Physical Geography- Coastal landforms

What type of system is the coastline?
An open system
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What are the four main imputs into the coastal system?
Marine, Atmospheric, Humans, Terrestrial
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Name three marine imputs into the coastal sstem
Waves, tides, salt spray
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Name four atmospheric imputs into the coastal system
Sun, precipitation, wind speed, air pressure
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Name four human imputs into the coastal system
Pollution, settlements, recreation, defences
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Name four terrestrial imputs into the coastal system
Weathering, erosion, rock type, deposition
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Name the three processes in the coastal system
Erosion, deposition and transport
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4 Types of erosion?
Hydraulic action, abrasion, attrition, solution
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4 types of transportation?
Saltation, solution, suspension, traction
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Name the outputs of the coastline
Beaches, sand dunes, bars, tombolos, headlands and bays, cliffs, wave cut platforms/notches, caves, arches, stacks, stumps
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What are the four sources of sediment?
Volcanoes, mountains, clay and eroded pebbles
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What are thr three principle supplies of sediment?
Rivers, cliffs, dunes (terrestrial)
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What is attrition?
Materials carries by the waves bump into each other and so are smoothed and broken down into smaller particles
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What is hydraulic action?
This process involves the force of the water against the coast. The water enters cracks in the coastline and compresses air within it. When the wave retreats the air in the crack expands quickly causing a minor explosion and weakening the cliff.
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What is solution (marine erosion)?
The chemical action of the water. These acids dissolve rocks on the coast such as limestone.
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What is abrasion?
The coast is worn down by the material carried by the waves, waves throw the material against the rock breaking and weakening it.
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What is traction?
Boulders are pushed along by the river bed by the force of the water
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What is saltation?
Pebbles bounce along the river bed
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What is suspension
Small particles like slit and clay are carried along in the water
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What is suspended load?
Grains are supported by turbulance
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What is solution
Soluble materials dissolved in the water are carried along
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Explain longshore drift
Sediments are washed up onto the beach by the swash of the wave. As the waves keep hitting the beach at angles the objects are moved further down the beach. Under the influence of gravity backwash moves sediment back towards the coast at right angle
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What does longshore drift allow
Sediments to be moved along the coast
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What does longshore drift depend on
The direction of the wind and the orientation of the coastline
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What types of subarial weathering is there?
Chemical, physical and biological
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What types of chemical weathering can occur?
Solution, hydration, hydrolysis, oxidation, reduction, chelation, acidic rainwater
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What is (chemical weathering) solution?
Solubility of material depends on the temperature and acidity of the water
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What is (chemical weathering) Hydration?
Materials absorb water weakening Crystal structure and more prone to erosion
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What is (chemical weathering) Hydrolysis?
Reaction between mineral and water related hydrogen ion concentration in the water, water particularly affects feldspar materials in granite
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What is (chemical weathering) oxidation?
Adding or removing oxygen. Particularly effects rocks wit high iron content. Reduction is common in waterlogged conditions
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What is (chemical weathering) chelation?
Organic acids produced by plant roots and decaying matter bound to metal ions causing weathering
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What are four types of physical weathering?
Temperature change, freeze thaw, salt water crystal growth, wetting and drying
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What is salt water crystal growth?
Crystals grow in cracks and exert pressure on the rocks
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What does wetting and drying cause?
Expansion and contraction
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What kind of biological weathering is there?
From plants and animals. e.g. borrowing rabbits
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What is mass movement?
The down slope movement of material under the influence of gravity
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What types of rapid mass movement are there?
Rock fall, rock slides, rock toppling, rotational slides and slumps
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What is rock fall?
When blocks of rock discarded by weathering fall to the cliff foot
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What are rock slides?
When blocks of rock slide down the cliff face.
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Where are rock slides common?
common on the cliffs of Gower in South Wales
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What is slumping?
The gravel (permeable rock) allows water to soak in. Rain water infiltrates the gravels gaining weight but not entering the clay (impermeable) This pressure causes the rotational mass movement.
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Name the three types of slow mass movement
Creep, solifluction, gradual movement of wet soil down a slope.
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What is creep mass movement?
Downslope movement of regolith
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What is solifluction mass movemtn?/
Dwnslope movement of regolith saturated by the meeting of active layer of permafrost
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What is a coastal sediment cell?
Areas along the coastline where the movement of material is largely self contained
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How many sediment cells in the UK?
11
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What are within sediment cells
smaller sub -cells
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What are sediment cells usually bound by?
Two headlands
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Examples of sediment cells
In wales there ae three main sediment and littoral cells, with boundaries at St. Davids Head, Bardsey Sound and Great Orme Head
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What is a coastal sediment budget?
How much sediment is available, where it comes from, where it is stored and how it leaves a particular section
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What three natural sources go into the coastal sediment budget
Cliffs, coastal stores such as marshes and dunes, longshore drift
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What anthropogenic sources go into the coastal sediment budget?
Beach feeding, dune building
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What natural outputs are there for the coastal sediment budget?
To coastal stores (dunes and marshses), offshore, longshore drift
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What is thd definition of fetch?
The distance the wind blows over the surface of the water, the larger the fetch the larger the wave
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How is a wave produced?
The frictional effect of the wind on the seawater surface produces a circular motion where each individual water particle moves in a circular path.
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What does the amount of energy transferred between the wind and the water depend on?
Wind velocity, wind duration, fetch, orientation of the coast to the waves
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How does a wave break?
As the waves enter shallow water, the circular motion in the wave is affected by the sea floor. As the water depth decreases the water path changes from a circular to elliptical shape. The wave steepens then breaks offshore.
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Name some different types of waves
Constructive, destructive, plunging, spilling, surging
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Describe a plunging wave
Steep angled shore gradient, steep fronted, tend to curl over and plunge, strong backwash, destroys beach
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Describe a spilling wave
Steep, low angled, break some distance from the shore, foam forms at the wave crest, low frequency, constructs beach
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Describe a surging wave?
Gentle, steep angled shore gradient, tend not to break completely, waves slide up and down the shore
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Name some features of constructive waves.
Weak backwash, high swash, low wave frequency, low wave height, occurs in the summer, generates berms of sediment on the beach.
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Name some features of destructive waves
Low swash, spilling/surging breaker, high wave height, occurs in the winter, beach stealing, cliff collapsing, large steep wave, high frequency
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Explain wave reflection
Along rocky coastlines where there is deep water the waves are reflected back and do not break the shoreline. The interaction of reflected and incoming waves creates a standing wave
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Explain wave refraction
As the waves approch the shoreline the direction of the wave is modified by the sea bed. This occurs because part of the wace slows when it reaches the shallow water, yet the wave in deeper water continues travelling at the same speed.
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Where are waves concentrated and dispersed due to wave refraction
Concentrated at headlands and dispersed around bays
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What are semi-diurnal tides? and where do they occur?
Occur on all Atlantic coastlines. Two high and two low tides per day
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What are diurnal tides? Where do they occur?
Occur in Antarctica. One high and one low tide per day
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What kind of coats are tide dominated
Lowland sandy estuarine coasts
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What is spring tide? When does it occur?
Spring tide occurs 2x per month. When the sun and moon are in alignment they gravitational energy is combined so there's a stronger pull. If combined with strong winds this causes very high tides and landform changes
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What do tides result from?
from the gravitational attraction on water from the moon and the sun. The moon has twice the impact as the sun
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What is neap tide? When does it occur?
Occurs 2x per month. When the sun and the moon are at right angle with respect to the earth the gravitational forces work against each other so are lessened. This causes a lower than adverage tide.
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What do tides circulate around?
Amphidromic points
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What is an amphidromic point?
Where there is no tide
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What is flood tide?
Water rises and deposits material
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What is Ebb tide?
Falling backwards tide moves material in the other direction
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What does tidal range determine?
The vertical distances over which coastal processes operate
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What happens on a micro-tidal coast?
Wave breaking is concentrated in narrow vertical cut notches formed at the foot of cliffs
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What happens on macro tidal coasts?
Wave energy is distributed over a wider area
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Give an example of a micro-tidal coast
There is a tidal range of less than 2m in eastern Australia
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Give an example of a macro tidal
Tidal range in excess of 6m in most of the Uk coast and parts of northern america
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Name all the types of currents
-Onshore currents -River currents -Rip currents -Longshore currents -Offshore currents - Tidal currents -Shore normal currents
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What is steady state equilibrium
Where variations in energy and morphological response do not change much from adverage
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What is meta state equilibrium
Where the environment switches between two or more states of equilibrium
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What is dynamic equilibrium?
When imputs=outputs. The equilibrium conditions may change slightly however over a long period of time
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What is positive feedback?
amplify the initial change in the system leading to a decrease in sediment.
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What is negitive feedback?
Diminish the effect of change leading to an increase in sediment
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Describe high energy coasts
Dominant ant action is erosion. here there is high wave activity (destructive waves). Exposure to prevailing winds and long fetch. Headlands, cliffs and wave-cut platforms are produced.
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Examples of high energy coastlines
Dyfed in Pembrokeshire, or in South Gower in Wales.
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Describe low energy coasts
This is where the dominant cation is deposition. Often have sand beaches backed by dunes. Depositional features such as spits salt marshes and bars.
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Examples of low energy coast
Netherlands coast
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How is igneous rock formed? Example
Formed through fire. Granite
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How is metamorphic rock formed? Example
Changed from one type of rock to another. This is hard rock. Limestone into marble
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How is sedimentary rock formed? Example?
Formed through layers. This is soft rock. Sandstone
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What is a discordant coastline?
Rock structure is perpendicular to the coast (creates headlands and bays) Creating bands of alternate rock types
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What is a concordant coastline?
Rock lithology runs parallel to coasts (creates coves)
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What is incoherent rock? Example?
Erode easily (clay and sands)
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What is coherant rock?
Have interlocking crystals and strongly cemented particles which have few lines of weakenesses
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What is permeability? Example?
Allows liquids to pass through. Chalk and sand are permeable however clay is impermeable
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When is deposition likely to occur? (4)
When waves enter shallow water, when waves enter a sheltered area, there is little wind, there is a good supply of material
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What is a swash aligned beach?
Waves break parallel to the shore, and there is little longshore drift. Sediment moves onshore and offshore
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What is a drift aligned beach?
Waves break at an oblique angle and longshore drift occurs
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What are zeta-formed beaches?
Headlands and reflection stop longshore drift. Causing a buildup of sediment in front of the headland.
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What is a spit?
A linear deposit of sand a shingle attached to the land at the proximal end but freee at the distal end
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How is a spit created?
Longshore drift moves sediment along the shore, even when there's a change in the coastal trend. The spit is stopped travelling any further by the fastest currnt in the estury.
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What is located behind the spit and why?
Sheltered area which causes deposition and because of this produces saltmarsh.
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How are recurved tips created in a saltmarsh?
Created by the 2nd most dominant fetch.
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Where can you find a spit?
Spurn head
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What are cuspate forelands? How are they created?
triangular shaped projection with an apex pointing out to sea. Sediment from longshore drift is trapped when longshore drift happens in both directions
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What is a tombolo? Example?
When a spit joins onto an island due to longshore drift. Chesil Beach which connects to the Isle of Portland of the dorset coast
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What are bars and barrier islands?
Elongated deposits of sand ans shingle parallel to the coastline. Formed by constructive waves and separated from the shore by lagoons. Typically occur in seas with shallow offshore gradient.
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Where are sand dunes found?
Studland bay and west wittering
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How is a psamorre created?
through the processes of succession
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How are sand dunes created?
Beaches are the source of sand which when dries out is blown inland by saltation.
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What do sand dunes need to be developed?
-When there are strong onshore winds. -They need vegetation such as sea couch and marram grass to colonise the dunes once they are formed. -Sand dunes need an obstacle. -Abundant supply of sand.
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What are sand dunes?
Dynamic ecosystems called psammoseres
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Describe the embryo dunes?
There is a PH of 7. There is poor water retention and a high water marl. Plants living here: sea rocket, saltwort, sandwort and sea couch. here the plants have waxy leaves to retain moisture and withstand winds..
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Describe the yellow dunes?
There is a PH of 6.5. Here there are reduced wind speeds and it is above the level of tides. the soil here is less alkaline. Plants here: Marram grass. This is salt tolerant and thrives on being buried in the sand
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Describe the grey dunes
There is a ph of 5.6. Plants here: Heather. Here there is a nutrient supply and water retention and soil is improved.
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Describe the dune slack?
there is a Ph of 4.5. The soil here is acidic and the water table is high. Grey slacks occur in low lying hollows between dune ridges. Plants here: Rushes, reeds, bog cotton. these plants are moisture loving and are commonly found in wetland areas.
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Where are estuaries located?
Location where rivers extend into the coastal zone
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What do estuaries result from?
the interaction between marine and fluvial processes.
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Where do the sediments found in esturies come from?
1. Fluvial/glacial land based sources 2.estuary margin sources. 3. Sources outside the estuary itself, eg from longshore drift or cliff erosion downdrift.
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Where can tidal flats be found?
Around the edges of esturies
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Example of where a tidal flat is located?
Afon Mawdach on the West coast of Wales
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What do tidal flats provide ideal environments for? Why?
Lugworms, they churn up mudflats a process known as bioturbination
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Where can salt marshes be found?
In sheltered river esturies or behind spits.
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What type of vegetation grows in a salt marsh?
Halophyte and pioneer (cordgrass, grasswort and eelgrass)
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Example of a salt marsh?
Spurn Point in the Humber estuary
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What are the ideal conditions for a salt marsh?
In low energy environments, a large input of sediment which can arrive from the sea or rivers. Near a tidal flat.
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How are wave cut platforms formed?
Formed by the quarrying and corrosion at the base of the cliff, which eventually undermines the cliff, causing slope failure
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What are blowholes?
Where waves surge into a cave that may ct through a shaft through the cliff top through which air or water can be forced. The water is pushed through an forced out the blowhole
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What are geos?
Where the caves roof collapses and a narrow inlet called a geo is formed
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When is deposition likely to occur?
When the swash is stronger than the backwash. When there are constructive waves. When waves enter shallow water. When waves enter a sheltered area. When there is little wind or a good supply of sediment
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What is deposition
When the sea loses energy and drops the material it has been carrying
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What is flocculation?
Process where clay particles aggregate together to form flocs. Flocculation increases fall velocity and therefore speeds up deposition leading to the formation of beaches and bars
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Three protection strategies for coastal landscapes? (Global, national and local)
(global) World heriage sites such as the Great Barrier Reef (national) National marine reserves such as Cape Cod (Local) SSSIs- Site of special scientific interest (studland bay sand dunes)
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At Birling Gap Sussex, what is the rate of erosion?
3 foot per year
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At Birling Gap Sussex, what do they want to save and for how long?
Save properties worth £300,000 for 30 years
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At Birling Gap Sussex, what are they going to do and why?
Going to 'do nothing', as it would be to expensive for he number of properties at risk and it would spoil the landscape
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What is dredging?
The removal of sediment and debris from the bottom of lakes, rivers, harbour, etc
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Disadvantages of dredging?
Effects fisheries, increases erosion, damages wildlife
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What impacts did tourism have on the development of Cancun Mexico?
Many areas are still underdeveloped because of the gap between the rich and the poor, lots of pollution, 25% of mexicos income comes from tourism in Cancun, Many houses still without water,
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In studland Bay in Dorset, how are the sand dunes being damaged?
Tourism (trampling reduces vegetation and lead to blowouts), Knock on effects from holiday campsites, development for housing, can get crowded in summer months
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In studland Bay in Dorset, how are the sand dunes being managed?
By planting marram grass and recycled christmas trees, making designated paths, getting bins, gencing areas off, car parks and broadwalks
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In Wallasea Island, what is happening to the defences? What is the government doing?
The north coast defences are falling into disrepair. The government decided to realign the northern part of the island by constructing a new embankment inland and allowing sea defences to flood
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In Wallasea Island, how much will the scheme cost and who is managing the site
£7.5 million, RSPB
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how big is Hegistbry Head?
17km
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What is the erosion rate for Hengistbury Head
1 metre per year
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What is the geology of Christchurch Bay?
Dominated by sands and gravels with and underlying clay
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Factors influencing coastal management At Barton on Sea?
Sources and amount of funding, pressure from locals, pressure from conservationists, media
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Positive impacts of human activity along coasts
Provides jobs, coastal flooding, locals rely on tourism, ports/trade, culture, positive multiplier, if people visit the site money is protecting the area, fishing
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Negative impacts of human activity along coasts
Landslides, flooding, reliance on tourism, upsets dynamic equilibrium, hard to get insurance, loss of ecosystems, damaged infrastructre
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Advantages and disadvantages of hard engineering
Lasts longer so there is more protection, but its expensive and ugly and there may be consequences further down the coast
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Advantages and disadvantages of soft engineering
Doesn't last, not as effective, looks nicer and not as expensive
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How many villages have been lost on the Holderness coast and why
29 villages have been lost since roman times due to retreating cliff
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What do corals grow from?
Dead excess skeletons of polyps
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What are the necessary conditions for Coral Reef growth
Sea temperature no less than 21, Maximum of 20-30m from the sea surface, Sea sanity of 30ppt to 40ppt, clear oxygenated water, plentiful supply of microscopic zooplankton
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Why are coral reefs important?
Breeding grounds for fish, important for fisheries. rich ecosystems, protect the coast from storms and tsunamis, basis of tourism industries
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Types of coral reefs?
Fringing (reefs grow close to the shore) Barrier (reefs grow close to the shore but have a lagoon that separates them) Atoll (a ring of coral that grows on a submerged volcano or mountain)
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What are the local threats to coral reefs?
Overfishing, tourism, coral mining, high nutrient levels from agricultural run off areas (can make algae grow too much which suffocates coral)
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Global threats to coral reefs?
Coral bleaching, acidification, rising sea levels ad pollution
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What happens when a coral dies?
Leaves behind a limestone skeleton which is susceptible to erosion
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Where do mangroves occur?
30 degrees either side of the equator, in 118 counties, extensively across the east coast of Malaya, topical climates
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How are mangroves adapated
They're halophytes, Have tap roots that sit above the mud to help anchor the three and help with oxygen uptake,
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Why are mangroves important?
provide breeding grounds for fish, home to many species (Bengal tigers, kingfishers, barracuda, turtles), create buffer zone between the sea and land, good for fishing villages,collect slit and sediment and stabilize shorelines against erosion
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Threats to mangrove swamps?
Tourism, Many mangroves have been destroyed to make room for rice paddies, fertilizers destroy habitats
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What is eustatic change?
Change in the amount of water in the sea because the oceans are interconnected
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What is eustatic change caused by
Changes in the ocean water volume and temperature, (thermal expansion and contraction)
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What is glacio eustatic change?
Occurs when the ice on continental ice caps and sheets forms and melts taking water from or to the ocean
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What would happen if Greenland and Antarctic ice sheets melted
there would be eustatic change of 90m
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What is hydro-isostasy?
Sinking of the ocean basins under the weight of the water. Depresses it by 1/3 of the depth of the additional water
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When do emergent landforms appear?
towards the end of an ice age when the isostatic rebound takes place faster than the eustatic rise in sea level.
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Example of an emergant landform
Gower coast in South wales
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What is isostatic change?
Local regional changes in the sea level resulting from land rising or falling relitive to the sea. When ice sheets cover the land it weighs it down making it sink. When the ice sheets melts the land begins to rise again
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What is glacio-isostacy
When glaciated continents are depressed by the weight of their glaciers so sea level is higher
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What are submergent landforms?
They form when eustatic change occurs faster than isostatic rebound. The water floods the land and fills up landforms on the land
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Where are fjords found?
In locations where past glacification extended below current sea level (Norway and Chile)
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What are Fjords?
Drowned glacial valleys which are deep, long, narrow inlets with steep often straight sides
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Where are fjords formed?
Higher altitudes where the effects of ice have been more profound
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What is an entrance to a fjord called?
Threshold (often shallow)
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Where are Rias common?
Along discordant coastlines
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How do rias form?
When global sea levels where lower than now, base level was lowered giving rivers a renewed energy to cut downwards, forming deep rejuvenated river valleys. The sea level rose and drowned the river valleys
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Why are rias important?
For ports as they have deepwater
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Example of a ria
Southern cornwall devon
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What does a seaward dipping bedding plane cause?
Slumping and mass movement
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What does a vertical bedded cliff cause?
Rock toppling
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What do horizontally bedded cliffs cause?
Notches
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What are landward bedding cliffs?
Steep and stable cliffs
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Card 2

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What are the four main imputs into the coastal system?

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Card 3

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Name three marine imputs into the coastal sstem

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Preview of the front of card 3

Card 4

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Name four atmospheric imputs into the coastal system

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Card 5

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Name four human imputs into the coastal system

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