Coasts

Question 0

What is constructive wave?

Answer 0

• created in calm weather and less powerful than destructive wave.
• deposit material, building up beaches.
• Swash stronger than backwash.
• Long wavelength, low in height.

Question 1

What is constructive wave?

Answer 1

• Created by storm conditions.
• Stronger backwash and swash.
• short wave length that are high and steep.
• tend to edrode the coast.

Question 2

Define abrasion

Answer 2

Erosion by Bits of rock and sand in waves grind down cliff surfaces.

Question 3

Define hydraulic action

Answer 3

• Type of erosion happen when air is trapped in cracks on a cliff face.
• When waves break –> trapped air compressed –> weakens the cliff –> erosion

Question 4

Define Attition

Answer 4

Waves smash rocks on the shore into each other, the big rocks break and become smaller and smoother

Question 5

Define Solution erosion

Answer 5

When acids in sea water dissolve some types of rocks such as chalk or limestone

Question 6

What is coastal transport by solution?

Answer 6

• When minerals dissolved in sea water and carried in solution.
• Not visible.

Question 7

Coastal transport- suspension

Answer 7

• small particles are carried in water

- currents pick up large sediments in suspension during a storm.

Question 8

Coastal transport- Saltation

Answer 8

Load is bounced along the sea bed i.e: small pieces of shingle.
- currents can’t keep the larger and heavier sediments afloat for long period

Question 9

Coastal transportation- Traction

Answer 9

Pebbles and large sediments are rolled along the sea bed

Question 10

Describe formation of a bay and headland

Answer 10

Bay:
- alternative layers of hard of soft rock
- The sea erode soft rocks a lot quicker than the hard rock(less resistance).
- An indented area of land found between two headlands
- Wave energy is focused on the headlands because of refraction –> waves are weaker and it meets the bay –> constructive –> beach.
- More sheltered –> less erosive power –> beach
Headland
- Piece of land that sticks out into the sea.
- Hard rocks erode slower

Question 11

Formation of Wave cut notch and Wave cut platform

Answer 11

• high tides attack and erode the bottom of the cliff.
• Over time this created a wave cut noth and eorde hole at the bottom of the cliff –> notch
• Wave cut notch gets bigger –> weight of rock above the cliff gets greater –> cliff can’t supprt its own weight –> collapses.
• Process continues –> new wave cut notch –> Cliff retreats
• When cliff moves backwards (recession) –> wave cut platform is created (expansion of bare rocks)
  IT’S ONLY VISIBLE AT LOW TIDE.

Question 12

Describe 2 types of Coastal defences

Answer 12

Hard engineering:

• a physical structure (usually wood or concret) used to protect the coast.
• Effective
• Expenesive and ugly to look at

Soft engineering:

• Working with the nature
• Doesn’t ruin the look of the coastline
• Cheaper
• Can’t withstand strong storms

Question 13

Examples of hard engineering

Answer 13

• Rip rap: A giant boulder placed at the foot of the cliff –> absorbs wave energy to protect the cliff behind.
• Gabions: Large boulders placed in cage –> install quickly and effectively but reduce access to the sea.
• Groynes: Designed to stop longshore drift transporting beach material away. It causes problems down the coast because they will not receive beach material.
• Sea walls: concrete block to absorb wave energy.
• Break water: Built out into the sea, around the mouth of the rivers. It can disrupt shipping and animals.
• Revetments: Similar to sea walls, but built out of woods.