Coasts Flashcards
Input-What?
Material or energy moving into the system from outside the system
Output-What?
Material or energy moving from inside the system to outside the system
Energy-What?
A power or driving force
Dynamic Equilibrium-What?
A state of balance within a constantly changing system
Stores-What?
The individual elements or parts of a system
Flows/Transfers-What?
The links or relationships between the components
Positive Feedback-What?
When a flow/transfer leads to increase or growth
Negative Feedback-What?
When a flow/transfer leads to decrease or decline
Erosion-What?
The gradual destruction of the coasts by waves
Landforms-What?
A naturally created thing on the coast
Landscape-What?
The area as a whole
Deposition-What?
When sediment is deposited on a beach
Open System-What?
A system with inputs and outputs
Coastal System-What?
The way the coast works
Links between the coast and other systems-Urban Pollution
Pollution in towns and cities causes water pollution, which leads to animals dying
Links between the coast and other systems-Farms near rivers
The fertilizers used runs into the water-causes water pollution and eutrophication
Links between the coast and other systems-Global Warming
Causes sea levels to rise. Increase in coastal flooding
Links between the coast and other systems-Marine Ecosystem
Small fish in river estuaries-more coastal biodiversity
Links between the coast and other systems-Forests
They provide food for the coastline when they erode. Mangroves are known as the “nurseries of the sea”-provides habitat
Energy Sources at Coast-Wind
Wind is the movement of air. Strong winds can create powerful winds
Energy Sources at Coast-Wind-Prevailing Wind
The prevailing wind is the direction in which the wind consistently comes from. In the UK, it is the South West
Energy Sources at Coast-Factors that influence wave height
- Fetch
- Wind Strength
- Seismic Movement-Tsunami
- Asteroids colliding with water
- Atmospheric Pressure
Fetch-What?
The distance the wave has travelled. High fetch=more energy=Strong Wave
Types of Atmospheric Pressure-High Pressure
- Dry
- No wind
- Low energy waves/No waves
Types of Atmospheric Pressure-Low Pressure
- Storms
- Strong Winds
- Strong Waves
Wave Formation-How?
- The water becomes shallower and the circular orbit of the water particles change to a elliptical shape
- The wavelength and the velocity decreases, wave height increases-Causes water to back up behind and rise to a point where it starts to topple over
- Water rushes up the beach as Swash, and moved back down the beach as Backwash
Wavelength-What?
The distance between the crest (top) of two waves
Types of Wave
There are two different types of wave:
- Constructive
- Destructive
Differences between Wave Types-Formation
- Constructive-Distant weather systems generate waves in the open ocean
- Destructive-Local storms create these waves
Differences between Wave Types-Wave Form
- Constructive-Low,surging waves with a long wavelength
- Destructive-High,plunging waves with a short wavelength
Differences between Wave Types-Wave Break
- Constructive-Strong Swash, Weak Backwash
- Destructive-Strong Backwash, Weak Swash
Differences between Wave Types-Beach Gain/Loss
- Constructive-Beach gain
- Destructive-Beach loss
Differences between Wave Types-Beach Profile
- Constructive-Gentle beach that will over time will become steeper
- Destructive-Steep beach, over time it will become flatter
Sources of Energy at Coast-Tides-What
Tides are the periodic rise and fall of the ocean surface, caused by the gravitational pull of the Moon, and to an extent the Sun
Sources of Energy at the Coast-Tides
Tides affect the position at which waves break on the beach. The area between maximum high tide and minimum low tide is where most landforms are created and destroyed
Sources of Energy at the Coast-Currents-What?
The general flow of water in one direction.
Sources of Energy at the Coast-Currents
Currents move materials along the coast
Types of Coastlines
There are two types of coastline:
- High Energy
- Low Energy
Types of Coastlines-High Energy Coasts
- Has large powerful waves
- Sandy Coves
- Rocky Landforms
- High rate of erosion
- Low rate of deposition
Types of Coastlines-Low Energy Coasts
- Has small,gentle waves
- Has offshore reefs or islands
- Has saltmarshes and tidal mudflats
- High rate of deposition
- Low rate of erosion
Types of Coastline-Causes
On a local scale, the cause of high and low energy coastlines is Wave Refraction
Wave Refraction-What?
Wave refraction is the distortion of wave fronts as they approach a indented coastline
Wave Refraction-How?
Wave refraction causes energy to be concentrated at headlands (on high energy coasts) and dissipated in bays
Sediment-What?
Any material which can be eroded,transported or deposited. Sediment can vary in size from large boulders to microscopic particles
Sources of Sediment-Rivers
Sediment that is transported in rivers often account for the majoirty of coastal sediment. The sediment will be deposited in river mouths and estuaries, where it will be reworked by waves, tides and currents
Sources of Sediment-Cliff Erosion
Important in areas of relatively soft or unconsolidated rocks. Soft rock cliffs erode much quicker than hard rock cliffs
Sources of Sediment-Longshore Drift
Sediment is transported from one stretch of coastline to another stretch of coastline
Sources of Sediment-Wind
In glacial or hot environments,wind blown sands can be deposited in coastal erosion. Sand dunes are both a acclamation of sand and a potential source of sand
Sources of Sediment-Glaciers
Ice Sheets break off and fall into the sea, depositing sediment trapped within the ice
Sources of Sediment-Offshore
Offshore sediment can be transformed into the coast by waves,tides and currents. A rise in sea level means that a large amount of sediment being bulldozed to form landforms. Storm surges and Tsunami waves can also be responsible for inputs of sediment to the coastal system
Sediment Cell-What?
A stretch of coastline, usually boarded by two prominent headlands, where the movement of sediment is more or less contained within the cell
Sediment Cells in the UK-How many
There are eleven major sediment cells in the UK. These can be divided into smaller subcells
Sediment Budget-What?
The difference between the amount of sediment that enters the system and the amount of sediment that leaves the system
Sediment Budget-Positive Budget
Occurs when more sediment enters the system than leaves. This builds the coastline
Sediment Budget-Negative Budget
Occurs when more sediment leaves than enters the system. This causes the coastline to retreat
Weathering-What?
The breakdown or disintegration or rock in situ (original place) at or close to the ground
Types of Weathering
There are three types of weathering:
- Physical (Mechanical) Weathering
- Biological Weathering
- Chemical Weathering
Weathering-Physical-What?
The break down of rocks without any chemical changes taking place
Weathering-Physical-Types-Frost Shattering
Occurs when water enters a crack or joint in the rock when it rains and then freezes. When water freezes, it expands. This expansion exert pressure on the rock, which makes the cracks widen. Once this process repeats,rock fragments break away
Weathering-Physical-Types-Salt Crystallization
When salt water evaporates, it leaves salt crystals behind. These grow over time Nd exert pressure in the rock,causing it to break up. Salt can also corrode rocks
Weathering-Physical-Types-Wetting and Drying
Frequent cycles of wetting and drying are common on the coast. Rocks rich in clay expand when wet and contract as they get dry. This can cause them to crack and break apart
Weathering-Biological-What?
The breakdown of rocks by organic activity
Weathering-Biological-Types-Plant Roots
Thin plant roots grow into small cracks in a cliff face. These cracks widen as the roots grow,causing rocks to be broken up
Weathering-Biological-Types Water
Water running through decaying vegetation becomes acidic, leads in increased chemical vegetation
Weathering-Biological-Types-Birds and Animals
Birds and animals dig burrows into cliffs
Weathering-Biological-Types-Marine Organisms
They can also burrow into rocks and/or secreting acids
Weathering-Chemical-What?
A chemical reaction where salts are dissolved and the rocks becomes easily erodeable
Weathering-Chemical-Types-Carbonation
Rainwater absorbs carbon dioxide from the atmosphere to form a weak carbonic acid. This reacts with calcium carbonate in the rock to form calcium bicarbonate, which can easily dissolved
Weathering-Chemical-Types-Oxidation
The reaction of rock minerals with oxygen to form a powder, leaving rocks vulnerable to erosion
Weathering-Chemical-Types-Solution
The dissolving of rock minerals
Mass Movement-What?
The downhill movement of material under the influence of gravity
Mass Movements-Types-Soil Creep-Rate and Nature
Rate of movement:Imperceptible
Nature of movement: Creep/Flow
Mass Movements-Types-Soil Creep-How?
When sediment expands, individual particles are lifted up at right angles to the slope. Sediments can expand when they freeze, get wet or heated up. When sediment shrinks, the particles fall straight back down. Soil creep takes a long time because each participant might move a millimetre each time
Mass Movements-Types-Soil Creep-Case Study
Launceston
Mass Movements-Types-Mudflow-Nature and Rate
Nature of movement: Flow
Rate of movement: Quite rapid
Mass Movements-Types-Mudflow-How?
After a period of heavy rain, water gets trapped within the rock, increasing water pressure. This forces rock particles apart and leads to slope failure. Mudflows are often sudden and fast flowing
Mass Movements-Types-Mudflow-Case Study
California
Mass Movements-Types-Landslides-Nature and Rate
Nature of movement-Slide
Rate of movement- Usually rapid
Mass Movements-Types-Landslides-How?
A landslide involves a block or rock moving very rapidly down a slide plane. Landslides are frequently triggered by earthquakes or very heavy rainfall, when the slip surface becomes lubricated and friction is reduced. Landslides tend to be very rapid and pose a threat to people and property
Mass Movements-Types-Landslides-Case Study
Holbeck Hall
Mass Movements-Types-Rockfall-Nature and Rate
Nature of movement-Fall
Rate of movement-Rapid
Mass Movements-Types-Rockfall-How?
A rockfall involves the sudden collapse or breaking away of rock at cliff. They are associated with steep or vertical cliffs and resistant rocks. A rockfall is often triggered by freeze thaw or a earthquake. Once broken away from the source, rocks fall or bounce down the slope to form scree at the foot of the slope
Scree-What?
Scree is a temporary store in the coastal system, with material being removed and transported. Scree is a store and a input into a sediment cell
Mass Movements-Types-Rockfall-Case Study
Cornwall
Mass Movements-Types-Landslide/Slope-Nature and Rate
Nature of movement-Slide
Rate of movement-Rapid
Mass Movements-Types-Landslide/Slump-How?
A landslide/Slump differs from a landslide in the the slide surface is curved rather than flat. Landslips occur in weak clays and sands, often when permeable rock overlays impermeable rock, which causes pore water pressure to build up. Landslips are characterized by a sharp break of slope and the formation of a scar
Mass Movements-Types-Landslips/Slumps-Case Study
The Holderness Coastline
Mass Movements-Types-Runoff-Nature and Rate
Nature of movement-Flow
Rate of movement-Rapid
Mass Movements-Types-Runoff-How?
When overland flow occurs down a slope/cliff face, small particles are moved downslope to enter the littoral zone. Runoff can be considered a type of flow that transfers both water and sediment from one store to another
Mass Movements-Types-Runoff-Case Study
Any river
Mass Movements-Types-Solification-Nature and Rate
Nature of movement-Creep
Rate of movement-Imperceptible
Mass Movements-Types-Solification-How?
Solification is similar to soil creep, but it only happens in cold periglacial environments. In the summer, the surface layer of soil thraws out and becomes extremely saturated because it lies on top of impermeable frozen ground called permafrost.
Mass Movements-Types-Solification-Case Study
The Arctic
Types of Movement-Slides
Material shifts in a straight line
Types of Movement-Slumps
Materials shifts with a rotation
Types of Movement-Flow
Materials flow downslope
Transportation of Sediment
Coastal transportation plays a major role in the coast system as it transfers sediment from one store to another
Transportation of Sediment-Types
There are 4 types of coastal transportation:
- Saltation
- Suspension
- Solution
- Traction
Transportation of Sediment-Types-Traction
The rolling of course sediment along the seabed that is too heavy to be picked up and carried by the sea
Transportation of Sediment-Types-Saltation
Sediment is “bounced” along the seabed. Sediments is light enough to be picked up or dislodged but too heavy to remain in the water flow
Transportation of Sediment-Types-Suspension
Smaller (lighter) sediment is picked up and carried within the water flow
Transportation of Sediment-Types-Solution
Chemicals dissolved in the water , transported and precipitated elsewhere
Transportation of Sediment-Longshore Drift
Longshore drift is an important transfer mechanism as it is responsible for moving vast amounts of sediment along the coastline
Transportation of Sediment-Longshore Drift-How?
The waves approach the beach at an angle, in the direction of the prevailing wind. The waves are refracted before reaching the beach. When the wave reaches the beach, it picks up sediment and advances up the beach. Backwash then carries the sediment down the beach at 90° to the swash. This is due to gravity. The sediment is either moved by traction, saltation or suspension. This repeats until the sediment has reached the end of the beach, or a curve in the beach, where a spit would be created
Ways to erode the coast-Abrasion
Bits of rock and sediment transported by the waves smash and grind against rocks and cliffs, breaking bits off and smoothing surfaces
Ways to erode the coast-Hydraulic Action
Air in cracks in the cliffs is compressed when waves crash in. The pressure exerted by the compressed air breaks off rock pieces
Ways to erode the coast-Cavitation
As waves recede, the compressed air expands violently, again exerting pressure on the rock and causing pieces to break off
Ways to erode the coast-Wave Quarrying
The energy of a wave as breaks against a cliff is enough to detach bits of rock
Ways to erode the coast-Solution
Soluble rocks get gradually dissolved by the sea water
Ways to erode the coast-Attrition
Bits of rock in the water smash against each other and break into smaller bits