Coastal Systems And Landscapes Flashcards
(122 cards)
1
Q
Define system
A
A set of interrelated components working together towards some kind of process
2
Q
Define closed system and give an example
A
Closed systems have transfers of energy both into and beyond the system boundary, but no transfer of matter
Eg carbon cycle
3
Q
Define open system and give an example
A
Where matter and energy can be transferred from the system, across the boundary and into the surrounding environment
Eg hydrological cycle
4
Q
Define isolated system
A
Isolated systems have no interaction with anything outside the system boundary.
No input / output of matter of energy
5
Q
Define dynamic equilibrium
A
Where there is a balance between inputs and outputs of a system
6
Q
Define positive feedback
A
Where the effects of an action are multiplied by the following knock on effects
7
Q
Define negative feedback
A
Where the effects of an action are cancelled out by its following knock on effects
8
Q
Define subsystems
A
The earth is divided into 5 subsections / spheres
9
Q
Name the earths 5 subsystems
A
Atmosphere Lithosphere Biosphere Hydrosphere Cryosphere
10
Q
Define cascading system
A
The earths subsystems interlink to form a cascading system
11
Q
Define fetch
A
Distance travelled by waves
12
Q
Define prevailing wind
A
Most frequent wind direction
13
Q
Define wavelength
A
Distance from one wave crest to the next
14
Q
Define wave height
A
Distance from wave crest to trough
15
Q
Define swash
A
Wave travelling up the beach
16
Q
Define backwash
A
Wave travelling from the beach back into the sea
17
Q
Define constructive wave
A
Characteristics mean more sediment is brought onto the beach in the swash than is removed by the backwash
18
Q
Define destructive wave
A
Characteristics mean more sediment is removed from the beach by backwash than is brought onto it
19
Q
Give an example of positive feedback in a system
A
Global temp rises -> oceans warm up -> warm water unable to dissolve gas -> more CO2 released -> more CO2 in atmosphere -> greenhouse effect -> global temp rise
20
Q
Give an example of negative feedback in a system
A
Increase use of fossil fuels -> more CO2 in atmosphere -> global temp increase -> more plants grow -> absorb CO2 -> reduce in CO2 in atmosphere -> less global warming
21
Q
Facts about the atmosphere
A
• nitrogen (78%), oxygen (21%), other gases (1%)
• atmosphere becomes thinner the higher up it is until it reaches space
• divided into 5 layers:
- troposphere
- stratosphere
- mesosphere
- thermosphere
- exosphere
• purpose to filter and stop UV radiation entering the earth
22
Q
Facts about the biosphere
A
• area on or near the earths surface where life is found
• subdivided into 3 sections:
- lithosphere (rocks)
- atmosphere (air)
- hydrosphere (water)
• stretches 10km above sea level and 8km deep
23
Q
Facts about the lithosphere
A
- includes the upper mantle and crust
- ‘lithos’ is Greek for rock
- average 75km thick
- sits on top of asthenosphere
24
Q
Facts about the hydrosphere
A
• includes all water on, above and below earth - lakes - sea - rivers - ice - clouds • water can be liquid, vapour or ice
25
Facts about the Cryosphere
• the frozen water part of the earths system
- snow
- freshwater ice
- sea ice
- glaciers
- permafrost
26
How might the Cryosphere interact with the lithosphere?
Permafrost
Freeze thaw
Glacial erosion
27
How can you link the hydrosphere to the lithosphere?
Coastal / river erosion -> sediment ->. Deposition
28
How can you link the lithosphere to the biosphere?
Rocks in the lithosphere break down to form soil
| Volcanoes - lahar mud flows
29
Is the coast a closed or open system?
Open
30
How can the dynamic equilibrium of the coastal system be upset?
Eg increased deposition of sediment on the beach but no corresponding change in sediment being removed
31
Inputs of the coastal system
```
• energy from
- waves
- wind
- tides
- sea currents
• sediment
• geology of coastline
• sea level change
```
32
Components in the coastal system...
* erosional landforms and landscapes (caused by erosional processes)
* depositional landforms and landscapes (caused by wind and water transport)
33
Outputs in the coastal system...
* dissipation of wave energy
* accumulation of sediment above the tidal limit
* sediment removed beyond local sediment cells
34
How might the lithosphere interact with the atmosphere?
Weathering of rocks (rain wind etc)
| Volcano -> ash cloud
35
What are the 'shore' areas in a coastal transect?
Backshore
Foreshore.
Inshore
Offshore
36
Where is the backshore area found and when do things occur here?
Area between HWM and landward limit of marine activity
| Changes normally occur here only during storm activity
37
Where is the foreshore area found and what occurs here?
Area between HWM and LWM
| Most important zone for marine processes in times not effected by storm activity
38
Where is the inshore area found?
Area between LWM and point where waves have no influence on land beneath them
39
Where is the offshore mark found and what activity takes place here?
Area beyond the point where waves cease to impact upon seabed
Activity limited to deposition of sediment
40
Give an example of negative feedback at the coast
Beach in dynamic equilibrium -> sediment eroded from beach during a storm -> sediment deposited forming offshore bar -> waves now forced to break before reaching the beach, dissipating their energy + reducing erosion at beach -> when storm calms, normal wave conditions erode offshore bar -> beach in dynamic equilibrium
41
What are waves formed by?
Winds on the surface of the sea - can be both local and distant winds
42
What are the factors that affect the strength of waves?
Wind velocity
Wind duration
Fetch
43
Which winds that hit the UK are most prevailing?
Come from South West, Atlantic Ocean
44
Describe how waves are formed
Wind causes friction at surface of sea
Friction causes a swell (wave)
Energy from wind causes water to move forward in an elliptical motion (circular)
45
Give the wave energy equation
Energy =(prop) wavelength x wave height^2
46
Give the characteristics of a constructive wave
```
Sloping wave front
Wide wavelength
Strong swash
Weak backwash
Low frequency (6-8/min)
```
47
Give the beach characteristics created by constructive waves
Wide, gently sloping beach
| Berms (ridges)
48
Give the characteristics of destructive waves
```
Steep wave front
Short wavelength
Weak swash
Strong backwash
High frequency (10-14/min)
```
49
Give the beach characteristics created by destructive waves
Narrow steep beach profile
| Trough
50
When does wave refraction occur?
When waves are not a regular shape when they reach the shore
51
What changes in the waves as they reach the shore during refaction?
Wave depth increases
Wave velocity decreases
Waves are bent towards the shoreline that is slowest
Waves crash to mirror the seabed contour
52
Which type of waves converge during wave refraction and where do they converge to?
Destructive waves converge towards headlands, eroding it
53
Which type of wave diverge during wave refraction and where do they diverge to?
Constructive waves diverge towards bays, depositing sediment there
54
Define global ocean conveyorbelt
Constant moving system of deep ocean circulation driven by temperature and salinity
55
What is the global ocean conveyorbelt driven by?
Combination of thermohaline currents in the deep ocean and wind driven currents on the surface
56
How does the global ocean conveyorbelt link to the coast?
The temperature of the water changes when it enters areas closer to coastlines
57
Define upwelling
A process in which deep, cold water rises towards the surface
58
Describe how upwelling takes place
Winds blowing across the ocean surface push water away.
| Water then rises up from beneath surface to replace the water.
59
Why do areas of upwelling often have high biological activity?
The water that rises to the surface is typically colder and is rich in nutrients, which fertilise the surface waters
60
What are ocean currents driven by?
Wind
Water density differences
Tides
61
Define ocean currents
The movement of a body of water from one location to another
| Generally measured in m/s or in knots
62
What are currents driven by?
The rise and fall of tides
Wind
Thermohaline currents
63
How does the rise and fall of tides impact on currents?
Tides create a current in oceans which are strongest near the shore and in bays and estuaries along the coast = tidal currents.
64
Give some information about tidal currents
Change in a very regular pattern and can be predicted for future dates
Strong tidal currents may travel at speeds of 8 knots or more
65
How do winds impact on currents?
Winds drive currents that are on / near the ocean surface
In coastal areas they drive currents on a local scale -> upwelling
Global scale = winds drive currents that circulate ware for thousands of miles throughout ocean basins
66
How does thermohaline circulation impacts on currents?
Currents occur at both deep and shallow ocean levels and move much slower than tidal / surface currents
67
How do currents affect the earth's climate?
By driving warm water from the equator and cold water from the poles around the earth
68
Define rip current
Powerful, narrow channels of fast moving water
Move at speeds of up to 8 feet/second
They flow away from the shoreline towards the sea
69
What is a longshore current?
When a wave reaches the coastline, it releases a short burst of energy that generates a current which runs parallel to the shoreline = longshore current
70
What are longshore currents affected by?
Velocity of the wave
Angle of the wave / beach
E.g. Longshore currents increase velocity when.... wave breaks at steeper angle / steeper beach slope / high wave
71
Define flood current
An incoming tidal flow
72
Define ebb current
An outgoing tidal flow
73
Define slack water / slack tide
The period between flood and ebb tides when there is little / no current
74
What are tides caused by?
The gravitational pull of the moon and the sun
75
What are tides?
Very long period waves that move through the oceans in response to the forces from the moon and sun.
Tides start off in the oceans and move toward the coastlines where they appear as the regular rise and fall of the sea surface
76
Define high tide and low tide
High tide - when the crest of the wave reaches the shore
| Low tide - when the trough of the wave reaches the shore
77
Define tidal range
The difference between high and low tide
78
When do spring tides occur? Why?
During full moons / new moons
When the earth, sun and moon are in alignment
The gravitational pull of the sun is added to that of the moon, causing the oceans to bulge a bit more than usual
79
How do spring tides affect tides and how often do they occur?
Average tidal ranges are slightly larger
| Happen twice each lunar month
80
When do neap tides occur? Why?
When the sun and moon are at right angles to each other
| The solar tide partially cancels out the lunar tide and produces moderate tides
81
How do neap tides affect tides and how often do they occur?
Tidal range is smaller
| Happens twice each lunar month
82
What is the difference between currents and tides?
Currents move left and right, tides move up and down
Currents occur due to tides, winds and thermohaline circulation, tides occur due to gravitational forces from the moon and sun
83
What are the characteristics of a low energy coast?
Low wave energy
Low rate of erosion (sometimes higher rate of deposition)
Landforms include beaches and spits
84
What are the characteristics of a high energy coast?
High wave energy
Fast rate of erosion
Landforms include headlands, cliffs, WCP
85
What factors influence the regular pattern of the tide?
Morphology of the seabed
Proximity to landmass
Coriolis force
86
What is tidal range significant for?
Shipping routes
Coastal erosion
Leisure reasons
87
When do tidal surges occur and what is their effect?
Occur at times of intense low pressure (a depression)
| Produce very high sea levels and violent storms
88
Name the two types of geomorphological processes
Marine processes
| Sub aerial processes
89
Define marine process
Coastal processes that link with the sea e.g. Waves, tides, LSD
90
Define subaerial process
Take place on land but determine the shape of the coastline e.g. Weathering, mass movement, run off
91
Name the types of marine processes
```
Hydraulic action
Wave quarrying
Abrasion
Attrition
Solution
```
92
Define hydraulic action
The weakening of rocks by the force and pressure caused by the water hitting them
93
Define wave quarrying
Waves compress air into fissures / joints in the cliff face
As the wave withdraws the air is quickly released like an explosion
This weakens / breaks off the rock
94
Define abrasion
The weakening of rocks by sediment in the sea being thrown against the cliffs / WCP
95
Define attrition
Material in the sea wear down each other as they collide in the water
96
Define solution
When acidic water dissolves calcium based rocks e.g. Limestone
Carbon based rocks at the coast can be eroded by rainwater flow from the land as the pH of this is slightly acidic
Salt from the sea water residue in the rocks evaporates, forming salt crystals which as it expands, weakens the rock
97
Name the factors that affect the rate of marine erosion
```
Wave steepness
Breaking point
Fetch
Sea depth
Coastal configuration
Beach presence
Human activity
```
98
How does wave steepness affect the rate of coastal erosion?
Steeper waves carry more energy -> more erosive
99
How does breaking point of waves affect the rate of coastal erosion?
Closer the waves break to the shore, The more they erode rocks
100
How does fetch affect the rate of coastal erosion?
Waves have more energy if they have travelled a longer distance before reaching the shore -> more erosive
101
How does sea depth affect the rate of coastal erosion?
A steeper-shelving sea bed by the shore -> higher and steeper waves
102
How does coastal configuration affect the rate of coastal erosion?
Headlands attract high energy, destructive waves through wave refraction
Concordant / discordant -> more / less resistant rocks exposed
103
How does beach presence affect the rate of coastal erosion?
Beaches dissipate wave energy -> lower rate of erosion
Steep narrow beaches -> dissipate flatter waves
Flat, wide beaches -> dissipate high/rapid energy outputs (spread over a large area)
Shingle beaches -> dissipate steep waves by friction/percolation
104
How does human activity affect the rate of coastal erosion?
Higher rate of erosion -> removing beach material
| Lower rate of erosion -> sea defences (may increase erosion elsewhere)
105
Define lithology
Refers to the characteristics of the rock
| Esp resistance to erosion and permeability
106
Define differential erosion
The variation in rates that different rock types erode
107
Define concordant coastline
Where rock types run parallel to the coastline
| E.g. Lulworth Cove
108
Define discordant coastline
Where rock types run perpendicular to the shoreline
| Et Swanage bay
109
Define the 'dip' of the rocks
The angle at which rock layers are aligned within the rock
110
What does the dip of the rock affect?
Affects the steepness of cliff
Steepest cliffs - where rock strata is horizontal / dipping inland
Sloping cliffs - where rock strata dips towards the sea
111
Name the types of marine transportation
Traction
Saltation
Suspension
Solution
112
Define traction
Large rocks / boulders slide along the seabed in high energy locations due to the movement of the water
113
Define saltation
Small stones bounce along the seabed / beach in high energy locations , dislodging other stones
114
Define suspension
Very small particles of sand and silt that are carried in/ picked up by the water, giving it a murky appearance
115
Define solution
Dissolved materials are transported within the mass of moving water
116
What is the official name for sand dunes?
Psammosere
117
What are sand dunes created by?
Aeolian transportation
| Aeolian deposition
118
Name the types of aeolian transportation that causes sand dunes to form?
Surface creep
| Saltation
119
Define fluid threshold velocity
Wind speed needed to entrain sand particles
| So that sand dunes form
120
What are the conditions needed for sand dunes to form?
Lots of fine sediment - from rivers/seas
High wind energy - big fetch
Large tidal range
Large backshore area
121
Name the types of sand dunes
```
Embryo dune
Fore dune
Yellow dune
Grey dune
Dune slack
Mature dune
```
122
How do sand dunes form?
Sand is deposited when an obstacle traps it e.g. Driftwood, a rock, a bush
As sediment accumulates the mound of sand becomes larger -> dune
Plant e.g. Marram grass, sea couch
The roots interlock with the sand, holding the dune together
