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Physical Geography > Coasts > Flashcards

Coasts Flashcards

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1
Q

What is the littoral zone made up of?

A

Backshore, foreshore, nearshore and offshore

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2
Q

How many sediment cells are there in England and Wales?

A

11

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3
Q

Sediment cells

A

A sediment cell is generally thought to be a closed system, which suggests that no sediment is transferred from one cell to another.In reality it is unlikely that sediment cells are fully closed systems - with variations in wind direction and tidal currents it is inevitable that some sediment, particularly fine sediment, is transferred between cells.
There are also many sub-cells of a smaller scale existing within the major cells.

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4
Q

Tides explained

A

The periodic rise and fall in the level of the sea. Caused by the gravitational pull of the sun and the moon. The moon is nearer so has the greatest influence. The moon pulls water towards it, creating high tide, with a compensatory bulge on the opposite side of the earth.

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5
Q

Spring tides

A

Twice in a lunar month, when the moon, sun and Earth are aligned, the tidal force is at its strongest. This produces the highest monthly tidal range, known as the spring tide.

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6
Q

Neap tides

A

When the moon and sun are at 90° to each other (also twice per lunar month) the alignments produces the lowest monthly tidal range, known as the neap tide.

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7
Q

Metamorphic rock

A

Are formed when sedimentary or igneous rocks are subjected to great heat or pressure. E.g marble or limestone

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8
Q

Igneous rock

A

Are formed by magma from the molten interior of the earth e.g basalt or granite

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9
Q

Sedimentary rock

A

Are formed from sediments that have settled at the bottom of a lake, sea or ocean, and have been compressed over millions of years.

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10
Q
A
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11
Q

What are dalmation coasts?

A

Are another type of concordant coastline. They have formed as a result of a rise in sea level. Valleys and ridges run parallel to each other. When the valley is flooded because of a rise in sea level, the tops of the ridges remained above the surface of the sea - as a series of offshore islands that run parallel to the coast.

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12
Q

What are haff coasts?

A

Consist of concordant features - long spits of sand and lagoons - aligned parallel to the coast. These are named after the Haffs, or lagoons of the southern shore of the Baltic Sea, which are enclosed by sand spits or dunes.

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13
Q

What is plant succession?

A

Is the long-term change in a plant community as initial colonising species are gradually replaced by others

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14
Q

What is a halosere?

A

Is plant succession in a salt marsh

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15
Q

Plant succession

A
  1. Bare ground is gradually colonised by plants called pioneer species.
  2. Pioneer species modify the environment by binding sand or mud with their roots
    and add nutrient when they die and decay (creating humus).
  3. Creeping plants, with leaves, help keep moisture in the sand/mud. These changes
    allow other species to colonise.
  4. The new invaders modify the environment by providing shade and improve the soil.
  5. As the environment changes, different species colonise until it becomes stable.
  6. The final community to colonise is the climax community (trees)
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16
Q

Embryo dunes

A

First dunes to develop due to sand collecting around debris. 1m in height. Suitable for colonisation by grasses (e.g sea couch, lyme grass) but harsh conditions it is very salty and loosely bound soil does not allow for much growth.

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17
Q

Foredunes

A

Upward growth of the embryo dunes due to accumulation of sand. 5m tall. All colonisation increases like marram begin to add humus to the sand, slightly increasing moisture content. Makes the dune look grey.

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18
Q

Marram grass

A

Grows the roots of which bind the sand together beginning to stabilise it.

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19
Q

Grey dunes

A

More fixed as they are colonised by plant species - roots bind sand together and decaying matter increases fertility. Plants grow (e.g Lichens, mosses and flowering plants) Dunes are 8-10m. pH is becoming more acidic as there is less of an influence of saline water.

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20
Q

Wasting dunes

A

Very little new sand is added as this dune is the furthest from the beach. Heather, gorse and bracken - adapted to more acidic, water retentive sandy soil. Dunes are slightly lower at 8m.

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21
Q

What is the transition from embryo dune to heathland is known as? (sand dune succession)

A

Psammoseral succession

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22
Q

What is eustatic change?

A

Global changes in sea level

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23
Q

What is isostatic change?

A

Changes in the lands elevation

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24
Q

In the North of the UK what types of isostatic change have occurred since the last ice age?

A

Land in the north and west - which was covered by ice sheets during the last Ice Age - is still rising as a result of isostatic recovery

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25
Q

In the South of the UK what types of isostatic change have occurred since the last ice age?

A

However, land in the south and east is sinking. Rivers pour water and sediment into the Thames estuary (accretion). The weight of this sediment causes the crust to sink there and relative sea levels to rise. Therefore, south-east England faces increased flood risks as a result of the land sinking due to isotatic change, as well as a rising sea level caused by global warming

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26
Q

Rias e.g Poole Harbour the south coast is a submergent coastline

A

They form when valleys in a dissected upland are flooded. Common in the south-west England.

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27
Q

Fjords e.g Hardangerfjord in Norway (second-longest in the world)

A

Are formed when deep glacial troughs are flooded by a rise in sea level. They are long and steep-sided, with a U-shaped cross section and hanging valleys. They are much deeper inland than rias.

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28
Q

Storm surges: 2013 UK low pressure system

A

Driven by powerful jet stream bringing low pressure weather systems across the Atlantic. Intense low pressure 976mb.

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29
Q

North sea funnel

A

North Sea is open to the Atlantic ocean and tapers towards the south - a funnel shape allowing strong northerly winds to push storm surges towards London and low-lying coastal areas.

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30
Q

Impacts of 2013 storm surge UK

A

Gusts over 200km/hr in Scotland. 1400 homes flooded. Evacuation mostly along the coast of Eastern England but also in North Wales. Two people died. Insurers calculated the cost of damage as £100 million.

31
Q

Effective responses- 2013 storm surge UK

A

Hundreds of thousands of properties protected by flood defences and the Thames Barrier was closed to protect London. Protects 4000 listed buildings, 4 world heritage sites and 116 railway and tube stations

32
Q

Impacts of 2013 storm surge 2013 the Netherlands

A

On the East Frisian coast it reached 3.7m above mean sea level. No one died.

33
Q

The Netherlands management

A

Constructed a series of Delta Works in response to the 1953 storm surge consisting of storm-surge barriers - cost 2.5 billion euros and 17 million euros to operate. These were closed against the 2013 storm surge.

34
Q

Storm surge, Cyclone Sidr, Bangladesh

A

Category 4 winds up to 223 km/hr. 6m in height. Breached many coastal and river embankments. Drinking water contaminated. The sanitation infrastructure was destroyed increasing risk of disease. 3,400 deaths.

35
Q

Bangladesh more effects

A

Total cost was estimated US$1.7 billion. Around 1.5 million houses destroyed.

36
Q

Maldives

A

Around 70% of the native Maldivian population are involved in fishing. The country has spent $96 million for climate change mitigation and adaptation from its state budget alone in 2022, which is over 30 times increase compared to a decade ago. Maldives has a population of 400,000.
Removal of mangrove swamps makes coasts very susceptible to eustatic change

37
Q

MFF (Mangroves For Future)

A

In 2006 MFF set up by countries most affected by the 2004 Indian tsunami

38
Q

Maldives management

A

Average ground elevation is 1.5m. The Global Environmental Facility has provided small grants to islanders to help develop sustainable and organic farming as an alternative food and income to coral reef fish. Money spent on capital Male and creating new artificial islands means that isolated islands are ignored.

39
Q

ICZM

A

Emphasises cooperation between all stakeholders so that everyone benefits it is a dynamic process of changing demands at the coast and decisions are likely to be increasingly concerned with sustainability

40
Q

Holderness coast location

A

East coast of England and low-lying agricultural Yorkshire

41
Q

Holderness coast geology

A

Boulder clay (soft rock), Chalk forms headland and Jurassic rock behind

42
Q

Holderness coast: causes of erosion

A

Soft Boulder clay - becomes saturated - mass movement - unstable - erosion

43
Q

Holderness coast erosion impacts

A

Decrease in tourism
Gas terminal in Easlington - supplies 25% of gas in the UK
Around 30 villages lost since Roman times
Fastest eroding coastline in Europe 2m per year

44
Q

Management holderness coast

A
  • Northern part does not need protection headland shelters the area
  • Gabions used to protect villages
  • Hornsea is a holiday resort £1.5 million on groynes
  • Beach nourishment
    AIM TO HOLD THE LINE
    ICZM
  • Welwick salt marsh protected - conservationists happy,!
  • 32 properties likely to be lost in erosion
45
Q

Lyme Regis management

A
  • Cliff stabilisation
  • Sea wall £20 million project building a 390m sea wall in front of the existing wall
  • Wide sand and shingle beach
  • Rock armour placed in front of the sea wall to absorb wave energy and retain the beach
  • Promenade over sea wall (social benefits)
    Involved 4 stages from 1990- 2015
  • The local economy depends on tourism as a major source of income and jobs. 37,500 people are employed in tourism in Dorset.
46
Q

Medmerry - Managed retreat

A
  • West Sussex
  • Created clay banks to divert seawater
  • Used to spend £0.2 million on management
  • Salt marsh acts as a natural buffer and allows high levels of biodiversity and salt marsh beef
47
Q

Rocky shores

A

Rocky coasts (high and low relief) result from resistant geology
(withstands erosive forces of sea, rain and wind), often in a
high-energy environment

48
Q

Coastal plain landscapes

A

(Sandy and estuarine coasts) are found near areas of low relief
and result from supply of sediment from different terrestrial
and offshore sources, often in a low-energy environment.

49
Q

Give examples of coastal morphology

A

Haff coasts
Dalmation coasts
Headlands and bays

50
Q

Give examples of geological structure that influences coastal morphology and erosion rates

A

Jointing, dip, faulting, folding

51
Q

Dip

A

Dip is the angle of inclination of the rock strata from the horizontal. It’s a tectonic feature. Sedimentary rocks are deposited horizontally, but can be tilted by folding and faulting by tectonic forces. It can have dramatic effects on cliff profiles.

Horizontal dip produces a vertical, or near-vertical profile, with notches reflecting weathering and small scale mass movement of strata that are jointed or more easily eroded.

High angle of seaward dip (>45) produces a sloping, low-angled profile with one rock layer facing the sea; vulnerable to rock slides down the dip slope when uppermost strata are attacked by sub-aerial processes. The profile slopes corresponding to that of strata dip. Bedding planes between strata are weakly bonded and readily loosened by weathering.

Low angle of seaward dip (<45) produces a steep profile, that may even exceed 90 degrees, creating areas of overhanging rock; very vulnerable to rock falls. Frequent small-scale mass movement of material weathered from cliff face. Major cliff collapse when undercutting by marine erosion makes overhang unsustainable.

Landward dipping strata produces steep profiles on 70-80’ as downslope gravitational force pulls loosened blocks into place. Very stable profile with few rock falls.

52
Q

Folding

A

Folds are bends in rocks. They are produced by sedimentary rock layers being squeezed by tectonic forces. The two main types are anticlines and synclines.
Folded rock is often more heavily jointed, meaning they are more easily eroded.

It also increases erosion rates by increasing angle of dip, and by causing joint formation.

53
Q

What are coastal micro-features?

A

Caves, wave-cut platforms and wave-cut notches

54
Q

Lithology effects cliff profiles and recession rates

A

Differential erosion of alternating strata in cliffs
(permeable/impermeable, resistant/less resistant) produces
complex cliff profiles and influences recession rates.

55
Q

Salt marsh formation

A

A salt marsh begins when mud and silt are deposited along a sheltered part of the coastline. This is because rates of deposition are greater than transportation due to the lack of energy in the waves. Often salt marsh is found on the inside of a coastal spit.Due to the sediment and material accumulating, it gets covered by the tide less. This and rain will leach (wash out) some of the salt. As the salt is now lower in concentration, it means more plants can start to grow in the more fertile soil. Colonisation occurs.

56
Q

Sediment cells: Dynamic equilbrium

A

Dynamic equilibrium in a sediment cell is where input and
outputs of sediment are in a constant state of change but remain in balance. The dynamic equilibrium may be upset in the long term by human interventions, or in the short term it may be interrupted by natural variations. Within each sediment cell there are smaller subcells. Often the smaller subcells are used when planning coastal management projects.

57
Q

Sediment cells: Negative feedback loop

A
  1. When the destructive waves from the storm lose their energy excess sediment is deposited
    as an offshore bar.
  2. The bar dissipates the waves energy which protects the beach from further erosion.
  3. Over time the bar gets eroded instead of the beach.
  4. Once the bar has gone normal conditions ensue and the system goes back to dynamic
    equilibrium.
58
Q

Sediment cells: Positive feedback loop

A

this exaggerates the change making the system more unstable and
taking it away from dynamic equilibrium:
1. People walking over sand dunes destroys vegetation growing there and
causes erosion.
2. As the roots from the vegetation have been holding the sand dunes
together, damaging the vegetation makes the sand dunes more
susceptible to erosion. This increases the rate of erosion.
3. Eventually the sand dunes will be completely eroded leaving more of the
beach open to erosion taking the beach further away from its original state.

59
Q

Mass movement creates distinctive landforms

A

Rotational scars, talus scree slopes, terraced cliff profiles

60
Q

What formations does sea level change result in?

A

Sea level change has produced emergent coastlines (raised
beaches formed from wave-cut notches above sea level with fossil cliffs an old cliff displaying features such
as caves, arches and stacks.) and submergent coastlines (rias,
fjords and Dalmatian).

61
Q

What is turbinal groyne syndrome?

A

When the coast becomes vulnerable after groynes due to reduced deposition.

62
Q

What is strategic realignment?

A

Managed retreat

63
Q

Headlands and bays - rock resistance

A

Softer and uncemented sediment and rock are vulnerable
to cliff retreat. Igneous rocks have a stronger crystalline structure that
Joints and fractures in the rock result in more complex coastal landforms
– e.g. faults can be exploited to form caves, which cut through to form
arches, the tops of which collapse to form stacks, which over time are
undermined and collapse to form stumps.

64
Q

Example of igneous rock coastline

A

Much of the north Cornish coastline is formed by steep cliffs of igneous rocks such as basalt and granite

65
Q

British geological society

A

An NGO that looks at data and their new dataset has been designed to assist future planning, with resilience considerations based on the natural geological characteristics of the coastal region.

66
Q

What stabilises beaches, recurved and double spits,
offshore bars, barrier beaches and bars, tombolos and
cuspate forelands?

A

Plant succession

67
Q

Horizontal bedding

A

These are natural horizontal cracks that are breaks in strata caused by gaps in time during periods of rock formation.

68
Q

Knock cliff - Isle of Wight

A

Has a rapid rate of cliff retraeat as a result of a layer of permeable rock overlaying a layer of permeable gault clay when it rains water percolates through the GAULT CLAY as a result there is lubrication slip created between the two rocks which leads to rotational slumping so high rates of coastal recession.

69
Q

Swanage

A

The coastline at Swanage is made up of: Bands of hard rock (e.g. chalk). Limestone. Soft clays.
Sands.18 timber groynes put in place in 2005 and 90,000m3 of sand deposited on the beach

70
Q

Lithology

A

Is the hardness or rock strength/make up

71
Q

If a cliff is steep/quasi-verticle what does this suggest about its resistance?

A

It is resistant

72
Q

What influences rate of recession?

A
  • Wind direction
  • Fetch
  • Tides
  • Seasons
  • Weather systems
  • Storms
  • Geology
  • Human management
73
Q

Happisburgh management

A

Norfolk coast it has a population of 1400 people. Houses that used to be over 6 metres from the cliff edge are now about to fall into the sea. Very large fetch. Managed retreat is official policy but the local council funded extra rock armour in 2015 9000 tonnes of rock armour were realigned.

74
Q

Transportation

A

Traction, saltation, solution and suspension

Physical Geography (5 decks)

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