Costal Landscapes and Change Flashcards
What is the littoral zone?
It is a zone that stretches out into the sea and onto the shore. It is divided into 4 sections and is constantly changing.
What are the 4 Littoral zones?
Backshore
Foreshore
nearshore
offshore
What factors can effect the littoral zone?
Short term- waves, daily tides, seasonal storms
Long term- changes to sea level, climate change
What are the natural processes that will cause changes to the littoral zone?
Sediment input from sea and rivers
Destructive waves – erodes the beach
Constructive Waves – build up the beach
Longshore drift – moves material along the coast
Tidal Range – determines where wave action occurs
What are the human activity’s that will cause changes to the littoral zone?
Dredging of rivers (for navigation)
Dredging off offshore areas (material for construction)
Building of coastal defences
What are the inputs to the coast as a system?
Marine- waves, tides, storm surges
Atmospheric- weather/climate, climate change, solar energy
Land- rock type and structure, tectonic activity
People- human activity, costal management
What are the processes to the coast as a system?
Weathering Mass movement Erosion Transport Deposition
What are the Outputs to the coast as a system?
Erosional landforms
Depositional landforms
Different types of coasts
what Valentin’s classification of coasts?
Recognises that coasts can be erosional or depositional and emerging or submerging and that these effects can magnify or neutralise each other.
(circle split into 8 sections)
What are coasts classified depending on?
Their Geology
Level of energy
The balance between erosion and deposition
Changes in sea level
How can coats be classified in the long term?
Geology (discordant + concordant)
Sea level rise (eustatic +isostatic)
How can coasts be classified in the short term?
Wave energy (high energy coast + low energy coast) Wave type (constructive + destructive)
What are the three types of rock?
Igneous
Metamorphic
Sedimentary
How is igneous rock formed?
Created by volcanic activity when magma or lava cools, forming crystals that are usually hard
How is sedimentary rock Formed?
Formed of small particles that have been eroded, transported & deposited in layers or from remains of plants and animals
How is metamorphic rock formed?
Form from other rocks changing by extreme heat and pressure.
Usually form from layers / bands of crystals and very hard
What is costal morphology?
The shape and form of costal landscapes and their features
What is costal recession?
Another term for costal erosion
What is lithology?
The physical characteristics of particular rocks
Give an example of an igneous rock?
Granite
Give an example of an sedimentary rock?
Limestone and chalk
Give an example of an metamorphic rock?
Gneiss and marble
Give an example of an unconsolidated material?
Bolder clay (Holderness coast)
What is the resistance and erosion rates of igneous rock?
Very resistant, annual recession of 1mm per year on average
What is the resistance and erosion rates of Metamorphic rock?
Very resistant
What is the resistance and erosion rates of sedimentary rock?
Thinly bedded limestone – annual recession of 2.5cm per year
What is the resistance and erosion rates of unconsolidated material?
1m per year average at Holderness
What is the permeability of igneous rock?
Impermeable very few spaces of joints for water to pass through
What is the permeability of sedimentary rock?
Often porous – makes susceptible to weather
What is the permeability of metamorphic rock?
Impermeable very few spaces of joints for water to pass through
What is the permeability of unconsolidated material?
Loose materials and so permeable – lost of spaces for water to pass through
What is strata?
Layers of rock
What are bedding planes?
These are natural breaks in the strata, caused by gaps in time during periods of rock formation
What are joints?
These are fractures, caused either by contraction as sediments dry out, or by earth movements during uplift
What are folds?
Formed by pressure during tectonic activity, which makes rocks buckle and crumple (Lulworth cove)
What are faults?
Formed when the stress or pressure to which a rock is subjected, exceeds its eternal strength
The faults then slip or move along fault planes
What are dips?
This refers to the angle at which rock strata lie
What does lithology include?
Geological structure (number and angle of strata & bedding planes)
How porous the rock is (permeability)
Permeability is linked to grain size, rock structure (e.g. crystal) etc…
Composition (e.g - limestone is soluble in rain water because it is a diluted carbonic acid – chemical weathering)
Describe a high energy coastline?
In the UK they tend to be Atlantic facing coats, where the waves are powerful for much of the year (Cornwall)
Where rates of erosion exceeds the rate of deposition
What landforms are created at high energy coastlines?
Headlands
Cliffs
Shoreline platforms
Describe a low energy coastline?
Sandy and estuarine coasts are generally found here
Stretches of the coast where the waves are less powerful, or where the coast is sheltered from large waves
Where the rate of deposition exceeds the rate of erosion
What landforms are created at low energy coastlines?
Beaches
Spits
Costal plains
What is a discordant coastline?
Where the geology alternates between bonds of more resistant and less resistant rock, which run at right angles to the coast
What is a concordant coastline?
This is where bands of more resistant and less resistant rock run parallel to the coast
What are Dalmatian coasts?
They are another type of concordant coastline
They have formed as a result of a rise in sea level
What is a Haff coastline?
It consists of concordant features of long spits and sandy lagoons aligned parallel to the coast
What is a wave length?
The distance between one peak of a wave to the next corresponding peak
What is a wave crest?
The top of a wave (opposite of a trough)
What is a wave trough?
bottom of a wave (opposite of crest)
What is swash?
When a wave reaches the shore, the water that rushes up the beach
What is backwash?
The water that flows back towards the sea
What is wave height?
The wave height of a surface wave is the difference between the height of a crest and the trough
What is fetch?
How far the wind has travelled
What are constructive waves?
Linked to low energy coastlines Low surging waves long wavelength Strong wash Weak backwash Beach gain 6-9 per minute
What are destructive waves?
Linked to high energy and storm weather, leads to erosion Long fetch High plummeting waves Short wavelengths Weak swash Strong backwash Beach loss 11-16 per minute
What is beach morphology?
It means the shape of a beach, including its width and slope (the beach profile) and features such as berms, ridges and runnels. It also includes the type of sediment (shingle, mud, sand) found at different location on the beach
What is a beach profile?
A cross section of a beach
What are the temporal factors effecting beach morphology?
Over a day, as a storm passes and destructive waves change to constructive ones as the wind drops
Between summer and winter (see next slide)
When there are changes to the climate (e.g. if global warming resulted in the UK climate becoming on average stormier, then destructive waves and ‘winter’ beach profiles would become common
Describe summer beaches?
Shallower profiles as constructive waves are more common.
As constructive waves are less frequent, waves energy dissipates and deposits over a wide area
The swash of a constructive wave deposits larger material at the top of the beach – creating a berm
Describe winter beaches?
Steeper profiles as destructive waves are more common.
As destructive waves are more frequent, berms are eroded by plunging waves
Strong backwash transports sediment offshore creating offshore bars
What are berms?
The shingle ridges often found towards the back of a beach
What are offshore bars?
Elongate ridges and mounds of sand or gravel deposited beyond a shoreline by currents and waves
What is abrasion?
This is when pebbles grind along a rock platform, much like sandpaper
Over time the rock becomes smooth
What is hydraulic action?
This is the sheer power of the waves as they smash against the cliff
Air becomes trapped in the cracks in the rock and causes the rock to break apart
What is corrosion?
This is when sea water dissolves certain types of rocks
In the UK, chalk and limestone cliffs are prone to this type of erosion
What is attrition?
This is when rocks that the sea is carrying knock against each other
They break apart to become smaller and more rounded
What are the erosional landforms?
Headlands and bays Wave cut notch Structure platform Cliff Cave, Arch, Stack and Stump
How is a cave formed?
Caves occur when waves force their way into cracks in the cliff face
The water contains sand and other materials that grind away at the rock until the cracks become a cave
Hydraulic action is the predominant process