Coastal Landscapes

Question 1

Define coastal erosion

Answer 1

The breaking down and carrying away of materials by the sea.

Question 2

Define coastal deposition

Answer 2

When the sea drops the rock particles, sand and pebbles it has been carrying.

Question 3

What is hard engineering?

Answer 3

Man-made structures which are built to reduce the rate of erosion.

Question 4

What is soft engineering?

Answer 4

Schemes set up using the knowledge of coastal system and natural processes/resources to reduce the rate of erosion.

Question 5

State the differences between constructive and destructive waves.

Answer 5

Constructive wave:
* strong swash
* weak backwash
* low height
* low frequency
* long wavelength
* builds the beach (deposition)

Destructive waves:
* weak swash
* strong backwash
* high height
* high frequency
* short wavelength
* erodes the beach

Question 6

Define abrasion

Answer 6

Erodes particles in the water by scraping and rubbing against rock, removing the small pieces.

Question 7

Define attrition.

Answer 7

Materials carried by the waves collide into each other, breaking into smaller pieces and becomes more rounder and smoother.

Question 8

Define hydraulic action

Answer 8

Waves crash against rocks and compresses the air which puts pressure on them, which widens the crack and causes the rock to erode.

Question 9

Define solution

Answer 9

It’s the chemical action of the sea water where the acids in the salt water slowly dissolves rocks on the coast.

Question 10

Define weathering
What makes weathering different to erosion?

Answer 10

The break-up and decomposition of rocks in-situ.
It doesn’t involve the movement of materials, making it different from erosion.

Question 11

What is mechanical weathering?

Answer 11

It’s the breakdown of rocks caused by changes in temperatures without changing the chemical composition.

Question 12

What is biological weathering?

Answer 12

Caused by plants as they can grow in the rock cracks, forcing the crack to widen and the rock can break apart.

Question 13

What is chemical weathering?

Answer 13

Breakdown of rock by changing the chemical composition as rainwater (carbonic acid) and salt water can cause chemical change and dissolve rocks.

Question 14

Explain the process of Freeze-thaw weathering.

Answer 14

• Water enters the rock cracks and when the temp is low, the water freezes.
• As the water freezes, it puts pressure on the rock and expands the water, making the cracks wider.
• When the water thaws, it contracts, releasing the pressure on the rock
• Eventually the crack gets to wide, that the rock splits

Question 15

What is mass movement?

Answer 15

The movement of loose materials down slope due to gravity. occuring quickly and suddenly through slumping and sliding

Question 16

Mass movement

Explain how the rotational slip / slumping forms.

Answer 16

This occurs after a long period of rainfall.
* Rainwater seeps through permeable rocks (limestone) and makes them impermeable (clay)
* The saturated soil and weak rocks slump (like it’s melting down) down the hill in a rotational matter on a curved surface.

Don’t mention about melting in exam; it’s just to picture it

Question 17

Mass movement

Explain how to mud slide forms.

Answer 17

Occurs along the flat surface
* Rains slips in the permeable rocks, making them impermeable
* It causes the toplayer of soil and impermeable material to slide down the rock face rapidly.

Question 18

Mass movement

Explain how rockfall occurs.

Answer 18

It occurs suddenly.
* When piece of rock falls as the base of the rock was undercut and leaves the rock supported
* The mass of the rock becomes too much that it’s unable to support
* Due to the heavy masss, the rock collapses as gravity pulls it down.

Question 19

Mass movement

Explain how landslide occurs

Answer 19

When soil moves down the slope
* Due to the weathering, the rock chunks get cracked and borken down at te base of the cliff, forming a smaller landslide.
* A wave cut notch is formed and as it gets bigger, the weight of the cliff gets heavier, leading to a bigger landslide.
* Landslides gives a temporary protection to the rest of the rock and when it gets removedby the sea, the rock collapses.

Question 20

What determines the size of the winds?

Answer 20

• How strong the wind is
• how long the wind has been blowing for
• The distance the wind has travelled

Question 21

What the wave cut notch?

Answer 21

A repeated erosion which is focused at the base of the cliff (between low and high tides), causing it to repeadely collapse and therefore retreat, creating a wave - cut platform.

Question 22

Explain how to wave cut platform forms.

Answer 22

• Sea erodes the cliff material between the low and high tides by hydraulic action and abrasion
• This creates cracks in the cliff face and the destructive waves hitting the cliff face traps air in the cracks (cavitation)
• The acidic sea erodes the bottom of the cliff, creating a wave-cut notch
• This makes the top of the cliff unstable and unsupported, causing it to collapse and the materials falls on the wave-cut platform
• Overtime this process repeated continuously and retreats the cliff.

Question 23

Explain the four water transportation processes in order.

Answer 23

• Traction - large particles like boulders are pushed along the sea bed by the force of the water.
• Solution - soluble materials (limestone) dissolve in the sea and are carried along but the load is not visible, which can come from chalk, calcium carbonate.
• Saltation - pebble sized particles bounce along the sea bed due to the force of the water.
• Suspension - small particles are carried in the water (silt and clays), making the water look cloudy.

Question 24

What is the longshore drift?

Answer 24

The zigzag movement of sediment along a shore caused by the waves going up the beach at an oblique angle and backwash occurs at a right angle.

Question 25

Explain the process of longshore drift.

Answer 25

1) Waves follow the direction of the pravailing wind.
2) The waves hit the beach at an oblique angle which is the swash.
3) The swash carries the materials up the beach in the same direction of the waves.
4) The backwash carries the materials towards the sea at a right angle.
5) Over-time this zigzag movement moves sediment along the coast.

Question 26

What is coastal deposition?
When does it occur?

Answer 26

When the sea drops the sediment it has been carrying by constructive waves.
It occurs when the water carrying sediment loses energy and slows down.

Question 27

Give 3 reasons why coastal deposition can occur.

Answer 27

• waves enter an area of shallow water
• waves enter a sheltered area like cove or bay
• less wind
• river or estuary flows into the sea, reducing water energy
• due to good supply of maaterials, and the amount being trasnported is grather than how much the wave energy can trasnport.