Coasts Flashcards

(71 cards)

1
Q

What causes waves?

A

Friction with the wind+surface of the water.
Wind picks up the water to create waves.

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2
Q

Why are some waves stronger than others?

A

1) if wind is strong (fast windspeed)
2) if wind has blown a long time
3) Long fetch (distance wave has traveled)

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3
Q

Explain what makes a wave break.

A

As the wave comes into the shore the botom of the wave slows down as it touches the sand. (friction with sea bed) So the top of the wave speeds up and topples over/ breaks.

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4
Q

How does the wave type affect the coastline?

A

Constructive - stronger swash so material deposited/deposits material and builds up beach.
Destructive - have stronger backwash so errodes the coastline

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5
Q

What are the two types of waves?

A

Constructive waves
Destructive waves

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6
Q

What are the characteristics of destructive waves?

A
  • short wavelength = frequent
  • short swash
  • strong backwash
  • steep beach as waves errode material
  • tall = lots of energy
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7
Q

What are the characteristics of constructive waves ?

A
  • long wavelenth = less frequent
  • short
  • log strong swash
  • short backwash
  • deposits material = wide flat beaches
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8
Q

What are the three types of processes that shape the coastline?

A

Erosion - wearing away
Transportation - moving
Deposition - put down

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9
Q

What are the three types of erosion?

A

Abraision
Attrition
Hydraulic action

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10
Q

Explain what hydraulic action is.

A

The force of waves traps air in cracks. This process is repeated over time untill the air pressure breaks of pieces of rocks.

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11
Q

Explain what abrasion is.

A

The waves throw pebbles and rocks against the cliffs wearing them away.
Abraid the rock.

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12
Q

Explain what attrition is.

A

The pebbles and rocks are worn away as they crash against eachother.

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13
Q

Name the types of Transportation.(4)

A

Traction
Saltation
Suspension
Solution

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14
Q

Explain the process of longshore drift.

A

Prevailing wind moves waves up the beach at an angle. The swash moves up the beach at the same angle, and the backwash is moved back down with gravity. This movement transports material along the the coast, parallel to the shoreline.

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15
Q

Explain the four types of transportation.

A

TRACTION Larger rocks roll on the sea bed
SALTATION small rocks bounce along the sea bed
SUSPENSION mud or sand particals float in the water
SOLUTION minerals like salt are dissolved in the water

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16
Q

What is deposition?

A

When a wave puts down/drops material like sand, shingle, rocks or mud.

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17
Q

Why does deposition happen? (3)

A

Deposition happens when a wave loss energy,
- when a wave spreads out
- when it meets an obsticle
- less windy in sheltered areas

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18
Q

What is the difference between erosion and weathering?

A

Errosion is the breakingdown of rock by water mostly at the bottom.
Whereas weathering is the breakingdown of rock usualy at the top of a cliff.

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19
Q

What is mass movement?

A

The downward of rock or soil due to gravity caused by weathering of rock and heavy rainfall.

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20
Q

What is chemical weathering?

A

The breakdown of rocks by changing chemical composition.
eg. carbonation rainwater.

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21
Q

Explain how carbonation works?

A

Rainwater is a weak carbonic acid it dissolves rocks that contain calcium carbonated.

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22
Q

Name and explain one process of mechanical weathering.

A

FREEZETHAW. Rainwater gets into cracks in the rocks.
When the rainwater freezes it expands putting pressure on the rock and making the crack bigger.
This repeatedly happens - melting, thawing and expanding the crack.
Untill crack causes the rock to break off.

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23
Q

Name three types of mass movement.

A

Slumping
Slides
Rockfalls

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24
Q

Describe the mass movement sliding.

A

Downhill movement of a large ammount of rock and mud. Occurs when cliffs are weakened by weathering. Heavy rainfall infiltrates soil making it heavier. Saturated heavier mass falls in a straight line moving fast.

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25
What is slumping?
Rainwater **soaks** into the rock. It becomes too **heavy** and starts to **slide down** on the cliff. Happens very **slowly**, rock slump stays for a **long time.**
26
Describe the mass movement rock falls.
Bare well jointed rocks are prone to mechanical weathering which results in falling rocks losing contact with the cliff face. OR Large rockfall with no support and waves erroding the bottom. Differs in size of rocks falling.
27
How does rock type affect land forms?
Hard rocks - **interlocking bonds** which are **very** resistant to different errosion. Softer rocks - **clastic** and **less** resistant
28
What is a discordant coastline?
Where rock types run perpendicular to the coastline.
29
Explain how bays and headlines are formed.
Formed on a **discordant** coastline, soft rock found next to hard rock lies **perpendicular** to the sea. Waves errode the soft rock **more quickly** by abraision because bonds are **clastic** so less resistant. So bays are formed here. Waves errode hard rock **more slowly** because bonds are **interlocking** so hard rock is left **sticking into the sea** to form a headland.
30
What is wave refraction?
Headlands sticking out into the sea cause waves to **bend**. Waves **converge** around the headland, the wave has refracted. Energy has **concentrated on the sides** of the headland. Waves in bays are **spread out** so they **lose energy**.
31
How do wave cut platforms form?
1) At high tide waves hit the **base of the cliff** 2) This **errodes cracks** in the cliff by HA creating a wavecut **notch** 3) Rock above has **no support **so **colapses** 4) Colapsed rock is **broken down** by attrition+hurled against cliff abraiding it further 5) Cliff **receeded** leaving a wave cut **platform**, continues to receed this way untill it loses energy. | HA hydraulic action
32
Explain the formation of a stack.
- Large cracks in the rock opened by **HA** - This is **enlarged** by erosion to form a **cave** - To form an arch waves must converge on **either side of a headland** to form **caves** which may **join**. - The top is weathered by mechanical weathering that **weakens the rock** making it **unstable** - The arch can nolonger support its weight so it **colapses** - Leaving a tall rock, a **stack**. The stack is **eroded** to form a **stump**.
33
How does wave refraction impact the erosion of a headland.
Because of wave refrection, where waves converge around a headland focusing their energy on either side, caves occur on either side of a headland and may join to form an arch. | what wave refraction is, caves to arch.
34
Explain how and arch forms.
Large cracks in a headland are **opened** by HA. These cracks are **enlarged** to form **caves**. Waves **converge** on either side of the headland they form caves, **Arches** are formed when these **two caves join**.
35
What are beaches ? (depositional landforms)
A landform that sit **between high and low tide levels** formed by **constructive waves**. They occur when a wave loses energy so it **deposits material building up the beach**. Found in **sheltered areas**. Beaches are a **barrier between the land and sea** that can slow/**prevent coastal errosion.**
36
Name some depositional landforms.
Beaches Sanddunes Spits Bars
37
# Define: Embryo dune, Windward, Leeward Water table, Dune slack, Marram grass, Crest | (sand dunes)
1) new formed sand dune closest to sea 2) slope that faces the wind 3) sloap that faces away from wind 4) upper horisonal limit of wet sand 5) low points in sand dunes 6) plant found in sand dune with long binding roots 7) top of sand dune
38
How is a sand dune formed?
When sand is moved up the beach by **Wind **saltation **obsticles** cause the wind speed to decrease so it **deposits** the sand.This build up over time forming **hummocks**. Sand is often **inhabited by plants** that stabilize it causing more to **accumulate**. Forms embryo dunes. The oldest dunes overtime endup inland as **newer ones form closer to the sea**.
39
Why are sand dunes unusual in terms of coastal formations?
They are a coastal formation that is formed by the wind not the sea.
40
Why is sand deposited when it meets an obstacle on the beach?
The obsticle causes windspeed to decrease so wind loses energy and deposits material.
41
What are three main things that need to happen to make a spit?
- Longshore drift - A change in direction of the coast - Lots of sand/shingle
42
What forms behind a spit?
Salt marshes and Mud flats
43
What is deposited and why does deposition occur behind a spit?
The river deposits mud behind a spit because its sheltered so water loses energy so deposits sediment its carrying. Mud builds up → mudflats → saltmarshes +plants+wildlife
44
How are spits formed? | ( mention hook)
They occur where the coastline **suddenly changes** shape or at the mouth of a river. **Sand is moved** by Longshore drift because **prevailing wind **moves waves up the beach at an angle. When the coastline changes direction sand is **deposited** and overtime builds up a **sand ridge**, called a spit, which continues to grow. **Wave refraction** moves material forming a **hook**. Saltmarshes are formed **behind**.
45
Explain how a bar is formed.
A bar is a long **narrow stretch** of pebbles and sand which grows across a **bay** attatched to land at both sides. Forms when **longshore drift **occurs on a coastline. When the coastline **changes direction** and Longshore drift **continues** to **transport material** and deposit it in the sea. Eventualy a **sand ridge** forms. If spit develops over a **bay** it may build across two headlands forming a **bar**. **Lagoon** brackish behind.
46
Name four types of hard engineering.
Sea wall Rock armour Gabbions Groynes
47
Name four types of soft engineering.
Beach Nourishment Beach Reprofiling Dune regeneration Managed retreat/ coastal realignment
48
What is hard engineering?
Man made structures built to control the flow of sea **to reduce flooding and errosion.** - building a **physical structure** - **stops natural processes** - often expencive.
49
What is soft engineering?
Scemes that **work with the natural processes** to reduce the effects of flooding and errosion.
50
How does a Seawall prevent coastal errosion?
Creates a barrier between the land and sea. When the sea hits the wall it **loses energy**. Usually made out of **concrete**, modern versions have a **curved surface to reflect** and **absorbe wave energy**. Wave return wall.
51
How does Rock armour prevent coastal errosion?
Physical barrier that stops the sea erroding and flooding. **Organised pile** of hard **resistant rocks** that are places at an **angle** And wave energy is **dispersed in the gaps**.
52
How do gabbion's prevent coastal errosion?
Steel wire mesh **cadges filled with pebbles** and rocks and placed **against cliffs** so that waves enter the **cages which dissipate energy**.
53
How do Groynes prevent coastal errosion?
Wooden or stone structures **built at right angle **to the beach, that stretch out to sea. **Prevent Longshore drift** as sand builds up on one side of the beach **= larger beach**. Larger **beach absorbes more wave enregy** so land behind is **protected**.
54
What are some advantages and disadvantages of Seawalls? | 3/3
ADVANTAGE - long term solution - can be used as a promenade - effective DISADVANTAGES - expencive to build and maintain - not aestheticaly pleasing - can increase scouring | scouring = strong back wash bc of wave return wall.
55
What are some advantages and disadvantages of Rock armour? | 4/4
ADVANTAGES- less expenc. than sea wall - quick to build - looks natural - effective, ignious rocks DISADVANTAGES - big rocks can be dangerous - reduce acess - rubbish can collect in gaps - expencive
56
What are some advantages and disadvantages of Gabbions? | 2/3
ADVANTAGES- much cheaper than sea wall - gaps in rocks disperse wave energy DISADVANTAGES - metal is dangerous, corrodes quickly - needs mainenance - wont last long
57
What are some advantages and disadvantages of Groynes?
ADVANTAGES - much cheaper - encourages more beach to form - doesnt restrict acess - good looking DISADVANTAGES - stops LDS further down the coast - wooden ones will not last for as long. | LSD long shore drift
58
Explain how hydraulic action causes erosion to coasts.
Hydraulic action is a form of coastal erosion. It happens when the waves break against the cliffs and over long periods of time it makes pieces of the cliff break off. Hydraulic action happens when the waves break against the cliff. Air is trapped between the sea water and the cliff. The wave keeps going and forces the compressed air into cracks in the cliff. Waves continue hitting the cliff and forcing air into cracks in the cliff. Eventually, this begins to enlarge the crack and erode the rock.
59
How does Beach nourishment reduce the effects of erosion?
Adding or replacing sand+pebbles on a beach. Because beaches are the best natural form of defence, they absorbe wave energy. Sand is taken from other beaches or the sea bed.
60
How does Beach Reprofiling reduce the effects of erosion?
Articicial reshaping of the beach using existing beach material. Wider beaches create a barrier between the Land and sea.
61
How does Dune regeneration reduce the effects of erosion?
Artificial creation of new dunes = putting down an obsticle and planting marram grass. Or restoring existing ones creates a barrier to absorbe the waves energy.
62
What is managed retreat or Coastal realignment?
Where areas of the coast are allowed to be flooded naturally. This is areas considered to be of low value : not used for housing or farmland. Flooding tjis land protects the land behind.
63
What are some advantages or disadvantages of Beach Nourishment? | 4/3
ADVANTAGES - cheap - looks natural - nicer beach = more tourists - doesnt prevent LSD, natural processes DISADVANTAGES - needs lots of maintainance - sand taken easily by destructive waves in storms. - sand taken from other beaches, with other habitats
64
What are some advantages or disadvantages of Beach Reprofiling? | 4/2
ADVANTAGES - small cost yearly - natural - using what is already on the beach - wide beach created DISADVANTAGES - needs to be done regularly - distruptive when being done
65
What are some advantages or disadvantages of Dune Regeneration?
ADVANTAGES - looks natural - very cheap - creates habitats - long lasting once grown DISADVANTAGES - does take time for sand to form - restricts areas of the beach
66
What are some advantages or disadvantages of Managed retreat?
ADVANTAGES - creates new habitats - protects the land behind DISADVANTAGES - low valued land may still be used for some famers and homes - still a loss of land
67
List some Physical reasons to why the Holderness coastline is eroding so quickly (4)
**Narrow beach**dosnt stop waves hitting the cliff base **Climate change** increasing storms so more strong waves errode the cliff **Soft Rock** boulder clay so less reststant to erosion **Strong Waves** fetch of waves is 500-800km across the north sea
68
List some Human reasons to why the Holderness coastline needs coastal management schemes (3)
**Easington gas terminal**, company supplies 1/4 ok UK gas supply **Tourist econemy** creates jobs and wealth for the area **Large poulations** at Bridlington, Hornsea, withernsea and Mappleton.
69
What coastal management schemes have been put inplace on the Holderness coastline?
Bridlington= 4.7km sea wall Hornsea= concrete seawall, rock armour & groynes Mappleton = rock groynesx2 Withernsea= rock armour & sea wall Easington= rock reventments at cliff bottom Spun head spit= managed retreat
70
Why have areas of the Holderness coastline been protected?
- There are towns and villages like Hornsea (+8000 people) - Important infrastructure, road linking many towns up across that coast - Easington gas terminal with 1/4 of UK gas supply is close to the edge of the cliff.
71
Why may coastal management cause conflict?
Schemes can be successfull but still cause conflict as people have different oppinions on what should be protected and there is a finite amount of money. - schemes can increase errosion down the coast eg. GreatCowden farm. - little compensation is given for the unprotected - loss of important habitat eg. Spurn head spit - Vast ammounts of money is spent on some areas eg. Easington