over the water without disruption
38
What are wind waves?
- Waves generated by the immediate local wind.
- Not self-sustaining and will die out when wind stops
39
What are swell waves?
- Self-Sustaining waves generated by energy beneath the ocean's surface.
- No longer needing local wind
40
What is a constructive wave?
- Shallower waves with much less energy
- Deposit sediment on beaches
41
What is a destructive wave?
- Shorter and higher waves with a lot more energy.
- Remove sediment from beaches and cliffs
42
What is a summer beach?
- Higher beach with more shingle
- More level and has a lower high tide because of berm
- Gradual slope down to low tide due to sediment deposition
43
What is a winter beach?
- More submerged beach at high tide
- Bar formation because of sediment
- Lots of ridges and a high energy location
- Steeper slope down to high tide w
44
What is a storm beach?
- Furthest part of a beach from the tide line.
- Happen after a storm and involve high energy deposition of every coarse sediment
45
What is a berm?
- Lips in a beach from usually from shingle or gravel
46
What is traction?
- When sediment rolls along, pushed by the waves and currents
47
What is saltation?
- When sediment bounces along, either due to the force of the water or wind
48
What is suspension?
- When sediment is carried in the water column
49
What is solution?
- Dissolved material is carried I. the water as a solution
50
What are the 4 processes of erosion?
- Hydraulic Action
- Abrasion
- Attrition
- Corrosion
50
What are the 4 processes of erosion?
- Hydraulic Action
- Abrasion
- Attrition
- Corrosion
51
What is hydraulic action?
- Waves push air into cracks in a cliff face
- Wave retreats and air is relaxed and cliff expands
- Process weakens joints and cracks eventually causing it to break off
52
What is Abrasion?
- Waves advance and pick up pebbles and sediment from seabed
- Wave breaks and hurls the pebbles and sediment at the cliff edge
- Chips away at the cliff and causes it to break
53
What is attrition?
- Gradual wearing down of rock in the water until it becomes sediment.
- Rocks bash together in the water and gradually reduce particle size
54
What is Corrosion?
- When cliffs are formed from an alkaline rock, weak acid in seawater can dissolve these rocks
- Causes rock to break and cliff to crumble.
55
What is the CCASS system?
- Crack
- Cave
- Arch
- Stack
- Stump
56
What are stacks?
- Isolated pillars of rocks that lie just off the coast and are surrounded by water
57
What are stumps?
- Stumps are smaller stacks that become submerged at high tide
58
What are shoreline platforms?
- Flat rocky platforms that extend out from the coast and surround the isolated stacks and stumps.
59
What is a wave cut notch?
- Bottom part of a cliff wall that has been eroded and have a large overhang of rock on the top.
60
What is a tombolo?
- A beach that has formed between a small island and the mainland
61
What is a cuspate foreland?
- A triangular shaped headland that extends out from the main coastline
62
What is a barrier beach?
- When a beach or spit extends across a bay to join two headlands
63
What is a spit?
- A long narrow feature of sand that extends into the sea as a result of sediment deposited by LSD
64
What is an offshore bar?
- Submerge ridge of sand or course sediment
65
What is Longshore Drift?
- The mass movement of sediment up a coastline as a result of the wave direction
66
What is mass movement?
- Movement of a weathered material down a slope
67
What is soil creep?
- Slow downhill movement of individual soil particles
68
What is mudflow?
- When wet soil and mud becomes loose and flows down a slope
69
What is Rockfall?
- When rain freezes, expands and causes fragments of rocks in a cliff to break and fall
70
What is a slump?
- When soil and sediment slump down a cliff due to saturated boulder clay
71
What is a landslide?
- When rock falls down a sloped cliff because the top of a cliff face becomes heavy.
72
What are the 5 types of weathering?
- Mechanical Weathering
- Biological Weathering
- Chemical Weathering
- Salt Weathering
- Wetting and Drying
73
What is Mechanical weathering?
and what happens
- Weathering that. breaks down rocks due to the exertion of a physical force.
- Freeze thaw when water enters cracks.
- Pressure on the rock causes the pressure forcing the crack to widen.
- Freeze thaw repetition causes the rocks to break and fall off
74
What is Salt Weathering and what happens?
- When salt water evaporates leaving crystals
- Corrodes rock (Particularly those with traces of iron)
- Crystals can grow over time, exert pressure on the rock and cause the rock to break
75
What is wetting and Drying?
- When clay expands as it gets wet and contracts the it gets dry causing the rocks to break because of pressure
76
What is Biological Weathering and what happens?
- When weathering occurs due to the action of plants, bacteria or animals
- Thin plant roots grow into cracks in cliff face. Expand and cause rock to break.
or
- Water running through decaying vegetation becomes acidic leading to increased chemical weathering
or
- Birds and animals dig burrows into cliff
or
- Marine organisms ca burrow into rock
77
What is Chemical Weathering and what happens?
- When a chemical reaction takes place causing the generation of a new chemical compound
- Rainwater absorbs CO2 from air to form weak carbonic acid (Carbonation).
- Reacts with calcium carbonate in rocks to form calcium bicarbonate, which can be easily dissolved.
- Cooler the temp of rainwater, more CO2 is absorbed
- Increases effect of carbonation in winter
78
What is marine regression?
- When a former seabed is exposed as sea level drops producing emergent coastline
79
What is marine transgression?
- When areas of land 'flood' causing the coastline to 'drown' producing submerging coast
80
What is Eustatic Sea level change?
- When glaciers melt causing there to be more water in sea causing sea level to rise
or
- When glaciers are formed causing water to be removed from oceans causing sea level to fall
81
What is isostatic sea level change?
- When Glaciers are formed or there is mass deposition in an area, weight of it causes slow 'Crustal sag' where the tectonic plate sinks into the sea causing sea level to effectively rise.
or
- When glaciers melt, reducing weight on the tectonic plate causing it to rise and sea level to fall as land is getting higher.
82
what are 3 physical factors that encourage coastal recession?
- Weathering
- Erosion
- Sea Level Rise
83
Example of a dam that causes coastal erosion?
- Aswan High Dam on the river Nile
- Blocks sediment from being carried downstream and replenishing coastline therefore causing coastal erosion.
84
What is a storm surge?
- When abnormally high waves move swiftly across an ocean as a result of a storm
85
What are the flooding case studies?
- Kiribati
- Bangladesh
86
What is soft engineering?
- When natural processes are used to reduce coastal erosion and flood risk
87
What is hard engineering?
- When man-made items are used to immediately protect areas from coastal erosion or flooding
88
What are some examples of hard-engineering?
- Sea walls
- Groins
- Rock Armour
- Revetments
- Rock Breakwater
89
What are the main factors when managing coastal recession?
- Land use and value
- Political, Social and Economic reasons
- Impacts on coastal processes
- Environmental sensitivity
90
What are environmental refugees?
- People who have had to flee their homes as a result of environmental damage
91
Why is Tuvalu likely to be one of the first sources of environmental refugees?
- Very low lying
- Easy to flood because of rising sea level
- May soon become submerged
92
Why might some stake holders object to a hard engineering approach?
- Ruins the look of the natural coastline
93
What are the 4 shoreline management policies?
- Hold the existing shoreline
- Advance the existing shoreline
- Managed realignment of shoreline
- No active internvention
94
What are some examples of soft-engineering?
- Marsh creation
- Cliff stabilisation
- Dune stabilisation
- Beach nourishment
95
What is mitigation?
- When action is taken to stop long-term risks or hazards
96
what is adaptation?
- Adopting new ways of doing things in order to live with the outcomes.
97
What is an SMP? and what does it involve?
And what is an SMPz?
- Shoreline Management Plan
- Creating a strategy for coastal defence for a specified length of coastline
- SMPz = More modern SMP
98
What is an ICZM and what does it involve?
- Integrated Coastal Zone Management
- Tries to resolve issues in the whole coastal zone, not just on the shoreline
99
What are the 5 factors involved in sustainable coastal management?
- Managing Natural resources
- Managing food and erosion risk through adaptation relocation
- Creating alternative livelihoods
- Education of communities
- Monitoring change
