Coastal Environments

Question 1

Constructive waves

Answer 1

• long wavelength
• strong swash
• weak backwash

Question 2

Destructive waves

Answer 2

• tall waves with short wavelength
• weak swash
• strong backwash

Question 3

What is fetch

Answer 3

Length of time and distance over open water that the wind has blown to create a wave

Question 4

Examples of erosion

Answer 4

• hydraulic action
• abrasion
• corrosion
• attrition
• etc etc

Question 5

What is hydraulic action

Answer 5

Waves hit cliffs and force air into cracks

Question 6

What is abrasion

Answer 6

Waves pick up pebbles and hurl them against the cliff

Question 7

What is solution (corrosion)

Answer 7

The dissolving of CaCO3 rocks (eg limestone or chalk) by the sea

Question 8

What is attrition

Answer 8

Pebbles carried by the waves collide with each other and become smaller and more rounded over time

Question 9

What is deposition

Answer 9

Occurs when waves lose energy material carried is too large to transport with the amount of energy the wave has

Question 10

What is the process of longshore drift?

Answer 10

• wave swash approaches the beach at a 45-degree angle (the same as the prevailing wind direction)
• this is in conditions where wave refraction is not complete
• backwash is at a 90-degree angle, due to gravity
• process repeats, moving sediment along the beach
• smaller material is transported further as it requires less energy

Question 11

How are materials moved in water?

Answer 11

• traction
• saltation
• suspension
• solution

Question 12

What is traction?

Answer 12

When large heavy material is dragged along the sea floor

Question 13

What is saltation?

Answer 13

When smaller material bounces along the sea floor

Question 14

What is suspension?

Answer 14

The fine material held in water, ‘suspended’

Question 15

What is solution

Answer 15

The dissolved material carried in the water

Question 16

What is the meaning of weathering

Answer 16

When rocks break down in situ

Question 17

What are the types of weathering?

Answer 17

• mechanical
• chemical
• biological

Question 18

What are processes of physical weathering?

Answer 18

• freeze-thaw
• salt crystal growth
• wetting and drying of clay rich rocks

Question 19

How does freeze-thaw work?

Answer 19

1. Water gets into cracks and joints in the rock
2. When the water freezes it expands and the cracks open a little wider
3. Over time, pieces of rock split off the rock face, whilst big boulders are broken into smaller rocks and gravel

Question 20

How does salt weathering work?

Answer 20

1. Water in cracks evaporates leaving salt crystals
2. The salt crystals expand and the cracks become larger
3. Over time, pieces of rock split off the rock face, whilst big boulders are broken into smaller rocks and gravel

Question 21

What are the processes of chemical weathering?

Answer 21

• carbonation
• oxidation
• acid rain
• usually impacts CaCO3 rocks

Question 22

How does chemical weathering generally work?

Answer 22

1. Rainwater is slightly acidic through absorbing carbon dioxide from the atmosphere
2. This reacts with minerals in the rock, creating new material
3. Rock type affects the rate of weathering eg limestones chemically weathers faster than granite
4. The warmer the temperature, the faster the chemical reaction

Question 23

What are the processes of biological weathering?

Answer 23

• plant roots
• burrowing animals
• nesting birds

Question 24

How does roots of plants break down rock?

Answer 24

1. Trees and plants grow in the crack of the rock formation
2. As the roots grow bigger, they push open crack sin the rocks, making them wider and deeper
3. Over time, the growing tree eventually forces the rock apart

Question 25

How does microorganisms weather rock?

Answer 25

1. Organisms like bacteria, algae and moss can grow on rocks 2. These produce chemicals that break down the surface layer of the rock

Question 26

How does burrowing animals weather down rocks?

Answer 26

1. Burrowing animals eg rabbits disturb the ground 2. This destabilizes the rock above the burrow 3. Increasing pressure on any cracks 4. Eventually pieces fall off the rock

Question 27

What is mass movement?

Answer 27

The downhill movement of material under the influence of gravity

Question 28

Types of mass movement…

Answer 28

- slumping - sliding

Question 29

What is slumping?

Answer 29

When the waves erode the cliff base and cause instability. Rainwater permeates thought eh rock, saturating it, until it becomes unstable and slumps along bedding planes. This leads to a stair-like appearance

Question 30

What is

Answer 30

When the waves erode the cliff base and cause instability. Rainwater permeates thought eh rock, saturating it, until it becomes unstable and slumps along bedding planes. This leads to a stair-like appearance

Question 31

What is sliding

Answer 31

When weathering loosens rock, which slides down off bedding planes. Leads to landslides and mudslides. Blocks of rock slides downhill

Question 32

What is geology

Answer 32

The study of rock type

Question 33

What is lithology

Answer 33

The study of characteristics of rock eg relative hardness, permeability etc

Question 34

What is discordant geology / coastline?

Answer 34

Rock outcrops are at 90 degrees to the sea, in alternating layers of hard and soft rock. This leads to headlands and bays.

Question 35

What is concordant geology/coastline?

Answer 35

Rock outcrops are parallel to the sea, ie only one type of rock along one coastline. Crates coves, eg Lulworth cove, Dorset

Question 36

What are bedding planes?

Answer 36

The change in sediment texture, structure and or composition, ie differnt type of rock in layers.

Question 37

How does vegetation influence the coast?

Answer 37

- biological weathering - can create sand dunes via encouraging deposition, and then stabilizing them - can protect and preserve coastal landforms by buffering and reducing wave energy (e.g. mangroves)

Question 38

How does sea level influence the coast?

Answer 38

- flooding, a huge issue associated with rising sea level, especially considering many urban areas are situated on the coast - saltwater incursion - creation of landforms (different dependent on whether sea levels are rising or falling - remember this is different in different parts of the world)

Question 39

What is isostatic readjustment?

Answer 39

When land level rises or falls relative to the sea, so it appears that sea level is falling or rising. - this leads to relict (old) landforms - emergent landforms (falling sea level) = raised beaches and cliffs - submerging landforms (rising sea level) = rias (drowned river valleys) and fjords (drowned glaciated valleys.