Coasts- Coastal Processes

Question 1

What are the six main ways that waves wrote the coastline?

Answer 1

Corrasion
Hydraulic action
Cavitation
Wave quarrying
Solution
Attrition

Question 2

What is corrasion/ abrasion?

Answer 2

rocks smash and grind against one another and cliffs breaking bits off and smoothing surfaces

Question 3

What is hydraulic action?

Answer 3

Air in cracks in cliffs is compressed when waves crash in
Pressure exerted by compressed air breaks off rock pieces

Question 4

What is cavitation?

Answer 4

As waves recede, compressed air expands violently, again exerting pressure on the rock causing pieces to break off

Question 5

What is wave quarrying?

Answer 5

The energy of a wave as it breaks against a cliff is enough to detach bit of rock

Question 6

What is soloution/ corrosion?

Answer 6

Soluble rocks eg limestone, chalk get gradually dissolved by the seawater

Question 7

What is attrition?

Answer 7

Bits of rock in the water smash against each other and break into smaller bits

Question 8

What are the four ways material is transported at the coast?

Answer 8

Soloution
Suspension
Saltation
Traction

Question 9

What is soloution?

Answer 9

Substance that can dissolve are carried along in the water

Question 10

What is suspension?

Answer 10

Very fine material, such as slit and clay particles is whipped up by turbulence and carried along in the water
Most transported this way

Question 11

What is saltation?

Answer 11

Larger particles such as pebbles or gravel are too heavy to be carried in suspension. Instead the force of the water causes them to bounce along the sea bed

Question 12

What is traction?

Answer 12

Very large particles eg boulders are pushed along the sea bed by the force of the water

Question 13

Explain the process of long shore drift

Answer 13

Swash carries sediment up the beach, parallel to the prevailing wind.
Backwash carries sediment back down the beach at right angles to the shoreline
When there is an angle between the prevailing wind and the shoreline, a few rounds of swash and backwash move the sediment along the shoreline

Question 14

What is marine deposition?

Answer 14

When sediment carried by seawater is deposited

Question 15

What is aeolian deposition?

Answer 15

When sediment carried by the wind is deposited

Question 16

When do marine and aeolian deposition occur? And why?

Answer 16

When sediment load exceeds the ability of the water or wind to carry it
Can be because sediment load increase or because wind or water flow slows down

Question 17

Why do wind and water slow down?

Answer 17

Friction increases
Flow becomes turbulent

Question 18

How does an increase in friction slow down deposition?

Answer 18

Waves enter shallow water or wind reaches land, friction between the water/wind and ground surfaces increase which slows down the water oe wind

Question 19

How does flows becoming turbulent slow down deposition?

Answer 19

If water or wind encounter an obstacle, the flow becomes rougher and overall speed decreases

Question 20

What happens if the wind drops to deposition?

Answer 20

Wave height, speed and energy will decrease as well

Question 21

What is sub- aerial weathering?

Answer 21

The gradual break down of rocks by agents such as ice, salt, plant roots and acid

Question 22

Why is weathering bad for rock?

Answer 22

Weakens cliffs and makes them more vulnerable to erosion

Question 23

What are the four main types of weathering?

Answer 23

Salt weathering
Freeze- thaw weathering
Wetting and drying
Chemical weathering

Question 24

What is salt weathering?

Answer 24

-Cause by saline water
-Saline water enters prepare cracks in rock at high tide
-As the tide goes out the rocks dry an water evaporates, forming salt crystals
-As the salt crystals form they expand, exerting pressure on the rock causing pieces to fall off

Question 25

What is freeze- thaw weathering?

Answer 25

-occurs in areas where temperatures fluctuate above and below freezing -water enters the joints and crevices in rock -if the temperatures drop below 0degrees the water in the cracks freezes and expands -over time, repeated freeze- thaw action weakens the rock and causes pieces to fall off

Question 26

What is wetting and drying weathering?

Answer 26

Some rocks contain clay When clay gets wet it expands and the pressure caused by this breaks fragments off the rock causing pieces

Question 27

What is chemical weathering?

Answer 27

-Chemical weathering is the breakdown of rid by changing its chemical composition -eg co2 in the atmosphere dissolves in rainwater, forming a weak carbonic acid. This acid reacts with rock that contains calcium carbonate- so the rocks are gradually dissolved

Question 28

What is mass movement?

Answer 28

The shifting of material downhill due to gravity

Question 29

In coastal area, when is mass movement most likely to happen?

Answer 29

When cliffs are undercut by wave action which leave an unsupported hang which is likely to collapse

Question 30

What are the four types of mass movement?

Answer 30

Slides Slumps Rockfalls Mudflows

Question 31

What is a slide?

Answer 31

Material shifts in a straight line

Question 32

What is a slump?

Answer 32

Material shifts with a rotation

Question 33

What is rockfall?

Answer 33

Material breaks up and falls

Question 34

What is mudflows?

Answer 34

Material flows down the slope

Question 35

Why are unconsolidated rock prone to collapse?

Answer 35

As there is little friction between particles to hold them together

Question 36

What can make unconsolidated rock more prone to collapse due to lack of friction?

Answer 36

Heavy rain as it saturates the rock

Question 37

What does runoff do to fine particles?

Answer 37

Erodes them and transports them downslope