Coastal Transport And Deposition Flashcards

1
Q

What are the types of transport?

A

LSD

Tides and currents

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2
Q

What is LSD?

A

Most waves approach a beach at an angle- generally from the same direction as the prevailing wind.

As the waves advance, material is carried up the beach at an angle.

The backwash then pulls material down the beach at right angles to the shore.

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3
Q

What does LSD do?

A

Transports material along the beach.

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4
Q

What are tides?

A

Changes in the water level of seas and oceans - caused by the gravitational pull of the moon and, to lesser extent, the sun.

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5
Q

What is tidal range?

A

Relative difference in height between high and low tides.

High tidal range = creates powerful tidal currents, as tides rise and fall.

Tidal currents can become particularly strong and fast in estuaries and narrow channels, and are important in transporting sediment.

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6
Q

What are the types of marine transport?

A

Traction
Saltation
Suspension
Solution

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7
Q

What is traction?

A

Relatively large and heavy rocks are rolled along the seabed

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8
Q

What is saltation?

A

Smaller and lighter rocks bounce along the seabed

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9
Q

What is suspension?

A

Lighter sediment is carried

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10
Q

What is solution?

A

Dissolved sediment is carried

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11
Q

When does deposition occur?

A

When waves no longer have sufficient energy to continue to transport material

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12
Q

How does deposition occur?

A

Gravity settling

Flocculation

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13
Q

What is gravity settling?

A

Occurs when the energy of transporting waters becomes too low to move sediment.

Large sediment will be deposited first, followed by smaller sediment

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14
Q

What is flocculation?

A

Small particles will remain suspended in water.

Particles will clump together through electrical or chemical attraction, and become larger enough to sink

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15
Q

What are the types of coastal depositional landforms?

A
Spits 
Different types of beaches 
Offshore bars 
Bars 
Tombolos 
Cuspate forelands
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16
Q

What are spits?

A

A long narrow feature, made of sand or shingle, which extends from the land into the sea (or part way across an estuary).

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17
Q

How are spits formed?

A

It’s moved along the coast by LSD.

If the coastline suddenly changes direction (e.g. because of a river estuary), sediment will begin to build up across the estuary mouth and a spit will start to form.

The outward flow of the river associated with the estuary will prevent the spit from extending right across the estuary mouth.

18
Q

What is a recurved spit?

A

The end of a spit will begin to curve round, as wave refraction carries material round into the more sheltered water behind the spit.

19
Q

What may happen behind a spit?

A

A salt marsh may develop, where finer sediment settles and begins to be colonised by salt-tolerant plants

20
Q

What are offshore bars?

A

Also known as sandbars, are submerged (or partly exposed) ridges of sand or coarse sediment - created by waves offshore from the coast.

21
Q

How are offshore bars created?

A

By waves offshore from the coast

Destructive waves erode sand from the beach with their strong backwash and deposit it offshore in bars.

22
Q

What are bars?

A

Where a beach or spit extends across a bay to join two headlands

23
Q

What can happen behind bars?

A

They can trap water behind them to form lagoons.

25
Q

What are tombolos?

A

A beach (or ridge of sand and shingle) that has formed between a small island and the mainland

26
Q

How do tombolos form?

A

Deposition occurs where waves lose their energy and it begins to build

They may be covered at high tide

27
Q

What is a cuspate foreland?

A

A triangular shaped headland that extends out from the main coastline.

28
Q

What are sediment cells?

A

A length of coastline and its associated nearshore area within which the movement of coarse sediment (sand and shingle) is largely self contained.

There are 11 sediment cells around England and Wales

29
Q

What happens within sediment cells?

A

Sediment moves between the beach, cliffs and sea through processes of erosion, transport and deposition.

30
Q

What do sediment cells have?

A

Sources
Transfers (flows)
Sinks

31
Q

What is the sediment budget?

A

The amount of sediment available within a sediment cell.

32
Q

What is positive feedback?

A

Enhances and speeds up processes, promoting rapid change.

If the sediment budget falls, waves continue to transport sediment (and erosion may therefore increase in some areas, because the sea has surplus energy).
One change has led to another change.

33
Q

What is negative feedback?

A

The regulation and reduction of a natural process.

If the sediment budget increases, more deposition is likely.
The sea corrects itself, because it can only carry so much - and any surplus is deposited.
The sea returns to a situation where it can handle the sediment supply.

34
Q

What is dynamic equilibrium?

A

The way in which systems attempt to balance.

35
Q

How do cuspate foreland form?

A

Occurs where a coast is exposed to LSD from opposite directions.

Sediment is deposited at the point where the two meet, which forms a natural triangular shape as it builds up.

As vegetation begins to grow on the deposited sediment, it helps to stabilise the landform and protect it from storms that could erode it.

36
Q

What is plant succession?

A

Bare ground (such as rock, sand dunes, salt marshes and mud flats) is gradually colonised by plants.

The first colonising plants are called pioneer species. These species begin the process of plant succession, during which other species invade and take over until a balance is reached.

37
Q

What do plants do in plant succession?

A

Pioneer species help bind sand or soil with their roots and adding nutrients when they die and decay.

Creeping plants, or those with leaf cover, help the sand or mud in dunes and marshes to retain moisture.

The invaders provide shade as well as improving the soil.

As the environment changes over time, different species colonise it until it becomes stable.

38
Q

What are the types of dune?

A

Embryo dunes are the first dunes to develop.

As embryo dunes develop, they grow into bigger fore dunes - which are initially yellow in colour, but darken to grey as decaying plants add humus.

Depression between dunes can develop into dune slacks - damper areas where the water table is closer to, or at, the surface.

39
Q

What are salt marshes?

A

Areas of flat, silty sediments that accumulate around estuaries or lagoons

40
Q

Where do salt marshes develop?

A

In sheltered areas where deposition occurs

Where salt and fresh water meets

Where there are no strong tides or currents to prevent sediment deposition and accumulation.

41
Q

What are types of stabilising depositional landforms?

A

Plant succession

Salt marshes