Coastal Environments Key Definitions

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  • Created on: 09-05-14 12:27
Coastal Environments
Where the land meets the sea.
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Inputs of the Coastal System
River sediment, eroded cliff sediment, landslide sediment, transported sediment from offshore
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Process of the Coastal System
Wave action, Tidal movement, erosion, weathering, transportation, deposition
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Outputs of the Coastal System
Sediment taken out to sea, sediment deposited further along the coast
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Littoral Cells
Also known as coastal sediment cells.
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Wave types
Destructive and constructive
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Differences between constructive(c) and destructive(d) waves
C- low frquency, low and long structure, elliptical cross profile, swash brings and deposits sediment on shore. D- high frequency, high and steep structure and have strong backwash.
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movement of water rising onto the shore
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The removal of water from the shore, taking away sediment with it
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Periodic rise and fall of sea levels
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Tidal range
The difference in height between a low tide and high tide
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Sub Aerial processes
Coastal processes NOT relating to the sea- freeze thaw weathering etc.
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Freeze Thaw
Water gets into the cracks of the cliffs, which then freeze overnight, expanding. This causes the crack to widen and erode
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Carbonic acid forms in rocks like limestone, causing them to dissolve. Carbonic acid is a combination of rainwater and dissolved carbon dioxide
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Biological Weathering
Animals and plants put pressure on the ground, causing it to crack. eg. rabbits making a burrow in ground which causes existing cracks to expand
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What does weathering do?
Weakens cliffs, making them more vulnerable to erosion.
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Mass movement
movement of material downhill (because gravity exists)
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Types of mass movement
landslides, slumping and rockfalls
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5 ways waves erode the coastline (marine processes)
Abrasion, Corrosion, Hydraulic Action, Quarrying, Attrition
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Water dissolves minerals from the rocks and washes them away in the backwash
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Also known as CorrAsion. Rock pieces crush against the cliffs and other rocks and cause them to break down. Also smoothen edges of rocks
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Energy of waves is strong enough to break down rocks and deposited sediment
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Hydraulic Action
Compressed air in the cliff is exerted with pressure when the wave crashes against the cliff. This causes pieces of rock to snap off.
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Rocks in the water bash against other pieces of rock, forcing them to crack and break
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5 Factors affecting rate of erosion on a coastline
Rock type, fetch of waves, breaking point of waves, the aspect, the width of a beach
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What is the Aspect?
If there is a prevailing wind blowing in one direction, then erosion and LSD will occur faster
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Discordant coastline
Has mixed types of rocks along it's coastline
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Concordant coastline
Has the same type of rock along it's coastline
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Longshore Drift (LSD)
Currents move sediment along a coastline
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Dynamic Equilibrium
Lack of change in a system as inputs and outputs remain in balance.
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The distance over open sea that a wind blows to generate waves. The longer the fetch, the larger the potential waves
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Waves tend to appoach the coastline in a parallel formation. However, coastline landforms tend to change the energy the wave has.
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Storm Surges
Natural storms (eg. hurricanes) cause atmospheric pressure to reduce. This makes the water level rise.
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Huge waves form due to a shift in the ocean floor. The waves approach the coastline, the bottom of the waves slow down, causing the top waves to rise considerably.
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Coastal Landforms formed by Deposition
Bars, Sand Dunes, Salt Marshes, Beaches and Spits
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Beaches contain.....
Berms, Runnels and Cusps
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How are beaches formed?
Constructive waves deposit sediment on the shore
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Features of a shingle beach
Steep, narrow, have larger particles like stones
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Features of a sand beach
Wide, flat, have smaller particles
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What on earth is a berm?!
A Berm is a ridge containing sand and pebbles. Found at high tide marks. Formed due to the deposition of coarse material.
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What are runnels?
Grooves in the sand that run parallel to the shore. Formed due to the backwash
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What is a Cusp?
Semi-circular shaped depressions which form when waves break directly on the beach. Swash and Backswash are strong. Occur at junctions of shingle and sandy beaches.
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How does a spit form?
Form where coastline suddenly changes in shape
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Instructions for a forming Spit
LSD deposits material across a river mouth, leaving a stick of sand sediment poking out of the coast. The spit gets a recurved end when prevailing wind changes direction. The waves go back to their original direction, causing a marshland to form.
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Describe a Bar
Forms when a Spit makes contact with a bay where there is no strong flow, so it appears to look like a bridge. A lagoon forms behind the Bar.
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Shallow area of water, protected by surrounding areas of deposition (including a bar) and land
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A spit that connects an island to a mainland.
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Develops offshore, parallel to the shore, moved towards the coastline by waves and winds until it joins the mainland
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Found in areas of slow wave movement. The mud/silt is deposited in layers. The mudflats are exposed at low tide.
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Barrier beach
Uncommon in the UK. A long and narrow beach of sand and/or gravel that runs parallel to the coastline and is not submerged by the tide.
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9 Coastal Landforms caused by Erosion
Cliffs, Wave-Cut Platforms, Headlands, Bays, Caves, Blow Holes, Arches, Stacks and Stumps
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Cliff formation
Notch forms at high water mark, rock above notch collapses, causing a cliff to form
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Wave-Cut Platforms
Formed with the remainders of the fallen rock caused by the notch at base of cliff
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Notch at base of cliff develops into a cave
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The area of hard rock, that is eroded slower than a bay
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An area of soft rock which erodes quicker than headlands
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Blow Hole
When a cave extends up to the top of a cliff. (like a smarties tube up a cliff)
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Where two caves meet through a headland. Looks like a tunnel.
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As the coastline erodes, the arch collapses, leaving a stack standing alone in the sea
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Over time, the stack will deteriote due to weathering and erosion processes. This leaves a stump
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Sand Dunes
Form from wind blown sand that is initially deposited against an obstruction such as a bush, driftwood or rock. As more sand particles are deposited the dunes grow in size, forming rows at right angles to the prevailing wind direction.
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Salt Marshes
Salt marshes are exposed at low tide and at least partially flooded at high tide, so only salt resistant forms of vegetation can grow there. They are typically very flat, with numerous muddy channels.
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Isostatic Change
Vertical movements of land relative to the sea. Land goes down= water goes up, vice versa
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Causes of Isostatic Change
Local effects usually. Causes: Tectonic movement, compression/decompression of Earth's crust and Subsistence of land
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Eustatic Change
Caused by a change in sea volume or by change in sea basins.
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Causes of Eustatic Change
Global effects usually. Causes: Tectonic movement, changes in climate (increase in temp= melt ice)
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Features of Submergence (sea level rise)
Rias, Fjords, Dalmation Coastline
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A flooded river valley- partially submerged. Have a gentle long-profile and cross-profile. Wide and deep at mouth. Narrow and shallow inland
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Alot like Rias, however a Fjord is a drowned glacial valley. Straight and narrow with very steep sides. Have a shallow mouth. They get deeper the further in land you go.
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Dalmation Coastline
Valleys lie parallel to the coast. An increase in sea level can then form a dalmation Coastline. This leaves Islands parallel to the mainland
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They rise from submerged volcanoes. They are similar to barrier reefs in terms of biodiversity and form. However, they are confined to submerged oceanic islands, unlike barrier islands which can follow continental coastlines e.g. Great Barrier Reef.
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Fringing Reef
Fringing reefs circle or fringe the coastline or islands. They are often protected by barrier reefs further out to sea, so the plants and animals that live in fringing reefs are suited to low wave energy environments.
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Barrier Reef
These occur further from the sea and are commonly separated from the mainland or island by a deep lagoon. Barrier reefs are normally older and wider than fringing reefs. The Great Barrier reef in Eastern Australia is a barrier reef.
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Hard Engineering
Involves building some type of sea defence with a specific purpose
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Hard Engineering Examples
Sea Walls, Rip Rap, Gabions, Revetments, Groynes, Cliff Fixing, Offshore Reefs
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Soft Engineering
Uses natural systems for coastal defence
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Soft Engineering Examples
Beach Nourishment, Dune Regeneration, Managed Retreat, Do Nothing
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Managed Retreat
Abandons the current line of sea defences, and develops the exposed land in some way. eg. salt marshes built to slow down wave power
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Other cards in this set

Card 2


River sediment, eroded cliff sediment, landslide sediment, transported sediment from offshore


Inputs of the Coastal System

Card 3


Wave action, Tidal movement, erosion, weathering, transportation, deposition


Preview of the back of card 3

Card 4


Sediment taken out to sea, sediment deposited further along the coast


Preview of the back of card 4

Card 5


Also known as coastal sediment cells.


Preview of the back of card 5
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