2.3: Coasts (Paper 1 and 2)

Question 1

State the types of Marine Processes: (4)

Answer 1

• Wave action from constructive and destructive waves
• Wind action
• Mass movements and weathering
• River and ice actions

Question 2

Describe the features of a destructive wave: (8)

Answer 2

• Short wavelengths (1)
• High height of more than 1 metre (1)
• High frequency of 10-12 per minute (1)
• Occurs once every 5-6 seconds (1)
• Weak swash and strong backwash
• Steep Gradient (1)
• Caused by local winds and storms (1)
• High energy waves (1)

Question 3

Describe the features of a constructive wave: (8)

Answer 3

• Long wavelengths (1)
• Low heights of less than 1 metre (1)
• Low frequency of 6-8 per minute (1)
• Occurs once every 8-10 seconds (1)
• Strong swash and weak backwash (1)
• Low Gradient (1)
• Caused by swelll from distant storms (1)
• Low energy wave (1)

Question 4

Explain the factors that affect coastal processes and coastal landforms: (4)

Answer 4

• Waves and currents: including longshore drift. (1)
• Local Geology: Rock type, structure and strength (1)
• Changes in sea levels (1)
• Human activity: Increased use of coastal engineering (1)

Question 5

Explain the erosional processes: (4)

Answer 5

• Abrasion (Corrasion): The wearing away of the cliffs by the load carried by the sea (1)
• Hydraulic Action: The force of air and water when the waves break (1)
• Solution (corrosion): The removal of chemical ions (1), especially calcium which causes rocks to dissolve. (1)
• Attrition: The wearing away of the load carried by the sea

Question 6

Explain the transportation processes: (4)

Answer 6

• Traction: Large particles that are dragged along the sea floor
• Saltation: Small particles that bounce along the sea floor.
• Suspension: Very fine materials that are held up in the water.
• Solution: Dissolved sediments like calcium that are carried by the water

Question 7

Explain what the word fetch means: (1)

Answer 7

• The amount of open water over which a wave has passed (1)

Question 8

Explain what is longshore drift and how it works: (5)

Definition: (1)
Explanation: (4)

Answer 8

• A process which transports material along the beach (1)
• Waves approach the beach at an angle similar to that of the wind. (1)
• The swash carries material up the beach following the angle of the waves. (1)
• The backwash will take the material down the beach at 90 degree angles no matter at what angle the swash moves up the beach. (1)
• This process continues and material is moved along the beach as a result. (1)

Question 9

State reasons why deposition occurs: (3)

Answer 9

• A decrease in wave energy or velocity (1)
• A large supply of material (1)
• An irregular or indented coastline, for example river mouths (1)

Question 10

Define the term coastal deposition: (1)

Answer 10

The build up of material on the beach or by the sea. (1)

Question 11

Explain how wave-cut platforms/notch are formed: (5)

Answer 11

• Many cliffs have a ‘knick-point’ around the high-water mark, called the ‘wave-cut notch’, which is where the wave has undercut the rock. (1)
• Abrasion, corrosion and hydraulic action further extend the notch back into the cliff. (1)
• As undercutting continues, the cliff above becomes unsupported and unstable and eventually collapses. (1)
• The backwash of the waves, carries away the eroded material, leaving behind a wave-cut platform. (1)

The process repeats and the cliff continues to retreat, leading to a coastal retreat. (1)

Question 12

Explain how a cliff is formed: (4)

Answer 12

• Cliffs form due to abrasion and hydraulic action being acted upon it. (1)
• Because the sea water carries rocks and sediments, when waves hit the cliff, it grinds away the rock. (1)
• As well as abrasion, when water hits the rock with such force, water and air rush into the cracks in the rock putting a lot of pressure. This is called hydraulic action. (1)
• The rock then eventually collapses due to the amount of pressure on it. (1)

Question 13

Explain how a cave, arch, stack and stump is formed: (7)

Answer 13

• Due to hydraulic action, a crack opens up in a headland. (1)
• The crack then grows into a cave caused by hydraulic action and abrasion. (1)
• As this continues, the cave gets larger. (1)
• The cave then breaks through the headland forming an arch. (1)
• Eventually, the arch is eroded and then it collapses. (1)
• This leaves a tall rock stack. (1)
• The stack is then eroded and forms a stump. (1)

Question 14

Explain how headlands and bays are formed: (4)

Answer 14

• A coastline faces the wave attack with discordant beds of sediment. (1)
• Wave attack in the form hydraulic action and attrition causes the cliff to retreat. (1)
• Less resistant rocks are eroded at faster rates to create bays and more resistant rocks stick out to the sea as headlands. (1)
• During calm periods, the sheltered bays allow deposition of beaches. (1)

Question 15

Explain how a beach is formed: (5)

Answer 15

• Beaches form in sheltered areas such as bays. (1)
• Deposition occurs through constructive wave movement, where the swash is stronger than the backwash. (1)

Beach formation usually occurs in the summer months when the weather is calmer. (1)

Sometimes sand from offshore bars can blow onto the shore by strong winds. (1)

Blown sand can create sand dunes at the backshore of a beach. (1)

Question 16

Explain how a spit is formed: (6)

Answer 16

• Sediment is transported by the action of longshore drift. (1)
• Where the coastline changes direction, a shallow, sheltered area allows for deposition of sediment. (1)
• Due to increased friction, more deposition occurs. (1)
• Eventually, a spit slowly builds up to sea level and extends in length. (1)
• If the wind changes direction, then the wave pattern alters and results in a hooked end. (1)
• The area behind the spit becomes sheltered
  Silts are deposited here to form salt marshes or mud flat. (1)

Question 17

Explain how coastal sand dunes are formed: (4)

Answer 17

• Windblown sand is deposited against an obstruction - pebble or driftwood. (1)
• As more sand particles are caught, the dunes grow in size, forming rows at right angles to the prevailing wind. (1)
• Over time, the ridges of the dunes will be colonized and fixed by vegetation in a process called succession. (1)

The first plants (pioneer species) have to deal with: Salinity, Lack of moisture as sand drains quickly (highly permeable) Wind, Temporary submergence by wind-blown sand, Rising sea levels. (1)

Question 18

Define the following terms:

• Coral Reef (1)
• Mangrove Swamp (1)

Answer 18

Coral Reef: an underwater ecosystem characterized by reef-building corals.

Mangrove Swamp: Coastal wetlands found in tropical and subtropical regions.

Question 19

Describe the conditions required for a coral reef: (3)

Answer 19

• Water with a temperature over 20 degrees celcious (1)
• Shallow coastal water is needed for light and photosynthesis. (1)
• A good supply of water and plankton. (1)

Question 20

Describe the conditions required for mangrove swamps:

Answer 20

• High humidity (75%-80%) (1)
• High rainfall per annum (1500-3000) (1)
• Ideal temperature to grow in is 27 degrees celcious (1)

Question 21

Explain the opportunities coasts provide for people: (7)

Answer 21

• Development of surrounding land
• Nature reserves
• Tourism
• Trade/Industry
• Fishing
• Agriculture
• Ports and Harbours

Question 22

Explain the hazards coasts bring to people: (4)

Answer 22

• Coastal Erosion: Coastal erosion threatens many islands placing residents and tourist resorts at risk. (1)
• Rising Sea Levels: This issue is made worse as many of the world’s densely populated areas are located on coastal lowlands. (1)
• Tropical Storms: Brings heavy rainfall, strong winds, floods and mudslides. (1)
• Tsunami Events: This causes homes to be damaged, boats washed away, forest damaged and infrastructure destroyed. (1)

Question 23

Explain the aims and methods of the following hard-engineering coastal managements: (9)

• Sea Walls (1)
• Revetments (1)
• Gabions (1)
• Groynes (1)
• Rock Armour (1)
• Offshore breakwaters (1)
• Rock strongpoints (1)
• Cliff drainage (1)
• Cliff regrading (1)

Answer 23

• Sea Walls: Large-scale concrete curved walls designed to reflect wave energy. (1)
• Revetments: Porous design to absorb wave energy. (1)
• Gabions: Rocks held in wire cages absorb wave energy. (1)
• Groynes: To prevent longshore drift. (1)
• Rock armour: Large rocks at the base of the cliff to absorb wave energy. (1)
• Offshore breakwaters: Reduce wave power offshore. (1)
• Rock strongpoints: To reduce longshore drift. (1)
• Cliff drainage: Removal of water from rocks in the cliff. (1)
• Cliff regrading: Lowering of slope angle to make cliff safer. (1)

Question 24

Explain the aims and methods of the following soft-engineering coastal managements: (4)

• Offshore reefs (1)
• Beach nourishment (1)
• Managed retreat (1)
• Do nothing (1)

Answer 24

• Offshore reefs: Waste materials, e.g old tyres, weighted down to reduce the speed of incoming wave. (1)
• Beach nourishment: Sand pumped from sea bed to replace eroded sand. (1)
• Managed retreat: Coastline allowed to retreat in certain places. (1)
• Do nothing: Accept that nature will win. (1)

Question 25

Define the following terms: (3)

• Fringing reefs: (1)
• Barrier reefs: (1)
• Atoll: (1)

Answer 25

• Fringing Reefs: Reefs that grow outwards around an island (1)
• Barrier reefs: A reef that is separated from the coast by a deep channel (1)
• Atoll: A circular reef enclosing a shallow lagoon (1)