Coastal processes

Question 1

What does weathering mean?

Answer 1

Weathering is the breakdown of rocks in situ (where they are)

Question 2

What does erosion mean?

Answer 2

Erosion is when rocks are broken down and carried away by something

Question 3

What is mechanical weathering

Give an example

Answer 3

The breakdown of rock without chnaging its chemical composition

Freeze-thaw weathering

Question 4

Explain freeze thaw weathering

Answer 4

Water enters the rock that has cracks e.g granite
When the water freezes it expands which puts pressure on the rock
When the water thaws it contracts, which releases the pressure on the rock
Repeated freezing and thawing widens the cracks and causes the rock to break up

Question 5

When does freeze thaw weathering happen?

Answer 5

It happens when the temperature alternates above and below 0c (freezing point of water)

Question 6

What is chemical weathering ?

Answer 6

The breakdown of rock by changing its chemical composition

Question 7

When does carbonaion weathering take place?

Answer 7

A type of chemical weathering that happens in warm and wet conditions

Question 8

Explain carbonation weathering

Answer 8

Carbon dioxide can dissolve in the rain to create a weak ‘cabonic acid’
Carbonic acid reacts with rock that contains calcium carbonate and dissolves that bit
E.g. carboniferous limestone reacts with the rock and are dissolved

Question 9

What does fetch mean?

How is a wave more powerful

Answer 9

The distance the wind blows over the sea

The grater the fetch the more powerful wave

Question 10

Describe constructive waves

Answer 10

• They deposit material
• Not very tall (called calm sea)
• They have a low frequency and are low and long
• Their swash is more powerful then their backwash so the material is deposited
• The wave have longer wavelength than destructive waves

Question 11

What is swash and backwash

Answer 11

Swash is water moving up the beach

Backwash is water moving down the beach

Question 12

Describe destructive waves

Answer 12

• They erode the coast
• They have high frequency and are steep
• Their backwash is more powerful than their swash so material is removed
• They are really tall

Question 13

Abrasion

Process of erosion

Answer 13

Eroded particles in the water scrape and rub against the rock

Question 14

Hydraulic power

Process of erosion

Answer 14

Waves crash against rack and compress the air in the cracks. This puts pressure on the rock. Repeated compressions widens the cracks and causes bits of rock to fall of

Question 15

Attrition

Process of erosion

Answer 15

Eroded particles in the water collide break in smaller pieces and become more rounder

Question 16

What is mass movement?

Answer 16

When material falls down a slope
The shifiting of rock and lose material down a slope e.g. a cliff

Question 17

Why does mass movement happen ?

Answer 17

It happens when the force of gravity acting on a slope is greater than the force supporting it

Question 18

What does mass movement do and when is it more likely to happen

Answer 18

It causes coast to retreat rapidly
Its more likely to happen when the material is full of water - water acts as a lubricant and makes the material heavier
When the material shifts it can create a scrap (a steep ‘cut’ in the side of the slope)

Question 19

How is material transported along the coast

Answer 19

By longshore drift

Question 20

Explain the process of longshore drift

Answer 20

Waves follow the direction of prevailing (most common) wind
They usually hit the coast at an oblique angle (any angle that isn’t a right angle)
The swash carries that material up the beach in the same direction as the waves
The backwash then carries material up the beach at right angles back towards the see
Overtime material zig zags along the beach

Question 21

Traction

Answer 21

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

Question 22

Suspension

Answer 22

Small particles like slit and clay are carried along in the water

Question 23

Solution

Answer 23

Soluble materials (e.g limestone) dissolve in the water and are carried along

Question 24

Saltation

Answer 24

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

Question 25

What is deposition and when does it occur?

Answer 25

Deposition is the dropping of material
It occurs when water carrying sediment loses energy and slows down

Question 26

When do coasts build up ?

refer to deposition and erosion

Answer 26

When the amount of deposition is greater than the amount of erosion
The amount of material thats deposited on an area coast is increased when theres lots of erosion elsewhere on the coast (so more material is avaliable)
Lots of material is transported into the sea

Answer 27

Constructive waves drop more material than they remove - theres more deposition than erosion