Coasts Flashcards
What is the name of a holistic view on a bay?
Shoreline Management Plan
what is the name for the area at the back of the beach?
backshore
How does a Fjord form?
Through the melting of Glaciers, a previously V-Shaped valley becomes a U-shaped Valley. Due to eustatic sea level rise, the valley becomes submerged causing it to flood. Also meaning it is surrounded by mountainous regions.
Where do fjord tend to form?
Norway- Sognefjord
Canada- Saguenay
Alaska
What is a swash aligned beach?
A beach where the waves have shaped it by arriving parallel to the shoreline, usually due to wave refraction. This makes littoral drift minimal.
What is Eustatic sea-level rise?
It is sea level rise on a global scale, for example due to thermal expansion.
What is isostatic sea level rise?
When the sea level rises but in one specific place. Usually occurs due to glacial decompression.
What is a drift aligned beach?
A beach likely to experience littoral drift as the swash arrives at a 45 degree angle, and the backwash perpendicular to the beach. This consequently pushes sediment up the beach.
How does a rip-current form?
When a series of waves are plunged at the shoreline, causing a build up of water. This is then met with resistance from newly breaking waves and the backwash. This forms an x shape current.
What are the types of energy at the coastline?
Currents
Tides
Wind
Waves
What are the main zones on an active coastline?
Offshore
Inshore
Foreshore
Backshore
How do waves form?
Air moves across the surface of the water with friction, creating ripples. In open water an orbital motion begins to occur. Once reaching the shore, the orbital motion creates a crest, and begins to occur horizontally driving it onto the beach, and breaking as a wave.
What are the key features of constructive waves?
Long wavelength
strong swash
weak backwash
sediment deposition
more gentle beach profile, which gradually becomes steeper with deposition.
What are key features of destructive waves?
short wavelength
has a long fetch, creating high energy
weak swash
strong backwash
reduction of sediment
steeper beach profile, due to sediment reduction.
What is a neap tide?
The moon is at a 90 degree angle to the sun.
The gravitational pull acts against each other to create lower high tides, and higher low tides.
They have a small tidal range.
What is a spring tide?
The moon is in line with the sun, usually a full or new moon.
The gravitational pull acts together to create higher high tides, and lower low tides.
They have a large tidal range.
What is wave refraction?
When wave fronts are distorted as they approach a discordant coastline. This forces the waves to become focussed towards the headlands.
Occurs when the waves move from deep water into shallow.
What are the different types of weathering at the coastline?
Chemical- Involves a chemical reaction, where salts may be dissolved.
Biological- The breakdown of rocks through organic activity.
Mechanical- The breakdown of rock without any chemicals, usually through methods such as Freeze thaw.
What is Soil creep?
A slow form of mass movement, where soil particles move downhill creating teracettes. Occurs on a slope.
What is Solifluction?
Similar to soil creep, but only occurs in colder climates. During summer, the top layer thaws and becomes highly saturated. This “active layer” moves slowly downhill with the vegetation.
What is a land slip?
occur in weak land, such as clay and sand. Usually these lie above a layer of impermeable and permeable rock, causing a build up of water pressure between the rocks. This causes the land to slip.
Explain the process of Hydraulic action.
Once a wave crashes against the rock, the air get pressurised and trapped within cracks in the rock. This then expands with wave retreat, weakening the joints in the cliff.
What is the sediment cell?
Usually a stretch of the coastline, between two prominently headlands. There are 11 in the UK.
What is the sediment budget?
The material in the sediment cell that is lost and gained.
What can be outputs of the sediment cell?
Material swept out to sea.
Significant changes to storm patterns.
What is wave quarrying?
The action of breaking waves against unconsolidated material such as sand and gravel.
What is corrasion?
The waves break at the base of the cliff, the transported material is hurled at the cliff foot, which chips away at the rock.
What is abrasion?
This is classed as a “sandpapering effect” as sediment is dragged across the beach eroding and smoothing rocky surfaces.
What is solution?
Weak acids contained within the salt water gradually wear away at the rock, and the bonds that hold the rock together.
What is sub-aerial weathering?
The process of breaking down rocks in situ. It is usually rock located above the high tide line.
How are sand dunes formed?
The growth of marron grass, with deep roots and long leaves traps sediment blown into it by the wind.
This gradually builds up overtime, suggesting that the dune will grow in size.
How do caves, Arches, Stacks and Stumps form?
Waves erode into the cliff’s joints and cracks to form a cave.
Continual erosion, or if two caves join up then the arch is formed.
Eventually the rock cannot self sustain, and the top of the arch collapses.
The gradual reduction through erosion forces the stack to collapse, leaving behind a stump.
How does a spit form?
Spits form through the process of deposition.
Sand and shingle is moved along the beach.
When a beach meets an estuary, the change in water direction, causes the sediment to build up along the mouth of the river.
How does a tombolo form?
When waves loose their energy, they deposit sediment. Meaning they drop sediment in the same location building up a tombolo.
Tombolo’s can be covered at times of high tide.
They form between a small island and the mainland, connecting them.
How does an off-shore bar form?
they are ridges of sand and sediment deposited as destructive waves deposit sediment when they loose their energy.
This means that they can absorb wave energy, as they act as a barrier before the beach.
What is a barrier beach?
The build up of sediment joining two headlands.
This can trap water behind it, in a lagoon.
For example Slapton sands has the Slapton freshwater ley trapped behind the beach.
How do estuarine mudflats develop?
Due to the river meeting the sea, the water is slowed causing the process of flocculation. This means that any mud and sand carried by the river is dropped.
Pioneer plants and Halophytes then begin to colonise the deposited sediment (eelgrass and cordgrass).
Mud continues to be trapped in the plants, raising the level of the mudflat.
At low tide water can flow across the flats, meaning that creeks form.
What is the difference between a saltmarsh and a mudflat?
Saltmarsh is highly expansive, whereas a mudflat only develops close to the shoreline with the only sediment accumulating being mud.
What are coastlines of emergence?
Land that has risen following isostatic recovery, meaning that former wave cut platforms are above the sea level.
Examples of landforms of emergence.
Raised Beaches- found in Scotland.
Relic Cliffs- remains of eroded cliff lines, usually found behind raised beaches.
What are coastlines of submergence?
These are coastlines that form as a result of flooding, due to isostatic change.
What is isostatic rebound?
The high of the land changes following the melting of glaciers, meaning that it decompresses. Equally this means that in other areas, the sea level rises acting almost as a see-saw.
Examples of landforms of submergence?
Rias- form when valleys in a dissected upland area are flooded. Found in South-West England.
Fjords- glacial troughs are flooded. Found in Sweden.
How can tectonic activity have an impact upon the coastline?
The uplift from mountain ranges can result in relative fall in sea level.
Local tilting of land mean some ancient ports have been submerged.
How do Dalmatian coasts form?
This is when ridges and valleys form directly parallel to the coastline. Following sea level rising, they flood and the top of the ridges are visible forming small islands.
What is Thermal expansion?
when water heats, the particles expand. This means that they take up more space and therefore the sea level rises. This is a by-product of climate change, as a positive feedback.
How much sea levels rise between 1993-2010?
3.2 mm per year.
What is a cost benefit analysis?
It is undertaken before any coastal management strategy is implemented, and determines the cost vs the benefit that it will have upon the area.
What are the different types of Traditional management strategies?
Groynes
Sea Wall
Rip Rap
Revetments
Offshore Breakwater
What are the different types of sustainable management strategies?
Beach Nourishment
Cliff regrading
Dune Stabilisation
Marsh Creation
What is a shoreline management Plan?
A plan set out for each of the 11 sediment cells in the UK to identify the natural processes occurring within the cells. They can then determine the impacts that any intervention may have in both their situ and the areas further along the cell.
What is a Coastal Integral Management Zone?
This is the process that brings together intervention, development, management and use of the coast.
This means that the bay is being managed as a whole, taking a holistic view.
It works in a similar way to SMP’s.
How does a Ria form?
The Sea level rises, meaning that a river valley floods, usually at the estuary and mouth of the river.
Where can a Ria be seen?
Kingsbridge, Devon- located near Salcombe.
Give an example of a Fjord.
Milford sound.
Where is an example of a Spit in the UK?
Hurst Spit, Keyhaven.
Where can an example of a Tombolo be found?
Frank Island, british Columbia.
Give an example of an arch.
Durdle Door, Dorset UK
Where can an example of a bay be found?
Lulworth Cove, Dorset
What is sub-aerial weathering?
The breaking down of rocks by rain, frost, rivers. These are land based processes that alter the shape of the coastline.
What are geomorphic processes?
The physical and chemical interactions between the earth’s surface and natural forces, that create landforms.
How does cavitation work?
Compressed air within sea joints, cause sea water to be severely compressed. As the wave retreats, air comes out ‘fizzing’ which then enlarges the cracks within the rocks.
