Coasts EQ2

Question 1

How are waves formed?

Answer 1

Friction between wind + water, energy from wind being transferred into water

Question 2

What 4 factors does wave size depend on?

Answer 2

1. Strength of wind
2. Wind duration
3. Wave depth
4. Wave fetch

Question 3

What way to waves move along?

Answer 3

Circular motion
Becomes elliptical due to friction on seabed

Question 4

What is fetch?

Answer 4

Uninterrupted distance across water over which a wind blows (distance waves have to grow in size)

Question 5

What are swell waves?

Answer 5

Wind that caused waves has dropped but remaining waves gradually make their way onshore

Question 6

How are waves affected by water depth?

Answer 6

Water depth half wave size= friction between wave + seabed slows wave down

Wave length decreases + wave height increase as approach shore

Question 7

Why do waves break in shallow waters?

Answer 7

Crest of the wave begins to move forward faster than wave trough

Question 8

What are constructive waves?

Answer 8

Waves with low wave height + long wave length

Question 9

What are the features of constructive waves?

Answer 9

• Strong swash
• Weak backwash
• Deposited sediment
• On gentle beach profile

Question 10

What are destructive waves?

Answer 10

Wave height of over 1m + wave length of 20m

Question 11

What are the features of destructive waves?

Answer 11

• Strong backwash (erodes beach materials + carried offshore)

Question 12

What is swash?

Answer 12

Flow of water up a beach as a wave breaks

Question 13

What is backwash?

Answer 13

Water runs back down the beach to meet the next incoming wave

Question 14

What can be found at high energy coastlines?

e.g. Bristol, SW Wales

Answer 14

• Destructive waves
• Headlands, crack, cave, arch, stack, stump
• Steep cliff

Question 15

What can be found at low energy coastlines?

e.g. Mediterranean

Answer 15

• Constructive waves
• Sandy beaches
• Sand dunes
• Spits/ bars
• Tombolo

Question 16

What is beach morphology?

Answer 16

Shape of the beach (width + slope) + features (berms/ ridges)
- Types of sediment found at different locations on beach

Question 17

What is clastic?

Answer 17

Broken down rock

Question 18

What is biogenic?

Answer 18

Remains of living organisms

Question 19

What changes can happen to beach profiles over a long period of time?

Answer 19

1. Sediment supply reduced
2. Coastal management added
3. Climate change

Question 20

When will most erosion occur?

Answer 20

1. Waves are at their highest
2. Wave approaches coast at 90° to cliff face
3. High tide
4. Heavy rainfall
5. Debris from previous erosion

Question 21

What does a summer beach look like?

Answer 21

• Berm in summer
• Constructive waves
• Depositional
• Tidal range dries out sand creating berm (object for dunes)

Question 22

What does a winter beach look like?

Answer 22

• Sediment removed
• Destructive waves
• Summer accumulation of sediment removed
• Backshore steepness

Question 23

What features are at the beach?

Answer 23

1. Berms + beach scarps
2. Storm beach
3. Ridges + runnels
4. Cusps

Question 24

What is hydraulic action (wave quarrying)?

Answer 24

• Air trapped in cracks + fissures compressed by force of waves crashing against cliff
• Pressure forces cracks open
• Dislodges blocks of rock from cliff face

Question 25

What are the influence of lithology in regard to hydraulic action?

Answer 25

- Heavily jointed/ fissured sedimentary

Question 26

What is abrasion (corrasion)?

Answer 26

- Sediment picked up by breaking waves thrown against cliff face - Sediment chisels away at surface + wears away

Question 27

What are the influences of lithology in regard to abrasion?

Answer 27

- Suitably loose sediment has to be available - Softer sedimentary rocks more vulnerable

Question 27

What is attrition?

Answer 27

- Acts on already eroded sediment - Sediment moved around waves + collide between particles chipping off sediment - Get smaller and rounder

Question 28

What are the influences of lithology in regard to attrition?

Answer 28

- Softer rock rapidly reduce in size

Question 29

What is corrosion (solution)?

Answer 29

- Limestone vulnerable by rainwater, seawater

Question 30

What are the influences of lithology in regard to corrosion?

Answer 30

- Limestone (vulnerable to solution by weak acids)

Question 31

How is a wave cut platform formed?

Answer 31

- Bottom of cliff eroded by hydraulic action + abrasion - Notch becomes deeper + overhanging rock becomes unstable + collapse

Question 32

What is a geo?

Answer 32

Narrow fault guided gullies

Question 33

What is a blow hole?

Answer 33

Forms when coastal cave turns upwards + breaks through flat cliff top

Question 34

How are tides formed?

Answer 34

Caused by combined gravitational pull of the moon + sun

Question 35

What is a neap tide?

Answer 35

Lowest tidal range - Minimal difference between low/ high tide - Moon is at right angles to Sun

Question 36

What is a spring tide?

Answer 36

Highest tidal range - Alignment of Sun + Moon

Question 37

What is erosion?

Answer 37

Breakdown of rock due the action of some external force which transports eroded material to new location