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Physical Geography > The Coastal Zone > Flashcards

The Coastal Zone Flashcards

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1
Q

Explain the formation of a wave:

A
  1. The wind blows over the sea creating ripples
  2. These ripples become bigger swells and the swells approach land
  3. The sea becomes shallower
  4. The bottom of the wave slows due to friction
  5. The top keeps going and forms a crest
  6. The crest topples forming a breaking wave
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2
Q

Name the two parts of a wave and define them:

A

Swash- The movement of the wave up the beach

Backwash- The movement of a wave back down the beach

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3
Q

What is fetch?

A

The distance the wind blows over the sea. A bigger fetch = a bigger wave

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4
Q

Name the 2 types of wave and their properties

A

Constructive: Waves created by shorter fetch, flatter, less powerful, stronger swash and deposit sediment
Destructive: Waves created by a larger fetch, taller, more powerful, weak swash, strong back wash, erode the coastline

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5
Q

What is erosion?

A

The wearing down of rock by moving forces. This usually occurs at the base of cliffs and by waves.

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6
Q

What is weathering?

A

The breakdown of rocks in situ (in their original location without them being moved away). This produces finer particles that can then be removed away by mass movement, transportation and erosion.

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7
Q

What is mass movement?

A

The movement of rock downhill under gravity. Weathering & mass movement work together. Cliffs are weakened by weathering, pieces of rock are loosened and they fall away

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8
Q

What’s mechanical weathering?

A

The breakdown of the rock without any changes to the minerals that form the rock (includes freeze thaw and exfoliation). Sometimes called physical weathering.

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9
Q

What’s freeze-thaw weathering?

A

Water enters a crack or joint in a rock, freezes and expands exerting pressure on the rock. Repeated freeze thawing shatters a rock. Sometimes called frost shattering.

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10
Q

What’s exfoliation?

A

In hot, dry climates the outer layers of rock heat up quicker than the inner layers. Repeated heating and cooling peels off the outer layers. Sometimes called onion skin weathering, think exfoliating face

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11
Q

What’s chemical weathering?

A

When the rock’s mineral composition is changed, leading to the disintergration of the rock. It occurs mostly in moist, warm environments.

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12
Q

What’s biological weathering?

A

Caused by plants and animals- they speed up mechanical weathering with their roots and burrowing. Organic acids released by organisms may also speed up chemical weathering

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13
Q

Name the 4 different types of erosion and their definitions?

A

Hydraulic action- The power and weight of the water breaking against the coastline
Abrasion- The breaking waves throw sand and sediment against the cliff face
Attrition- particles carried in the wave rub against
eachother and are worn down
Corrosion- the action of acids and salts in the sea water corroding the cliff face

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14
Q

What’s longshore drift?

A

Movement of sediment in a zig zag pattern up and down the shore with the swash and backwash. The direction of longshore drift is dictated by the direction of the prevailing wind. (It’s a process of transportation)

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15
Q

Name the 4 types of transportation and their definitions?

A

Traction- the rolling of large boulders on the seabed
Saltation- the bouncing of smaller boulders on the seabed
Suspension- when sediment is carried in the body of the water
Solution- when sediment is dissolved in water

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16
Q

What’s deposition?

A

The dumping of sediment by the sea (constructive waves). It occurs when the waves lose energy, often when they enter a bay.

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17
Q

Deposition creates what?

A

Beaches

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18
Q

What’s a headland?

A

An area of hard rock protruding outi into the sea. The geology of this headland is limestone.

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19
Q

What’s a bay?

A

An are of soft rock creating an inlet or embayment. The geology of the bay is clay.

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20
Q

How are bays and headland formed?

A

Where rocks of different hardness and resistance to erosion meet the sea, the weaker rock is eroded back more quickly to form bays. Harder more resistant rock is left protruding out as prominent headland either side of the bay.

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21
Q

What is a cliff?

A

The most widespread landform of coastal erosion - a sheer rock face formed by erosion

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22
Q

What is a wave cut notch?

A

A cutting that forms in the base of the cliff, between the high and low water mark, by hydraulic action and abrasion

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23
Q

What is cliff recession?

A

Cliffs retreat when destructive waves attack the bottom of the rock face between the high and low water mark. Hydraulic action and abrasion undercut the cliff, forming a wave cut notch, the notch increases until the cliff is unsupported and it collapses. This repeats and the cliff retreats.

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24
Q

What is a wave cut platform?

A

As the cliff retreats, a new landform known as a wave cut platform is left where the old cliff face once stood.

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25
Q

How does a cave form?

A

A line of weakness in a cliff face (a crack or fissure) is widened by hydraulic action and abrasion

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26
Q

How does an arch form?

A

When waves (hydraulic action and abrasion) erode through the cave in the headland to form an arch

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27
Q

How does a stack form?

A

When the top of an arch becomes unsupported and collapses leaving a stack

28
Q

How does a stump form?

A

When a stack is continually eroded by hyrdaulic action and abrasion, it’s reduced to a stump

29
Q

What is a beach?

A

The gently sloping area of land between high and low water marks, created by contructive waves and longshore drift. They are composed of sand, shingle or pebbles

30
Q

What’s a spit?

A

A long narrow ridge of sand or shingle that extends into the sea, found where there is a change in direction of coastline or at the mouth of an estuary

31
Q

How is a spit formed?

A
  1. Longshore drift transports sediment down the coast in the coast in the direction of the prevailing wind
  2. Longshore drift begins to deposit sediment out away from the coast (change in the shape of the land)
  3. A long tongue of sediment builds up, known as a spit.
32
Q

What’s a bar?

A

A ridge of sand or shingle across the entrance to a bay or river mouth, linking two headlands. The enclosed area behind is called a lagoon.

33
Q

What’s a tombolo?

A

A ridge of sand or shingle (where a spit grows) that links the mainland to an off shore island.

34
Q

What’s a tombolo?

A

A ridge of sand or shingle (where a spit grows) that links the mainland to an off shore island.

35
Q

Why are sea levels rising?

A
  1. Thermal Expansion: As the temperature rises, the sea absorbs more heat and the water expands, increasing the sea level
  2. Ice Sheets/glaciers melting: Ice sheets in Greenland and Antarctica are melting faster than the snow is replacing them, land glaciers are melting increasing the sea level
  3. Post glacial rebound: Land (north of uk) that was weighed down by ice sheets/glaciers is rising, meaning the south is sinking -prone to flooding
36
Q

What and where is Tuvalu?

A

It’s a Polynesian island (a coral atoll) in the Pacific Ocean

37
Q

What are Tuvalu’s biggest threats?

A

King tides: the highest tide that Tuvalu has, it’s getting higher by 5mm each year
Storm surges: Storms rage in the Pacific as they hit the shore, the surface of the sea rises, flooding the land
Groundwater flooding: the thin cora soils are porous. This means salty sea water comes up through the pores in the ground (salt intrusion)

38
Q

What are the environmental impacts of the Tuvalu flooding?

A
  • Salt contaminate soil
  • Soil is eroded
  • Coral reefs are damaged (bleached)
  • Loss of habitats
39
Q

What are the social impacts of the Tuvalu flooding?

A
  • Tuvaluans are being forced to migrate to New Zealand
  • Families torn apart
  • Cultures and traditions are dying
  • Water borne diseases (typhoid, diarrohea)
  • Stress
40
Q

What are the economic impacts of the Tuvalu flooding?

A
  • 2 industries being hit
  • Bleaching of coral reefs reduces fish stock
  • Salt intrusion hitting agriculture
  • Downturn in GDP
  • Pulaka killed (cash crop)
41
Q

What are the political impacts of the Tuvalu flooding?

A
  • Government have to plan the migration of the remaining 10,000 inhabitants
  • Relies on aid from New Zealand
  • Government campaigning/trying to get voice heard
42
Q

What’s the current rate of erosion for the Holderness coast in Yorkshire?

A

2m per year

43
Q

What are the causes for erosion of the Holderness coast?

A
  • The coastline is made up of soft boulder clay
  • The cliffs are a mass of brown clay containing pieces of rock (erratics)
  • Soft clay sits on chalk
44
Q

What are the causes for erosion of the Holderness coast?

A
  • The coastline is made up of soft boulder clay
  • The cliffs are a mass of brown clay containing pieces of rock (erratics)
  • Soft clay sits on chalk
45
Q

What are the processes that erode the Holderness coast?

A

Attack from above:
-Soft boulder clay is saturated with rain water
-Chemical weathering in the summer, freeze thaw in the winter
-Cliffs fail and mass movement/landslide occurs
Attack from below:
-Large destructive waves
-Hydraulic action and abrasion (wave cut notches)
-Cliffs retreat, sediment removed by longshore drift

46
Q

How is the village of Mappleton being protected?

A
  • Shoreline management plan costing £2 million was introduced
  • Rock armour placed along the beach
  • 2 rock groynes built
47
Q

What is terminal groyne syndrome?

A

Rates of erosion are increased after the last groyne due to the sediment supply being cut off. Example: Mappleton, Holderness

48
Q

What are the 3 hard engineering strategies used to manage the coast?

A
  1. Sea walls: concret walls that deflect the force of waves/sediment away from the sea front. expensive
  2. Groynes: trap the sand which is carried along the coast by longshore drift. Waves break on the beach and not on the cliffs. terminal groyne syndrome
  3. Rock Armour: boulders and stones used to absorb wave energy, waves break on the armour. expensive
49
Q

What 4 soft engineering strategies are used to manage the coast?

A
  1. Beach nourishment: artificial extension of the beach to buffer &absorb wave energy. time consuming
  2. Marsh creation: the controlled flooding of the coast to create marshes, these absorb energy and flood waters. damages soil, loss of land
  3. Dune regeneration: the planting of marram grass at the back of beaches to stabalise the dunes, they buffer energy from the waves
  4. Managed retreat: when areas are left to flood naturally, involves moving homes and allowing farmland to be engulfed by the sea
50
Q

Where is Lyme Regis?

A

The Jurassic Coast, Dorset

51
Q

Why is Lyme Regis vulnerable?

A
  • It suffers from wave attack, strong westerly winds bring powerful destructive waves
  • Landslides are a major hazard
  • Chemical weathering and rock falls are common
52
Q

What hard engineering strategies are used in Lyme Regis?

A

Sea wall, rock armour, 2 stone groynes, drainage improvements, metal piling and soil nailing

53
Q

What soft engineering strategies are used in Lyme Regis?

A

Beach nourishment, landslide early warning system

54
Q

What soft engineering strategies are used in Lyme Regis?

A

Beach nourishment, landslide early warning system

55
Q

What are the costs of the engineering strategies in Lyme Regis?

A
  • High cost (£21million)
  • Disruption to environmentally sensitive area
  • Temporary eye sore
  • Heavy maintenance burden
  • Intense changes to cliff habitats&coastal processes
  • Terminal groyne syndrome
56
Q

What are the benefits of the engineering strategies in Lyme Regis?

A
  • Safeguards 140 properties and businesses
  • Secures income from tourism (worth £94million a year)
  • Improvements in amenities
  • Access to seafront
  • Landslide early warning system installed
  • Reassured residents
57
Q

What’s a salt marsh?

A

An area of periodically flooded low-lying coastal wetlands, rich in plants, birds and animals.

58
Q

How do salt marshed develop?

A

They begin as a mixture of mud, sand and silt, deposition builds up sediment in a sheltered part of the coastline, salt tolerant plants move into the area, more species move into the area- succession

59
Q

What is succession?

A

A sequence of vegetation species that develops withhin an environment. Over time vegetation will develop from small tough plants to large complex shrubs and trees.

60
Q

Describe the steps of succession:

A
  1. Species move into the area- colonisation
  2. First species (pioneer) help to create more favourable conditions for other plants
  3. As conditions improve, more species move into the area- over hundreds of years, a succession of plants develops
61
Q

Where are the Keyhaven Marshes?

A

Southern Hampshire, behind Hurst Castle spit

62
Q

Why do the Keyhaven Marshes deserve to be protected?

A
  • Delicate ecosystem that supports wildlife

- Acts as a natural buffer to the sea

63
Q

Why are the Keyhaven Marshes under threat?

A
  • Loss of shingle
  • They’re receeding
  • Engineering work&groynes cut off the supply of mud&sediment that replenished the marshes
64
Q

What has been done to prevent the Keyhaven Marshes from disappearing?

A
  • 550m of rock armour
  • Armoured breakwater at beginning of spit
  • 100m of rock reventment was built at the eastern end of the spit
65
Q

How are authorities ensuring the sustainability of the marshes?

A
  • Marshes grazed to keep cordgrass and other species healthy
  • Footpaths clearly marked
  • Dog and litter bins
  • Footpaths on wooden ramps to prevent erosion
  • Dogs on leads
  • Close gates

Physical Geography (3 decks)

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