Coasts

Question 1

Explain the 4 different types of erosion

Answer 1

Hydraulic action: strong waves crash into the cliff face. Trapped air is blasted into holes and cracks in the rock causing them to break apart
Corrasion/abrasion: rocks being thrown into the cliffs by waves and breaking off bits of the cliff
Attrition: rock fragments carried by the sea knock into each other, they break down and become smaller and more rounded
Solution: slight acidity of sea water causes bits of the cliff to dissolve

Question 2

What is deposition?

Answer 2

When eroded material is stopped by constructive waves

Question 3

What are destructive waves?

Answer 3

Fairly weak swash
Strong backwash 
Erode and transport material away from beaches 
Steep beaches 
Breaks downwards with great force

Question 4

What are constructive waves?

Answer 4

Flat and low
Strong swash
Weak backwash
Deposit material and build beaches up 
Gentle beaches

Question 5

What is coastal erosion?

Answer 5

The wearing away of the coast by destructive waves

Question 6

How do waves form?

Answer 6

Transfer of energy
Friction that occurs when wind blows over water
When it reaches the shore, the lower part slows due to friction with the sea bed but the upper part continues to move. It topples and breaks against the cliff face.

Question 7

What is the size and energy of a wave influenced by?

Answer 7

How long wind has been blowing
Strength of wind
How far the wave has travelled

Question 8

What is transportation?

Answer 8

The movement of material in the sea and along the coast by waves

Question 9

What are the 4 different types of transportation?

Answer 9

Traction: large material rolled along sea floor
Suspension: beach material is suspended and carried by waves
Saltation: beach material is bounced along sea floor
Solution: material is dissolved and carried by water

Question 10

What is longshore drift?

Answer 10

The process of waves moving material along a coastline

Question 11

How does longshore drift occur?

Answer 11

1. Waves approach the coast at right angles
2. The backwash is at right angles to the coast as this is the steepest gradient
3. The material will move up the coast

Question 12

How is a stump formed?

Answer 12

1. Lines of weakness such as faults/cracks occur in headlands
2. Abrasion and hydraulic action erode the fault to form a cave
3. The cave is widened and deepened
4. The sea cuts through to form an arch
5. The sea erodes the foot of the arch and widens it
6. The roof of the arch becomes too heavy and collapses
7. Part of the former cliff is now isolated as a stack
8. Over time, the stack is eroded and it might be undercut and collapse
9. A stump is the remains of the eroded stack

Question 13

How are cliffs formed?

Answer 13

When destructive waves attack the bottom of the rock face between the high and low water marks

Question 14

How are wave cut platforms formed?

Answer 14

1. Waves break against the cliff and erosion at high tide form a wave-cut notch
2. The notch gets deepened until the overlaying cliff collapses
3. A new wave cut notch is created and the sequence continues
4. The cliff line gradually retreats leaving a gently sloping wave cute platform. This is the gently sloping rocky area between the high and low water marks

Question 15

What is a spit and how is it formed?

Answer 15

A spit is a ridge of sand and shingle projecting from the mainland into the sea

1. Longshore drift deposits materials at an angle of about 45 degrees
2. The backwash, however is at right angles
3. The materials therefore move in a zig-zag fashion
4. There is deposition of material at the change of direction of the coast, which leads to the formation of a spit
5. Curving at the end may be caused by a change in wind direction

Question 16

What is a bar and how is it formed?

Answer 16

A bar is a ridge of sand and shingle which joins two headlands, cutting off a bay

1. A spit continues to grow as more material is deposited
2. Sometimes, the spit will eventually join two headlands forming a bar
3. The bay is cut off and a lagoon is formed

Question 17

What is a tombolo and how is it formed?

Answer 17

A tombolo is a ridge of sand and shingle joining the mainland to the land
Sometimes a spit will grow out from a headland and will eventually join the mainland

Question 18

How are bay and headline coastlines formed?

Answer 18

1. Where rocks of different hardness and resistance meet the sea, the weaker rocks are eroded back more quickly to form bays
2. In the shelter of a bay, constructive waves deposit material from elsewhere and beaches are formed
3. The stronger rocks resist wave attacks for longer and stand out as prominent rocky headlands.

Question 19

What is the difference between a concordant and discordant coastline?

Answer 19

Concordant coastlines are where bands of hard and soft rock run parallel to the coastline while discordant coastlines are where bands of hard and soft rock run perpendicular to the coastline

Question 20

What are sand dunes?

Answer 20

Small ridges/hills of sand found at the top of a beach above the usual maximum reach of the waves

Question 21

How are sand dunes formed?

Answer 21

1. Sand dries out
2. Wind picks up particles of sands from beaches, especially at low tide
3. The sand is deposited around an obstruction
4. The dunes build up over time from an embryo dune to an established dune

Question 22

What are the conditions needed for sand dunes to form?

Answer 22

A supply of dry sand over a wide beach
An area of low lying sand behind the beach
Predominantly onshore winds

Question 23

What are coral reefs?

Answer 23

A coral reef is a line of coral polyp found in warm, shallow seas. They are formed when polyps build limestone around themselves and then these foundations are used by other polyps. When the limestone foundations build up, they are called coral reefs.

Question 24

What are the conditions needed for coral reefs?

Answer 24

Minimum water temperature of 18 degrees (warm waters)
Light conditions 
Water depth of less than 25m 
Salty water-no less than 30-32psu
Clean, clear water

Question 25

Where are mangrove swamps formed?

Answer 25

On the coastline in an intertidal zone

Question 26

What conditions can mangroves endure?

Answer 26

``` Flooding of saltwater by the sea Flooding of freshwater by rainfall Alternating salt and temperature levels Choking mud They have special adaptations to help them survive ```

Question 27

Opportunities presented by coasts

Answer 27

Areas of beautiful scenery/good views/enjoy the scenery; Use by tourists/for leisure activities or example/income from tourism; Hiking/coastal paths; Fishing industry; Development of harbours/ports; People live there/residential/retirement.

Question 28

Hazards presented by coasts

Answer 28

``` Tropical storms Flooding High winds Hurricanes Landslides Tsunamis Storm surges ```