Coastal Environments (Excluding Case Studies & Investigating Coastal Environments)

Question 1

Describe the Characteristics of Constructive Waves

Answer 1

• Relatively Strong Wash
• Weak Backwash
• Build up the Beach
• Push Sand & Pebbles up the Beach
• Gently sloping wavefront
• Longer wavelength

Question 2

Describe the Characteristics of Destructive Waves

Answer 2

• Strong Backwash
• Relatively Weak Swash
• Steep, high waves which arrive in quick succession
• Remove material from the beach
• Causes erosion through processes such as hydraulic action.
• Steeper and Smaller Wavelength

Question 3

Define the term ‘erosion’

Answer 3

• Where materials are worn away and transported by natural forces such as wind or water.
• Involves the removal and breakdown of material and shaping of landforms – the wearing away of rock.
• The 4 main erosional processes are…
- Hydraulic Action
- Abrasion
- Attrition
- Corrosion (solution)

Question 4

Define the term ‘weathering’

Answer 4

• Describes the breaking down or
dissolving of rocks and minerals on the surface of the
Earth.
• Water, ice, acids, salts, plants, animals, and
changes in temperature are all causes of weathering.
• It does not involve the removal of rocks.
Weathering is broken down into three types
- Mechanical weathering
- Biological weathering
- Chemical weathering

Question 5

Define the term ‘mass movement’

Answer 5

The downward movement or sliding of material under the influence of gravity. Examples include:

• Rockfalls
• Slumps
• Mudflows
• Landslides

Question 6

Describe the process of ‘mechanical’ weathering

Answer 6

• Relates to changes in the atmosphere, temperature, and water.
• Caused by processes such as freeze thaw - When water gets into the cracks of rocks, freezes and expands putting pressure on the rock, the rock weakens resulting in rockfalls.

Question 7

Describe the process of ‘biological’ weathering

Answer 7

• Relates to animals and plants
• Caused by animals digging burrows and plant roots breaking up rocks.

Question 8

Describe the process of ‘chemical’ weathering

Answer 8

• Relates to acids and chemicals causing a reaction with the rock weakening it and changing the rock structure and dissolving them.
• Caused by acid rain, sea water dissolving the rocks (corrosion), etc.

Question 9

Describe the mass movement process of ‘sliding’ (landslides)

Answer 9

• When large amounts of rock suddenly break loose from a cliff or a mountainside. They move quickly.

Question 10

Describe the mass movement process of ‘slumping’

Answer 10

• A large area of land moving down a slope. This usually occurs on clay cliffs that become saturated during heavy rainfall, then ooze towards the sea as a mud/debris flow.
• Consists of Heads, Feet, Toes and Scarps

Question 11

Describe the erosional process of ‘hydraulic action’

Answer 11

• Water is forced into rocks or cliff faces squashing the air inside which blasts out when the wave retreats breaking up the rock/cliff face.

Question 12

Describe the erosional process of ‘abrasion’

Answer 12

• Smaller pebbles and rocks hit the cliff face repeatedly and thus erode it through friction causing the cliff to retreat.

Question 13

Describe the erosional process of ‘corrosion’

Answer 13

• The dissolving of rocks by sea water consisting of certain chemicals. Particularly evident amongst limestone and chalk cliffs.
• Also known as ‘solution’

Question 14

Describe the erosional process of ‘attrition’

Answer 14

• When stones carried in water knock into each other making the stones smaller and rounder which can then be deposited by constructive waves building up the beach.

Question 15

Describe the transportation process of ‘traction’

Answer 15

• Large particles like boulders are pushed along the bottom of the sea bed by the force of the water.

Question 16

Describe the transportation process of ‘saltation’

Answer 16

• Pebble sized particles are bounced along the sea bed by the force of the water.

Question 17

Describe the transportation process of ‘suspension’

Answer 17

• Small, fine particles/sediment are carried along by the water

Question 18

Describe the transportation process of ‘solution’

Answer 18

• Soluble materials dissolve in water and are carried along.

Question 19

Describe the process of ‘longshore drift’

Answer 19

• Form of transportation
• The movement of sediment along a beach in a zig zag pattern. Groynes can help to prevent this.
• Prevailing winds make the waves come in at an angle and then retreat slowly moving material along the coast.
• Key in the formation of spits.

Question 20

Define the term ‘deposition’

Answer 20

• Where material is left behind when there is a loss of energy via constructive waves when the conditions are calm - usually in summer.

Question 21

Describe how ‘geology’ affects the coast.

Answer 21

• An area of soft rock will erode more easily than one of hard rock.
• Geology affects the coastline…
- In plain view - headlands and bays
- Vertically - the heights and profile of cliffs

Question 22

Describe the role of ‘vegetation’ in coastal environments

Answer 22

• The longer a coastal landform has been in place, the more likely it will be colonised by vegetation.
• Vegetation has to cope with high salinity in the air and soil.
• Vegetation can protect a cliff.
• It binds the soil together as in salt marshes, e.g. sea purslane.

Question 23

Describe how ‘sea-level changes’ can affect coastal environments

Answer 23

• Global warming and climate change could lead to low lying coasts being drowned by rising sea levels.
• It could also lead to the formation of raised beaches from sea levels falling.

Question 24

Explain the terms ‘isostatic’ and ‘eustatic’

Answer 24

• Isostatic - Local changes caused by subsidence or uplift of the crust related either to changes in the amount of ice on land or growth of erosion of mountains.
• Eustatic - Global changes to the volume of water in the ocean and seas for example - ice caps melt and sea levels rise on a much larger scale.

Question 25

Describe how ‘human’ activities affect coastal environments

Answer 25

• Settlement - coastal lowlands attracted people and their settlements.
• Economic Development - fishing, agriculture, industry, tourism, etc.
• Coastal Management - people have tried to control the coastline.

Question 26

Define the terms ‘concordant’ and ‘dis-concordant’ coastlines

Answer 26

• Concordant - Same type of rock along its length, coves are common on concordant coastlines.
• Dis-concordant - Different types of rock along its length consisting of headlands (piece of land jutting out into the sea) and bays (coastal inlets).

Question 27

Explain the formation of ‘headlands’ and ‘bays’

Answer 27

Headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock (dis-concordant)
The bands of soft rock, such as sand and clay, erode more quickly than those of more resistant rock, such as chalk. This leaves a section of land jutting out into the sea called a headland. The areas where the soft rock has eroded away, next to the headland, are called bays.

Question 28

Explain how cliffs are formed.

Answer 28

• Cliff - A steep rock face, especially at the edge of the sea.
• They are formed via weathering, erosion and gravity determining the profile and steepness.

Question 29

Explain how a ‘wave-cut platform’ is formed

Answer 29

• The base of the cliffs is attacked by Destructive waves.
• These erode the cliffs by Hydraulic power and corrosion forming a Wave-cut notch.
• This gets larger until the cliff collapses.
• As the process is repeated many times the cliff retreats leaving a wave cut platform below exposing the bare rock .

Question 30

Explain the formation of caves, arches, and stumps.

Answer 30

• The sea attacks a line of weakness opening up the crack.
• Caves occur when waves force their way into cracks in the cliff face. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action is the predominant process.
If the cave is formed in a headland, it may eventually break through to the other side forming an arch.
The arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump - a third the height of the headland and is covered at high tide.

A good example of this is the Old Harry rocks in Dorset near Swanage bay.

Question 31

Explain how ‘beaches’ are formed

Answer 31

• Accumulation of sand and shingle (pebbles or smaller) found where deposition occurs along the coast.
• The sediments, which form beach, enter the coastal system from rivers, cliff erosion, and waves transporting and depositing it.
• Sand beaches are formed from constructive waves depositing smaller sediment as they have less energy.
• Whereas shingle and pebble beaches are formed from de-constructive waves with more energy that can carry bigger pebbles and stones.

Some common features of beaches include: berms, storm beaches, sand dunes, etc.

Question 32

Explain how ‘berms’, ‘storm beaches’ & ‘cusps’ are formed

Answer 32

• Berms - Terraces, usually on shingle beaches. Formed when sediment is pushed onto the beach under strong swash conditions and then not reached again for a period of time.
• Storm Beaches - An expanse of sand or gravel thrown up on the coast formed by storms throwing up large material.
• Cusps - Small semi-circular depressions formed by the movement of the swash and backwash of waves up and down the beach.

Question 33

Describe how ‘spits’ are formed

Answer 33

• Long narrow ridges of sand and shingle which project into the sea from the coastline.
• Formed by longshore drift. Develop in places where:
- Longshore drift moves large amounts of material along the beach.
- There is a sudden change of direction of the coastline.
- The sea is relatively shallow, sheltered and calm.

Question 34

Describe how ‘bars’ are formed

Answer 34

• When a spit joins to another piece of headland

Question 35

Describe how a ‘tombolo’ is formed

Answer 35

• When a spit joins to an island

Question 36

Explain how a ‘salt marsh’ is formed

Answer 36

• Formed in a low energy environment with shelter from the wind and a large input of sediment coming from the sea and river.
• As the mud stars to accumulate (coastal accretion) reduces the length of flooding allowing vegetation to grow.
• This binds the sediment together so more can be built up and the marsh grows over time.

Question 37

Explain how a ‘sand dune’ is formed

Answer 37

• Ridges or hills of sand found at the top of a beach, above the usual maximum reach of the waves.
• Formed when dry sand is blown inland by the wind to form dunes. Over time, the sand forms a series of ridges running parallel to the coastline. They eventually stabilise when vegetation takes root.

Question 38

Define the term ‘fetch’

Answer 38

• Distance that a wave has travelled

Question 39

Describe the process of cliff erosion

Answer 39

Weather weakens the top of the cliff.
The sea attacks the base of the cliff forming a wave-cut notch.
The notch increases in size causing the cliff to collapse.
The backwash carries the rubble towards the sea forming a wave-cut platform.
The process repeats and the cliff continues to retreat.

Question 40

Explain the four main factors affecting the distribution of coral reefs.

Answer 40

(a) TEMPERATURE - Coral needs water temperature to be a minimum of 18 degrees Celsius although grows best in temperatures between 23 and 25 degrees Celsius.

(b) LIGHT - Coral will be found in shallow waters because they need light to grow.

(c) WATER DEPTH - Coral will grow in waters less than 25 metres deep because it needs light to grow.

(d) SALINITY - coral can only survive in salty waters.