Coastal Systems And Landscapes Flashcards
Define what a system is
A set of interrelated components working together forming a process
Define Dynamic Equilibrium
Rate of input + output in a system are equal to
Define what positive feedback loop
When a process or change in conditions causes a change to the landscape causing it to be more likely to happen again
Define what a negative feedback loop is
When a process or change in conditions causes a change in the landscape making change less likely to happen again
How are waves created
Created by the transfer of energy from the wind blowing over the surface of the sea.
Why do waves break
As waves enter shallower waters waves circular orbits begin to become influenced by friction from the seabed, causing it to become elliptical (oval). Over time this friction slows the wave so much that it causes the wave to break.
What waves occur on steeper beaches
Destructive Waves
What waves occur on shallower beaches
Constructive waves
Describe the swash and backwash characteristics of a constructive wave
Strong Swash, Weak Backwash
Describe the swash and backwash characteristics of Destructive waves
Strong Backwash, Weak Swash
Explain how headland wave refraction demonstrates negative feedback
- Along a discordant coastline, the soft rock is eroded faster
- This forms bays (soft rock) and headlands (hard rock)
- Waves then concentrate their energy onto the headland reducing rate of erosion on the soft rock
- This causes them to be eroded at the same rate rather than increased on bays, therefore considered negative feedback
Describe what happens at a spring tide
When the sun, moon and earth align in a straight line, tidal raising forces (gravity) are at their strongest, producing the highest monthly tidal range
Describe what happens at Neap tides
When the moon and sun form 2 perpendicular lines to earth the tidal raising forces are at their lowest so gives the lowest monthly tidal range.
Which tidal range increases concentration of erosional processes
Low tidal range
Which tidal range increases exposure to subareal weathering
Low tidal range
Which tidal range reduces concentration of erosion
High tidal range
Which tidal range decreases exposure to subareal weathering
High tidal range
What effect do tides have on a storm surge
At high tide the storm surge is amplified, at low tides the storm surge is weakened
What beach has the highest tidal range in the world
The Bay of Fundy
How large is the roll that riptides play in the formation of coastlines
Very little as riptides are localised
Where do riptides form
Between sandbars
Name at least 3 forms of mechanical weathering
Any From:
- Freeze Thaw
- Wetting + Drying
- Pressure Release
- Salt Crystallisation
- Exfoliation
Describe + Explain the process of freeze thaw weathering
- Occurs when water enters a crack in a rock due to precipitation
- A following period of cooler conditions freezes this water
- As ice is less dense than water it expands, exerting pressure on the rock causing cracks to widen or break open, causing scree to fall to the base of the cliff.
Describe and explain the process of Wetting + Drying weathering
- Rock in the intertidal zone (and just above due to sea spray) may alternate between wet and dry.
- Shale and porous rocks expand when they are wet and contract when they are dry.
- This process repeats causing fissures to develop and the rock can fragment
Describe and explain the process of pressure release weathering
- Once overlaying sediment and material breaks off, sediment undergoes a pressure release.
- This causes it to develop weaknesses through mechanisms in the rock cause it to develop weaknesses, cracks or joints as it is allowed to expands.
Describe and explain the process of salt crystallisation weathering
- When salt water evaporates it drys up
- Salt crystals are left behind and grow over time, exerting stresses on the rocks over time (just like the ice during freeze thaw weathering)
- Salt can also corrode rock, particularly those containing iron
Describe and explain the process of exfoliation weathering
- Dry rock in the sun is likely to absorb considerable amounts of heat
- these warm rocks are then cooled rapidly when in contact with the sea causing repeated expanding and contracting of the rock, causing it to fracture
- some describe this erosion to occur like an onion skin
Describe and explain the process of biological weathering
Any One From:
-Thin plant roots grow and cause cracks in the cliff face, widening any cracks and causing them to break
- Water running through decaying vegetation can become slightly acidic, increasing chemical weathering
- Animals digging burrows into cliff faces can increase fractures
Name at least 3 forms of Chemical weathering
Any 3 from:
- Oxidation
- Hydrolysis
- Hydration
- Carbonation
- Solution
- Acid Rain
Describe the process of Oxidation weathering
The reaction of rock to oxygen e.g. rust can cause weakness in rock, increasing risk of fractures and breakages
Describe the process of Hydrolysis weathering
Where mildly acidic water reacts or combines with minerals in rock, weakening the rock
Describe the process of Hydration weathering
Water is added to minerals in the rock making it more susceptible to further weathering by causing the rock to expand causing it to disintegrate and cracks to form
Describe the process of carbonation weathering
Carbon dioxide reacts with water creating weak carbonic acid. This reacts with calcium carbonate to create calcium bicarbonate. This can dissolve easily in water.
Describe the process of solution weathering
Slightly acidic water/ water dissolving the rock it runs over
Describe the process of acid rain weathering
Nitrous oxides and sulphur dioxide can lead to acid rain forming which can be effective at dissolving certain types of rock
Why are sediment cells considered closed systems
Geographers consider sediment cells as closed systems as nothing is lost or gained. However some fine sediment can move between sediment cells by finding their way past the headland.
Define what a sediment cell is
A sediment cell is a distinct area of coastline, separated from other areas by well defined boundaries such as headlands and stretches of deep water.
Name an issue with the concept of sediment budgets
Any 1 from:
- The cells are based upon the movement of coarser particles rather than the movement of suspended fine material.
- Fine sediments can find their way into other cells meaning this closed cell concept is not always true
Describe the Mass Movement process of soil creep
Soil creep is a heave process whereby individual particles expand and contract due to the physical environment (particularly moisture) causing it to move downhill slowly. This is very common in clay.
Describe the Mass movement process of Slumping
A flow type of mass movement in which a major section of regolith, soil or weakened bedrock comes down a steep slope as a backward-rotating slump block. Common along coastlines on verges of main roads. Usually in weak rock, clay or soil.
Describe the mass movement process of rockfall
The fastest form of mass movement, the free fall or downslope rolling of rock pieces, loosened by weathering. These boulders shatter at the bottom and form a scree slope.
Describe the mass movement process of a Flow
Typically occurring in more damp/wet environments when there is a plentiful amount of water and a higher clay content. Over saturated sediment flows from a source area down the side of a slope.
Describe the mass movement process or landslides
When a significant amount of the cliff becomes detached and slides down. Often a block of rock moving along a plane or a slump but can be rotational or flow.
Give an example of a mass movement in the uk
Beachy Head - Landslide in Jan 1999 destroying the devils chimney
Describe wave quarrying
A type of erosion where a breaking wave traps air as it hits the cliff face. The force of the water compresses this air into any gap in the rock face, creating enormous pressure within the fissure/joint. As the water pulls back there is an explosive effect of the air under pressure being released.
Describe Abrasion/Corrosion
A type of erosion where the material that the sea picks up wears away rock faces. Sand, shingle and boulders hurled against a cliff line will do enormous damage. This is also apparent on intertidal rock platforms where sediment is drawn back and fourth grinding away at the platform.
Describe Hydraulic Action
A type of erosion that refers to the impact on rocks of the sheer force of the water itself (without debris). This can exert enormous pressure upon a rock surface, thus weakening it. Such activity is sometimes referred to as wave pounding.
Describe Attrition
A type of erosion where the smaller rocks in the sea which carry out abrasion are slowly worn down into smaller and more rounded pieces.
List 3 factors that effect rate of erosion
Any 3 From:
-Wave Steepness + Breaking Point
- Fetch
- Sea Depth
- Beach Presence
- Human Activity
- Lithology (Rock Characteristics)
- Dip (Angle at which rock lies)
- structure (Discordant/Concordant)
Describe the transportation method of traction
Large stones + Boulders rolled along the sea bed
Describe the transportation process of Saltation
Small stones being bounced along the sea bed
Describe the transportation process of Suspension
Very fine, small particles of sand and silt carried in ocean currents waves + tides.
Describe the transportation process of Solution
Chemicals dissolved in water and carried about in ocean currents, waves and tides
Describe and explain the process of longshore drift
- Swash in the direction of the prevailing wind deposits sediment along the beach at that angle of incidence.
- They are then backwashed perpendicular to the coastline back to sea.
-This process is repeated over time causing sediment to be moved done the beach in the direction of the prevailing wind.
What is a Tombolo
A beach that connects the mainland to an offshore island and is formed due to wave refraction off of the coastal island therefore reducing wave velocity and energy. This results in sediment being deposited. Sometimes these landforms are covered at high tide if the are low.
What is an offshore bar
An offshore region where sand is deposited, as the waves don’t have enough energy to carry the sediment to shore. They can be formed when the wave breaks early, instantly depositing its sediment as a loose sediment offshore bar.
What is a barrier beach/bar
A barrier beach occurs when a beach or spit extends across a bay to join two headlands. This traps water behind it, leading to the formation of a brackish lagoon which is separated from the sea. Some barrier beaches can also be formed due to rising sea levels.
Name the 4 phases of dune growth
- Embryo Dune
- Foredune
- Grey Dune
- Mature Dune
Describe the process of the formation of a Wave Cut Platforms
- Erosion occurs on the base of the cliff forming a wave cut notch
- Weathering weakens the top of the cliff
- The weight of the unsupported cliff causes it to collapse
- Over time this process repeats and the cliff retreats inland
- Backwash transports material from broken cliffs back out to sea forming a wave cut platform at the base of the cliff
Why is a wave cut platform, negative feedback
As the platform is formed by erosion to the cliff and the platform blocks erosion to the cliff
What coastlines do bays and headlands occur on?
Discordant
Describe and explain the formation of bays and headlands
- On a discordant coastline, soft rock erodes faster than hard rock causing it to retreat behind the hard rock.
- Due to wave refraction, hard rock headlands receive more erosion than bays, forming a negative feedback loop causing the coast to retreat uniformly
- this retains the extruding hard rock headlands and soft rock bays
Define dip
The angle at which the strata (layers of rock) lie on a cliff face
What is a bedding plane
A horizontal natural breaks in the strata caused by gaps in time during periods of rock formation
What is a joint
Vertical fractures caused by weathering or the earths movements
Describe the process of cove formation
- Along a concordant coastline, harder rocks and be jointed and can become easily punctured through processes such as wave quarrying, hydraulic action and abrasion
- This eventually reaches the soft rock laying behind
- The softer rock is rapidly eroded so rapidly into a cove
- The hard rock remains for far longer, forming 2 extruding headlands, protecting the bay from erosion thanks to wave refraction.
What is a storm beach
A ridge composed of the beaches largest sediment i.e. boulders thrown by the largest waves on a spring tide
What is a Beach Berm
Ridges forming below storm beaches that are formed as constructive waves deposit sediment.
What is a beach cusp
Semi-Circular shaped depressions formed when waves break directly onto the beach when Swash and backwash are strong
What is a ripple (beach feature)
Developed in the sand by wave/tidal action altering the sea bed where friction has influence
What is a runnel (beach feature)
Occurring before a ridge, runnels are channels that run parallel to the shoreline and are caused by lack of water percolation.
What are the main characteristics of a Swash aligned beach
- Usually perpendicular to the direction of longshore drift, therefore experience minimal longshore drift.
- Can be found on an irregular coastline where waves hit the beach head on.
What are the main characteristics of drift aligned beaches
- Usually parallel to the direction of longshore drift, therefore lots of transport occurring
- Waves are angled to the beach
Explain how a wave cut platform forms
- Erosion occurs at the base of the cliff (hydraulic action, wave quarrying and abrasion) forming a wave cut notch.
- Weathering weakens the top of the cliff
- The weight of the unsupported cliff causes it to collapse and over time for the cliff to retreat inwards.
- Backwash transports material from broken cliffs back out to sea forming a wave cut platform
Describe how a spit forms
- These landforms occur in areas where the coastline changes direction in an aggressive manner and where sediment is actively being transported down the beach via longshore drift.
- Due to longshore drift the sediment extrudes from the coast in the general direction of longshore drift, extending out and curving backwards due to wave energy.
- This forms the spit, which shelters the area behind to form a salt marsh
Explain the difference between a summer and winter beach
Winter Beach:
- Erosion of berm
- Erosion of dunes
- Bar Formation
Summer Beach:
- Formation of Berms
- Regeneration of Dunes
- No bar
What is the difference between a simple and compound spit
Simple:
- Either straight or recurved
- Do not have minor spits of recurved ridges along the landward edge
Compound:
- May have similar features to simple spits
- Have a number of recurved ridges or minor spits along their landward side.
List 3 submergant landforms
Any 3 from:
- Rias
- Dalmatian coastlines
- Fjords
Explain the formation of a Ria
- when a river valley is submerged by the rising sea level, it will flood, sharing the same long and cross profile of the previous river with higher sea levels
- They tend to be rather wide
Explain the formation of a Dalmatian coastline
- Forming similarly to rias but along a concordant coastline. As the sea level rises it submerges the lowlands of valleys where the old coast used to be.
- this leaves islands spotted along the coastlines offshore area, sheltering the new coastline from errosion.
Explain the formation of a Fjord
- Formed when rising sea levels submerge a glacial valley or glacial trough.
- These are formed as glaciers cut through existing valleys, aggressively eroding the surrounding sediment through aggressive abrasion.
- This forms straight and narrow U-Shape valley with very steep sides.
- They also have a shallower part near the mouth near to where all of the sediment carried by the glacier was deposited.
List 2 Emergent coastline landforms
Any 2 from:
- Raises beaches
- Relict Cliffs
Explain the formation of raised beaches
- These are deposits of sand and pebbles on gently sloping platforms, backed by an old (relict) cliff line. These may contain fossil caves, wave cut platforms and even arches.
- these are formed as the sea level lowers the beach is left without erosion leaving it on a ledge above the new beach
Explain the formation of relict cliffs
The old cliffs/cliff line of a coast that has now become exposed as the land has risen from the sea as ice sheets clear from an area. These cliffs are likely to contain fossils and old land features such as wave cut platforms, caves, arches and stacks
How far has the Isle of Jura in Scotland emerged by
40m
Define Eustatic Change
A global change in sea level resulting from an actual fall or rise in sea level itself
Define Isostatic change
Local changes in sea level resulting from the land rising or falling relative to the sea
Define tectonic change
Land being shifted up, down or sideways due to tectonic plate movement
What is isostatic readjustment
- The process of land that was previously covered by ice sheets during the glacial period that is now thawed in the interglacial period causing the land to rebound upwards as there is less weight pushing the land mass down.
- This can also cause other areas of land mass to fall rapidly as the land mass rotated, as the areas of ice coverage rise, areas without prior ice coverage fall.
What areas in the UK suffer the most extreme isostatic readjustment
Western Scotland - +2m/year
South East England - -2m/year
How much have sea levels risen since the end of the the last ice age period
120m
What are the 2 reasons that sea levels are rising
- Ice thawing into the sea, increasing its volume.
- Thermal expansion as temperature of ocean rise reduces its density, increasing its volume.
If global sea levels rises 2m how many properties in the uk will be effected
Just under 500,000
What case study is used for sustainable coastal management
The Holderness coast
What is the SMP in Bridlington and why
Hold the line - a cost-benefit analysis has been done and it has been proven economically and socially important to keep this town from being submerged.
What is the SMP for Easington and why
Hold the line until 2026 - As there is a gas terminal supplying 20% of the UK’s natural gas, it is extremely important to protect it for the time being. However the gas is likely to run out and a new terminal will have to be built so holding the line is not a permanent plan
What is the SMP at flambourough head and why
Managed Realignment to no active intervention - The spit is home to a lifeboat station that already receives limited access and it is only a matter of time before this spit is submerged and completely flooded. The coastline management have decided it is not worth the cost to protect this coastline.
What is the rate of erosion on the holderness coast
3.3m/year on average but 10m/year in some areas
What is the rock types of the holderness coastline
An unconsolidated boulder clay laying (high erosion) in front of chalk
Which towns along the holderness coastline are currently considered “hold the line”
Bridlington, Hornsea, Mappleton, Withernsea, Kilnsea, Easington
Since Roman times, approximately how many villages have been lost since Roman times
Approximately 20-35 villages
What percentage of the UK’s natural gas is supplied at Easington’s Gas terminal
20%
Define what is meant by a rollback scheme
The expenses incurred as a result of an individual’s decision to replace a threatened coastal property with a new home inland.
Give an example of a rollback scheme on the holderness coastline
At kilnsea there is a caravan park where the government paid for every 4 caravans destroyed by the sea, 5 are paid for and placed further back.
