✅COASTS 3.1.3.3 - Coastal Landscape Development Flashcards
1
Q
How is a wave cut platform formed?
A
Waves breaking at foot of cliff form wave cut notch
Undercutting is result of erosion by waves
As undercutting continues, rock above collapses and cliff gradually retreats
A sloping rocky platform is left behind, the wave cut platform, covered at high tide
2
Q
What effect do wave cut platforms have on the rate of erosion?
A
They affect the wave’s ability to erode the cliff because they have further to travel in shallow water
They break earlier and dissipate their energy, reducing rates of erosion
3
Q
What type of process is soil creep?
A
Creep/flow
4
Q
What type of process is mudflow?
A
Flow
5
Q
What type of process is run off?
A
Flow
6
Q
What type of process is landslide/slump?
A
Slide
7
Q
What type of process is rockfall?
A
Fall
8
Q
How does soil creep occur?
A
Slow form of movement of individual soil particles moving down a hill or slope, slow
9
Q
How does mudflow occur?
A
Earth and mud flowing down a slope or hill
10
Q
How does run off occur?
A
A type of flow from one store (rockface) to another (beach or sea)
11
Q
How does landslide/slump occur?
A
Where material slides on a curved surface over weak and unconsolidated rock
12
Q
How does rockfall occur?
A
Sudden form of collapse or breaking away of rocks from a cliff face
13
Q
How is a stack formed?
A
Headland is attacked by waves along lines of weakness
The erosion exploits a weakness, forming a cave
If the weakness runs through the headland, two caves may form back to back
Eventually an arch is formed
Wave attack continues at the base of the arch until it collapses, leaving a stack
14
Q
How is a stump formed?
A
When a stack is continually eroded until it collapses
15
Q
In what conditions do swash aligned beaches form?
A
When waves break parallel to the coast
16
Q
In what conditions do drift aligned beached form?
A
When longshore drift moves material don the coast, producing a range of partially detached features
17
Q
In what conditions do sand dunes form?
A
When dry material from flat, open beaches is blown inland
Large tidal rain can cause sand to be dried out, meaning it can be blown into dune
18
Q
In what conditions do mudflats and slat marshes form?
A
When finer material stacks together in the shallow water of estuaries
19
Q
When do beach cusps occur?
A
Where the coarser material at the top of the beach absorbs wave swash
20
Q
Where do bay head beaches build up?
A
In sheltered, low energy environments of coves. Wave refraction focuses erosion on the surrounding headands, encouraging deposition in the bay
21
Q
How are coves formed
A
Concordant coast
Hard rock erodes, soft rock erodes fast behind it, creates circle
E.g Lulworth Cove
22
Q
Where do bay bars form?
A
Across estuaries, blocking off rivers
23
Q
When do barrier beaches form?
A
When waves recycle offshore material
24
Q
How do drift aligned beaches develop?
A
Where waves approach the coastline at an angle, the swash moves material up the beach in that direction, and the backwash returns at right angles - LONGSHORE DRIFT
25
How do swash aligned beaches develop?
When waves break parallel with the coast, the movement of water and material is largely up and down the beach. Little LSD.
26
What features arise from swash aligned beaches?
Bay head beaches
Bay bars
Barrier beaches
27
What features develop from drift aligned beaches?
Spits
Recurved spits
Tombolos
Cuspate forelands
28
What can form behind a spit?
Brackish lagoon, due to trapping water. E.g, Slapton Leg, Dorset
29
What are tombolos?
When spits extend from the coasts to an island- e,g., Isle of Portland in UK
30
What are cuspate forelands?
Triangular shaped features which may have resulted from changes in the growth and direction of spits.
31
When does deposition occur?
When there is insufficient energy to move sediments further in low energy environments
32
Where do runnels form?
Close to low water marks, separating pools of standing water at low tide
33
Where do ripples form?
Small marks that appear where the slop of the beach increases and where the tide moves over the beach
34
How does pebble size change up the beach?
Bigger, heavier pebbles are found further up the beach because more energy is required to transport them. Smaller lighter ones are further up to the backshore.
35
What are the features of swash aligned beaches?
Beaches can be large, especially if facing into prevailing wind
Landforms are created by offshore sediment
Found right at the back of bays due to wave refraction
36
What are the features of drift aligned beaches?
Pebbles and sand drift along because in wind direction
| Landforms created by material moved along beach by LSD
37
What is a spit?
A long, narrow feature that extends from the mainland at the end of a drift aligned beach
38
Why does a recurved end occur?
Wave refraction and a second dominant wind force material to move in a different direction
39
In what conditions do tombolos form?
```
Island close to mainland
Area of shallow water
Preferential supply of sediment (cliff erosion)
Small, low energy waves
Sheltered area
Consistent prevailing wind
```
40
When is an offshore bar formed?
When material is built up parallel to the coast. Due to destructive waves' backwash or low energy swash
41
When is a barrier beach formed?
If a bar reaches a headland and the body of water behind it is cut off.
42
What are barrier islands?
Islands formed parallel to the coastline but not touching it, a lagoon may form behind
43
How are sand dunes formed?
Sand accumulates on beach from longshore drift around an obstacle
At low tide, sand dries out, allowing prevailing wind to move it up beach
Larger intertidal range for sand to dry
Sand transported by saltation
Debris on beach traps it
Grasses grow and stabilise dunes
Later, plants die, fertilise dune, forests can form further in land (makes land inward more acidic due to humus accumulation)
44
What is the strand line?
Where debris traps the sand to begin forming a dune
45
What is fluid threshold velocity?
The amount of energy the wind must have to move the sand on a beach
46
What are the stages of dune formation?
```
Embryo dune
Fore dune
Yellow dune
Grey/Fixed dune
Dune slack
Mature dune/heath
```
47
What are the features of embryo dunes?
Sand continually moving - needs obstruction to break force of wind
High pH and wind sped
Lots of salt spray, less the 1m tall, exposed
48
What are the features of fore dunes?
Drought resistant plants colonise eg Lyme grass, Marram grass
As they grown, more sand trapped, building height
Pioneer species- marram grass
Height increases to 5m, 20% of sand exposed
49
What are the features of yellow dunes?
Greater diversity of plants, humus exposed, alkaline pH, more shelter and less spray
Marram grass dominates, moss, heather etc
5-10m high, 80% sand vegetated
50
What are the features of grey dunes?
Stable, 100% marram grass and small shrubs
Sheltered from winds, humus darkens allowing soil to form
Grey because sand mixes with soil
More acidic pH
51
What are the features of dune slacks?
Found between mature dunes
Where water table reaches surface
Plants adapt to damp and shelter, cotton grass, rushes etc
52
What are the features of dune heath/mature dunes?
Found 100m from shore
If undisturbed, can support shrubs and trees such as ash and birch
Fast growing conifers may be planted
53
What are the features of climax vegetation?
May have pine/birch in acidic conditions or beech in alkaline
Increased depth of soil and distance from the sea reduces salt
54
What type of feature are salt marshes and mudflats?
Estuarine
55
What are mudflats?
Created by deposition of fine silts and clays in sheltered low energy coastal environments such as estuaries
56
What are salt marshes?
An area of coastal grassland regularly flooded by seawater
57
What are the factors affecting salt marsh development?
```
Weather
River regime
Sediment supply
Human action
Sea level
Climate
Wave type
Tidal regime
```
58
How does weather impact salt marsh development?
Storms can erode the marsh
59
How does river regime impact salt marsh development?
Changes in currents and volume can effect erosion
60
How does sediment supply impact salt marsh development?
Supply changes can enhance or diminish the available silt
61
How does human action impact salt marsh development?
Commercial, industrial and recreational activity can damage marsh
62
How does sea level impact salt marsh development?
Rises can upset equilibrium and destroy marshes
63
How does climate impact salt marsh development?
Affects species type, growth rates and sea levels
64
How does wave type impact salt marsh development?
Changes in direction, nature and size can affect salt marsh stability
65
How does tidal regime impact salt marsh development?
Changes in tidal currents can increase erosion and alter species
66
What is key to salt marsh development?
A low energy environment
67
What are the required features for mudflat formation?
```
Supply of sediment, coastal or fluvial
Low energy, sheltered area
In an area where deposition will occur
Where salt and freshwater meet
Where there are no strong tides or currents to wash sediment away
```
68
What is a pioneer species?
Hardy plants tolerant to flooding which first colonise an area
69
What is flocculation?
Tiny particles of mud sticking together to enable them to sink
70
What are halophytes?
Plants tolerant to the salt and frequent flooding caused by tides. Like Marram grass
71
What is the process of succession on a salt marsh?
As tidal currents are slowed, material deposited.
Eel grass may begin to grow, slows tides more
Mudflats begin to develop and halophytes colonise
Glasswort develops close vegetation over mud
Plants trap more sediment and leaves and stalks help to to build up
Mud rises, creek system forms
Eventually rises above sea level and new species grow
Upper levels of marsh are rarely flooded and slat marsh succession is complete
72
How could sea level rise threaten salt marshes and mud flats?
As sea levels rise, storms will increase in frequency, leading to more frequent flooding so succession becomes impossible.
The low energy environment will also be disrupted
73
Why are salt marshes and mud flats much rarer than other depositional landforms?
Because the conditions they require are so specific
74
What is isostatic sea level change?
Local changes in sea level resulting from the land rising or falling, relative
75
What is eustatic sea level change?
A global change in sea level, resulting from a fall or rise in the level of the sea itself, actual
76
What are the two major factors causing eustatic change?
Thermal expansion and ice melt
77
How have sea levels changed in the last 10,000 years?
They have generally risen, with some times of fluctuation due to warming and cooling of the oceans
78
Sea level rise in last 20,000 years, since last ice age
130 meters
79
Forecasts suggest rise of how much in sea level by 2100?
at least 0.44 meters
80
How can tectonics alter sea level?
As they change the volume of the oceans, making them larger or smaller and affecting the water capacity they can hold
81
How would glaciation affect isostatic and eustatic change?
Global temperatures cool, ice accumulates on land to form glaciers and ice sheets
Accumulation of ice reduces water available to fill oceans, eustatic fall
Relative fall in sea level partly moderated by ice forcing land mass down by isostatic change
When climate warms, ice melts and eustatic rise
Rising seas flood some coastlines and create submergent features
Once ice is fully melted, isostatic rebound occurs
Prolonged rebound allows emergent features
82
What are the differences between isostatic and eustatic change?
Eustatic is global, isostatic local
Eustatic is actual, isostatic is relative
Eustatic is change to sea, isostatic is changes to land
Eustatic is much quicker
Eustatic can be human induced, isostatic cannot
83
How are raised beaches formed?
As land rises in isostatic change, former wave cut platforms and beaches raised above current sea level
84
How are fjords formed?
When deep glacial troughs are flooded by a rise in sea level.
85
What are the features of fjords?
Long and steep sided with a U shape valley cross section and hanging valleys. Much deeper inland than at coast
86
How are relict/fossil cliffs formed?
Coast undergoes isostatic change and land rises. Sea can no longer reach the cliff face, so erosion stops. Leaves relict cliff set way back from the coast and now beach formed in front.
87
How are rias formed?
Sheltered winding inlets with irregular shorelines are formed when valleys in upland areas are flooded due to eustatic rise
88
Where are rias often found?
Lower parts of rivers and tributaries which were drowned, such as in South West England where sea levels rose after last ice age
89
How are marine platforms/terraces formed?
Wave cut platforms lifted out of the wave activity zone by isostatic change as sea levels fall relative to the land
90
How are Dalmation coasts formed?
When a landscape of ridges and valleys running parallel to the coast is flooded. As sea levels rise, tops of ridges remain exposed while valleys are submerged, leaving a series of offshore islands
91
Which landforms are submergent?
Fjords, Rias, Dalmation Coasts
92
Which landforms are emergent?
Raised beaches, relict cliffs, marine platforms
93
What is subsistence?
Coastal areas sinking often due to excess groundwater abstraction. Has the effect of making sea level relatively higher.
94
What is water volume change?
Due to thermal expansion or addition of extra water from land stores (ice melt)
95
What takes in most of the heat from global warming?
The oceans, at 90%
96
How could underground water resources be affected by sea level rise?
The zone where seawater mixes with fresh water in rivers is dynamic and a rise in sea levels can casue it to move upstream
97
What are some of the effects of climate change on the coasts?
Villages can be lost to flooding
Groundwater can become salt contaminated
High value agricultural land lost
Higher rates of erosion with sea level rise
98
Igneous Rock, examples, rate of erosion
Ex: granite, basalt
Rate: very slow <0.1cm/year
Due to interlocking crystals
99
Metamorphic Rock, examples, rate of erosion
Ex: slate, marble
Rate: slow 0.1-0.3cm/year
Structure: crystals pointed in same direction
100
Sedimentary Rock, examples, rate of erosion
Ex: limestone
Rate: 0.5-10cm/year
Structure: sedimented particles, more vulnerable to erosion, more faults
101
How El Nino causes erosion, California coast
El Nino, stronger waves, more erosion instead
